Applied Sciences

Editorial

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5 pages, 197 KiB

Open AccessEditorial

Special Issue on “Sound and Music Computing”

by Tapio Lokki^1,*

, Meinard Müller², Stefania Serafin³ and Vesa Välimäki⁴

¹ Department of Computer Science, Aalto University, 02150 Espoo, Finland

² International Audio Laboratories Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

³ Department of Architecture, Design and Media Technology, Aalborg University, 2450 Copenhagen SV, Denmark

⁴ Department of Signal Processing and Acoustics, Aalto University, 02150 Espoo, Finland

Appl. Sci. 2018, 8(4), 518; https://doi.org/10.3390/app8040518 - 28 Mar 2018

Cited by 1 | Viewed by 4077

Abstract

Sound and music computing is a young and highly multidisciplinary research field. [...]
Full article

(This article belongs to the Special Issue Sound and Music Computing)

3 pages, 160 KiB

Open AccessEditorial

Microgrids for Productive Uses of Energy in the Developing World and Blockchain: A Promising Future

by George Kyriakarakos and George Papadakis^*

Department of Natural Resources Management and Agricultural Engineering, School of Agricultural Production, Infrastructure and Environment, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens, Greece

Appl. Sci. 2018, 8(4), 580; https://doi.org/10.3390/app8040580 - 8 Apr 2018

Cited by 24 | Viewed by 4588

Abstract

Currently, 1.06 billion people still do not have access to electricity, with the majority living in rural areas around the world[...] Full article

(This article belongs to the Section Energy Science and Technology)

3 pages, 184 KiB

Open AccessEditorial

Advanced Paving Materials and Technologies

by Zhanping You^1,*

, Qingli Dai¹ and Feipeng Xiao²

¹ Department of Civil and Environmental Engineering, Michigan Technological University, Houghton 49931, MI, USA

² Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, Shanghai 200000, China

Appl. Sci. 2018, 8(4), 588; https://doi.org/10.3390/app8040588 - 9 Apr 2018

Cited by 4 | Viewed by 3466

Abstract

n/a Full article

(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)

Research

Jump to: Editorial, Review

10 pages, 7194 KiB

Open AccessArticle

Neuroprotective Investigation of Chitosan Nanoparticles for Dopamine Delivery

by Andrea Ragusa^1,2,*

, Paola Priore², Anna Maria Giudetti³

, Giuseppe Ciccarella^2,4

and Antonio Gaballo^2,*

¹ Department of Engineering for Innovation, University of Salento, via Monteroni, 73100 Lecce, Italy

² CNR Nanotec, Institute of Nanotechnology, via Monteroni, 73100 Lecce, Italy

³ Department of Biological and Environmental Sciences and Technologies, University of Salento, via Monteroni, 73100 Lecce, Italy

⁴ Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento & UdR INSTM di Lecce, c/o Campus Ecotekne, Via Monteroni, 73100 Lecce, Italy

Appl. Sci. 2018, 8(4), 474; https://doi.org/10.3390/app8040474 - 21 Mar 2018

Cited by 30 | Viewed by 5394

Abstract

Chitosan nanoparticles (CS NPs) have been widely exploited for the delivery of various types of drugs due to their biocompatibility, availability, ease of functionalization and other advantages. Nevertheless, despite their wide use, their mechanism of action is not very clear and many aspects [...] Read more.

Chitosan nanoparticles (CS NPs) have been widely exploited for the delivery of various types of drugs due to their biocompatibility, availability, ease of functionalization and other advantages. Nevertheless, despite their wide use, their mechanism of action is not very clear and many aspects still need to be investigated in detail, with only a few studies having studied the behavior of this polymer. We prepared CS NPs encapsulating dopamine (DA) and studied the generation of reactive oxygen species (ROS) and the antioxidant effect of the neurotransmitter in detail. Encapsulation of the drug and its subsequent sustained release significantly reduced the oxidation rate in vitro, thus potentially exerting neuroprotective effects. ROS production in SH-SY5Y cells was investigated through a H₂O₂ assay, while a deeper study of the enzymatic activity allowed us to determine the significant contribution of both GPx and SOD enzymes in preventing oxidative stress. Full article

(This article belongs to the Special Issue Eco-Friendly Nanocomposites for Biomedical Applications)

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18 pages, 5731 KiB

Open AccessArticle

Initial Results of Testing a Multilayer Laser Scanner in a Collision Avoidance System for Light Rail Vehicles

by Murat Lüy¹

, Ertuğrul Çam¹

, Faruk Ulamış^2,*, İbrahim Uzun³ and Salih İbrahim Akın⁴

¹ Department of Electrical and Electronics Engineering, Kirikkale University, 71450 Kirikkale, Turkey

² Hacilar Huseyin Aytemiz Vocational High School, Kirikkale University, 71480 Kirikkale, Turkey

³ Department of Mechanical Engineering, Kirikkale University, 71450 Kirikkale, Turkey

⁴ R&D Department of Durmazlar Machine Inc., 16140 Bursa, Turkey

Appl. Sci. 2018, 8(4), 475; https://doi.org/10.3390/app8040475 - 21 Mar 2018

Cited by 21 | Viewed by 4570

Abstract

This paper presents an application to detect and track obstacles using a multilayer laser scanner. The goal of the detection system is to develop collision avoidance for the Light Rail Vehicle (LRV). The laser scanner, which is mounted in front of the tram, [...] Read more.

This paper presents an application to detect and track obstacles using a multilayer laser scanner. The goal of the detection system is to develop collision avoidance for the Light Rail Vehicle (LRV). The laser scanner, which is mounted in front of the tram, collects information in a four-scan plane. The object recognition and tracking module, which is composed of a three sub-modules segmentation, classification, and Kalman Filter tracking, was carried out on the raw data. Thus, data were provided for collision avoidance module. The proposed system was applied to a tram named “Silkworm” which is manufactured by Durmazlar Machine Inc. (Bursa, Turkey) and initial experimental tests have been conducted at the facilities of Durmazlar Machine Inc. in the city of Bursa, Turkey. This study aims to illustrate parts of the possible tests that can be carried out and to share with the scientific community an important application of multilayer laser scanners, although in the initial implementation phase, in urban rail transportation. Full article

(This article belongs to the Special Issue Laser Scanning)

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17 pages, 3320 KiB

Open AccessFeature PaperArticle

Biomass District Heating Systems Based on Agriculture Residues

by Víctor M. Soltero^1,*

, Ricardo Chacartegui²

, Carlos Ortiz³

, Jesús Lizana⁴ and Gonzalo Quirosa¹

¹ Department of Design Engineering, University of Seville, 41011 Seville, Spain

² Department of Energy Engineering, University of Seville, 41092 Seville, Spain

³ Department of Electronic and Electromagnetism, University of Seville, 41012 Seville, Spain

⁴ Department of Building Construction, University of Seville, 41012 Seville, Spain

Appl. Sci. 2018, 8(4), 476; https://doi.org/10.3390/app8040476 - 21 Mar 2018

Cited by 21 | Viewed by 5972

Abstract

This paper presents a methodology for analyzing the regional potential for developing biomass district heating systems combining forestry biomass and agriculture residues as fuel. As a case study, this methodology is applied to the continental region of Spain. With this analysis the potential [...] Read more.

This paper presents a methodology for analyzing the regional potential for developing biomass district heating systems combining forestry biomass and agriculture residues as fuel. As a case study, this methodology is applied to the continental region of Spain. With this analysis the potential for the implementation of biomass district heating systems based on the use of agriculture residues is applied to 501 rural municipalities in Spain. The renewable forestry biomass and agriculture residues resources availability is analyzed and the biomass required for heating is assessed. The results of applying the methodology show the interest of the combination of biomass sources in a relevant number of municipalities with estimated Internal Rate of Return (IRR) values above 10% and for the analyzed region an IRR mean value of 4.3%. Full article

(This article belongs to the Special Issue Simulation, Analysis, Optimization and New Challenges of District Heating and Cooling Networks)

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11 pages, 7900 KiB

Open AccessArticle

Accurate Models for Evaluating the Direct Conducted and Radiated Emissions from Integrated Circuits

by Domenico Capriglione¹, Andrea G. Chiariello²

and Antonio Maffucci^3,*

¹ Department of Industrial Engineering, University of Salerno, Campus di Fisciano, 84084 Fisciano, Italy

² Department of Engineering, University della Campania L. Vanvitelli, Via Roma 29, 81031 Aversa, Italy

³ Department of Electrical and Information Engineering, University of Cassino and Southern Lazio, via G. Di Biasio 43, 03043 Cassino, Italy

Appl. Sci. 2018, 8(4), 477; https://doi.org/10.3390/app8040477 - 21 Mar 2018

Cited by 13 | Viewed by 5474

Abstract

This paper deals with the electromagnetic compatibility (EMC) issues related to the direct and radiated emissions from a high-speed integrated circuits (ICs). These emissions are evaluated here by means of circuital and electromagnetic models. As for the conducted emission, an equivalent circuit model [...] Read more.

This paper deals with the electromagnetic compatibility (EMC) issues related to the direct and radiated emissions from a high-speed integrated circuits (ICs). These emissions are evaluated here by means of circuital and electromagnetic models. As for the conducted emission, an equivalent circuit model is derived to describe the IC and the effect of its loads (package, printed circuit board, decaps, etc.), based on the Integrated Circuit Emission Model template (ICEM). As for the radiated emission, an electromagnetic model is proposed, based on the superposition of the fields generated in the far field region by the loop currents flowing into the IC and the package pins. A custom experimental setup is designed for validating the models. Specifically, for the radiated emission measurement, a custom test board is designed and realized, able to highlight the contribution of the direct emission from the IC, usually hidden by the indirect emission coming from the printed circuit board. Measurements of the package currents and of the far-field emitted fields are carried out, providing a satisfactory agreement with the model predictions. Full article

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13 pages, 7772 KiB

Open AccessArticle

Deep Activation Pooling for Blind Image Quality Assessment

by Zhong Zhang^1,2,*

, Hong Wang^1,2, Shuang Liu^1,2 and Tariq S. Durrani³

¹ Tianjin Key Laboratory of Wireless Mobile Communications and Power Transmission, Tianjin Normal University, Tianjin 300387, China

² College of Electronic and Communication Engineering, Tianjin Normal University, Tianjin 300387, China

³ Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow Scotland G1 1XQ , UK

Appl. Sci. 2018, 8(4), 478; https://doi.org/10.3390/app8040478 - 21 Mar 2018

Cited by 10 | Viewed by 4240

Abstract

Driven by the rapid development of digital imaging and network technologies, the opinion-unaware blind image quality assessment (BIQA) method has become an important yet very challenging task. In this paper, we design an effective novel scheme for opinion-unaware BIQA. We first utilize the [...] Read more.

Driven by the rapid development of digital imaging and network technologies, the opinion-unaware blind image quality assessment (BIQA) method has become an important yet very challenging task. In this paper, we design an effective novel scheme for opinion-unaware BIQA. We first utilize the convolutional maps to select high-contrast patches, and then we utilize these selected patches of pristine images to train a pristine multivariate Gaussian (PMVG) model. In the test stage, each high-contrast patch is fitted by a test MVG (TMVG) model, and the local quality score is obtained by comparing with the PMVG. Finally, we propose the deep activation pooling (DAP) to automatically emphasize the more important scores and suppress the less important ones so as to obtain the overall image quality score. We verify the proposed method on two widely used databases, that is, the computational and subjective image quality (CSIQ) and the laboratory for image and video engineering (LIVE) databases, and the experimental results demonstrate that the proposed method achieves better results than the state-of-the-art methods. Full article

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23 pages, 20076 KiB

Open AccessArticle

Seismic Response of a Three-Dimensional Asymmetric Multi-Storey Reinforced Concrete Structure

by Hyun-Kyu Lim¹, Jun Won Kang^1,*

, Hongrak Pak¹

, Ho-Seok Chi², Young-Geun Lee² and Janghwan Kim³

¹ Department of Civil Engineering, Hongik University, Seoul 04066, Korea

² Department of Structural Systems & Site Safety Evaluation, Korea Institute of Nuclear Safety, Daejeon 34142, Korea

³ Daelim Industrial Corporation Ltd., Seoul 03152, Korea

Appl. Sci. 2018, 8(4), 479; https://doi.org/10.3390/app8040479 - 22 Mar 2018

Cited by 12 | Viewed by 5481

Abstract

This study discusses the seismic behavior of a geometrically asymmetric three-storey reinforced concrete (RC) building, considering torsional effect and material nonlinearity. The building is a test structure that was used for seismic performance evaluation in the SMART 2013 (Seismic design and best-estimate Methods [...] Read more.

This study discusses the seismic behavior of a geometrically asymmetric three-storey reinforced concrete (RC) building, considering torsional effect and material nonlinearity. The building is a test structure that was used for seismic performance evaluation in the SMART 2013 (Seismic design and best-estimate Methods Assessment for Reinforced concrete buildings subjected to Torsion and nonlinear effects) international benchmark. To begin with, nonlinear stress–strain relationships that were set up for concrete and reinforcing steel are validated by finite element local tests with a representative volume element. A modal analysis shows that the first three calculated natural frequencies are close to the ones that are obtained by modal experiments. The finite element modeling is further validated by comparing the calculated displacement and acceleration due to a low-intensity ground motion with the responses from the corresponding shaking table test. Using the validated model, a blind nonlinear seismic analysis is performed for a series of Northridge earthquakes in order to estimate the behavior of the asymmetric RC structure to high-intensity ground motions. The calculated displacement and acceleration, as well as their response spectra at various sampling points, agree well with the results of a three-dimensional benchmark shaking table test. By investigating the seismic torsional behavior of the asymmetric RC structure, it is shown that the seismic response of an asymmetric structure is larger than that of a hypothetical symmetric structure. The result indicates that a larger seismic response should be considered in the seismic design of an asymmetric structure compared to a symmetric structure with similar design conditions. Full article

(This article belongs to the Section Mechanical Engineering)

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13 pages, 3810 KiB

Open AccessArticle

Ca/Si and Si/Al Ratios of Metakaolinite-Based Wastes: Their Influence on Mineralogy and Mechanical Strengths

by Rosario García-Giménez^1,*

, Moisés Frias²

, Raquel Vigil de la Villa¹ and Sagrario Martínez-Ramírez³

¹ Departamento de Geología y Geoquímica, Unidad Asociada Geomateriales CSIC-UAM, Facultad de Ciencias, Universidad Autónoma, 28049 Madrid, Spain

² Eduardo Torroja Institute (CSIC), 28033 Madrid, Spain

³ Institute for the Structure of Matter (IEM-CSIC), 28006 Madrid, Spain

Appl. Sci. 2018, 8(4), 480; https://doi.org/10.3390/app8040480 - 22 Mar 2018

Cited by 8 | Viewed by 3603

Abstract

Kaolinite-based wastes are researched as an alternative means of extracting metakaolinite, a pozzolanic product for the manufacture of eco-efficient cements. However, both crystallinity and the content of this crystalline phase play important roles during their thermal activation and, therefore, in their subsequent behavior [...] Read more.

Kaolinite-based wastes are researched as an alternative means of extracting metakaolinite, a pozzolanic product for the manufacture of eco-efficient cements. However, both crystallinity and the content of this crystalline phase play important roles during their thermal activation and, therefore, in their subsequent behavior in the matrix with cementitious properties. In this study, the initial compositions of two thermally activated products (paper sludge and coal waste) are studied for both the mineralogy and the mechanical properties of binary cements. The elemental composition of the materials was analyzed with X-ray Fluorescence (XRF). The mineralogy of the crystalline materials was determined by X-ray Diffraction (XRD). The sample morphology was determined with scanning electron microscopy (SEM). The pozzolanic activity is measured by accelerated methods and the preparation of the specimens of blended cement is prepared following the procedure described by Kock-Steinegger. The results showed that the pozzolanic activity of the waste (in terms of fixed lime) was similar at 90 days but that its reaction rate was different. The pozzolanic reaction of both wastes produced stratlingite and C-S-H gels, with the presence of C₄AH₁₃. The C-S-H gel generated with coal waste had very short chains, was poorer in Ca and was rich in Al. The addition of both wastes to the cement modified its mineralogical composition in comparison with a conventional cement, favoring the formation of C₄AH₁₃ over the formation of ettringite. Full article

(This article belongs to the Section Materials Science and Engineering)

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23 pages, 99925 KiB

Open AccessArticle

The Multiple-Update-Infill Sampling Method Using Minimum Energy Design for Sequential Surrogate Modeling

by Yongmoon Hwang¹, Sang-Lyul Cha¹, Sehoon Kim², Seung-Seop Jin^1,*

and Hyung-Jo Jung^1,*

¹ Department of Civil & Environmental Engineering, KAIST, DaeJeon 34141, Korea

² Department of Civil & Environmental Engineering, Sejong University, Seoul 05006, Korea

Appl. Sci. 2018, 8(4), 481; https://doi.org/10.3390/app8040481 - 22 Mar 2018

Cited by 3 | Viewed by 4111

Abstract

Computer experiments are widely used to evaluate the performance and reliability of engineering systems with the lowest possible time and cost. Sometimes, a high-fidelity model is required to ensure predictive accuracy; this becomes computationally intensive when many computational analyses are required (for example, [...] Read more.

Computer experiments are widely used to evaluate the performance and reliability of engineering systems with the lowest possible time and cost. Sometimes, a high-fidelity model is required to ensure predictive accuracy; this becomes computationally intensive when many computational analyses are required (for example, inverse analysis or uncertainty analysis). In this context, a surrogate model can play a valuable role in addressing computational issues. Surrogate models are fast approximations of high-fidelity models. One efficient way for surrogate modeling is the sequential sampling (SS) method. The SS method sequentially adds samples to refine the surrogate model. This paper proposes a multiple-update-infill sampling method using a minimum energy design to improve the global quality of the surrogate model. The minimum energy design was recently developed for global optimization to find multiple optima. The proposed method was evaluated with other multiple-update-infill sampling methods in terms of convergence, accuracy, sampling efficiency, and computational cost. Full article

(This article belongs to the Section Mechanical Engineering)

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17 pages, 3142 KiB

Open AccessArticle

The Rotating Flow of Magneto Hydrodynamic Carbon Nanotubes over a Stretching Sheet with the Impact of Non-Linear Thermal Radiation and Heat Generation/Absorption

by Sher Muhammad^1,2, Gohar Ali¹, Zahir Shah^3,4,*

, Saeed Islam³

and Syed Asif Hussain^1,2

¹ Department of Mathematics, Islamia College, Peshawar 25000, KP, Pakistan

² Department of Mathematics, Cecos University of Information Technology & Emerging Science, Peshawar 25000, KP, Pakistan

³ Department of Mathematics, Abdul Wali Khan University, Mardan 23200, KP, Pakistan

⁴ Gandhara Institute of Science & Technology, South Canal Road, Peshawar 2500, KP, Pakistan

Appl. Sci. 2018, 8(4), 482; https://doi.org/10.3390/app8040482 - 22 Mar 2018

Cited by 70 | Viewed by 6193

Abstract

The aim of this research work is to investigate the innovative concept of magnetohydrodynamic (MHD) three-dimensional rotational flow of nanoparticles (single-walled carbon nanotubes and multi-walled carbon nanotubes). This flow occurs in the presence of non-linear thermal radiation along with heat generation or absorption [...] Read more.

The aim of this research work is to investigate the innovative concept of magnetohydrodynamic (MHD) three-dimensional rotational flow of nanoparticles (single-walled carbon nanotubes and multi-walled carbon nanotubes). This flow occurs in the presence of non-linear thermal radiation along with heat generation or absorption based on the Casson fluid model over a stretching sheet. Three common types of liquids (water, engine oil, and kerosene oil) are proposed as a base liquid for these carbon nanotubes (CNTs). The formulation of the problem is based upon the basic equation of the Casson fluid model to describe the non-Newtonian behavior. By implementing the suitable non-dimensional conditions, the model system of equations is altered to provide an appropriate non-dimensional nature. The extremely productive Homotopy Asymptotic Method (HAM) is developed to solve the model equations for velocity and temperature distributions, and a graphical presentation is provided. The influences of conspicuous physical variables on the velocity and temperature distributions are described and discussed using graphs. Moreover, skin fraction coefficient and heat transfer rate (Nusselt number) are tabulated for several values of relevant variables. For ease of comprehension, physical representations of embedded parameters such as radiation parameter

(R d)

, magnetic parameter

(M)

, rotation parameter (

K

), Prandtl number (

P r

), Biot number

(λ)

, and heat generation or absorption parameter

(Q_{h})

are plotted and deliberated graphically. Full article

(This article belongs to the Special Issue Multi-Walled Carbon Nanotubes)

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13 pages, 2040 KiB

Open AccessArticle

A Stability Analysis on Mixed Convection Boundary Layer Flow along a Permeable Vertical Cylinder in a Porous Medium Filled with a Nanofluid and Thermal Radiation

by Shahirah Abu Bakar¹, Norihan Md Arifin^1,2,*

, Fadzilah Md Ali^1,2, Norfifah Bachok^1,2, Roslinda Nazar³ and Ioan Pop⁴

¹ Institute for Mathematical Research, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia

² Department of Mathematics, Faculty of Science, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia

³ School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysia

⁴ Department of Mathematics, Babes-Bolyai University, Cluj-Napoca R-400084, Romania

Appl. Sci. 2018, 8(4), 483; https://doi.org/10.3390/app8040483 - 23 Mar 2018

Cited by 34 | Viewed by 4432

Abstract

A study on mixed convection boundary layer flow with thermal radiation and nanofluid over a permeable vertical cylinder lodged in a porous medium is performed in this current research by considering groupings of a variety nanoparticles, consisting of copper (Cu), aluminium (Al₂ [...] Read more.

A study on mixed convection boundary layer flow with thermal radiation and nanofluid over a permeable vertical cylinder lodged in a porous medium is performed in this current research by considering groupings of a variety nanoparticles, consisting of copper (Cu), aluminium (Al₂O₃) and titanium (TiO₂). By using a method of similarity transformation, a governing set of ordinary differential equations has been reduced from the governing system of nonlinear partial differential equations, which are the values of selected parameters such as mixed convection parameter

λ

, nanoparticle volume fraction

φ

, radiation parameter Rd, suction parameter S, and curvature parameter

ξ

are solved numerically. From the numerical results, we observed that the involving of certain parameters ranges lead to the two different branches of solutions. We then performed a stability analysis by a bvp4c function (boundary value problem with fourth-order accuracy) to determine the most stable solution between these dual branches and the respective solutions. The features have been discussed in detail. Full article

(This article belongs to the Special Issue Nanofluids and Their Applications)

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13 pages, 5356 KiB

Open AccessArticle

High-Performance Asymmetric Supercapacitors Based on the Surfactant/Ionic Liquid Complex Intercalated Reduced Graphene Oxide Composites

by Jun-Hong Lin^*, Bo-Wen Shi and Zhao-Cheng Chen

Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan

Appl. Sci. 2018, 8(4), 484; https://doi.org/10.3390/app8040484 - 23 Mar 2018

Cited by 8 | Viewed by 4920

Abstract

In this paper, ionic surfactants are employed to intercalate thermally-reduced graphene oxide (TRG). The ionic interaction between the intercalated surfactant and the ionic liquid could lead to the formation of large-sized ionic aggregates and, hence, enlarge the interlayer distance between the TRG sheets. [...] Read more.

In this paper, ionic surfactants are employed to intercalate thermally-reduced graphene oxide (TRG). The ionic interaction between the intercalated surfactant and the ionic liquid could lead to the formation of large-sized ionic aggregates and, hence, enlarge the interlayer distance between the TRG sheets. The morphology and vibration modes of these composites were systematically characterized using XRD (X-ray diffraction), SAXS (small-angle X-ray scattering), and FTIR (Fourier transform infrared spectroscopy). An asymmetric supercapacitor, which consisted of a cationic surfactant-intercalated electrode on one side and an anionic surfactant-intercalated electrode on the other, was examined. It was found that, with the increased interlayer distance, the energy density and capacitance of the cells were improved. It seems that the cell with a cationic surfactant as the cathode had the best energy density of 67.8 Wh/kg, which is 4.4-fold higher than that of the TRG cell. Full article

(This article belongs to the Special Issue Supercapacitor Energy Storage Systems: Technology, Performance and Applications)

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12 pages, 3006 KiB

Open AccessArticle

Raman Imaging for the Detection of Adulterants in Paprika Powder: A Comparison of Data Analysis Methods

by Santosh Lohumi¹, Hoonsoo Lee², Moon Sung Kim², Jianwei Qin² and Byoung-Kwan Cho^1,*

¹ Department of Biosystems Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Korea

² Environmental Microbiology and Food Safety Laboratory, Agricultural Research Services, U.S. Department of Agriculture, 10300 Baltimore Avenue, Bldg 303 BARC-East, Beltsville, MD 20705, USA

Appl. Sci. 2018, 8(4), 485; https://doi.org/10.3390/app8040485 - 23 Mar 2018

Cited by 10 | Viewed by 4591

Abstract

Raman imaging requires the effective extraction of chemical information from the corresponding datasets, which can be achieved by a range of analytical methods. However, since each of these methods exhibits both strengths and weaknesses, we herein directly compare univariate, bivariate, and multivariate analyses [...] Read more.

Raman imaging requires the effective extraction of chemical information from the corresponding datasets, which can be achieved by a range of analytical methods. However, since each of these methods exhibits both strengths and weaknesses, we herein directly compare univariate, bivariate, and multivariate analyses of Raman imaging data by evaluating their performance in the quantitation of two adulterants in paprika powder. Univariate and bivariate models were developed based on the spectral features of the target adulterants, whereas spectral angle mapper (SAM), adopted as a multivariate analysis method, utilized the complete dataset. The obtained results demonstrate that despite being simple and easily implementable, the univariate method affords false positive pixels in the presence of background noise. Luckily, the above problem can be easily resolved using the bivariate method, which utilizes the multiplication of two band images wherein the same adulterant shows high-intensity peaks exhibiting the least overlap with those of other sample constituents. Finally, images produced by SAM contain abundant false negative pixels of adulterants, particularly for low-concentration samples. Notably, the bivariate method affords results closely matching the theoretical adulterant content, exhibiting the advantages of using non-complex data (only two bands are utilized) and being well suited to online applications of Raman imaging in the agro-food sector. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

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15 pages, 11941 KiB

Open AccessArticle

Spatial Coherence of Backscattered Signals in Multi-Line Transmit Ultrasound Imaging and Its Effect on Short-Lag Filtered-Delay Multiply and Sum Beamforming

by Giulia Matrone^1,2,*

and Alessandro Ramalli^3,4

¹ Department of Electrical, Computer and Biomedical Engineering, University of Pavia, 27100 Pavia, Italy

² Centre for Health Technologies, University of Pavia, 27100 Pavia, Italy

³ Laboratory on Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium

⁴ Department of Information Engineering, University of Florence, 50139 Florence, Italy

Appl. Sci. 2018, 8(4), 486; https://doi.org/10.3390/app8040486 - 23 Mar 2018

Cited by 35 | Viewed by 5764

Abstract

In Multi-Line Transmission (MLT), high frame-rate ultrasound imaging is achieved by the simultaneous transmission of multiple focused beams along different directions, which unfortunately generates unwanted artifacts in the image due to inter-beam crosstalk. The Filtered-Delay Multiply and Sum (F-DMAS) beamformer, a non-linear spatial-coherence [...] Read more.

In Multi-Line Transmission (MLT), high frame-rate ultrasound imaging is achieved by the simultaneous transmission of multiple focused beams along different directions, which unfortunately generates unwanted artifacts in the image due to inter-beam crosstalk. The Filtered-Delay Multiply and Sum (F-DMAS) beamformer, a non-linear spatial-coherence (SC)-based algorithm, was demonstrated to successfully reduce such artifacts, improving the spatial resolution at the same time. In this paper, we aim to provide further insights on the working principle and performance of F-DMAS beamforming in MLT imaging. First, we carry out an analytical study to analyze the behavior and trend of backscattered signals SC in MLT images, when the number of simultaneously transmitted beams and/or their angular spacing change. We then reconsider the F-DMAS algorithm proposing the “short-lag F-DMAS” formulation, in order to limit the maximum lag of signals used for the SC computation on which the beamformer is based. Therefore, we investigate in simulations how the performance of short-lag F-DMAS varies along with the maximum lag in the different MLT configurations considered. Finally, we establish a relation between the obtained results and the signals SC trend. Full article

(This article belongs to the Special Issue Ultrasound B-mode Imaging: Beamforming and Image Formation Techniques)

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19 pages, 1470 KiB

Open AccessFeature PaperArticle

Viscoelastic Behavior of Polymer-Modified Cement Pastes: Insight from Downscaling Short-Term Macroscopic Creep Tests by Means of Multiscale Modeling

by Luise Göbel^1,2,*,†, Markus Königsberger^2,3

, Andrea Osburg¹

and Bernhard Pichler²

¹ F.A. Finger-Institute for Building Material Engineering, Bauhaus-Universität Weimar, 99423 Weimar, Germany

² Institute for Mechanics of Materials and Structures, TU Wien—Vienna University of Technology, 1040 Vienna, Austria

³ BATir Department, Université libre de Bruxelles (ULB), 1050 Bruxelles, Belgium

^† Current address: Coudraystraße 11 A, 99423 Weimar, Germany.

Appl. Sci. 2018, 8(4), 487; https://doi.org/10.3390/app8040487 - 23 Mar 2018

Cited by 15 | Viewed by 5801

Abstract

Adding polymers to cementitious materials improves their workability and impermeability, but also increases their creep activity. In the present paper, the creep behavior of polymer-modified cement pastes is analyzed based on macroscopic creep tests and a multiscale model. The continuum micromechanics model allows [...] Read more.

Adding polymers to cementitious materials improves their workability and impermeability, but also increases their creep activity. In the present paper, the creep behavior of polymer-modified cement pastes is analyzed based on macroscopic creep tests and a multiscale model. The continuum micromechanics model allows for “downscaling” the results of macroscopic hourly-repeated ultra-short creep experiments to the viscoelastic behavior of micron-sized hydration products and polymer particles. This way, the increased creep activity of polymer-modified cement pastes is traced back to an isochoric power-law-type creep behavior of the polymers. The shear creep modulus of the polymers is found (i) to be two orders of magnitude smaller than that of the hydrates and (ii) to increase considerably with increasing material age. The latter result suggests that the creep activity of the polymers decreases with the self-desiccation-related decrease of the relative humidity inside the air-filled pores of cement paste. Furthermore, its decrease is most likely related to the penetration of cementitious hydrates into compliant polymer agglomerates. Full article

(This article belongs to the Special Issue Modelling of Early Age Cracking Risks and Serviceability of Concrete Structures)

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16 pages, 2023 KiB

Open AccessArticle

Modeling Restrained Shrinkage Induced Cracking in Concrete Rings Using the Thick Level Set Approach

by Rebecca Nakhoul^* and Olivier Pierard

CENAERO, Computational Multiphysics Software Development Team, Bâtiment Eole, 29 rues des Frères Wright, B-6041 Gosselies, Belgium

Appl. Sci. 2018, 8(4), 488; https://doi.org/10.3390/app8040488 - 23 Mar 2018

Cited by 2 | Viewed by 3773

Abstract

Modeling restrained shrinkage-induced damage and cracking in concrete is addressed herein. The novel Thick Level Set (TLS) damage growth and crack propagation model is used and adapted by introducing shrinkage contribution into the formulation. The TLS capacity to predict damage evolution, crack initiation [...] Read more.

Modeling restrained shrinkage-induced damage and cracking in concrete is addressed herein. The novel Thick Level Set (TLS) damage growth and crack propagation model is used and adapted by introducing shrinkage contribution into the formulation. The TLS capacity to predict damage evolution, crack initiation and growth triggered by restrained shrinkage in absence of external loads is evaluated. A study dealing with shrinkage-induced cracking in elliptical concrete rings is presented herein. Key results such as the effect of rings oblateness on stress distribution and critical shrinkage strain needed to initiate damage are highlighted. In addition, crack positions are compared to those observed in experiments and are found satisfactory. Full article

(This article belongs to the Special Issue Modelling of Early Age Cracking Risks and Serviceability of Concrete Structures)

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29 pages, 515 KiB

Open AccessFeature PaperArticle

Computational Accountability in MAS Organizations with ADOPT

by Matteo Baldoni^*,†

, Cristina Baroglio^†

, Katherine M. May^†, Roberto Micalizio^†

and Stefano Tedeschi^†

¹ Dipartimento di Informatica, Università degli Studi di Torino, via Pessinetto 12, I10149 Torino, Italy

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 489; https://doi.org/10.3390/app8040489 - 23 Mar 2018

Cited by 25 | Viewed by 4431

Abstract

This work studies how the notion of accountability can play a key role in the design and realization of distributed systems that are open and that involve autonomous agents that should harmonize their own goals with the organizational goals. The socio–technical systems that [...] Read more.

This work studies how the notion of accountability can play a key role in the design and realization of distributed systems that are open and that involve autonomous agents that should harmonize their own goals with the organizational goals. The socio–technical systems that support the work inside human companies and organizations are examples of such systems. The approach that is proposed in order to pursue this purpose is set in the context of multiagent systems organizations, and relies on an explicit specification of relationships among the involved agents for capturing who is accountable to whom and for what. Such accountability relationships are created along with the agents’ operations and interactions in a shared environment. In order to guarantee accountability as a design property of the system, a specific interaction protocol is suggested. Properties of this protocol are verified, and a case study is provided consisting of an actual implementation. Finally, we discuss the impact on real-world application domains and trace possible evolutions of the proposal. Full article

(This article belongs to the Special Issue Multi-Agent Systems)

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18 pages, 57789 KiB

Open AccessArticle

Numerical Studies on the Action Mechanism of Combustion Intermediates and Free Radicals on Nitrogen Oxides under Oil-Water Blended Conditions

by Xiumin Yu^1,2, Fengshuo He^1,2

, Yaodong Du^1,2,* and Zezhou Guo^1,2

¹ State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022, China

² College of Automotive Engineering, Jilin University, Changchun 130022, China

Appl. Sci. 2018, 8(4), 490; https://doi.org/10.3390/app8040490 - 23 Mar 2018

Viewed by 3100

Abstract

The action mechanism of combustion intermediates and free radicals on nitrogen oxides have been evaluated. Based on chemical reaction dynamics and modern statistical theory, the subject was investigated by means of numerical simulation. A wide water/oil ratio and a wide air/fuel ratio were [...] Read more.

The action mechanism of combustion intermediates and free radicals on nitrogen oxides have been evaluated. Based on chemical reaction dynamics and modern statistical theory, the subject was investigated by means of numerical simulation. A wide water/oil ratio and a wide air/fuel ratio were also taken into account. Some main conclusions were drawn that the reaction response of H₂O₂ is lagged behind, with the increase of water mass fraction from 10% to 30%. The maximum generation rate is 2.77%, 5.67%, 8.38% and the maximum consumption rate is 3.55%, 6.80%, 13.01% lower than that without water. Water addition leads to decline of the maximum generation rate of NO, N₂O, NO₂ by 15.24%, 9.21%, 14.78% on average. Further, the saliency factor is explored in the main reaction process depending on the correlation analysis and the sensitivity analysis method. According to the degree of the significance, OH > O > H₂ for NO, O > H₂ > OH > HO₂ for N₂O, and OH > H₂ > O > H₂O₂ > HO₂ for NO₂. In the case of oil-water blended, H + O₂ <=> O + OH and H₂O₂(+M) <=> 2OH(+M) promote the generation of OH and O at the beginning of the second stage, but H + O₂(+M) <=> HO₂(+M), HO₂ + OH <=> H₂O + O₂, H₂O₂ + OH <=> H₂O + HO₂ play an inhibitory role in the generation of OH and O. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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20 pages, 3038 KiB

Open AccessArticle

Design and Analysis of a Floor Radiant Heating System Based on Energy Substitution Technology

by Lian Zhang^* and Baowen Cao

Department of New Energy, Tianjin Sino-German University of Applied Sciences, Tianjin 300350, China

Appl. Sci. 2018, 8(4), 491; https://doi.org/10.3390/app8040491 - 25 Mar 2018

Cited by 8 | Viewed by 4061

Abstract

With the development of renewable energy, energy substitution technology has been applied to many fields. This research suggests that solar energy, as renewable energy, takes the place of conventional energy: a floor radiant heating system driven by solar energy is combined with a [...] Read more.

With the development of renewable energy, energy substitution technology has been applied to many fields. This research suggests that solar energy, as renewable energy, takes the place of conventional energy: a floor radiant heating system driven by solar energy is combined with a photovoltaic floor radiant heating system, and the photothermal floor radiant heating system has been proposed and investigated in this study. This research also designs a fuzzy PID (Proportion, Integration, Differentiation) control system to control the indoor temperature within the set range precisely. In this paper, the proposed floor radiant heating system has been tested and analyzed. The experimental results show that the inhomogeneity of the indoor floor surface temperature distribution is larger than that of other places, and the standard deviation of the indoor floor surface temperature can reach 1.87 °C. The standard deviation was approximately 0.36 °C at 0.6 m, 1.2 m and 1.8 m, which indicates this is suitable for habitation. Three kinds of floor radiant heating systems were compared and analyzed to demonstrate the advantage of the proposed floor radiant heating system. The calculation method of the heating system was proposed and applied to the actual heating system in this paper. The proposed floor radiant heating system is a highly efficient and environmental protection system that can be used for heating extensive areas to realize the objective of energy saving and emission reduction. Full article

(This article belongs to the Section Energy Science and Technology)

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8 pages, 14141 KiB

Open AccessArticle

Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

by Megumi Sakurai¹, Taro Sato², Jiawei Xu^2,3, Soichi Sato¹ and Tatsuya Fujino^2,3,*

¹ Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0379, Japan

² Department of Applied Chemistry, Graduate School of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan

³ Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe 350-8585, Japan

Appl. Sci. 2018, 8(4), 492; https://doi.org/10.3390/app8040492 - 26 Mar 2018

Cited by 3 | Viewed by 4275

Abstract

Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by [...] Read more.

Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe. Measurements of model peptides, angiotensin II (AngII) and substance P (SubP), were also carried out but the obtained peak intensities were very low. In order to explain this result, the interaction between CdTe and AngII was confirmed by diffuse reflectance spectroscopy. The results suggest that electrostatic binding between semiconductor nanoparticles and AngII prevented the efficient desorption of AngII into the gas phase. Full article

(This article belongs to the Special Issue Photoionization Mass Spectrometry)

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16 pages, 5251 KiB

Open AccessArticle

A Bayesian Network Based Adaptability Design of Product Structures for Function Evolution

by Shaobo Li^1,2

, Yongming Wu^1,2,*, Yanxia Xu¹, Jie Hu^1,3 and Jianjun Hu^2,3,*

¹ Key Laboratory of Advanced Manufacturing Technology (Guizhou University), Ministry of Education, Guiyang 550025, China

² School of Mechanical Engineering, Guizhou University, Guiyang 550025, China

³ Department of Computer Science and Engineering, University of South Carolina, Columbia, SC 29208, USA

Appl. Sci. 2018, 8(4), 493; https://doi.org/10.3390/app8040493 - 26 Mar 2018

Cited by 12 | Viewed by 4860

Abstract

Structure adaptability design is critical for function evolution in product families, in which many structural and functional design factors are intertwined together with manufacturing cost, customer satisfaction, and final market sales. How to achieve a delicate balance among all of these factors to [...] Read more.

Structure adaptability design is critical for function evolution in product families, in which many structural and functional design factors are intertwined together with manufacturing cost, customer satisfaction, and final market sales. How to achieve a delicate balance among all of these factors to maximize the market performance of the product is too complicated to address based on traditional domain experts’ knowledge or some ad hoc heuristics. Here, we propose a quantitative product evolution design model that is based on Bayesian networks to model the dynamic relationship between customer needs and product structure design. In our model, all of the structural or functional features along with customer satisfaction, manufacturing cost, sale price, market sales, and indirect factors are modeled as random variables denoted as nodes in the Bayesian networks. The structure of the Bayesian model is then determined based on the historical data, which captures the dynamic sophisticated relationship of customer demands of a product, structural design, and market performance. Application of our approach to an electric toothbrush product family evolution design problem shows that our model allows for designers to interrogate with the model and obtain theoretical and decision support for dynamic product feature design process. Full article

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26 pages, 1934 KiB

Open AccessArticle

An Ensemble Based Evolutionary Approach to the Class Imbalance Problem with Applications in CBIR

by Aun Irtaza¹, Syed M. Adnan¹, Khawaja Tehseen Ahmed², Arfan Jaffar³, Ahmad Khan⁴, Ali Javed⁵

and Muhammad Tariq Mahmood^6,*

¹ Department of Computer Science, University of Engineering and Technology, Taxila 47080, Pakistan

² Department of Computer Science, University of Central Punjab, Lahore 54000, Pakistan

³ College of Computer and Information Sciences, Al Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11432, Saudi Arabia

⁴ Department of Computer Science, COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan

⁵ Department of Software Engineering, University of Engineering and Technology, Taxila 47080, Pakistan

⁶ School of Computer Science and Engineering, Korea University of Technology and Education, 1600 Chungjeolno, Byeogchunmyun, Cheonan 31253, Korea

Appl. Sci. 2018, 8(4), 495; https://doi.org/10.3390/app8040495 - 26 Mar 2018

Cited by 30 | Viewed by 4188

Abstract

In order to lower the dependence on textual annotations for image searches, the content based image retrieval (CBIR) has become a popular topic in computer vision. A wide range of CBIR applications consider classification techniques, such as artificial neural networks (ANN), support vector [...] Read more.

In order to lower the dependence on textual annotations for image searches, the content based image retrieval (CBIR) has become a popular topic in computer vision. A wide range of CBIR applications consider classification techniques, such as artificial neural networks (ANN), support vector machines (SVM), etc. to understand the query image content to retrieve relevant output. However, in multi-class search environments, the retrieval results are far from optimal due to overlapping semantics amongst subjects of various classes. The classification through multiple classifiers generate better results, but as the number of negative examples increases due to highly correlated semantic classes, classification bias occurs towards the negative class, hence, the combination of the classifiers become even more unstable particularly in one-against-all classification scenarios. In order to resolve this issue, a genetic algorithm (GA) based classifier comity learning (GCCL) method is presented in this paper to generate stable classifiers by combining ANN with SVMs through asymmetric and symmetric bagging. The proposed approach resolves the classification disagreement amongst different classifiers and also resolves the class imbalance problem in CBIR. Once the stable classifiers are generated, the query image is presented to the trained model to understand the underlying semantic content of the query image for association with the precise semantic class. Afterwards, the feature similarity is computed within the obtained class to generate the semantic response of the system. The experiments reveal that the proposed method outperforms various state-of-the-art methods and significantly improves the image retrieval performance. Full article

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14 pages, 9777 KiB

Open AccessArticle

Novel Automatic Idle Speed Control System with Hydraulic Accumulator and Control Strategy for Construction Machinery

by Haoling Ren, Tianliang Lin^*, Shengyan Zhou, Weiping Huang and Cheng Miao

College of Mechanical Engineering and Automation, Huaqiao University, Xiamen 361021, China

Appl. Sci. 2018, 8(4), 496; https://doi.org/10.3390/app8040496 - 26 Mar 2018

Cited by 8 | Viewed by 6575

Abstract

To reduce the energy consumption and emissions of the hydraulic excavator, a two-level idle speed control system with a hydraulic accumulator for the construction machinery is proposed to reduce the energy consumption and improve the control performance of the actuator when the idle [...] Read more.

To reduce the energy consumption and emissions of the hydraulic excavator, a two-level idle speed control system with a hydraulic accumulator for the construction machinery is proposed to reduce the energy consumption and improve the control performance of the actuator when the idle mode is cancelled. The structure and working principle are analyzed. The hydraulic accumulator (HA) is used to store the energy, which can provide backup pressured fluid when the idle mode is cancelled. Then, a method of how to set the pressure differential between the hydraulic accumulator and the load is proposed and the control law is discussed. The test rig is built. The experimental result shows that the idle speed can be switched among the first idle speed, the second idle speed and the normal speed automatically. Though the idle speed in the novel system can be reduced more than that in the conventional automatic idle speed control system (AISCS), the proposed system can still build the actuator pressure more quickly when the idle mode is cancelled. When compared to the system without the idle speed control, the energy saving of the proposed system is about 67%. The proposed two-level idle speed control system with a HA can achieve a high energy efficiency and a good control performance. Full article

(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)

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9 pages, 34398 KiB

Open AccessArticle

Electromagnetic Power Harvester Using Wide-Angle and Polarization-Insensitive Metasurfaces

by Xuanming Zhang, Haixia Liu^* and Long Li^*

Key Laboratory of High Speed Circuit Design and EMC of Ministry of Education, School of Electronic Engineering, Xidian University, Xi’an 710071, China

Appl. Sci. 2018, 8(4), 497; https://doi.org/10.3390/app8040497 - 26 Mar 2018

Cited by 54 | Viewed by 6119

Abstract

A new wide-angle and polarization-insensitive metasurface (MS) instead of traditional antenna is built as the primary ambient energy harvester in this paper. The MS is a two-dimensional energy harvesting array that is composed of subwavelength electrical small ring resonator that is working at [...] Read more.

A new wide-angle and polarization-insensitive metasurface (MS) instead of traditional antenna is built as the primary ambient energy harvester in this paper. The MS is a two-dimensional energy harvesting array that is composed of subwavelength electrical small ring resonator that is working at 2.5 GHz (LTE/WiFi). In the case of different polarization and incidence angles, we demonstrate the metasurface can achieve high harvesting efficiency of 90%. The fabricated prototype of 9 × 9 MS energy harvesting array is measured, and the experimental results validate that the proposed MS has a good performance more than 80% of energy harvesting efficiency for arbitrary polarization and wide-angle incident waves. The good agreement of the simulation with the experiment results verifies the practicability and effectiveness of the proposed MS structure, which will provide a new source of supply in wireless sensor networks (WSN). Full article

(This article belongs to the Special Issue Metasurfaces: Physics and Applications)

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14 pages, 3822 KiB

Open AccessArticle

Rock Fragmentation Characteristics by TBM Cutting and Efficiency under Bi-Lateral Confinement

by Yulong Chen^1,* and Chenpeng Song^2,3,*

¹ State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China

² Department of Energy and Mineral Engineering, EMS Energy Institute and G3 Center, Pennsylvania State University, University Park, PA 16802, USA

³ Key Laboratory of Hydraulic and Waterway Engineering of the Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China

Appl. Sci. 2018, 8(4), 498; https://doi.org/10.3390/app8040498 - 26 Mar 2018

Cited by 5 | Viewed by 4145

Abstract

In this study, the mechanisms of rock breakage are assessed using tunnel boring machine (TBM) disc cutters under bi-axial pressure. Sequential indentation tests were conducted on granite specimens using a tri-axial testing platform. The morphology and volume of the fractured surface were measured [...] Read more.

In this study, the mechanisms of rock breakage are assessed using tunnel boring machine (TBM) disc cutters under bi-axial pressure. Sequential indentation tests were conducted on granite specimens using a tri-axial testing platform. The morphology and volume of the fractured surface were measured and analyzed using a three-dimensional surface profilometer. An analysis of rock breaking growth and efficiency was performed as well. When the minor confining pressure (σ₁) is constant, the results show that a larger difference in confining pressure leads to a larger volume of fractured surface, thereafter improving the rock-breaking efficiency even though the penetration energy is enlarged. On the other hand, when the major confining pressure (σ₂) is constant, the penetration energy increases proportionally with the σ₁; however, the volume of fractured surface is decreased, and the breaking efficiency is attenuated as well. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 8759 KiB

Open AccessArticle

Assist-as-Needed Control of a Robotic Orthosis Actuated by Pneumatic Artificial Muscle for Gait Rehabilitation

by Quy-Thinh Dao^1,*

and Shin-ichiroh Yamamoto²

¹ Graduate School of Engineering and Science, Shibaura Institute of Technology, Saitama 337-8570, Japan

² Department of Bioscience Engineering, Shibaura Institute of Technology, Saitama 337-8570, Japan

Appl. Sci. 2018, 8(4), 499; https://doi.org/10.3390/app8040499 - 26 Mar 2018

Cited by 42 | Viewed by 7245

Abstract

Rehabilitation robots are designed to help patients improve their recovery from injury by supporting them to perform repetitive and systematic training sessions. These robots are not only able to guide the subjects’ lower-limb to a designate trajectory, but also estimate their disability and [...] Read more.

Rehabilitation robots are designed to help patients improve their recovery from injury by supporting them to perform repetitive and systematic training sessions. These robots are not only able to guide the subjects’ lower-limb to a designate trajectory, but also estimate their disability and adapt the compliance accordingly. In this research, a new control strategy for a high compliant lower-limb rehabilitation orthosis system named AIRGAIT is developed. The AIRGAIT orthosis is powered by pneumatic artificial muscle actuators. The trajectory tracking controller based on a modified computed torque control which employs a fractional derivative is proposed for the tracking purpose. In addition, a new method is proposed for compliance control of the robotic orthosis which results in the successful implementation of the assist-as-needed training strategy. Finally, various subject-based experiments are carried out to verify the effectiveness of the developed control system. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 22611 KiB

Open AccessArticle

A Semantic Segmentation Algorithm Using FCN with Combination of BSLIC

by Wei Zhao¹, Haodi Zhang¹, Yujin Yan¹, Yi Fu¹

and Hai Wang^2,*

¹ Key Laboratory of Electronic Equipment Structure Design, Ministry of Education, Xidian University, Xi’an 710071, China

² School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

Appl. Sci. 2018, 8(4), 500; https://doi.org/10.3390/app8040500 - 26 Mar 2018

Cited by 33 | Viewed by 7122

Abstract

An image semantic segmentation algorithm using fully convolutional network (FCN) integrated with the recently proposed simple linear iterative clustering (SLIC) that is based on boundary term (BSLIC) is developed. To improve the segmentation accuracy, the developed algorithm combines the FCN semantic segmentation results [...] Read more.

An image semantic segmentation algorithm using fully convolutional network (FCN) integrated with the recently proposed simple linear iterative clustering (SLIC) that is based on boundary term (BSLIC) is developed. To improve the segmentation accuracy, the developed algorithm combines the FCN semantic segmentation results with the superpixel information acquired by BSLIC. During the combination process, the superpixel semantic annotation is newly introduced and realized by the four criteria. The four criteria are used to annotate a superpixel region, according to FCN semantic segmentation result. The developed algorithm can not only accurately identify the semantic information of the target in the image, but also achieve a high accuracy in the positioning of small edges. The effectiveness of our algorithm is evaluated on the dataset PASCAL VOC 2012. Experimental results show that the developed algorithm improved the target segmentation accuracy in comparison with the traditional FCN model. With the BSLIC superpixel information that is involved, the proposed algorithm can get 3.86%, 1.41%, and 1.28% improvement in pixel accuracy (PA) over FCN-32s, FCN-16s, and FCN-8s, respectively. Full article

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13 pages, 32165 KiB

Open AccessFeature PaperArticle

Mechanical Characterisation and Modelling of Elastomeric Shockpads

by David Cole^1,*, Steph Forrester¹

and Paul Fleming²

¹ Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK

² School of Architecture, Building and Civil Engineering, Loughborough University, Loughborough LE11 3TU, UK

Appl. Sci. 2018, 8(4), 501; https://doi.org/10.3390/app8040501 - 27 Mar 2018

Cited by 9 | Viewed by 6207

Abstract

Third generation artificial turf systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. An elastomeric shockpad is often included beneath the carpet layer to [...] Read more.

Third generation artificial turf systems are comprised of a range of polymeric and elastomeric materials that exhibit non-linear and strain rate dependent behaviours under the complex loads applied from players and equipment. An elastomeric shockpad is often included beneath the carpet layer to aid in the absorption of impact forces. The purpose of this study was to characterise the behaviour of two elastomeric shockpads and find a suitable material model to represent them in finite element simulations. To characterise the behaviour of the shockpads an Advanced Artificial Athlete test device was used to gather stress-strain data from different drop heights (15, 35 and 55 mm). The experimental results from both shockpads showed a hyperelastic material response with viscoelasticity. Microfoam material models were found to describe the material behaviour of the shockpads and were calibrated using the 55 mm drop height experimental data. The material model for each shockpad was verified through finite element simulations of the Advanced Artificial Athlete impact from different drop heights (35 and 15 mm). Finite element model accuracy was assessed through the comparison of a series of key variables including shock absorption, energy restitution, vertical deformation and contact time. Both shockpad models produced results with a mean error of less than 10% compared to experimental data. Full article

(This article belongs to the Special Issue Sports Materials)

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18 pages, 71309 KiB

Open AccessArticle

A New Wind Turbine Generating System Model for Balanced and Unbalanced Distribution Systems Load Flow Analysis

by Ahmet Koksoy^1,*, Onur Ozturk¹, Murat Erhan Balci² and Mehmet Hakan Hocaoglu¹

¹ Electronics Engineering Department, Gebze Technical University, Cumhuriyet District, 2254 St., No. 2, 41400 Gebze/Kocaeli, Turkey

² Electrical and Electronics Engineering Department, Balıkesir University, 10145 Balıkesir, Turkey

Appl. Sci. 2018, 8(4), 502; https://doi.org/10.3390/app8040502 - 27 Mar 2018

Cited by 16 | Viewed by 4539

Abstract

Wind turbine generating systems (WTGSs), which are conventionally connected to high voltage transmission networks, have frequently been employed as distributed generation units in today’s distribution networks. In practice, the distribution networks always have unbalanced bus voltages and line currents due to uneven distribution [...] Read more.

Wind turbine generating systems (WTGSs), which are conventionally connected to high voltage transmission networks, have frequently been employed as distributed generation units in today’s distribution networks. In practice, the distribution networks always have unbalanced bus voltages and line currents due to uneven distribution of single or double phase loads over three phases and asymmetry of the lines, etc. Accordingly, in this study, for the load flow analysis of the distribution networks, Conventional Fixed speed Induction Generator (CFIG) based WTGS, one of the most widely used WTGS types, is modelled under unbalanced voltage conditions. The Developed model has active and reactive power expressions in terms of induction machine impedance parameters, terminal voltages and input power. The validity of the Developed model is confirmed with the experimental results obtained in a test system. The results of the slip calculation based phase-domain model (SCP Model), which was previously proposed in the literature for CFIG based WTGSs under unbalanced voltages, are also given for the comparison. Finally, the Developed model and the SCP model are implemented in the load flow analysis of the IEEE 34 bus test system with the CFIG based WTGSs and unbalanced loads. Thus, it is clearly pointed out that the results of the load flow analysis implemented with both models are very close to each other, and the Developed model is computationally more efficient than the SCP model. Full article

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7 pages, 19979 KiB

Open AccessArticle

Stability of Two-Dimensional Polymorphs for 10,12-Pentacosadyn-1-ol on Graphite Investigated by SPM

by Daisuke Takajo^1,* and Koichi Sudoh²

¹ Research Center for Structural Thermodynamics, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan

² The Institute of Scientific and Industrial Research, Osaka University, Ibaraki 567-0047, Japan

Appl. Sci. 2018, 8(4), 503; https://doi.org/10.3390/app8040503 - 27 Mar 2018

Cited by 2 | Viewed by 3268

Abstract

For monomolecular layers of 10,12-pentacosadiyn-1-ol on graphite, it is known that two different two-dimensional polymorphic forms—herringbone (H) and parallel (P) arrangements—are observable at room temperature. Here, we study the thermodynamic stability of these polymorphs by scanning tunneling microscopy (STM) and atomic force microscopy. [...] Read more.

For monomolecular layers of 10,12-pentacosadiyn-1-ol on graphite, it is known that two different two-dimensional polymorphic forms—herringbone (H) and parallel (P) arrangements—are observable at room temperature. Here, we study the thermodynamic stability of these polymorphs by scanning tunneling microscopy (STM) and atomic force microscopy. When the monomolecular films, where H and P domains coexist, are annealed at above 40 °C, the area of P arrangement irreversibly increases, demonstrating that P arrangement is thermodynamically stable while H arrangement is quasi-stable. Consistently, invasion of P domains into H domains is observed during morphological changes induced by STM scanning at room temperature. Furthermore, we estimate that the melting point of the monomolecular film of P arrangement is about 80 °C, which is 20 °C higher than that of the bulk crystal. Full article

(This article belongs to the Special Issue Quantum Materials)

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10 pages, 21416 KiB

Open AccessArticle

An FPGA Implementation of a Convolutional Auto-Encoder

by Wei Zhao¹, Zuchen Jia¹

, Xiaosong Wei¹ and Hai Wang^2,*

¹ Key Laboratory of Electronic Equipment Structure Design, Ministry of Education, Xidian University, Xi’an 710071, China

² School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

Appl. Sci. 2018, 8(4), 504; https://doi.org/10.3390/app8040504 - 27 Mar 2018

Cited by 13 | Viewed by 7561

Abstract

In order to simplify the hardware design and reduce the resource requirements, this paper proposes a novel implementation of a convolutional auto-encoder (CAE) in a field programmable gate array (FPGA). Instead of the traditional framework realized in a layer-by-layer way, we designed a [...] Read more.

In order to simplify the hardware design and reduce the resource requirements, this paper proposes a novel implementation of a convolutional auto-encoder (CAE) in a field programmable gate array (FPGA). Instead of the traditional framework realized in a layer-by-layer way, we designed a new periodic layer-multiplexing framework for CAE. Only one layer is introduced and periodically reused to establish the network, which consumes fewer hardware resources. Moreover, by fixing the number of channels, this framework can be applicable to an image of arbitrary size. Furthermore, to effectively improve the speed of convolution calculation, the parallel convolution method is used based on shift registers. Experimental results show that the proposed CAE framework achieves good performance in image compression. It can be observed that our CAE framework has advantages in resources occupation, operation speed, and power consumption, indicating great potential for application in digital signal processing. Full article

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22 pages, 119602 KiB

Open AccessArticle

Multi-Objective and Multi-Rate Control of the Grinding and Classification Circuit with Electromagnetic Mill

by Szymon Ogonowski^*

, Zbigniew Ogonowski and Marek Pawełczyk

Institute of Automatic Control, Silesian University of Technology, 44-100 Gliwice, Poland

Appl. Sci. 2018, 8(4), 506; https://doi.org/10.3390/app8040506 - 27 Mar 2018

Cited by 19 | Viewed by 4576

Abstract

The paper presents an innovative construction and installation of dry grinding in electromagnetic mill that provides a significant reduction of energy consumption when compared to traditional mills. The installation constitutes complex multi-objective plant. To gain control over all the objectives, hierarchical structure of [...] Read more.

The paper presents an innovative construction and installation of dry grinding in electromagnetic mill that provides a significant reduction of energy consumption when compared to traditional mills. The installation constitutes complex multi-objective plant. To gain control over all the objectives, hierarchical structure of control system was developed where different time-horizons involve multi-rate scheme of steering. The paper presents solutions for the direct regulation, supervisory control, and optimization level. The electromagnetic mill installation constitutes a unique setup that causes open loop instability and implies the application of novel control schemes at all of the levels. The paper presents these solutions and illustrates them with the results of experiments carried out on the electromagnetic mill installations. Full article

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18 pages, 2309 KiB

Open AccessArticle

Assessment of Student Music Performances Using Deep Neural Networks

by Kumar Ashis Pati^*,†, Siddharth Gururani^† and Alexander Lerch

¹ Center for Music Technology, Georgia Institute of Technology, Atlanta, GA 30318, USA

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 507; https://doi.org/10.3390/app8040507 - 27 Mar 2018

Cited by 39 | Viewed by 10200

Abstract

Music performance assessment is a highly subjective task often relying on experts to gauge both the technical and aesthetic aspects of the performance from the audio signal. This article explores the task of building computational models for music performance assessment, i.e., analyzing an [...] Read more.

Music performance assessment is a highly subjective task often relying on experts to gauge both the technical and aesthetic aspects of the performance from the audio signal. This article explores the task of building computational models for music performance assessment, i.e., analyzing an audio recording of a performance and rating it along several criteria such as musicality, note accuracy, etc. Much of the earlier work in this area has been centered around using hand-crafted features intended to capture relevant aspects of a performance. However, such features are based on our limited understanding of music perception and may not be optimal. In this article, we propose using Deep Neural Networks (DNNs) for the task and compare their performance against a baseline model using standard and hand-crafted features. We show that, using input representations at different levels of abstraction, DNNs can outperform the baseline models across all assessment criteria. In addition, we use model analysis techniques to further explain the model predictions in an attempt to gain useful insights into the assessment process. The results demonstrate the potential of using supervised feature learning techniques to better characterize music performances. Full article

(This article belongs to the Special Issue Digital Audio and Image Processing with Focus on Music Research)

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16 pages, 11357 KiB

Open AccessArticle

Internet of Things for Sensing: A Case Study in the Healthcare System

by Syed Aziz Shah¹

, Aifeng Ren², Dou Fan²

, Zhiya Zhang², Nan Zhao², Xiaodong Yang^2,*, Ming Luo², Weigang Wang³, Fangming Hu², Masood Ur Rehman⁴

, Osamah S. Badarneh⁵ and Qammer Hussain Abbasi⁶

¹ School of International Education, Xidian University, Xi’an 710071, Shaanxi, China

² School of Electronic Engineering, Xidian University, Xi’an 710071, Shaanxi, China

³ Northwest Women’s and Children’s Hospital, Xi’an 710061, Shaanxi, China

⁴ School of Computer Science and Technology, University of Bedfordshire, Luton LU1 3JU, UK

⁵ Electrical Engineering Department, University of Tabuk, Tabuk 71491, Saudi Arabia

⁶ School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK

Appl. Sci. 2018, 8(4), 508; https://doi.org/10.3390/app8040508 - 27 Mar 2018

Cited by 47 | Viewed by 9368

Abstract

Medical healthcare is one of the fascinating applications using Internet of Things (IoTs). The pervasive smart environment in IoTs has the potential to monitor various human activities by deploying smart devices. In our pilot study, we look at narcolepsy, a disorder in which [...] Read more.

Medical healthcare is one of the fascinating applications using Internet of Things (IoTs). The pervasive smart environment in IoTs has the potential to monitor various human activities by deploying smart devices. In our pilot study, we look at narcolepsy, a disorder in which individuals lose the ability to regulate their sleep-wake cycle. An imbalance in the brain chemical called orexin makes the sleep pattern irregular. This sleep disorder in patients suffering from narcolepsy results in them experience irrepressible sleep episodes while performing daily routine activities. This study presents a novel method for detecting sleep attacks or sleepiness due to immune system attacks and affecting daily activities measured using the S-band sensing technique. The S-Band sensing technique is channel sensing based on frequency spectrum sensing using the orthogonal frequency division multiplexing transmission at a 2 to 4 GHz frequency range leveraging amplitude and calibrated phase information of different frequencies obtained using wireless devices such as card, and omni-directional antenna. Each human behavior induces a unique channel information (CI) signature contained in amplitude and phase information. By linearly transforming raw phase measurements into calibrated phase information, we ascertain phase coherence. Classification and validation of various human activities such as walking, sitting on a chair, push-ups, and narcolepsy sleep episodes are done using support vector machine, K-nearest neighbor, and random forest algorithms. The measurement and evaluation were carried out several times with classification values of accuracy, precision, recall, specificity, Kappa, and F-measure of more than 90% that were achieved when delineating sleep attacks. Full article

(This article belongs to the Special Issue Wearable Wireless Devices)

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14 pages, 4388 KiB

Open AccessArticle

Sequencing Batch Reactor and Bacterial Community in Aerobic Granular Sludge for Wastewater Treatment of Noodle-Manufacturing Sector

by Tang Thi Chinh^1,3,*, Phung Duc Hieu¹, Bui Van Cuong¹, Nguyen Nhat Linh², Nguyen Ngoc Lan^2,3, Nguyen Sy Nguyen¹, Nguyen Quang Hung^1,3 and Le Thi Thu Hien^2,3,*

¹ Institute of Environmental Technology (IET), Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam

² Institute of Genome Research (IGR), Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam

³ Graduate University of Science and Technology (GUST), Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam

Appl. Sci. 2018, 8(4), 509; https://doi.org/10.3390/app8040509 - 27 Mar 2018

Cited by 3 | Viewed by 8502

Abstract

The sequencing batch reactor (SBR) has been increasingly applied in the control of high organic wastewater. In this study, SBR with aerobic granular sludge was used for wastewater treatment in a noodle-manufacturing village in Vietnam. The results showed that after two months of [...] Read more.

The sequencing batch reactor (SBR) has been increasingly applied in the control of high organic wastewater. In this study, SBR with aerobic granular sludge was used for wastewater treatment in a noodle-manufacturing village in Vietnam. The results showed that after two months of operation, the chemical oxygen demand, total nitrogen and total phosphorous removal efficiency of aerobic granular SBR reached 92%, 83% and 75%, respectively. Bacterial diversity and bacterial community in wastewater treatment were examined using Illumina Miseq sequencing to amplify the V3-V4 regions of the 16S rRNA gene. A high diversity of bacteria was observed in the activated sludge, with more than 400 bacterial genera and 700 species. The predominant genus was Lactococcus (21.35%) mainly containing Lactococcus chungangensis species. Predicted functional analysis showed a high representation of genes involved in membrane transport (12.217%), amino acid metabolism (10.067%), and carbohydrate metabolism (9.597%). Genes responsible for starch and sucrose metabolism accounted for 0.57% of the total reads and the composition of starch hydrolytic enzymes including α-amylase, starch phosphorylase, glucoamylase, pullulanase, α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, and 1,4-α-glucan branching enzyme. The presence of these enzymes in the SBR system may improve the removal of starch pollutants in wastewater. Full article

(This article belongs to the Special Issue Sustainable Environmental Remediation)

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12 pages, 18333 KiB

Open AccessArticle

Thermally Bonded PET–Basalt Sandwich Composites for Heat Pipeline Protection: Preparation, Stab Resisting, and Thermal-Insulating Properties

by Ting-Ting Li^1,2, Xiayun Zhang¹, Haokai Peng¹, Qian Jiang¹, Wenna Dai¹, Ching-Wen Lou³ and Jia-Horng Lin^2,4,5,6,*

¹ Innovation Platform of Intelligent and Energy-Saving Textiles, School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China

² Fujian Key Laboratory of Novel Functional Fibers and Materials, Minjiang University, Fuzhou 350108, China

³ Graduate Institute of Biotechnology and Biomedical Engineering, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan

⁴ Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials, Feng Chia University, Taichung 40724, Taiwan

⁵ Department of Fashion Design, Asia University, Taichung 41354, Taiwan

⁶ School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan

Appl. Sci. 2018, 8(4), 510; https://doi.org/10.3390/app8040510 - 27 Mar 2018

Cited by 11 | Viewed by 4946

Abstract

In order to solve the cost and bulky problems of buried thermal pipeline insulating materials, this study adopts basalt fabric and low-melting PET nonwoven to construct low-cost and light-weight pipeline thermal-insulating composites after needle punching and thermal bonding processes. Research result shows that [...] Read more.

In order to solve the cost and bulky problems of buried thermal pipeline insulating materials, this study adopts basalt fabric and low-melting PET nonwoven to construct low-cost and light-weight pipeline thermal-insulating composites after needle punching and thermal bonding processes. Research result shows that thermal-bonded temperature affected the stab resistance and burst energy more significantly. As thermal-bonded temperature increased, knife resistance and spike resistance presented the upward and then downward trends, but the burst energy gradually decreased. Yarn pull-out result shows that the enhancement of stab resistance of intra-/inter-thermal-bonded structure resulted from the increment in the coefficient of friction between yarns. When PET–basalt sandwich composites were thermal-bonded at 140 °C for 5 min, the maximum knife and spike resistance were 147.00 N (1.99 J) and 196.30 N (1.11 J), respectively, and burst energy was 4.79 J, thermal conductivity reduced to 0.0073 W/(m∙K). The resultant thermally bonded sandwich composites can be used as thermal-insulating protection for buried thermal pipeline. Full article

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9 pages, 2486 KiB

Open AccessArticle

Silicone-Based Molding Technique for Optical Flow Analysis in Transparent Models of Fluidic Components

by Mark Schult, Christoph Drobek and Hermann Seitz^*

Fluid Technology and Microfluidics, University of Rostock, Justus-von-Liebig-Weg 6, 18059 Rostock, Germany

Appl. Sci. 2018, 8(4), 512; https://doi.org/10.3390/app8040512 - 27 Mar 2018

Viewed by 4567

Abstract

Optical flow analysis methods such as particle image velocimetry can only be performed in fluid systems or components with optical access. Many fluidic components, such as metallic tubes, do not typically feature optical accessibility. A new silicone-based molding technique is presented that makes [...] Read more.

Optical flow analysis methods such as particle image velocimetry can only be performed in fluid systems or components with optical access. Many fluidic components, such as metallic tubes, do not typically feature optical accessibility. A new silicone-based molding technique is presented that makes it possible to replicate non-transparent fluidic components as models with optical accessibility that can be used to perform optical flow analysis. Furthermore, to avoid errors due to refraction, a test fluid is presented whose refractive index matches that of the silicone material of the replication. This new method allows flows to be analyzed in tubes or similar components with diameters in the range of only a few millimeters. An initial test was performed demonstrating the proof of concept and the velocity field of the flow inside a manifold was measured using a micro-particle image velocimetry setup. The study showed that both simple parts like tubes and complex parts such as manifolds can be replicated and investigated. Full article

(This article belongs to the Section Mechanical Engineering)

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12 pages, 18874 KiB

Open AccessArticle

Growth Identification of Aspergillus flavus and Aspergillus parasiticus by Visible/Near-Infrared Hyperspectral Imaging

by Xuan Chu^1,†, Wei Wang^1,†

, Xinzhi Ni², Haitao Zheng³, Xin Zhao¹, Ren Zhang^4,* and Yufeng Li^5,*

¹ College of Engineering, China Agricultural University, Beijing 100083, China

² Crop Genetics and Breeding Research Unit, USDA-ARS, 2747 Davis Road, Tifton, GA 31793, USA

³ College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China

⁴ College of Information Engineering, Tarim University, Alar 843300, China

⁵ Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China

^† These authors contributed equally to this work and should be considered co-first authors

Appl. Sci. 2018, 8(4), 513; https://doi.org/10.3390/app8040513 - 28 Mar 2018

Cited by 14 | Viewed by 5448

Abstract

Visible/near-infrared (Vis/NIR) hyperspectral imaging (400–1000 nm) was applied to identify the growth process of Aspergillus flavus and Aspergillus parasiticus. The hyperspectral images of the two fungi that were growing on rose bengal medium were recorded daily for 6 days. A band ratio [...] Read more.

Visible/near-infrared (Vis/NIR) hyperspectral imaging (400–1000 nm) was applied to identify the growth process of Aspergillus flavus and Aspergillus parasiticus. The hyperspectral images of the two fungi that were growing on rose bengal medium were recorded daily for 6 days. A band ratio using two bands at 446 nm and 460 nm separated A. flavus and A. parasiticus on day 1 from other days. Image at band of 520 nm classified A. parasiticus on day 6. Principle component analysis (PCA) was performed on the cleaned hyperspectral images. The score plot of the second to sixth principal components (PC₂ to PC₆) gave a rough clustering of fungi in the same incubation time. However, in the plot, A. flavus on day 3 and day 4 and A. parasiticus on day 2 and day 3 overlapped. The average spectra of each fungus in each growth day were extracted, then PCA and support vector machine (SVM) classifier were applied to the full spectral range. SVM models built by PC₂ to PC₆ could identify fungal growth days with accuracies of 92.59% and 100% for A. flavus and A. parasiticus individually. In order to simplify the prediction models, competitive adaptive reweighted sampling (CARS) was employed to choose optimal wavelengths. As a result, nine (402, 442, 487, 502, 524, 553, 646, 671, 760 nm) and seven (461, 538, 542, 742, 753, 756, 919 nm) wavelengths were selected for A. flavus and A. parasiticus, respectively. New optimal wavelengths SVM models were built, and the identification accuracies were 83.33% and 98.15% for A. flavus and A. parasiticus, respectively. Finally, the visualized prediction images for A. flavus and A. parasiticus in different growth days were made by applying the optimal wavelength’s SVM models on every pixel of the hyperspectral image. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

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21 pages, 15012 KiB

Open AccessArticle

Power to Fuels: Dynamic Modeling of a Slurry Bubble Column Reactor in Lab-Scale for Fischer Tropsch Synthesis under Variable Load of Synthesis Gas

by Siavash Seyednejadian^1,*

, Reinhard Rauch²

, Samir Bensaid¹, Hermann Hofbauer³

, Gerald Weber⁴ and Guido Saracco¹

¹ Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

² Engler-Bunte-Institut, Karlsruher Institute of Technology, Engler-Bunte- Ring 3, 76139 Karlsruhe, Germany

³ Institute of Chemical Engineering, Technical University of Vienna, Getreidemarket 9/166, 1060 Vienna, Austria

⁴ Institute Bioenergy 2020+, Wiener Strasse 49, 7540 Güssing, Austria

Appl. Sci. 2018, 8(4), 514; https://doi.org/10.3390/app8040514 - 28 Mar 2018

Cited by 19 | Viewed by 7670

Abstract

This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m D_t and 2.5 m height) for Fischer–Tropsch (FT) synthesis under flexible operation of synthesis gas load flow rates. The variable loads of synthesis gas are [...] Read more.

This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m D_t and 2.5 m height) for Fischer–Tropsch (FT) synthesis under flexible operation of synthesis gas load flow rates. The variable loads of synthesis gas are set at 3.5, 5, 7.5 m³/h based on laboratory adjustments at three different operating temperatures (483, 493 and 503 K). A set of Partial Differential Equations (PDEs) in the form of mass transfer and chemical reaction are successfully coupled to predict the behavior of all the FT components in two phases (gas and liquid) over the reactor bed. In the gas phase, a single-bubble-class-diameter (SBCD) is adopted and the reduction of superficial gas velocity through the reactor length is incorporated into the model by the overall mass balance. Anderson Schulz Flory distribution is employed for reaction kinetics. The modeling results are in good agreement with experimental data. The results of dynamic modeling show that the steady state condition is attained within 10 min from start-up. Furthermore, they show that step-wise syngas flow rate does not have a detrimental influence on FT product selectivity and the dynamic modeling of the slurry reactor responds quite well to the load change conditions. Full article

(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)

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24 pages, 3635 KiB

Open AccessArticle

Defeat Your Enemy Hiding behind Public WiFi: WiGuard Can Protect Your Sensitive Information from CSI-Based Attack

by Jie Zhang^1,‡

, Meng Li^1,‡

, Zhanyong Tang^1,*, Xiaoqing Gong¹, Wei Wang¹, Dingyi Fang¹

and Zheng Wang²

¹ School of Information Science and Technology, Northwest University, Xi’an 710127, China

² School of Computing and Communications, Lancaster University, Lancaster LA1 4YX, UK

^‡ Jie Zhang and Meng Li are co-first authors.

Appl. Sci. 2018, 8(4), 515; https://doi.org/10.3390/app8040515 - 28 Mar 2018

Cited by 10 | Viewed by 4113

Abstract

Channel state information (CSI) has been recently shown to be useful in performing security attacks in public WiFi environments. By analyzing how CSI is affected by finger motions, CSI-based attacks can effectively reconstruct text-based passwords and locking patterns. This paper presents WiGuard, a [...] Read more.

Channel state information (CSI) has been recently shown to be useful in performing security attacks in public WiFi environments. By analyzing how CSI is affected by finger motions, CSI-based attacks can effectively reconstruct text-based passwords and locking patterns. This paper presents WiGuard, a novel system to protect sensitive on-screen input information in a public place. Our approach carefully exploits WiFi channel interference to introduce noise to attacker’s CSI measurements to reduce the success rate of CSI-based attacks. Our approach automatically detects when a CSI-based attack happens. We evaluate our approach by applying it to protect text-based passwords and pattern locks on mobile devices. Experimental results show that our approach is able to reduce the success rate of CSI-based attacks from 92–42% for text-based passwords and from 82–22% for pattern lock. Full article

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32 pages, 17250 KiB

Open AccessArticle

A User-Centered Mobile Cloud Computing Platform for Improving Knowledge Management in Small-to-Medium Enterprises in the Chilean Construction Industry

by Daniela Núñez^1,†, Ximena Ferrada^2,†

, Andrés Neyem^1,†, Alfredo Serpell^3,†

and Marcos Sepúlveda^1,*,†

¹ Computer Science Department, School of Engineering, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile

² School of Civil Construction, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile

³ Faculty of Engineering, Universidad del Desarrollo, Santiago 7610658, Chile

^† All authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 516; https://doi.org/10.3390/app8040516 - 28 Mar 2018

Cited by 15 | Viewed by 7624

Abstract

Knowledge management (KM) is a key element for the development of small-to-medium enterprises (SMEs) in the construction industry. This is particularly relevant in Chile, where this industry is composed almost entirely of SMEs. Although various KM system proposals can be found in the [...] Read more.

Knowledge management (KM) is a key element for the development of small-to-medium enterprises (SMEs) in the construction industry. This is particularly relevant in Chile, where this industry is composed almost entirely of SMEs. Although various KM system proposals can be found in the literature, they are not suitable for SMEs, due to usability problems, budget constraints, and time and connectivity issues. Mobile Cloud Computing (MCC) systems offer several advantages to construction SMEs, but they have not yet been exploited to address KM needs. Therefore, this research is aimed at the development of a MCC-based KM platform to manage lessons learned in different construction projects of SMEs, through an iterative and user-centered methodology. Usability and quality evaluations of the proposed platform show that MCC is a feasible and attractive option to address the KM issues in SMEs of the Chilean construction industry, since it is possible to consider both technical and usability requirements. Full article

(This article belongs to the Special Issue Mobile Cloud Computing)

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14 pages, 2860 KiB

Open AccessArticle

A Body-Nonlinear Green’s Function Method with Viscous Dissipation Effects for Large-Amplitude Roll of Floating Bodies

by Zhiqun Guo¹

, Qingwei Ma^1,2, Shuangrui Yu¹ and Hongde Qin^1,*

¹ College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China

² School of Engineering and Mathematical Sciences, City University London, London EC1V 0HB, UK

Appl. Sci. 2018, 8(4), 517; https://doi.org/10.3390/app8040517 - 28 Mar 2018

Cited by 3 | Viewed by 4100

Abstract

A novel time-domain body-nonlinear Green’s function method is developed for evaluating large-amplitude roll damping of two-dimensional floating bodies with consideration of viscous dissipation effects. In the method, the instantaneous wetted surface of floating bodies is accurately considered, and the viscous dissipation effects are [...] Read more.

A novel time-domain body-nonlinear Green’s function method is developed for evaluating large-amplitude roll damping of two-dimensional floating bodies with consideration of viscous dissipation effects. In the method, the instantaneous wetted surface of floating bodies is accurately considered, and the viscous dissipation effects are taken into account based on the “fairly perfect fluid” model. As compared to the method based on the existing inviscid body-nonlinear Green’s function, the newly proposed method can give a more accurate damping coefficient of floating bodies rolling on the free surface with large amplitudes according to the numerical tests and comparison with experimental data for a few cases related to ship hull sections with bilge keels. Full article

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11 pages, 29715 KiB

Open AccessArticle

Aerodynamic Analysis and Noise-Reducing Design of an Outside Rear View Mirror

by Yong-Ju Chu¹, Yong-Sang Shin² and Seung-Yop Lee^2,*

¹ Electric Powertrain R&D Center, Korea Automotive Technology Institute, 201 Gwahakseo-ro, Guji-myon, Dalseong-gum, Daegu 43011, Korea

² Department of Mechanical Engineering, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Korea

Appl. Sci. 2018, 8(4), 519; https://doi.org/10.3390/app8040519 - 29 Mar 2018

Cited by 18 | Viewed by 15104

Abstract

The outside rear view mirror (OSRVM) is installed on the exterior of vehicles to secure the side and rear views of the vehicle, but its extruded design causes unwanted aerodynamic noise and vibration during driving. In this study, additional line holes (inner dents) [...] Read more.

The outside rear view mirror (OSRVM) is installed on the exterior of vehicles to secure the side and rear views of the vehicle, but its extruded design causes unwanted aerodynamic noise and vibration during driving. In this study, additional line holes (inner dents) are made on the inner and outer edges of the mirror housing without a reduction in size in order to enhance the aerodynamic flow and noise around the mirror. Based on computational fluid dynamics (CFD) analysis, this study compares the aerodynamic characteristics of the original and modified mirror models. The comparative analyses verify that the proposed OSRVM model with the inner ducts dramatically improves the velocity profiles and sound pressure levels. Full article

(This article belongs to the Section Mechanical Engineering)

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12 pages, 54741 KiB

Open AccessArticle

The Influence of Forming Directions and Strain Rate on Dynamic Shear Properties of Aerial Aluminum Alloy

by Ying Meng, Xiangyu Wang, Hao Zongcheng and Xiuli Fu^*

Department of Mechanical Engineering, University of Jinan, No. 336, Nanxinzhuang West Road, Jinan 250022, China

Appl. Sci. 2018, 8(4), 520; https://doi.org/10.3390/app8040520 - 29 Mar 2018

Cited by 8 | Viewed by 4056

Abstract

Dynamic shear properties under high strain rate are an important basis for studying the dynamic mechanical properties and microscopic mechanisms of materials. Dynamic impact shear tests of aerial aluminum alloy 7050-T7451 in rolling direction (RD), transverse direction (TD) and normal direction (ND) were [...] Read more.

Dynamic shear properties under high strain rate are an important basis for studying the dynamic mechanical properties and microscopic mechanisms of materials. Dynamic impact shear tests of aerial aluminum alloy 7050-T7451 in rolling direction (RD), transverse direction (TD) and normal direction (ND) were performed at a range of strain rates from 2.5 × 10⁴ s⁻¹ to 4.5 × 10⁴ s⁻¹ by High Split Hopkinson Pressure Bar (SHPB). The influence of different forming directions and strain rates on the dynamic shear properties of material and the microstructure evolution under dynamic shear were emphatically analyzed. The results showed that aluminum alloy 7050-T7451 had a certain strain rate sensitivity and positive strain rate strengthening effect, and also the material had no obvious strain strengthening effect. Different forming directions had a great influence on dynamic shear properties. The shear stress in ND was the largest, followed by that in RD, and the lowest was that in TD. The microstructure observation showed that the size and orientation of the grain structure were different in three directions, which led to the preferred orientation of the material. All of those were the main reasons for the difference of dynamic shear properties of the material. Full article

(This article belongs to the Section Mechanical Engineering)

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21 pages, 34757 KiB

Open AccessArticle

Ni-Al Alloys as Alternative EUV Mask Absorber

by Vu Luong^1,2,*

, Vicky Philipsen¹, Eric Hendrickx¹, Karl Opsomer¹, Christophe Detavernier³, Christian Laubis⁴, Frank Scholze⁴ and Marc Heyns^1,2

¹ IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

² KU Leuven, Department of Materials Engineering, B-3001 Leuven, Belgium

³ Department of Solid-state Sciences, Ghent University, Krijgslaan 281 (S1), B-9000 Gent, Belgium

⁴ PTB, Abbestraße 2-12, 10587 Berlin, Germany

Appl. Sci. 2018, 8(4), 521; https://doi.org/10.3390/app8040521 - 29 Mar 2018

Cited by 34 | Viewed by 12928

Abstract

Extreme ultraviolet (EUV) lithography is being industrialized as the next candidate printing technique for high-volume manufacturing of scaled down integrated circuits. At mask level, the combination of EUV light at oblique incidence, absorber thickness, and non-uniform mirror reflectance through incidence angle, creates photomask-induced [...] Read more.

Extreme ultraviolet (EUV) lithography is being industrialized as the next candidate printing technique for high-volume manufacturing of scaled down integrated circuits. At mask level, the combination of EUV light at oblique incidence, absorber thickness, and non-uniform mirror reflectance through incidence angle, creates photomask-induced imaging aberrations, known as mask 3D (M3D) effects. A possible mitigation for the M3D effects in the EUV binary intensity mask (BIM), is to use mask absorber materials with high extinction coefficient κ and refractive coefficient n close to unity. We propose nickel aluminide alloys as a candidate BIM absorber material, and characterize them versus a set of specifications that a novel EUV mask absorber must meet. The nickel aluminide samples have reduced crystallinity as compared to metallic nickel, and form a passivating surface oxide layer in neutral solutions. Composition and density profile are investigated to estimate the optical constants, which are then validated with EUV reflectometry. An oxidation-induced Al L2 absorption edge shift is observed, which significantly impacts the value of n at 13.5 nm wavelength and moves it closer to unity. The measured optical constants are incorporated in an accurate mask model for rigorous simulations. The M3D imaging impact of the nickel aluminide alloy mask absorbers, which predict significant M3D reduction in comparison to reference absorber materials. In this paper, we present an extensive experimental methodology flow to evaluate candidate mask absorber materials. Full article

(This article belongs to the Special Issue Advanced EUV and X-Ray Optics)

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19 pages, 1823 KiB

Open AccessArticle

Damage Imaging in Lamb Wave-Based Inspection of Adhesive Joints

by Magdalena Rucka^*

, Erwin Wojtczak

and Jacek Lachowicz

Department of Mechanics of Materials and Structures, Faculty of Civil and Environmental Engineering, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland

Appl. Sci. 2018, 8(4), 522; https://doi.org/10.3390/app8040522 - 29 Mar 2018

Cited by 36 | Viewed by 5008

Abstract

Adhesive bonding has become increasingly important in many industries. Non-destructive inspection of adhesive joints is essential for the condition assessment and maintenance of a structure containing such joints. The aim of this paper was the experimental investigation of the damage identification of a [...] Read more.

Adhesive bonding has become increasingly important in many industries. Non-destructive inspection of adhesive joints is essential for the condition assessment and maintenance of a structure containing such joints. The aim of this paper was the experimental investigation of the damage identification of a single lap adhesive joint of metal plate-like structures. Nine joints with different defects in the form of partial debonding were considered. The inspection was based on ultrasonic guided wave propagation. The Lamb waves were excited at one point of the analyzed specimen by means of a piezoelectric actuator, while the guided wave field was measured with the use of a laser vibrometer. For damage imaging, the recorded out-of-plane vibrations were processed by means of the weighted root mean square (WRMS). The influence of different WRMS parameters (i.e., the time window and weighting factor), as well as excitation frequencies, were analyzed using statistical analysis. The results showed that two-dimensional representations of WRMS values allowed for the identification of the presence of actual defects in the adhesive film and determined their geometry. Full article

(This article belongs to the Special Issue Ultrasonic Guided Waves)

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13 pages, 41395 KiB

Open AccessArticle

Selection of Spectral Resolution and Scanning Speed for Detecting Green Jujubes Chilling Injury Based on Hyperspectral Reflectance Imaging

by Huanda Lu¹

, Xinjie Yu¹, Lijuan Zhou¹ and Yong He^2,*

¹ Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China

² College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China

Appl. Sci. 2018, 8(4), 523; https://doi.org/10.3390/app8040523 - 29 Mar 2018

Cited by 18 | Viewed by 3904

Abstract

Hyperspectral imaging is a non-destructive method for the detection of chilling injury in fruit. However, the limitation of this technique is the lacking of an appropriate working parameters and a feasible discriminating model for chilling on-line sorting. This research was aimed to select [...] Read more.

Hyperspectral imaging is a non-destructive method for the detection of chilling injury in fruit. However, the limitation of this technique is the lacking of an appropriate working parameters and a feasible discriminating model for chilling on-line sorting. This research was aimed to select the optimal spectral resolution, scanning speed, and classification model for green jujube chilling injury detection based on hyperspectral reflectance imaging. Criminisi algorithm was firstly carried out to reconstruct the specular reflection region in spectral images before deriving mean spectra, and thus the optimal wavelengths were selected by random frog. Results showed that the Criminisi algorithm presented a desirable ability of spectral image inpainting. The linear discriminant analysis (LDA) achieved overall accuracies of 98.3% and 93.3% for two-class and three-class classification, respectively, at the speed of 20 mm/s with the spectral resolution of 5.03 nm based on selected spectral features. The results demonstrated that 20 mm/s with the spectral resolution of 5.03 nm was more feasible for the detection of green jujube chilling injury in hyperspectral imaging system due to a higher scanning efficiency, but a less data size. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

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13 pages, 48505 KiB

Open AccessArticle

Acceleration Harmonic Estimation for Hydraulic Servo Shaking Table by Using Simulated Annealing Algorithm

by Jianjun Yao, Zhenshuai Wan^* and Yu Fu

College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China

Appl. Sci. 2018, 8(4), 524; https://doi.org/10.3390/app8040524 - 29 Mar 2018

Cited by 2 | Viewed by 4248

Abstract

In order to study the anti-shock performance of equipment under different working conditions, a hydraulic servo shaking table is used to replicate the desired motion with high fidelity. However, the sinusoidal acceleration response waveform is not a pure sinusoid due to the inherent [...] Read more.

In order to study the anti-shock performance of equipment under different working conditions, a hydraulic servo shaking table is used to replicate the desired motion with high fidelity. However, the sinusoidal acceleration response waveform is not a pure sinusoid due to the inherent nonlinearities within the system. The generating higher harmonic deteriorates the control performance and leads to system instability. To suppress the harmonic distortion and accurately estimate harmonic information, the harmonic estimation scheme based on simulated annealing algorithm is proposed. The sum of error square between actual value and estimated value is defined as the objective function. The amplitude and phase of each harmonic can be directly extracted when the objective function is minimized. Simulation and experimental results indicate that the proposed algorithm has good convergence performance and high estimation precision. Full article

(This article belongs to the Section Mechanical Engineering)

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16 pages, 3856 KiB

Open AccessArticle

Probabilistic Sensitivity Amplification Control for Lower Extremity Exoskeleton

by Likun Wang^1,2, Zhijiang Du^1,*, Wei Dong¹, Yi Shen² and Guangyu Zhao³

¹ State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China

² School of Astronautics, Harbin Institute of Technology, Harbin 150080, China

³ Weapon Equipment Research Institute, China Ordnance Industries Group, Beijing 102202, China

Appl. Sci. 2018, 8(4), 525; https://doi.org/10.3390/app8040525 - 29 Mar 2018

Cited by 11 | Viewed by 4295

Abstract

To achieve ideal force control of a functional autonomous exoskeleton, sensitivity amplification control is widely used in human strength augmentation applications. The original sensitivity amplification control aims to increase the closed-loop control system sensitivity based on positive feedback without any sensors between the [...] Read more.

To achieve ideal force control of a functional autonomous exoskeleton, sensitivity amplification control is widely used in human strength augmentation applications. The original sensitivity amplification control aims to increase the closed-loop control system sensitivity based on positive feedback without any sensors between the pilot and the exoskeleton. Thus, the measurement system can be greatly simplified. Nevertheless, the controller lacks the ability to reject disturbance and has little robustness to the variation of the parameters. Consequently, a relatively precise dynamic model of the exoskeleton system is desired. Moreover, the human-robot interaction (HRI) cannot be interpreted merely as a particular part of the driven torque quantitatively. Therefore, a novel control methodology, so-called probabilistic sensitivity amplification control, is presented in this paper. The innovation of the proposed control algorithm is two-fold: distributed hidden-state identification based on sensor observations and evolving learning of sensitivity factors for the purpose of dealing with the variational HRI. Compared to the other state-of-the-art algorithms, we verify the feasibility of the probabilistic sensitivity amplification control with several experiments, i.e., distributed identification model learning and walking with a human subject. The experimental result shows potential application feasibility. Full article

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8 pages, 5679 KiB

Open AccessFeature PaperArticle

A Topological View on Optical and Phononic Fabry–Perot Microcavities through the Su–Schrieffer–Heeger Model

by Martin Esmann and Norberto Daniel Lanzillotti-Kimura^*

Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris Sud, Université Paris Saclay, C2N Marcoussis, 91460 Marcoussis, France

Appl. Sci. 2018, 8(4), 527; https://doi.org/10.3390/app8040527 - 30 Mar 2018

Cited by 13 | Viewed by 5899

Abstract

Advances in nanofabrication technologies have enabled the study of acoustic wave phenomena in the technologically relevant GHz–THz range. First steps towards applying concepts from topology in nanophononics were made with the proposal of a new topological acoustic resonator, based on the concept of [...] Read more.

Advances in nanofabrication technologies have enabled the study of acoustic wave phenomena in the technologically relevant GHz–THz range. First steps towards applying concepts from topology in nanophononics were made with the proposal of a new topological acoustic resonator, based on the concept of band inversion. In topology, the Su–Schrieffer–Heeger (SSH) model is the paradigm that accounts for the topological properties of many one-dimensional structures. Both the classical Fabry–Perot resonator and the reported topological resonators are based on Distributed Bragg Reflectors (DBRs). A clear and detailed relation between the two systems, however, is still lacking. Here, we show how a parallelism between the standard DBR-based acoustic Fabry–Perot type cavity and the SSH model of polyacetylene can be established. We discuss the existence of surface modes in acoustic DBRs and interface modes in concatenated DBRs and show that these modes are equivalent to Fabry–Perot type cavity modes. Although it is not possible to assign topological invariants to both acoustic bands enclosing the considered minigap in the nanophononic Fabry–Perot case, the existence of the confined mode in a Fabry–Perot cavity can nevertheless be interpreted in terms of the symmetry inversion of the Bloch modes at the Brillouin zone edge. Full article

(This article belongs to the Special Issue Brillouin Scattering and Optomechanics)

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16 pages, 18219 KiB

Open AccessArticle

Chemical and Molecular Variations in Commercial Epoxide Photoresists for X-ray Lithography

by Vitor Vlnieska^1,2,*, Margarita Zakharova¹

, Martin Börner¹, Klaus Bade¹

, Jürgen Mohr¹ and Danays Kunka¹

¹ Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

² Chemistry Department, Federal University of Paraná, Rua Coronel Francisco Heráclito dos Santos, 100, Jardim das Américas, 81531-980 Curitiba, PR, Brazil

Appl. Sci. 2018, 8(4), 528; https://doi.org/10.3390/app8040528 - 30 Mar 2018

Cited by 6 | Viewed by 4542

Abstract

The quality of high aspect ratio microstructures fabricated by deep X-ray lithography is highly dependent on the photoresist material used and the process parameters applied. Even with photoresists more suitable to this process, it is common to face defects in the final optical [...] Read more.

The quality of high aspect ratio microstructures fabricated by deep X-ray lithography is highly dependent on the photoresist material used and the process parameters applied. Even with photoresists more suitable to this process, it is common to face defects in the final optical components, such as in case of X-ray gratings. The gratings need to be fabricated with critical dimensions on a sub-micrometer and micrometer scale, with periods of few micrometers and heights of hundreds of micrometers to be used in X-ray imaging techniques such as Talbot–Lau Interferometry. During the fabrication process, these features lead to challenges such as mechanical stability, homogeneity, and defect-free grating patterns. Usually, an epoxy-based negative photoresist is used in X-ray lithography, which needs to account for the shrinkage that takes place during polymer crosslinking in order to avoid defects in the final pattern. Nowadays, photoresist material still lacks certain suitable properties (chemical and mechanical) to fabricate gratings of high quality and with acceptable reproducibility. This work presents the results of TGA, FTIR, and MALDI-TOF analysis made on photoresists commercially available and suitable for X-ray lithography. The photoresists presented different profiles regarding the solvent content and oligomers composition, and in the case of some samples, there were high amounts of non-epoxidized oligomers. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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12 pages, 35494 KiB

Open AccessArticle

Three-Dimensional Electromagnetic Mixing Models for Dual-Phase Steel Microstructures

by Weibin Zhou^1,2, Mingyang Lu^2,*

, Ziqi Chen², Lei Zhou³, Liyuan Yin⁴, Qian Zhao⁵, Anthony Peyton²

, Yu Li⁶ and Wuliang Yin^1,2,*

¹ School of Electronic Information and Automation, Tianjin University of Science and Technology, Tianjin 300384, China

² School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, UK

³ Warwick Manufacturing Group (WMG), University of Warwick, Coventry CV4 7AL, UK

⁴ School of Information Engineering and Automation, Kunming University of Science and Technology, Kunming 650221, China

⁵ College of Engineering, Qufu Normal University, Qufu 273165, China

⁶ School of Information Science and Engineering, Lanzhou University, Lanzhou 730000, China

Appl. Sci. 2018, 8(4), 529; https://doi.org/10.3390/app8040529 - 30 Mar 2018

Cited by 14 | Viewed by 3991

Abstract

Linking the ferrite fraction in a dual-phase (DP) steel microstructure and its electromagnetic properties is critical in the effort to develop on-line measurement techniques for phase transformation using electromagnetic (EM) sensors. This paper developed a seamlessly integrated method for generating 3D microstructures and [...] Read more.

Linking the ferrite fraction in a dual-phase (DP) steel microstructure and its electromagnetic properties is critical in the effort to develop on-line measurement techniques for phase transformation using electromagnetic (EM) sensors. This paper developed a seamlessly integrated method for generating 3D microstructures and evaluating their equivalent permeability values. Both the generation of 3D microstructures and evaluation of equivalent permeability have been achieved through custom modelling packages developed by the authors. Voronoi modelling based on the random close packing of spheres (RCPS-VM) was used to precisely control the ferrite fraction in DP steel microstructure, and an equivalent uniform field method for 3D finite element simulation was developed for efficient analysis. Full article

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28 pages, 14450 KiB

Open AccessArticle

A Collaborative Multiplicative Holt-Winters Forecasting Approach with Dynamic Fuzzy-Level Component

by H. M. Emrul Kays¹

, A. N. M. Karim², Mohd Radzi C. Daud¹, Maria L. R. Varela^3,*

, Goran D. Putnik³ and José M. Machado⁴

¹ Department of Manufacturing and Materials Engineering, International Islamic University Malaysia, Jalan Gombak, 53100 Kuala Lumpur, Malaysia

² Faculty of Science and Engineering, Queensland University of Technology, 2 George St, Brisbane 4000, Australia

³ Department of Production and Systems, School of Engineering, University of Minho, 4800-058 Guimarães, Portugal

⁴ Department of Mechanical Engineering, School of Engineering, University of Minho, 4800-058 Guimarães, Portugal

Appl. Sci. 2018, 8(4), 530; https://doi.org/10.3390/app8040530 - 30 Mar 2018

Cited by 23 | Viewed by 6738

Abstract

The adoption of forecasting approaches such as the multiplicative Holt-Winters (MHW) model is preferred in business, especially for the prediction of future events having seasonal and other causal variations. However, in the MHW model the initial values of the time-series parameters and smoothing [...] Read more.

The adoption of forecasting approaches such as the multiplicative Holt-Winters (MHW) model is preferred in business, especially for the prediction of future events having seasonal and other causal variations. However, in the MHW model the initial values of the time-series parameters and smoothing constants are incorporated by a recursion process to estimate and update the level (L_T), growth rate (b_T) and seasonal component (SN_T). The current practice of integrating and/or determining the initial value of L_T is a stationary process, as it restricts the scope of adjustment with the progression of time and, thereby, the forecasting accuracy is compromised, while the periodic updating of L_T is avoided, presumably due to the computational complexity. To overcome this obstacle, a fuzzy logic-based prediction model is developed to evaluate L_T dynamically and to embed its value into the conventional MHW approach. The developed model is implemented in the MATLAB Fuzzy Logic Toolbox along with an optimal smoothing constant-seeking program. The new model, proposed as a collaborative approach, is tested with real-life data gathered from a local manufacturer and also for two industrial cases extracted from literature. In all cases, a significant improvement in forecasting accuracy is achieved. Full article

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30 pages, 55603 KiB

Open AccessArticle

Reverberation-Ray Matrix Analysis and Interpretation of Bending Waves in Bi-Coupled Periodic Multi-Component Beams

by Yongqiang Guo^*

, Liangteng Guo and Zhe Guo

School of Civil Engineering and Mechanics, Lanzhou University, and Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, Lanzhou 730000, China

Appl. Sci. 2018, 8(4), 531; https://doi.org/10.3390/app8040531 - 30 Mar 2018

Cited by 11 | Viewed by 4085

Abstract

Most existing research on periodic beams concerns bending waves in mono-coupled and bi-coupled periodic mono-component beams with the unit cell containing only one beam segment, and very few works on bi-coupled periodic multi-component beams with the unit cell containing more than one beam [...] Read more.

Most existing research on periodic beams concerns bending waves in mono-coupled and bi-coupled periodic mono-component beams with the unit cell containing only one beam segment, and very few works on bi-coupled periodic multi-component beams with the unit cell containing more than one beam segments study the bending waves in structures with only binary unit cells. This paper presents the method of reverberation-ray matrix (MRRM) as an alternative theoretical method for analyzing the dispersion characteristics of bending waves with the wavelength greater than the size of the cross-sections of all components in bi-coupled periodic multi-component beams. The formulation of MRRM is proposed in detail with its numerically well-conditioned property being emphasized, which is validated through comparison of the results obtained with the counterpart results by other methods for exemplified bi-coupled periodic beams. Numerical examples are also provided to illustrate the comprehensive dispersion curves represented as the relations between any two among three in frequency, wavenumber (wavelength) and phase-velocity for summarizing the general features of the dispersion characteristics of bending waves in bi-coupled periodic multi-component beams. The effects of the geometrical and material parameters of constituent beams and the unit-cell configuration on the band structures are also demonstrated by numerical examples. The most innovative finding indicated from the dispersion curves is that the frequencies corresponding to the Brillouin zone boundary may not be the demarcation between the pass-band and stop-band for bending waves in bi-coupled periodic multi-component beams. Full article

(This article belongs to the Section Acoustics and Vibrations)

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27 pages, 4967 KiB

Open AccessArticle

Research on Distributed PV Storage Virtual Synchronous Generator System and Its Static Frequency Characteristic Analysis

by Xiangwu Yan^1,*, Xueyuan Zhang¹

, Bo Zhang¹

, Yanjun Ma¹ and Ming Wu²

¹ Key Laboratory of Distributed Energy Storage and Micro-Grid of Hebei Province, North China Electric Power University, Baoding 071003, China

² China Electric Power Research Institute (CEPRI), Beijing 100000, China

Appl. Sci. 2018, 8(4), 532; https://doi.org/10.3390/app8040532 - 30 Mar 2018

Cited by 15 | Viewed by 5865

Abstract

The increasing penetration rate of grid connected renewable energy power generation reduces the primary frequency regulation capability of the system and poses a challenge to the security and stability of the power grid. In this paper, a distributed photovoltaic (PV) storage virtual synchronous [...] Read more.

The increasing penetration rate of grid connected renewable energy power generation reduces the primary frequency regulation capability of the system and poses a challenge to the security and stability of the power grid. In this paper, a distributed photovoltaic (PV) storage virtual synchronous generator system is constructed, which realizes the external characteristics of synchronous generator/motor. For this kind of input/output bidirectional devices (e.g., renewable power generation/storage combined systems, pumped storage power stations, battery energy storage systems, and vehicle-to-grid electric vehicles), a synthesis analysis method for system power-frequency considering source-load static frequency characteristics (S-L analysis method) is proposed in order to depict the system’s power balance dynamic adjustment process visually. Simultaneously, an inertia matching method is proposed to solve the problem of inertia matching in the power grid. Through the simulation experiment in MATLAB, the feasibility of the distributed PV storage synchronous virtual machine system is verified as well as the effectiveness of S-L analysis method and inertia matching method. Full article

(This article belongs to the Special Issue Renewable Energy 2018)

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27 pages, 18707 KiB

Open AccessArticle

Battery Management System Hardware Concepts: An Overview

by Markus Lelie^1,2,*,†, Thomas Braun^1,2,†, Marcus Knips^1,2,†, Hannes Nordmann^1,2,†, Florian Ringbeck^1,2,†

, Hendrik Zappen^1,2,† and Dirk Uwe Sauer^1,2,3

¹ Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Jaegerstr. 17/19, 52066 Aachen, Germany

² Jara, Juelich Aachen Research Alliance, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

³ Institute for Power Generation and Storage Systems, RWTH Aachen University, Mathieustraße 10, 52074 Aachen, Germany

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 534; https://doi.org/10.3390/app8040534 - 30 Mar 2018

Cited by 216 | Viewed by 45808

Abstract

This paper focuses on the hardware aspects of battery management systems (BMS) for electric vehicle and stationary applications. The purpose is giving an overview on existing concepts in state-of-the-art systems and enabling the reader to estimate what has to be considered when designing [...] Read more.

This paper focuses on the hardware aspects of battery management systems (BMS) for electric vehicle and stationary applications. The purpose is giving an overview on existing concepts in state-of-the-art systems and enabling the reader to estimate what has to be considered when designing a BMS for a given application. After a short analysis of general requirements, several possible topologies for battery packs and their consequences for the BMS’ complexity are examined. Four battery packs that were taken from commercially available electric vehicles are shown as examples. Later, implementation aspects regarding measurement of needed physical variables (voltage, current, temperature, etc.) are discussed, as well as balancing issues and strategies. Finally, safety considerations and reliability aspects are investigated. Full article

(This article belongs to the Special Issue Battery Management and State Estimation)

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19 pages, 18624 KiB

Open AccessArticle

A Thermodynamic Analysis of the Pressure Gain of Continuously Rotating Detonation Combustor for Gas Turbine

by Hongtao Zheng¹, Lei Qi¹, Ningbo Zhao^1,2,*, Zhiming Li¹ and Xiao Liu¹

¹ College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China

² Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA

Appl. Sci. 2018, 8(4), 535; https://doi.org/10.3390/app8040535 - 30 Mar 2018

Cited by 28 | Viewed by 5294

Abstract

Considering the potential applications of continuously rotating detonation (CRD) combustors in gas turbines, this paper performed a numerical investigation into the pressure gain performance of CRD combustors, using methane–air as a reactive mixture and under the operating conditions of a micro gas turbine. [...] Read more.

Considering the potential applications of continuously rotating detonation (CRD) combustors in gas turbines, this paper performed a numerical investigation into the pressure gain performance of CRD combustors, using methane–air as a reactive mixture and under the operating conditions of a micro gas turbine. To analyze the formation process of CRD waves, the variation characteristics of several typical thermodynamic parameters involving thermal efficiency, pressure ratio, and available energy loss were discussed in terms of time and space scales. Numerical results showed that the pressure gain characteristics of the CRD combustors was associated with the corresponding change in Gibbs free energy. Compared to approximate constant pressure-based combustors, usually used in the gas turbines studied, CRD combustors with lower Gibbs free energy loss could offer a significant advantage in terms of pressure ratio. It was found that detonation waves played an important role in increasing pressure ratios but that oblique shock waves caused the loss of extra Gibbs free energy. Due to the changing oblique shock wave height, the effects of CRD combustor axial length on pressure ratios and Gibbs free energy loss were more significant than the effects on detonation wave propagating characteristics and combustion thermal efficiency. When the axial length was changed from 200 mm to 100 mm, the pressure ratio increased by approximately 15.8%. Full article

(This article belongs to the Special Issue Gas Turbine Engine - towards the Future of Power)

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16 pages, 4538 KiB

Open AccessFeature PaperArticle

Evaluation of the Toxin-to-Protein Binding Rates during Hemodialysis Using Sorbent-Loaded Mixed-Matrix Membranes

by Christos S. Stiapis^1,2, Eugene D. Skouras^1,3

, Denys Pavlenko⁴, Dimitrios Stamatialis⁴

and Vasilis N. Burganos^1,*

¹ Institute of Chemical Engineering Sciences (ICE-HT), Foundation for Research and Technology, Hellas (FORTH), Stadiou, Platani, GR-26504 Patras, Greece

² Department of Chemical Engineering, University of Patras, GR-26504 Patras, Greece

³ Department of Mechanical Engineering TE, TEI of Western Greece, GR-26334 Patras, Greece

⁴ (Bio)artificial Organs group, Department of Biomaterials Science and Technology, TechMed Institute for Biomedical Technology and Technical Medicine, University of Twente, 7522 NB Enschede, The Netherlands

Appl. Sci. 2018, 8(4), 536; https://doi.org/10.3390/app8040536 - 31 Mar 2018

Cited by 7 | Viewed by 5462

Abstract

The transport and reaction phenomena that take place in multi-layered mixed-matrix membranes with activated carbon (AC) sorbents that are expected to improve extra-corporeal blood purification, are studied at the macroscopic scale. A model was developed that aims at the description of the removal [...] Read more.

The transport and reaction phenomena that take place in multi-layered mixed-matrix membranes with activated carbon (AC) sorbents that are expected to improve extra-corporeal blood purification, are studied at the macroscopic scale. A model was developed that aims at the description of the removal efficiency of harmful uremic toxins from the blood in the presence of carbon-adsorptive particles and produces results that are aligned with the experimental data. The importance of the generally unknown kinetic rate constants of the association of toxins to albumin is investigated through sensitivity analysis. Matching with further experimental data allowed the extraction of vital kinetic rate constants for key uremic toxins such as indoxyl sulfate (IS) and p-cresyl sulfate (PCS). Moreover, the effects of the plasma composition, as well as of the membrane loading with activated carbon, on the total removal of the protein-bound toxins are quantified and discussed. Full article

(This article belongs to the Special Issue Modeling and Simulations for Membrane Processes of Industrial Interest)

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14 pages, 1471 KiB

Open AccessArticle

A Novel Method for Modeling the Electromagnetic Characteristics of Switched Reluctance Motors

by Cunhe Li

, Guofeng Wang^*, Jian Liu, Yan Li and Yunsheng Fan

School of Information and Technology, Dalian Maritime University, Dalian 116026, China

Appl. Sci. 2018, 8(4), 537; https://doi.org/10.3390/app8040537 - 31 Mar 2018

Cited by 14 | Viewed by 4205

Abstract

Accurate measurement and determination of the electromagnetic characteristics of the switched reluctance motor (SRM) are indispensable to their advanced control and performance analysis. This paper proposes a novel method for modeling the flux-linkage characteristics of SRM. This strategy without rotor locking, includes three [...] Read more.

Accurate measurement and determination of the electromagnetic characteristics of the switched reluctance motor (SRM) are indispensable to their advanced control and performance analysis. This paper proposes a novel method for modeling the flux-linkage characteristics of SRM. This strategy without rotor locking, includes three steps, namely measuring, estimating and calculating steps. In the first step, flux linkage curves with current at four equilibrium positions are obtained by an indirect measurement method. In the second step, the flux-linkage characteristic of SRM in the middle position is estimated by its two adjacent flux-linkage curves. In the third step, a decoupled analytical model based on the five-order Fourier series is developed to construct the entire flux-linkage characteristics. The proposed method can not only eliminate the requirements on rotor clamping devices or position sensors, but also achieve fast and accurate modeling for the electromagnetic characteristics of SRM. Comparative studies are carried out between the proposed method and the conventional rotor clamping method, and the results demonstrate that the proposed method has a good agreement with the conventional rotor clamping method. Moreover, the simulation model is established in MATLAB/Simulink software based on the entire electromagnetic characteristics calculated by the proposed method. The accuracy of the proposed method is further verified by comparing the simulation and experimental results under different operating modes of the SRM. Full article

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21 pages, 2986 KiB

Open AccessArticle

A Hybrid Metaheuristic for Multi-Objective Scientific Workflow Scheduling in a Cloud Environment

by Nazia Anwar^1,2 and Huifang Deng^1,*

¹ School of Computer Science and Engineering, South China University of Technology, Guangzhou 510006, China

² Department of Computer Science, University of Education, Lahore 54770, Pakistan

Appl. Sci. 2018, 8(4), 538; https://doi.org/10.3390/app8040538 - 31 Mar 2018

Cited by 61 | Viewed by 6534

Abstract

Cloud computing has emerged as a high-performance computing environment with a large pool of abstracted, virtualized, flexible, and on-demand resources and services. Scheduling of scientific workflows in a distributed environment is a well-known NP-complete problem and therefore intractable with exact solutions. It becomes [...] Read more.

Cloud computing has emerged as a high-performance computing environment with a large pool of abstracted, virtualized, flexible, and on-demand resources and services. Scheduling of scientific workflows in a distributed environment is a well-known NP-complete problem and therefore intractable with exact solutions. It becomes even more challenging in the cloud computing platform due to its dynamic and heterogeneous nature. The aim of this study is to optimize multi-objective scheduling of scientific workflows in a cloud computing environment based on the proposed metaheuristic-based algorithm, Hybrid Bio-inspired Metaheuristic for Multi-objective Optimization (HBMMO). The strong global exploration ability of the nature-inspired metaheuristic Symbiotic Organisms Search (SOS) is enhanced by involving an efficient list-scheduling heuristic, Predict Earliest Finish Time (PEFT), in the proposed algorithm to obtain better convergence and diversity of the approximate Pareto front in terms of reduced makespan, minimized cost, and efficient load balance of the Virtual Machines (VMs). The experiments using different scientific workflow applications highlight the effectiveness, practicality, and better performance of the proposed algorithm. Full article

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9 pages, 22824 KiB

Open AccessFeature PaperArticle

Organic Light-Emitting Diodes Based on Phthalimide Derivatives: Improvement of the Electroluminescence Properties

by Frédéric Dumur^1,*

, Malika Ibrahim-Ouali² and Didier Gigmes¹

¹ Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire ICR, UMR 7273, F-13397 Marseille, France

² Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, F-13397 Marseille, France

Appl. Sci. 2018, 8(4), 539; https://doi.org/10.3390/app8040539 - 31 Mar 2018

Cited by 6 | Viewed by 5001

Abstract

In this study, a phthalimide-based fluorescent material has been examined as a green emitter for multilayered organic light-emitting diodes (OLEDs). By optimizing the device stacking, a maximum brightness of 28,450 cd/m² at 11.0 V and a maximum external quantum efficiency of 3.11% [...] Read more.

In this study, a phthalimide-based fluorescent material has been examined as a green emitter for multilayered organic light-emitting diodes (OLEDs). By optimizing the device stacking, a maximum brightness of 28,450 cd/m² at 11.0 V and a maximum external quantum efficiency of 3.11% could be obtained. Interestingly, OLEDs fabricated with Fluo-2 presented a 20-fold current efficiency improvement compared to the previous results reported in the literature, evidencing the crucial role of the device stacking in the electroluminescence (EL) performance of a selected emitter. Device lifetime was also examined and an operational stability comparable to that reported for a standard triplet emitter i.e., bis(4-methyl-2,5-diphenyl-pyridine)iridium(III) acetylacetonate [(mdppy)₂Iracac] was evidenced. Full article

(This article belongs to the Special Issue Fluorescence and Phosphorescence in Organic Materials: from Fundamental to OLED Devices)

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13 pages, 68788 KiB

Open AccessArticle

Effects of Thermal Frequency on Microstructures, Mechanical and Corrosion Properties of AA6061 Joints

by Li Jin, Jiaxiang Xue^*, Zhanhui Zhang

and Yu Hu

School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510000, China

Appl. Sci. 2018, 8(4), 540; https://doi.org/10.3390/app8040540 - 2 Apr 2018

Cited by 13 | Viewed by 3105

Abstract

Three thermal frequencies that were designated as 3, 4, and 5 Hz were used to reveal the microstructural evolution, mechanical, and corrosion properties of AA6061-T6 sheets that were welded by double pulsed gas metal arc welding (DP-GMAW) using microstructural observations, microhardness tests, tensile [...] Read more.

Three thermal frequencies that were designated as 3, 4, and 5 Hz were used to reveal the microstructural evolution, mechanical, and corrosion properties of AA6061-T6 sheets that were welded by double pulsed gas metal arc welding (DP-GMAW) using microstructural observations, microhardness tests, tensile tests, bend tests, impact tests, and corrosion tests. A self-developed welding system consisted of a digital multifunctional welder and an arc dynamic waveform wavelet analyzer was chosen to perform welding operations and to record electrical signal waveforms during the welding process. The results show that the process of DP-GMAW was stable, and the weld beads exhibited aesthetic ripples. The ripple distance, the grain size, and porosity of the fusion zone decreased with an increasing thermal frequency. Microhardness and corrosion properties of the weld joint improved when the thermal frequency increased. In addition, all of the joints exhibited excellent bending properties. However, the impact property of the weld joint was lower than that of the BM. It indicated that the low impact energy results of the welded AA6061-T6 sheet were mainly due to the formation of micro-cracks in the fusion zone. Full article

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23 pages, 2595 KiB

Open AccessArticle

Project Robust Scheduling Based on the Scattered Buffer Technology

by Nansheng Pang^*, Huifang Su^* and Yingling Shi

School of Economics and Management, North China Electric Power University, Beijing 102206, China

Appl. Sci. 2018, 8(4), 541; https://doi.org/10.3390/app8040541 - 2 Apr 2018

Cited by 8 | Viewed by 3816

Abstract

The research object in this paper is the sub network formed by the predecessor’s affect on the solution activity. This paper is to study three types of influencing factors from the predecessors that lead to the delay of starting time of the solution [...] Read more.

The research object in this paper is the sub network formed by the predecessor’s affect on the solution activity. This paper is to study three types of influencing factors from the predecessors that lead to the delay of starting time of the solution activity on the longest path, and to analyze the influence degree on the delay of the solution activity’s starting time from different types of factors. On this basis, through the comprehensive analysis of various factors that influence the solution activity, this paper proposes a metric that is used to evaluate the solution robustness of the project scheduling, and this metric is taken as the optimization goal. This paper also adopts the iterative process to design a scattered buffer heuristics algorithm based on the robust scheduling of the time buffer. At the same time, the resource flow network is introduced in this algorithm, using the tabu search algorithm to solve baseline scheduling. For the generation of resource flow network in the baseline scheduling, this algorithm designs a resource allocation algorithm with the maximum use of the precedence relations. Finally, the algorithm proposed in this paper and some other algorithms in previous literature are taken into the simulation experiment; under the comparative analysis, the experimental results show that the algorithm proposed in this paper is reasonable and feasible. Full article

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16 pages, 9417 KiB

Open AccessArticle

An Iterative Load Disaggregation Approach Based on Appliance Consumption Pattern

by Huijuan Wang^1,2

and Wenrong Yang^1,*

¹ State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China

² School of Computer and Remote Sensing Information Technology, North China Institute of Aerospace Engineering, Langfang 065000, China

Appl. Sci. 2018, 8(4), 542; https://doi.org/10.3390/app8040542 - 2 Apr 2018

Cited by 28 | Viewed by 4371

Abstract

Non-intrusive load monitoring (NILM), monitoring single-appliance consumption level by decomposing the aggregated energy consumption, is a novel and economic technology that is beneficial to energy utilities and energy demand management strategies development. Hardware costs of high-frequency sampling and algorithm’s computational complexity hampered NILM [...] Read more.

Non-intrusive load monitoring (NILM), monitoring single-appliance consumption level by decomposing the aggregated energy consumption, is a novel and economic technology that is beneficial to energy utilities and energy demand management strategies development. Hardware costs of high-frequency sampling and algorithm’s computational complexity hampered NILM large-scale application. However, low sampling data shows poor performance in event detection when multiple appliances are simultaneously turned on. In this paper, we contribute an iterative disaggregation approach that is based on appliance consumption pattern (ILDACP). Our approach combined Fuzzy C-means clustering algorithm, which provide an initial appliance operating status, and sub-sequence searching Dynamic Time Warping, which retrieves single energy consumption based on the typical power consumption pattern. Results show that the proposed approach is effective to accurately disaggregate power consumption, and is suitable for the situation where different appliances are simultaneously operated. Also, the approach has lower computational complexity than Hidden Markov Model method and it is easy to implement in the household without installing special equipment. Full article

(This article belongs to the Section Energy Science and Technology)

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11 pages, 15373 KiB

Open AccessFeature PaperArticle

Octave Spanning Supercontinuum in Titanium Dioxide Waveguides

by Kamal Hammani^*

, Laurent Markey, Manon Lamy, Bertrand Kibler, Juan Arocas, Julien Fatome, Alain Dereux, Jean-Claude Weeber and Christophe Finot

Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS—Université Bourgogne Franche-Comté, 9 Avenue Alain Savary, BP 47870, 21078 Dijon CEDEX, France

Appl. Sci. 2018, 8(4), 543; https://doi.org/10.3390/app8040543 - 2 Apr 2018

Cited by 34 | Viewed by 6369

Abstract

We report on the experimental generation of an octave-spanning supercontinuum in a 2.2 cm-long titanium dioxide optical waveguide with two zero dispersion wavelengths. The resulting on-chip supercontinuum reaches the visible wavelength range as well as the mid-infrared region by using a femtosecond fiber [...] Read more.

We report on the experimental generation of an octave-spanning supercontinuum in a 2.2 cm-long titanium dioxide optical waveguide with two zero dispersion wavelengths. The resulting on-chip supercontinuum reaches the visible wavelength range as well as the mid-infrared region by using a femtosecond fiber laser pump at 1.64 µm. Full article

(This article belongs to the Special Issue Mid-Infrared Supercontinuum Sources: Materials, Waveguides and Applications)

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19 pages, 44411 KiB

Open AccessArticle

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

by Xueping Du

, Dongtai Han^* and Qiangmin Zhu

School of Electrical and Power Engineering, China University of Mining and Technology, Xuzhou 221116, China

Appl. Sci. 2018, 8(4), 544; https://doi.org/10.3390/app8040544 - 2 Apr 2018

Cited by 5 | Viewed by 5942

Abstract

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D [...] Read more.

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min. Full article

(This article belongs to the Section Energy Science and Technology)

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14 pages, 41995 KiB

Open AccessArticle

A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers

by Hao Zhang, Wei Fan and Li-Xin Guo^*

School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China

Appl. Sci. 2018, 8(4), 545; https://doi.org/10.3390/app8040545 - 2 Apr 2018

Cited by 17 | Viewed by 7499

Abstract

This paper proposes an approach to investigating the effect of different temperatures and flow velocities on the acoustic performance of silencers in a more accurate and meticulous fashion, based on steady computational results of the flow field inside the silencer using computational fluid [...] Read more.

This paper proposes an approach to investigating the effect of different temperatures and flow velocities on the acoustic performance of silencers in a more accurate and meticulous fashion, based on steady computational results of the flow field inside the silencer using computational fluid dynamics (CFD). This approach can transfer the CFD results—including temperature and flow velocity distribution—to acoustic meshes by mesh mapping. A numerical simulation on the sound field inside the silencer is then performed, using the CFD results as a boundary condition. This approach facilitates the analysis of complex silencer designs such as perforated tube silencers, and the numerical predictions are verified by a comparison with available experimental data. In the case of the three-pass perforated tube silencer of a car, the proposed approach is implemented to calculate the transmission loss (TL) of the silencer at different temperatures and flow velocities. We found that increasing the air temperature shifts the TL curve to a higher frequency and reduces the acoustic attenuation at most frequencies. As the air flow increases, the curve moves to a slightly lower frequency and the acoustic attenuation increases slightly. Additionally, the pressure loss of perforated tube silencers could be calculated according to the total pressure distribution of their inlet and outlet from the steady computational results using CFD. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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16 pages, 1425 KiB

Open AccessArticle

Adaptive Trajectory Tracking Control for Underactuated Unmanned Surface Vehicle Subject to Unknown Dynamics and Time-Varing Disturbances

by Dongdong Mu

, Guofeng Wang^*, Yunsheng Fan

, Bingbing Qiu

and Xiaojie Sun

School of Marine Electrical Engineering, Dalian Maritime University, Dalian 116026, Liaoning, China

Appl. Sci. 2018, 8(4), 547; https://doi.org/10.3390/app8040547 - 2 Apr 2018

Cited by 33 | Viewed by 4681

Abstract

This paper proposes an adaptive trajectory tracking control strategy for underactuated unmanned surface vehicles subject to unknown dynamics and time-varing external disturbances. In short, the goal of this paper is to provide a control strategy that allows an underactuated unmanned surface vehicle to [...] Read more.

This paper proposes an adaptive trajectory tracking control strategy for underactuated unmanned surface vehicles subject to unknown dynamics and time-varing external disturbances. In short, the goal of this paper is to provide a control strategy that allows an underactuated unmanned surface vehicle to track a time dependent trajectory. First, a first-order sliding surface is introduced into the design of surge control law to converge to surge tracking error, and then a second-order sliding surface is hired to design yaw control law to deal with sway motion tracking error. Meanwhile, neural network minimum learning parameter method, which has a smaller amount of computation than a multilayer neural network, is employed to preserve the control law robustness against unknown dynamics and time-varing disturbances induced by wind, waves and ocean currents. Furthermore, much effort is made to obtain uniform ultimate bounded stability for the closed-loop control system. Finally, the numerical simulation experiments of straight line and circle trajectory tracking have been given to prove the correctness and feasibility of the proposed control strategy. Full article

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20 pages, 29142 KiB

Open AccessArticle

A Self-Recovery Fragile Image Watermarking with Variable Watermark Capacity

by Chengyou Wang

, Heng Zhang

and Xiao Zhou^*

School of Mechanical, Electrical and Information Engineering, Shandong University, Weihai 264209, China

Appl. Sci. 2018, 8(4), 548; https://doi.org/10.3390/app8040548 - 2 Apr 2018

Cited by 28 | Viewed by 5024

Abstract

Currently, the watermark capacity of most self-recovery fragile image watermarking schemes is fixed. That means for smooth regions and texture regions, the length of watermark information is always the same. However, it is impractical since more recovery information is needed for the recovery [...] Read more.

Currently, the watermark capacity of most self-recovery fragile image watermarking schemes is fixed. That means for smooth regions and texture regions, the length of watermark information is always the same. However, it is impractical since more recovery information is needed for the recovery of texture regions. In this paper, a self-recovery fragile image watermarking with variable watermark capacity is proposed. Based on the characteristic of singular value decomposition (SVD), a new block classification method is introduced. The image blocks are classified into smooth blocks and texture blocks. For smooth blocks, the average pixel values are adopted as the recovery information to recover the tampered blocks, while for texture blocks, the quantized and coded DCT coefficients are adopted as the recovery information. After encrypted by binary pseudo-random sequence, the recovery watermark of each block is embedded into its mapping block. In the detection side, the three-level detection mechanism is applied to detect and locate the tampered regions. The experimental results prove that the proposed method achieves good tamper detection results, and the recovered image has better image quality than other self-recovery fragile watermarking methods. Full article

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13 pages, 50419 KiB

Open AccessArticle

Prediction of the Tensile Load of Drilled CFRP by Artificial Neural Network

by Burak Yenigun^1,*

and Erol Kilickap²

¹ Department of Mechanical Engineering, Batman University, Batman 72100, Turkey

² Department of Mechanical Engineering, Dicle University, Diyarbakır 21100, Turkey

Appl. Sci. 2018, 8(4), 549; https://doi.org/10.3390/app8040549 - 2 Apr 2018

Cited by 10 | Viewed by 4345

Abstract

The application areas of carbon fiber reinforced plastics (CFRP) have been increasing day by day. The machining of CFRP with incorrect machining parameters leads in huge loss cost and time. Therefore, it is very important that the composite materials are machined with correct [...] Read more.

The application areas of carbon fiber reinforced plastics (CFRP) have been increasing day by day. The machining of CFRP with incorrect machining parameters leads in huge loss cost and time. Therefore, it is very important that the composite materials are machined with correct machining parameters. The aim of this paper is to examine the influence of drilling parameters on tensile load after drilling of CFRP. The drilling operations were carried out on Computer Numerical Control (CNC) by Tungsten Carbide (WC), High Speed Steel (HSS) and Brad Spur type drill bits with spindle speeds of 1000, 3000 and 5000 rpm and feed rates of 0.05, 0.10 and 0.15 mm/rev. The results indicate that the surface roughness, delamination and thrust force, were affected by drilling parameters therefore tensile load was also affected by the same parameters. It was observed that increase in surface roughness, delamination and thrust force all lead to the decrease of tensile load of CFRP. If the correct drilling parameters are selected; the decrease in tensile load of CFRP can be saved up to 25%. Furthermore, an artificial neural network (ANN) model has been used to predict of tensile load. The results of the ANN model are in close agreement with the experimental results. Full article

(This article belongs to the Section Mechanical Engineering)

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16 pages, 14385 KiB

Open AccessArticle

A High-Performance Implementation of an IoT System Using DPDK

by JuGeon Pak and KeeHyun Park^*

Computer Engineering Department, Keimyung University, Daegu 1095, Korea

Appl. Sci. 2018, 8(4), 550; https://doi.org/10.3390/app8040550 - 2 Apr 2018

Cited by 13 | Viewed by 7637

Abstract

An IoT (Internet of Things) system typically encompasses a number of devices and sensors and is required to process a large number of messages at a high speed. To address this requirement, we propose a dual plane architecture, which consists of a control [...] Read more.

An IoT (Internet of Things) system typically encompasses a number of devices and sensors and is required to process a large number of messages at a high speed. To address this requirement, we propose a dual plane architecture, which consists of a control plane and a data plane. The control plane processes signaling messages and the data plane takes charge of processing user data messages. This allows the system to process messages separately and simultaneously in the different planes according to the type of incoming message. In this paper, we present the each plane’s role and how messages are processed in the different planes. We also present the interworking method between both planes. To verify the proposed architecture, we implement and apply the architecture to our previous single plane IoT system. We also compare the performance of the proposed system with that of the single plane IoT system in terms of throughput and packet loss ratio. The results reveal that the performance of the proposed architecture is much higher than that of the previous single plane IoT systems. The results prove that the proposed architecture is highly appropriate for IoT environments. Full article

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14 pages, 2960 KiB

Open AccessArticle

Optimal Piezoelectric Potential Distribution for Controlling Multimode Vibrations

by Fabio Botta^*, Andrea Scorza

and Andrea Rossi

Dipartimento di Ingegneria, Università degli Studi Roma Tre, Via della Vasca Navale, 79, 00146 Roma, Italy

Appl. Sci. 2018, 8(4), 551; https://doi.org/10.3390/app8040551 - 3 Apr 2018

Cited by 18 | Viewed by 3303

Abstract

Vibration damping is prominent in engineering; in fact, vibrations are related to many phenomena (e.g., the fatigue of structural elements). The advent of smart materials has significantly increased the number of available solutions in this field. Among smart materials, piezoelectric materials are most [...] Read more.

Vibration damping is prominent in engineering; in fact, vibrations are related to many phenomena (e.g., the fatigue of structural elements). The advent of smart materials has significantly increased the number of available solutions in this field. Among smart materials, piezoelectric materials are most promising. However, their efficiency depends on their placement. There are many studies on their optimal placement for damping a particular mode, but few account for multimodal vibrations damping. In a previous work, an analytical method was proposed to find the optimal placement of piezoelectric plates to control the multimode vibrations of a cantilever beam. In this study, the efficiency of the above method has been improved, considering all plates active simultaneously, regardless of the eigenmodes that are excited, and changing, instead of the plates, the potential distribution. The method results indicate the optimal potential distribution for different excited eigenmodes. The results have been compared with those obtained by experimental tests and numerical simulations, exhibiting very good agreement. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 6404 KiB

Open AccessArticle

Pigment Dyeing of Atmospheric Pressure Plasma-Treated Cotton Fabric

by Chi-Wai Kan^* and Wai-Shan Man

Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Appl. Sci. 2018, 8(4), 552; https://doi.org/10.3390/app8040552 - 3 Apr 2018

Cited by 9 | Viewed by 3746

Abstract

In this work, the effect of atmospheric pressure plasma treatment on improving the application of pigment dyeing in cotton was investigated. The colour-related properties such as (i) colour yield; (ii) colour levelness; (iii) crocking fastness; and (iv) dry-cleaning fastness of the pigment-dyed cotton [...] Read more.

In this work, the effect of atmospheric pressure plasma treatment on improving the application of pigment dyeing in cotton was investigated. The colour-related properties such as (i) colour yield; (ii) colour levelness; (iii) crocking fastness; and (iv) dry-cleaning fastness of the pigment-dyed cotton fabric were determined and evaluated. Atmospheric pressure plasma under different combinations of operational parameters was used for treating 100% ready-for-dyeing cotton fabric. The atmospheric pressure plasma-treated cotton fabric was dyed with yellow pigment by the pad-dyeing method, and the pigment-dyeing solution concentrations were 1 g/L and 5 g/L. Experimental results revealed that colour yield of the yellow pigment-dyed cotton sample improved. The crocking and dry-cleaning fastness properties also improved. In addition, prediction model equations were developed for 1 g/L and 5 g/L pigment dyeing based on multiple linear regression, and the measured colour yield was close to the predicted colour yield. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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14 pages, 2710 KiB

Open AccessArticle

Experimental Study of Damage Development in Salt Rock under Uniaxial Stress Using Ultrasonic Velocity and Acoustic Emissions

by Haoran Li^1,2,3,*, Zhikai Dong¹, Yun Yang³, Bo Liu¹, Mingyi Chen¹ and Wenjun Jing⁴

¹ Structural Health Monitoring and Control Institute, Shijiazhuang Tiedao University, Shijiazhuang 050043, Hebei, China

² State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, Hubei, China

³ Department of Energy and Mineral Engineering, G3 Center and EMS Energy Institute, Pennsylvania State University, University Park, PA 16802, USA

⁴ College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266555, China

Appl. Sci. 2018, 8(4), 553; https://doi.org/10.3390/app8040553 - 4 Apr 2018

Cited by 16 | Viewed by 4566

Abstract

Ultrasonic waves and acoustic emissions (AE) are important technologies to reveal rock damage. However, few studies have simultaneously monitored both types of data in the same experiment because of limitations on the experimental apparatus. In this study, an integrated ultrasonic wave and AE [...] Read more.

Ultrasonic waves and acoustic emissions (AE) are important technologies to reveal rock damage. However, few studies have simultaneously monitored both types of data in the same experiment because of limitations on the experimental apparatus. In this study, an integrated ultrasonic wave and AE testing device was developed to investigate the deformation characteristics and damage development of salt rock. Fracture experiments under uniaxial compression were carried out on three samples from the Jintan Salt Mine, Jiangsu Province, China. The deformation process can be divided into five stages. In the compression fissure and linear deformation stages, P- and S-waves rose slightly to stability, and acoustic emission activity was weak (0.04% and 2.66%, respectively). Subsequently, S-wave velocity slowly declined and AE events become more active, with about 13.8% of the total in the stabilized-growth cracks stage. When the salt rock entered the accelerated-growth cracks stage, AE events increased to 75.27%; with features of an earthquake swarm, the velocities of P- and S-waves began to fall significantly. After the peak stress, salt rock produced only a small number of AE events. The beginning stress of rock damage and dilatancy were about 42–50% and 62–67% of the uniaxial compressive strength, respectively. The ultrasonic wave velocity ratio, Ib-value, and r-value effectively predicted rock failure, but the r-value was superior owing to its sensitivity and ease of measurement. Full article

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17 pages, 10093 KiB

Open AccessArticle

Low-Rate Non-Intrusive Load Disaggregation with Graph Shift Quadratic Form Constraint

by Bing Qi, Liya Liu^* and Xin Wu

School of Electric and Electronic Engineering, North China Electric Power University, Changping District, Beijing 102206, China

Appl. Sci. 2018, 8(4), 554; https://doi.org/10.3390/app8040554 - 4 Apr 2018

Cited by 19 | Viewed by 3622

Abstract

Non-intrusive load monitoring (NILM) is a cost-effective technique for extracting device-level energy consumption information by monitoring the aggregated signal at the entrance of the electric power. With the large-scale deployment of smart metering, NILM should ideally be designed to operate purely on the [...] Read more.

Non-intrusive load monitoring (NILM) is a cost-effective technique for extracting device-level energy consumption information by monitoring the aggregated signal at the entrance of the electric power. With the large-scale deployment of smart metering, NILM should ideally be designed to operate purely on the low-rate data from smart meters. In this paper, an approach based on Graph Shift Quadratic Form constrained Active Power Disaggregation (GSQF-APD) is proposed, which is built upon matrix factorization and introduces graph shift quadratic form constraint according to piecewise smoothness of the power signal. In addition, a two-step iterative optimization method is designed to solve this problem. The first step minimizes the regularization term to find the signal with minimum variation, and then the second step uses the simulated annealing (SA) algorithm to iteratively minimize the objective function and constraint based on the total graph variation minimizer. Using one open-access dataset, the strength of GSQF-APD is demonstrated through three sets of experiments. The numerical results show the superior performance of GSQF-APD, with Graph Laplacian Quadratic Form constrained Active Power Disaggregation (GLQF-APD) and the state-of-the-art NILM methods as benchmarks. Full article

(This article belongs to the Section Energy Science and Technology)

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16 pages, 25925 KiB

Open AccessArticle

A Reliable Scheme for Synchronizing Multimedia Data Streams under Multicasting Environment

by Rab Nawaz Jadoon^1,2

, WuYang Zhou^1,*, Faizan Ul Haq³, Jawad Shafi², Iftikhar Ahmed Khan²

and Waqas Jadoon²

¹ School of Information Science and Technology, University of Science and Technology of China, Hefei 230000, China

² Department of Computer Science, COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan

³ Ericsson Research Corporate Unit, 97231 Luleå, Sweden

Appl. Sci. 2018, 8(4), 556; https://doi.org/10.3390/app8040556 - 4 Apr 2018

Cited by 2 | Viewed by 4876

Abstract

An emerging requirement in multimedia applications over the Internet is the provisioning of synchronized play out of multimedia streams on all the ultimate receivers. Most multimedia applications use real-time transport protocol/real-time control protocol (RTP/RTCP) to transport multimedia data over the internet. Internet Protocol [...] Read more.

An emerging requirement in multimedia applications over the Internet is the provisioning of synchronized play out of multimedia streams on all the ultimate receivers. Most multimedia applications use real-time transport protocol/real-time control protocol (RTP/RTCP) to transport multimedia data over the internet. Internet Protocol (IP) network incurs a loss and/or delay of media packets resulting in distortions at receivers that can be perceived by the user. These distortions need to be removed before data is presented to the end user. To handle such issues inter-stream and intra-stream synchronization algorithms were developed by the researcher using RTP/RTCP protocols. These schemes could not work under multicasting environment properly. In this paper, we have presented an algorithm based on RTP/RTCP protocol that achieved synchronized playout of multimedia data under multicasting environment. The proposed scheme offers a modification in RTCP and usage of the Network Time Protocol (NTP) as a source of the common clock to achieve synchronized playout of multimedia data on multiple devices at the same time. We have implemented and tested our algorithm in Ericson Research Corporate Unit, Lulea, Sweden. Implementation results show that the proposed algorithm delivered accurately synchronized playout of multimedia data under all the possible scenarios defined in the experimental setup. Full article

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20 pages, 25002 KiB

Open AccessArticle

Development of Piezoelectric Harvesters with Integrated Trimming Devices

by Alberto Doria^*, Cristian Medè, Giulio Fanti, Daniele Desideri, Alvise Maschio and Federico Moro

Department of Industrial Engineering, University of Padova, 35131 Padova, Italy

Appl. Sci. 2018, 8(4), 557; https://doi.org/10.3390/app8040557 - 4 Apr 2018

Cited by 11 | Viewed by 5127

Abstract

Piezoelectric cantilever harvesters have a large power output at their natural frequency, but in some applications the frequency of ambient vibrations is different from the harvester’s frequency and/or ambient vibrations are periodic with some harmonic components. To cope with these operating conditions harvesters [...] Read more.

Piezoelectric cantilever harvesters have a large power output at their natural frequency, but in some applications the frequency of ambient vibrations is different from the harvester’s frequency and/or ambient vibrations are periodic with some harmonic components. To cope with these operating conditions harvesters with integrated trimming devices (ITDs) are proposed. Some prototypes are developed with the aid of an analytical model and tested with an impulsive method. Results show that a small trimming device can lower the main resonance frequency of a piezoelectric harvester of the same extent as a larger tip mass and, moreover, it generates at high frequency a second resonance peak. A multi-physics numerical finite element (FE) model is developed for predicting the generated power and for performing a stress-strain analysis of harvesters with ITDs. The numerical model is validated on the basis of the experimental results. Several configurations of ITDs are conceived and studied. Numerical results show that the harvesters with ITDs are able to generate relevant power at two frequencies, owing to the particular shape of the modes of vibration. The stress in the harvesters with ITDs is smaller than the stress in the harvester with a tip mass trimmed to the same frequency. Full article

(This article belongs to the Special Issue Piezoelectric Energy Harvesting: Materials, Devices and Application)

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18 pages, 27052 KiB

Open AccessArticle

An Evolutionary-Based MPPT Algorithm for Photovoltaic Systems under Dynamic Partial Shading

by Alberto Dolara^*, Francesco Grimaccia

, Marco Mussetta

, Emanuele Ogliari and Sonia Leva

Department of Energy, Politecnico di Milano, via La Masa 34, 20156 Milano, Italy

Appl. Sci. 2018, 8(4), 558; https://doi.org/10.3390/app8040558 - 4 Apr 2018

Cited by 46 | Viewed by 5665

Abstract

The increase of renewable energy usage in the last two decades, in particular photovoltaic (PV) systems, has opened up different solar plant configurations that need to operate and properly perform in terms of efficient power transfer with respect to all of the involved [...] Read more.

The increase of renewable energy usage in the last two decades, in particular photovoltaic (PV) systems, has opened up different solar plant configurations that need to operate and properly perform in terms of efficient power transfer with respect to all of the involved components, such as inverters, grid interface, storage, and other electrical loads. In such applications, the power characteristics of the plant modules all together represent the main components that are responsible for power extraction, depending on both external and internal factors. Conventional maximum power point tracking techniques may not have a proper conversion efficiency under particular external dynamic conditions. This paper proposes an evolutionary-based maximum power point tracking algorithm suitable to operate under dynamic partial shading conditions and compares its performance with classical maximum power point tracking methods in order to evaluate their conversion efficiency in partial shading scenarios with relevant and dynamic changes in the environmental conditions. Simulations taking into account the different dynamic shading conditions were carried out to prove the effectiveness and limitations of the proposed approach with respect to classical algorithms. Full article

(This article belongs to the Special Issue Computational Intelligence in Photovoltaic Systems)

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17 pages, 1963 KiB

Open AccessArticle

Heat Transfer in Non-Newtonian Flows by a Hybrid Immersed Boundary–Lattice Boltzmann and Finite Difference Method

by Li Wang^* and Fang-Bao Tian^*

School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2600, Australia

Appl. Sci. 2018, 8(4), 559; https://doi.org/10.3390/app8040559 - 4 Apr 2018

Cited by 35 | Viewed by 6507

Abstract

A hybrid immersed boundary–lattice Boltzmann and finite difference method for fluid–structure interaction and heat transfer in non-Newtonian flow is presented. The present numerical method includes four parts: fluid solver, heat transfer solver, structural solver, and immersed boundary method for fluid–structure interaction and heat [...] Read more.

A hybrid immersed boundary–lattice Boltzmann and finite difference method for fluid–structure interaction and heat transfer in non-Newtonian flow is presented. The present numerical method includes four parts: fluid solver, heat transfer solver, structural solver, and immersed boundary method for fluid–structure interaction and heat transfer. Specifically, the multi-relaxation time lattice Boltzmann method is adopted for the dynamics of non-Newtonian flow, with a geometry-adaptive technique to enhance the computational efficiency and immersed boundary method to achieve no-slip boundary conditions. The heat transfer equation is spatially discretized by a second-order up-wind scheme for the convection term, a central difference scheme for the diffusion term, and a second-order difference scheme for the temporal term. The structural dynamics is numerically solved using a finite difference method. The major contribution of this work is the integration of spatial adaptivity, thermal finite difference method, and fluid flow immersed boundary-lattice Boltzmann method. Several benchmark problems including the developing flow of non-Newtonian fluid in a channel, non-Newtonian fluid flow and heat transfer around a stationary cylinder and flow around a stationary cylinder with a detached filament are used to validate the present method and developed solver. The good agreements achieved by the present method with the published data show that the present extension is an efficient way for fluid–structure interaction and heat transfer involving non-Newtonian fluid. The heat transfer around an oscillating cylinder in non-Newtonian fluid flow at Reynolds number of 100 is also numerically studied using the present solver, considering the effects of the oscillating frequency and amplitude. The results may be used to expand the currently limited database of fluid–structure interaction and heat transfer benchmark studies. Full article

(This article belongs to the Special Issue Development and Applications of Kinetic Solvers for Complex Flows)

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13 pages, 26998 KiB

Open AccessArticle

Development of ELISA-Like Fluorescence Assay for Melamine Detection Based on Magnetic Dummy Molecularly Imprinted Polymers

by Guangyang Liu^1,2,†, Yongxin She^2,†, Sihui Hong², Jing Wang^2,* and Donghui Xu^1,*

¹ Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Key Laboratory of Vegetables Quality and Safety Control, Ministry of Agriculture of China, Ministry of Agriculture, Beijing 100081, China

² Institute of Quality Standard and Testing Technology for Agro Products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agrifood Safety and Quality, Ministry of Agriculture of China, Beijing 100081, China

^† Co-authors with equal contributions.

Appl. Sci. 2018, 8(4), 560; https://doi.org/10.3390/app8040560 - 4 Apr 2018

Cited by 19 | Viewed by 4871

Abstract

We present a directly competitive fluorescence assay for highly sensitive detection of melamine in milk using magnetic dummy molecularly imprinted polymers (MDMIPs). The detection principle is based on competitive binding between the fluorescent label and melamine on the MDMIPs. The fluorescent label was [...] Read more.

We present a directly competitive fluorescence assay for highly sensitive detection of melamine in milk using magnetic dummy molecularly imprinted polymers (MDMIPs). The detection principle is based on competitive binding between the fluorescent label and melamine on the MDMIPs. The fluorescent label was obtained by combining fluorescein isothiocyanate (FITC) with melamine in ethanol and water. MDMIPs were prepared on the surface of Fe₃O₄@SiO₂ nanoparticles using 2,4-diamino-6-methyl-1,3,5-triazine as dummy template. The MDMIPs were characterized and their adsorption capacity was evaluated based on their static adsorption and Scatchard analysis. Results suggest that MDMIPs were successfully coated on the Fe₃O₄@SiO₂ surface and had a core–shell structure. Adsorption experiments suggested that the MDMIPs had higher specific recognition capacities for melamine and FITC–melamine (FITC-Mel) than did magnetic dummy molecularly non-imprinted polymers. Competitive binding between FITC-Mel and melamine was performed under the optimum conditions to determine melamine quantitatively. The linear range of this fluorescence assay was 0.1–20 mg/L for melamine detection. The detection limit was 0.05 mg/L in negative milk samples. The assay was also successfully employed to detect melamine in spiked milk samples, with satisfactory recoveries, i.e., between 70.2% and 92.7%. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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19 pages, 34192 KiB

Open AccessArticle

A Novel Tempogram Generating Algorithm Based on Matching Pursuit

by Wenming Gui^1,*

, Yao Sun^1,*, Yuting Tao¹, Yanping Li², Lun Meng³ and Jinglan Zhang⁴

¹ School of Software Engineering, Jinling Institute of Technology, Nanjing 211169, China

² Nanjing University of Posts and Telecommunications, Nanjing 210003, China

³ College of Public Administration, Hohai University, Nanjing 210098, China

⁴ Science and Engineering Faculty, Queensland University of Technology, Queensland 4001, Australia

Appl. Sci. 2018, 8(4), 561; https://doi.org/10.3390/app8040561 - 4 Apr 2018

Viewed by 4633

Abstract

Tempogram is one of the most useful representations for tempo, which has many applications, such as music tempo estimation, music structure analysis, music classification, and beat tracking. This paper presents a novel tempogram generating algorithm, which is based on matching pursuit. First, a [...] Read more.

Tempogram is one of the most useful representations for tempo, which has many applications, such as music tempo estimation, music structure analysis, music classification, and beat tracking. This paper presents a novel tempogram generating algorithm, which is based on matching pursuit. First, a tempo dictionary is designed in the light of the characteristics of tempo and note onset, then matching pursuit based on the tempo dictionary is executed on the resampled novelty curve, and finally the tempogram is created by assembling the coefficients of matching pursuit. The tempogram created by this algorithm has better resolution, stronger sparsity, and flexibility than those of the traditional algorithms. We demonstrate the properties of the algorithm through experiments and provide an application example for tempo estimation. Full article

(This article belongs to the Special Issue Digital Audio and Image Processing with Focus on Music Research)

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19 pages, 2942 KiB

Open AccessArticle

Fault Studies and Distance Protection of Transmission Lines Connected to DFIG-Based Wind Farms

by Bin Li¹, Junyu Liu^1,*, Xin Wang² and Lili Zhao³

¹ Smart Grid Key Laboratory of Ministry of Education, Tianjin University, Tianjin 300072, China

² Maintenance Company of Tianjin Electric Power Company, Tianjin 300250, China

³ Electric Power Dispatching Control Center of Guizhou Power Grid Company, Guiyang 550002, China

Appl. Sci. 2018, 8(4), 562; https://doi.org/10.3390/app8040562 - 5 Apr 2018

Cited by 45 | Viewed by 8427

Abstract

Doubly fed induction generator (DFIG) based wind farms are being increasingly integrated into power grids with transmission lines, and distance protection is usually used as either the main or the backup protection for the transmission line. This paper analyzes the composition of a [...] Read more.

Doubly fed induction generator (DFIG) based wind farms are being increasingly integrated into power grids with transmission lines, and distance protection is usually used as either the main or the backup protection for the transmission line. This paper analyzes the composition of a DFIG short circuit current and indicates the existence of a rotor speed frequency component. By analyzing several real fault cases of the DFIG-based wind farms connected to transmission lines, the weak power supply system and current frequency deviation of the wind farm side are illustrated. When a fault occurs on the transmission line, the short circuit current on the wind farm side is small and its frequency may no longer be nominal due to the existence of rotor speed frequency component, whereas the voltage frequency remains nominal frequency because of the grid support. As a result, the conventional distance protection cannot accurately measure the impedance, which can result in unnecessary circuit breaker tripping. Therefore, a time-domain distance protection method combined with the least-squares algorithm is proposed to address the problem. The efficacy of the proposed method is validated with real fault cases and simulation. Full article

(This article belongs to the Special Issue Large Grid-Connected Wind Turbines)

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17 pages, 2751 KiB

Open AccessArticle

A Modified Method for Evaluating Sustainable Transport Solutions Based on AHP and Dempster–Shafer Evidence Theory

by Luyuan Chen¹ and Xinyang Deng^2,*

¹ School of Computer, Northwestern Polytechnical University, Xi’an 710072, China

² School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China

Appl. Sci. 2018, 8(4), 563; https://doi.org/10.3390/app8040563 - 5 Apr 2018

Cited by 70 | Viewed by 6684

Abstract

With the challenge of transportation environment, a large amount of attention is paid to sustainable mobility worldwide, thus bringing the problem of the evaluation of sustainable transport solutions. In this paper, a modified method based on analytical hierarchy process (AHP) and Dempster–Shafer evidence [...] Read more.

With the challenge of transportation environment, a large amount of attention is paid to sustainable mobility worldwide, thus bringing the problem of the evaluation of sustainable transport solutions. In this paper, a modified method based on analytical hierarchy process (AHP) and Dempster–Shafer evidence theory (D-S theory) is proposed for evaluating the impact of transport measures on city sustainability. AHP is adapted to determine the weight of sustainability criteria while D-S theory is used for data fusion of the sustainability assessment. A Transport Sustainability Index (TSI) is presented as a primary measure to determine whether transport solutions have a positive impact on city sustainability. A case study of car-sharing is illustrated to show the efficiency of our proposed method. Our modified method has two desirable properties. One is that the BPA is generated with a new modification framework of evaluation levels, which can flexibly manage uncertain information. The other is that the modified method has excellent performance in sensitivity analysis. Full article

(This article belongs to the Special Issue Smart Sustainable Manufacturing Systems)

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16 pages, 24466 KiB

Open AccessFeature PaperArticle

Detection of Azo Dyes in Curry Powder Using a 1064-nm Dispersive Point-Scan Raman System

by Sagar Dhakal¹, Kuanglin Chao^1,*, Walter Schmidt¹, Jianwei Qin¹, Moon Kim¹ and Qing Huang²

¹ United States Department of Agriculture/Agricultural Research Service, Environmental Microbial and Food Safety Laboratory, Bldg. 303, Beltsville Agricultural Research Center East, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA

² Chinese Academy of Sciences (CAS), 350 Shushanhu Road, P.O. Box 1138, Hefei 230031, China

Appl. Sci. 2018, 8(4), 564; https://doi.org/10.3390/app8040564 - 5 Apr 2018

Cited by 26 | Viewed by 6463

Abstract

Curry powder is extensively used in Southeast Asian dishes. It has been subject to adulteration by azo dyes. This study used a newly developed 1064 nm dispersive point-scan Raman system for detection of metanil yellow and Sudan-I contamination in curry powder. Curry powder [...] Read more.

Curry powder is extensively used in Southeast Asian dishes. It has been subject to adulteration by azo dyes. This study used a newly developed 1064 nm dispersive point-scan Raman system for detection of metanil yellow and Sudan-I contamination in curry powder. Curry powder was mixed with metanil yellow and (separately) with Sudan-I, at concentration levels of 1%, 3%, 5%, 7%, and 10% (w/w). Each sample was packed into a nickel-plated sample container (25 mm × 25 mm × 1 mm). One Raman spectral image of each sample was acquired across the 25 mm × 25 mm surface area. Intensity threshold value was applied to the spectral images of Sudan-I mixtures (at 1593 cm⁻¹) and metanil yellow mixtures (at 1147 cm⁻¹) to obtain binary detection images. The results show that the number of detected adulterant pixels is linearly correlated with the sample concentration (R² = 0.99). The Raman system was further used to obtain a Raman spectral image of a curry powder sample mixed together with Sudan-I and metanil yellow, with each contaminant at equal concentration of 5% (w/w). The multi-component spectra of the mixture sample were decomposed using self-modeling mixture analysis (SMA) to extract pure component spectra, which were then identified as matching those of Sudan-I and metanil yellow using spectral information divergence (SID) values. The results show that the 1064 nm dispersive Raman system is a potential tool for rapid and nondestructive detection of multiple chemical contaminants in the complex food matrix. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

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8 pages, 16855 KiB

Open AccessArticle

Facile Fabrication of 3D Hierarchically Porous Carbon Foam as Supercapacitor Electrode Material

by Yunfang Gao^*, Liangpo Cai, Xin Xu and Jie Ying

State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China

Appl. Sci. 2018, 8(4), 565; https://doi.org/10.3390/app8040565 - 5 Apr 2018

Cited by 7 | Viewed by 4673

Abstract

A hierarchically porous 3D starch-derived carbon foam (SCF) with a high specific surface area (up to 1693 m²·g⁻¹) was first prepared by a facile solvothermal treatment, in which Na₂CO₃ is used as both the template and [...] Read more.

A hierarchically porous 3D starch-derived carbon foam (SCF) with a high specific surface area (up to 1693 m²·g⁻¹) was first prepared by a facile solvothermal treatment, in which Na₂CO₃ is used as both the template and activating agent. The hierarchically porous structure and high specific area endow the SCF with favorable electrochemical properties such as a high specific capacitance of 179.6 F·g⁻¹ at 0.5 A·g⁻¹ and a great rate capability and cycling stability, which suggest that the material can be a promising candidate for energy storage applications. Full article

(This article belongs to the Special Issue Electrode Materials for Lithium-ion Batteries/Super-capacitors)

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15 pages, 22141 KiB

Open AccessArticle

Predicting Output Power for Nearshore Wave Energy Harvesting

by Henock Mamo Deberneh and Intaek Kim^*

Department of Information and Communications Engineering, Myongji University, 116 Myongji-ro, Yongin, Gyeonggi 17058, Korea

Appl. Sci. 2018, 8(4), 566; https://doi.org/10.3390/app8040566 - 5 Apr 2018

Cited by 9 | Viewed by 6920

Abstract

Energy harvested from a Wave Energy Converter (WEC) varies greatly with the location of its installation. Determining an optimal location that can result in maximum output power is therefore critical. In this paper, we present a novel approach to predicting the output power [...] Read more.

Energy harvested from a Wave Energy Converter (WEC) varies greatly with the location of its installation. Determining an optimal location that can result in maximum output power is therefore critical. In this paper, we present a novel approach to predicting the output power of a nearshore WEC by characterizing ocean waves using floating buoys. We monitored the movement of the buoys using an Arduino-based data collection module, including a gyro-accelerometer sensor and a wireless transceiver. The collected data were utilized to train and test prediction models. The models were developed using machine learning algorithms: SVM, RF and ANN. The results of the experiments showed that measurements from the data collection module can yield a reliable predictor of output power. Furthermore, we found that the predictors work better when the regressors are combined with a classifier. The accuracy of the proposed prediction model suggests that it could be extremely useful in both locating optimal placement for wave energy harvesting plants and designing the shape of the buoys used by them. Full article

(This article belongs to the Special Issue Applications of Artificial Neural Networks for Energy Systems)

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18 pages, 2523 KiB

Open AccessArticle

Peak Load Regulation and Cost Optimization for Microgrids by Installing a Heat Storage Tank and a Portable Energy System

by Hong Zhang^1,2,*, Qian Zhang¹, Taorong Gong², Hao Sun¹ and Xin Su³

¹ Department of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China

² China Electric Power Research Institute, Beijing 100192, China

³ Yingkou Electric Power Supply Company of State Grid, Yingkou 115000, China

Appl. Sci. 2018, 8(4), 567; https://doi.org/10.3390/app8040567 - 5 Apr 2018

Cited by 10 | Viewed by 4544

Abstract

With the rapid growth of electricity demands, many traditional distributed networks cannot cover their peak demands, especially in the evening. Additionally, with the interconnection of distributed electrical and thermal grids, system operational flexibility and energy efficiency can be affected as well. Therefore, by [...] Read more.

With the rapid growth of electricity demands, many traditional distributed networks cannot cover their peak demands, especially in the evening. Additionally, with the interconnection of distributed electrical and thermal grids, system operational flexibility and energy efficiency can be affected as well. Therefore, by adding a portable energy system and a heat storage tank to the traditional distributed system, this paper proposes a newly defined distributed network to deal with the aforementioned problems. Simulation results show that by adding a portable energy system, fossil fuel energy consumption and daily operation cost can be reduced by 8% and 28.29%, respectively. Moreover, system peak load regulating capacity can be significantly improved. However, by introducing the portable energy system to the grid, system uncertainty can be increased to some extent. Therefore, chance constrained programming is proposed to control the system while considering system uncertainty. By applying Particle Swarm Optimization—Monte Carlo to solve the chance constrained programming, results show that power system economy and uncertainty can be compromised by selecting appropriate confidence levels α and β. It is also reported that by installing an extra heat storage tank, combined heat and power energy efficiency can be significantly improved and the installation capacity of the battery can be reduced. Full article

(This article belongs to the Section Energy Science and Technology)

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11 pages, 21391 KiB

Open AccessArticle

Respiration Symptoms Monitoring in Body Area Networks

by Lu Liu^1,2,†, Syed Aziz Shah^1,†

, Guoqing Zhao¹ and Xiaodong Yang^1,*

¹ School of Electronic Engineering, Xidian University, Xi’an 710071, China

² School of Communications and Information Engineering, Xi’an University of Posts and Telecommunications, Xi’an 710061, China

^† These authors contributed equally to the work.

Appl. Sci. 2018, 8(4), 568; https://doi.org/10.3390/app8040568 - 6 Apr 2018

Cited by 45 | Viewed by 5030

Abstract

This work presents a framework that monitors particular symptoms such as respiratory conditions (abnormal breathing pattern) experienced by hyperthyreosis, sleep apnea, and sudden infant death syndrome (SIDS) patients. The proposed framework detects and monitors respiratory condition using S-Band sensing technique that leverages the [...] Read more.

This work presents a framework that monitors particular symptoms such as respiratory conditions (abnormal breathing pattern) experienced by hyperthyreosis, sleep apnea, and sudden infant death syndrome (SIDS) patients. The proposed framework detects and monitors respiratory condition using S-Band sensing technique that leverages the wireless devices such as antenna, card, omni-directional antenna operating in 2 GHz to 4 GHz frequency range, and wireless channel information extraction tool. The rhythmic patterns extracted using S-Band sensing present the periodic and non-periodic waveforms that correspond to normal and abnormal respiratory conditions, respectively. The fine-grained amplitude information obtained using aforementioned devices is used to examine the breathing pattern over a period of time and accurately identifies the particular condition. Full article

(This article belongs to the Special Issue Wearable Wireless Devices)

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11 pages, 15715 KiB

Open AccessArticle

Bio-Corrosion Behavior of Ceramic Coatings Containing Hydroxyapatite on Mg-Zn-Ca Magnesium Alloy

by Hong-Yan Ding^1,†, Hong Li^1,†, Guo-Qing Wang², Tao Liu¹ and Guang-Hong Zhou^1,2,*

¹ Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003, China

² College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China

^† These authors contributed equally to this work and should be considered co-first authors.

Appl. Sci. 2018, 8(4), 569; https://doi.org/10.3390/app8040569 - 6 Apr 2018

Cited by 12 | Viewed by 4433

Abstract

Ceramic coatings containing hydroxyapatite (HA) were fabricated on a biodegradable Mg₆₆Zn₂₉Ca₅ magnesium alloy through micro-arc oxidation by adding HA particles into the electrolytes. The phase composition and surface morphology of the coatings were characterized by X-ray diffraction and [...] Read more.

Ceramic coatings containing hydroxyapatite (HA) were fabricated on a biodegradable Mg₆₆Zn₂₉Ca₅ magnesium alloy through micro-arc oxidation by adding HA particles into the electrolytes. The phase composition and surface morphology of the coatings were characterized by X-ray diffraction and scanning electron microscopy analyses, respectively. Electrochemical experiments and immersion tests were performed in Hank’s solution at 37 °C to measure the corrosion resistance of the coatings. Blood compatibility was evaluated by in vitro blood platelet adhesion tests and static water contact angle measurement. The results show that the typical ceramic coatings with a porous structure were prepared on the magnesium alloy surface with the main phases of MgO and MgSiO₃ and a small amount of Mg₃(PO₄)₂ and HA. The optimal surface morphology appeared at HA concentration of 0.4 g/L. The electrochemical experiments and immersion tests reveal a significant improvement in the corrosion resistance of the ceramic coatings containing HA compared with the coatings without HA or bare Mg₆₆Zn₂₉Ca₅ magnesium alloy. The static water contact angle of the HA-containing ceramic coatings is 18.7°, which is lower than that of the coatings without HA (40.1°). The in vitro blood platelet adhesion tests indicate that the HA-containing ceramic coatings possess improved blood compatibility compared with the coatings without HA. Utilizing HA-containing ceramic coatings may be an effective way to improve the surface biocompatibility and corrosion resistance of magnesium alloys. Full article

(This article belongs to the Section Materials Science and Engineering)

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15 pages, 44556 KiB

Open AccessFeature PaperArticle

On the Properties of WC/SiC Multilayers

by Mauro Prasciolu

and Saša Bajt^*

Photon Science, DESY, Notkestraße 85, Hamburg 22607, Germany

Appl. Sci. 2018, 8(4), 571; https://doi.org/10.3390/app8040571 - 6 Apr 2018

Cited by 16 | Viewed by 4844

Abstract

A study of the materials properties of WC/SiC multilayer coatings is presented. We investigated the dependence of interface and surface roughness, intrinsic stress, microstructure, chemical composition, and stoichiometry as a function of multilayer period and in some cases compared these to W/SiC multilayer [...] Read more.

A study of the materials properties of WC/SiC multilayer coatings is presented. We investigated the dependence of interface and surface roughness, intrinsic stress, microstructure, chemical composition, and stoichiometry as a function of multilayer period and in some cases compared these to W/SiC multilayer systems. The WC/SiC material pair forms multilayers with extremely smooth and sharp interfaces and both materials remain amorphous over a wide range of thicknesses. These properties are desirable for multilayer-based high-resolution diffractive x-ray optics, such as multilayer Laue lenses (MLLs), which require very thick films in which the layer spacing varies considerably. Thermal and structural stability studies show that WC/SiC multilayers have exceptional thermal stability, making this an extremely robust and favorable material pair for MLLs and other multilayer-based X-ray optical elements. Full article

(This article belongs to the Special Issue Advanced EUV and X-Ray Optics)

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21 pages, 33760 KiB

Open AccessArticle

Effects of Crack and Climate Change on Service Life of Concrete Subjected to Carbonation

by Xiao-Yong Wang

Department of Architectural Engineering, Kangwon National University, Chuncheon-si 24341, Korea

Appl. Sci. 2018, 8(4), 572; https://doi.org/10.3390/app8040572 - 6 Apr 2018

Cited by 5 | Viewed by 5438

Abstract

Carbonation is among the primary reasons for the initiation of the corrosion of steel rebar in reinforced concrete (RC) structures. Due to structural loading effects and environmental actions, inevitable cracks have frequently occurred in concrete structures since the early ages. Additionally, climate change, [...] Read more.

Carbonation is among the primary reasons for the initiation of the corrosion of steel rebar in reinforced concrete (RC) structures. Due to structural loading effects and environmental actions, inevitable cracks have frequently occurred in concrete structures since the early ages. Additionally, climate change, which entails increases in CO₂ concentration and environmental temperature, will also accelerate the carbonation of concrete. This article presents an analytical way of predicting the service life of cracked concrete structures considering influences of carbonation and climate change. First, using a hydration model, the quantity of carbonatable materials and concrete porosity were calculated. Carbonation depth was evaluated considering properties of concrete materials and environmental conditions. Second, the influence of cracks on CO₂ diffusivity was examined. Carbonation depth for cracked concrete was evaluated using equivalent CO₂ diffusivity. The effects of climate change, for example, growing CO₂ concentration and environmental temperature, were considered using different schemes of carbonation models. Third, different climate change scenarios (such as Representative Concentration Pathways (RCP) 2.6, RCP 4.5, RCP 8.5 and upper 90% confidence interval of RCP 8.5) and time slices (such as 2000 and 2050) were used for case studies. By utilizing the Monte Carlo method, the influences of various climate change scenarios on the service life loss of concrete structures were highlighted. Full article

(This article belongs to the Special Issue Modelling of Early Age Cracking Risks and Serviceability of Concrete Structures)

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17 pages, 40466 KiB

Open AccessFeature PaperArticle

A Novel Connectivity Factor for Morphological Characterization of Membranes and Porous Media: A Simulation Study on Structures of Mono-Sized Spherical Particles

by Stefano Bellini¹, Giulia Azzato¹, Monia Grandinetti¹, Virgilio Stellato¹, Giuseppe De Marco²

, Yu Sun³ and Alessio Caravella^1,*

¹ Department of Environmental and Chemical Engineering (DIATIC), University of Calabria, Via P. Bucci, Cubo 44A, 87036 Rende (CS), Italy

² Information Technology Center (ICT), University of Calabria, Via P. Bucci, Cubo 22B, 87036 Rende (CS), Italy

³ International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Motooka 744, Nishi Ku, Fukuoka 819-0395, Japan

Appl. Sci. 2018, 8(4), 573; https://doi.org/10.3390/app8040573 - 6 Apr 2018

Cited by 15 | Viewed by 5438

Abstract

In this study, we propose to define a connectivity factor as the inverse of the diffusional tortuosity to measure quantitatively the connectivity of whatever type of structure. The concept of connectivity used here is related to the diffusional accessibility of the structure voids. [...] Read more.

In this study, we propose to define a connectivity factor as the inverse of the diffusional tortuosity to measure quantitatively the connectivity of whatever type of structure. The concept of connectivity used here is related to the diffusional accessibility of the structure voids. This definition of connectivity factor arises from the consideration that, if we ideally imagine to decrease progressively the porosity of a regular structure, the porosity itself reaches a limit value below which the inner pores are not interconnected anymore. This leads to an evident situation of zero connectivity and infinite tortuosity, where there is no continuous diffusion path able to connect the structure voids. According to the proposed definition, the connectivity factor is comprised within [0, 1], with zero corresponding to a completely disconnected structure and unity to a completely connected one. To show the efficacy of the presented approach, a case study on the regular structure of mono-sized (mono-disperse) spherical particles (Simple Cubic (SC), Face-Centred Cubic (FCC), Body-Centred Cubic (BCC) and Tetragonal structures) is provided. In particular, the tortuosity of such structures is evaluated by Computational Fluid Dynamics simulations, calculating the connectivity factor consequently. The morphological modification with porosity is induced by changing the surface–surface interparticle distance, allowing us to take both positive (detached particles) and negative values (overlapping particles). For each structure, a comparison between the calculated trends and some correlations of literature is made, and a novel “hidden” morphological parameter has been identified, that is, the here-called Limit Porosity Value, below which the connectivity is zero. The presented approach represents a systematic methodology to quantify the connectivity of any structure and to compare the morphology of membranes, catalysts, and porous media in general. Full article

(This article belongs to the Special Issue Modeling and Simulations for Membrane Processes of Industrial Interest)

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24 pages, 54602 KiB

Open AccessArticle

Ramjet Nozzle Analysis for Transport Aircraft Configuration for Sustained Hypersonic Flight

by Raman Baidya¹, Apostolos Pesyridis^1,2,* and Maxim Cooper¹

¹ College of Engineering and Design, Brunel University London, Uxbridge UB8 3PH, London, UK

² Metapulsion Engineering Ltd., Northwood HA6 3LG, London, UK

Appl. Sci. 2018, 8(4), 574; https://doi.org/10.3390/app8040574 - 6 Apr 2018

Cited by 19 | Viewed by 17243

Abstract

For the past several decades, research dealing with hypersonic flight regimes has been restricted mainly to military applications. Hypersonic transportation could be a possible and affordable solution to travel in the medium term and there is renewed interest from several private organisations for [...] Read more.

For the past several decades, research dealing with hypersonic flight regimes has been restricted mainly to military applications. Hypersonic transportation could be a possible and affordable solution to travel in the medium term and there is renewed interest from several private organisations for commercial exploitation in this direction. Various combined cycle propulsion configurations have been proposed and the present paper deals with implications for the nozzle component of a ramjet configuration as part of one such combined cycle propulsion configuration. An investigation was undertaken for a method of turbine-based propulsion which enables the hypersonic vehicle to take off under its own power and propel the aircraft under different mission profiles into ramjet operational Mach regimes. The present study details an optimal method of ramjet exhaust expansion to produce sufficient thrust to propel the vehicle into altitudes and Mach regimes where scramjet operation can be initiated. This aspect includes a Computational Fluid Dynamics (CFD)-based geometric study to determine the optimal configuration to provide the best thrust values. The CFD parametric analysis investigated three candidate nozzles and indicated that the dual bell nozzle design produced the highest thrust values when compared to other nozzle geometries. The altitude adaptation study also validated the effectiveness of the nozzle thrust at various altitudes without compromising its thrust-producing capabilities. Computational data were validated against published experimental data, which indicated that the computed values correlated well with the experimental data. Full article

(This article belongs to the Special Issue Gas Turbine Engine - towards the Future of Power)

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16 pages, 1451 KiB

Open AccessArticle

Robust Optimization for Household Load Scheduling with Uncertain Parameters

by Jidong Wang¹

, Peng Li¹

, Kaijie Fang^2,* and Yue Zhou³

¹ Key Laboratory of Smart Grid of Ministry of Education, Tianjin University, Tianjin 300072, China

² State Grid Jiangsu Electric Power Company Research Institute, Nanjing 211103, China

³ School of Engineering, Cardiff University, Cardiff CF24 3AA, UK

Appl. Sci. 2018, 8(4), 575; https://doi.org/10.3390/app8040575 - 7 Apr 2018

Cited by 25 | Viewed by 4866

Abstract

Home energy management systems (HEMS) face many challenges of uncertainty, which have a great impact on the scheduling of home appliances. To handle the uncertain parameters in the household load scheduling problem, this paper uses a robust optimization method to rebuild the household [...] Read more.

Home energy management systems (HEMS) face many challenges of uncertainty, which have a great impact on the scheduling of home appliances. To handle the uncertain parameters in the household load scheduling problem, this paper uses a robust optimization method to rebuild the household load scheduling model for home energy management. The model proposed in this paper can provide the complete robust schedules for customers while considering the disturbance of uncertain parameters. The complete robust schedules can not only guarantee the customers’ comfort constraints but also cooperatively schedule the electric devices for cost minimization and load shifting. Moreover, it is available for customers to obtain multiple schedules through setting different robust levels while considering the trade-off between the comfort and economy. Full article

(This article belongs to the Special Issue Smart Home and Energy Management Systems)

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6 pages, 18867 KiB

Open AccessArticle

New Instrument for Oral Hygiene of Children with Cleft Lip and Palate

by Rita Rodrigues^1,2

, Maria Helena Fernandes^1,3

, António Bessa Monteiro⁴, Rowney Furfuro⁴, Cátia Carvalho Silva², César Soares⁵

, Ricardo Vardasca⁵

, Joaquim Mendes^5,*

and Maria Conceição Manso^3,6

¹ Faculty of Dentistry, University of Porto, R. Dr. Manuel Pereira da Silva, 93, 4200-393 Porto, Portugal

² Faculty of Health Sciences, University Fernando Pessoa, Praça 9 de Abril, 349, 4249-004 Porto, Portugal

³ Associated Laboratory for Green Chemistry (LAQV/REQUIMTE), University of Porto, 4051-401 Porto, Portugal

⁴ Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, s/n, 4200-319 Porto, Portugal

⁵ Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal

⁶ Faculty of Health Sciences, University Fernando Pessoa, Fernando Pessoa Energy, Environment and Health Research Unit (FP-ENAS), Praça de 9 de Abril, 349, 4249-004 Porto, Portugal

Appl. Sci. 2018, 8(4), 576; https://doi.org/10.3390/app8040576 - 19 Apr 2018

Cited by 3 | Viewed by 7928

Abstract

Patients with cleft lip and palate (CLP) have several oral alterations that make the removal of bacterial plaque in the cleft area difficult, which is the main cause of the high incidence of oral health problems. The aim of this study is to [...] Read more.

Patients with cleft lip and palate (CLP) have several oral alterations that make the removal of bacterial plaque in the cleft area difficult, which is the main cause of the high incidence of oral health problems. The aim of this study is to develop a toothbrush especially designed to perform the hygiene of the cleft area. This device, called Cleft Toothbrush, is an add-on to a conventional toothbrush to clean hard-to-reach areas that are not accessible by using conventional brush shapes. The design was made in SOLIDWORKS® (Waltham, MA, USA) 3D and a sample of this device was produced by CURAPROX (Kriens, Switzerland). The efficacy of the Cleft Toothbrush was tested in a preliminary study performed in a four years old child with CLP, compared to that of a conventional toothbrush. A significantly higher reduction of the bacterial plaque was achieved with the Cleft Toothbrush. The child’s parents also felt more confident with this device, as it deals better with sensitive areas, as it did not hurt the child. This innovative toothbrush adapter appears to greatly improve the cleaning areas of high bacterial plaque retention in patients with CLP, together with excellent acceptance. Full article

(This article belongs to the Section Materials Science and Engineering)

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8 pages, 19244 KiB

Open AccessArticle

Interface Characteristics of Ti-Clad V–4Cr–4Ti Alloy Diffusion-Bonded Joint Produced by Hot Forging

by Gaowei Zhang

, Wentuo Han, Xiaoou Yi and Farong Wan^*

School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

Appl. Sci. 2018, 8(4), 577; https://doi.org/10.3390/app8040577 - 7 Apr 2018

Cited by 3 | Viewed by 3790

Abstract

Diffusion bonding of V–4Cr–4Ti alloy to pure titanium (Ti) was carried out by hot forging in the temperature range between 1150 °C and 950 °C. The microstructure and mechanical properties of the bonded joint were determined by using light optical microscopy (OM), scanning [...] Read more.

Diffusion bonding of V–4Cr–4Ti alloy to pure titanium (Ti) was carried out by hot forging in the temperature range between 1150 °C and 950 °C. The microstructure and mechanical properties of the bonded joint were determined by using light optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), micro-hardness measurements, and shear tests. The results indicate that the sound dissimilar joint can be obtained through hot forging processes. The interface has a width of about 100 μm and can be divided into two distinctive zones: a Widmanstatten structure zone and a β-Ti phase structure zone. According to the micro-hardness distribution profile across the substrates and the interface, the largest hardness of 332 HV was measured in a narrow region between the Ti substrate and the joint, which is remarkably higher than that of the substrates (Ti of 190 HV and V–4Cr–4Ti alloy of 258 HV). The lowest hardness of only 182 HV was found in a region in the V–4Cr–4Ti substrate adjacent to the joint. The shear test showed that the joint has a bonding strength higher than 165 MPa and a fracture of the joint took place in the region with the highest hardness. Full article

(This article belongs to the Section Materials Science and Engineering)

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15 pages, 20012 KiB

Open AccessArticle

An Outdoor Navigation System for Blind Pedestrians Using GPS and Tactile-Foot Feedback

by Ramiro Velázquez^1,*

, Edwige Pissaloux²

, Pedro Rodrigo¹

, Miguel Carrasco³

, Nicola Ivan Giannoccaro⁴

and Aimé Lay-Ekuakille⁴

¹ Faculty of Engineering, Universidad Panamericana, Aguascalientes 20290, Mexico

² Physics Department, Université de Rouen, Mont-Saint-Aignan 76821, France

³ Faculty of Engineering and Sciences, Universidad Adolfo Ibáñez, Peñalolén, Santiago 7941169, Chile

⁴ Department of Innovation Engineering, Università del Salento, Lecce 73100, Italy

Appl. Sci. 2018, 8(4), 578; https://doi.org/10.3390/app8040578 - 7 Apr 2018

Cited by 82 | Viewed by 15274

Abstract

This paper presents a novel, wearable navigation system for visually impaired and blind pedestrians that combines a global positioning system (GPS) for user outdoor localization and tactile-foot stimulation for information presentation. Real-time GPS data provided by a smartphone are processed by dedicated navigation [...] Read more.

This paper presents a novel, wearable navigation system for visually impaired and blind pedestrians that combines a global positioning system (GPS) for user outdoor localization and tactile-foot stimulation for information presentation. Real-time GPS data provided by a smartphone are processed by dedicated navigation software to determine the directions to a destination. Navigational directions are then encoded as vibrations and conveyed to the user via a tactile display that inserts into the shoe. The experimental results showed that users were capable of recognizing with high accuracy the tactile feedback provided to their feet. The preliminary tests conducted in outdoor locations involved two blind users who were guided along 380–420 m predetermined pathways, while sharing the space with other pedestrians and facing typical urban obstacles. The subjects successfully reached the target destinations. The results suggest that the proposed system enhances independent, safe navigation of blind pedestrians and show the potential of tactile-foot stimulation in assistive devices. Full article

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9 pages, 16726 KiB

Open AccessArticle

A 3D Printed Membrane-Based Gas Microflow Regulator for On-Chip Cell Culture

by Agnieszka Podwin^*, Rafał Walczak and Jan Dziuban

Faculty of Microsystems Electronics and Photonics, Wroclaw University of Science and Technology, 50-370 Wrocław, Poland

Appl. Sci. 2018, 8(4), 579; https://doi.org/10.3390/app8040579 - 8 Apr 2018

Cited by 7 | Viewed by 5279

Abstract

A miniature 3D printed membrane-based gas microflow regulator which delivers gaseous media to on-chip cell cultures is presented in this paper. The device uses a polydimethylosiloxane (PDMS) membrane to act as a diffusion barrier and maintain gas flow at the desired rate. The [...] Read more.

A miniature 3D printed membrane-based gas microflow regulator which delivers gaseous media to on-chip cell cultures is presented in this paper. The device uses a polydimethylosiloxane (PDMS) membrane to act as a diffusion barrier and maintain gas flow at the desired rate. The regulator was characterized, and repeatable flow values for different membrane thicknesses and gas types in the function of pressure were obtained. As a result, a long-term on-chip culture of Euglena gracilis was achieved, this was due to constant and stable carbon dioxide release from the regulator (flow rate: 0.3 μL/min). Full article

(This article belongs to the Special Issue Microfluidics in Biology and Medicine)

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16 pages, 2802 KiB

Open AccessArticle

Dynamic Supply Chain Design and Operations Plan for Connected Smart Factories with Additive Manufacturing

by Byung Do Chung^1,*, Sung Il Kim² and Jun Seop Lee³

¹ Department of Industrial Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

² AI Platform Development Team, LG Uplus, 32 Hangang-daero, Yongsan-gu, Seoul 04389, Korea

³ Department of Industrial Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

Appl. Sci. 2018, 8(4), 583; https://doi.org/10.3390/app8040583 - 8 Apr 2018

Cited by 51 | Viewed by 7256

Abstract

Interest in smart factories and smart supply chains has been increasing, and researchers have emphasized the importance and the effects of advanced technologies such as 3D printers, the Internet of Things, and cloud services. This paper considers an innovation in dynamic supply-chain design [...] Read more.

Interest in smart factories and smart supply chains has been increasing, and researchers have emphasized the importance and the effects of advanced technologies such as 3D printers, the Internet of Things, and cloud services. This paper considers an innovation in dynamic supply-chain design and operations: connected smart factories that share interchangeable processes through a cloud-based system for personalized production. In the system, customers are able to upload a product design file, an optimal supply chain design and operations plan are then determined based on the available resources in the network of smart factories. The concept of smart supply chains is discussed and six types of flexibilities are identified, namely: design flexibility, product flexibility, process flexibility, supply chain flexibility, collaboration flexibility, and strategic flexibility. Focusing on supply chain flexibility, a general planning framework and various optimization models for dynamic supply chain design and operations plan are proposed. Further, numerical experiments are conducted to analyze fixed, production, and transportation costs for various scenarios. The results demonstrate the extent of the dynamic supply chain design and operations problem, and the large variation in transportation cost. Full article

(This article belongs to the Special Issue Smart Sustainable Manufacturing Systems)

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17 pages, 906 KiB

Open AccessArticle

Energy Efficient Joint Power Control and User Association Optimization in Massive MIMO Enabled HetNets

by Liangrui Tang, Hailin Hu^*

and Yanhua He

State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University (NCEPU), Beijing 102206, China

Appl. Sci. 2018, 8(4), 584; https://doi.org/10.3390/app8040584 - 8 Apr 2018

Cited by 7 | Viewed by 3614

Abstract

Massive MIMO enabled heterogeneous cellular networks (HetNets) have a wide application prospect in improving end-to-end performance. To increase the performance of energy efficiency (EE), we formulate the joint optimization problem of power control and user association in this paper. Unfortunately, the problem is [...] Read more.

Massive MIMO enabled heterogeneous cellular networks (HetNets) have a wide application prospect in improving end-to-end performance. To increase the performance of energy efficiency (EE), we formulate the joint optimization problem of power control and user association in this paper. Unfortunately, the problem is a fractional and mixed integer nonlinear programming problem (FMINLP). Nevertheless, an energy efficient joint power control and user association optimization algorithm is proposed to solve the problem. Firstly, based on the Dinkelbach’s theorem, we transform the objective function of the problem into an integral expression and propose the optimal EE iterative algorithm. Then, with the help of the approximately iterative method and Lagrange’s decomposition dual method, the problem can be transformed into a convex optimization problem and the joint optimization algorithm is proposed correspondingly. In the simulation, the performance of EE and its influence factors are analyzed and some interesting points are discussed. Full article

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23 pages, 29024 KiB

Open AccessArticle

Energy Management Strategy for Rural Communities’ DC Micro Grid Power System Structure with Maximum Penetration of Renewable Energy Sources

by Maheswaran Gunasekaran¹

, Hidayathullah Mohamed Ismail¹, Bharatiraja Chokkalingam¹

, Lucian Mihet-Popa^2,*

and Sanjeevikumar Padmanaban³

¹ Department of Electrical and Electronics Engineering, SRM University, Chennai 603 203, India

² Faculty of Engineering, Østfold University College, Kobberslagerstredet 5, 1671 Kråkeroy-Fredrikstad, Norway

³ Department of Energy Technology, Aalborg University, Esbjerg 6700, Denmark

Appl. Sci. 2018, 8(4), 585; https://doi.org/10.3390/app8040585 - 8 Apr 2018

Cited by 45 | Viewed by 6525

Abstract

The AC and DC power system structures need to be modernized to meet consumer demands. DC microgrids are suitably admired due to their high efficiency, consistency, reliability, and load sharing performance, when interconnected to DC renewable and storage sources. The main control objective [...] Read more.

The AC and DC power system structures need to be modernized to meet consumer demands. DC microgrids are suitably admired due to their high efficiency, consistency, reliability, and load sharing performance, when interconnected to DC renewable and storage sources. The main control objective for any DC microgrid is providing proper load–power balancing based on the Distributed Generator (DG) sources. Due to the intermittent nature of renewable energy sources, batteries play an important role in load–power balancing in a DC microgrid. The existing energy management strategy may be able to meet the load demand. However, that technique is not suitable forrural communities’ power system structure. This research offers an energy management strategy (EMS) for a DC microgrid to supply power to rural communities with solar, wind, fuel cell, and batteries as input sources. The proposed EMS performs the load–power balancing between each source (renewable and storage) in a DC microgrid for dynamic load variation. Here, the EMS handles two battery sources (one is used to deliver power to the priority load, and the other is utilized in the common DC bus) to meet the required demand. The proposed EMS is capable of handling load–power balancing using renewable energy sources with less consumption of non- conventional energy sources (such as a diesel generator). The performance of the system is analyzed based on different operating conditions of the input sources. The MATLAB/Simulink simulation model for the proposed DC microgrid with their EMS control system is developed and investigated, and their results are tabulated under different input and load conditions. The proposed EMS is verified through a laboratory real-time DC microgrid experimental setup, and the results are discussed. Full article

(This article belongs to the Special Issue DC & Hybrid Micro-Grids)

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12 pages, 19253 KiB

Open AccessArticle

Analytical Solution for 2D Inter-Well Porous Flow in a Rectangular Reservoir

by Junfeng Ding and Shimin Wang^*

Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing 100049, China

Appl. Sci. 2018, 8(4), 586; https://doi.org/10.3390/app8040586 - 8 Apr 2018

Cited by 3 | Viewed by 3746

Abstract

Inter-well fluid flows through porous media are commonly encountered in the production of groundwater, oil, and geothermal energy. In this paper, inter-well porous flow inside a rectangular reservoir is solved based on the complex variable function theory combined with the method of mirror [...] Read more.

Inter-well fluid flows through porous media are commonly encountered in the production of groundwater, oil, and geothermal energy. In this paper, inter-well porous flow inside a rectangular reservoir is solved based on the complex variable function theory combined with the method of mirror images. In order to derive the solution analytically, the inter-well flow is modeled as a 2D flow in a homogenous and isotropic porous medium. The resulted exact analytical solution takes the form of an infinite series, but it can be truncated to give high accuracy approximation. In terms of nine cases of inter-well porous flow associated with enhanced geothermal systems, the applications of the obtained analytical solution are demonstrated, and the convergence properties of the truncated series are investigated. It is shown that the convergent rate of the truncated series increases with the symmetric level of well distribution inside the reservoir, and the adoption of Euler transform significantly accelerates the convergence of alternating series cases associated with asymmetric well distribution. In principle, the analytical solution proposed in this paper can be applied to other scientific and engineering fields, as long as the involved problem is governed by 2D Laplace equation in a rectangular domain and subject to similar source/sink and boundary conditions, i.e., isolated point sources/sinks and uniform Dirichlet or homogeneous Neumann boundary conditions. Full article

(This article belongs to the Section Mechanical Engineering)

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28 pages, 1610 KiB

Open AccessArticle

Energy Sharing for Interconnected Microgrids with a Battery Storage System and Renewable Energy Sources Based on the Alternating Direction Method of Multipliers

by Nian Liu^*

and Jie Wang

State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China

Appl. Sci. 2018, 8(4), 590; https://doi.org/10.3390/app8040590 - 9 Apr 2018

Cited by 15 | Viewed by 5570

Abstract

In order to facilitate the local sharing of renewable energy, an energy sharing management method of multiple microgrids (MGs) with a battery energy storage system (BESS) and renewable energy sources (RESs) is developed. First, a virtual entity named the energy sharing provider (ESP), [...] Read more.

In order to facilitate the local sharing of renewable energy, an energy sharing management method of multiple microgrids (MGs) with a battery energy storage system (BESS) and renewable energy sources (RESs) is developed. First, a virtual entity named the energy sharing provider (ESP), which acts as an agent for MGs, is introduced to minimize the power loss cost. Second, a distributed optimal model and a two-level iterative algorithm for the MGs and ESP are proposed, which minimize the total operation cost including purchasing electricity cost, energy storage cost and power loss cost. Based on the energy sharing framework, considering the local objectives of MGs and the objective of ESP, the optimal scheduling can be achieved through the bidirectional interaction between MGs and ESP. During the optimization, the shared information between MGs and ESP is limited to expected exchange power, which protects the privacy of MGs and ESP. Finally, the effectiveness of the proposed model and algorithm in different scenarios is verified through a case study. Full article

(This article belongs to the Special Issue Developing and Implementing Smart Grids: Novel Technologies, Techniques and Models)

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23 pages, 11877 KiB

Open AccessArticle

Application of Workflow Technology for Big Data Analysis Service

by Bin Zhang¹, Le Yu¹, Yunbo Feng¹, Lijun Liu¹ and Shuai Zhao^2,*

¹ China Mobile Information Security Center, 32 Xuanwumen West Street, Xicheng District, Beijing 100033, China

² Beijing University of Post and Telecommunications, 10 Xitu Cheng Road, Haidian District, Beijing 100876, China

Appl. Sci. 2018, 8(4), 591; https://doi.org/10.3390/app8040591 - 9 Apr 2018

Cited by 11 | Viewed by 6196

Abstract

This study presents a lightweight representational state transfer-based cloud workflow system to construct a big data intelligent software-as-a-service (SaaS) platform. The system supports the dynamic construction and operation of an intelligent data analysis application, and realizes rapid development and flexible deployment of the [...] Read more.

This study presents a lightweight representational state transfer-based cloud workflow system to construct a big data intelligent software-as-a-service (SaaS) platform. The system supports the dynamic construction and operation of an intelligent data analysis application, and realizes rapid development and flexible deployment of the business analysis process that can improve the interaction and response time of the process. The proposed system integrates offline-batch and online-streaming analysis models that allow users to conduct batch and streaming computing simultaneously. Users can rend cloud capabilities and customize a set of big data analysis applications in the form of workflow processes. This study elucidates the architecture and application modeling, customization, dynamic construction, and scheduling of a cloud workflow system. A chain workflow foundation mechanism is proposed to combine several analysis components into a chain component that can promote efficiency. Four practical application cases are provided to verify the analysis capability of the system. Experimental results show that the proposed system can support multiple users in accessing the system concurrently and effectively uses data analysis algorithms. The proposed SaaS workflow system has been used in network operators and has achieved good results. Full article

(This article belongs to the Special Issue Advanced Internet of Things for Smart Infrastructure System)

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8 pages, 7316 KiB

Open AccessArticle

Design and Optimization of an Opened Suspended Core Fiber-Based SPR Sensor with Gold Cylinder Structures

by Wentan Jiao^1,†, Jinrong Liu^2,†, Jing Zhang³, Guanjun Wang^2,4,* and Mengxing Huang^4,*

¹ College of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023, China

² School of Information and Communication Engineering, North University of China, Taiyuan 030051, China

³ School of Electronic and Information Engineering, Beihang University, Beijing 100083, China

⁴ Collage of Information Science & Technology, Hainan University, Haikou 570228, China

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 592; https://doi.org/10.3390/app8040592 - 9 Apr 2018

Cited by 3 | Viewed by 3938

Abstract

In this study, an opened three-hole suspended core fiber surface plasmon resonance sensor structure based on the combination of photonic crystal fiber and surface plasmon resonance (SPR) mechanism was proposed and analyzed. One hole in the clad layer was exposed to the outside, [...] Read more.

In this study, an opened three-hole suspended core fiber surface plasmon resonance sensor structure based on the combination of photonic crystal fiber and surface plasmon resonance (SPR) mechanism was proposed and analyzed. One hole in the clad layer was exposed to the outside, and a lay of gold cylinders with the same size and gap was placed along the inside of the opened hole. The existence of the gold cylinders could stimulate the SPR effect and selecting the suitable gaps between the cylinders could enhance the SPR effect and increase its sensitivity. Then COMSOL software was used to simulate how the cylinder diameter, the gaps between the cylinders, and the fluid refractive index variation affect the sensor’s transmission loss spectrum, field enhancement effect, and the sensitivity. The optimized results show that the sensitivity of this proposed SPR sensor could be high, up to 1 × 10⁻⁵ RIU/nm, and it was much higher than the sensitivity of the existing photonic crystal fiber SPR sensor (1 × 10⁻⁴ RIU/nm), which was an order of magnitude improvement. This study could provide a reliable theoretical basis for future research and design of real-time and high-sensitivity opened fiber SPR sensors. Full article

(This article belongs to the Special Issue Fiber Bragg Gratings: Fundamentals, Materials and Applications)

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17 pages, 45554 KiB

Open AccessArticle

Finite Element Modeling of an Aircraft Tire Rolling on a Steel Drum: Experimental Investigations and Numerical Simulations

by Iulian Rosu, Hélène L. Elias-Birembaux^* and Frédéric Lebon

Aix-Marseille University CNRS, Centrale Marseille, LMA, F-13453 Marseille CEDEX 13, France

Appl. Sci. 2018, 8(4), 593; https://doi.org/10.3390/app8040593 - 10 Apr 2018

Cited by 14 | Viewed by 6977

Abstract

The aim of this study is to investigate the thermal evolution of an aircraft tire rolling at high velocities up to take off values. As this kind of experiment is difficult to realize on a real runway, experimental tests were realized on aircraft [...] Read more.

The aim of this study is to investigate the thermal evolution of an aircraft tire rolling at high velocities up to take off values. As this kind of experiment is difficult to realize on a real runway, experimental tests were realized on aircraft tires rolling on a steel drum. The rotating drum facility allows to apply variable velocities beyond the take off limits, at fixed skidding angles and loadings. The rolling conditions, vertical loading, velocity and cornering conditions were adopted to correspond to the real conditions of an aircraft tire running or skidding on a flat runway. In the experimental part, the influence of skidding angle, velocity and loading on the thermal evolution of the tire tread were investigated. The thermo-mechanical finite element analysis of a pneumatic radial tire structure was performed taking into account the hyper-viscoelastic rubber behavior, with heating mechanisms developed by the inelastic deformation and by friction. Three-dimensional finite element simulations of an aircraft tire rolling on a steel drum were carried out using Abaqus/Standard finite element solver. The comparison of the temperature distribution on the tire tread between numerical results and the experimental data shows the same overall tendencies. The good correlation between numerical and experimental data shows that numerical simulation could predict the thermal evolution of the tire in critical situations. The authors would like to mention that for confidentiality reason, certain numerical data could not be revealed. Full article

(This article belongs to the Special Issue Viscoelastic Solids: Mechanical Behaviour, Contact Mechanics, Fracture and Wear)

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20 pages, 31470 KiB

Open AccessArticle

Preliminary Design and Model Assessment of a Supercritical CO₂ Compressor

by Zhiyuan Liu^1,2, Weiwei Luo¹, Qingjun Zhao^1,2,3,*, Wei Zhao^1,2 and Jianzhong Xu^1,2

¹ Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China

² School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100190, China

³ Key Laboratory of Light-duty Gas-turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China

Appl. Sci. 2018, 8(4), 595; https://doi.org/10.3390/app8040595 - 10 Apr 2018

Cited by 42 | Viewed by 7991

Abstract

The compressor is a key component in the supercritical carbon dioxide (SCO₂) Brayton cycle. In this paper, the authors designed a series of supercritical CO₂ compressors with different parameters. These compressors are designed for 100 MWe, 10 MWe and 1 [...] Read more.

The compressor is a key component in the supercritical carbon dioxide (SCO₂) Brayton cycle. In this paper, the authors designed a series of supercritical CO₂ compressors with different parameters. These compressors are designed for 100 MWe, 10 MWe and 1 MWe scale power systems, respectively. For the 100 MWe SCO₂ Brayton cycle, an axial compressor has been designed by the Smith chart to test whether an axial compressor is suitable for the SCO₂ Brayton cycle. Using a specific speed and a specific diameter, the remaining two compressors were designed as centrifugal compressors with different pressure ratios to examine whether models used for air in the past are applicable to SCO₂. All compressors were generated and analyzed with internal MATLAB programs coupled with the NIST REFPROP database. Finally, the design results are all checked by numerical simulations due to the lack of reliable experimental data. Research has found that in order to meet the de Haller stall criterion, axial compressors require a considerable number of stages, which introduces many additional problems. Thus, a centrifugal compressor is more suitable for the SCO₂ Brayton cycle, even for a 100 MWe scale system. For the performance prediction model of a centrifugal compressor, the stall predictions are compared with steady numerical calculation, which indicates that past stall criteria may also be suitable for SCO₂ compressors, but more validations are needed. However, the accuracy of original loss models is found to be inadequate, particularly for lower flow and higher pressure ratio cases. Deviations may be attributed to the underestimation of clearance loss according to the result of steady simulation. A modified model is adopted which can improve the precision to a certain extent, but more general and reasonable loss models are needed to improve design accuracy in the future. Full article

(This article belongs to the Special Issue Carbon Capture Utilization and Sequestration (CCUS))

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13 pages, 26436 KiB

Open AccessArticle

Actively Controlling the Topological Transition of Dispersion Based on Electrically Controllable Metamaterials

by Zhiwei Guo

, Haitao Jiang^*, Yong Sun

, Yunhui Li and Hong Chen

Key Laboratory of Advanced Micro-structure Materials, MOE, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China

Appl. Sci. 2018, 8(4), 596; https://doi.org/10.3390/app8040596 - 10 Apr 2018

Cited by 27 | Viewed by 4259

Abstract

Topological transition of the iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid provides unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive, and the related experimental observations are highly desirable. Here, [...] Read more.

Topological transition of the iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid provides unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive, and the related experimental observations are highly desirable. Here, a tunable electric IFC in a periodic structure composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of the graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing perfect electric conductor/perfect magnetic conductor impurities. Finally, by adding variable capacitance diodes into a two-dimensional transmission-line system, we present an experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase in voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of an actively tuned topological transition will open up a new avenue in the dynamical control of metamaterials. Full article

(This article belongs to the Section Optics and Lasers)

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16 pages, 18325 KiB

Open AccessArticle

Investigation on the Effects of Internal EGR by Variable Exhaust Valve Actuation with Post Injection on Auto-ignited Combustion and Emission Performance

by Insu Cho¹, Yumin Lee² and Jinwook Lee^3,*

¹ Department of Mechanical Engineering, Graduate School, Soongsil University, Seoul 06978, Korea

² Department of Mechanical Engineering, Undergraduate Course, Soongsil University, Seoul 06978, Korea

³ Department of Mechanical Engineering, Soongsil University, Seoul 06978, Korea

Appl. Sci. 2018, 8(4), 597; https://doi.org/10.3390/app8040597 - 10 Apr 2018

Cited by 11 | Viewed by 7522

Abstract

Variable valve mechanisms are usually applied to a gasoline combustion engine to improve its power performance by controlling the amount of intake air according to the operating load. These mechanisms offer one possibility of resolving the conflict of objectives between a further reduction [...] Read more.

Variable valve mechanisms are usually applied to a gasoline combustion engine to improve its power performance by controlling the amount of intake air according to the operating load. These mechanisms offer one possibility of resolving the conflict of objectives between a further reduction of raw emissions and an improvement in fuel efficiency. In recent years, variable valve control systems have become extremely important in the diesel combustion engine. Importantly, it has been shown that there are several potential benefits of applying variable valve timing (VVT) to a compression ignition engine. Valve train variability could offer one option to achieve the reduction goals of engine-out emissions and fuel consumption. The aim of this study was to investigate the effects on part load combustion and emission performance of internal exhaust gas recirculation (EGR) by variable exhaust valve lift actuation using a cam-in-cam system, which is an electronically variable valve device with a variable inside cam retarded to about 30 degrees. Numerical simulation based on GT-POWER has been performed to predict the NO_x reduction strategy at the part load operating point of 1200 rpm in a four-valve diesel engine. A GT-POWER model of a common-rail direct injection engine with internal EGR was built and verified with experimental data. As a result, large potential for reducing NO_x emissions through the use of exhaust valve control has been identified. Namely, it is possible to utilize heat efficiently as recompression of retarded post injection with downscaled specification of the exhaust valve rather than the intake valve, even if the CIC V1 condition with a reduction of the exhaust valve has a higher internal EGR rate of about 2% compared to that of the CIC V2 condition. Full article

(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)

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18 pages, 19725 KiB

Open AccessArticle

Adaptive Non-Strict Trajectory Tracking Control Scheme for a Fully Actuated Unmanned Surface Vehicle

by Jian Wang^*

, Jing-yang Liu, Hong Yi and Nai-long Wu

State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Appl. Sci. 2018, 8(4), 598; https://doi.org/10.3390/app8040598 - 11 Apr 2018

Cited by 8 | Viewed by 3617

Abstract

This study presents a new adaptive trajectory tracking control scheme for a fully actuated Unmanned Surface Vehicle (USV) to track a common moving target region. In this control concept, the desired objective trajectory is specified as a moving region instead of a moving [...] Read more.

This study presents a new adaptive trajectory tracking control scheme for a fully actuated Unmanned Surface Vehicle (USV) to track a common moving target region. In this control concept, the desired objective trajectory is specified as a moving region instead of a moving point, and so which is called non-strict trajectory tracking. Within this control scheme, a regression matrix is used to handle the parameter uncertainties, and region-based control scheme is used to track a desired moving region. A switching gain control term based on the exponential function is proposed to make the USV’s trajectory converge into the desired moving region rather than converge on the boundary of the moving region, and to reduce system chattering at the same time. A Lyapunov-like function is presented for stability analysis of the proposed control scheme. Numerical simulations are conducted to demonstrate the performance of the proposed non-strict trajectory tracking control scheme of the USV. Full article

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15 pages, 1852 KiB

Open AccessArticle

A Nonlinear Beamformer Based on p-th Root Compression—Application to Plane Wave Ultrasound Imaging

by Maxime Polichetti^1,2,*, François Varray¹

, Jean-Christophe Béra², Christian Cachard¹ and Barbara Nicolas¹

¹ University Lyon, INSA-Lyon, UCBL, UJM-Saint-Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, F-69100 Villeurbanne, France

² LabTAU, INSERM, Centre Léon Bérard, UCBL, University Lyon, F-69003 Lyon, France

Appl. Sci. 2018, 8(4), 599; https://doi.org/10.3390/app8040599 - 11 Apr 2018

Cited by 57 | Viewed by 7222

Abstract

Ultrafast medical ultrasound imaging is necessary for 3D and 4D ultrasound imaging, and it can also achieve high temporal resolution (thousands of frames per second) for monitoring of transient biological phenomena. However, reaching such frame rates involves reduction of image quality compared with [...] Read more.

Ultrafast medical ultrasound imaging is necessary for 3D and 4D ultrasound imaging, and it can also achieve high temporal resolution (thousands of frames per second) for monitoring of transient biological phenomena. However, reaching such frame rates involves reduction of image quality compared with that obtained with conventional ultrasound imaging, since the latter requires each image line to be reconstructed separately with a thin ultrasonic focused beam. There are many techniques to simultaneously acquire several image lines, although at the expense of resolution and contrast, due to interference from echoes from the whole medium. In this paper, a nonlinear beamformer is applied to plane wave imaging to improve resolution and contrast of ultrasound images. The method consists of the introduction of nonlinear operations in the conventional delay-and-sum (DAS) beamforming algorithm. To recover the value of each pixel, the raw radiofrequency signals are first dynamically focused and summed on the plane wave dimension. Then, their amplitudes are compressed using the signed

p^{t h}

root. After summing on the element dimension, the signed p-power is applied to restore the original dimensionality in volts. Finally, a band-pass filter is used to remove artificial harmonics introduced by these nonlinear operations. The proposed method is referred to as p-DAS, and it has been tested here on numerical and experimental data from the open access platform of the Plane wave Imaging Challenge in Medical UltraSound (PICMUS). This study demonstrates that p-DAS achieves better resolution and artifact rejection than the conventional DAS (for

p = 2

with eleven plane wave imaging on experimental phantoms, the lateral resolution is improved by

21 %

, and contrast ratio (CR) by

59 %

). However, like many coherence-based beamformers, it tends to distort the conventional speckle structure (contrast-to-noise-ratio (CNR) decreased by

45 %

). It is demonstrated that p-DAS, for

p = 2

, is very similar to the nonlinear filtered-delay-multiply-and-sum (FDMAS) beamforming, but also that its impact on image quality can be tuned changing the value of p. Full article

(This article belongs to the Special Issue Ultrasound B-mode Imaging: Beamforming and Image Formation Techniques)

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14 pages, 16752 KiB

Open AccessArticle

Application of Elastic Wave Velocity for Estimation of Soil Depth

by Hyunwook Choo¹, Hwandon Jun² and Hyung-Koo Yoon^3,*

¹ Department of Civil Engineering, Kyung Hee University, Yongin 17-104, Korea

² Department of Civil Engineering, Seoul National University of Science and Technology, Seoul 139-743, Korea

³ Department of Construction and Disaster Prevention Engineering, Daejeon University, Daejeon 300-716, Korea

Appl. Sci. 2018, 8(4), 600; https://doi.org/10.3390/app8040600 - 11 Apr 2018

Cited by 7 | Viewed by 3667

Abstract

Because soil depth is a crucial factor for predicting the stability at landslide and debris flow sites, various techniques have been developed to determine soil depth. The objective of this study is to suggest the graphical bilinear method to estimate soil depth through [...] Read more.

Because soil depth is a crucial factor for predicting the stability at landslide and debris flow sites, various techniques have been developed to determine soil depth. The objective of this study is to suggest the graphical bilinear method to estimate soil depth through seismic wave velocity. Seismic wave velocity rapidly changes at the interface of two different layers due to the change in material type, packing type, and contact force of particles and thus, it is possible to pick the soil depth based on seismic wave velocity. An area, which is susceptible to debris flow, was selected, and an aerial survey was performed to obtain a topographic map and digital elevation model. In addition, a seismic survey and a dynamic cone penetration test were performed in this study. The comparison between the soil depth based on dynamic cone tests and the graphical bilinear method shows good agreement, indicating that the newly suggested soil depth estimating method may be usefully applied to predict soil depth. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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9 pages, 21764 KiB

Open AccessArticle

Effects of Nanoparticle Materials on Prebreakdown and Breakdown Properties of Transformer Oil

by Yuzhen Lv^1,2, Yang Ge^1,*

, Lei Wang¹, Zhen Sun², You Zhou³, Meng Huang¹

, Chengrong Li¹, Jinsha Yuan¹ and Bo Qi¹

¹ Beijing Key Laboratory of High Voltage & EMC, School of Electric and Electronic Engineering, North China Electric Power University, Beijing 102206, China

² School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China

³ Hunan Province Key Laboratory of Smart Grids Operation and Control, Changsha University of Science and Technology, Changsha 410076, China

Appl. Sci. 2018, 8(4), 601; https://doi.org/10.3390/app8040601 - 11 Apr 2018

Cited by 11 | Viewed by 4839

Abstract

In order to reveal the effects of nanoparticle materials on prebreakdown and breakdown properties of transformer oil, three types of nanoparticle materials, including conductive Fe₃O₄, semiconductive TiO₂ and insulating Al₂O₃ nanoparticles, were prepared with the [...] Read more.

In order to reveal the effects of nanoparticle materials on prebreakdown and breakdown properties of transformer oil, three types of nanoparticle materials, including conductive Fe₃O₄, semiconductive TiO₂ and insulating Al₂O₃ nanoparticles, were prepared with the same size and surface modification. An experimental study on the breakdown strength and prebreakdown streamer propagation characteristics were investigated for transformer oil and three types of nanofluids under positive lightning impulse voltage. The results indicate that the type of nanoparticle materials has a notable impact on breakdown strength and streamer propagation characteristics of transformer oil. Breakdown voltages of nanofluids are markedly increased by 41.3% and 29.8% respectively by the presence of Fe₃O₄ and TiO₂ nanoparticles. Whereas a slight increase of only 7.4% is observed for Al₂O₃ nanofluid. Moreover, main discharge channels with thicker and denser branches are formed and the streamer propagation velocities are greatly lowered both in Fe₃O₄ and TiO₂ nanofluids, while no obvious change appears in the propagation process of streamers in Al₂O₃ nanofluid in comparison with that in pure oil. The test results of trap characteristics reveal that the densities of shallow traps both in Fe₃O₄ and TiO₂ nanofluids are much higher than that in Al₂O₃ nanofluid and pure oil, greatly reducing the distortion of the electric field. Thus, the propagations of positive streamers in the nanofluids are significantly suppressed by Fe₃O₄ and TiO₂ nanoparticles, leading to the improvements of breakdown strength. Full article

(This article belongs to the Special Issue Nanofluids and Their Applications)

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8 pages, 1519 KiB

Open AccessArticle

Inducing Strong Non-Linearities in a Phonon Trapping Quartz Bulk Acoustic Wave Resonator Coupled to a Superconducting Quantum Interference Device

by Maxim Goryachev¹, Eugene N. Ivanov¹

, Serge Galliou²

and Michael E. Tobar^1,*

¹ ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia

² FEMTO-ST Institute, CNRS, Univ. Bourgogne Franche Comte, ENSMM, 26 Chemin de l’Épitaphe, 25000 Besançon, France

Appl. Sci. 2018, 8(4), 602; https://doi.org/10.3390/app8040602 - 11 Apr 2018

Cited by 1 | Viewed by 4232

Abstract

A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons in such a way that they are well confined and immune to suspension losses so they exhibit extremely high acoustic Q-factors at low temperature, with

Q \times f

products of [...] Read more.

A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons in such a way that they are well confined and immune to suspension losses so they exhibit extremely high acoustic Q-factors at low temperature, with

Q \times f

products of order

10^{18}

Hz. In this work we couple such a resonator to a Superconducting Quantum Interference Device (SQUID) amplifier and investigate effects in the strong signal regime. Both parallel and series connection topologies of the system are investigated. The study reveals significant non-Duffing response that is associated with the nonlinear characteristics of Josephson junctions. The nonlinearity provides quasi-periodic structure of the spectrum in both incident power and frequency. The result gives an insight into the open loop behaviour of a future Cryogenic Quartz Oscillator in the strong signal regime. Full article

(This article belongs to the Special Issue Brillouin Scattering and Optomechanics)

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22 pages, 64111 KiB

Open AccessArticle

An Active Seat Controller with Vehicle Suspension Feedforward and Feedback States: An Experimental Study

by Abdulaziz Alfadhli^*, Jocelyn Darling and Andrew J. Hillis

Centre for Power Transmission and Motion Control, Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK

Appl. Sci. 2018, 8(4), 603; https://doi.org/10.3390/app8040603 - 11 Apr 2018

Cited by 16 | Viewed by 6886

Abstract

Active seat suspensions can be used to reduce the harmful vertical vibration of a vehicle’s seat by applying an external force using a closed loop controller. Many of the controllers found in the literature are difficult to implement practically, because they are based [...] Read more.

Active seat suspensions can be used to reduce the harmful vertical vibration of a vehicle’s seat by applying an external force using a closed loop controller. Many of the controllers found in the literature are difficult to implement practically, because they are based on using unavailable or difficult and costly measurements. This paper presents both simulation and experimental studies of five novel, simple, and cost-effective control strategies to be used for an active seat suspension in order to improve ride comfort at low frequencies below 20 Hz. These strategies use available and measurable feedforward (preview) information states from the vehicle secondary suspension, as well as feedback states from the seat suspension, together with gains optimised to minimise the occupant vibration. The gains were optimised using a genetic algorithm (GA), with a fitness function based on the seat effective amplitude transmissibility (SEAT) factor. Constraints on the control force and the seat suspension stroke were also included in the optimisation algorithm. Simulation and laboratory experimental tests were carried out to assess the performance of the proposed controllers according to the ISO 2631-1 standard, in both the frequency and time domains with a range of different road profiles. The experimental tests were performed using a multi-axis simulation table (MAST) and a physical active seat suspension configured as a hardware-in-loop (HIL) simulation with a virtual linear quarter vehicle model (QvM). The results demonstrate that the proposed controllers substantially attenuate the vertical vibration at the driver’s seat compared with both a passive and a proportional-integral-derivative (PID) active seat suspension and thus improve ride comfort together with reducing vibration-linked health risks. Moreover, experimental results show that employing both feedforward information and feedback vehicle body and seat acceleration signals in the controller provides isolation performance gains of up to 19.5 dB over the human body sensitivity frequency range and improves the ride comfort in terms of the SEAT factor and the weighted root mean square (RMS) seat acceleration by at least 25% when compared with a passive system, irrespective of vehicle forward speed. Full article

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12 pages, 20061 KiB

Open AccessArticle

Fabrication and Characterization of Medical Mesh-Nebulizer for Aerosol Drug Delivery

by Kyong-Hoon Choi¹, Sang-Hyub Moon², Su-Kang Park³, Guangsup Cho⁴, Ki Chang Nam^2,*

and Bong Joo Park^1,4,*

¹ Institute of Biomaterials, Kwangwoon University, 20 Kwangwoongil, Nowon-gu, Seoul 01897, Korea

² Department of Medical Engineering, Dongguk University College of Medicine, Gyeonggi-do 10326, Korea

³ Medical Device Center, Korea Testing Certification, Gunpo-si, Gyeonggi-do 10326, Korea

⁴ Department of Electrical Biological Physics, Kwangwoon University, 20 Kwangwoongil, Nowon-gu, Seoul 01897, Korea

Appl. Sci. 2018, 8(4), 604; https://doi.org/10.3390/app8040604 - 11 Apr 2018

Cited by 15 | Viewed by 13065

Abstract

In the field of drug delivery, a nebulizer is a device used to convert liquid drugs into tiny airborne droplets, such as aerosol or a mist form. These fine droplets are delivered to a patient’s lungs and airways and then spread throughout the [...] Read more.

In the field of drug delivery, a nebulizer is a device used to convert liquid drugs into tiny airborne droplets, such as aerosol or a mist form. These fine droplets are delivered to a patient’s lungs and airways and then spread throughout the body via blood vessels. Therefore, nebulization therapy is a highly-effective method compared with existing drug delivery methods. To enhance the curative influence of a drug, this study suggests the use of a new micro-porous mesh nebulizer consisting of a controllable palladium–nickel (Pd–Ni) membrane filter, piezoelectric element, and a cavity in the micro-pump. In this research, we optimize a biocompatible Pd–Ni membrane filter, such that it generated the smallest aerosol particles of various drugs. The pore size of the filter outlet is 4.2 μm ± 0.15 μm and the thickness of the Pd-Ni membrane filter is approximately 41.5 μm. In addition, the Pd–Ni membrane filter has good biocompatibility with normal cells. The result of a spray test with deionized (DI) water indicated that the size of a standard liquid droplet is 4.53 μm. The device has an electrical requirement, with a low power consumption of 2.5 W, and an optimal operation frequency of 98.5 kHz. Full article

(This article belongs to the Special Issue Smart Environment and Healthcare)

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14 pages, 6409 KiB

Open AccessArticle

Study of the Electromagnetic Properties of Nano (M_xZn_1−x)Fe₂O₄ (M=Cu, Ni) as a Function of the Sintering Temperature

by Yenchun Liu^* and Jarnchih Hsu

Graduate School of OptoMechatronics and Materials, WuFeng University, Chiayi 62153, Taiwan

Appl. Sci. 2018, 8(4), 605; https://doi.org/10.3390/app8040605 - 11 Apr 2018

Cited by 3 | Viewed by 3722

Abstract

In this study, the chemical co-precipitation method was used to prepare a nanoscale ferrite powder with Cu-Zn and Ni-Zn compositions. Ferrite, in different Cu-Zn stoichiometric ratios, showed optimal composition of saturated magnetization for Cu_0.7Zn_0.3Fe₂O₄; under [...] Read more.

In this study, the chemical co-precipitation method was used to prepare a nanoscale ferrite powder with Cu-Zn and Ni-Zn compositions. Ferrite, in different Cu-Zn stoichiometric ratios, showed optimal composition of saturated magnetization for Cu_0.7Zn_0.3Fe₂O₄; under an air environment and calcined at 900 °C, the saturated magnetization was 60.19 M(emu/g). The average particle diameter was 10 nm for the non-calcined sample, while when the sintering temperature was 900 °C, the particle diameter was about 150 nm. In addition, in different Ni-Zn stoichiometric ratios, the optimal composition of the saturated magnetization was Ni_0.5Zn_0.5Fe₂O₄; under an air environment and calcination at 900 °C, the saturated magnetization was 91.40 M(emu/g). The average particle diameter for the non-calcined sample was about 10 nm, but when the sintering temperature was 1200 °C, the particle diameter was 201.06 nm. The prepared ferrite nano-powder was characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), and vibrating sample magnetometer(VSM) to reveal its microscopic structure and related electromagnetic properties. Ferrite powders of either Cu-Zn or Ni-Zn composition can be used as catalysts for chemical reactions or iron core materials. Full article

(This article belongs to the Special Issue Cu and Cu-Based Nanoparticles: Applications in Catalysis)

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23 pages, 3681 KiB

Open AccessArticle

End-to-End Neural Optical Music Recognition of Monophonic Scores

by Jorge Calvo-Zaragoza^1,2,* and David Rizo^3,4

¹ Schulich School of Music, McGill University, Montreal, QC H3A 1E3, Canada

² PRHLT Research Center, Universitat Politècnica de València, 46022 Valencia, Spain

³ Instituto Superior de Enseñanzas Artísticas, 03690 Alicante, Spain

⁴ Departamento de Lenguajes y Sistemas Informáticos, Universidad de Alicante, 03690 Alicante, Spain

Appl. Sci. 2018, 8(4), 606; https://doi.org/10.3390/app8040606 - 11 Apr 2018

Cited by 67 | Viewed by 21411

Abstract

Optical Music Recognition is a field of research that investigates how to computationally decode music notation from images. Despite the efforts made so far, there are hardly any complete solutions to the problem. In this work, we study the use of neural networks [...] Read more.

Optical Music Recognition is a field of research that investigates how to computationally decode music notation from images. Despite the efforts made so far, there are hardly any complete solutions to the problem. In this work, we study the use of neural networks that work in an end-to-end manner. This is achieved by using a neural model that combines the capabilities of convolutional neural networks, which work on the input image, and recurrent neural networks, which deal with the sequential nature of the problem. Thanks to the use of the the so-called Connectionist Temporal Classification loss function, these models can be directly trained from input images accompanied by their corresponding transcripts into music symbol sequences. We also present the Printed Music Scores dataset, containing more than 80,000 monodic single-staff real scores in common western notation, that is used to train and evaluate the neural approach. In our experiments, it is demonstrated that this formulation can be carried out successfully. Additionally, we study several considerations about the codification of the output musical sequences, the convergence and scalability of the neural models, as well as the ability of this approach to locate symbols in the input score. Full article

(This article belongs to the Special Issue Digital Audio and Image Processing with Focus on Music Research)

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21 pages, 53602 KiB

Open AccessArticle

Design and Construction of Oblique Prestressed Concrete Pavement: A Case Study in China

by Ling Yu¹, Xu Yang^2,*, Xiaohui Yan^3,†, Xiaowei Zhang^1,†, Ting Zhao^4,†, Cong Duan⁵

and Julian Mills-Beale⁶

¹ School of Transportation, Shenyang Jianzhu University, East Hunnan Road, Shenyang 110168, China

² Department of Civil Engineering, Monash University, Clayton VIC 3800, Australia

³ Henan Vocational College of Water Conservancy and Environment, Garden Street, Zhengzhou 450008, China

⁴ Department of English for Nonmajors, Shenyang Jianzhu University, East Hunnan Road, Shenyang 110168, China

⁵ National Land Resources Engineering Institute, Lianhua Campus, Kunming University of Science and Technology, Kunming 650093, China

⁶ Department of Civil & Environmental Engineering, California Baptist University, 8432 Magnolia Ave, Riverside, CA 92504, USA

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(4), 607; https://doi.org/10.3390/app8040607 - 11 Apr 2018

Cited by 9 | Viewed by 9113

Abstract

Prestressed concrete pavement can reduce slab thickness, eliminate transverse joints and enhance durability compared to traditional concrete pavement. Traditional prestressing or precast prestressing in the longitudinal direction requires additional space for anchorage and adds more joints. This study proposed an oblique prestress concrete [...] Read more.

Prestressed concrete pavement can reduce slab thickness, eliminate transverse joints and enhance durability compared to traditional concrete pavement. Traditional prestressing or precast prestressing in the longitudinal direction requires additional space for anchorage and adds more joints. This study proposed an oblique prestress concrete pavement, in which prestressed tendons were distributed with an angle to the road direction so that the prestress can be applied in both the transverse and longitudinal directions. The detailed design of the oblique prestress concrete pavement, including the selection of raw materials, design of cement concrete, anchorage area, size and distribution of prestressed tendons, stress analysis within the concrete slab, sliding layer, side reinforcement, and regular reinforcement at top and bottom are all included in this study. The slab thickness, diameter, distribution angle, and spacing of tendons were obtained based on the stress analysis to meet the requirement of fracture criteria and fatigue criteria. A demonstrative road pavement section, which has performed well after three years of traffic opening, was constructed according to the design. A step-by-step description of the construction was also presented in the study. Full article

(This article belongs to the Special Issue Achievements and Prospects of Advanced Pavement Materials Technologies)

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11 pages, 5698 KiB

Open AccessArticle

Synthesis of Zeolite A from Metakaolin and Its Application in the Adsorption of Cationic Dyes

by Priscila Martins Pereira¹, Breno Freitas Ferreira¹, Nathalia Paula Oliveira¹, Eduardo José Nassar¹, Katia Jorge Ciuffi¹, Miguel Angel Vicente^2,*

, Raquel Trujillano², Vicente Rives²

, Antonio Gil³

, Sophia Korili³ and Emerson Henrique De Faria^1,*

¹ Grupo de Pesquisas em Materiais Lamelares Híbridos (GPMatLam), Universidade de Franca, Av. Dr. Armando Salles Oliveira, CEP 14404-600, Franca 201, Brazil

² GIR-QUESCAT-Departamento de Química Inorgánica, Universidad de Salamanca, 37008 Salamanca, Spain

³ INAMAT-Departamento de Química Aplicada, Universidad Pública de Navarra, 31006 Pamplona, Spain

Appl. Sci. 2018, 8(4), 608; https://doi.org/10.3390/app8040608 - 11 Apr 2018

Cited by 51 | Viewed by 7658

Abstract

The present work reports the synthesis of zeolites from two metakaolins, one derived from the white kaolin and the other derived from the red kaolin, found in a deposit in the city of São Simão (Brazil). The metakaolins were prepared by calcination of [...] Read more.

The present work reports the synthesis of zeolites from two metakaolins, one derived from the white kaolin and the other derived from the red kaolin, found in a deposit in the city of São Simão (Brazil). The metakaolins were prepared by calcination of the kaolins at 600 °C; zeolite A was obtained after alkali treatment of the metakaolins with NaOH. The resulting solids were characterized by powder X-ray diffraction, thermal analysis, scanning electron microscopy, and nitrogen adsorption/desorption at −196 °C, which confirmed formation of zeolite A. The zeolites were applied as adsorbents to remove methylene blue, safranine, and malachite green from aqueous solutions. The zeolites displayed high adsorption capacity within short times (between one and five minutes); q_t was 0.96 mg/g. The equilibrium study showed that the zeolites had higher adsorption capacity for malachite green (q_e = 55.00 mg/g) than for the other two cationic dyes, and that the Langmuir isotherm was the model that best explained the adsorption mechanism. Full article

(This article belongs to the Special Issue Nanoporous Materials and Their Applications)

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15 pages, 2799 KiB

Open AccessArticle

Prediction of HIFU Propagation in a Dispersive Medium via Khokhlov–Zabolotskaya–Kuznetsov Model Combined with a Fractional Order Derivative

by Shilei Liu¹

, Yanye Yang¹, Chenghai Li¹, Xiasheng Guo^1,*, Juan Tu¹ and Dong Zhang^1,2,*

¹ Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Centre of Advanced Microstructure, Nanjing University, Nanjing 210093, China

² The State Key Laboratory of Acoustics, Chinese Academy of Science, Beijing 10080, China

Appl. Sci. 2018, 8(4), 609; https://doi.org/10.3390/app8040609 - 12 Apr 2018

Cited by 12 | Viewed by 4807

Abstract

High intensity focused ultrasound (HIFU) has been proven to be promising in non-invasive therapies, in which precise prediction of the focused ultrasound field is crucial for its accurate and safe application. Although the Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation has been widely used in the calculation [...] Read more.

High intensity focused ultrasound (HIFU) has been proven to be promising in non-invasive therapies, in which precise prediction of the focused ultrasound field is crucial for its accurate and safe application. Although the Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation has been widely used in the calculation of the nonlinear acoustic field of HIFU, some deviations still exist when it comes to dispersive medium. This problem also exists as an obstacle to the Westervelt model and the Spherical Beam Equation. Considering that the KZK equation is the most prevalent model in HIFU applications due to its accurate and simple simulation algorithms, there is an urgent need to improve its performance in dispersive medium. In this work, a modified KZK (mKZK) equation derived from a fractional order derivative is proposed to calculate the nonlinear acoustic field in a dispersive medium. By correcting the power index in the attenuation term, this model is capable of providing improved prediction accuracy, especially in the axial position of the focal area. Simulation results using the obtained model were further compared with the experimental results from a gel phantom. Good agreements were found, indicating the applicability of the proposed model. The findings of this work will be helpful in making more accurate treatment plans for HIFU therapies, as well as facilitating the application of ultrasound in acoustic hyperthermia therapy. Full article

(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)

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14 pages, 32232 KiB

Open AccessArticle

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

by Zhangbao Peng^1,†, Ziquan Guo^1,†, Tingzhu Wu¹

, Peng Zhuang², Zhicheng Ye¹, Yuan Shi², Tien-Mo Shih^1,3, Yijun Lu¹, Hao-Chung Kuo^4,5,* and Zhong Chen^1,*

¹ Department of Electronic Science, Fujian Engineering Research Center for Solid-State Lighting, Xiamen University, Xiamen 361005, China

² Xiamen Products Quality Supervision & Inspection Institute, National Testing Center for LED Application Products, Xiamen 361004, China

³ Changtai Tianming Physics Research Institute, Changtai 363900, China

⁴ Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan

⁵ Department of Electronic Engineering, Xiamen University, Xiamen 361005, China

^† These authors contributed equally to this work and should be considered co-first authors.

Appl. Sci. 2018, 8(4), 610; https://doi.org/10.3390/app8040610 - 12 Apr 2018

Cited by 1 | Viewed by 3803

Abstract

We have experimentally analyzed multi-azimuth degradation mechanisms that govern failures of commercially-available high-power (1 Watt) phosphor-coated white (hppc-W) light-emitting diodes (LEDs) covered with peanut-shaped lenses under three current-stress aging (CSA) conditions. Comprehensive analyses focus on photometric, chromatic, electrical, thermal and packaging characteristics. At [...] Read more.

We have experimentally analyzed multi-azimuth degradation mechanisms that govern failures of commercially-available high-power (1 Watt) phosphor-coated white (hppc-W) light-emitting diodes (LEDs) covered with peanut-shaped lenses under three current-stress aging (CSA) conditions. Comprehensive analyses focus on photometric, chromatic, electrical, thermal and packaging characteristics. At the packaging level, (a) the decrease of the phosphor-conversion efficiency; (b) the yellow-browning of the optical lens; and (c) the darkening of the silver-coated reflective layer deposited with extraneous chemical elements (e.g., C, O, Si, Mg, and Cu, respectively) contribute collectively to the integral degradation of the optical power. By contrast, Ohmic contacts, thermal properties, and angles of maximum intensity remain unchanged after 3840 h aging in three cases. Particularly at the chip level, the formation of point defects increases the number of non-radiative recombination centers, and thus decreases the optical power during aging stages. Nevertheless, in view of the change of the ideality factor, the Mg dopant activation and the annealing effect facilitate the increase of the optical power in two specific aging stages (192 h~384 h and 768 h~1536 h). This work offers a systematic guidance for the development of reliable LED-based light sources in general-lighting areas. Full article

(This article belongs to the Special Issue Highly Efficient UV and Visible Light Sources)

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14 pages, 10557 KiB

Open AccessArticle

Development of a High-Pressure Pneumatic On/Off Valve with High Transient Performances Direct-Driven by Voice Coil Motor

by Songlin Nie

, Xiangyang Liu, Fanglong Yin^*, Hui Ji and Jingxiu Zhang

Beijing Key Laboratory of Advanced Manufacturing Technology, Beijing University of Technology, Beijing 100124, China

Appl. Sci. 2018, 8(4), 611; https://doi.org/10.3390/app8040611 - 12 Apr 2018

Cited by 24 | Viewed by 6960

Abstract

The high-speed pneumatic on/off valve is one of the critical components in pneumatic systems, which has been widely investigated in the last decades. In this research, a new voice coil motor direct drive high-speed pneumatic on/off valve (VCM-DHPV) is proposed, and the mathematical [...] Read more.

The high-speed pneumatic on/off valve is one of the critical components in pneumatic systems, which has been widely investigated in the last decades. In this research, a new voice coil motor direct drive high-speed pneumatic on/off valve (VCM-DHPV) is proposed, and the mathematical model of VCM-DHPV, which consists of the fluid subsystem and electro-mechanical subsystem, is established. In addition, the key structural parameters of VCM-DHPV are optimized through the simulation analysis to improve its dynamic performance. The experiment results show that the developed VCM-DHPV has a good sealing performance by adopting the face-seal type in the valve port, and a large flow rate up to 5500 L/min, and its opening response time is 8.2 ms under the gas supply pressure of 8 MPa and exiting voltage of 240 V. With the supply pressure and the exciting voltage rising, the opening response time of VCM-DHPV is gradually increasing, and the variation tendency of the spool displacement curves is in accordance with the simulation results. This research will have significantly effects on raising the performance of the high-speed pneumatic on/off valve and the development of pneumatic precision motion control. Full article

(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)

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16 pages, 873 KiB

Open AccessFeature PaperArticle

Dimensioning Models of Optical WDM Rings in Xhaul Access Architectures for the Transport of Ethernet/CPRI Traffic

by Vincenzo Eramo^1,*

, Marco Listanti¹, Francesco G. Lavacca¹

and Paola Iovanna²

¹ DIET, University of Rome ”Sapienza”, 00184 Rome, Italy

² Ericsson Research, Via Moruzzi 1, 56124 Pisa, Italy

Appl. Sci. 2018, 8(4), 612; https://doi.org/10.3390/app8040612 - 12 Apr 2018

Cited by 22 | Viewed by 5782

Abstract

The Centralized Radio Access Network (C-RAN) provides a valid solution to overcome the problem of traditional RAN in scaling up to the needed processing resource and quality expected in 5G. The Common Public Rate Interface has been defined to transport traffic flows in [...] Read more.

The Centralized Radio Access Network (C-RAN) provides a valid solution to overcome the problem of traditional RAN in scaling up to the needed processing resource and quality expected in 5G. The Common Public Rate Interface has been defined to transport traffic flows in C-RAN and recently some market solutions are available. Its disadvantage is to increase by at least 10 times the needed bandwidth and for this reason its introduction will be gradual and will coexist with traditional RAN solutions in which Ethernet traffic is carried towards the radio base stations. In this paper, we propose an Xhaul optical network architecture based on Optical Transport Network (OTN) and Dense Wavelength Division Multiplexing (DWDM) technologies. The network allows for a dynamic allocation of the bandwidth resources according to the current traffic demand. The network topology is composed of OTN/DWDM rings and the objective of the paper is to evaluate the best configuration (number of rings and number of wavelengths needed) to both to minimize the cost and to provide an implementable solution. We introduce an analytical model for the evaluation of the number of wavelengths needed in each optical ring and provide some results for 5G case studies. We show how, although the single ring configuration provides the least cost solution due to the high statistical multiplexing advantage, it is not implementable because it needs switching apparatus with a too high number of ports. For this reason, more than one ring is needed and its value depends on several parameters as the offered traffic, the number of Radio Remote Units (RRU), the percentage of business sub-area and so on. Finally, the analytical model allows us to evaluate the advantages of the proposed dynamic resource allocation solution with respect to the static one in which the network is provided with a number of wavelengths determined in the scenario in which the radio station works at full load. The bandwidth saving can be in the order of 90% in a 5G traffic scenario. Full article

(This article belongs to the Special Issue Optical Communications and Networking Solutions for the Support of C-RAN in 5G Environments)

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14 pages, 8628 KiB

Open AccessArticle

Self-Interaction Attention Mechanism-Based Text Representation for Document Classification

by Jianming Zheng^†

, Fei Cai^*,†, Taihua Shao^† and Honghui Chen

¹ Science and Technology on Information Systems Engineering Laboratory, National University of Defense Technology, Changsha 410073, China

^† Co-first authors of this article.

Appl. Sci. 2018, 8(4), 613; https://doi.org/10.3390/app8040613 - 12 Apr 2018

Cited by 18 | Viewed by 3993

Abstract

Document classification has a broad application in the field of sentiment classification, document ranking and topic labeling, etc. Previous neural network-based work has mainly focused on investigating a so-called forward implication, i.e., the preceding text segments are taken as the context of the [...] Read more.

Document classification has a broad application in the field of sentiment classification, document ranking and topic labeling, etc. Previous neural network-based work has mainly focused on investigating a so-called forward implication, i.e., the preceding text segments are taken as the context of the following text segments when generating the text representation. Such a scenario typically ignores the fact that the semantics of a document are a product of the mutual implication of all text segments in a document. Thus, in this paper, we introduce a concept of interaction and propose a text representation model with Self-interaction Attention Mechanism (TextSAM) for document classification. In particular, we design three aggregated strategies to integrate the interaction into a hierarchical architecture for document classification, i.e., averaging the interaction, maximizing the interaction and adding one more attention layer on the interaction, which leads to three models, i.e., TextSAM_AVE, TextSAM_MAX and TextSAM_ATT, respectively. Our comprehensive experimental results on two public datasets, i.e., Yelp 2016 and Amazon Reviews (Electronics), show that our proposals can significantly outperform the state-of-the-art neural-based baselines for document classification, presenting a general improvement in terms of accuracy ranging from 5.97% to 14.05% against the best baseline. Furthermore, we find that our proposals with a self-interaction attention mechanism can obviously alleviate the impact brought by the increase of sentence number as the relative improvement of our proposals against the baselines are enlarged when the sentence number increases. Full article

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10 pages, 7408 KiB

Open AccessArticle

Using Allan Variance Based Semi-Parameter Model to Calibrate Pointing Errors of Alt-az Telescopes

by Lingjie Yan^1,2,3

, Yongmei Huang^1,2,* and Yahui Zhang^1,2

¹ Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China

² Institute of Optics and Electronics, Chinese Academy of Science, Chengdu 610209, China

³ College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100039, China

Appl. Sci. 2018, 8(4), 614; https://doi.org/10.3390/app8040614 - 13 Apr 2018

Cited by 17 | Viewed by 3104

Abstract

In this paper, a new model called Allan variance based semi-parameter model is put forward to improve the pointing precision for alt-az telescopes. As for electro-optical tracking systems, the precision of line-of-sight (LOS) pointing is seriously influenced by both geometric and nonlinear error [...] Read more.

In this paper, a new model called Allan variance based semi-parameter model is put forward to improve the pointing precision for alt-az telescopes. As for electro-optical tracking systems, the precision of line-of-sight (LOS) pointing is seriously influenced by both geometric and nonlinear error sources. In modeling part of the parameter model, a simplified mount model is set up to demonstrate impacts of geometric errors that are caused by imprecision during mechanical processes on LOS pointing, according to values of encoders and miss distances in charge-coupled-device (CCD) cameras. Considering the limitations of mount models, an improved hybrid model called the Allan variance based semi-parameter model is introduced to compensate for residual nonlinear errors in the calibration portion. Compared with the classical mount model, the Allan variance based semi-parameter model removes both geometric errors and nonlinear errors, and the LOS pointing precision has been remarkably improved after calibration of the proposed model. Full article

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7 pages, 1465 KiB

Open AccessCommunication

Photooxidation of p-Arsanilic Acid in Aqueous Solution by UV/Persulfate Process

by Xiangyi Shen¹, Jing Xu^2,*, Ivan P. Pozdnyakov^3,4 and Zizheng Liu^5,*

¹ Department of Environmental Science, School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China

² State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China

³ Institute of Chemical Kinetics and Combustion, Institutskaya 3, 630090 Novosibirsk, Russia

⁴ Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk, Russia

⁵ School of Civil Engineering, Wuhan University, Wuhan 430072, China

Appl. Sci. 2018, 8(4), 615; https://doi.org/10.3390/app8040615 - 13 Apr 2018

Cited by 10 | Viewed by 3526

Abstract

Used as a kind of feed additive, p-arsanilic acid can pose a potential risk to organisms when abandoned in the environment. The photodegradation of p-ASA was investigated under UV-C irradiation in the presence of persulfate (PS) in this work. The addition [...] Read more.

Used as a kind of feed additive, p-arsanilic acid can pose a potential risk to organisms when abandoned in the environment. The photodegradation of p-ASA was investigated under UV-C irradiation in the presence of persulfate (PS) in this work. The addition of PS facilitated the decomposition of p-ASA and notably, the presence of 50 mmol PS brought about a nearly complete mineralization after 3 h, while an insignificant total organic carbon (TOC) removal was observed under UV irradiation (λ = 254 nm) only. Experimental results proved that sulfate radical (SO₄•⁻) was responsible for the promotion effect. The cleavage of As-C bond released inorganic arsenic and caused the occurrence of various organic products, for example, hydroxybenzaldehyde, nitrobenzene, benzenediol sulfate, and biphenylarsinic acid. The application of PS with UV-C light may throw a light on thorough treatment for p-ASA containing wastewater. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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8 pages, 5053 KiB

Open AccessArticle

Trade-off between Photon Management Efficacy and Material Quality in Thin-Film Solar Cells on Nanostructured Substrates of High Aspect Ratio Structures

by Alan H. Chin^1,2,*, Majid Keshavarz^1,3 and Qi Wang^4,5

¹ nLiten Energy Corporation, 650 Castro Street, Suite 120–422, Mountain View, CA 94041, USA

² Affiliated with Arizona State University, School of Electrical, Computer, and Energy Engineering, Tempe, AZ 85287, USA

³ Currently with Natron Energy, 3542 Bassett St, Santa Clara, CA 95054, USA

⁴ National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA

⁵ Currently with Jinko Solar, 595 Market Street, Suite 2200, San Francisco, CA 94105, USA

Appl. Sci. 2018, 8(4), 616; https://doi.org/10.3390/app8040616 - 13 Apr 2018

Viewed by 3278

Abstract

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced [...] Read more.

Although texturing of the transparent electrode of thin-film solar cells has long been used to enhance light absorption via light trapping, such texturing has involved low aspect ratio features. With the recent development of nanotechnology, nanostructured substrates enable improved light trapping and enhanced optical absorption via resonances, a process known as photon management, in thin-film solar cells. Despite the progress made in the development of photon management in thin-film solar cells using nanostructures substrates, the structural integrity of the thin-film solar cells deposited onto such nanostructured substrates is rarely considered. Here, we report the observation of the reduction in the open circuit voltage of amorphous silicon solar cells deposited onto a nanostructured substrate with increasing areal number density of high aspect ratio structures. For a nanostructured substrate with the areal number density of such nanostructures increasing in correlation with the distance from one edge of the substrate, a correlation between the open circuit voltage reduction and the increase of the areal number density of high aspect ratio nanostructures of the front electrode of the small-size amorphous silicon solar cells deposited onto different regions of the substrate with graded nanostructure density indicates the effect of the surface morphology on the material quality, i.e., a trade-off between photon management efficacy and material quality. This observed trade-off highlights the importance of optimizing the morphology of the nanostructured substrate to ensure conformal deposition of the thin-film solar cell. Full article

(This article belongs to the Special Issue Nanostructured Photodetectors and Photovoltaic Devices)

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17 pages, 36512 KiB

Open AccessArticle

Waveguide Coupling via Magnetic Gratings with Effective Strips

by Kevin M. Roccapriore¹, David P. Lyvers^1,2, Dean P. Brown^2,3, Ekaterina Poutrina^2,3, Augustine M. Urbas³, Thomas A. Germer⁴ and Vladimir P. Drachev^1,5,*

¹ Department of Physics and Advance Materials Manufacturing Processing Institute, University of North Texas, Denton, TX 76203, USA

² UES, Inc., 4401 Dayton-Xenia Rd, Dayton, OH 45432, USA

³ Air Force Research Lab, Materials and Manufacturing Directorate, 3005 Hobson Way, Wright Patterson AFB, Dayton, OH 45433, USA

⁴ Sensor Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA

⁵ Center of Photonics & Quantum Materials, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia

Appl. Sci. 2018, 8(4), 617; https://doi.org/10.3390/app8040617 - 14 Apr 2018

Cited by 2 | Viewed by 3958

Abstract

Gratings with complex multilayer strips are studied under inclined incident light. Great interest in these gratings is due to applications as input/output tools for waveguides and as subwavelength metafilms. The structured strips introduce anisotropy in the effective parameters, providing additional flexibility in polarization [...] Read more.

Gratings with complex multilayer strips are studied under inclined incident light. Great interest in these gratings is due to applications as input/output tools for waveguides and as subwavelength metafilms. The structured strips introduce anisotropy in the effective parameters, providing additional flexibility in polarization and angular dependences of optical responses. Their characterization is challenging in the intermediate regime between subwavelength and diffractive modes. The transition between modes occurs at the Wood’s anomaly wavelength, which is different at different angle of incidence. The usual characterization with an effective film using permittivity

ε

and permeability

μ

has limited effectiveness at normal incidence but does not apply at inclined illumination, due to the effect of periodicity. The optical properties are better characterized with effective medium strips instead of an effective medium layer to account for the multilayer strips and the underlying periodic nature of the grating. This approach is convenient for describing such intermediate gratings for two types of applications: both metafilms and the coupling of incident waves to waveguide modes or diffraction orders. The parameters of the effective strips are retrieved by matching the spectral-angular map at different incident angles. Full article

(This article belongs to the Special Issue Metasurfaces: Physics and Applications)

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12 pages, 39428 KiB

Open AccessArticle

Effects of Electrode Structure and Electron Energy on Abatement of NO in Dielectric Barrier Discharge Reactor

by Weixuan Zhao¹

, Feng Wang², Yanghaichao Liu¹, Renxi Zhang^1,* and Huiqi Hou¹

¹ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Institute of Environmental Science, Fudan University, Shanghai 200433, China

² State Grid Rizhao Power Supply Company, Rizhao 276826, China

Appl. Sci. 2018, 8(4), 618; https://doi.org/10.3390/app8040618 - 15 Apr 2018

Cited by 10 | Viewed by 3525

Abstract

Electrode structure and electron energy effects on NO abatement were studied in two different structure DBD reactors. Final product analysis of NO abatement in coaxial cylinder dielectric barrier discharge (CC-DBD) and tubular multilayer dielectric barrier discharge (TM-DBD) reactors indicated that the electrode structure [...] Read more.

Electrode structure and electron energy effects on NO abatement were studied in two different structure DBD reactors. Final product analysis of NO abatement in coaxial cylinder dielectric barrier discharge (CC-DBD) and tubular multilayer dielectric barrier discharge (TM-DBD) reactors indicated that the electrode structure of TM-DBD was better under low O₂ concentration conditions, but the result was opposite because the new NO_x was produced in TM-DBD when O₂ concentration was increasing. In addition, results of particle-in-cell with Monte Carlo collisions (PIC-MCC) simulation manifested that the largest and the average electron energy were 12.09 eV and 3.35 eV in TM-DBD reactor, respectively, while they were 5.25 eV and 2.96 eV in CC-DBD reactor, respectively. CC-DBD electrode structures are preferable for better NO abatement and no new NO_x under oxygen-containing condition. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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19 pages, 24265 KiB

Open AccessArticle

Fault Diagnosis of Rotating Machinery Based on the Multiscale Local Projection Method and Diagonal Slice Spectrum

by Yong Lv^1,2, Rui Yuan^1,2,*

and Wei Shi³

¹ Key Laboratory of Metallurgical Equipment and Control Technology, Wuhan University of Science and Technology, Ministry of Education, Wuhan 430081, China

² Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China

³ Wuhan Ship Development & Design Institute, Wuhan 430064, China

Appl. Sci. 2018, 8(4), 619; https://doi.org/10.3390/app8040619 - 16 Apr 2018

Cited by 4 | Viewed by 3795

Abstract

The vibration signals of bearings and gears measured from rotating machinery usually have nonlinear, nonstationary characteristics. The local projection algorithm cannot only reduce the noise of the nonlinear system, but can also preserve the nonlinear deterministic structure of the signal. The influence of [...] Read more.

The vibration signals of bearings and gears measured from rotating machinery usually have nonlinear, nonstationary characteristics. The local projection algorithm cannot only reduce the noise of the nonlinear system, but can also preserve the nonlinear deterministic structure of the signal. The influence of centroid selection on the performance of noise reduction methods is analyzed, and the multiscale local projection method of centroid was proposed in this paper. This method considers both the geometrical shape and statistical error of the signal in high dimensional phase space, which can effectively eliminate the noise and preserve the complete geometric structure of the attractors. The diagonal slice spectrum can identify the frequency components of quadratic phase coupling and enlarge the coupled frequency component in the nonlinear signal. Therefore, the proposed method based on the above two algorithms can achieve more accurate results of fault diagnosis of gears and rolling bearings. The simulated signal is used to verify its effectiveness in a numerical simulation. Then, the proposed method is conducted for fault diagnosis of gears and rolling bearings in application researches. The fault characteristics of faulty bearings and gears can be extracted successfully in the researches. The experimental results indicate the effectiveness of the novel proposed method. Full article

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11 pages, 5435 KiB

Open AccessArticle

Ensemble Classification of Data Streams Based on Attribute Reduction and a Sliding Window

by Yingchun Chen^*, Ou Li, Yu Sun and Fei Li

National Digital Switching System Engineering & Technological Research and Development Center (NDSC), Zhengzhou 450000, China

Appl. Sci. 2018, 8(4), 620; https://doi.org/10.3390/app8040620 - 16 Apr 2018

Cited by 5 | Viewed by 3508

Abstract

With the current increasing volume and dimensionality of data, traditional data classification algorithms are unable to satisfy the demands of practical classification applications of data streams. To deal with noise and concept drift in data streams, we propose an ensemble classification algorithm based [...] Read more.

With the current increasing volume and dimensionality of data, traditional data classification algorithms are unable to satisfy the demands of practical classification applications of data streams. To deal with noise and concept drift in data streams, we propose an ensemble classification algorithm based on attribute reduction and a sliding window in this paper. Using mutual information, an approximate attribute reduction algorithm based on rough sets is used to reduce data dimensionality and increase the diversity of reduced results in the algorithm. A double-threshold concept drift detection method and a three-stage sliding window control strategy are introduced to improve the performance of the algorithm when dealing with both noise and concept drift. The classification precision is further improved by updating the base classifiers and their nonlinear weights. Experiments on synthetic datasets and actual datasets demonstrate the performance of the algorithm in terms of classification precision, memory use, and time efficiency. Full article

(This article belongs to the Special Issue Complex Networks and Machine Learning: From Molecular to Social Sciences)

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10 pages, 30162 KiB

Open AccessArticle

A Feasibility Study of Photoacoustic Detection of Hidden Dental Caries Using a Fiber-Based Imaging System

by Takuya Koyama¹, Satoko Kakino² and Yuji Matsuura^1,*

¹ Graduate School of Biomedical Engineering, Tohoku University, 6-6-05 Aoba, Sendai 980-8579, Japan

² Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo 113-8510, Japan

Appl. Sci. 2018, 8(4), 621; https://doi.org/10.3390/app8040621 - 17 Apr 2018

Cited by 7 | Viewed by 5899

Abstract

In this paper, the feasibility of an optical fiber-based photoacoustic imaging system for detecting caries lesions inside a tooth is examined. Models of hidden caries were prepared using a pigment with an absorption spectrum similar to that of real caries lesions, and the [...] Read more.

In this paper, the feasibility of an optical fiber-based photoacoustic imaging system for detecting caries lesions inside a tooth is examined. Models of hidden caries were prepared using a pigment with an absorption spectrum similar to that of real caries lesions, and the occlusal surface of the model teeth containing the pigment was irradiated with laser pulses with a wavelength of 532 nm. An examination of the frequency spectra of the emitted photoacoustic waves revealed that the spectra from simulated caries lesions included frequency components in the range of 0.5–1.2 MHz that were not seen in the spectra from healthy parts of the teeth. This indicates that hidden caries can be detected via a photoacoustic imaging technique. Accordingly, an imaging system for clinical applications was fabricated. It consists of a bundle of hollow-optical fibers for laser radiation and an acoustic probe that is attached to the tooth surface. Results of ex vivo imaging experiments using model teeth and an extracted tooth with hidden caries lesions show that relatively large caries lesions inside teeth that are not seen in visual inspections can be detected by focusing on the above frequency components of the photoacoustic waves. Full article

(This article belongs to the Special Issue Biomedical Photoacoustic and Thermoacoustic Imaging)

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16 pages, 11340 KiB

Open AccessArticle

A New Mixture Refrigerant for Space Heating Air Source Heat Pump: Theoretical Modelling and Performance Analysis

by Xiangrui Kong¹, Yufeng Zhang¹ and Jinzhe Nie^2,*

¹ School of Architecture, Tianjin University, Tianjin 300072, China

² Beijing Key Lab of Heating, Gas Supply, Ventilating and Air Conditioning Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

Appl. Sci. 2018, 8(4), 622; https://doi.org/10.3390/app8040622 - 17 Apr 2018

Cited by 9 | Viewed by 5083

Abstract

Air source heat pump (ASHP) is becoming a substitute for small coal boilers in rural residential buildings of North China. However, the application of ASHP faces challenges of heating capacity, energy efficiency, ozone depletion potential (ODP) and global warming potential (GWP). Proper refrigerant [...] Read more.

Air source heat pump (ASHP) is becoming a substitute for small coal boilers in rural residential buildings of North China. However, the application of ASHP faces challenges of heating capacity, energy efficiency, ozone depletion potential (ODP) and global warming potential (GWP). Proper refrigerant is a key factor influences the performance of ASHP. In this paper, a new mixture refrigerant named RHR-1 is proposed, which aimed to improve energy efficiency, eliminate ODP and reduce GWP of ASHP refrigerant. The performance of RHR-1 was analyzed and compared with commonly used refrigerants including R134a, R410A, R407C and R22 in terms of heating coefficient of performance (COP_h), compression ratio (CR) and discharging temperature (DT). The results show that, under the design cases, where supply water temperatures vary from 35 °C to 50 °C and outdoor air temperatures vary from −15 °C to 15 °C, the COP_h of RHR-1 are in the range of 2.43–4.93. The COP_h of RHR-1 is higher than other candidates when the supply water temperature is above 40 °C. The CR and DT of RHR-1 are in medium levels of the compared samples. A logarithmic regression equation was deduced to get the relationship of COP_h with temperature difference between supply water and outdoor air which suggested the temperature difference should be controlled within 47.5 °C to get reasonable COP_h. In addition, RHR-1 has no ODP, and its GWP is 279, which is much lower than other candidates. RHR-1 could be a reasonable refrigerant used in ASHP for space heating in North China. Full article

(This article belongs to the Special Issue New Heating and Cooling Concepts)

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13 pages, 11156 KiB

Open AccessArticle

Interface Shear Performance between Porous Polyurethane Mixture and Asphalt Sublayer

by Jun Chen¹

, Cheng Yao¹, Hao Wang^2,*

, Wei Huang², Xie Ma¹ and Junyu Qian³

¹ College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China

² Department of Civil and Environmental Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA

³ Department of Civil, Environmental and Ocean Engineering, Steven Institute of Technology, Hoboken, NJ 07030, USA

Appl. Sci. 2018, 8(4), 623; https://doi.org/10.3390/app8040623 - 17 Apr 2018

Cited by 23 | Viewed by 4384

Abstract

This paper aims to study interface shear performance between porous polyurethane mixture (PPM) and asphalt mixture with different adhesive materials. Polyurethane, epoxy resin, and SBS (styrene–butadiene–styrene) modified asphalt were selected as adhesive materials to fabricate composite specimens. The interface shear strength and shear [...] Read more.

This paper aims to study interface shear performance between porous polyurethane mixture (PPM) and asphalt mixture with different adhesive materials. Polyurethane, epoxy resin, and SBS (styrene–butadiene–styrene) modified asphalt were selected as adhesive materials to fabricate composite specimens. The interface shear strength and shear fatigue life of composite specimen was measured using inclined shear test. The research results emphasizes that it is necessary to apply adhesive material to the interface between PPM and asphalt mixture, since the untreated interface shear strength is smaller than the ones between two asphalt mixtures. The interface shear strength is affected by the thickness of adhesive layer, temperature, and freezing–thaw condition. In general, the greatest interface shear strength was achieved by using epoxy resin followed by polyurethane and then SBS modified asphalt at 25 °C as the adhesive layer thickness is the same. However, the interface shear strengths of composite specimen with three adhesive materials are similar to each other at high and low temperatures (60 °C and −18 °C) or after freezing–thaw cycles. On the other hand, the composite specimen with epoxy resin as adhesive material has the longest fatigue life; while the SBS modified asphalt has the least fatigue life at 25 °C. The research findings can help select the appropriate adhesive materials and increase the durability and service life of pavement when PPM is used as road surface layer for safety and noise reduction. Full article

(This article belongs to the Special Issue Achievements and Prospects of Advanced Pavement Materials Technologies)

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16 pages, 17795 KiB

Open AccessArticle

Effect of Carbon Black Nanoparticles from the Pyrolysis of Discarded Tires on the Performance of Asphalt and its Mixtures

by Chuangmin Li^1,2, Ziran Fan², Shaopeng Wu^3,*, Yuanyuan Li^3,*

, Youwei Gan² and Aoming Zhang⁴

¹ The Key Laboratory of Road Structure & Material Ministry of Transport, Beijing 100088, China

² School of Traffic and Transportation Engineering, Changsha University of Science and Technology, Changsha 410114, China

³ State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China

⁴ School of Civil Engineering and Architecture, Hubei University of Arts and Science, Xiangyang 441021, China

Appl. Sci. 2018, 8(4), 624; https://doi.org/10.3390/app8040624 - 17 Apr 2018

Cited by 39 | Viewed by 5396

Abstract

It is of great benefit to the environment and the economy to use discarded tires pyrolysis carbon black (TPCB) nanoparticles as a modifier for asphalt binders. A base asphalt binder with 60/80 penetration (GF-70) was selected to prepare the TPCB-modified asphalt binder (TPCB/GF-70) [...] Read more.

It is of great benefit to the environment and the economy to use discarded tires pyrolysis carbon black (TPCB) nanoparticles as a modifier for asphalt binders. A base asphalt binder with 60/80 penetration (GF-70) was selected to prepare the TPCB-modified asphalt binder (TPCB/GF-70) with a 15% dosage of TPCB by the melt blending method. The test instruments, such as Fourier transform infrared spectroscopy, laser particle size analyzer, and thermogravimetric analyzer, were used to study the characteristics of TPCB. The physical performance of GF-70 and TPCB/GF-70 were tested and the rheological properties were also tested with a dynamic shear rheometer to investigate TPCB’s effect on the performance of GF-70. In addition, the aromatic hydrocarbon oil (AHO) was used as the softening agent for TPCB/GF-70. The pavement performance of AC-13 and AC-20 was studied to evaluate the comprehensive effect of TPCB and AHO on the pavement performance of asphalt mixtures. Results show that a 15% dosage of TPCB can significantly improve the anti-rutting performance of GF-70, and decrease the low-temperature performance of GF-70 within one PG grade. AHO can obviously improve the low-temperature performance of TPCB/GF-70, but does not significantly decrease the high-temperature performance. With the addition of AHO and a 0.1% higher oil aggregate ratio, TPCB tends to significantly improve the anti-rutting performance and the low-temperature performance of TPCB-modified mixtures; the moisture stability of TPCB and AHO composite modified mixtures satisfies the requirement of water stability. Full article

(This article belongs to the Special Issue Achievements and Prospects of Advanced Pavement Materials Technologies)

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15 pages, 19577 KiB

Open AccessArticle

Diagnostics of Hydrogen-Containing Mixture Compression by a Two-Stage Piston Compressor with Cooling Demand Prediction

by Tomáš Brestovič¹, Mária Čarnogurská^1,*, Miroslav Příhoda², Peter Lukáč¹, Marián Lázár¹, Natália Jasminská¹ and Romana Dobáková¹

¹ Department of Power Engineering, Faculty of Mechanical Engineering, Technical University of Košice, Vysokoškolská 4, 042 00 Košice, Slovakia

² Department of Thermal Engineering, Faculty of Metallurgy and Materials Engineering, VŠB—Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava, Poruba, Czech Republic

Appl. Sci. 2018, 8(4), 625; https://doi.org/10.3390/app8040625 - 17 Apr 2018

Cited by 7 | Viewed by 5059

Abstract

The present article describes the diagnostics of a compressor that is compressing a mixture of H₂ and N₂ on the basis of the results that were obtained by operational measurements of the flow rates and temperatures at selected compressor sites, as [...] Read more.

The present article describes the diagnostics of a compressor that is compressing a mixture of H₂ and N₂ on the basis of the results that were obtained by operational measurements of the flow rates and temperatures at selected compressor sites, as well as of the acoustic pressure levels during the full loading thereof. The obtained data were subsequently used to determine the limit conditions of the compressor operations in terms of the cooling capacity. A thermodynamic analysis of the compression of the H₂/N₂ gas mixture was carried out with subsequent heat and energy flow calculation and the determination of the minimum cooling water flow rate that is required to ensure the continuous compressor operations. Full article

(This article belongs to the Special Issue Green Energy and Applications)

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10 pages, 272 KiB

Open AccessArticle

Ultrasound-Based Liver Stiffness Surveillance in Patients Treated for Chronic Hepatitis B or C

by Sheng-Hung Chen^1,2,3

and Cheng-Yuan Peng^2,3,*

¹ Graduate Institute of Clinical Medical Science, School of Medicine, China Medical University, Taichung 40447, Taiwan

² School of Medicine, China Medical University, Taichung 40402, Taiwan

³ Division of Hepatogastroenterology, Department of Internal Medicine, China Medical University Hospital, Taichung 40447, Taiwan

Appl. Sci. 2018, 8(4), 626; https://doi.org/10.3390/app8040626 - 17 Apr 2018

Cited by 3 | Viewed by 5243

Abstract

Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining [...] Read more.

Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining the LS progression or regression rate for refining LS measurement (LSM)-based prognostics. The paradigm of LSMs has altered the focus from liver fibrosis staging alone to comprehensive liver-relevant risk estimations. However, diverse ranges of cohort characteristics, disease types, surveillance protocols and timeframes, necroinflammatory resolutions or biochemical responses (BRs), factors explaining the magnitude or kinetics in LS change, virologic responses (VRs), fibrosis reversals (FRs), and noninvasive surveillance results have rarely been reviewed collectively. Elastography-based LS surveillance alone conveys chronological and valuable patient information and assists in characterizing worldwide patient cohorts under antiviral treatment by delineating the concurrent time elapsed, VR, BR, and FR. In groups with uniform VRs to direct-acting antivirals for chronic hepatitis C and nucleoside and nucleotide analogs for chronic hepatitis B, decline in LS can be explained using concurrent BR from 24 weeks to 3 years, followed by FR and the time elapsed. Full article

(This article belongs to the Special Issue Ultrasound Elastography)

27 pages, 15039 KiB

Open AccessArticle

Solar Radiation Parameters for Assessing Temperature Distributions on Bridge Cross-Sections

by Junqing Xue^1,*

, Jianhui Lin¹, Bruno Briseghella¹

, Habib Tabatabai²

and Baochun Chen¹

¹ College of Civil Engineering, Fuzhou University, Fuzhou, Fujian 350108, China

² Department of Civil and Environmental Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA

Appl. Sci. 2018, 8(4), 627; https://doi.org/10.3390/app8040627 - 17 Apr 2018

Cited by 35 | Viewed by 5189

Abstract

Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost- or time-prohibitive to obtain. A [...] Read more.

Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost- or time-prohibitive to obtain. A review of literature was carried out on estimation models for solar radiation parameters, including the global solar radiation, beam solar radiation and diffuse solar radiation. Solar radiation data from eight cities in Fujian Province in southeastern China were obtained on site. Solar radiation models applicable to Fujian, China were proposed and verified using the measured data. The linear Ångström–Page model (based on sunshine duration) can be used to estimate the daily global solar radiation. The Collares-Pereira and Rabl model and the Hottel model can be used to estimate the hourly global solar radiation and the beam solar radiation, respectively. Three bridges were chosen as case study, for which the temperature distribution on girder cross-sections were monitored on site. Finite element models (FEM) of cross-sections of bridge girders were implemented using the Midas program. The temperature–time curves obtained from FEM showed very close agreement with the measured values for summertime. Ignoring the solar radiation effect would result in lower and delayed temperature peaks. However, the influence of solar radiation on the temperature distribution in winter is negligible. Full article

(This article belongs to the Section Energy Science and Technology)

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13 pages, 2072 KiB

Open AccessArticle

Multi-Attributes, Utility-Based, Channel Quality Ranking Mechanism for Cognitive Radio Networks

by Youness Arjoune^*, Zakaria El Mrabet and Naima Kaabouch

Electrical Engineering Department, University of North Dakota; Grand Forks, ND 58202, USA; zakaria.elmrabet @und.edu (Z.E.M.); naima.kaabouch@engr.und.edu (N.K.)

Appl. Sci. 2018, 8(4), 628; https://doi.org/10.3390/app8040628 - 17 Apr 2018

Cited by 15 | Viewed by 4179

Abstract

Cognitive radio is an intelligent wireless solution that aims to enhance the access to the radio spectrum. In this technology, secondary users sense the radio spectrum, select the best channel among a pool of free channels, and determine the optimal transmission parameters to [...] Read more.

Cognitive radio is an intelligent wireless solution that aims to enhance the access to the radio spectrum. In this technology, secondary users sense the radio spectrum, select the best channel among a pool of free channels, and determine the optimal transmission parameters to meet their quality-of-service requirements while maximizing the spectral efficiency. Over the past decade, several channel-ranking mechanisms have been proposed. However, these mechanisms consider only the remaining idle time of the channel and exclude some crucial parameters. This convincingly demonstrates a strong need for a new channel quality-ranking model that jointly considers several parameters to select the best communication channel for transmission. This paper proposes a utility model that integrates several important parameters for ranking channels. First, we underline the importance of the process of the channel quality ranking. Then, we describe a multi-attributes, utility-based, channel quality-ranking model. Finally, we describe a series of experiments and their results, which show that our model effectively ranks the best communication channels first. Full article

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8 pages, 9949 KiB

Open AccessArticle

Blue and Orange Two-Color CW Laser Based on Single-Pass Second-Harmonic and Sum-Frequency Generation in MgO:PPLN

by Dismas K. Choge^1,2

, Huai-Xi Chen¹, Yi-Bin Xu¹, Lei Guo¹, Guang-Wei Li¹ and Wan-Guo Liang^1,*

¹ Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Appl. Sci. 2018, 8(4), 629; https://doi.org/10.3390/app8040629 - 18 Apr 2018

Cited by 8 | Viewed by 5029

Abstract

We demonstrate a compact blue and orange-two color continuous wave laser source emitting at 487 nm and from 597.4 to 600.3 nm, respectively. The temperature tunable coherent orange radiation is achieved by frequency mixing 974 nm laser diode (LD) and a C-band amplified [...] Read more.

We demonstrate a compact blue and orange-two color continuous wave laser source emitting at 487 nm and from 597.4 to 600.3 nm, respectively. The temperature tunable coherent orange radiation is achieved by frequency mixing 974 nm laser diode (LD) and a C-band amplified spontaneous emission laser source while the temperature insensitive blue radiation is generated by second-order quasi-phase-matching frequency doubling of 974 nm LD. We implement the simultaneous nonlinear processes in a single magnesium oxide doped periodically poled lithium niobate bulk crystal without the need of an aperiodic design. Full article

(This article belongs to the Section Optics and Lasers)

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21 pages, 18311 KiB

Open AccessArticle

Reconstruct Recurrent Neural Networks via Flexible Sub-Models for Time Series Classification

by Ye Ma^*

, Qing Chang, Huanzhang Lu and Junliang Liu

Laboratory of Automatic Target Recognition, College of Electronic Science, National University of Defense Technology (NUDT), Changsha 410073, China

Appl. Sci. 2018, 8(4), 630; https://doi.org/10.3390/app8040630 - 18 Apr 2018

Cited by 6 | Viewed by 4673

Abstract

Recurrent neural networks (RNNs) remain challenging, and there is still a lack of long-term memory or learning ability in sequential data classification and prediction. In this paper, we propose a flexible recurrent model, BIdirectional COnvolutional RaNdom RNNs (BICORN-RNNs), incorporating a series of sub-models: [...] Read more.

Recurrent neural networks (RNNs) remain challenging, and there is still a lack of long-term memory or learning ability in sequential data classification and prediction. In this paper, we propose a flexible recurrent model, BIdirectional COnvolutional RaNdom RNNs (BICORN-RNNs), incorporating a series of sub-models: random projection, convolutional operation, and bidirectional transmission. These subcategories advance classification accuracy, which was limited by the gradient vanishing and the exploding problem. Experiments on public time series datasets demonstrate that our proposed method substantially outperforms a variety of existing models. Furthermore, the coordination of the accuracy and efficiency concerning a variety of factors, including SNR, length, data missing, and overlapping, is also discussed. Full article

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14 pages, 5225 KiB

Open AccessArticle

Adaptive CoMP with Spatial Phase Coding for Interference Mitigation in the Heterogeneous Network

by Won-Chang Kim, Min-Jae Paek, Jae-Hyun Ro and Hyoung-Kyu Song^*

uT Communication Research Institute, Sejong University, Gunja-dong 98, Gwangjin-gu, Seoul 05006, Korea

Appl. Sci. 2018, 8(4), 631; https://doi.org/10.3390/app8040631 - 18 Apr 2018

Cited by 4 | Viewed by 3512

Abstract

This paper proposes an adaptive coordinated multi point (CoMP) scheme using pre-coding in order to improve the reliability of wireless communication systems based on orthogonal frequency division multiplexing (OFDM). In the conventional scheme, the received signal to noise ratio (SNR) of the mobile [...] Read more.

This paper proposes an adaptive coordinated multi point (CoMP) scheme using pre-coding in order to improve the reliability of wireless communication systems based on orthogonal frequency division multiplexing (OFDM). In the conventional scheme, the received signal to noise ratio (SNR) of the mobile is degraded due to the interference signal. Therefore, the bit error rate (BER) performance is degraded, as is, the reliability of the system, due to inter-cell interference (ICI). Therefore, the BER performance of the system is reduced and the transmitter must perform unnecessary re-transmission. The proposed scheme uses the CoMP scheme to improve reliability in a heterogeneous network (HetNet) system. Additionally, the proposed scheme uses the constructive spatial phase coding (SPC) scheme to mitigate the received SNR reduction due to the interference signal. Therefore, the proposed scheme can prevent performance degradation caused by the interference signal. When a mobile is located in the cell edge, the transmission signal is distorted by the transmitted signal from the adjacent cell. The proposed scheme can reduce the SNR of the interference signal by using the destructive SPC scheme. Therefore, this scheme can improve the reliability of the system. The simulation results show that the BER performance of the proposed scheme is better than that of the conventional scheme. As a result, the proposed scheme improves the reliability of systems by adaptively applying the CoMP and SPC schemes. Full article

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14 pages, 2156 KiB

Open AccessArticle

A Novel Swarm Optimisation Algorithm Based on a Mixed-Distribution Model

by Xiaoming Zhang^1,*

, Tinghao Feng², Qingsong Niu³ and Xijin Deng³

¹ School of Information and Computers, Anhui Agricultural University, Hefei 230031, China

² iFlytek Co. Ltd., Hefei 230088, China

³ Qinghai Institute of Science and Technology Information, Xining 810008, China

Appl. Sci. 2018, 8(4), 632; https://doi.org/10.3390/app8040632 - 18 Apr 2018

Cited by 9 | Viewed by 4055

Abstract

Many swarm intelligence optimisation algorithms have been inspired by the collective behaviour of natural and artificial, decentralised, self-organised systems. Swarm intelligence optimisation algorithms have unique advantages in solving certain complex problems that cannot be easily solved by traditional optimisation algorithms. Inspired by the [...] Read more.

Many swarm intelligence optimisation algorithms have been inspired by the collective behaviour of natural and artificial, decentralised, self-organised systems. Swarm intelligence optimisation algorithms have unique advantages in solving certain complex problems that cannot be easily solved by traditional optimisation algorithms. Inspired by the adaptive phenomena of plants, a novel evolutionary algorithm named the bean optimisation algorithm (BOA) is proposed, which combines natural evolutionary tactics and limited random searches. It demonstrates stable behaviour in experiments and is a promising alternative to existing optimisation methods for engineering applications. A novel distribution model for BOA is built through research and study on the relevant research results of biostatistics. This model is based on a combination of the negative binomial and normal distributions, and the resulting algorithm is called NBOA. To validate NBOA, function optimisation experiments are carried out, which include ten typical benchmark functions. The results indicate that NBOA performs better than particle swarm optimisation (PSO) and BOA. We also investigate the characteristics of NBOA and conduct a contrast analysis to verify our conclusions about the relationship between its parameters and its performance. Full article

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19 pages, 5055 KiB

Open AccessArticle

Experimental Investigation of the Creep Behaviour of Coal by Monitoring Changes of Acoustic Properties

by Sen Yang^1,2

, Nong Zhang^1,*

, Xiaowei Feng¹ and Jiaguang Kan¹

¹ Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China

² Department of Energy and Mineral Engineering, G3 Center and Energy Institute, The Pennsylvania State University, University Park, PA 16802, USA

Appl. Sci. 2018, 8(4), 633; https://doi.org/10.3390/app8040633 - 19 Apr 2018

Cited by 7 | Viewed by 4174

Abstract

Time-dependent deformation of coal is a major concern for deep coal mining. When experiencing high stress conditions, the enhanced time-dependent deformation of coal will become a very possible factor to trigger the violent failure of underground openings. For this study, the inner structural [...] Read more.

Time-dependent deformation of coal is a major concern for deep coal mining. When experiencing high stress conditions, the enhanced time-dependent deformation of coal will become a very possible factor to trigger the violent failure of underground openings. For this study, the inner structural variation of an extremely inhomogeneous coal subjected to incremental creep stress has been experimentally investigated by monitoring both the macroscopic deformation and acoustic property. Results show the following: (1) The pronounced inhomogeneity of coal induces considerable irregularities in creep strain data collected during the increase of stress level. These flawed data highlight the shortcomings of conventional strain-time relationship experiments for deciphering the mechanisms that control creep; (2) The mechanical response of samples under creep compression is the result of competition between compaction and cracking. Cracking deteriorates the structure and increases the ultrasonic attenuation, whilst the compaction causes the densification along the axial axis and reduces attenuation; (3) Long-term creep involves multiple structural deformations that alter the internal structure of the coal. This results in fluctuations of the ultrasonic velocities and their dynamic moduli; (4) During uploading phase of short term creep, vertical cracks develop and transform the sample into a structure consisting of separated columns. Further deterioration of the coal increases the possibility of tensile and shear failure of individual columns, which can trigger the violent collapse of an already fragile structure. Full article

(This article belongs to the Section Acoustics and Vibrations)

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11 pages, 2317 KiB

Open AccessArticle

Enhancement of Neuroprotective Effects of Spirulina platensis Extract from a High-Pressure Homogenization Process

by Woon Yong Choi¹ and Hyeon Yong Lee^2,*

¹ Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon 200-701, Korea

² Department of Food Science and Engineering, Seowon University, Cheongju 361-742, Korea

Appl. Sci. 2018, 8(4), 634; https://doi.org/10.3390/app8040634 - 19 Apr 2018

Cited by 10 | Viewed by 4242

Abstract

This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear [...] Read more.

This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear stress of approximately 20,000 (1/s) compared to 5.27 mg/g from conventional 70% ethanol extraction (EE) at 40 °C for 24 h. However, a higher input pressure did not increase the extraction yield and in fact decreased it, possibly due to the destruction of chlorophyll a at a high shear stress of approximately 50,000 (1/s) under 1370 bar of input pressure. Chlorophyll a and other components of the extract had additive effects, showing higher antioxidant activities of ca. 56% of DPPH radical scavenging activities than 10 μg/mL chlorophyll a alone, which corresponded to the same chlorophyll a content that existed in the extract. It was also confirmed that the high antioxidant activities of the HP extract reduced the production of reactive oxygen species (ROS) from glutamate-induced HT22 cells, which resulted in increased neuroprotective activity compared to EE and even chlorophyll a alone, in addition to effectively reducing the release of Ca²⁺ from nerve cells. Full article

(This article belongs to the Special Issue Acoustic and Hydrodynamic Effects in Food Processing)

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11 pages, 27259 KiB

Open AccessArticle

Histological and Bone Morphometric Evaluation of Osseointegration Aspects by Alkali Hydrothermally-Treated Implants

by Hanako Umehara, Reiko Kobatake, Kazuya Doi^*, Yoshifumi Oki, Yusuke Makihara, Takayasu Kubo and Kazuhiro Tsuga

Department of Advanced Prosthodontics, Hiroshima University Graduate School of Biomedical and Health Sciences, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8553, Japan

Appl. Sci. 2018, 8(4), 635; https://doi.org/10.3390/app8040635 - 19 Apr 2018

Cited by 6 | Viewed by 4373

Abstract

The purpose of this study was to investigate the osseointegration aspects of alkali-treated implants by histological and bone morphometric evaluations. Titanium implants (control) and alkali hydrothermally-treated titanium implants were used. Samples were evaluated by surface structure observation and wettability tests. Both implants were [...] Read more.

The purpose of this study was to investigate the osseointegration aspects of alkali-treated implants by histological and bone morphometric evaluations. Titanium implants (control) and alkali hydrothermally-treated titanium implants were used. Samples were evaluated by surface structure observation and wettability tests. Both implants were placed into the femurs of five rabbits, and osseointegration was assessed by measurement of removal torque (RT), bone–implant contact ratio (BIC), and bone tissue area ratio (BTA). Measurements were performed at the whole portion around the implant, the cortical bone portion, and the bone marrow portion. The surface structure of alkali-group showed nanoscale pores and super hydrophilicity. RT, BIC, and BTA values of alkali-group were significantly higher than those of control-group at the whole portion. In the cortical bone portion, the BIC value was higher in the alkali-group than in the control-group, and BTA showed no significant difference between groups. In the bone marrow portion, even though no significant difference between control and alkali groups, the latter had higher ratio of BIC than the former. These results indicate that alkali treated implants enhance bone integration in areas where the implant is in contact with bone, and may promote osteoinduction in the non-bone marrow portion. Full article

(This article belongs to the Section Materials Science and Engineering)

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19 pages, 6961 KiB

Open AccessArticle

Forecasting of Power Grid Investment in China Based on Support Vector Machine Optimized by Differential Evolution Algorithm and Grey Wolf Optimization Algorithm

by Shuyu Dai^1,2,*, Dongxiao Niu^1,2 and Yaru Han^1,2

¹ School of Economics and Management, North China Electric Power University, Beijing 102206, China

² Beijing Key Laboratory of New Energy and Low-Carbon Development, North China Electric Power University, Beijing 102206, China

Appl. Sci. 2018, 8(4), 636; https://doi.org/10.3390/app8040636 - 19 Apr 2018

Cited by 40 | Viewed by 6047

Abstract

In recent years, the construction of China’s power grid has experienced rapid development, and its scale has leaped into the first place in the world. Accurate and effective prediction of power grid investment can not only help pool funds and rationally arrange investment [...] Read more.

In recent years, the construction of China’s power grid has experienced rapid development, and its scale has leaped into the first place in the world. Accurate and effective prediction of power grid investment can not only help pool funds and rationally arrange investment in power grid construction, but also reduce capital costs and economic risks, which plays a crucial role in promoting power grid investment planning and construction process. In order to forecast the power grid investment of China accurately, firstly on the basis of analyzing the influencing factors of power grid investment, the influencing factors system for China’s power grid investment forecasting is constructed in this article. The method of grey relational analysis is used for screening the main influencing factors as the prediction model input. Then, a novel power grid investment prediction model based on DE-GWO-SVM (support vector machine optimized by differential evolution and grey wolf optimization) algorithm is proposed. Next, two cases are taken for empirical analysis to prove that the DE-GWO-SVM model has strong generalization capacity and has achieved a good prediction effect for power grid investment forecasting in China. Finally, the DE-GWO-SVM model is adopted to forecast power grid investment in China from 2018 to 2022. Full article

(This article belongs to the Section Energy Science and Technology)

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18 pages, 32924 KiB

Open AccessArticle

Multi-Plane Ultrafast Compound 3D Strain Imaging: Experimental Validation in a Carotid Bifurcation Phantom

by Stein Fekkes^*

, Anne E. C. M. Saris

, Jan Menssen, Maartje M. Nillesen, Hendrik H. G. Hansen

and Chris L. De Korte

Medical Ultrasound Imaging Center, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands

Appl. Sci. 2018, 8(4), 637; https://doi.org/10.3390/app8040637 - 20 Apr 2018

Cited by 9 | Viewed by 4828

Abstract

Strain imaging of the carotid artery (CA) has demonstrated to be a technique capable of identifying plaque composition. This study assesses the performance of volumetric strain imaging derived from multi-plane acquisitions with a single transducer, with and without displacement compounding. These methods were [...] Read more.

Strain imaging of the carotid artery (CA) has demonstrated to be a technique capable of identifying plaque composition. This study assesses the performance of volumetric strain imaging derived from multi-plane acquisitions with a single transducer, with and without displacement compounding. These methods were compared to a reference method using two orthogonally placed transducers. A polyvinyl alcohol phantom was created resembling a stenotic CA bifurcation. A realistic pulsatile flow was imposed on the phantom, resulting in fluid pressures inducing 10% strains. Two orthogonally aligned linear array transducers were connected to two Verasonics systems and fixed in a translation stage. For 120 equally spaced elevational positions, ultrasound series were acquired for a complete cardiac cycle and synchronized using a trigger. Each series consisted of ultrafast plane-wave acquisitions at 3 alternating angles. Inter-frame displacements were estimated using a 3D cross-correlation-based tracking algorithm. Horizontal displacements were acquired using the single probe lateral displacement estimate, the single probe compounded by axial displacement estimates obtained at angles of 19.47 and −19.47 degrees, and the dual probe registered axial displacement estimate. After 3D tracking, least squares strain estimations were performed to compare compressive and tensile principal strains in 3D for all methods. The compounding technique clearly outperformed the zero-degree method for the complete cardiac cycle and resulted in more accurate 3D strain estimates. Full article

(This article belongs to the Special Issue Ultrafast Ultrasound Imaging)

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15 pages, 5871 KiB

Open AccessArticle

Trouton’s Rule for Vapor Sorption in Solids

by Ard-Jan De Jong^1,* and Hartmut Fischer²

¹ TNO, Leeghwaterstraat 46, 2628 CA Delft, The Netherlands

² TNO, High Tech Campus 5, 5656 AE Eindhoven, The Netherlands

Appl. Sci. 2018, 8(4), 638; https://doi.org/10.3390/app8040638 - 20 Apr 2018

Cited by 3 | Viewed by 7297

Abstract

Hygroscopic salts exhibiting fast and reversible hydration are promising systems for seasonal heat storage, providing the possibility of storing excess solar energy from the warm season for later use during the cold season. For heat storage, the salt is dehydrated with the available [...] Read more.

Hygroscopic salts exhibiting fast and reversible hydration are promising systems for seasonal heat storage, providing the possibility of storing excess solar energy from the warm season for later use during the cold season. For heat storage, the salt is dehydrated with the available heat, and for heat recovery, the salt is rehydrated. There are many salt hydration transitions and for selecting the most suited ones with respect to the envisaged use cases, temperatures of dehydration and rehydration are needed, as well as the heat storage density. Estimation of these properties requires entropy and enthalpy changes of the transitions. Collections of hydration entropies and enthalpies have been published, but not all data seems reliable for various reasons, and it is often hard to access original sources and experimental conditions. For the necessary data validation, we propose the use of Trouton’s rule, known to hold for the evaporation of classes of fluids. Besides data validation, Trouton’s rule is useful for predicting heat storage densities and vapor pressures when only the transition enthalpy is known. We discuss the validity of Trouton’s rule for salt hydration and ammoniation transitions by theoretical and experimental evidence on the available extensive data collections. Full article

(This article belongs to the Special Issue Materials for Thermal Energy Storage)

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17 pages, 7586 KiB

Open AccessArticle

Development of Proportional Pressure Control Valve for Hydraulic Braking Actuator of Automobile ABS

by Che-Pin Chen and Mao-Hsiung Chiang^*

Department of Engineering Science and Ocean Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei City 106, Taiwan

Appl. Sci. 2018, 8(4), 639; https://doi.org/10.3390/app8040639 - 20 Apr 2018

Cited by 19 | Viewed by 12273

Abstract

This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high [...] Read more.

This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high controllability and ease of production, the driver of this proportional valve was designed with a small volume and powerful solenoid force to control braking pressure and flow. Since the proportional valve can have closed-loop control, the proportional valve can replace a conventional solenoid valve in current brake actuators. With the proportional valve controlling braking and pressure relief mode, it can narrow the space of hydraulic braking actuator, and precisely control braking force to achieve safety objectives. Finally, the proposed novel proportional pressure control valve of an automobile hydraulic braking actuator was implemented and verified experimentally. Full article

(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)

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12 pages, 10870 KiB

Open AccessArticle

Fusion of Spectra and Texture Data of Hyperspectral Imaging for the Prediction of the Water-Holding Capacity of Fresh Chicken Breast Filets

by Yi Yang¹, Wei Wang^1,*

, Hong Zhuang², Seung-Chul Yoon² and Hongzhe Jiang¹

¹ College of Engineering, China Agricultural University, Beijing 100083, China

² Quality & Safety Assessment Research Unit, U. S. National Poultry Research Center, USDA-ARS, 950 College Station Rd., Athens, GA 30605, USA

Appl. Sci. 2018, 8(4), 640; https://doi.org/10.3390/app8040640 - 20 Apr 2018

Cited by 35 | Viewed by 5598

Abstract

This study investigated the fusion of spectra and texture data of hyperspectral imaging (HSI, 1000–2500 nm) for predicting the water-holding capacity (WHC) of intact, fresh chicken breast filets. Three physical and chemical indicators—drip loss, expressible fluid, and salt-induced water gain—were measured to be [...] Read more.

This study investigated the fusion of spectra and texture data of hyperspectral imaging (HSI, 1000–2500 nm) for predicting the water-holding capacity (WHC) of intact, fresh chicken breast filets. Three physical and chemical indicators—drip loss, expressible fluid, and salt-induced water gain—were measured to be different WHC references of chicken meat. Different partial least squares regression (PLSR) models were established with corresponding input variables including the full spectra, key wavelengths, and texture variables, as well as the fusion data of key wavelengths and the corresponding texture variables, respectively. The results demonstrated that for drip loss and expressible fluid, texture data was an effective supplement to spectra data, and fusion data as an input variable could effectively improve the predictive ability of the independent prediction set (Rp = 0.80, RMSEp = 0.80; Rp = 0.56, RMSEp = 2.10). While the best model to predict salt-induced water gain was based on key wavelengths (Rp = 0.69, RMSEp = 18.04), this was mainly because salt-induced water gain was measured on mince samples, which lacked the important physical structure to represent the texture information of meat. Our results of this study demonstrated the potential to further improve the evaluation of the WHC of chicken meat by HSI. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

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18 pages, 3854 KiB

Open AccessArticle

Power System Voltage Correction Scheme Based on Adaptive Horizon Model Predictive Control

by Yan Zhang^1,*, Meng Liu¹, Wen Zhang², Wenchuan Sun³, Xingwang Hu³ and Gang Kong¹

¹ State Grid Shandong Electric Power Research Institute, Jinan 250003, China

² Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education, Shandong University, Jinan 250061, China

³ State Grid Shandong Electric Power Company, Jinan 250001, China

Appl. Sci. 2018, 8(4), 641; https://doi.org/10.3390/app8040641 - 20 Apr 2018

Cited by 2 | Viewed by 4217

Abstract

Model predictive control (MPC) is commonly used to compensate for modeling inaccuracies and measurement noise in voltage control problems. The length of the prediction horizon and control horizon of a MPC-based method has significant impact on the control performances. In existing relevant works, [...] Read more.

Model predictive control (MPC) is commonly used to compensate for modeling inaccuracies and measurement noise in voltage control problems. The length of the prediction horizon and control horizon of a MPC-based method has significant impact on the control performances. In existing relevant works, those horizon parameters are determined off-line based on experience or enumeration, and keeps constant during the entire receding-horizon optimization process. This paper presents a system voltage correction scheme based on adaptive horizon model predictive control (AH-MPC). The reactive power compensation and voltage regulation devices are coordinated to maintain the system voltages within a desired range. An evaluation index is proposed to determine the horizon parameters, which reflects the maximum voltage regulation ability with the current parameter configuration. Within each sampling interval, the horizon parameters are updated according to the evaluation index and real-time measurements periodically, which comprehensively considers the system uncertainties and voltage recovery speed, and the computational effort is remarkably reduced. The validation and effectiveness of the proposed method is verified by the simulation analysis on the test system. Full article

(This article belongs to the Special Issue Smart Grid and Smart Cities Activities)

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13 pages, 4401 KiB

Open AccessFeature PaperArticle

Stability Analysis of Stagnation-Point Flow in a Nanofluid over a Stretching/Shrinking Sheet with Second-Order Slip, Soret and Dufour Effects: A Revised Model

by Najwa Najib^*

, Norfifah Bachok, Norihan Md Arifin and Fadzilah Md Ali

Department of Mathematics and Institute for Mathematical Research, Universiti Putra Malaysia, UPM Serdang, Selangor 43400, Malaysia

Appl. Sci. 2018, 8(4), 642; https://doi.org/10.3390/app8040642 - 20 Apr 2018

Cited by 32 | Viewed by 5284

Abstract

The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were [...] Read more.

The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were transformed into the ordinary differential equations by applying a suitable similarity transformation. The numerical results were obtained by using bvp4c codes in Matlab. The skin friction coefficient, heat transfer coefficient, mass transfer coefficient, as well as the velocity, temperature, and concentration profiles were presented graphically for different values of slip parameters, Soret effect, Dufour effect, Brownian motion parameter, and thermophoresis parameter. A dual solution was obtained in this present paper. The presence of the slip parameters (first- and second-order slip parameters) was found to expand the range of solutions. However, the presence of the slip parameters led to a decrease in the skin friction coefficient, whereas the heat transfer coefficient increased. Besides that, a larger Soret effect (smallest Dufour effect) led to the decrement of the heat transfer coefficient. The effects of the Brownian motion and thermophoresis parameters on the heat transfer coefficient were also studied in this paper. A stability analysis was performed in this paper to verify the stability of the solutions obtained. Full article

(This article belongs to the Special Issue Nanofluids and Their Applications)

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6 pages, 2830 KiB

Open AccessCommunication

Carbon Nanotube Mode-Locked Fiber Laser Generating Cylindrical Vector Beams with a Two-Mode Fiber Bragg Grating

by Yu Cai¹, Jiaojiao Zhang¹, Changle Wang², Lin Zhang² and Zuxing Zhang^1,*

¹ Advanced Photonic Technology Lab, College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

² Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET, UK

Appl. Sci. 2018, 8(4), 643; https://doi.org/10.3390/app8040643 - 20 Apr 2018

Cited by 2 | Viewed by 4305

Abstract

We propose and demonstrate a compact all-fiber laser generating cylindrical vector beam (CVB) using carbon nanotubes as the saturable absorber for mode-locking and a two-mode fiber Bragg grating (TM-FBG) as the mode discriminator. Both radially and azimuthally polarized beams with a polarization purity [...] Read more.

We propose and demonstrate a compact all-fiber laser generating cylindrical vector beam (CVB) using carbon nanotubes as the saturable absorber for mode-locking and a two-mode fiber Bragg grating (TM-FBG) as the mode discriminator. Both radially and azimuthally polarized beams with a polarization purity of 90% were obtained by simply adjusting the polarization controllers. The CVB mode-locked fiber laser operates at 1552.9 nm with a 3-dB line width of less than 0.02 nm, generating ns CVB pulses. The all-fiber CVB laser may have potential applications from fundamental research to practical applications, such as particle capture, high-resolution measurement and material processing. Full article

(This article belongs to the Special Issue Erbium-doped Fiber Lasers)

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10 pages, 5501 KiB

Open AccessArticle

Camera Calibration with Phase-Shifting Wedge Grating Array

by Jiayuan Tao, Yuwei Wang, Bolin Cai and Keyi Wang^*

Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China

Appl. Sci. 2018, 8(4), 644; https://doi.org/10.3390/app8040644 - 20 Apr 2018

Cited by 8 | Viewed by 5069

Abstract

Planar targets with known features have been widely used for camera calibration in various vision systems. This paper utilizes phase-shifting wedge grating (PWG) arrays as an active calibration target. Features points are encoded into the carrier phase, which can be accurately calculated using [...] Read more.

Planar targets with known features have been widely used for camera calibration in various vision systems. This paper utilizes phase-shifting wedge grating (PWG) arrays as an active calibration target. Features points are encoded into the carrier phase, which can be accurately calculated using the phase-shifting algorithm. The 2π-phase points are roughly extracted with edge detection and then optimized by windowed bicubic fitting with sub-pixel accuracy. Two 2π-phase lines for each PWG are obtained using linear fitting method. The PWG centers that are used as feature points are detected through computing the intersections of 2π-phase lines. Experiment results indicate that the proposed method is accurate and reliable. Full article

(This article belongs to the Section Optics and Lasers)

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32 pages, 9373 KiB

Open AccessArticle

Proposing Enhanced Feature Engineering and a Selection Model for Machine Learning Processes

by Muhammad Fahim Uddin^1,*, Jeongkyu Lee¹, Syed Rizvi² and Samir Hamada³

¹ School of Computer Science and Engineering, University of Bridgeport, 126 Park Ave, Bridgeport, CT 06604, USA

² Information Science and Technologies, Penn State University, 3000 Ivyside Park, Altoona, PA 16601, USA

³ Computer Systems, School of Business, Farmingdale State College, 2350 Broadhollow Rd, Farmingdale, NY 11735, USA

Appl. Sci. 2018, 8(4), 646; https://doi.org/10.3390/app8040646 - 20 Apr 2018

Cited by 50 | Viewed by 10269

Abstract

Machine Learning (ML) requires a certain number of features (i.e., attributes) to train the model. One of the main challenges is to determine the right number and the type of such features out of the given dataset’s attributes. It is not uncommon for [...] Read more.

Machine Learning (ML) requires a certain number of features (i.e., attributes) to train the model. One of the main challenges is to determine the right number and the type of such features out of the given dataset’s attributes. It is not uncommon for the ML process to use dataset of available features without computing the predictive value of each. Such an approach makes the process vulnerable to overfit, predictive errors, bias, and poor generalization. Each feature in the dataset has either a unique predictive value, redundant, or irrelevant value. However, the key to better accuracy and fitting for ML is to identify the optimum set (i.e., grouping) of the right feature set with the finest matching of the feature’s value. This paper proposes a novel approach to enhance the Feature Engineering and Selection (eFES) Optimization process in ML. eFES is built using a unique scheme to regulate error bounds and parallelize the addition and removal of a feature during training. eFES also invents local gain (LG) and global gain (GG) functions using 3D visualizing techniques to assist the feature grouping function (FGF). FGF scores and optimizes the participating feature, so the ML process can evolve into deciding which features to accept or reject for improved generalization of the model. To support the proposed model, this paper presents mathematical models, illustrations, algorithms, and experimental results. Miscellaneous datasets are used to validate the model building process in Python, C#, and R languages. Results show the promising state of eFES as compared to the traditional feature selection process. Full article

(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)

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18 pages, 4663 KiB

Open AccessArticle

Novel Guidance CPS Based on the FatBeacon Protocol

by Moisés Lodeiro-Santiago^*, Iván Santos-González, Cándido Caballero-Gil

, Pino Caballero-Gil

and Félix Herrera-Priano

Departamento de Ingeniería Informática y de Sistemas, Universidad de La Laguna, Tenerife 38200, Spain

Appl. Sci. 2018, 8(4), 647; https://doi.org/10.3390/app8040647 - 20 Apr 2018

Cited by 4 | Viewed by 4278

Abstract

Throughout this work, the use of a new technology is proposed to give an innovative solution to the problem of indoor and outdoor positioning and a guidance system in areas where there is no coverage of Internet or global positioning systems. This novel [...] Read more.

Throughout this work, the use of a new technology is proposed to give an innovative solution to the problem of indoor and outdoor positioning and a guidance system in areas where there is no coverage of Internet or global positioning systems. This novel solution is based on the Bluetooth protocol called FatBeacon, created by Google, which can be used in places such as subway stations located below ground, outdoor areas where even 2G coverage is unreachable or simply as an alternative to current technologies that may require an additional cost, such as the Internet in some countries. In particular, this work describes a new solution for supporting tourism called Smart Tourism for which an interactive and non-intrusive guidance application based on the FatBeacon protocol is presented. The developed application informs the users about the way to reach their destination without getting lost and can be used to obtain user data tracking anonymously. In this way, the cooperation between the different systems and components of the scheme creates a distributed ecosystem that is independent of an Internet connection. Since no FatBeacon implementations can be found yet, an experimental implementation was developed to test the proposal, and the obtained results are promising. Full article

(This article belongs to the Special Issue Security and Privacy for Cyber Physical Systems)

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23 pages, 2160 KiB

Open AccessArticle

Energy Management Scheme for an EV Smart Charger V2G/G2V Application with an EV Power Allocation Technique and Voltage Regulation

by Saad Ullah Khan¹

, Khawaja Khalid Mehmood¹

, Zunaib Maqsood Haider¹, Syed Basit Ali Bukhari¹

, Soon-Jeong Lee², Muhammad Kashif Rafique¹ and Chul-Hwan Kim^1,*

¹ College of Information and Communication Engineering, Sungkyunkwan University, Suwon 16419, Korea

² KEPCO Economy and Management Research Institute, Naju 58217, Korea

Appl. Sci. 2018, 8(4), 648; https://doi.org/10.3390/app8040648 - 21 Apr 2018

Cited by 55 | Viewed by 10569

Abstract

The increasing penetration of electric vehicles (EVs) in the distribution grid has established them as a prospective resource for ancillary services. These services require adequate control strategies for prompt and efficient operation. In this study, an energy management scheme (EMS) has been proposed [...] Read more.

The increasing penetration of electric vehicles (EVs) in the distribution grid has established them as a prospective resource for ancillary services. These services require adequate control strategies for prompt and efficient operation. In this study, an energy management scheme (EMS) has been proposed to employ an off-board EV smart charger to support the grid during short-term variance of renewables and reactive load onset. The scheme operates by calculating power references for the charger instantaneously. The EMS incorporates a proportional power division methodology, proposed to allocate power references to the individual EVs connected to the charger DC-bus. This methodology considers the state-of-charge and battery sizes of the EVs, and it can aggregate energy from various types of EVs. The proposed scheme is compared with another power allocation method, and the entire EMS is tested under the scenarios of power mismatch and voltage sag/swell events. The results show that the proposed scheme achieves the goal of the aggregation of EVs at the charger level to support the grid. The EMS also fulfills the objectives of voltage regulation and four-quadrant operation of the smart charger. Full article

(This article belongs to the Special Issue Developing and Implementing Smart Grids: Novel Technologies, Techniques and Models)

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22 pages, 11977 KiB

Open AccessArticle

Lyapunov Equivalent Representation Form of Forced, Damped, Nonlinear, Two Degree-of-Freedom Systems

by Alex Elías-Zúñiga^1,*

, Luis M. Palacios-Pineda²

, Daniel Olvera-Trejo¹ and Oscar Martínez-Romero¹

¹ Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L., C.P. 64849, Mexico

² División de Estudios de Posgrado e Investigación, Tecnológico Nacional de México/Instituto Tecnológico de Pachuca, Carr. México-Pachuca Km 87.5, Pachuca, Hidalgo, C.P. 42080, Mexico

Appl. Sci. 2018, 8(4), 649; https://doi.org/10.3390/app8040649 - 21 Apr 2018

Cited by 11 | Viewed by 4429

Abstract

The aim of this paper focuses on finding equivalent representation forms of forced, damped, two degree-of-freedom, nonlinear systems in the sense of Lyapunov by using a nonlinear transformation approach that provides decoupled, forced, damped, nonlinear equations of the Duffing type, under the assumption [...] Read more.

The aim of this paper focuses on finding equivalent representation forms of forced, damped, two degree-of-freedom, nonlinear systems in the sense of Lyapunov by using a nonlinear transformation approach that provides decoupled, forced, damped, nonlinear equations of the Duffing type, under the assumption that the driving frequency and the external forces are equal in both systems. The values of Lyapunov characteristic exponents (LCEs), Lyapunov largest exponents (LLE), and time-amplitude and frequency-amplitude curves computed from numerical integration solutions, indicate that the decoupled Duffing-type equations are equivalent, in the sense of Lyapunov, to the original dynamic system, since both set of motion equations tend to have the same qualitative and quantitative behaviors. Full article

(This article belongs to the Section Mechanical Engineering)

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22 pages, 11454 KiB

Open AccessArticle

Dynamic Response of a Long-Span Concrete-Filled Steel Tube Tied Arch Bridge and the Riding Comfort of Monorail Trains

by Hongye Gou^1,2,3

, Wen Zhou¹, Changwei Yang^1,2,*, Yi Bao³ and Qianhui Pu¹

¹ Department of Bridge Engineering, School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China

² Key Laboratory of High-Speed Railway Engineering, Ministry of Education, Chengdu 610031, China

³ Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO 65401, USA

Appl. Sci. 2018, 8(4), 650; https://doi.org/10.3390/app8040650 - 23 Apr 2018

Cited by 39 | Viewed by 8907

Abstract

In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to [...] Read more.

In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to investigate the dynamic behaviors of the bridge under moving trains. A refined three-dimensional finite element model is built for the bridge and a 15 degrees-of-freedom vehicle model is presented for the train. The numerical model is validated using in-situ test results and then used to analyze the dynamic displacement and acceleration of the bridge and the trains on the bridge. Based on the simulation results, the impact factor of the bridge is investigated and the riding comfort of the trains is evaluated. The investigation results show that the impact factor of vehicle loads reaches the maximum value when the resonance of the bridge is induced by the moving vehicles. The effect of train braking predominates the longitudinal vibration of the bridge but is negligible in the transverse and vertical directions. The vehicle speed is the dominating factor for the riding comfort of the train. Full article

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15 pages, 9735 KiB

Open AccessArticle

On the Statistical Characterization of Lightning-Induced Voltages

by Amedeo Andreotti¹

, Fabio Mottola^2,*

, Antonio Pierno¹

and Daniela Proto¹

¹ University of Naples Federico II, Via Claudio 21, 80125 Naples, Italy

² University of Naples Parthenope, Centro Direzionale di Napoli, Is. C4, 80143 Naples, Italy

Appl. Sci. 2018, 8(4), 651; https://doi.org/10.3390/app8040651 - 23 Apr 2018

Cited by 12 | Viewed by 4335

Abstract

Protection against lightning-induced voltages is a particularly critical issue, especially for smart grids, due to the presence of electronic-based equipment, as well as control and monitoring devices. Analysis of the severity of the induced voltages is then imperative; on the other hand, the [...] Read more.

Protection against lightning-induced voltages is a particularly critical issue, especially for smart grids, due to the presence of electronic-based equipment, as well as control and monitoring devices. Analysis of the severity of the induced voltages is then imperative; on the other hand, the random nature of the lightning phenomenon cannot be disregarded. In this paper, the severity of lightning-induced voltage is analyzed by means of a probabilistic approach which, starting from closed-form solutions, uses a Monte Carlo procedure. Parametric distributions that best fit the distributions of the induced voltages are investigated as well. The results show that the lognormal and the generalized extreme value distributions are the best candidates. Full article

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13 pages, 878 KiB

Open AccessArticle

Rapid High-Resolution Wavenumber Extraction from Ultrasonic Guided Waves Using Adaptive Array Signal Processing

by Shigeaki Okumura^1,*, Vu-Hieu Nguyen², Hirofumi Taki³, Guillaume Haïat⁴, Salah Naili² and Toru Sato¹

¹ Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan

² Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 94010 Créteil CEDEX, France

³ Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8575, Japan

⁴ CNRS, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 94010 Créteil CEDEX, France

Appl. Sci. 2018, 8(4), 652; https://doi.org/10.3390/app8040652 - 23 Apr 2018

Cited by 21 | Viewed by 4549

Abstract

Quantitative ultrasound techniques for assessment of bone quality have been attracting significant research attention. The axial transmission technique, which involves analysis of ultrasonic guided waves propagating along cortical bone, has been proposed for assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect [...] Read more.

Quantitative ultrasound techniques for assessment of bone quality have been attracting significant research attention. The axial transmission technique, which involves analysis of ultrasonic guided waves propagating along cortical bone, has been proposed for assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect the elastic parameters of the medium, high-resolution estimation of the wavenumbers is required at each frequency with low computational cost. We use an adaptive array signal processing method and propose a technique that can be used to estimate the numbers of propagation modes that exist at each frequency without the need for time-consuming calculations. An experimental study of 4-mm-thick copper and bone-mimicking plates showed that the proposed method estimated the wavenumbers accurately with estimation errors of less than 4% and a calculation time of less than 0.5 s when using a laptop computer. Full article

(This article belongs to the Special Issue Ultrasonic Guided Waves)

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14 pages, 3459 KiB

Open AccessArticle

External Field Response and Applications of Metal Coated Hemispherical Janus Particles

by So Aizawa, Keisuke Seto and Eiji Tokunaga^*

Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan

Appl. Sci. 2018, 8(4), 653; https://doi.org/10.3390/app8040653 - 23 Apr 2018

Cited by 3 | Viewed by 5119

Abstract

Hemispherical Janus particles that were coated with silver or nickel on the equatorial plane of hemispherical polymer microparticles were prepared and dispersed in water and the responses to AC electric and stationary magnetic fields applied were investigated. Both of the particles are so [...] Read more.

Hemispherical Janus particles that were coated with silver or nickel on the equatorial plane of hemispherical polymer microparticles were prepared and dispersed in water and the responses to AC electric and stationary magnetic fields applied were investigated. Both of the particles are so oriented that the equatorial plane is parallel to the AC electric field, owing to electric-field induced dipole orientation, which is the response proportional to the quadratic electric field. The nickel coated particles are self-assembled to make a chain-like structure aligned in the direction of the stationary magnetic field. In addition, when both AC electric and stationary magnetic fields are applied, the orientation of a nickel-coated hemispherical particle is uniquely determined in such a way that the equatorial plane is parallel to both electric and magnetic fields. Because the particle is magnetized on the plane, its direction is reversed when the magnetic field is reversed, which is the response that is proportional to the magnetic field. Utilizing these features, mirrors are fabricated that can switch the transmittance and reflectance with electric and magnetic fields. Such features of the Janus particles as to be controlled by an electric and magnetic fields will find wide applications in the fields of microoptics and microfluidics. Full article

(This article belongs to the Section Optics and Lasers)

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Review

Jump to: Editorial, Research

23 pages, 9931 KiB

Open AccessFeature PaperReview

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

by Thanh-Tuân Bui^1,*

, Fabrice Goubard¹, Malika Ibrahim-Ouali², Didier Gigmes³ and Frédéric Dumur^3,*

¹ Laboratoire de Physicochimie des Polymères et des Interfaces (LPPI), Université de Cergy-Pontoise, 5 mail Gay Lussac, 95000 Neuville-sur-Oise, France

² Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, F-13397 Marseille, France

³ Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire ICR, UMR 7273, F-13397 Marseille, France

Appl. Sci. 2018, 8(4), 494; https://doi.org/10.3390/app8040494 - 26 Mar 2018

Cited by 53 | Viewed by 12953

Abstract

Organic light-emitting diodes offer attractive perspectives for the next generation display and lighting technologies. The potential is huge and the list of potential applications is almost endless. So far, blue emitters still suffer from noticeably inferior electroluminescence performances in terms of efficiency, lifespan, [...] Read more.

Organic light-emitting diodes offer attractive perspectives for the next generation display and lighting technologies. The potential is huge and the list of potential applications is almost endless. So far, blue emitters still suffer from noticeably inferior electroluminescence performances in terms of efficiency, lifespan, color quality, and charge injection/transport when compared to that of the other colors. Emitting materials matching the NTSC standard blue of coordinates (0.14, 0.08) are extremely rare and still constitutes the focus of numerous academic and industrial researches. In this context, we review herein the recent developments on highly emissive deep-blue thermally activated delayed fluorescence emitters that constitute the third-generation electroluminescent materials. Full article

(This article belongs to the Special Issue Fluorescence and Phosphorescence in Organic Materials: from Fundamental to OLED Devices)

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7 pages, 239 KiB

Open AccessReview

A Short Update on the Advantages, Applications and Limitations of Hyperspectral and Chemical Imaging in Food Authentication

by Jessica Roberts, Aoife Power

, James Chapman^†

, Shaneel Chandra

and Daniel Cozzolino^*

¹ Agri-Chemistry Group, School of Medical and Applied Sciences, Central Queensland University (CQU) Australia, Bruce Highway, North Rockhampton, QLD 4701, Australia

^† Current address: School of Science, RMIT University, Melbourne, Victoria, Australia.

Appl. Sci. 2018, 8(4), 505; https://doi.org/10.3390/app8040505 - 27 Mar 2018

Cited by 40 | Viewed by 5574

Abstract

Around the world, the food industry needs to maintain high quality and safety standards in order to satisfy consumers demand for healthy foods and to trace the origin of raw materials and products that are used during food manufacture. These objectives can be [...] Read more.

Around the world, the food industry needs to maintain high quality and safety standards in order to satisfy consumers demand for healthy foods and to trace the origin of raw materials and products that are used during food manufacture. These objectives can be achieved by applying analytical methods and techniques that are able to provide information about composition, structure, physicochemical properties, and sensory characteristics of foods. Modern techniques and methods based on spectroscopy (near infrared (NIR), mid infrared (MIR), Raman) are highly desirable due to their low cost and easy to implement, and often requiring minimal sample preparation. This paper reviews some of the advantages and recent applications of hyperspectral and chemical imaging to discriminate and authenticate foods. Full article

(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)

15 pages, 9422 KiB

Open AccessReview

Towards an ICT-Based Platform for Type 1 Diabetes Mellitus Management

by Ignacio Rodríguez-Rodríguez¹

, Miguel-Ángel Zamora-Izquierdo¹

and José-Víctor Rodríguez^2,*

¹ Dpto. de Ingeniería de la Información y las Comunicaciones, Universidad de Murcia, 30100 Murcia, Spain

² Dpto. de Tecnologías de la Información y las Comunicaciones, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain

Appl. Sci. 2018, 8(4), 511; https://doi.org/10.3390/app8040511 - 27 Mar 2018

Cited by 25 | Viewed by 6906

Abstract

Type 1 Diabetes Mellitus (DM1) is a metabolic disease that is characterized by chronic hyperglycemia due to a lack of pancreatic insulin production. This forces patients to perform several blood glucose measurements per day—by means of capillary glucometers—in order to infer a trend [...] Read more.

Type 1 Diabetes Mellitus (DM1) is a metabolic disease that is characterized by chronic hyperglycemia due to a lack of pancreatic insulin production. This forces patients to perform several blood glucose measurements per day—by means of capillary glucometers—in order to infer a trend and try to predict future values. In this way, a decision about the insulin dosage that has to be exogenously injected to maintain glycemia within the desirable levels is made. Unfortunately, this method usually suffers from relatively high imprecision. However, recent advances in information and communication technologies (ICT), along with novel biosensors that could provide a real-time comprehensive condition of the patient, offer a new perspective in DM1 management. In this sense, new disruptive technologies like Big Data, the Internet of Things (IoT), and Cloud Computing, as well as Machine Learning (ML) can play an important role in managing DM1. In this work, firstly, an analysis of previously published ICT-based methods for the management of diabetes continuous monitoring is carried out. In this way, an assessment of the possible lack of such proposals is presented, along with the challenges to be overcome in forthcoming smart DM1 management systems. Finally, an overview of a holistic ICT-based platform for DM1 management that try to solve the limitations of previous works, while at the same time, taking advantage of the abovementioned disruptive technologies is hereby proposed. Full article

(This article belongs to the Special Issue Advanced Internet of Things for Smart Infrastructure System)

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21 pages, 2421 KiB

Open AccessFeature PaperReview

Field Emission from Carbon Nanostructures

by Filippo Giubileo^1,*

, Antonio Di Bartolomeo^1,2

, Laura Iemmo^1,2, Giuseppe Luongo^1,2

and Francesca Urban^1,2

¹ CNR-SPIN Salerno, via Giovanni Paolo II, n. 132, 84084 Fisciano, Italy

² Dipartimento di Fisica “E.R. Caianiello”, Università di Salerno, via Giovanni Paolo II, n. 132, 84084 Fisciano, Italy

Appl. Sci. 2018, 8(4), 526; https://doi.org/10.3390/app8040526 - 29 Mar 2018

Cited by 165 | Viewed by 16852

Abstract

Field emission electron sources in vacuum electronics are largely considered to achieve faster response, higher efficiency and lower energy consumption in comparison with conventional thermionic emitters. Carbon nanotubes had a leading role in renewing attention to field emission technologies in the early 1990s, [...] Read more.

Field emission electron sources in vacuum electronics are largely considered to achieve faster response, higher efficiency and lower energy consumption in comparison with conventional thermionic emitters. Carbon nanotubes had a leading role in renewing attention to field emission technologies in the early 1990s, due to their exceptional electron emitting properties enabled by their large aspect ratio, high electrical conductivity, and thermal and chemical stability. In the last decade, the search for improved emitters has been extended to several carbon nanostructures, comprising carbon nanotubes, either individual or films, diamond structures, graphitic materials, graphene, etc. Here, we review the main results in the development of carbon-based field emitters. Full article

(This article belongs to the Special Issue Field Emission from Graphene and other Nanostructures)

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22 pages, 380 KiB

Open AccessFeature PaperReview

Attosecond-Resolved Electron Dynamics in Many-Electron Atoms: Quantitative Theory and Comparison with Measurements

by Cleanthes Anthony Nicolaides

Theoretical and Physical Chemistry Institute, National Hellenic Research, Foundation, 48 Vasileos Constantinou Avenue, 11635 Athens, Greece

Appl. Sci. 2018, 8(4), 533; https://doi.org/10.3390/app8040533 - 30 Mar 2018

Cited by 9 | Viewed by 4131

Abstract

A variety of processes originating from the interaction of atomic or molecular N-electron states with strong and/or hypershort radiation pulses can be understood quantitatively only by first determining with good accuracy the solutions of the many-electron time-dependent Schrödinger equation (METDSE) that describe the [...] Read more.

A variety of processes originating from the interaction of atomic or molecular N-electron states with strong and/or hypershort radiation pulses can be understood quantitatively only by first determining with good accuracy the solutions of the many-electron time-dependent Schrödinger equation (METDSE) that describe the corresponding physics. The METDSE is solvable nonperturbatively via the state-specific expansion approach (SSEA). SSEA solutions have been used, or can be used, for quantitative explanation and numerically reliable predictions of quantities that have been measured or are measurable in modern laser-driven experiments that can track, with hypershort (attosecond) time resolution, the effects of electron rearrangements in atoms and molecules. The calculations take into account in a transparent way the interplay between the phenomena and the electronic structures of the physically significant states in discrete and multichannel continuous spectra, including multiply- and inner-hole–excited resonance states. The discussion focuses on novel topics of time-resolved many-electron physics and includes a comparison of our predictions to recent quantitative measurements of attosecond-resolved generation of the profile of the

{(2 s 2 p)}^{1} P^{o}

doubly excited resonance state of helium during photoionization and of the relative time delay in photoemission of the (2s,2p) electrons of neon. Full article

(This article belongs to the Special Issue Extreme Time Scale Photonics)

19 pages, 24690 KiB

Open AccessReview

Three Flow Features behind the Flow Control Authority of DBD Plasma Actuator: Result of High-Fidelity Simulations and the Related Experiments

by Kozo Fujii

Department of Information and Computer Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan

Appl. Sci. 2018, 8(4), 546; https://doi.org/10.3390/app8040546 - 2 Apr 2018

Cited by 42 | Viewed by 8005

Abstract

Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge) plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an [...] Read more.

Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge) plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an airfoil and the mechanism of flow control of this small device is discussed. The DBD plasma actuator, especially in burst mode, is shown to be very effective for controlling flow separation at Reynolds number of 6.3 × 10⁴, when applied to the flows at an angle of attack higher than the stall. The analysis reveals that the flow structure includes three remarkable features that provide good authority for flow separation control with the appropriate actuator parameters. With proper setting of the actuator parameters to enhance the effective flow features for the application, good flow control can be achieved. Based on the analysis, guidelines for the effective use of DBD plasma actuators are proposed. A DBD plasma actuator is also applied to the flows under cruise conditions. With the DBD plasma actuator attached, a simple airfoil turns out to show higher lift-to-drag ratio than a well-designed airfoil. Full article

(This article belongs to the Special Issue Active Flow Control Technologies for Energy and Propulsive Systems)

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18 pages, 2991 KiB

Open AccessReview

Multifunctional Metasurfaces Based on the “Merging” Concept and Anisotropic Single-Structure Meta-Atoms

by Shiwei Tang^1,*

, Tong Cai^2,*, He-Xiu Xu^2,*, Qiong He^3,*, Shulin Sun^4,* and Lei Zhou^3,*

¹ Department of Physics, Faculty of Science, Ningbo University, Ningbo 315211, China

² Air and Missile Defend College, Air force Engineering University, Xi’an 710051, China

³ State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Collaborative Innovation Center of Advanced Microstructures, and Physics Department of Fudan University, Shanghai 200433, China

⁴ Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Green Photonics and Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China

Appl. Sci. 2018, 8(4), 555; https://doi.org/10.3390/app8040555 - 4 Apr 2018

Cited by 43 | Viewed by 9622

Abstract

Metasurfaces offer great opportunities to control electromagnetic (EM) waves, attracting intensive attention in science and engineering communities. Recently, many efforts were devoted to multifunctional metasurfaces integrating different functionalities into single flat devices. In this article, we present a concise review on the development [...] Read more.

Metasurfaces offer great opportunities to control electromagnetic (EM) waves, attracting intensive attention in science and engineering communities. Recently, many efforts were devoted to multifunctional metasurfaces integrating different functionalities into single flat devices. In this article, we present a concise review on the development of multifunctional metasurfaces, focusing on the design strategies proposed and functional devices realized. We first briefly review the early efforts on designing such systems, which simply combine multiple meta-structures with distinct functionalities to form multifunctional devices. To overcome the low-efficiency and functionality cross-talking issues, a new strategy was proposed, in which the meta-atoms are carefully designed single structures exhibiting polarization-controlled transmission/reflection amplitude/phase responses. Based on this new scheme, various types of multifunctional devices were realized in different frequency domains, which exhibit diversified functionalities (e.g., focusing, deflection, surface wave conversion, multi-beam emissions, etc.), for both pure-reflection and pure-transmission geometries or even in the full EM space. We conclude this review by presenting our perspectives on this fast-developing new sub-field, hoping to stimulate new research outputs that are useful in future applications. Full article

(This article belongs to the Special Issue Metasurfaces: Physics and Applications)

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29 pages, 9455 KiB

Open AccessFeature PaperReview

Probing Ferroic States in Oxide Thin Films Using Optical Second Harmonic Generation

by Johanna Nordlander

, Gabriele De Luca

, Nives Strkalj, Manfred Fiebig and Morgan Trassin^*

Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland

Appl. Sci. 2018, 8(4), 570; https://doi.org/10.3390/app8040570 - 6 Apr 2018

Cited by 55 | Viewed by 12432

Abstract

Forthcoming low-energy consumption oxide electronics rely on the deterministic control of ferroelectric and multiferroic domain states at the nanoscale. In this review, we address the recent progress in the field of investigation of ferroic order in thin films and heterostructures, with a focus [...] Read more.

Forthcoming low-energy consumption oxide electronics rely on the deterministic control of ferroelectric and multiferroic domain states at the nanoscale. In this review, we address the recent progress in the field of investigation of ferroic order in thin films and heterostructures, with a focus on non-invasive optical second harmonic generation (SHG). For more than 50 years, SHG has served as an established technique for probing ferroic order in bulk materials. Here, we will survey the specific new aspects introduced to SHG investigation of ferroelectrics and multiferroics by working with thin film structures. We show how SHG can probe complex ferroic domain patterns non-invasively and even if the lateral domain size is below the optical resolution limit or buried beneath an otherwise impenetrable cap layer. We emphasize the potential of SHG to distinguish contributions from individual (multi-) ferroic films or interfaces buried in a device or multilayer architecture. Special attention is given to monitoring switching events in buried ferroic domain- and domain-wall distributions by SHG, thus opening new avenues towards the determination of the domain dynamics. Another aspect studied by SHG is the role of strain. We will finally show that by integrating SHG into the ongoing thin film deposition process, we can monitor the emergence of ferroic order and properties in situ, while they emerge during growth. Our review closes with an outlook, emphasizing the present underrepresentation of ferroic switching dynamics in the study of ferroic oxide heterostructures. Full article

(This article belongs to the Section Materials Science and Engineering)

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18 pages, 23274 KiB

Open AccessReview

Matched-Filter Thermography

by Nima Tabatabaei

Department of Mechanical Engineering, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada

Appl. Sci. 2018, 8(4), 581; https://doi.org/10.3390/app8040581 - 8 Apr 2018

Cited by 24 | Viewed by 9921

Abstract

Conventional infrared thermography techniques, including pulsed and lock-in thermography, have shown great potential for non-destructive evaluation of broad spectrum of materials, spanning from metals to polymers to biological tissues. However, performance of these techniques is often limited due to the diffuse nature of [...] Read more.

Conventional infrared thermography techniques, including pulsed and lock-in thermography, have shown great potential for non-destructive evaluation of broad spectrum of materials, spanning from metals to polymers to biological tissues. However, performance of these techniques is often limited due to the diffuse nature of thermal wave fields, resulting in an inherent compromise between inspection depth and depth resolution. Recently, matched-filter thermography has been introduced as a means for overcoming this classic limitation to enable depth-resolved subsurface thermal imaging and improving axial/depth resolution. This paper reviews the basic principles and experimental results of matched-filter thermography: first, mathematical and signal processing concepts related to matched-fileting and pulse compression are discussed. Next, theoretical modeling of thermal-wave responses to matched-filter thermography using two categories of pulse compression techniques (linear frequency modulation and binary phase coding) are reviewed. Key experimental results from literature demonstrating the maintenance of axial resolution while inspecting deep into opaque and turbid media are also presented and discussed. Finally, the concept of thermal coherence tomography for deconvolution of thermal responses of axially superposed sources and creation of depth-selective images in a diffusion-wave field is reviewed. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Infrared Thermography)

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34 pages, 13102 KiB

Open AccessReview

A Review of Data Mining with Big Data towards Its Applications in the Electronics Industry

by Shengping Lv^1,2, Hoyeol Kim²

, Binbin Zheng¹ and Hong Jin^1,*

¹ College of Engineering, South China Agricultural University, Guangzhou 510642, China

² Department of Industrial, Manufacturing and Systems Engineering, Texas Tech University, Lubbock, TX 79409, USA

Appl. Sci. 2018, 8(4), 582; https://doi.org/10.3390/app8040582 - 8 Apr 2018

Cited by 38 | Viewed by 11578

Abstract

Data mining (DM) with Big Data has been widely used in the lifecycle of electronic products that range from the design and production stages to the service stage. A comprehensive analysis of DM with Big Data and a review of its application in [...] Read more.

Data mining (DM) with Big Data has been widely used in the lifecycle of electronic products that range from the design and production stages to the service stage. A comprehensive analysis of DM with Big Data and a review of its application in the stages of its lifecycle will not only benefit researchers to develop strong research themes and identify gaps in the field but also help practitioners for DM application system development. In this paper, a brief clarification of DM-related topics is presented first. A flowchart of DM and the main content of the flowchart steps are given in which commonly used data preparation and preprocessing approaches, DM functions and techniques, and performances indicators are summarized. Then, a comprehensive review covering 105 articles from 2007 to 2017 on DM or Big Data applications in the electronics industry is provided according to the flowchart from various points of view such as data handling, applications of DM, or Big Data at different lifecycle stages, and the software used in the applications. On this basis, a diagram of data content for different knowledge areas and a framework for DM and Big Data applications in the electronics industry are established. Finally, conclusions and future research directions are given. Full article

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30 pages, 11595 KiB

Open AccessReview

Preparation Techniques of TiO₂ Nanofluids and Challenges: A Review

by Hafiz Muhammad Ali^*, Hamza Babar

, Tayyab Raza Shah, Muhammad Usman Sajid

, Muhammad Arslan Qasim and Samina Javed

Mechanical Engineering Department, University of Engineering and Technology, Taxila 47050, Pakistan

Appl. Sci. 2018, 8(4), 587; https://doi.org/10.3390/app8040587 - 8 Apr 2018

Cited by 243 | Viewed by 17844

Abstract

Titanium dioxide (TiO₂) has been used extensively because of its unique thermal and electric properties. Different techniques have been used for the preparation of TiO₂ nanofluids which include single-step and two-step methods. In the natural world, TiO₂ exists in [...] Read more.

Titanium dioxide (TiO₂) has been used extensively because of its unique thermal and electric properties. Different techniques have been used for the preparation of TiO₂ nanofluids which include single-step and two-step methods. In the natural world, TiO₂ exists in three different crystalline forms as anatase, brookite, and rutile. Nanoparticles are not used directly in many heat transfer applications, and this provides a major challenge to researchers to advance towards stable nanofluid preparation methods. The primary step involved in the preparation of nanofluid is the production of nano-sized solid particles by using a suitable technique, and then these particles are dispersed into base fluids like oil, water, paraffin oil or ethylene glycol. However, nanofluid can also be prepared directly by using a liquid chemical method or vapor deposition technique (VDT). Nanofluids are mostly used in heat transfer applications and the size and cost of the heat transfer device depend upon the working fluid properties, thus, in the past decade scientists have made great efforts to formulate stable and cost-effective nanofluids with enhanced thermophysical properties. This review focuses on the different synthesis techniques and important physical properties (thermal conductivity and viscosity) that need to be considered very carefully during the preparation of TiO₂ nanofluids for desired applications. Full article

(This article belongs to the Special Issue Nanofluids and Their Applications)

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19 pages, 19855 KiB

Open AccessReview

High-Speed Visible Light Communications: Enabling Technologies and State of the Art

by Ruonan Ji^1,2,3

, Shaowei Wang^2,3,*

, Qingquan Liu^2,3,4 and Wei Lu^2,3

¹ Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710129, China

² State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China

³ Shanghai Engineering Research Center of Energy-Saving Coatings, Shanghai 200083, China

⁴ School of Physics and Technology, ShanghaiTech University, Shanghai 201210, China

Appl. Sci. 2018, 8(4), 589; https://doi.org/10.3390/app8040589 - 9 Apr 2018

Cited by 63 | Viewed by 12174

Abstract

In the nearest decades, the rapidly increasing demand of wireless connectivity has resulted in the ubiquitous deployment of wireless systems as well as heavily congested wireless spectrum. Owing to the various inherent advantages, such as spectral and bandwidth relief, no healthy concern, high [...] Read more.

In the nearest decades, the rapidly increasing demand of wireless connectivity has resulted in the ubiquitous deployment of wireless systems as well as heavily congested wireless spectrum. Owing to the various inherent advantages, such as spectral and bandwidth relief, no healthy concern, high security, low cost, and low interference with Radio Frequency (RF) waves, visible light communication (VLC) has been an emerging optical wireless data transmission approach that can act as a good complement to and substitute for Radio Frequency. How to achieve a high-speed data transmission is a key problem to be solved in the VLC system. This review mainly focuses on the enabling technologies for high-speed VLC systems, including novel transmitter architectures, blue filters and advanced modulation, and equalization technologies. And the inherent advantages, potential applications, and some issues of VLC that need further study are presented as well. Finally, a comprehensive survey on the recent developments and the key contributions by research groups involved in the field of high-speed VLC is provided. Full article

(This article belongs to the Special Issue Optical Wireless Communications)

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21 pages, 3216 KiB

Open AccessReview

Metasurface-Based Polarimeters

by Fei Ding^*, Yiting Chen^* and Sergey I. Bozhevolnyi

SDU Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark

Appl. Sci. 2018, 8(4), 594; https://doi.org/10.3390/app8040594 - 10 Apr 2018

Cited by 43 | Viewed by 9694

Abstract

The state of polarization (SOP) is an inherent property of light that can be used to gain crucial information about the composition and structure of materials interrogated with light. However, the SOP is difficult to experimentally determine since it involves phase information between [...] Read more.

The state of polarization (SOP) is an inherent property of light that can be used to gain crucial information about the composition and structure of materials interrogated with light. However, the SOP is difficult to experimentally determine since it involves phase information between orthogonal polarization states, and is uncorrelated with the light intensity and frequency, which can be easily determined with photodetectors and spectrometers. Rapid progress on optical gradient metasurfaces has resulted in the development of conceptually new approaches to the SOP characterization. In this paper, we review the fundamentals of and recent developments within metasurface-based polarimeters. Starting by introducing the concepts of generalized Snell’s law and Stokes parameters, we explain the Pancharatnam–Berry phase (PB-phase) which is instrumental for differentiating between orthogonal circular polarizations. Then we review the recent progress in metasurface-based polarimeters, including polarimeters, spectropolarimeters, orbital angular momentum (OAM) spectropolarimeters, and photodetector integrated polarimeters. The review is ended with a short conclusion and perspective for future developments. Full article

(This article belongs to the Special Issue Metasurfaces: Physics and Applications)

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20 pages, 12320 KiB

Open AccessReview

A Review of MEMS Scale Piezoelectric Energy Harvester

by Wenchao Tian, Zongyu Ling^*, Wenbo Yu

and Jing Shi

School of Electro-Mechanical Engineering, Xidian University, Number 2 Taibai South Road, Xi’an 710071, China

Appl. Sci. 2018, 8(4), 645; https://doi.org/10.3390/app8040645 - 20 Apr 2018

Cited by 82 | Viewed by 11332

Abstract

Piezoelectric energy harvester (PEH) is emerging as a novel device which can convert mechanical energy into electrical energy. It is mainly used to collect ambient vibration energy to power sensors, chips and some other small applications. This paper first introduces the working principle [...] Read more.

Piezoelectric energy harvester (PEH) is emerging as a novel device which can convert mechanical energy into electrical energy. It is mainly used to collect ambient vibration energy to power sensors, chips and some other small applications. This paper first introduces the working principle of PEH. Then, the paper elaborates the research progress of PEH from three aspects: piezoelectric materials, piezoelectric modes and energy harvester structures. Piezoelectric material is the core of the PEH. The piezoelectric and mechanical properties of piezoelectric material determine its application in energy harvesting. There are three piezoelectric modes, d₃₁, d₃₃ and d₁₅, the choice of which influences the maximum output voltage and power. Matching the external excitation frequency maximizes the conversion efficiency of the energy harvester. There are three approaches proposed in this paper to optimize the PEH’s structure and match the external excitation frequency, i.e., adjusting the resonant frequency, frequency up-converting and broadening the frequency bandwidth. In addition, harvesting maximum output power from the PEH requires impedance matching. Finally, this paper analyzes the above content and predicts PEH’s future development direction. Full article

(This article belongs to the Section Energy Science and Technology)

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