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Appl. Sci., Volume 8, Issue 4 (April 2018)

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Cover Story (view full-size image) The figure displays a schematic of a third generation (3G) artificial turf surface used for [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial Special Issue on “Sound and Music Computing”
Appl. Sci. 2018, 8(4), 518; doi:10.3390/app8040518
Received: 22 March 2018 / Revised: 27 March 2018 / Accepted: 27 March 2018 / Published: 28 March 2018
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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)
Open AccessEditorial Microgrids for Productive Uses of Energy in the Developing World and Blockchain: A Promising Future
Appl. Sci. 2018, 8(4), 580; doi:10.3390/app8040580
Received: 2 April 2018 / Revised: 4 April 2018 / Accepted: 4 April 2018 / Published: 8 April 2018
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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)
Open AccessEditorial Advanced Paving Materials and Technologies
Appl. Sci. 2018, 8(4), 588; doi:10.3390/app8040588
Received: 30 March 2018 / Revised: 1 April 2018 / Accepted: 2 April 2018 / Published: 9 April 2018
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(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)

Research

Jump to: Editorial, Review

Open AccessArticle Neuroprotective Investigation of Chitosan Nanoparticles for Dopamine Delivery
Appl. Sci. 2018, 8(4), 474; doi:10.3390/app8040474
Received: 19 February 2018 / Revised: 14 March 2018 / Accepted: 15 March 2018 / Published: 21 March 2018
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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
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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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Open AccessArticle Initial Results of Testing a Multilayer Laser Scanner in a Collision Avoidance System for Light Rail Vehicles
Appl. Sci. 2018, 8(4), 475; doi:10.3390/app8040475
Received: 20 February 2018 / Revised: 12 March 2018 / Accepted: 17 March 2018 / Published: 21 March 2018
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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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Open AccessFeature PaperArticle Biomass District Heating Systems Based on Agriculture Residues
Appl. Sci. 2018, 8(4), 476; doi:10.3390/app8040476
Received: 5 February 2018 / Revised: 14 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
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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
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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
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Open AccessArticle Accurate Models for Evaluating the Direct Conducted and Radiated Emissions from Integrated Circuits
Appl. Sci. 2018, 8(4), 477; doi:10.3390/app8040477
Received: 17 January 2018 / Revised: 1 March 2018 / Accepted: 20 March 2018 / Published: 21 March 2018
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Deep Activation Pooling for Blind Image Quality Assessment
Appl. Sci. 2018, 8(4), 478; doi:10.3390/app8040478
Received: 30 January 2018 / Revised: 15 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Seismic Response of a Three-Dimensional Asymmetric Multi-Storey Reinforced Concrete Structure
Appl. Sci. 2018, 8(4), 479; doi:10.3390/app8040479
Received: 28 January 2018 / Revised: 12 March 2018 / Accepted: 19 March 2018 / Published: 22 March 2018
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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
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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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Open AccessArticle Ca/Si and Si/Al Ratios of Metakaolinite-Based Wastes: Their Influence on Mineralogy and Mechanical Strengths
Appl. Sci. 2018, 8(4), 480; doi:10.3390/app8040480
Received: 12 February 2018 / Revised: 5 March 2018 / Accepted: 19 March 2018 / Published: 22 March 2018
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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)
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Open AccessArticle The Multiple-Update-Infill Sampling Method Using Minimum Energy Design for Sequential Surrogate Modeling
Appl. Sci. 2018, 8(4), 481; doi:10.3390/app8040481
Received: 30 January 2018 / Revised: 14 March 2018 / Accepted: 16 March 2018 / Published: 22 March 2018
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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,
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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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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
Appl. Sci. 2018, 8(4), 482; doi:10.3390/app8040482
Received: 13 February 2018 / Revised: 16 March 2018 / Accepted: 19 March 2018 / Published: 22 March 2018
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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
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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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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
Appl. Sci. 2018, 8(4), 483; doi:10.3390/app8040483
Received: 1 February 2018 / Revised: 23 February 2018 / Accepted: 25 February 2018 / Published: 23 March 2018
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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
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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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Open AccessArticle High-Performance Asymmetric Supercapacitors Based on the Surfactant/Ionic Liquid Complex Intercalated Reduced Graphene Oxide Composites
Appl. Sci. 2018, 8(4), 484; doi:10.3390/app8040484
Received: 24 January 2018 / Revised: 7 March 2018 / Accepted: 20 March 2018 / Published: 23 March 2018
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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.
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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
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Open AccessArticle Raman Imaging for the Detection of Adulterants in Paprika Powder: A Comparison of Data Analysis Methods
Appl. Sci. 2018, 8(4), 485; doi:10.3390/app8040485
Received: 12 February 2018 / Revised: 21 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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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
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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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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
Appl. Sci. 2018, 8(4), 486; doi:10.3390/app8040486
Received: 6 February 2018 / Revised: 9 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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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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Open AccessFeature PaperArticle Viscoelastic Behavior of Polymer-Modified Cement Pastes: Insight from Downscaling Short-Term Macroscopic Creep Tests by Means of Multiscale Modeling
Appl. Sci. 2018, 8(4), 487; doi:10.3390/app8040487
Received: 28 February 2018 / Revised: 16 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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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
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Open AccessArticle Modeling Restrained Shrinkage Induced Cracking in Concrete Rings Using the Thick Level Set Approach
Appl. Sci. 2018, 8(4), 488; doi:10.3390/app8040488
Received: 27 February 2018 / Revised: 19 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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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
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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
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Open AccessFeature PaperArticle Computational Accountability in MAS Organizations with ADOPT
Appl. Sci. 2018, 8(4), 489; doi:10.3390/app8040489
Received: 28 February 2018 / Revised: 14 March 2018 / Accepted: 20 March 2018 / Published: 23 March 2018
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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
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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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Open AccessArticle Numerical Studies on the Action Mechanism of Combustion Intermediates and Free Radicals on Nitrogen Oxides under Oil-Water Blended Conditions
Appl. Sci. 2018, 8(4), 490; doi:10.3390/app8040490
Received: 5 March 2018 / Revised: 18 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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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
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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 Chemistry)
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Open AccessArticle Design and Analysis of a Floor Radiant Heating System Based on Energy Substitution Technology
Appl. Sci. 2018, 8(4), 491; doi:10.3390/app8040491
Received: 14 February 2018 / Revised: 23 March 2018 / Accepted: 23 March 2018 / Published: 25 March 2018
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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
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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)
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Open AccessArticle Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles
Appl. Sci. 2018, 8(4), 492; doi:10.3390/app8040492
Received: 14 February 2018 / Revised: 23 March 2018 / Accepted: 23 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle A Bayesian Network Based Adaptability Design of Product Structures for Function Evolution
Appl. Sci. 2018, 8(4), 493; doi:10.3390/app8040493
Received: 5 February 2018 / Revised: 19 March 2018 / Accepted: 22 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle An Ensemble Based Evolutionary Approach to the Class Imbalance Problem with Applications in CBIR
Appl. Sci. 2018, 8(4), 495; doi:10.3390/app8040495
Received: 12 February 2018 / Revised: 16 March 2018 / Accepted: 19 March 2018 / Published: 26 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Novel Automatic Idle Speed Control System with Hydraulic Accumulator and Control Strategy for Construction Machinery
Appl. Sci. 2018, 8(4), 496; doi:10.3390/app8040496
Received: 23 January 2018 / Revised: 6 March 2018 / Accepted: 19 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle Electromagnetic Power Harvester Using Wide-Angle and Polarization-Insensitive Metasurfaces
Appl. Sci. 2018, 8(4), 497; doi:10.3390/app8040497
Received: 16 February 2018 / Revised: 21 March 2018 / Accepted: 22 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle Rock Fragmentation Characteristics by TBM Cutting and Efficiency under Bi-Lateral Confinement
Appl. Sci. 2018, 8(4), 498; doi:10.3390/app8040498
Received: 12 February 2018 / Revised: 13 March 2018 / Accepted: 13 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle Assist-as-Needed Control of a Robotic Orthosis Actuated by Pneumatic Artificial Muscle for Gait Rehabilitation
Appl. Sci. 2018, 8(4), 499; doi:10.3390/app8040499
Received: 26 February 2018 / Revised: 23 March 2018 / Accepted: 23 March 2018 / Published: 26 March 2018
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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
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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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Open AccessArticle A Semantic Segmentation Algorithm Using FCN with Combination of BSLIC
Appl. Sci. 2018, 8(4), 500; doi:10.3390/app8040500
Received: 12 February 2018 / Revised: 17 March 2018 / Accepted: 23 March 2018 / Published: 26 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle Mechanical Characterisation and Modelling of Elastomeric Shockpads
Appl. Sci. 2018, 8(4), 501; doi:10.3390/app8040501
Received: 30 January 2018 / Revised: 19 March 2018 / Accepted: 20 March 2018 / Published: 27 March 2018
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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
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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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Open AccessArticle A New Wind Turbine Generating System Model for Balanced and Unbalanced Distribution Systems Load Flow Analysis
Appl. Sci. 2018, 8(4), 502; doi:10.3390/app8040502
Received: 7 February 2018 / Revised: 17 March 2018 / Accepted: 21 March 2018 / Published: 27 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Stability of Two-Dimensional Polymorphs for 10,12-Pentacosadyn-1-ol on Graphite Investigated by SPM
Appl. Sci. 2018, 8(4), 503; doi:10.3390/app8040503
Received: 16 February 2018 / Revised: 21 March 2018 / Accepted: 23 March 2018 / Published: 27 March 2018
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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.
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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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Open AccessArticle An FPGA Implementation of a Convolutional Auto-Encoder
Appl. Sci. 2018, 8(4), 504; doi:10.3390/app8040504
Received: 24 February 2018 / Revised: 16 March 2018 / Accepted: 20 March 2018 / Published: 27 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Multi-Objective and Multi-Rate Control of the Grinding and Classification Circuit with Electromagnetic Mill
Appl. Sci. 2018, 8(4), 506; doi:10.3390/app8040506
Received: 16 January 2018 / Revised: 22 February 2018 / Accepted: 22 March 2018 / Published: 27 March 2018
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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
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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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Open AccessArticle Assessment of Student Music Performances Using Deep Neural Networks
Appl. Sci. 2018, 8(4), 507; doi:10.3390/app8040507
Received: 28 February 2018 / Revised: 19 March 2018 / Accepted: 22 March 2018 / Published: 27 March 2018
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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
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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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Open AccessArticle Internet of Things for Sensing: A Case Study in the Healthcare System
Appl. Sci. 2018, 8(4), 508; doi:10.3390/app8040508
Received: 1 December 2017 / Revised: 10 March 2018 / Accepted: 19 March 2018 / Published: 27 March 2018
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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
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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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Open AccessArticle Sequencing Batch Reactor and Bacterial Community in Aerobic Granular Sludge for Wastewater Treatment of Noodle-Manufacturing Sector
Appl. Sci. 2018, 8(4), 509; doi:10.3390/app8040509
Received: 1 March 2018 / Revised: 24 March 2018 / Accepted: 26 March 2018 / Published: 27 March 2018
PDF Full-text (4389 KB) | HTML Full-text | XML Full-text | Supplementary Files
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
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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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Open AccessArticle Thermally Bonded PET–Basalt Sandwich Composites for Heat Pipeline Protection: Preparation, Stab Resisting, and Thermal-Insulating Properties
Appl. Sci. 2018, 8(4), 510; doi:10.3390/app8040510
Received: 6 February 2018 / Revised: 20 March 2018 / Accepted: 26 March 2018 / Published: 27 March 2018
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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
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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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Open AccessArticle Silicone-Based Molding Technique for Optical Flow Analysis in Transparent Models of Fluidic Components
Appl. Sci. 2018, 8(4), 512; doi:10.3390/app8040512
Received: 19 January 2018 / Revised: 8 March 2018 / Accepted: 26 March 2018 / Published: 27 March 2018
PDF Full-text (2486 KB) | HTML Full-text | XML Full-text
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
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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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Open AccessArticle Growth Identification of Aspergillus flavus and Aspergillus parasiticus by Visible/Near-Infrared Hyperspectral Imaging
Appl. Sci. 2018, 8(4), 513; doi:10.3390/app8040513
Received: 8 February 2018 / Revised: 28 February 2018 / Accepted: 12 March 2018 / Published: 28 March 2018
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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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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
Appl. Sci. 2018, 8(4), 514; doi:10.3390/app8040514
Received: 23 February 2018 / Revised: 24 March 2018 / Accepted: 25 March 2018 / Published: 28 March 2018
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Abstract
This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m Dt 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
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This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m Dt 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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Open AccessArticle Defeat Your Enemy Hiding behind Public WiFi: WiGuard Can Protect Your Sensitive Information from CSI-Based Attack
Appl. Sci. 2018, 8(4), 515; doi:10.3390/app8040515
Received: 27 February 2018 / Revised: 19 March 2018 / Accepted: 23 March 2018 / Published: 28 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A User-Centered Mobile Cloud Computing Platform for Improving Knowledge Management in Small-to-Medium Enterprises in the Chilean Construction Industry
Appl. Sci. 2018, 8(4), 516; doi:10.3390/app8040516
Received: 9 February 2018 / Revised: 20 March 2018 / Accepted: 27 March 2018 / Published: 28 March 2018
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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
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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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Open AccessArticle A Body-Nonlinear Green’s Function Method with Viscous Dissipation Effects for Large-Amplitude Roll of Floating Bodies
Appl. Sci. 2018, 8(4), 517; doi:10.3390/app8040517
Received: 26 February 2018 / Revised: 22 March 2018 / Accepted: 24 March 2018 / Published: 28 March 2018
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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
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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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Open AccessArticle Aerodynamic Analysis and Noise-Reducing Design of an Outside Rear View Mirror
Appl. Sci. 2018, 8(4), 519; doi:10.3390/app8040519
Received: 18 February 2018 / Revised: 16 March 2018 / Accepted: 23 March 2018 / Published: 29 March 2018
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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)
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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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Open AccessArticle The Influence of Forming Directions and Strain Rate on Dynamic Shear Properties of Aerial Aluminum Alloy
Appl. Sci. 2018, 8(4), 520; doi:10.3390/app8040520
Received: 14 March 2018 / Revised: 26 March 2018 / Accepted: 26 March 2018 / Published: 29 March 2018
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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
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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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Open AccessArticle Ni-Al Alloys as Alternative EUV Mask Absorber
Appl. Sci. 2018, 8(4), 521; doi:10.3390/app8040521
Received: 31 January 2018 / Revised: 23 March 2018 / Accepted: 25 March 2018 / Published: 29 March 2018
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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
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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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Open AccessArticle Damage Imaging in Lamb Wave-Based Inspection of Adhesive Joints
Appl. Sci. 2018, 8(4), 522; doi:10.3390/app8040522
Received: 5 February 2018 / Revised: 15 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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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
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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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Open AccessArticle Selection of Spectral Resolution and Scanning Speed for Detecting Green Jujubes Chilling Injury Based on Hyperspectral Reflectance Imaging
Appl. Sci. 2018, 8(4), 523; doi:10.3390/app8040523
Received: 13 March 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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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
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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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Open AccessArticle Acceleration Harmonic Estimation for Hydraulic Servo Shaking Table by Using Simulated Annealing Algorithm
Appl. Sci. 2018, 8(4), 524; doi:10.3390/app8040524
Received: 15 March 2018 / Revised: 22 March 2018 / Accepted: 28 March 2018 / Published: 29 March 2018
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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
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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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Open AccessArticle Probabilistic Sensitivity Amplification Control for Lower Extremity Exoskeleton
Appl. Sci. 2018, 8(4), 525; doi:10.3390/app8040525
Received: 27 January 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle A Topological View on Optical and Phononic Fabry–Perot Microcavities through the Su–Schrieffer–Heeger Model
Appl. Sci. 2018, 8(4), 527; doi:10.3390/app8040527
Received: 9 March 2018 / Revised: 22 March 2018 / Accepted: 26 March 2018 / Published: 30 March 2018
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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
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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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Open AccessArticle Chemical and Molecular Variations in Commercial Epoxide Photoresists for X-ray Lithography
Appl. Sci. 2018, 8(4), 528; doi:10.3390/app8040528
Received: 18 December 2017 / Revised: 1 March 2018 / Accepted: 28 March 2018 / Published: 30 March 2018
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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
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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 Chemistry)
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Open AccessArticle Three-Dimensional Electromagnetic Mixing Models for Dual-Phase Steel Microstructures
Appl. Sci. 2018, 8(4), 529; doi:10.3390/app8040529
Received: 28 February 2018 / Revised: 15 March 2018 / Accepted: 29 March 2018 / Published: 30 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Collaborative Multiplicative Holt-Winters Forecasting Approach with Dynamic Fuzzy-Level Component
Appl. Sci. 2018, 8(4), 530; doi:10.3390/app8040530
Received: 24 February 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 30 March 2018
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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
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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 (LT), growth rate (bT) and seasonal component (SNT). The current practice of integrating and/or determining the initial value of LT 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 LT is avoided, presumably due to the computational complexity. To overcome this obstacle, a fuzzy logic-based prediction model is developed to evaluate LT 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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Open AccessArticle Reverberation-Ray Matrix Analysis and Interpretation of Bending Waves in Bi-Coupled Periodic Multi-Component Beams
Appl. Sci. 2018, 8(4), 531; doi:10.3390/app8040531
Received: 15 January 2018 / Revised: 22 March 2018 / Accepted: 28 March 2018 / Published: 30 March 2018
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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
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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)
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Open AccessArticle Research on Distributed PV Storage Virtual Synchronous Generator System and Its Static Frequency Characteristic Analysis
Appl. Sci. 2018, 8(4), 532; doi:10.3390/app8040532
Received: 11 February 2018 / Revised: 22 March 2018 / Accepted: 23 March 2018 / Published: 30 March 2018
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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
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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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Open AccessArticle Battery Management System Hardware Concepts: An Overview
Appl. Sci. 2018, 8(4), 534; doi:10.3390/app8040534
Received: 6 February 2018 / Revised: 15 March 2018 / Accepted: 22 March 2018 / Published: 30 March 2018
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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
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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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Open AccessArticle A Thermodynamic Analysis of the Pressure Gain of Continuously Rotating Detonation Combustor for Gas Turbine
Appl. Sci. 2018, 8(4), 535; doi:10.3390/app8040535
Received: 4 February 2018 / Revised: 15 March 2018 / Accepted: 28 March 2018 / Published: 30 March 2018
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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.
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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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Open AccessFeature PaperArticle Evaluation of the Toxin-to-Protein Binding Rates during Hemodialysis Using Sorbent-Loaded Mixed-Matrix Membranes
Appl. Sci. 2018, 8(4), 536; doi:10.3390/app8040536
Received: 1 March 2018 / Revised: 27 March 2018 / Accepted: 28 March 2018 / Published: 31 March 2018
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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
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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
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Open AccessArticle A Novel Method for Modeling the Electromagnetic Characteristics of Switched Reluctance Motors
Appl. Sci. 2018, 8(4), 537; doi:10.3390/app8040537
Received: 4 February 2018 / Revised: 17 March 2018 / Accepted: 29 March 2018 / Published: 31 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Hybrid Metaheuristic for Multi-Objective Scientific Workflow Scheduling in a Cloud Environment
Appl. Sci. 2018, 8(4), 538; doi:10.3390/app8040538
Received: 27 February 2018 / Revised: 22 March 2018 / Accepted: 28 March 2018 / Published: 31 March 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle Organic Light-Emitting Diodes Based on Phthalimide Derivatives: Improvement of the Electroluminescence Properties
Appl. Sci. 2018, 8(4), 539; doi:10.3390/app8040539 (registering DOI)
Received: 4 March 2018 / Revised: 28 March 2018 / Accepted: 29 March 2018 / Published: 31 March 2018
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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%
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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
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Open AccessArticle Effects of Thermal Frequency on Microstructures, Mechanical and Corrosion Properties of AA6061 Joints
Appl. Sci. 2018, 8(4), 540; doi:10.3390/app8040540
Received: 9 March 2018 / Revised: 24 March 2018 / Accepted: 27 March 2018 / Published: 2 April 2018
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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
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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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Open AccessArticle Project Robust Scheduling Based on the Scattered Buffer Technology
Appl. Sci. 2018, 8(4), 541; doi:10.3390/app8040541
Received: 12 February 2018 / Revised: 21 March 2018 / Accepted: 29 March 2018 / Published: 2 April 2018
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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
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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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Open AccessArticle An Iterative Load Disaggregation Approach Based on Appliance Consumption Pattern
Appl. Sci. 2018, 8(4), 542; doi:10.3390/app8040542
Received: 23 February 2018 / Revised: 26 March 2018 / Accepted: 29 March 2018 / Published: 2 April 2018
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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
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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)
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Open AccessFeature PaperArticle Octave Spanning Supercontinuum in Titanium Dioxide Waveguides
Appl. Sci. 2018, 8(4), 543; doi:10.3390/app8040543
Received: 13 February 2018 / Revised: 22 March 2018 / Accepted: 28 March 2018 / Published: 2 April 2018
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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
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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
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Open AccessArticle Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions
Appl. Sci. 2018, 8(4), 544; doi:10.3390/app8040544
Received: 28 January 2018 / Revised: 26 March 2018 / Accepted: 28 March 2018 / Published: 2 April 2018
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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
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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)
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Open AccessArticle A CFD Results-Based Approach to Investigating Acoustic Attenuation Performance and Pressure Loss of Car Perforated Tube Silencers
Appl. Sci. 2018, 8(4), 545; doi:10.3390/app8040545
Received: 1 March 2018 / Revised: 27 March 2018 / Accepted: 29 March 2018 / Published: 2 April 2018
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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
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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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Open AccessArticle Adaptive Trajectory Tracking Control for Underactuated Unmanned Surface Vehicle Subject to Unknown Dynamics and Time-Varing Disturbances
Appl. Sci. 2018, 8(4), 547; doi:10.3390/app8040547
Received: 6 March 2018 / Revised: 31 March 2018 / Accepted: 2 April 2018 / Published: 2 April 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Self-Recovery Fragile Image Watermarking with Variable Watermark Capacity
Appl. Sci. 2018, 8(4), 548; doi:10.3390/app8040548
Received: 14 February 2018 / Revised: 27 March 2018 / Accepted: 29 March 2018 / Published: 2 April 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Prediction of the Tensile Load of Drilled CFRP by Artificial Neural Network
Appl. Sci. 2018, 8(4), 549; doi:10.3390/app8040549
Received: 2 March 2018 / Revised: 27 March 2018 / Accepted: 27 March 2018 / Published: 2 April 2018
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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
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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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Open AccessArticle A High-Performance Implementation of an IoT System Using DPDK
Appl. Sci. 2018, 8(4), 550; doi:10.3390/app8040550
Received: 24 February 2018 / Revised: 28 March 2018 / Accepted: 1 April 2018 / Published: 2 April 2018
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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
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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
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Optimal Piezoelectric Potential Distribution for Controlling Multimode Vibrations
Appl. Sci. 2018, 8(4), 551; doi:10.3390/app8040551
Received: 15 March 2018 / Revised: 29 March 2018 / Accepted: 30 March 2018 / Published: 3 April 2018
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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
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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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Open AccessArticle Pigment Dyeing of Atmospheric Pressure Plasma-Treated Cotton Fabric
Appl. Sci. 2018, 8(4), 552; doi:10.3390/app8040552
Received: 28 February 2018 / Revised: 21 March 2018 / Accepted: 26 March 2018 / Published: 3 April 2018
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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
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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 Chemistry)
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Open AccessArticle Experimental Study of Damage Development in Salt Rock under Uniaxial Stress Using Ultrasonic Velocity and Acoustic Emissions
Appl. Sci. 2018, 8(4), 553; doi:10.3390/app8040553
Received: 21 February 2018 / Revised: 19 March 2018 / Accepted: 27 March 2018 / Published: 4 April 2018
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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
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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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