Applied Sciences

Editorial

Jump to: Research, Review

5 pages, 161 KiB

Open AccessEditorial

Advances in Vibroacoustics and Aeroacustics of Aerospace and Automotive Systems

by Roberto Citarella^1,*

and Luigi Federico²

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

² Italian Aerospace Research Centre (C.I.R.A), via Maiorise snc, 81043 Capua, Italy

Appl. Sci. 2018, 8(3), 366; https://doi.org/10.3390/app8030366 - 3 Mar 2018

Cited by 21 | Viewed by 3441

Abstract

n/a Full article

(This article belongs to the Special Issue Advances in Vibroacoustics and Aeroacustics of Aerospace and Automotive Systems)

3 pages, 155 KiB

Open AccessEditorial

Special Issue on Solid State Lasers Materials, Technologies and Applications

by Federico Pirzio

Dipartimento di Ingegneria Industriale e dell’Informazione, Università di Pavia, Via Ferrata 5, 27100 Pavia, Italy

Appl. Sci. 2018, 8(3), 460; https://doi.org/10.3390/app8030460 - 17 Mar 2018

Cited by 1 | Viewed by 3233

Abstract

Even though more than half a century has already passed since the first demonstration of laser action in ruby crystal, solid-state lasers are still a hot research topic.[...] Full article

(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)

Research

Jump to: Editorial, Review

16 pages, 5443 KiB

Open AccessFeature PaperArticle

Quasi-Static Elastography and Ultrasound Plane-Wave Imaging: The Effect of Beam-Forming Strategies on the Accuracy of Displacement Estimations

by Gijs A.G.M. Hendriks^1,*

, Chuan Chen¹, Hendrik H.G. Hansen¹

and Chris L. De Korte^1,2

¹ Medical UltraSound Imaging Center, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands

² Physics of Fluids Group, MIRA, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

Appl. Sci. 2018, 8(3), 319; https://doi.org/10.3390/app8030319 - 26 Feb 2018

Cited by 12 | Viewed by 5061

Abstract

Quasi-static elastography is an ultrasound method which is widely used to assess displacements and strain in tissue by correlating ultrasound data at different levels of deformation. Ultrafast plane-wave imaging allows us to obtain ultrasound data at frame rates over 10 kHz, permitting the [...] Read more.

Quasi-static elastography is an ultrasound method which is widely used to assess displacements and strain in tissue by correlating ultrasound data at different levels of deformation. Ultrafast plane-wave imaging allows us to obtain ultrasound data at frame rates over 10 kHz, permitting the quantification and visualization of fast deformations. Currently, mainly three beam-forming strategies are used to reconstruct radio frequency (RF) data from plane-wave acquisitions: delay-and-sum (DaS), and Lu’s-fk and Stolt’s-fk operating in the temporal-spatial and Fourier spaces, respectively. However, the effect of these strategies on elastography is unknown. This study investigates the effect of these beam-forming strategies on the accuracy of displacement estimation in four transducers (L7-4, 12L4VF, L12-5, MS250) for various reconstruction line densities and apodization/filtering settings. A method was developed to assess the accuracy experimentally using displacement gradients obtained in a rotating phantom. A line density with multiple lines per pitch resulted in increased accuracy compared to one line per pitch for all transducers and strategies. The impact on displacement accuracy of apodization/filtering varied per transducer. Overall, Lu’s-fk beam-forming resulted in the most accurate displacement estimates. Although DaS in some cases provided similar results, Lu’s-fk is more computationally efficient, leading to the conclusion that Lu’s-fk is most optimal for plane wave ultrasound-based elastography. Full article

(This article belongs to the Special Issue Ultrafast Ultrasound Imaging)

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13 pages, 11515 KiB

Open AccessArticle

Failure Monitoring and Condition Assessment of Steel-Concrete Adhesive Connection Using Ultrasonic Waves

by Magdalena Rucka

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

Appl. Sci. 2018, 8(3), 320; https://doi.org/10.3390/app8030320 - 26 Feb 2018

Cited by 19 | Viewed by 4117

Abstract

Adhesive bonding is increasingly being incorporated into civil engineering applications. Recently, the use of structural adhesives in steel-concrete composite systems is of particular interest. The aim of the study is an experimental investigation of the damage assessment of the connection between steel and [...] Read more.

Adhesive bonding is increasingly being incorporated into civil engineering applications. Recently, the use of structural adhesives in steel-concrete composite systems is of particular interest. The aim of the study is an experimental investigation of the damage assessment of the connection between steel and concrete during mechanical degradation. Nine specimens consisted of a concrete cube and two adhesively bonded steel plates were examined. The inspection was based on the ultrasound monitoring during push-out tests. Ultrasonic waves were excited and registered by means of piezoelectric transducers every two seconds until the specimen failure. To determine the slip between the steel and concrete a photogrammetric method was applied. The procedure of damage evaluation is based on the monitoring of the changes in the amplitude and phase shift of signals measured during subsequent phases of degradation. To quantify discrepancies between the reference signal and other registered signals, the Sprague and Gears metric was applied. The results showed the possibilities and limitations of the proposed approach in diagnostics of adhesive connections between steel and concrete depending on the failure modes. Full article

(This article belongs to the Section Acoustics and Vibrations)

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11 pages, 2428 KiB

Open AccessFeature PaperArticle

Characteristic Analysis of Compact Spectrometer Based on Off-Axis Meta-Lens

by Yi Zhou, Rui Chen and Yungui Ma^*

Centre for Optical and Electromagnetic Research, State Key Lab of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058, China

Appl. Sci. 2018, 8(3), 321; https://doi.org/10.3390/app8030321 - 26 Feb 2018

Cited by 23 | Viewed by 6313

Abstract

Ultra-compact spectrometers with high-resolution and/or broadband features have long been pursued for their wide application prospects. The off-axis meta-lens, a new species of planar optical instruments, provides a unique and feasible way to realize these goals. Here we give a detailed investigation of [...] Read more.

Ultra-compact spectrometers with high-resolution and/or broadband features have long been pursued for their wide application prospects. The off-axis meta-lens, a new species of planar optical instruments, provides a unique and feasible way to realize these goals. Here we give a detailed investigation of the influences of structural parameters of meta-lens-based spectrometers on the effective spectral range and the spectral resolution using both wave optics and geometrical optics methods. Aimed for different usages, two types of meta-lens based spectrometers are numerically proposed: one is a wideband spectrometer working at 800–1800 nm wavelengths with the spectral resolution of 2–5 nm and the other is a narrowband one working at the 780–920 nm band but with a much higher spectral resolution of 0.15–0.6 nm. The tolerance for fabrication errors is also discussed in the end. These provides a prominent way to design and integrate planar film-based spectrometers for various instrumental applications. Full article

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

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13 pages, 396 KiB

Open AccessArticle

Attosecond Time Delay in Photoionization of Noble-Gas and Halogen Atoms

by Liang-Wen Pi^*

and Alexandra S. Landsman

Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, D-01187 Dresden, Germany

Appl. Sci. 2018, 8(3), 322; https://doi.org/10.3390/app8030322 - 26 Feb 2018

Cited by 14 | Viewed by 5015

Abstract

Ultrafast processes are now accessible on the attosecond time scale due to the availability of ultrashort XUV laser pulses. Noble-gas and halogen atoms remain important targets due to their giant dipole resonance and Cooper minimum. Here, we calculate photoionization cross section, asymmetry parameter [...] Read more.

Ultrafast processes are now accessible on the attosecond time scale due to the availability of ultrashort XUV laser pulses. Noble-gas and halogen atoms remain important targets due to their giant dipole resonance and Cooper minimum. Here, we calculate photoionization cross section, asymmetry parameter and Wigner time delay using the time-dependent local-density approximation (TDLDA), which includes the electron correlation effects. Our results are consistent with experimental data and other theoretical calculations. The asymmetry parameter provides an extra layer of access to the phase information of the photoionization processes. We find that halogen atoms bear a strong resemblance on cross section, asymmetry parameter and time delay to their noble-gas neighbors. Our predicted time delay should provide a guidance for future experiments on those atoms and related molecules. Full article

(This article belongs to the Special Issue Extreme Time Scale Photonics)

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19 pages, 1610 KiB

Open AccessArticle

Applicability of Emotion Recognition and Induction Methods to Study the Behavior of Programmers

by Michal R. Wrobel

Department of Software Engineering, Faculty Of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 80-233 Gdańsk, Poland

Appl. Sci. 2018, 8(3), 323; https://doi.org/10.3390/app8030323 - 26 Feb 2018

Cited by 18 | Viewed by 5295

Abstract

Recent studies in the field of software engineering have shown that positive emotions can increase and negative emotions decrease the productivity of programmers. In the field of affective computing, many methods and tools to recognize the emotions of computer users were proposed. However, [...] Read more.

Recent studies in the field of software engineering have shown that positive emotions can increase and negative emotions decrease the productivity of programmers. In the field of affective computing, many methods and tools to recognize the emotions of computer users were proposed. However, it has not been verified yet which of them can be used to monitor the emotional states of software developers. The paper describes a study carried out on a group of 35 participants to determine which of these methods can be used during programming. During the study, data from multiple sensors that are commonly used in methods of emotional recognition were collected. The participants were extensively questioned about the sensors’ invasiveness during programming. This allowed us to determine which of them are applicable in the work of programmers. In addition, it was verified which methods are suitable for use in the work environment and which are only suitable in the laboratory. Moreover, three methods for inducing negative emotions have been proposed, and their effectiveness has been verified. Full article

(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)

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11 pages, 1042 KiB

Open AccessArticle

Improvement of RF Wireless Power Transmission Using a Circularly Polarized Retrodirective Antenna Array with EBG Structures

by Son Trinh-Van, Jong Min Lee, Youngoo Yang, Kang-Yoon Lee and Keum Cheol Hwang^*

School of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 440-746, Korea

Appl. Sci. 2018, 8(3), 324; https://doi.org/10.3390/app8030324 - 26 Feb 2018

Cited by 12 | Viewed by 8291

Abstract

This paper presents the performance improvement of a circularly polarized (CP) retrodirective array (RDA) through the suppression of mutual coupling effects. The RDA is designed based on CP Koch-shaped patch antenna elements with an inter-element spacing as small as 0.4

λ

for a [...] Read more.

This paper presents the performance improvement of a circularly polarized (CP) retrodirective array (RDA) through the suppression of mutual coupling effects. The RDA is designed based on CP Koch-shaped patch antenna elements with an inter-element spacing as small as 0.4

λ

for a compact size (

λ

is the wavelength in free space at the designed frequency of 5.2 GHz). Electromagnetic band gap (EBG) structures are applied to reduce the mutual coupling between the antenna elements, thus improving the circular polarization characteristic of the RDA. Two CP RDAs with EBGs, in the case 5 × 5 and 10 × 10 arrays, are used as wireless power transmitters to transmit a total power of 50 W. A receiver is located at a distance of 1 m away from the transmitter to harvest the transmitted power. At the broadside direction, the simulated results demonstrate that the received powers are improved by approximately 11.32% and 12.45% when using the 5 × 5 and 10 × 10 CP RDAs with the EBGs, respectively, as the transmitters. Full article

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17 pages, 7448 KiB

Open AccessArticle

Flexural Performance of Transparent Plastic Bar Reinforced Concrete

by Byoungil Kim^1,*

and Yoon-Jung Han²

¹ School of Architecture, Seoul National University of Science & Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea

² Institute of Construction Technology, Seoul National University of Science & Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea

Appl. Sci. 2018, 8(3), 325; https://doi.org/10.3390/app8030325 - 26 Feb 2018

Cited by 7 | Viewed by 4816

Abstract

In this study, experiments were conducted to derive a mix design for improving the flexural performance of light transparent concrete, which is attracting much attention and interest as an interior and exterior material for buildings, so that it could be easily applied in [...] Read more.

In this study, experiments were conducted to derive a mix design for improving the flexural performance of light transparent concrete, which is attracting much attention and interest as an interior and exterior material for buildings, so that it could be easily applied in the field as a non-structural element by securing a lightweight, workability, and economic efficiency through the improvement of the concrete mix design and the use of economical materials for promoting its practical use. It was found that the mixing of polyvinyl alcohol (PVA) fiber was effective in improving the consistency by preventing the aggregate from floating due to the mixing of lightweight aggregate with a low specific gravity. The flexural performance test results showed that the load transfer factor (LTF) from the concrete matrix to the fiber was highest in the test specimens without plastic bars, followed by those with 5 and 10 mm plastic bars, respectively. Full article

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

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10 pages, 853 KiB

Open AccessFeature PaperArticle

Capacity Enhancement of Few-Mode Fiber Transmission Systems Impaired by Mode-Dependent Loss

by El-Mehdi Amhoud^*, Ghaya Rekaya-Ben Othman and Yves Jaouën

LTCI, Télécom ParisTech, 46 Rue Barrault, 75013 Paris, France

Appl. Sci. 2018, 8(3), 326; https://doi.org/10.3390/app8030326 - 26 Feb 2018

Cited by 5 | Viewed by 3494

Abstract

Space-division multiplexing over few-mode fibers is a promising solution to increase the capacity of the future generation of optical transmission systems. Mode-dependent loss (MDL) is known to have a detrimental impact on the capacity of few-mode fiber systems. In the presence of MDL, [...] Read more.

Space-division multiplexing over few-mode fibers is a promising solution to increase the capacity of the future generation of optical transmission systems. Mode-dependent loss (MDL) is known to have a detrimental impact on the capacity of few-mode fiber systems. In the presence of MDL, spatial modes experience different attenuations which results in capacity reduction. In this work, we propose a digital signal processing solution and an optical solution to mitigate the impact of MDL and improve the channel capacity. First, we show that statistical channel state information can be used for a better power allocation for spatial modes instead of equal launch power to increase the system capacity. Afterwards, we propose a deterministic mode scrambling strategy to efficiently reduces the impact of MDL and improves few-mode fiber systems capacity. This scrambling strategy can be efficiently combined with the optimal power allocation to further enhance the capacity. Through numerical simulations of the average and outage capacities, we show that the proposed techniques bring significant capacity gains. Full article

(This article belongs to the Special Issue DSP for Next Generation Fibre Communication Systems)

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14 pages, 3426 KiB

Open AccessArticle

Surface Decorated Zn_0.15Cd_0.85S Nanoflowers with P25 for Enhanced Visible Light Driven Photocatalytic Degradation of Rh-B and Stability

by Muneerah Alomar

, Yueli Liu and Wen Chen^*

State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China

Appl. Sci. 2018, 8(3), 327; https://doi.org/10.3390/app8030327 - 26 Feb 2018

Cited by 4 | Viewed by 3642

Abstract

Decoration of Zn_0.15Cd_0.85S nanoflowers with P25 for forming P25/Zn_0.15Cd_0.85S nanocomposite has been successfully synthesized with fine crystallinity by one-step low temperature hydrothermal method. Photocatalytic efficiency of the as-prepared P25/Zn_0.15Cd_0.85S for the [...] Read more.

Decoration of Zn_0.15Cd_0.85S nanoflowers with P25 for forming P25/Zn_0.15Cd_0.85S nanocomposite has been successfully synthesized with fine crystallinity by one-step low temperature hydrothermal method. Photocatalytic efficiency of the as-prepared P25/Zn_0.15Cd_0.85S for the degradation of Rh-B is evaluated under the visible light irradiation. The synthesized composite is completely characterized with XRD, FESEM, TEM, BET, and UV-vis DRS. TEM observations reveal that P25 is closely deposited on the Zn_0.15Cd_0.85S nanoflowers with maintaining its nanoflower morphology. The photocatalytic activity of the as-obtained photocatalyst shows that the P25/Zn_0.15Cd_0.85S exhibits very high catalytic activity for degradation of Rh-B under visible light irradiation due to an increasing of the active sites and enhancing the catalyst stability because of the minimum recombination of the photo-induced electrons and holes. Moreover, it is found that the nanocomposite retains its photocatalytic activity even after four cycles. In addition, to explain the mechanism of degradation, scavengers are used to confirm the reactive species. Photo-generated holes and ^●OH play a significant role in the visible light of P25/Zn_0.15Cd_0.85S nanocomposite induced degradation system, but electrons play the most important role. Full article

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

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21 pages, 1536 KiB

Open AccessArticle

Multi-Agent Decision Support Tool to Enable Interoperability among Heterogeneous Energy Systems

by Brígida Teixeira¹

, Tiago Pinto^2,*

, Francisco Silva¹

, Gabriel Santos¹

, Isabel Praça¹ and Zita Vale¹

¹ Research Group on Intelligent Engineering and Computing for Advanced Innovation and Development (GECAD), Polytechnic of Porto (IPP), 4200-072 Porto, Portugal

² BISITE Research Group, Bioinformatic, Intelligent Systems and Educational Technology, University of Salamanca (USAL), 37007 Salamanca, Spain

Appl. Sci. 2018, 8(3), 328; https://doi.org/10.3390/app8030328 - 26 Feb 2018

Cited by 27 | Viewed by 4581

Abstract

Worldwide electricity markets are undergoing a major restructuring process. One of the main reasons for the ongoing changes is to enable the adaptation of current market models to the new paradigm that arises from the large-scale integration of distributed generation sources. In order [...] Read more.

Worldwide electricity markets are undergoing a major restructuring process. One of the main reasons for the ongoing changes is to enable the adaptation of current market models to the new paradigm that arises from the large-scale integration of distributed generation sources. In order to deal with the unpredictability caused by the intermittent nature of the distributed generation and the large number of variables that contribute to the energy sector balance, it is extremely important to use simulation systems that are capable of dealing with the required complexity. This paper presents the Tools Control Center (TOOCC), a framework that allows the interoperability between heterogeneous energy and power simulation systems through the use of ontologies, allowing the simulation of scenarios with a high degree of complexity, through the cooperation of the individual capacities of each system. A case study based on real data is presented in order to demonstrate the interoperability capabilities of TOOCC. The simulation considers the energy management of a microgrid of a real university campus, from the perspective of the network manager and also of its consumers/producers, in a projection for a typical day of the winter of 2050. Full article

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

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22 pages, 6976 KiB

Open AccessArticle

Artificial Flora (AF) Optimization Algorithm

by Long Cheng^1,2,*

, Xue-han Wu¹ and Yan Wang¹

¹ Department of Computer and Communication Engineering, Northeastern University, Qinhuangdao 066004, Hebei Province, China

² School of Information Science and Engineering, Northeastern University, Shenyang 110819, Liaoning Province, China

Appl. Sci. 2018, 8(3), 329; https://doi.org/10.3390/app8030329 - 26 Feb 2018

Cited by 100 | Viewed by 8358

Abstract

Inspired by the process of migration and reproduction of flora, this paper proposes a novel artificial flora (AF) algorithm. This algorithm can be used to solve some complex, non-linear, discrete optimization problems. Although a plant cannot move, it can spread seeds within a [...] Read more.

Inspired by the process of migration and reproduction of flora, this paper proposes a novel artificial flora (AF) algorithm. This algorithm can be used to solve some complex, non-linear, discrete optimization problems. Although a plant cannot move, it can spread seeds within a certain range to let offspring to find the most suitable environment. The stochastic process is easy to copy, and the spreading space is vast; therefore, it is suitable for applying in intelligent optimization algorithm. First, the algorithm randomly generates the original plant, including its position and the propagation distance. Then, the position and the propagation distance of the original plant as parameters are substituted in the propagation function to generate offspring plants. Finally, the optimal offspring is selected as a new original plant through the selection function. The previous original plant becomes the former plant. The iteration continues until we find out optimal solution. In this paper, six classical evaluation functions are used as the benchmark functions. The simulation results show that proposed algorithm has high accuracy and stability compared with the classical particle swarm optimization and artificial bee colony algorithm. Full article

(This article belongs to the Special Issue Swarm Robotics)

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9 pages, 1569 KiB

Open AccessArticle

Compact 6 dB Two-Color Continuous Variable Entangled Source Based on a Single Ring Optical Resonator

by Ning Wang^1,2, Shanna Du^1,2 and Yongmin Li^1,2,*

¹ State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China

² Collaborative Innovation Centre of Extreme Optics, Shanxi University, Taiyuan 030006, China

Appl. Sci. 2018, 8(3), 330; https://doi.org/10.3390/app8030330 - 26 Feb 2018

Cited by 4 | Viewed by 3598

Abstract

Continuous-variable entangled optical beams at the degenerate wavelength of 0.8 μm or 1.5 μm have been investigated extensively, but separately. The two-color entangled states of these two useful wavelengths, with sufficiently high degrees of entanglement, still lag behind. In this work, we analyze [...] Read more.

Continuous-variable entangled optical beams at the degenerate wavelength of 0.8 μm or 1.5 μm have been investigated extensively, but separately. The two-color entangled states of these two useful wavelengths, with sufficiently high degrees of entanglement, still lag behind. In this work, we analyze the various limiting factors that affect the entanglement degree. On the basis of this, we successfully achieve 6 dB of two-color quadrature entangled light beams by improving the escape efficiency of the nondegenerate optical amplifier, the stability of the phase-locking servo system, and the detection efficiency. Our entangled source is constructed only from a single ring optical resonator, and thus is highly compact, which is suitable for applications in long-distance quantum communication networks. Full article

(This article belongs to the Section Optics and Lasers)

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16 pages, 2623 KiB

Open AccessArticle

Granular Activated Carbon from Grape Seeds Hydrothermal Char

by Chandra Wahyu Purnomo^1,2, Daniele Castello^3,4

and Luca Fiori^4,*

¹ Advanced Material and Mineral Processing Research Group, Department of Chemical Engineering, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia

² Resource Recovery and Waste Management Research Center, PIAT, Universitas Gadjah Mada, Yogyakarta 55573, Indonesia

³ Department of Energy Technology, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg Øst, Denmark

⁴ Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano 77, 38123 Trento, Italy

Appl. Sci. 2018, 8(3), 331; https://doi.org/10.3390/app8030331 - 27 Feb 2018

Cited by 44 | Viewed by 5656

Abstract

A two-stage conversion process for the production of a valuable product from biomass waste, i.e., grape seeds activated carbon (GSAC) was investigated. Such process involved hydrothermal carbonization (HTC) of grape seeds, followed by chemical activation with potassium hydroxide (KOH). Different HTC temperatures (T [...] Read more.

A two-stage conversion process for the production of a valuable product from biomass waste, i.e., grape seeds activated carbon (GSAC) was investigated. Such process involved hydrothermal carbonization (HTC) of grape seeds, followed by chemical activation with potassium hydroxide (KOH). Different HTC temperatures (T_HTC = 180–250 °C), as well as different KOH:hydrochar ratios (R = 0.25:1–1:1), were explored. The samples that were obtained from both stages of the biomass conversion process were analyzed in terms of textural characterization (apparent total and micro-pore surface areas, total and micro-pore volumes, pore size distribution), proximate and ultimate compositions, thermal stability, surface morphology (via SEM), and surface chemistry characterization (via FTIR). Overall yields of approximately 35% were achieved, which are comparable to those obtained with the state-of-art one-stage process. In a wide range of operating conditions, the higher T_HTC and R, the higher was the surface area of the GSAC, which was maximal (above 1000 m²/g) for T_HTC = 250 °C and R = 0.5. At such optimal conditions, around 90% of the total porosity was due to micro-pores. Such a trend was not fulfilled at the most severe operating conditions (T_HTC = 250 °C; R = 1), which resulted in larger pore size, causing surface area reduction. A proper selection of the process parameters of both the process stages gives great opportunities of tuning and optimizing the overall process. The produced GSACs showed a remarkable thermal stability, and their surface appeared rather free of functional groups. Full article

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

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10 pages, 1656 KiB

Open AccessArticle

Comparative Spectroscopic Investigation of Tm³⁺:Tellurite Glasses for 2-μm Lasing Applications

by Huseyin Cankaya^1,2,3,*, Adil Tolga Gorgulu¹, Adnan Kurt⁴

, Adolfo Speghini⁵

, Marco Bettinelli⁵

and Alphan Sennaroglu^1,6,*

¹ Laser Research Laboratory, Departments of Physics and Electrical-Electronics Engineering, Koç University Rumelifeneri, Sariyer, Istanbul 34450, Turkey

² Center for Free-Electron Laser Science, Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany

³ Physics Department, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

⁴ Teknofil. Inc., Zekeriyakoy, Istanbul 34450, Turkey

⁵ Dipartimento di Biotecnologie, University of Verona and INSTM UdR Verona, Ca’Vignal, Strada Le Grazie 15, 37134 Verona, Italy

⁶ Koç University Surface Science and Technology Center (KUYTAM), Koç University Rumelifeneri, Sariyer, Istanbul 34450, Turkey

Appl. Sci. 2018, 8(3), 333; https://doi.org/10.3390/app8030333 - 27 Feb 2018

Cited by 24 | Viewed by 3609

Abstract

We performed a comparative spectroscopic analysis on three novel Tm³⁺:tellurite-based glasses with the following compositions Tm₂O₃:TeO₂-ZnO (TeZnTm), Tm₂O₃:TeO₂-Nb₂O₅ (TeNbTm), and Tm³⁺:TeO₂-K₂ [...] Read more.

We performed a comparative spectroscopic analysis on three novel Tm³⁺:tellurite-based glasses with the following compositions Tm₂O₃:TeO₂-ZnO (TeZnTm), Tm₂O₃:TeO₂-Nb₂O₅ (TeNbTm), and Tm³⁺:TeO₂-K₂O-Nb₂O₅ (TeNbKTm), primarily for 2-μm laser applications. Tellurite glasses were prepared at different doping concentrations in order to investigate the effect of Tm³⁺ ion concentration as well as host composition on the stimulated emission cross sections and the luminescence quantum efficiencies. By performing Judd–Ofelt analysis, we determined the average radiative lifetimes of the ³H₄ level to be 2.55 ± 0.07 ms, 2.76 ± 0.03 ms and 2.57 ± 0.20 ms for the TeZnTm, TeNbTm and TeNbKTm samples, respectively. We clearly observed the effect of the cross-relaxation, which becomes significant at higher Tm₂O₃ concentrations, leading to the quenching of 1460-nm emission and enhancement of 1860-nm emission. Furthermore, with increasing Tm₂O₃ concentrations, we observed a decrease in the fluorescence lifetimes as a result of the onset of non-radiative decay. For the ³H₄ level, the highest obtained quantum efficiency was 32% for the samples with the lowest Tm₂O₃ ion concentration. For the 1860-nm emission band, the average emission cross section was determined to measure around 6.33 ± 0.34 × 10⁻²¹ cm², revealing the potential of thulium-doped tellurite gain media for 2-μm laser applications in bulk and fiber configurations. Full article

(This article belongs to the Special Issue Rare-Earth Doping for Optical Applications)

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9 pages, 3187 KiB

Open AccessArticle

Minkowski Island and Crossbar Fractal Microstrip Antennas for Broadband Applications

by Roman Kubacki^*, Mirosław Czyżewski and Dariusz Laskowski

Faculty of Electronics, Military University of Technology, 00-809 Warsaw, Poland

Appl. Sci. 2018, 8(3), 334; https://doi.org/10.3390/app8030334 - 27 Feb 2018

Cited by 28 | Viewed by 5793

Abstract

The paper presents microstrip patch antennas, which are based on the fractal antenna concept, and use planar periodic geometries, providing improved characteristics. The properties of the fractal structure were used in a single-fractal layer design as well as in a design, which employs [...] Read more.

The paper presents microstrip patch antennas, which are based on the fractal antenna concept, and use planar periodic geometries, providing improved characteristics. The properties of the fractal structure were used in a single-fractal layer design as well as in a design, which employs fractals on both the upper and bottom layers of the antenna. The final structure, i.e., a double-fractal layer antenna has been optimized to enhance bandwidth and gain of the microstrip antenna. The proposed geometry significantly improved antenna performance. The antenna could support an ultra-wide bandwidth ranging from 4.1 to 19.4 GHz, demonstrating higher gain with an average value of 6 dBi over the frequency range, and a radiation capability directed in the horizontal plane of the antenna. Full article

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

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17 pages, 6603 KiB

Open AccessArticle

REV Application in DEM Analysis of Non-Vibrational Rock Splitting Method to Propose Feasible Borehole Spacing

by Turab H. Jafri and Hankyu Yoo^*

Department of Civil and Environmental Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan 15588, Korea

Appl. Sci. 2018, 8(3), 335; https://doi.org/10.3390/app8030335 - 27 Feb 2018

Cited by 8 | Viewed by 4321

Abstract

Most of the tunnel excavation methods involve the use of explosion and vibration techniques that is not feasible in urban areas due to unavoidable production of noise, vibration, and dust. The environmental considerations of tunneling projects in urban areas demand the use of [...] Read more.

Most of the tunnel excavation methods involve the use of explosion and vibration techniques that is not feasible in urban areas due to unavoidable production of noise, vibration, and dust. The environmental considerations of tunneling projects in urban areas demand the use of excavation methods in which minimum noise, vibration, and dust is produced. In this study, non-vibrational rock splitting method is introduced that involves the fragmentation of rock segments using a split-wedge system inserted into already drilled boreholes. The main objective of this study is the investigation of important parameters involved in the non-vibrational rock splitting method for improving its efficiency. Discrete element analysis of this method was performed using Particle Flow Code (PFC^2D) and the concept of Representative Elementary Volume (REV) was used to simulate intact rocks based on their unconfined compressive strength and modulus ratio concept. Maximum borehole spacing values were obtained using the numerical simulation of rock splitting process in intact rocks. The numerical analysis results show that increased borehole spacing values can be used for all intact rock types in cases of average modulus ratio and high modulus ratio and also that decreasing the borehole depth generally results in the use of increased borehole spacing. Full article

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11 pages, 2532 KiB

Open AccessFeature PaperArticle

Radiation Pressure-Driven Plasma Surface Dynamics in Ultra-Intense Laser Pulse Interactions with Ultra-Thin Foils

by Bruno Gonzalez-Izquierdo¹, Remi Capdessus¹, Martin King¹

, Ross J. Gray¹, Robbie Wilson¹

, Rachel J. Dance¹, John McCreadie¹, Nicholas M. H. Butler¹, Steve J. Hawkes², James S. Green², Nicola Booth², Marco Borghesi³, David Neely² and Paul McKenna^1,*

¹ SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK

² Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, UK

³ Centre for Plasma Physics, Queens University Belfast, Belfast BT7 1NN, UK

Appl. Sci. 2018, 8(3), 336; https://doi.org/10.3390/app8030336 - 27 Feb 2018

Cited by 9 | Viewed by 4739

Abstract

The dynamics of the plasma critical density surface in an ultra-thin foil target irradiated by an ultra-intense (∼6 × 10

^{20}

Wcm

^{- 2}

) laser pulse is investigated experimentally and via 2D particle-in-cell simulations. Changes to the surface motion are diagnosed as [...] Read more.

The dynamics of the plasma critical density surface in an ultra-thin foil target irradiated by an ultra-intense (∼6 × 10

^{20}

Wcm

^{- 2}

) laser pulse is investigated experimentally and via 2D particle-in-cell simulations. Changes to the surface motion are diagnosed as a function of foil thickness. The experimental and numerical results are compared with hole-boring and light-sail models of radiation pressure acceleration, to identify the foil thickness range for which each model accounts for the measured surface motion. Both the experimental and numerical results show that the onset of relativistic self-induced transparency, in the thinnest targets investigated, limits the velocity of the critical surface, and thus the effectiveness of radiation pressure acceleration. Full article

(This article belongs to the Special Issue Laser-Driven Particle Acceleration)

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22 pages, 5183 KiB

Open AccessArticle

MOVICLOUD: Agent-Based 3D Platform for the Labor Integration of Disabled People

by Alberto L. Barriuso^*

, Fernando De la Prieta

, Gabriel Villarrubia González

, Daniel H. De La Iglesia

and Álvaro Lozano

BISITE Digital Innovation Hub., University of Salamanca, Edificio Multiusos I+D+i, C/Espejo SN, 37007 Salamanca, Spain

Appl. Sci. 2018, 8(3), 337; https://doi.org/10.3390/app8030337 - 27 Feb 2018

Cited by 9 | Viewed by 4772

Abstract

Agent-Based Social Simulation (ABSS), used in combination with three-dimensional representation, makes it possible to do near-reality modeling and visualizations of changing and complex environments. In this paper, we describe the design and implementation of a tool that integrates these two techniques. The purpose [...] Read more.

Agent-Based Social Simulation (ABSS), used in combination with three-dimensional representation, makes it possible to do near-reality modeling and visualizations of changing and complex environments. In this paper, we describe the design and implementation of a tool that integrates these two techniques. The purpose of this tool is to assist in creating a work environment that is adapted to the needs of people with disabilities. The tool measures the degree of accessibility in the place of work and identifies the architectural barriers of the environment by considering the activities carried out by workers. Thus, thanks to the use of novel mechanisms and simulation techniques more people with disabilities will have the opportunity to work and feel comfortable in the environment. To validate the developed tool, a case study was performed in a real environment. Full article

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

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28 pages, 10678 KiB

Open AccessArticle

MAP-MRF-Based Super-Resolution Reconstruction Approach for Coded Aperture Compressive Temporal Imaging

by Tinghua Zhang^1,2,* and Kun Gao¹

¹ School of Optics and Electronics, Beijing Institute of Technology, Beijing 100081, China

² Department of Optical and Electronic Equipment, Space Engineering University, Beijing 101416, China

Appl. Sci. 2018, 8(3), 338; https://doi.org/10.3390/app8030338 - 27 Feb 2018

Cited by 2 | Viewed by 4494

Abstract

Coded Aperture Compressive Temporal Imaging (CACTI) can afford low-cost temporal super-resolution (SR), but limits are imposed by noise and compression ratio on reconstruction quality. To utilize inter-frame redundant information from multiple observations and sparsity in multi-transform domains, a robust reconstruction approach based on [...] Read more.

Coded Aperture Compressive Temporal Imaging (CACTI) can afford low-cost temporal super-resolution (SR), but limits are imposed by noise and compression ratio on reconstruction quality. To utilize inter-frame redundant information from multiple observations and sparsity in multi-transform domains, a robust reconstruction approach based on maximum a posteriori probability and Markov random field (MAP-MRF) model for CACTI is proposed. The proposed approach adopts a weighted 3D neighbor system (WNS) and the coordinate descent method to perform joint estimation of model parameters, to achieve the robust super-resolution reconstruction. The proposed multi-reconstruction algorithm considers both total variation (TV) and

ℓ_{2, 1}

norm in wavelet domain to address the minimization problem for compressive sensing, and solves it using an accelerated generalized alternating projection algorithm. The weighting coefficient for different regularizations and frames is resolved by the motion characteristics of pixels. The proposed approach can provide high visual quality in the foreground and background of a scene simultaneously and enhance the fidelity of the reconstruction results. Simulation results have verified the efficacy of our new optimization framework and the proposed reconstruction approach. Full article

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22 pages, 6175 KiB

Open AccessFeature PaperArticle

Metaheuristic Algorithm for Photovoltaic Parameters: Comparative Study and Prediction with a Firefly Algorithm

by Mohamed Louzazni^1,*

, Ahmed Khouya¹, Khalid Amechnoue¹, Alessandro Gandelli², Marco Mussetta²

and Aurelian Crăciunescu³

¹ Mathematics Informatic & Applications Team, National School of Applied Sciences, Abdelmalek Essaadi University, Tanger 1818, Morocco

² Department of Energy, Politecnico di Milano, 20156 Milano, Italy

³ Electrical Engineering Department, University Politehnica of Bucharest, Bucharest 060042, Romania

Appl. Sci. 2018, 8(3), 339; https://doi.org/10.3390/app8030339 - 27 Feb 2018

Cited by 100 | Viewed by 10752

Abstract

In this paper, a Firefly algorithm is proposed for identification and comparative study of five, seven and eight parameters of a single and double diode solar cell and photovoltaic module under different solar irradiation and temperature. Further, a metaheuristic algorithm is proposed in [...] Read more.

In this paper, a Firefly algorithm is proposed for identification and comparative study of five, seven and eight parameters of a single and double diode solar cell and photovoltaic module under different solar irradiation and temperature. Further, a metaheuristic algorithm is proposed in order to predict the electrical parameters of three different solar cell technologies. The first is a commercial RTC mono-crystalline silicon solar cell with single and double diodes at 33 °C and 1000 W/m². The second, is a flexible hydrogenated amorphous silicon a-Si:H solar cell single diode. The third is a commercial photovoltaic module (Photowatt-PWP 201) in which 36 polycrystalline silicon cells are connected in series, single diode, at 25 °C and 1000 W/m² from experimental current-voltage. The proposed constrained objective function is adapted to minimize the absolute errors between experimental and predicted values of voltage and current in two zones. Finally, for performance validation, the parameters obtained through the Firefly algorithm are compared with recent research papers reporting metaheuristic optimization algorithms and analytical methods. The presented results confirm the validity and reliability of the Firefly algorithm in extracting the optimal parameters of the photovoltaic solar cell. Full article

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

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21 pages, 4584 KiB

Open AccessArticle

An Integrated Open Approach to Capturing Systematic Knowledge for Manufacturing Process Innovation Based on Collective Intelligence

by Gangfeng Wang^1,*

, Yongbiao Hu¹, Xitian Tian², Junhao Geng², Gailing Hu³ and Min Zhang²

¹ Key Laboratory of Road Construction Technology and Equipment of MOE, School of Construction Machinery, Chang’an University, Xi’an 710064, China

² School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China

³ School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Appl. Sci. 2018, 8(3), 340; https://doi.org/10.3390/app8030340 - 27 Feb 2018

Cited by 14 | Viewed by 5708

Abstract

Process innovation plays a vital role in the manufacture realization of increasingly complex new products, especially in the context of sustainable development and cleaner production. Knowledge-based innovation design can inspire designers’ creative thinking; however, the existing scattered knowledge has not yet been properly [...] Read more.

Process innovation plays a vital role in the manufacture realization of increasingly complex new products, especially in the context of sustainable development and cleaner production. Knowledge-based innovation design can inspire designers’ creative thinking; however, the existing scattered knowledge has not yet been properly captured and organized according to Computer-Aided Process Innovation (CAPI). Therefore, this paper proposes an integrated approach to tackle this non-trivial issue. By analyzing the design process of CAPI and technical features of open innovation, a novel holistic paradigm of process innovation knowledge capture based on collective intelligence (PIKC-CI) is constructed from the perspective of the knowledge life cycle. Then, a multi-source innovation knowledge fusion algorithm based on semantic elements reconfiguration is applied to form new public knowledge. To ensure the credibility and orderliness of innovation knowledge refinement, a collaborative editing strategy based on knowledge lock and knowledge–social trust degree is explored. Finally, a knowledge management system MPI-OKCS integrating the proposed techniques is implemented into the pre-built CAPI general platform, and a welding process innovation example is provided to illustrate the feasibility of the proposed approach. It is expected that our work would lay the foundation for the future knowledge-inspired CAPI and smart process planning. Full article

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

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13 pages, 3147 KiB

Open AccessArticle

Disentangling Long Trajectory Contributions in Two-Colour High Harmonic Generation

by Cornelia Hofmann^1,*

, Alexandra S. Landsman¹ and Ursula Keller²

¹ Max Planck Insitute for the Physics of Complex Systems, Nöthnitzer Straße 38, D-01187 Dresden, Germany

² Department of Physics, ETH Zurich, 8093 Zurich, Switzerland

Appl. Sci. 2018, 8(3), 341; https://doi.org/10.3390/app8030341 - 28 Feb 2018

Cited by 8 | Viewed by 7360

Abstract

This work investigates High Harmonic Generation (HHG) in gas targets, induced by intense two-colour driving fields. We compared classical trajectory Monte Carlo simulations based on a semiclassical model of strong field tunnel ionisation of helium to experimental HHG spectra, and investigated the relative [...] Read more.

This work investigates High Harmonic Generation (HHG) in gas targets, induced by intense two-colour driving fields. We compared classical trajectory Monte Carlo simulations based on a semiclassical model of strong field tunnel ionisation of helium to experimental HHG spectra, and investigated the relative contribution of long trajectories to low harmonic orders. This phenomenon can be found even when the experimental setup is chosen to suppress long trajectories and favour phase matching for short trajectories. Full article

(This article belongs to the Special Issue Extreme Time Scale Photonics)

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21 pages, 10219 KiB

Open AccessArticle

Tackling Area Coverage Problems in a Reconfigurable Floor Cleaning Robot Based on Polyomino Tiling Theory

by Veerajagadheswar Prabakaran^1,*, Rajesh Elara Mohan¹, Vinu Sivanantham¹, Thejus Pathmakumar¹

and Suganya Sampath Kumar²

¹ Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore

² Parkway Pantai Groups, Mount Elizabeth, Novena, 38 Irrawaddy Rd, Singapore 68986898, Singapore

Appl. Sci. 2018, 8(3), 342; https://doi.org/10.3390/app8030342 - 28 Feb 2018

Cited by 17 | Viewed by 5796

Abstract

Whilst Polyomino tiling theory has been extensively studied as a branch of research in mathematics, its application has been largely confined to multimedia, graphics and gaming domains. In this paper, we present a novel application of Tromino tiling theory, a class of Polyomino [...] Read more.

Whilst Polyomino tiling theory has been extensively studied as a branch of research in mathematics, its application has been largely confined to multimedia, graphics and gaming domains. In this paper, we present a novel application of Tromino tiling theory, a class of Polyomino with three cells in the context of a reconfigurable floor cleaning robot, hTromo. The developed robot platform is able to automatically generate a global tiling set required to cover a defined space while leveraging on the Tromino tiling theory. Specifically, we validated the application of five Tromino tiling theorems with our hTromo robot. Experiments performed clearly demonstrate the efficacy of the proposed approach resulting in very high levels of area coverage performance in all considered experimental cases. This paper also presents the system architecture of our hTromo robot and a detailed description of the five tiling theorems applied in this study. Full article

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11 pages, 936 KiB

Open AccessArticle

Using a Combination of Spectral and Textural Data to Measure Water-Holding Capacity in Fresh Chicken Breast Fillets

by Beibei Jia¹, Wei Wang^1,*

, Seung-Chul Yoon², Hong Zhuang² and Yu-Feng Li^3,*

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

² Quality & Safety Assessment Research Unit, U.S. National Poultry Research Center, USDA-ARS, 950 College Station Rd., Athens, GA 30605, USA

³ Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China

Appl. Sci. 2018, 8(3), 343; https://doi.org/10.3390/app8030343 - 28 Feb 2018

Cited by 9 | Viewed by 4150

Abstract

The aim here was to explore the potential of visible and near-infrared (Vis/NIR) hyperspectral imaging (400–1000 nm) to classify fresh chicken breast fillets into different water-holding capacity (WHC) groups. Initially, the extracted spectra and image textural features, as well as the mixed data [...] Read more.

The aim here was to explore the potential of visible and near-infrared (Vis/NIR) hyperspectral imaging (400–1000 nm) to classify fresh chicken breast fillets into different water-holding capacity (WHC) groups. Initially, the extracted spectra and image textural features, as well as the mixed data of the two, were used to develop partial least square-discriminant analysis (PLS-DA) classification models. Smoothing, a first derivative process, and principle component analysis (PCA) were carried out sequentially on the mean spectra of all samples to deal with baseline offsets and identify outlier data. Six samples located outside the confidence ellipses of 95% confidence level in the score plot were defined as outliers. A PLS-DA model based on the outlier-free spectra provided a correct classification rate (CCR) value of 78% in the prediction set. Then, seven optimal wavelengths selected using a successive projections algorithm (SPA) were used to develop a simplified PLS-DA model that obtained a slightly reduced CCR with a value of 73%. Moreover, the gray-level co-occurrence matrix (GLCM) was implemented on the first principle component image (with 98.13% of variance) of the hyperspectral image to extract textural features (contrast, correlation, energy, and homogeneity). The CCR of the model developed using textural variables was less optimistic with a value of 59%. Compared to results of models based on spectral or textural data individually, the performance of the model based on the mixed data of optimal spectral and textural features was the best with an improved CCR of 86%. The results showed that the spectral and textural data of hyperspectral images together can be integrated in order to measure and classify the WHC of fresh chicken breast fillets. Full article

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

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22 pages, 4805 KiB

Open AccessArticle

Safety Design and Development of a Human-Robot Collaboration Assembly Process in the Automotive Industry

by Sahar Heydaryan^1,*

, Joel Suaza Bedolla² and Giovanni Belingardi¹

¹ Department of Mechanical and Aerospace Engineering (DIMEAS), Politecnico di Torino, 10129 Torino, Italy

² Department of Management and Production Engineering (DIGEP), Politecnico di Torino, 10129 Torino, Italy

Appl. Sci. 2018, 8(3), 344; https://doi.org/10.3390/app8030344 - 28 Feb 2018

Cited by 91 | Viewed by 10264

Abstract

Human-robot collaboration (HRC) is a complex procedure in manufacturing due to the problems posed by compatibility and operational safety among humans and robots, and by task definitions among them in a collaborative order. In this paper, the research results of the human-robot collaboration [...] Read more.

Human-robot collaboration (HRC) is a complex procedure in manufacturing due to the problems posed by compatibility and operational safety among humans and robots, and by task definitions among them in a collaborative order. In this paper, the research results of the human-robot collaboration study for the case of an automotive brake disc assembly is presented. The analytic hierarchy process (AHP) is proposed as a decision-making method for the human-robot collaboration system, and detailed hierarchical task analysis (HTA) is applied to allocate operational tasks to humans and robots, thus reducing the chance of duty interference. Additionally, a virtual environment software (Tecnomatix Process Simulate, version 11.1,80, Siemens, Munich, BY, Germany, 2012) is used to model the assembly workstation, providing an opportunity to evaluate the feasibility of the process through different scenarios. Finally, an experimental test is conducted to evaluate the performance of the assembly procedure. This research proves that, although human-robot collaboration increases the total process time slightly, this collaboration improves human ergonomics considerably and reduces the operator injury risk. Full article

(This article belongs to the Section Mechanical Engineering)

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19 pages, 26979 KiB

Open AccessArticle

Characterization of Control-Dependent Variable Stiffness Behavior in Discrete Muscle-Like Actuators

by Caleb Fuller^*,†

and Joshua Schultz^†

¹ Department of Mechanical Engineering, University of Tulsa, Tulsa, OK 74104, USA

^† Current address: 800 S. Tucker Dr. Tulsa, OK 74104, USA.

Appl. Sci. 2018, 8(3), 346; https://doi.org/10.3390/app8030346 - 28 Feb 2018

Cited by 3 | Viewed by 5132

Abstract

This paper presents the modeling, characterization and validation for a discrete muscle-like actuator system composed of individual on–off motor units with complex dynamics inherent to the architecture. The dynamics include innate hardening behavior in the actuator with increased length. A series elastic actuator [...] Read more.

This paper presents the modeling, characterization and validation for a discrete muscle-like actuator system composed of individual on–off motor units with complex dynamics inherent to the architecture. The dynamics include innate hardening behavior in the actuator with increased length. A series elastic actuator model is used as the plant model for an observer used in feedback control of the actuator. Simulations are performed showing the nonlinear nature of the changing stiffness as well as how this affects the dynamics, clearly observed in the phase portrait. Variable-stiffness hardening behavior is evaluated in experiment and shows good agreement with the model. Full article

(This article belongs to the Special Issue Bio-Inspired Robotics)

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19 pages, 3401 KiB

Open AccessArticle

Dimensionless Energy Conversion Characteristics of an Air-Powered Hydraulic Vehicle

by Dongkai Shen, Qilong Chen and Yixuan Wang^*

School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

Appl. Sci. 2018, 8(3), 347; https://doi.org/10.3390/app8030347 - 28 Feb 2018

Cited by 2 | Viewed by 5652

Abstract

Due to the advantages of resource conservation and less exhaust emissions, compressed air-powered vehicle has attracted more and more attention. To improve the power and efficiency of air-powered vehicle, an air-powered hydraulic vehicle was proposed. As the main part of the air-powered hydraulic [...] Read more.

Due to the advantages of resource conservation and less exhaust emissions, compressed air-powered vehicle has attracted more and more attention. To improve the power and efficiency of air-powered vehicle, an air-powered hydraulic vehicle was proposed. As the main part of the air-powered hydraulic vehicles, HP transformer (short for Hydropneumatic transformer) is used to convert the pneumatic power to higher hydraulic power. In this study, to illustrate the energy conversion characteristics of air-powered hydraulic vehicle, dimensionless mathematical model of the vehicle’s working process was set up. Through experimental study on the vehicle, the dimensionless model was verified. Through simulation study on the vehicle, the following can be obtained: firstly, the increase of the hydraulic chamber orifice and the area ratio of the pistons can lead to a higher output power, while output pressure is just the opposite. Moreover, the increase of the output pressure and the aperture of the hydraulic chamber can lead to a higher efficiency, while area ratio of the pistons played the opposite role. This research can be referred to in the performance and design optimization of the HP transformers. Full article

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

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14 pages, 2774 KiB

Open AccessArticle

Intelligent Video Surveillance Platform for Wireless Multimedia Sensor Networks

by Nasim Abbas^1,2

, Fengqi Yu^1,2,* and Yang Fan^1,2

¹ Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Appl. Sci. 2018, 8(3), 348; https://doi.org/10.3390/app8030348 - 28 Feb 2018

Cited by 21 | Viewed by 5157

Abstract

Wireless multimedia sensor networks (WMSNs) are increasingly being deployed for surveillance and monitoring applications. WMSNs applications produce large amount of data, which require high transmission rates. An efficient and seamless delivery of multimedia services in WMSNs is still a challenging task. This article [...] Read more.

Wireless multimedia sensor networks (WMSNs) are increasingly being deployed for surveillance and monitoring applications. WMSNs applications produce large amount of data, which require high transmission rates. An efficient and seamless delivery of multimedia services in WMSNs is still a challenging task. This article proposes an intelligent video surveillance platform (IVSP) for wireless multimedia sensor networks. IVSP presents the design of a networked system for joint rate control and error control of video over resource-constrained embedded devices. First, a combination of two different congestion indicators is introduced to differentiate between congestion levels and handle them accordingly. Second, a feedback-based rate controller is developed to maximize received video quality, in which sensor nodes can adaptively adjust their sending rates. Finally, a different retransmission mechanism for different packets is proposed. Lost packets can be stored temporarily and resend when free channel is available to avoid congestion. The core component of IVSP is an open source hardware platform, which is based on Raspberry Pi sensor nodes. IVSP is extensively evaluated on 7 Raspberry Pi sensor nodes. We present the results of 7-node real-world deployment of IVSP in a video surveillance application and show that it works well in long-term deployments. Full article

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21 pages, 5735 KiB

Open AccessArticle

Using Multispectral Airborne LiDAR Data for Land/Water Discrimination: A Case Study at Lake Ontario, Canada

by Salem Morsy^*

, Ahmed Shaker and Ahmed El-Rabbany

Department of Civil Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada

Appl. Sci. 2018, 8(3), 349; https://doi.org/10.3390/app8030349 - 28 Feb 2018

Cited by 22 | Viewed by 5516

Abstract

Coastal areas are environmentally sensitive and are affected by nature events and human activities. Land/water interaction in coastal areas changes over time and, therefore, requires accurate detection and frequent monitoring. Multispectral Light Detection and Ranging (LiDAR) systems, which operate at different wavelengths, have [...] Read more.

Coastal areas are environmentally sensitive and are affected by nature events and human activities. Land/water interaction in coastal areas changes over time and, therefore, requires accurate detection and frequent monitoring. Multispectral Light Detection and Ranging (LiDAR) systems, which operate at different wavelengths, have become available. This new technology can provide an effective and accurate solution for the determination of the land/water interface. In this context, we aim to investigate a set of point features based on elevation, intensity, and geometry for this application, followed by a presentation of an unsupervised land/water discrimination method based on seeded region growing algorithm. The multispectral airborne LiDAR sensor, the Optech Titan, was used to acquire LiDAR data at three wavelengths (1550, 1064, and 532 nm) of a study area covering part of Lake Ontario in Scarborough, Canada for testing the discrimination methods. The elevation- and geometry-based features achieved an average overall accuracy of 75.1% and 74.2%, respectively, while the intensity-based features achieved 63.9% accuracy. The region growing method succeeded in discriminating water from land with more than 99% overall accuracy, and the land/water boundary was delineated with an average root mean square error of 0.51 m. The automation of this method is restricted by having double returns from water bodies at the 532 nm wavelength. Full article

(This article belongs to the Special Issue Laser Scanning)

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24 pages, 2812 KiB

Open AccessArticle

Smart Control System to Optimize Time of Use in a Solar-Assisted Air-Conditioning by Ejector for Residential Sector

by Giovanna Avedian-González^1,†, Apolinar González-Potes^1,2,*,†

, Vrani Ibarra-Junquera^2,†, Walter A. Mata-López^1,†

and Carlos Escobar-del Pozo^1,†

¹ Faculty of Electrical and Mechanical Engineering, University of Colima, Km. 9 Carretera Colima-Coquimatlán, Coquimatlán Col. C.P. 28400, Mexico

² Agrobio-Technological Laboratory, University of Colima Tecnoparque CLQ, Colima, C.P. 28629, Mexico

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(3), 350; https://doi.org/10.3390/app8030350 - 28 Feb 2018

Cited by 3 | Viewed by 5704

Abstract

The present work provides a series of theoretical improvements of a control strategy in order to optimize the time of use of solar air-conditioning by an ejector distributed in multiple solar collectors of vacuum tubes for the residential sector, which will allow us [...] Read more.

The present work provides a series of theoretical improvements of a control strategy in order to optimize the time of use of solar air-conditioning by an ejector distributed in multiple solar collectors of vacuum tubes for the residential sector, which will allow us to reduce carbon-dioxide emissions, costs and electrical energy consumption. In a solar ejector cooling system, the instability of the solar source of energy causes an operational conflict between the solar thermal system and ejector cooling cycle. A fuzzy control structure for the supervisory ejector cycle and multi-collector control system is developed: the first control is applied to control the mass flow of the generator and the evaporator for different cooling capacities (3, 3.5, 4, 4.5 and 5 kW) and set a temperature reference according to the operating conditions; the second is applied to keep a constant temperature power source that feeds the low-grade ejector cooling cycle using R134aas refrigerant. For the present work, the temperature of the generator oscillates between 65 °C and 90 °C, a condenser temperature of 30 °C and an evaporator temperature of 10 °C. For the purpose of optimization, there are different levels of performance for time of use: the Mode 0 (economic) gives a performance of 17.55 h, Mode 5 (maximum cooling power) 14.86 h and variable mode (variable mode of capacities) 16.25 h, on average. Simulations are done in MATLAB-Simulink applying fuzzy logic for a mathematical model of the thermal balance. They are compared with two different types of solar radiation: real radiation and disturbed radiation. Full article

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

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14 pages, 5818 KiB

Open AccessFeature PaperArticle

A Vector Printing Method for High-Speed Electrohydrodynamic (EHD) Jet Printing Based on Encoder Position Sensors

by Thanh Huy Phung¹, Luu Ngoc Nguyen² and Kye-Si Kwon^2,*

¹ Department of Electronics Material and Devices Engineering, Soonchunhyang University, 22, Soonchunhyang-Ro, Shinchang, Asan, Chungnam 336-745, Korea

² Department of Mechanical Engineering, Soonchunhyang University, 22, Soonchunhyang-Ro, Shinchang, Asan, Chungnam 336-745, Korea

Appl. Sci. 2018, 8(3), 351; https://doi.org/10.3390/app8030351 - 28 Feb 2018

Cited by 11 | Viewed by 6070

Abstract

Electrohyrodynamic (EHD) jet printing has been widely used in the field of direct micro-nano patterning applications, due to its high resolution printing capability. So far, vector line printing using a single nozzle has been widely used for most EHD printing applications. However, the [...] Read more.

Electrohyrodynamic (EHD) jet printing has been widely used in the field of direct micro-nano patterning applications, due to its high resolution printing capability. So far, vector line printing using a single nozzle has been widely used for most EHD printing applications. However, the application has been limited to low-speed printing, to avoid non-uniform line width near the end points where line printing starts and ends. At end points of line vector printing, the deposited drop amount is likely to be significantly large compared to the rest of the printed lines, due to unavoidable acceleration and deceleration. In this study, we proposed a method to solve the printing quality problems by producing droplets at an equally spaced distance, irrespective of the printing speed. For this purpose, an encoder processing unit (EPU) was developed, so that the jetting trigger could be generated according to user-defined spacing by using encoder position signals, which are used for the positioning control of the two linear stages. Full article

(This article belongs to the Special Issue Printed Electronics 2017)

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16 pages, 2092 KiB

Open AccessArticle

A Lattice Boltzmann Method and Asynchronous Model Coupling for Viscoelastic Fluids

by Jin Su^1,*

, Jie Ouyang^2,* and Junxiang Lu¹

¹ School of Science, Xi’an Polytechnic University, Xi’an 710048, China

² School of Science, Northwestern Polytechnical University, Xi’an 710129, China

Appl. Sci. 2018, 8(3), 352; https://doi.org/10.3390/app8030352 - 28 Feb 2018

Viewed by 3991

Abstract

The numerical algorithms of viscoelastic flows can appear a tremendous challenge as the Weissenberg number (Wi) enlarged sufficiently. In this study, we present a generalized technique of time-stably advancing based on the coupled lattice Boltzmann method, in order to improve the [...] Read more.

The numerical algorithms of viscoelastic flows can appear a tremendous challenge as the Weissenberg number (Wi) enlarged sufficiently. In this study, we present a generalized technique of time-stably advancing based on the coupled lattice Boltzmann method, in order to improve the numerical stability of simulations at a high Wi number. The mathematical models of viscoelastic fluids include both the equation of the solvent and the Oldroyd-B constitutive equation of the polymer. In the two-dimensional (2D) channel flow, the coupled method shows good agreements between the corresponding exact results and the numerical results obtained by our method. In addition, as the Wi number increased, for the viscoelastic flows through contractions, we show that the prediction of our presented method can reproduce the same numerical results that were reported by previous studies. The main advantage of current method is that it can be applied to simulate the complex phenomena of the viscoelastic fluids. Full article

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

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12 pages, 5940 KiB

Open AccessArticle

Oxygen Vacancy-Mediated ZnO Nanoparticle Photocatalyst for Degradation of Methylene Blue

by Qiuping Zhang¹, Ming Xu^1,2,*

, Biao You², Qin Zhang¹, Huan Yuan¹ and Kostya (Ken) Ostrikov^3,4,*

¹ Key Laboratory of Information Materials of Sichuan Province, School of Electrical and Information Engineering, Southwest University for Nationalities, Chengdu 610041, China

² National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China

³ Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000, Australia

⁴ CSIRO-QUT Joint Sustainable Processes and Devices Laboratory, P.O. Box 218, Lindfield, NSW 2070, Australia

Appl. Sci. 2018, 8(3), 353; https://doi.org/10.3390/app8030353 - 28 Feb 2018

Cited by 122 | Viewed by 9618

Abstract

ZnO nanoparticles (NPs) are synthesized by deoxidizing ZnO powder in a vacuum drying process. This process reduces the size of the NPs and increases the concentration of oxygen vacancies on their surfaces. ZnO NPs with sufficient oxygen vacancies are highly effective for the [...] Read more.

ZnO nanoparticles (NPs) are synthesized by deoxidizing ZnO powder in a vacuum drying process. This process reduces the size of the NPs and increases the concentration of oxygen vacancies on their surfaces. ZnO NPs with sufficient oxygen vacancies are highly effective for the photodecomposition of methylene blue (MB) dye in water under ultraviolet irradiation. The MB degradation efficiency exceeds 99 percent after 50 min of light irradiation, and the catalytic property of the NPs remains stable over several complete degradation cycles. It is revealed that the concentration of oxygen vacancies on the surface, and the photocatalytic activity, are both higher for smaller NPs. Oxygen vacancies reduce the recombination rate of photo-generated charge carriers by capturing the electrons and hence, improve the efficiency of redox reactions. In addition, a smaller particle size leads to a larger specific surface area and a higher photonic efficiency for the ZnO NPs. Full article

(This article belongs to the Special Issue Nanostructured Photodetectors and Photovoltaic Devices)

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12 pages, 2838 KiB

Open AccessFeature PaperArticle

Application of Auxetic Foam in Sports Helmets

by Leon Foster^1,*

, Prashanth Peketi², Thomas Allen³

, Terry Senior¹, Olly Duncan⁴ and Andrew Alderson⁴

¹ Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield S1 1WB, UK

² Adidas Futures Team, Portland, OR 97217, USA

³ School of Engineering, Manchester Metropolitan University, Manchester M1 5GD, UK

⁴ Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB, UK

Appl. Sci. 2018, 8(3), 354; https://doi.org/10.3390/app8030354 - 1 Mar 2018

Cited by 109 | Viewed by 16453

Abstract

This investigation explored the viability of using open cell polyurethane auxetic foams to augment the conformable layer in a sports helmet and improve its linear impact acceleration attenuation. Foam types were compared by examining the impact severity on an instrumented anthropomorphic headform within [...] Read more.

This investigation explored the viability of using open cell polyurethane auxetic foams to augment the conformable layer in a sports helmet and improve its linear impact acceleration attenuation. Foam types were compared by examining the impact severity on an instrumented anthropomorphic headform within a helmet consisting of three layers: a rigid shell, a stiff closed cell foam, and an open cell foam as a conformable layer. Auxetic and conventional foams were interchanged to act as the helmet’s conformable component. Attenuation of linear acceleration was examined by dropping the combined helmet and headform on the front and the side. The helmet with auxetic foam reduced peak linear accelerations (p < 0.05) relative to its conventional counterpart at the highest impact energy in both orientations. Gadd Severity Index reduced by 11% for frontal impacts (38.9 J) and 44% for side impacts (24.3 J). The conformable layer within a helmet can influence the overall impact attenuating properties. The helmet fitted with auxetic foam can attenuate impact severity more than when fitted with conventional foam, and warrants further investigation for its potential to reduce the risk of traumatic brain injuries in sport specific impacts. Full article

(This article belongs to the Special Issue Sports Materials)

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8 pages, 1247 KiB

Open AccessArticle

Temperature Dependence on Density, Viscosity, and Electrical Conductivity of Ionic Liquid 1-Ethyl-3-Methylimidazolium Fluoride

by Fengguo Liu¹, Xiongwei Zhong², Junli Xu³, Ali Kamali¹

and Zhongning Shi^1,*

¹ School of Metallurgy, Northeastern University, No. 3-11, Wenhua Road, Shenyang 110819, China

² Department of Materials Science and Engineering, Southern University of Science and Technology, No. 1088, Xueyuanda Road, Shenzhen 518055, China

³ School of Science, Northeastern University, No. 3-11, Wenhua Road, Shenyang 110819, China

Appl. Sci. 2018, 8(3), 356; https://doi.org/10.3390/app8030356 - 1 Mar 2018

Cited by 18 | Viewed by 7142

Abstract

Ionic liquids are considered environmentally friendly media for various industrial applications. Basic data on physicochemical properties are significant for a new material, in terms of developing its potential applications. In this work, 1-ethyl-3-methylimidazolium fluoride ([EMIm]F) ionic liquid was synthesized via an anion metathesis [...] Read more.

Ionic liquids are considered environmentally friendly media for various industrial applications. Basic data on physicochemical properties are significant for a new material, in terms of developing its potential applications. In this work, 1-ethyl-3-methylimidazolium fluoride ([EMIm]F) ionic liquid was synthesized via an anion metathesis process. Physical properties including the density, viscosity, electrical conductivity, and thermal stability of the product were measured. The results show that the density of [EMIm]F decreases linearly with temperature increases, while dynamic viscosity decreases rapidly below 320 K and the temperature dependence of electrical conductivity is in accordance with the VFT (Vogel–Fulcher–Tammann) equation. The temperature dependence of the density, conductivity, and viscosity of [EMIm]F can be expressed via the following equations: ρ = 1.516 − 1.22 × 10⁻³ T, σ_m = 4417.1exp[−953.17/(T − 166.65)] and η = 2.07 × 10⁻⁷exp(−5.39 × 10⁴/T), respectively. [EMIm]F exhibited no clear melting point. However, its glass transition point and decomposition temperature are −71.3 °C and 135 °C, respectively. Full article

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

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16 pages, 6660 KiB

Open AccessArticle

A Biomimetic Approach for Designing a Full External Breast Prosthesis: Post-Mastectomy

by Pedro Cruz^1,*

, F. Josue Hernandez¹

, Ma. Lourdes Zuñiga², Jose Maria Rodríguez³, Rafael Figueroa⁴, Antonio Vertiz² and Zaira Pineda¹

¹ Department of Mechanical Engineering, Autonomous University of San Luis Potosí, UASLP, 78700 San Luis Potosi, Mexico

² Department of Nursing, Autonomous University of San Luis Potosí, UASLP, 78700 San Luis Potosi, Mexico

³ Department of Mechanical Engineering, National Center for Research and Technological Development, CENIDET, 62490 Cuernavaca, Mexico

⁴ Department of Engineering, Sonora Institute of Technology, 85130 Cd Obregon, Mexico

Appl. Sci. 2018, 8(3), 357; https://doi.org/10.3390/app8030357 - 1 Mar 2018

Cited by 8 | Viewed by 10152

Abstract

This work presents the design of a new breast prosthesis using the biomimetic technique for cases of complete mastectomy to address the problem of the increasing number of women diagnosed with breast cancer in Mexico who are candidates for a mastectomy. The designed [...] Read more.

This work presents the design of a new breast prosthesis using the biomimetic technique for cases of complete mastectomy to address the problem of the increasing number of women diagnosed with breast cancer in Mexico who are candidates for a mastectomy. The designed prosthesis considers the morphology of a real breast regarding its internal structure to obtain authentic mobility and feel. In order to accomplish this, a model was obtained in 3D CAD using a coordinate measuring machine (CMM) that can be scalable without losing its qualities, and which can be used in any type of patient; afterwards, a finite element model was developed and a static analysis performed with suggested load cases to evaluate the sensitivity and naturalness of the prosthesis; and finally, a modal analysis was conducted. The results obtained in displacements and in distribution of stress for the load cases assessed are consistent with those of a real breast: there were smooth contours and there was natural mobility in the prosthesis designed by means of the biomimetic technique. Full article

(This article belongs to the Special Issue Biofabrication: From Additive Bio-Manufacturing to Bioprinting)

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10 pages, 4482 KiB

Open AccessArticle

Bloch-Surface-Polariton-Based Hybrid Nanowire Structure for Subwavelength, Low-Loss Waveguiding

by Weijing Kong¹, Yuhang Wan^2,*, Wenhui Zhao¹, Shuna Li³ and Zheng Zheng^2,4

¹ School of Electronic Engineering, Tianjin University of Technology and Education, 1310 Dagu South Rd., Tianjin 300222, China

² School of Electronic and Information Engineering, Beihang University, 37 Xueyuan Rd, Beijing 100191, China

³ National Key Laboratory for Electronic Measurement Technology, North University of China, 3 Xueyuan Rd., Shanxi, Taiyuan 030051, China

⁴ Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China

Appl. Sci. 2018, 8(3), 358; https://doi.org/10.3390/app8030358 - 1 Mar 2018

Cited by 8 | Viewed by 4049

Abstract

Surface plasmon polaritons (SPPs) have been thoroughly studied in the past decades for not only sensing but also waveguiding applications. Various plasmonic device structures have been explored due to their ability to confine their optical mode to the subwavelength level. However, with the [...] Read more.

Surface plasmon polaritons (SPPs) have been thoroughly studied in the past decades for not only sensing but also waveguiding applications. Various plasmonic device structures have been explored due to their ability to confine their optical mode to the subwavelength level. However, with the existence of metal, the large ohmic loss limits the propagation distance of the SPP and thus the scalability of such devices. Therefore, different hybrid waveguides have been proposed to overcome this shortcoming. Through fine tuning of the coupling between the SPP and a conventional waveguide mode, a hybrid mode could be excited with decent mode confinement and extended propagation distance. As an effective alternative of SPP, Bloch surface waves have been re-investigated more recently for their unique advantages. As is supported in all-dielectric structures, the optical loss for the Bloch surface wave is much lower, which stands for a much longer propagating distance. Yet, the confinement of the Bloch surface wave due to the reflections and refractions in the multilayer structure is not as tight as that of the SPP. In this work, by integrating a periodic multilayer structure that supports the Bloch surface wave with a metallic nanowire structure, a hybrid Bloch surface wave polariton could be excited. With the proposed hybrid nanowire structure, a hybrid mode is demonstrated with the deep subwavelength mode confinement and a propagation distance of tens of microns. Full article

(This article belongs to the Special Issue Surface Waves on Planar Photonic Crystals)

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13 pages, 7476 KiB

Open AccessArticle

Numerical Analysis to Improve the Ballistic Trajectory of an Air-Based Material Density Separator System

by Haider Ali¹

, Kyung Won Kim¹, Sung Gi Bang², Hyun Bae Chae², Seung Wook Shin² and Cheol Woo Park^1,*

¹ School of Mechanical Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Korea

² I-ENTEC Co. Ltd., 18-Gil 33, Seongseogongdanbukro, Dalseogu, Daegu 42712, Korea

Appl. Sci. 2018, 8(3), 359; https://doi.org/10.3390/app8030359 - 1 Mar 2018

Cited by 2 | Viewed by 3474

Abstract

A material density separator utilizes a high velocity channel of air with a ballistic trajectory to separate materials based on their different densities and sizes. Light materials are carried with the airflow, leaving behind the separated heavy materials. A vibrating bed is then [...] Read more.

A material density separator utilizes a high velocity channel of air with a ballistic trajectory to separate materials based on their different densities and sizes. Light materials are carried with the airflow, leaving behind the separated heavy materials. A vibrating bed is then used to collect both heavy and light plastic materials for further separation and recycling processes. The effectiveness of the separation process mainly depends on the ballistic trajectory of the air stream and the slanting position of the vibrating bed. In this study, flow characteristics inside the density separation system were investigated to optimize the ballistic trajectory of air and the slanting position of the vibrating bed to improve the separation process. Various inlet air velocities, duct shapes, and the slanting angles of the mechanical separators were used to study their effects on flow properties (velocity magnitude, pressure, shear stress, and vorticity). Results show that the ballistic trajectory of air strongly depends on the diameter and shape of the duct hole, the inclination angle of the vibrating bed, and the air inlet velocity. The selection of the suitable values of these parameters is necessary to improve the plastic separation process. Full article

(This article belongs to the Section Mechanical Engineering)

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11 pages, 301 KiB

Open AccessArticle

A Self-Consistent Physical Model of the Bubbles in a Gas Solid Two-Phase Flow

by Haiming Dong^1,*

, Jingfeng He², Chenlong Duan² and Yuemin Zhao^2,*

¹ School of Physical Science and Technology, China University of Mining and Technology, Xuzhou 221116, China

² Key Laboratory of Coal Processing and Efficient Utilization, Ministry of Education, China University of Mining and Technology, Xuzhou 221116, China

Appl. Sci. 2018, 8(3), 360; https://doi.org/10.3390/app8030360 - 2 Mar 2018

Viewed by 3893

Abstract

We develop a self-consistent physical model of bubbles in a gas solid two-phase flow. Using the Peng-Robonson state equation and a detailed specific heat ratio equation of bubbles, we obtain the kinetic equations of the bubbles on the basis of the Ergun equation, [...] Read more.

We develop a self-consistent physical model of bubbles in a gas solid two-phase flow. Using the Peng-Robonson state equation and a detailed specific heat ratio equation of bubbles, we obtain the kinetic equations of the bubbles on the basis of the Ergun equation, thermodynamic equations, and kinetic equations. It is found that the specific heat ratio of bubbles in such systems strongly depends on bubble pressures and temperatures, which play an important role in the characteristics of the bubbles. The theoretical studies show that with increasing height in the systems, the gas flow rate shows a downward trend. Moreover, the larger particles in the gas solid flows are, the greater the gas velocity is. The bubble sizes increase with the increasing heights of the gas solid systems, and then decrease. The bubble velocity is affected by the gas velocity and the bubble size, which gradually increase and eventually quasi-stabilize. This shows that gas and solid phases in a gas solid two-phase flow interact with each other and a self-consistent system comes into being. The theoretical results have exhibited important value as a guide for understanding the properties and effects of bubbles in gas solid two-phase flows. Full article

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

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19 pages, 7019 KiB

Open AccessArticle

An Experimental Study of a Data Compression Technology-Based Intelligent Data Acquisition (IDAQ) System for Structural Health Monitoring of a Long-Span Bridge

by Gwanghee Heo¹

, Chunggil Kim¹

, Seunggon Jeon²

and Joonryong Jeon^1,*

¹ Department of International Civil & Plant Engineering, Konyang University, Nonsan 32992, Korea

² Department of Civil Engineering, Chungnam National University, Daejeon 34134, Korea

Appl. Sci. 2018, 8(3), 361; https://doi.org/10.3390/app8030361 - 2 Mar 2018

Cited by 7 | Viewed by 3238

Abstract

There has recently been an increase in interest in structural health monitoring (SHM) using wireless sensor networks. For SHM, in particular, it is important to accurately and efficiently measure the dynamic acceleration response using wireless sensor networks in real-time. For the purpose, a [...] Read more.

There has recently been an increase in interest in structural health monitoring (SHM) using wireless sensor networks. For SHM, in particular, it is important to accurately and efficiently measure the dynamic acceleration response using wireless sensor networks in real-time. For the purpose, a CAFB (cochlea-inspired artificial filter bank) has been developed in a previous study, which is a dynamic data compression technology. Since the developed CAFB can select and compress only the interested range of frequency signals from an entire response of a structure, it efficiently provides a real-time dynamic response based on wireless networking. CAFB of the previous study is optimized to selectively acquire low-frequency signals of sub-10 Hz, which is required for SHM of long and large-scale structures. According to the CAFB’s optimization using an El-Centro seismic waveform, six band-pass filters, 1.0 Hz interval, and 0.6 Hz bandwidth have been adapted. This article is to evaluate dynamic acceleration response performance of civil structures using the CAFB developed in the previous study. To achieve the purpose, the optimally-designed CAFB was embedded in an intelligent data acquisition (IDAQ) system. To evaluate the performance of the IDAQ system with the embedded CAFB, the real-time dynamic response was investigated for a model cable-stayed bridge, measured by a wire-measuring system and the CAFB-based IDAQ system simultaneously. The results show excellent agreement between the compressed dynamic response acquired by the CAFB-based IDAQ system and that acquired by the wire measuring system. In addition, the measurement from the CAFB-based IDAQ system revealed the modal information of the model bridge. The developed CAFB can determine and reconstruct the entire dynamic response from compression with modal information only; its efficient operation illustrates its potential to be utilized in real-time structural health monitoring. Full article

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

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17 pages, 2136 KiB

Open AccessArticle

Preventive Effects of Lactobacillus Plantarum YS4 on Constipation Induced by Activated Carbon in Mice

by Yu Qian^{1,2,3,4,5,†}, Jia-Le Song^6,†, Ruokun Yi^2,3,4,5, Guijie Li^2,3,4,5, Peng Sun^2,3,4,5, Xin Zhao^2,3,4,5,*

and Guicheng Huo^1,*

¹ Key Laboratory of Dairy Science, Ministry of Education, College of Food Science, Northeast Agricultural University, Harbin 150030, China

² Chongqing Collaborative Innovation Center for Functional Food, Chongqing University of Education, Chongqing 400067, China

³ Chongqing Engineering Research Center of Functional Food, Chongqing University of Education, Chongqing 400067, China

⁴ Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing 400067, China

⁵ College of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China

⁶ Department of Nutrition and Food Hygiene, School of Public Health, Guilin Medical University, Guilin 541004, China

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(3), 363; https://doi.org/10.3390/app8030363 - 2 Mar 2018

Cited by 27 | Viewed by 4845

Abstract

This study was designed to analyze the effects of Lactobacillus plantarum YS4 (LP-YS4) on activated carbon-induced constipation in ICR (Institute of Cancer Research) mice. The mice were fed on YS4 and LB (Lactobacillus bulgaricus), followed by inducing constipation. The results of [...] Read more.

This study was designed to analyze the effects of Lactobacillus plantarum YS4 (LP-YS4) on activated carbon-induced constipation in ICR (Institute of Cancer Research) mice. The mice were fed on YS4 and LB (Lactobacillus bulgaricus), followed by inducing constipation. The results of the experiment suggested that anti-gastric acid and bile salt activities of LP-YS4 were more effective than LB. It was conclusive that LP-YS4 could inhibit the weight loss induced by constipation and had an effect on fecal weight, particle number and further decrease in water content initiated by constipation. At the same time, LP-YS4 could increase gastrointestinal (GI) transit rate and limit the time of the first black stool defecation. It could also raise the motilin (MTL), endothelin (ET), acetylcholinesterase (AChE), substance P (SP), and vasoactive intestinal peptide (VIP) serum levels and reduce the somatostatin (SS) level in constipated mice as compared to the mice in control group. LP-YS4 could reduce myeloperoxidase (MPO), nitric oxide (NO), and malondialdehyde (MDA) levels in small intestinal tissue of mice and raise glutathione (GSH) levels as compared to the control group mice. By H&E (hematoxylin-eosin) assay, we determined that LP-YS4 could reduce the small intestinal tissue injury by activated carbon. Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) experiment data demonstrated that LP-YS4 has the capability to increase c-Kit, stem cell factor (SCF), glial cellline-derived neurotrophic factor (GDNF) mRNA (messenger RNA) expressions and decrease transient receptor potential vanilloid 1 (TRPV1), nitric oxide synthase (NOS) expressions in small intestine tissue of constipated mice. High concentration of LP-YS4 exhibited much better effects than that of LB. From these results, LP-YS4 could be considered as an effective substance that actively inhibits constipation. Full article

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

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20 pages, 3889 KiB

Open AccessArticle

Analysis of Mechanical Properties of Self Compacted Concrete by Partial Replacement of Cement with Industrial Wastes under Elevated Temperature

by Junaid Mansoor¹, Syyed Adnan Raheel Shah^1,2,*, Mudasser Muneer Khan³, Abdullah Naveed Sadiq¹, Muhammad Kashif Anwar¹, Muhammad Usman Siddiq¹ and Hassam Ahmad¹

¹ Department of Civil Engineering, Pakistan Institute of Engineering and Technology, Multan 66000, Pakistan

² Instituut Voor Mobiliteit, Hasselt University, Wetenschapspark 5 Bus 6, 3590 Diepenbeek, Belgium

³ Department of Civil Engineering, University College of Engineering & Technology, Bahauddin Zakariya University, Multan 66000, Pakistan

Appl. Sci. 2018, 8(3), 364; https://doi.org/10.3390/app8030364 - 7 Mar 2018

Cited by 34 | Viewed by 6558

Abstract

Self-Compacting Concrete (SCC) differs from the normal concrete as it has the basic capacity to consolidate under its own weight. The increased awareness regarding environmental disturbances and its hazardous effects caused by blasting and crushing procedures of stone, it becomes a delicate and [...] Read more.

Self-Compacting Concrete (SCC) differs from the normal concrete as it has the basic capacity to consolidate under its own weight. The increased awareness regarding environmental disturbances and its hazardous effects caused by blasting and crushing procedures of stone, it becomes a delicate and obvious issue for construction industry to develop an alternative remedy as material which can reduce the environmental hazards and enable high-performance strength to the concrete, which would make it durable and efficient for work. A growing trend is being established all over the world to use industrial byproducts and domestic wastes as a useful raw material in construction, as it provides an eco-friendly edge to the construction process and especially for concrete. This study aims to enlighten the use and comparative analysis for the performance of concrete with added industrial byproducts such as Ground Granulated Blast Furnace Slag (GGBFS), Silica fumes (SF) and Marble Powder (MP) in the preparation of SCC. This paper deals with the prediction of mechanical properties (i.e., compressive, tensile and flexural Strength) of self-compacting concrete by considering four major factors such as type of additive, percentage additive replaced, curing days and temperature using Artificial Neural Networks (ANNs). Full article

(This article belongs to the Special Issue Soft Computing Techniques in Structural Engineering and Materials)

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12 pages, 2499 KiB

Open AccessArticle

Influence of Size Reduction of Fly Ash Particles by Grinding on the Chemical Properties of Geopolymers

by Carlos Antonio Rosas-Casarez¹

, Susana Paola Arredondo-Rea^1,*

, Adriana Cruz-Enríquez¹, Ramón Corral-Higuera¹

, Manuel De Jesús Pellegrini-Cervantes¹, José Manuel Gómez-Soberón²

and Teresita De Jesús Medina-Serna¹

¹ Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., Los Mochis, Sinaloa CP 81223, Mexico

² Escuela Politécnica Superior de Edificación de Barcelona, Universidad Politécnica de Cataluña, Av. Doctor Marañón 44-50, 08028 Barcelona, Spain

Appl. Sci. 2018, 8(3), 365; https://doi.org/10.3390/app8030365 - 4 Mar 2018

Cited by 24 | Viewed by 4385

Abstract

Chemical properties of geopolymers were evaluated from the reduction of fly ash particle size by grinding. X-ray diffraction determined that at early curing ages new crystalline phases appear in the matrix of the geopolymer and they remain for 28 days, with increases in [...] Read more.

Chemical properties of geopolymers were evaluated from the reduction of fly ash particle size by grinding. X-ray diffraction determined that at early curing ages new crystalline phases appear in the matrix of the geopolymer and they remain for 28 days, with increases in intensities up to 60%. In Fourier transform infrared spectroscopy, displacements were identified in the main band of the geopolymers at higher wavenumbers, attributed to the greater rigidity in the structures of the aluminosilicate gel due to the increase of the reaction products in the geopolymers obtained through fly ashsubjected to previous grinding, which is observable in the geopolymers matrix. Results indicate that the reduction of fly ash particle size by grinding has an influence on the chemical properties of geopolymers. Full article

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

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8 pages, 1868 KiB

Open AccessArticle

Polyimide Encapsulation of Spider-Inspired Crack-Based Sensors for Durability Improvement

by Taewi Kim^1,†, Taemin Lee^2,3,†, Gunhee Lee^2,3,†, Yong Whan Choi^2,3,†, Sang Moon Kim⁴, Daeshik Kang^1,*

and Mansoo Choi^2,3,*

¹ Department of Mechanical Engineering, Ajou University, San 5, Woncheon-Dong, Yeongtong-Gu, Suwon 443-749, Korea

² Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Korea

³ Global Frontier Center for Multiscale Energy Systems, Seoul National University, Seoul 151-742, Korea

⁴ Department of Mechanical Engineering, Incheon National University, Incheon 406-772, Korea

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(3), 367; https://doi.org/10.3390/app8030367 - 3 Mar 2018

Cited by 52 | Viewed by 9181

Abstract

In mechanical sensory systems, encapsulation is one of the crucial issues to take care of when it comes to protection of the systems from external damage. Recently, a new type of a mechanical strain sensor inspired by spider’s slit organ has been reported, [...] Read more.

In mechanical sensory systems, encapsulation is one of the crucial issues to take care of when it comes to protection of the systems from external damage. Recently, a new type of a mechanical strain sensor inspired by spider’s slit organ has been reported, which has incredibly high sensitivity, flexibility, wearability, and multifunctional sensing abilities. In spite of many of these advantages, the sensor is still vulnerable in harsh environments of liquids and/or high temperature, because it has heat-vulnerable polyethylene terephthalate (PET) substrate without any encapsulation layer. Here, we present a mechanical crack-based strain sensor with heat, water and saline solution resistance by alternating the substrate from polyester film to polyimide film and encapsulating the sensor with polyimide. We have demonstrated the ability of the encapsulated crack-based sensor against heat, water, saline solution damage through experiments. Our sensor exhibited reproducibility and durability with high sensitivity to strain (gauge factor above 10,000 at strain of two percent). These results show a new potential of the crack-based sensory system to be used as a wearable voice/motion/pulse sensing device and a high-temperature strain sensor. Full article

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12 pages, 1954 KiB

Open AccessArticle

Quillaja saponaria Saponins with Potential to Enhance the Effectiveness of Disinfection Processes in the Beverage Industry

by Hubert Antolak^1,*, Urszula Mizerska², Joanna Berłowska¹

, Anna Otlewska¹ and Dorota Kręgiel¹

¹ Institute of Fermentation Technology and Microbiology, Faculty of Biotechnology and Food Science, Lodz University of Technology, 171/173 Wolczanska, 90-924 Lodz, Poland

² Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland

Appl. Sci. 2018, 8(3), 368; https://doi.org/10.3390/app8030368 - 3 Mar 2018

Cited by 13 | Viewed by 5044

Abstract

This study examines the in vitro effect of Quillaja saponaria extracts on Asaia spp. planktonic cells and biofilms, in comparison and combination with two disinfectants: peracetic acid and N-ethyl-N,N-dimethylhexadecylammonium bromide. The growth of six bacterial strains was evaluated [...] Read more.

This study examines the in vitro effect of Quillaja saponaria extracts on Asaia spp. planktonic cells and biofilms, in comparison and combination with two disinfectants: peracetic acid and N-ethyl-N,N-dimethylhexadecylammonium bromide. The growth of six bacterial strains was evaluated spectrophotometrically. Biofilm eradication was determined using the plate count method and luminometry. The planktonic cells were characterized by relatively high resistance to peracetic acid and higher sensitivity to N-ethylo-N,N-dimethylohexadecylioamonium bromide. In almost all the tested strains, growth was inhibited by 0.125% (v/v) peracetic acid and 0.0313% (w/v) quaternary ammonium compound. However, combinations of cell pretreatment using saponin and peracetic acid action were the most efficient against both planktonic and biofilm cells. The minimum inhibitory concentrations for peracetic acid were 4–8 times lower than those for bacterial strains without preliminary saponin action. Eradication of Asaia spp. biofilms reduced the number of living cells by 4–5 logarithmic units. These results demonstrate the synergetic action of saponin extract and disinfectant, and could be useful in the development of industrial strategies against Asaia spp. biofilms. Full article

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

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19 pages, 3423 KiB

Open AccessArticle

Finger Angle-Based Hand Gesture Recognition for Smart Infrastructure Using Wearable Wrist-Worn Camera

by Feiyu Chen¹, Jia Deng¹, Zhibo Pang²

, Majid Baghaei Nejad³, Huayong Yang¹ and Geng Yang^1,*

¹ State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China

² ABB Corporate Research Sweden, Vasteras 72178, Sweden

³ Electrical Engineering Department, Hakim Sabzevari University, Sabzevar 9617976487, Iran

Appl. Sci. 2018, 8(3), 369; https://doi.org/10.3390/app8030369 - 3 Mar 2018

Cited by 40 | Viewed by 16861

Abstract

The arising of domestic robots in smart infrastructure has raised demands for intuitive and natural interaction between humans and robots. To address this problem, a wearable wrist-worn camera (WwwCam) is proposed in this paper. With the capability of recognizing human hand gestures in [...] Read more.

The arising of domestic robots in smart infrastructure has raised demands for intuitive and natural interaction between humans and robots. To address this problem, a wearable wrist-worn camera (WwwCam) is proposed in this paper. With the capability of recognizing human hand gestures in real-time, it enables services such as controlling mopping robots, mobile manipulators, or appliances in smart-home scenarios. The recognition is based on finger segmentation and template matching. Distance transformation algorithm is adopted and adapted to robustly segment fingers from the hand. Based on fingers’ angles relative to the wrist, a finger angle prediction algorithm and a template matching metric are proposed. All possible gesture types of the captured image are first predicted, and then evaluated and compared to the template image to achieve the classification. Unlike other template matching methods relying highly on large training set, this scheme possesses high flexibility since it requires only one image as the template, and can classify gestures formed by different combinations of fingers. In the experiment, it successfully recognized ten finger gestures from number zero to nine defined by American Sign Language with an accuracy up to 99.38%. Its performance was further demonstrated by manipulating a robot arm using the implemented algorithms and WwwCam to transport and pile up wooden building blocks. Full article

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

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31 pages, 21768 KiB

Open AccessArticle

Wireless Sensors and IoT Platform for Intelligent HVAC Control

by António Ruano^1,2,*

, Sérgio Silva³, Helder Duarte¹ and P.M. Ferreira⁴

¹ Faculty of Science and Technology, University of Algarve, 8005-139 Faro, Portugal

² IDMEC, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal

³ EasySensing—Intelligent Systems, Centro Empresarial de Gambelas, University of Algarve, 8005-139 Faro, Portugal

⁴ LaSIGE, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal

Appl. Sci. 2018, 8(3), 370; https://doi.org/10.3390/app8030370 - 3 Mar 2018

Cited by 36 | Viewed by 9123

Abstract

Energy consumption of buildings (residential and non-residential) represents approximately 40% of total world electricity consumption, with half of this energy consumed by HVAC systems. Model-Based Predictive Control (MBPC) is perhaps the technique most often proposed for HVAC control, since it offers an enormous [...] Read more.

Energy consumption of buildings (residential and non-residential) represents approximately 40% of total world electricity consumption, with half of this energy consumed by HVAC systems. Model-Based Predictive Control (MBPC) is perhaps the technique most often proposed for HVAC control, since it offers an enormous potential for energy savings. Despite the large number of papers on this topic during the last few years, there are only a few reported applications of the use of MBPC for existing buildings, under normal occupancy conditions and, to the best of our knowledge, no commercial solution yet. A marketable solution has been recently presented by the authors, coined the IMBPC HVAC system. This paper describes the design, prototyping and validation of two components of this integrated system, the Self-Powered Wireless Sensors and the IOT platform developed. Results for the use of IMBPC in a real building under normal occupation demonstrate savings in the electricity bill while maintaining thermal comfort during the whole occupation schedule. Full article

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

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12 pages, 7250 KiB

Open AccessArticle

Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

by Ben Lane^1,2,3,*, Paul Sherratt¹

, Xiao Hu² and Andy Harland¹

¹ Sports Technology Institute, Loughborough University, Loughborough LE11 3TU, UK

² School of Materials Science & Engineering, Nanyang Technological University, Singapore 637551, Singapore

³ Institute for Sports Research, Nanyang Technological University, Singapore 637551, Singapore

Appl. Sci. 2018, 8(3), 371; https://doi.org/10.3390/app8030371 - 4 Mar 2018

Cited by 6 | Viewed by 6283

Abstract

The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and [...] Read more.

The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional). The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s⁻¹ in tension and to a maximum strain of −0.4 and a maximum rate of −800 s⁻¹ in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models. Full article

(This article belongs to the Special Issue Sports Materials)

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15 pages, 10876 KiB

Open AccessArticle

Effects of Heat Treatment on the Tribological Properties of Sicp/Al-5Si-1Cu-0.5Mg Composite Processed by Electromagnetic Stirring Method

by Ning Li^1,2, Hong Yan^1,* and Zhi-Wei Wang¹

¹ School of Mechanical Electrical Engineering, Nanchang University, Nanchang 330031, China

² School of Aviation Manufacturing Engineering, Nanchang Hangkong University, Nanchang 330069, China

Appl. Sci. 2018, 8(3), 372; https://doi.org/10.3390/app8030372 - 4 Mar 2018

Cited by 13 | Viewed by 4003

Abstract

This paper investigated the influence of heat treatment (T6) on the dry sliding wear behavior of SiCp/Al-5Si-1Cu-0.5Mg composite that was fabricated by electromagnetic stirring method. The wear rates and friction coefficients were measured using a pin-on-disc tribometer under loads of 15–90 N at [...] Read more.

This paper investigated the influence of heat treatment (T6) on the dry sliding wear behavior of SiCp/Al-5Si-1Cu-0.5Mg composite that was fabricated by electromagnetic stirring method. The wear rates and friction coefficients were measured using a pin-on-disc tribometer under loads of 15–90 N at dry sliding speeds of 100 r/min, 200 r/min, and 300 r/min, over a sliding time of 15 min. The worn surfaces and debris were examined using a scanning electron microscope and was analyzed with an energy dispersive spectrometer. The experimental results revealed that SiCp/Al-5Si-1Cu-0.5Mg alloy treated with T6 exhibited lower wear rate and friction coefficient than the other investigated alloys. As the applied load increased, the wear rate and friction coefficient increased. While, the wear rate and friction coefficient decreased with the sliding speed increasing. The morphology of the eutectic silicon was spheroidal after the T6 heat treatment. SiCp particles and Al₂Cu phase can be considered as the main raisons for improving the wear behavior. Abrasion and oxidation were the wear mechanisms at low load levels. However, the wear mechanisms at high load levels were plastic deformation and delamination. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Aluminium Alloys)

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20 pages, 952 KiB

Open AccessArticle

Hybrid Genetic Algorithm Fuzzy-Based Control Schemes for Small Power System with High-Penetration Wind Farms

by Mohammed Elsayed Lotfy^1,2,*

, Tomonobu Senjyu²

, Mohammed Abdel-Fattah Farahat¹, Amal Farouq Abdel-Gawad¹, Liu Lei² and Manoj Datta³

¹ Department of Electrical Power and Machines, Zagazig University, Zagazig 44519, Egypt

² Department of Electrical and Electronics Engineering, University of the Ryukyus, Okinawa 903-0213, Japan

³ Department of Electrical and Biomedical Engineering, RMIT University, Melbourne, Victoria 3001, Australia

Appl. Sci. 2018, 8(3), 373; https://doi.org/10.3390/app8030373 - 4 Mar 2018

Cited by 30 | Viewed by 5212

Abstract

Wind is a clean, abundant, and inexhaustible source of energy. However, wind power is not constant, as windmill output is proportional to the cube of wind speed. As a result, the generated power of wind turbine generators (WTGs) fluctuates significantly. Power fluctuation leads [...] Read more.

Wind is a clean, abundant, and inexhaustible source of energy. However, wind power is not constant, as windmill output is proportional to the cube of wind speed. As a result, the generated power of wind turbine generators (WTGs) fluctuates significantly. Power fluctuation leads to frequency deviation and voltage flicker inside the system. This paper presents a new methodology for controlling system frequency and power. Two decentralized fuzzy logic-based control schemes with a high-penetration non-storage wind–diesel system are studied. First, one is implemented in the governor of conventional generators to damp frequency oscillation, while the other is applied to control the pitch angle system of wind turbines to smooth wind output power fluctuations and enhance the power system performance. A genetic algorithm (GA) is employed to tune and optimize the membership function parameters of the fuzzy logic controllers to obtain optimal performance. The effectiveness of the suggested controllers is validated by time domain simulation for the standard IEEE nine-bus three-generator test system, including three wind farms. The robustness of the power system is checked under normal and faulty operating conditions. Full article

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

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12 pages, 2656 KiB

Open AccessArticle

Symmetry-Breaking Effect on the Electromagnetic Properties of Plasmonic Trimers Composed of Graphene Nanodisks

by Weibin Qiu^1,*

, Houbo Chen¹, Junbo Ren¹

, Pingping Qiu¹, Zhili Lin¹, Jiaxian Wang¹, Qiang Kan^2,3 and Jiaoqing Pan^2,3

¹ Fujian Provincial Key Laboratory of Light Propagation and Transformation, College of Information Science and Engineering, Huaqiao University, Xiamen 361021, China

² College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100083, China

³ Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083, China

Appl. Sci. 2018, 8(3), 374; https://doi.org/10.3390/app8030374 - 5 Mar 2018

Cited by 3 | Viewed by 4124

Abstract

Plasmonic trimers composed of equal-sized graphene nanodisks are proposed in this paper. The symmetry-breaking effect on the electromagnetic properties of the nanostructure is numerically investigated by studying plasmon energy diagrams and optical scattering spectra in mid-infrared range with a gradient vertex angle. The [...] Read more.

Plasmonic trimers composed of equal-sized graphene nanodisks are proposed in this paper. The symmetry-breaking effect on the electromagnetic properties of the nanostructure is numerically investigated by studying plasmon energy diagrams and optical scattering spectra in mid-infrared range with a gradient vertex angle. The degenerate plasmonic modes are lifted and new modes appear with increased vertex angle. The energy diagrams are consistent with scattering extinction spectra, about which the dipole moment distribution of the proposed structure is discussed to demonstrate the coupling strength of the collective plasmonic modes of the trimer. More specifically, the frequency tunability of the plasmonic trimer is pointed out by modifying the chemical potential of the graphene nanodisks without varying the geometric configuration. The proposed structure might find applications such as light-matter interaction, single molecule detection, and high-sensitivity chemical sensing. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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14 pages, 5368 KiB

Open AccessArticle

Effects of Shot-Peening and Stress Ratio on the Fatigue Crack Propagation of AL 7475-T7351 Specimens

by Natália Ferreira¹, Pedro V. Antunes^1,*

, José A. M. Ferreira¹

, José D. M. Costa¹ and Carlos Capela^1,2

¹ Department of Mechanical Engineering, Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), University of Coimbra, Rua Luís Reis Santos, Coimbra 3030-788, Portugal

² Department of Mechanical Engineering, Instituto Politécnico de Leiria, ESTG, Morro do Lena—Alto Vieiro, Leiria 2400-901, Portugal

Appl. Sci. 2018, 8(3), 375; https://doi.org/10.3390/app8030375 - 5 Mar 2018

Cited by 13 | Viewed by 5752

Abstract

Shot peening is an attractive technique for fatigue enhanced performance of metallic components, because it increases fatigue crack initiation life prevention and retards early crack growth. Engineering design based on fatigue crack propagation predictions applying the principles of fracture mechanics is commonly used [...] Read more.

Shot peening is an attractive technique for fatigue enhanced performance of metallic components, because it increases fatigue crack initiation life prevention and retards early crack growth. Engineering design based on fatigue crack propagation predictions applying the principles of fracture mechanics is commonly used in aluminum structures for aerospace engineering. The main purpose of present work was to analyze the effect of shot peening on the fatigue crack propagation of the 7475 aluminum alloy, under both constant amplitude loading and periodical overload blocks. The tests were performed on 4 and 8 mm thickness specimens with stress ratios of 0.05 and 0.4. The analysis of the shot-peened surface showed a small increase of the micro-hardness values due to the plastic deformations imposed by shot peening. The surface peening beneficial effect on fatigue crack growth is very limited; its main effect is more noticeable near the threshold. The specimen’s thickness only has marginal influence on the crack propagation, in opposite to the stress ratio. Periodic overload blocks of 300 cycles promotes a reduction of the fatigue crack growth rate for both intervals of 7500 and 15,000 cycles. Full article

(This article belongs to the Special Issue Mechanical Behaviour of Aluminium Alloys)

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13 pages, 5180 KiB

Open AccessArticle

The Improvement of Mechanical Properties, Thermal Stability, and Water Absorption Resistance of an Eco-Friendly PLA/Kenaf Biocomposite Using Acetylation

by Taek-Jun Chung^1,†, Ji-Won Park^2,3,†

, Hyun-Ji Lee², Hueck-Jin Kwon², Hyun-Joong Kim^2,3,*, Young-Kyu Lee⁴

and William Tai Yin Tze⁵

¹ LG Chemistry, 188, Munji-ro, Yuseong-gu, Daejeon 34122, Korea

² Laboratory of Adhesion & Bio-Composites, Program in Environmental Materials Science, College of Agriculture and Life-Science, Seoul National University Seoul, Seoul 08826, Korea

³ Research Institute for Agriculture & Life Sciences, Seoul National University, Seoul 08826, Korea

⁴ Indoor Air Quality Analysis Center, National Instrumentation Center for Environmental Management, Seoul National University, Seoul 08826, Korea

⁵ Department of Bioproducts & Biosystems Engineering, University of Minnesota, Saint Paul, MN 55108-6130, USA

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(3), 376; https://doi.org/10.3390/app8030376 - 5 Mar 2018

Cited by 93 | Viewed by 6956

Abstract

As a result of industrialization and environmental pollution, increasing importance is being given to eco-friendly materials and technology. In particular, eco-friendly biocomposites using polylactic acid (PLA) have attracted great interest. In this work, fiber-reinforced composites were investigated in order to enhance the mechanical [...] Read more.

As a result of industrialization and environmental pollution, increasing importance is being given to eco-friendly materials and technology. In particular, eco-friendly biocomposites using polylactic acid (PLA) have attracted great interest. In this work, fiber-reinforced composites were investigated in order to enhance the mechanical properties and improve the economic efficiency of PLA. Specifically, composite materials using natural fibers, such as kenaf were actively studied. In the utilization of natural fibers, such as kenaf, the treatment method for increasing the bonding force between the fiber and the matrix is very important. In this study, the surface of kenaf was treated using an acetylation technique, and the PLA composite material was prepared using surface-treated kenaf. Changes in fiber properties were observed with acetylation treatment time. The mechanical properties, thermal stability, and water absorption resistance of the acetylated kenaf and PLA composites prepared for each condition were evaluated. Finally, was concluded that acetylation treatment is effective for improving the performance of PLA/kenaf composites. This behavior was found to relate to the surface cleaning of acetylated kanaf, in addition to the efficient modification of the hydrophilic characteristics of kenaf. Full article

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

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15 pages, 3688 KiB

Open AccessArticle

Aesthetics and Survival of Immediately Restored Implants in Partially Edentulous Anterior Maxillary Patients

by Roni Kolerman^1,*, Haim Tal¹, Jose Luis Calvo Guirado²

, Eitan Barnea³, Liat Chaushu¹

, Manar Abu Wasel⁴ and Joseph Nissan⁵

¹ Department of Periodontology and Dental Implantology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Tel Aviv 69978, Israel

² Oral Surgery and Implant Dentistry, Universidad Católica San Antonio de Murcia (UCAM), 30107 Murcia, Spain

³ Specialist in Oral Rehabilitation, Private Practice Tel-Aviv, Tel-Aviv 69978, Israel

⁴ The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Tel Aviv 69978, Israel

⁵ Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Tel Aviv 69978, Israel

Appl. Sci. 2018, 8(3), 377; https://doi.org/10.3390/app8030377 - 5 Mar 2018

Cited by 9 | Viewed by 4189

Abstract

This retrospective study was undertaken to determine survival rates and aesthetic outcomes of immediate placement of multiple implants at anterior maxilla sites. One hundred and eighteen implants placed in 39 patients (21 women and 18 men; average age 58.3 years) were immediately restored [...] Read more.

This retrospective study was undertaken to determine survival rates and aesthetic outcomes of immediate placement of multiple implants at anterior maxilla sites. One hundred and eighteen implants placed in 39 patients (21 women and 18 men; average age 58.3 years) were immediately restored (24–72 h after placement). Aesthetic assessment, radiographic bone loss, and biological and prosthetic complications were evaluated. Data collection between 12 and 84 months (mean 32.2 ± 18) after final prosthetic installation revealed that no implants were lost, and that 106/118 (89.8%) implants had no more than 1.5 mm of bone loss by the end of the first year and an additional 0.2 mm for each successive year. The marginal bone loss was higher for extractions due to periodontitis compared to extractions due to caries (mean mesial loss of 1.37 mm vs. 1.01 mm, respectively, and mean distal loss of 1.37 mm and 0.99 mm, respectively, p = 0.001). The mesial papilla was present in 83/118 implants (70.3%), while the distal papilla was present in 76/118 implants (64.4%). The cervical metallic part of the abutment was exposed in 16/118 (13.5%) implants. There was a higher ratio of recessions and missing papillae in patients in whom the extractions were performed due to periodontal reasons. Within the limitations of the present study, aesthetic and radiographic parameters support immediate restoration of partially edentulous maxillae. Full article

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10 pages, 2018 KiB

Open AccessArticle

Improving the Electrochemical Performance of LiNi_0.80Co_0.15Al_0.05O₂ in Lithium Ion Batteries by LiAlO₂ Surface Modification

by Chunhua Song

, Wenge Wang, Huili Peng, Ying Wang^*, Chenglong Zhao^*, Huibin Zhang, Qiwei Tang, Jinzhao Lv, Xianjun Du and Yanmeng Dou

Shandong YuHuang New Energy Technology Co. Ltd., Heze 274000, China

Appl. Sci. 2018, 8(3), 378; https://doi.org/10.3390/app8030378 - 5 Mar 2018

Cited by 49 | Viewed by 7112

Abstract

LiNi_0.80Co_0.15Al_0.05O₂ (NCA) as a lithium ion battery cathode material has received attention for its highly specific capacity and excellent low temperature performance. However, the disadvantages of its high surface lithium compound residues and high pH value [...] Read more.

LiNi_0.80Co_0.15Al_0.05O₂ (NCA) as a lithium ion battery cathode material has received attention for its highly specific capacity and excellent low temperature performance. However, the disadvantages of its high surface lithium compound residues and high pH value have influenced its processing performance and limited its application. This paper uses a facile method to modify NCA through LiAlO₂ coating. The results showed that when the molar ratio of Al(NO₃)₃·9H₂O and lithium compound residues at the surface of NCA cathode material was 0.25:1, the pH of the cathode material decreased from 12.70 to 11.80 and the surface lithium compound residues decreased from 3.99% to 1.48%. The NCA cell was charged and discharged for 100 cycles at 1 C in the voltage range of 3.0–4.3 V, to test the capacity retention of NCA. It was found to be as high as 94.67%, which was 5.36% higher than the control NCA cell. The discharge capacity of NCA-0.25-500 °C was 139.8 mAh/g even at 8 C rate, which was 15% higher than the raw NCA. Further research indicated that Al(NO₃)₃·9H₂O reacted with the surface lithium compound residues of NCA and generated LiAlO₂, which improved the NCA electrochemical performance. Full article

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

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39 pages, 1292 KiB

Open AccessArticle

State-of-the-Art Mobile Intelligence: Enabling Robots to Move Like Humans by Estimating Mobility with Artificial Intelligence

by Xue-Bo Jin^1,2,*

, Ting-Li Su^1,2, Jian-Lei Kong^1,2, Yu-Ting Bai³, Bei-Bei Miao⁴ and Chao Dou⁵

¹ School of Computer and Information Engineering, Beijing Technology and Business University, Beijing 100048, China

² Beijing Key Laboratory of Big Data Technology for Food Safety, Beijing Technology and Business University, Beijing 100048, China

³ School of Automation, Beijing Institute of Technology, Beijing 100081, China

⁴ Baidu, Inc., Beijing 100085, China

⁵ Center of Quality Engineering AVIC China Aero-Polytechnology Establishment, Beijing 100028, China

Appl. Sci. 2018, 8(3), 379; https://doi.org/10.3390/app8030379 - 5 Mar 2018

Cited by 41 | Viewed by 17124

Abstract

Mobility is a significant robotic task. It is the most important function when robotics is applied to domains such as autonomous cars, home service robots, and autonomous underwater vehicles. Despite extensive research on this topic, robots still suffer from difficulties when moving in [...] Read more.

Mobility is a significant robotic task. It is the most important function when robotics is applied to domains such as autonomous cars, home service robots, and autonomous underwater vehicles. Despite extensive research on this topic, robots still suffer from difficulties when moving in complex environments, especially in practical applications. Therefore, the ability to have enough intelligence while moving is a key issue for the success of robots. Researchers have proposed a variety of methods and algorithms, including navigation and tracking. To help readers swiftly understand the recent advances in methodology and algorithms for robot movement, we present this survey, which provides a detailed review of the existing methods of navigation and tracking. In particular, this survey features a relation-based architecture that enables readers to easily grasp the key points of mobile intelligence. We first outline the key problems in robot systems and point out the relationship among robotics, navigation, and tracking. We then illustrate navigation using different sensors and the fusion methods and detail the state estimation and tracking models for target maneuvering. Finally, we address several issues of deep learning as well as the mobile intelligence of robots as suggested future research topics. The contributions of this survey are threefold. First, we review the literature of navigation according to the applied sensors and fusion method. Second, we detail the models for target maneuvering and the existing tracking based on estimation, such as the Kalman filter and its series developed form, according to their model-construction mechanisms: linear, nonlinear, and non-Gaussian white noise. Third, we illustrate the artificial intelligence approach—especially deep learning methods—and discuss its combination with the estimation method. Full article

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19 pages, 6522 KiB

Open AccessArticle

Enhancing the Accuracy of Advanced High Temperature Mechanical Testing through Thermography

by Jonathan Jones

Institute of Structural Materials, Swansea University, Singleton Park, Sketty, Swansea SA2 8PP, UK

Appl. Sci. 2018, 8(3), 380; https://doi.org/10.3390/app8030380 - 6 Mar 2018

Cited by 17 | Viewed by 5852

Abstract

This paper describes the advantages and enhanced accuracy thermography provides to high temperature mechanical testing. This technique is not only used to monitor, but also to control test specimen temperatures where the infra-red technique enables accurate non-invasive control of rapid thermal cycling for [...] Read more.

This paper describes the advantages and enhanced accuracy thermography provides to high temperature mechanical testing. This technique is not only used to monitor, but also to control test specimen temperatures where the infra-red technique enables accurate non-invasive control of rapid thermal cycling for non-metallic materials. Isothermal and dynamic waveforms are employed over a 200–800 °C temperature range to pre-oxidised and coated specimens to assess the capability of the technique. This application shows thermography to be accurate to within ±2 °C of thermocouples, a standardised measurement technique. This work demonstrates the superior visibility of test temperatures previously unobtainable by conventional thermocouples or even more modern pyrometers that thermography can deliver. As a result, the speed and accuracy of thermal profiling, thermal gradient measurements and cold/hot spot identification using the technique has increased significantly to the point where temperature can now be controlled by averaging over a specified area. The increased visibility of specimen temperatures has revealed additional unknown effects such as thermocouple shadowing, preferential crack tip heating within an induction coil, and, fundamental response time of individual measurement techniques which are investigated further. Full article

(This article belongs to the Special Issue Novel Ideas for Infrared Thermography also Applied in Integrated Approaches)

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24 pages, 12079 KiB

Open AccessArticle

Noncontact Surface Roughness Estimation Using 2D Complex Wavelet Enhanced ResNet for Intelligent Evaluation of Milled Metal Surface Quality

by Weifang Sun¹, Bin Yao^1,2, Binqiang Chen^1,2,*

, Yuchao He^1,3, Xincheng Cao¹, Tianxiang Zhou⁴ and Huigang Liu¹

¹ School of Aerospace Engineering, Xiamen University, Xiamen 361005, China

² Shenzhen Research Institute of Xiamen University, Shenzhen 518000, China

³ Cross-strait Tsinghua Research Institute, Beijing 100084, China

⁴ School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China

Appl. Sci. 2018, 8(3), 381; https://doi.org/10.3390/app8030381 - 6 Mar 2018

Cited by 47 | Viewed by 6099

Abstract

Machined surfaces are rough from a microscopic perspective no matter how finely they are finished. Surface roughness is an important factor to consider during production quality control. Using modern techniques, surface roughness measurements are beneficial for improving machining quality. With optical imaging of [...] Read more.

Machined surfaces are rough from a microscopic perspective no matter how finely they are finished. Surface roughness is an important factor to consider during production quality control. Using modern techniques, surface roughness measurements are beneficial for improving machining quality. With optical imaging of machined surfaces as input, a convolutional neural network (CNN) can be utilized as an effective way to characterize hierarchical features without prior knowledge. In this paper, a novel method based on CNN is proposed for making intelligent surface roughness identifications. The technical scheme incorporates there elements: texture skew correction, image filtering, and intelligent neural network learning. Firstly, a texture skew correction algorithm, based on an improved Sobel operator and Hough transform, is applied such that surface texture directions can be adjusted. Secondly, two-dimensional (2D) dual tree complex wavelet transform (DTCWT) is employed to retrieve surface topology information, which is more effective for feature classifications. In addition, residual network (ResNet) is utilized to ensure automatic recognition of the filtered texture features. The proposed method has verified its feasibility as well as its effectiveness in actual surface roughness estimation experiments using the material of spheroidal graphite cast iron 500-7 in an agricultural machinery manufacturing company. Testing results demonstrate the proposed method has achieved high-precision surface roughness estimation. Full article

(This article belongs to the Section Mechanical Engineering)

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8 pages, 8446 KiB

Open AccessArticle

Field Emission and Emission-Stimulated Desorption of ZnO Nanomaterials

by Nannan Li^1,2,*, Xiaozhao Li¹ and Baoqing Zeng²

¹ Micro/Nano Fabrication Laboratory, Microsystem & Terahertz Research Center, CAEP, Chengdu 610200, China

² National Key Laboratory of Science and Technology on Vacuum Electronics, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China

Appl. Sci. 2018, 8(3), 382; https://doi.org/10.3390/app8030382 - 6 Mar 2018

Cited by 5 | Viewed by 3284

Abstract

Compared with other field-emission nanomaterials, 1D ZnO nanomaterials have some unique properties—such as high melting point, high thermal and chemical stability, and ambient insensitivity—which means they have promising potential applications as field emitters in harsh environments. This work proposed a water-assisted physical vapor [...] Read more.

Compared with other field-emission nanomaterials, 1D ZnO nanomaterials have some unique properties—such as high melting point, high thermal and chemical stability, and ambient insensitivity—which means they have promising potential applications as field emitters in harsh environments. This work proposed a water-assisted physical vapor deposition method to prepare various ZnO nanostructures simultaneously on a silicon substrate with one experimental run. Field emission characteristics of the as-grown ZnO nanomaterials were measured and analyzed. Emission-stimulated desorption was proposed and investigated. The gas released under the emission-stimulated desorption effect was measured in the way of monitoring the variation of the pressure. The results show that the slight variation of the pressure has almost no effects on the field-emissions, and field emission properties can be improved with the gases released from the surface of ZnO under the emission-stimulated-desorption effect. Finally, a low turn-on voltage in the range of 0.5–0.9 V/μm was achieved and a stable emission current was obtained. The ambient insensitivity of ZnO nanomaterials make them possible to be used as field emission cathodes in harsh environments with fluctuating pressure. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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16 pages, 3050 KiB

Open AccessArticle

Attend It Again: Recurrent Attention Convolutional Neural Network for Action Recognition

by Haodong Yang^1,*

, Jun Zhang^1,*, Shuohao Li¹, Jun Lei¹ and Shiqi Chen²

¹ Science and Technology on Information Systems Engineering Laboratory, National University of Defense Technology, No. 109, Deya Road, Changsha 410073, China

² College of Electronic Sciences, National University of Defense Technology, No. 109, Deya Road, Changsha 410073, China

Appl. Sci. 2018, 8(3), 383; https://doi.org/10.3390/app8030383 - 6 Mar 2018

Cited by 19 | Viewed by 4137

Abstract

Human action recognition in videos is an important task with a broad range of applications. In this study, we improve the performance of recurrent attention convolutional neural network (RACNN) by proposing a novel model, “attention-again”. We consider the nature of video frames as [...] Read more.

Human action recognition in videos is an important task with a broad range of applications. In this study, we improve the performance of recurrent attention convolutional neural network (RACNN) by proposing a novel model, “attention-again”. We consider the nature of video frames as sequences, which will cause the change of regions of interest in the frame, thus we cannot use an attention mechanism similar to that in images. “Attention-again” model is a variant from traditional attention model for recognizing human activities and is embedded in two long short-term memory (LSTM) layers. Different from hierarchal LSTM which change the LSTM structure to combine the hidden states from two LSTM layers, our proposals introduce “attention-again” model to avoid the change of LSTM structure. Furthermore, this model not only learns the relations in each frame, but also obtains the relations among all frames, and these relations instruct the next learning stage. Therefore, our proposed model outperform the baseline and is superior to methods with the same experimental conditions on three benchmark datasets: UCF-11, HMDB-51 and UCF-101. To understand how the model works, we also visualize the region of interest in the frame. Full article

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11 pages, 3300 KiB

Open AccessArticle

Experiment and Simulation Investigation on the Characteristics of Diesel Spray Impingement Based on Droplet Impact Phenomenon

by Yongfeng Liu¹, Qi Xiang¹, Zhijun Li^2,*, Shengzhuo Yao¹, Xingyu Liang² and Fang Wang¹

¹ Beijing Key Laboratory of Performance Guarantee on Urban Rail Transit Vehicles, School of Mechanical-Electronic and Vehicle Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

² State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China

Appl. Sci. 2018, 8(3), 384; https://doi.org/10.3390/app8030384 - 6 Mar 2018

Cited by 7 | Viewed by 3953

Abstract

In order to study the characteristics of diesel spray impinging in small-size internal combustion (IC) engine, the laboratorial platform of spray impingement is used to visualize the droplet impact phenomenon. A high-speed camera is used to record the whole process of the spray. [...] Read more.

In order to study the characteristics of diesel spray impinging in small-size internal combustion (IC) engine, the laboratorial platform of spray impingement is used to visualize the droplet impact phenomenon. A high-speed camera is used to record the whole process of the spray. An experimental research is accomplished under the impingement phenomenon of diesel spray on the wall with a fixed injection volume of 25 mg, injection pressure of 40 MPa, wall-injector distance of 40mm and orifice diameter of 0.26 mm. The computational fluid dynamics (CFD) simulation is carried out and the turbulence kinetic energy (TKE) distribution diagram is obtained. The results show that the maximum spray radius is 29.3 mm and maximum spray height is 10.2 mm at 2.8 ms. The spray impingement phenomenon presents the “blanket” shape. The simulation results are similar to the experimental results with the average error of the spray height within 3%. Full article

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12 pages, 1238 KiB

Open AccessArticle

Cobalt (II) Complexes with Schiff Base Ligands Derived from Terephthalaldehyde and ortho-Substituted Anilines: Synthesis, Characterization and Antibacterial Activity

by Sahar Shaygan, Hoda Pasdar^*, Naser Foroughifar, Mehran Davallo and Fereshteh Motiee

Department of Chemistry, North Tehran Branch, Islamic Azad University, Tehran 1651153311, Iran

Appl. Sci. 2018, 8(3), 385; https://doi.org/10.3390/app8030385 - 6 Mar 2018

Cited by 54 | Viewed by 9717

Abstract

In this study, N-propyl-benzoguanamine-SO₃H magnetic nanoparticles (MNPs) were used as a catalyst for the synthesis of new Schiff base ligands from condensation reaction of terephthalaldehyde and ortho-aniline derivatives. The bioactive ligands and their cobalt (II) complexes were characterized with [...] Read more.

In this study, N-propyl-benzoguanamine-SO₃H magnetic nanoparticles (MNPs) were used as a catalyst for the synthesis of new Schiff base ligands from condensation reaction of terephthalaldehyde and ortho-aniline derivatives. The bioactive ligands and their cobalt (II) complexes were characterized with nuclear magnetic resonance (¹H-NMR), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Visible), mass spectroscopy studies and molar conductance. The antibacterial activity of ligands and their metal complexes were screened using disc diffusion and broth dilution methods against Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa (gram negative bacteria), Bacillus Subtilis and Staphylococcus aureus (gram positive bacteria). The ligands with hydroxyl group showed better biological activity when compared to other ligands. The results showed that the metal complexes have much higher antibacterial activity compare to the parent ligands. It was found that the CoL₃ complex was more effective than other metal complexes used against all types of bacteria tested and it was more effective against Pseudomonas aeruginosa with diameter inhibition zone of 17 mm and minimal inhibitory concentration value of 0.15 mg/mL. Full article

(This article belongs to the Special Issue Nano-systems for Antimicrobial Therapy)

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12 pages, 4152 KiB

Open AccessArticle

Nanometric Plasmonic Rulers Based on Orthogonal Plasmonic Gap Modes in Metal Nanoblocks

by Tae-Woo Lee, Young Jin Lee, Eunso Shin and Soon-Hong Kwon^*

Department of Physics, Chung-Ang University, Seoul 06974, Korea

Appl. Sci. 2018, 8(3), 386; https://doi.org/10.3390/app8030386 - 6 Mar 2018

Cited by 1 | Viewed by 2934

Abstract

We theoretically propose a three-dimensional (3D) plasmonic ruler based on orthogonal plasmonic gap modes which have different wavelengths. The ruler consists of three silver nanoblocks with two ten-nanometer air gaps. First, in a two-block structure, the lateral displacement of one block can be [...] Read more.

We theoretically propose a three-dimensional (3D) plasmonic ruler based on orthogonal plasmonic gap modes which have different wavelengths. The ruler consists of three silver nanoblocks with two ten-nanometer air gaps. First, in a two-block structure, the lateral displacement of one block can be determined by the absorption spectrum, in which two orthogonal modes are observed with different wavelengths. Secondly, in a three-block structure, due to the distinctive wavelength dependencies on the x- or y-directional movement of the two orthogonal modes and the strong dependencies on the air gap size, the 3D positioning of one nanoblock relative to a reference nanoblock can be measured with a 2.5 nm resolution using the spectral positions of the absorption spectrum. Full article

(This article belongs to the Special Issue Photonic Metamaterials)

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30 pages, 4951 KiB

Open AccessArticle

A Multi-Modal Person Recognition System for Social Robots

by Mohammad K. Al-Qaderi and Ahmad B. Rad^*

Autonomous and Intelligent Systems Laboratory, School of Mechatronic Systems Engineering Simon Fraser University, Surrey, BC V3T 0A3, Canada

Appl. Sci. 2018, 8(3), 387; https://doi.org/10.3390/app8030387 - 6 Mar 2018

Cited by 16 | Viewed by 6864

Abstract

The paper presents a solution to the problem of person recognition by social robots via a novel brain-inspired multi-modal perceptual system. The system employs spiking neural network to integrate face, body features, and voice data to recognize a person in various social human-robot [...] Read more.

The paper presents a solution to the problem of person recognition by social robots via a novel brain-inspired multi-modal perceptual system. The system employs spiking neural network to integrate face, body features, and voice data to recognize a person in various social human-robot interaction scenarios. We suggest that, by and large, most reported multi-biometric person recognition algorithms require active participation by the subject and as such are not appropriate for social human-robot interactions. However, the proposed algorithm relaxes this constraint. As there are no public datasets for multimodal systems, we designed a hybrid dataset by integration of the ubiquitous FERET, RGB-D, and TIDIGITS datasets for face recognition, person recognition, and speaker recognition, respectively. The combined dataset facilitates association of facial features, body shape, and speech signature for multimodal person recognition in social settings. This multimodal dataset is employed for testing the algorithm. We assess the performance of the algorithm and discuss its merits against related methods. Within the context of the social robotics, the results suggest the superiority of the proposed method over other reported person recognition algorithms. Full article

(This article belongs to the Special Issue Social Robotics)

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14 pages, 925 KiB

Open AccessArticle

Pressure Transient Model of Water-Hydraulic Pipelines with Cavitation

by Dan Jiang^*, Cong Ren, Tianyang Zhao and Wenzhi Cao

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

Appl. Sci. 2018, 8(3), 388; https://doi.org/10.3390/app8030388 - 7 Mar 2018

Cited by 12 | Viewed by 5883

Abstract

Transient pressure investigation of water-hydraulic pipelines is a challenge in the fluid transmission field, since the flow continuity equation and momentum equation are partial differential, and the vaporous cavitation has high dynamics; the frictional force caused by fluid viscosity is especially uncertain. In [...] Read more.

Transient pressure investigation of water-hydraulic pipelines is a challenge in the fluid transmission field, since the flow continuity equation and momentum equation are partial differential, and the vaporous cavitation has high dynamics; the frictional force caused by fluid viscosity is especially uncertain. In this study, due to the different transient pressure dynamics in upstream and downstream pipelines, the finite difference method (FDM) is adopted to handle pressure transients with and without cavitation, as well as steady friction and frequency-dependent unsteady friction. Different from the traditional method of characteristics (MOC), the FDM is advantageous in terms of the simple and convenient computation. Furthermore, the mechanism of cavitation growth and collapse are captured both upstream and downstream of the water-hydraulic pipeline, i.e., the cavitation start time, the end time, the duration, the maximum volume, and the corresponding time points. By referring to the experimental results of two previous works, the comparative simulation results of two computation methods are verified in experimental water-hydraulic pipelines, which indicates that the finite difference method shows better data consistency than the MOC. Full article

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

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17 pages, 4318 KiB

Open AccessArticle

Power Control Optimization of an Underwater Piezoelectric Energy Harvester

by Iñigo Aramendia¹

, Unai Fernandez-Gamiz^1,*

, Ekaitz Zulueta Guerrero², Jose Manuel Lopez-Guede² and Javier Sancho¹

¹ Nuclear Engineering and Fluid Mechanics Department, University Basque Country, UPV/EHU, 01006 Vitoria, Spain

² Automatic Control and System Engineering Department, University Basque Country, UPV/EHU, 01006 Vitoria, Spain

Appl. Sci. 2018, 8(3), 389; https://doi.org/10.3390/app8030389 - 7 Mar 2018

Cited by 22 | Viewed by 5750

Abstract

Over the past few years, it has been established that vibration energy harvesters with intentionally designed components can be used for frequency bandwidth enhancement under excitation for sufficiently high vibration amplitudes. Pipelines are often necessary means of transporting important resources such as water, [...] Read more.

Over the past few years, it has been established that vibration energy harvesters with intentionally designed components can be used for frequency bandwidth enhancement under excitation for sufficiently high vibration amplitudes. Pipelines are often necessary means of transporting important resources such as water, gas, and oil. A self-powered wireless sensor network could be a sustainable alternative for in-pipe monitoring applications. A new control algorithm has been developed and implemented into an underwater energy harvester. Firstly, a computational study of a piezoelectric energy harvester for underwater applications has been studied for using the kinetic energy of water flow at four different Reynolds numbers Re = 3000, 6000, 9000, and 12,000. The device consists of a piezoelectric beam assembled to an oscillating cylinder inside the water of pipes from 2 to 5 inches in diameter. Therefore, unsteady simulations have been performed to study the dynamic forces under different water speeds. Secondly, a new control law strategy based on the computational results has been developed to extract as much energy as possible from the energy harvester. The results show that the harvester can efficiently extract the power from the kinetic energy of the fluid. The maximum power output is 996.25 µW and corresponds to the case with Re = 12,000. Full article

(This article belongs to the Special Issue Development and Application of Thermoelectric Power Generators, Energy Harvesters and Refrigerators)

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9 pages, 2586 KiB

Open AccessArticle

Bloch Surface Waves Using Graphene Layers: An Approach toward In-Plane Photodetectors

by Richa Dubey^1,*

, Miriam Marchena²

, Babak Vosoughi Lahijani¹, Myun-Sik Kim¹

, Valerio Pruneri^2,3 and Hans Peter Herzig¹

¹ Optics & Photonics Technology Laboratory (OPT), École Polytechnique Fédérale de Lausanne (EPFL), Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland

² Institut de Ciències Fotòniques (ICFO), The Barcelona Institute of Science and Technology, 08860 Castelldefels, Spain

³ Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain

Appl. Sci. 2018, 8(3), 390; https://doi.org/10.3390/app8030390 - 7 Mar 2018

Cited by 10 | Viewed by 6389

Abstract

A dielectric multilayer platform was investigated as a foundation for two-dimensional optics. In this paper, we present, to the best of our knowledge, the first experimental demonstration of absorption of Bloch surface waves in the presence of graphene layers. Graphene is initially grown [...] Read more.

A dielectric multilayer platform was investigated as a foundation for two-dimensional optics. In this paper, we present, to the best of our knowledge, the first experimental demonstration of absorption of Bloch surface waves in the presence of graphene layers. Graphene is initially grown on a Cu foil via Chemical Vapor Deposition and transferred layer by layer by a wet-transfer method using poly(methyl methacrylate), (PMMA). We exploit total internal reflection configuration and multi-heterodyne scanning near-field optical microscopy as a far-field coupling method and near-field characterization tool, respectively. The absorption is quantified in terms of propagation lengths of Bloch surface waves. A significant drop in the propagation length of the BSWs is observed in the presence of graphene layers. The propagation length of BSWs in bare multilayer is reduced to 17 times shorter in presence of graphene monolayer, and 23 times shorter for graphene bilayer. Full article

(This article belongs to the Special Issue Surface Waves on Planar Photonic Crystals)

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17 pages, 3578 KiB

Open AccessArticle

Exergy Analysis of Serpentine Thermosyphon Solar Water Heater

by Muhammad Faisal Hasan^1,2,*, Md. Sayeed Ur Rahim Mahadi³, Takahiko Miyazaki^1,4,*, Shigeru Koyama^1,4 and Kyaw Thu^1,2,4,*

¹ Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6–1 Kasuga-koen, Kasuga, Fukuoka 816–8580, Japan

² Green Asia Education Center, Kyushu University, 6–1 Kasuga-koen, Kasuga, Fukuoka 816–8580, Japan

³ Institute of Energy, University of Dhaka, Dhaka 1000, Bangladesh

⁴ International Institute for Carbon-Neutral Energy Research, Kyushu University, Motooka, Nishi Ward, Fukuoka 819–0385, Japan

Appl. Sci. 2018, 8(3), 391; https://doi.org/10.3390/app8030391 - 7 Mar 2018

Cited by 16 | Viewed by 7483

Abstract

The performance of a solar hot water system is assessed for heat pump and domestic heating applications. Thermodynamic analysis on a serpentine-type thermosyphon flat-plate solar heater is conducted using the Second Law of thermodynamics. Exergetic optimization is first performed to determine the parameters [...] Read more.

The performance of a solar hot water system is assessed for heat pump and domestic heating applications. Thermodynamic analysis on a serpentine-type thermosyphon flat-plate solar heater is conducted using the Second Law of thermodynamics. Exergetic optimization is first performed to determine the parameters for the maximum exergy efficiency using MATLAB optimization toolbox. Geometric parameters (collector surface area, dimensions, and pipe diameter), optical parameters (transmittance absorptance product), ambient temperature, solar irradiation and operating parameters (mass flow rate, fluid temperature, and overall heat transfer (loss) coefficient) are accounted for in the optimization scheme. The exergy efficiency at optimum condition is found to be 3.72%. The results are validated using experimental data and found to be in good agreement. The analysis is further extended to the influence of various operating parameters on the exergetic efficiency. It is observed that optical and thermal exergy losses contribute almost 20%, whereas approximately 77% exergy destruction is contributed by the thermal energy conversion. Exergy destruction due to pressure drop is found negligible. The result of this analysis can be used for designing and optimization of domestic heat pump system and hot water application. Full article

(This article belongs to the Special Issue Sciences in Heat Pump and Refrigeration)

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7 pages, 1524 KiB

Open AccessArticle

Shape Memory-Enhanced Electrical Self-Healing of Stretchable Electrodes

by Hongsheng Luo^1,*

, Huaquan Wang¹, Huankai Zhou¹, Xingdong Zhou¹, Jinlian Hu^2,*

, Guobin Yi¹, Zhifeng Hao¹ and Wenjing Lin¹

¹ School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China

² Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Appl. Sci. 2018, 8(3), 392; https://doi.org/10.3390/app8030392 - 7 Mar 2018

Cited by 15 | Viewed by 5513

Abstract

A novel shape memory-based self-healable stretchable electrode was explored by embedding the silver nanowires (AgNWs) network into a healable polymer matrix. Unlike the traditional shape memory-assisted self-healing, pre-stretching to the temporary shapes, which was fixed in a typical shape, memory thermo-mechanical programming significantly [...] Read more.

A novel shape memory-based self-healable stretchable electrode was explored by embedding the silver nanowires (AgNWs) network into a healable polymer matrix. Unlike the traditional shape memory-assisted self-healing, pre-stretching to the temporary shapes, which was fixed in a typical shape, memory thermo-mechanical programming significantly enhanced the thermo-triggered healing performance. The morphological as well as conduction variations during the healing process were investigated. The enhancing effect of the pre-stretching on the healing efficiency was emphasized, which was expected to attribute to the release of the pre-stored strain energy driving the closure of the scratch. The findings disclosed how to utilize the shape memory effect to improve the biomimetic properties for the stretchable electrodes, which may greatly benefit the application of the intelligent polymers in the field of multi-functional flexible electronics. Full article

(This article belongs to the Special Issue Shape Memory Polymers)

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13 pages, 9427 KiB

Open AccessFeature PaperArticle

Laser-Based Additive Manufacturing of Zirconium

by Himanshu Sahasrabudhe and Amit Bandyopadhyay^*

W. M. Keck Biomedical Materials Research Center, School of Mechanical & Materials Engineering, Washington State University, Pullman, WA 99164-2920, USA

Appl. Sci. 2018, 8(3), 393; https://doi.org/10.3390/app8030393 - 7 Mar 2018

Cited by 15 | Viewed by 6316

Abstract

Additive manufacturing of zirconium is attempted using commercial Laser Engineered Net Shaping (LENS^TM) technique. A LENS^TM-based approach towards processing coatings and bulk parts of zirconium, a reactive metal, aims to minimize the inconvenience of traditional metallurgical practices of handling [...] Read more.

Additive manufacturing of zirconium is attempted using commercial Laser Engineered Net Shaping (LENS^TM) technique. A LENS^TM-based approach towards processing coatings and bulk parts of zirconium, a reactive metal, aims to minimize the inconvenience of traditional metallurgical practices of handling and processing zirconium-based parts that are particularly suited to small volumes and one-of-a-kind parts. This is a single-step manufacturing approach for obtaining near net shape fabrication of components. In the current research, Zr metal powder was processed in the form of coating on Ti6Al4V alloy substrate. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) as well as phase analysis via X-ray diffraction (XRD) were studied on these coatings. In addition to coatings, bulk parts were also fabricated using LENS™ from Zr metal powders, and measured part accuracy. Full article

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

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18 pages, 13638 KiB

Open AccessFeature PaperArticle

Numerical Simulation of Early Age Cracking of Reinforced Concrete Bridge Decks with a Full-3D Multiscale and Multi-Chemo-Physical Integrated Analysis

by Tetsuya Ishida^1,*

, Kolneath Pen¹, Yasushi Tanaka², Kosuke Kashimura³ and Ichiro Iwaki⁴

¹ Department of Civil Engineering, The University of Tokyo, Tokyo 113-8656, Japan

² Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan

³ Research Institute of General Research Laboratory, Yokogawa Bridge Holdings Co., Ltd., Chiba 261-0002, Japan

⁴ College of Engineering, Nihon University, Fukushima 963-8642, Japan

Appl. Sci. 2018, 8(3), 394; https://doi.org/10.3390/app8030394 - 7 Mar 2018

Cited by 11 | Viewed by 6594

Abstract

In November 2011, the Japanese government resolved to build “Revival Roads” in the Tohoku region to accelerate the recovery from the Great East Japan Earthquake of March 2011. Because the Tohoku region experiences such cold and snowy weather in winter, complex degradation from [...] Read more.

In November 2011, the Japanese government resolved to build “Revival Roads” in the Tohoku region to accelerate the recovery from the Great East Japan Earthquake of March 2011. Because the Tohoku region experiences such cold and snowy weather in winter, complex degradation from a combination of frost damage, chloride attack from de-icing agents, alkali–silica reaction, cracking and fatigue is anticipated. Thus, to enhance the durability performance of road structures, particularly reinforced concrete (RC) bridge decks, multiple countermeasures are proposed: a low water-to-cement ratio in the mix, mineral admixtures such as ground granulated blast furnace slag and/or fly ash to mitigate the risks of chloride attack and alkali–silica reaction, anticorrosion rebar and 6% entrained air for frost damage. It should be noted here that such high durability specifications may conversely increase the risk of early age cracking caused by temperature and shrinkage due to the large amounts of cement and the use of mineral admixtures. Against this background, this paper presents a numerical simulation of early age deformation and cracking of RC bridge decks with full 3D multiscale and multi-chemo-physical integrated analysis. First, a multiscale constitutive model of solidifying cementitious materials is briefly introduced based on systematic knowledge coupling microscopic thermodynamic phenomena and microscopic structural mechanics. With the aim to assess the early age thermal and shrinkage-induced cracks on real bridge deck, the study began with extensive model validations by applying the multiscale and multi-physical integrated analysis system to small specimens and mock-up RC bridge deck specimens. Then, through the application of the current computational system, factors that affect the generation and propagation of early age thermal and shrinkage-induced cracks are identified via experimental validation and full-scale numerical simulation on real RC slab decks. Full article

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

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15 pages, 3888 KiB

Open AccessArticle

Thermal Analysis of Nanofluid Flow over a Curved Stretching Surface Suspended by Carbon Nanotubes with Internal Heat Generation

by Fitnat Saba¹, Naveed Ahmed¹

, Saqib Hussain², Umar Khan^2,*, Syed Tauseef Mohyud-Din³ and Maslina Darus⁴

¹ Department of Mathematics, Faculty of Sciences, HITEC University, Taxila Cantt 47080, Pakistan

² Department of Mathematics, COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan

³ Center for Research (CFR), University of Islamabad (UoI), Islamabad 44000, Pakistan

⁴ School of Mathematical Sciences, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia

Appl. Sci. 2018, 8(3), 395; https://doi.org/10.3390/app8030395 - 8 Mar 2018

Cited by 77 | Viewed by 5258

Abstract

We have investigated a two-dimensional radiative flow of a boundary layer nature. The fluid under consideration is carbon nanotube (CNT)-based nanofluid and it flows over a curved surface. The heat transfer through the flow is analyzed under the influence of internal heat generation. [...] Read more.

We have investigated a two-dimensional radiative flow of a boundary layer nature. The fluid under consideration is carbon nanotube (CNT)-based nanofluid and it flows over a curved surface. The heat transfer through the flow is analyzed under the influence of internal heat generation. Water (base fluid) along with single or multi-walled carbon nanotubes is taken to compose the nanofluid. After introducing the suitable similarity variables, the consequent equations are reduced to a system of nonlinear ordinary differential equations. The solution to the system is computed by using the shooting method accompanied by Runge–Kutta–Fehlberg algorithm. Various parameters, emerging in the governing equations, influences the flow and heat transfer distribution. These changes are captured and portrayed in the form of graphs. The changes in local rate of heat transfer and skin friction coefficient are also enlisted. To ensure the correctness of applied numerical scheme, the results are compared with some already existing studies. Full article

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

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22 pages, 2985 KiB

Open AccessArticle

Dynamic Relaxation Method for Load Capacity Analysis of Reinforced Concrete Elements

by Anna Szcześniak^* and Adam Stolarski

Faculty of Civil Engineering and Geodesy, Military University of Technology, 2 Gen. W. Urbanowicza Street, 00-908 Warsaw, Poland

Appl. Sci. 2018, 8(3), 396; https://doi.org/10.3390/app8030396 - 8 Mar 2018

Cited by 8 | Viewed by 4204

Abstract

In this paper, an analysis method for the nonlinear behavior of reinforced concrete elements subjected to short-term static loads is proposed. The range of inelastic properties for the structural materials is considered, and the deformation processes of reinforced concrete bar elements are modeled. [...] Read more.

In this paper, an analysis method for the nonlinear behavior of reinforced concrete elements subjected to short-term static loads is proposed. The range of inelastic properties for the structural materials is considered, and the deformation processes of reinforced concrete bar elements are modeled. The structural material properties are modeled using the assumptions from plastic flow theory. The load capacity analysis method for the structural system is developed using the finite difference method. The dynamic relaxation method with critical damping allows for describing the static behavior of a structural element, which is used to solve the nonlinear equilibrium equations. To increase the effectiveness of the method for post-critical analysis, the arc-length parameter on the equilibrium path is included. Numerical experiments for a reinforced concrete beam and eccentrically loaded column are run. Comparative analysis with previously published experimental, numerical, and analytical results demonstrated that the proposed computational method is very effective. Full article

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

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18 pages, 8346 KiB

Open AccessArticle

Field Navigation Using Fuzzy Elevation Maps Built with Local 3D Laser Scans

by Jorge L. Martínez^*

, Mariano Morán

, Jesús Morales

, Antonio J. Reina and Manuel Zafra

Dpto. de Ingeniería de Sistemas y Automática, Universidad de Málaga, Andalucía Tech, 29071 Málaga, Spain

Appl. Sci. 2018, 8(3), 397; https://doi.org/10.3390/app8030397 - 8 Mar 2018

Cited by 10 | Viewed by 4797

Abstract

The paper describes the case study of the mobile robot Andabata navigating on natural terrain at low speeds with fuzzy elevation maps (FEMs). To this end, leveled three-dimensional (3D) point clouds of the surroundings are obtained by synchronizing ranges obtained from a 360 [...] Read more.

The paper describes the case study of the mobile robot Andabata navigating on natural terrain at low speeds with fuzzy elevation maps (FEMs). To this end, leveled three-dimensional (3D) point clouds of the surroundings are obtained by synchronizing ranges obtained from a 360

^{\circ}

field of view 3D laser scanner with odometric and inertial measurements of the vehicle. Then, filtered point clouds are employed to produce FEMs and their corresponding fuzzy reliability masks (FRMs). Finally, each local FEM and its FRM are processed to choose the best motion direction to reach distant goal points through traversable areas. All these tasks have been implemented using ROS (Robot Operating System) nodes distributed among the cores of the onboard processor. Experimental results of Andabata during non-stop navigation on an urban park are presented. Full article

(This article belongs to the Special Issue Laser Scanning)

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31 pages, 4318 KiB

Open AccessArticle

Hesitant Probabilistic Multiplicative Preference Relations in Group Decision Making

by Zia Bashir¹, Tabasam Rashid², Jarosław Wątróbski^3,*, Wojciech Sałabun⁴ and Abbas Malik⁵

¹ Department of Mathematics, Quaid-i-Azam University, Islamabad 45320, Pakistan

² Department of Mathematics, University of Management and Technology, Lahore 54770, Pakistan

³ Faculty of Economics and Management, University of Szczecin, 71-101 Szczecin, Poland

⁴ Department of Artificial Intelligence Method and Applied Mathematics in the Faculty of Computer Science and Information Technology, West Pomeranian University of Technology, 71-210 Szczecin, Poland

⁵ Department of Computer Science, School of Engineering, Computer and Mathematical Sciences, Auckland University of Technology, Auckland 1010, New Zealand

Appl. Sci. 2018, 8(3), 398; https://doi.org/10.3390/app8030398 - 8 Mar 2018

Cited by 44 | Viewed by 4870

Abstract

The preference of one alternative over another is a useful way to express the opinion of the decision-maker. In the process of group decision-making, preference relations are used in preference modeling of the alternatives under given criteria. The probability is an important tool [...] Read more.

The preference of one alternative over another is a useful way to express the opinion of the decision-maker. In the process of group decision-making, preference relations are used in preference modeling of the alternatives under given criteria. The probability is an important tool to deal with uncertainty and, in many scenarios of decision-making problems, the probabilities of different events affect the decision-making process directly. In order to deal with this issue, the hesitant probabilistic multiplicative preference relation (HPMPR) is defined in this paper. Furthermore, consistency of the HPMPR and consensus among decision makers are studied here. In this respect, many algorithms are developed to achieve consistency of HPMPRs, reasonable consensus between decision-makers and a final algorithm is proposed comprehending all other algorithms, presenting a complete decision support model for group decision-making. Lastly, we present a case study with complete illustration of the proposed model and discuss the effects of probabilities on decision-making validating the importance of the introduction of probability in hesitant multiplicative preference relations. Full article

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18 pages, 1085 KiB

Open AccessArticle

Optimization of Mass Concrete Construction Using a Twofold Parallel Genetic Algorithm

by Mariane Rita¹, Eduardo Fairbairn^1,*

, Fernando Ribeiro¹, Henrique Andrade¹ and Helio Barbosa²

¹ Department of Civil Engineering, The Federal University of Rio de Janeiro (COPPE/UFRJ), Rio de Janeiro 21941-972, RJ, Brazil

² National Laboratory of Scientific Computing (LNCC), The Federal University of Juiz de Fora (UFJF), Juiz de Fora 25651-075, MG, Brazil

Appl. Sci. 2018, 8(3), 399; https://doi.org/10.3390/app8030399 - 9 Mar 2018

Cited by 24 | Viewed by 6328

Abstract

This paper presents a solution strategy, based on a parallel Genetic Algorithm (GA), to optimize the construction of massive concrete structures. The optimization process aims at minimizing the construction cost, considering the following design variables: the concrete mixes, the placing temperature, the height [...] Read more.

This paper presents a solution strategy, based on a parallel Genetic Algorithm (GA), to optimize the construction of massive concrete structures. The optimization process aims at minimizing the construction cost, considering the following design variables: the concrete mixes, the placing temperature, the height of the lifts, and the time intervals between placing the lifts. The cracking tendency is taken into account by a penalty scheme imposed to the fitness function of the GA. A thermo-chemo-mechanical model is used to calculate the transient fields of hydration, temperature, stress, strain, and cracking tendency. This model is implemented in a finite element code that is, in turn, parallelized. To demonstrate the efficiency of the proposed methodology, the simulation of the construction of a structure similar to the real thick foundation of an industrial building is presented. It shows that the optimization procedure here presented is feasible and is ready to be used in real engineering applications. Full article

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

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18 pages, 2996 KiB

Open AccessArticle

Advanced Hysteretic Model of a Prototype Seismic Isolation System Made of Polymeric Bearings

by Tomasz Falborski^*

and Robert Jankowski

Faculty of Civil and Environmental Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk, Poland

Appl. Sci. 2018, 8(3), 400; https://doi.org/10.3390/app8030400 - 9 Mar 2018

Cited by 25 | Viewed by 3825

Abstract

The present paper reports the results of acomprehensive study designed to verify the effectiveness of an advanced mathematical model in simulating the complex mechanical behaviour of a prototype seismic isolation system made of polymeric bearings (PBs). Firstly, in order to construct the seismic [...] Read more.

The present paper reports the results of acomprehensive study designed to verify the effectiveness of an advanced mathematical model in simulating the complex mechanical behaviour of a prototype seismic isolation system made of polymeric bearings (PBs). Firstly, in order to construct the seismic bearings considered in this research, a specially prepared flexible polymeric material with increased damping properties was employed. High effectiveness of PBs in reducing structural vibrations due to seismic excitations was already confirmed during a previously conducted shaking table investigation. In order to accurately capture the complex mechanical behaviour of PBs in numerical analysis, the proposed mathematical model defines the lateral force as a nonlinear function of shear displacement and deformation velocity. Function parameters were evaluated by fitting the general form of the mathematical model into the experimentally obtained hysteresis loops, using the least squares optimisation method. The effectiveness of the mathematical model was verified by comparing the experimental data (i.e., seismic response of a 1.20 m high single-storey and a 2.30 m high two-storey structure models under various ground motions) with the results obtained from the detailed numerical analysis, where the experimental models were idealized as multi-degree-of-freedom systems. The results obtained from this investigation explicitly confirmed that the proposed mathematical model can be successfully adopted to accurately capture complex mechanical behaviour of PBs in numerical studies. Full article

(This article belongs to the Section Mechanical Engineering)

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30 pages, 17650 KiB

Open AccessArticle

Examination of Indoor Mobile Mapping Systems in a Diversified Internal/External Test Field

by Grazia Tucci^1,*, Domenico Visintini²

, Valentina Bonora¹ and Erica Isabella Parisi¹

¹ GECO Laboratory, Department of Civil and Environmental Engineering, University of Florence, via Pier Antonio Micheli 8, I-50121 Florence, Italy

² Polytechnic Department of Engineering and Architecture, University of Udine, via delle Scienze 206, I-33100 Udine, Italy

Appl. Sci. 2018, 8(3), 401; https://doi.org/10.3390/app8030401 - 9 Mar 2018

Cited by 82 | Viewed by 7770

Abstract

Nowadays, simultaneous localization and mapping (SLAM) algorithms support several commercial sensors which have recently been introduced to the market, and, like the more common mobile mapping systems (MMSs), are designed to acquire three-dimensional and high-resolution point clouds. The new systems are said to [...] Read more.

Nowadays, simultaneous localization and mapping (SLAM) algorithms support several commercial sensors which have recently been introduced to the market, and, like the more common mobile mapping systems (MMSs), are designed to acquire three-dimensional and high-resolution point clouds. The new systems are said to work both in external and internal environments, and completely avoid the use of targets and control points. The possibility of increasing productivity in three-dimensional digitization projects is fascinating, but data quality needs to be carefully evaluated to define appropriate fields of application. The paper presents the analytical measurement principle of these indoor mobile mapping systems (IMMSs) and the results of some tests performed on three commercial systems. A common test field was defined in order to acquire comparable data. By taking the already available terrestrial laser scan survey as the ground truth, the datasets under examination were compared with the reference and some assessments are presented which consider both quantitative and qualitative aspects. Geometric deformation in the final models was computed using the so-called Multiscale Model to Model Cloud Comparison (M3C2) algorithm. Cross sections and cloud to mesh (C2M) distances were also employed for a more detailed analysis. The real usability assessment is based on the features of recognizability, double surface evidence, and visualization effectiveness. For these evaluations, comparative images and tables are presented. Full article

(This article belongs to the Special Issue Laser Scanning)

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17 pages, 3328 KiB

Open AccessArticle

Experimental Estimation of the Constant Envelope FM-OFDM Method Usage in Underwater Acoustic Communication Systems

by Aleksandr Rodionov¹, Lyubov Statsenko¹, Peter Unru^1,*, Yury Morgunov², Aleksandr Golov²

, Eugene Voitenko² and Alexey Kiryanov¹

¹ Department of Electronics and Communications, Far Eastern Federal University, Primorsky Region, 690091 Vladivostok, Russia

² V.I. ll’ichev Pacific Oceanological Institute, Primorsky Region, 690041 Vladivostok, Russia

Appl. Sci. 2018, 8(3), 402; https://doi.org/10.3390/app8030402 - 9 Mar 2018

Cited by 5 | Viewed by 4002

Abstract

Nowadays, more and more complex methods of signal modulating and processing are actively used for organizing underwater acoustic communication with and between submerged mobile vehicles due to harsh underwater conditions. In this research, the method that is based on multi-frequency signals forming (OFDM) [...] Read more.

Nowadays, more and more complex methods of signal modulating and processing are actively used for organizing underwater acoustic communication with and between submerged mobile vehicles due to harsh underwater conditions. In this research, the method that is based on multi-frequency signals forming (OFDM) with the constant envelope is applied to the problem. It is based on multi-frequency FM-OFDM signals forming with Quadrature Phase Shift Keying (QPSK) modulated subcarriers and FM spectrum spreading coefficients of 1, 2, 4, and 10. The proposed solution was modeled in a software simulator, which implements a noisy underwater acoustic multipath channel, changing the bit error rate (BER) from 0.15 to 10⁻³. In addition, it was tested during the full-scale data transmission experiments at 25 km distance using a low frequency (400 Hz) underwater acoustic apparatus under conditions of strong impulse noises and quasi-non-stationary channel. The results of in-situ experiments were similar to the ones that were obtained during the simulation. Full article

(This article belongs to the Special Issue Underwater Acoustics, Communications and Information Processing)

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16 pages, 3945 KiB

Open AccessArticle

Printability Study of Bioprinted Tubular Structures Using Liquid Hydrogel Precursors in a Support Bath

by Houzhu Ding and Robert C. Chang^*

Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA

Appl. Sci. 2018, 8(3), 403; https://doi.org/10.3390/app8030403 - 9 Mar 2018

Cited by 91 | Viewed by 8714

Abstract

Microextrusion-based bioprinting within a support bath material is an emerging additive manufacturing paradigm for complex three-dimensional (3D) tissue construct fabrication. Although a support bath medium enables arbitrary in-process geometries to be printed, a significant challenge lies in preserving the shape fidelity upon the [...] Read more.

Microextrusion-based bioprinting within a support bath material is an emerging additive manufacturing paradigm for complex three-dimensional (3D) tissue construct fabrication. Although a support bath medium enables arbitrary in-process geometries to be printed, a significant challenge lies in preserving the shape fidelity upon the extraction of the support bath material. Based on the bioprinting in a support bath paradigm, this paper advances quantitative analyses to systematically determine the printability of cell-laden liquid hydrogel precursors towards filament-based tissue constructs. First, a yield stress nanoclay material is judiciously selected as the support bath medium owing to its insensitivity to temperature and ionic variations that are considered in the context of the current gelatin-alginate bio-ink material formulation. Furthermore, phenomenological observations for the rheology-mediated print outcomes enable the compositions for the bio-ink material (10% gelatin, 3% alginate), in tandem with the support bath medium (4% nanoclay, 0.5% CaCl₂), to be identified. To systematically evaluate the performance outcomes for bioprinting within a support bath, this paper advances an experimental parametric study to optimize the 3D structural shape fidelity by varying parameters such as the layer height, extrusion flowrate, printing temperature, and printhead speed, towards fabricating complex 3D structures with the stabilization of the desired shape outcome. Specifically, it is found that the layer height and printhead speed are determinant parameters for the extent of successive layer fusion. Moreover, maintenance of an optimal bath temperature is identified as a key parameter for establishing the printability for the hydrogel bio-ink. Studying this effect is enabled by the custom design of a PID temperature control system with integration with the bioprinter for real-time precision control of the support bath temperature. In order to qualify the printed construct, a surface irregularity metric, defined as the average height difference between consecutive local maximum and minimum points of the binary image contour for the printed structure, is advanced to evaluate the quality of the printed constructs. Complex one-to-four bifurcating tubular structure prints demonstrate the applicability of the optimized bioprinting parameter space to create exemplar 3D human vessel-like structures. Finally, a cell viability assay and perfusion test for a printed cell-laden tubular element demonstrates high cell survival rates and leakage-free flow, respectively. Full article

(This article belongs to the Special Issue Biofabrication: From Additive Bio-Manufacturing to Bioprinting)

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11 pages, 1714 KiB

Open AccessArticle

Interaction of Extracellular Vesicles with Si Surface Studied by Nanomechanical Microcantilever Sensors

by Stefania Federici^1,2,*, Andrea Ridolfi¹, Andrea Zendrini³, Annalisa Radeghieri^3,4, Elza Bontempi^1,2

, Laura E. Depero^1,2 and Paolo Bergese^2,3,4

¹ Department of Mechanical and Industrial Engineering, University of Brescia, 25123 Brescia, Italy

² Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), 50121 Firenze, Italy

³ Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy

⁴ Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interface (CSGI), 50019 Sesto Fiorentino, Italy

Appl. Sci. 2018, 8(3), 404; https://doi.org/10.3390/app8030404 - 9 Mar 2018

Cited by 3 | Viewed by 3676

Abstract

We report on the interaction of small (<150 nm) extracellular vesicles (EVs) with silicon surface. The study is conducted by leveraging Si nanomechanical microcantilever sensors actuated in static and dynamic modes, that allow tracking of EV collective adsorption energy and adsorbed mass. Upon [...] Read more.

We report on the interaction of small (<150 nm) extracellular vesicles (EVs) with silicon surface. The study is conducted by leveraging Si nanomechanical microcantilever sensors actuated in static and dynamic modes, that allow tracking of EV collective adsorption energy and adsorbed mass. Upon incubation for 30 min at about 10 nM concentration, EVs isolated from human vascular endothelial cell (HVEC) lines form a patchy layer that partially covers the Si total surface. Formation of this layer releases a surface energy equal to (8 ± 1) mJ/m², typical of weak electrostatic interactions. These findings give a first insight into the EV-Si interface and proof the possibility to realize new hybrid biointerphases that can be exploited as advanced models to investigate properties of biological membranes and/or biosensing platforms that take advantage of biomolecules embedded/supported in membranes. Full article

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

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17 pages, 3792 KiB

Open AccessArticle

Investigation on the Sensitivity of Ultrasonic Test Applied to Reinforced Concrete Beams Using Neural Network

by Jason Maximino C. Ongpeng^1,*

, Andres Winston C. Oreta¹ and Sohichi Hirose²

¹ Department of Civil Engineering, De La Salle University, 2401 Taft Avenue, Manila 1004, Philippines

² Department of Civil Engineering, Tokyo Institute of Technology, Meguro Ookayama 2-12-1, Tokyo 152-8552, Japan

Appl. Sci. 2018, 8(3), 405; https://doi.org/10.3390/app8030405 - 9 Mar 2018

Cited by 14 | Viewed by 5341

Abstract

An experiment on reinforced concrete beams using four-point bending test during an ultrasonic test was conducted. Three beam specimens were considered for each water/cement ratio (WC) of 40% and 60%, with three reinforcement schedules named design A (comprising two top bars and two [...] Read more.

An experiment on reinforced concrete beams using four-point bending test during an ultrasonic test was conducted. Three beam specimens were considered for each water/cement ratio (WC) of 40% and 60%, with three reinforcement schedules named design A (comprising two top bars and two bottom bars), design B (with two bottom bars), and design C (with one bottom bar). The concrete beam had a size of 100 mm × 100 mm × 400 mm in length with a plain reinforcement bar of 9 mm in diameter. An ultrasonic test with pitch–catch configuration was conducted at each loading with the transducers oriented in direct transmission across the beams' length with recordings of 68 datasets per beam specimen. Recordings of ultrasonic test results and strains at the top and bottom surfaces subjected to multiple step loads in the experiment were done. After the collection of the data, feed-forward backpropagation artificial neural network (ANN) was used to investigate the sensitivity of the ultrasonic parameters to the mechanical load applied. Five input parameters were examined, as follows: neutral axis (NA), fundamental harmonic amplitude (A1), second harmonic amplitude (A2), third harmonic amplitude (A3), and peak-to-peak amplitude (PPA), while the output parameter was the percentage of ultimate load. Optimum models were chosen after training, validating, and testing 60 ANN models. The optimum model was chosen on the basis of the highest Pearson’s Correlation Coefficient (R) and soundness, confirming that it exhibited good behavior in agreement with theories. A classification of sensitivity was performed using simulations based on the developed optimum models. It was found that A2 and NA were sensitive to all WC and reinforcements used in the ANN simulation. In addition, the range of sensitivity of A2 and NA was inversely and directly proportional to the reinforcing bars, respectively. This study can be used as a guide in the selection of ultrasonic parameters to assess damage in concrete with low or high WC and varying reinforcement content. Full article

(This article belongs to the Special Issue Soft Computing Techniques in Structural Engineering and Materials)

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22 pages, 4453 KiB

Open AccessArticle

Pneumatic Rotary Actuator Position Servo System Based on ADE-PD Control

by Yeming Zhang^*

, Ke Li^*

, Shaoliang Wei and Geng Wang

School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454000, China

Appl. Sci. 2018, 8(3), 406; https://doi.org/10.3390/app8030406 - 9 Mar 2018

Cited by 5 | Viewed by 5687

Abstract

In order to accurately control the rotation position of a pneumatic rotary actuator, the flow state of the gas and the motion state of the pneumatic rotary actuator in the pneumatic rotary actuator position servo system are analyzed in this paper. The mathematical [...] Read more.

In order to accurately control the rotation position of a pneumatic rotary actuator, the flow state of the gas and the motion state of the pneumatic rotary actuator in the pneumatic rotary actuator position servo system are analyzed in this paper. The mathematical model of the system and the experiment platform are established after that. An Adaptive Differential Evolution (ADE) algorithm which adaptively ameliorates the scaling factor and crossover probability in the process of individual evolution is proposed and applied to the parameter optimization of PD controller. The experimental platform is used to compare the controller with Differential Evolution (DE) algorithm and NCD-PID controller. Finally, the characteristics of the system are tested by increasing the inertial load. The experimental results illustrate that system using ADE-PD control strategy has greater position precision and faster response than using DE-PD and NCD-PID strategies, and shows great robustness. Full article

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

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24 pages, 4821 KiB

Open AccessArticle

Path Planning Strategy for Vehicle Navigation Based on User Habits

by Pengzhan Chen

, Xiaoyan Zhang, Xiaoyue Chen^* and Mengchao Liu

School of Electrical Engineering and Automation, East China Jiaotong University, Nanchang 330013, China

Appl. Sci. 2018, 8(3), 407; https://doi.org/10.3390/app8030407 - 9 Mar 2018

Cited by 15 | Viewed by 4826

Abstract

Vehicle navigation is widely used in path planning of self driving travel, and it plays an increasing important role in people's daily trips. Therefore, path planning algorithms have attracted substantial attention. However, most path planning methods are based on public data, aiming at [...] Read more.

Vehicle navigation is widely used in path planning of self driving travel, and it plays an increasing important role in people's daily trips. Therefore, path planning algorithms have attracted substantial attention. However, most path planning methods are based on public data, aiming at different driver groups rather than a specific user. Hence, this study proposes a personalized path decision algorithm that is based on user habits. First, the categories of driving characteristics are obtained through the investigation of public users, and the clustering results corresponding to the category space are obtained by log fuzzy C-means clustering algorithm (LFCM) based on the driving information contained in the log trajectories. Then, the road performance personalized quantization algorithm evaluation is proposed to evaluate roads from the user’s field of vision. Finally, adaptive ant colony algorithm is improved and used to validate the path planning based on the road performance personalized values. Results show that the algorithm can meet the personalized requirements of the user path selection in the path decision. Full article

(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)

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19 pages, 4198 KiB

Open AccessFeature PaperArticle

Model Predictive Control Home Energy Management and Optimization Strategy with Demand Response

by Radu Godina^1,*

, Eduardo M. G. Rodrigues^1,*, Edris Pouresmaeil²

, João C. O. Matias^1,3

and João P. S. Catalão^1,4,5

¹ Centre for Mechanical and Aerospace Science and Technologies (C-MAST), University of Beira Interior, 6201-001 Covilhã, Portugal

² Department of Electrical Engineering and Automation, Aalto University, 02150 Espoo, Finland

³ The Research Unit on Governance, Competitiveness and Public Policies (GOVCOPP), University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

⁴ Institute for Systems and Computer Engineering, Technology and Science (INESC TEC) and the Faculty of Engineering of the University of Porto, 4200-465 Porto, Portugal

⁵ Instituto de Engenharia de Sistemas e Computadores-Investigação e Desenvolvimento (INESC-ID), Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal

Appl. Sci. 2018, 8(3), 408; https://doi.org/10.3390/app8030408 - 9 Mar 2018

Cited by 89 | Viewed by 9377

Abstract

The growing demand for electricity is a challenge for the electricity sector as it not only involves the search for new sources of energy, but also the increase of generation capacity of the existing electrical infrastructure and the need to upgrade the existing [...] Read more.

The growing demand for electricity is a challenge for the electricity sector as it not only involves the search for new sources of energy, but also the increase of generation capacity of the existing electrical infrastructure and the need to upgrade the existing grid. Therefore, new ways to reduce the consumption of energy are necessary to be implemented. When comparing an average house with an energy efficient house, it is possible to reduce annual energy bills up to 40%. Homeowners and tenants should consider developing an energy conservation plan in their homes. This is both an ecological and economically rational action. With this goal in mind, the need for the energy optimization arises. However, this has to be made by ensuring a fair level of comfort in the household, which in turn spawns a few control challenges. In this paper, the ON/OFF, proportional-integral-derivative (PID) and Model Predictive Control (MPC) control methods of an air conditioning (AC) of a room are compared. The model of the house of this study has a PV domestic generation. The recorded climacteric data for this case study are for Évora, a pilot Portuguese city in an ongoing demand response (DR) project. Six Time-of-Use (ToU) electricity rates are studied and compared during a whole week of summer, typically with very high temperatures for this period of the year. The overall weekly expense of each studied tariff option is compared for every control method and in the end the optimal solution is reached. Full article

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

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22 pages, 13487 KiB

Open AccessFeature PaperArticle

Depth Retrieval Procedures in Pulsed Thermography: Remarks in Time and Frequency Domain Analyses

by Panagiotis Theodorakeas^*

and Maria Koui

NDT Laboratory, Department of Materials Science & Engineering, School of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou No. 9, Zografou Campus, 15780 Athens, Greece

Appl. Sci. 2018, 8(3), 409; https://doi.org/10.3390/app8030409 - 9 Mar 2018

Cited by 16 | Viewed by 4030

Abstract

In the present study, a Carbon Fibre Reinforced Polymer (CFRP) sample of trapezoid shape, consisting of internal artificial delaminations of various sizes and depth locations, is investigated by means of optical pulsed thermography for the retrieval of quantitative depth information. The main objectives [...] Read more.

In the present study, a Carbon Fibre Reinforced Polymer (CFRP) sample of trapezoid shape, consisting of internal artificial delaminations of various sizes and depth locations, is investigated by means of optical pulsed thermography for the retrieval of quantitative depth information. The main objectives of this work are to evaluate the produced depth estimation accuracy from two contrast-based depth inversion procedures as well as to correlate the acquired results with characteristics such as the location and size of the detected features and with analysis parameters such as the selection of the sound area. Quantitative analysis is performed in both the temporal and frequency domains, utilising, respectively, the informative parameters of thermal contrast peak slope time and blind frequency. The two depth retrieval procedures are applied for the depth estimation of features ranging in size from 3 mm to 15 mm and in depth from 0.2 mm to 1 mm. The results of the present study showed that the two different analyses provided efficient depth estimations, with frequency domain analysis presenting a greater accuracy. Nevertheless, predicting errors were observed in both cases and the factors responsible for these errors are defined and discussed. Full article

(This article belongs to the Special Issue Novel Ideas for Infrared Thermography also Applied in Integrated Approaches)

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19 pages, 6558 KiB

Open AccessArticle

Robust Image Watermarking Algorithm Based on ASIFT against Geometric Attacks

by Chengyou Wang

, Yunpeng Zhang

and Xiao Zhou^*

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

Appl. Sci. 2018, 8(3), 410; https://doi.org/10.3390/app8030410 - 9 Mar 2018

Cited by 39 | Viewed by 6946

Abstract

Image processing technology has been developed rapidly in recent years, and altering the content of an image is easy for everyone, but may be illegal for an attacker. Thus, it is urgent and necessary to overcome this problem to protect the integrity and [...] Read more.

Image processing technology has been developed rapidly in recent years, and altering the content of an image is easy for everyone, but may be illegal for an attacker. Thus, it is urgent and necessary to overcome this problem to protect the integrity and authenticity of images. Watermarking is a powerful technique proposed to solve this problem. This paper introduces a robust image watermarking algorithm working in the wavelet domain, embedding the watermark information into the third level low frequency coefficients after the three-level discrete wavelet transform (DWT) and singular value decomposition (SVD). Additionally, to improve the robustness to geometric attacks, the affine-scale-invariant feature transform (ASIFT) is applied to obtain feature points which are invariant to geometric attacks. Then, features of acquired points between the watermarked image and the received image are used to realize the resynchronization to improve the robustness. Experimental results show that the proposed algorithm achieves great balance between robustness and imperceptibility, and is robust against geometric attacks, JPEG compression, noise addition, cropping, median filters, and so on. Full article

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12 pages, 2846 KiB

Open AccessArticle

Interleukin 6 Plays a Role in the Migration of Magnetically Levitated Mesenchymal Stem Cells Spheroids

by Jake Casson

, Sam O’Kane, Carol-Anne Smith, Matthew John Dalby and Catherine Cecilia Berry^*

Centre for Cell Engineering, Institute of Molecular, Cell and Systems Biology (IMCSB), The University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK

Appl. Sci. 2018, 8(3), 412; https://doi.org/10.3390/app8030412 - 11 Mar 2018

Cited by 14 | Viewed by 6790

Abstract

Mesenchymal stem cells (MSCs) reside quiescently within a specialised ‘niche’ environment in the bone marrow. However, following appropriate signalling cues, MSCs mobilise and migrate out from the niche, typically toward either sites of injury (a regenerative response) or toward primary tumours (an intrinsic [...] Read more.

Mesenchymal stem cells (MSCs) reside quiescently within a specialised ‘niche’ environment in the bone marrow. However, following appropriate signalling cues, MSCs mobilise and migrate out from the niche, typically toward either sites of injury (a regenerative response) or toward primary tumours (an intrinsic homing response, which promotes MSCs as cellular vectors for therapeutic delivery). To date, very little is known about MSC mobilisation. By adopting a 3D MSC niche model, whereby MSC spheroids are cultured within a type I collagen gel, recent studies have highlighted interleukin-6 (IL-6) as a key cytokine involved in MSC migration. Herein, the ability of IL-6 to induce MSC migration was further investigated, and the key matrix metalloproteinases used to effect cell mobilisation were identified. Briefly, the impact of IL-6 on the MSC migration in a two-dimensional model systems was characterised—both visually using an Ibidi chemotaxis plate array (assessing for directional migration) and then via a standard 2D monolayer experiment, where cultured cells were challenged with IL-6 and extracted media tested using an Abcam Human MMP membrane antibody array. The 2D assay displayed a strong migratory response toward IL-6 and analysis of the membrane arrays data showed significant increases of several key MMPs. Both data sets indicated that IL-6 is important in MSC mobilisation and migration. We also investigated the impact of IL-6 induction on MSCs in 3D spheroid culture, serving as a simplistic model of the bone marrow niche, characterised by fluorescently tagged magnetic nanoparticles and identical membrane antibody arrays. An increase in MMP levels secreted by cells treated with 1 ng/mL IL-6 versus control conditions was noted in addition to migration of cells away from the central spheroid mass. Full article

(This article belongs to the Special Issue Biological Applications of Magnetic Nanoparticles)

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8 pages, 1555 KiB

Open AccessFeature PaperArticle

Development of Multiphoton Ionization Time-of-Flight Mass Spectrometry for the Detection of Small Emulsion Droplets

by Chiaki Fujita, Yoshiki Sugimura and Tomohiro Uchimura^*

Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan

Appl. Sci. 2018, 8(3), 413; https://doi.org/10.3390/app8030413 - 11 Mar 2018

Cited by 4 | Viewed by 3724

Abstract

A system for measuring small oil droplets in an oil-in-water (O/W) emulsion was developed using multiphoton ionization time-of-flight mass spectrometry. In the present study, a capillary column with an inner diameter of 15 µm was used for sample introduction. Moreover, a compact microscopic [...] Read more.

A system for measuring small oil droplets in an oil-in-water (O/W) emulsion was developed using multiphoton ionization time-of-flight mass spectrometry. In the present study, a capillary column with an inner diameter of 15 µm was used for sample introduction. Moreover, a compact microscopic system was constructed for observing an emulsion flowing through a capillary column. As a result, the length for sample introduction was shortened, which is preferable for the direct evaluation of an emulsion. Using this system, the minimum diameter of a detectable toluene droplet in an O/W emulsion was decreased to 1.7 µm. The present system could be used to evaluate the local microenvironment and stability of an emulsion. Full article

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

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15 pages, 425 KiB

Open AccessArticle

Capture Effect in the FSA-Based Networks under Rayleigh, Rician and Nakagami-m Fading Channels

by Yang Wang

, Jianghong Shi and Lingyu Chen^*

School of Information Science and Engineering, Xiamen University, Xiamen 361005, China

Appl. Sci. 2018, 8(3), 414; https://doi.org/10.3390/app8030414 - 11 Mar 2018

Cited by 4 | Viewed by 3953

Abstract

Framed slotted aloha (FSA) is a multiple access protocol widely used in wireless communication for its simplicity and effectivity. The theoretical maximum channel utilization of FSA is approximately equal to 0.37 irrespective of the capture effect. In fact, the capture effect is a [...] Read more.

Framed slotted aloha (FSA) is a multiple access protocol widely used in wireless communication for its simplicity and effectivity. The theoretical maximum channel utilization of FSA is approximately equal to 0.37 irrespective of the capture effect. In fact, the capture effect is a common phenomenon in wireless communication, which can increase the channel utilization. In this paper, we derive the closed-form expressions of capture probabilities under Rayleigh, Rician and Nakagami-m fading channels, respectively, and further give the optimal frame length which maximizes the channel utilization in the FSA-based networks. The numerical results are given for indicating the capture probabilities under different fading channels and their impacts on the optimal frame length and the maximum channel utilization. Full article

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25 pages, 9033 KiB

Open AccessArticle

Potential of Waste Oyster Shells as a Novel Biofiller for Hot-Mix Asphalt

by Nader Nciri

, Taesub Shin, Haksoo Lee and Namjun Cho^*

Department of Energy, Materials, and Chemical Engineering, Korea University of Technology and Education, 1600 Chungjeol-ro, Byeongcheon-myeon, Dongnam-gu, Cheonan 330-708, Korea

Appl. Sci. 2018, 8(3), 415; https://doi.org/10.3390/app8030415 - 11 Mar 2018

Cited by 54 | Viewed by 9785

Abstract

This paper reports the use of waste oyster shells as a novel biofiller for hot-mix asphalt (HMA) pavement applications. The effects of different fractions (e.g., 0, 5, 10, 15 wt %) of oyster shell powder (OSP) on the bitumen performance were investigated. The [...] Read more.

This paper reports the use of waste oyster shells as a novel biofiller for hot-mix asphalt (HMA) pavement applications. The effects of different fractions (e.g., 0, 5, 10, 15 wt %) of oyster shell powder (OSP) on the bitumen performance were investigated. The chemical properties of unfilled and OSP-filled asphalts were characterized by means of thin layer chromatography-ionization detection (TLC-FID), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Thermal characteristics were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Physical and rheological properties were assessed through penetration, softening point, ductility, and dynamic shear rheometer (DSR) tests. Results showed that OSP addition increased the resins content, as well as the stiffness of blends. No obvious reactions have occurred between the filler and the asphalt. A higher dose of OSP altered the morphology of the binder, whereas lower and intermediate doses improved its thermal stability and enhanced its low-temperature, rutting, and fatigue performances with respect to the plain asphalt. Overall, the waste oyster shells could be used as filler substitute, not only to improve the quality of road pavements but also to reduce the cost of their construction and solve the waste disposal problems. Full article

(This article belongs to the Special Issue Achievements and Prospects of Functional Pavement: Materials and Structures)

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19 pages, 2826 KiB

Open AccessFeature PaperArticle

Performance Evaluation of Two Indoor Mapping Systems: Low-Cost UWB-Aided Photogrammetry and Backpack Laser Scanning

by Andrea Masiero^1,*

, Francesca Fissore¹

, Alberto Guarnieri¹

, Francesco Pirotti¹

, Domenico Visintini²

and Antonio Vettore¹

¹ Interdepartmental Research Center of Geomatics (CIRGEO), University of Padova, via dell’Università 16, 35020 Legnaro (PD), Italy

² Dipartimento Politecnico di Ingegneria e Architettura, University of Udine, via delle Scienze 206, 33100 Udine, Italy

Appl. Sci. 2018, 8(3), 416; https://doi.org/10.3390/app8030416 - 11 Mar 2018

Cited by 48 | Viewed by 6191

Abstract

During the past dozen years, several mobile mapping systems based on the use of imaging and positioning sensors mounted on terrestrial (and aerial) vehicles have been developed. Recently, systems characterized by an increased portability have been proposed in order to enable mobile mapping [...] Read more.

During the past dozen years, several mobile mapping systems based on the use of imaging and positioning sensors mounted on terrestrial (and aerial) vehicles have been developed. Recently, systems characterized by an increased portability have been proposed in order to enable mobile mapping in environments that are difficult to access for vehicles, in particular for indoor environments. In this work the performance of a low-cost mobile mapping system is compared with that of: (i) a state-of-the-art terrestrial laser scanning (TLS), considered as the control; (ii) a mobile mapping backpack system (Leica Pegasus), which can be considered as the state-of-the-art of commercial mobile mapping backpack systems. The aim of this paper is two-fold: first, assessing the reconstruction accuracy of the proposed low-cost mobile mapping system, based on photogrammetry and ultra-wide band (UWB) for relative positioning (and a GNSS receiver if georeferencing is needed), with respect to a TLS survey in an indoor environment, where the global navigation satellite system (GNSS) signal is not available; second, comparing such performance with that obtained with the Leica backpack. Both mobile mapping systems are designed to work without any control point, to enable an easy and quick survey (e.g., few minutes) and to be easily portable (relatively low weight and small size). The case study deals with the 3D reconstruction of a medieval bastion in Padua, Italy. Reconstruction using the Leica Pegasus backpack allowed obtaining a smaller absolute error with respect to the UWB-based photogrammetric system. In georeferenced coordinates, the root mean square (RMS) error was respectively 16.1 cm and 50.3 cm; relative error in local coordinates was more similar, respectively 8.2 cm and 6.1 cm. Given the much lower cost (approximately $6k), the proposed photogrammetric-based system can be an interesting alternative when decimetric reconstruction accuracy in georeferenced coordinates is sufficient. Full article

(This article belongs to the Special Issue Laser Scanning)

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13 pages, 3426 KiB

Open AccessArticle

Fatigue Resistance Evaluation of Modified Asphalt Using a Multiple Stress Creep and Recovery (MSCR) Test

by Weiguang Zhang¹, Tao Ma^1,*, Gang Xu¹, Xiaoming Huang¹, Meng Ling², Xiao Chen³ and Jiayue Xue³

¹ School of Transportation, Southeast University, Nanjing 211189, China

² Texas A&M Transportation Institute, College Station, TX 77843, USA

³ School of Transportation, Southeast University, Nanjing 211189, China

Appl. Sci. 2018, 8(3), 417; https://doi.org/10.3390/app8030417 - 12 Mar 2018

Cited by 26 | Viewed by 6060

Abstract

Fatigue resistance quantification of modified asphalt is typically time consuming and may not correlate well with mixture fatigue test results. In this paper, the applicability of a multiple stress creep and recovery (MSCR) test on asphalt binder’s fatigue resistance was evaluated. Six binder [...] Read more.

Fatigue resistance quantification of modified asphalt is typically time consuming and may not correlate well with mixture fatigue test results. In this paper, the applicability of a multiple stress creep and recovery (MSCR) test on asphalt binder’s fatigue resistance was evaluated. Six binder types with a variety of modifiers and different modifier contents were characterized. The MSCR test was conducted and its sensitivity to binder type and additive content under different aging durations was evaluated. Mixture fatigue tests including a semi-circular bending- Illinois flexibility index test and indirect tensile strength were conducted using control base asphalt and SBS modified asphalt. A ranking between the binder MSCR and mixture fracture test results was conducted to check if the MSCR result was representative of the mixture’s fatigue resistance. Results indicate that the MSCR test at intermediate temperatures (20 °C, 25 °C, and 30 °C) can be performed with good repetitions. It was also found that the MSCR test was sensitive enough to differentiate the fatigue resistance among different binder types and additive contents. The ranking analysis shows that the binder MSCR test at intermediate temperatures showed a similar ranking to the mixture’s fatigue tests, indicating that the binder MSCR test could be potentially utilized to represent a mixture’s fatigue resistance where binder selection is a major concern. It was also found that the SBS modified binder showed the best crack resistance and was less affected by aging. Full article

(This article belongs to the Special Issue Achievements and Prospects of Functional Pavement: Materials and Structures)

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13 pages, 3888 KiB

Open AccessArticle

Feasibility of Using Graphene Oxide Nanoflake (GONF) as Additive of Cement Composite

by Jinwoo An¹, Matthew McInnis², Wonseok Chung^3,* and Boo Hyun Nam^1,*

¹ Department of Civil, Environmental, and Construction Engineering, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL 32816, USA

² Manager of Applied Technology, Garmor Inc. 6317 McCoy Road. Suite 100, Orlando, FL 32822, USA

³ Department of Civil Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Korea

Appl. Sci. 2018, 8(3), 419; https://doi.org/10.3390/app8030419 - 12 Mar 2018

Cited by 36 | Viewed by 5846

Abstract

The object of this study is to investigate the feasibility of ball-milled graphene oxide nanoflakes (GONFs) produced by a mechanochemical process as an additive in Ordinary Portland Cement (OPC)-based paste and concrete. Different percentages of GONFs (0.01–1 wt. %) were added in OPC [...] Read more.

The object of this study is to investigate the feasibility of ball-milled graphene oxide nanoflakes (GONFs) produced by a mechanochemical process as an additive in Ordinary Portland Cement (OPC)-based paste and concrete. Different percentages of GONFs (0.01–1 wt. %) were added in OPC paste mix to find the optimum content of GONF in GONF-combined cement composites. To investigate the effect of the changes in the mix design on OPC paste, two mix design methods were employed: (1) Dry-mix, where GONFs and OPC powders are mixed prior to paste formation and (2) Wet-mix, where sonicated GONFs solution is used as the pour water with OPC paste mix. Data from mechanical tests (compressive and flexural tests) showed that OPC paste incorporating 0.05% GONF resulted in the highest strength for OPC paste. The results of strength tests indicated that Dry-mix is competitive as compared with Wet-mix. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) was used to identify GONFs inside products of cement hydration. To explore the practicality of using GONF in concrete, concrete specimens were made, cured and tested with different percentages of dry-mixed GONFs (0.01–0.1 wt. %). The result of strength test showed that GONF improves the compressive and flexural strengths of concrete around 15% with 0.01 wt. % GONF. Full article

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

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11 pages, 1116 KiB

Open AccessArticle

Molecular Characterization and Theoretical Calculation of Plant Growth Regulators Based on Terahertz Time-Domain Spectroscopy

by Fangfang Qu^1,2, Lei Lin^1,2, Chengyong Cai^1,2, Tao Dong^1,2, Yong He^1,2

and Pengcheng Nie^1,2,3,*

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China

² Key Laboratory of Sensors Sensing, Ministry of Agriculture, Zhejiang University, Hangzhou 310058, China

³ State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058, China

Appl. Sci. 2018, 8(3), 420; https://doi.org/10.3390/app8030420 - 12 Mar 2018

Cited by 23 | Viewed by 5099

Abstract

Terahertz (THz), as an advanced spectral technology, has unique absorption characteristics for most biological macromolecules. In this work, the theoretical fundamentals for the application of THz time-domain spectroscopy (THz-TDS) to molecular characterization and fingerprint peak detection of three plant growth regulators (PGRs), including [...] Read more.

Terahertz (THz), as an advanced spectral technology, has unique absorption characteristics for most biological macromolecules. In this work, the theoretical fundamentals for the application of THz time-domain spectroscopy (THz-TDS) to molecular characterization and fingerprint peak detection of three plant growth regulators (PGRs), including 2,4-Dichlorophenoxyacetic acid (2,4-D), forchlorfenuron (CPPU) and indole-3-acetic acid (IAA) were researched. Meanwhile, the effects of eight types of window functions on THz spectra were studied when converting time-domain spectra into frequency-domain spectra by Fourier transform. Based on the optimal window function, the THz absorption coefficient and refractive index of PGRs in frequencies of 0.2–3 THz were extracted. The molecule structure and vibration mode of three PGR samples were simulated by using density functional theory (DFT). The results showed that the three PGRs had different fingerprint peaks. Characteristic absorption and anomalous dispersion of 2,4-D were found at 1.35, 1.57 and 2.67 THz, those of CPPU were found at 1.77 and 2.44 THz, and the absorption peak of IAA was located at 2.5 THz. The absorption peaks obtained from THz spectra were identified according to the theoretical calculation results of DFT. These fingerprint peaks in THz spectra were generated by the interior stretching vibration and external deformation vibration of molecular groups. The experimental results revealed the feasibility of identifying PGRs species and detecting residues using THz-TDS. Full article

(This article belongs to the Special Issue Laser Processing for Bioengineering Applications)

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15 pages, 1202 KiB

Open AccessArticle

Throughput Maximization Using an SVM for Multi-Class Hypothesis-Based Spectrum Sensing in Cognitive Radio

by Sana Ullah Jan

, Van-Hiep Vu and Insoo Koo^*

School of Electrical Engineering, University of Ulsan, Ulsan 44610, Korea

Appl. Sci. 2018, 8(3), 421; https://doi.org/10.3390/app8030421 - 12 Mar 2018

Cited by 21 | Viewed by 4732

Abstract

A framework of spectrum sensing with a multi-class hypothesis is proposed to maximize the achievable throughput in cognitive radio networks. The energy range of a sensing signal under the hypothesis that the primary user is absent (in a conventional two-class hypothesis) is further [...] Read more.

A framework of spectrum sensing with a multi-class hypothesis is proposed to maximize the achievable throughput in cognitive radio networks. The energy range of a sensing signal under the hypothesis that the primary user is absent (in a conventional two-class hypothesis) is further divided into quantized regions, whereas the hypothesis that the primary user is present is conserved. The non-radio frequency energy harvesting-equiped secondary user transmits, when the primary user is absent, with transmission power based on the hypothesis result (the energy level of the sensed signal) and the residual energy in the battery: the lower the energy of the received signal, the higher the transmission power, and vice versa. Conversely, the lower is the residual energy in the node, the lower is the transmission power. This technique increases the throughput of a secondary link by providing a higher number of transmission events, compared to the conventional two-class hypothesis. Furthermore, transmission with low power for higher energy levels in the sensed signal reduces the probability of interference with primary users if, for instance, detection was missed. The familiar machine learning algorithm known as a support vector machine (SVM) is used in a one-versus-rest approach to classify the input signal into predefined classes. The input signal to the SVM is composed of three statistical features extracted from the sensed signal and a number ranging from 0 to 100 representing the percentage of residual energy in the node’s battery. To increase the generalization of the classifier, k-fold cross-validation is utilized in the training phase. The experimental results show that an SVM with the given features performs satisfactorily for all kernels, but an SVM with a polynomial kernel outperforms linear and radial-basis function kernels in terms of accuracy. Furthermore, the proposed multi-class hypothesis achieves higher throughput compared to the conventional two-class hypothesis for spectrum sensing in cognitive radio networks. Full article

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8 pages, 943 KiB

Open AccessArticle

Implications of Rigid Gripping Constraints on Clubhead Dynamics in Steel Golf Shafts

by Tom W. Corke^1,2, Nils F. Betzler^2,3, Eric S. Wallace¹, Martin Strangwood⁴ and Steve R. Otto^2,*

¹ Sport and Exercise Sciences Research Institute, Ulster University, Newtownabbey BT37 0QB, UK

² R&A Rules Ltd., St. Andrews KY16 9JD, UK

³ Qualisys AB, Kvarnbergsgatan 2, 411 05 Gothenburg, Sweden

⁴ School of Metallurgy & Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Appl. Sci. 2018, 8(3), 422; https://doi.org/10.3390/app8030422 - 12 Mar 2018

Cited by 2 | Viewed by 3672

Abstract

Research and equipment testing with golf robots offers much greater control and manipulation of experimental variables compared to tests using human golfers. However, whilst it is acknowledged that the club gripping mechanism of a robot is dissimilar to that of a human, there [...] Read more.

Research and equipment testing with golf robots offers much greater control and manipulation of experimental variables compared to tests using human golfers. However, whilst it is acknowledged that the club gripping mechanism of a robot is dissimilar to that of a human, there appears to be no scientific findings on the effects of these gripping differences on the clubhead at ball impact. Theoretical and experimental strain propagation rates from the clubhead to the grip and back to the clubhead were determined during robot testing with a 9-iron to determine if this time interval was sufficiently short to permit the gripping mechanism to have an effect on the clubhead during impact. Longitudinal strain appears to propagate the most quickly, but such deflections are likely to be small and therefore of little meaningful consequence. Shaft bending was not a primary concern as modes of large enough amplitude appear to propagate too slowly to be relevant. Torsional strain propagates at a rate which suggests that constraints at the grip end of a golf club could potentially influence impact dynamics for steel shafted irons; however, this effect seems unlikely to be significant, a likelihood that decreases further for longer irons. As such, it is considered reasonable to treat the influence of a robot’s gripping mechanism on clubhead dynamics at impact as negligible, and therefore comparisons between robot and human data in this regard are valid. Full article

(This article belongs to the Special Issue Sports Materials)

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10 pages, 2748 KiB

Open AccessArticle

A Study on the Influence of Stage Load on Health Monitoring of Axial Concrete Members Using Piezoelectric Based Smart Aggregate

by Chengcheng Du, Dujian Zou, Tiejun Liu^*

and Weijie Li

Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China

Appl. Sci. 2018, 8(3), 423; https://doi.org/10.3390/app8030423 - 12 Mar 2018

Cited by 6 | Viewed by 3322

Abstract

Piezoceramic based smart aggregate (SA) has been employed to monitor the strength development of early age concrete. The validity of SA-based active sensing method was tested and verified with loading and unloading conditions. However, the early age concrete in buildings is subjected to [...] Read more.

Piezoceramic based smart aggregate (SA) has been employed to monitor the strength development of early age concrete. The validity of SA-based active sensing method was tested and verified with loading and unloading conditions. However, the early age concrete in buildings is subjected to many load increments during the construction process. The influence of incremental load on the properties of the propagating waves is still unclear. This study aims to investigate the effects of axial stage loads on the signal response of the SA. The concrete specimens that are embedded with SA’s were loaded step by step, and the amplitude and wave velocity of the sensing signals were measured at each stress state. The experimental results indicated that the amplitude of the received signal decrease with the increase of the stress level. As for the velocity of the propagated stress wave, however, the velocity shows an increasing trend before a sharp decline at high stress level. Full article

(This article belongs to the Section Mechanical Engineering)

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10 pages, 2223 KiB

Open AccessArticle

Temperature-Dependent Electrical Properties of Al₂O₃-Passivated Multilayer MoS₂ Thin-Film Transistors

by Seok Hwan Jeong, Na Liu, Heekyeong Park, Young Ki Hong^*

and Sunkook Kim^*

School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 16419, Korea

Appl. Sci. 2018, 8(3), 424; https://doi.org/10.3390/app8030424 - 12 Mar 2018

Cited by 24 | Viewed by 9092

Abstract

It is becoming more important for electronic devices to operate stably and reproducibly under harsh environments, such as extremely low and/or high temperatures, for robust and practical applications. Here, we report on the effects of atomic-layer-deposited (ALD) aluminum oxide (Al₂O₃ [...] Read more.

It is becoming more important for electronic devices to operate stably and reproducibly under harsh environments, such as extremely low and/or high temperatures, for robust and practical applications. Here, we report on the effects of atomic-layer-deposited (ALD) aluminum oxide (Al₂O₃) passivation on multilayer molybdenum disulfide (MoS₂) thin-film transistors (TFTs) and their temperature-dependent electrical properties, especially at a high temperature range from 293 K to 380 K. With the aid of ultraviolet-ozone treatment, an Al₂O₃ layer was uniformly applied to cover the entire surface of MoS₂ TFTs. Our Al₂O₃-passivated MoS₂ TFTs exhibited not only a dramatic reduction of hysteresis but also enhancement of current in output characteristics. In addition, we investigated the temperature-dependent behaviors of the TFT performance, including intrinsic carrier mobility based on the Y-function method. Full article

(This article belongs to the Special Issue Thin-Film Transistor)

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14 pages, 7896 KiB

Open AccessArticle

Potential of TCPInSAR in Monitoring Linear Infrastructure with a Small Dataset of SAR Images: Application of the Donghai Bridge, China

by Lei Zhang¹

, Qian Sun^2,3,* and Jun Hu⁴

¹ Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong 999077, China

² College of Resources and Environmental Science, Hunan Normal University, No. 36 Lushan Road, Changsha 410081, China

³ Key Laboratory of Geospatial Big Data Mining and Application, Hunan Province, Changsha 410081, China

⁴ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

Appl. Sci. 2018, 8(3), 425; https://doi.org/10.3390/app8030425 - 19 Mar 2018

Cited by 27 | Viewed by 5832

Abstract

Reliably monitoring deformation associated with linear infrastructures, such as long-span bridges, is vitally important to assess their structural health. In this paper, we attempt to employ satellite interferometric synthetic aperture radar (InSAR) to map the deformation of Donghai Bridge over a half of [...] Read more.

Reliably monitoring deformation associated with linear infrastructures, such as long-span bridges, is vitally important to assess their structural health. In this paper, we attempt to employ satellite interferometric synthetic aperture radar (InSAR) to map the deformation of Donghai Bridge over a half of an annual cycle. The bridge, as the fourth longest cross-sea bridge in the world, located in the north of Hangzhou Bay, East China Sea where the featureless sea surface largely occupied the radar image raises challenges to accurately co-register the coherent points along the bridge. To tackle the issues due to co-registration and the limited number of synthetic aperture radar (SAR) images, we adopt the termed temporarily-coherent point (TCP) InSAR (TCPInSAR) technique to process the radar images. TCPs that are not necessarily coherent during the whole observation period can be identified within every two SAR acquisitions during the co-registration procedure based on the statistics of azimuth and range offsets. In the process, co-registration is performed only using the offsets of these TCPs, leading to improved interferometric phases and the local Delaunay triangulation is used to construct point pairs to reduce the atmospheric artifacts along the bridge. With the TCPInSAR method the deformation rate along the bridge is estimated with no need of phase unwrapping. The achieved result reveals that the Donghai Bridge suffered a line-of-sight (LOS) deformation rate up to −2.3 cm/year from January 2009 to July 2009 at the cable-stayed part, which is likely due to the thermal expansion of cables. Full article

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12 pages, 1846 KiB

Open AccessArticle

Cross-Cultural Perception of Spanish Synthetic Expressive Voices Among Asians

by Ganapreeta Renunathan Naidu¹

, Syaheerah Lebai Lutfi^1,*, Amal Abdulrahman Azazi¹, Jaime Lorenzo-Trueba² and Juan Manuel Montero Martinez²

¹ School of Computer Sciences, University Sains Malaysia, Gelugor 11800, Pulau Pinang, Malaysia

² Speech Technology Group, ETSI Telecomunicacion, Universidad Politécnica de Madrid, Calle Ramiro de Maeztu, 7, 28040 Madrid, Spain

Appl. Sci. 2018, 8(3), 426; https://doi.org/10.3390/app8030426 - 12 Mar 2018

Cited by 2 | Viewed by 3680

Abstract

Nonverbal cues play a vital role in contributing to how emotions are perceived, especially by outgroups. In this study, a cross-cultural perception experiment of Spanish Synthetic Expressive Voices (SEV) was conducted to investigate the perception rate among different groups of Asians towards the [...] Read more.

Nonverbal cues play a vital role in contributing to how emotions are perceived, especially by outgroups. In this study, a cross-cultural perception experiment of Spanish Synthetic Expressive Voices (SEV) was conducted to investigate the perception rate among different groups of Asians towards the SEV. Ten (10) subjects from each ethnic group namely Japanese, Chinese, Vietnamese, and Malaysians participated in this test. The subjects were required to listen to and categorize the SEV corpus which contains 260 utterances with 4 emotions (anger, happiness, sadness, and surprise) and the neutral speech in different intensities and durations. Overall, the results indicate that duration and intensity of speech plays a significant role in perception. This paper concludes that listeners’ perceptions are influenced by a speaker’s nonverbal expression and it is important that these features (duration and intensity of speech) are considered when modelling synthetic speech for artificial agents in real-time applications in a cross-cultural user environment. Full article

(This article belongs to the Section Acoustics and Vibrations)

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17 pages, 1953 KiB

Open AccessArticle

Forward and Inverse Studies on Scattering of Rayleigh Wave at Surface Flaws

by Bin Wang, Yihui Da and Zhenghua Qian^*

State Key Laboratory of Mechanics and Control of Mechanical Structures/College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

Appl. Sci. 2018, 8(3), 427; https://doi.org/10.3390/app8030427 - 12 Mar 2018

Cited by 5 | Viewed by 3529

Abstract

The Rayleigh wave has been frequently applied in geological seismic inspection and ultrasonic non-destructive testing, due to its low attenuation and dispersion. A thorough and effective utilization of Rayleigh wave requires better understanding of its scattering phenomenon. The paper analyzes the scattering of [...] Read more.

The Rayleigh wave has been frequently applied in geological seismic inspection and ultrasonic non-destructive testing, due to its low attenuation and dispersion. A thorough and effective utilization of Rayleigh wave requires better understanding of its scattering phenomenon. The paper analyzes the scattering of Rayleigh wave at the canyon-shaped flaws on the surface, both in forward and inverse aspects. Firstly, we suggest a modified boundary element method (BEM) incorporating the far-field displacement patterns into the traditional BEM equation set. Results show that the modified BEM is an efficient and accurate approach for calculating far-field reflection coefficients. Secondly, we propose an inverse reconstruction procedure for the flaw shape using reflection coefficients of Rayleigh wave. By theoretical deduction, it can be proved that the objective function of flaw depth d(x₁) is approximately expressed as an inverse Fourier transform of reflection coefficients in wavenumber domain. Numerical examples are given by substituting the reflection coefficients obtained from the forward analysis into the inversion algorithm, and good agreements are shown between the reconstructed flaw images and the geometric characteristics of the actual flaws. Full article

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

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20 pages, 889 KiB

Open AccessArticle

A Novel Network Security Risk Assessment Approach by Combining Subjective and Objective Weights under Uncertainty

by Yancui Duan, Yonghua Cai, Zhikang Wang and Xinyang Deng^*

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

Appl. Sci. 2018, 8(3), 428; https://doi.org/10.3390/app8030428 - 13 Mar 2018

Cited by 18 | Viewed by 5428

Abstract

Nowadays, computer networks are playing a more and more important role in people’s daily lives. Meanwhile, the security of computer networks has also attracted widespread concern. However, up to now, there is no universal and effective assessment approach for computer network security. Therefore, [...] Read more.

Nowadays, computer networks are playing a more and more important role in people’s daily lives. Meanwhile, the security of computer networks has also attracted widespread concern. However, up to now, there is no universal and effective assessment approach for computer network security. Therefore, a novel network security risk assessment approach by combining subjective and objective weights under uncertainty is proposed. In the proposed evaluation approach, the uncertainty of evaluation data is taken into account, which is translated into objective weights through an uncertainty measure. By combining the subjective weights of evaluation criteria and the objective weights of evaluation data, the final weights can be obtained. Then, Dempster–Shafer (D-S) evidence theory and pignistic probability transformation (PPT) are employed to derive a consensus decision for the degree of the network security risk. Two illustrative examples are given to show the efficiency of the proposed approach. This approach of risk assessment, which combines subjective and objective weights, can not only effectively evaluate computer network security, but also be widely used in decision-making. Full article

(This article belongs to the Special Issue Security and Privacy for Cyber Physical Systems)

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19 pages, 6826 KiB

Open AccessArticle

A PSF-Shape-Based Beamforming Strategy for Robust 2D Motion Estimation in Ultrafast Data

by Anne E. C. M. Saris^1,*

, Stein Fekkes¹

, Maartje M. Nillesen¹, Hendrik H. G. Hansen¹

and Chris L. De Korte^1,2

¹ Medical Ultra Sound Imaging Center, Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands

² Physics of Fluids Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

Appl. Sci. 2018, 8(3), 429; https://doi.org/10.3390/app8030429 - 13 Mar 2018

Cited by 14 | Viewed by 4166

Abstract

This paper presents a framework for motion estimation in ultrafast ultrasound data. It describes a novel approach for determining the sampling grid for ultrafast data based on the system’s point-spread-function (PSF). As a consequence, the cross-correlation functions (CCF) used in the speckle tracking [...] Read more.

This paper presents a framework for motion estimation in ultrafast ultrasound data. It describes a novel approach for determining the sampling grid for ultrafast data based on the system’s point-spread-function (PSF). As a consequence, the cross-correlation functions (CCF) used in the speckle tracking (ST) algorithm will have circular-shaped peaks, which can be interpolated using a 2D interpolation method to estimate subsample displacements. Carotid artery wall motion and parabolic blood flow simulations together with rotating disk experiments using a Verasonics Vantage 256 are used for performance evaluation. Zero-degree plane wave data were acquired using an ATL L5-12 (f_c = 9 MHz) transducer for a range of pulse repetition frequencies (PRFs), resulting in 0–600 µm inter-frame displacements. The proposed methodology was compared to data beamformed on a conventionally spaced grid, combined with the commonly used 1D parabolic interpolation. The PSF-shape-based beamforming grid combined with 2D cubic interpolation showed the most accurate and stable performance with respect to the full range of inter-frame displacements, both for the assessment of blood flow and vessel wall dynamics. The proposed methodology can be used as a protocolled way to beamform ultrafast data and obtain accurate estimates of tissue motion. Full article

(This article belongs to the Special Issue Ultrafast Ultrasound Imaging)

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28 pages, 13256 KiB

Open AccessArticle

Research on the Hygroscopicity of a Composite Hygroscopic Material and its Influence on Indoor Thermal and Humidity Environment

by Huahui Xie¹, Guangcai Gong^1,*, Yi Wu², Yongchao Liu¹ and Yingjuan Wang¹

¹ College of Civil Engineering, Hunan University, Changsha 410006, China

² College of Engineering, Hunan Agriculture University, Changsha 410128, China

Appl. Sci. 2018, 8(3), 430; https://doi.org/10.3390/app8030430 - 13 Mar 2018

Cited by 14 | Viewed by 5103

Abstract

Indoor air humidity is closely related to daily life and productivity. It is necessary to develop new materials which can maintain the indoor humidity environment steady within an acceptable range of 40–70%. In this paper a new composite hygroscopic material composed of wood [...] Read more.

Indoor air humidity is closely related to daily life and productivity. It is necessary to develop new materials which can maintain the indoor humidity environment steady within an acceptable range of 40–70%. In this paper a new composite hygroscopic material composed of wood fibre and sepiolite with expanded perlite (CHM-WSE) is used in a building envelope to evaluate its moisture buffering performance. A series of experiments assessing the microstructure, hygroscopicity, mechanical and thermodynamic properties of the new composite hygroscropic material have been executed. Furthermore, a numerical model for predicting the influence of humidity environment and energy consumption on composite hygroscopic mortar in different climatic regions has been established. The experiments show that the indoor moisture buffering performance in late spring is better than that in winter, when the practical moisture buffering performance can reach at 0.89 g/(m²%RH)@8/16h; and the non-uniformity coefficient of indoor relative humidity is about 0.006. The simulation results show that a room with CHM-WSE is more comfortable than a common mortar (CM) room, and it has better energy-saving performance in the hot summer and cold winter (HSCW) region in China. The experiments and simulations show that the developed hygroscopic material could be feasible for application in buildings. Full article

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

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17 pages, 8627 KiB

Open AccessArticle

A 1064 nm Dispersive Raman Spectral Imaging System for Food Safety and Quality Evaluation

by Kuanglin Chao^1,*, Sagar Dhakal¹, Jianwei Qin¹, Moon Kim¹ and Yankun Peng²

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

² National R&D Centre for Agro-Processing, China Agricultural University, 17 Qinghua East Road, Beijing 100083, China

Appl. Sci. 2018, 8(3), 431; https://doi.org/10.3390/app8030431 - 13 Mar 2018

Cited by 27 | Viewed by 7481

Abstract

Raman spectral imaging is an effective method to analyze and evaluate the chemical composition and structure of a sample, and has many applications for food safety and quality research. This study developed a 1064 nm dispersive Raman spectral imaging system for surface and [...] Read more.

Raman spectral imaging is an effective method to analyze and evaluate the chemical composition and structure of a sample, and has many applications for food safety and quality research. This study developed a 1064 nm dispersive Raman spectral imaging system for surface and subsurface analysis of food samples. A 1064 nm laser module is used for sample excitation. A bifurcated optical fiber coupled with Raman probe is used to focus excitation laser on the sample and carry scattering signal to the spectrograph. A high throughput volume phase grating disperses the incoming Raman signal. A 512 pixels Indium-Gallium-Arsenide (InGaAs) detector receives the dispersed light signal. A motorized positioning table moves the sample in two-axis directions, accumulating hyperspectral image of the sample by the point-scan method. An interface software was developed in-house for parameterization, data acquisition, and data transfer. The system was spectrally calibrated using naphthalene and polystyrene. It has the Raman shift range of 142 to 1820 cm⁻¹, the spectral resolution of 12 cm⁻¹ at full width half maximum (FWHM). The spatial resolution of the system was evaluated using a standard resolution glass test chart. It has the spatial resolution of 0.1 mm. The application of the system was demonstrated by surface and subsurface detection of metanil yellow contamination in turmeric powder. Results indicate that the 1064 nm dispersive Raman spectral imaging system is a useful tool for food safety and quality evaluation. Full article

(This article belongs to the Special Issue Hyper- and Multi-Spectral Imaging)

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20 pages, 4609 KiB

Open AccessArticle

A Virtual Power Plant Architecture for the Demand-Side Management of Smart Prosumers

by Marco Pasetti^1,*

, Stefano Rinaldi¹

and Daniele Manerba²

¹ Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy

² Department of Control and Computer Engineering and ICT for City Logistics and Enterprise Lab, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino, Italy

Appl. Sci. 2018, 8(3), 432; https://doi.org/10.3390/app8030432 - 13 Mar 2018

Cited by 122 | Viewed by 15133

Abstract

In this paper, we present a conceptual study on a Virtual Power Plant (VPP) architecture for the optimal management of Distributed Energy Resources (DERs) owned by prosumers participating in Demand-Side Management (DSM) programs. Compared to classical VPP architectures, which aim to aggregate several [...] Read more.

In this paper, we present a conceptual study on a Virtual Power Plant (VPP) architecture for the optimal management of Distributed Energy Resources (DERs) owned by prosumers participating in Demand-Side Management (DSM) programs. Compared to classical VPP architectures, which aim to aggregate several DERs dispersed throughout the electrical grid, in the proposed VPP architecture the supervised physical domain is limited to single users, i.e., to single Points of Delivery (PODs) of the distribution network. The VPP architecture is based on a service-oriented approach, where multiple agents cooperate to implement the optimal management of the prosumer’s assets, by also considering different forms of Demand Response (DR) requests. The considered DR schemes range from Price-Based DRs to Event-Based DRs, covering both the normal operating functions and the emergency control requests applied in modern distribution networks. With respect to centralized approaches, in this study the control perspective is moved from the system level to the single prosumer’s level, who is allowed to independently provide flexible power profiles through the aggregation of multiple DERs. A generalized optimization model, formulated as a Mixed-Integer Linear Programming (MILP) problem, is also introduced. Such a model is able to compute the optimal scheduling of a prosumer’s assets by considering both DR requests and end-users’ requirements in terms of comfort levels while minimizing the costs. Full article

(This article belongs to the Special Issue Progress in Virtual Power Plant Design and Applications)

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14 pages, 606 KiB

Open AccessArticle

Gauge-Invariant Formulation of Time-Dependent Configuration Interaction Singles Method

by Takeshi Sato^1,2

, Takuma Teramura¹

and Kenichi L. Ishikawa^1,2,*

¹ Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

² Photon Science Center, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Appl. Sci. 2018, 8(3), 433; https://doi.org/10.3390/app8030433 - 13 Mar 2018

Cited by 16 | Viewed by 4120

Abstract

We propose a gauge-invariant formulation of the channel orbital-based time-dependent configuration interaction singles (TDCIS) method [Phys. Rev. A, 74, 043420 (2006)], one of the powerful ab initio methods to investigate electron dynamics in atoms and molecules subject to an external laser field. In [...] Read more.

We propose a gauge-invariant formulation of the channel orbital-based time-dependent configuration interaction singles (TDCIS) method [Phys. Rev. A, 74, 043420 (2006)], one of the powerful ab initio methods to investigate electron dynamics in atoms and molecules subject to an external laser field. In the present formulation, we derive the equations of motion (EOMs) in the velocity gauge using gauge-transformed time-dependent, not fixed, orbitals that are equivalent to the conventional EOMs in the length gauge using fixed orbitals. The new velocity-gauge EOMs avoid the use of the length-gauge dipole operator, which diverges at large distance, and allows us to exploit computational advantages of the velocity-gauge treatment over the length-gauge one, e.g., a faster convergence in simulations with intense and long-wavelength lasers, and the feasibility of exterior complex scaling as an absorbing boundary. The reformulated TDCIS method is applied to an exactly solvable model of one-dimensional helium atom in an intense laser field to numerically demonstrate the gauge invariance. We also discuss the consistent method for evaluating the time derivative of an observable, which is relevant, e.g., in simulating high-harmonic generation. Full article

(This article belongs to the Special Issue Attosecond Science and Technology: Principles and Applications)

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24 pages, 14502 KiB

Open AccessArticle

Study on Actuator Line Modeling of Two NREL 5-MW Wind Turbine Wakes

by Ziying Yu¹, Xing Zheng^1,* and Qingwei Ma^1,2

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

² School of Mathematics, Computer Sciences & Engineering, City, University of London, London EC1V 0HB, UK

Appl. Sci. 2018, 8(3), 434; https://doi.org/10.3390/app8030434 - 13 Mar 2018

Cited by 43 | Viewed by 6262

Abstract

The wind turbine wakes impact the efficiency and lifespan of the wind farm. Therefore, to improve the wind plant performance, research on wind plant control is essential. The actuator line model (ALM) is proposed to simulate the wind turbine efficiently. This research investigates [...] Read more.

The wind turbine wakes impact the efficiency and lifespan of the wind farm. Therefore, to improve the wind plant performance, research on wind plant control is essential. The actuator line model (ALM) is proposed to simulate the wind turbine efficiently. This research investigates the National Renewable Energy Laboratory 5 Million Watts (NREL 5-MW) wind turbine wakes with Open Field Operation and Manipulation (OpenFOAM) using ALM. Firstly, a single NREL 5-MW turbine is simulated. The comparison of the power and thrust with Fatigue, Aerodynamics, Structures, and Turbulence (FAST) shows a good agreement below the rated wind speed. The information relating to wind turbine wakes is given in detail. The top working status is proved at the wind speed of 8 m/s and the downstream distance of more than 5 rotor diameters (5D). Secondly, another case with two NREL 5-MW wind turbines aligned is also carried out, in which 7D is validated as the optimum distance between the two turbines. The result also shows that the upstream wind turbine has an obvious influence on the downstream one. Full article

(This article belongs to the Section Mechanical Engineering)

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13 pages, 4923 KiB

Open AccessArticle

Study of the Ultimate Error of the Axis Tolerance Feature and Its Pose Decoupling Based on an Area Coordinate System

by Qungui Du^1,2, Xiaochen Zhai^1,3,*

and Qi Wen^1,2

¹ School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou 510640, China

² Guangdong Provincial Key Laboratory of Automotive Engineering, Guangzhou 510640, China

³ State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China

Appl. Sci. 2018, 8(3), 435; https://doi.org/10.3390/app8030435 - 13 Mar 2018

Cited by 6 | Viewed by 3106

Abstract

Manufacturing error and assembly error should be taken into consideration during evaluation and analysis of accurate product performance in the design phase. Traditional tolerance analysis methods establish error propagation model based on dimension chains with tolerance values being regarded as error boundaries, and [...] Read more.

Manufacturing error and assembly error should be taken into consideration during evaluation and analysis of accurate product performance in the design phase. Traditional tolerance analysis methods establish error propagation model based on dimension chains with tolerance values being regarded as error boundaries, and obtain the limit of target feature error through optimization methods or conducting statistical analysis with the tolerance domain being the boundary. As deviations of the tolerance feature (TF) on degrees of freedom (DOF) have coupling relations, accurate deviations on all DOF may not be obtained, even though these deviations constitute the basis for product performance analysis. Therefore, taking the widely used shaft-hole fit as an example, a pose decoupling model of the axis TF was proposed based on an area coordinate system. This model realized decoupling analysis of any pose of the axis TF within the tolerance domain. As proposed by the authors, by combining a tolerance analysis model based on tracking local coordinate systems, ultimate pose analysis of the closed-loop system, namely the target feature, as well as statistical analysis could be further implemented. This method contributed to analysis of true product performance with arbitrary error in the product design phase from the angle of tolerance, therefore, shortening the product research and development cycle. This method is demonstrated through applying it to a real-life example. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 1174 KiB

Open AccessArticle

Constraint-Based Time-Scale Modification of Music Recordings for Noise Beautification

by Meinard Müller^1,*

, Helmut Hedwig¹, Frank Zalkow¹

and Stefan Popescu²

¹ International Audio Laboratories Erlangen, 91058 Erlangen, Germany

² Siemens Healthcare GmbH, 91052 Erlangen, Germany

Appl. Sci. 2018, 8(3), 436; https://doi.org/10.3390/app8030436 - 14 Mar 2018

Viewed by 4442

Abstract

In magnetic resonance imaging (MRI), a patient is exposed to beat-like knocking sounds, often interrupted by periods of silence, which are caused by pulsing currents of the MRI scanner. In order to increase the patient’s comfort, one strategy is to play back ambient [...] Read more.

In magnetic resonance imaging (MRI), a patient is exposed to beat-like knocking sounds, often interrupted by periods of silence, which are caused by pulsing currents of the MRI scanner. In order to increase the patient’s comfort, one strategy is to play back ambient music to induce positive emotions and to reduce stress during the MRI scanning process. To create an overall acceptable acoustic environment, one idea is to adapt the music to the locally periodic acoustic MRI noise. Motivated by this scenario, we consider in this paper the general problem of adapting a given music recording to fulfill certain temporal constraints. More concretely, the constraints are given by a reference time axis with specified time points (e.g., the time positions of the MRI scanner’s knocking sounds). Then, the goal is to temporally modify a suitable music recording such that its beat positions align with the specified time points. As one technical contribution, we model this alignment task as an optimization problem with the objective to fulfill the constraints while avoiding strong local distortions in the music. Furthermore, we introduce an efficient algorithm based on dynamic programming for solving this task. Based on the computed alignment, we use existing time-scale modification procedures for locally adapting the music recording. To illustrate the outcome of our procedure, we discuss representative synthetic and real-world examples, which can be accessed via an interactive website. In particular, these examples indicate the potential of automated methods for noise beautification within the MRI application scenario. Full article

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

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13 pages, 1946 KiB

Open AccessArticle

Non-Invasive Assessment of Hepatic Fibrosis by Elastic Measurement of Liver Using Magnetic Resonance Tagging Images

by Xuejun Zhang^1,3,*

, Xiangrong Zhou², Takeshi Hara² and Hiroshi Fujita²

¹ School of Computer and Electronic Information, Guangxi University, Nanning 530004, Guangxi, China

² Department of Electrical, Electronic and Computer Engineering, Gifu University, Gifu 501-1193, Japan

³ Guangxi Key Laboratory of Multimedia Communications and Network Technology, Nanning 530004, Guangxi, China

Appl. Sci. 2018, 8(3), 437; https://doi.org/10.3390/app8030437 - 14 Mar 2018

Cited by 3 | Viewed by 3685

Abstract

To date, the measurement of the stiffness of liver requires a special vibrational tool that limits its application in many hospitals. In this study, we developed a novel method for automatically assessing the elasticity of the liver without any use of contrast agents [...] Read more.

To date, the measurement of the stiffness of liver requires a special vibrational tool that limits its application in many hospitals. In this study, we developed a novel method for automatically assessing the elasticity of the liver without any use of contrast agents or mechanical devices. By calculating the non-rigid deformation of the liver from magnetic resonance (MR) tagging images, the stiffness was quantified as the displacement of grids on the liver image during a forced exhalation cycle. Our methods include two major processes: (1) quantification of the non-rigid deformation as the bending energy (BE) based on the thin-plate spline method in the spatial domain and (2) calculation of the difference in the power spectrum from the tagging images, by using fast Fourier transform in the frequency domain. By considering 34 cases (17 normal and 17 abnormal liver cases), a remarkable difference between the two groups was found by both methods. The elasticity of the liver was finally analyzed by combining the bending energy and power spectral features obtained through MR tagging images. The result showed that only one abnormal case was misclassified in our dataset, which implied our method for non-invasive assessment of liver fibrosis has the potential to reduce the traditional liver biopsy. Full article

(This article belongs to the Special Issue Ultrasound Elastography)

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10 pages, 1569 KiB

Open AccessArticle

Treatment of Mineral Oil Refinery Wastewater in Microbial Fuel Cells Using Ionic Liquid Based Separators

by Hasna Addi^1,2, Francisco Mateo-Ramírez¹, Víctor Manuel Ortiz-Martínez¹, María José Salar-García¹, Francisco José Hernández-Fernández^1,*, Antonia Pérez de los Ríos^3,*, Carlos Godínez¹, El Mostapha Lotfi², Mohammed El Mahi² and Luis Javier Lozano Blanco¹

¹ Department of Chemical and Environmental Engineering, Regional Campus of International Excellence “Campus Mare Nostrum”, Technical University of Cartagena, Campus La Muralla, E-30202 Cartagena, Murcia, Spain

² Laboratory of Mechanics, Processes and Industrial Process (LM2PI), Chemical Sciences Team, Higher School of Technical Education of Rabat (ENSET), Mohammed V University in Rabat, Rabat 10100 B.P. 6207, Morocco

³ Department of Chemical Engineering, Regional Campus of International Excellence “Campus Mare Nostrum”, University of Murcia, Campus de Espinardo, E-30100 Murcia, Spain

Appl. Sci. 2018, 8(3), 438; https://doi.org/10.3390/app8030438 - 14 Mar 2018

Cited by 17 | Viewed by 4903

Abstract

Microbial fuel cells (MFCs) are an environmentally friendly technology that can recover electricity directly from several wastes at ambient temperatures. This work explores the use of mineral oil refinery wastewater as feedstock in single-chamber air-cathode MFC devices. A polymer inclusion membrane based on [...] Read more.

Microbial fuel cells (MFCs) are an environmentally friendly technology that can recover electricity directly from several wastes at ambient temperatures. This work explores the use of mineral oil refinery wastewater as feedstock in single-chamber air-cathode MFC devices. A polymer inclusion membrane based on the ionic liquid methyltrioctylammonium chloride, [MTOA⁺][Cl⁻], at a concentration of 70% w/w, was used as separator, showing a good efficiency in power production and chemical oxygen demand (COD) removal. The power and the chemical oxygen demand removal reached values of 45 mW/m³ and over 80%, respectively. The evolution of other parameters of the wastewater including nitrites, phosphates and sulphates were also studied. Kjeldahl nitrogen and sulphates were significantly reduced during MFC operation. The results show that mineral oil refinery wastewater can be used as feedstock in air breathing cathode-microbial fuel cells based on polymer ionic liquid inclusion membranes. This configuration could represent a good alternative for wastewater depuration while producing energy during the process. Full article

(This article belongs to the Special Issue Ionic Liquids for Green Chemical Technology)

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9 pages, 2490 KiB

Open AccessArticle

A Tunable CW Orange Laser Based on a Cascaded MgO:PPLN Single-Pass Sum-Frequency Generation Module

by Dismas K. Choge^1,2

, Huai-Xi Chen¹, Bao-Lu Tian¹, Yi-Bin Xu¹, Guang-Wei Li¹ and Wan-Guo Liang^1,*

¹ Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Appl. Sci. 2018, 8(3), 439; https://doi.org/10.3390/app8030439 - 15 Mar 2018

Cited by 4 | Viewed by 3651

Abstract

We report an all-solid-state continuous wave (CW) tunable orange laser based on cascaded single-pass sum-frequency generation with fundamental wavelengths at 1545.7 and 975.2 nm using two quasi-phase-matched (QPM) MgO-doped periodically poled lithium niobate (MgO:PPLN) crystals. Up to 10 mW of orange laser is [...] Read more.

We report an all-solid-state continuous wave (CW) tunable orange laser based on cascaded single-pass sum-frequency generation with fundamental wavelengths at 1545.7 and 975.2 nm using two quasi-phase-matched (QPM) MgO-doped periodically poled lithium niobate (MgO:PPLN) crystals. Up to 10 mW of orange laser is generated in the cascaded module corresponding to a 10.4%/W nonlinear conversion efficiency. The orange output showed a temperature tuning rate of ~0.05 nm/°C, and the beam quality (M²) value of the orange laser was about 2.0. We use this technique to combine the high efficiency offered by uniformly poled crystals and the broad input wavelength acceptance characteristic of step-chirped structures. Full article

(This article belongs to the Section Optics and Lasers)

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13 pages, 1265 KiB

Open AccessFeature PaperArticle

Economic and Environmental Impact of Energy Saving in Healthcare Buildings

by Justo García-Sanz-Calcedo^1,*

, Awf Al-Kassir¹

and Talal Yusaf²

¹ School of Industrial Engineering, University of Extremadura, 06006 Badajoz, Spain

² USQ International, University of Southern Queensland Toowoomba, Darling Heights, QLD 4350, Australia

Appl. Sci. 2018, 8(3), 440; https://doi.org/10.3390/app8030440 - 15 Mar 2018

Cited by 73 | Viewed by 8077

Abstract

The purpose of this article is to estimate the economic and environmental impacts of energy consumption derived from healthcare buildings and proposes several energy-saving options in the sector. An experimental energy consumption study was development between 2005 and 2013 in 12 hospitals and [...] Read more.

The purpose of this article is to estimate the economic and environmental impacts of energy consumption derived from healthcare buildings and proposes several energy-saving options in the sector. An experimental energy consumption study was development between 2005 and 2013 in 12 hospitals and 70 healthcare centres in Spain, built between 1980 and 2005 through audits carried out between 2005 and 2012, performed by the Extremadura Energy Agency. The study focused on electric energy, HVAC, DWH, lighting systems, renewable energies, maintenance strategy, thermal insulation, and optimal building size. Specifically, the following parameters were evaluated: energy savings, investment emission of CO₂, NO₂, and SO₂ gases, and payback. The results revealed that through an appropriate energy management of healthcare buildings it is possible to save up to 8.60 kWh/m² per year, for buildings of less than 5000 m² (with no beds), which represents an expense of 1.55 €/m². In healthcare buildings larger than 5000 m² (with beds), it was possible to save up to 6.88 kWh/m² per year, which represents an expense of 1.25 €/m². Full article

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

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15 pages, 4539 KiB

Open AccessArticle

FPGA Implementation of a BPSK 1D-CNN Demodulator

by Yan Liu¹, Yue Shen¹, Li Li^2,3 and Hai Wang^4,*

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

² School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China

³ China Academy of Space Technology (Xi’an), Xi’an 710100, China

⁴ School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

Appl. Sci. 2018, 8(3), 441; https://doi.org/10.3390/app8030441 - 15 Mar 2018

Cited by 7 | Viewed by 6396

Abstract

In this paper, we propose a field programmable gate array (FPGA) implementation of a one-dimensional convolution neural network (1D-CNN) demodulator for binary phase shift keying (BPSK). The 1D-CNN demodulator includes two 1D-CNNs and a decision module. Discrete time series of BPSK signals are [...] Read more.

In this paper, we propose a field programmable gate array (FPGA) implementation of a one-dimensional convolution neural network (1D-CNN) demodulator for binary phase shift keying (BPSK). The 1D-CNN demodulator includes two 1D-CNNs and a decision module. Discrete time series of BPSK signals are imported into the well-trained 1D-CNNs. The 1D-CNNs detect the phase shifts’ moment and type, including phase shift from 0 to π and that from π to 0. The decision module combines results of the two 1D-CNNs and outputs the demodulated data. In order to improve the efficiency of resource utilization and operation speed of the FPGA circuit, a time-delay network for convolutional calculation and a structure for piecewise approximation for the activation function were designed. To enhance the performance of the 1D-CNN demodulator, universal and diversity training data considering five impact factors were generated specially. Experimental results under different channel conditions show that the proposed demodulator has good adaptability to frequency offset and short latency. The demodulation loss of the proposed demodulator can almost be kept within 2 dB. Full article

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20 pages, 7573 KiB

Open AccessFeature PaperArticle

Microstructure-Based Prediction of the Elastic Behaviour of Hydrating Cement Pastes

by Hadi Mazaheripour¹

, Rui Faria^1,*

, Guang Ye²

, Erik Schlangen²

, José Granja³ and Miguel Azenha³

¹ Civil Engineering Department, Faculty of Engineering, University of Porto (FEUP), 4200-465 Porto, Portugal

² Microlab, Faculty of Civil Engineering & Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands

³ ISISE, Department of Civil Engineering, School of Engineering, University of Minho, 4800-058 Guimarães, Portugal

Appl. Sci. 2018, 8(3), 442; https://doi.org/10.3390/app8030442 - 15 Mar 2018

Cited by 16 | Viewed by 5018

Abstract

The development of the elastic properties of a hardening cement paste results from the microstructural evolution due to cement hydration. The elastic behaviour of cement paste can be predicted by a combination of the hydration model and micromechanical analysis, which originates from a [...] Read more.

The development of the elastic properties of a hardening cement paste results from the microstructural evolution due to cement hydration. The elastic behaviour of cement paste can be predicted by a combination of the hydration model and micromechanical analysis, which originates from a microstructural representative volume where the elastic behaviour of different hydrating cement products can be recognised. In this paper, the formation of the microstructural volume is simulated with the computational code HYMOSTRUC3D for cement hydration. The obtained microstructure is an input for a micromechanical modelling. A 3D regular lattice model is proposed to predict the elastic modulus of the microstructure, considering a water-to-cement (w/c) ratio within the range [0.30–0.50]. In addition, the Finite Element Method (FEM) is used to compare and validate the results from the lattice model. Predictions from these two modelling approaches are then compared to the experimental results provided by the EMM-ARM (Elasticity Modulus Measurement through Ambient Response Method) testing technique, the latter allowing measurement of the elastic modulus of hydrating cement pastes. Finally, the above-referred numerical models are used to evaluate the influence of the following features: the particle size distribution of the cement grains, the microstructure discretisation refinement and the elastic modulus of the C-S-H cement hydration product. Full article

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

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21 pages, 6826 KiB

Open AccessFeature PaperArticle

Real-Time Tomography of Gas-Jets with a Wollaston Interferometer

by Andreas Adelmann^1,*

, Benedikt Hermann^1,2

, Rasmus Ischebeck¹, Malte C. Kaluza^3,4, Uldis Locans⁵, Nick Sauerwein¹ and Roxana Tarkeshian²

¹ Paul Scherrer Institut, 5232 Villigen, Switzerland

² Institut für Angewandte Physik, Universität Bern, 3012 Bern, Switzerland

³ Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, 07743 Jena, Germany

⁴ Helmholtz Institute Jena, 07743 Jena, Germany

⁵ Intel, Universitè de Versailles Saint-Quentin-en-Yvelines 45, 78000 Versailles, France

Appl. Sci. 2018, 8(3), 443; https://doi.org/10.3390/app8030443 - 15 Mar 2018

Cited by 14 | Viewed by 6431

Abstract

A tomographic gas-density diagnostic using a Single-Beam Wollaston Interferometer able to characterize non-symmetric density distributions in gas jets is presented. A real-time tomographic algorithm is able to reconstruct three-dimensional density distributions. A Maximum Likelihood-Expectation Maximization algorithm, an iterative method with good convergence properties [...] Read more.

A tomographic gas-density diagnostic using a Single-Beam Wollaston Interferometer able to characterize non-symmetric density distributions in gas jets is presented. A real-time tomographic algorithm is able to reconstruct three-dimensional density distributions. A Maximum Likelihood-Expectation Maximization algorithm, an iterative method with good convergence properties compared to simple back projection, is used. With the use of graphical processing units, real-time computation and high resolution are achieved. Two different gas jets are characterized: a kHz, piezo-driven jet for lower densities and a solenoid valve-based jet producing higher densities. While the first jet is used for free electron laser photon beam characterization, the second jet is used in laser wake field acceleration experiments. In this latter application, well-tailored and non-symmetric density distributions produced by a supersonic shock front generated by a razor blade inserted laterally to the gas flow, which breaks cylindrical symmetry, need to be characterized. Full article

(This article belongs to the Special Issue Laser-Driven Particle Acceleration)

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9 pages, 867 KiB

Open AccessArticle

A Multiple-Model Particle Filter Fusion Algorithm for GNSS/DR Slide Error Detection and Compensation

by Rafael Toledo-Moreo^1,*

, Carlos Colodro-Conde² and Javier Toledo-Moreo¹

¹ Department of Electronics and Computer Technology, Universidad Politécnica de Cartagena, 30202 Murcia, Spain

² Instituto de Astrofísica de Canarias, La Laguna, 38205 Tenerife, Spain

Appl. Sci. 2018, 8(3), 445; https://doi.org/10.3390/app8030445 - 15 Mar 2018

Cited by 6 | Viewed by 4550

Abstract

Continuous accurate positioning is a key element for the deployment of many advanced driver assistance systems (ADAS) and autonomous vehicle navigation. To achieve the necessary performance, global navigation satellite systems (GNSS) must be combined with other technologies. A common onboard sensor-set that allows [...] Read more.

Continuous accurate positioning is a key element for the deployment of many advanced driver assistance systems (ADAS) and autonomous vehicle navigation. To achieve the necessary performance, global navigation satellite systems (GNSS) must be combined with other technologies. A common onboard sensor-set that allows keeping the cost low, features the GNSS unit, odometry, and inertial sensors, such as a gyro. Odometry and inertial sensors compensate for GNSS flaws in many situations and, in normal conditions, their errors can be easily characterized, thus making the whole solution not only more accurate but also with more integrity. However, odometers do not behave properly when friction conditions make the tires slide. If not properly considered, the positioning perception will not be sound. This article introduces a hybridization approach that takes into consideration the sliding situations by means of a multiple model particle filter (MMPF). Tests with real datasets show the goodness of the proposal. Full article

(This article belongs to the Special Issue Road Vehicles Surroundings Supervision: On-Board Sensors and Communications)

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21 pages, 1201 KiB

Open AccessArticle

Modelling the Interaction Levels in HCI Using an Intelligent Hybrid System with Interactive Agents: A Case Study of an Interactive Museum Exhibition Module in Mexico

by Ricardo Rosales^1,*

, Manuel Castañón-Puga^2,*

, Felipe Lara-Rosano³

, Josue Miguel Flores-Parra², Richard Evans⁴

, Nora Osuna-Millan¹ and Carelia Gaxiola-Pacheco²

¹ Accounting and Administration School, Autonomous University of Baja California, Tijuana 22390, Mexico

² Chemistry and Engineering School, Autonomous University of Baja California, Tijuana 22390, Mexico

³ Complexity Science Center, National Autonomous University of Mexico, Mexico City 04510, Mexico

⁴ Business Information Management and Operations Department, University of Westminster, London NW1 5LS, UK

Appl. Sci. 2018, 8(3), 446; https://doi.org/10.3390/app8030446 - 15 Mar 2018

Cited by 13 | Viewed by 6414

Abstract

Technology has become a necessity in our everyday lives and essential for completing activities we typically take for granted; technologies can assist us by completing set tasks or achieving desired goals with optimal affect and in the most efficient way, thereby improving our [...] Read more.

Technology has become a necessity in our everyday lives and essential for completing activities we typically take for granted; technologies can assist us by completing set tasks or achieving desired goals with optimal affect and in the most efficient way, thereby improving our interactive experiences. This paper presents research that explores the representation of user interaction levels using an intelligent hybrid system approach with agents. We evaluate interaction levels of Human-Computer Interaction (HCI) with the aim of enhancing user experiences. We consider the description of interaction levels using an intelligent hybrid system to provide a decision-making system to an agent that evaluates interaction levels when using interactive modules of a museum exhibition. The agents represent a high-level abstraction of the system, where communication takes place between the user, the exhibition and the environment. In this paper, we provide a means to measure the interaction levels and natural behaviour of users, based on museum user-exhibition interaction. We consider that, by analysing user interaction in a museum, we can help to design better ways to interact with exhibition modules according to the properties and behaviour of the users. An interaction-evaluator agent is proposed to achieve the most suitable representation of the interaction levels with the aim of improving user interactions to offer the most appropriate directions, services, content and information, thereby improving the quality of interaction experienced between the user-agent and exhibition-agent. Full article

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

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14 pages, 2543 KiB

Open AccessFeature PaperArticle

Comparison of Nonlinear Compensation Techniques for 400-Gb/s Coherent Multi-Band OFDM Super-Channels

by Vasiliki Vgenopoulou^1,*

, Mengdi Song², Erwan Pincemin³, Yves Jaouën², Stylianos Sygletos⁴ and Ioannis Roudas⁵

¹ Department of Physics, University of Patras, Rio, 26500 Patras, Greece

² LTCI, CNRS, Telecom ParisTech, Université Paris Saclay, 75013 Paris, France

³ Orange Labs Networks, 2 Avenue Pierre Marzin, 22307 Lannion, France

⁴ Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET, UK

⁵ Department of Electrical and Computer Engineering, Montana State University, Bozeman, MT 59717, USA

Appl. Sci. 2018, 8(3), 447; https://doi.org/10.3390/app8030447 - 15 Mar 2018

Cited by 9 | Viewed by 4784

Abstract

The last few years, many studies have been published on the 3rd-order inverse Volterra series transfer function nonlinear equalizer (IVSTF-NLE) in long-haul optical communication systems. Nonetheless, no experimental work has been published on investigating the potential of the 3rd-order IVSTF-NLE for the compensation [...] Read more.

The last few years, many studies have been published on the 3rd-order inverse Volterra series transfer function nonlinear equalizer (IVSTF-NLE) in long-haul optical communication systems. Nonetheless, no experimental work has been published on investigating the potential of the 3rd-order IVSTF-NLE for the compensation of Kerr nonlinearities in a long-haul wavelength division multiplexing (WDM) system consisting of high-bit rate super-channels, as high as 400 Gb/s. In this paper, we study experimentally the performance of a 3rd-order IVSTF-NLE in a coherent optical WDM system, with a central, 400-Gb/s, 4-band, dual-polarization (DP), 16-ary quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) super-channel. We compare its performance against the performance of the digital back-propagation split-step Fourier (DBP-SSF) method for the compensation of nonlinearities after 10 × 100 km of ITU-T G.652 standard single mode fiber (SSMF). In the second part of this paper, we compare, via Monte Carlo simulations, the performance of the 3rd-order IVSTF-NLE and the DBP-SSF method, in terms of reach extension and computational complexity, after propagation through ITU-T G.652 SSMF and a ITU-T G.655 large effective area fiber (LEAF). By means of both experimental evaluation and simulations, we show that, in the presence of strong nonlinear effects, the 3rd-order IVSTF-NLE, which uses a single step per span, performs similarly with the two-steps-per-span DBP-SSF, whereas the eight-steps-per-span DBP-SSF is only marginally better but at the vast expense of computational complexity. Full article

(This article belongs to the Special Issue DSP for Next Generation Fibre Communication Systems)

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15 pages, 3835 KiB

Open AccessFeature PaperArticle

Simplified Modeling Strategy for the Thermomechanical Analysis of Massive Reinforced Concrete Structures at an Early Age

by Jacky Mazars^1,*, Stéphane Grange²

and Matthieu Briffaut¹

¹ CNRS, Univ. Grenoble Alpes, Grenoble INP, 3SR, F-38000 Grenoble, France

² INSA-Lyon, Univ. Lyon, GEOMAS, F-69621 Villeurbanne CEDEX, France

Appl. Sci. 2018, 8(3), 448; https://doi.org/10.3390/app8030448 - 15 Mar 2018

Cited by 8 | Viewed by 4588

Abstract

The objective of this work is to propose a comprehensive and efficient modeling approach to simulate the entire loading program of the RG8 test (both the restrained shrinkage and mechanical parts) performed within the framework of the French national program CEOS.fr. This effort [...] Read more.

The objective of this work is to propose a comprehensive and efficient modeling approach to simulate the entire loading program of the RG8 test (both the restrained shrinkage and mechanical parts) performed within the framework of the French national program CEOS.fr. This effort was made possible by introducing a multi-fiber beam discretization that included a thermomechanical model coupled with a unilateral concrete damage model. Due to the massiveness of the test structure, the scale effect needed to be taken into account. This step could be accomplished through use of a Weibull law. Extensive results were obtained during the experiment, some of which focused on deformations and forces developed in the structure by restrained shrinkage, the times of crack appearance and opening, and the consequences of damage sustained on the residual mechanical performance of the beam. A comparison with calculation output has demonstrated the ability of our modeling approach to simulate phenomena at both global and local levels, thus confirming the relevance of model choices made. Full article

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

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11 pages, 4249 KiB

Open AccessArticle

Numerical and Experimental Study on Multi-Focal Metallic Fresnel Zone Plates Designed by the Phase Selection Rule via Virtual Point Sources

by Jinseob Kim¹, Hyuntai Kim²

, Gun-Yeal Lee^3,4, Juhwan Kim¹, Byoungho Lee^3,4 and Yoonchan Jeong^1,4,5,*

¹ Laser Engineering and Applications Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea

² Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK

³ Optical Engineering and Quantum Electronics Laboratory, Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea

⁴ Inter-University of Semiconductor Research Center, Seoul National University, Seoul 08826, Korea

⁵ Institute of Applied Physics, Seoul National University, Seoul 08826, Korea

Appl. Sci. 2018, 8(3), 449; https://doi.org/10.3390/app8030449 - 15 Mar 2018

Cited by 21 | Viewed by 5595

Abstract

We propose a novel design method for multi-focal metallic Fresnel zone plates (MFZPs), which exploits the phase selection rule by putting virtual point sources (VPSs) at the desired focal points distant to the MFZP plane. The phase distribution at the MFZP plane reciprocally [...] Read more.

We propose a novel design method for multi-focal metallic Fresnel zone plates (MFZPs), which exploits the phase selection rule by putting virtual point sources (VPSs) at the desired focal points distant to the MFZP plane. The phase distribution at the MFZP plane reciprocally formed by the VPSs was quantized in a binary manner based on the phase selection rule, thereby leading to a corresponding on-off amplitude pattern for the targeted MFZP. The resultant phase distribution was dependent on the complex amplitudes of the VPSs, so that they could be determined from the perspective of both multi-focal functionality and fabrication feasibility. As a typical example, we utilized the particle swarm optimization algorithm to determine them. Based on the proposed method, we designed and numerically analyzed two types of novel MFZPs—one for a monochromatic multi-focal application and the other for a multi-chromatic mono-focal application—verifying the effectiveness and validity of the proposed method. We also fabricated them onto Au-deposited glass substrates, using electron beam evaporation and a focused ion beam milling process. We experimentally characterized them and also verified that they successfully demonstrated their feasibilities. The former produced distinct hot spots at three different focal distances of 10, 15, and 20

μ m

for monochromatic incidence at 650 nm, and the latter produced a single hot spot at a focal distance of 15

μ m

for multi-chromatic incidence at 660, 532, and 473 nm. The experimental results were also in good agreement with their corresponding numerical results. We expect that both MFZPs will have various applications, such as laser micromachining, optical trapping, biomedical sensing, confocal collimation, achromatic optics, etc. Full article

(This article belongs to the Section Optics and Lasers)

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13 pages, 6041 KiB

Open AccessArticle

A Pseudo-3D Model for Electromagnetic Acoustic Transducers (EMATs)

by Wuliang Yin^1,*, Yuedong Xie^2,*, Zhigang Qu¹ and Zenghua Liu³

¹ College of Electronic Information and Automation, Tianjin University of Science & Technology, 1038 DaguNan Road, Hexi District, Tianjin 300222, China

² School of Electrical and Electronic Engineering, University of Manchester, 60 Sackville Street, Manchester M13 9PL, UK

³ College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, 100 Pingleyuan, Beijing 100124, China

Appl. Sci. 2018, 8(3), 450; https://doi.org/10.3390/app8030450 - 15 Mar 2018

Cited by 6 | Viewed by 5215

Abstract

Previous methods for modelling Rayleigh waves produced by a meander-line-coil electromagnetic acoustic transducer (EMAT) consisted mostly of two-dimensional (2D) simulations that focussed on the vertical plane of the material. This paper presents a pseudo-three-dimensional (3D) model that extends the simulation space to both [...] Read more.

Previous methods for modelling Rayleigh waves produced by a meander-line-coil electromagnetic acoustic transducer (EMAT) consisted mostly of two-dimensional (2D) simulations that focussed on the vertical plane of the material. This paper presents a pseudo-three-dimensional (3D) model that extends the simulation space to both vertical and horizontal planes. For the vertical plane, we combines analytical and finite-difference time-domain (FDTD) methods to model Rayleigh waves’ propagation within an aluminium plate and their scattering behaviours by cracks. For the horizontal surface plane, we employ an analytical method to investigate the radiation pattern of Rayleigh waves at various depths. The experimental results suggest that the models and the modelling techniques are valid. Full article

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

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18 pages, 9648 KiB

Open AccessArticle

Transmission of High Frequency Vibrations in Rotating Systems. Application to Cavitation Detection in Hydraulic Turbines

by David Valentín^*

, Alexandre Presas, Mònica Egusquiza

, Carme Valero and Eduard Egusquiza

Center for Industrial Diagnostics and Fluid Dynamics (CDIF), Polytechnic University of Catalonia (UPC), Av. Diagonal, 647, ETSEIB, 08028 Barcelona, Spain

Appl. Sci. 2018, 8(3), 451; https://doi.org/10.3390/app8030451 - 16 Mar 2018

Cited by 27 | Viewed by 6087

Abstract

One of the main causes of damage in hydraulic turbines is cavitation. While not all cavitation appearing in a turbine is of a destructive type, erosive cavitation can severely affect the structure, thus increasing maintenance costs and reducing the remaining useful life of [...] Read more.

One of the main causes of damage in hydraulic turbines is cavitation. While not all cavitation appearing in a turbine is of a destructive type, erosive cavitation can severely affect the structure, thus increasing maintenance costs and reducing the remaining useful life of the machine. Of all types of cavitation, the maximum erosion occurs when clouds of bubbles collapse on the runner surface (cloud cavitation). When this occurs it is associated with a substantial increase in noise, and vibrations that are propagated everywhere throughout the machine. The generation of these cavitation clouds may occur naturally or it may be the response to a periodic pressure fluctuation, like the rotor/stator interaction in a hydraulic turbine. Erosive bubble cavitation generates high-frequency vibrations that are modulated by the shedding frequency. Therefore, the methods for the detection of erosive cavitation in hydraulic turbines are based on the measurement and demodulation of high-frequency vibrations. In this paper, the feasibility of detecting erosive cavitation in hydraulic turbines is investigated experimentally in a rotating disk system, which represents a simplified hydraulic turbine structure. The test rig used consists of a rotating disk submerged in a tank of water and confined with nearby axial and radial rigid surfaces. The excitation patterns produced by cloud cavitation are reproduced with a PZT (piezoelectric patch) located on the disk. These patterns include pseudo-random excitations of different frequency bands modulated by one low carrier frequency, which model the erosive cavitation characteristics. Different types of sensors have been placed in the stationary and in the rotating parts (accelerometers, acoustic emission (AE), and a microphone) in order to detect the excitation pattern. The results obtained for all the sensors tested have been compared in detail for the different excitation patterns applied to the disk. With this information, the best location and type of sensor to detect the different excitations have been identified. This study permits improving the actual technique of detecting erosive cavitation in hydraulic turbines and, therefore, to avoid operation under these circumstances. Full article

(This article belongs to the Section Acoustics and Vibrations)

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19 pages, 5138 KiB

Open AccessArticle

A Novel Distributed Large-Scale Demand Response Scheme in High Proportion Renewable Energy Sources Integration Power Systems

by Shuai Fan¹, Guangyu He^1,*, Kunqi Jia¹ and Zhihua Wang²

¹ School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

² Electric Power Dispatching and Control Center of State Grid Shanghai Municipal Electric Power Company, Shanghai 200122, China

Appl. Sci. 2018, 8(3), 452; https://doi.org/10.3390/app8030452 - 16 Mar 2018

Cited by 20 | Viewed by 4698

Abstract

Large-scale demand response (DR) is a useful regulatory method used in high proportion renewable energy sources (RES) integration power systems. Current incentive-based DR schemes are unsuitable for large-scale DR due to their centralized formulation. This paper proposes a distributed scheme to support large-scale [...] Read more.

Large-scale demand response (DR) is a useful regulatory method used in high proportion renewable energy sources (RES) integration power systems. Current incentive-based DR schemes are unsuitable for large-scale DR due to their centralized formulation. This paper proposes a distributed scheme to support large-scale implementation of DR. To measure DR performance, this paper proposes the customer directrix load (CDL), which is a desired load profile, to replace the customer baseline load (CBL). The uniqueness of CDL makes it more suitable for distributed schemes, while numerous CBLs have to be calculated in a centralized manner to ensure fairness. To allocate DR tasks and rebates, this paper proposes a distributed approach, where the load serving entity (LSE) only needs to publish a total rebate and corresponding CDL. As for each customer, s/he needs to claim an ideal rebate ratio that ranges from 0 to 1, which indicates the proportion of rebate s/he wants to get from LSE. The rebate value for each customer also determines his or her DR task. Then, the process of customer claims for the ideal rebate ratio is modeled as a non-cooperative game, and the Nash equilibrium is proved to exist. The Gossip algorithm is improved in this paper to be suitable for socially connected networks, and the entire game process is distributed. Finally, a large-scale DR system is formulated. The simulation results show that the proposed DR can promote the consumption of RES. Additionally, this scheme is suitable for large-scale customer systems, and the distributed game process is effective. Full article

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

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29 pages, 16527 KiB

Open AccessArticle

Development of a High-Fidelity Model for an Electrically Driven Energy Storage Flywheel Suitable for Small Scale Residential Applications

by Mustafa E. Amiryar^*

, Keith R. Pullen^*

and Daniel Nankoo

School of Mathematics, Computer Science and Engineering, University of London, London EC1V 0HB, UK

Appl. Sci. 2018, 8(3), 453; https://doi.org/10.3390/app8030453 - 16 Mar 2018

Cited by 33 | Viewed by 8394

Abstract

Energy storage systems (ESS) are key elements that can be used to improve electrical system efficiency by contributing to balance of supply and demand. They provide a means for enhancing the power quality and stability of electrical systems. They can enhance electrical system [...] Read more.

Energy storage systems (ESS) are key elements that can be used to improve electrical system efficiency by contributing to balance of supply and demand. They provide a means for enhancing the power quality and stability of electrical systems. They can enhance electrical system flexibility by mitigating supply intermittency, which has recently become problematic, due to the increased penetration of renewable generation. Flywheel energy storage systems (FESS) are a technology in which there is gathering interest due to a number of advantages offered over other storage solutions. These technical qualities attributed to flywheels include high power density, low environmental impact, long operational life, high round-trip efficiency and high cycle life. Furthermore, when configured in banks, they can store MJ levels of energy without any upper limit. Flywheels configured for grid connected operation are systems comprising of a mechanical part, the flywheel rotor, bearings and casings, and the electric drive part, inclusive of motor-generator (MG) and power electronics. This contribution focusses on the modelling and simulation of a high inertia FESS for energy storage applications which has the potential for use in the residential sector in more challenging situations, a subject area in which there are few publications. The type of electrical machine employed is a permanent magnet synchronous motor (PMSM) and this, along with the power electronics drive, is simulated in the MATLAB/Simulink environment. A brief description of the flywheel structure and applications are given as a means of providing context for the electrical modelling and simulation reported. The simulated results show that the system run-down losses are 5% per hour, with overall roundtrip efficiency of 88%. The flywheel speed and energy storage pattern comply with the torque variations, whilst the DC-bus voltage remains constant and stable within ±3% of the rated voltage, regardless of load fluctuations. Full article

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

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11 pages, 3029 KiB

Open AccessArticle

An Investigation of the High Efficiency Estimation Approach of the Large-Scale Scattered Point Cloud Normal Vector

by Xianglin Meng^1,*, Wantao He^2,* and Junyan Liu³

¹ School of Mechanical Engineering, Heilongjiang University of Science and Technology, Harbin 150027, China

² State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China

³ School of Mechatronic Engineering, Harbin Institute of Technology, Harbin 150001, China

Appl. Sci. 2018, 8(3), 454; https://doi.org/10.3390/app8030454 - 16 Mar 2018

Cited by 4 | Viewed by 4942

Abstract

The normal vector estimation of the large-scale scattered point cloud (LSSPC) plays an important role in point-based shape editing. However, the normal vector estimation for LSSPC cannot meet the great challenge of the sharp increase of the point cloud that is mainly attributed [...] Read more.

The normal vector estimation of the large-scale scattered point cloud (LSSPC) plays an important role in point-based shape editing. However, the normal vector estimation for LSSPC cannot meet the great challenge of the sharp increase of the point cloud that is mainly attributed to its low computational efficiency. In this paper, a novel, fast method-based on bi-linear interpolation is reported on the normal vector estimation for LSSPC. We divide the point sets into many small cubes to speed up the local point search and construct interpolation nodes on the isosurface expressed by the point cloud. On the premise of calculating the normal vectors of these interpolated nodes, a normal vector bi-linear interpolation of the points in the cube is realized. The proposed approach has the merits of accurate, simple, and high efficiency, because the algorithm only needs to search neighbor and calculates normal vectors for interpolation nodes that are usually far less than the point cloud. The experimental results of several real and simulated point sets show that our method is over three times faster than the Elliptic Gabriel Graph-based method, and the average deviation is less than 0.01 mm. Full article

(This article belongs to the Section Mechanical Engineering)

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26 pages, 3204 KiB

Open AccessArticle

A Hybrid Method for Optimal Siting and Sizing of Battery Energy Storage Systems in Unbalanced Low Voltage Microgrids

by Guido Carpinelli¹

, Fabio Mottola²

, Daniela Proto^1,*, Angela Russo³

and Pietro Varilone⁴

¹ University of Naples Federico II, via Claudio 21, 80125 Naples, Italy

² University of Naples Parthenope, Centro Direzionale di Napoli, Isola C/4, 80143 Naples, Italy

³ Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Turin, Italy

⁴ University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino, Italy

Appl. Sci. 2018, 8(3), 455; https://doi.org/10.3390/app8030455 - 16 Mar 2018

Cited by 27 | Viewed by 4567

Abstract

This paper deals with the problem of optimal allocation (siting and sizing) of storage resources in unbalanced three-phase low voltage microgrids. The siting and sizing problem is formulated as a mixed, non-linear, constrained optimization problem whose objective function deals with economic issues and [...] Read more.

This paper deals with the problem of optimal allocation (siting and sizing) of storage resources in unbalanced three-phase low voltage microgrids. The siting and sizing problem is formulated as a mixed, non-linear, constrained optimization problem whose objective function deals with economic issues and whose constraints involve technical limitations of both network and distributed resources. Emphasis is given to the power quality issue with particular attention to unbalance reduction and voltage profile improvement. Technological issues, such as those related to the preservation of batteries’ lifetime, were also taken into account. The planning problem is solved by means of a genetic algorithm which includes an inner algorithm based on sequential quadratic programming. In order to limit the processing time while maintaining reasonable accuracy, the genetic algorithm search space is significantly reduced identifying a subset of candidate buses for the siting of the storage resources. The Inherent Structure Theory of Networks and the Loading Constraints Criterion were used to identify the candidate buses. The proposed method has been applied to a low voltage test network demonstrating the effectiveness of the procedure in terms of computational burden while also preserving the accuracy of the solution. Full article

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

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12 pages, 1866 KiB

Open AccessArticle

Influence of Substrate Stage Temperature and Rotation Rate on the Magneto-Optical Quality of RF-Sputtered Bi_2.1Dy_0.9Fe_3.9Ga_1.1O₁₂ Garnet Thin Films

by M. Nur-E-Alam^*

, Mikhail Vasiliev

and Kamal Alameh

Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia

Appl. Sci. 2018, 8(3), 456; https://doi.org/10.3390/app8030456 - 16 Mar 2018

Cited by 4 | Viewed by 4263

Abstract

Highly bismuth-substituted iron garnet thin films are prepared on quartz substrates by using a radio frequency (RF) magnetron sputtering technique. We study the factors (process parameters associated with the RF magnetron sputter deposition technique) affecting the magneto-optical (MO) properties of ferrite garnet films [...] Read more.

Highly bismuth-substituted iron garnet thin films are prepared on quartz substrates by using a radio frequency (RF) magnetron sputtering technique. We study the factors (process parameters associated with the RF magnetron sputter deposition technique) affecting the magneto-optical (MO) properties of ferrite garnet films of composition Bi_2.1Dy_0.9Fe_3.9Ga_1.1O₁₂. All films show high MO response across the visible range of wavelengths after being annealed. In particular, the effects of substrate stage temperature and rotation rate on the various properties of films are studied. Experimental results reveal that the characteristics of garnet films of this type can be tuned and optimized for use in various magnetic field-driven nanophotonics and integrated optics devices, and that, at a substrate stage rotation rate near 16 revolutions per minute, the MO quality of the developed MO films is the best, in comparison with films deposited at other rotation rates. To the best of our knowledge, this is the first report on the effects of deposition parameters on the properties of garnet films of this stoichiometry. Full article

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

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16 pages, 2527 KiB

Open AccessArticle

Design of SBS-Modified Bitumen Stabilizer Powder Based on the Vulcanization Mechanism

by Wengang Zhang^1,*

, Longting Ding² and Zhirong Jia^1,*

¹ School of Civil and Architectural Engineering, Shandong University of Technology, Zibo 255049, China

² Highway College of Chang’ an University, Xi’an 710064, China

Appl. Sci. 2018, 8(3), 457; https://doi.org/10.3390/app8030457 - 16 Mar 2018

Cited by 16 | Viewed by 6795

Abstract

In order to improve the problem of the bad thermal storage stability of Styrene-Butadiene-Styrene Block Copolymer Modified Bitumen (SBS-modified bitumen), the vulcanization reaction was selected as the basic mechanism for the research and development of the stabilizer. Sulfur, tetramethylthiuram disulfide (TMTD), zinc oxide, [...] Read more.

In order to improve the problem of the bad thermal storage stability of Styrene-Butadiene-Styrene Block Copolymer Modified Bitumen (SBS-modified bitumen), the vulcanization reaction was selected as the basic mechanism for the research and development of the stabilizer. Sulfur, tetramethylthiuram disulfide (TMTD), zinc oxide, butylated hydroxytoluene (BHT), kaolin (Al₂O₃·2SiO₂·2H₂O) and carbon-white (SiO₂) were used as raw materials, and 32 kinds of components with different contents of raw materials were designed. The 48-h segregation softening point and other modified bitumen technical indicators, such as ductility, penetration, penetration index, viscosity, and so on, were tested and analyzed. The fluorescence microscope test was also conducted to explore the crosslinking situation based on the vulcanization reaction. The results show that the component with good performance of the SBS-modified bitumen stabilizer powder was S:TMTD:ZnO:BHT: Al₂O₃·2SiO₂·2H₂O = 60:16:4:20:1250 or S:TMTD:ZnO:BHT:SiO₂ = 60:16:4:20:625. The optimum content of stabilizer powder was 0.9% (S/modified bitumen). The stabilizer was dry powder and can be directly put into bitumen. It can cross-link SBS and especially has an effect on preventing SBS segregation. The technical performance of SBS-modified bitumen with stabilizer powder, such as hot temperature performance, low temperature performance, anti-aging performance and thermal storage stability, all meet the relevant specifications. Full article

(This article belongs to the Special Issue Achievements and Prospects of Advanced Pavement Materials Technologies)

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19 pages, 1144 KiB

Open AccessArticle

A Kernel Least Mean Square Algorithm Based on Randomized Feature Networks

by Yuqi Liu, Chao Sun^* and Shouda Jiang

Department of Automatic Testing and Control, Harbin Institute of Technology, Harbin 150080, China

Appl. Sci. 2018, 8(3), 458; https://doi.org/10.3390/app8030458 - 16 Mar 2018

Cited by 5 | Viewed by 4568

Abstract

To construct an online kernel adaptive filter in a non-stationary environment, we propose a randomized feature networks-based kernel least mean square (KLMS-RFN) algorithm. In contrast to the Gaussian kernel, which implicitly maps the input to an infinite dimensional space in theory, the randomized [...] Read more.

To construct an online kernel adaptive filter in a non-stationary environment, we propose a randomized feature networks-based kernel least mean square (KLMS-RFN) algorithm. In contrast to the Gaussian kernel, which implicitly maps the input to an infinite dimensional space in theory, the randomized feature mapping transform inputs samples into a relatively low-dimensional feature space, where the transformed samples are approximately equivalent to those in the feature space using a shift-invariant kernel. The mean square convergence process of the proposed algorithm is investigated under the uniform convergence analysis method of a nonlinear adaptive filter. The computational complexity is also evaluated. In Lorenz time series prediction and nonstationary channel equalization scenarios, the simulation results demonstrate the effectiveness of the proposed algorithm. Full article

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15 pages, 10478 KiB

Open AccessFeature PaperArticle

Extraction of Independent Structural Images for Principal Component Thermography

by Dmitry Gavrilov^1,* and Roman Gr. Maev²

¹ Department of Physics, University of Windsor, Windsor, ON N9B 3P4, Canada

² Institute for Diagnostic Imaging Research, University of Windsor, Windsor, ON N9A 5R5, Canada

Appl. Sci. 2018, 8(3), 459; https://doi.org/10.3390/app8030459 - 17 Mar 2018

Cited by 8 | Viewed by 4650

Abstract

Thermography is a powerful tool for non-destructive testing of a wide range of materials. Thermography has a number of approaches differing in both experiment setup and the way the collected data are processed. Among such approaches is the Principal Component Thermography (PCT) method, [...] Read more.

Thermography is a powerful tool for non-destructive testing of a wide range of materials. Thermography has a number of approaches differing in both experiment setup and the way the collected data are processed. Among such approaches is the Principal Component Thermography (PCT) method, which is based on the statistical processing of raw thermal images collected by thermal camera. The processed images (principal components or empirical orthogonal functions) form an orthonormal basis, and often look like a superposition of all possible structural features found in the object under inspection—i.e., surface heating non-uniformity, internal defects and material structure. At the same time, from practical point of view it is desirable to have images representing independent structural features. The work presented in this paper proposes an approach for separation of independent image patterns (archetypes) from a set of principal component images. The approach is demonstrated in the application of inspection of composite materials as well as the non-invasive analysis of works of art. Full article

(This article belongs to the Special Issue Novel Ideas for Infrared Thermography also Applied in Integrated Approaches)

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19 pages, 5265 KiB

Open AccessArticle

Parameters Studies on Surface Initiated Rolling Contact Fatigue of Turnout Rails by Three-Level Unreplicated Saturated Factorial Design

by Xiaochuan Ma^1,2

, Ping Wang², Jingmang Xu^2,* and Rong Chen²

¹ Engineering Research Center of Railway Environment Vibration and Noise, Ministry of Education, East China Jiaotong University, Nanchang 330013, China

² MOE Key Laboratory of High-Speed Railway Engineering, Southwest Jiaotong University, Chengdu 610031, China

Appl. Sci. 2018, 8(3), 461; https://doi.org/10.3390/app8030461 - 17 Mar 2018

Cited by 15 | Viewed by 5201

Abstract

Surface initiated rolling contact fatigue (RCF), mainly characterized by cracks and material stripping, is a common type of damage to turnout rails, which can not only shorten service life of turnout but also lead to poor running safety of vehicle. The rail surface [...] Read more.

Surface initiated rolling contact fatigue (RCF), mainly characterized by cracks and material stripping, is a common type of damage to turnout rails, which can not only shorten service life of turnout but also lead to poor running safety of vehicle. The rail surface initiated RCF of turnouts is caused by a long-term accumulation, the size and distribution of which are related to the dynamic parameters of the complicated vehicle-turnout system. In order to simulate the accumulation of rail damage, some random samples of dynamic parameters significantly influencing it should be input. Based on the three-level unreplicated saturated factorial design, according to the evaluation methods of H, P and B statistic values, six dynamic parameters that influence the rail surface initiated RCF in turnouts, namely running speed of vehicle, axle load, wheel-rail profiles, integral vertical track stiffness and wheel-rail friction coefficient, are obtained by selecting 13 dynamic parameters significantly influencing the dynamic vehicle-turnout interaction as the analysis factors, considering four dynamic response results, i.e., the normal wheel-rail contact force, longitudinal creep force, lateral creep force and wheel-rail contact patch area as the observed parameters. In addition, the rail surface initiated RCF behavior in turnouts under different wheel-rail creep conditions is analyzed, considering the relative motion of stock/switch rails. The results show that the rail surface initiated RCF is mainly caused by the tangential stress being high under small creep conditions, the normal and tangential stresses being high under large creep conditions, and the normal stress being high under pure spin creep conditions. Full article

(This article belongs to the Section Mechanical Engineering)

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10 pages, 2654 KiB

Open AccessArticle

Plasmonic Filter and Demultiplexer Based on Square Ring Resonator

by Zhaojian Zhang¹

, Junbo Yang^2,*, Xin He², Yunxin Han², Jingjing Zhang¹, Jie Huang¹ and Dingbo Chen¹

¹ College of Liberal Arts and Sciences, National University of Defense Technology, Changsha 410073, China

² Center of Material Science, National University of Defense Technology, Changsha 410073, China

Appl. Sci. 2018, 8(3), 462; https://doi.org/10.3390/app8030462 - 17 Mar 2018

Cited by 40 | Viewed by 5903

Abstract

A ring resonator is a basic component of traditional photonic integrated circuits (PIC), which has been, however, found difficult to be applied efficiently in high-compact plasmonic metal-insulator-metal (MIM) systems. Here, based on a plasmonic band-stop filter with a square ring resonator (SRR), a [...] Read more.

A ring resonator is a basic component of traditional photonic integrated circuits (PIC), which has been, however, found difficult to be applied efficiently in high-compact plasmonic metal-insulator-metal (MIM) systems. Here, based on a plasmonic band-stop filter with a square ring resonator (SRR), a novel side-coupling method is introduced both numerically and theoretically to achieve a drop in the resonant wavelength in the SRR with considerable efficiency. By introducing the reflector structure, the performance can be appreciably improved. Besides, this structure also has potential for sensing and switching. Finally, a dual demultiplexer based on SRRs is realized at telecommunication wavelengths with comparable performance, which makes it possible to apply ring resonators in on-chip plasmonic wavelength division multiplex (WDM) networks. This work is valuable for PIC design, and will promote the on-chip plasmonic system progress. Full article

(This article belongs to the Special Issue Integrated Photonic and Plasmonic Devices Based on Slot Waveguides)

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15 pages, 3482 KiB

Open AccessArticle

Extraction of Coal and Gangue Geometric Features with Multifractal Detrending Fluctuation Analysis

by Kai Liu¹

, Xi Zhang¹ and YangQuan Chen^2,*

¹ School of Mechanical Electronic & Information Engineering, China University of Mining and Technology, Beijing 100083, China

² Mechatronics, Embedded Systems and Automation Lab, University of California, Merced, CA 95343, USA

Appl. Sci. 2018, 8(3), 463; https://doi.org/10.3390/app8030463 - 17 Mar 2018

Cited by 39 | Viewed by 5670

Abstract

The separation of coal and gangue is an important process of the coal preparation technology. The conventional way of manual selection and separation of gangue from the raw coal can be replaced by computer vision technology. In the literature, research on image recognition [...] Read more.

The separation of coal and gangue is an important process of the coal preparation technology. The conventional way of manual selection and separation of gangue from the raw coal can be replaced by computer vision technology. In the literature, research on image recognition and classification of coal and gangue is mainly based on the grayscale and texture features of the coal and gangue. However, there are few studies on characteristics of coal and gangue from the perspective of their outline differences. Therefore, the multifractal detrended fluctuation analysis (MFDFA) method is introduced in this paper to extract the geometric features of coal and gangue. Firstly, the outline curves of coal and gangue in polar coordinates are detected and achieved along the centroid, thereby the multifractal characteristics of the series are analyzed and compared. Subsequently, the modified local singular spectrum widths

Δ h

of the outline curve series are extracted as the characteristic variables of the coal and gangue for pattern recognition. Finally, the extracted geometric features by MFDFA combined with the grayscale and texture features of the images are compared with other methods, indicating that the recognition rate of coal gangue images can be increased by introducing the geometric features. Full article

(This article belongs to the Special Issue Fractal Based Information Processing and Recognition)

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19 pages, 10845 KiB

Open AccessArticle

Kinematics and Dynamics Analysis of a 3-DOF Upper-Limb Exoskeleton with an Internally Rotated Elbow Joint

by Xin Wang¹, Qiuzhi Song^1,*, Xiaoguang Wang^1,2 and Pengzhan Liu¹

¹ School of Mechatronical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China

² Harbin Jiancheng Group Co., Ltd., 65 Nanzhi Road, Xiangfang District, Harbin 150030, China

Appl. Sci. 2018, 8(3), 464; https://doi.org/10.3390/app8030464 - 17 Mar 2018

Cited by 25 | Viewed by 9308

Abstract

The contradiction between self-weight and load capacity of a power-assisted upper-limb exoskeleton for material hanging is unresolved. In this paper, a non-anthropomorphic 3-degree of freedom (DOF) upper-limb exoskeleton with an internally rotated elbow joint is proposed based on an anthropomorphic 5-DOF upper-limb exoskeleton [...] Read more.

The contradiction between self-weight and load capacity of a power-assisted upper-limb exoskeleton for material hanging is unresolved. In this paper, a non-anthropomorphic 3-degree of freedom (DOF) upper-limb exoskeleton with an internally rotated elbow joint is proposed based on an anthropomorphic 5-DOF upper-limb exoskeleton for power-assisted activity. The proposed 3-DOF upper-limb exoskeleton contains a 2-DOF shoulder joint and a 1-DOF internally rotated elbow joint. The structural parameters of the 3-DOF upper-limb exoskeleton were determined, and the differences and singularities of the two exoskeletons were analyzed. The workspace, the joint torques and the power consumption of two exoskeletons were analyzed by kinematics and dynamics, and an exoskeleton prototype experiment was performed. The results showed that, compared with a typical anthropomorphic upper-limb exoskeleton, the non-anthropomorphic 3-DOF upper-limb exoskeleton had the same actual workspace; eliminated singularities within the workspace; improved the elbow joint force situation; and the maximum elbow joint torque, elbow external-flexion/internal-extension and shoulder flexion/extension power consumption were significantly reduced. The proposed non-anthropomorphic 3-DOF upper-limb exoskeleton can be applied to a power-assisted upper-limb exoskeleton in industrial settings. Full article

(This article belongs to the Section Mechanical Engineering)

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27 pages, 2323 KiB

Open AccessArticle

NMR-MPar: A Fault-Tolerance Approach for Multi-Core and Many-Core Processors

by Vanessa Vargas^1,2,*,†

, Pablo Ramos^1,2, Jean-Francois Méhaut⁴ and Raoul Velazco^2,3

¹ Universidad de las Fuerzas Armadas ESPE, DEEE, Avenida General Rumiñahui S/N, 171-5-231B, Sangolqui, Ecuador

² TIMA Labs., Université Grenoble-Alpes, Avenue Félix Viallet, 38000 Grenoble, France

³ National Center for Scientific Research (CNRS), 38000 Grenoble, France

⁴ LIG Labs., Université Grenoble-Alpes, 3 Parvis Louis Néel, 38054. Grenoble, France

^† Current address: Universidad de las Fuerzas Armadas ESPE, Av. General Rumiñahui s/n, 171-5-231B, Sangolqui, Ecuador, P.O. BOX:171-5-231B.

Appl. Sci. 2018, 8(3), 465; https://doi.org/10.3390/app8030465 - 17 Mar 2018

Cited by 19 | Viewed by 5592

Abstract

Multi-core and many-core processors are a promising solution to achieve high performance by maintaining a lower power consumption. However, the degree of miniaturization makes them more sensitive to soft-errors. To improve the system reliability, this work proposes a fault-tolerance approach based on redundancy [...] Read more.

Multi-core and many-core processors are a promising solution to achieve high performance by maintaining a lower power consumption. However, the degree of miniaturization makes them more sensitive to soft-errors. To improve the system reliability, this work proposes a fault-tolerance approach based on redundancy and partitioning principles called N-Modular Redundancy and M-Partitions (NMR-MPar). By combining both principles, this approach allows multi-/many-core processors to perform critical functions in mixed-criticality systems. Benefiting from the capabilities of these devices, NMR-MPar creates different partitions that perform independent functions. For critical functions, it is proposed that N partitions with the same configuration participate of an N-modular redundancy system. In order to validate the approach, a case study is implemented on the KALRAY Multi-Purpose Processing Array (MPPA)-256 many-core processor running two parallel benchmark applications. The traveling salesman problem and matrix multiplication applications were selected to test different device’s resources. The effectiveness of NMR-MPar is assessed by software-implemented fault-injection. For evaluation purposes, it is considered that the system is intended to be used in avionics. Results show the improvement of the application reliability by two orders of magnitude when implementing NMR-MPar on the system. Finally, this work opens the possibility to use massive parallelism for dependable applications in embedded systems. Full article

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11 pages, 1109 KiB

Open AccessArticle

An Interference Cancellation Scheme for High Reliability Based on MIMO Systems

by Jae-Hyun Ro, Sung-Soon Park and Hyoung-Kyu Song^*

uT Communication Research Institute, Sejong University, Gunja-dong 98, Gwangjin-gu, Seoul 05006, Korea

Appl. Sci. 2018, 8(3), 466; https://doi.org/10.3390/app8030466 - 18 Mar 2018

Cited by 2 | Viewed by 3117

Abstract

This article proposes a new interference cancellation scheme in a half-duplex based two-path relay system. In the conventional two-path relay system, inter-relay-interference (IRI) which severely degrades the error performances at a destination occurs because a source and a relay transmit signals simultaneously at [...] Read more.

This article proposes a new interference cancellation scheme in a half-duplex based two-path relay system. In the conventional two-path relay system, inter-relay-interference (IRI) which severely degrades the error performances at a destination occurs because a source and a relay transmit signals simultaneously at a specific time. The proposed scheme removes the IRI at a relay for higher signal-to-interference plus noise ratio (SINR) to receive interference free signal at a destination, unlike the conventional relay system, which removes IRI at a destination. To handle the IRI, the proposed scheme uses multiple-input multiple-output (MIMO) signal detection at the relays and it makes low-complexity signal processing at a destination which is a usually mobile user. At the relays, the proposed scheme uses the low-complexity QR decomposition-M algorithm (QRD-M) to optimally remove the IRI. Also, for obtaining diversity gain, the proposed scheme uses cyclic delay diversity (CDD) to transmit the signals at a source and the relays. In simulation results, the error performance for the proposed scheme is better when the distance between one relay and another relay is low unlike the conventional scheme because the QRD-M detects received signal in order of higher post signal-to-noise ratio (SNR). Full article

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19 pages, 7683 KiB

Open AccessArticle

Measuring Identification and Quantification Errors in Spectral CT Material Decomposition

by Aamir Younis Raja^1,*

, Mahdieh Moghiseh¹, Christopher J. Bateman^1,2, Niels De Ruiter¹, Benjamin Schon³, Nanette Schleich⁴, Tim B. F. Woodfield³, Anthony P. H. Butler^1,2 and Nigel G. Anderson¹

¹ Department of Radiology, University of Otago, Christchurch 8011, New Zealand

² Department of Physics, University of Canterbury, Christchurch 8041, New Zealand

³ Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch 8011, New Zealand

⁴ Department of Radiation Therapy, University of Otago, Wellington 6242, New Zealand

Appl. Sci. 2018, 8(3), 467; https://doi.org/10.3390/app8030467 - 18 Mar 2018

Cited by 18 | Viewed by 6771

Abstract

Material decomposition methods are used to identify and quantify multiple tissue components in spectral CT but there is no published method to quantify the misidentification of materials. This paper describes a new method for assessing misidentification and mis-quantification in spectral CT. We scanned [...] Read more.

Material decomposition methods are used to identify and quantify multiple tissue components in spectral CT but there is no published method to quantify the misidentification of materials. This paper describes a new method for assessing misidentification and mis-quantification in spectral CT. We scanned a phantom containing gadolinium (1, 2, 4, 8 mg/mL), hydroxyapatite (54.3, 211.7, 808.5 mg/mL), water and vegetable oil using a MARS spectral scanner equipped with a poly-energetic X-ray source operated at 118 kVp and a CdTe Medipix3RX camera. Two imaging protocols were used; both with and without 0.375 mm external brass filter. A proprietary material decomposition method identified voxels as gadolinium, hydroxyapatite, lipid or water. Sensitivity and specificity information was used to evaluate material misidentification. Biological samples were also scanned. There were marked differences in identification and quantification between the two protocols even though spectral and linear correlation of gadolinium and hydroxyapatite in the reconstructed images was high and no qualitative segmentation differences in the material decomposed images were observed. At 8 mg/mL, gadolinium was correctly identified for both protocols, but concentration was underestimated by over half for the unfiltered protocol. At 1 mg/mL, gadolinium was misidentified in 38% of voxels for the filtered protocol and 58% of voxels for the unfiltered protocol. Hydroxyapatite was correctly identified at the two higher concentrations for both protocols, but mis-quantified for the unfiltered protocol. Gadolinium concentration as measured in the biological specimen showed a two-fold difference between protocols. In future, this methodology could be used to compare and optimize scanning protocols, image reconstruction methods, and methods for material differentiation in spectral CT. Full article

(This article belongs to the Special Issue Hyper- and Multi-Spectral Imaging)

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15 pages, 4774 KiB

Open AccessArticle

Development and Characterization of Two-Dimensional Gratings for Single-Shot X-ray Phase-Contrast Imaging

by Margarita Zakharova^1,*

, Vitor Vlnieska¹, Heike Fornasier¹, Martin Börner¹, Tomy dos Santos Rolo²

, Jürgen Mohr¹ and Danays Kunka¹

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

² Karlsruhe Institute of Technology (KIT), Institute of Photon Science and Synchrotron Radiation (IPS), Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Appl. Sci. 2018, 8(3), 468; https://doi.org/10.3390/app8030468 - 18 Mar 2018

Cited by 11 | Viewed by 7206

Abstract

Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and [...] Read more.

Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and increasing flux efficiency. One of the ways to upgrade single-shot imaging techniques is to utilize customized optical components, such as two-dimensional (2D) X-ray gratings. In this contribution, we present the achievements in the development of 2D gratings with UV lithography and gold electroplating. Absorption gratings represented by periodic free-standing gold pillars with lateral structure sizes from 5 µm to 25 µm and heights from 5 µm to 28 µm have shown a high degree of periodicity and defect-free patterns. Grating performance was tested in a radiographic setup using a self-developed quality assessment algorithm based on the intensity distribution histograms. The algorithm allows the final user to estimate the suitability of a specific grating to be used in a particular setup. Full article

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

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14 pages, 6482 KiB

Open AccessArticle

Evaluation of Fatigue Life of Asphalt Concrete Mixtures with Reclaimed Asphalt Pavement

by Wojciech Bańkowski

Road and Bridge Research Institute, 03-301 Warsaw, Poland

Appl. Sci. 2018, 8(3), 469; https://doi.org/10.3390/app8030469 - 19 Mar 2018

Cited by 41 | Viewed by 6898

Abstract

The topic of this article is the evaluation of the fatigue life of asphalt concrete mixtures with reclaimed asphalt pavement (RAP). The evaluation was carried out in relation to asphalt concrete mixtures AC22P and high modulus asphalt concrete ACWMS16 with 50% contents of [...] Read more.

The topic of this article is the evaluation of the fatigue life of asphalt concrete mixtures with reclaimed asphalt pavement (RAP). The evaluation was carried out in relation to asphalt concrete mixtures AC22P and high modulus asphalt concrete ACWMS16 with 50% contents of RAP, greater than currently permitted by technical regulations in Poland. The first stage consisted of the evaluation of laboratory results, which was followed by a mechanistic analysis of the designed life of pavement structures with reclaimed asphalt. The evaluation included the results of laboratory tests (i.e., the air voids content, effective asphalt content, properties of recovered asphalt (penetration, softening point), stiffness, and resistance to fatigue of bituminous mixtures). Calculations of the design life of the structure were made using the criteria according to the 2004 AASHTO specifications for fatigue life and the Asphalt Institute for subgrade deformation. In addition, calculations were carried out using the French method. The analyses allowed for a comprehensive evaluation of the asphalt concrete mixture in the analyzed scope. The evaluation of the fatigue life of AC22P and ACWMS16 mixtures with 50% content of reclaimed asphalt as well as the results of the calculations of design life of the structure indicated positive effects. The tests have been carried out within the framework of the research project dedicated to hot recycling entitled “Reclaimed asphalt pavement: Innovative technology of bituminous mixtures using material from reclaimed asphalt pavement”. Full article

(This article belongs to the Special Issue Achievements and Prospects of Advanced Pavement Materials Technologies)

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15 pages, 2277 KiB

Open AccessArticle

Polyphonic Piano Transcription with a Note-Based Music Language Model

by Qi Wang^1,2, Ruohua Zhou^1,2,* and Yonghong Yan^1,2,3

¹ Key Laboratory of Speech Acoustics and Content Understanding, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100190, China

³ Xinjiang Laboratory of Minority Speech and Language Information Processing, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumchi 830001, China

Appl. Sci. 2018, 8(3), 470; https://doi.org/10.3390/app8030470 - 19 Mar 2018

Cited by 12 | Viewed by 5247

Abstract

This paper proposes a note-based music language model (MLM) for improving note-level polyphonic piano transcription. The MLM is based on the recurrent structure, which could model the temporal correlations between notes in music sequences. To combine the outputs of the note-based MLM and [...] Read more.

This paper proposes a note-based music language model (MLM) for improving note-level polyphonic piano transcription. The MLM is based on the recurrent structure, which could model the temporal correlations between notes in music sequences. To combine the outputs of the note-based MLM and acoustic model directly, an integrated architecture is adopted in this paper. We also propose an inference algorithm, in which the note-based MLM is used to predict notes at the blank onsets in the thresholding transcription results. The experimental results show that the proposed inference algorithm improves the performance of note-level transcription. We also observe that the combination of the restricted Boltzmann machine (RBM) and recurrent structure outperforms a single recurrent neural network (RNN) or long short-term memory network (LSTM) in modeling the high-dimensional note sequences. Among all the MLMs, LSTM-RBM helps the system yield the best results on all evaluation metrics regardless of the performance of acoustic models. Full article

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

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19 pages, 7061 KiB

Open AccessArticle

Prostate Clinical Outlook Visualization System for Patients and Clinicians Considering Cyberknife Treatment—A Personalized Approach

by Jihwan Park^1,2,*

, Mi Jung Rho^2,3

, Anatoly Dritschilo⁴, In Young Choi² and Seong K. Mun¹

¹ Open Source Electronic Health Record Alliance, 1934 Old Gallows Road Suite 420, Vienna, VA 22182, USA

² Department of Medical Informatics, College of Medicine, The Catholic University of Korea, 222, Banpo-dong, Seocho-gu, Seoul 06591, Korea

³ Arlington Innovation Center, Virginia Tech, 900 N Glebe Road, Arlington, VA 22203, USA

⁴ Department of Radiation Medicine, Georgetown University Hospital, 3800 Reservoir Rd. NW, Washington, DC 20007, USA

Appl. Sci. 2018, 8(3), 471; https://doi.org/10.3390/app8030471 - 19 Mar 2018

Cited by 4 | Viewed by 5106

Abstract

Background: When a patient presents with localized prostate cancer, referral for radiation oncology consultation includes a discussion of likely outcomes of therapy. Among current radiation treatments for prostate cancers, hypo-fractionated stereotactic body radiation therapy (SBRT) has gained clinical acceptance based on efficacy, short [...] Read more.

Background: When a patient presents with localized prostate cancer, referral for radiation oncology consultation includes a discussion of likely outcomes of therapy. Among current radiation treatments for prostate cancers, hypo-fractionated stereotactic body radiation therapy (SBRT) has gained clinical acceptance based on efficacy, short duration of treatment, and the potential radiobiological advantages. The Prostate Clinical Outlook Visualization System (PCOVS) was developed to provide the patient and the clinician with a tool to visualize probable treatment outcomes using institutional, patient specific data for comparing results of treatment. Methods: We calculated the prostate cancer outcomes—for each prospective patient using the EPIC-26 quality of life parameters based on clinical outcomes data of 580 prostate cancer patients who were treated with SBRT. We applied Kaplan-Meier analysis using the ASTRO definition for biochemical recurrence (BCR) free survival and likely outcome and the PCOVS nomogram to calculate parameters for quality of life. Open-source R, RShiny, and MySQL were used to develop a modularized architecture system. Results: The PCOVS presents patient specific risk scores in a gauge chart style and risk free probability bar plots to compare the treatment data of patients treated with SBRT. The PCOVS generates reports, in PDF, which consists of a comparison charts of risk free probabilities late effects and gauge charts of risk scores. This system is now being expanded as a web-based service to patients. Conclusions: The PCOVS visualized patient specific likely outcomes were compared to treatment data from a single department, helping the patient and the clinician to visualize likely outcomes. The PCOVS approach can be expanded to other specialties of oncology with the flexible, modularized architecture, which can be customized by changing independent modules. Full article

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9 pages, 25106 KiB

Open AccessArticle

Dispersion Properties of an Elliptical Patch with Cross-Shaped Aperture for Synchronized Propagation of Transverse Magnetic and Electric Surface Waves

by Amagoia Tellechea^1,*, Iñigo Ederra^1,2

, Ramón Gonzalo^1,2 and Juan Carlos Iriarte^1,2

¹ Campus Arrosadía, Public University of Navarra, 31006 Pamplona, Navarra, Spain

² Campus Arrosadía, Institute of Smart Cities, 31006 Pamplona, Navarra, Spain

Appl. Sci. 2018, 8(3), 472; https://doi.org/10.3390/app8030472 - 19 Mar 2018

Cited by 1 | Viewed by 4845

Abstract

This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synchronized phase propagation of transverse magnetic (TM) and transverse electric (TE) modes. The pixel is composed by an elliptical metallic patch with an asymmetric cross-shaped aperture in the center, printed [...] Read more.

This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synchronized phase propagation of transverse magnetic (TM) and transverse electric (TE) modes. The pixel is composed by an elliptical metallic patch with an asymmetric cross-shaped aperture in the center, printed on a grounded slab. A practical implementation of a metasurface was carried out employing such a pixel geometry. Simulation results show similar frequency dispersion properties for both modes within the working frequency band, in agreement with the theoretical basis. Full article

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

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19 pages, 3584 KiB

Open AccessArticle

Multi-Objective Motion Control Optimization for the Bridge Crane System

by Renxin Xiao

, Zelin Wang

, Ningyuan Guo, Yitao Wu, Jiangwei Shen and Zheng Chen^*

Faculty of Transportation Engineering, Kunming University of Science and Technology, Kunming 650500, China

Appl. Sci. 2018, 8(3), 473; https://doi.org/10.3390/app8030473 - 20 Mar 2018

Cited by 8 | Viewed by 5213

Abstract

A novel control algorithm combining the linear quadratic regulator (LQR) control and trajectory planning (TP) is proposed for the control of an underactuated crane system, targeting position adjustment and swing suppression. The TP is employed to control the swing angle within certain constraints, [...] Read more.

A novel control algorithm combining the linear quadratic regulator (LQR) control and trajectory planning (TP) is proposed for the control of an underactuated crane system, targeting position adjustment and swing suppression. The TP is employed to control the swing angle within certain constraints, and the LQR is applied to achieve anti-disturbance. In order to improve the accuracy of the position control, a differential-integral control loop is applied. The weighted LQR matrices representing priorities of the state variables for the bridge crane motion are searched by the multi-objective genetic algorithm (MOGA). The stability proof is provided in order to validate the effectiveness of the proposed algorithm. Numerous simulation and experimental validations justify the feasibility of the proposed method. Full article

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Review

Jump to: Editorial, Research

28 pages, 2548 KiB

Open AccessReview

Imaging Electron Dynamics with Ultrashort Light Pulses: A Theory Perspective

by Daria Popova-Gorelova^1,2

¹ Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany

² The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany

Appl. Sci. 2018, 8(3), 318; https://doi.org/10.3390/app8030318 - 25 Feb 2018

Cited by 13 | Viewed by 4801

Abstract

A wide range of ultrafast phenomena in various atomic, molecular and condense matter systems is governed by electron dynamics. Therefore, the ability to image electronic motion in real space and real time would provide a deeper understanding of such processes and guide developments [...] Read more.

A wide range of ultrafast phenomena in various atomic, molecular and condense matter systems is governed by electron dynamics. Therefore, the ability to image electronic motion in real space and real time would provide a deeper understanding of such processes and guide developments of tools to control them. Ultrashort light pulses, which can provide unprecedented time resolution approaching subfemtosecond time scale, are perspective to achieve real-time imaging of electron dynamics. This task is challenging not only from an experimental view, but also from a theory perspective, since standard theories describing light-matter interaction in a stationary regime can provide erroneous results in an ultrafast case as demonstrated by several theoretical studies. We review the theoretical framework based on quantum electrodynamics, which has been shown to be necessary for an accurate description of time-resolved imaging of electron dynamics with ultrashort light pulses. We compare the results of theoretical studies of time-resolved nonresonant and resonant X-ray scattering, and time- and angle-resolved photoelectron spectroscopy and show that the corresponding time-resolved signals encode analogous information about electron dynamics. Thereby, the information about an electronic system provided by these time-resolved techniques is different from the information provided by their time-independent analogues. Full article

(This article belongs to the Special Issue Extreme Time Scale Photonics)

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8 pages, 1265 KiB

Open AccessFeature PaperReview

Real Time Quantum Dynamics of Spontaneous Translational Symmetry Breakage in the Early Stage of Photo-Induced Structural Phase Transitions

by Keiichiro Nasu

Institute of Material Structure Science, KEK, 1-1, Oho, Tsukuba 305-0801, Japan

Appl. Sci. 2018, 8(3), 332; https://doi.org/10.3390/app8030332 - 27 Feb 2018

Cited by 1 | Viewed by 2776

Abstract

Real time quantum dynamics of the spontaneous translational symmetry breakage in the early stage of photo-induced structural phase transitions is reviewed and supplementally explained, under the guide of the Toyozawa theory, which is exactly in compliance with the conservation laws of the total [...] Read more.

Real time quantum dynamics of the spontaneous translational symmetry breakage in the early stage of photo-induced structural phase transitions is reviewed and supplementally explained, under the guide of the Toyozawa theory, which is exactly in compliance with the conservation laws of the total momentum and energy. At the Franck-Condon state, an electronic excitation just created by a visible light, is in a plane wave state, which is extended all over the crystal. While, after the lattice relaxation having been completed, it is localized around a certain lattice site of the crystal, as a new excitation. Is there a sudden shrinkage of the excitation wave function, in between? No! The wave function never shrinks, but only the spatial (or inter lattice-site) quantum coherence (interference) of the excitation disappears, as the lattice relaxation proceeds. This is nothing but the spontaneous breakage of translational symmetry. Full article

(This article belongs to the Special Issue Photoinduced Cooperative Phenomena)

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15 pages, 2546 KiB

Open AccessEditor’s ChoiceReview

Polydimethylsiloxane (PDMS)-Based Flexible Resistive Strain Sensors for Wearable Applications

by Jing Chen^1,2, Jiahong Zheng¹, Qinwu Gao², Jinjie Zhang², Jinyong Zhang², Olatunji Mumini Omisore², Lei Wang^2,*

and Hui Li^2,*

¹ School of Mechanical and Electrical Engineering, Shaanxi University of Science & Technology, Xi’an 710021, China

² Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

Appl. Sci. 2018, 8(3), 345; https://doi.org/10.3390/app8030345 - 28 Feb 2018

Cited by 274 | Viewed by 24616

Abstract

There is growing attention and rapid development on flexible electronic devices with electronic materials and sensing technology innovations. In particular, strain sensors with high elasticity and stretchability are needed for several potential applications including human entertainment technology, human–machine interface, personal healthcare, and sports [...] Read more.

There is growing attention and rapid development on flexible electronic devices with electronic materials and sensing technology innovations. In particular, strain sensors with high elasticity and stretchability are needed for several potential applications including human entertainment technology, human–machine interface, personal healthcare, and sports performance monitoring, etc. This article presents recent advancements in the development of polydimethylsiloxane (PDMS)-based flexible resistive strain sensors for wearable applications. First of all, the article shows that PDMS-based stretchable resistive strain sensors are successfully fabricated by different methods, such as the filtration method, printing technology, micromolding method, coating techniques, and liquid phase mixing. Next, strain sensing performances including stretchability, gauge factor, linearity, and durability are comprehensively demonstrated and compared. Finally, potential applications of PDMS-based flexible resistive strain sensors are also discussed. This review indicates that the era of wearable intelligent electronic systems has arrived. Full article

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20 pages, 1166 KiB

Open AccessReview

On the Vehicle Sideslip Angle Estimation: A Literature Review of Methods, Models, and Innovations

by Daniel Chindamo^1,*

, Basilio Lenzo²

and Marco Gadola¹

¹ Department of Industrial and Mechanical Engineering, Automotive Group, University of Brescia, I-25123 Brescia, Italy

² Department of Engineering and Mathematics, Sheffield Hallam University, Sheffield S1 1WB, UK

Appl. Sci. 2018, 8(3), 355; https://doi.org/10.3390/app8030355 - 1 Mar 2018

Cited by 140 | Viewed by 16186

Abstract

Typical active safety systems that control the dynamics of passenger cars rely on the real-time monitoring of the vehicle sideslip angle (VSA), together with other signals such as the wheel angular velocities, steering angle, lateral acceleration, and the rate of rotation about the [...] Read more.

Typical active safety systems that control the dynamics of passenger cars rely on the real-time monitoring of the vehicle sideslip angle (VSA), together with other signals such as the wheel angular velocities, steering angle, lateral acceleration, and the rate of rotation about the vertical axis, which is known as the yaw rate. The VSA (also known as the attitude or “drifting” angle) is defined as the angle between the vehicle’s longitudinal axis and the direction of travel, taking the centre of gravity as a reference. It is basically a measure of the misalignment between vehicle orientation and trajectory; therefore, it is a vital piece of information enabling directional stability assessment, such as in transience following emergency manoeuvres, for instance. As explained in the introduction, the VSA is not measured directly for impracticality, and it is estimated on the basis of available measurements such as wheel velocities, linear and angular accelerations, etc. This work is intended to provide a comprehensive literature review on the VSA estimation problem. Two main estimation methods have been categorised, i.e., observer-based and neural network-based, focussing on the most effective and innovative approaches. As the first method normally relies on a vehicle model, a review of the vehicle models has been included. The advantages and limitations of each technique have been highlighted and discussed. Full article

(This article belongs to the Section Mechanical Engineering)

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18 pages, 5709 KiB

Open AccessReview

Orbital Angular Momentum Generation and Detection by Geometric-Phase Based Metasurfaces

by Menglin L. N. Chen^1,2

, Li Jun Jiang^1,2,* and Wei E. I. Sha^3,*

¹ Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China

² HKU Shenzhen Institute of Research and Innovation, Shenzhen 518057, China

³ Key Laboratory of Micro-Nano Electronic Devices and Smart Systems of Zhejiang Province, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China

Appl. Sci. 2018, 8(3), 362; https://doi.org/10.3390/app8030362 - 2 Mar 2018

Cited by 95 | Viewed by 12222 | Correction

Abstract

We present a comprehensive review on the geometric-phase based metasurfaces for orbital angular momentum (OAM) generation and detection. These metasurfaces manipulate the electromagnetic (EM) wave by introducing abrupt phase change, which is strongly dependent on the polarization state of incident EM wave and [...] Read more.

We present a comprehensive review on the geometric-phase based metasurfaces for orbital angular momentum (OAM) generation and detection. These metasurfaces manipulate the electromagnetic (EM) wave by introducing abrupt phase change, which is strongly dependent on the polarization state of incident EM wave and can be interpreted by geometric phase. Hence, the conventional bulk devices that based on the accumulated phase change along the optical path can be avoided. Full article

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

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17 pages, 3977 KiB

Open AccessFeature PaperReview

Core@shell Nanoparticles: Greener Synthesis Using Natural Plant Products

by Mehrdad Khatami^1,2,*

, Hajar Q. Alijani^1,3, Meysam S. Nejad⁴

and Rajender S. Varma^5,*

¹ NanoBioelectrochemistry Research Center, Bam University of Medical Sciences, Bam, Iran

² Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran

³ Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Iran

⁴ Research Center for Tropical and Infectious Diseases, Kerman University of Medical Sciences, Kerman, Iran

⁵ Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic

Appl. Sci. 2018, 8(3), 411; https://doi.org/10.3390/app8030411 - 10 Mar 2018

Cited by 159 | Viewed by 18559

Abstract

Among an array of hybrid nanoparticles, core-shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the center, while the other material/materials that were located around the central core develops a shell. [...] Read more.

Among an array of hybrid nanoparticles, core-shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the center, while the other material/materials that were located around the central core develops a shell. Core-shell nanostructures are useful entities with high thermal and chemical stability, lower toxicity, greater solubility, and higher permeability to specific target cells. Plant or natural products-mediated synthesis of nanostructures refers to the use of plants or its extracts for the synthesis of nanostructures, an emerging field of sustainable nanotechnology. Various physiochemical and greener methods have been advanced for the synthesis of nanostructures, in contrast to conventional approaches that require the use of synthetic compounds for the assembly of nanostructures. Although several biological resources have been exploited for the synthesis of core-shell nanoparticles, but plant-based materials appear to be the ideal candidates for large-scale green synthesis of core-shell nanoparticles. This review summarizes the known strategies for the greener production of core-shell nanoparticles using plants extract or their derivatives and highlights their salient attributes, such as low costs, the lack of dependence on the use of any toxic materials, and the environmental friendliness for the sustainable assembly of stabile nanostructures. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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11 pages, 973 KiB

Open AccessReview

New Advances and Challenges of Fall Detection Systems: A Survey

by Tao Xu¹, Yun Zhou^2,* and Jing Zhu¹

¹ School of Software and Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an 710072, Shaanxi, China

² School of Education, Shaanxi Normal University, 199 South Chang’an Road, Xi’an 710062, Shaanxi, China

Appl. Sci. 2018, 8(3), 418; https://doi.org/10.3390/app8030418 - 12 Mar 2018

Cited by 157 | Viewed by 14097

Abstract

Falling, as one of the main harm threats to the elderly, has drawn researchers’ attentions and has always been one of the most valuable research topics in the daily health-care for the elderly in last two decades. Before 2014, several researchers reviewed the [...] Read more.

Falling, as one of the main harm threats to the elderly, has drawn researchers’ attentions and has always been one of the most valuable research topics in the daily health-care for the elderly in last two decades. Before 2014, several researchers reviewed the development of fall detection, presented issues and challenges, and navigated the direction for the study in the future. With smart sensors and Internet of Things (IoT) developing rapidly, this field has made great progress. However, there is a lack of a review and discussion on novel sensors, technologies and algorithms introduced and employed from 2014, as well as the emerging challenges and new issues. To bridge this gap, we present an overview of fall detection research and discuss the core research questions on this topic. A total of 6830 related documents were collected and analyzed based on the key words. Among these documents, the twenty most influential and highly cited articles are selected and discussed profoundly from three perspectives: sensors, algorithms and performance. The findings would assist researchers in understanding current developments and barriers in the systems of fall detection. Although researchers achieve fruitful work and progress, this research domain still confronts challenges on theories and practice. In the near future, the new solutions based on advanced IoT will sustainably urge the development to prevent falling injuries. Full article

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

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21 pages, 2643 KiB

Open AccessReview

Recent Progress on Aberration Compensation and Coherent Noise Suppression in Digital Holography

by Yun Liu^1,*

, Zhao Wang^2,* and Junhui Huang²

¹ Key Lab of NC Machine Tools and Integrated Manufacturing Equipment of the Education Ministry & Key Lab of Mechanical Manufacturing Equipment of Shaanxi Province, Xi’an University of Technology, Xi’an 710048, China

² School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Appl. Sci. 2018, 8(3), 444; https://doi.org/10.3390/app8030444 - 15 Mar 2018

Cited by 36 | Viewed by 6301

Abstract

Digital holographic microscopy (DHM) is a topographic measurement technique that permits full-field, nondestructive, dynamic, quantitative amplitude, and phase-contrast imaging. The technique may realize the lateral resolution with submicron scale and the longitudinal resolution with subnanometer scale, respectively. Improving imaging quality has always been [...] Read more.

Digital holographic microscopy (DHM) is a topographic measurement technique that permits full-field, nondestructive, dynamic, quantitative amplitude, and phase-contrast imaging. The technique may realize the lateral resolution with submicron scale and the longitudinal resolution with subnanometer scale, respectively. Improving imaging quality has always been the research focus in DHM since it has a direct effect on the precise topographic measurement. In this paper, the recent progress on phase aberration compensation and coherent noise suppression is reviewed. Included in this review are the hologram spectrum’s centering judgment methods of side band in tilt phase error compensation, the physical and numerical compensation methods in phase aberration compensation, and the single-shot digital process methods in coherent noise suppression. The summaries and analyses for these approaches can contribute to improving the imaging quality and reducing the measurement error of DHM, which will further promote the wider applications of DHM in the topographic measurement fields, such as biology and micro-electro mechanical systems. Full article

(This article belongs to the Special Issue Holography and 3D Imaging: Tomorrows Ultimate Experience)

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