Applied Sciences

Editorial

3 pages, 148 KiB

Open AccessEditorial

Editorial for Special Issue: “Application of Artificial Neural Networks in Geoinformatics”

by Saro Lee^1,2

¹ Geological Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 124, Gwahak-ro Yuseong-gu, Daejeon 34132, Korea

² Department of Geophysical Exploration, Korea University of Science and Technology, 217 Gajeong-ro Yuseong-gu, Daejeon 34113, Korea

Appl. Sci. 2018, 8(1), 55; https://doi.org/10.3390/app8010055 - 2 Jan 2018

Cited by 4 | Viewed by 2857

Abstract

Recently, a need has arisen for prediction techniques that can address a variety of problems by combining methods from the rapidly developing field of machine learning with geoinformation technologies such as GIS, remote sensing, and GPS.[…] Full article

(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)

52 pages, 1958 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Applied Sciences and Announcement of the 2017 Outstanding Reviewer Awards Winners

by Applied Sciences Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

Appl. Sci. 2018, 8(1), 133; https://doi.org/10.3390/app8010133 - 18 Jan 2018

Viewed by 13492

Abstract

Peer review is an essential part in the publication process, ensuring that Applied Sciences maintains high quality standards for its published papers [...]
Full article

Research

Jump to: Editorial, Review, Other

5 pages, 905 KiB

Open AccessArticle

A High-Power Continuous-Wave Mid-Infrared Optical Parametric Oscillator Module

by Yichen Liu¹, Xukai Xie¹, Jian Ning^1,2, Xinjie Lv^1,2,*, Gang Zhao^1,2, Zhenda Xie^1,3,* and Shining Zhu¹

¹ National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China

² College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China

³ School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China

Appl. Sci. 2018, 8(1), 1; https://doi.org/10.3390/app8010001 - 21 Dec 2017

Cited by 34 | Viewed by 5903

Abstract

We demonstrate here a compact optical parametric oscillator module for mid-infrared generation via nonlinear frequency conversion. This module weighs only 2.5 kg and fits within a small volume of 220 × 60 × 55 mm³. The module can be easily aligned [...] Read more.

We demonstrate here a compact optical parametric oscillator module for mid-infrared generation via nonlinear frequency conversion. This module weighs only 2.5 kg and fits within a small volume of 220 × 60 × 55 mm³. The module can be easily aligned to various pump laser sources, and here we use a 50 W ytterbium (Yb)-doped fiber laser as an example. With a two-channel MgO-doped periodically poled lithium niobate crystal (MgO:PPLN), our module covers a tuning range of 2416.17–2932.25 nm and 3142.18–3452.15 nm. The highest output power exceeds 10.4 W at 2.7 μm, corresponding to a conversion efficiency of 24%. The measured power stability is 2.13% Root Meat Square (RMS) for a 10 h duration under outdoor conditions. Full article

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

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18 pages, 1417 KiB

Open AccessArticle

A Network-Based Method for the EMU Train High-Level Maintenance Planning Problem

by Jianping Wu, Boliang Lin^*

, Jiaxi Wang and Siqi Liu

School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China

Appl. Sci. 2018, 8(1), 2; https://doi.org/10.3390/app8010002 - 21 Dec 2017

Cited by 15 | Viewed by 4519

Abstract

Electric Multiple Unit (EMU) high-level maintenance planning is a typical discrete system. EMU high-level maintenance (HM) planning determines when to undergo HM or execute transportation task for train-sets, based on practical requirements such as passenger transport demand, workshop maintenance capacity, and maintenance regulations. [...] Read more.

Electric Multiple Unit (EMU) high-level maintenance planning is a typical discrete system. EMU high-level maintenance (HM) planning determines when to undergo HM or execute transportation task for train-sets, based on practical requirements such as passenger transport demand, workshop maintenance capacity, and maintenance regulations. This research constructs a time-state network that can display the transformation processes between different states. On this basis, a path based model and its improvement are developed to minimize the HM costs with consideration of all necessary regulations and practical constraints. To handle the solution space, a path set generation method is presented. A real-world instance from Shanghai Railway, which is the largest affiliate in China Railway Corporation, was conducted to demonstrate the efficiency and effectiveness of the proposed approach, which indicates that the model can be solved to optimum within short computational times by the state-of-the-art solver Gurobi. Moreover, a sensitivity analysis was also performed to evaluate the effects of the variation in average daily operating mileage, HM capacity at the depot and the assumed minimum value of cumulative mileage. Full article

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23 pages, 7131 KiB

Open AccessArticle

Modeling of Malachite Green Removal from Aqueous Solutions by Nanoscale Zerovalent Zinc Using Artificial Neural Network

by Wenqian Ruan¹, Xuedan Shi¹, Jiwei Hu^1,2,*, Yu Hou¹, Mingyi Fan¹

, Rensheng Cao¹ and Xionghui Wei³

¹ Guizhou Provincial Key Laboratory for Information Systems of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang 550001, China

² Cultivation Base of Guizhou National Key Laboratory of Mountainous Karst Eco-Environment, Guizhou Normal University, Guiyang 550001, China

³ Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

Appl. Sci. 2018, 8(1), 3; https://doi.org/10.3390/app8010003 - 21 Dec 2017

Cited by 17 | Viewed by 4743

Abstract

The commercially available nanoscale zerovalent zinc (nZVZ) was used as an adsorbent for the removal of malachite green (MG) from aqueous solutions. This material was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The advanced experimental design tools were adopted to study the [...] Read more.

The commercially available nanoscale zerovalent zinc (nZVZ) was used as an adsorbent for the removal of malachite green (MG) from aqueous solutions. This material was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The advanced experimental design tools were adopted to study the effect of process parameters (viz. initial pH, temperature, contact time and initial concentration) and to reduce number of trials and cost. Response surface methodology and rapidly developing artificial intelligence technologies, i.e., artificial neural network coupled with particle swarm optimization (ANN-PSO) and artificial neural network coupled with genetic algorithm (ANN-GA) were employed for predicting the optimum process variables and obtaining the maximum removal efficiency of MG. The results showed that the removal efficiency predicted by ANN-GA (94.12%) was compatible with the experimental value (90.72%). Furthermore, the Langmuir isotherm was found to be the best model to describe the adsorption of MG onto nZVZ, while the maximum adsorption capacity was calculated to be 1000.00 mg/g. The kinetics for adsorption of MG onto nZVZ was found to follow the pseudo-second-order kinetic model. Thermodynamic parameters (ΔG⁰, ΔH⁰ and ΔS⁰) were calculated from the Van’t Hoff plot of lnKc vs. 1/T in order to discuss the removal mechanism of MG. Full article

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

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14 pages, 7345 KiB

Open AccessArticle

Characterizing the Dissolution Rate of CO₂-Brine in Porous Media under Gaseous and Supercritical Conditions

by Bohao Wu¹

, Xingbo Li¹, Ying Teng¹, Pengfei Lv¹, Yu Liu¹, Tingting Luo¹, Jianan Zheng¹, Dayong Wang¹ and Lanlan Jiang^1,2,*

¹ Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China

² Research Institute of Innovative Technology for the Earth, Kizugawa City, Kyoto 619-0292, Japan

Appl. Sci. 2018, 8(1), 4; https://doi.org/10.3390/app8010004 - 21 Dec 2017

Cited by 7 | Viewed by 4504

Abstract

The CO₂-brine dissolution homogenizes the distribution of residual CO₂ and reduces the leakage risk in the saline aquifer. As a key parameter to immobilize the free CO₂, the dissolution rate of CO₂-brine could be accelerated through [...] Read more.

The CO₂-brine dissolution homogenizes the distribution of residual CO₂ and reduces the leakage risk in the saline aquifer. As a key parameter to immobilize the free CO₂, the dissolution rate of CO₂-brine could be accelerated through mechanisms like diffusion and dispersion, which are affected by the subsurface condition, pore structure, and background hydrological flow. This study contributed the calculated dissolution rates of both gaseous and supercritical CO₂ during brine imbibition at a pore-scale. The flow development and distribution in porous media during dynamic dissolution were imaged in two-dimensional visualization using X-ray microtomography. The fingerings branching and expansion resulted in greater dissolution rates of supercritical CO₂ with high contact between phases, while the brine bypassed the clusters of gaseous CO₂ with a slower dissolution and longer duration due to the isolated bubbles. The dissolution rate of supercritical CO₂ was about two or three orders of magnitude greater than that of gaseous CO₂, while the value distributions both spanned about four orders of magnitude. The dissolution rates of gaseous CO₂ increased with porosity, but the relationship was the opposite for supercritical CO₂. CO₂ saturation and the Reynolds number were analyzed to characterize the different impacts on gaseous and supercritical CO₂ at different dissolution periods. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

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9 pages, 1231 KiB

Open AccessArticle

Temporal Response of Ultrafast Grating Monochromators

by Luca Poletto^*

and Fabio Frassetto

CNR—Institute of Photonics and Nanotechnologies, 35131 Padova, Italy

Appl. Sci. 2018, 8(1), 5; https://doi.org/10.3390/app8010005 - 21 Dec 2017

Cited by 6 | Viewed by 4496

Abstract

The temporal response of double-grating monochromators is analyzed considering two effects on the ultrafast pulse given by the configuration. The first effect is the compensation of the pulse-front tilt, i.e., all the rays emitted by the source in different directions at the same [...] Read more.

The temporal response of double-grating monochromators is analyzed considering two effects on the ultrafast pulse given by the configuration. The first effect is the compensation of the pulse-front tilt, i.e., all the rays emitted by the source in different directions at the same wavelength have to travel the same optical path. The second effect is the group delay introduced by the two gratings, i.e., different wavelengths within the bandwidth transmitted by the slit travel different paths. The methodology to calculate the group delay introduced by the double-grating configuration is presented. Some practical design examples are provided to show the design rules and the achieved performances. Full article

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

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23 pages, 2376 KiB

Open AccessFeature PaperArticle

A Synthetic Nervous System Controls a Simulated Cockroach

by Scott Rubeo^*, Nicholas Szczecinski and Roger Quinn

Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA

Appl. Sci. 2018, 8(1), 6; https://doi.org/10.3390/app8010006 - 22 Dec 2017

Cited by 15 | Viewed by 5892

Abstract

The purpose of this work is to better understand how animals control locomotion. This knowledge can then be applied to neuromechanical design to produce more capable and adaptable robot locomotion. To test hypotheses about animal motor control, we model animals and their nervous [...] Read more.

The purpose of this work is to better understand how animals control locomotion. This knowledge can then be applied to neuromechanical design to produce more capable and adaptable robot locomotion. To test hypotheses about animal motor control, we model animals and their nervous systems with dynamical simulations, which we call synthetic nervous systems (SNS). However, one major challenge is picking parameter values that produce the intended dynamics. This paper presents a design process that solves this problem without the need for global optimization. We test this method by selecting parameter values for SimRoach2, a dynamical model of a cockroach. Each leg joint is actuated by an antagonistic pair of Hill muscles. A distributed SNS was designed based on pathways known to exist in insects, as well as hypothetical pathways that produced insect-like motion. Each joint’s controller was designed to function as a proportional-integral (PI) feedback loop and tuned with numerical optimization. Once tuned, SimRoach2 walks through a simulated environment, with several cockroach-like features. A model with such reliable low-level performance is necessary to investigate more sophisticated locomotion patterns in the future. Full article

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

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16 pages, 5953 KiB

Open AccessArticle

A Method to Decompose the Streamed Acoustic Emission Signals for Detecting Embedded Fatigue Crack Signals

by Lu Zhang¹, Didem Ozevin^1,*, David He²

, William Hardman³ and Alan Timmons³

¹ Civil and Materials Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA

² Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA

³ NAVAIR NAS Patuxent River, St. Mary’s County, MD 20670, USA

Appl. Sci. 2018, 8(1), 7; https://doi.org/10.3390/app8010007 - 22 Dec 2017

Cited by 11 | Viewed by 4805

Abstract

The data collection of Acoustic Emission (AE) method is typically based on threshold-dependent approach, where the AE system acquires data when the output of AE sensor is above the pre-defined threshold. However, this approach fails to detect flaws in noisy environment, as the [...] Read more.

The data collection of Acoustic Emission (AE) method is typically based on threshold-dependent approach, where the AE system acquires data when the output of AE sensor is above the pre-defined threshold. However, this approach fails to detect flaws in noisy environment, as the signal level of noise may overcome the signal level of AE from flaws, and saturate the AE system. Time-dependent approach is based on streaming waveforms and extracting features at every pre-defined time interval. It is hypothesized that the relevant AE signals representing active flaws are embedded into the streamed signals. In this study, a decomposition method of the streamed AE signals to separate noise signal and crack signal is demonstrated. The AE signals representing fatigue crack growth in steel are obtained from the laboratory scale testing. The streamed AE signals in a noisy operational condition are obtained from the gearbox testing at the Naval Air Systems Command (NAVAIR) facility. The signal addition and decomposition is achieved to determine the minimum detectable signal to noise ratio that is embedded into the streamed AE signals. The developed decomposition approach is demonstrated on detecting burst signals embedded into the streamed signals recorded in the spline testing of the helicopter gearbox test rig located at the NAVAIR facility. Full article

(This article belongs to the Section Acoustics and Vibrations)

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19 pages, 3683 KiB

Open AccessArticle

Rule Based Coordinated Control of Domestic Combined Micro-CHP and Energy Storage System for Optimal Daily Cost

by Dezhi Li^1,2, Xinyi Xu¹, Dongmin Yu^1,*

, Mingyu Dong² and Huanan Liu^1,3

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

² China Electric Power Research Institute, Beijing 100192, China

³ Beijing Key Laboratory of Demand Side Multi-Energy Carriers Optimization and Interaction Technique, Beijing 100192, China

Appl. Sci. 2018, 8(1), 8; https://doi.org/10.3390/app8010008 - 22 Dec 2017

Cited by 14 | Viewed by 4134

Abstract

This paper presents a novel control algorithm for optimising operational costs of a combined domestic micro-CHP (combined heat and power), battery and heat storage system. Using a minute by minute basic time-step, this work proposes a simple and computationally efficient rule based whole-system [...] Read more.

This paper presents a novel control algorithm for optimising operational costs of a combined domestic micro-CHP (combined heat and power), battery and heat storage system. Using a minute by minute basic time-step, this work proposes a simple and computationally efficient rule based whole-system management, developed from empirical study of realistic simulated domestic electricity and heat loads. The CHP availability is considered in two binary states which, together with leveraging storage effectively, maximises CHP efficiency, and gives the algorithm increased real world feasibility. In addition, a novel application of a dual battery system is proposed to support the micro-CHP with each battery supplying just one of the distinctive morning and evening electrical load peaks, and thus inherently improving overall battery system lifetime. A case study is presented where the algorithm is shown to yield approximately 23% energy cost savings above the base case, almost 3% higher savings than that of the closest previous work, and 96.8% of the theoretical minimum cost. In general, the algorithm is shown to always yield better than 88% of the theoretical minimum cost, a ratio that will be considerably higher when real-world CHP limitations are factored into the theoretical minimum calculation. Full article

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

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16 pages, 1895 KiB

Open AccessFeature PaperArticle

Online Identification of Photovoltaic Source Parameters by Using a Genetic Algorithm

by Giovanni Petrone^1,*,†

, Massimiliano Luna²

, Giuseppe La Tona²

, Maria Carmela Di Piazza²

and Giovanni Spagnuolo¹

¹ Dipartimento di Ingegneria dell’Informazione ed Elettrica e Matematica Applicata, Università degli Studi di Salerno, 84084-Fisciano, Italy

² Consiglio Nazionale delle Ricerche, Istituto di Studi sui Sistemi Intelligenti per l’Automazione, 90146-Palermo, Italy

^† Current address: Via Giovanni Paolo II n.132-84084 Fisciano, Salerno, Italy.

Appl. Sci. 2018, 8(1), 9; https://doi.org/10.3390/app8010009 - 22 Dec 2017

Cited by 14 | Viewed by 4438

Abstract

In this paper, an efficient method for the online identification of the photovoltaic single-diode model parameters is proposed. The combination of a genetic algorithm with explicit equations allows obtaining precise results without the direct measurement of short circuit current and open circuit voltage [...] Read more.

In this paper, an efficient method for the online identification of the photovoltaic single-diode model parameters is proposed. The combination of a genetic algorithm with explicit equations allows obtaining precise results without the direct measurement of short circuit current and open circuit voltage that is typically used in offline identification methods. Since the proposed method requires only voltage and current values close to the maximum power point, it can be easily integrated into any photovoltaic system, and it operates online without compromising the power production. The proposed approach has been implemented and tested on an embedded system, and it exhibits a good performance for monitoring/diagnosis applications. Full article

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

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13 pages, 3252 KiB

Open AccessArticle

Attenuation of Temperature Fluctuations on an External Surface of the Wall by a Phase Change Material-Activated Layer

by Dariusz Heim^*

and Anna Wieprzkowicz

Department of Environmental Engineering, Lodz University of Technology, ul. Wolczanska 213, 90-924 Lodz, Poland

Appl. Sci. 2018, 8(1), 11; https://doi.org/10.3390/app8010011 - 22 Dec 2017

Cited by 18 | Viewed by 4395

Abstract

Periodical changes of temperature on an external surface of building envelope, e.g., thermal stress or excessive heat gains, is often an undesirable phenomenon. The idea proposed and described in the following paper is to stabilize the external surface temperature in a period of [...] Read more.

Periodical changes of temperature on an external surface of building envelope, e.g., thermal stress or excessive heat gains, is often an undesirable phenomenon. The idea proposed and described in the following paper is to stabilize the external surface temperature in a period of significant heat gains by the originally developed, novel composite modified by phase change material (PCM) and applied as an external, thin finishing plaster layer. The PCM composite is made from porous, granulated perlite soaked with paraffin wax (T_m = 25 °C) and macro-encapsulated by synthetic resin. The effect of temperature attenuation was estimated for two designated periods of time—the heat gains season (HGS) and the heat losses season (HLS). The attenuation coefficient (AC) was proposed as evaluation parameter of isothermal storage of heat gains determining the reduction of temperature fluctuations. The maximum registered temperature of an external surface for a standard insulation layer was around 20 K higher than for the case modified by PCM. The calculated values of AC were relatively constant during HGS and around two times lower for PCM case. The obtained results confirmed that the proposed modification of an external partition by equipped with additional PCM layer can be effectively used to minimize temperature variations and heat flux in the heat gains season. Full article

(This article belongs to the Special Issue Phase Change Material (PCM) 2017)

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10 pages, 2489 KiB

Open AccessArticle

Na-Doping Effects on Thermoelectric Properties of Cu_2−xSe Nanoplates

by Yingshi Jin, Mi-Kyung Han^* and Sung-Jin Kim^*

Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea

Appl. Sci. 2018, 8(1), 12; https://doi.org/10.3390/app8010012 - 22 Dec 2017

Cited by 28 | Viewed by 6887

Abstract

For this work, a β-phase Cu_2−xSe nanowire and nanoplate, and a Na-doped Cu_2−xSe nanoplate were successfully synthesized using solution syntheses. The morphologies of the Cu_2−xSe nanowire and nanoplate could be easily controlled by changing the synthetic condition. [...] Read more.

For this work, a β-phase Cu_2−xSe nanowire and nanoplate, and a Na-doped Cu_2−xSe nanoplate were successfully synthesized using solution syntheses. The morphologies of the Cu_2−xSe nanowire and nanoplate could be easily controlled by changing the synthetic condition. The Na-doped Cu_2−xSe nanoplate was prepared by a simple treatment of the Cu_2−xSe nanoplate with a sodium hydroxide-ethylene glycol solution. The nanopowders were then consolidated to bulk materials using spark plasma sintering (SPS). The phase structure and the microstructure of all of the samples were checked using X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), and scanning electron microscope (SEM) analyses. The thermoelectric transport properties, such as the electrical conductivity, Seebeck coefficient, carrier concentration, carrier mobility, and thermal conductivity, were measured at temperature ranges from 323 to 673 K. The results show that Na played two important roles: one is reducing the carrier concentration, thereby improving the Seebeck coefficient, the other is reducing the thermal conductivity. Overall, the maximum thermoelectric figure of merit (ZT) of 0.24 was achieved at 673 K in the Na-doped Cu_2−xSe nanoplate. Full article

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

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18 pages, 2581 KiB

Open AccessArticle

Study on Driving Decision-Making Mechanism of Autonomous Vehicle Based on an Optimized Support Vector Machine Regression

by Junyou Zhang^*, Yaping Liao, Shufeng Wang^* and Jian Han

College of Transportation, Shandong University of Science and Technology, Huangdao District, Qingdao 266590, China

Appl. Sci. 2018, 8(1), 13; https://doi.org/10.3390/app8010013 - 22 Dec 2017

Cited by 52 | Viewed by 9234

Abstract

Driving Decision-making Mechanism (DDM) is identified as the key technology to ensure the driving safety of autonomous vehicle, which is mainly influenced by vehicle states and road conditions. However, previous studies have seldom considered road conditions and their coupled effects on driving decisions. [...] Read more.

Driving Decision-making Mechanism (DDM) is identified as the key technology to ensure the driving safety of autonomous vehicle, which is mainly influenced by vehicle states and road conditions. However, previous studies have seldom considered road conditions and their coupled effects on driving decisions. Therefore, road conditions are introduced into DDM in this paper, and are based on a Support Vector Machine Regression (SVR) model, which is optimized by a weighted hybrid kernel function and a Particle Swarm Optimization (PSO) algorithm, this study designs a DDM for autonomous vehicle. Then, the SVR model with RBF (Radial Basis Function) kernel function and BP (Back Propagation) neural network model are tested to validate the accuracy of the optimized SVR model. The results show that the optimized SVR model has the best performance than other two models. Finally, the effects of road conditions on driving decisions are analyzed quantitatively by comparing the reasoning results of DDM with different reference index combinations, and by the sensitivity analysis of DDM with added road conditions. The results demonstrate the significant improvement in the performance of DDM with added road conditions. It also shows that road conditions have the greatest influence on driving decisions at low traffic density, among those, the most influential is road visibility, then followed by adhesion coefficient, road curvature and road slope, while at high traffic density, they have almost no influence on driving decisions. Full article

(This article belongs to the Special Issue Road Vehicles Surroundings Supervision: On-Board Sensors and Communications)

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15 pages, 5172 KiB

Open AccessArticle

Grasping Claws of Bionic Climbing Robot for Rough Wall Surface: Modeling and Analysis

by Quansheng Jiang¹

and Fengyu Xu^2,*

¹ School of Mechanical Engineering, Suzhou University of Science and Technology, Suzhou 215009, China

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

Appl. Sci. 2018, 8(1), 14; https://doi.org/10.3390/app8010014 - 22 Dec 2017

Cited by 16 | Viewed by 6960

Abstract

Aiming at the inspection of rough stone and concrete wall surfaces, a grasping module of cross-arranged claw is designed. It can attach onto rough wall surfaces by hooking or grasping walls. First, based on the interaction mechanism of hooks and rough wall surfaces, [...] Read more.

Aiming at the inspection of rough stone and concrete wall surfaces, a grasping module of cross-arranged claw is designed. It can attach onto rough wall surfaces by hooking or grasping walls. First, based on the interaction mechanism of hooks and rough wall surfaces, the hook structures in claw tips are developed. Then, the size of the hook tip is calculated and the failure mode is analyzed. The effectiveness and reliability of the mechanism are verified through simulation and finite element analysis. Afterwards, the prototype of the grasping module of claw is established to carry out grasping experiment on vibrating walls. Finally, the experimental results demonstrate that the proposed cross-arranged claw is able to stably grasp static wall surfaces and perform well in grasping vibrating walls, with certain anti-rollover capability. This research lays a foundation for future researches on wall climbing robots with vibrating rough wall surfaces. Full article

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

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17 pages, 6004 KiB

Open AccessArticle

Measurement of Static Stiffness after Motion on a Three-Axis CNC Milling Table

by Tomáš Stejskal¹, Jozef Svetlík^1,*

, Miroslav Dovica², Peter Demeč¹ and Ján Kráľ³

¹ Department of Manufacturing Machinery, Faculty of Mechanical Engineering, The Technical University of Kosice, Letná 9, 04001 Košice, Slovakia

² Department of Biomedical Engineering and Measurement, Faculty of Mechanical Engineering, The Technical University of Kosice, Letná 9, 04001 Košice, Slovakia

³ Prototype and Innovation Centre, Faculty of Mechanical Engineering, The Technical University of Kosice, Letná 9, 04001 Košice, Slovakia

Appl. Sci. 2018, 8(1), 15; https://doi.org/10.3390/app8010015 - 23 Dec 2017

Cited by 16 | Viewed by 6824

Abstract

This paper deals with a modified methodology for measuring the static stiffness of the machine tool. Inspiration to modify the commonly used expanded method of static stiffness measurement resulted from considerably different experimentally measured static stiffness values in the simulated process of load [...] Read more.

This paper deals with a modified methodology for measuring the static stiffness of the machine tool. Inspiration to modify the commonly used expanded method of static stiffness measurement resulted from considerably different experimentally measured static stiffness values in the simulated process of load application under laboratory conditions compared to the standard method. An important takeaway from the measurements is that the measured static stiffness of the table depends greatly on the previous work performed thereon and on the method of the load application onto the table. This modified view of the static stiffness of the machine can have an impact on the increased emphasis on eliminating the phenomena related thereto. It is applicable in engineering practice, in particular in the field of machine tool design, where it will ensure higher machining precision under comparable conditions. In the experiments performed, deformations and displacements were measured with a laser interferometer. Full article

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11 pages, 376 KiB

Open AccessCommunication

Optimal Steady-State Range Prediction Filter for Tracking with LFM Waveforms

by Kenshi Saho

Department of Intelligent Systems Design Engineering, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan

Appl. Sci. 2018, 8(1), 17; https://doi.org/10.3390/app8010017 - 23 Dec 2017

Cited by 2 | Viewed by 3030

Abstract

This communication proposes a gain design method of an

α

-

β

filter with linear frequency-modulated (LFM) waveforms to achieve optimal range prediction (tracking) of maneuvering targets in steady-state. First, a steady-state root-mean-square (RMS) prediction error, called an RMS-index, is analytically derived for [...] Read more.

This communication proposes a gain design method of an

α

-

β

filter with linear frequency-modulated (LFM) waveforms to achieve optimal range prediction (tracking) of maneuvering targets in steady-state. First, a steady-state root-mean-square (RMS) prediction error, called an RMS-index, is analytically derived for a constant-acceleration target. Next, a design method of the optimal gains that minimizes the derived RMS-index is proposed. Numerical analyses demonstrate the effectiveness of the proposed method, as well as producing a performance improvement over the conventional Kalman filter-based design method. Moreover, the theoretical relationship between range tracking performance and a coefficient for range-Doppler coupling of LFM waveforms is clarified. Numerical simulations using the proposed method demonstrate LFM radar tracking of maneuvering targets and prove the method’s effectiveness. Full article

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15 pages, 1146 KiB

Open AccessArticle

A Game Player Expertise Level Classification System Using Electroencephalography (EEG)

by Syed Muhammad Anwar^1,*

, Sanay Muhammad Umar Saeed², Muhammad Majid²

, Saeeda Usman³, Chaudhry Arshad Mehmood⁴ and Wei Liu⁵

¹ Department of Software Engineering, University of Engineering and Technology, Taxila 47050, Pakistan

² Department of Computer Engineering, University of Engineering and Technology, Taxila 47050, Pakistan

³ Department of Electrical Engineering, COMSATS Institute of Information Technology, Sahiwal 54700, Pakistan

⁴ Department of Electrical Engineering, COMSATS Institute of Information Technology, Abbotabad 22060, Pakistan

⁵ Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 4DE, UK

Appl. Sci. 2018, 8(1), 18; https://doi.org/10.3390/app8010018 - 23 Dec 2017

Cited by 28 | Viewed by 8213

Abstract

The success and wider adaptability of smart phones has given a new dimension to the gaming industry. Due to the wide spectrum of video games, the success of a particular game depends on how efficiently it is able to capture the end users’ [...] Read more.

The success and wider adaptability of smart phones has given a new dimension to the gaming industry. Due to the wide spectrum of video games, the success of a particular game depends on how efficiently it is able to capture the end users’ attention. This leads to the need to analyse the cognitive aspects of the end user, that is the game player, during game play. A direct window to see how an end user responds to a stimuli is to look at their brain activity. In this study, electroencephalography (EEG) is used to record human brain activity during game play. A commercially available EEG headset is used for this purpose giving fourteen channels of recorded EEG brain activity. The aim is to classify a player as expert or novice using the brain activity as the player indulges in the game play. Three different machine learning classifiers have been used to train and test the system. Among the classifiers, naive Bayes has outperformed others with an accuracy of

88 %

, when data from all fourteen EEG channels are used. Furthermore, the activity observed on electrodes is statistically analysed and mapped for brain visualizations. The analysis has shown that out of the available fourteen channels, only four channels in the frontal and occipital brain regions show significant activity. Features of these four channels are then used, and the performance parameters of the four-channel classification are compared to the results of the fourteen-channel classification. It has been observed that support vector machine and the naive Bayes give good classification accuracy and processing time, well suited for real-time applications. Full article

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28 pages, 5450 KiB

Open AccessArticle

Theoretical Assessment of DC/DC Power Converters’ Basic Topologies. A Common Static Model

by Juan Manuel Enrique, Antonio Javier Barragán

, Eladio Durán

and José Manuel Andújar^*

Departamento de Ingeniería Electrónica, de Sistemas Informáticos y Automática, University of Huelva, Campus “La Rábida”, 21819 – La Rábida, Huelva Spain

Appl. Sci. 2018, 8(1), 19; https://doi.org/10.3390/app8010019 - 23 Dec 2017

Cited by 11 | Viewed by 3797

Abstract

By the application of well-known circuit analysis techniques, this paper develops an intuitive approach to model the steady state regime of the three DC/DC power converters’ basic topologies (buck, boost and buck-boost). The developed approach can be considered new, realistic, accurate, general and [...] Read more.

By the application of well-known circuit analysis techniques, this paper develops an intuitive approach to model the steady state regime of the three DC/DC power converters’ basic topologies (buck, boost and buck-boost). The developed approach can be considered new, realistic, accurate, general and practical. The approach is new because it is not present in the literature; realistic because it considers the main non-idealities of the different passive and active components that make up the converters; accurate because its theoretical results fit properly to those obtained in actual converters; general because it is valid for the three basic topologies; and practical because its applicability is easy and immediate from the data sheets of the converters’ components (no measurements are needed). The developed model transforms a complex system with strong non-idealities in the form of distributed parameters, in a simple and intuitive scheme of concentrated parameters (just three), which accurately reflects the actual behavior of the three basic converters’ topologies. The characteristic parameters of the model and its main relationships are determined analytically. The quality of the developed approach has been tested in the paper and can be considered excellent. Full article

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24 pages, 11049 KiB

Open AccessArticle

Stability Augmentation of a Grid-Connected Wind Farm by Fuzzy-Logic-Controlled DFIG-Based Wind Turbines

by Md. Rifat Hazari^1,*

, Mohammad Abdul Mannan², S. M. Muyeen³, Atsushi Umemura¹, Rion Takahashi¹ and Junji Tamura¹

¹ Department of Electrical and Electronic Engineering, Kitami Institute of Technology (KIT), 165 Koen-cho, Kitami, Hokkaido 090-8507, Japan

² Department of Electrical and Electronic Engineering, American International University-Bangladesh (AIUB), Ka-66/1, Kuratoli Road, Kuril, Khilkhet, Dhaka 1229, Bangladesh

³ Department of Electrical and Computer Engineering, Curtin University, Perth, WA 6845, Australia

Appl. Sci. 2018, 8(1), 20; https://doi.org/10.3390/app8010020 - 24 Dec 2017

Cited by 31 | Viewed by 7078

Abstract

Wind farm (WF) grid codes require wind generators to have low voltage ride through (LVRT) capability, which means that normal power production should be resumed quickly once the nominal grid voltage has been recovered. However, WFs with fixed-speed wind turbines with squirrel cage [...] Read more.

Wind farm (WF) grid codes require wind generators to have low voltage ride through (LVRT) capability, which means that normal power production should be resumed quickly once the nominal grid voltage has been recovered. However, WFs with fixed-speed wind turbines with squirrel cage induction generators (FSWT-SCIGs) have failed to fulfill the LVRT requirement, which has a significant impact on power system stability. On the other hand, variable-speed wind turbines with doubly fed induction generators (VSWT-DFIGs) have sufficient LVRT augmentation capability and can control the active and reactive power delivered to the grid. However, the DFIG is more expensive than the SCIG due to its AC/DC/AC converter. Therefore, the combined use of SCIGs and DFIGs in a WF could be an effective solution. The design of the rotor-side converter (RSC) controller is crucial because the RSC controller contributes to the system stability. The cascaded control strategy based on four conventional PI controllers is widely used to control the RSC of the DFIG, which can inject only a small amount of reactive power during fault conditions. Therefore, the conventional strategy can stabilize the lower rating of the SCIG. In the present paper, a new control strategy based on fuzzy logic is proposed in the RSC controller of the DFIG in order to enhance the LVRT capability of the SCIG in a WF. The proposed fuzzy logic controller (FLC) is used to control the reactive power delivered to the grid during fault conditions. Moreover, reactive power injection can be increased in the proposed control strategy. Extensive simulations executed in the PSCAD/EMTDC environment for both the proposed and conventional PI controllers of the RSC of the DFIG reveal that the proposed control strategy can stabilize the higher rating of the SCIG. Full article

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

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16 pages, 2114 KiB

Open AccessArticle

TFR: A Novel Approach for Clock Synchronization Fault Recovery in Precision Time Protocol (PTP) Networks

by Alfarooq Omar Alshaikhli

and Jong Myung Rhee^*

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

Appl. Sci. 2018, 8(1), 21; https://doi.org/10.3390/app8010021 - 24 Dec 2017

Cited by 9 | Viewed by 6488

Abstract

Accurate and precise clock synchronization is one of the fundamental requirements for various applications, such as telecommunication systems, measurement and control systems, and smart grid systems. Precision time protocol (PTP) was designed and specified in IEEE 1588 to meet that requirement. PTP provides [...] Read more.

Accurate and precise clock synchronization is one of the fundamental requirements for various applications, such as telecommunication systems, measurement and control systems, and smart grid systems. Precision time protocol (PTP) was designed and specified in IEEE 1588 to meet that requirement. PTP provides a mechanism for synchronizing the clocks in a PTP system to a high degree of accuracy and precision based on exchange synchronization messages through a master–slave hierarchy. The best master clock (BMC) algorithm is currently used to establish the master–slave hierarchy for PTP. However, the BMC algorithm does not provide a fast recovery mechanism in case of master failures. The accuracy and precision of the PTP clocks could be deteriorated by the occurrence of failure in the network (link or node failure). These fault occurrences will affect network performance and reliability, and cause clock time drifting of the PTP nodes. In this paper, we present a novel approach, called timing fault recovery (TFR), to significantly reduce clock time drifting in PTP systems. TFR detects the fault occurrence in the network and recovers it by using a handshake mechanism with a short duration. Therefore, the TFR approach provides clock stability and constancy and increases the reliability and the availability of PTP systems. The performance of TFR has been analyzed and compared to that of the standard PTP. Various simulations were conducted to validate the performance analysis. The results show that, for our sample network, the TFR approach reduces clock drifting by 90% in comparison to the standard PTP, thus providing better clock firmness and synchronization accuracy for PTP clocks. Full article

(This article belongs to the Special Issue Smart Grid and Information Technology)

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8 pages, 1696 KiB

Open AccessCommunication

Facile Synthesis of Two-Dimensional Porous MgCo₂O₄ Nanosheets as Anode for Lithium-Ion Batteries

by Fei Wang¹, Yong Liu^1,*

, Yuanfang Zhao¹, Yue Wang¹, Zhijie Wang², Wanhong Zhang^1,* and Fengzhang Ren^1,*

¹ Collaborative Innovation Center of Nonferrous Metals of Henan Province, the Key Laboratory of Henan Province on Nonferrous Metallic Materials Science and Fabrication Technology, School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China

² Engineering Laboratory for the Next Generation Power and Energy Storage Batteries, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China

Appl. Sci. 2018, 8(1), 22; https://doi.org/10.3390/app8010022 - 24 Dec 2017

Cited by 125 | Viewed by 8595

Abstract

Lithium-ion batteries (LIBs) have drawn considerable attention due to their high energy density and good cycling stability. As a transition-metal oxide, MgCo₂O₄ (MCO) is a promising candidate for energy storage applications because of its low-cost and environmental characteristics. Here, MCO [...] Read more.

Lithium-ion batteries (LIBs) have drawn considerable attention due to their high energy density and good cycling stability. As a transition-metal oxide, MgCo₂O₄ (MCO) is a promising candidate for energy storage applications because of its low-cost and environmental characteristics. Here, MCO porous nanosheets have been successfully synthesized by a microwave-assisted liquid phase method followed by an annealing procedure. As a result, MCO annealed at 600 °C exhibited optimal rate and cycling performances for Lithium storage application. Specifically, when tested as anode materials for Lithium ion batteries, MCO porous nanosheets delivered a high specific capacity of 1173.8 mAh g⁻¹ at 200 mA g⁻¹, and the specific capacity reached 1130.1 mAh g⁻¹ after 100 cycles at 200 mA g⁻¹, achieving 96.3% for the retention rate. The excellent electrochemical performances are mainly attributed to the monolayer porous nanosheet, which provides short transport paths for Li ions and electrons. Results demonstrated that the MCO porous nanosheets are promising electrode materials for Lithium ion batteries applications. Full article

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

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9 pages, 2377 KiB

Open AccessArticle

Estimate of Passive Time Reversal Communication Performance in Shallow Water

by Sunhyo Kim¹

, Su-Uk Son², Hyeonsu Kim¹, Kang-Hoon Choi¹ and Jee Woong Choi^1,*

¹ Department of Marine Science and Convergence Engineering, Hanyang University, Ansan 15588, Gyeonggi, Korea

² Agency for Defense Development, Jinhae, P.O. Box 18, Changwon 51678, Gyeongsangnamdo, Korea

Appl. Sci. 2018, 8(1), 23; https://doi.org/10.3390/app8010023 - 25 Dec 2017

Cited by 7 | Viewed by 4738

Abstract

Time reversal processes have been used to improve communication performance in the severe underwater communication environment characterized by significant multipath channels by reducing inter-symbol interference and increasing signal-to-noise ratio. In general, the performance of the time reversal is strongly related to the behavior [...] Read more.

Time reversal processes have been used to improve communication performance in the severe underwater communication environment characterized by significant multipath channels by reducing inter-symbol interference and increasing signal-to-noise ratio. In general, the performance of the time reversal is strongly related to the behavior of the

q

-function, which is estimated by a sum of the autocorrelation of the channel impulse response for each channel in the receiver array. The

q

-function depends on the complexity of the communication channel, the number of channel elements and their spacing. A

q

-function with a high side-lobe level and a main-lobe width wider than the symbol duration creates a residual ISI (inter-symbol interference), which makes communication difficult even after time reversal is applied. In this paper, we propose a new parameter,

E_{q}

, to describe the performance of time reversal communication.

E_{q}

is an estimate of how much of the

q

-function lies within one symbol duration. The values of

E_{q}

were estimated using communication data acquired at two different sites: one in which the sound speed ratio of sediment to water was less than unity and one where the ratio was higher than unity. Finally, the parameter

E_{q}

was compared to the bit error rate and the output signal-to-noise ratio obtained after the time reversal operation. The results show that these parameters are strongly correlated to the parameter

E_{q}

. Full article

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

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22 pages, 4349 KiB

Open AccessArticle

Message Collision Avoidance Protocols for Detecting Stray Nodes in a Scuba Diving Group Using Ultrasonic Multi-Hop Message Communication

by Shinya Kaido and Kazumasa Takami^*

Information Systems Science Major, Graduate School of Engineering, Soka University, 1-236 Tangi-cho, Hachioji 192-8577, Japan

Appl. Sci. 2018, 8(1), 24; https://doi.org/10.3390/app8010024 - 25 Dec 2017

Cited by 3 | Viewed by 4043

Abstract

Recent years have seen a growing interest in underwater communication and some progress has been made in this area. However, underwater communication is still immature compared with terrestrial communication. A prime reason for this is that the underwater environment is intrinsically not suitable [...] Read more.

Recent years have seen a growing interest in underwater communication and some progress has been made in this area. However, underwater communication is still immature compared with terrestrial communication. A prime reason for this is that the underwater environment is intrinsically not suitable for propagation of electric waves. Instead, ultrasonic waves are mainly used for underwater communication. Since ultrasonic waves cannot provide sufficient communication speed or capacity, they cannot use existing network technologies, which assume use of radio waves. In particular, communication in shallow water is still an uncharted territory. Few communication technologies are employed in environments where people enjoy scuba diving. This paper addresses problems faced by recreational scuba divers. It proposes constructing an ad hoc mesh-shaped network between divers within a group and use ultrasonic waves as transmission media in order to enable the detection of a stray diver. It also proposes a communication protocol in which messages are relayed in multiple hops, and a message collision avoidance method, which is intended to reduce the rate of packet loss caused by message propagation delay. We have implemented the proposed methods in a network simulator, and compared them with an existing communication method that has no message collision avoidance function, in terms of the packet loss rate, the stray driver detection rate, and the rate of the ability to communicate in multiple hops. Full article

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

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21 pages, 4354 KiB

Open AccessArticle

Broken Rotor Bar Fault Detection and Classification Using Wavelet Packet Signature Analysis Based on Fourier Transform and Multi-Layer Perceptron Neural Network

by Sahar Zolfaghari^1,*, Samsul Bahari Mohd Noor¹, Mohammad Rezazadeh Mehrjou^1,2

, Mohammad Hamiruce Marhaban¹ and Norman Mariun^1,2

¹ Department of Electrical and Electronic Engineering, University Putra Malaysia, Serdang 43400, Malaysia

² Centre of Advanced Power and Energy Research (CAPER), University Putra Malaysia, Serdang 43400, Malaysia

Appl. Sci. 2018, 8(1), 25; https://doi.org/10.3390/app8010025 - 25 Dec 2017

Cited by 58 | Viewed by 7288

Abstract

As a result of increasing machines capabilities in modern manufacturing, machines run continuously for hours. Therefore, early fault detection is required to reduce the maintenance expenses and obviate high cost and unscheduled downtimes. Fault diagnosis systems that provide features extraction and patterns classification [...] Read more.

As a result of increasing machines capabilities in modern manufacturing, machines run continuously for hours. Therefore, early fault detection is required to reduce the maintenance expenses and obviate high cost and unscheduled downtimes. Fault diagnosis systems that provide features extraction and patterns classification of the fault are able to detect and classify the failures in machines. The majority of the related works that reported a procedure for detection of rotor bar breakage so far have applied motor current signal analysis using discrete wavelet transform. In this paper, the most appropriate features are extracted from the coefficients of a wavelet packet transform after fast Fourier transform of current signal. The aim of this study is to develop an effective and sensitive method for fault detection under low load conditions. Through combining the strength of both time-scale and frequency domain analysis techniques, a unified wavelet packet signature analysis pinpoints the fault signature in the special fault-oriented frequency bands. The wavelet analysis combined with a feed-forward neural network classifier provides an intelligent methodology for the automatic diagnosis of the fault severity during runtime of the motor. The faults severity is considered as one, two, and three broken rotor bars. The results have confirmed that the proposed method is effective for diagnosing rotor bar breakage fault in an induction motor and classification of fault severity. Full article

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10 pages, 1045 KiB

Open AccessArticle

Enhancement of Chlorophyll a Production from Marine Spirulina maxima by an Optimized Ultrasonic Extraction Process

by Woon Yong Choi¹ and Hyeon Yong Lee^2,*

¹ Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon 200-701, Korea

² Department of Food Science and Engineering, Seowon University, Cheongju 361-742, Korea

Appl. Sci. 2018, 8(1), 26; https://doi.org/10.3390/app8010026 - 25 Dec 2017

Cited by 20 | Viewed by 5905

Abstract

Under the optimal ultrasonification extraction conditions of 20.52 kHz for the frequency, 32.59 °C for the temperature, and 4.91 h for the process time, 17.98 mg/g of chlorophyll a was obtained. It was much higher than 13.81 mg/g from conventional 70% ethanol extraction [...] Read more.

Under the optimal ultrasonification extraction conditions of 20.52 kHz for the frequency, 32.59 °C for the temperature, and 4.91 h for the process time, 17.98 mg/g of chlorophyll a was obtained. It was much higher than 13.81 mg/g from conventional 70% ethanol extraction and even higher than other data from Spirulina. This yield was close to the predicted value of 18.21 mg/g from the second-order polynomial model with a regression coefficient of 0.969. This model showed the greatest significance with the ultrasonic frequency and process time and the least significance with the temperature. The extracts also showed high α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activities as 69.38%, compared to 58.25% for the extracts from the 70% ethanol extraction. It was first shown that the optimal extraction was effective at enhancing the neuroprotective activities possibly due to the synergistic effects of higher amounts of chlorophyll a and other bioactive substances in the extract, revealing a 90% protection of the growth of mouse neuronal cells and a great reduction in Reactive Oxygen Species (ROS) production. Full article

(This article belongs to the Collection Ultrasound in Extraction Processing)

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17 pages, 1519 KiB

Open AccessArticle

Noninvasive Grading of Glioma Tumor Using Magnetic Resonance Imaging with Convolutional Neural Networks

by Saed Khawaldeh^1,2,3,*,†

, Usama Pervaiz^1,2,†, Azhar Rafiq⁴ and Rami S. Alkhawaldeh⁵

¹ Erasmus+ Joint Master Program in Medical Imaging and Applications, University of Girona, 17004 Girona, Spain

² Erasmus+ Joint Master Program in Medical Imaging and Applications, University of Burgundy, 21000 Dijon, France

³ Department of Electrical Engineering and Automation, Aalto University, 02150 Espoo, Finland

⁴ Department of Surgery, Virginia Commonwealth University, Richmond, VA 23298, USA

⁵ Department of Computer Information Systems, The University of Jordan, Aqaba 77110, Jordan

^† These authors contributed equally to this work and they both share the first authorship.

Appl. Sci. 2018, 8(1), 27; https://doi.org/10.3390/app8010027 - 25 Dec 2017

Cited by 172 | Viewed by 8506

Abstract

In recent years, Convolutional Neural Networks (ConvNets) have rapidly emerged as a widespread machine learning technique in a number of applications especially in the area of medical image classification and segmentation. In this paper, we propose a novel approach that uses ConvNet for [...] Read more.

In recent years, Convolutional Neural Networks (ConvNets) have rapidly emerged as a widespread machine learning technique in a number of applications especially in the area of medical image classification and segmentation. In this paper, we propose a novel approach that uses ConvNet for classifying brain medical images into healthy and unhealthy brain images. The unhealthy images of brain tumors are categorized also into low grades and high grades. In particular, we use the modified version of the Alex Krizhevsky network (AlexNet) deep learning architecture on magnetic resonance images as a potential tumor classification technique. The classification is performed on the whole image where the labels in the training set are at the image level rather than the pixel level. The results showed a reasonable performance in characterizing the brain medical images with an accuracy of 91.16%. Full article

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23 pages, 8571 KiB

Open AccessArticle

Comparative Study on KNN and SVM Based Weather Classification Models for Day Ahead Short Term Solar PV Power Forecasting

by Fei Wang^1,2,*

, Zhao Zhen¹, Bo Wang³ and Zengqiang Mi¹

¹ State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University), Baoding 071003, China

² Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

³ State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems, China Electric Power Research Institute, Beijing 100192, China

Appl. Sci. 2018, 8(1), 28; https://doi.org/10.3390/app8010028 - 25 Dec 2017

Cited by 172 | Viewed by 12113

Abstract

Accurate solar photovoltaic (PV) power forecasting is an essential tool for mitigating the negative effects caused by the uncertainty of PV output power in systems with high penetration levels of solar PV generation. Weather classification based modeling is an effective way to increase [...] Read more.

Accurate solar photovoltaic (PV) power forecasting is an essential tool for mitigating the negative effects caused by the uncertainty of PV output power in systems with high penetration levels of solar PV generation. Weather classification based modeling is an effective way to increase the accuracy of day-ahead short-term (DAST) solar PV power forecasting because PV output power is strongly dependent on the specific weather conditions in a given time period. However, the accuracy of daily weather classification relies on both the applied classifiers and the training data. This paper aims to reveal how these two factors impact the classification performance and to delineate the relation between classification accuracy and sample dataset scale. Two commonly used classification methods, K-nearest neighbors (KNN) and support vector machines (SVM) are applied to classify the daily local weather types for DAST solar PV power forecasting using the operation data from a grid-connected PV plant in Hohhot, Inner Mongolia, China. We assessed the performance of SVM and KNN approaches, and then investigated the influences of sample scale, the number of categories, and the data distribution in different categories on the daily weather classification results. The simulation results illustrate that SVM performs well with small sample scale, while KNN is more sensitive to the length of the training dataset and can achieve higher accuracy than SVM with sufficient samples. Full article

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

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28 pages, 706 KiB

Open AccessArticle

Robust Control Examples Applied to a Wind Turbine Simulated Model

by Silvio Simani^1,*

and Paolo Castaldi²

¹ Dipartimento di Ingegneria, Università degli Studi di Ferrara, Via Saragat 1E, 44122 Ferrara, Italy

² Dipartimento di Ingegneria dell’Energia Elettrica e dell’Informazione “Guglielmo Marconi”—DEI, Alma Mater Studiorum Università di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy

Appl. Sci. 2018, 8(1), 29; https://doi.org/10.3390/app8010029 - 26 Dec 2017

Cited by 13 | Viewed by 4517

Abstract

Wind turbine plants are complex dynamic and uncertain processes driven by stochastic inputs and disturbances, as well as different loads represented by gyroscopic, centrifugal and gravitational forces. Moreover, as their aerodynamic models are nonlinear, both modeling and control become challenging problems. On the [...] Read more.

Wind turbine plants are complex dynamic and uncertain processes driven by stochastic inputs and disturbances, as well as different loads represented by gyroscopic, centrifugal and gravitational forces. Moreover, as their aerodynamic models are nonlinear, both modeling and control become challenging problems. On the one hand, high-fidelity simulators should contain different parameters and variables in order to accurately describe the main dynamic system behavior. Therefore, the development of modeling and control for wind turbine systems should consider these complexity aspects. On the other hand, these control solutions have to include the main wind turbine dynamic characteristics without becoming too complicated. The main point of this paper is thus to provide two practical examples of the development of robust control strategies when applied to a simulated wind turbine plant. Extended simulations with the wind turbine benchmark model and the Monte Carlo tool represent the instruments for assessing the robustness and reliability aspects of the developed control methodologies when the model-reality mismatch and measurement errors are also considered. Advantages and drawbacks of these regulation methods are also highlighted with respect to different control strategies via proper performance metrics. Full article

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

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13 pages, 1833 KiB

Open AccessArticle

Efficient Disruption of Escherichia coli for Plasmid DNA Recovery in a Bead Mill

by Adriana Padilla-Zamudio¹, J. Armando Lucero-Acuña¹

, Patricia Guerrero-Germán^1,*

, Jaime Ortega-López² and Armando Tejeda-Mansir³

¹ Department of Chemical Engineering and Metallurgy, University of Sonora, Hermosillo 83000, Mexico

² Department of Biotechnology and Bioengineering, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City 07360, Mexico

³ Department of Scientific and Technological Research, University of Sonora, Hermosillo 83000, Mexico

Appl. Sci. 2018, 8(1), 30; https://doi.org/10.3390/app8010030 - 26 Dec 2017

Cited by 4 | Viewed by 6239

Abstract

The release kinetics of pDNA in a bead mill was studied. Samples taken during the process were analyzed to determine total pDNA (pDNA(t)) and supercoiled pDNA (pDNA(sc)) concentration. In order to identify important variables of the process and to develop an empirical model [...] Read more.

The release kinetics of pDNA in a bead mill was studied. Samples taken during the process were analyzed to determine total pDNA (pDNA(t)) and supercoiled pDNA (pDNA(sc)) concentration. In order to identify important variables of the process and to develop an empirical model for optimal pDNA(t) and pDNA(sc) release, a two level 2³ factorial design was used with variables: mill frequency, cell concentration, and bead size. The results were analyzed by response surface methodology. The optimized conditions for pDNA(t) yield 13.26 mg/g dcw (93.41% recovery), with a mill frequency of 30 Hz, a bead size of 0.10–0.25 mm, and a cell concentration of 20 g wcw/L. However, the optimized conditions for pDNA(sc) yield 7.65 mg/g dcw (92.05% recovery), with a mill frequency of 15 Hz, a bead size of 0.10–0.25 mm, and a cell concentration of 10 g wcw/L. Cell disruption in a bead mill was proved efficient for the release of pDNA(t) and pDNA(sc) compared to the alkaline treatment. The results obtained suggest a compromise between pDNA(sc) purity and recuperation in the process development. Full article

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

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Graphical abstract

16 pages, 1811 KiB

Open AccessArticle

Germinal Center Optimization Applied to Neural Inverse Optimal Control for an All-Terrain Tracked Robot

by Carlos Villaseñor¹

, Jorge D. Rios¹, Nancy Arana-Daniel^1,*, Alma Y. Alanis¹

, Carlos Lopez-Franco¹ and Esteban A. Hernandez-Vargas²

¹ Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. Marcelino García Barragán 1421, 44430 Guadalajara, Mexico

² Frankfurt Institute For Advanced Studies, Ruth-Moufang-Straße 1, 60438 Frankfurt am Main, Germany

Appl. Sci. 2018, 8(1), 31; https://doi.org/10.3390/app8010031 - 27 Dec 2017

Cited by 14 | Viewed by 6488

Abstract

Nowadays, there are several meta-heuristics algorithms which offer solutions for multi-variate optimization problems. These algorithms use a population of candidate solutions which explore the search space, where the leadership plays a big role in the exploration-exploitation equilibrium. In this work, we propose to [...] Read more.

Nowadays, there are several meta-heuristics algorithms which offer solutions for multi-variate optimization problems. These algorithms use a population of candidate solutions which explore the search space, where the leadership plays a big role in the exploration-exploitation equilibrium. In this work, we propose to use a Germinal Center Optimization algorithm (GCO) which implements temporal leadership through modeling a non-uniform competitive-based distribution for particle selection. GCO is used to find an optimal set of parameters for a neural inverse optimal control applied to all-terrain tracked robot. In the Neural Inverse Optimal Control (NIOC) scheme, a neural identifier, based on Recurrent High Orden Neural Network (RHONN) trained with an extended kalman filter algorithm, is used to obtain a model of the system, then, a control law is design using such model with the inverse optimal control approach. The RHONN identifier is developed without knowledge of the plant model or its parameters, on the other hand, the inverse optimal control is designed for tracking velocity references. Applicability of the proposed scheme is illustrated using simulations results as well as real-time experimental results with an all-terrain tracked robot. Full article

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

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13 pages, 479 KiB

Open AccessArticle

A Fusion Link Prediction Method Based on Limit Theorem

by Yiteng Wu^*, Hongtao Yu^*, Ruiyang Huang, Yingle Li

and Senjie Lin

National Digital Switching System Engineering and Technological R&D Center, Zhengzhou 450002, China

Appl. Sci. 2018, 8(1), 32; https://doi.org/10.3390/app8010032 - 28 Dec 2017

Cited by 3 | Viewed by 3534

Abstract

The theoretical limit of link prediction is a fundamental problem in this field. Taking the network structure as object to research this problem is the mainstream method. This paper proposes a new viewpoint that link prediction methods can be divided into single or [...] Read more.

The theoretical limit of link prediction is a fundamental problem in this field. Taking the network structure as object to research this problem is the mainstream method. This paper proposes a new viewpoint that link prediction methods can be divided into single or combination methods, based on the way they derive the similarity matrix, and investigates whether there a theoretical limit exists for combination methods. We propose and prove necessary and sufficient conditions for the combination method to reach the theoretical limit. The limit theorem reveals the essence of combination method that is to estimate probability density functions of existing links and nonexistent links. Based on limit theorem, a new combination method, theoretical limit fusion (TLF) method, is proposed. Simulations and experiments on real networks demonstrated that TLF method can achieve higher prediction accuracy. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)

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7 pages, 1123 KiB

Open AccessFeature PaperArticle

Metallic, 3D-Printed, K-Band-Stepped, Double-Ridged Square Horn Antennas

by Bing Zhang^1,2, Yong-Xin Guo^1,*, Hucheng Sun³ and Yanjie Wu⁴

¹ Department of Electrical and Computer Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576, Singapore

² College of Electronics and Information Engineering, Sichuan University, Chengdu 610065, China

³ School of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China

⁴ School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China

Appl. Sci. 2018, 8(1), 33; https://doi.org/10.3390/app8010033 - 27 Dec 2017

Cited by 22 | Viewed by 8168

Abstract

This paper presents K-band-stepped, double-ridged square horn antennas fabricated by metallic 3D printing technology in copper (85% copper and 15% stannum) and aluminum alloy (89.5% aluminum, 10% silicon, and 0.5% magnesium). Compared with the popular dielectric 3D-printed horn antenna, the metallic counterpart features [...] Read more.

This paper presents K-band-stepped, double-ridged square horn antennas fabricated by metallic 3D printing technology in copper (85% copper and 15% stannum) and aluminum alloy (89.5% aluminum, 10% silicon, and 0.5% magnesium). Compared with the popular dielectric 3D-printed horn antenna, the metallic counterpart features better mechanical robustness in terms of material. Moreover, the metallic horns are printed in one piece in one run, different from the dielectric horns that are printed in split pieces and electroplated, they simplify the process and thus result in reduced cost. The agreement between the simulation and measurement results verified the antenna’s performance. Both the 3D-printed copper and aluminum alloy antenna have an impedance bandwidth across the K-band, with a maximum gain of 13.23 dBi @ 25 GHz and 13.5 dBi @ 24 GHz, respectively. The metallic, 3D-printed horn antennas are preferable alternatives to replace traditionally-fabricated antennas. Full article

(This article belongs to the Special Issue 3D Printed Antennas)

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20 pages, 6621 KiB

Open AccessArticle

Forced Response Prediction of Turbine Blades with Flexible Dampers: The Impact of Engineering Modelling Choices

by Chiara Gastaldi^1,*

, Alfredo Fantetti²

and Teresa M. Berruti¹

¹ Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

² Imperial College London, South Kensington Campus, London SW7 2AZ, UK

Appl. Sci. 2018, 8(1), 34; https://doi.org/10.3390/app8010034 - 27 Dec 2017

Cited by 30 | Viewed by 5923

Abstract

This paper focuses on flexible friction dampers (or “strips”) mounted on the underside of adjacent turbine blade platforms for sealing and damping purposes. A key parameter to ensure a robust and trustworthy design is the correct prediction of the maximum frequency shift induced [...] Read more.

This paper focuses on flexible friction dampers (or “strips”) mounted on the underside of adjacent turbine blade platforms for sealing and damping purposes. A key parameter to ensure a robust and trustworthy design is the correct prediction of the maximum frequency shift induced by the strip damper coupling adjacent blades. While this topic has been extensively addressed on rigid friction dampers, both experimentally and numerically, no such investigation is available as far as flexible dampers are concerned. This paper builds on the authors’ prior experience with rigid dampers to investigate the peculiarities and challenges of a robust dynamic model of blade-strips systems. The starting point is a numerical tool implementing state-of-the-art techniques for the efficient solution of the nonlinear equations, e.g., multi-harmonic balance method with coupled static solution and state-of-the-art contact elements. The full step-by-step modelling process is here retraced and upgraded to take into account the damper flexibility: for each step, key modelling choices (e.g., mesh size, master nodes selection, contact parameters) which may affect the predicted response are addressed. The outcome is a series of guidelines which will help the designer assign numerical predictions the proper level of trust and outline a much-needed experimental campaign. Full article

(This article belongs to the Section Mechanical Engineering)

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17 pages, 4206 KiB

Open AccessArticle

A Real-Time Sound Field Rendering Processor

by Tan Yiyu^1,2,*

, Yasushi Inoguchi², Makoto Otani³, Yukio Iwaya⁴ and Takao Tsuchiya⁵

¹ RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047, Japan

² Research Center for Advanced Computing Infrastructure, Japan Advanced Institute of Science & Technology, Nomi, Ishikawa 923-1292, Japan

³ Department of Architecture and Architectural Engineering, Kyoto University, Kyoto 615-8540, Japan

⁴ Department of Electrical Engineering and Information Technology, Tohoku Gakuin University, Sendai, Miyagi 980-8511, Japan

⁵ Faculty of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan

Appl. Sci. 2018, 8(1), 35; https://doi.org/10.3390/app8010035 - 28 Dec 2017

Cited by 5 | Viewed by 4670

Abstract

Real-time sound field renderings are computationally intensive and memory-intensive. Traditional rendering systems based on computer simulations suffer from memory bandwidth and arithmetic units. The computation is time-consuming, and the sample rate of the output sound is low because of the long computation time [...] Read more.

Real-time sound field renderings are computationally intensive and memory-intensive. Traditional rendering systems based on computer simulations suffer from memory bandwidth and arithmetic units. The computation is time-consuming, and the sample rate of the output sound is low because of the long computation time at each time step. In this work, a processor with a hybrid architecture is proposed to speed up computation and improve the sample rate of the output sound, and an interface is developed for system scalability through simply cascading many chips to enlarge the simulated area. To render a three-minute Beethoven wave sound in a small shoe-box room with dimensions of 1.28 m × 1.28 m × 0.64 m, the field programming gate array (FPGA)-based prototype machine with the proposed architecture carries out the sound rendering at run-time while the software simulation with the OpenMP parallelization takes about 12.70 min on a personal computer (PC) with 32 GB random access memory (RAM) and an Intel i7-6800K six-core processor running at 3.4 GHz. The throughput in the software simulation is about 194 M grids/s while it is 51.2 G grids/s in the prototype machine even if the clock frequency of the prototype machine is much lower than that of the PC. The rendering processor with a processing element (PE) and interfaces consumes about 238,515 gates after fabricated by the 0.18 µm processing technology from the ROHM semiconductor Co., Ltd. (Kyoto Japan), and the power consumption is about 143.8 mW. Full article

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

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17 pages, 3897 KiB

Open AccessArticle

PHD and CPHD Algorithms Based on a Novel Detection Probability Applied in an Active Sonar Tracking System

by Xiao Chen^*

, Yaan Li^*

, Yuxing Li

and Jing Yu

School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

Appl. Sci. 2018, 8(1), 36; https://doi.org/10.3390/app8010036 - 27 Dec 2017

Cited by 25 | Viewed by 4372

Abstract

Underwater multi-targets tracking has always been a difficult problem in active sonar tracking systems. In order to estimate the parameters of time-varying multi-targets moving in underwater environments, based on the Bayesian filtering framework, the Random Finite Set (RFS) is introduced to multi-targets tracking, [...] Read more.

Underwater multi-targets tracking has always been a difficult problem in active sonar tracking systems. In order to estimate the parameters of time-varying multi-targets moving in underwater environments, based on the Bayesian filtering framework, the Random Finite Set (RFS) is introduced to multi-targets tracking, which not only avoids the problem of data association in multi-targets tracking, but also realizes the estimation of the target number and their states simultaneously. Usually, the conventional Probability Hypothesis Density (PHD) and Cardinalized Probability Hypothesis Density (CPHD) algorithms assume that the detection probability is known as a priori, which is not suitable in many applications. Some methods have been proposed to estimate the detection probability, but most assume that it is constant both in time and surveillance region. In this paper, we model the detection probability through the active sonar equation. When fixed the false detection probability, we can get the analytic expression for the detection probability, which is related to target position. In addition, this novel detection probability is used in PHD and CPHD algorithms and applied to underwater active sonar tracking systems. Also, we use the adaptive ellipse gate strategy to reduce the computational load in PHD and CPHD algorithms. Under the linear Gaussian assumption, the proposed detection probability is illustrated in both Gaussian Mixture Probability Hypothesis Density (GM-PHD) and Gaussian Mixture Cardinalized Probability Hypothesis Density (GM-CPHD), respectively. Simulation results show that the proposed Pd-GM-PHD and Pd-GM-CPHD algorithms are more realistic and accuratein underwater active sonar tracking systems. Full article

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

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15 pages, 3232 KiB

Open AccessArticle

Parameter Determination of a Minimal Model for Brake Squeal

by Zhigang Chu^1,2,*, Fei Zheng², Lei Liang³, Hui Yan³ and Runcheng Kang³

¹ State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China

² College of Automotive Engineering, Chongqing University, Chongqing 400044, China

³ National Automobile Quality Supervision Test Center, Xiangyang 441004, China

Appl. Sci. 2018, 8(1), 37; https://doi.org/10.3390/app8010037 - 1 Jan 2018

Cited by 12 | Viewed by 3772

Abstract

In the research into the mechanism of brake squeal, minimal models with two degrees of freedom (DoFs) are widely used. Compared with the finite element method, the minimal model is more concise and efficient, making it easier to analyze the effect of parameters. [...] Read more.

In the research into the mechanism of brake squeal, minimal models with two degrees of freedom (DoFs) are widely used. Compared with the finite element method, the minimal model is more concise and efficient, making it easier to analyze the effect of parameters. However, how to accurately determine its kinetic parameters is rarely reported in the literature. In this paper, firstly, the finite element model of a disc brake is established and the complex eigenvalue analysis (CEA) is carried out to obtain unstable modes of the brake. Then, an unstable mode with seven nodal diameters predicted by CEA is taken as an example to establish the 2-DoF model. In order that the natural frequency, Hopf bifurcation point and real parts of eigenvalues of the minimal model coincide with that of the unstable mode with seven nodal diameters, the response surface method (RSM) is applied to determine the kinetic parameters of the minimal model. Finally, the parameter-optimized minimal model is achieved. Furthermore, the negative slope of friction-velocity characteristic is introduced into the model, and transient analysis (TA) is used to study the effect of braking velocity on stability of the brake system. The results show that the brake system becomes unstable when braking velocity is lower than a critical value. The lower the velocity is, the worse the stability appears, and the higher the brake squeal propensity is. Full article

(This article belongs to the Section Acoustics and Vibrations)

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13 pages, 774 KiB

Open AccessArticle

A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform

by Xing Zhang^1,*, Kang Song^1,2,3, Chunguo Li^1,* and Luxi Yang¹

¹ School of Information Science and Engineering, Southeast University, Nanjing 210096, China

² School of Electronic and Information Engineering, Qingdao University, Qingdao 266071, China

³ School of Automation and Electrical Engineering, Qingdao University, Qingdao 266071, China

Appl. Sci. 2018, 8(1), 38; https://doi.org/10.3390/app8010038 - 1 Jan 2018

Cited by 4 | Viewed by 3534

Abstract

In this paper, the estimation of doubly spread underwater acoustic (UWA) channels is investigated. The UWA channels are characterized by severe delay spread and significant Doppler effects, and can be well modeled as a multi-scale multi-lag (MSML) channel. Furthermore, exploiting the sparsity of [...] Read more.

In this paper, the estimation of doubly spread underwater acoustic (UWA) channels is investigated. The UWA channels are characterized by severe delay spread and significant Doppler effects, and can be well modeled as a multi-scale multi-lag (MSML) channel. Furthermore, exploiting the sparsity of UWA channels, MSML channel estimation can be transformed into the estimation of parameter sets (amplitude, Doppler scale factor, time delay). Based on this, the orthogonal matching pursuit (OMP) algorithm has been widely used. However, the estimation accuracy of OMP depends on the size of the dictionary, which is related with both delay spread and Doppler spread. Thus it requires high computational complexity. This paper proposes a new method, called wavelet transform (WT) based algorithm, for the UWA channel estimation. Different from OMP algorithm which needs to search in both time domain and Doppler domain, WT-based algorithm only needs to search in time domain by using the Doppler invariant characteristic of hyperbolic frequency modulation (HFM) signal. The performance of the proposed algorithm is evaluated by computer simulations based on BELLHOP. The simulation results show that WT-based algorithm performs slightly better than OMP algorithm in low signal to noise ratio (SNR) while can greatly reduce computational complexity. Full article

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

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7 pages, 2103 KiB

Open AccessFeature PaperArticle

Slot Waveguide Enhanced Bloch Surface Waves

by Matthieu Roussey

Institute of Photonics, Department of Physics and Mathematics, University of Eastern Finland, P.O. BOX 111, 80101 Joensuu, Finland

Appl. Sci. 2018, 8(1), 39; https://doi.org/10.3390/app8010039 - 30 Dec 2017

Cited by 3 | Viewed by 4784

Abstract

The paper presents a novel concept for the on-chip integration of a multilayer platform sustaining Bloch surface waves further enhanced by the so-called slot waveguide effect. Through simulations, we demonstrate that a carefully designed polymer waveguide arrangement coated with a subwavelength dielectric multilayer [...] Read more.

The paper presents a novel concept for the on-chip integration of a multilayer platform sustaining Bloch surface waves further enhanced by the so-called slot waveguide effect. Through simulations, we demonstrate that a carefully designed polymer waveguide arrangement coated with a subwavelength dielectric multilayer can be efficiently used to first excite a Bloch surface wave at the surface of the multilayer and second to enhance this wave and allow longer propagation of the surface mode by constructive superimposition of two evanescent tails inside a narrow gap. Full article

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

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9 pages, 2960 KiB

Open AccessArticle

An Efficient Numerical Approach for Field Infrared Smoke Transmittance Based on Grayscale Images

by Runze Tang, Tonglai Zhang, Xuebin Wei and Zunning Zhou^*

State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

Appl. Sci. 2018, 8(1), 40; https://doi.org/10.3390/app8010040 - 29 Dec 2017

Cited by 9 | Viewed by 4003

Abstract

Infrared smoke screen has been playing an important role in electro-optical countermeasures on the battlefield. Smoke transmittance is one of the most important parameters which can evaluate the obscuration performance of smoke. In this paper, an efficient numerical approach for field infrared smoke [...] Read more.

Infrared smoke screen has been playing an important role in electro-optical countermeasures on the battlefield. Smoke transmittance is one of the most important parameters which can evaluate the obscuration performance of smoke. In this paper, an efficient numerical approach for field infrared smoke transmittance based on grayscale images is presented. Firstly, a field trial experimental setup is introduced. Then a grayscale smoke transmittance mathematical model is deduced and built. In addition, an image processing algorithm is used to extract the gray values of certain pixel points from grayscale images, and the positions of the selected points are discussed. Lastly, a field trial sample calculation is included to illustrate the procedure of the proposed method. The results prove to be of enough precision for engineering applications, and the method has greatly simplified the field trial process, thus improving efficiency. Full article

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

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15 pages, 8380 KiB

Open AccessArticle

Research on the Transportation of Low-Strength Composites Sheets

by Renhe Ji^1,2, Baohua Chang^1,2

, Li Wang^1,2, Wenzhu Wang^1,2 and Dong Du^1,2,*

¹ Department of Mechanical Engineering, Tsinghua University, 30 Shuangqing Rd., Beijing 100084, China

² Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, China

Appl. Sci. 2018, 8(1), 41; https://doi.org/10.3390/app8010041 - 31 Dec 2017

Cited by 2 | Viewed by 2992

Abstract

The novel non-combustible sandwich panel is extremely fragile in manufacturing and cannot be tensioned between rolls. Previous studies on the roll-to-roll system, which mainly focused on the high-tension situations and little described the low-strength materials, are insufficient. To explore the transportation of low-strength [...] Read more.

The novel non-combustible sandwich panel is extremely fragile in manufacturing and cannot be tensioned between rolls. Previous studies on the roll-to-roll system, which mainly focused on the high-tension situations and little described the low-strength materials, are insufficient. To explore the transportation of low-strength materials, we study the tension distribution of continuous moving flexible one-dimensional materials on a steady-state track. First, we propose a numerical method to calculate the steady-state track of low-strength sheet between rolls considering the gravity, as well as size and position of rolls. Then we obtain the optimum sag at different size and position of rolls. We find out that there is a lower limit of the sheet’s strength-density ratio (the Minimum Specific Strength) for a specific set of size and position of rolls. Finally, we establish a method to calculate the lower limit approximately for engineering use. Our method can be generalized in manufacturing other low-strength flexible thin-sheet materials as well. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 842 KiB

Open AccessArticle

Finite Difference/Collocation Method for a Generalized Time-Fractional KdV Equation

by Wen Cao^†, Yufeng Xu^† and Zhoushun Zheng^*,†

¹ School of Mathematics and Statistics, Central South University, 932 Lushan South Road, Changsha 410083, China

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(1), 42; https://doi.org/10.3390/app8010042 - 1 Jan 2018

Cited by 18 | Viewed by 4920

Abstract

In this paper, we studied the numerical solution of a time-fractional Korteweg–de Vries (KdV) equation with new generalized fractional derivative proposed recently. The fractional derivative employed in this paper was defined in Caputo sense and contained a scale function and a weight function. [...] Read more.

In this paper, we studied the numerical solution of a time-fractional Korteweg–de Vries (KdV) equation with new generalized fractional derivative proposed recently. The fractional derivative employed in this paper was defined in Caputo sense and contained a scale function and a weight function. A finite difference/collocation scheme based on Jacobi–Gauss–Lobatto (JGL) nodes was applied to solve this equation and the corresponding stability was analyzed theoretically, while the convergence was verified numerically. Furthermore, we investigated the behavior of solution of the generalized KdV equation depending on its parameter

δ

, scale function

z (t)

in fractional derivative. We found that the full discrete scheme was effective to obtain a numerical solution of the new KdV equation with different conditions. The wave number

δ

in front of the third order space derivative term played a significant role in splitting a soliton wave into multiple small pieces. Full article

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16 pages, 3905 KiB

Open AccessArticle

Virtual Reality-Wireless Local Area Network: Wireless Connection-Oriented Virtual Reality Architecture for Next-Generation Virtual Reality Devices

by Jinsoo Ahn¹

, Young Yong Kim¹ and Ronny Yongho Kim^2,*

¹ School of Electrical & Electronics Engineering, Yonsei University, Seoul 03722, Korea

² Department of Railroad Electrical and Electronic Engineering, Korea National University of Transportation, Gyeonggi 16106, Korea

Appl. Sci. 2018, 8(1), 43; https://doi.org/10.3390/app8010043 - 3 Jan 2018

Cited by 10 | Viewed by 8246

Abstract

In order to enhance the user experience of virtual reality (VR) devices, multi-user VR environments and wireless connections should be considered for next-generation VR devices. Wireless local area network (WLAN)-based wireless communication devices are popular consumer devices with high throughput and low cost [...] Read more.

In order to enhance the user experience of virtual reality (VR) devices, multi-user VR environments and wireless connections should be considered for next-generation VR devices. Wireless local area network (WLAN)-based wireless communication devices are popular consumer devices with high throughput and low cost using unlicensed bands. However, the use of WLANs may cause delays in packet transmission, owing to their distributed nature while accessing the channel. In this paper, we carefully examine the feasibility of wireless VR over WLANs, and we propose an efficient wireless multiuser VR communication architecture, as well as a communication scheme for VR. Because the proposed architecture in this paper utilizes multiple WLAN standards, based on the characteristics of each set of VR traffic, the proposed scheme enables the efficient delivery of massive uplink data generated by multiple VR devices, and provides an adequate video frame rate and control frame rate for high-quality VR services. We perform extensive simulations to corroborate the outstanding performance of the proposed scheme. Full article

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

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16 pages, 3107 KiB

Open AccessArticle

Upper-Body Control and Mechanism of Humanoids to Compensate for Angular Momentum in the Yaw Direction Based on Human Running

by Takuya Otani^1,*,†

, Kenji Hashimoto^2,3,†, Shunsuke Miyamae^4,†, Hiroki Ueta^4,†, Akira Natsuhara^4,†, Masanori Sakaguchi^5,†, Yasuo Kawakami^6,†, Hum-Ok Lim^3,7,† and Atsuo Takanishi^1,3,†

¹ Department of Modern Mechanical Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan

² Waseda Institute for Advanced Study, Waseda University, No. 41-304, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan

³ Humanoid Robotics Institute (HRI), Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan

⁴ Graduate School of Science and Engineering, Waseda University, No. 41-304, 17 Kikui-cho, Shinjuku-ku, Tokyo 162-0044, Japan

⁵ ASICS Corporation, Institute of Sport Science, 6-2-1 Takatsukadai, Nishi-ku, Kobe, 651-2271, Japan

⁶ Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa-shi, Tokyo 359-1192, Japan

⁷ Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(1), 44; https://doi.org/10.3390/app8010044 - 3 Jan 2018

Cited by 17 | Viewed by 8203

Abstract

Many extant studies proposed various stabilizing control methods for humanoids during the stance phase while hopping and running. Although these methods contribute to stability during hopping and running, humanoid robots do not swing their legs rapidly during the flight phase to prevent rotation [...] Read more.

Many extant studies proposed various stabilizing control methods for humanoids during the stance phase while hopping and running. Although these methods contribute to stability during hopping and running, humanoid robots do not swing their legs rapidly during the flight phase to prevent rotation in the yaw direction. Humans utilize their torsos and arms when running to compensate for the angular momentum in the yaw direction generated by leg movement during the flight phase. In this study, we developed an angular momentum control method based on human motion for a humanoid upper body. The method involves calculation of the angular momentum generated by the movement of the humanoid legs and calculation of the torso and arm motions required to compensate for the angular momentum of the legs in the yaw direction. We also developed a humanoid upper-body mechanism having human link length and mass properties, using carbon-fiber-reinforced plastic and a symmetric structure for generating large angular momentum. The humanoid robot developed in this study could generate almost the same angular momentum as that of a human. Furthermore, when suspended in midair, the humanoid robot achieved angular momentum compensation in the yaw direction. Full article

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

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21 pages, 4794 KiB

Open AccessArticle

Application of the Wave Propagation Approach to Sandwich Structures: Vibro-Acoustic Properties of Aluminum Honeycomb Materials

by Edoardo Alessio Piana^1,*

, Candida Petrogalli¹, Diego Paderno¹ and Ulf Carlsson²

¹ Department of Mechanical and Industrial Engineering, University of Brescia, 25128 Brescia, Italy

² Department of Aeronautical and Vehicle Engineering, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden

Appl. Sci. 2018, 8(1), 45; https://doi.org/10.3390/app8010045 - 1 Jan 2018

Cited by 25 | Viewed by 6138

Abstract

Sandwich structures are manufactured using multiple combinations of materials for core and laminates. The real performances are influenced by variability in the composing layers and even by the uncertainties introduced while bonding them together. Therefore, experimental tests are usually the preferred way to [...] Read more.

Sandwich structures are manufactured using multiple combinations of materials for core and laminates. The real performances are influenced by variability in the composing layers and even by the uncertainties introduced while bonding them together. Therefore, experimental tests are usually the preferred way to assess the most important parameters required to develop and to characterize the product, the main downsides lying in their cost and time consumption. This work explores a practical application of the wave propagation approach by means of a case study, in which some significant properties of an aluminum honeycomb panel are obtained starting from simple vibro-acoustic tests carried out on beam specimens. After determining the frequency-dependent bending stiffness function, the sound transmission loss is predicted and compared with the experimental results obtained in sound transmission suites. The same vibro-acoustic tests are used to estimate the core shear modulus. Finally, a parametric study is proposed to show how this technique can be effectively used in the early design stage, when producing physical samples is often impossible due to time and money constraints. The method proved to be a reliable and powerful tool in all the tested applications, providing good results with limited computational effort. Full article

(This article belongs to the Section Acoustics and Vibrations)

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13 pages, 5948 KiB

Open AccessFeature PaperArticle

Impact of a Porous Si-Ca-P Monophasic Ceramic on Variation of Osteogenesis-Related Gene Expression of Adult Human Mesenchymal Stem Cells

by Rabadan-Ros Ruben^1,*, Revilla-Nuin Beatriz², Mazón Patricia³

, Aznar-Cervantes Salvador⁴, Ros-Tarraga Patricia¹, De Aza Piedad N.⁵

and Meseguer-Olmo Luis¹

¹ Tissue Regeneration and Repair Group: Orthobiology, Biomaterials and Tissue Engineering, UCAM-San Antonio Catholic University of Murcia, Guadalupe, 30107 Murcia, Spain

² Genomic Unit, Biomedical Research Institute of Murcia (IMIB-Arrixaca-UMU), University Clinical Hospital “Virgen de la Arrixaca”, University of Murcia, El Palmar, 30120 Murcia, Spain

³ Department of Materials, Optics and Electronic Technology, Miguel Hernández University, Avda. Universidad s/n, Elche, 03202 Alicante, Spain

⁴ Department of Biotechnology, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), La Alberca, 30150 Murcia, Spain

⁵ Institute of Bioengineering, Miguel Hernández University, Avda. Universidad s/n, Elche, 03202 Alicante, Spain

Appl. Sci. 2018, 8(1), 46; https://doi.org/10.3390/app8010046 - 1 Jan 2018

Cited by 7 | Viewed by 3799

Abstract

This work evaluates in vitro the influence of a new biocompatible porous Si-Ca-P monophasic (7CaO·P₂O₅·2SiO₂) ceramic on the cellular metabolic activity, morphology and osteogenic differentiation of adult human mesenchymal stem cells (ahMSCs) cultured in basal [...] Read more.

This work evaluates in vitro the influence of a new biocompatible porous Si-Ca-P monophasic (7CaO·P₂O₅·2SiO₂) ceramic on the cellular metabolic activity, morphology and osteogenic differentiation of adult human mesenchymal stem cells (ahMSCs) cultured in basal growth medium and under osteogenic inductive medium. Alamar Blue Assay and FESEM were carried out in order to monitor the cell proliferation and the shape of the cells growing on the Si-Ca-P monophasic ceramic during the study period. The osteogenic differentiation of ahMSCs was investigated by means of immunofluorescent staining (osteocalcin, osteopontin, heparan sulphate and collagen type I expression), quantitative reverse transcription polymerase chain reaction (qRT-PCR) (integrin-binding sialoprotein, osteocalcin, alkaline phosphatase, osteopontin, osteonectin, runt-related transcription factor 2 and collagen type I) and expression of surface markers (CD73, CD90 and CD105). We could check osteogenic differentiation in ahMSCs growing under the influence of Si-Ca-P monophasic ceramics itself, but especially when growth medium was replaced by osteogenic medium in the culture conditions. These results allowed us to conclude that the new Si-Ca-P monophasic scaffold greatly enhanced ahMSCs proliferation and osteogenic differentiation; therefore, it may be considered to be employed as a new bone graft substitute or scaffold for bone tissue engineering. Full article

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

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16 pages, 3326 KiB

Open AccessArticle

Swarming Behavior Emerging from the Uptake–Kinetics Feedback Control in a Plant-Root-Inspired Robot

by Emanuela Del Dottore^*

, Alessio Mondini, Ali Sadeghi and Barbara Mazzolai^*

Center for Micro-Biorobotics, Istituto Italiano di Tecnologia, 56025 Pontedera, Italy

Appl. Sci. 2018, 8(1), 47; https://doi.org/10.3390/app8010047 - 1 Jan 2018

Cited by 11 | Viewed by 5861

Abstract

This paper presents a plant root behavior-based approach to defining the control architecture of a plant-root-inspired robot, which is composed of three root-agents for nutrient uptake and one shoot-agent for nutrient redistribution. By taking inspiration and extracting key principles from the uptake of [...] Read more.

This paper presents a plant root behavior-based approach to defining the control architecture of a plant-root-inspired robot, which is composed of three root-agents for nutrient uptake and one shoot-agent for nutrient redistribution. By taking inspiration and extracting key principles from the uptake of nutrient, movements and communication strategies adopted by plant roots, we developed an uptake–kinetics feedback control for the robotic roots. Exploiting the proposed control, each root is able to regulate the growth direction, towards the nutrients that are most needed, and to adjust nutrient uptake, by decreasing the absorption rate of the most plentiful one. Results from computer simulations and implementation of the proposed control on the robotic platform, Plantoid, demonstrate an emergent swarming behavior aimed at optimizing the internal equilibrium among nutrients through the self-organization of the roots. Plant wellness is improved by dynamically adjusting nutrients priorities only according to local information without the need of a centralized unit delegated for wellness monitoring and task allocation among the agents. Thus, the root-agents can ideally and autonomously grow at the best speed, exploiting nutrient distribution and improving performance, in terms of exploration capabilities and exploitation of resources, with respect to the tropism-inspired control previously proposed by the same authors. Full article

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

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11 pages, 2372 KiB

Open AccessArticle

Methodology of Classifying the Causes of Occupational Accidents Involving Construction Scaffolding Using Pareto-Lorenz Analysis

by Anna Hoła¹, Marek Sawicki² and Mariusz Szóstak^2,*

¹ Department of Building Physics and Computer Aided Design, Faculty of Civil Engineering, Wroclaw University of Science and Technology, 50-370 Wrocław, Poland

² Department of Construction Technology and Management, Faculty of Civil Engineering, Wroclaw University of Science and Technology, 50-370 Wrocław, Poland

Appl. Sci. 2018, 8(1), 48; https://doi.org/10.3390/app8010048 - 1 Jan 2018

Cited by 60 | Viewed by 5666

Abstract

This article presents the developed methodology of classifying and evaluating the causes of accidents involving construction scaffolding. This methodology allows the causes of accidents to be identified, classified into generic groups, and also allows the importance of individual causes in their generic groups [...] Read more.

This article presents the developed methodology of classifying and evaluating the causes of accidents involving construction scaffolding. This methodology allows the causes of accidents to be identified, classified into generic groups, and also allows the importance of individual causes in their generic groups to be assessed. For the classification of causes, the Technical–Organizational–Human (TOH) method was used. Its assumption is the division of causes into technical (T), organizational (O), and human (H) ones. Pareto-Lorenz analysis and ABC classification were used to identify the most important causes. The developed methodology was used to analyze and assess the causes of accidents that involve construction scaffolding using the data of accidents that occurred in Poland as an example. The use of the proposed methodology in different countries will enable the results of the conducted studies and analysis to be compared, and conclusions that would be of a great importance in accident prevention to be drawn. Full article

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12 pages, 1331 KiB

Open AccessArticle

Linear Approximation Signal Detection Scheme in MIMO-OFDM Systems

by Jae-Hyun Ro, Jong-Kwang Kim, Young-Hwan You and Hyoung-Kyu Song^*

uT Communication Research Institute, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 05006, Korea

Appl. Sci. 2018, 8(1), 49; https://doi.org/10.3390/app8010049 - 1 Jan 2018

Cited by 5 | Viewed by 4181

Abstract

In this paper, a linearly approximate signal detection scheme is proposed in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The huge MIMO-OFDM system, which uses many transmit antennas and high order modulation, requires a detection scheme at the receiver with very [...] Read more.

In this paper, a linearly approximate signal detection scheme is proposed in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The huge MIMO-OFDM system, which uses many transmit antennas and high order modulation, requires a detection scheme at the receiver with very low complexity for practical implementation. In the proposed detection scheme, one

N \times N

MIMO-OFDM system is divided into

N / 2

2 \times 2

MIMO-OFDM systems for linear increase of complexity. After the partial zero-forcing (ZF), decision feedback equalizer (DFE) and QR decomposition-M algorithm (QRD-M) are applied to each

2 \times 2

MIMO-OFDM system. Despite nonlinear detection schemes, the overall complexity of the proposed algorithm increases almost linearly because the DFE and the QRD-M are applied to

2 \times 2

MIMO-OFDM systems. Also, the value of M in the QRD-M is fixed according to position of the center point in constellation for efficient signal detection. In simulation results, the proposed detection scheme has higher error performance and lower complexity than the conventional ZF. Also, the proposed detection scheme has very lower complexity than the conventional DFE, with slight loss of error performance. Full article

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

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19 pages, 11939 KiB

Open AccessArticle

IR Reflectography and Active Thermography on Artworks: The Added Value of the 1.5–3 µm Band

by Jeroen Peeters^1,*

, Gunther Steenackers¹

, Stefano Sfarra^3,†

, Stijn Legrand², Clemente Ibarra-Castanedo⁴

, Koen Janssens²

and Geert Van der Snickt²

¹ Electro Mechanic Department, University of Antwerp, Op3Mech Research Group, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

² Chemistry Department, University of Antwerp, AXES Research Groep, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

³ Las.E.R. Laboratory, Department of Industrial and Information Engineering and Economics (DIIIE), University of L’Aquila, Piazzale E. Pontieri 1, Loc. Monteluco di Roio, Roio Poggio, 67100 L’Aquila, Italy

⁴ Electrical and Computer Engineering Department, Computer Vision and Systems Laboratory, Laval University, 1065 av de la Medecine, QC G1V 0A6, Canada

^† Additional affiliation: Thermal Control Methods Lab No. 34, Tomsk Polytechnic University, Lenin Av., 30, Tomsk 634050, Russia.

Appl. Sci. 2018, 8(1), 50; https://doi.org/10.3390/app8010050 - 1 Jan 2018

Cited by 26 | Viewed by 6685

Abstract

Infrared Radiation (IR) artwork inspection is typically performed through active thermography and reflectography with different setups and cameras. While Infrared Radiation Reflectography (IRR) is an established technique in the museum field, exploiting mainly the IR-A (0.7–1.4 µm) band to probe for hidden layers [...] Read more.

Infrared Radiation (IR) artwork inspection is typically performed through active thermography and reflectography with different setups and cameras. While Infrared Radiation Reflectography (IRR) is an established technique in the museum field, exploiting mainly the IR-A (0.7–1.4 µm) band to probe for hidden layers and modifications within the paint stratigraphy system, active thermography operating in the IR-C range (3–5

μ

m) is less frequently employed with the aim to visualize structural defects and features deeper inside the build-up. In this work, we assess to which extent the less investigated IR-B band (1.5–3

μ

m) can combine the information obtained from both setups. The application of IR-B systems is relatively rare as there are only a limited amount of commercial systems available due to the technical complexity of the lens coating. This is mainly added as a so-called broadband option on regular Mid-wave infrared radiation (MWIR) (IR-C’/3–5

μ

m) cameras to increase sensitivity for high temperature applications in industry. In particular, four objects were studied in both reflectographic and thermographic mode in the IR-B spectral range and their results benchmarked with IR-A and IR-C images. For multispectral application, a single benchmark is made with macroscopic reflection mode Fourier transform infrared (MA-rFTIR) results. IR-B proved valuable for visualisation of underdrawings, pencil marks, canvas fibres and wooden grain structures and potential pathways for additional applications such as pigment identification in multispectral mode or characterization of the support (panels, canvas) are indicated. Full article

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

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21 pages, 3865 KiB

Open AccessArticle

Omnidirectional Jump of a Legged Robot Based on the Behavior Mechanism of a Jumping Spider

by Yaguang Zhu^1,2,*

, Long Chen¹, Qiong Liu¹, Rui Qin¹ and Bo Jin²

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

² State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310028, China

Appl. Sci. 2018, 8(1), 51; https://doi.org/10.3390/app8010051 - 1 Jan 2018

Cited by 17 | Viewed by 10927

Abstract

To find a common approach for the development of an efficient system that is able to achieve an omnidirectional jump, a jumping kinematic of a legged robot is proposed based on the behavior mechanism of a jumping spider. To satisfy the diversity of [...] Read more.

To find a common approach for the development of an efficient system that is able to achieve an omnidirectional jump, a jumping kinematic of a legged robot is proposed based on the behavior mechanism of a jumping spider. To satisfy the diversity of motion forms in robot jumping, a kind of 4 degrees of freedom (4DoFs) mechanical leg is designed. Taking the change of joint angle as inspiration by observing the behavior of the jumping spider during the acceleration phase, a redundant constraint to solve the kinematic is obtained. A series of experiments on three types of jumping—vertical jumping, sideways jumping and forward jumping—is carried out, while the initial attitude and path planning of the robot is studied. The proposed jumping kinematic is verified on the legged robot experimental platform, and the added redundant constraint could be verified as being reasonable. The results indicate that the jumping robot could maintain stability and complete the planned task of jumping, and the proposed spider-inspired jumping strategy could easily achieve an omnidirectional jump, thus enabling the robot to avoid obstacles. Full article

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

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18 pages, 15413 KiB

Open AccessArticle

Thermal Stability and Tuning of Thermoelectric Properties of Ag_1−xSb_1+xTe_2+x (0 ≤ x ≤ 0.4) Alloys

by Paweł Wyżga^1,2,3,*, Igor Veremchuk^3,*, Ulrich Burkhardt³, Paul Simon³, Yuri Grin³ and Krzysztof T. Wojciechowski²

¹ Institut für Experimentelle Physik, TU Bergakademie Freiberg, Leipziger Str. 23, 09599 Freiberg, Germany

² Thermoelectric Research Laboratory, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, A. Mickiewicza Av. 30, 30-059 Krakow, Poland

³ Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany

Appl. Sci. 2018, 8(1), 52; https://doi.org/10.3390/app8010052 - 4 Jan 2018

Cited by 10 | Viewed by 4554

Abstract

Introduction of nonstoichiometry to AgSbTe₂-based materials is considered to be an effective way to tune thermoelectric properties similarly to extrinsic doping. To prove this postulate, a systematic physicochemical study of the Ag_1−xSb_1+xTe_2+x alloys [...] Read more.

Introduction of nonstoichiometry to AgSbTe₂-based materials is considered to be an effective way to tune thermoelectric properties similarly to extrinsic doping. To prove this postulate, a systematic physicochemical study of the Ag_1−xSb_1+xTe_2+x alloys (0 ≤ x ≤ 0.4) was performed. In order to investigate the influence of the cooling rate after synthesis on phase composition and thermoelectric performance, slowly cooled and quenched Ag_1−xSb_1+xTe_2+x alloys (x = 0; 0.1; 0.17; 0.19; 0.3; 0.4) were prepared. Single-phase material composed of the β phase (NaCl structure type) was obtained for the quenched x = 0.19 sample only. The other alloys must be regarded as multi-phase materials. The cooling rate affects the formation of the phases in the Ag-Sb-Te system and influences mainly electronic properties, carrier mobility and carrier concentration. The extremely low lattice thermal conductivity is an effect of the mosaic nanostructure. The maximal value of the figure of merit ZT_max = 1.2 is observed at 610 K for the slowly cooled multi-phase sample Ag_0.9Sb_1.1Te_2.1. Thermoelectric properties are repeatedly reproducible up to 490 K. Full article

(This article belongs to the Special Issue Recent Progress in the Development of Thermoelectric Materials)

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14 pages, 7809 KiB

Open AccessArticle

Correlation between the Golden Ratio and Nanowire Transistor Performance

by Talib Al-Ameri^1,2

¹ School of Engineering, University of Glasgow, Glasgow G12 8LT, UK

² Electrical Engineering Department, College of Engineering, Al-Mustansiriyah University, Baghdad 10052, Iraq

Appl. Sci. 2018, 8(1), 54; https://doi.org/10.3390/app8010054 - 2 Jan 2018

Cited by 2 | Viewed by 5030

Abstract

An observation was made in this research regarding the fact that the signatures of isotropic charge distributions in silicon nanowire transistors (NWT) displayed identical characteristics to the golden ratio (Phi). In turn, a simulation was conducted regarding ultra-scaled n-type Si (NWT) with respect [...] Read more.

An observation was made in this research regarding the fact that the signatures of isotropic charge distributions in silicon nanowire transistors (NWT) displayed identical characteristics to the golden ratio (Phi). In turn, a simulation was conducted regarding ultra-scaled n-type Si (NWT) with respect to the 5-nm complementary metal-oxide-semiconductor (CMOS) application. The results reveal that the amount of mobile charge in the channel and intrinsic speed of the device are determined by the device geometry and could also be correlated to the golden ratio (Phi). This paper highlights the issue that the optimization of NWT geometry could reduce the impact of the main sources of statistical variability on the Figure of Merit (FoM) of devices. In the context of industrial early successes in fabricating vertically stacked NWT, ensemble Monte Carlo (MC) simulations with quantum correction are used to accurately predict the drive current. This occurs alongside a consideration of the degree to which the carrier transport in the vertically stacked lateral NWTs are complex. Full article

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

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Graphical abstract

18 pages, 8195 KiB

Open AccessFeature PaperArticle

A Bio-Inspired Control Strategy for Locomotion of a Quadruped Robot

by Yinquan Zeng¹, Junmin Li^1,*, Simon X. Yang^2,*

and Erwei Ren¹

¹ School of Mechanical Engineering, Xihua University, Chengdu 610039, China

² Advanced Robotics and Intelligent Systems Laboratory, School of Engineering, University of Guelph, Guelph, ON N1G 2W1, Canada

Appl. Sci. 2018, 8(1), 56; https://doi.org/10.3390/app8010056 - 2 Jan 2018

Cited by 23 | Viewed by 9302

Abstract

In order to effectively plan the robot gaits and foot workspace trajectory (WT) synchronously, a novel biologically inspired control strategy for the locomotion of a quadruped robot based on central pattern generator—neural network—workspace trajectory (CPG-NN-WT) is presented in this paper. Firstly, a foot [...] Read more.

In order to effectively plan the robot gaits and foot workspace trajectory (WT) synchronously, a novel biologically inspired control strategy for the locomotion of a quadruped robot based on central pattern generator—neural network—workspace trajectory (CPG-NN-WT) is presented in this paper. Firstly, a foot WT is planned via the Denavit-Hartenberg (D-H) notation and the inverse kinematics, which has the advantages of low mechanical shock, smooth movement, and sleek trajectory. Then, an improved central pattern generator (CPG) based on Hopf oscillators is proposed in this paper for smooth gait planning. Finally, a neural network is designed and trained to convert the CPG output to the preplanned WT, which can make full use of the advantages of the CPG-based method in gait planning and the WT-based method in foot trajectory planning simultaneously. Furthermore, virtual prototype simulations and experiments with a real quadruped robot are presented to validate the effectiveness of the proposed control strategy. The results show that the gait of the quadruped robot can be controlled easily and effectively by the CPG with its internal parameters; meanwhile, the foot trajectory meets the preplanned WT well. Full article

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

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Graphical abstract

18 pages, 6507 KiB

Open AccessArticle

Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System

by Yeongsu Bak¹, June-Seok Lee² and Kyo-Beum Lee^1,*

¹ Department of Electrical and Computer Engineering, Ajou University, 206, World cup-ro, Yeongtong-gu, Suwon 16499, Korea

² Railroad Safety Research Division, Korea Railroad Research Institute, 176, Cheoldo Bangmulgwan-ro, Uiwang 16105, Korea

Appl. Sci. 2018, 8(1), 57; https://doi.org/10.3390/app8010057 - 2 Jan 2018

Cited by 40 | Viewed by 8172

Abstract

This paper presents a low-voltage ride-through (LVRT) control strategy for grid-connected energy storage systems (ESSs). In the past, researchers have investigated the LVRT control strategies to apply them to wind power generation (WPG) and solar energy generation (SEG) systems. Regardless of the energy [...] Read more.

This paper presents a low-voltage ride-through (LVRT) control strategy for grid-connected energy storage systems (ESSs). In the past, researchers have investigated the LVRT control strategies to apply them to wind power generation (WPG) and solar energy generation (SEG) systems. Regardless of the energy source, the main purpose of the LVRT control strategies is to inject reactive power into the grid depending on the grid-code regulations using the grid-side inverter; the proposed LVRT control strategy for grid-connected ESSs also has the same purpose. However, unlike the WPG and SEG systems having unidirectional power flow, grid-connected ESSs have a bidirectional power flow. Therefore, the charging condition of the grid-connected ESSs should be considered for the LVRT control strategy. The proposed LVRT control strategy for grid-connected ESSs determines the injection quantity of the active and reactive currents, and the strategy depends on the voltage drop ratio of the three-phase grid. Additionally, in this paper, we analyzed the variations of the point of common coupling (PCC) voltage depending on the phase of the reactive current during the charging and discharging conditions. The validity of the proposed LVRT control strategy is verified and the variations of the PCC voltage of the grid-connected ESS are analyzed by simulation and experimental results. Full article

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

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10 pages, 1548 KiB

Open AccessArticle

Study on the Structure of an Efficient Receiver for Covert Underwater Communication Using Direct Sequence Spread Spectrum

by Chang-Uk Baek¹, Ji-Won Jung^1,* and Dae-Won Do²

¹ Department of Radio Communication Engineering, Korea Maritime and Ocean University, 727 Taejong-ro, Yeongdo-gu, Busan 49112, Korea

² Agency for Defense Development, P.O. Box 18, Jinhae-gu, Changwon-si, Gyeongsangnam-do 51678, Korea

Appl. Sci. 2018, 8(1), 58; https://doi.org/10.3390/app8010058 - 3 Jan 2018

Cited by 10 | Viewed by 4804

Abstract

This paper proposes an underwater communication receive model based on the spread spectrum technique in order to provide the characteristic of a low probability of interception. To do this, turbo equalization techniques employing Bahl-Cocke-Jelinek-Raviv (BCJR) decoding to improve performance through repetition are applied [...] Read more.

This paper proposes an underwater communication receive model based on the spread spectrum technique in order to provide the characteristic of a low probability of interception. To do this, turbo equalization techniques employing Bahl-Cocke-Jelinek-Raviv (BCJR) decoding to improve performance through repetition are applied to offer excellent performance even at a low signal to noise ratio (SNR) of transmitted signals due to the spread spectrum technique. A turbo equalization model based on RAKE which increase signal power by summing the received signal through the multipath is proposed to compensate distorted data due to multipath channel and the performance improvements were proven by applying the threshold and weighted coefficient in the RAKE receiver model. The model was applied to covert underwater communication in a multi-sensor environment, and the efficiency of the proposed method was proven through underwater experiments. Full article

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

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20 pages, 382 KiB

Open AccessArticle

Automatic Speech-to-Background Ratio Selection to Maintain Speech Intelligibility in Broadcasts Using an Objective Intelligibility Metric

by Yan Tang^*

, Bruno M. Fazenda

and Trevor J. Cox

Acoustics Research Centre, University of Salford, Salford M5 4WT, UK

Appl. Sci. 2018, 8(1), 59; https://doi.org/10.3390/app8010059 - 3 Jan 2018

Cited by 15 | Viewed by 4668

Abstract

While mixing, sound producers and audio professionals empirically set the speech-to- background ratio (SBR) based on rules of thumb and their own perception of sounds. There is no guarantee that the speech content will be intelligible for the general population consuming content over [...] Read more.

While mixing, sound producers and audio professionals empirically set the speech-to- background ratio (SBR) based on rules of thumb and their own perception of sounds. There is no guarantee that the speech content will be intelligible for the general population consuming content over a wide variety of devices, however. In this study, an approach to automatically determine the appropriate SBR for a scene using an objective intelligibility metric is introduced. The model-estimated SBR needed for a preset minimum intelligibility level was compared to the listener-preferred SBR for a range of background sounds. It was found that an extra gain added to the model estimation is needed even for listeners with normal hearing. This gain is needed so an audio scene can be auditioned with comfort and without compromising the sound effects contributed by the background. When the background introduces little informational masking, the extra gain holds almost constant across the various background sounds. However, a larger gain is required for a background that induces informational masking, such as competing speech. The results from a final subjective rating study show that the model-estimated SBR with the additional gain, yields the same listening experience as the SBR preferred by listeners. Full article

(This article belongs to the Section Acoustics and Vibrations)

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15 pages, 7705 KiB

Open AccessArticle

Broadband Electromagnetic Dipole Resonance by the Coupling Effect of Multiple Dielectric Nanocylinders

by Bo Fang¹, Xufeng Jing^2,*, Qiufeng Ye², Jinhui Cai¹ and Pengwei Zhou²

¹ College of Metrology & Measurement Engineering, China Jiliang University, Hangzhou 310018, China

² Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018, China

Appl. Sci. 2018, 8(1), 60; https://doi.org/10.3390/app8010060 - 3 Jan 2018

Cited by 4 | Viewed by 5551

Abstract

Broadband resonant scattering in a visible region that can be obtained by coupled multiple silicon nanocylinders. For a single high refractive index silicon nanocylinder, the electric dipole and magnetic dipole resonances can be observed. By constructing a silicon nanocylinder dimer, the interaction between [...] Read more.

Broadband resonant scattering in a visible region that can be obtained by coupled multiple silicon nanocylinders. For a single high refractive index silicon nanocylinder, the electric dipole and magnetic dipole resonances can be observed. By constructing a silicon nanocylinder dimer, the interaction between the particles plays an important role in broadband scattering. Interestingly, due to magnetic-magnetic dipole interaction, a splitting phenomenon of magnetic resonance mode is revealed. A new magnetic resonant mode emerges at a longer wavelength in dimer and trimer by changing the diameter of one nanocylinder in dimer or trimer, and the gap size between nanocylinders. The scattering bandwidth can further increase with the effect of substrate, which is attributed to the extension of resonant mode into substrate. The broadband optical response can be revealed by the calculated scattering resonant spectra and the spatial electromagnetic field distributions. Furthermore, the transmission of periodic nanocylinder structure, including single nanocylinder and dimer, is demonstrated. By decreasing the gap between nanocylinders in dimer for periodic array structure, a new electric resonant mode occurs. These results can provide a guideline to realize broadband resonant optical elements. Full article

(This article belongs to the Special Issue Sub-wavelength Optics)

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17 pages, 3513 KiB

Open AccessArticle

Passive Sonar Target Detection Using Statistical Classifier and Adaptive Threshold

by Hamed Komari Alaie^* and Hassan Farsi

Department of Electrical and Computer Engineering, University of Birjand, Birjand 97175, Iran

Appl. Sci. 2018, 8(1), 61; https://doi.org/10.3390/app8010061 - 3 Jan 2018

Cited by 23 | Viewed by 8830

Abstract

This paper presents the results of an experimental investigation about target detecting with passive sonar in Persian Gulf. Detecting propagated sounds in the water is one of the basic challenges of the researchers in sonar field. This challenge will be complex in shallow [...] Read more.

This paper presents the results of an experimental investigation about target detecting with passive sonar in Persian Gulf. Detecting propagated sounds in the water is one of the basic challenges of the researchers in sonar field. This challenge will be complex in shallow water (like Persian Gulf) and noise less vessels. Generally, in passive sonar, the targets are detected by sonar equation (with constant threshold) that increases the detection error in shallow water. The purpose of this study is proposed a new method for detecting targets in passive sonars using adaptive threshold. In this method, target signal (sound) is processed in time and frequency domain. For classifying, Bayesian classification is used and posterior distribution is estimated by Maximum Likelihood Estimation algorithm. Finally, target was detected by combining the detection points in both domains using Least Mean Square (LMS) adaptive filter. Results of this paper has showed that the proposed method has improved true detection rate by about 24% when compared other the best detection method. Full article

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9 pages, 3824 KiB

Open AccessFeature PaperArticle

Bloch Surface Wave Photonic Device Fabricated by Femtosecond Laser Polymerisation Technique

by Ksenia A. Abrashitova^1,2, Dmitry N. Gulkin¹, Kirill R. Safronov¹, Natalia G. Kokareva¹, Ilya M. Antropov¹, Vladimir O. Bessonov^1,3,* and Andrey A. Fedyanin¹

¹ Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia

² Institute of Physics, Mathematics and Informational Technologies, Center for Functionalized Magnetic Materials (FunMagMa), Immanuel Kant Baltic Federal University, Kaliningrad 236041, Russia

³ Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119071, Russia

Appl. Sci. 2018, 8(1), 63; https://doi.org/10.3390/app8010063 - 4 Jan 2018

Cited by 18 | Viewed by 6371

Abstract

We applied femtosecond laser polymerisation technique to fabricate a novel Bloch surface wave integrated photonic device with a compact coupling scheme. The device consisted of a waveguide, coupling and decoupling gratings and focusing and defocusing triangles. We manufactured an array of devices with [...] Read more.

We applied femtosecond laser polymerisation technique to fabricate a novel Bloch surface wave integrated photonic device with a compact coupling scheme. The device consisted of a waveguide, coupling and decoupling gratings and focusing and defocusing triangles. We manufactured an array of devices with varying geometrical parameters of waveguide. Excitation and propagation of Bloch surface wave waveguide modes were studied by direct and back focal plane imaging. The obtained results prove that the maskless and flexible femtosecond laser polymerisation technique may be applied for fabrication of Bloch-surface-wave based integrated photonics. Full article

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

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14 pages, 9683 KiB

Open AccessArticle

Plasmonics in the Ultraviolet with Aluminum, Gallium, Magnesium and Rhodium

by Yael Gutiérrez, Rodrigo Alcaraz de la Osa, Dolores Ortiz, José María Saiz, Francisco González and Fernando Moreno^*

Department of Applied Physics, University of Cantabria, Avda. Los Castros, s/n, 39005 Santander, Spain

Appl. Sci. 2018, 8(1), 64; https://doi.org/10.3390/app8010064 - 4 Jan 2018

Cited by 89 | Viewed by 9576

Abstract

Ultraviolet plasmonics (UV) has become an active topic of research due to the new challenges arising in fields such as biosensing, chemistry or spectroscopy. Recent studies have pointed out aluminum, gallium, magnesium and rhodium as promising candidates for plasmonics in the UV range. [...] Read more.

Ultraviolet plasmonics (UV) has become an active topic of research due to the new challenges arising in fields such as biosensing, chemistry or spectroscopy. Recent studies have pointed out aluminum, gallium, magnesium and rhodium as promising candidates for plasmonics in the UV range. Aluminum and magnesium present a high oxidation tendency that has a critical effect in their plasmonic performance. Nevertheless, gallium and rhodium have drawn a lot of attention because of their low tendency of oxidation and, at the same time, good plasmonic response in the UV and excellent photocatalytic properties. Here, we present a short overview of the current state of UV plasmonics with the latest findings in the plasmonic response and applications of aluminum, gallium, magnesium and rhodium nanoparticles. Full article

(This article belongs to the Special Issue Light Matter Interaction at Nanoscale: What Matters Most)

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13 pages, 4438 KiB

Open AccessArticle

Standing Wave Field Distribution in Graded-Index Antireflection Coatings

by Hongxiang Deng^1,2,*, Xianyue Dong¹, Huanhuan Gao¹, Xiaodong Yuan¹, Wanguo Zheng¹ and Xiaotao Zu^2,*

¹ Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China

² School of Physical Electronic, University of Electronic Science and Technology of China, Chengdu 610054, China

Appl. Sci. 2018, 8(1), 65; https://doi.org/10.3390/app8010065 - 4 Jan 2018

Cited by 3 | Viewed by 3635

Abstract

Standing wave field distributions in three classic types of graded-index antireflection coatings are studied. These graded-index antireflection coatings are designed at wavelengths from 200 nm to 1200 nm, which is the working wavelength range of high energy laser system for inertial-fusion research. The [...] Read more.

Standing wave field distributions in three classic types of graded-index antireflection coatings are studied. These graded-index antireflection coatings are designed at wavelengths from 200 nm to 1200 nm, which is the working wavelength range of high energy laser system for inertial-fusion research. The standing wave field distributions in these coatings are obtained by the numerical calculation of electromagnetic wave equation. We find that standing wave field distributions in these three graded-index anti-reflection coatings are quite different. For the coating with linear index distribution, intensity of standing wave field decreases periodically from surface to substrate with narrow oscillation range and the period is proportional to the incident wavelength. For the coating with exponential index distribution, intensity of standing wave field decreases periodically from surface to substrate with large oscillation range and the period is also proportional to the incident wavelength. Finally, for the coating with polynomial index, intensity of standing wave field is quickly falling down from surface to substrate without an obvious oscillation. We find that the intensity of standing wave field in the interface between coating and substrate for linear index, exponential index and polynomial index are about 0.7, 0.9 and 0.7, respectively. Our results indicate that the distributions of standing wave field in linear index coating and polynomial index coating are better than that in exponential index coating for the application in high energy laser system. Moreover, we find that the transmittance of linear index coating and polynomial index coating are also better than exponential index coating at the designed wavelength range. Present simulation results are useful for the design and application of graded-index antireflection coating in high energy laser system. Full article

(This article belongs to the Special Issue Radiation Effects of Materials with Laser, Ion Beam and Rays)

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41 pages, 2128 KiB

Open AccessArticle

Challenges of the Usual Graphical Methods Used to Characterize Phase Change Materials by Differential Scanning Calorimetry

by Stéphane Gibout

, Erwin Franquet, Didier Haillot, Jean-Pierre Bédécarrats and Jean-Pierre Dumas^*

University Pau & Pays de l’Adour, Laboratoire de Thermique, Énergétique et Procédés - IPRA, EA 1932, Bât. d’Alembert, rue Jules Ferry, BP 7511, F-64075 Pau, France

Appl. Sci. 2018, 8(1), 66; https://doi.org/10.3390/app8010066 - 9 Jan 2018

Cited by 28 | Viewed by 6788

Abstract

Modeling the thermal behavior of a plant or devices using Phase Change Materials (PCM) requires to know their thermophysical properties. The Differential Scanning Calorimetry (DSC) is a technic largely used to investigate them. However, under the pretext to experiment with small samples, some [...] Read more.

Modeling the thermal behavior of a plant or devices using Phase Change Materials (PCM) requires to know their thermophysical properties. The Differential Scanning Calorimetry (DSC) is a technic largely used to investigate them. However, under the pretext to experiment with small samples, some authors consider the DSC curves as directly representing the properties of the materials without realizing that this interpretation is very often incompatible with the thermodynamics laws: as an example, although a pure substance melts at a fixed temperature

T_{F}

, it is proposed a melting through a temperature range higher than

T_{F}

and depending on the experiments (heating rates, sample masses...), for solutions the suggested characteristic temperatures are incompatible with the phase diagram, and also a hysteresis phenomenon is invented... In this paper, we demonstrate by a model coupling thermodynamics and conduction heat transfers, that the DSC curves are exactly compatible with the thermodynamics of phase changes (melting at fixed temperature for pure substances, in conformity with phase diagrams for solutions...). The cases of pure substances, saline solutions, substances with impurities or solid solutions are detailed. We indicate which information can, however, be given by the curves. We also propose a more sophisticated method by inverse calculations to determine the specific enthalpy whose all the thermodynamical properties can be deduced. Finally, we give some indications to understand and use the results indicating supercooling. Full article

(This article belongs to the Special Issue Phase Change Material (PCM) 2017)

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21 pages, 9930 KiB

Open AccessFeature PaperArticle

Multi-Agent System for Demand Prediction and Trip Visualization in Bike Sharing Systems

by Álvaro Lozano^1,*

, Juan F. De Paz¹, Gabriel Villarrubia González¹

, Daniel H. De La Iglesia¹

and Javier Bajo²

¹ Faculty of Science, University of Salamanca, Plaza de la Merced s/n, 37002 Salamanca, Spain

² Department of Artificial Intelligence, Polytechnic University of Madrid, Campus Montegancedo s/n, Boadilla del Monte, 28660 Madrid, Spain

Appl. Sci. 2018, 8(1), 67; https://doi.org/10.3390/app8010067 - 5 Jan 2018

Cited by 33 | Viewed by 10570

Abstract

This paper proposes a multi agent system that provides visualization and prediction tools for bike sharing systems (BSS). The presented multi-agent system includes an agent that performs data collection and cleaning processes, it is also capable of creating demand forecasting models for each [...] Read more.

This paper proposes a multi agent system that provides visualization and prediction tools for bike sharing systems (BSS). The presented multi-agent system includes an agent that performs data collection and cleaning processes, it is also capable of creating demand forecasting models for each bicycle station. Moreover, the architecture offers API (Application Programming Interface) services and provides a web application for visualization and forecasting. This work aims to make the system generic enough for it to be able to integrate data from different types of bike sharing systems. Thus, in future studies it will be possible to employ the proposed system in different types of bike sharing systems. This article contains a literature review, a section on the process of developing the system and the built-in prediction models. Moreover, a case study which validates the proposed system by implementing it in a public bicycle sharing system in Salamanca, called SalenBici. It also includes an outline of the results and conclusions, a discussion on the challenges encountered in this domain, as well as possibilities for future work. Full article

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

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15 pages, 5568 KiB

Open AccessArticle

A Study of Order Modification for Reactive Power Support by Wind Farm during Communication Failure

by Seungmin Jung¹, Yeuntae Yoo², Taehyung Kim², Jae-Hyeong Lee², Minhan Yoon³ and Gilsoo Jang^2,*

¹ Department of Electrical Engineering, Hanbat National University, Daejeon 305-719, Korea

² School of Electrical Engineering, Korea University, Seoul 136-713, Korea

³ Department of Electrical Engineering, Tongmyong University, Busan 48520, Korea

Appl. Sci. 2018, 8(1), 68; https://doi.org/10.3390/app8010068 - 5 Jan 2018

Viewed by 4119

Abstract

Various control methods and applications have been introduced to power systems in order to alleviate the uncertainties of relying on renewable sources. This paper, focusing on a reactive power allocation process, discusses the development of a self-modification algorithm and its introduction to an [...] Read more.

Various control methods and applications have been introduced to power systems in order to alleviate the uncertainties of relying on renewable sources. This paper, focusing on a reactive power allocation process, discusses the development of a self-modification algorithm and its introduction to an online reference management system. The algorithm is designed to predict unexpected situations occurring in real-time operations, when, due to technical issues, the control system becomes unavailable. A test system has been formed to check the feasibility of the composed method. As the main purpose of the feasibility study is checking availability with a complex solution, case studies are designed to adapt a reactive power allocation method based on loss minimization. When unexpected systemic errors were induced, the proposed modification plan changed order automatically with maintaining previous objective function. The improved effects, caused by realistic responses, are classified according to EMTDC (Electro-Magnetic Transient Design and Control) analysis. Full article

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15 pages, 1666 KiB

Open AccessFeature PaperArticle

Estimation of Mental Distress from Photoplethysmography

by Roberto Zangróniz¹

, Arturo Martínez-Rodrigo¹

, María T. López²

, José Manuel Pastor¹

and Antonio Fernández-Caballero^2,3,*

¹ Instituto de Tecnologías Audiovisuales, Universidad de Castilla-La Mancha, 16071 Cuenca, Spain

² Instituto de Investigación en Informática, Universidad de Castilla-La Mancha, 02071 Albacete, Spain

³ Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029 Madrid, Spain

Appl. Sci. 2018, 8(1), 69; https://doi.org/10.3390/app8010069 - 5 Jan 2018

Cited by 48 | Viewed by 7231

Abstract

This paper introduces the design of a new wearable photoplethysmography (PPG) sensor and its assessment for mental distress estimation. In our design, a PPG sensor obtains blood volume information by means of an optical plethysmogram technique. A number of temporal, morphological and frequency [...] Read more.

This paper introduces the design of a new wearable photoplethysmography (PPG) sensor and its assessment for mental distress estimation. In our design, a PPG sensor obtains blood volume information by means of an optical plethysmogram technique. A number of temporal, morphological and frequency markers are computed using time intervals between adjacent normal cardiac cycles to characterize pulse rate variability (PRV). In order to test the efficiency of the developed wearable for classifying distress versus calmness, the well-known International Affective Picture System has been used to induce different levels of arousal in forty-five healthy participants. The obtained results have shown that temporal features present a single discriminant power between emotional states of calm and stress, ranging from 67 to 72%. Moreover, a discriminant tree-based model is used to assess the possible underlying relationship among parameters. In this case, the combination of temporal parameters reaches 82.35% accuracy. Considering the low difficulty of metrics and methods used in this work, the algorithms are prepared to be embedded into a micro-controller device to work in real-time and in a long-term fashion. Full article

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

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17 pages, 3267 KiB

Open AccessArticle

Placing Visual Sensors Using Heuristic Algorithms for Bridge Surveillance

by Sungbum Jun¹, Tai-Woo Chang^2,*

and Hyuk-Jin Yoon³

¹ School of Industrial Engineering, Purdue University, West Lafayette, IN 47907, USA

² Department of Industrial & Management Engineering/Intelligence & Manufacturing Research Center, Kyonggi University, Suwon, Gyeonggi 16227, Korea

³ Korea Railroad Research Institute, Uiwang, Gyeonggi 16105, Korea

Appl. Sci. 2018, 8(1), 70; https://doi.org/10.3390/app8010070 - 6 Jan 2018

Cited by 14 | Viewed by 3937

Abstract

This study addresses the camera placement problem for bridge surveillance and proposes solutions that minimize the cost while satisfying the minimum coverage level. We discuss the field of view of cameras in the three-dimensional space. We also consider occlusions, the characteristics of surveillance [...] Read more.

This study addresses the camera placement problem for bridge surveillance and proposes solutions that minimize the cost while satisfying the minimum coverage level. We discuss the field of view of cameras in the three-dimensional space. We also consider occlusions, the characteristics of surveillance targets, and different pan-tilt-zoom cameras in the visibility test. To solve the camera placement problem while minimizing the total cost, we propose a genetic algorithm (GA) and a uniqueness score with a local search algorithm (ULA). Problem sets for a large-scale dimension scenario are generated based on the data of actual bridges in the Republic of Korea. For three simulation sets and a case study of Samoonjin Bridge, the proposed ULA yields better results than GA. Full article

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

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14 pages, 4680 KiB

Open AccessArticle

Phase Coherence Index, HHT and Wavelet Analysis to Extract Features from Active and Passive Distribution Networks

by Silvano Vergura^*

and Mario Carpentieri

Department of Electrical and Information Engineering, Polytechnic University of Bari, St. E. Orabona 4, I-70125 Bari, Italy

Appl. Sci. 2018, 8(1), 71; https://doi.org/10.3390/app8010071 - 7 Jan 2018

Cited by 8 | Viewed by 5065

Abstract

The modern Power Distribution Systems (PDS) operate more and more often with distributed generators and the optimal operation of the utility distribution systems has to take into account the possibility of bi-directional energy flows, although this event may only occur for some of [...] Read more.

The modern Power Distribution Systems (PDS) operate more and more often with distributed generators and the optimal operation of the utility distribution systems has to take into account the possibility of bi-directional energy flows, although this event may only occur for some of the PDS. For this reason, the analysis methods that are usually employed to investigate the electrical behavior of the PDS can be more or less effective, depending on the typology of electrical loads connected to the line and on the presence or absence of Renewable Energy Sources (RES). This paper proposes either a methodology to select the best performing mathematical tool to investigate the electrical behavior of the PDS—depending on their linearity and stationarity—either an index to discriminate the PDS on the basis of a different amount of PV penetration. The proposed approach is applied to three real cases of PDS with different characteristics: residential and commercial, in the presence or absence of PV plants. In addition, two indices that are able to characterize the PDS in terms of periodicity and disturbance of the electrical signal are considered, specifically the phase coherence between two arbitrary signals and the phase coherence between an arbitrary signal and a reference one. The combined use of these indices can give valuable information about the degree of non-linearity and can be a measure of the PV penetration in a distribution circuit. Full article

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

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16 pages, 2947 KiB

Open AccessArticle

A Low-Power WLAN Communication Scheme for IoT WLAN Devices Using Wake-Up Receivers

by Hanseul Hong¹

, Young Yong Kim¹ and Ronny Yongho Kim^2,*

¹ School of Electrical & Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

² Department of Railroad Electrical & Electronic Engineering, Korea National University of Transportation, 157 Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 16106, Korea

Appl. Sci. 2018, 8(1), 72; https://doi.org/10.3390/app8010072 - 7 Jan 2018

Cited by 14 | Viewed by 5041

Abstract

In this paper, we propose a delay- and power-efficient, multi-user, low-power wireless local area network (WLAN) communication scheme for Internet of Things (IoT) WLAN devices. Extremely low-power operation is one of the key requirements of emerging IoT devices. However, the current duty-cycle-based power [...] Read more.

In this paper, we propose a delay- and power-efficient, multi-user, low-power wireless local area network (WLAN) communication scheme for Internet of Things (IoT) WLAN devices. Extremely low-power operation is one of the key requirements of emerging IoT devices. However, the current duty-cycle-based power saving approach may incur large access delay times owing to the trade-offs between the power consumption and the access delay. In order to reduce this delay and enhance the power-saving performance, wake-up receiver-based schemes have been proposed. However, because wake-up receiver-based schemes do not consider multiuser operation in dense communication environments, large delays are inevitable in the case of multiuser operation. In order to provide extremely low-power operation and under 1-mW standby power with reduced delay, we employed the optimized multiuser transmission scheduling of IEEE 802.11ax in the proposed scheme and proper enhanced distributed channel access (EDCA) parameter settings. This is with the aim to reduce the delay caused by long wake-up times, and to avoid collisions caused by simultaneous transmission in uplink multiuser scenario. By using the proposed scheme, simultaneous IoT communication with multiple mobile IoT devices is possible while providing low-power operation. Simulation results verified the outstanding delay performance of the proposed scheme. Full article

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16 pages, 7565 KiB

Open AccessArticle

Controllable Micro-Particle Rotation and Transportation Using Sound Field Synthesis Technique

by Shuang Deng¹

, Kun Jia^2,*, Eryong Wu^1,*, Xuxiao Hu³, Zongwei Fan⁴ and Keji Yang¹

¹ State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, China

² State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi’an Jiaotong University, 28 West Xianning Road, Xi’an 710049, China

³ School of Mechanical and Automatic Control, Zhejiang Sci-Tech University, Hangzhou 310018, China

⁴ School of Engineering, Qufu Normal University, Rizhao 276825, China

Appl. Sci. 2018, 8(1), 73; https://doi.org/10.3390/app8010073 - 8 Jan 2018

Cited by 10 | Viewed by 4583

Abstract

Rotation and transportation of micro-particles using ultrasonically-driven devices shows promising applications in the fields of biological engineering, composite material manufacture, and micro-assembly. Current interest in mechanical effects of ultrasonic waves has been stimulated by the achievements in manipulations with phased array. Here, we [...] Read more.

Rotation and transportation of micro-particles using ultrasonically-driven devices shows promising applications in the fields of biological engineering, composite material manufacture, and micro-assembly. Current interest in mechanical effects of ultrasonic waves has been stimulated by the achievements in manipulations with phased array. Here, we propose a field synthesizing method using the fewest transducers to control the orientation of a single non-spherical micro-particle as well as its spatial location. A localized acoustic force potential well is established and rotated by using sound field synthesis technique. The resultant acoustic radiation torque on the trapped target determines its equilibrium angular position. A prototype device consisting of nine transducers with 2 MHz center frequency is designed and fabricated. Controllable rotation of a silica rod with 90 μm length and 15 μm diameter is then successfully achieved. There is a good agreement between the measured particle orientation and the theoretical prediction. Within the same device, spatial translation of the silica rod can also be realized conveniently. When compared with the existing acoustic rotation methods, the employed transducers of our method are strongly decreased, meanwhile, device functionality is improved. Full article

(This article belongs to the Section Acoustics and Vibrations)

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18 pages, 3198 KiB

Open AccessArticle

A General Euler Angle Error Model of Strapdown Inertial Navigation Systems

by Jianli Li^1,2,*, Pengfei Dang², Yiqi Li² and Bin Gu²

¹ The National Key Lab of Satellite Navigation System and Equipment Technology, The 54th Research Institute of China Electronics Technology Group Corporation, Shijiazhuang 050002, China

² School of Instrument Science and Opto-Electronic Engineering, Beihang University, Beijing 100191, China

Appl. Sci. 2018, 8(1), 74; https://doi.org/10.3390/app8010074 - 12 Jan 2018

Cited by 6 | Viewed by 7721

Abstract

Attitude error models play an important role in analyzing the characteristics of navigation error propagation for the design and operation of strapdown inertial navigation systems (SINS). However, the majority of existing attitude error models focus on misalignment, rather than Euler angle errors. Misalignment [...] Read more.

Attitude error models play an important role in analyzing the characteristics of navigation error propagation for the design and operation of strapdown inertial navigation systems (SINS). However, the majority of existing attitude error models focus on misalignment, rather than Euler angle errors. Misalignment cannot directly describe attitude error propagation, which is an indirect measurement. To solve the problem, a general Euler angle error model of SINS is proposed. Based on Euler angle error propagation analysis, relative Euler angle errors, and convected Euler angle errors are introduced to compose the general Euler angle error model. Simulation experiments are carried out to verify the proposed model. Full article

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13 pages, 25032 KiB

Open AccessArticle

Real-Time Strength Monitoring for Concrete Structures Using EMI Technique Incorporating with Fuzzy Logic

by Sang-Ki Choi¹, Najeebullah Tareen², Junkyeong Kim²

, Seunghee Park^3,* and Innjoon Park⁴

¹ Interdisciplinary Program in Crisis, Disaster and Risk Management, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si 16419, Gyonggi-do, Korea

² Department of Civil, Architecture & Environmental System Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si 16419, Gyonggi-do, Korea

³ School of Civil & Architectural Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si 16419, Gyonggi-do, Korea

⁴ Department of Civil Engineering, Hanseo University, 46 Hanseo 1-ro, Haemi-myeon, Seosan-si 31962, Chungcheongnam-do, Korea

Appl. Sci. 2018, 8(1), 75; https://doi.org/10.3390/app8010075 - 8 Jan 2018

Cited by 22 | Viewed by 4425

Abstract

This study estimates the strength of a special mixture of high-strength concrete (HSC) with admixtures for use in a nuclear power plant (NPP). Nuclear power plant structures need a HSC with some additional qualities to operate the safe options. For this purpose, the [...] Read more.

This study estimates the strength of a special mixture of high-strength concrete (HSC) with admixtures for use in a nuclear power plant (NPP). Nuclear power plant structures need a HSC with some additional qualities to operate the safe options. For this purpose, the experimented concrete was specially designed to fulfill the required qualities of NPP. For gaining these desirable qualities, it needs to monitor the concrete strength development process. Here, the PZT materials were used as sensors to acquire data by measuring the electromechanical impedance (EMI), and then cross correlation (CC) was calculated to look at changes according to strength development. Data were measured for 28 days, and over this period concrete can gain up to 96% of its design strength. This technique is based on a single sensor. After casting concrete, the PZT material starts vibrating as an actuator to produce vibrations. At the same time, it also works as a sensor to measure the dynamic response of the structure to the vibrations. With strength development, the resonant frequencies of the EMI start changing. To estimate the strength development, a fuzzy logic tool was used to analyze the parameters, allowing for us to estimate and predict the concrete strength. For cross-checking, the estimated strength was compared with the actual strength of concrete; this was determined by examining cuboid cores taken from specimens during experiments at the 1st, 3rd, 7th, 14th, and 28th days. According to the results, this approach of strength estimation and monitoring the strength development is useful for forecasting the stability of structures. Full article

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

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16 pages, 880 KiB

Open AccessArticle

Prescribed Performance Constraint Regulation of Electrohydraulic Control Based on Backstepping with Dynamic Surface

by Qing Guo^1,2,*

, Yili Liu¹, Dan Jiang^3,*, Qiang Wang¹, Wenying Xiong¹, Jie Liu¹ and Xiaochai Li¹

¹ School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu 611731, China

² State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China

³ School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

Appl. Sci. 2018, 8(1), 76; https://doi.org/10.3390/app8010076 - 8 Jan 2018

Cited by 29 | Viewed by 4309

Abstract

In electro-hydraulic system (EHS), uncertain nonlinearities such as some hydraulic parametric uncertainties and external load disturbance often degrade the output dynamic performance. To address this problem, a prescribed performance constraint (PPC) control method is adopted in EHS to restrict the tracking position error [...] Read more.

In electro-hydraulic system (EHS), uncertain nonlinearities such as some hydraulic parametric uncertainties and external load disturbance often degrade the output dynamic performance. To address this problem, a prescribed performance constraint (PPC) control method is adopted in EHS to restrict the tracking position error of the cylinder position to a prescribed accuracy and guarantee the dynamic and steady position response in a required boundedness under these uncertain nonlinearities. Furthermore, a dynamic surface is designed to avoid the explosion of complexity due to the repeatedly calculated differentiations of the virtual control variables derived in backstepping. The effectiveness of the proposed controller has been verified by a comparative results. Full article

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

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14 pages, 4347 KiB

Open AccessArticle

New Insights in the Ion Beam Sputtering Deposition of ZnO-Fluoropolymer Nanocomposites

by Maria Chiara Sportelli¹

, Marco Valentini^2,3, Rosaria Anna Picca¹

, Antonella Milella¹, Angelo Nacci¹

, Antonio Valentini^2,3 and Nicola Cioffi^1,*

¹ Dipartimento di Chimica, Università degli Studi di Bari “Aldo Moro”, via E. Orabona 4, Bari 70126, Italy

² Dipartimento Interateneo di Fisica, Università degli Studi di Bari “Aldo Moro”, via Amendola 173, Bari 70126, Italy

³ INFN-Sezione di Bari, via E. Orabona 4, Bari 70126, Italy

Appl. Sci. 2018, 8(1), 77; https://doi.org/10.3390/app8010077 - 9 Jan 2018

Cited by 11 | Viewed by 4510

Abstract

Surface modification treatments able to confer antistain/antibacterial properties to natural or synthetic materials are receiving increasing attention among scientists. Ion beam co-sputtering (IBS) of zinc oxide (ZnO) and poly-tetrafluoroethylene (PTFE) targets allows for the preparation of novel multifunctional coatings composed of antimicrobial ZnO [...] Read more.

Surface modification treatments able to confer antistain/antibacterial properties to natural or synthetic materials are receiving increasing attention among scientists. Ion beam co-sputtering (IBS) of zinc oxide (ZnO) and poly-tetrafluoroethylene (PTFE) targets allows for the preparation of novel multifunctional coatings composed of antimicrobial ZnO nanoparticles (NPs) finely dispersed in an antistain PTFE polymeric matrix. Remarkably, IBS has been proved to be successful in the controlled deposition of thin nanocoatings as an alternative to wet methods. Moreover, tuning IBS deposition parameters allows for the control of ZnONP loadings, thus modulating the antibacterial/antistain coating’s final properties. All the deposited coatings were fully characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM) in order to obtain information on the materials’ surface composition, with deep insight into the nanocoatings’ morphology as a function of the ZnONP loadings. An analysis of high-resolution XP spectra evidenced a high degree of polymer defluorination along with the formation of inorganic fluorides at increasing ZnO volume ratios. Hence, post-deposition treatments for fluorides removal, performed directly in the deposition chamber, were successfully developed and optimized. In this way, a complete stoichiometry for inorganic nanophases was obtained, allowing for the conversion of fluorides into ZnO. Full article

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

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8 pages, 844 KiB

Open AccessArticle

The Effects of Remineralization via Fluoride Versus Low-Level Laser IR810 and Fluoride Agents on the Mineralization and Microhardness of Bovine Dental Enamel

by Edith Lara-Carrillo¹

, Nayeli Lovera-Rojas¹, Raúl Alberto Morales-Luckie²

, Norma Leticia Robles-Bermeo¹, María Magdalena García-Fabila³, Rubén De la Rosa-Santillana⁴ and Carlo Eduardo Medina-Solís^1,4,*

¹ Advanced Studies and Research Center in Dentistry “Dr. Keisaburo Miyata” of School of Dentistry at Autonomous University State of Mexico, Toluca 50130, Mexico

² Faculty of Chemistry, Department of Materials Science, Center for Research in Sustainable Chemistry (CIQS), Autonomous University State of Mexico-National Autonomous University of Mexico (UNAM), Toluca 50120, Mexico

³ Faculty of Chemistry, Instrumental Analysis Laboratory, Autonomous University State of Mexico, Toluca 50120, Mexico

⁴ Academic Area of Dentistry of Health Sciences Institute at the Autonomous University of Hidalgo State, Pachuca 42060, Mexico

Appl. Sci. 2018, 8(1), 78; https://doi.org/10.3390/app8010078 - 9 Jan 2018

Cited by 4 | Viewed by 4165

Abstract

The objective of this study was to assess the mineralization and microhardness of bovine dental enamel surfaces treated with fluoride, tri-calcium phosphate, and infrared (IR) 810 laser irradiation. The study used 210 bovine incisors, which were divided into six groups (n = [...] Read more.

The objective of this study was to assess the mineralization and microhardness of bovine dental enamel surfaces treated with fluoride, tri-calcium phosphate, and infrared (IR) 810 laser irradiation. The study used 210 bovine incisors, which were divided into six groups (n = 35 in each): Group A: Untreated (control), Group B: Fluoride (Durapath-Colgate), Group C: Fluoride+Tri-calcium phosphate (Clin-Pro White-3 M), Group D: Laser IR 810 (Quantum), Group E: Fluoride+laser, and Group F: Fluoride+tri-calcium phosphate+laser). Mineralization was measured via UV-Vis spectroscopy for phosphorus and via atomic absorption spectroscopy for calcium upon demineralization and remineralization with proven agents. Microhardness (SMH) was measured after enamel remineralization. Mineral loss data showed differences between the groups before and after the mineralizing agents were placed (p < 0.05). Fluoride presented the highest remineralization tendency for both calcium and phosphate, with a Vickers microhardness of 329.8 HV0.1/11 (p < 0.05). It was observed that, if remineralization solution contained fewer minerals, the microhardness surface values were higher (r = −0.268 and −0.208; p < 0.05). This study shows that fluoride has a remineralizing effect compared with calcium triphosphate and laser IR810. This in vitro study imitated the application of different remineralizing agents and showed which one was the most efficient for treating non-cavitated injuries. This can prevent the progression of lesions in patients with white spot lesions. Full article

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

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9 pages, 2715 KiB

Open AccessArticle

Thiokol with Excellent Restriction on the Shuttle Effect in Lithium–Sulfur Batteries

by Bin Liu¹, Shan Wang^1,*, Quanling Yang¹, Guo-Hua Hu^1,2 and Chuanxi Xiong^1,*

¹ State Key Laboratory of Silicate Materials for Architectures, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China

² Laboratory of Reactions and Process Engineering (LRGP, CNRS UMR 7274), CNRS-University of Lorraine, 1rue Grandville, BP 20451, 54001 Nancy, France

Appl. Sci. 2018, 8(1), 79; https://doi.org/10.3390/app8010079 - 9 Jan 2018

Cited by 9 | Viewed by 5765

Abstract

Commercial application of lithium–sulfur (Li–S) batteries is still greatly hampered by several issues, especially the shuttle effect of polysulfides. In this work, we proposed a simple but effective method to restrain the shuttle of the soluble polysulfides by adopting a novel binder of [...] Read more.

Commercial application of lithium–sulfur (Li–S) batteries is still greatly hampered by several issues, especially the shuttle effect of polysulfides. In this work, we proposed a simple but effective method to restrain the shuttle of the soluble polysulfides by adopting a novel binder of Thiokol in the sulfur cathode. Compared to the battery with conventional polyvinylidene fluoride (PVDF) binder, the initial discharge capacity for the battery with the Thiokol binder were increased by 42%, that is from 578 to 819 mAh/g, while the capacity after 200 cycles were increased by 201%, which is from 166 to 501 mAh/g. Besides, according to the rate capability test cycling from 0.1 to 1 C, the battery with the Thiokol binder still released a capacity amounting to 90.9% of the initial capacity, when the current density returned back to 0.1 C. Based on the UV–vis and ex situ XRD results, it is reasonably proposed that the reactions with polysulfides of the Thiokol help to restrain the shuttle effect of polysulfides. It is therefore suggested that the novel Thiokol binder holds promise for application in high-performance lithium–sulfur batteries. Full article

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

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23 pages, 1589 KiB

Open AccessArticle

Locomotion Efficiency Optimization of Biologically Inspired Snake Robots

by Eleni Kelasidi^1,*

, Mansoureh Jesmani², Kristin Y. Pettersen¹ and Jan Tommy Gravdahl²

¹ Centre for Autonomous Marine Operations and Systems, Department of Engineering Cybernetics at NTNU, NO-7491 Trondheim, Norway

² Department of Engineering Cybernetics at NTNU, NO-7491 Trondheim, Norway

Appl. Sci. 2018, 8(1), 80; https://doi.org/10.3390/app8010080 - 9 Jan 2018

Cited by 34 | Viewed by 6522

Abstract

Snake robots constitute bio-inspired solutions that have been studied due to their ability to move in challenging environments where other types of robots, such as wheeled or legged robots, usually fail. In this paper, we consider both land-based and swimming snake robots. One [...] Read more.

Snake robots constitute bio-inspired solutions that have been studied due to their ability to move in challenging environments where other types of robots, such as wheeled or legged robots, usually fail. In this paper, we consider both land-based and swimming snake robots. One of the principal concerns of the bio-inspired snake robots is to increase the motion efficiency in terms of the forward speed by improving the locomotion methods. Furthermore, energy efficiency becomes a crucial challenge for this type of robots due to the importance of long-term autonomy of these systems. In this paper, we take into account both the minimization of the power consumption and the maximization of the achieved forward velocity in order to investigate the optimal gait parameters for bio-inspired snake robots using lateral undulation and eel-like motion patterns. We furthermore consider possible negative work effects in the calculation of average power consumption of underwater snake robots. To solve the multi-objective optimization problem, we propose transforming the two objective functions into a single one using a weighted-sum method. For different set of weight factors, Particle Swarm Optimization is applied and a set of optimal points is consequently obtained. Pareto fronts or trade-off curves are illustrated for both land-based and swimming snake robots with different numbers of links. Pareto fronts represent trade-offs between the objective functions. For example, how increasing the forward velocity results in increasing power consumption. Therefore, these curves are a very useful tool for the control and design of snake robots. The trade-off curve thus constitutes a very useful tool for both the control and design of bio-inspired snake robots. In particular, the operators or designers of bio-inspired snake robots can choose a Pareto optimal point based on the trade-off curve, given the preferred number of links on the robot. The optimal gait parameters for the robot control system design are then directly given both for land-based and underwater snake robots. Moreover, we are able to obtain some observations about the optimal values of the gait parameters, which provide very important insights for future control design of bio-inspired snake robots. Full article

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

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14 pages, 2157 KiB

Open AccessFeature PaperArticle

Supercritical Regeneration of an Activated Carbon Fiber Exhausted with Phenol

by M. Jesus Sanchez-Montero, Jennifer Pelaz, Nicolas Martin-Sanchez

, Carmen Izquierdo and Francisco Salvador^*

Dpto Química-Física, Facultad de Ciencias Química, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca, Spain

Appl. Sci. 2018, 8(1), 81; https://doi.org/10.3390/app8010081 - 9 Jan 2018

Cited by 14 | Viewed by 4851

Abstract

The properties of supercritical CO₂ (SCCO₂) and supercritical water (SCW) turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF) saturated with a [...] Read more.

The properties of supercritical CO₂ (SCCO₂) and supercritical water (SCW) turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF) saturated with a pollutant usually contained in wastewater and drinking water, phenol. Severe regeneration conditions, up to 225 bar and 400 °C, had to be employed in SCCO₂ regeneration to break the strong interaction established between phenol and the ACF. Under suitable conditions (regeneration temperature, time, and pressure, and flow of SCCO₂) the adsorption capacity of the exhausted ACF was completely recovered, and even slightly increased. Most of the retained phenol was removed by thermal desorption, but the extra percentage removed by extraction allowed SCCO₂ regeneration to be significantly more efficient than the classical thermal regeneration methods. SCCO₂ regeneration and SCW regeneration were also compared for the first time. The use of SCW slightly improved regeneration, although SCW pressure was thrice SCCO₂ pressure. The pathways that controlled SCW regeneration were also investigated. Full article

(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)

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13 pages, 15721 KiB

Open AccessArticle

A Novel Particulate Matter 2.5 Sensor Based on Surface Acoustic Wave Technology

by Jiuling Liu^1,*, Wenchang Hao², Minghua Liu¹, Yong Liang¹ and Shitang He¹

¹ Institute of Acoustics, Chinese Academy of Sciences, No. 21, North 4th Ring West Road, Beijing 100190, China

² Beijing Research Institute of Telemetry, Beijing 100076, China

Appl. Sci. 2018, 8(1), 82; https://doi.org/10.3390/app8010082 - 9 Jan 2018

Cited by 24 | Viewed by 7157

Abstract

Design, fabrication and experiments of a miniature particulate matter (PM) 2.5 sensor based on the surface acoustic wave (SAW) technology were proposed. The sensor contains a virtual impactor (VI) for particle separation, a thermophoretic precipitator (TP) for PM_2.5 capture and a SAW [...] Read more.

Design, fabrication and experiments of a miniature particulate matter (PM) 2.5 sensor based on the surface acoustic wave (SAW) technology were proposed. The sensor contains a virtual impactor (VI) for particle separation, a thermophoretic precipitator (TP) for PM_2.5 capture and a SAW sensor chip for PM_2.5 mass detection. The separation performance of the VI was evaluated by using the finite element method (FEM) model and the PM_2.5 deposition characteristic in the TP was obtained by analyzing the thermophoretic theory. Employing the coupling-of-modes (COM) model, a low loss and high-quality SAW resonator was designed. By virtue of the micro electro mechanical system (MEMS) technology and semiconductor technology, the SAW based PM_2.5 sensor detecting probe was fabricated. Then, combining a dual-port SAW oscillator and an air sampler, the experimental platform was set up. Exposing the PM_2.5 sensor to the polystyrene latex (PSL) particles in a chamber, the sensor performance was evaluated. The results show that by detecting the PSL particles with a certain diameter of 2 μm, the response of the SAW based PM_2.5 sensor is linear, and in accordance with the response of the light scattering based PM_2.5 monitor. The developed SAW based PM_2.5 sensor has great potential for the application of airborne particle detection. Full article

(This article belongs to the Section Acoustics and Vibrations)

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17 pages, 5431 KiB

Open AccessFeature PaperArticle

Silicon Photonics towards Disaggregation of Resources in Data Centers

by Miltiadis Moralis-Pegios¹, Nikolaos Terzenidis¹, George Mourgias-Alexandris¹

and Konstantinos Vyrsokinos^2,*

¹ Department of Informatics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

² Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

Appl. Sci. 2018, 8(1), 83; https://doi.org/10.3390/app8010083 - 10 Jan 2018

Cited by 5 | Viewed by 4327

Abstract

In this paper, we demonstrate two subsystems based on Silicon Photonics, towards meeting the network requirements imposed by disaggregation of resources in Data Centers. The first one utilizes a 4 × 4 Silicon photonics switching matrix, employing Mach Zehnder Interferometers (MZIs) with Electro-Optical [...] Read more.

In this paper, we demonstrate two subsystems based on Silicon Photonics, towards meeting the network requirements imposed by disaggregation of resources in Data Centers. The first one utilizes a 4 × 4 Silicon photonics switching matrix, employing Mach Zehnder Interferometers (MZIs) with Electro-Optical phase shifters, directly controlled by a high speed Field Programmable Gate Array (FPGA) board for the successful implementation of a Bloom-Filter (BF)-label forwarding scheme. The FPGA is responsible for extracting the BF-label from the incoming optical packets, carrying out the BF-based forwarding function, determining the appropriate switching state and generating the corresponding control signals towards conveying incoming packets to the desired output port of the matrix. The BF-label based packet forwarding scheme allows rapid reconfiguration of the optical switch, while at the same time reduces the memory requirements of the node’s lookup table. Successful operation for 10 Gb/s data packets is reported for a 1 × 4 routing layout. The second subsystem utilizes three integrated spiral waveguides, with record-high 2.6 ns/mm², delay versus footprint efficiency, along with two Semiconductor Optical Amplifier Mach-Zehnder Interferometer (SOA-MZI) wavelength converters, to construct a variable optical buffer and a Time Slot Interchange module. Error-free on-chip variable delay buffering from 6.5 ns up to 17.2 ns and successful timeslot interchanging for 10 Gb/s optical packets are presented. Full article

(This article belongs to the Special Issue Optical Interconnects)

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19 pages, 6856 KiB

Open AccessArticle

Dynamic and Quantitative Assessment of Blood Coagulation Status with an Oscillatory Rheometer

by Silju-John Kunnakattu^1,2, Theresia Groß², Juvano Knieps², Tim Kemper², Stefan Fennrich¹, Nicole Rauch², Hans P. Wendel¹ and Sandra Stoppelkamp^1,*

¹ Department of Thoracic, Cardiac and Vascular Surgery, Clinical Research Laboratory, University Hospital Tuebingen, 72076 Tuebingen, Germany

² Department of Micro- and Nanoanalytics, University of Applied Sciences Iserlohn, 58644 Iserlohn, Germany

Appl. Sci. 2018, 8(1), 84; https://doi.org/10.3390/app8010084 - 9 Jan 2018

Cited by 3 | Viewed by 6497

Abstract

During open heart surgery, the haemostasis status of a patient has to be monitored permanently in order to quickly and reliably detect bleeding or coagulation-based disorders. Currently, no single medical device is available to provide a comprehensive solution for monitoring the coagulation status [...] Read more.

During open heart surgery, the haemostasis status of a patient has to be monitored permanently in order to quickly and reliably detect bleeding or coagulation-based disorders. Currently, no single medical device is available to provide a comprehensive solution for monitoring the coagulation status (coagulation, platelets and fibrinolysis). We intend to approach this problem with a rheological method. Here, we compared the performance of an oscillatory rheometer with a medical reference device, a ball coagulometer. Measuring the extrinsic coagulation (prothrombin time; PT), various heparin concentrations (0.5–2.0 IU/mL) could be differentiated and also discriminated from the intrinsic coagulation (activated partial thromboplastin time; aPTT) providing comparable clotting times between rheometer and ball coagulometer. In addition, the oscillatory rheometer was capable to detect the antagonising of heparin with the equimolar concentration of protamine and also the titration of various protamine concentrations (0.5–3.0 IU/mL) to a fixed heparin concentration (2 IU/mL). The addition of increasing concentrations of heparin to citrated blood prolonged the clotting time (CT), changed the slope calculated by linear regression of the elastic and viscous shear moduli (i.e., information of the coagulation process) and changed the value of the shear moduli at the end of the measurement (300 s). These results indicate that the oscillatory rheometer is capable to dynamically measure the haemostasis status with different activators and various inhibitor concentrations. Full article

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

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24 pages, 1380 KiB

Open AccessArticle

CoSimulating Communication Networks and Electrical System for Performance Evaluation in Smart Grid

by Hwantae Kim¹, Kangho Kim², Seongjoon Park³

, Hyunsoon Kim⁴ and Hwangnam Kim^3,*

¹ Kukka Inc., Seoul 06245, Korea

² Network Technology R&D Center, SK Telecom, Seongnam-si, Gyeonggi-do 13595, Korea

³ School of Electrical Engineering, Korea University, Seoul 02841, Korea

⁴ TmaxSoft Inc., Seongnam-si, Gyeonggi-do 13613, Korea

Appl. Sci. 2018, 8(1), 85; https://doi.org/10.3390/app8010085 - 9 Jan 2018

Cited by 15 | Viewed by 5190

Abstract

In smart grid research domain, simulation study is the first choice, since the analytic complexity is too high and constructing a testbed is very expensive. However, since communication infrastructure and the power grid are tightly coupled with each other in the smart grid, [...] Read more.

In smart grid research domain, simulation study is the first choice, since the analytic complexity is too high and constructing a testbed is very expensive. However, since communication infrastructure and the power grid are tightly coupled with each other in the smart grid, a well-defined combination of simulation tools for the systems is required for the simulation study. Therefore, in this paper, we propose a cosimulation work called OOCoSim, which consists of OPNET (network simulation tool) and OpenDSS (power system simulation tool). By employing the simulation tool, an organic and dynamic cosimulation can be realized since both simulators operate on the same computing platform and provide external interfaces through which the simulation can be managed dynamically. In this paper, we provide OOCoSim design principles including a synchronization scheme and detailed descriptions of its implementation. To present the effectiveness of OOCoSim, we define a smart grid application model and conduct a simulation study to see the impact of the defined application and the underlying network system on the distribution system. The simulation results show that the proposed OOCoSim can successfully simulate the integrated scenario of the power and network systems and produce the accurate effects of the networked control in the smart grid. Full article

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21 pages, 1294 KiB

Open AccessArticle

Improving Roadside Unit Deployment in Vehicular Networks by Exploiting Genetic Algorithms

by Manuel Fogue¹, Julio A. Sanguesa¹

, Francisco J. Martinez^1,*

and Johann M. Marquez-Barja²

¹ iNiT Research Group, Computer Science and System Engineering Department, University of Zaragoza, Ciudad Escolar s/n, 44003 Teruel, Spain

² IDLab—Faculty of Applied Engineering, University of Antwerp—imec, Groenenborgerlaan 171, 2020 Antwerp, Belgium

Appl. Sci. 2018, 8(1), 86; https://doi.org/10.3390/app8010086 - 9 Jan 2018

Cited by 68 | Viewed by 5884

Abstract

Vehicular networks make use of the Roadside Units (RSUs) to enhance the communication capabilities of the vehicles in order to forward control messages and/or to provide Internet access to vehicles, drivers and passengers. Unfortunately, within vehicular networks, the wireless signal propagation is mostly [...] Read more.

Vehicular networks make use of the Roadside Units (RSUs) to enhance the communication capabilities of the vehicles in order to forward control messages and/or to provide Internet access to vehicles, drivers and passengers. Unfortunately, within vehicular networks, the wireless signal propagation is mostly affected by buildings and other obstacles (e.g., urban fixtures), in particular when considering the IEEE 802.11p standard. Therefore, a crowded RSU deployment may be required to ensure vehicular communications within urban environments. Furthermore, some applications, notably those applications related to safety, require a fast and reliable warning data transmission to the emergency services and traffic authorities. However, communication is not always possible in vehicular environments due to the lack of connectivity even employing multiple hops. To overcome the signal propagation problem and delayed warning notification time issues, an effective, smart, cost-effective and all-purpose RSU deployment policy should be put into place. In this paper, we propose the genetic algorithm for roadside unit deployment (GARSUD) system, which uses a genetic algorithm that is capable of automatically providing an RSU deployment suitable for any given road map layout. Our simulation results show that GARSUD is able to reduce the warning notification time (the time required to inform emergency authorities in traffic danger situations) and to improve vehicular communication capabilities within different density scenarios and complexity layouts. Full article

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35 pages, 2667 KiB

Open AccessArticle

Low-Dimensional Reconciliation for Continuous-Variable Quantum Key Distribution

by Laszlo Gyongyosi^1,2,3,* and Sandor Imre²

¹ School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK

² Department of Networked Systems and Services, Budapest University of Technology and Economics, H-1117 Budapest, Hungary

³ MTA-BME Information Systems Research Group, Hungarian Academy of Sciences, H-1051 Budapest, Hungary

Appl. Sci. 2018, 8(1), 87; https://doi.org/10.3390/app8010087 - 9 Jan 2018

Cited by 23 | Viewed by 3846

Abstract

We propose an efficient logical layer-based reconciliation method for continuous-variable quantum key distribution (CVQKD) to extract binary information from correlated Gaussian variables. We demonstrate that by operating on the raw-data level, the noise of the quantum channel can be corrected in the low-dimensional [...] Read more.

We propose an efficient logical layer-based reconciliation method for continuous-variable quantum key distribution (CVQKD) to extract binary information from correlated Gaussian variables. We demonstrate that by operating on the raw-data level, the noise of the quantum channel can be corrected in the low-dimensional (scalar) space, and the reconciliation can be extended to arbitrary dimensions. The CVQKD systems allow an unconditionally secret communication over standard telecommunication networks. To exploit the real potential of CVQKD a robust reconciliation technique is needed. It is currently unavailable, which makes it impossible to reach the real performance of the CVQKD protocols. The reconciliation is a post-processing step separated from the transmission of quantum states, which is aimed to derive the secret key from the raw data. The reconciliation process of correlated Gaussian variables is a complex problem that requires either tomography in the physical layer that is intractable in a practical scenario, or high-cost calculations in the multidimensional spherical space with strict dimensional limitations. To avoid these issues, we define the low-dimensional reconciliation. We prove that the error probability of one-dimensional reconciliation is zero in any practical CVQKD scenario, and provides unconditional security. The results allow for significantly improving the currently available key rates and transmission distances of CVQKD. Full article

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13 pages, 982 KiB

Open AccessFeature PaperArticle

Integrated Aero–Vibroacoustics: The Design Verification Process of Vega-C Launcher

by Davide Bianco^1,*

, Francesco P. Adamo¹, Mattia Barbarino¹, Pasquale Vitiello¹, Daniele Bartoccini², Luigi Federico¹ and Roberto Citarella³

¹ Italian Aerospace Research Centre (C.I.R.A), via Maiorise snc, 81043 Capua, Italy

² Avio S.p.A., I-00034 Colleferro, Italy

³ Department of Industrial Engineering, University of Salerno, 84084 Fisciano (SA), Italy

Appl. Sci. 2018, 8(1), 88; https://doi.org/10.3390/app8010088 - 10 Jan 2018

Cited by 20 | Viewed by 4562

Abstract

The verification of a space launcher at the design level is a complex issue because of (i) the lack of a detailed modeling capability of the acoustic pressure produced by the rocket; and (ii) the difficulties in applying deterministic methods to the large-scale [...] Read more.

The verification of a space launcher at the design level is a complex issue because of (i) the lack of a detailed modeling capability of the acoustic pressure produced by the rocket; and (ii) the difficulties in applying deterministic methods to the large-scale metallic structures. In this paper, an innovative integrated design verification process is described, based on the bridging between a new semiempirical jet noise model and a hybrid finite-element method/statistical energy analysis (FEM/SEA) approach for calculating the acceleration produced at the payload and equipment level within the structure, vibrating under the external acoustic forcing field. The result is a verification method allowing for accurate prediction of the vibroacoustics in the launcher interior, using limited computational resources and without resorting to computational fluid dynamics (CFD) data. Some examples concerning the Vega-C launcher design are shown. Full article

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

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15 pages, 3674 KiB

Open AccessArticle

An Ensemble Classifier with Random Projection for Predicting Protein–Protein Interactions Using Sequence and Evolutionary Information

by Xiao-Yu Song^1,†, Zhan-Heng Chen^2,†, Xiang-Yang Sun¹, Zhu-Hong You^2,*, Li-Ping Li² and Yang Zhao¹

¹ School of Electronic and Information Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China

² Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China

^† Co-first author.

Appl. Sci. 2018, 8(1), 89; https://doi.org/10.3390/app8010089 - 10 Jan 2018

Cited by 25 | Viewed by 4554

Abstract

Identifying protein–protein interactions (PPIs) is crucial to comprehend various biological processes in cells. Although high-throughput techniques generate many PPI data for various species, they are only a petty minority of the entire PPI network. Furthermore, these approaches are costly and time-consuming and have [...] Read more.

Identifying protein–protein interactions (PPIs) is crucial to comprehend various biological processes in cells. Although high-throughput techniques generate many PPI data for various species, they are only a petty minority of the entire PPI network. Furthermore, these approaches are costly and time-consuming and have a high error rate. Therefore, it is necessary to design computational methods for efficiently detecting PPIs. In this study, a random projection ensemble classifier (RPEC) was explored to identify novel PPIs using evolutionary information contained in protein amino acid sequences. The evolutionary information was obtained from a position-specific scoring matrix (PSSM) generated from PSI-BLAST. A novel feature fusion scheme was then developed by combining discrete cosine transform (DCT), fast Fourier transform (FFT), and singular value decomposition (SVD). Finally, via the random projection ensemble classifier, the performance of the presented approach was evaluated on Yeast, Human, and H. pylori PPI datasets using 5-fold cross-validation. Our approach achieved high prediction accuracies of 95.64%, 96.59%, and 87.62%, respectively, effectively outperforming other existing methods. Generally speaking, our approach is quite promising and supplies a practical and effective method for predicting novel PPIs. Full article

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

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11 pages, 3923 KiB

Open AccessArticle

DNA as Functional Material in Organic-Based Electronics

by Lijuan Liang^1,2, Yabo Fu¹, Dongdong Wang¹, Yen Wei³, Norihisa Kobayashi⁴ and Takeo Minari^2,*

¹ Beijing Institute of Graphic Communication, Beijing 102600, China

² World Premier International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) Tsukuba, Ibaraki 305-0044, Japan

³ Department of Chemistry, Tsinghua University, Beijing 100084, China

⁴ Department of Image & Materials Science, Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Appl. Sci. 2018, 8(1), 90; https://doi.org/10.3390/app8010090 - 10 Jan 2018

Cited by 20 | Viewed by 6307

Abstract

Recently, biological materials such as DNA molecules, proteins, and albumen have been extensively investigated for various applications, as they are environmentally friendly and exhibit novel optical and electronic properties. Especially, over the last decades, DNA–lipid complex have been frequently reported as components of [...] Read more.

Recently, biological materials such as DNA molecules, proteins, and albumen have been extensively investigated for various applications, as they are environmentally friendly and exhibit novel optical and electronic properties. Especially, over the last decades, DNA–lipid complex have been frequently reported as components of optical electronic devices. In this mini-review, the physicochemical performance of DNA–lipid complex is introduced, and then the related research progress in electronic devices such as organic thin film transistors and other optical-electrical devices are discussed. Finally, the challenges and prospects of other possible applications are also presented. Full article

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

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22 pages, 6766 KiB

Open AccessArticle

Developing Automatic Form and Design System Using Integrated Grey Relational Analysis and Affective Engineering

by Chen-Yuan Liu^1,* and Lee-Ing Tong²

¹ Department of Visual Communication Design, National Yunlin University of Science and Technology, Douliu, Yunlin 64002, Taiwan

² Department of Industrial Engineering and Management, National Chiao Tung University, Hsinchu 30010, Taiwan

Appl. Sci. 2018, 8(1), 91; https://doi.org/10.3390/app8010091 - 10 Jan 2018

Cited by 16 | Viewed by 4627

Abstract

In the modern highly competitive marketplace and global market environment, product quality improvements that abridge development time and reduce the production costs are effective methods for promoting the business competitiveness of a product in shorter lifecycles. Since the design process is the best [...] Read more.

In the modern highly competitive marketplace and global market environment, product quality improvements that abridge development time and reduce the production costs are effective methods for promoting the business competitiveness of a product in shorter lifecycles. Since the design process is the best time to control such parameters, systematically designing the processes to develop a product that more closely fits the demand requirements for the market is a key factor for developing a successful product. In this paper, a combined affective engineering method and grey relational analysis are used to develop a product design process. First, design image scale technology is used to acquire the best the design criteria factors, and then affective engineering methods are used to set the relationships between customer needs and production factors. Finally, grey relational analysis is used to select the optimal design strategy. Using this systematic design method, a higher quality product can be expanded upon in a shorter lead-time for improving business competition. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)

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19 pages, 2150 KiB

Open AccessArticle

Emergency-Prioritized Asymmetric Protocol for Improving QoS of Energy-Constraint Wearable Device in Wireless Body Area Networks

by Jaeho Lee¹

and Seungku Kim^2,*

¹ Department of Information and Communications Engineering, Seowon University, 377-3 Musimseoro, Seowon-gu, Cheongju 28674, Chungbuk, Korea

² School of Electronics Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju 28644, Chungbuk, Korea

Appl. Sci. 2018, 8(1), 92; https://doi.org/10.3390/app8010092 - 10 Jan 2018

Cited by 13 | Viewed by 3816

Abstract

Wireless Body Area Network (WBAN) is usually composed of nodes for contacting the body and coordinator for collecting the body data from the nodes. In this setup, the nodes are under constraint of the energy resource while the coordinator can be recharged and [...] Read more.

Wireless Body Area Network (WBAN) is usually composed of nodes for contacting the body and coordinator for collecting the body data from the nodes. In this setup, the nodes are under constraint of the energy resource while the coordinator can be recharged and has relatively larger energy resource than the nodes. Therefore, the architecture mechanism of the networks must not allow the nodes to consume much energy. Primarily, Medium Access Control (MAC) protocols should be carefully designed to consider this issue, because the MAC layer has the key of the energy efficiency phenomenon (e.g., idle listening). Under these characteristics, we propose a new MAC protocol to satisfy the higher energy efficiency of nodes than coordinator by designing the asymmetrically energy-balanced model between nodes and coordinator. The proposed scheme loads the unavoidable energy consumption into the coordinator instead of the nodes to extend their lifetime. Additionally, the scheme also provides prioritization for the emergency data transmission with differentiated Quality of Service (QoS). For the evaluations, IEEE 802.15.6 was used for comparison. Full article

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

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15 pages, 3098 KiB

Open AccessArticle

Generative Adversarial Networks Based Heterogeneous Data Integration and Its Application for Intelligent Power Distribution and Utilization

by Yuanpeng Tan¹, Wei Liu¹, Jian Su¹ and Xiaojing Bai^2,*

¹ Beijing Key Laboratory of Distribution Transformer Energy-Saving Technology, China Electric Power Research Institute, Beijing 100192, China

² Department of Engineering Physics, Tsinghua University, Beijing 100084, China

Appl. Sci. 2018, 8(1), 93; https://doi.org/10.3390/app8010093 - 11 Jan 2018

Cited by 6 | Viewed by 5893

Abstract

Heterogeneous characteristics of a big data system for intelligent power distribution and utilization have already become more and more prominent, which brings new challenges for the traditional data analysis technologies and restricts the comprehensive management of distribution network assets. In order to solve [...] Read more.

Heterogeneous characteristics of a big data system for intelligent power distribution and utilization have already become more and more prominent, which brings new challenges for the traditional data analysis technologies and restricts the comprehensive management of distribution network assets. In order to solve the problem that heterogeneous data resources of power distribution systems are difficult to be effectively utilized, a novel generative adversarial networks (GANs) based heterogeneous data integration method for intelligent power distribution and utilization is proposed. In the proposed method, GANs theory is introduced to expand the distribution of completed data samples. Then, a so-called peak clustering algorithm is proposed to realize the finite open coverage of the expanded sample space, and repair those incomplete samples to eliminate the heterogeneous characteristics. Finally, in order to realize the integration of the heterogeneous data for intelligent power distribution and utilization, the well-trained discriminator model of GANs is employed to check the restored data samples. The simulation experiments verified the validity and stability of the proposed heterogeneous data integration method, which provides a novel perspective for the further data quality management of power distribution systems. Full article

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16 pages, 2332 KiB

Open AccessArticle

A Modal Solution for Finite Length Rods with Non-Uniform Area

by Andrew J. Hull

Naval Undersea Warfare Center, Newport, RI 02841, USA

Appl. Sci. 2018, 8(1), 94; https://doi.org/10.3390/app8010094 - 11 Jan 2018

Cited by 4 | Viewed by 3467

Abstract

This paper derives a modal solution to the displacement field of a finite length rod whose area varies with respect to its length. This new method facilitates a solution to any problem where the area and derivative of the area can be represented [...] Read more.

This paper derives a modal solution to the displacement field of a finite length rod whose area varies with respect to its length. This new method facilitates a solution to any problem where the area and derivative of the area can be represented as analytical functions. The problem begins by writing the longitudinal displacement of the non-uniform area rod as a series of indexed coefficients multiplied by the eigenfunctions of the uniform area rod. This series solution is inserted into the non-uniform area rod equation and multiplied by a single p-indexed eigenfunction. This equation is then integrated over the interval of the rod. Although the resultant expressions are not orthogonal, they can be written as a set of linear algebraic equations which can be solved to yield the unknown coefficients. Once these are known, the displacement of the system can be calculated. Five example problems are included: the first one has a non-uniform area that corresponds with a known analytical solution, the second has an area that can be represented by a Fourier series, the third and fourth have areas that do not have a known analytical solution and the fifth is a generic second order non-constant coefficient differential equation. Four of these problems are verified with other methods. Convergence of the series solution is discussed. It is shown that this new model is almost two orders of magnitude faster than corresponding finite element analysis. Full article

(This article belongs to the Section Acoustics and Vibrations)

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13 pages, 5901 KiB

Open AccessArticle

Poisoning Effect of SO₂ on Honeycomb Cordierite-Based Mn–Ce/Al₂O₃Catalysts for NO Reduction with NH₃ at Low Temperature

by Chengzhi Wang¹

, Cheng Zhang¹, Yonggang Zhao¹, Xin Yan² and Peng Cao^1,*

¹ Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China

² Tianfu South Thermoelectric Co., Ltd., Shihezi 832000, China

Appl. Sci. 2018, 8(1), 95; https://doi.org/10.3390/app8010095 - 11 Jan 2018

Cited by 17 | Viewed by 5453

Abstract

Honeycomb cordierite-based Mn–Ce/Al₂O₃ catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR) of NO_x with NH₃, with and without SO₂ and/or H₂O in a homemade fixed-bed tubular reactor. [...] Read more.

Honeycomb cordierite-based Mn–Ce/Al₂O₃ catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR) of NO_x with NH₃, with and without SO₂ and/or H₂O in a homemade fixed-bed tubular reactor. The catalyst reached nearly 80% NO_x conversion at 100 °C in the absence of SO₂. However, SO₂ reduces the catalytic activity (80% to 72%) of the honeycomb cordierite-based Mn–Ce/Al₂O₃ catalysts under identical conditions. This finding demonstrated that the catalyst exhibited high activity at low temperature and excellent SO₂ resistance in the presence of 50 ppm SO₂. The fresh and sulfated honeycomb cordierite-based Mn–Ce/Al₂O₃ catalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N₂ adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG-DTA), and Fourier transform infrared (FT-IR) spectroscopy. Characterization results indicated that the deactivation by SO₂ was primarily the result of the deposition of ammonium hydrogen sulfate and sulfated CeO₂ on the catalyst surface during the SCR process. The formed sulfates depressed the catalytic activity via the blocking of pores and the occupation of active sites. Additionally, the competitive adsorption between SO₂ and NH₃ always decreased the catalytic activity. Full article

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

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21 pages, 586 KiB

Open AccessArticle

Audlet Filter Banks: A Versatile Analysis/Synthesis Framework Using Auditory Frequency Scales

by Thibaud Necciari^1,*

, Nicki Holighaus¹, Peter Balazs¹

, Zdeněk Průša¹

, Piotr Majdak¹ and Olivier Derrien²

¹ Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12–14, 1040 Vienna, Austria

² Universite de Toulon, Aix-Marseille Universite, CNRS-PRISM, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France

Appl. Sci. 2018, 8(1), 96; https://doi.org/10.3390/app8010096 - 11 Jan 2018

Cited by 24 | Viewed by 7021

Abstract

Many audio applications rely on filter banks (FBs) to analyze, process, and re-synthesize sounds. For these applications, an important property of the analysis–synthesis system is the reconstruction error; it has to be minimized to avoid audible artifacts. Other advantageous properties include stability and [...] Read more.

Many audio applications rely on filter banks (FBs) to analyze, process, and re-synthesize sounds. For these applications, an important property of the analysis–synthesis system is the reconstruction error; it has to be minimized to avoid audible artifacts. Other advantageous properties include stability and low redundancy. To exploit some aspects of auditory perception in the signal chain, some applications rely on FBs that approximate the frequency analysis performed in the auditory periphery, the gammatone FB being a popular example. However, current gammatone FBs only allow partial reconstruction and stability at high redundancies. In this article, we construct an analysis–synthesis system for audio applications. The proposed system, referred to as Audlet, is an oversampled FB with filters distributed on auditory frequency scales. It allows perfect reconstruction for a wide range of FB settings (e.g., the shape and density of filters), efficient FB design, and adaptable redundancy. In particular, we show how to construct a gammatone FB with perfect reconstruction. Experiments demonstrate performance improvements of the proposed gammatone FB when compared to current gammatone FBs in terms of reconstruction error and stability, especially at low redundancies. An application of the framework to audio source separation illustrates its utility for audio processing. Full article

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

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15 pages, 6253 KiB

Open AccessArticle

Effect of Thin Cement-Based Renders on the Structural Response of Masonry Wall Panels

by Marco Corradi^*

, Romina Sisti and Antonio Borri

Department of Engineering, University of Perugia, Via Duranti 93, 06125 Perugia, Italy

Appl. Sci. 2018, 8(1), 98; https://doi.org/10.3390/app8010098 - 11 Jan 2018

Cited by 9 | Viewed by 3729

Abstract

URM (Unreinforced Masonry) historic buildings can be generally arranged into three categories: adobe, brick and stone masonry. However, a common feature of URM structures is typically the low mechanical properties of the masonry material, especially in terms of shear strength. URM buildings are [...] Read more.

URM (Unreinforced Masonry) historic buildings can be generally arranged into three categories: adobe, brick and stone masonry. However, a common feature of URM structures is typically the low mechanical properties of the masonry material, especially in terms of shear strength. URM buildings are not amenable to seismic analysis, and the relatively low strength of stone and brickwork masonry often requires expensive and invasive retrofitting intervention. Hard, intractable stones broke artificially or naturally into random shapes were often used for construction in many parts of Europe and constitute the main material of historic buildings. Thin, cement or lime-based renders are often employed to protect masonry construction, but these are frequently ignored in analysis and design. This paper shows how standard, thin, cement-based renderings can highly enhance the lateral load-capacity and shear stiffness of wall panels. An experimental campaign was carried out on-site to assess the effect of cement-based renders. In detail, compression and shear tests were conducted on twelve full-scale wall panels up to failure, and comparisons are presented to study the effect of cement-based renders on the structural behavior of stone and brickwork masonry panels. Full article

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

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11 pages, 1141 KiB

Open AccessArticle

Virtual Source Array-Based Multiple Time-Reversal Focusing

by Gihoon Byun¹, Heechun Song² and Jeasoo Kim^1,*

¹ Department of Convergence Study on the Ocean Science and Technology, Korea Maritime and Ocean University, Busan 606-791, Korea

² Scripps Institution of Oceanography, La Jolla, CA 92093-0238, USA

Appl. Sci. 2018, 8(1), 99; https://doi.org/10.3390/app8010099 - 11 Jan 2018

Cited by 4 | Viewed by 4121

Abstract

Time reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by transmitting a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of [...] Read more.

Time reversal (TR) is the process of generating a spatio-temporal focus at a probe source (PS) location by transmitting a time-reversed version of a received signal. While TR focusing requires the PS for a coherent acoustic focus at its origin, the requirement of the PS has been partially relaxed by the introduction of the concept of a virtual source array (VSA) (J. Acoust. Soc. Am. 2009, 125, 3828–3834). A VSA can serve as a remote platform or lens and redirect a focused field to a selected location beyond the VSA for which the field is assumed as a homogeneous medium with constant sound speed. The objective of this study is to extend VSA-based single TR focusing to simultaneous multiple focusing. This is achieved using the optimization theory by employing the multiple constraints method derived from a constraint matrix, which consists of appropriately synchronized transfer functions. Through numerical simulations, it is found that simultaneous multiple focusing can be achieved with distortionless response at selected multiple locations, and its performance degrades in the presence of sound speed mismatch. For achieving robust multiple focusing in the mismatch environment, singular value decomposition is applied to obtain the weight vector (i.e., backpropagation vector) that best approximates the column vectors of the constraint matrix. Numerical simulation results show that VSA-based multiple TR focusing using SVD is not a method to simultaneously focus on multiple locations, but a method of constructing a field which robustly passes through multiple locations in sound speed mismatch environment. Full article

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

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13 pages, 1875 KiB

Open AccessArticle

Calculation of Noise Barrier Insertion Loss Based on Varied Vehicle Frequencies

by Haibo Wang^1,2, Peng Luo³ and Ming Cai^1,2,*

¹ School of Engineering, Sun Yat-sen University, Guangzhou 510275, China

² Guangdong Provincial Key Laboratory of Intelligent Transportation System, Guangzhou 510275, China

³ Dongguan Geographic Information and Urban Planning Research Center, Dongguan 523129, China

Appl. Sci. 2018, 8(1), 100; https://doi.org/10.3390/app8010100 - 11 Jan 2018

Cited by 23 | Viewed by 7028

Abstract

A single frequency of 500 Hz is used as the equivalent frequency for traffic noise to calculate the approximate diffraction in current road barrier designs. However, the noise frequency changes according to the different types of vehicles moving at various speeds. The primary [...] Read more.

A single frequency of 500 Hz is used as the equivalent frequency for traffic noise to calculate the approximate diffraction in current road barrier designs. However, the noise frequency changes according to the different types of vehicles moving at various speeds. The primary objective of this study is the development of a method of calculating the insertion loss based on frequencies. First, the noise emissions of a large number of vehicles classified by speed and type were measured to obtain data the noise spectrum. The corresponding relation between vehicle type, speed, and noise frequency was obtained. Next, the impact of different frequencies on the insertion loss was analyzed and was verified to be reasonable in experiments with different propagation distances compared to the analysis of a pure 500 Hz sound. In addition, calculations were applied in a case with different traffic flows, and the effect of a road noise barrier with different types of constituents and flow speeds were analyzed. The results show that sound pressure levels behind a barrier of a heavy vehicle flow or with a high speed are notably elevated. Full article

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

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11 pages, 2945 KiB

Open AccessArticle

Reduction of T2 Relaxation Rates due to Large Volume Fractions of Magnetic Nanoparticles for All Motional Regimes

by Bashar Issa

Department of Physics, UAE University, P.O. Box 15551, Al-Ain, UAE

Appl. Sci. 2018, 8(1), 101; https://doi.org/10.3390/app8010101 - 11 Jan 2018

Cited by 4 | Viewed by 3974

Abstract

The effect of high volume fraction of magnetic nanoparticles (MNP) on Magnetic Resonance Imaging (MRI) transverse relaxation rates (R₂ = 1/T₂ and R₂* = 1/T₂*) is investigated using Monte Carlo (MC) simulations. Theoretical models [...] Read more.

The effect of high volume fraction of magnetic nanoparticles (MNP) on Magnetic Resonance Imaging (MRI) transverse relaxation rates (R₂ = 1/T₂ and R₂* = 1/T₂*) is investigated using Monte Carlo (MC) simulations. Theoretical models assume that particles occupy a small volume fraction of the sample space. Results presented in this work show that models based on both motional averaged (MAR) and static dephasing (SDR) regimes respectively underestimate and overestimate relaxation rates at large volume fractions. Furthermore, both R₂* and R₂* become echo-time dependent. This suggests that diffusion is involved with larger echo-times producing smaller relaxation rates due to better averaging of the magnetic field gradients. Findings emphasize the need for the models to be modified to take account of high particle concentration especially important for application involving clustering and trapping of nanoparticles inside cells. This is important in order to improve the design process of MNP Contrast Agents. Full article

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

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13 pages, 3997 KiB

Open AccessArticle

Surface Waves Propagating on Grounded Anisotropic Dielectric Slab

by Zhuozhu Chen^1,* and Zhongxiang Shen²

¹ School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, China

² School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

Appl. Sci. 2018, 8(1), 102; https://doi.org/10.3390/app8010102 - 11 Jan 2018

Cited by 12 | Viewed by 6741

Abstract

This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method [...] Read more.

This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM) or transverse electric (TE) mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications. Full article

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

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29 pages, 1815 KiB

Open AccessArticle

Live Convolution with Time-Varying Filters

by Øyvind Brandtsegg^1,*, Sigurd Saue¹

and Victor Lazzarini²

¹ Norwegian University of Science and Technology, 7491 Trondheim, Norway

² Department of Music, Maynooth University, Maynooth, W23 X021 Co. Kildare, Ireland

Appl. Sci. 2018, 8(1), 103; https://doi.org/10.3390/app8010103 - 12 Jan 2018

Cited by 10 | Viewed by 9674

Abstract

The paper presents two new approaches to artefact-free real-time updates of the impulse response in convolution. Both approaches are based on incremental updates of the filter. This can be useful for several applications within digital audio processing: parametrisation of convolution reverbs, dynamic filters, [...] Read more.

The paper presents two new approaches to artefact-free real-time updates of the impulse response in convolution. Both approaches are based on incremental updates of the filter. This can be useful for several applications within digital audio processing: parametrisation of convolution reverbs, dynamic filters, and live convolution. The development of these techniques has been done within the framework of a research project on crossadaptive audio processing methods for live performance. Our main motivation has thus been live convolution, where the signals from two music performers are convolved with each other, allowing the musicians to “play through each other’s sound”. Full article

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

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18 pages, 6987 KiB

Open AccessArticle

Novel Measurement Method for Determining Mass Characteristics of Pico-Satellites

by Lai Teng^*

, Hao Yang

and Zhonghe Jin

School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China

Appl. Sci. 2018, 8(1), 104; https://doi.org/10.3390/app8010104 - 15 Jan 2018

Cited by 8 | Viewed by 4631

Abstract

The centroid and moment of inertia directly affect the dynamic characteristics of aircraft, and accurate mass characteristic measurements are crucial to adequately control aircraft attitude. This paper proposes a new measurement method for determining aircraft mass characteristics that can improve measurement precision when [...] Read more.

The centroid and moment of inertia directly affect the dynamic characteristics of aircraft, and accurate mass characteristic measurements are crucial to adequately control aircraft attitude. This paper proposes a new measurement method for determining aircraft mass characteristics that can improve measurement precision when used in regard to pico-satellites. The measurement system is designed according to the principles of three-point measure and constant torque. The feasibility of the test method of this study for determining the mass characteristics is proved by using a dynamic simulation and an experimental analysis method. Through a number of standard workpiece tests, the deviation of the measurement system and effective compensation methods of the mass characteristics are obtained. The measurement system and compensation methods are applied to measure the mass characteristics of a pico-satellite, which can be detected by only one time clamping. The measurement system proposed herein can effectively improve measurement precision, as it was found that the accuracy of the centroid and the moment of inertia of the pico-satellite are less than 1 mm and 1.5 × 10⁻² kgm², respectively. The proposed measurement system also has many advantages, such as a simple operation, high efficiency, small volume, and low cost. Full article

(This article belongs to the Section Mechanical Engineering)

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19 pages, 6703 KiB

Open AccessArticle

Application of Machine Learning for the Spatial Analysis of Binaural Room Impulse Responses

by Michael Lovedee-Turner^*,†,‡

and Damian Murphy^†

¹ Communication Technologies Research Group, Department of Electronic Engineering, University of York, York YO10 5DD, UK

^† Current address: Audio Lab, Department of Electronic Engineering, University of York, York YO10 5DD, UK.

^‡ Binaural model code, neural network code, and direct sound and reflection dataset will be made available at: 10.5281/zenodo.1038021.

Appl. Sci. 2018, 8(1), 105; https://doi.org/10.3390/app8010105 - 12 Jan 2018

Cited by 11 | Viewed by 6715

Abstract

Spatial impulse response analysis techniques are commonly used in the field of acoustics, as they help to characterise the interaction of sound with an enclosed environment. This paper presents a novel approach for spatial analyses of binaural impulse responses, using a binaural model [...] Read more.

Spatial impulse response analysis techniques are commonly used in the field of acoustics, as they help to characterise the interaction of sound with an enclosed environment. This paper presents a novel approach for spatial analyses of binaural impulse responses, using a binaural model fronted neural network. The proposed method uses binaural cues utilised by the human auditory system, which are mapped by the neural network to the azimuth direction of arrival classes. A cascade-correlation neural network was trained using a multi-conditional training dataset of head-related impulse responses with added noise. The neural network is tested using a set of binaural impulse responses captured using two dummy head microphones in an anechoic chamber, with a reflective boundary positioned to produce a reflection with a known direction of arrival. Results showed that the neural network was generalisable for the direct sound of the binaural room impulse responses for both dummy head microphones. However, it was found to be less accurate at predicting the direction of arrival of the reflections. The work indicates the potential of using such an algorithm for the spatial analysis of binaural impulse responses, while indicating where the method applied needs to be made more robust for more general application. Full article

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

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8 pages, 2907 KiB

Open AccessArticle

Modeling kV X-ray-Induced Coloration in Radiochromic Films

by Mehrdad Shahmohammadi Beni¹, Dragana Krstic², Dragoslav Nikezic^1,2 and Kwan Ngok Yu^1,*

¹ Department of Physics, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China

² Faculty of Science, University of Kragujevac, Kragujevac 34000, Serbia

Appl. Sci. 2018, 8(1), 106; https://doi.org/10.3390/app8010106 - 12 Jan 2018

Cited by 4 | Viewed by 4627

Abstract

Commercially available radiochromic films are primarily designed for clinical X-ray dosimetry. These films change color upon exposures to radiation as a result of solid-state polymerization (SSP). Built on a previous model developed for SSP upon exposures to ultraviolet (UV) radiation, a new model [...] Read more.

Commercially available radiochromic films are primarily designed for clinical X-ray dosimetry. These films change color upon exposures to radiation as a result of solid-state polymerization (SSP). Built on a previous model developed for SSP upon exposures to ultraviolet (UV) radiation, a new model was developed in the present work for X-ray-induced coloration in Gafchromic EBT3 films. Monte Carlo simulations using the Monte Carlo N-Particle (MCNP) code were employed to model the transport and interaction of photons and the generated secondary electrons within the film active layer. The films were exposed to continuous-energy photon beams. The dose D_E in the external radiation detector (i.e., ionization chamber) was determined and the realistic dose D_A in the film active layer was then obtained using the calibration coefficient R (=D_A/D_E). The finite element method (FEM) was used to solve the classical steady-state Helmholtz equation using the multifrontal massively parallel sparse direct solver (MUMPS). An extensive grid independence test was carried out and the numerical stability of the present model was ensured. The reflected light intensity from the film surface was used to theoretically obtain the net reflective optical density of the film exposed to X-ray. Good agreement was obtained between the experimental and theoretical results of the net reflective optical density of the film. For X-ray doses >~600 cGy, due to the already formed densely cross-linked structure in the active layer of the EBT3 film so further bond formation was less likely, the reflected light intensity from the film surface increased at a relatively lower rate when compared to those for dose values <~600 cGy. Full article

(This article belongs to the Special Issue Radiation Effects of Materials with Laser, Ion Beam and Rays)

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12 pages, 2911 KiB

Open AccessArticle

Application of Fiber Bragg Grating Sensing Technology for Bolt Force Status Monitoring in Roadways

by Minfu Liang and Xinqiu Fang^*

Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China

Appl. Sci. 2018, 8(1), 107; https://doi.org/10.3390/app8010107 - 12 Jan 2018

Cited by 42 | Viewed by 6453

Abstract

Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM) method has poor anti-interference performance, is easily affected by harsh downhole environments, [...] Read more.

Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM) method has poor anti-interference performance, is easily affected by harsh downhole environments, and cannot support remote real-time monitoring. This paper presents a fiber Bragg grating (FBG) bolt force sensor that monitors the force of roadway bolts. This sensor uses a cantilever and a diaphragm as elastic elements and two FBGs bonded on the top and bottom surfaces of the cantilever as sensing elements. The experimental results indicate that the measuring sensitivity is improved by using the center wavelength difference between the two FBGs. The sensitivity is 38.79 pm/kN within the range from 0 to 150 kN, and the correlation coefficient reaches 99.98%. The engineering applications show that the FBG sensing technology can automatically acquire, and monitoring results are of great significance in roadway anchorage engineering safety and bolt support quality evaluation. Furthermore, such a sensor is also widely used in quasi-distributed measurement and long-term online monitoring of bolt force status in such fields as geotechnical engineering, tunnel engineering, and slope engineering. Full article

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

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10 pages, 3540 KiB

Open AccessCommunication

Flow Cell Coupled Dynamic Light Scattering for Real-Time Monitoring of Nanoparticle Size during Liquid Phase Bottom-Up Synthesis

by Nicole Meulendijks¹, Renz Van Ee¹, Ralph Stevens¹, Maurice Mourad¹, Marcel Verheijen^2,3, Nils Kambly⁴, Ricardo Armenta⁴ and Pascal Buskens^1,5,6,*

¹ The Netherlands Organisation for Applied Scientific Research (TNO), De Rondom 1, 5612 AP Eindhoven, The Netherlands

² Philips Innovation Labs, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands

³ Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands

⁴ LS Instruments AG, Passage du Cardinal 1, CH-1700 Fribourg, Switzerland

⁵ Hasselt University, Institute for Materials Research, Inorganic and Physical Chemistry, Agoralaan Building D, B-3590 Diepenbeek, Belgium

⁶ Zuyd University of Applied Sciences, Nieuw Eyckholt 300, Postbus 550, 6400 AN Heerlen, The Netherlands

Appl. Sci. 2018, 8(1), 108; https://doi.org/10.3390/app8010108 - 13 Jan 2018

Cited by 13 | Viewed by 11532

Abstract

To tailor the properties of nanoparticles and nanocomposites, precise control over particle size is of vital importance. Real-time monitoring of particle size during bottom-up synthesis in liquids would allow a detailed study of particle nucleation and growth, which provides valuable insights in the [...] Read more.

To tailor the properties of nanoparticles and nanocomposites, precise control over particle size is of vital importance. Real-time monitoring of particle size during bottom-up synthesis in liquids would allow a detailed study of particle nucleation and growth, which provides valuable insights in the mechanism of formation of the nanoparticles. Furthermore, it facilitates a rational scale-up, and would enable adequate intervention in the production process of nanoparticle dispersions to minimize the number of off-spec batches. Since real-time monitoring requires particle size measurements on dispersions in flow, conventional dynamic light scattering (DLS) techniques are not suited: they rely on single scattering and measure the Brownian motion of particles dispersed in a liquid. Here, we present a set-up that allows accurate measurements in real-time on flowing dispersions using a DLS technique based on modulated 3D cross-correlation. This technique uses two simultaneous light scattering experiments performed at the same scattering vector on the same sample volume in order to extract only the single scattering information common to both. We connected the reactor to a flow-cell in the DLS equipment using a tailor-made analysis loop, and successfully demonstrated the complete set-up through monitoring of the size of spherical silica nanoparticles during Stöber synthesis in a water-alcohol mixture starting from the molecular precursor tetraethyl orthosilicate. Full article

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

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16 pages, 6984 KiB

Open AccessArticle

Implementation of an RFID-Based Sequencing-Error-Proofing System for Automotive Manufacturing Logistics

by Yong-Shin Kang^1,*, Hyoennam Kim² and Yong-Han Lee³

¹ Department of Systems Management Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Korea

² ME Advanced Team, ME Center, GM Korea Company, 233 Bupyeong-daero, Bupyeong-gu, Incheon 21334, Korea

³ Department of Industrial and Systems Engineering, Dongguk University-Seoul, 3ga, Pil-dong, Jung-gu, Seoul 04620, Korea

Appl. Sci. 2018, 8(1), 109; https://doi.org/10.3390/app8010109 - 13 Jan 2018

Cited by 15 | Viewed by 10049

Abstract

Serialized tracing provides the ability to track and trace the lifecycle of the products and parts. Unlike barcodes, Radio frequency identification (RFID), which is an important building block for internet of things (IoT), does not require a line of sight and has the [...] Read more.

Serialized tracing provides the ability to track and trace the lifecycle of the products and parts. Unlike barcodes, Radio frequency identification (RFID), which is an important building block for internet of things (IoT), does not require a line of sight and has the advantages of recognizing many objects simultaneously and rapidly, and storing more information than barcodes. Therefore, RFID has been used in a variety of application domains such as logistics, distributions, and manufacturing, significantly improving traceability and process efficiency. In this study, we applied RFID to improve the just-in-sequence operation of an automotive inbound logistics process. First, we implemented an RFID-based visibility system for real-time traceability and control of part supply from the production lines of suppliers to the assembly line of a car manufacturer. Second, we developed an RFID-based sequence-error proofing system to avoid accidental line stops due to incorrect part sequencing. The whole system has been successfully installed in a rear-axle inbound logistics process of GM Korea. We achieved a significant amount of cost savings, especially due to the prevention of sequencing errors and part shortages, and the reduction of manual operations. Thorough cost-benefit analysis demonstrates the clear economic feasibility of using RFID technologies for the just-in-sequence inbound logistics in an automobile manufacturing environment. Full article

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17 pages, 906 KiB

Open AccessFeature PaperArticle

Effects of Order of Expansion for the Exponential Matrix and Number of Mathematical Layers in the Exact 3D Static Analysis of Functionally Graded Plates and Shells

by Salvatore Brischetto^*

and Roberto Torre

Department of Mechanical and Aerospace Engineering, Politecnico di Torino, corso Duca degli Abruzzi, 24, 10129 Torino, Italy

Appl. Sci. 2018, 8(1), 110; https://doi.org/10.3390/app8010110 - 14 Jan 2018

Cited by 10 | Viewed by 3725

Abstract

This work deals with the study of the convergence ratio of the exponential matrix method used in the 3D static analysis of functionally graded structures subjected to harmonic loads. The equilibrium equations are written in mixed orthogonal curvilinear coordinates. This feature allows plates, [...] Read more.

This work deals with the study of the convergence ratio of the exponential matrix method used in the 3D static analysis of functionally graded structures subjected to harmonic loads. The equilibrium equations are written in mixed orthogonal curvilinear coordinates. This feature allows plates, cylinders, spherical and cylindrical shells to be studied with the same and unique formulation. After a reduction to first order differential equations, the obtained system is solved through the thickness by means of the exponential matrix method. The coefficients of these equations are not constant because the mechanical properties of the considered functionally graded materials change through the thickness. Moreover, the curvature terms introduce a further dependence of the coefficients from the thickness coordinate. The use of several mathematical layers allows for evaluating both the material properties and the curvature terms at certain points through the thickness direction. The M number of mathematical layers to be introduced is here studied in combination with the N expansion order of the exponential matrix. These values are influenced by several parameters. Therefore, different geometries, thickness ratios, lamination sequences, functionally graded material laws and half-wave numbers are considered. Full article

(This article belongs to the Special Issue Functionally Graded Material (FGM) and Functionally Graded Carbon Nanotube (FG-CNT) Reinforced Composites)

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15 pages, 17748 KiB

Open AccessArticle

Desert and Sonic Ecosystems: Incorporating Environmental Factors within Site-Responsive Sonic Art

by Lauren Hayes^1,*,† and Julian Stein²

¹ Arts, Media + Engineering, Arizona State University, Tempe, AZ 85287-5802, USA

² Design Media Arts, University of California, Los Angeles, CA 90095-1456, USA

^† Current address: ASU Arts, Media + Engineering, 950 S Forest Mall, Tempe, AZ 85287, USA.

Appl. Sci. 2018, 8(1), 111; https://doi.org/10.3390/app8010111 - 14 Jan 2018

Cited by 6 | Viewed by 7042

Abstract

Advancements in embedded computer platforms have allowed data to be collected and shared between objects—or smart devices—in a network. While this has resulted in highly functional outcomes in fields such as automation and monitoring, there are also implications for artistic and expressive systems. [...] Read more.

Advancements in embedded computer platforms have allowed data to be collected and shared between objects—or smart devices—in a network. While this has resulted in highly functional outcomes in fields such as automation and monitoring, there are also implications for artistic and expressive systems. In this paper we present a pluralistic approach to incorporating environmental factors within the field of site-responsive sonic art using embedded audio and data processing techniques. In particular, we focus on the role of such systems within an ecosystemic framework, both in terms of incorporating systems of living organisms, as well as sonic interaction design. We describe the implementation of such a system within a large-scale site-responsive sonic art installation that took place in the subtropical desert climate of Arizona in 2017. Full article

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

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13 pages, 2736 KiB

Open AccessArticle

The Effect of Laser Pulse Widths on Laser—Ag Nanoparticle Interaction: Femto- to Nanosecond Lasers

by Jin-Woo Jeon¹, Sangwoo Yoon², Hae Woon Choi³, Joohan Kim^2,*, Dave Farson⁴ and Sung-Hak Cho^1,5

¹ Department of Laser & Electron Beam Application, Korea Institute of Machinery & Materials, Daejeon 34103, S. Korea

² Department of Mechanical Engineering, Seoul National University of Science and Technology, Seoul 01811, S. Korea

³ Department of Mechanical and Automotive Engineering, Keimyung University, Daegu 42601, S. Korea

⁴ Department of Material Science Engineering, the Ohio State University, Columbus, OH 43210, USA

⁵ Department of Nano-Mechatronics, Korea University of Science & Technology, Daejeon 34113, S. Korea

Appl. Sci. 2018, 8(1), 112; https://doi.org/10.3390/app8010112 - 14 Jan 2018

Cited by 69 | Viewed by 9611

Abstract

The effect of the laser pulse width on the production of nanoparticles by laser fragmentation was investigated. Laser pulse widths of 164 fs, 5 ps, 4 ns, 36 ns, 64 ns, and 100 ns were used. To assess the effect of the laser [...] Read more.

The effect of the laser pulse width on the production of nanoparticles by laser fragmentation was investigated. Laser pulse widths of 164 fs, 5 ps, 4 ns, 36 ns, 64 ns, and 100 ns were used. To assess the effect of the laser pulse width on the energy distribution in the nanoparticles, the energy distribution was simulated using wave optics. Silver (Ag) nanoparticles were produced by laser irradiation of an Ag target in distilled water. The wavelength of the femtosecond, picosecond, and nanosecond lasers used was 1070 nm, and their fluences were 0.10–0.13 mJ/cm². Nanoparticle microstructure was visualized by transmission electron microscopy and scanning electron microscopy, and the nanoparticle size distribution was evaluated using a particle size analyzer. Full article

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

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19 pages, 6598 KiB

Open AccessArticle

Analysis of Nonlinear Vibration in Permanent Magnet Synchronous Motors under Unbalanced Magnetic Pull

by Ao Zhang

, Yan Bai, Bo Yang and He Li^*

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

Appl. Sci. 2018, 8(1), 113; https://doi.org/10.3390/app8010113 - 15 Jan 2018

Cited by 37 | Viewed by 8497

Abstract

The vibration and noise of permanent magnet synchronous motors (PMSM) are mainly caused by unbalanced magnetic pull (UMP). This paper aims to investigate nonlinear vibration in PMSMs. Firstly, the analytical model of the air-gap magnetic field with an eccentric rotor in PMSM is [...] Read more.

The vibration and noise of permanent magnet synchronous motors (PMSM) are mainly caused by unbalanced magnetic pull (UMP). This paper aims to investigate nonlinear vibration in PMSMs. Firstly, the analytical model of the air-gap magnetic field with an eccentric rotor in PMSM is studied, and the analytical model is verified by the finite element method. Then the dynamic model of an offset rotor-bearing system is established, and the gyroscopic effect, nonlinear bearing force and UMP are taken into consideration. Finally, the dynamic characteristics of different static displacement eccentricities, rotor offsets and radial clearances are investigated in both the time domain and the frequency domain. The results show that the amplitudes of dynamic responses increase with the static displacement eccentricity and rotor offset and high integer multiples of rotating frequency appear with the increase of displacement eccentricity. The coupling effects of bearing force, unbalanced mass force and UMP are observed in the frequency domain, and the frequency components in the dynamic responses indicate that the bearings have an effect on the system. Full article

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10 pages, 4682 KiB

Open AccessArticle

Bio-Inspired Adhesive Footpad for Legged Robot Climbing under Reduced Gravity: Multiple Toes Facilitate Stable Attachment

by Zhongyuan Wang^1,2

, Zhouyi Wang²

, Zhendong Dai^2,*

and Stanislav N. Gorb³

¹ The 28th Research Institute of China Electronics Technology Group Corporation, Nanjing 210007, China

² Institute of Bio-inspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

³ Department Functional Morphology and Biomechanics, Zoological Institute of the University of Kiel, Kiel 24118, Germany

Appl. Sci. 2018, 8(1), 114; https://doi.org/10.3390/app8010114 - 15 Jan 2018

Cited by 20 | Viewed by 5645

Abstract

This paper presents the design of a legged robot with gecko-mimicking mechanism and mushroom-shaped adhesive microstructure (MSAMS) that can climb surfaces under reduced gravity. The design principle, adhesion performance and roles of different toes of footpad are explored and discussed in this paper. [...] Read more.

This paper presents the design of a legged robot with gecko-mimicking mechanism and mushroom-shaped adhesive microstructure (MSAMS) that can climb surfaces under reduced gravity. The design principle, adhesion performance and roles of different toes of footpad are explored and discussed in this paper. The effect of the preload velocity, peeling velocity and thickness of backing layering on the reliability of the robot are investigated. Results show that pull-force is independent of preload velocity, while the peeling force is relying on peeling velocity, and the peel strength increased with the increasing thickness of the backing layer. The climbing experiments show that the robot can climb under mimic zero gravity by using multiple toes facilitating adhesion. The robot with new type of footpads also provides a good platform for testing different adhesive materials for the future space applications. Full article

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

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21 pages, 4089 KiB

Open AccessArticle

Structural Health Monitoring and Time-Dependent Effects Analysis of Self-Anchored Suspension Bridge with Extra-Wide Concrete Girder

by Guangpan Zhou¹, Aiqun Li^1,2,*, Jianhui Li³ and Maojun Duan³

¹ School of Civil Engineering, Southeast University, No. 2 Sipailou Road, Nanjing 210096, China

² Beijing Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, No. 1 Zhanlanguan Road, Beijing 100044, China

³ School of Civil Engineering, Nanjing Forestry University, No. 159 Longpan Road, Nanjing 210037, China

Appl. Sci. 2018, 8(1), 115; https://doi.org/10.3390/app8010115 - 15 Jan 2018

Cited by 18 | Viewed by 4655

Abstract

The present work is aimed at studying the structural health status of Hunan Road Bridge, which is currently the widest concrete self-anchored suspension bridge in China. The monitoring data included the structural deformations, internal forces, and vibration characteristics from April 2015 to April [...] Read more.

The present work is aimed at studying the structural health status of Hunan Road Bridge, which is currently the widest concrete self-anchored suspension bridge in China. The monitoring data included the structural deformations, internal forces, and vibration characteristics from April 2015 to April 2016 were analyzed to evaluate the structural changes and safety. The influences brought by the ambient temperature changes and the dual effects composed of concrete shrinkage & creep (S&C) and seasonal temperature changes were analyzed based on the measured data. The long-time effects of concrete S&C were predicted using the CEB-FIP 90 model and the age-adjusted effective modulus method based on the ANSYS beam finite element model. The measured data showed that the transverse displacements of towers were more significant than the longitudinal ones. The spatial effect of the extra-wide girder is significant, which performs as the longitudinal stresses change unevenly along the transverse direction. The seasonal ambient warming caused overall increases in girder compressive stresses, and the cooling resulted in decreases along with significant temperature gradient effects. The prediction results show that the cable anchoring positions at girder ends and tower tops will move towards the mid-span affected by concrete S&C. In terms of the middle region of mid-span girder, significant increases in longitudinal stresses of top plate and decreases in the ones of bottom plate will be caused by the significant deflection. Comprehensively, the increases in the girder compressive stresses of side-span bottom plate and mid-span top plate are worthy of attention when confronted with extreme high temperature during the bridge service life cycle. Full article

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

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18 pages, 2588 KiB

Open AccessArticle

Underwater Cylindrical Object Detection Using the Spectral Features of Active Sonar Signals with Logistic Regression Models

by Yoojeong Seo^1,†, Baeksan On^1,†, Sungbin Im^1,*,†

, Taebo Shim^2,† and Iksu Seo^3,†

¹ School of Electronic Engineering, Soongsil University, Seoul 06978, Korea

² Applied Physics Laboratory, University of Washington, 1013 NE 40th St, Seattle, WA 98105, USA

³ Agency of Defences and Developments, Jinhae 51678, Korea

^† These authors contributed equally to this work.

Appl. Sci. 2018, 8(1), 116; https://doi.org/10.3390/app8010116 - 15 Jan 2018

Cited by 11 | Viewed by 7391

Abstract

The issue of detecting objects bottoming on the sea floor is significant in various fields including civilian and military areas. The objective of this study is to investigate the logistic regression model to discriminate the target from the clutter and to verify the [...] Read more.

The issue of detecting objects bottoming on the sea floor is significant in various fields including civilian and military areas. The objective of this study is to investigate the logistic regression model to discriminate the target from the clutter and to verify the possibility of applying the model trained by the simulated data generated by the mathematical model to the real experimental data because it is not easy to obtain sufficient data in the underwater field. In the first stage of this study, when the clutter signal energy is so strong that the detection of a target is difficult, the logistic regression model is employed to distinguish the strong clutter signal and the target signal. Previous studies have found that if the clutter energy is larger, false detection occurs even for the various existing detection schemes. For this reason, the discrete Fourier transform (DFT) magnitude spectrum of acoustic signals received by active sonar is applied to train the model to distinguish whether the received signal contains a target signal or not. The goodness of fit of the model is verified in terms of receiver operation characteristic (ROC), area under ROC curve (AUC), and classification table. The detection performance of the proposed model is evaluated in terms of detection rate according to target to clutter ratio (TCR). Furthermore, the real experimental data are employed to test the proposed approach. When using the experimental data to test the model, the logistic regression model is trained by the simulated data that are generated based on the mathematical model for the backscattering of the cylindrical object. The mathematical model is developed according to the size of the cylinder used in the experiment. Since the information on the experimental environment including the sound speed, the sediment type and such is not available, once simulated data are generated under various conditions, valid simulated data are selected using 70% of the experiment cylinder data. The selected simulated data are used to train the model. Randomly selected experiment cylinder data, which are 70% of the total experimental cylinder data, and the rock measurement data are used to test the model. This process is repeatedly carried out 1000 times. The results show that the proposed method is effective under the circumstance where experimental data are not sufficient and a mathematical model is available for a target. Full article

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

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8 pages, 2341 KiB

Open AccessArticle

Impact Fatigue of Viscoelastic Materials Subjected to Pounding

by Peng Zhang^1,2

, Linsheng Huo^2,*

and Gangbing Song^3,*

¹ Institute of Road and Bridge Engineering, Dalian Maritime University, Dalian 116023, China

² State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China

³ Department of Mechanical Engineering, University of Houston, Houston, TX 77004, USA

Appl. Sci. 2018, 8(1), 117; https://doi.org/10.3390/app8010117 - 15 Jan 2018

Cited by 15 | Viewed by 4603

Abstract

The pounding tuned mass damper (PTMD) is a novel vibration control device that can be used for many different structures. The PTMD utilizes a viscoelastic delimiter to enhance its vibration control effectiveness and robustness though pounding between the tuned mass and the viscoelastic [...] Read more.

The pounding tuned mass damper (PTMD) is a novel vibration control device that can be used for many different structures. The PTMD utilizes a viscoelastic delimiter to enhance its vibration control effectiveness and robustness though pounding between the tuned mass and the viscoelastic material. However, the viscoelastic material is subjected to repeated poundings during its service life, which influences the property of the material and degrades its energy dissipation ability. Therefore, this study investigates the fatigue behavior of the viscoelastic material under impact loading. An experimental apparatus, which can generate and sense the lateral impacts, is designed and fabricated to facilitate the fatigue study of the viscoelastic material subject to impact loading. Based on experimental data, the pounding stiffness and the hysteresis loops are employed to characterize the behavior of the material. It is revealed that the impact fatigue process can be divided into two phases: the cyclic-hardening phases and the cyclic-softening phase. The energy dissipation is firstly reduced, and then increased, by the repeated impacts. In summary, with a total of 360,000 impacts, the viscous elastic material is still effective in dissipating impact energy. Full article

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

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17 pages, 12694 KiB

Open AccessArticle

Development of a Self-Powered Magnetorheological Damper System for Cable Vibration Control

by Zhihao Wang^1,*, Zhengqing Chen², Hui Gao¹ and Hao Wang³

¹ School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

² Key Laboratory for Wind and Bridge Engineering of Hunan Province, Hunan University, Changsha 410082, China

³ Key Laboratory of Concrete and Prestressed Concrete Structure of Ministry of Education, Southeast University, Nanjing 210096, China

Appl. Sci. 2018, 8(1), 118; https://doi.org/10.3390/app8010118 - 15 Jan 2018

Cited by 37 | Viewed by 7816

Abstract

A new self-powered magnetorheological (MR) damper control system was developed to mitigate cable vibration. The power source of the MR damper is directly harvested from vibration energy through a rotary permanent magnet direct current (DC) generator. The generator itself can also serve as [...] Read more.

A new self-powered magnetorheological (MR) damper control system was developed to mitigate cable vibration. The power source of the MR damper is directly harvested from vibration energy through a rotary permanent magnet direct current (DC) generator. The generator itself can also serve as an electromagnetic damper. The proposed smart passive system also incorporates a roller chain and sprocket, transforming the linear motion of the cable into the rotational motion of the DC generator. The vibration mitigation performance of the presented self-powered MR damper system was evaluated by model tests with a 21.6 m long cable. A series of free vibration tests of the cable with a passively operated MR damper with constant voltage, an electromagnetic damper alone, and a self-powered MR damper system were performed. Finally, the vibration control mechanisms of the self-powered MR damper system were investigated. The experimental results indicate that the supplemental modal damping ratios of the cable in the first four modes can be significantly enhanced by the self-powered MR damper system, demonstrating the feasibility and effectiveness of the new smart passive system. The results also show that both the self-powered MR damper and the generator are quite similar to a combination of a traditional linear viscous damper and a negative stiffness device, and the negative stiffness can enhance the mitigation efficiency against cable vibration. Full article

(This article belongs to the Special Issue Development and Application of Nonlinear Dissipative Device in Structural Vibration Control)

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14 pages, 444 KiB

Open AccessArticle

A Semi-Explicit Multi-Step Method for Solving Incompressible Navier-Stokes Equations

by Pavel Ryzhakov^1,*

and Julio Marti^1,2

¹ Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE), Edifici C1 Campus Nord UPC C/ Gran Capità, S/N 08034 Barcelona, Spain

² Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya (UPC), 08034 Barcelona, Spain

Appl. Sci. 2018, 8(1), 119; https://doi.org/10.3390/app8010119 - 16 Jan 2018

Cited by 5 | Viewed by 5250

Abstract

The fractional step method is a technique that results in a computationally-efficient implementation of Navier–Stokes solvers. In the finite element-based models, it is often applied in conjunction with implicit time integration schemes. On the other hand, in the framework of finite difference and [...] Read more.

The fractional step method is a technique that results in a computationally-efficient implementation of Navier–Stokes solvers. In the finite element-based models, it is often applied in conjunction with implicit time integration schemes. On the other hand, in the framework of finite difference and finite volume methods, the fractional step method had been successfully applied to obtain predictor-corrector semi-explicit methods. In the present work, we derive a scheme based on using the fractional step technique in conjunction with explicit multi-step time integration within the framework of Galerkin-type stabilized finite element methods. We show that under certain assumptions, a Runge–Kutta scheme equipped with the fractional step leads to an efficient semi-explicit method, where the pressure Poisson equation is solved only once per time step. Thus, the computational cost of the implicit step of the scheme is minimized. The numerical example solved validates the resulting scheme and provides the insights regarding its accuracy and computational efficiency. Full article

(This article belongs to the Section Mechanical Engineering)

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12 pages, 2363 KiB

Open AccessArticle

A Distribution Power Electronic Transformer with MMC

by Gianluca Brando¹, Biagio Bova², Andrea Cervone¹, Adolfo Dannier^1,*

and Andrea Del Pizzo¹

¹ Department of Electrical Eng. and IT, DIETI, University of Naples Federico II, 80125 Naples, Italy

² GETRA Engineering & Consulting, 81025 Caserta, Italy

Appl. Sci. 2018, 8(1), 120; https://doi.org/10.3390/app8010120 - 16 Jan 2018

Cited by 5 | Viewed by 4568

Abstract

This paper deals with a Power Electronic Transformer (PET) topology for a 3-phase AC distribution grid. In the discussed topology, a Modular Multilevel Converter (MMC) and a Full-Bridge converter are employed for the medium voltage (MV) and the low voltage (LV) side, respectively. [...] Read more.

This paper deals with a Power Electronic Transformer (PET) topology for a 3-phase AC distribution grid. In the discussed topology, a Modular Multilevel Converter (MMC) and a Full-Bridge converter are employed for the medium voltage (MV) and the low voltage (LV) side, respectively. By using the space vector, approach a mathematical model for the MMC is presented and a grid-synchronous algorithm is implemented to easily control the power flow through the structure. The MV and LV side converters are linked through a High Frequency (HF) transformer, whose control strategy is a Dual-Active Phase-Shift Control (PSC) with Square Wave Modulation (SQM). This technique is combined with a predictive algorithm, which is able to keep each leg’s capacitors’ voltages balanced both in stationary and in transient conditions. The proposed algorithm is numerically validated in the Matlab/Simulink^® environment. Full article

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12 pages, 3279 KiB

Open AccessFeature PaperArticle

Electromechanical Anisotropy at the Ferroelectric to Relaxor Transition of (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ Ceramics from the Thermal Evolution of Resonance Curves

by Nicolás Pérez¹, Alvaro García², Enrique Riera³

and Lorena Pardo^2,*

¹ Instituto de Ingeniería Eléctrica, Facultad de Ingeniería, Universidad de la República, Julio Herreray Reissig 565, 11300 Montevideo, Uruguay

² Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), c/Sor Juana Inés de la Cruz, 3. Cantoblanco, 28049 Madrid, Spain

³ Instituto de Tecnologías Físicas y de la Información (ITEFI-CSIC), c/Serrano 144, 28006 Madrid, Spain

Appl. Sci. 2018, 8(1), 121; https://doi.org/10.3390/app8010121 - 16 Jan 2018

Cited by 6 | Viewed by 3769

Abstract

(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ dense ceramics were obtained from autocombustion sol-gel synthesized nanopowders and sintered at 1050 °C for 1–2 h for the study of the electromechanical anisotropy. Measurement of the complex impedance spectrum was carried out [...] Read more.

(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ dense ceramics were obtained from autocombustion sol-gel synthesized nanopowders and sintered at 1050 °C for 1–2 h for the study of the electromechanical anisotropy. Measurement of the complex impedance spectrum was carried out on thin ceramic disks, thickness-poled, as a function of the temperature from 16 °C up to the vanishing of the electromechanical resonances at the ferroelectric to relaxor transition near 100 °C. The spectrum comprises the fundamental radial extensional mode and three overtones of this, together with the fundamental thickness extensional mode, coupled with other complex modes. Thermal evolution of the spectrum shows anisotropic behavior. Piezoelectric, elastic, and dielectric material coefficients, including all losses, were determined from iterative analysis of the complex impedance curves at the planar, thickness, and shear virtually monomodal resonances of disks and shear plates, thickness-poled. d₃₃ was measured quasi-statically at 100 Hz. This set of data was used as the initial condition for the optimization of the numerical calculation by finite elements of the full spectrum of the disk, from 100 kHz to 1.9 MHz, to determine the thermal evolution of the material coefficients. An appropriate measurement strategy to study electromechanical anisotropy of piezoelectric ceramics has been developed. Full article

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

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21 pages, 7349 KiB

Open AccessArticle

Transition Analysis and Its Application to Global Path Determination for a Biped Climbing Robot

by Haifei Zhu¹

, Shichao Gu¹, Li He¹, Yisheng Guan^1,* and Hong Zhang^1,2

¹ School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China

² Department of Computing Science, University of Alberta, Edmonton, AB T6G2H1, Canada

Appl. Sci. 2018, 8(1), 122; https://doi.org/10.3390/app8010122 - 16 Jan 2018

Cited by 16 | Viewed by 6335

Abstract

Biped climbing robots are considered good assistants and (or) substitutes for human workers carrying out high-rise truss-associated routine tasks. Flexible locomotion on three-dimensional complex trusses is a fundamental skill for these robots. In particular, the capability to transit from one structural member to [...] Read more.

Biped climbing robots are considered good assistants and (or) substitutes for human workers carrying out high-rise truss-associated routine tasks. Flexible locomotion on three-dimensional complex trusses is a fundamental skill for these robots. In particular, the capability to transit from one structural member to another is paramount for switching objects to be climbed upon. In this paper, we study member-to-member transition and its utility in global path searching for biped climbing robots. To compute operational regions for transition, hierarchical inspection of safety, reachability, and accessibility of grips is taken into account. A novel global path rapid determination approach is subsequently proposed based on the transition analysis. This scheme is efficient for finding feasible routes with respect to the overall structural environment, which also benefits the subsequent grip and motion planning. Simulations are conducted with Climbot, our self-developed biped climbing robot, to verify the efficiency of the presented method. Results show that our proposed method is able to accurately determine the operational region for transition within tens of milliseconds and can obtain global paths within seconds in general. Full article

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

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23 pages, 4671 KiB

Open AccessArticle

Multiple Speech Source Separation Using Inter-Channel Correlation and Relaxed Sparsity

by Maoshen Jia^1,*,†,‡

, Jundai Sun^1,†,‡ and Xiguang Zheng²

¹ Beijing Key Laboratory of Computational Intelligence and Intelligent System, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, China

² Faculty of Engineering & Information Sciences, University of Wollongong, Wollongong NSW2522, Australia

^† Current address: Beijing University of Technology, No. 100, Pingleyuan, Chaoyang District, Beijing, China.

^‡ These authors contributed equally to this work.

Appl. Sci. 2018, 8(1), 123; https://doi.org/10.3390/app8010123 - 16 Jan 2018

Cited by 2 | Viewed by 3619

Abstract

In this work, a multiple speech source separation method using inter-channel correlation and relaxed sparsity is proposed. A B-format microphone with four spatially located channels is adopted due to the size of the microphone array to preserve the spatial parameter integrity of the [...] Read more.

In this work, a multiple speech source separation method using inter-channel correlation and relaxed sparsity is proposed. A B-format microphone with four spatially located channels is adopted due to the size of the microphone array to preserve the spatial parameter integrity of the original signal. Specifically, we firstly measure the proportion of overlapped components among multiple sources and find that there exist many overlapped time-frequency (TF) components with increasing source number. Then, considering the relaxed sparsity of speech sources, we propose a dynamic threshold-based separation approach of sparse components where the threshold is determined by the inter-channel correlation among the recording signals. After conducting a statistical analysis of the number of active sources at each TF instant, a form of relaxed sparsity called the half-K assumption is proposed so that the active source number in a certain TF bin does not exceed half the total number of simultaneously occurring sources. By applying the half-K assumption, the non-sparse components are recovered by regarding the extracted sparse components as a guide, combined with vector decomposition and matrix factorization. Eventually, the final TF coefficients of each source are recovered by the synthesis of sparse and non-sparse components. The proposed method has been evaluated using up to six simultaneous speech sources under both anechoic and reverberant conditions. Both objective and subjective evaluations validated that the perceptual quality of the separated speech by the proposed approach outperforms existing blind source separation (BSS) approaches. Besides, it is robust to different speeches whilst confirming all the separated speeches with similar perceptual quality. Full article

(This article belongs to the Section Acoustics and Vibrations)

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19 pages, 4314 KiB

Open AccessArticle

Elastic Characterization of Transparent and Opaque Films, Multilayers and Acoustic Resonators by Surface Brillouin Scattering: A Review

by Giovanni Carlotti

Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia, Italy

Appl. Sci. 2018, 8(1), 124; https://doi.org/10.3390/app8010124 - 16 Jan 2018

Cited by 34 | Viewed by 7403

Abstract

There is currently a renewed interest in the development of experimental methods to achieve the elastic characterization of thin films, multilayers and acoustic resonators operating in the GHz range of frequencies. The potentialities of surface Brillouin light scattering (surf-BLS) for this aim are [...] Read more.

There is currently a renewed interest in the development of experimental methods to achieve the elastic characterization of thin films, multilayers and acoustic resonators operating in the GHz range of frequencies. The potentialities of surface Brillouin light scattering (surf-BLS) for this aim are reviewed in this paper, addressing the various situations that may occur for the different types of structures. In particular, the experimental methodology and the amount of information that can be obtained depending on the transparency or opacity of the film material, as well as on the ratio between the film thickness and the light wavelength, are discussed. A generalization to the case of multilayered samples is also provided, together with an outlook on the capability of the recently developed micro-focused scanning version of the surf-BLS technique, which opens new opportunities for the imaging of the spatial profile of the acoustic field in acoustic resonators and in artificially patterned metamaterials, such as phononic crystals. Full article

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

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22 pages, 2194 KiB

Open AccessFeature PaperArticle

Numerical Assessment of Virtual Control Surfaces for Load Alleviation on Compressor Blades

by Valentina Motta^*

, Leonie Malzacher and Dieter Peitsch

Chair for Aero Engines, Institute of Aeronautics and Astronautics, Technische Universität Berlin, 10623 Berlin, Germany Marchstraße 12-14, 10587 Berlin, Germany

Appl. Sci. 2018, 8(1), 125; https://doi.org/10.3390/app8010125 - 17 Jan 2018

Cited by 6 | Viewed by 5528

Abstract

Virtual control surfaces for the optimization of steady and unsteady airloads on a compressor cascade are assessed numerically. The effects of mechanical surfaces are realized with plasma actuators, located both on the pressure and on the suction side of the blade trailing edge. [...] Read more.

Virtual control surfaces for the optimization of steady and unsteady airloads on a compressor cascade are assessed numerically. The effects of mechanical surfaces are realized with plasma actuators, located both on the pressure and on the suction side of the blade trailing edge. Suction side plasma actuation is thought to reproduce the effects of mechanical wing spoilers, whereas pressure side plasma actuation is meant to act as a mechanical Gurney flap. Indeed, actuators are operated to generate an induced velocity field that is opposite relative to the direction of the freestream velocity. As a consequence, controlled recirculating flow areas are generated, which modify the effective mean line shape, as well as the position of the Kutta condition application point—and in turn the developed airloads. Proper triggering of pressure/suction side actuation is found to be effective in altering the blade loading, with effects comparable to those of mechanical control surfaces. Traveling wave mode simulations show that significant reductions in the peaks of the blade pitching moment can be achieved on the whole spectrum of interblade phase angles. It is proved that virtual control surfaces can provide effective load alleviation on the cascade, with potential remarkable reduction of fatigue phenomena. Full article

(This article belongs to the Special Issue Active Flow Control Technologies for Energy and Propulsive Systems)

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14 pages, 1360 KiB

Open AccessArticle

Structural Optimization of a High-Speed Press Considering Multi-Source Uncertainties Based on a New Heterogeneous TOPSIS

by Jin Cheng¹

, Yangyan Zhang^1,2, Yixiong Feng^1,*

, Zhenyu Liu^1,* and Jianrong Tan¹

¹ State Key Laboratory of Fluid Power & Mechatronic Systems, Zhejiang University, Hangzhou 310027, China

² Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education, Harbin Institute of Technology, Harbin 150001, China

Appl. Sci. 2018, 8(1), 126; https://doi.org/10.3390/app8010126 - 17 Jan 2018

Cited by 16 | Viewed by 4281

Abstract

In order to achieve high punching precision, good operational reliability and low manufacturing cost, the structural optimization of a high-speed press in the presence of a set of available alternatives comprises a heterogeneous multiple-attribute decision-making (HMADM) problem involving deviation, fixation, cost and benefit [...] Read more.

In order to achieve high punching precision, good operational reliability and low manufacturing cost, the structural optimization of a high-speed press in the presence of a set of available alternatives comprises a heterogeneous multiple-attribute decision-making (HMADM) problem involving deviation, fixation, cost and benefit attributes that can be described in various mathematical forms due to the existence of multi-source uncertainties. Such a HMADM problem cannot be easily resolved by existing methods. To overcome this difficulty, a new heterogeneous technique for order preference by similarity to an ideal solution (HTOPSIS) is proposed. A new approach to normalization of heterogeneous attributes is proposed by integrating the possibility degree method, relative preference relation and the attribute transformation technique. Expressions for determining positive and negative ideal solutions corresponding to heterogeneous attributes are also developed. Finally, alternative structural configurations are ranked according to their relative closeness coefficients, and the optimal structural configuration can be determined. The validity and effectiveness of the proposed HTOPSIS are demonstrated by a numerical example. The proposed HTOPSIS can also be applied to structural optimization of other complex equipment, because there is no prerequisite of independency among various attributes for its application. Full article

(This article belongs to the Section Mechanical Engineering)

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15 pages, 3655 KiB

Open AccessArticle

Pore Solution pH for the Corrosion Initiation of Rebars Embedded in Concrete under a Long-Term Natural Carbonation Reaction

by Xiguang Liu^*, Ditao Niu, Xingchen Li, Yao Lv and Qiang Fu

College of Civil Engineering, Xi’an University of Architecture & Technology, 13 Yanta Road, Xi’an 710055, China

Appl. Sci. 2018, 8(1), 128; https://doi.org/10.3390/app8010128 - 17 Jan 2018

Cited by 43 | Viewed by 7609

Abstract

This paper presents an in-situ inspection and experimental investigation on the pore solution pH of concrete cover for the corrosion initiation of rebars under a long-term natural carbonation reaction. A 77-year-old steel mill was inspected, and 35 concrete column cover samples were collected [...] Read more.

This paper presents an in-situ inspection and experimental investigation on the pore solution pH of concrete cover for the corrosion initiation of rebars under a long-term natural carbonation reaction. A 77-year-old steel mill was inspected, and 35 concrete column cover samples were collected to test the pH of the pore solution and phase compositions layer by layer. The variation in pH and phase compositions of the concrete along the cover depth was studied. The in-situ inspection results indicate that the rebar embedded in concrete had begun to corrode when the carbonation depth was almost less than one-third of the cover depth. The corrosion initiation of rebars embedded in concrete can occur when the pH is between 11.3 and 12.1. The pore solution pH test results and X-ray diffraction (XRD) analysis indicated that there is a semi-carbonated zone between the fully carbonated zone and the rebar. The pH of a fully carbonated zone is in a range of 8.0–9.5, and the pH of a semi-carbonated zone is between 9.5 and 12.1. Full article

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

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24 pages, 11813 KiB

Open AccessArticle

The Study of Non-Detection Zones in Conventional Long-Distance Ultrasonic Guided Wave Inspection on Square Steel Bars

by Lei Zhang^1,2

, Yuan Yang^1,*, Xiaoyuan Wei¹ and Wenqing Yao¹

¹ School of Automation and Information Engineering, Xi’an University of Technology, Xi’an 710048, China

² School of Physics and Optoelectronic Technology, Baoji University of Arts and Sciences, Baoji 721016, China

Appl. Sci. 2018, 8(1), 129; https://doi.org/10.3390/app8010129 - 17 Jan 2018

Cited by 9 | Viewed by 4513

Abstract

In a low-frequency ultrasonic guided wave dual-probe flaw inspection of a square steel bar with a finite length boundary, the flaw reflected pulse wave cannot be identified using conventional time monitoring when the flaw is located near the reflection terminal; therefore, the conventional [...] Read more.

In a low-frequency ultrasonic guided wave dual-probe flaw inspection of a square steel bar with a finite length boundary, the flaw reflected pulse wave cannot be identified using conventional time monitoring when the flaw is located near the reflection terminal; therefore, the conventional ultrasonic echo method is not applicable and results in a non-detection zone. Using analysis and simulations of ultrasonic guided waves for the inspection of a square steel bar, the reasons for the appearance of the non-detection zone and its characteristics were analyzed and the range of the non-detection zone was estimated. Subsequently, by extending the range of the conventional detection time domain, the envelope of the specific reflected pulse signal was extracted by a combination of simulations and related envelope calculations to solve the problem of the non-detection zone in conventional inspection methods. A comparison between the simulation and the experimental results demonstrate that the solution is feasible. This study has certain practical significance for ultrasonic guided wave structural monitoring. Full article

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

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8 pages, 2576 KiB

Open AccessArticle

A Phase Change Material for Reconfigurable Circuit Applications

by Dushyant Tomer and Ronald A. Coutu^*

Department of Electrical and Computer Engineering, Marquette University, Milwaukee, WI 53233, USA

Appl. Sci. 2018, 8(1), 130; https://doi.org/10.3390/app8010130 - 18 Jan 2018

Cited by 9 | Viewed by 5187

Abstract

The large resistance contrast between amorphous and crystalline states of phase change materials (PCM) makes them a promising candidate for data-storage applications. Germanium telluride (GeTe), an early member of the PCM family, shows ~6 orders of magnitude difference in resistivity upon phase transition. [...] Read more.

The large resistance contrast between amorphous and crystalline states of phase change materials (PCM) makes them a promising candidate for data-storage applications. Germanium telluride (GeTe), an early member of the PCM family, shows ~6 orders of magnitude difference in resistivity upon phase transition. In this paper, two different heating methods, direct (Joule) and indirect thermal heating, were applied to induce a phase transition in vertical and horizontal GeTe resistors. In the electrical measurements, it was observed that thermal heating produces a two orders of magnitude larger difference in GeTe resistivity that the Joule heating, irrespective of the resistor’s geometry and orientation. It was also found that the large inter-electrode distances in horizontal resistors make them impractical for low voltage applications. In addition, a correlation in between crystallization voltage and resistor’s geometrical parameters (i.e., inter-electrode distance and cross-sectional area) was also established. Here, it was found that the threshold voltage increases with resistor length, while it remains unaffected with a change in cross-sectional area. This work provides design guidelines to make use of not only GeTe but also other phase change materials in reconfigurable circuit applications. Full article

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16 pages, 4071 KiB

Open AccessArticle

Experimental Investigation on Seismic Behavior of Steel Truss-RC Column Hybrid Structure with Steel Diagonal Braces

by Bo Wang¹, Huijuan Dai², Tao Wu¹, Guoliang Bai³ and Yongtao Bai^4,*

¹ School of Civil Engineering, Chang’an University, Xi’an 710061, China

² School of Civil Engineering, Xi’an University of Science and Technology, Xi’an 710054, China

³ School of Civil Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China

⁴ School of Civil Engineering, Chongqing University, Chongqing 400044, China

Appl. Sci. 2018, 8(1), 131; https://doi.org/10.3390/app8010131 - 18 Jan 2018

Cited by 10 | Viewed by 6909

Abstract

This paper aims to provide an experimental support on seismic performance evaluation of the steel braced truss-RC (reinforced concrete) column hybrid structure, which could be applied as the air-cooled supporting structural system in large-capacity thermal power plants located in strong earthquake prone regions. [...] Read more.

This paper aims to provide an experimental support on seismic performance evaluation of the steel braced truss-RC (reinforced concrete) column hybrid structure, which could be applied as the air-cooled supporting structural system in large-capacity thermal power plants located in strong earthquake prone regions. A series of pseudo-dynamic tests (PDTs) and quasi-static tests (QSTs) were performed on a 1/8-scaled sub-structure. The dynamic characteristics, lateral deformation patterns, deterioration behavior, hysteretic behavior and failure mechanisms were investigated. Test results showed that the first vibration mode is torsion, which is caused by the small torsional stiffness of this kind of hybrid structure. The lateral deformation shape is shear mode, and the drift ratio of the structure above the corbel is significantly less than that of the column below the corbel. Earthquake energy is mainly dissipated by the RC pipe columns where cracks mainly occurred at the bottom of column and lower part of corbel. The failure mechanisms were identified indicating that the steel braces improved the global stiffness and modified the load transfer mechanism. This study affirms that the steel braced truss-RC column hybrid structure has the sufficient ductility and good energy dissipation capacity to satisfy the design requirements in high seismic regions. Full article

(This article belongs to the Section Acoustics and Vibrations)

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16 pages, 5347 KiB

Open AccessArticle

Combined Effects of Fe₃O₄ Nanoparticles and Chemotherapeutic Agents on Prostate Cancer Cells In Vitro

by Kanako Kojima¹, Sanai Takahashi¹, Shungo Saito¹, Yoshihiro Endo¹, Tadashi Nittami¹, Tadashige Nozaki², Ranbir Chander Sobti^3,4 and Masatoshi Watanabe^1,5,*

¹ Laboratory for Medical Engineering, Division of Materials Science and Chemical Engineering, Graduate School of Engineering, Yokohama National University, Yokohama Kanagawa 240-8501, Japan

² Department of Pharmacology, Faculty of Dentistry, Osaka Dental University, Hirakata, Osaka 573-1121, Japan

³ Department of Biotechnology, Panjab University, Chandigarh 160014, India

⁴ Vice Chancellor BBA (Central) University, Lucknow 226027, India

⁵ Department of Oncologic Pathology, Graduate School of Medicine, Mie University, Tsu, Mie 514-8507, Japan

Appl. Sci. 2018, 8(1), 134; https://doi.org/10.3390/app8010134 - 18 Jan 2018

Cited by 18 | Viewed by 6485

Abstract

Patients with metastatic castration-resistant prostate cancer (mCRPC) have poor outcomes. Docetaxel (DTX)-based therapy is a current standard treatment for patients with mCRPC. Approaches combining conventional chemotherapeutic agents and nanoparticles (NPs), particularly iron oxide NPs, may overcome the serious side effects and drug resistance, [...] Read more.

Patients with metastatic castration-resistant prostate cancer (mCRPC) have poor outcomes. Docetaxel (DTX)-based therapy is a current standard treatment for patients with mCRPC. Approaches combining conventional chemotherapeutic agents and nanoparticles (NPs), particularly iron oxide NPs, may overcome the serious side effects and drug resistance, resulting in the establishment of new therapeutic strategies. We previously reported the combined effects of Fe₃O₄ nanoparticles (Fe₃O₄ NPs) with DTX on prostate cancer cells in vitro. In this study, we investigated the combined effects of Fe₃O₄ NPs and rapamycin or carboplatin on prostate cancer cells in vitro. Treatment of DU145 and PC-3 cells with Fe₃O₄ NPs increased intracellular reactive oxygen species (ROS) levels in a concentration-dependent manner. Treatment of both cell lines with 100 μg/mL Fe₃O₄ NPs for 72 h resulted in significant inhibition of cell viability with a different inhibitory effect. Combination treatments with 100 µg/mL Fe₃O₄ NPs and 10 µM carboplatin or 10 nM rapamycin in DU145 and PC-3 cells significantly decreased cell viability. Synergistic effects on apoptosis were observed in PC-3 cells treated with Fe₃O₄ NPs and rapamycin and in DU145 cells with Fe₃O₄ NPs and carboplatin. These results suggest the possibility of combination therapy with Fe₃O₄ NPs and various chemotherapeutic agents as a novel therapeutic strategy for patients with mCRPC. Full article

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

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21 pages, 2858 KiB

Open AccessArticle

Analyzing Free-Hand Sound-Tracings of Melodic Phrases

by Tejaswinee Kelkar^*

and Alexander Refsum Jensenius

University of Oslo, Department of Musicology, RITMO Centre for Interdisciplinary Studies in Rhythm, Time and Motion, 0371 Oslo, Norway

Appl. Sci. 2018, 8(1), 135; https://doi.org/10.3390/app8010135 - 18 Jan 2018

Cited by 21 | Viewed by 10198

Abstract

In this paper, we report on a free-hand motion capture study in which 32 participants ‘traced’ 16 melodic vocal phrases with their hands in the air in two experimental conditions. Melodic contours are often thought of as correlated with vertical movement (up and [...] Read more.

In this paper, we report on a free-hand motion capture study in which 32 participants ‘traced’ 16 melodic vocal phrases with their hands in the air in two experimental conditions. Melodic contours are often thought of as correlated with vertical movement (up and down) in time, and this was also our initial expectation. We did find an arch shape for most of the tracings, although this did not correspond directly to the melodic contours. Furthermore, representation of pitch in the vertical dimension was but one of a diverse range of movement strategies used to trace the melodies. Six different mapping strategies were observed, and these strategies have been quantified and statistically tested. The conclusion is that metaphorical representation is much more common than a ‘graph-like’ rendering for such a melodic sound-tracing task. Other findings include a clear gender difference for some of the tracing strategies and an unexpected representation of melodies in terms of a small object for some of the Hindustani music examples. The data also show a tendency of participants moving within a shared ‘social box’. Full article

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

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21 pages, 5453 KiB

Open AccessArticle

Pareto Optimal Solutions for Network Defense Strategy Selection Simulator in Multi-Objective Reinforcement Learning

by Yang Sun¹

, Yun Li^2,*, Wei Xiong¹, Zhonghua Yao¹, Krishna Moniz³ and Ahmed Zahir⁴

¹ Science and Technology on Complex Electronic System Simulation Laboratory, Space Engineering University, Beijing 101400, China

² Network Management Center, CAPF, Beijing 100089, China

³ College of Humanities and Sciences, University of Montana, 32 Campus Dr, Missoula, MT 59812, USA

⁴ Centre for Instructional Design and Technology, Open University Malaysia, Jalan Tun Ismail, 50480 Kuala Lumpur, Malaysia

Appl. Sci. 2018, 8(1), 136; https://doi.org/10.3390/app8010136 - 18 Jan 2018

Cited by 10 | Viewed by 6393

Abstract

Using Pareto optimization in Multi-Objective Reinforcement Learning (MORL) leads to better learning results for network defense games. This is particularly useful for network security agents, who must often balance several goals when choosing what action to take in defense of a network. If [...] Read more.

Using Pareto optimization in Multi-Objective Reinforcement Learning (MORL) leads to better learning results for network defense games. This is particularly useful for network security agents, who must often balance several goals when choosing what action to take in defense of a network. If the defender knows his preferred reward distribution, the advantages of Pareto optimization can be retained by using a scalarization algorithm prior to the implementation of the MORL. In this paper, we simulate a network defense scenario by creating a multi-objective zero-sum game and using Pareto optimization and MORL to determine optimal solutions and compare those solutions to different scalarization approaches. We build a Pareto Defense Strategy Selection Simulator (PDSSS) system for assisting network administrators on decision-making, specifically, on defense strategy selection, and the experiment results show that the Satisficing Trade-Off Method (STOM) scalarization approach performs better than linear scalarization or GUESS method. The results of this paper can aid network security agents attempting to find an optimal defense policy for network security games. Full article

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9 pages, 4262 KiB

Open AccessArticle

A 25.78-Gbit/s × 4-ch Active Optical Cable with Ultra-Compact Form Factor for High-Density Optical Interconnects

by Naohiro Kohmu^*

, Toshiaki Takai, Norio Chujo and Hideo Arimoto

Hitachi, Ltd. Research & Development Group; Tokyo 185-8601, Japan

Appl. Sci. 2018, 8(1), 137; https://doi.org/10.3390/app8010137 - 18 Jan 2018

Cited by 7 | Viewed by 5830

Abstract

A 25.78-Gbit/s × 4-ch active optical cable (AOC) with an ultra-compact form factor is proposed. The size of the proposed AOC is 5.2 cm³, which is 55% smaller than the standard form factor of Quad Small Form-factor Pluggable (QSFP28), and 45% [...] Read more.

A 25.78-Gbit/s × 4-ch active optical cable (AOC) with an ultra-compact form factor is proposed. The size of the proposed AOC is 5.2 cm³, which is 55% smaller than the standard form factor of Quad Small Form-factor Pluggable (QSFP28), and 45% smaller than that of Micro Quad Small Form-factor Pluggable (μQSFP). As a result of utilizing a high-efficiency heat-dissipation structure and optimizing signal transmission lines and ground vias, the proposed AOC achieves high-heat dissipation and low-crosstalk characteristics. Furthermore, the proposed AOC demonstrated 25.78-Gbit/s error-free optical transmission over a 100-m Optical Multimode 3 (OM3) multimode fiber under all-channels (4-ch) operation and case temperature (T_c) of 70 °C. Full article

(This article belongs to the Special Issue Optical Interconnects)

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16 pages, 4773 KiB

Open AccessArticle

Computational Modelling of Rectangular Sub-Boundary Layer Vortex Generators

by Unai Fernandez-Gamiz^1,*

, Iñigo Errasti¹

, Ruben Gutierrez-Amo¹, Ana Boyano² and Oscar Barambones³

¹ Nuclear Engineering and Fluid Mechanics Department, University of the Basque Country, Nieves Cano 12, 01006 Vitoria-Gasteiz, Araba, Spain

² Department of Mechanical Engineering, University of the Basque Country (UPV/EHU), Nieves Cano 12, 01006 Vitoria-Gasteiz, Spain

³ Automatic control and System Engineering Department, University of the Basque Country, Nieves Cano 12, 01006 Vitoria-Gasteiz, Araba, Spain

Appl. Sci. 2018, 8(1), 138; https://doi.org/10.3390/app8010138 - 19 Jan 2018

Cited by 33 | Viewed by 5601

Abstract

Vortex generators (VGs) are increasingly used in the wind turbine manufacture industry as flow control devices to improve rotor blade aerodynamic performance. Nevertheless, VGs may produce excess residual drag in some applications. The so-called sub-boundary layer VGs can provide an effective flow-separation control [...] Read more.

Vortex generators (VGs) are increasingly used in the wind turbine manufacture industry as flow control devices to improve rotor blade aerodynamic performance. Nevertheless, VGs may produce excess residual drag in some applications. The so-called sub-boundary layer VGs can provide an effective flow-separation control with lower drag than the conventional VGs. The main objective of this study is to investigate how well the simulations can reproduce the physics of the flow of the primary vortex generated by rectangular sub-boundary layer VGs mounted on a flat plate with a negligible pressure gradient with an angle of attack of the vane to the oncoming flow of β = 18°. Three devices with aspect ratio values of 2, 2.5 and 3 are qualitatively and quantitatively compared. To that end, computational simulations have been carried out using the RANS (Reynolds averaged Navier–Stokes) method and at Reynolds number Re = 2600 based on the boundary layer momentum thickness θ at the VG position. The computational results show good agreement with the experimental data provided by the Advanced Aerodynamic Tools of Large Rotors (AVATAR) European project for the development and validation of aerodynamic models. Finally, the results indicate that the highest VG seems to be more suitable for separation control applications. Full article

(This article belongs to the Special Issue Active Flow Control Technologies for Energy and Propulsive Systems)

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15 pages, 2538 KiB

Open AccessArticle

Motion Planning for Bipedal Robot to Perform Jump Maneuver

by Xinyang Jiang¹, Xuechao Chen^1,2,*, Zhangguo Yu^1,3, Weimin Zhang^1,3, Libo Meng¹

and Qiang Huang^1,2

¹ Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China

² Key Laboratory of Biomimetic Robots and Systems, Ministry of Education, Beijing 100081, China

³ Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing 100081, China

Appl. Sci. 2018, 8(1), 139; https://doi.org/10.3390/app8010139 - 19 Jan 2018

Cited by 13 | Viewed by 9695

Abstract

The remarkable ability of humans to perform jump maneuvers greatly contributes to the improvements of the obstacle negotiation ability of humans. The paper proposes a jumping control scheme for a bipedal robot to perform a high jump. The half-body of the robot is [...] Read more.

The remarkable ability of humans to perform jump maneuvers greatly contributes to the improvements of the obstacle negotiation ability of humans. The paper proposes a jumping control scheme for a bipedal robot to perform a high jump. The half-body of the robot is modeled as three planar links and the motion during the launching phase is taken into account. A geometrically simple motion was first conducted through which the gear reduction ratio that matches the maximum motor output for high jumping was selected. Then, the following strategies to further exploit the motor output performance was examined: (1) to set the maximum torque of each joint as the baseline that is explicitly modeled as a piecewise linear function dependent on the joint angular velocity; (2) to exert it with a correction of the joint angular accelerations in order to satisfy some balancing criteria during the motion. The criteria include the location of ZMP (zero moment point) and the torque limit. Using the technique described above, the jumping pattern is pre-calculated to maximize the jump height. Finally, the effectiveness of the proposed method is evaluated through simulations. In the simulation, the bipedal robot model achieved a 0.477-m high jump. Full article

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

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18 pages, 8397 KiB

Open AccessArticle

Agile Attitude Control and Singularity Avoidance/Escape by the SDRE Method Using a Biased State-Dependent Weighting Matrix

by Ryotaro Ozawa^1,*

and Masaki Takahashi²

¹ School of Science for Open and Environmental Systems, Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

² Department of System Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

Appl. Sci. 2018, 8(1), 140; https://doi.org/10.3390/app8010140 - 19 Jan 2018

Cited by 4 | Viewed by 5538

Abstract

In recent years there has been an increasing need to improve satellite attitude control performance in terms of agility and attitude accuracy in large-angle attitude maneuvers. To achieve such control performance, single-gimbal control moment gyros (SGCMGs) should be mounted as modern-type actuators. Conventionally, [...] Read more.

In recent years there has been an increasing need to improve satellite attitude control performance in terms of agility and attitude accuracy in large-angle attitude maneuvers. To achieve such control performance, single-gimbal control moment gyros (SGCMGs) should be mounted as modern-type actuators. Conventionally, based on the torque command calculated by the attitude control system of the satellite, SGCMGs were controlled by solving inverse kinematics through a pseudo inverse matrix steering law. However, in such a control system structure, it may be difficult to obtain the desired torque required by the attitude control system because of the singularity problem of SGCMGs. Furthermore, with respect to implementation, since the condition number of the Jacobian matrix of SGCMG becomes extremely large in the singularity, the numerical calculation error of the pseudo inverse matrix increases greatly. Therefore, we propose an overall control system that can solve above-described problems and the state-dependent Riccati equation (SDRE) control system that integrates the satellite and SGCMG system. The proposed optimal control system, which does not solve the pseudo inverse matrix, can realize gimbal angle guidance by gimbal angle feedback and singularity avoidance/escape using the biased weighting matrix. In the numerical simulation, the usefulness of proposed system is shown in comparison with the conventional system. Full article

(This article belongs to the Section Mechanical Engineering)

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24 pages, 3209 KiB

Open AccessArticle

Hierarchical Colored Petri Nets for Modeling and Analysis of Transit Signal Priority Control Systems

by Yisheng An^1,*

, Naiqi Wu²

, Xiangmo Zhao¹, Xuan Li¹ and Pei Chen¹

¹ School of Information Engineering, Chang’an University, Xi’an 710064, China

² Institute of Systems Engineering, Macau University of Science and Technology, Taipa 999078, Macau

Appl. Sci. 2018, 8(1), 141; https://doi.org/10.3390/app8010141 - 19 Jan 2018

Cited by 14 | Viewed by 7075

Abstract

In this paper, we consider the problem of developing a model for traffic signal control with transit priority using Hierarchical Colored Petri nets (HCPN). Petri nets (PN) are useful for state analysis of discrete event systems due to their powerful modeling capability and [...] Read more.

In this paper, we consider the problem of developing a model for traffic signal control with transit priority using Hierarchical Colored Petri nets (HCPN). Petri nets (PN) are useful for state analysis of discrete event systems due to their powerful modeling capability and mathematical formalism. This paper focuses on their use to formalize the transit signal priority (TSP) control model. In a four-phase traffic signal control model, the transit detection and two kinds of transit priority strategies are integrated to obtain the HCPN-based TSP control models. One of the advantages to use these models is the clear presentation of traffic light behaviors in terms of conditions and events that cause the detection of a priority request by a transit vehicle. Another advantage of the resulting models is that the correctness and reliability of the proposed strategies are easily analyzed. After their full reachable states are generated, the boundness, liveness, and fairness of the proposed models are verified. Experimental results show that the proposed control model provides transit vehicles with better effectiveness at intersections. This work helps advance the state of the art in the design of signal control models related to the intersection of roadways. Full article

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9 pages, 4466 KiB

Open AccessArticle

Variability of Hydroacoustic Noise Probability Density Function at the Output of Automatic Gain Control System

by Sergey Gorovoy^*

, Alexey Kiryanov and Evgeniy Zheldak

Department of Instrument Engineering, Far Eastern Federal University, 690650 Vladivostk, Russia

Appl. Sci. 2018, 8(1), 142; https://doi.org/10.3390/app8010142 - 20 Jan 2018

Cited by 3 | Viewed by 4680

Abstract

This research presents results of the estimation of temporal variability of the hydroacoustic noise probability density function (PDF) in shallow waters within the frequency band of 0.03–3.3 kHz; the studies were conducted near the Primorsky Aquarium on Russky Island, Vladivostok, Russia. Signals were [...] Read more.

This research presents results of the estimation of temporal variability of the hydroacoustic noise probability density function (PDF) in shallow waters within the frequency band of 0.03–3.3 kHz; the studies were conducted near the Primorsky Aquarium on Russky Island, Vladivostok, Russia. Signals were received via unidirectional hydrophone and automatic gain control of the received signals. The hydrophone was attached to a drifting buoy via an elastic suspension; the received signals were transmitted by cable to a boat drifting with the buoy. The results of the comparison of the sea noise probability density function (PDF) estimates at the output of a system with automatic gain control (AGC) with similar results for a white Gaussian noise in the same frequency band are described. Full article

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

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10 pages, 1918 KiB

Open AccessFeature PaperArticle

Manipulating Propagation Constants of Silver Nanowire Plasmonic Waveguide Modes Using a Dielectric Multilayer Substrate

by Yifeng Xiang^1,†, Junxue Chen^2,†, Douguo Zhang^1,*, Ruxue Wang¹, Yan Kuai¹, Fengya Lu¹, Xi Tang¹, Pei Wang¹, Hai Ming¹, Mary Rosenfeld³, Ramachandram Badugu³ and Joseph R. Lakowicz³

¹ Department of Optics and Optical Engineering, Institute of Photonics, University of Science and Technology of China, Hefei 230026, Anhui, China

² School of Science, Southwest University of Science and Technology, Mianyang 621010, Sichuan, China

³ Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA

^† This authors contribute equally to this work.

Appl. Sci. 2018, 8(1), 144; https://doi.org/10.3390/app8010144 - 22 Jan 2018

Cited by 11 | Viewed by 6104

Abstract

Experiments and numerical simulations demonstrate that when a silver nanowire is placed on a dielectric multilayer, but not the commonly used bare glass slide, the effective refractive index of the propagating surface plasmons along the silver nanowire can be controlled. Furthermore, by increasing [...] Read more.

Experiments and numerical simulations demonstrate that when a silver nanowire is placed on a dielectric multilayer, but not the commonly used bare glass slide, the effective refractive index of the propagating surface plasmons along the silver nanowire can be controlled. Furthermore, by increasing the thickness of the top dielectric layer, longer wavelength light can also propagate along a very thin silver nanowire. In the experiment, the diameter of the silver nanowire could be as thin as 70 nm, with the incident wavelength as long as 640 nm. The principle of this control is analysed from the existence of a photonic band gap and the Bloch surface wave with this dielectric multilayer substrate. Full article

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

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18 pages, 9181 KiB

Open AccessArticle

Maximum Power Point Tracking Implementation by Dspace Controller Integrated Through Z-Source Inverter Using Particle Swarm Optimization Technique for Photovoltaic Applications

by Kalaiarasi N.^1,*

, Subranshu Sekhar Dash¹, Sanjeevikumar Padmanaban^2,*

, Paramasivam S.³ and Pandav Kiran Morati⁴

¹ Department of Electrical and Electronics Engineering, SRM University, Chennai 603203, India

² Department of Energy Technology, Aalborg University, Esbjerg 6700, Denmark

³ Danfoss Industries Ltd., Chennai 600001, India

⁴ Department of Electrical and Electronics Engineering Science, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa

Appl. Sci. 2018, 8(1), 145; https://doi.org/10.3390/app8010145 - 22 Jan 2018

Cited by 25 | Viewed by 6342

Abstract

Maximum Power Point Tracking (MPPT) technique is used to extract maximum power from the photovoltaic system. This paper involves working on an enhanced Particle Swarm Optimization (PSO) based MPPT method for the photovoltaic (PV) system integrated through Z-Source inverter. The main benefit of [...] Read more.

Maximum Power Point Tracking (MPPT) technique is used to extract maximum power from the photovoltaic system. This paper involves working on an enhanced Particle Swarm Optimization (PSO) based MPPT method for the photovoltaic (PV) system integrated through Z-Source inverter. The main benefit of the proposed method is the diminishing of the steady-state oscillation when the maximum power point (MPP) is located. Additionally, during an extreme environmental condition, such as partial shading and large fluctuations of irradiance and temperature, the proposed method has the capability to track the MPP. This algorithm is implemented in dspace 1104 controller. MATLAB simulations are carried out under varying irradiance and temperature conditions to evaluate its effectiveness. Its performance is compared with a conventional method like Perturb and observe (P&O) method. Full article

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

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14 pages, 4658 KiB

Open AccessArticle

Research on Model-Based Fault Diagnosis for a Gas Turbine Based on Transient Performance

by Detang Zeng^1,2,*, Dengji Zhou^3,4,*, Chunqing Tan^1,2 and Baoyang Jiang⁴

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

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

³ The Key Laboratory of Power Machinery and Engineering of Education Ministry, Shanghai Jiao Tong University, Shanghai 200240, China

⁴ Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA

Appl. Sci. 2018, 8(1), 148; https://doi.org/10.3390/app8010148 - 22 Jan 2018

Cited by 16 | Viewed by 6205

Abstract

It is essential to monitor and to diagnose faults in rotating machinery with a high thrust–weight ratio and complex structure for a variety of industrial applications, for which reliable signal measurements are required. However, the measured values consist of the true values of [...] Read more.

It is essential to monitor and to diagnose faults in rotating machinery with a high thrust–weight ratio and complex structure for a variety of industrial applications, for which reliable signal measurements are required. However, the measured values consist of the true values of the parameters, the inertia of measurements, random errors and systematic errors. Such signals cannot reflect the true performance state and the health state of rotating machinery accurately. High-quality, steady-state measurements are necessary for most current diagnostic methods. Unfortunately, it is hard to obtain these kinds of measurements for most rotating machinery. Diagnosis based on transient performance is a useful tool that can potentially solve this problem. A model-based fault diagnosis method for gas turbines based on transient performance is proposed in this paper. The fault diagnosis consists of a dynamic simulation model, a diagnostic scheme, and an optimization algorithm. A high-accuracy, nonlinear, dynamic gas turbine model using a modular modeling method is presented that involves thermophysical properties, a component characteristic chart, and system inertial. The startup process is simulated using this model. The consistency between the simulation results and the field operation data shows the validity of the model and the advantages of transient accumulated deviation. In addition, a diagnostic scheme is designed to fulfill this process. Finally, cuckoo search is selected to solve the optimization problem in fault diagnosis. Comparative diagnostic results for a gas turbine before and after washing indicate the improved effectiveness and accuracy of the proposed method of using data from transient processes, compared with traditional methods using data from the steady state. Full article

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

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12 pages, 775 KiB

Open AccessArticle

Real-Time Reduction of Task-Related Scalp-Hemodynamics Artifact in Functional Near-Infrared Spectroscopy with Sliding-Window Analysis

by Yuta Oda^*, Takanori Sato, Isao Nambu

and Yasuhiro Wada

Department of Electrical, Electronics and Information Engineering, Nagaoka University of Technology, 1603-1, Kamitomioka Nagaoka, Niigata 940-2188, Japan

Appl. Sci. 2018, 8(1), 149; https://doi.org/10.3390/app8010149 - 22 Jan 2018

Cited by 6 | Viewed by 5645

Abstract

Functional near-infrared spectroscopy (fNIRS) is an effective non-invasive neuroimaging technique for measuring hemoglobin concentration in the cerebral cortex. Owing to the nature of fNIRS measurement principles, measured signals can be contaminated with task-related scalp blood flow (SBF), which is distributed over the whole [...] Read more.

Functional near-infrared spectroscopy (fNIRS) is an effective non-invasive neuroimaging technique for measuring hemoglobin concentration in the cerebral cortex. Owing to the nature of fNIRS measurement principles, measured signals can be contaminated with task-related scalp blood flow (SBF), which is distributed over the whole head and masks true brain activity. Aiming for fNIRS-based real-time application, we proposed a real-time task-related SBF artifact reduction method. Using a principal component analysis, we estimated a global temporal pattern of SBF from few short-channels, then we applied a general linear model for removing it from long-channels that were possibly contaminated by SBF. Sliding-window analysis was applied for both signal steps for real-time processing. To assess the performance, a semi-real simulation was executed with measured short-channel signals in a motor-task experiment. Compared with conventional techniques with no elements of SBF, the proposed method showed significantly higher estimation performance for true brain activation under a task-related SBF artifact environment. Full article

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14 pages, 14998 KiB

Open AccessFeature PaperArticle

SampleCNN: End-to-End Deep Convolutional Neural Networks Using Very Small Filters for Music Classification

by Jongpil Lee

, Jiyoung Park, Keunhyoung Luke Kim and Juhan Nam^*

Graduate School of Culture Technology, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea

Appl. Sci. 2018, 8(1), 150; https://doi.org/10.3390/app8010150 - 22 Jan 2018

Cited by 133 | Viewed by 16296

Abstract

Convolutional Neural Networks (CNN) have been applied to diverse machine learning tasks for different modalities of raw data in an end-to-end fashion. In the audio domain, a raw waveform-based approach has been explored to directly learn hierarchical characteristics of audio. However, the majority [...] Read more.

Convolutional Neural Networks (CNN) have been applied to diverse machine learning tasks for different modalities of raw data in an end-to-end fashion. In the audio domain, a raw waveform-based approach has been explored to directly learn hierarchical characteristics of audio. However, the majority of previous studies have limited their model capacity by taking a frame-level structure similar to short-time Fourier transforms. We previously proposed a CNN architecture which learns representations using sample-level filters beyond typical frame-level input representations. The architecture showed comparable performance to the spectrogram-based CNN model in music auto-tagging. In this paper, we extend the previous work in three ways. First, considering the sample-level model requires much longer training time, we progressively downsample the input signals and examine how it affects the performance. Second, we extend the model using multi-level and multi-scale feature aggregation technique and subsequently conduct transfer learning for several music classification tasks. Finally, we visualize filters learned by the sample-level CNN in each layer to identify hierarchically learned features and show that they are sensitive to log-scaled frequency. Full article

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

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19 pages, 964 KiB

Open AccessFeature PaperReview

Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

by Brett Hallam^1,*,†, Axel Herguth^2,†

, Phillip Hamer^1,3, Nitin Nampalli^1,4, Svenja Wilking², Malcolm Abbott¹, Stuart Wenham¹ and Giso Hahn²

¹ School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052, Australia

² Department of Physics, University of Konstanz, Universitätsstr. 10, 78457 Konstanz, Germany

³ Now with Department of Materials, University of Oxford, 16 Parks Rd, Oxford OX1 3PH, UK

⁴ Now with Department of Electronics and Nanoengineering, Aalto University, Tiototie 3, 02150 Espoo, Finland

^† These authors contributed equally to this manuscript.

Appl. Sci. 2018, 8(1), 10; https://doi.org/10.3390/app8010010 - 22 Dec 2017

Cited by 72 | Viewed by 11637

Abstract

This paper discusses developments in the mitigation of light-induced degradation caused by boron-oxygen defects in boron-doped Czochralski grown silicon. Particular attention is paid to the fabrication of industrial silicon solar cells with treatments for sensitive materials using illuminated annealing. It highlights the importance [...] Read more.

This paper discusses developments in the mitigation of light-induced degradation caused by boron-oxygen defects in boron-doped Czochralski grown silicon. Particular attention is paid to the fabrication of industrial silicon solar cells with treatments for sensitive materials using illuminated annealing. It highlights the importance and desirability of using hydrogen-containing dielectric layers and a subsequent firing process to inject hydrogen throughout the bulk of the silicon solar cell and subsequent illuminated annealing processes for the formation of the boron-oxygen defects and simultaneously manipulate the charge states of hydrogen to enable defect passivation. For the photovoltaic industry with a current capacity of approximately 100 GW peak, the mitigation of boron-oxygen related light-induced degradation is a necessity to use cost-effective B-doped silicon while benefitting from the high-efficiency potential of new solar cell concepts. Full article

(This article belongs to the Special Issue Next Generation Photovoltaic Solar Cells)

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47 pages, 5709 KiB

Open AccessReview

Room Response Equalization—A Review

by Stefania Cecchi^1,*

, Alberto Carini²

and Sascha Spors³

¹ Department of Information Engineering, Università Politecnica delle Marche, 60121 Ancona, Italy

² Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy

³ Institute of Communications Engineering, University of Rostock, 18011 Rostock, Germany

Appl. Sci. 2018, 8(1), 16; https://doi.org/10.3390/app8010016 - 23 Dec 2017

Cited by 85 | Viewed by 14720

Abstract

Room response equalization aims at improving the sound reproduction in rooms by applying advanced digital signal processing techniques to design an equalizer on the basis of one or more measurements of the room response. This topic has been intensively studied in the last [...] Read more.

Room response equalization aims at improving the sound reproduction in rooms by applying advanced digital signal processing techniques to design an equalizer on the basis of one or more measurements of the room response. This topic has been intensively studied in the last 40 years, resulting in a number of effective techniques facing different aspects of the problem. This review paper aims at giving an overview of the existing methods following their historical evolution, and discussing pros and cons of each approach with relation to the room characteristics, as well as instrumental and perceptual measures. The review is concluded by a discussion on emerging topics and new trends. Full article

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

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16 pages, 7719 KiB

Open AccessFeature PaperReview

Review and Perspectives of Aurivillius Structures as a Lead-Free Piezoelectric System

by Alberto Moure

Instituto de Cerámica y Vidrio, CSS Group (Electroceramic Department), Consejo Superior de Investigaciones Científicas (CSIC), C/Kelsen, 5 28049 Madrid, Spain

Appl. Sci. 2018, 8(1), 62; https://doi.org/10.3390/app8010062 - 3 Jan 2018

Cited by 117 | Viewed by 9028

Abstract

According to the EU-Directives 2002/95/EC, 2002/96/EC, lead-based piezoceramics must be substituted in the future with more environmentally friendly alternatives, only when a reliable alternative is found. This is why an increasing interest has grown in the research community to find lead free piezoelectric [...] Read more.

According to the EU-Directives 2002/95/EC, 2002/96/EC, lead-based piezoceramics must be substituted in the future with more environmentally friendly alternatives, only when a reliable alternative is found. This is why an increasing interest has grown in the research community to find lead free piezoelectric materials that fulfil the requirements for this substitution. Different families of compounds have been shown to be possible candidates for this use, such as bismuth and niobates based perovskites, pyrochlores, etc. However, a material with piezoelectric coefficients similar to those of PZT (lead zirconate titanate, Pb[Zr_xTi_1-x]O₃) has not been yet found. Besides, each of these families has its specific characteristics in terms of remnant polarization, coercive field or application temperature. Thus, the choice of each material should be made according to the specific needs of the application. In this sense, Aurivillius-type structure materials (also known as Bismuth Layered Structure Ferroelectrics, BLSF) can take advantage of their specific properties for uses as Lead Free Piezoelectric systems. Some of them have a high Curie temperature, which make them good candidates to be used as high temperature piezoelectrics; high coercive fields, which facilitates their use as actuators; or a high switching fatigue resistance, which can be useful for future applications as Ferroelectric Random Access Memories (FERAM). Full article

(This article belongs to the Special Issue A Perspective on the Design of Lead-Free Piezoceramics)

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16 pages, 4593 KiB

Open AccessReview

Multimodal Magnetic-Plasmonic Nanoparticles for Biomedical Applications

by Shelley Stafford

, Raquel Serrano Garcia and Yurii K. Gun’ko^*

School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland

Appl. Sci. 2018, 8(1), 97; https://doi.org/10.3390/app8010097 - 11 Jan 2018

Cited by 61 | Viewed by 8655

Abstract

Magnetic plasmonic nanomaterials are of great interest in the field of biomedicine due to their vast number of potential applications, for example, in molecular imaging, photothermal therapy, magnetic hyperthermia and as drug delivery vehicles. The multimodal nature of these nanoparticles means that they [...] Read more.

Magnetic plasmonic nanomaterials are of great interest in the field of biomedicine due to their vast number of potential applications, for example, in molecular imaging, photothermal therapy, magnetic hyperthermia and as drug delivery vehicles. The multimodal nature of these nanoparticles means that they are potentially ideal theranostic agents—i.e., they can be used both as therapeutic and diagnostic tools. This review details progress in the field of magnetic-plasmonic nanomaterials over the past ten years, focusing on significant developments that have been made and outlining the future work that still needs to be done in this fast emerging area. The review describes the main synthetic approaches to each type of magnetic plasmonic nanomaterial and the potential biomedical applications of these hybrid nanomaterials. Full article

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

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15 pages, 1388 KiB

Open AccessFeature PaperReview

Optical Effects Induced by Bloch Surface Waves in One-Dimensional Photonic Crystals

by Irina V. Soboleva^1,2, Maria N. Romodina¹, Evgeny V. Lyubin¹ and Andrey A. Fedyanin^1,*

¹ Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia

² Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119071, Russia

Appl. Sci. 2018, 8(1), 127; https://doi.org/10.3390/app8010127 - 17 Jan 2018

Cited by 14 | Viewed by 6158

Abstract

The review considers the influence of Bloch surface waves on the optical and magneto-optical effects observed in photonic crystals; for example, the Goos–Hänchen effect, the Faraday effect, optical trapping and so on. Prospects for using Bloch surface waves for spatial light modulation, for [...] Read more.

The review considers the influence of Bloch surface waves on the optical and magneto-optical effects observed in photonic crystals; for example, the Goos–Hänchen effect, the Faraday effect, optical trapping and so on. Prospects for using Bloch surface waves for spatial light modulation, for controlling the polarization of light, for optical trapping and control of micro-objects are discussed. Full article

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

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28 pages, 4353 KiB

Open AccessReview

Current Status of Single Particle Imaging with X-ray Lasers

by Zhibin Sun^1,2,3, Jiadong Fan³, Haoyuan Li^2,4 and Huaidong Jiang^3,*

¹ State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China

² Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA

³ School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China

⁴ Department of Physics, Stanford University, Stanford, CA 94305, USA

Appl. Sci. 2018, 8(1), 132; https://doi.org/10.3390/app8010132 - 22 Jan 2018

Cited by 36 | Viewed by 10205

Abstract

The advent of ultrafast X-ray free-electron lasers (XFELs) opens the tantalizing possibility of the atomic-resolution imaging of reproducible objects such as viruses, nanoparticles, single molecules, clusters, and perhaps biological cells, achieving a resolution for single particle imaging better than a few tens of [...] Read more.

The advent of ultrafast X-ray free-electron lasers (XFELs) opens the tantalizing possibility of the atomic-resolution imaging of reproducible objects such as viruses, nanoparticles, single molecules, clusters, and perhaps biological cells, achieving a resolution for single particle imaging better than a few tens of nanometers. Improving upon this is a significant challenge which has been the focus of a global single particle imaging (SPI) initiative launched in December 2014 at the Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, USA. A roadmap was outlined, and significant multi-disciplinary effort has since been devoted to work on the technical challenges of SPI such as radiation damage, beam characterization, beamline instrumentation and optics, sample preparation and delivery and algorithm development at multiple institutions involved in the SPI initiative. Currently, the SPI initiative has achieved 3D imaging of rice dwarf virus (RDV) and coliphage PR772 viruses at ~10 nm resolution by using soft X-ray FEL pulses at the Atomic Molecular and Optical (AMO) instrument of LCLS. Meanwhile, diffraction patterns with signal above noise up to the corner of the detector with a resolution of ~6 Ångström (Å) were also recorded with hard X-rays at the Coherent X-ray Imaging (CXI) instrument, also at LCLS. Achieving atomic resolution is truly a grand challenge and there is still a long way to go in light of recent developments in electron microscopy. However, the potential for studying dynamics at physiological conditions and capturing ultrafast biological, chemical and physical processes represents a tremendous potential application, attracting continued interest in pursuing further method development. In this paper, we give a brief introduction of SPI developments and look ahead to further method development. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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18 pages, 4426 KiB

Open AccessFeature PaperReview

Incoherent Digital Holography: A Review

by Jung-Ping Liu¹, Tatsuki Tahara^2,3, Yoshio Hayasaki⁴ and Ting-Chung Poon^1,5,*

¹ Department of Photonics, Feng Chia University, 100 Wenhwa Rd., Seatwen, Taichung 40725, Taiwan

² Faculty of Engineering Science, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680, Japan

³ PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

⁴ Center for Optical Research & Education (CORE), Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585, Japan

⁵ Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA

Appl. Sci. 2018, 8(1), 143; https://doi.org/10.3390/app8010143 - 20 Jan 2018

Cited by 122 | Viewed by 16371

Abstract

Digital holography (DH) is a promising technique for modern three-dimensional (3D) imaging. Coherent holography records the complex amplitude of a 3D object holographically, giving speckle noise upon reconstruction and presenting a serious drawback inherent in coherent optical systems. On the other hand, incoherent [...] Read more.

Digital holography (DH) is a promising technique for modern three-dimensional (3D) imaging. Coherent holography records the complex amplitude of a 3D object holographically, giving speckle noise upon reconstruction and presenting a serious drawback inherent in coherent optical systems. On the other hand, incoherent holography records the intensity distribution of the object, allowing a higher signal-to-noise ratio as compared to its coherent counterpart. Currently there are two incoherent digital holographic techniques: optical scanning holography (OSH) and Fresnel incoherent correlation holography (FINCH). In this review, we first explain the principles of OSH and FINCH. We then compare, to some extent, the differences between OSH and FINCH. Finally, some of the recent applications of the two incoherent holographic techniques are reviewed. Full article

(This article belongs to the Special Issue Holography and 3D Imaging: Tomorrows Ultimate Experience)

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2 pages, 154 KiB

Open AccessCorrection

Correction: Md. Mehedi Hasan, et al. Compact Left-Handed Meta-Atom for S-, C- and Ku-Band Application. Appl. Sci. 2017, 7, 1071

by Md. Mehedi Hasan^1,*

, Mohammad Rashed Iqbal Faruque^1,*

and Mohammad Tariqul Islam^2,*

¹ Space Science Centre (ANGKASA), Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

² Department of Electrical, Electronic and Systems Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Appl. Sci. 2018, 8(1), 53; https://doi.org/10.3390/app8010053 - 4 Jan 2018

Cited by 1 | Viewed by 3592

Abstract

We, the authors, wish to update the caption of Figure 1 and the Reference section in our published paper [1][...] Full article

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