Applied Sciences

11 pages, 3718 KiB

Open AccessArticle

Methodological Considerations of Using Thermoelectrics with Fin Heat Sinks for Cooling Applications

by Kok Seng Ong, Choon Foong Tan and Koon Chun Lai^*

Faculty of Engineering and Green Technology, UniversitiTunku Abdul Rahman, Kampar 31900, Malaysia

Appl. Sci. 2017, 7(2), 62; https://doi.org/10.3390/app7020062 - 7 Feb 2017

Cited by 5 | Viewed by 5701

Abstract

An experimental investigation was conducted to evaluate the performance of a thermoelectric (TE) module fitted to a conventional fin heat sink with a similar sized heat source. Experiments were conducted with power inputs at 10 W and 20 W under natural convection (NC) [...] Read more.

An experimental investigation was conducted to evaluate the performance of a thermoelectric (TE) module fitted to a conventional fin heat sink with a similar sized heat source. Experiments were conducted with power inputs at 10 W and 20 W under natural convection (NC) and forced convection (FC) air cooling. The results showed that the use of the TE module is not effective under the NC cooling mode. With the present TE module employed, under FC cooling at 20 W, the applied voltage (V_te) to the TE module should be >4 V and at 10 W, it should be >1 V. A simple iterative method of predicting the hot side temperature of the TE module was presented. Agreement between predicted and experimental values was better than 2%. Full article

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11 pages, 2966 KiB

Open AccessArticle

Welding Robot Collision-Free Path Optimization

by Xuewu Wang^*

, Lika Xue, Yixin Yan and Xingsheng Gu

Key Laboratory of Advanced Control and Optimization for Chemical Processes of Ministry of Education, East China University of Science and Technology, Shanghai 200237, China

Appl. Sci. 2017, 7(2), 89; https://doi.org/10.3390/app7020089 - 8 Feb 2017

Cited by 24 | Viewed by 7134

Abstract

Reasonable welding path has a significant impact on welding efficiency, and a collision-free path should be considered first in the process of welding robot path planning. The shortest path length is considered as an optimization objective, and obstacle avoidance is considered as the [...] Read more.

Reasonable welding path has a significant impact on welding efficiency, and a collision-free path should be considered first in the process of welding robot path planning. The shortest path length is considered as an optimization objective, and obstacle avoidance is considered as the constraint condition in this paper. First, a grid method is used as a modeling method after the optimization objective is analyzed. For local collision-free path planning, an ant colony algorithm is selected as the search strategy. Then, to overcome the shortcomings of the ant colony algorithm, a secondary optimization is presented to improve the optimization performance. Finally, the particle swarm optimization algorithm is used to realize global path planning. Simulation results show that the desired welding path can be obtained based on the optimization strategy. Full article

(This article belongs to the Special Issue Gas Tungsten Arc Welding)

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17 pages, 7327 KiB

Open AccessArticle

A Two-Step Strategy for System Identification of Civil Structures for Structural Health Monitoring Using Wavelet Transform and Genetic Algorithms

by Carlos Andres Perez-Ramirez¹

, Arturo Yosimar Jaen-Cuellar¹, Martin Valtierra-Rodriguez¹, Aurelio Dominguez-Gonzalez¹, Roque Alfredo Osornio-Rios¹

, Rene De Jesus Romero-Troncoso² and Juan Pablo Amezquita-Sanchez^1,*

¹ Faculty of Engineering, Autonomous University of Queretaro, Campus San Juan del Rio, Rio Moctezuma 249, Col. San Cayetano, 76805 San Juan del Rio, Mexico

² CA Telematica, División de Ingenierias Campus Irapuato Salamanca, University of Guanajuato, Carr. Salamanca-Valle de Santiago Km. 3.5 + 1.8, 36885 Salamanca, Mexico

Appl. Sci. 2017, 7(2), 111; https://doi.org/10.3390/app7020111 - 24 Jan 2017

Cited by 22 | Viewed by 6468

Abstract

Nowadays, the accurate identification of natural frequencies and damping ratios play an important role in smart civil engineering, since they can be used for seismic design, vibration control, and condition assessment, among others. To achieve it in practical way, it is required to [...] Read more.

Nowadays, the accurate identification of natural frequencies and damping ratios play an important role in smart civil engineering, since they can be used for seismic design, vibration control, and condition assessment, among others. To achieve it in practical way, it is required to instrument the structure and apply techniques which are able to deal with noise-corrupted and non-linear signals, as they are common features in real-life civil structures. In this article, a two-step strategy is proposed for performing accurate modal parameters identification in an automated manner. In the first step, it is obtained and decomposed the measured signals using the natural excitation technique and the synchrosqueezed wavelet transform, respectively. Then, the second step estimates the modal parameters by solving an optimization problem employing a genetic algorithm-based approach, where the micropopulation concept is used to improve the speed convergence as well as the accuracy of the estimated values. The accuracy and effectiveness of the proposal are tested using both the simulated response of a benchmark structure and the measurements of a real eight-story building. The obtained results show that the proposed strategy can estimate the modal parameters accurately, indicating than the proposal can be considered as an alternative to perform the abovementioned task. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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23 pages, 24879 KiB

Open AccessArticle

A Multi-Layer Fusion-Based Facial Expression Recognition Approach with Optimal Weighted AUs

by Xibin Jia^1,*, Shuangqiao Liu¹, David Powers^1,2

and Barry Cardiff³

¹ Beijing Municipal Key Laboratory of Multimedia and Intelligent Software Technology, Beijing University of Technology, Beijing 100124, China

² School of Computer Science, Engineering and Mathematics, Flinders University of South Australia, Adelaide 5001, Australia

³ School of Electrical, electronic & communications Engineering, University College Dublin, Dublin 4, Ireland

Appl. Sci. 2017, 7(2), 112; https://doi.org/10.3390/app7020112 - 24 Jan 2017

Cited by 6 | Viewed by 4975

Abstract

Affective computing is an increasingly important outgrowth of Artificial Intelligence, which is intended to deal with rich and subjective human communication. In view of the complexity of affective expression, discriminative feature extraction and corresponding high-performance classifier selection are still a big challenge. Specific [...] Read more.

Affective computing is an increasingly important outgrowth of Artificial Intelligence, which is intended to deal with rich and subjective human communication. In view of the complexity of affective expression, discriminative feature extraction and corresponding high-performance classifier selection are still a big challenge. Specific features/classifiers display different performance in different datasets. There has currently been no consensus in the literature that any expression feature or classifier is always good in all cases. Although the recently updated deep learning algorithm, which uses learning deep feature instead of manual construction, appears in the expression recognition research, the limitation of training samples is still an obstacle of practical application. In this paper, we aim to find an effective solution based on a fusion and association learning strategy with typical manual features and classifiers. Taking these typical features and classifiers in facial expression area as a basis, we fully analyse their fusion performance. Meanwhile, to emphasize the major attributions of affective computing, we select facial expression relative Action Units (AUs) as basic components. In addition, we employ association rules to mine the relationships between AUs and facial expressions. Based on a comprehensive analysis from different perspectives, we propose a novel facial expression recognition approach that uses multiple features and multiple classifiers embedded into a stacking framework based on AUs. Extensive experiments on two public datasets show that our proposed multi-layer fusion system based on optimal AUs weighting has gained dramatic improvements on facial expression recognition in comparison to an individual feature/classifier and some state-of-the-art methods, including the recent deep learning based expression recognition one. Full article

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22 pages, 6756 KiB

Open AccessArticle

Importance of Physical and Physiological Parameters in Simulated Particle Transport in the Alveolar Zone of the Human Lung

by Dogan Ciloglu¹, Hassan Athari^2,*, Abdurrahim Bolukbasi³ and Marc A. Rosen⁴

¹ Vocational School of Higher Education, Atatürk University, Erzurum 25240, Turkey

² Elm_o_fan University College of Science and Technology, Urmia 57159, Iran

³ Department of Mechanical Engineering, Atatürk University, Erzurum 25240, Turkey

⁴ Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, ON L1H 7K4, Canada

Appl. Sci. 2017, 7(2), 113; https://doi.org/10.3390/app7020113 - 24 Jan 2017

Cited by 7 | Viewed by 4839

Abstract

The trajectory and deposition efficiency of micron-sized (1–5 µm) particles, inhaled into the pulmonary system, are accurately determined with the aid of a newly developed model and modified simulation techniques. This alveolar model, which has a simple but physiologically appropriate geometry, and the [...] Read more.

The trajectory and deposition efficiency of micron-sized (1–5 µm) particles, inhaled into the pulmonary system, are accurately determined with the aid of a newly developed model and modified simulation techniques. This alveolar model, which has a simple but physiologically appropriate geometry, and the utilized fluid structure interaction (FSI) methods permit the precise simulation of tissue wall deformation and particle fluid interactions. The relation between tissue movement and airflow in the alveolated duct is solved by a two-way fluid structure interaction simulation technique, using ANSYS Workbench (Release 16.0, ANSYS INC., Pittsburgh, PA, USA, 2015). The dynamic transport of particles and their deposition are investigated as a function of aerodynamic particle size, tissue visco-elasticity, tidal breathing period, gravity orientation and particle–fluid interactions. It is found that the fluid flows and streamlines differ between the present flexible model and rigid models, and the two-way coupling particle trajectories vary relative to one-way particle coupling. In addition, the results indicate that modelling the two-way coupling particle system is important because the two-way discrete phase method (DPM) approach despite its complexity provides more extensive particle interactions and is more reliable than transport results from the one-way DPM approach. The substantial difference between the results of the two approaches is likely due to particle–fluid interactions, which re-suspend the sediment particles in the airway stream and hence pass from the current generation. Full article

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15 pages, 2534 KiB

Open AccessArticle

A Kinematic Model to Compensate the Structural Deformations in Machine Tools Using Fiber Bragg Grating (FBG) Sensors

by Francesco Aggogeri¹

, Alberto Borboni¹

, Rodolfo Faglia¹

, Angelo Merlo² and Nicola Pellegrini^1,*

¹ Department of Mechanical and Industrial Engineering, University of Brescia, via Branze, 38, 25123 Brescia, Italy

² CE.S.I Centro Studi Industriali, via Tintoretto, 10, 20093 Cologno Monzese, Italy

Appl. Sci. 2017, 7(2), 114; https://doi.org/10.3390/app7020114 - 24 Jan 2017

Cited by 16 | Viewed by 4955

Abstract

Structural deformations are one of the most significant factors that affects machine tool (MT) positioning accuracy. These induced errors are complex for accurate representation by a model, nevertheless they need to be evaluated and predicted in order to increase the machining performance. This [...] Read more.

Structural deformations are one of the most significant factors that affects machine tool (MT) positioning accuracy. These induced errors are complex for accurate representation by a model, nevertheless they need to be evaluated and predicted in order to increase the machining performance. This paper presents a novel approach to calibrate a machine tool in real-time, analyzing the thermo-mechanical errors through fiber Bragg grating (FBG) sensors embedded in the MT frame. The proposed configuration consists of an adaptronic structure of passive materials, Carbon Fiber Reinforced Polymers (CFRP), equipped with FBG sensors that are able to measure in real-time the deformed conditions of the frame. By using a proper thermo-mechanical kinematic model, the displacement of the end effector may be predicted and corrected when it is subjected to external undesired factors. By starting from a set of Finite Element (FE) simulations to develop a model able to describe the MT structure stresses, a prototype has been fabricated and tested. The aim of this study was to compare the numerical model with the experimental tests using FBG sensors. The experimental campaign has been performed by varying the structure temperature over time and measuring the tool tip point (TTP) positions. The obtained results showed a substantial matching between the real and the predicted position of the TTP, thereby confirming the effectiveness of the proposed system. Full article

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

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14 pages, 4913 KiB

Open AccessArticle

A Single-Stage LED Tube Lamp Driver with Power-Factor Corrections and Soft Switching for Energy-Saving Indoor Lighting Applications

by Chun-An Cheng

, En-Chih Chang^*, Ching-Hsien Tseng and Tsung-Yuan Chung

Department of Electrical Engineering, I-Shou University, Dashu District, Kaohsiung City 84001, Taiwan

Appl. Sci. 2017, 7(2), 115; https://doi.org/10.3390/app7020115 - 24 Jan 2017

Cited by 15 | Viewed by 7997

Abstract

This paper presents a single-stage alternating current (AC)/direct current (DC) light-emitting diode (LED) tube lamp driver for energy-saving indoor lighting applications; this driver features power-factor corrections and soft switching, and also integrates a dual buck-boost converter with coupled inductors and a half-bridge series [...] Read more.

This paper presents a single-stage alternating current (AC)/direct current (DC) light-emitting diode (LED) tube lamp driver for energy-saving indoor lighting applications; this driver features power-factor corrections and soft switching, and also integrates a dual buck-boost converter with coupled inductors and a half-bridge series resonant converter cascaded with a bridge rectifier into a single-stage power-conversion topology. The features of the presented driver are high efficiency (>91%), satisfying power factor (PF > 0.96), low input-current total-harmonic distortion (THD < 10%), low output voltage ripple factor (<7.5%), low output current ripple factor (<8%), and zero-voltage switching (ZVS) obtained on both power switches. Operational principles are described in detail, and experimental results obtained from an 18 W-rated LED tube lamp for T8/T10 fluorescent lamp replacements with input utility-line voltages ranging from 100 V to 120 V have demonstrated the functionality of the presented driver suitable for indoor lighting applications. Full article

(This article belongs to the Special Issue Energy Saving)

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16 pages, 2818 KiB

Open AccessArticle

A Piezoelectric Energy Harvester with Bending–Torsion Vibration in Low-Speed Water

by Xiaobiao Shan¹, Jie Deng¹

, Rujun Song²

and Tao Xie^1,*

¹ School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China

² School of Mechatronics Engineering, Shandong University of Technology, Zibo 255049, China

Appl. Sci. 2017, 7(2), 116; https://doi.org/10.3390/app7020116 - 25 Jan 2017

Cited by 36 | Viewed by 6233

Abstract

This paper presents a piezoelectric energy harvester using an eccentric cylinder undergoing bending–torsion vibration in low-speed water. It can harvest energy from water using vortex-induced vibration (VIV). A distributed parameter beam model with respect to the motion of the piezoelectric beam was established [...] Read more.

This paper presents a piezoelectric energy harvester using an eccentric cylinder undergoing bending–torsion vibration in low-speed water. It can harvest energy from water using vortex-induced vibration (VIV). A distributed parameter beam model with respect to the motion of the piezoelectric beam was established based on Euler–Bernoulli beam theory. The governing coupled equations of the harvester system were derived by Lagrange’s equations. The optimal configurations and work conditions of harvesters were numerically analyzed according to the above mathematical models. Experiments were designed and performed to verify the numerical results. The numerical results were in good agreement with the experiment results, which verifies the validity of the mathematical models. The harvester with bending–torsion vibration generated an output power of 0.3978 mW, which is 1.99 times of that of the harvester with a solid-cylinder tip undergoing bending only. Full article

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

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13 pages, 4660 KiB

Open AccessArticle

A Comprehensive Empirical Correlation for Finned Heat Exchangers with Parallel Plates Working in Oscillating Flow

by Jiale Huang^1,2, Mianli Liu^1,2 and Tao Jin^1,2,*

¹ Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027, China

² Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Hangzhou 310027, China

Appl. Sci. 2017, 7(2), 117; https://doi.org/10.3390/app7020117 - 8 Feb 2017

Cited by 13 | Viewed by 4512

Abstract

The oscillating-flow heat transfer performance in finned heat exchangers is one of the main factors affecting the working efficiency of regenerative heat engines and refrigerators. In addition to the working parameters, the geometrical parameters of finned heat exchangers are also major influencing factors. [...] Read more.

The oscillating-flow heat transfer performance in finned heat exchangers is one of the main factors affecting the working efficiency of regenerative heat engines and refrigerators. In addition to the working parameters, the geometrical parameters of finned heat exchangers are also major influencing factors. In the present study, the ratio of the heat exchanger length and hydraulic diameter is applied as an independent similarity criterion. An experimental study has been carried out with six different geometrical dimensions of finned heat exchangers with parallel plates, in order to analyze the impacts of fin length, plate spacing, and corresponding relative fluid displacement amplitude, under various working conditions. Based on 298 tested points, a comprehensive empirical correlation for the finned heat exchangers with parallel plates working in oscillating flow has been proposed, providing a relatively accurate prediction, with 98.6% of data in the ±20% deviation and 83.9% of data in the ±10% deviation, within the range discussed. Full article

(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)

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12 pages, 3290 KiB

Open AccessArticle

Wetting Resistance of Commercial Membrane Distillation Membranes in Waste Streams Containing Surfactants and Oil

by Lies Eykens^1,2,*

, Kristien De Sitter¹, Chris Dotremont¹, Wim De Schepper¹, Luc Pinoy³ and Bart Van Der Bruggen^2,4

¹ VITO—Flemish Institute for Technological Research, Boeretang 200, 2400 Mol, Belgium

² Department of Chemical Engineering, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium

³ Department of Chemical Engineering, Cluster Sustainable Chemical Process Technology, KU Leuven, Gebroeders Desmetstraat 1, B-9000 Ghent, Belgium

⁴ Faculty of Engineering and the Built Environment, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa

Appl. Sci. 2017, 7(2), 118; https://doi.org/10.3390/app7020118 - 25 Jan 2017

Cited by 61 | Viewed by 10046

Abstract

Water management is becoming increasingly challenging and several technologies, including membrane distillation (MD) are emerging. This technology is less affected by salinity compared to reverse osmosis and is able to treat brines up to saturation. The focus of MD research recently shifted from [...] Read more.

Water management is becoming increasingly challenging and several technologies, including membrane distillation (MD) are emerging. This technology is less affected by salinity compared to reverse osmosis and is able to treat brines up to saturation. The focus of MD research recently shifted from seawater desalination to industrial applications out of the scope of reverse osmosis. In many of these applications, surfactants or oil traces are present in the feed stream, lowering the surface tension and increasing the risk for membrane wetting. In this study, the technological boundaries of MD in the presence of surfactants are investigated using surface tension, contact angle and liquid entry pressure measurements together with lab-scale MD experiments to predict the wetting resistance of different membranes. Synthetic NaCl solutions mixed with sodium dodecyl sulfate (SDS) were used as feed solution. The limiting surfactant concentration was found to be dependent on the surface chemistry of the membrane, and increased with increasing hydrophobicity and oleophobicity. Additionally, a hexadecane/SDS emulsion was prepared with a composition simulating produced water, a waste stream in the oil and gas sector. When hexadecane is present in the emulsion, oleophobic membranes are able to resist wetting, whereas polytetrafluoretheen (PTFE) is gradually wetted by the feed liquid. Full article

(This article belongs to the Special Issue Membrane Distillation)

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17 pages, 4635 KiB

Open AccessArticle

Experimental Study and Modelling of the Thermal Conductivity of Sandy Soils of Different Porosities and Water Contents

by Hua Jin¹, Yu Wang^2,*, Qiang Zheng¹, Hu Liu³ and Edmund Chadwick²

¹ College of Water Resource Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China

² School of Computing, Science & Engineering, University of Salford, Manchester M5 4WT, UK

³ Taiyuan Bilan Hydraulic Engineering Design Co. Ltd., Taiyuan 030024, China

Appl. Sci. 2017, 7(2), 119; https://doi.org/10.3390/app7020119 - 25 Jan 2017

Cited by 16 | Viewed by 6456

Abstract

This paper at first reports an experimental work to test the thermal conductivity of formulated sandy soil specimens of different porosities and water contents. Both needle probe and hot-plate methods were conducted and compared. It has been confirmed that the needle probe method [...] Read more.

This paper at first reports an experimental work to test the thermal conductivity of formulated sandy soil specimens of different porosities and water contents. Both needle probe and hot-plate methods were conducted and compared. It has been confirmed that the needle probe method has a better accuracy for the measurement of unsaturated soil thermal conductivity, and that the pore size distribution plays an important role on unsaturated soil thermal conductivity. Secondly, it gives out an extensive review on the modelling work, and investigates two major types of empirical models in detail. Two generalized formulas have been suggested to mathematically characterise the two types of models and tested using the experimental data. Finally, in terms of the intrinsic relation to the pore size distribution and the similarity between the thermal conductivity and water retention characteristics of unsaturated soils, a soil water retention model has been suggested and tested to describe unsaturated soil thermal conductivity. Full article

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

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21 pages, 4678 KiB

Open AccessReview

A Review of Experimental Techniques for Measuring Micro- to Nano-Particle-Laden Gas Flows

by Chengxu Tu¹, Zhaoqin Yin^1,*, Jianzhong Lin^1,2 and Fubing Bao¹

¹ Zhejiang Provincial Key Laboratory of Flow Measurement Technology, China Jiliang University, Hangzhou 310018, China

² State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China

Appl. Sci. 2017, 7(2), 120; https://doi.org/10.3390/app7020120 - 25 Jan 2017

Cited by 28 | Viewed by 7635

Abstract

Dispersed micro- to nano-particle-laden gas flows are common in many engineering and environmental applications. Characterizing both their dispersed and carrier phase using experimental methods is very important for determining their properties and behavior. This paper reviews techniques for measuring the carrier phase, as [...] Read more.

Dispersed micro- to nano-particle-laden gas flows are common in many engineering and environmental applications. Characterizing both their dispersed and carrier phase using experimental methods is very important for determining their properties and behavior. This paper reviews techniques for measuring the carrier phase, as well as the dispersed particles ranging from the micro- to the nano-scale. We focus not only on the developments of specific techniques over the last 20 years, but also on relationships and comparisons among these techniques. In addition to a systematic description and classification of these methods, we discuss the parameters they measure, such as particle velocity, size, composition and concentration. A more detailed review is provided for several important measurement techniques, including particle image velocimetry, the phase-Doppler particle analyzer and light-scattering intensity measurements for microparticles, as well as the scanning mobility particle sizer, the fast mobility particle sizer and the electrical low pressure impactor for nano-particles. The founding principles, development histories, various applications of these techniques and where they are going are summarized. This article provides a resource for investigators that plan to study micro- or nano-particle-laden gas flows in various contexts. Full article

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14 pages, 4805 KiB

Open AccessArticle

The Model Analysis of a Complex Tuning Fork Probe and Its Application in Bimodal Atomic Force Microscopy

by Zhichao Wu, Tong Guo^*, Ran Tao, Linyan Xu, Jinping Chen, Xing Fu and Xiaotang Hu

State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Appl. Sci. 2017, 7(2), 121; https://doi.org/10.3390/app7020121 - 25 Jan 2017

Cited by 3 | Viewed by 5304

Abstract

A new electromechanical coupling model was built to quantitatively analyze the tuning fork probes, especially the complex ones. A special feature of a novel, soft tuning fork probe, that the second eigenfrequency of the probe was insensitive to the effective force gradient, was [...] Read more.

A new electromechanical coupling model was built to quantitatively analyze the tuning fork probes, especially the complex ones. A special feature of a novel, soft tuning fork probe, that the second eigenfrequency of the probe was insensitive to the effective force gradient, was found and used in a homemade bimodal atomic force microscopy to measure power dissipation quantitatively. By transforming the mechanical parameters to the electrical parameters, a monotonous and concise method without using phase to calculate the power dissipation was proposed. Full article

(This article belongs to the Special Issue Dimensional Micro and Nanometrology)

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15 pages, 3313 KiB

Open AccessArticle

A GTA Welding Cooling Rate Analysis on Stainless Steel and Aluminum Using Inverse Problems

by Elisan Dos Santos Magalhaes

, Ana Lúcia Fernandes de Lima e Silva and Sandro Metrevelle Marcondes Lima e Silva^*

Heat Transfer Laboratory—LabTC, Institute of Mechanical Engineering—IEM, Federal University of Itajubá—UNIFEI, Campus Prof. José Rodrigues Seabra, Av. BPS, 1303, 37500-903 Itajubá, MG, Brazil

Appl. Sci. 2017, 7(2), 122; https://doi.org/10.3390/app7020122 - 25 Jan 2017

Cited by 12 | Viewed by 7142

Abstract

This work presents an analysis of the thermal influence of the heat transfer by convection and radiation during GTA (gas tungsten arc) welding process. The authors’ in-house C++ previously-developed code was modified to calculate the amount of heat transfer by convection and radiation. [...] Read more.

This work presents an analysis of the thermal influence of the heat transfer by convection and radiation during GTA (gas tungsten arc) welding process. The authors’ in-house C++ previously-developed code was modified to calculate the amount of heat transfer by convection and radiation. In this software, an iterative Broydon-Fletcher-Goldfarb-Shanno (BFGS) inverse method was applied to estimate the amount of heat delivered to the plate when the appropriate sensitivity criteria were defined. The methodology was validated by accomplishing lab-controlled experiments on stainless steel AISI 304L and aluminum 6065 T5 plates. Due to some experimental singularities, the forced thermal convection induced by the electromagnetic field and thermal-capillary force were disregarded. Significant examples of these singularities are the relatively small weld bead when compared to the sample size and the reduced time of the welding process. In order to evaluate the local Nusselt number, empirical correlations for flat plates were used. The thermal emission was a dominant cooling effect on the aluminum cooling. However, it did not present the same behavior as the stainless steel samples. The study found that the heat losses by convection and radiation of the weld pool do not affect the cooling process significantly. Full article

(This article belongs to the Special Issue Gas Tungsten Arc Welding)

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14 pages, 7454 KiB

Open AccessArticle

Microstructural Evolution within the Interphase between Hardening Overlay and Existing Concrete Substrates

by Łukasz Sadowski^*

and Damian Stefaniuk

Faculty of Civil Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland

Appl. Sci. 2017, 7(2), 123; https://doi.org/10.3390/app7020123 - 25 Jan 2017

Cited by 28 | Viewed by 5195

Abstract

This article presents the microstructural evolution within the interphase between a hardening overlay made of cement mortar and an existing concrete substrate. The substrate has been treated using four methods, due to which different surfaces were obtained: a raw surface, a surface formed [...] Read more.

This article presents the microstructural evolution within the interphase between a hardening overlay made of cement mortar and an existing concrete substrate. The substrate has been treated using four methods, due to which different surfaces were obtained: a raw surface, a surface formed after contact with the formwork, a grinded surface, and a shotblasted surface. Special focus is placed on the results of the microporosity within the interphase zone (IZ) using X-ray micro computed tomography (micro-CT). The microporosity profiles obtained from the micro-CT images have been used to assess the nature of the IZ between the hardening overlay and the existing concrete substrate. It has been shown that microporosity and the number of pores in the concrete within the IZ increases during the hardening time of an overlay made of cement mortar. It also depends on the applied surface treatment method. However, no significant changes in the microporosity of the existing concrete substrate have been noted. Full article

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17 pages, 7386 KiB

Open AccessArticle

Artificial Neural Network-Based Constitutive Relationship of Inconel 718 Superalloy Construction and Its Application in Accuracy Improvement of Numerical Simulation

by Junya Lv^1,*, Huiyu Ren¹ and Kai Gao²

¹ College of Computer and Information Engineering, Henan University of Economics and Law, Zhengzhou 450002, China

² College of Materials Science and Engineering, Southwest University, Chongqing 400715, China

Appl. Sci. 2017, 7(2), 124; https://doi.org/10.3390/app7020124 - 26 Jan 2017

Cited by 15 | Viewed by 6407

Abstract

The application of accurate constitutive relationship in finite element simulation would significantly contribute to accurate simulation results, which play critical roles in process design and optimization. In this investigation, the true stress-strain data of an Inconel 718 superalloy were obtained from a series [...] Read more.

The application of accurate constitutive relationship in finite element simulation would significantly contribute to accurate simulation results, which play critical roles in process design and optimization. In this investigation, the true stress-strain data of an Inconel 718 superalloy were obtained from a series of isothermal compression tests conducted in a wide temperature range of 1153–1353 K and strain rate range of 0.01–10 s⁻¹ on a Gleeble 3500 testing machine (DSI, St. Paul, DE, USA). Then the constitutive relationship was modeled by an optimally-constructed and well-trained back-propagation artificial neural network (ANN). The evaluation of the ANN model revealed that it has admirable performance in characterizing and predicting the flow behaviors of Inconel 718 superalloy. Consequently, the developed ANN model was used to predict abundant stress-strain data beyond the limited experimental conditions and construct the continuous mapping relationship for temperature, strain rate, strain and stress. Finally, the constructed ANN was implanted in a finite element solver though the interface of “URPFLO” subroutine to simulate the isothermal compression tests. The results show that the integration of finite element method with ANN model can significantly promote the accuracy improvement of numerical simulations for hot forming processes. Full article

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

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22 pages, 5697 KiB

Open AccessReview

Line-Scan Hyperspectral Imaging Techniques for Food Safety and Quality Applications

by Jianwei Qin¹, Moon S. Kim^1,*, Kuanglin Chao¹, Diane E. Chan¹, Stephen R. Delwiche² and Byoung-Kwan Cho³

¹ USDA/ARS Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, 10300 Baltimore Ave., Beltsville, MD 20705, USA

² USDA/ARS Food Quality Laboratory, Beltsville Agricultural Research Center, 10300 Baltimore Ave., Beltsville, MD 20705, USA

³ Department of Biosystems Machinery Engineering, College of Agricultural and Life Science, Chungnam National University, 99 Daehak-ro, Yuseoung-gu, Daejeon 305-764, Korea

Appl. Sci. 2017, 7(2), 125; https://doi.org/10.3390/app7020125 - 26 Jan 2017

Cited by 79 | Viewed by 14594

Abstract

Hyperspectral imaging technologies in the food and agricultural area have been evolving rapidly over the past 15 years owing to tremendous interest from both academic and industrial fields. Line-scan hyperspectral imaging is a major method that has been intensively researched and developed using [...] Read more.

Hyperspectral imaging technologies in the food and agricultural area have been evolving rapidly over the past 15 years owing to tremendous interest from both academic and industrial fields. Line-scan hyperspectral imaging is a major method that has been intensively researched and developed using different physical principles (e.g., reflectance, transmittance, fluorescence, Raman, and spatially resolved spectroscopy) and wavelength regions (e.g., visible (VIS), near infrared (NIR), and short-wavelength infrared (SWIR)). Line-scan hyperspectral imaging systems are mainly developed and used for surface inspection of food and agricultural products using area or line light sources. Some of these systems can also be configured to conduct spatially resolved spectroscopy measurements for internal or subsurface food inspection using point light sources. This paper reviews line-scan hyperspectral imaging techniques, with introduction, demonstration, and summarization of existing and emerging techniques for food and agricultural applications. The main topics include related spectroscopy techniques, line-scan measurement methods, hardware components and systems, system calibration methods, and spectral and image analysis techniques. Applications in food safety and quality are also presented to reveal current practices and future trends of line-scan hyperspectral imaging techniques. Full article

(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture)

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9 pages, 915 KiB

Open AccessArticle

Effects of Nominal Maximum Aggregate Size on the Performance of Stone Matrix Asphalt

by Hongying Liu, Peiwen Hao^* and Jinzhi Xu

Highway College, Chang’An University, Xi’an 710064, China

Appl. Sci. 2017, 7(2), 126; https://doi.org/10.3390/app7020126 - 26 Jan 2017

Cited by 23 | Viewed by 5575

Abstract

It is well known that the performance of hot mix asphalt (HMA) in service life is closely related to a proper aggregate gradation. A laboratory study was conducted to investigate the effects of nominal maximum aggregate size (NMAS) on the performance of stone [...] Read more.

It is well known that the performance of hot mix asphalt (HMA) in service life is closely related to a proper aggregate gradation. A laboratory study was conducted to investigate the effects of nominal maximum aggregate size (NMAS) on the performance of stone matrix asphalt (SMA). The volumetric characteristics and performance properties obtained from wheel tracking tests, permeability test, beam bending test, contabro test are compared for SMA mixes with different NMAS. The results indicated that voids in mineral aggregate (VMA) and voids filled with asphalt (VFA) of SMA mixtures increased with a decrease of aggregate size in aggregate gradation. SMA30 had the lowest optimum asphalt content among all the mixtures. Increase of NMAS contributed to improvement of the rutting resistance of SMA mixtures. However, a decrease of NMAS showed better cracking and raveling resistance. Permeability rate of SMA was primarily affected by the air voids (AV) and break point sieve, but was also sensitive to aggregate gradation to some extent, with reduced NMAS corresponding to less permeability rate. Based on the test results, SMA5 and SMA13 are suggested to be used as a water-proof layer in bridge deck pavement, and SMA20 and SMA30 are suggested to be used as binder course in asphalt pavement, which needs to possess superior rutting resistance at high temperature. Full article

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

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8 pages, 168 KiB

Open AccessEditorial

Rainbow Stars—Multi-Color Laser Emission for Science and Art

by Totaro Imasaka

Division of International Strategy, Center of Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

Appl. Sci. 2017, 7(2), 127; https://doi.org/10.3390/app7020127 - 4 Feb 2017

Viewed by 3653

Abstract

December 28, 1987:[...] Full article

(This article belongs to the Special Issue Multi-Color Laser Emission for the Generation of Ultrashort Optical Pulse)

15 pages, 4327 KiB

Open AccessArticle

Wind Turbine Gearbox Fault Diagnosis Based on Improved EEMD and Hilbert Square Demodulation

by Huanguo Chen, Pei Chen, Wenhua Chen^*, Chuanyu Wu, Jianmin Li and Jianwei Wu

Faculty of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China

Appl. Sci. 2017, 7(2), 128; https://doi.org/10.3390/app7020128 - 26 Jan 2017

Cited by 39 | Viewed by 7649

Abstract

The rapid expansion of wind farms has accelerated research into improving the reliability of wind turbines to reduce operational and maintenance costs. A critical component in wind turbine drive-trains is the gearbox, which is prone to different types of failures due to long-term [...] Read more.

The rapid expansion of wind farms has accelerated research into improving the reliability of wind turbines to reduce operational and maintenance costs. A critical component in wind turbine drive-trains is the gearbox, which is prone to different types of failures due to long-term operation under tough environments, variable speeds and alternating loads. To detect gearbox fault early, a method is proposed for an effective fault diagnosis by using improved ensemble empirical mode decomposition (EEMD) and Hilbert square demodulation (HSD). The method was verified numerically by implementing the scheme on the vibration signals measured from bearing and gear test rigs. In the implementation process, the following steps were identified as being important: (1) in order to increase the accuracy of EEMD, a criterion of selecting the proper resampling frequency for raw vibration signals was developed; (2) to select the fault related intrinsic mode function (IMF) that had the biggest kurtosis index value, the resampled signal was decomposed into a series of IMFs; (3) the selected IMF was demodulated by means of HSD, and fault feature information could finally be obtained. The experimental results demonstrate the merit of the proposed method in gearbox fault diagnosis. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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20 pages, 6882 KiB

Open AccessArticle

A Comprehensive Real-Time Traffic Map for Geographic Routing in VANETs

by Chi-Fu Huang, Yuan-Feng Chan and Ren-Hung Hwang^*

Department of Computer Science and Information Engineering, National Chung Cheng University, Chiayi 621, Taiwan

Appl. Sci. 2017, 7(2), 129; https://doi.org/10.3390/app7020129 - 26 Jan 2017

Cited by 9 | Viewed by 4679

Abstract

Vehicular Ad Hoc Networks (VANETs) have attracted a lot of attention during the last decade. VANETs can not only improve driving safety, but also convenience, and support most future Intelligent Transportation System (ITS). Due to the highly dynamic network topology of VANETs, many [...] Read more.

Vehicular Ad Hoc Networks (VANETs) have attracted a lot of attention during the last decade. VANETs can not only improve driving safety, but also convenience, and support most future Intelligent Transportation System (ITS). Due to the highly dynamic network topology of VANETs, many geographic routing protocols have been proposed and use real-time traffic information as an important metric to select a reliable forwarding path. However, most of the existing works do not describe how to gather real-time traffic. They either assume this information is already available, or can query an existing traffic center. Few studies have noticed this issue but the proposed solutions only consider a small region. In this paper, we propose a Comprehensive Real-Time Traffic Map (CRT Map) to collect wide-ranging real-time traffic information with low overhead. In the design of a CRT Map, the concept of Crowdsensing is adopted. Vehicles cooperatively gather traffic information and share it with each other to construct an overview of the whole road network traffic. In addition, we design a CRT Map Based Routing (CBR), which takes into account the connectivity of consecutive roads in routing decisions. Simulation results show that the CBR can achieve a lower end-to-end delay and a higher packet delivery ratio. Full article

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15 pages, 1916 KiB

Open AccessArticle

Supercooled Water Droplet Impacting Superhydrophobic Surfaces in the Presence of Cold Air Flow

by Morteza Mohammadi^*, Moussa Tembely and Ali Dolatabadi

Department of Mechanical and Industrial Engineering, Concordia University, Montreal, QC H3G 2W1, Canada

Appl. Sci. 2017, 7(2), 130; https://doi.org/10.3390/app7020130 - 26 Jan 2017

Cited by 26 | Viewed by 7746

Abstract

In the present work, an investigation of stagnation flow imposed on a supercooled water drop in cold environmental conditions was carried out at various air velocities ranging from 0 (i.e., still air) to 10 m/s along with temperature spanning from −10 to −30 [...] Read more.

In the present work, an investigation of stagnation flow imposed on a supercooled water drop in cold environmental conditions was carried out at various air velocities ranging from 0 (i.e., still air) to 10 m/s along with temperature spanning from −10 to −30 °C. The net effect of air flow on the impacting water droplet was investigated by controlling the droplet impact velocity to make it similar with and without air flow. In cold atmospheric conditions with temperatures as low as −30 °C, due to the large increase of both internal and contact line viscosity combined with the presence of ice nucleation mechanisms, supercooled water droplet wetting behavior was systematically affected. Instantaneous pinning for hydrophilic and hydrophobic surfaces was observed when the spread drop reached the maximum spreading diameter (i.e., no recoiling phase). Nevertheless, superhydrophobic surfaces showed a great repellency (e.g., contact time reduction up to 30% where air velocity was increased up to 10 m/s) at temperatures above the critical temperature of heterogeneous ice nucleation (i.e., −24 °C). However, the freezing line of the impacting water droplet was extended up to 2-fold at air velocity up to 10 m/s where substrate temperature was maintained below the aforementioned critical temperature (e.g., −30 °C). Full article

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39 pages, 4036 KiB

Open AccessArticle

A Numerical Investigation on the Natural Frequencies of FGM Sandwich Shells with Variable Thickness by the Local Generalized Differential Quadrature Method

by Francesco Tornabene^1,*

, Nicholas Fantuzzi¹

, Michele Bacciocchi¹

, Erasmo Viola¹ and Junuthula N. Reddy²

¹ DICAM—Department, School of Engineering and Architecture, University of Bologna, 40126, Italy

² Advanced Computational Mechanics Laboratory, Department of Mechanical Engineering, Texas A&M University, College Station, TX, 77843, USA

Appl. Sci. 2017, 7(2), 131; https://doi.org/10.3390/app7020131 - 27 Jan 2017

Cited by 118 | Viewed by 9471

Abstract

The main aim of the present paper is to solve numerically the free vibration problem of sandwich shell structures with variable thickness and made of Functionally Graded Materials (FGMs). Several Higher-order Shear Deformation Theories (HSDTs), defined by a unified formulation, are employed in [...] Read more.

The main aim of the present paper is to solve numerically the free vibration problem of sandwich shell structures with variable thickness and made of Functionally Graded Materials (FGMs). Several Higher-order Shear Deformation Theories (HSDTs), defined by a unified formulation, are employed in the study. The FGM structures are characterized by variable mechanical properties due to the through-the-thickness variation of the volume fraction distribution of the two constituents and the arbitrary thickness profile. A four-parameter power law expression is introduced to describe the FGMs, whereas general relations are used to define the thickness variation, which can affect both the principal coordinates of the shell reference domain. A local scheme of the Generalized Differential Quadrature (GDQ) method is employed as numerical tool. The natural frequencies are obtained varying the exponent of the volume fraction distributions using higher-order theories based on a unified formulation. The structural models considered are two-dimensional and require less degrees of freedom when compared to the corresponding three-dimensional finite element (FE) models, which require a huge number of elements to describe the same geometries accurately. A comparison of the present results with the FE solutions is carried out for the isotropic cases only, whereas the numerical results available in the literature are used to prove the validity as well as accuracy of the current approach in dealing with FGM structures characterized by a variable thickness profile. Full article

(This article belongs to the Special Issue Applications of Generalized Differential and Integral Quadrature Methods)

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13 pages, 5657 KiB

Open AccessArticle

Analysis of the Chip Geometry in Dry Machining of Aeronautical Aluminum Alloys

by Francisco Javier Trujillo Vilches^*, Lorenzo Sevilla Hurtado

, Francisco Martín Fernández and Carolina Bermudo Gamboa

Civil, Material and Manufacturing Engineering Department, ETSII-EPS, University of Malaga, Málaga 29071, Spain

Appl. Sci. 2017, 7(2), 132; https://doi.org/10.3390/app7020132 - 27 Jan 2017

Cited by 25 | Viewed by 4392

Abstract

Aluminum alloys are widely used in the manufacturing of structural parts for aircraft, frequently in combination with other materials such as CFRP (Carbon Fiber Reinforced Polymer), to form FML (Fiber Metal Laminates) structures (CFRP/Al). The dry machining of these structures presents several problems, [...] Read more.

Aluminum alloys are widely used in the manufacturing of structural parts for aircraft, frequently in combination with other materials such as CFRP (Carbon Fiber Reinforced Polymer), to form FML (Fiber Metal Laminates) structures (CFRP/Al). The dry machining of these structures presents several problems, some of which are related to chip evacuation, either when machining aluminum alloys as an isotropic material, or during hybridization with composites. In this work, a study of the way in which cutting parameters influence the chip morphology in the dry machining of UNS A97075-T6 (Al-Zn) and UNS A92024-T3 (Al-Cu) alloys, is performed. Thus, different geometric parameters of the chip morphology have been obtained, and their evolution with feed has been analysed. Finally, the different relationships which occur between these geometric parameters and feed, have been obtained. These relationships allow a prediction of the evolution of some of the geometric parameters of the chip, as a function of feed. Full article

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13 pages, 2291 KiB

Open AccessArticle

Postharvest Quality Monitoring and Variance Analysis of Peach and Nectarine Cold Chain with Multi-Sensors Technology

by Xiang Wang¹, Maja Matetić²

, Huijuan Zhou³, Xiaoshuan Zhang^1,* and Tomislav Jemrić^4,*

¹ Beijing Laboratory of Food Quality and Safety, China Agricultural University, Beijing 100083, China

² Department of Informatics, University of Rijeka, Radmile Matejčić 2, Rijeka HR-51000, Croatia

³ Key Laboratory of Protected Horticultural Technology, Forestry and Fruit Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China

⁴ Faculty of Agriculture, Department of Pomology, University of Zagreb, Svetošimunska 25, Zagreb HR-10000, Croatia

Appl. Sci. 2017, 7(2), 133; https://doi.org/10.3390/app7020133 - 29 Jan 2017

Cited by 40 | Viewed by 6889

Abstract

Fresh peaches and nectarines are very popular for their high nutritional and therapeutic value. Unfortunately, they are prone to rapid deterioration after harvest, especially if the cold chain is not well maintained. The objective of this work is to study the environmental fluctuation [...] Read more.

Fresh peaches and nectarines are very popular for their high nutritional and therapeutic value. Unfortunately, they are prone to rapid deterioration after harvest, especially if the cold chain is not well maintained. The objective of this work is to study the environmental fluctuation and the quality change of fresh peaches and nectarines in cold chain. The temperature, relative humidity, and CO₂ level were real-time monitored by sensor nodes with a wireless sensor network (WSN). The cold chain lasted for 16.8 h and consisted of six segments. The dynamic change of temperature, relative humidity, and CO₂ level were real-time monitored and analyzed in detail in each of the six stages. The fruit quality index (fruit weight, fruit firmness, and soluble solids concentration (SSC)) were detected and analyzed immediately before the first stage (S1) and at the beginning of the last stage (S6). The results show that without good temperature control fruit softening is the most significant problem, even in a short chain; the WSN node can provide complete and accurate temperature, humidity, and gas monitoring information for cold chains, and can be used to further improve quality and safety assurance for peach fruit cold chains. Full article

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16 pages, 7803 KiB

Open AccessArticle

Trapezoidal Cantilevers with Irregular Cross-Sections for Energy Harvesting Systems

by Andrius Čeponis^1,*, Dalius Mažeika¹ and Vytautas Bakanauskas²

¹ Department of Information Systems, Faculty of Fundamental Sciences, Vilnius Gediminas Technical University, Vilnius LT-10223, Lithuania

² Laboratory of Robotics and Piezomechanics, Institute of Mechatronics, Kaunas University of Technology, Kaunas LT-44249, Lithuania

Appl. Sci. 2017, 7(2), 134; https://doi.org/10.3390/app7020134 - 29 Jan 2017

Cited by 14 | Viewed by 4764

Abstract

The results of numerical and experimental investigation of trapezoidal cantilevers with irregular cross-sections are presented in this paper. Modifications of the cross-section were made in order to increase strain and improve its distribution in the piezo ceramic layer of a cantilever. The proposed [...] Read more.

The results of numerical and experimental investigation of trapezoidal cantilevers with irregular cross-sections are presented in this paper. Modifications of the cross-section were made in order to increase strain and improve its distribution in the piezo ceramic layer of a cantilever. The proposed modifications allowed improving the energy conversion coefficient and increasing the power density. The numerical investigation revealed that modifications have a positive influence on strain and its distribution characteristics. Moreover, the electrical characteristics of piezoelectric cantilevers were investigated by employing a numerical model. The analysis of the results revealed that modifications of the cross-section have positively affected the electrical outputs of the cantilevers. The results of the numerical investigation were validated by experimental investigation. Experimental investigation showed that output voltage density was increased by 9.9%, output current density by 6.9% and power density by more than three-times compared with a conventional cantilever. Full article

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

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13 pages, 3197 KiB

Open AccessArticle

Composition Distribution, Damping and Thermal Properties of the Thickness-Continuous Gradient Epoxy/Polyurethane Interpenetrating Polymer Networks

by Xuesong Lv¹, Zhixiong Huang^1,*, Minxian Shi^1,*, Yun Fan² and Guanbin Gao^3,*

¹ Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China

² College of Foreign Languages and Literature, Luojia College, Wuhan University, Wuhan 430064, China

³ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China

Appl. Sci. 2017, 7(2), 135; https://doi.org/10.3390/app7020135 - 30 Jan 2017

Cited by 29 | Viewed by 6544

Abstract

A thickness gradient interpenetrating polymer network (IPN) was easily created that takes advantage of the relatively poor compatibility and curing rates discrepancy between epoxy (EP) and polyurethane (PU). Ultraviolet absorption spectrum (UV-Vis), thermogravimetric (TG), Differential scanning calorimetry (DSC), Dynamic thermomechanical analysis (DMA), Atomic [...] Read more.

A thickness gradient interpenetrating polymer network (IPN) was easily created that takes advantage of the relatively poor compatibility and curing rates discrepancy between epoxy (EP) and polyurethane (PU). Ultraviolet absorption spectrum (UV-Vis), thermogravimetric (TG), Differential scanning calorimetry (DSC), Dynamic thermomechanical analysis (DMA), Atomic force microscope (AFM) and water contact angle were adopted to characterize this IPN structure. We found that the absorption in visible light region, glass-transition temperatures (Tg), thermal decomposition temperatures (Td) and Derjaguin–Muller–Toporov (DMT) modulus were increasing along with the gradient direction from bottom side to top side of the IPN. While the absorption in ultraviolet region and adhesion force were decreasing along with the gradient direction from bottom side to top side of the IPN. DMA analysis demonstrates that this continuous gradient IPN has a good balance between the damping temperature range and the loss factor which is suitable for using as a self-supporting damping structure. Full article

(This article belongs to the Special Issue Bio-Inspired Applications of Composites)

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22 pages, 5680 KiB

Open AccessArticle

Manufacturing Scheduling Using Colored Petri Nets and Reinforcement Learning

by Maria Drakaki^*

and Panagiotis Tzionas

Alexander Technological Educational Institute of Thessaloniki, Department of Automation Engineering, P.O. Box 141, GR-57400 Thessaloniki, Greece

Appl. Sci. 2017, 7(2), 136; https://doi.org/10.3390/app7020136 - 3 Feb 2017

Cited by 48 | Viewed by 10374

Abstract

Agent-based intelligent manufacturing control systems are capable to efficiently respond and adapt to environmental changes. Manufacturing system adaptation and evolution can be addressed with learning mechanisms that increase the intelligence of agents. In this paper a manufacturing scheduling method is presented based on [...] Read more.

Agent-based intelligent manufacturing control systems are capable to efficiently respond and adapt to environmental changes. Manufacturing system adaptation and evolution can be addressed with learning mechanisms that increase the intelligence of agents. In this paper a manufacturing scheduling method is presented based on Timed Colored Petri Nets (CTPNs) and reinforcement learning (RL). CTPNs model the manufacturing system and implement the scheduling. In the search for an optimal solution a scheduling agent uses RL and in particular the Q-learning algorithm. A warehouse order-picking scheduling is presented as a case study to illustrate the method. The proposed scheduling method is compared to existing methods. Simulation and state space results are used to evaluate performance and identify system properties. Full article

(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)

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12 pages, 2362 KiB

Open AccessArticle

Optimization Design of Coupling Beam Metal Damper in Shear Wall Structures

by Zhe Zhang¹, Jinping Ou², Dongsheng Li^2,* and Shuaifang Zhang³

¹ Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian 116024, China

² Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China

³ Department of Mechanical Engineering, Penn State University, State College, PA 16802, USA

Appl. Sci. 2017, 7(2), 137; https://doi.org/10.3390/app7020137 - 3 Feb 2017

Cited by 37 | Viewed by 6942

Abstract

The coupling beam damper is a fundamental energy dissipation component in coupling shear wall structures that directly influences the performance of the shear wall. Here, we proposed a two-fold design method that can give better energy dissipation performance and hysteretic behavior to coupling [...] Read more.

The coupling beam damper is a fundamental energy dissipation component in coupling shear wall structures that directly influences the performance of the shear wall. Here, we proposed a two-fold design method that can give better energy dissipation performance and hysteretic behavior to coupling beam dampers. First, we devised four in-plane yielding coupling beam dampers that have different opening types but the same amount of total materials. Then the geometry parameters of each opening type were optimized to yield the maximum hysteretic energy. The search for the optimal parameter set was realized by implementing the Kriging surrogate model which iterates randomly selected input shape parameters and the corresponding hysteretic energy calculated by the infinite element method. By comparing the maximum hysteretic energy in all four opening types, one type that had the highest hysteresis energy was selected as the optimized design. This optimized damper has the advantages of having a simple geometry and a high dissipation energy performance. The proposed method also provided a new framework for the design of in-plane coupling beam dampers. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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16 pages, 3713 KiB

Open AccessArticle

A Time Finite Element Method Based on the Differential Quadrature Rule and Hamilton’s Variational Principle

by Yufeng Xing^1,*

, Mingbo Qin¹ and Jing Guo²

¹ Institute of Solid Mechanics, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing 100191, China

² Science and Technology on Reliability and Environment Engineering Laboratory, Beijng Institute of Structure and Environment Engineering, No. 1, Dahongmen Road, Fengtai District, Beijing 100076, China

Appl. Sci. 2017, 7(2), 138; https://doi.org/10.3390/app7020138 - 4 Feb 2017

Cited by 13 | Viewed by 4703

Abstract

An accurate and efficient Differential Quadrature Time Finite Element Method (DQTFEM) was proposed in this paper to solve structural dynamic ordinary differential equations. This DQTFEM was developed based on the differential quadrature rule, the Gauss–Lobatto quadrature rule, and the Hamilton variational principle. The [...] Read more.

An accurate and efficient Differential Quadrature Time Finite Element Method (DQTFEM) was proposed in this paper to solve structural dynamic ordinary differential equations. This DQTFEM was developed based on the differential quadrature rule, the Gauss–Lobatto quadrature rule, and the Hamilton variational principle. The proposed DQTFEM has significant benefits including the high accuracy of differential quadrature method and the generality of standard finite element formulation, and it is also a highly accurate symplectic method. Theoretical studies demonstrate the DQTFEM has higher-order accuracy, adequate stability, and symplectic characteristics. Moreover, the initial conditions in DQTFEM can be readily imposed by a method similar to the standard finite element method. Numerical comparisons for accuracy and efficiency among the explicit Runge–Kutta method, the Newmark method, and the proposed DQTFEM show that the results from DQTFEM, even with a small number of sampling points, agree better with the exact solutions and validate the theoretical conclusions. Full article

(This article belongs to the Special Issue Applications of Generalized Differential and Integral Quadrature Methods)

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17 pages, 7297 KiB

Open AccessArticle

A 3D Skeletonization Algorithm for 3D Mesh Models Using a Partial Parallel 3D Thinning Algorithm and 3D Skeleton Correcting Algorithm

by Xun Jin¹ and Jongweon Kim^2,*

¹ Department of Copyright Protection, Sangmyung University, Seoul 03016, Korea

² Department of Electronics Engineering, Sangmyung University, Seoul 03016, Korea

Appl. Sci. 2017, 7(2), 139; https://doi.org/10.3390/app7020139 - 4 Feb 2017

Cited by 12 | Viewed by 10985

Abstract

A three-dimensional (3D) skeletonization algorithm extracts the skeleton of a 3D model and provides it for many applications, such as 3D model classification and identification. There are three major skeletonization methodologies used in the literature, distance transform field-based methods, Voronoi diagram-based methods, and [...] Read more.

A three-dimensional (3D) skeletonization algorithm extracts the skeleton of a 3D model and provides it for many applications, such as 3D model classification and identification. There are three major skeletonization methodologies used in the literature, distance transform field-based methods, Voronoi diagram-based methods, and thinning-based methods. However, the existing algorithms cannot preserve the connectivity of the skeletons of the 3D mesh models. In this paper, we propose a 3D skeletonization algorithm for 3D mesh models using a partial parallel thinning algorithm and a 3D skeleton correcting algorithm. The proposed algorithm uses pre-defined removing and recovering templates. The partial parallel 3D thinning algorithm separates 62 symmetrical removing templates into two groups based on symmetry. It thins a model with the templates of each group in each thinning procedure. The 3D skeleton correcting algorithm uses six correcting templates to inspect the disconnected voxels in the skeleton and corrects them. The experimental results show several comparisons of skeletons extracted by different skeletonization algorithms. The proposed algorithm can extract the skeleton of each branch of a model and preserve the connectivity. Full article

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16 pages, 7651 KiB

Open AccessArticle

A Novel Optical Morse Code-Based Electronic Lock Using the Ambient Light Sensor and Fuzzy Controller

by Chin-Tan Lee^1,*, Tung-Chun Shen¹

and Win-Der Lee²

¹ Department of Electronic Engineering, National Quemoy University, Jinning, Kinmen 89250, Taiwan

² Department of Electrical Engineering, Lee-Ming Institute of Technology, Taishan, New Taipei 24305, Taiwan

Appl. Sci. 2017, 7(2), 140; https://doi.org/10.3390/app7020140 - 4 Feb 2017

Cited by 4 | Viewed by 9562

Abstract

In this work, a novel electronic lock that can encode and decode optical signals, modulated using Morse code conventions, was developed to build a smart home security system based on the Internet of Things (IoT). There are five topics of interest in this [...] Read more.

In this work, a novel electronic lock that can encode and decode optical signals, modulated using Morse code conventions, was developed to build a smart home security system based on the Internet of Things (IoT). There are five topics of interest in this research: (1) optical Morse code encoder; (2) optical Morse code decoder; (3) ambient light sensor circuit; (4) fuzzy controller; (5) cloud monitoring system. We take advantage of the light-emitting components as the encoder, which are readily available in hand-held mobile devices (e.g., Smart phones) and photoresistors and a microcontroller as the decoder. By Wi-Fi transferring, even without a personal computer, real-time information about this lock can be uploaded to the cloud service platform, and helps users to ensure home safety on the remote monitoring system. By using the ambient light sensor and fuzzy controller in this novel optical Morse code-based electronic lock, experimental results show that the reliability of this system is much improved from 65% to 100%. That means that it is highly resistant to different illumination conditions in the work environment, and therefore all functions, including coding, emitting, receiving, decoding, uploading and cloud monitoring, can work well. Furthermore, besides the convenience and cost reduction, by incorporating traditional keys into smart phones, as a consumer electronics, our proposed system is suitable for users of all ages because of a user-friendly operation interface. Full article

(This article belongs to the Special Issue Selected Papers from International Conference on Applied System Innovation 2016)

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17 pages, 8217 KiB

Open AccessArticle

SAR Interferogram Filtering of Shearlet Domain Based on Interferometric Phase Statistics

by Yonghong He^1,2

, Jianjun Zhu^1,*, Haiqiang Fu¹, Qinghua Xie¹, Bing Xu¹ and Bing Zhang¹

¹ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

² School of Civil and Environmental Engineering, Hunan University of Science and Engineering, Yongzhou 425199, China

Appl. Sci. 2017, 7(2), 141; https://doi.org/10.3390/app7020141 - 4 Feb 2017

Cited by 3 | Viewed by 5649

Abstract

This paper presents a new filtering approach for Synthetic Aperture Radar (SAR) interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with [...] Read more.

This paper presents a new filtering approach for Synthetic Aperture Radar (SAR) interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with noisy phase fringes. Phase noise in SAR interferograms is directly related to the interferometric coherence and the look number of the interferogram. Therefore, an optimal interferogram filter should incorporate information from both of them. The proposed method combines the phase noise standard deviation with the shearlet transform. Experimental results show that the proposed method can reduce the interferogram noise while maintaining the spatial resolution, especially in areas with low coherence. Full article

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13 pages, 6674 KiB

Open AccessArticle

Steady-State Creep of Asphalt Concrete

by Alibai Iskakbayev¹, Bagdat Teltayev^2,*

and Cesare Oliviero Rossi³

¹ Department of Mechanics, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan

² Kazakhstan Highway Research Institute, Almaty 050061, Kazakhstan

³ Department of Chemistry and Chemical Technologies, University of Calabria, Rende 87036, Italy

Appl. Sci. 2017, 7(2), 142; https://doi.org/10.3390/app7020142 - 4 Feb 2017

Cited by 26 | Viewed by 6560

Abstract

This paper reports the experimental investigation of the steady-state creep process for fine-grained asphalt concrete at a temperature of 20 ± 2 °С and under stress from 0.055 to 0.311 MPa under direct tension and was found to occur at a constant rate. [...] Read more.

This paper reports the experimental investigation of the steady-state creep process for fine-grained asphalt concrete at a temperature of 20 ± 2 °С and under stress from 0.055 to 0.311 MPa under direct tension and was found to occur at a constant rate. The experimental results also determined the start, the end point, and the duration of the steady-state creep process. The dependence of these factors, in addition to the steady-state creep rate and viscosity of the asphalt concrete on stress is satisfactorily described by a power function. Furthermore, it showed that stress has a great impact on the specific characteristics of asphalt concrete: stress variation by one order causes their variation by 3–4.5 orders. The described relations are formulated for the steady-state of asphalt concrete in a complex stressed condition. The dependence is determined between stress intensity and strain rate intensity. Full article

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

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19 pages, 7653 KiB

Open AccessArticle

A Design for an Internet Router with a Digital Optical Data Plane

by Joe Touch^1,*, Joseph Bannister²

, Stephen Suryaputra¹ and Alan E. Willner³

¹ University of Southern California/Information Sciences Institute (USC/ISI), 4676 Admiralty Way, Marina del Rey, CA 90292-6695, USA

² The Aerospace Corporation, 2310 E. El Segundo Blvd., El Segundo, CA 90245-4609, USA

³ Department of EE-Systems, USC, 3740 McClintock Ave., Los Angeles, CA 90089-2560, USA

Appl. Sci. 2017, 7(2), 143; https://doi.org/10.3390/app7020143 - 6 Feb 2017

Viewed by 5446

Abstract

This paper presents a complete design for an optical Internet router based on the component steps required for Internet protocol (IP) packet forwarding. Implementations of hop count decrement and header matching are integrated with a simulation-based approach to variable-length packet traffic merging that [...] Read more.

This paper presents a complete design for an optical Internet router based on the component steps required for Internet protocol (IP) packet forwarding. Implementations of hop count decrement and header matching are integrated with a simulation-based approach to variable-length packet traffic merging that avoids recirculation, demonstrating an approach for an all-optical data plane. A method for IPv4 checksum computation is introduced, and this and previously designed components are extended from binary to higher-density (multiple bits per symbol) encodings. The implications of this design are considered, including the potential for chip-level and system integration, as well as the requirements of basic optical processing components. Full article

(This article belongs to the Special Issue Optical Modulators and Switches)

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16 pages, 1595 KiB

Open AccessArticle

Global and Continuous Pleasantness Estimation of the Soundscape Perceived during Walking Trips through Urban Environments

by Pierre Aumond^1,2,*

, Arnaud Can¹, Bert De Coensel³

, Carlos Ribeiro⁴, Dick Botteldooren³ and Catherine Lavandier²

¹ AME-LAE (Environmental Acoustics Laboratory), Ifsttar (Development of Networks, French Institute of Science and Technology for Transport), 44341 Bouguenais, France

² ETIS, UMR 8051/ENSEA, University of Cergy-Pontoise, CNRS, 95000 Cergy, France

³ Waves Research Group, Department of Infor mation Technology, Ghent University, Technologiepark-Zwijnaarde 15, 9052 Ghent, Belgium

⁴ Bruitparif, 93500 Pantin, France

Appl. Sci. 2017, 7(2), 144; https://doi.org/10.3390/app7020144 - 5 Feb 2017

Cited by 16 | Viewed by 5295

Abstract

This paper investigates how the overall pleasantness of the sound environment of an urban walking trip can be estimated through acoustical measurements along the path. For this purpose, two laboratory experiments were carried out, during which controlled and natural 3-min audio and audiovisual [...] Read more.

This paper investigates how the overall pleasantness of the sound environment of an urban walking trip can be estimated through acoustical measurements along the path. For this purpose, two laboratory experiments were carried out, during which controlled and natural 3-min audio and audiovisual sequences were presented. Participants were asked to continuously assess the pleasantness of the sound environment along the sequence, and globally at its end. The results reveal that the global sound pleasantness is principally explained by the average of the instantaneous sound pleasantness values. Accounting for recency or trend effects improved the estimates of the global sound pleasantness over controlled sound sequences, but their contribution is not significant for the second group of stimuli, which are based on natural audio sequences and include visual information. In addition, models for global and continuous pleasantness, as a function of the instantaneous sound pressure level L_eq,1s, are proposed. The instantaneous sound pleasantness is found to be mainly impacted by the average sound level over the past 6 s. A logarithmic fading mechanism, extracted from psychological literature, is also proposed for this modelling, and slightly improves the estimations. Finally, the globally perceived sound pleasantness can be accurately estimated from the sound pressure level of the sound sequences, explaining about 60% of the variance in the global sound pleasantness ratings. Full article

(This article belongs to the Special Issue Noise and Vibration Control in the Built Environment)

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17 pages, 4384 KiB

Open AccessArticle

The Bivariate Empirical Mode Decomposition and Its Contribution to Grinding Chatter Detection

by Huanguo Chen^1,*, Jianyang Shen¹, Wenhua Chen¹, Chuanyu Wu¹, Chunshao Huang², Yongyu Yi¹ and Jiacheng Qian¹

¹ Zhejiang Province’s Key Laboratory of Reliability Technology for Mechanical and Electrical Product, Hangzhou 310018, China

² Hangzhou Hangji Machine Tool Co., Ltd., Hangzhou 311305, China

Appl. Sci. 2017, 7(2), 145; https://doi.org/10.3390/app7020145 - 8 Feb 2017

Cited by 14 | Viewed by 6959

Abstract

Grinding chatter reduces the long-term reliability of grinding machines. Detecting the negative effects of chatter requires improved chatter detection techniques. The vibration signals collected from grinders are mainly nonstationary, nonlinear and multidimensional. Hence, bivariate empirical mode decomposition (BEMD) has been investigated as a [...] Read more.

Grinding chatter reduces the long-term reliability of grinding machines. Detecting the negative effects of chatter requires improved chatter detection techniques. The vibration signals collected from grinders are mainly nonstationary, nonlinear and multidimensional. Hence, bivariate empirical mode decomposition (BEMD) has been investigated as a multiple signal processing method. In this paper, a feature vector extraction method based on BEMD and Hilbert transform was applied to the problem of grinding chatter. The effectiveness of this method was tested and validated with a simulated chatter signal produced by a vibration signal generator. The extraction criterion of true intrinsic mode functions (IMFs) was also investigated, as well as a method for selecting the most ideal number of projection directions using the BEMD algorithm. Moreover, real-time variance and instantaneous energy were employed as chatter feature vectors for improving the prediction of chatter. Furthermore, the combination of BEMD and Hilbert transform was validated by experimental data collected from a computer numerical control (CNC) guideway grinder. The results reveal the good behavior of BEMD in terms of processing nonstationary and nonlinear signals, and indicating the synchronous characteristics of multiple signals. Extracted chatter feature vectors were demonstrated to be reliable predictors of early grinding chatter. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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22 pages, 2876 KiB

Open AccessArticle

Description of Anomalous Noise Events for Reliable Dynamic Traffic Noise Mapping in Real-Life Urban and Suburban Soundscapes

by Francesc Alías^*

and Joan Claudi Socoró

GTM—Grup de recerca en Tecnologies Mèdia, La Salle—Universitat Ramon Llull, Quatre Camins, 30, 08022 Barcelona, Spain

Appl. Sci. 2017, 7(2), 146; https://doi.org/10.3390/app7020146 - 4 Feb 2017

Cited by 41 | Viewed by 6876

Abstract

Traffic noise is one of the main pollutants in urban and suburban areas. European authorities have driven several initiatives to study, prevent and reduce the effects of exposure of population to traffic. Recent technological advances have allowed the dynamic computation of noise levels [...] Read more.

Traffic noise is one of the main pollutants in urban and suburban areas. European authorities have driven several initiatives to study, prevent and reduce the effects of exposure of population to traffic. Recent technological advances have allowed the dynamic computation of noise levels by means of Wireless Acoustic Sensor Networks (WASN) such as that developed within the European LIFE DYNAMAP project. Those WASN should be capable of detecting and discarding non-desired sound sources from road traffic noise, denoted as anomalous noise events (ANE), in order to generate reliable noise level maps. Due to the local, occasional and diverse nature of ANE, some works have opted to artificially build ANE databases at the cost of misrepresentation. This work presents the production and analysis of a real-life environmental audio database in two urban and suburban areas specifically conceived for anomalous noise events’ collection. A total of 9 h 8 min of labelled audio data is obtained differentiating among road traffic noise, background city noise and ANE. After delimiting their boundaries manually, the acoustic salience of the ANE samples is automatically computed as a contextual signal-to-noise ratio (SNR). The analysis of the real-life environmental database shows high diversity of ANEs in terms of occurrences, durations and SNRs, as well as confirming both the expected differences between the urban and suburban soundscapes in terms of occurrences and SNRs, and the rare nature of ANE. Full article

(This article belongs to the Section Acoustics and Vibrations)

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35 pages, 7816 KiB

Open AccessReview

Light Trapping above the Light Cone in One-Dimensional Arrays of Dielectric Spheres

by Evgeny N. Bulgakov^1,2, Almas F. Sadreev^1,* and Dmitrii N. Maksimov¹

¹ Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk 660036, Russia

² Deparment of Airspace Materials and Technology, Siberian State Aerospace University, Krasnoyarsk 660014, Russia

Appl. Sci. 2017, 7(2), 147; https://doi.org/10.3390/app7020147 - 8 Feb 2017

Cited by 7 | Viewed by 5610

Abstract

We demonstrate bound states in the radiation continuum (BSC) in a linear periodic array of dielectric spheres in air above the light cone. We classify the BSCs by orbital angular momentum m = 0,±1,±2 according to the rotational symmetry of the array, Bloch [...] Read more.

We demonstrate bound states in the radiation continuum (BSC) in a linear periodic array of dielectric spheres in air above the light cone. We classify the BSCs by orbital angular momentum m = 0,±1,±2 according to the rotational symmetry of the array, Bloch wave vector ꞵ directed along the array according to the translational symmetry, and polarization. The most simple symmetry protectedBSCshavem = 0,ꞵ = 0 and occur in a wide range of the radius of the spheres and dielectric constant. More sophisticated BSCs with m 6= 0,ꞵ = 0 exist only for a selected radius of spheres at ﬁxed dielectric constant. We also ﬁnd robust Bloch BSCs with ꞵ 6= 0,m = 0. All BSCs reside within the ﬁrst but below the other diffraction continua. We show that the BSCs can be easily detected by bright features in scattering of different plane waves by the array as dependent on type of the BSC. The symmetry protected TE/TMBSCs can be traced by collapsing Fano resonance in cross-sections of normally incident TE/TM plane waves. When plane wave with circular polarization with frequency tuned to the bound states with OAM illuminates the array the spin angular momentum of the incident wave transfers into the orbital angular momentum of the BSC.This ,inturn, gives rise to giant vortical power currents rotating around the array. Incident wave with linear polarization with frequency tuned to the Bloch bound state in the continuum induces giant laminar power currents. At last, the plane wave with linear polarization incident under tilt relative to the axis of array excites Poynting currents spiralling around the array. It is demonstrated numerically that quasi-bound leaky modes of the array can propagate both stationary waves and light pulses to a distance of 60 wavelengths at the frequencies close to the bound states in the radiation continuum. A semi-analytical estimate for decay rates of the guided waves is found to match the numerical data to a good accuracy. Full article

(This article belongs to the Special Issue Guided-Wave Optics)

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16 pages, 2659 KiB

Open AccessArticle

A Resource Allocation Scheme for Multi-D2D Communications Underlying Cellular Networks with Multi-Subcarrier Reusing

by Yong Zhang¹, Fangmin Li^1,2

, Mohammed Abdulaziz Aide Al-qaness¹

and Xidao Luan^2,*

¹ School of Information Engineering, Wuhan University of Technology, Wuhan 430070, China

² Department of Mathematics and Computer Science, Changsha University, Changsha 410022, China

Appl. Sci. 2017, 7(2), 148; https://doi.org/10.3390/app7020148 - 7 Feb 2017

Cited by 15 | Viewed by 4704

Abstract

Device-to-device (D2D) communication is proposed as a promising technique of future cellular networks which fulfills its potential in terms of high resource utilization. In this paper, in order to improve the achievable rate of D2D communication and the spectrum utilization, we consider the [...] Read more.

Device-to-device (D2D) communication is proposed as a promising technique of future cellular networks which fulfills its potential in terms of high resource utilization. In this paper, in order to improve the achievable rate of D2D communication and the spectrum utilization, we consider the scenario that multiple D2D pairs can share uplink spectrum resources with multiple cellular users (CUs). We aim to maximize the overall system spectrum efficiency while satisfying the rate requirements of all CUs and guaranteeing that the system gain is positive. We formulate the joint optimization problem of subcarrier assignment and power allocation which falls naturally into a mixed integer non-linear programming form that is a difficult problem to solve. Hence, we propose a two-stage resource allocation scheme which comprises a subcarrier assignment by employing a heuristic greedy strategy, as well as a power allocation algorithm based on the Lagrangian dual method. Numerical results demonstrate the advantageous performance of our scheme in greatly increasing the system sum spectrum efficiency. Full article

(This article belongs to the Special Issue Green Wireless Networks)

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17 pages, 5681 KiB

Open AccessArticle

CFD Studies of the Effects of Waveform on Swimming Performance of Carangiform Fish

by Zuo Cui^*, Xingshi Gu, Kangkang Li and Hongzhou Jiang

Harbin Institute of Technology, Department of Mechanical Engineering, Harbin 150001, China

Appl. Sci. 2017, 7(2), 149; https://doi.org/10.3390/app7020149 - 8 Feb 2017

Cited by 28 | Viewed by 7281

Abstract

Carangiform fish, like mackerel, saithe and bass, swim forward by rhythmically passing body waves from the head to the tail. In this paper, the undulating motions are decomposed into the travelling part and the standing part by complex orthogonal decomposition (COD), and the [...] Read more.

Carangiform fish, like mackerel, saithe and bass, swim forward by rhythmically passing body waves from the head to the tail. In this paper, the undulating motions are decomposed into the travelling part and the standing part by complex orthogonal decomposition (COD), and the ratio between these two parts, i.e., the travelling index, is proposed to analyse the waveform of fish-like movements. To further study the relative influences of the waveform on swimming performance, a self-propelled model of carangiform fish is developed by the level set/immersed boundary (LS-IB) method, and the in-house code is tested by two cases of flow past a sphere and an oscillating cylinder, respectively. In this study, the travelling index is varied in ranges up to 50% larger or smaller than the biological data. The results show that carangiform fish seem to favour a fast and efficient swimming motion with a travelling index of around 0.6. Meanwhile, we study several numerical cases with different amplitude coefficients (0.5~1.1) and tail-beat frequency (2 Hz~5 Hz), and then compare their swimming performance with each other. We found that the forward speed is closely related to the travelling index and tail-beat frequency, while the swimming efficiency is increased with the tail-beat frequency and amplitude coefficient. These results are also consistent with biological observations, and they might provide beneficial guidance with respect to the future design of robotic fish. Full article

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17 pages, 3650 KiB

Open AccessCommunication

Driver Fatigue Detection System Using Electroencephalography Signals Based on Combined Entropy Features

by Zhendong Mu, Jianfeng Hu^*

and Jianliang Min

The Center of Collaboration and Innovation, Jiangxi University of Technology, Nanchang 330098, Jiangxi, China

Appl. Sci. 2017, 7(2), 150; https://doi.org/10.3390/app7020150 - 6 Feb 2017

Cited by 110 | Viewed by 8178

Abstract

Driver fatigue has become one of the major causes of traffic accidents, and is a complicated physiological process. However, there is no effective method to detect driving fatigue. Electroencephalography (EEG) signals are complex, unstable, and non-linear; non-linear analysis methods, such as entropy, maybe [...] Read more.

Driver fatigue has become one of the major causes of traffic accidents, and is a complicated physiological process. However, there is no effective method to detect driving fatigue. Electroencephalography (EEG) signals are complex, unstable, and non-linear; non-linear analysis methods, such as entropy, maybe more appropriate. This study evaluates a combined entropy-based processing method of EEG data to detect driver fatigue. In this paper, 12 subjects were selected to take part in an experiment, obeying driving training in a virtual environment under the instruction of the operator. Four types of enthrones (spectrum entropy, approximate entropy, sample entropy and fuzzy entropy) were used to extract features for the purpose of driver fatigue detection. Electrode selection process and a support vector machine (SVM) classification algorithm were also proposed. The average recognition accuracy was 98.75%. Retrospective analysis of the EEG showed that the extracted features from electrodes T5, TP7, TP8 and FP1 may yield better performance. SVM classification algorithm using radial basis function as kernel function obtained better results. A combined entropy-based method demonstrates good classification performance for studying driver fatigue detection. Full article

(This article belongs to the Special Issue Application of Signal Processing Methods for Systematic Analysis of Physiological Health)

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21 pages, 4816 KiB

Open AccessArticle

PSF Estimation of Space-Variant Ultra-Wide Field of View Imaging Systems

by Petr Janout^*

, Petr Páta

, Petr Skala and Jan Bednář

Department of Radioelectronics, Faculty of Electrical Engineering, Czech Technical University in Prague, Technická 2, 166 27 Prague 6, Czech Republic

Appl. Sci. 2017, 7(2), 151; https://doi.org/10.3390/app7020151 - 8 Feb 2017

Cited by 10 | Viewed by 6349

Abstract

Ultra-wide-field of view (UWFOV) imaging systems are affected by various aberrations, most of which are highly angle-dependent. A description of UWFOV imaging systems, such as microscopy optics, security camera systems and other special space-variant imaging systems, is a difficult task that can be [...] Read more.

Ultra-wide-field of view (UWFOV) imaging systems are affected by various aberrations, most of which are highly angle-dependent. A description of UWFOV imaging systems, such as microscopy optics, security camera systems and other special space-variant imaging systems, is a difficult task that can be achieved by estimating the Point Spread Function (PSF) of the system. This paper proposes a novel method for modeling the space-variant PSF of an imaging system using the Zernike polynomials wavefront description. The PSF estimation algorithm is based on obtaining field-dependent expansion coefficients of the Zernike polynomials by fitting real image data of the analyzed imaging system using an iterative approach in an initial estimate of the fitting parameters to ensure convergence robustness. The method is promising as an alternative to the standard approach based on Shack–Hartmann interferometry, since the estimate of the aberration coefficients is processed directly in the image plane. This approach is tested on simulated and laboratory-acquired image data that generally show good agreement. The resulting data are compared with the results of other modeling methods. The proposed PSF estimation method provides around 5% accuracy of the optical system model. Full article

(This article belongs to the Section Optics and Lasers)

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16 pages, 6653 KiB

Open AccessArticle

Design of a Tubular Permanent Magnet Actuator for Active Lateral Secondary Suspension of a Railway Vehicle

by Jun-Ho Yoon¹, Dongwook Kim¹

, No-Cheol Park^1,* and Young-Pil Park²

¹ Department of Mechanical Engineering, Yonsei University, Seoul 03722, Korea

² Center for Information Storage Device, Yonsei University, Seoul 03722, Korea

Appl. Sci. 2017, 7(2), 152; https://doi.org/10.3390/app7020152 - 8 Feb 2017

Cited by 5 | Viewed by 9249

Abstract

This paper describes the finite element (FE)-based design of a slotted tubular permanent magnet actuator (TPMA) used in railway vehicle active lateral secondary suspension that improves the actuator’s thrust and lowers its cogging force under thermal and geometric constraints. To consider the electromagnetic [...] Read more.

This paper describes the finite element (FE)-based design of a slotted tubular permanent magnet actuator (TPMA) used in railway vehicle active lateral secondary suspension that improves the actuator’s thrust and lowers its cogging force under thermal and geometric constraints. To consider the electromagnetic and thermal fields and the complex interactions among the design variables, design was carried out in an electromagnet and thermal field environment using accurate and time-effective FE analysis. A six-slot prototype model was fabricated to estimate critical thermal parameters, which are difficult to compute without experiments. Three-dimensional FE analysis using the determined thermal parameters was adopted to calculate the precise thermal distribution of the TPMA and verify the forced air-cooling effect. A prototype TPMA with a quasi-Halbach array of permanent magnets and a moving magnet was manufactured through the FE-based design process; the dynamic, electromagnetic, and thermal characteristics of the prototype TPMA were validated experimentally. Full article

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17 pages, 3495 KiB

Open AccessArticle

Effects of a Nano-Silica Additive on the Rock Erosion Characteristics of a SC-CO₂ Jet under Various Operating Conditions

by Man Huang^1,2, Yong Kang^1,2,*, Xinping Long^1,2, Xiaochuan Wang^1,2, Yi Hu^1,2, Deng Li^1,2 and Mingxing Zhang^1,2

¹ School of Power and Mechanical Engineering, Wuhan University, Wuhan 430000, China

² Hubei Key Laboratory of Water Jet Theory and New Technology, Wuhan University, Wuhan 430000, China

Appl. Sci. 2017, 7(2), 153; https://doi.org/10.3390/app7020153 - 8 Feb 2017

Cited by 15 | Viewed by 4941

Abstract

In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO₂) jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO₂ jets with nano-silica mass fractions of 0 wt [...] Read more.

In order to improve the erosion capacity of a supercritical carbon dioxide (SC-CO₂) jet, the influence of a nano-silica additive on the rock erosion characteristics was experimentally investigated. By impinging the SC-CO₂ jets with nano-silica mass fractions of 0 wt % (pure SC-CO₂ jet), 3 wt %, 6 wt %, 9 wt %, 12 wt %, 15 wt %, and 18 wt % on specimens of red sandstone, the erosion volumes under various operating conditions were measured and analyzed. Results show that an appropriate amount of nano-silica additive can greatly enhance the erosion ability of a SC-CO₂ jet. The effect on the erosion ability largely depends on the operating conditions. For instance, when the other conditions are fixed, 6 wt %, 9 wt %, 12 wt %, and 15 wt % were the optimum mass fractions, successively, with the inlet pressure increasing from 30 MPa to 60 MPa. With the increase in ambient pressure, the optimum mass fraction is unchanged under the constant inlet pressure, while it increases under the constant pressure drop. Additionally, the optimum mass fraction decreases when the fluid temperature increases. In addition, the optimal standoff distances are about five times the nozzle diameter of the nano-silica SC-CO₂ jet, and three times for the pure jet. This research provides a new method for effectively enhancing the rock erosion performance of a SC-CO₂ jet. Full article

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

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23 pages, 6185 KiB

Open AccessArticle

A Scalable Parallel Architecture Based on Many-Core Processors for Generating HTTP Traffic

by Xinheng Wang^*, Chuan Xu

, Wenqiang Jin, Jiajie Wang, Qianyun Wang and Guofeng Zhao

Future Network Research Center, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

Appl. Sci. 2017, 7(2), 154; https://doi.org/10.3390/app7020154 - 8 Feb 2017

Viewed by 4886

Abstract

The past years have witnessed the significant development of the Internet. Numerous emerging network architectures and protocols have triggered the demand for traffic generators which stand in stark contrast to previous schemes. Namely, fixed test content is inefficient in the presence of such [...] Read more.

The past years have witnessed the significant development of the Internet. Numerous emerging network architectures and protocols have triggered the demand for traffic generators which stand in stark contrast to previous schemes. Namely, fixed test content is inefficient in the presence of such a dynamic and realistic demand. Moreover, the requirement of high-performance has raised the stakes on developing a new concurrent system. In this paper, we present a hierarchical parallel design for a Web traffic generator on a TILERAGX36 processor, called TGMP. We discuss the challenges in developing its hierarchical architectural design, and elaborate on its implementation details. Specifically, in order to generate a realistic network workload over a long and large time scale, we propose a user-control scheme based on cubic spline interpolation. To better improve the scalability of the system and satisfy the required flow rate, we adopt techniques, including optimization of parameters under the Linux kernel, event-driven concurrency, and parallel architectures of a TILERAGX36 processor. The experimental results demonstrate that TGMP is able to create real traffic and simulate 50,000 users accessing the Web server simultaneously. Full article

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15 pages, 3613 KiB

Open AccessArticle

Electrical Energy Forecasting and Optimal Allocation of ESS in a Hybrid Wind-Diesel Power System

by Hai Lan¹, He Yin¹, Shuli Wen^1,*, Ying-Yi Hong²

, David C. Yu³ and Lijun Zhang¹

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

² Department of Electrical Engineering, Chung Yuan Christian University, Chung Li District 320, Taoyuan City 32023, Taiwan

³ Department of Electrical Engineering and Computer Science, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA

Appl. Sci. 2017, 7(2), 155; https://doi.org/10.3390/app7020155 - 14 Feb 2017

Cited by 15 | Viewed by 5717

Abstract

Due to the increasingly serious energy crisis and environmental pollution problem, traditional fossil energy is gradually being replaced by renewable energy in recent years. However, the introduction of renewable energy into power systems will lead to large voltage fluctuations and high capital costs. [...] Read more.

Due to the increasingly serious energy crisis and environmental pollution problem, traditional fossil energy is gradually being replaced by renewable energy in recent years. However, the introduction of renewable energy into power systems will lead to large voltage fluctuations and high capital costs. To solve these problems, an energy storage system (ESS) is employed into a power system to reduce total costs and greenhouse gas emissions. Hence, this paper proposes a two-stage method based on a back-propagation neural network (BPNN) and hybrid multi-objective particle swarm optimization (HMOPSO) to determine the optimal placements and sizes of ESSs in a transmission system. Owing to the uncertainties of renewable energy, a BPNN is utilized to forecast the outputs of the wind power and load demand based on historic data in the city of Madison, USA. Furthermore, power-voltage (P-V) sensitivity analysis is conducted in this paper to improve the converge speed of the proposed algorithm, and continuous wind distribution is discretized by a three-point estimation method. The Institute of Electrical and Electronic Engineers (IEEE) 30-bus system is adopted to perform case studies. The simulation results of each case clearly demonstrate the necessity for optimal storage allocation and the efficiency of the proposed method. Full article

(This article belongs to the Special Issue Advances in Integrated Energy Systems Design, Control and Optimization)

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11 pages, 1863 KiB

Open AccessArticle

Adhesion Evaluation of Asphalt-Aggregate Interface Using Surface Free Energy Method

by Jie Ji¹, Hui Yao^2,3,*

, Luhou Liu¹, Zhi Suo¹, Peng Zhai¹, Xu Yang² and Zhanping You²

¹ School of Civil Engineering and Transportation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China

² Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA

³ School of Traffic and Transportation Engineering, Changsha University of Science and Technology, Changsha 410114, China

Appl. Sci. 2017, 7(2), 156; https://doi.org/10.3390/app7020156 - 9 Feb 2017

Cited by 34 | Viewed by 5915

Abstract

The influence of organic additives (Sasobit and RH) and water on the adhesion of the asphalt-aggregate interface was studied according to the surface free energy theory. Two asphalt binders (SK-70 and SK-90), and two aggregate types (limestone and basalt) were used in this [...] Read more.

The influence of organic additives (Sasobit and RH) and water on the adhesion of the asphalt-aggregate interface was studied according to the surface free energy theory. Two asphalt binders (SK-70 and SK-90), and two aggregate types (limestone and basalt) were used in this study. The sessile drop method was employed to test surface free energy components of asphalt, organic additives and aggregates. The adhesion models of the asphalt-aggregate interface in dry and wet conditions were established, and the adhesion work was calculated subsequently. The energy ratios were built to evaluate the effect of organic additives and water on the adhesiveness of the asphalt-aggregate interface. The results indicate that the addition of organic additives can enhance the adhesion of the asphalt-aggregate interface in dry conditions, because organic additives reduced the surface free energy of asphalt. However, the organic additives have hydrophobic characteristics and are sensitive to water. As a result, the adhesiveness of the asphalt-aggregate interface of the asphalt containing organic additives in wet conditions sharply decreased due to water damage to asphalt and organic additives. Furthermore, the compatibility of asphalt, aggregate with organic additive was noted and discussed. Full article

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

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15 pages, 35962 KiB

Open AccessArticle

Analysis of the Hazard, Vulnerability, and Exposure to the Risk of Flooding (Alba de Yeltes, Salamanca, Spain)

by Sergio Veleda¹, Antonio Martínez-Graña^1,*

, Fernando Santos-Francés²

, Javier Sánchez-SanRoman¹ and Marco Criado¹

¹ Department of Geology, Faculty of Sciences, University of Salamanca, Salamanca 37008, Spain

² Department of Soil Sciences, Faculty of Environmental Sciences, University of Salamanca, Salamanca 37007, Spain

Appl. Sci. 2017, 7(2), 157; https://doi.org/10.3390/app7020157 - 8 Feb 2017

Cited by 18 | Viewed by 5223

Abstract

The present work has developed a method using GIS technology to evaluate the danger, vulnerability, and exposure to the risk of flooding in the Alba de Yeltes area (Salamanca, Spain). It is a non-structural measure for the prevention and mitigation of the risk [...] Read more.

The present work has developed a method using GIS technology to evaluate the danger, vulnerability, and exposure to the risk of flooding in the Alba de Yeltes area (Salamanca, Spain). It is a non-structural measure for the prevention and mitigation of the risk of extraordinary flooding. After completing a full analysis of the physical environment (climate, geology, geomorphology, hydrology, hydrogeology, and land use), hydrological-hydraulic modeling was carried out using the GeoHecRas river analysis software. The results obtained from the analysis and the models have generated a danger map that facilitates the efficient evaluation of the spatial distribution of the different severity parameters (depth of the watersheet, current flow rate, and flood-prone areas). Also, map algebra and the databases associated with GIS tools, together with the vulnerability and exposure cartography, have allowed the risk to be analyzed in an integrate manner and the production of an environmental diagnostic map. The results of this study propose that there are inhabited areas close to the Yeltes-Morasverdes riverbed that have a high risk of flooding, indicating the need for proper land planning and the implementation of a series of measures that will help to reduce the risk of flooding and its impact. Full article

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10 pages, 1475 KiB

Open AccessArticle

Fault Diagnosis of Roller Bearings Based on a Wavelet Neural Network and Manifold Learning

by Lifeng Wu^1,2,3, Beibei Yao^1,2,3, Zhen Peng⁴ and Yong Guan^1,2,3,*

¹ College of Information Engineering, Capital Normal University, Beijing 100048, China

² Beijing Engineering Research Center of Highly Reliable Embedded Systems, Capital Normal University, Beijing 100048, China

³ Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100048, China

⁴ Information Management Department, Beijing Institute of Petrochemical Technology, Beijing 102617, Beijing, China

Appl. Sci. 2017, 7(2), 158; https://doi.org/10.3390/app7020158 - 8 Feb 2017

Cited by 40 | Viewed by 4619

Abstract

In order to improve the accuracy of the fault diagnosis of roller bearings, this paper proposes a kind of fault diagnosis algorithm based on manifold learning combined with a wavelet neural network. First, a high-dimensional feature signal set is obtained using a conventional [...] Read more.

In order to improve the accuracy of the fault diagnosis of roller bearings, this paper proposes a kind of fault diagnosis algorithm based on manifold learning combined with a wavelet neural network. First, a high-dimensional feature signal set is obtained using a conventional feature extraction algorithm; second, an improved Laplacian characteristic mapping algorithm is proposed to reduce the dimensions of the characteristics and obtain an effective characteristic signal. Finally, the processed characteristic signal is inputted into the constructed wavelet neural network whose output is the types of fault. In the actual experiment of recognizing data sets on roller bearing failures, the validity and accuracy of the method for diagnosing faults was verified. Full article

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9 pages, 992 KiB

Open AccessLetter

A Hybrid Model Algorithm for Hypersonic Glide Vehicle Maneuver Tracking Based on the Aerodynamic Model

by Yu Fan^*

, Fang Lu, Wuxuan Zhu, Guangzhou Bai and Liang Yan

Beijing Institute of Tracking and Telecommunications Technology, No. 26 Beiqing Road, Beijing 100094, China

Appl. Sci. 2017, 7(2), 159; https://doi.org/10.3390/app7020159 - 8 Feb 2017

Cited by 19 | Viewed by 5624

Abstract

In order to solve the problem of an uncertain initial state and big errors for hypersonic glide vehicle (HGV) tracking, a hybrid model algorithm is proposed by combining a single model algorithm with a multiple model algorithm. To develop the tracking algorithm with [...] Read more.

In order to solve the problem of an uncertain initial state and big errors for hypersonic glide vehicle (HGV) tracking, a hybrid model algorithm is proposed by combining a single model algorithm with a multiple model algorithm. To develop the tracking algorithm with the Cubature Kalman filter, in every model filter the process equation is established based on the HGV aerodynamic model and the measurement equation is established based on the radar measurement principle. The proposed hybrid model algorithm is developed by using the multiple model algorithm in the initial tracking stage and using the single model algorithm in the stable tracking stage, and they are divided by a proposed parameter. The former can avoid divergence and reduce the errors caused by the uncertain initial state. The latter can track the HGV at higher accuracy. The simulation indicates that the proposed hybrid model has high speed accuracy in the whole tracking stage and high position accuracy in the stable tracking stage. The average position root mean square error (RMSE) using the hybrid model algorithm is almost the same as that using the single model algorithm but the average speed RMSE using the single model algorithm is about 30% greater than that using the hybrid model algorithm. In a system for defending the HGV, the speed accuracy has more effect on the trajectory prediction as time goes on. Thus, the hybrid model algorithm is an engineering algorithm for HGVs with high accuracy. In future research, the hybrid model algorithm will be studied for general maneuvering target tracking. Full article

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9 pages, 2510 KiB

Open AccessArticle

Phenylalanine-Rich Peptide Mediated Binding with Graphene Oxide and Bioinspired Synthesis of Silver Nanoparticles for Electrochemical Sensing

by Li Wang^* and Jing Lin

College of Chemistry, Jilin Normal University, Siping 136000, China

Appl. Sci. 2017, 7(2), 160; https://doi.org/10.3390/app7020160 - 8 Feb 2017

Cited by 17 | Viewed by 5863

Abstract

We demonstrated that a phenylalanine-rich peptide molecule, (FEFEFKFK)2, could be used for the biofunctionalization of graphene oxide (GO) and the bioinspired synthesis of silver nanoparticles (AgNPs) for the creation of functional GO–AgNPs nanohybrids. The successful synthesis of GO–AgNPs nanohybrids was proven by the [...] Read more.

We demonstrated that a phenylalanine-rich peptide molecule, (FEFEFKFK)2, could be used for the biofunctionalization of graphene oxide (GO) and the bioinspired synthesis of silver nanoparticles (AgNPs) for the creation of functional GO–AgNPs nanohybrids. The successful synthesis of GO–AgNPs nanohybrids was proven by the characterizations of atomic force microscopy, transmission electron microscope, and X-ray photoelectron spectroscopy. The fabricated electrochemical H2O2 sensor based on the synthesized GO–AgNPs nanohybrids showed high performances with a linear detection range 0.02–18 mM and a detection limit of 0.13 μM. The design of graphene-binding peptides is of benefit to the biofunctionalization of graphene-based materials, the synthesis of novel graphene–peptide nanohybrids, and the potential applications of graphene in biomedical fields. Full article

(This article belongs to the Special Issue Graphene and Graphene Oxide in Biomedical Application)

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18 pages, 2565 KiB

Open AccessArticle

A Geometric Dictionary Learning Based Approach for Fluorescence Spectroscopy Image Fusion

by Zhiqin Zhu^1,2, Guanqiu Qi^1,3,*

, Yi Chai² and Penghua Li¹

¹ College of Automation, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

² State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044, China

³ School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, AZ 85287, USA

Appl. Sci. 2017, 7(2), 161; https://doi.org/10.3390/app7020161 - 9 Feb 2017

Cited by 28 | Viewed by 5029

Abstract

In recent years, sparse representation approaches have been integrated into multi-focus image fusion methods. The fused images of sparse-representation-based image fusion methods show great performance. Constructing an informative dictionary is a key step for sparsity-based image fusion method. In order to ensure sufficient [...] Read more.

In recent years, sparse representation approaches have been integrated into multi-focus image fusion methods. The fused images of sparse-representation-based image fusion methods show great performance. Constructing an informative dictionary is a key step for sparsity-based image fusion method. In order to ensure sufficient number of useful bases for sparse representation in the process of informative dictionary construction, image patches from all source images are classified into different groups based on geometric similarities. The key information of each image-patch group is extracted by principle component analysis (PCA) to build dictionary. According to the constructed dictionary, image patches are converted to sparse coefficients by simultaneous orthogonal matching pursuit (SOMP) algorithm for representing the source multi-focus images. At last the sparse coefficients are fused by Max-L1 fusion rule and inverted to fused image. Due to the limitation of microscope, the fluorescence image cannot be fully focused. The proposed multi-focus image fusion solution is applied to fluorescence imaging area for generating all-in-focus images. The comparison experimentation results confirm the feasibility and effectiveness of the proposed multi-focus image fusion solution. Full article

(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)

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21 pages, 4756 KiB

Open AccessArticle

Structural Performance of Composite Shear Walls under Compression

by Tingyue Hao^1,2, Wanlin Cao^1,3,*, Qiyun Qiao¹, Yan Liu^1,4 and Wenbin Zheng¹

¹ Key Laboratory of Urban Security and Disaster Engineering (Beijing University of Technology), Ministry of Education, Beijing 100124, China

² School of Civil Engineering, Tangshan University, Tangshan 063000, China

³ Beijing Collaborative Innovation Center for Metropolitan Transportation, Beijing University of Technology, Beijing 100124, China

⁴ College of Civil and Architectural Engineering, North China University of Science and Technology, Tangshan 063000, China

Appl. Sci. 2017, 7(2), 162; https://doi.org/10.3390/app7020162 - 9 Feb 2017

Cited by 16 | Viewed by 4463

Abstract

In order to research the effect of different layout forms of steel plate on the axial compression behavior of a steel plate-concrete composite shear wall, this paper presents the experimental results and analysis of the axial compression behavior of a composite shear wall, [...] Read more.

In order to research the effect of different layout forms of steel plate on the axial compression behavior of a steel plate-concrete composite shear wall, this paper presents the experimental results and analysis of the axial compression behavior of a composite shear wall, with different layout forms of steel plate. A total of three tests were carried out, composed of two composite walls with built-in steel plate, and one composite wall with two skins of steel plate. The gross dimensions of the three specimens were 1206 mm × 2006 mm × 300 mm. Experimental results show that the composite wall with two skins of steel plate has an optimal ability of elastic-plastic deformation, and the maximum axial compressive bearing capacity among the three specimens. Using the energy method, the critical local buckling stresses of steel plate were calculated, and compared with the yield stresses. According to different confined actions of concrete, concrete constitutive models were proposed, and the axial compressive strengths of confined concrete were calculated. Considering the local buckling of steel plate and confined concrete, the calculation formula of the axial compression of the composite wall was put forward, and the calculated results were in good agreement with the test results. Therefore, the different layout forms of steel plate have a great influence on its buckling, and on the concrete inhibition effect, which can affect the axial compressive bearing capacity of the composite wall. Full article

(This article belongs to the Special Issue Applications of Thin-Walled Structures)

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11 pages, 2667 KiB

Open AccessArticle

Multi-Objective Configuration Optimization of a Hybrid Energy Storage System

by Shan Cheng¹, Wei-Bin Sun² and Wen-Li Liu^2,*

¹ Hubei Provincial Collaborative Innovation Center for New Energy Microgrid (China Three Gorges University), Yichang 443002, China

² College of Electrical Engineering and New Energy, China Three Gorges University, Yichang 443002, China

Appl. Sci. 2017, 7(2), 163; https://doi.org/10.3390/app7020163 - 13 Feb 2017

Cited by 14 | Viewed by 4493

Abstract

This study aims to investigate multi-objective configuration optimization of a hybrid energy storage system (HESS). In order to maximize the stability of the wind power output with minimized HESS investment, a multi-objective model for optimal HESS configuration has been established, which proposes decreasing [...] Read more.

This study aims to investigate multi-objective configuration optimization of a hybrid energy storage system (HESS). In order to maximize the stability of the wind power output with minimized HESS investment, a multi-objective model for optimal HESS configuration has been established, which proposes decreasing the installation and operation & maintenance costs of an HESS and improving the compensation satisfaction rate of wind power fluctuation. Besides, fuzzy control has been used to allocate power in the HESS for lengthening battery lifetime and ensuring HESS with enough energy to compensate the fluctuation of the next time interval. Instead of converting multiple objectives into one, a multi-objective particle swarm optimization with integration of bacteria quorum sensing and circular elimination (BC-MOPSO) has been applied to provide diverse alternative solutions. In order to illustrate the feasibility and effectiveness of the proposed model and the application of BC-MOPSO, simulations along with analysis and discussion are carried out. The results verified the feasibility and effectiveness of the proposed approach. Full article

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

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14 pages, 3278 KiB

Open AccessArticle

Vibration-Based Signal Analysis for Shearer Cutting Status Recognition Based on Local Mean Decomposition and Fuzzy C-Means Clustering

by Lei Si^1,2

, Zhongbin Wang^1,*, Chao Tan¹ and Xinhua Liu¹

¹ School of Mechatronic Engineering, China University of Mining & Technology, No. 1 Daxue Road, Xuzhou 221116, China

² School of Information and Electrical Engineering, China University of Mining & Technology, No. 1 Daxue Road, Xuzhou 221116, China

Appl. Sci. 2017, 7(2), 164; https://doi.org/10.3390/app7020164 - 9 Feb 2017

Cited by 16 | Viewed by 3617

Abstract

In order to accurately acquire shearer cutting status, this paper proposed a pattern recognition method, based on the local mean decomposition (LMD), time-frequency statistical analysis, improved Laplacian score (LS), and fuzzy C-means (FCM) clustering algorithm. The LMD was employed to preprocess the vibration [...] Read more.

In order to accurately acquire shearer cutting status, this paper proposed a pattern recognition method, based on the local mean decomposition (LMD), time-frequency statistical analysis, improved Laplacian score (LS), and fuzzy C-means (FCM) clustering algorithm. The LMD was employed to preprocess the vibration signals of shear cutting coal seam, and several product functions (PFs) were obtained. Following this, 14 time-frequency statistical parameters of the original signal and optimal PF were extracted. Additionally, the improved LS algorithm was designed to ensure the accurate estimation of features, and a new feature vector could be selected. Subsequently, the obtained eigenvector matrix was fed into a FCM to be clustered, for optimal clustering performance. The experimental examples were provided to verify the effectiveness of the methodology and the results indicated that the proposed algorithm could be applied to recognize the different categories of shearer cutting status. Full article

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14 pages, 21325 KiB

Open AccessArticle

Measurement and Analysis of Channel Characteristics in Reflective Environments at 3.6 GHz and 14.6 GHz

by Xin Zhou^1,2, Zhangdui Zhong¹, Xin Bian², Ruisi He^1,*

, Ruoyu Sun³

, Ke Guan¹, Ke Liu² and Xiaotao Guo²

¹ State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China

² Division of Electronics and Information Technology, National Institute of Metrology, Beijing 100013, China

³ Communications Technology Laboratory, National Institute of Standards and Technology, Boulder, CO 80303, USA

Appl. Sci. 2017, 7(2), 165; https://doi.org/10.3390/app7020165 - 13 Feb 2017

Cited by 3 | Viewed by 4286

Abstract

Recently, high frequency bands (above 6 GHz) have attracted more attention for the next generation communication systems due to the limited frequency resources below 6 GHz. To reveal the influence of frequency on propagation channels, channel characterization results at 14.6 and 3.6 GHz [...] Read more.

Recently, high frequency bands (above 6 GHz) have attracted more attention for the next generation communication systems due to the limited frequency resources below 6 GHz. To reveal the influence of frequency on propagation channels, channel characterization results at 14.6 and 3.6 GHz bands based on measurements in an indoor scenario and in a reverberation chamber are presented. The measurement results indicate minimal differences in path loss exponents, shadow fading standard deviation, root-mean-square (RMS) delay spread and coherence bandwidth for the two frequency bands, while the path loss at 14.6 GHz band is clearly larger than that at the 3.6 GHz band. Furthermore, the underlying factors that influence the channel characteristics are investigated. It is found that the RMS delay spread is independent of the frequency in the scenario where free space propagation and/or reflection are the main mechanisms. Measurements in the reverberation chamber verify this inference. Full article

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16 pages, 1722 KiB

Open AccessArticle

Microbial Succession and the Dynamics of Chemical Compounds during the Solid-State Fermentation of Pu-erh Tea

by Yan Ma¹, Shuangmei Duan¹, Donglian Zhang¹, Xiaoqin Su¹, Dongying Zhang¹, Caiyou Lv^1,* and Ming Zhao^1,2,*

¹ College of Longrun Pu-erh Tea, Yunnan Agricultural University, Kunming 650201, China

² State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Kunming 650201, China

Appl. Sci. 2017, 7(2), 166; https://doi.org/10.3390/app7020166 - 10 Feb 2017

Cited by 42 | Viewed by 6883

Abstract

An in-depth knowledge of the microbiota and metabolites in the solid-state fermentation (SSF) of Post-fermented Pu-erh tea (Pu-erh Shucha, PFPT), a Chinese traditional tea with various health benefits, is essential to develop modern fermentation technology. In this work, the microbial diversity and succession [...] Read more.

An in-depth knowledge of the microbiota and metabolites in the solid-state fermentation (SSF) of Post-fermented Pu-erh tea (Pu-erh Shucha, PFPT), a Chinese traditional tea with various health benefits, is essential to develop modern fermentation technology. In this work, the microbial diversity and succession in two laboratory-developed SSF protocols for PFPT were investigated using pyrosequencing analyses of the bacterial 16S rRNA and fungal 18S rRNA genes. The active bacteria in the initial stages of SSF (seven days) were from the raw materials and environment, with a dominance of Proteobacteria in both the raw materials and SSF after seven days. The environmental bacteria were inoculated into the tea mass throughout the fermentation process and multiplied, with a dominance of Firmicutes at day 14 and 21, and then Firmicutes and Actinobacteria at the last stages of fermentation (day 28 and 35). The dominant fungi came from the raw material and were identified at the genus level as Aspergillus throughout the SSF process. The contents of tea polyphenols, free amino acids, gallic acid, theaflavin, thearubigin, and catechins decreased significantly (p < 0.05), while the level of theabrownin increased significantly (p < 0.05). The caffeine content showed no significant change (p > 0.05). In total, 30 bacterial and three fungal genera showed significant correlations to 1–8 and 3–4 identified tea compounds, respectively (p < 0.05). The dynamics of the microbiota and chemical compounds, and correlations between their changes in the SSF of PFPT were revealed, and present a foundation for further studies on the microbial effects on chemical compounds. Full article

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18 pages, 5622 KiB

Open AccessArticle

A Single-Stage High-Power-Factor Light-Emitting Diode (LED) Driver with Coupled Inductors for Streetlight Applications

by Chun-An Cheng, Chien-Hsuan Chang

, Hung-Liang Cheng^*, Ching-Hsien Tseng and Tsung-Yuan Chung

Department of Electrical Engineering, I-Shou University, Dashu District, Kaohsiung City 84001, Taiwan

Appl. Sci. 2017, 7(2), 167; https://doi.org/10.3390/app7020167 - 10 Feb 2017

Cited by 9 | Viewed by 7074

Abstract

This paper presents and implements a single-stage high-power-factor light-emitting diode (LED) driver with coupled inductors, suitable for streetlight applications. The presented LED driver integrates an interleaved buck-boost power factor correction (PFC) converter with coupled inductors and a half-bridge-type series-resonant converter cascaded with a [...] Read more.

This paper presents and implements a single-stage high-power-factor light-emitting diode (LED) driver with coupled inductors, suitable for streetlight applications. The presented LED driver integrates an interleaved buck-boost power factor correction (PFC) converter with coupled inductors and a half-bridge-type series-resonant converter cascaded with a full-bridge rectifier into a single-stage power conversion circuit. Coupled inductors inside the interleaved buck-boost PFC converter sub-circuit are designed to operate in discontinuous conduction mode (DCM) for achieving input-current shaping, and the half-bridge-type series resonant converter cascaded with a full-bridge rectifier is designed for obtaining zero-voltage switching (ZVS) on two power switches to reduce their switching losses. Analysis of operational modes and design equations for the presented LED driver are described and included. In addition, the presented driver features a high power factor, low total harmonic distortion (THD) of input current, and soft switching. Finally, a prototype driver is developed and implemented to supply a 165-W-rated LED streetlight module with utility-line input voltages ranging from 210 to 230 V. Experimental results demonstrate that high power factor (>0.99), low utility-line current THD (<7%), low-output voltage ripples (<1%), low-output current ripples (<10%), and high circuit efficiency (>90%) are obtained in the presented single-stage driver for LED streetlight applications. Full article

(This article belongs to the Special Issue Selected Papers from International Conference on Applied System Innovation 2016)

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20 pages, 3135 KiB

Open AccessArticle

Remedial Modelling of Steel Bridges through Application of Analytical Hierarchy Process (AHP)

by Maria Rashidi^1,*, Maryam Ghodrat¹, Bijan Samali¹, Brett Kendall² and Chunwei Zhang¹

¹ Centre for Infrastructure Engineering, Western Sydney University, Penrith 2751, Australia

² Road and Maritime Services (RMS), Werrington 2747, Australia

Appl. Sci. 2017, 7(2), 168; https://doi.org/10.3390/app7020168 - 10 Feb 2017

Cited by 52 | Viewed by 8757

Abstract

The deterioration and failure of steel bridges around the world is of growing concern for asset managers and bridge engineers due to aging, increasing volume of traffic and introduction of heavier vehicles. Hence, a model that considers these heuristics can be employed to [...] Read more.

The deterioration and failure of steel bridges around the world is of growing concern for asset managers and bridge engineers due to aging, increasing volume of traffic and introduction of heavier vehicles. Hence, a model that considers these heuristics can be employed to validate or challenge the practical engineering decisions. Moreover, in a time of increased litigation and economic unrest, engineers require a means of accountability to support their decisions. Maintenance, Repair and Rehabilitation (MR&R) of deteriorating bridge structures are considered as expensive actions for transportation agencies and the cost of error in decision making may aggravate problems related to infrastructure funding system. The subjective nature of decision making in this field could be replaced by the application of a Decision Support System (DSS) that supports asset managers through balanced consideration of multiple criteria. The main aim of this paper is to present the developed decision support system for asset management of steel bridges within acceptable limits of safety, functionality and sustainability. The Simplified Analytical Hierarchy Process S-AHP is applied as a multi criteria decision making technique. The model can serve as an integrated learning tool for novice engineers, or as an accountability tool for assurance to project stakeholders. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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20 pages, 9745 KiB

Open AccessArticle

Field Monitoring of Deformations and Internal Forces of Surrounding Rocks and Lining Structures in the Construction of the Gangkou Double-Arched Tunnel—A Case Study

by Qixiang Yan¹, Chuan Zhang¹

, Gang Lin² and Bo Wang^1,*

¹ Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, Sichuan, China

² China Railway Eryuan Engineering Group Co., Ltd., Chengdu 610031, Sichuan, China

Appl. Sci. 2017, 7(2), 169; https://doi.org/10.3390/app7020169 - 11 Feb 2017

Cited by 30 | Viewed by 8052

Abstract

Double-arched tunnel is a special and complex underground structure which needs to be monitored carefully during construction. Taking the Gangkou tunnel as the engineering background, this paper presents a case study of field monitoring of a representative double-arched tunnel. Typical cross sections were [...] Read more.

Double-arched tunnel is a special and complex underground structure which needs to be monitored carefully during construction. Taking the Gangkou tunnel as the engineering background, this paper presents a case study of field monitoring of a representative double-arched tunnel. Typical cross sections were chosen in each class of surrounding rock masses in the tunnel area and different types of sensors were embedded in designed locations, and the deformations and forces of both surrounding rocks and lining structures were monitored systematically. The dynamic evolution as well as the spatial distribution characteristics of the monitoring data including the internal displacements of surrounding rocks and the contact pressures between surrounding rocks and primary linings, the axial forces in rock bolts and the internal forces in both steel arches and secondary linings were analyzed. The monitoring and analysis results show that the deformations and forces of both surrounding rocks and lining structures are directly related to the construction procedures, geological conditions and locations in the double-arched tunnel. According to the results, some reasonable suggestions were provided for the improvement of the tunnel construction. This study will provide useful reference and guidance for the design, construction and monitoring of similar engineering projects in future. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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10 pages, 1446 KiB

Open AccessArticle

Electrical Impedance Spectroscopy for Detection of Cells in Suspensions Using Microfluidic Device with Integrated Microneedles

by Muhammad Asraf Mansor¹, Masaru Takeuchi²

, Masahiro Nakajima², Yasuhisa Hasegawa² and Mohd Ridzuan Ahmad^3,*

¹ Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia

² Department of Micro-Nano Systems Engineering, Nagoya University, Nagoya 464-8603, Japan

³ Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia

Appl. Sci. 2017, 7(2), 170; https://doi.org/10.3390/app7020170 - 10 Feb 2017

Cited by 38 | Viewed by 7412

Abstract

In this study, we introduce novel method of flow cytometry for cell detection based on impedance measurements. The state of the art method for impedance flow cytometry detection utilizes an embedded electrode in the microfluidic to perform measurement of electrical impedance of the [...] Read more.

In this study, we introduce novel method of flow cytometry for cell detection based on impedance measurements. The state of the art method for impedance flow cytometry detection utilizes an embedded electrode in the microfluidic to perform measurement of electrical impedance of the presence of cells at the sensing area. Nonetheless, this method requires an expensive and complicated electrode fabrication process. Furthermore, reuse of the fabricated electrode also requires an intensive and tedious cleaning process. Due to that, we present a microfluidic device with integrated microneedles. The two microneedles are placed at the half height of the microchannel for cell detection and electrical measurement. A commercially-available Tungsten needle was utilized for the microneedles. The microneedles are easily removed from the disposable PDMS (Polydimethylsiloxane) microchannel and can be reused with a simple cleaning process, such as washing by ultrasonic cleaning. Although this device was low cost, it preserves the core functionality of the sensor, which is capable of detecting passing cells at the sensing area. Therefore, this device is suitable for low-cost medical and food safety screening and testing process in developing countries. Full article

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

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16 pages, 3925 KiB

Open AccessArticle

Research of a Multi-Frequency Waveform Control Method on Double-Wire MIG Arc Welding

by Ping Yao^1,2 and Kang Zhou^3,*

¹ College of Electromechanical Engineering, Guangdong Polytechnic Normal University, Guangzhou 510635, China

² School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China

³ State Key Laboratory of High-Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Appl. Sci. 2017, 7(2), 171; https://doi.org/10.3390/app7020171 - 10 Feb 2017

Cited by 9 | Viewed by 5298

Abstract

To improve the energy efficiency and quality of the welding seam during the double-wire metal inert-gas (MIG) arc welding production, a new multi-frequency waveform control method was proposed in this paper. In this method, a multi-frequency modulation was added to the waveform in [...] Read more.

To improve the energy efficiency and quality of the welding seam during the double-wire metal inert-gas (MIG) arc welding production, a new multi-frequency waveform control method was proposed in this paper. In this method, a multi-frequency modulation was added to the waveform in the peak stage of trailing wire current, under the situation that the two wires current waveforms had the same frequencies but inverse phases. This new action can benefit the stability of welding process and improve the quality of welding seam. Actual experiments were conducted to validate the proposed method. Orthogonal experiments and corresponding mathematical analyses were also employed to seek an optimal parameters combination. Finally, an optimal combination was confirmed and a welding seam with satisfactory quality was obtained, which showed that the proposed control method and corresponding analyses can well serve the double-wire MIG arc welding, and then benefit the actual production in the future. Full article

(This article belongs to the Special Issue Gas Metal Arc Welding)

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12 pages, 3374 KiB

Open AccessArticle

Accurate Determination of Geographical Origin of Tea Based on Terahertz Spectroscopy

by Mingliang Li¹

, Guangbin Dai¹, Tianying Chang^1,2,*

, Changcheng Shi², Dongshan Wei²

, Chunlei Du² and Hong-Liang Cui^1,2

¹ College of Instrumentation & Electrical Engineering, Jilin University, Jilin 130061, China

² Chongqing Key Laboratory of Multi-Scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Research Center for Terahertz Technology, Chongqing 400714, China

Appl. Sci. 2017, 7(2), 172; https://doi.org/10.3390/app7020172 - 10 Feb 2017

Cited by 32 | Viewed by 4922

Abstract

This paper proposes a structured model for the identification of green tea, as well as tracing its geographical origins. Considering that the features of different types of green tea are similar under THz time-domain spectroscopy, we designed a program to perform principal component [...] Read more.

This paper proposes a structured model for the identification of green tea, as well as tracing its geographical origins. Considering that the features of different types of green tea are similar under THz time-domain spectroscopy, we designed a program to perform principal component analysis (PCA) of the spectroscopic data of various green tea samples and to determine the data sequences of principal components. We then established a training set for the principal components to train a support vector machine (SVM) model via a genetic algorithm (GA). We used this model to optimize the parameters and develop a GA-based SVM model with an identification rate of 96.25% for the tested samples. Taken together, our results confirm that THz time-domain spectroscopy combined with GA-SVM can be effectively applied to rapidly identify types of green tea with different geographical origins. Full article

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18 pages, 1433 KiB

Open AccessArticle

Analysis of Field Data to Describe the Effect of Context (Acoustic and Non-Acoustic Factors) on Urban Soundscapes

by Karmele Herranz-Pascual, Igone García^*, Itxasne Diez, Alvaro Santander and Itziar Aspuru

TECNALIA Research & Innovation, Parque Tecnologico de Bizkaia C/Geldo, Edificio 700, E-48160 Derio, Spain

Appl. Sci. 2017, 7(2), 173; https://doi.org/10.3390/app7020173 - 10 Feb 2017

Cited by 24 | Viewed by 4168

Abstract

The need to improve acoustic environments in our cities has led to increased interest in correcting or minimising noise pollution in urban environments, something that has been associated with the resurgence of the soundscape approach. This line of research highlights the importance of [...] Read more.

The need to improve acoustic environments in our cities has led to increased interest in correcting or minimising noise pollution in urban environments, something that has been associated with the resurgence of the soundscape approach. This line of research highlights the importance of context in the perception of acoustic environments. Despite this, few studies consider together a wide number of variables relating to the context, and analyse the relative importance of each. The purpose of this paper is therefore to identify the acoustic and non-acoustic characteristics of a place (context) that influence an individual’s perception of the sound environment and the relative importance of these factors in soundscape. The aim is to continue advancing in the definition of an acoustic comfort indicator for urban places. The data used here were collected in various soundscape campaigns carried out by Tecnalia in Bilbao (Spain) between 2011 and 2014. These studies involved 534 evaluations of 10 different places. The results indicate that many diverse contextual factors determine soundscape, the most important being the congruence between soundscape and landscape. The limitations of the findings and suggestions for further research are also discussed. Full article

(This article belongs to the Section Acoustics and Vibrations)

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11 pages, 2326 KiB

Open AccessArticle

Low-Loss Micro-Resonator Filters Fabricated in Silicon by CMOS-Compatible Lithographic Techniques: Design and Characterization

by Riccardo Marchetti¹, Valerio Vitali¹, Cosimo Lacava², Ilaria Cristiani¹, Guido Giuliani³, Viviane Muffato⁴, Maryse Fournier⁴, Silvio Abrate⁵

, Roberto Gaudino⁶

, Enrico Temporiti⁷

, Lee Carroll⁸ and Paolo Minzioni^1,*

¹ Department of Electrical, Computer, and Biomedical Engineering, Università di Pavia, Pavia I-27100, Italy

² Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK

³ Department of Civil Engineering and Architecture, Università di Pavia, Pavia I-27100, Italy

⁴ Photonic Department, CEA MINATEC Campus, Grenoble CEDEX F-38054, France

⁵ Istituto Superiore Mario Boella, Torino 10138, Italy

⁶ Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Torino 10129, Italy

⁷ STMicroelectronics-Studio di Microelettronica, Via Ferrata 4, Pavia 27100, Italy

⁸ Photonic Packaging Group, Tyndall National Institute, Lee Maltings Complex, Cork T12R5CP, Ireland

Appl. Sci. 2017, 7(2), 174; https://doi.org/10.3390/app7020174 - 11 Feb 2017

Cited by 24 | Viewed by 5985

Abstract

Optical resonators are fundamental building-blocks for the development of Si-photonics-integrated circuits, as tunable on-chip optical filters. In addition to the specific spectral shape, which may vary according to a particular application, extremely low losses from these devices are a crucial requirement. In the [...] Read more.

Optical resonators are fundamental building-blocks for the development of Si-photonics-integrated circuits, as tunable on-chip optical filters. In addition to the specific spectral shape, which may vary according to a particular application, extremely low losses from these devices are a crucial requirement. In the current state-of-the-art devices, most low-loss filters have only been demonstrated by exploiting ad hoc lithographic and etching techniques, which are not compatible with the standard CMOS (complementary metal-oxide semiconductor) process-flow available at Si-photonic foundries. In this paper, we describe the design and optimization of optical micro-resonators, based on Si-waveguides with a height lower than the standard ones (i.e., less than 220 nm), prepared on SOI (silicon on insulator) platform, which allow the realization of high-performance optical filters with an insertion loss lower than 1 dB, using only previously validated lithographic etch-depths. Full article

(This article belongs to the Special Issue Silicon Photonics Components and Applications)

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16 pages, 2472 KiB

Open AccessReview

A Review on Natural Ventilation-enabling Façade Noise Control Devices for Congested High-Rise Cities

by Shiu-Keung Tang

Department of Building Services Engineering, The Hong Kong Polytechnic University, Hong Kong, China

Appl. Sci. 2017, 7(2), 175; https://doi.org/10.3390/app7020175 - 13 Feb 2017

Cited by 65 | Viewed by 11493

Abstract

This review summarizes the current status of the research and development of natural ventilation-enabling noise control devices for use on the façades of high-rise residential buildings in congested cities. These devices are important for a sustainable urbanized city, as they are supposed to [...] Read more.

This review summarizes the current status of the research and development of natural ventilation-enabling noise control devices for use on the façades of high-rise residential buildings in congested cities. These devices are important for a sustainable urbanized city, as they are supposed to offer good acoustical protection to citizens, allowing for an acceptable level of natural ventilation inside residential units; energy for mechanical ventilation can then be saved. From the information presented in the existing literature, it is concluded that protrusive devices, such as lintels and balconies, are not effective noise screening devices, even if they are installed with sound absorbers and/or reflectors, under the effect of city reverberation. On the contrary, plenum windows and similar structures, which are plenum structures with a staggered air inlet and outlet, are interesting alternatives that are worth rigorous considerations. Full article

(This article belongs to the Special Issue Noise and Vibration Control in the Built Environment)

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16 pages, 5850 KiB

Open AccessArticle

Development of Probabilistic Reliability Models of Photovoltaic System Topologies for System Adequacy Evaluation

by Ahmad Alferidi^* and Rajesh Karki

The Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada

Appl. Sci. 2017, 7(2), 176; https://doi.org/10.3390/app7020176 - 14 Feb 2017

Cited by 31 | Viewed by 5896

Abstract

The contribution of solar power in electric power systems has been increasing rapidly due to its environmentally friendly nature. Photovoltaic (PV) systems contain solar cell panels, power electronic converters, high power switching and often transformers. These components collectively play an important role in [...] Read more.

The contribution of solar power in electric power systems has been increasing rapidly due to its environmentally friendly nature. Photovoltaic (PV) systems contain solar cell panels, power electronic converters, high power switching and often transformers. These components collectively play an important role in shaping the reliability of PV systems. Moreover, the power output of PV systems is variable, so it cannot be controlled as easily as conventional generation due to the unpredictable nature of weather conditions. Therefore, solar power has a different influence on generating system reliability compared to conventional power sources. Recently, different PV system designs have been constructed to maximize the output power of PV systems. These different designs are commonly adopted based on the scale of a PV system. Large-scale grid-connected PV systems are generally connected in a centralized or a string structure. Central and string PV schemes are different in terms of connecting the inverter to PV arrays. Micro-inverter systems are recognized as a third PV system topology. It is therefore important to evaluate the reliability contribution of PV systems under these topologies. This work utilizes a probabilistic technique to develop a power output model for a PV generation system. A reliability model is then developed for a PV integrated power system in order to assess the reliability and energy contribution of the solar system to meet overall system demand. The developed model is applied to a small isolated power unit to evaluate system adequacy and capacity level of a PV system considering the three topologies. Full article

(This article belongs to the Special Issue Advancing Grid-Connected Renewable Generation Systems)

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14 pages, 3869 KiB

Open AccessArticle

Dielectric Characterization of Chinese Standard Concrete for Compressive Strength Evaluation

by Kwok L. Chung¹

, Lei Yuan¹, Songtao Ji¹, Li Sun², Chengping Qu¹ and Chunwei Zhang^1,*

¹ School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China

² School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

Appl. Sci. 2017, 7(2), 177; https://doi.org/10.3390/app7020177 - 17 Feb 2017

Cited by 34 | Viewed by 9053

Abstract

Dielectric characterization of concrete is essential for the wireless structural health monitoring (SHM) of concrete structures. Guo Biao (GB) concrete refers to the concrete mixed and cast in accordance with the Chinese standard. Currently, China is the largest producer and consumer of concrete [...] Read more.

Dielectric characterization of concrete is essential for the wireless structural health monitoring (SHM) of concrete structures. Guo Biao (GB) concrete refers to the concrete mixed and cast in accordance with the Chinese standard. Currently, China is the largest producer and consumer of concrete in the world. However, minimal attention has been paid to the dielectric properties of GB concrete. This paper presents the results of the dielectric constant of GB concrete, where three regression models have been used to present the measurement data from 10 MHz to 6 GHz. The objective is to provide a data set of nominal values of the dielectric constant for ordinary GB concrete. The final goal is to facilitate a compressive strength evaluation via the measured dielectric constant. Measurements of the dielectric constant and compressive strength for five types of ordinary concrete have been undertaken, after 28 days of curing. As the main contribution in this work, the correlation model between the compressive strength and dielectric constant of GB concrete is realized. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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10 pages, 1839 KiB

Open AccessArticle

Fusion of Linear and Mel Frequency Cepstral Coefﬁcients for Automatic Classiﬁcation of Reptiles

by Juan J. Noda¹, Carlos M. Travieso^1,2

and David Sánchez-Rodríguez^1,3,*

¹ Institute for Technological Development and Innovation in Communications, University of Las Palmas de Gran Canaria, Campus Universitario de Taﬁra, 35017 Las Palmas de Gran Canaria, Spain

² Signal and Communications Department, University of Las Palmas de Gran Canaria, Campus Universitario de Taﬁra, 35017 Las Palmas de Gran Canaria, Spain

³ Telematic Engineering Department, University of Las Palmas de Gran Canaria, Campus Universitario de Taﬁra, 35017 Las Palmas de Gran Canaria, Spain

Appl. Sci. 2017, 7(2), 178; https://doi.org/10.3390/app7020178 - 13 Feb 2017

Cited by 5 | Viewed by 5011

Abstract

Bioacoustic research of reptile calls and vocalizations has been limited due to the general consideration that they are voiceless. However, several species of geckos, turtles, and crocodiles are abletoproducesimpleandevencomplexvocalizationswhicharespecies-speciﬁc.Thisworkpresents a novel approach for the automatic taxonomic identiﬁcation of reptiles through their bioacoustics by [...] Read more.

Bioacoustic research of reptile calls and vocalizations has been limited due to the general consideration that they are voiceless. However, several species of geckos, turtles, and crocodiles are abletoproducesimpleandevencomplexvocalizationswhicharespecies-speciﬁc.Thisworkpresents a novel approach for the automatic taxonomic identiﬁcation of reptiles through their bioacoustics by applying pattern recognition techniques. The sound signals are automatically segmented, extracting each call from the background noise. Then, their calls are parametrized using Linear and Mel Frequency Cepstral Coefﬁcients (LFCC and MFCC) to serve as features in the classiﬁcation stage. In this study, 27 reptile species have been successfully identiﬁed using two machine learning algorithms: K-Nearest Neighbors (kNN) and Support Vector Machine (SVM). Experimental results show an average classiﬁcation accuracy of 97.78% and 98.51%, respectively. Full article

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18 pages, 6594 KiB

Open AccessArticle

Voltage-Mode and Current-Mode Resistorless Third-Order Quadrature Oscillator

by Hua-Pin Chen^1,*, Yuh-Shyan Hwang² and Yi-Tsen Ku²

¹ Department of Electronic Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan

² Department of Electronic Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

Appl. Sci. 2017, 7(2), 179; https://doi.org/10.3390/app7020179 - 13 Feb 2017

Cited by 30 | Viewed by 5484

Abstract

This paper presents the realization of a resistorless third-order quadrature oscillator using two multiple-output current controlled current conveyor transconductance amplifiers (MO-CCCCTAs) and three grounded capacitors. The proposed circuit provides two quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance amplitude-controllable current [...] Read more.

This paper presents the realization of a resistorless third-order quadrature oscillator using two multiple-output current controlled current conveyor transconductance amplifiers (MO-CCCCTAs) and three grounded capacitors. The proposed circuit provides two quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance amplitude-controllable current output. The proposed oscillator satisfies the industrial requirement for amplifier and modulation signals and phase shift keying signals, when the input bias current of the second MO-CCCCTA is used as a modulating signal. Its oscillation condition and oscillation frequency can be adjusted independently by two different bias currents of MO-CCCCTAs. The structure of resistorless and only grounded capacitors suggests that the proposed oscillator can be easily implemented in an integrated circuit. Full article

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

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13 pages, 1849 KiB

Open AccessArticle

Construction Industrialization in China: Current Profile and the Prediction

by Yingbo Ji¹, Fadong Zhu¹, Hong Xian Li^2,*

and Mohamed Al-Hussein²

¹ School of Civil Engineering, North China University of Technology, Beijing 100041, China

² Hole School of Construction Engineering, Department of Civil and Environmental Engineering, University of Alberta, 9211 116 St. NW, Edmonton, AB T6G 1H9, Canada

Appl. Sci. 2017, 7(2), 180; https://doi.org/10.3390/app7020180 - 13 Feb 2017

Cited by 53 | Viewed by 8159

Abstract

The ongoing undertaking of construction industrialization in China is redefining the industry and creating a new era for building construction. In order to identify the construction industrialization status and progress, a national survey is conducted across 19 key provinces and municipalities in China. [...] Read more.

The ongoing undertaking of construction industrialization in China is redefining the industry and creating a new era for building construction. In order to identify the construction industrialization status and progress, a national survey is conducted across 19 key provinces and municipalities in China. Based on the collected data, construction industrialization is analyzed from various perspectives: (1) the industrialized building floor area is profiled using maps with colours showing the different levels of construction industrialization in China as of 2014; and (2) structural types and building types are analyzed for industrialized construction, and it is found that reinforced concrete is the predominant structure type, accounting for 77.1% of total floor area of industrialized construction in 2014. The industrialization trends are also predicted for the following five years using Holt’s and Delphi method. This research reveals the status and the promising trends of construction industrialization in China. Full article

(This article belongs to the Special Issue The Industrialization of the Building Construction Process)

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15 pages, 5794 KiB

Open AccessFeature PaperArticle

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF) Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS) Processes

by Faisal Abdulla AlMarzooqi, Muhammad Roil Bilad

and Hassan Ali Arafat^*

Department of Chemical and Environmental Engineering, Masdar Institute of Science and Technology, P.O. Box 54224 Abu Dhabi, UAE

Appl. Sci. 2017, 7(2), 181; https://doi.org/10.3390/app7020181 - 14 Feb 2017

Cited by 62 | Viewed by 11567

Abstract

Polyvinylidene fluoride (PVDF) is a popular polymer material for making membranes for several applications, including membrane distillation (MD), via the phase inversion process. Non-solvent-induced phase separation (NIPS) and vapor-induced phase separation (VIPS) are applied to achieve a porous PVDF membrane with low mass-transfer [...] Read more.

Polyvinylidene fluoride (PVDF) is a popular polymer material for making membranes for several applications, including membrane distillation (MD), via the phase inversion process. Non-solvent-induced phase separation (NIPS) and vapor-induced phase separation (VIPS) are applied to achieve a porous PVDF membrane with low mass-transfer resistance and high contact angle (hydrophobicity). In this work, firstly, the impacts of several preparation parameters on membrane properties using VIPS and NIPS were studied. Then, the performance of the selected membrane was assessed in a lab-scale direct-contact MD (DCMD) unit. The parametric study shows that decreasing PVDF concentration while increasing both relative humidity (RH) and exposure time increased the contact angle and bubble-point pore size (BP). Those trends were investigated further by varying the casting thickness. At higher casting thicknesses and longer exposure time (up to 7.5 min), contact angle (CA) increased but BP significantly decreased. The latter showed a dominant trend leading to liquid entry pressure (LEP) increase with thickness. Full article

(This article belongs to the Special Issue Membrane Distillation)

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16 pages, 4107 KiB

Open AccessArticle

Seismic Failure Mechanism of Reinforced Cold-Formed Steel Shear Wall System Based on Structural Vulnerability Analysis

by Jihong Ye^*, Liqiang Jiang and Xingxing Wang

The Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing 210018, China

Appl. Sci. 2017, 7(2), 182; https://doi.org/10.3390/app7020182 - 22 Feb 2017

Cited by 16 | Viewed by 9610

Abstract

A series of structural vulnerability analyses are conducted on a reinforced cold-formed steel (RCFS) shear wall system and a traditional cold-formed steel (CFS) shear wall system subjected to earthquake hazard based on forms in order to investigate their failure mechanisms. The RCFS shear [...] Read more.

A series of structural vulnerability analyses are conducted on a reinforced cold-formed steel (RCFS) shear wall system and a traditional cold-formed steel (CFS) shear wall system subjected to earthquake hazard based on forms in order to investigate their failure mechanisms. The RCFS shear wall adopts rigid beam-column joints and continuous concrete-filled CFS tube end studs rather than coupled-C section end studs that are used in traditional CFS shear walls, to achieve the rigid connections in both beam-column joints and column bases. The results show that: the RCFS and traditional CFS shear wall systems both exhibit the maximum vulnerability index associated with the failure mode in the first story. Therefore, the first story is likely to be a weakness of the CFS shear wall system. Once the wall is damaged, the traditional CFS shear wall system would collapse because the shear wall is the only lateral-resisting component. However, the collapse resistance of the RCFS shear wall system is effectively enhanced by the second defense, which is provided by a framework integrated by rigid beam-column joints and fixed column bases. The predicted collapse mode with maximum vulnerability index that was obtained by structural vulnerability analysis agrees well with the experimental result, and the structural vulnerability method is thereby verified to be reasonable to identify the weaknesses of framed structures and predict their collapse modes. Additionally, the quantitative vulnerability index indicates that the RCFS shear wall system exhibits better robustness compared to the traditional one. Furthermore, the “strong frame weak wallboard” and the “strong column weak beam” are proposed in this study as conceptional designations for the RCFS shear wall systems. Full article

(This article belongs to the Special Issue Applications of Thin-Walled Structures)

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20 pages, 3855 KiB

Open AccessArticle

Towards a Hybrid Approach to Context Reasoning for Underwater Robots

by Xin Li^*

, José-Fernán Martínez and Gregorio Rubio

Research Center on Software Technologies and Multimedia Systems for Sustainability (CITSEM), Campus Sur, Technical University of Madrid, 28031 Madrid, Spain

Appl. Sci. 2017, 7(2), 183; https://doi.org/10.3390/app7020183 - 15 Feb 2017

Cited by 20 | Viewed by 5924

Abstract

Ontologies have been widely used to facilitate semantic interoperability and serve as a common information model in many applications or domains. The Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) project, aiming to facilitate coordination and cooperation between heterogeneous underwater vehicles, also [...] Read more.

Ontologies have been widely used to facilitate semantic interoperability and serve as a common information model in many applications or domains. The Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) project, aiming to facilitate coordination and cooperation between heterogeneous underwater vehicles, also adopts ontologies to formalize information that is necessarily exchanged between vehicles. However, how to derive more useful contexts based on ontologies still remains a challenge. In particular, the extreme nature of the underwater environment introduces uncertainties in context data, thus imposing more difficulties in context reasoning. None of the existing context reasoning methods could individually deal with all intricacies in the underwater robot field. To this end, this paper presents the first proposal applying a hybrid context reasoning mechanism that includes ontological, rule-based, and Multi-Entity Bayesian Network (MEBN) reasoning methods to reason about contexts and their uncertainties in the underwater robot field. The theoretical foundation of applying this reasoning mechanism in underwater robots is given by a case study on the oil spill monitoring. The simulated reasoning results are useful for further decision-making by operators or robots and they show that the consolidation of different reasoning methods is a promising approach for context reasoning in underwater robots. Full article

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6 pages, 770 KiB

Open AccessArticle

Calculation of Receiver Sensitivities in (Orthogonal) Subcarrier Multiplexing Microwave-Optical Links

by Fernando A. Gutiérrez^1,*, Eamonn P. Martin¹, Philip Perry¹, Andrew D. Ellis² and Liam P. Barry¹

¹ Radio and Optical Communication Lab, School of Electronic Engineering, Dublin City University, Glasnevin, Dublin 9, Ireland

² Aston Institute of Photonics Technologies, Aston University, Aston Triangle, Birmingham B4 7ET, UK

Appl. Sci. 2017, 7(2), 184; https://doi.org/10.3390/app7020184 - 15 Feb 2017

Cited by 1 | Viewed by 4703

Abstract

Microwave-based all-analogue (orthogonal) subcarrier multiplexing (SCM) permits a direct processing of baseband data at Gbit/s while achieving low power consumption, low latency, low cost, and tolerance to dispersion. A key figure of merit in any SCM link is the sensitivity in the receiver, [...] Read more.

Microwave-based all-analogue (orthogonal) subcarrier multiplexing (SCM) permits a direct processing of baseband data at Gbit/s while achieving low power consumption, low latency, low cost, and tolerance to dispersion. A key figure of merit in any SCM link is the sensitivity in the receiver, which depends on the transmitter, the link and the receiver. By analysing the impact of the nonlinearities of an optical IQ modulator in the presence of optical noise, sensitivities are mathematically estimated as a function of the optical modulation index (OMI) at the transmitter. The results are verified with simulations achieving a good agreement with the mathematical model. The theoretical model provided can be employed as a tool to predict the best achievable sensitivities and the optimum OMI in broadband SCM and orthogonal SCM links. Full article

(This article belongs to the Special Issue Optical Modulators and Switches)

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21 pages, 4000 KiB

Open AccessArticle

Self-Tuning Fuzzy Control for Seismic Protection of Smart Base-Isolated Buildings Subjected to Pulse-Type Near-Fault Earthquakes

by Dahai Zhao^1,*, Yang Liu¹ and Hongnan Li²

¹ School of Civil Engineering and Mechanics, Yanshan University, Qinhuangdao 066004, China

² School of Civil Engineering, Dalian University of Technology, Dalian 116024, China

Appl. Sci. 2017, 7(2), 185; https://doi.org/10.3390/app7020185 - 16 Feb 2017

Cited by 12 | Viewed by 6684

Abstract

Pulse-type near-fault earthquakes have obvious long-duration pulses, so they can cause large deformation in a base-isolated system in contrast to non-pulse-type near-fault and far-field earthquakes. This paper proposes a novel self-tuning fuzzy logic control strategy for seismic protection of a base-isolated system, which [...] Read more.

Pulse-type near-fault earthquakes have obvious long-duration pulses, so they can cause large deformation in a base-isolated system in contrast to non-pulse-type near-fault and far-field earthquakes. This paper proposes a novel self-tuning fuzzy logic control strategy for seismic protection of a base-isolated system, which can operate the control force of the piezoelectric friction damper against different types of earthquakes. This control strategy employs a hierarchic control algorithm, in which a higher-level supervisory fuzzy controller is implemented to adjust the input normalization factors and output scaling factor, while a sub-level fuzzy controller effectively determines the command voltage of the piezoelectric friction damper according to current level of earthquakes. The efficiency of the proposed control strategy is also compared with uncontrolled and maximum passive cases. Numerical results reveal that the novel fuzzy logic control strategy can effectively reduce the isolation system deformations without the loss of potential advantages of base-isolated system. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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12 pages, 3244 KiB

Open AccessArticle

Block Recovery Rate-Based Unequal Error Protection for Three-Screen TV

by Hojin Ha¹ and Eun-Seok Ryu^2,*

¹ Department of Information, Communication and Broadcasting Engineering, Halla University, 28 Halladae-gil, Wonju-si 26404, Kangwon-do, Korea

² Department of Computer Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam 13120, Gyeonggi, Korea

Appl. Sci. 2017, 7(2), 186; https://doi.org/10.3390/app7020186 - 16 Feb 2017

Viewed by 4475

Abstract

This paper describes a three-screen television system using a block recovery rate (BRR)-based unequal error protection (UEP). The proposed in-home wireless network uses scalable video coding (SVC) and UEP with forward error correction (FEC) for maximizing the quality of service (QoS) over error-prone [...] Read more.

This paper describes a three-screen television system using a block recovery rate (BRR)-based unequal error protection (UEP). The proposed in-home wireless network uses scalable video coding (SVC) and UEP with forward error correction (FEC) for maximizing the quality of service (QoS) over error-prone wireless networks. For efficient FEC packet assignment, this paper proposes a simple and efficient performance metric, a BRR which is defined as a recovery rate of temporal and quality layer from FEC assignment by analyzing the hierarchical prediction structure including the current packet loss. It also explains the SVC layer switching scheme according to network conditions such as packet loss rate (PLR) and available bandwidth (ABW). In the experiments conducted, gains in video quality with the proposed UEP scheme vary from 1 to 3 dB in Y-peak signal-to-noise ratio (PSNR) with corresponding subjective video quality improvements. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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13 pages, 2325 KiB

Open AccessArticle

Subcritical Water Extraction of Ursolic Acid from Hedyotis diffusa

by Shangzhen Xiao¹, Xingjun Xi², Fei Tang², Juan Dai¹, Jing Liu^1,*, Jiandu Lei^1,3,* and Luying Wang¹

¹ Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China

² Institute of Food and Agricultural Standardization, China National Institute of Standardization, Beijing 100191, China

³ Minister of Education Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083, China

Appl. Sci. 2017, 7(2), 187; https://doi.org/10.3390/app7020187 - 15 Feb 2017

Cited by 11 | Viewed by 6808

Abstract

An efficient and environmental-friendly extraction method has been developed for extraction of ursolic acid (UA) from Hedyotis diffusa by using subcritical water extraction (SWE). The experiments were carried out at different particle sizes (20–100 mesh), extraction temperature (120–200 °C), extraction time (10–50 min), [...] Read more.

An efficient and environmental-friendly extraction method has been developed for extraction of ursolic acid (UA) from Hedyotis diffusa by using subcritical water extraction (SWE). The experiments were carried out at different particle sizes (20–100 mesh), extraction temperature (120–200 °C), extraction time (10–50 min), solvent/solid ratio (20–40 mL/g), and extraction pressure (0.6–3.0 MPa). Response surface methodology (RSM) was employed to optimize SWE conditions, and the maximum UA yield was 6.45 mg/g material. Optimal conditions are as follows: Particle size of 80 mesh, extraction temperature at 157 °C and a solvent/solid ratio of 30 mL/g. The model of experimental response was proved to predict the experimental results very well and demonstrated that UA yield was mainly depended on solvent/solid ratio, followed by particle size and temperature. The purified extract was analyzed by electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). The acquired precursor ion was m/z 455.3532, which is consistent with calculated value of UA. Furthermore, different extraction methods, including maceration extraction, heat reflux extraction, ultrasonic extraction, microwave-assisted extraction, and SWE were comparatively analyzed, which indicated that SWE was a time-saving, cost-saving and environment-friendly extraction technology for extraction of UA from Hedyotis diffusa. Full article

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

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11 pages, 1821 KiB

Open AccessArticle

Strain Transfer Analysis of a Clamped Fiber Bragg Grating Sensor

by Li Sun^1,*, Chuang Li¹, Jun Li²

, Chunwei Zhang³ and Xiaosu Ding¹

¹ School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

² Centre for Infrastructural Monitoring and Protection, School of Civil and Mechanical Engineering, Curtin University, Kent Street, Bentley WA 6102, Australia

³ School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China

Appl. Sci. 2017, 7(2), 188; https://doi.org/10.3390/app7020188 - 15 Feb 2017

Cited by 41 | Viewed by 5294

Abstract

Clamped fiber Bragg grating (FBG) sensors have been widely applied in engineering strain measurements due to their advantages of high flexibility and efficiency. However, due to the existence of the interlayer, the strain measured by the encapsulated FBG sensor is not equal to [...] Read more.

Clamped fiber Bragg grating (FBG) sensors have been widely applied in engineering strain measurements due to their advantages of high flexibility and efficiency. However, due to the existence of the interlayer, the strain measured by the encapsulated FBG sensor is not equal to the strain of the host material, which causes strain measurement errors. In this paper, the strain transfer analysis of a clamped FBG sensor based on the shear-lag theory is conducted to improve the accuracy of strain measurements. A novel theoretical model for the axial strain distribution of a clamped FBG sensor is proposed. It is also discussed how the gauge ratio and interlayer thickness affect the strain transfer rate. The accuracy of the proposed theoretical model is verified by experimental tensile tests. The theoretical value of the strain transfer rate matches well with the tested value. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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36 pages, 10162 KiB

Open AccessReview

Innovative Hyperspectral Imaging-Based Techniques for Quality Evaluation of Fruits and Vegetables: A Review

by Yuzhen Lu¹

, Yuping Huang² and Renfu Lu^3,*

¹ Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI 48824, USA

² College of Engineering, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China

³ United States Department of Agriculture Agricultural Research Service, Michigan State University, East Lansing, MI 48824, USA

Appl. Sci. 2017, 7(2), 189; https://doi.org/10.3390/app7020189 - 15 Feb 2017

Cited by 96 | Viewed by 14124

Abstract

New, non-destructive sensing techniques for fast and more effective quality assessment of fruits and vegetables are needed to meet the ever-increasing consumer demand for better, more consistent and safer food products. Over the past 15 years, hyperspectral imaging has emerged as a new [...] Read more.

New, non-destructive sensing techniques for fast and more effective quality assessment of fruits and vegetables are needed to meet the ever-increasing consumer demand for better, more consistent and safer food products. Over the past 15 years, hyperspectral imaging has emerged as a new generation of sensing technology for non-destructive food quality and safety evaluation, because it integrates the major features of imaging and spectroscopy, thus enabling the acquisition of both spectral and spatial information from an object simultaneously. This paper first provides a brief overview of hyperspectral imaging configurations and common sensing modes used for food quality and safety evaluation. The paper is, however, focused on the three innovative hyperspectral imaging-based techniques or sensing platforms, i.e., spectral scattering, integrated reflectance and transmittance, and spatially-resolved spectroscopy, which have been developed in our laboratory for property and quality evaluation of fruits, vegetables and other food products. The basic principle and instrumentation of each technique are described, followed by the mathematical methods for processing and extracting critical information from the acquired data. Applications of these techniques for property and quality evaluation of fruits and vegetables are then presented. Finally, concluding remarks are given on future research needs to move forward these hyperspectral imaging techniques. Full article

(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture)

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12 pages, 1363 KiB

Open AccessArticle

Design and Cooling Performances of an Air Conditioning System with Two Parallel Refrigeration Cycles for a Special Purpose Vehicle

by Moo-Yeon

Lee Department of Mechanical Engineering, Dong-A University, Busan 604-714, Korea

Appl. Sci. 2017, 7(2), 190; https://doi.org/10.3390/app7020190 - 15 Feb 2017

Cited by 3 | Viewed by 9930

Abstract

The objective of this study is to design and briefly investigate the cooling performances of an air conditioning system for a special purpose vehicle under various experimental conditions. An air conditioning system with two parallel refrigeration cycles consisting of two compressors and two [...] Read more.

The objective of this study is to design and briefly investigate the cooling performances of an air conditioning system for a special purpose vehicle under various experimental conditions. An air conditioning system with two parallel refrigeration cycles consisting of two compressors and two condensers for satisfying the required cooling performance of the special purpose vehicle was tested under extremely hot weather conditions and high thermal load conditions and then optimized by varying the refrigerant charge amount. The optimum refrigerant charge amount of the tested air conditioning system was 1200 g with the consideration of the cooling speed and cooling capacity. The indoor temperatures of the suggested air conditioning system at the refrigerant charge amounts of 1200 g, 1400 g, and 1600 g were 24.7 °C, 25.2 °C, and 26.4 °C, respectively, at the elapsed time of 300 s. The cooling time required to reach a 15.0°C inner temperature in the suggested air conditioning system increased by 13.3% with the decrease of the refrigerant charge amount from 1600 g to 1200 g. The cooling capacity and the coefficient of performance (COP) of the suggested air conditioning system increased by 37.9% and 10.9%, respectively, due to a decrease of the refrigerant charge amount from 1600 g to 1200 g. The observed cooling performance characteristics of the air conditioning system with two parallel refrigeration cycles means it could be suitable for cabin cooling of special purpose vehicles. In addition, the designed special air conditioning system with two parallel refrigeration cycles for a special purpose vehicle was built to ensure a sufficient cooling performance for equipped passengers. Full article

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

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15 pages, 2782 KiB

Open AccessArticle

FE Model Updating on an In-Service Self-Anchored Suspension Bridge with Extra-Width Using Hybrid Method

by Zhiyuan Xia¹, 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 College of Civil Engineering, Nanjing Forestry University, No. 159 Longpan Road, Nanjing 210037, China

Appl. Sci. 2017, 7(2), 191; https://doi.org/10.3390/app7020191 - 16 Feb 2017

Cited by 10 | Viewed by 4689

Abstract

Nowadays, many more bridges with extra-width have been needed for vehicle throughput. In order to obtain a precise finite element (FE) model of those complex bridge structures, the practical hybrid updating method by integration of Gaussian mutation particle swarm optimization (GMPSO), Kriging meta-model [...] Read more.

Nowadays, many more bridges with extra-width have been needed for vehicle throughput. In order to obtain a precise finite element (FE) model of those complex bridge structures, the practical hybrid updating method by integration of Gaussian mutation particle swarm optimization (GMPSO), Kriging meta-model and Latin hypercube sampling (LHS) was proposed. By demonstrating the efficiency and accuracy of the hybrid method through the model updating of a damaged simply supported beam, the proposed method was applied to the model updating of a self-anchored suspension bridge with extra-width which showed great necessity considering the results of ambient vibration test. The results of bridge model updating showed that both of the mode frequencies and shapes had relatively high agreement between the updated model and experimental structure. The successful model updating of this bridge fills in the blanks of model updating of a complex self-anchored suspension bridge. Moreover, the updating process enables other model updating issues for complex bridge structures Full article

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16 pages, 2708 KiB

Open AccessArticle

Recognition Algorithm Based on Improved FCM and Rough Sets for Meibomian Gland Morphology

by Fengmei Liang¹, Yajun Xu^1,*, Weixin Li², Xiaoling Ning³, Xueou Liu¹ and Ajian Liu¹

¹ College of Information Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China

² Engineering Experimental Class of National Pilot School, School of Precision Instrument & Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China

³ Shanxi Eye Hospital, Taiyuan 030002, Shanxi, China

Appl. Sci. 2017, 7(2), 192; https://doi.org/10.3390/app7020192 - 16 Feb 2017

Cited by 13 | Viewed by 5165

Abstract

To overcome the limitation of artificial judgment of meibomian gland morphology, we proposed a solution based on an improved fuzzy c-means (FCM) algorithm and rough sets theory. The rough sets reduced the redundant attributes while ensuring classification accuracy, and greatly reduced the amount [...] Read more.

To overcome the limitation of artificial judgment of meibomian gland morphology, we proposed a solution based on an improved fuzzy c-means (FCM) algorithm and rough sets theory. The rough sets reduced the redundant attributes while ensuring classification accuracy, and greatly reduced the amount of computation to achieve information dimension compression and knowledge system simplification. However, before this reduction, data must be discretized, and this process causes some degree of information loss. Therefore, to maintain the integrity of the information, we used the improved FCM to make attributes fuzzy instead of discrete before continuing with attribute reduction, and thus, the implicit knowledge and decision rules were more accurate. Our algorithm overcame the defects of the traditional FCM algorithm, which is sensitive to outliers and easily falls into local optima. Our experimental results show that the proposed method improved recognition efficiency without degrading recognition accuracy, which was as high as 97.5%. Furthermore, the meibomian gland morphology was diagnosed efficiently, and thus this method can provide practical application values for the recognition of meibomian gland morphology. Full article

(This article belongs to the Special Issue Smart Healthcare)

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22 pages, 4003 KiB

Open AccessArticle

Comparison of Oil Spill Classifications Using Fully and Compact Polarimetric SAR Images

by Yuanzhi Zhang^1,*, Yu Li^2,*, X. San Liang¹ and Jinyeu Tsou³

¹ School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China

² School of Information and Communication Engineering, Beijing University of Technology, Beijing 100021, China

³ Center for Housing Innovations, Chinese University of Hong Kong, Ma Liu Shui, Hong Kong, China

Appl. Sci. 2017, 7(2), 193; https://doi.org/10.3390/app7020193 - 16 Feb 2017

Cited by 36 | Viewed by 6645

Abstract

In this paper, we present a comparison between several algorithms for oil spill classifications using fully and compact polarimetric SAR images. Oil spill is considered as one of the most significant sources of marine pollution. As a major difficulty of SAR-based oil spill [...] Read more.

In this paper, we present a comparison between several algorithms for oil spill classifications using fully and compact polarimetric SAR images. Oil spill is considered as one of the most significant sources of marine pollution. As a major difficulty of SAR-based oil spill detection algorithms is the classification between mineral and biogenic oil, we focus on quantitatively analyzing and comparing fully and compact polarimetric satellite synthetic aperture radar (SAR) modes to detect hydrocarbon slicks over the sea surface, discriminating them from weak-damping surfactants, such as biogenic slicks. The experiment was conducted on quad-pol SAR data acquired during the Norwegian oil-on-water experiment in 2011. A universal procedure was used to extract the features from quad-, dual- and compact polarimetric SAR modes to rank different polarimetric SAR modes and common supervised classifiers. Among all the dual- and compact polarimetric SAR modes, the π/2 mode has the best performance. The best supervised classifiers vary and depended on whether sufficient polarimetric information can be obtained in each polarimetric mode. We also analyzed the influence of the number of polarimetric parameters considered as inputs for the supervised classifiers, onto the detection/discrimination performance. We discovered that a feature set with four features is sufficient for most polarimetric feature-based oil spill classifications. Moreover, dimension reduction algorithms, including principle component analysis (PCA) and the local linear embedding (LLE) algorithm, were employed to learn low dimensional and distinctive information from quad-polarimetric SAR features. The performance of the new feature sets has comparable performance in oil spill classification. Full article

(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)

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20 pages, 7686 KiB

Open AccessArticle

Time-Sequential Working Wavelength-Selective Filter for Flat Autostereoscopic Displays

by René De la Barré^1,*, Roland Bartmann¹, Silvio Jurk¹, Mathias Kuhlmey¹, Bernd Duckstein¹, Arno Seeboth², Detlef Lötzsch², Christian Rabe², Peter Frach³, Hagen Bartzsch³, Matthias Gittner³, Stefan Bruns⁴, Gerhard Schottner⁵ and Johanna Fischer⁵

¹ Department of Vision & Imaging Technologies, Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI, 10587 Berlin, Germany

² Department of Chromogenic Polymers, Fraunhofer Institute for Applied Polymer Research IAP, 12489 Berlin, Germany

³ Department of Precision Coatings, Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, 01109 Dresden, Germany

⁴ Department of Optical and Electrical Coatings, Fraunhofer Institute for Surface Engineering and Thin Films IST, 38108 Braunschweig, Germany

⁵ Business Unit Surfaces and Coatings, Fraunhofer Institute for Silicate Research ISC, 97082 Würzburg, Germany

Appl. Sci. 2017, 7(2), 194; https://doi.org/10.3390/app7020194 - 16 Feb 2017

Cited by 4 | Viewed by 6777

Abstract

A time-sequential working, spatially-multiplexed autostereoscopic 3D display design consisting of a fast switchable RGB-color filter array and a fast color display is presented. The newly-introduced 3D display design is usable as a multi-user display, as well as a single-user system. The wavelength-selective filter [...] Read more.

A time-sequential working, spatially-multiplexed autostereoscopic 3D display design consisting of a fast switchable RGB-color filter array and a fast color display is presented. The newly-introduced 3D display design is usable as a multi-user display, as well as a single-user system. The wavelength-selective filter barrier emits the light from a larger aperture than common autostereoscopic barrier displays with similar barrier pitch and ascent. Measurements on a demonstrator with commercial display components, simulations and computational evaluations have been carried out to describe the proposed wavelength-selective display design in static states and to show the weak spots of display filters in commercial displays. An optical modelling of wavelength-selective barriers has been used for instance to calculate the light ray distribution properties of that arrangement. In the time-sequential implementation, it is important to avoid that quick eye or eyelid movement leads to visible color artifacts. Therefore, color filter cells, switching faster than conventional LC display cells, must distribute directed light from different primaries at the same time, to create a 3D presentation. For that, electric tunable liquid crystal Fabry–Pérot color filters are presented. They switch on-off the colors red, green and blue in the millisecond regime. Their active areas consist of a sub-micrometer-thick nematic layer sandwiched between dielectric mirrors and indium tin oxide (ITO)-electrodes. These cells shall switch narrowband light of red, green or blue. A barrier filter array for a high resolution, glasses-free 3D display has to be equipped with several thousand switchable filter elements having different color apertures. Full article

(This article belongs to the Special Issue Optical Modulators and Switches)

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17 pages, 6165 KiB

Open AccessArticle

Surrogate Based Optimization of Aerodynamic Noise for Streamlined Shape of High Speed Trains

by Zhenxu Sun^*

, Ye Zhang

and Guowei Yang

Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Appl. Sci. 2017, 7(2), 196; https://doi.org/10.3390/app7020196 - 17 Feb 2017

Cited by 23 | Viewed by 8001

Abstract

Aerodynamic noise increases with the sixth power of the running speed. As the speed increases, aerodynamic noise becomes predominant and begins to be the main noise source at a certain high speed. As a result, aerodynamic noise has to be focused on when [...] Read more.

Aerodynamic noise increases with the sixth power of the running speed. As the speed increases, aerodynamic noise becomes predominant and begins to be the main noise source at a certain high speed. As a result, aerodynamic noise has to be focused on when designing new high-speed trains. In order to perform the aerodynamic noise optimization, the equivalent continuous sound pressure level (SPL) has been used in the present paper, which could take all of the far field observation probes into consideration. The Non-Linear Acoustics Solver (NLAS) approach has been utilized for acoustic calculation. With the use of Kriging surrogate model, a multi-objective optimization of the streamlined shape of high-speed trains has been performed, which takes the noise level in the far field and the drag of the whole train as the objectives. To efficiently construct the Kriging model, the cross validation approach has been adopted. Optimization results reveal that both the equivalent continuous sound pressure level and the drag of the whole train are reduced in a certain extent. 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, 2548 KiB

Open AccessArticle

Simulation of Hybrid Photovoltaic Solar Assisted Loop Heat Pipe/Heat Pump System

by Nannan Dai¹

, Xinyi Xu¹, Shuhong Li^1,* and Zheng Zhang²

¹ School of Energy and Environment, Southeast University, Nanjing 210000, China

² Gemdale Properties and Investment Corporation Limited, Shanghai 200000, China

Appl. Sci. 2017, 7(2), 197; https://doi.org/10.3390/app7020197 - 16 Feb 2017

Cited by 28 | Viewed by 7088

Abstract

A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP) water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP) mode and heat pump (HP) mode, and the two modes can be run separately [...] Read more.

A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP) water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP) mode and heat pump (HP) mode, and the two modes can be run separately or compositely according to the weather conditions. The performances of independent heat pump (HP) mode and hybrid loop heat pipe/heat pump (LHP/HP) mode were simulated and compared. Simulation results showed that on typical sunny days in spring or autumn, using LHP/HP mode could save 40.6% power consumption than HP mode. In addition, the optimal switchover from LHP mode to HP mode was analyzed in different weather conditions for energy saving and the all-year round operating performances of the system were also simulated. The simulation results showed that hybrid LHP/HP mode should be utilized to save electricity on sunny days from March to November and the system can rely on LHP mode alone without any power consumption in July and August. When solar radiation and ambient temperature are low in winter, HP mode should be used Full article

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

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27 pages, 5517 KiB

Open AccessArticle

Experimental Investigation on Soft Galloping and Hard Galloping of Triangular Prisms

by Jijian Lian¹, Xiang Yan¹

, Fang Liu^1,*

, Jun Zhang¹, Quanchao Ren¹ and Xu Yang²

¹ State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China

² Department of Civil Engineering, Case Western Reserve University, Cleveland, OH 44106, USA

Appl. Sci. 2017, 7(2), 198; https://doi.org/10.3390/app7020198 - 17 Feb 2017

Cited by 32 | Viewed by 5134

Abstract

The studies currently on soft galloping (SG) and hard galloping (HG) are scarce. In this study, SG and HG of spring-mounted triangular prisms in a water channel are investigated experimentally. A power take-off system (PTO), a spring system, additional weights, and different triangular [...] Read more.

The studies currently on soft galloping (SG) and hard galloping (HG) are scarce. In this study, SG and HG of spring-mounted triangular prisms in a water channel are investigated experimentally. A power take-off system (PTO), a spring system, additional weights, and different triangular prisms were used to achieve the variations in damping coefficient c, system stiffness K, oscillation mass m and section aspect ratios α, respectively. The present paper proves that the VIV (vortex-induced vibration) lower branch can be observed in the SG response. In SG response, VIV branches are incomplete while the galloping branch is complete, and galloping can be self-initiated only in the self-excited region. On the contrary, in HG response, VIV branches are complete, the galloping branch is incomplete, and galloping can only be initiated by external excitation at a velocity exceeding the critical velocity. As c and m increase, or K and α decrease, the oscillation mode of a triangular prism gradually transitions from SG to CG (critical galloping), and continues to HG. The amplitude in VIV branch is the main reason causing the onset of galloping in SG response. A critical damping coefficient c_c, which is dependent on m, K and α, is proposed to predict the occurrences of SG, CG and HG. When c < c_c, SG occurs; when c > c_c, HG occurs; when c = c_c, CG occurs. Full article

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12 pages, 4115 KiB

Open AccessArticle

Surface Quality of Staggered PCD End Mill in Milling of Carbon Fiber Reinforced Plastics

by Guangjun Liu¹, Hongyuan Chen¹, Zhen Huang¹, Fei Gao² and Tao Chen^2,*

¹ School of Mechanical Engineering, Tongji University, Shanghai 201804, China

² School of Mechanical and Power Engineering, Harbin University of Science and Technology, Harbin 150080, China

Appl. Sci. 2017, 7(2), 199; https://doi.org/10.3390/app7020199 - 17 Feb 2017

Cited by 25 | Viewed by 6792

Abstract

Machined surface quality determines the reliability, wear resistance and service life of carbon fiber reinforced plastic (CFRP) workpieces. In this work, the formation mechanism of the surface topography and the machining defects of CFRPs are proposed, and the influence of milling parameters and [...] Read more.

Machined surface quality determines the reliability, wear resistance and service life of carbon fiber reinforced plastic (CFRP) workpieces. In this work, the formation mechanism of the surface topography and the machining defects of CFRPs are proposed, and the influence of milling parameters and fiber cutting angles on the surface quality of CFRPs is obtained, which can provide a reference for extended tool life and good surface quality. Trimming and slot milling tests of unidirectional CFRP laminates are performed. The surface roughness of the machined surface is measured, and the influence of milling parameters on the surface roughness is analyzed. A regression model for the surface roughness of CFRP milling is established. A significance test of the regression model is conducted. The machined surface topography of milling CFRP unidirectional laminates with different fiber orientations is analyzed, and the effect of fiber cutting angle on the surface topography of the machined surface is presented by using a digital super depth-of-field microscope and scanning electron microscope (SEM). To study the influence of fiber cutting angle on machining defects, the machined topography under different fiber orientations is analyzed. The slot milling defects and their formation mechanism under different fiber cutting angles are investigated. Full article

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17 pages, 3550 KiB

Open AccessArticle

Comparative Interactions of Dihydroquinazolin Derivatives with Human Serum Albumin Observed via Multiple Spectroscopy

by Yi Wang^1,2, Meiqing Zhu¹, Jia Liu^1,3, Risong Na^1,3, Feng Liu², Xiangwei Wu¹, Shisuo Fan¹, Zhen Wang¹, Dandan Pan¹, Jun Tang¹, Qing X. Li⁴

, Rimao Hua^1,* and Shangzhong Liu^2,*

¹ Department of Science of Pesticides, School of Resources and Environment, Anhui Agricultural University, No. 130 Changjiang West Road, Hefei 230036, China

² Department of Applied Chemistry, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing 100193, China

³ Collaborative Innovation Center of Henan Grain Crops, National Key Laboratory of Wheat and Maize Crop Science, College of Plant Protection, Henan Agricultural University, Wenhua Road No. 95, Zhengzhou 450002, China

⁴ Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA

Appl. Sci. 2017, 7(2), 200; https://doi.org/10.3390/app7020200 - 17 Feb 2017

Cited by 11 | Viewed by 5102

Abstract

The interactions of dihydroquinazolines with human serum albumin (HSA) were studied in pH 7.4 aqueous solution via fluorescence, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic techniques. In this work, 6-chloro-1-(3,3-dimethyl-butanoyl)-2(un)substitutedphenyl-2,3-dihydroquinazolin-4(1H)-one (PDQL) derivatives were designed and synthesized to study the impact of [...] Read more.

The interactions of dihydroquinazolines with human serum albumin (HSA) were studied in pH 7.4 aqueous solution via fluorescence, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic techniques. In this work, 6-chloro-1-(3,3-dimethyl-butanoyl)-2(un)substitutedphenyl-2,3-dihydroquinazolin-4(1H)-one (PDQL) derivatives were designed and synthesized to study the impact of five similar substituents (methyl, methoxy, cyano, trifluoromethyl and isopropyl) on the interactions between PDQL and HSA using a comparative methodology. The results revealed that PDQL quenched the intrinsic fluorescence of HSA through a static quenching process. Displacement experiments with site-specific markers revealed that PDQL binds to HSA at site II (subdomain IIIA) and that there may be only one binding site for PDQL on HSA. The thermodynamic parameters indicated that hydrophobic interactions mainly drove the interactions between PDQL and HSA. The substitution using five similar groups in the benzene ring could increase the interactions between PDQL and HSA to some extent through the van der Waals force or hydrogen bond effects in the proper temperature range. Isopropyl substitution could particularly enhance the binding affinity, as observed via comparative studies Full article

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

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13 pages, 2811 KiB

Open AccessArticle

Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load

by Zheng Lu^1,2

, Yuling Yang²

, Xilin Lu^1,2 and Chengqing Liu^3,*

¹ State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China

² Research Institute of Structural Engineering and Disaster Reduction, Tongji University, Shanghai 200092, China

³ School of civil engineering, Southwest JiaoTong University, Chengdu 610031, China

Appl. Sci. 2017, 7(2), 201; https://doi.org/10.3390/app7020201 - 20 Feb 2017

Cited by 41 | Viewed by 6328

Abstract

Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we [...] Read more.

Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we propose a new type of device, a lateral damping buffer, to reduce the vulnerability of building structures to debris flows. This lateral damping buffer has two mechanisms of damage mitigation: when debris flows impact on a building, it acts as a buffer, and when the structure vibrates due to the impact, it acts as a shock absorber, which can reduce the maximum acceleration response and subsequent vibration respectively. To study the effectiveness of such a lateral damping buffer, an impact test is conducted, which mainly involves a lateral damping buffer attached to a two-degree-of-freedom structure under a simulated debris flow load. To enable the numerical study, the equation of motion of the structure along with the lateral damping buffer is derived. A subsequent parametric study is performed to optimize the lateral damping buffer. Finally, a practical design procedure is also provided. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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22 pages, 6766 KiB

Open AccessArticle

Numerical Study on the Asphalt Concrete Structure for Blast and Impact Load Using the Karagozian and Case Concrete Model

by Jun Wu^1,2, Liang Li^1,*, Xiuli Du¹ and Xuemei Liu³

¹ The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China

² School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China

³ School of Civil Engineering and Built Environment, Queensland University of Technology, Brisbane 4001, Australia

Appl. Sci. 2017, 7(2), 202; https://doi.org/10.3390/app7020202 - 17 Feb 2017

Cited by 20 | Viewed by 6969

Abstract

The behaviour of an asphalt concrete structure subjected to severe loading, such as blast and impact loadings, is becoming critical for safety and anti-terrorist reasons. With the development of high-speed computational capabilities, it is possible to carry out the numerical simulation of an [...] Read more.

The behaviour of an asphalt concrete structure subjected to severe loading, such as blast and impact loadings, is becoming critical for safety and anti-terrorist reasons. With the development of high-speed computational capabilities, it is possible to carry out the numerical simulation of an asphalt concrete structure subjected to blast or impact loading. In the simulation, the constitutive model plays a key role as the model defines the essential physical mechanisms of the material under different stress and loading conditions. In this paper, the key features of the Karagozian and Case concrete model (KCC) adopted in LSDYNA are evaluated and discussed. The formulations of the strength surfaces and the damage factor in the KCC model are verified. Both static and dynamic tests are used to determine the parameters of asphalt concrete in the KCC model. The modified damage factor is proposed to represent the higher failure strain that can improve the simulation of the behaviour of AC material. Furthermore, a series test of the asphalt concrete structure subjected to blast and impact loadings is conducted and simulated by using the KCC model. The simulation results are then compared with those from both field and laboratory tests. The results show that the use of the KCC model to simulate asphalt concrete structures can reproduce similar results as the field and laboratory test. Full article

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

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20 pages, 3554 KiB

Open AccessArticle

Fuzzy Synthetic Evaluation of the Long-Term Health of Tunnel Structures

by Bo Wang, Chencong Mo, Chuan He and Qixiang Yan^*

Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China

Appl. Sci. 2017, 7(2), 203; https://doi.org/10.3390/app7020203 - 17 Feb 2017

Cited by 23 | Viewed by 5980

Abstract

A tunnel is a coupled system of the surrounding rock and the supporting structure. The health status of a tunnel structure is complex and is influenced by various factors. In addition, these factors are coupled and interacted with each other, which calls for [...] Read more.

A tunnel is a coupled system of the surrounding rock and the supporting structure. The health status of a tunnel structure is complex and is influenced by various factors. In addition, these factors are coupled and interacted with each other, which calls for the linguistic description of the tunnel safety level. In this paper, we describe the health status of a highway tunnel structure in terms of four levels: safe; basically safe; potentially unsafe and unsafe. Based on the analysis of the safety characteristics of the tunnel structure and its proposed safety level, this research develops a multi-level fuzzy synthetic evaluation model for the long-term safety evaluation system of a tunnel structure. The Cang Ling Tunnel, which has embedded sensors to measure the stress values of the secondary lining and the contact pressure, is used as an example to study the proposed method. The results show that the structure of the entire Cang Ling Tunnel is in almost a safe condition under the current conditions, which is consistent with the actual operational situation. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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14 pages, 499 KiB

Open AccessArticle

An Adaptive Buffering Scheme for P2P Live and Time-Shifted Streaming

by Eunsam Kim¹

, Taeyoung Kim² and Choonhwa Lee^3,*

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

² Pasoo Inc., 396 Worldcup bukro, Mapo-gu, Seoul 03925, Korea

³ Division of Computer Science and Engineering, Hanyang University, Seoul 04763, Korea

Appl. Sci. 2017, 7(2), 204; https://doi.org/10.3390/app7020204 - 18 Feb 2017

Cited by 5 | Viewed by 5191

Abstract

Recently, P2P streaming techniques have been a promising solution to a large-scale live streaming system because of their high scalability and low installation cost. In P2P live streaming systems, however, it is difficult to manage peers’ buffers effectively, because they can buffer only [...] Read more.

Recently, P2P streaming techniques have been a promising solution to a large-scale live streaming system because of their high scalability and low installation cost. In P2P live streaming systems, however, it is difficult to manage peers’ buffers effectively, because they can buffer only a limited amount of data around a live broadcasting time in the main memory and suffer from long playback lag due to the nature of P2P structures. In addition, the number of peers decreases rapidly as the playback position moves further from this time by performing time-shifted viewing. These situations widen the distribution of peers’ playback positions, thereby decreasing the degree of data duplication among peers. Moreover, it is hard to use each peer’s buffer as the caching area because the buffer area where the chunks that have already been played back are stored can be overwritten at any time by new chunks that will arrive soon. In this paper, we therefore propose a novel buffering scheme to significantly increase data duplication in buffering periods among peers in P2P live and time-shifted streaming systems. In our proposed scheme, the buffer ratio of each peer is adaptively adjusted according to its relative playback position in a group by increasing the ratio of the caching area in its buffer as its playback position moves earlier in time and increasing the ratio of the prefetching area as its playback position moves later. Through extensive simulations, we demonstrate that our proposed adaptive buffering scheme outperforms the conventional buffering technique considerably in terms of startup delay, average jitter ratio, and the ratio of necessary chunks in a buffermap. Full article

(This article belongs to the Special Issue High-Performance and Parallel Computer Systems: Design and Algorithms)

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12 pages, 2988 KiB

Open AccessArticle

Microwave-Assisted Synthesis of SiC Nanoparticles for the Efficient Adsorptive Removal of Nitroimidazole Antibiotics from Aqueous Solution

by Ali Fakhri^1,*, Sahar Rashidi², Mohammad Asif^3,* and Ahmed A. Ibrahim³

¹ Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran, Iran

² Department of Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran

³ Department of Chemical Engineering, King Saud University, Riyadh 11421, Saudi Arabia

Appl. Sci. 2017, 7(2), 205; https://doi.org/10.3390/app7020205 - 20 Feb 2017

Cited by 27 | Viewed by 4946

Abstract

Environmental pollution caused by the improper disposal of pharmaceuticals is a matter of global concern, and warrants immediate attention. Of particular concern is the aquatic contamination caused by the increasing use of antibiotics, which could give rise to superbugs. While researchers have mainly [...] Read more.

Environmental pollution caused by the improper disposal of pharmaceuticals is a matter of global concern, and warrants immediate attention. Of particular concern is the aquatic contamination caused by the increasing use of antibiotics, which could give rise to superbugs. While researchers have mainly focused on improving the adsorption capacity of mostly activated carbon-based adsorbents, we have developed a non-conventional adsorbent (SiC nanoparticles) in the present work for the adsorptive removal of four different nitroimidazole antibiotics, namely metronidazole (MNZ), dimetridazole (DMZ), ronidazole (RNZ), and tinidazole (TNZ). In addition to the unique properties which are inherent to SiC, the present adsorbent not only possesses a high adsorption capacity, but also shows one of the highest adsorption rates; both of which are prerequisites for an efficient and cost-effective adsorption-based separation technology. Silicon carbide (SiC) nanoparticles, synthesized by a microwave-assisted method, were thoroughly characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and the Brunauer–Emmett–Teller method. The adsorption isotherm data were accurately described by the Langmuir isotherm model. On the other hand, the adsorption kinetics, closely represented by the pseudo-second order kinetic model, were faster than most previously reported adsorbents. The reaction rate constants were 0.0089, 0.0079, 0.0072, and 0.0055 g/(mg min), for MNZ, DMZ, RNZ, and TNZ, respectively. Full article

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

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14 pages, 2168 KiB

Open AccessArticle

LED Current Balance Using a Variable Voltage Regulator with Low Dropout vDS Control

by Hung-I Hsieh^* and Hao Wang

Department of Electrical Engineering, National Chiayi University, Chiayi City 60004, Taiwan

Appl. Sci. 2017, 7(2), 206; https://doi.org/10.3390/app7020206 - 20 Feb 2017

Cited by 5 | Viewed by 7091

Abstract

A cost-effective light-emitting diode (LED) current balance strategy using a variable voltage regulator (VVR) with low dropout vDS control is proposed. This can regulate the multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) of the linear current regulators (LCR), maintaining low dropout vDS on the flat [...] Read more.

A cost-effective light-emitting diode (LED) current balance strategy using a variable voltage regulator (VVR) with low dropout vDS control is proposed. This can regulate the multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) of the linear current regulators (LCR), maintaining low dropout vDS on the flat vGS-characteristic curves and making all drain currents almost the same. Simple group LCRs respectively loaded with a string LED are employed to implement the theme. The voltage VVdc from a VVR is synthesized by a string LED voltage NvD, source voltage vR, and a specified low dropout vDS = VQ. The VVdc updates instantly, through the control loop of the master LCR, which means that all slave MOSFETs have almost the same biases on their flat vGS-characteristic curves. This leads to all of the string LED currents being equal to each other, producing an almost even luminance. An experimental setup with microchip control is built to verify the estimations. Experimental results show that the luminance of all of the string LEDs are almost equal to one another, with a maximum deviation below 1% during a wide dimming range, while keeping all vDS of the MOSFETs at a low dropout voltage, as expected. Full article

(This article belongs to the Special Issue Energy Saving)

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22 pages, 5861 KiB

Open AccessArticle

Application of the DC Offset Cancellation Method and S Transform to Gearbox Fault Diagnosis

by Xinghui Zhang^1,*, Jianmin Zhao¹, Rusmir Bajrić²

and Liangliang Wang¹

¹ The management department of Mechanical Engineering College, Shijiazhuang 050003, China

² Public Enterprise Elektroprivreda BiH, Coal Mines Kreka, Tuzla 75000, Bosnia and Herzegovina

Appl. Sci. 2017, 7(2), 207; https://doi.org/10.3390/app7020207 - 20 Feb 2017

Cited by 12 | Viewed by 6340

Abstract

In this paper, the direct current (DC) offset cancellation and S transform-based diagnosis method is verified using three case studies. For DC offset cancellation, correlated kurtosis (CK) is used instead of the cross-correlation coefficient in order to determine the optimal iteration number. Compared [...] Read more.

In this paper, the direct current (DC) offset cancellation and S transform-based diagnosis method is verified using three case studies. For DC offset cancellation, correlated kurtosis (CK) is used instead of the cross-correlation coefficient in order to determine the optimal iteration number. Compared to the cross-correlation coefficient, CK enhances the DC offset cancellation ability enormously because of its excellent periodic impulse signal detection ability. Here, it has been proven experimentally that it can effectively diagnose the implanted bearing fault. However, the proposed method is less effective in the case of simultaneously present bearing and gear faults, especially for extremely weak bearing faults. In this circumstance, the iteration number of DC offset cancellation is determined directly by the high-speed shaft gear mesh frequency order. For the planetary gearbox, the application of the proposed method differs from the fixed-axis gearbox, because of its complex structure. For those small fault frequency parts, such as planet gear and ring gear, the DC offset cancellation’s ability is less effective than for the fixed-axis gearbox. In these studies, the S transform is used to display the time-frequency characteristics of the DC offset cancellation processed results; the performances are evaluated, and the discussions are given. The fault information can be more easily observed in the time-frequency contour than the frequency domain. Full article

(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)

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11 pages, 7271 KiB

Open AccessArticle

Overload Control in Smart Transformer-Fed Grid

by Giovanni De Carne^1,*

, Zhixiang Zou¹

, Giampaolo Buticchi¹, Marco Liserre¹ and Costas Vournas²

¹ Power Electronics, Christian-Albrechts University of Kiel, Kiel D-24143, Germany

² School of Electrical and Computer Engineering, National Technical University of Athens, Athens 157 80, Greece

Appl. Sci. 2017, 7(2), 208; https://doi.org/10.3390/app7020208 - 20 Feb 2017

Cited by 14 | Viewed by 6985

Abstract

Renewable energy resources and new loads—such as electric vehicles—challenge grid management. Among several scenarios, the smart transformer represents a solution for simultaneously managing low- and medium-voltage grids, providing ancillary services to the distribution grid. However, unlike conventional transformers, the smart transformer has a [...] Read more.

Renewable energy resources and new loads—such as electric vehicles—challenge grid management. Among several scenarios, the smart transformer represents a solution for simultaneously managing low- and medium-voltage grids, providing ancillary services to the distribution grid. However, unlike conventional transformers, the smart transformer has a very limited overload capability, because the junction temperature—which must always be below its maximum limit—is characterized by a short time constant. In this work, an overload control for smart transformer by means of voltage and frequency variations has been proposed and veriﬁed by means of simulations and experiments. Full article

(This article belongs to the Special Issue Advancing Grid-Connected Renewable Generation Systems)

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