Applied Sciences

17 pages, 2652 KiB

Open AccessArticle

Severity Prediction of Traffic Accidents with Recurrent Neural Networks

by Maher Ibrahim Sameen^† and Biswajeet Pradhan^*,†

¹ Department of Civil Engineering, Geospatial Information Science Research Center (GISRC), Faculty of Engineering, University Putra Malaysia, UPM, Serdang 43400, Malaysia

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 476; https://doi.org/10.3390/app7060476 - 8 Jun 2017

Cited by 181 | Viewed by 14939

Abstract

In this paper, a deep learning model using a Recurrent Neural Network (RNN) was developed and employed to predict the injury severity of traffic accidents based on 1130 accident records that have occurred on the North-South Expressway (NSE), Malaysia over a six-year period [...] Read more.

In this paper, a deep learning model using a Recurrent Neural Network (RNN) was developed and employed to predict the injury severity of traffic accidents based on 1130 accident records that have occurred on the North-South Expressway (NSE), Malaysia over a six-year period from 2009 to 2015. Compared to traditional Neural Networks (NNs), the RNN method is more effective for sequential data, and is expected to capture temporal correlations among the traffic accident records. Several network architectures and configurations were tested through a systematic grid search to determine an optimal network for predicting the injury severity of traffic accidents. The selected network architecture comprised of a Long-Short Term Memory (LSTM) layer, two fully-connected (dense) layers and a Softmax layer. Next, to avoid over-fitting, the dropout technique with a probability of 0.3 was applied. Further, the network was trained with a Stochastic Gradient Descent (SGD) algorithm (learning rate = 0.01) in the Tensorflow framework. A sensitivity analysis of the RNN model was further conducted to determine these factors’ impact on injury severity outcomes. Also, the proposed RNN model was compared with Multilayer Perceptron (MLP) and Bayesian Logistic Regression (BLR) models to understand its advantages and limitations. The results of the comparative analyses showed that the RNN model outperformed the MLP and BLR models. The validation accuracy of the RNN model was 71.77%, whereas the MLP and BLR models achieved 65.48% and 58.30% respectively. The findings of this study indicate that the RNN model, in deep learning frameworks, can be a promising tool for predicting the injury severity of traffic accidents. Full article

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

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19 pages, 10391 KiB

Open AccessArticle

Separation Control on a Bridge Box Girder Using a Bypass Passive Jet Flow

by Liang-Quan Zhang¹, Guan-Bin Chen¹

, Wen-Li Chen^2,3,*

and Dong-Lai Gao^2,3

¹ School of Civil Engineering, Northeast Forestry University, Harbin 150040, China

² Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin 150090, China

³ Key Lab of Structures Dynamic Behavior and Control of Ministry of Education, Harbin Institute of Technology, Harbin 150090, China

Appl. Sci. 2017, 7(6), 501; https://doi.org/10.3390/app7060501 - 24 May 2017

Cited by 22 | Viewed by 5374

Abstract

In the present study, a bypass passive jet flow control method was proposed to mitigate unsteady wind loads and to manipulate the flow field around a single box girder of a bridge. With a geometric ratio of 1:125, the single box girder model [...] Read more.

In the present study, a bypass passive jet flow control method was proposed to mitigate unsteady wind loads and to manipulate the flow field around a single box girder of a bridge. With a geometric ratio of 1:125, the single box girder model was determined using the cross-section of the Great Belt East Bridge. During the experiments, one test model without control was adopted, while five different test models with different suction/jet configurations were employed to analyze the effects of the control method and to reveal the underlying mechanism of different control schemes. The incoming wind speed was fixed to 12 m/s and the wind attack angles were changed from −20° to 20°, resulting in a corresponding Reynolds number of Re = 0.28 × 10⁵–0.74 × 10⁵ based on the different attack angles. A six-component force balance, a set of digital sensor array (DSA) pressure transducers, and a particle image velocimetry (PIV) system was used to measure the aerodynamic forces, pressure distributions, and flow fields around the test models to evaluate the control effectiveness of different control cases. Detailed flow structures are presented and discussed for two test cases when the angles of attack are +15° and −20°. The effects of control on the aerodynamic forces were first investigated to determine and select the best one out of five control cases. The pressure distributions on the surface of the test model without control and the best control case were then compared to evaluate the control effectiveness of the pressure gradient and the fluctuating pressure coefficients. The flow fields around the test models demonstrate that the bypass passive jet flow control could decrease vortex strength, delay flow separation, and change recirculation region and size. The results of the aerodynamic forces, pressure distributions, and flow fields indicate that the bypass passive jet flow control method results in effective control. Full article

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8 pages, 2503 KiB

Open AccessArticle

Improved Performance of High-Voltage Vertical GaN LEDs via Modification of Micro-Cell Geometry

by Ping-Chen Wu¹, Sin-Liang Ou², Ray-Hua Horng³

and Dong-Sing Wuu^1,*

¹ Department of Materials Science and Engineering, National Chung Hsing University, Taichung 40227, Taiwan

² Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan

³ Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan

Appl. Sci. 2017, 7(6), 506; https://doi.org/10.3390/app7060506 - 24 May 2017

Cited by 4 | Viewed by 4572

Abstract

Vertical-type high-voltage light-emitting diodes (HV-LEDs) with 2 × 2 micro-cells were fabricated on Cu substrates, and the micro-cell geometry was modified to enhance the optoelectronic performance. The current spreading in micro-cell is most dominantly affected by the distance between electrode and edge of [...] Read more.

Vertical-type high-voltage light-emitting diodes (HV-LEDs) with 2 × 2 micro-cells were fabricated on Cu substrates, and the micro-cell geometry was modified to enhance the optoelectronic performance. The current spreading in micro-cell is most dominantly affected by the distance between electrode and edge of chip. When square cells were combined in a HV-LED, the device performance was poor due to an obvious current-crowding phenomenon that occurred near the electrodes. This was attributed that the electrodes in these four square micro-cells were all far away from the edges, resulting in the severe current-crowding phenomenon. On the contrary, as the HV-LED was prepared with four rectangle, triangle, or L-shaped micro-cells, the electrodes were close to the edges of micro-cells and the current spreading effect can be easily improved. Although a HV-LED connected with L-shaped cells possessed a better current spreading effect and a lower surface temperature, the light extraction was relatively low because of an electrode-shading loss effect. When triangular cells were used to prepare the HV-LED, the device achieved a superior optoelectronic performance compared with that of other cells because of a lower current-crowding effect and a more uniform light emission. After an epoxy package process, a lower forward voltage of 14.9 V and a higher output power of 353.2 mW were obtained using this HV-LED at an injection current of 80 mA. Additionally, the wall-plug efficiencies of this device at 20 and 80 mA were 41.1% and 29.7%, respectively. The results confirm that the design of triangular cell is beneficial for enhancing the optoelectronic performance of HV-LEDs. Furthermore, the fabrication processes of vertical LEDs have high potential for HV-LED applications. Full article

(This article belongs to the Section Optics and Lasers)

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19 pages, 4199 KiB

Open AccessArticle

Passive Vibration Control of a Semi-Submersible Floating Offshore Wind Turbine

by Chao Li¹

, Tongyi Zhuang¹, Shengtao Zhou¹, Yiqing Xiao^1,* and Gang Hu²

¹ Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China

² Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

Appl. Sci. 2017, 7(6), 509; https://doi.org/10.3390/app7060509 - 26 May 2017

Cited by 56 | Viewed by 7332

Abstract

Floating offshore wind turbines have the potential to commercially convert the vast wind resource in deep-water area. Compared with fixed-bottom wind turbines, motions of the floating foundation complicate vibrations and loads of the wind turbine in offshore environment. To alleviate the responses of [...] Read more.

Floating offshore wind turbines have the potential to commercially convert the vast wind resource in deep-water area. Compared with fixed-bottom wind turbines, motions of the floating foundation complicate vibrations and loads of the wind turbine in offshore environment. To alleviate the responses of the wind turbine, this study investigates the use of fore–aft tuned mass damper (TMD) in nacelle/tower for passive control of a semi-submersible offshore wind turbine. A simplified structural model, considering the degree-of-freedom of platform pitch and surge, tower tilt and TMD translation, is proposed in the light of motion features of semi-submersible platform. After identifying ten unknown parameters, the correctness of the deterministic model is validated by pitch free decay responses. The mass, stiffness and damping of TMD are optimized using both method of exhaustion and genetic algorithm to avoid local minimum. Six optimized TMD devices are evaluated under three kinds of realistic environment conditions. The control effectiveness is assessed by the extreme and fatigue response reduction ratios. It is found that the high stiffness TMDs that directly dissipate the energy of tower oscillation exhibit an overall stable performance. Similar to the spar-type foundation, the TMDs in the nacelle/tower are capable of extending the service life of floating wind turbines. Full article

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16 pages, 2286 KiB

Open AccessArticle

Direct-Current Forced Interruption and Breaking Performance of Spiral-Type Contacts in Aero Applications

by Wenlei Huo^1,*, Jianwen Wu¹, Bowen Jia¹, Mingxuan Chen¹

, Suliang Ma¹ and Liying Zhu²

¹ School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

² Institute of Spacecraft System Engineering CAST, Beijing 100191, China

Appl. Sci. 2017, 7(6), 512; https://doi.org/10.3390/app7060512 - 26 May 2017

Cited by 1 | Viewed by 4879

Abstract

This paper analyses the transient characteristics and breaking performance of direct-current (DC) forced-interruption vacuum interrupters in 270 V power-supply systems. Three stages are identified in forced interruption: the DC-arcing stage, current-commutation stage, and voltage-recovery stage. During the current-commutation stage, the reverse peak-current coefficient [...] Read more.

This paper analyses the transient characteristics and breaking performance of direct-current (DC) forced-interruption vacuum interrupters in 270 V power-supply systems. Three stages are identified in forced interruption: the DC-arcing stage, current-commutation stage, and voltage-recovery stage. During the current-commutation stage, the reverse peak-current coefficient k, which is a key design factor, is used to calculate the rate of current at zero-crossing (di/dt). MATLAB/Simulink simulation models are established to obtain the transient characteristics influenced by the forced-commutation branch parameters and the coefficient k. To study the breaking performance of spiral-type contacts, experiments are conducted for different contact materials and arcing times for currents less than 3.5 kA. During the DC-arcing stage, a locally intensive burning arc is observed in the CuW80 contact; however, it is not observed in the CuCr50 contact. On examining the re-ignition interruption results of the CuW80 contact, the intensive burning arc is found to be positioned within a possible re-ignition region. When the arcing time is longer than 1 ms, the intensive burning arc occurs and affects the breaking performance of the spiral-type contacts. If the DC-arcing stage is prolonged, the total arcing energy increases, which leads to a lower breaking capacity. Full article

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12 pages, 3456 KiB

Open AccessArticle

Equivalence between Fuzzy PID Controllers and Conventional PID Controllers

by Chun-Tang Chao, Nana Sutarna, Juing-Shian Chiou^* and Chi-Jo Wang

Department of Electrical Engineering, Southern Taiwan University of Science and Technology, 1, Nan-Tai St., Yongkang District, Tainan City 71005, Taiwan

Appl. Sci. 2017, 7(6), 513; https://doi.org/10.3390/app7060513 - 2 Jun 2017

Cited by 50 | Viewed by 11577

Abstract

This paper proposes the equivalence between fuzzy Proportional-Integral-Derivative (PID) controllers and conventional PID controllers. A well-designed conventional PID controller, with the help of the proposed method, can be rapidly transformed to an equivalent fuzzy logic controller (FLC) by observing and defining the operating [...] Read more.

This paper proposes the equivalence between fuzzy Proportional-Integral-Derivative (PID) controllers and conventional PID controllers. A well-designed conventional PID controller, with the help of the proposed method, can be rapidly transformed to an equivalent fuzzy logic controller (FLC) by observing and defining the operating ranges of the input/output of the controller. Furthermore, the knowledge base of the proposed equivalent fuzzy PID controller is represented as a cube fuzzy associative memory (FAM), instead of a combination of PD-type and PI-type FLCs in most research. Simulation results show the feasibility of the proposed technique, both in continuous and discrete time. Since the design techniques of conventional linear PID controllers have matured, they can act as preliminary expert knowledge for nonlinear FLCs designs. Based on the proposed equivalence relationship, the designer can further tune the membership functions of fuzzy variables in the control rules to exhibit the nonlinearity of a FLC and yield more satisfactory system responses in an efficient way. Full article

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17 pages, 4320 KiB

Open AccessArticle

An Automatic Measurement Method for Absolute Depth of Objects in Two Monocular Images Based on SIFT Feature

by Lixin He^1,2,3,*, Jing Yang^2,*, Bin Kong² and Can Wang²

¹ Department of Automation, University of Science and Technology of China, Hefei 230027, China

² Hefei Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China

³ The Key Lab of Network and Intelligent Information Processing, Hefei University, Hefei 230601, China

Appl. Sci. 2017, 7(6), 517; https://doi.org/10.3390/app7060517 - 25 May 2017

Cited by 16 | Viewed by 4986

Abstract

Recovering depth information of objects from two-dimensional images is one of the very important and basic problems in the field of computer vision. In view of the shortcomings of existing methods of depth estimation, a novel approach based on SIFT (the Scale Invariant [...] Read more.

Recovering depth information of objects from two-dimensional images is one of the very important and basic problems in the field of computer vision. In view of the shortcomings of existing methods of depth estimation, a novel approach based on SIFT (the Scale Invariant Feature Transform) is presented in this paper. The approach can estimate the depths of objects in two images which are captured by an un-calibrated ordinary monocular camera. In this approach, above all, the first image is captured. All of the camera parameters remain unchanged, and the second image is acquired after moving the camera a distance d along the optical axis. Then image segmentation and SIFT feature extraction are implemented on the two images separately, and objects in the images are matched. Lastly, an object’s depth can be computed by the lengths of a pair of straight line segments. In order to ensure that the most appropriate pair of straight line segments are chosen, and also reduce computation, convex hull theory and knowledge of triangle similarity are employed. The experimental results show our approach is effective and practical. Full article

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16 pages, 6230 KiB

Open AccessArticle

Analysis of Preparation and Properties on Shape Memory Hydrogenated Epoxy Resin Used for Asphalt Mixtures

by Biao Ma¹, Xueyan Zhou^1,*, Kun Wei¹, Yanzhen Bo¹ and Zhanping You^1,2

¹ Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an 710064, China

² Department of Civil and Engineering Environment, Michigan Technological University, Houghton, MI 49931, USA

Appl. Sci. 2017, 7(6), 523; https://doi.org/10.3390/app7060523 - 23 May 2017

Cited by 22 | Viewed by 5324

Abstract

The objective of this investigation is to prepare the shape memory hydrogenated epoxy resin used for asphalt mixtures (SM-HEP-AM) and study its properties. The shape memory hydrogenated epoxy resin (SM-HEP) is prepared using hydrogenated bisphenol A epoxy resin (AL-3040), polypropylene glycol diglycidylether diacrylate [...] Read more.

The objective of this investigation is to prepare the shape memory hydrogenated epoxy resin used for asphalt mixtures (SM-HEP-AM) and study its properties. The shape memory hydrogenated epoxy resin (SM-HEP) is prepared using hydrogenated bisphenol A epoxy resin (AL-3040), polypropylene glycol diglycidylether diacrylate (JH-230), and isophorone diamine (IPDA). The formulations of the SM-HEP-AM are obtained by the linearly fitted method. The thermo-mechanical property, molecular structure, and shape-memory performance of the SM-HEP-AM are studied. The glass-transition temperature (T_g) is determined using the differential scanning calorimeter (DSC). The results proved that the T_g level increased when the JH-230 content decreased. The thermo-mechanical property of the SM-HEP-AM is measured by dynamical mechanical analysis (DMA). The storage modulus of the SM-HEP-AM decreased with the increase in the JH-230 content. The above phenomena are attributed to the change in the JH-230 content. The shape memory performance results of the SM-HEP-AM indicate that specimen deformation can completely recover after only several minutes at T_g + 10 °C and T_g + 20 °C. The shape recovery time of the SM-HEP-AM increases with increased JH-230 content, and the change between the shape recovery time and JH-230 content gradually decreased as the temperature increased. The deformation recovery performance of asphalt mixture with and without the SM-HEP-AM (T_g = 40 °C) was tested by the deformation recovery test. This was used to prove that the SM-HEP-AM helps to improve the deformation recovery performance of the asphalt mixture. Full article

(This article belongs to the Section Mechanical Engineering)

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17 pages, 4463 KiB

Open AccessArticle

Stereoscopic Image Super-Resolution Method with View Incorporation and Convolutional Neural Networks

by Zhiyong Pan¹, Gangyi Jiang^1,*, Hao Jiang², Mei Yu^1,*, Fen Chen¹ and Qingbo Zhang²

¹ Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China

² Intelligent Household Appliances Engineering Center, Zhejiang Business Technology Institute, Ningbo 315012, China

Appl. Sci. 2017, 7(6), 526; https://doi.org/10.3390/app7060526 - 26 May 2017

Cited by 3 | Viewed by 5510

Abstract

Super-resolution (SR) plays an important role in the processing and display of mixed-resolution (MR) stereoscopic images. Therefore, a stereoscopic image SR method based on view incorporation and convolutional neural networks (CNN) is proposed. For a given MR stereoscopic image, the left view of [...] Read more.

Super-resolution (SR) plays an important role in the processing and display of mixed-resolution (MR) stereoscopic images. Therefore, a stereoscopic image SR method based on view incorporation and convolutional neural networks (CNN) is proposed. For a given MR stereoscopic image, the left view of which is observed in full resolution, while the right view is viewed in low resolution, the SR method is implemented in two stages. In the first stage, a view difference image is defined to represent the correlation between views. It is estimated by using the full-resolution left view and the interpolated right view as input to the modified CNN. Accordingly, a high-precision view difference image is obtained. In the second stage, to incorporate the estimated right view in the first stage, a global reconstruction constraint is presented to make the estimated right view consistent with the low-resolution right view in terms of the MR stereoscopic image observation model. Experimental results demonstrated that, compared with the SR convolutional neural network (SRCNN) method and depth map based SR method, the proposed method improved the reconstructed right view quality by 0.54 dB and 1.14 dB, respectively, in the Peak Signal to Noise Ratio (PSNR), and subjective evaluation also implied that the proposed method produced better reconstructed stereoscopic images. Full article

(This article belongs to the Special Issue Holography and 3D Imaging: Tomorrows Ultimate Experience)

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19 pages, 11475 KiB

Open AccessArticle

Fundamental Limits on Spatial Resolution in Ultrafast X-ray Diffraction

by Adam Kirrander^1,*

and Peter M. Weber²

¹ EaStCHEM, School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, UK

² Department of Chemistry, Brown University, Providence, RI 02912, USA

Appl. Sci. 2017, 7(6), 534; https://doi.org/10.3390/app7060534 - 23 May 2017

Cited by 28 | Viewed by 6456

Abstract

X-ray Free-Electron Lasers have made it possible to record time-sequences of diffraction images to determine changes in molecular geometry during ultrafast photochemical processes. Using state-of-the-art simulations in three molecules (deuterium, ethylene, and 1,3-cyclohexadiene), we demonstrate that the nature of the nuclear wavepacket initially [...] Read more.

X-ray Free-Electron Lasers have made it possible to record time-sequences of diffraction images to determine changes in molecular geometry during ultrafast photochemical processes. Using state-of-the-art simulations in three molecules (deuterium, ethylene, and 1,3-cyclohexadiene), we demonstrate that the nature of the nuclear wavepacket initially prepared by the pump laser, and its subsequent dispersion as it propagates along the reaction path, limits the spatial resolution attainable in a structural dynamics experiment. The delocalization of the wavepacket leads to a pronounced damping of the diffraction signal at large values of the momentum transfer vector q, an observation supported by a simple analytical model. This suggests that high-q measurements, beyond 10–15 Å

^{- 1}

, provide scant experimental payback, and that it may be advantageous to prioritize the signal-to-noise ratio and the time-resolution of the experiment as determined by parameters such as the repetition-rate, the photon flux, and the pulse durations. We expect these considerations to influence future experimental designs, including source development and detection schemes. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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17 pages, 3831 KiB

Open AccessArticle

Use of Rolling Piston Expanders for Energy Regeneration in Natural Gas Pressure Reduction Stations—Selected Thermodynamic Issues

by Piotr Kolasiński^*, Michał Pomorski, Przemysław Błasiak and Józef Rak

Department of Thermodynamics, Theory of Machines and Thermal Systems, Faculty of Mechanical and Power Engineering, Wrocław University of Science and Technology, Wrocław 50-370, Poland

Appl. Sci. 2017, 7(6), 535; https://doi.org/10.3390/app7060535 - 23 May 2017

Cited by 16 | Viewed by 6459

Abstract

Gas pressure reduction stations are commonly applied to decrease the pressure of natural gas in the transmission pipelines. In such stations, natural gas is expanded in throttling valves without producing any energy. Through the use of expander in natural gas pressure reduction stations, [...] Read more.

Gas pressure reduction stations are commonly applied to decrease the pressure of natural gas in the transmission pipelines. In such stations, natural gas is expanded in throttling valves without producing any energy. Through the use of expander in natural gas pressure reduction stations, it is possible to recover the pressure energy of the natural gas during expansion, and drive the electrical generator. Possible solutions include turbines and volumetric expanders. However, turbines are complicated and expensive, while volumetric expanders are simple and cheap. This paper presents an analytical modeling of rolling piston expander work conditions when adopted to natural gas expansion. The main objective of this research was therefore a comprehensive analysis of influence of varied sizes of the expander components and natural gas thermal properties at the inlet and at the outlet of the expander, on the expander output power. The analysis presented in this paper indicates that the rolling piston expander is a good alternative to the turbines proposed for energy recovery in natural gas pressure reduction stations. Full article

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

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18 pages, 3978 KiB

Open AccessArticle

Microtab Design and Implementation on a 5 MW Wind Turbine

by Unai Fernandez-Gamiz^1,*

, Ekaitz Zulueta², Ana Boyano³, Josean A. Ramos-Hernanz⁴ and Jose Manuel Lopez-Guede²

¹ Department of Nuclear and Fluid Mechanics, University of the Basque Country (UPV/EHU) Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain

² System Engineering & Automation Control Department, University of the Basque Country (UPV/EHU) Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain

³ Department of Mechanical Engineering, University of the Basque Country (UPV/EHU) Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain

⁴ Electrical Engineering Department, University of the Basque Country (UPV/EHU) Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain

Appl. Sci. 2017, 7(6), 536; https://doi.org/10.3390/app7060536 - 24 May 2017

Cited by 32 | Viewed by 12340

Abstract

Microtabs (MT) consist of a small tab placed on the airfoil surface close to the trailing edge and perpendicular to the surface. A study to find the optimal position to improve airfoil aerodynamic performance is presented. Therefore, a parametric study of a MT [...] Read more.

Microtabs (MT) consist of a small tab placed on the airfoil surface close to the trailing edge and perpendicular to the surface. A study to find the optimal position to improve airfoil aerodynamic performance is presented. Therefore, a parametric study of a MT mounted on the pressure surface of an airfoil has been carried out. The aim of the current study is to find the optimal MT size and location to increase airfoil aerodynamic performance and to investigate its influence on the power output of a 5 MW wind turbine. Firstly, a computational study of a MT mounted on the pressure surface of the airfoil DU91W(2)250 has been carried out and the best case has been found according to the largest lift-to-drag ratio. This airfoil has been selected because it is typically used on wind turbine, such as the 5 MW reference wind turbine of the National Renewable Energy Laboratory (NREL). Second, Blade Element Momentum (BEM) based computations have been performed to investigate the effect of the MT on the wind turbine power output with different wind speed realizations. The results show that, due to the implementation of MTs, a considerable increase in the turbine average power is achieved. Full article

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8 pages, 2518 KiB

Open AccessArticle

Path Loss Measurements of Indoor LTE System for the Internet of Things

by Guan-Yi Liu¹, Tsung-Yu Chang¹, Yung-Chun Chiang¹, Po-Chiang Lin^1,2,*

and Jeich Mar^1,2

¹ Department of Communications Engineering, Yuan Ze University, 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan

² Communications Research Center, Yuan Ze University, 135 Yuan-Tung Road, Chungli, Taoyuan 320, Taiwan

Appl. Sci. 2017, 7(6), 537; https://doi.org/10.3390/app7060537 - 23 May 2017

Cited by 15 | Viewed by 6500

Abstract

The Internet of Things (IoT) provides communication service for future smart manufacturing, which is capable of independently exchanging and responding to information to manage industrial production processes. For the purpose of connecting machines, devices, sensors, and people with each other in a factory, [...] Read more.

The Internet of Things (IoT) provides communication service for future smart manufacturing, which is capable of independently exchanging and responding to information to manage industrial production processes. For the purpose of connecting machines, devices, sensors, and people with each other in a factory, reliable and scalable communication networks used in the cellular IoT are of great importance. This paper aims at channel parameter measurements of indoor Long Term Evolution systems in order to achieve good coverage and service reliability (SR) for the IoT. For the purpose of determining the path loss exponent and the standard deviation of the received shadow fading signal, we use software defined radio techniques to build a small cell experimental platform which contains an evolved node B and user equipment. Received power measurements were performed on this platform. Finally, based on the experimental results, the modified path loss model and the calculated fade margin (FM) for 90% SR are exploited to predict the coverage range of the small cell base station deployed in the factory. The measured path loss channel models are compared with International Telecommunication Union (ITU) path loss channel model. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Advanced Manufacturing (ICAM 2016))

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13 pages, 3311 KiB

Open AccessArticle

Investigation on Eddy Current Sensor in Tension Measurement at a Resonant Frequency

by Chengzhu Xiu¹, Liang Ren^1,*

and Hongnan Li^1,2,*

¹ Faculty of Infrastructure Engineering, State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116023, China

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

Appl. Sci. 2017, 7(6), 538; https://doi.org/10.3390/app7060538 - 24 May 2017

Cited by 15 | Viewed by 6154

Abstract

For resolving deficiencies of conventional tension measurement methods, this paper proposes a novel eddy current sensor with a single-coil structure based on the inverse magnetostrictive effect. An inductor–resistor–capacitor (LRC) model of eddy current sensor, which considers more parameters than the traditional inductor–resistor (LR) [...] Read more.

For resolving deficiencies of conventional tension measurement methods, this paper proposes a novel eddy current sensor with a single-coil structure based on the inverse magnetostrictive effect. An inductor–resistor–capacitor (LRC) model of eddy current sensor, which considers more parameters than the traditional inductor–resistor (LR) model, was established. The eddy current sensor was operated by a swept frequency signal that ranged from 0.1 MHz to 1.6 MHz, encompassing the sensor resonant frequency. At the resonant frequency, the data of impedance magnitude and phase were extracted and linear relations between the impedance parameters and the external tension were ascertained. The experimental results show that the resonant frequency and impedance magnitude of eddy current sensor will decrease linearly with the increase of the external tension, which is consistent with the theoretical model. In addition, to improve sensor performance, the sleeve structure was designed to reduce the loss of magnetic field. Both finite element simulations and experimental results demonstrate that the sleeve structure provides a higher permeability path to the magnetic field lines than the non-sleeve structure and effectively improves sensor sensitivity and correlation coefficient. Full article

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16 pages, 4203 KiB

Open AccessArticle

Coordination of EVs Participation for Load Frequency Control in Isolated Microgrids

by Mostafa Vahedipour-Dahraie¹, Homa Rashidizaheh-Kermani¹, Hamid Reza Najafi^1,*, Amjad Anvari-Moghaddam²

and Josep M. Guerrero²

¹ Department of Electrical & Computer Engineering, University of Birjand, Birjand 9856, Iran

² Department of Energy Technology, Aalborg University, 9220 Aalborg East, Denmark

Appl. Sci. 2017, 7(6), 539; https://doi.org/10.3390/app7060539 - 24 May 2017

Cited by 47 | Viewed by 6144

Abstract

Increasing the penetration levels of renewable energy sources (RESs) in microgrids (MGs) may lead to frequency instability issues due to intermittent nature of RESs and low inertia of MG generating units. On the other hand, presence of electric vehicles (EVs), as new high-electricity- [...] Read more.

Increasing the penetration levels of renewable energy sources (RESs) in microgrids (MGs) may lead to frequency instability issues due to intermittent nature of RESs and low inertia of MG generating units. On the other hand, presence of electric vehicles (EVs), as new high-electricity- consuming appliances, can be a good opportunity to contribute in mitigating the frequency deviations and help the system stability. This paper proposes an optimal charging/discharging scheduling of EVs with the goal of improving frequency stability of MG during autonomous operating condition. To this end, an efficient approach is applied to reschedule the generating units considering the EVs owners’ behaviors. An EV power controller (EVPC) is also designed to determine charge and discharge process of EVs based on the forecasted day-ahead load and renewable generation profiles. The performance of the proposed strategy is tested in different operating scenarios and compared to those from non-optimized methodologies. Numerical simulations indicate that the MG performance improves considerably in terms of economy and stability using the proposed strategy. Full article

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

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12 pages, 6754 KiB

Open AccessArticle

Application of FBG Based Sensor in Pipeline Safety Monitoring

by Tao Jiang¹, Liang Ren^1,*

, Ziguang Jia²

, Dongsheng Li¹ and Hongnan Li^1,3

¹ School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China

² School of Ocean Science and Technology, Dalian University of Technology, Panjin 124221, China

³ School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

Appl. Sci. 2017, 7(6), 540; https://doi.org/10.3390/app7060540 - 24 May 2017

Cited by 61 | Viewed by 7783

Abstract

Pipeline leakage and corrosion are two serious threats to pipeline safety operation. Therefore, to ensure the safety operation of long-distance pipeline, it is of great significance to conduct pipeline monitoring. Since hoop strain is an effective indicator to reflect the inner pressure fluctuation [...] Read more.

Pipeline leakage and corrosion are two serious threats to pipeline safety operation. Therefore, to ensure the safety operation of long-distance pipeline, it is of great significance to conduct pipeline monitoring. Since hoop strain is an effective indicator to reflect the inner pressure fluctuation and the wall thickness reduction of the pipeline, a method of monitoring leakage and corrosion simultaneously was proposed based on hoop strain measurement. In order to test the hoop strain variation, this paper introduces a fiber Bragg grating (FBG) strain hoop sensor. To verify the monitoring method and the performance of this FBG strain sensor, a pipeline leakage simulation experiment and corrosion simulation experiment were conducted on an actual pipeline and a polyvinyl chloride (PVC) pipe model, respectively. The experimental results demonstrate that the pipeline leakage and corrosion can be detected by the FBG hoop strain sensor. The FBG strain hoop sensor is a promising device in pipeline safety monitoring. Full article

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19 pages, 3053 KiB

Open AccessArticle

Stereophonic Microphone Array for the Recording of the Direct Sound Field in a Reverberant Environment

by Jonathan Albert Gößwein^*, Julian Grosse and Steven Van de Par

Acoustics Group, Cluster of Excellence “Hearing4All”, Carl von Ossietzky University, 26111 Oldenburg, Germany

Appl. Sci. 2017, 7(6), 541; https://doi.org/10.3390/app7060541 - 24 May 2017

Cited by 1 | Viewed by 5952

Abstract

State-of-the-art stereo recording techniques using two microphones have two main disadvantages: first, a limited reduction of the reverberation in the direct sound component, and second, compression or expansion of the angular position of sound sources. To address these disadvantages, the aim of this [...] Read more.

State-of-the-art stereo recording techniques using two microphones have two main disadvantages: first, a limited reduction of the reverberation in the direct sound component, and second, compression or expansion of the angular position of sound sources. To address these disadvantages, the aim of this study is the development of a true stereo recording microphone array that aims to record the direct and reverberant sound field separately. This array can be used within the recording and playback configuration developed in Grosse and van de Par, 2015. Instead of using only two microphones, the proposed method combines two logarithmically-spaced microphone arrays, whose directivity patterns are optimized with a superdirective beamforming algorithm. The optimization allows us to have a better control of the overall beam pattern and of interchannel level differences. A comparison between the newly-proposed system and existing microphone techniques shows a lower percentage of the recorded reverberance within the sound field. Full article

(This article belongs to the Special Issue Spatial Audio)

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9 pages, 1088 KiB

Open AccessArticle

Near-Field Coupling and Mode Competition in Multiple Anapole Systems

by Valerio Mazzone, Juan Sebastian Totero Gongora

and Andrea Fratalocchi^*

PRIMALIGHT, Faculty of Electrical Engineering, Applied Mathematics and Computational Science, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia

Appl. Sci. 2017, 7(6), 542; https://doi.org/10.3390/app7060542 - 24 May 2017

Cited by 28 | Viewed by 7722

Abstract

All-dielectric metamaterials are a promising platform for the development of integrated photonics applications. In this work, we investigate the mutual coupling and interaction of an ensemble of anapole states in silicon nanoparticles. Anapoles are intriguing non-radiating states originated by the superposition of internal [...] Read more.

All-dielectric metamaterials are a promising platform for the development of integrated photonics applications. In this work, we investigate the mutual coupling and interaction of an ensemble of anapole states in silicon nanoparticles. Anapoles are intriguing non-radiating states originated by the superposition of internal multipole components which cancel each other in the far-field. While the properties of anapole states in single nanoparticles have been extensively studied, the mutual interaction and coupling of several anapole states have not been characterized. By combining first-principles simulations and analytical results, we demonstrate the transferring of anapole states across an ensemble of nanoparticles, opening to the development of advanced integrated devices and robust waveguides relying on non-radiating modes. Full article

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

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13 pages, 2121 KiB

Open AccessArticle

DegoViz: An Interactive Visualization Tool for a Differentially Expressed Genes Heatmap and Gene Ontology Graph

by Somyung Oh¹, Junghyeon Ha², Kyungwon Lee² and Sejong Oh^3,*

¹ Department of Visualization, Texas A&M University, College Station, TX 77843, USA

² Department of Digital Media, Ajou University, Suwon 16499, Korea

³ Department of Software Science, Dankook University, Yongin 16890, Korea

Appl. Sci. 2017, 7(6), 543; https://doi.org/10.3390/app7060543 - 25 May 2017

Cited by 4 | Viewed by 8559

Abstract

Microarray is a general scheme to identify differentially expressed genes for a target concept and can be used for biology. The output is presented utilizing a heatmap that biologists analyze in related terms of gene ontology to determine the characteristics of differentially expressed [...] Read more.

Microarray is a general scheme to identify differentially expressed genes for a target concept and can be used for biology. The output is presented utilizing a heatmap that biologists analyze in related terms of gene ontology to determine the characteristics of differentially expressed genes. In this paper, we propose an integrated visualization tool for a heatmap and gene ontology graph. Most of the previous methods used were static and none of them were combined. The proposed visualization tool integrates these and provides users with an interactive management ability. Users can easily identify and confirm related terms of gene ontology for given differentially expressed genes. Further, the proposed tool visualizes the connections between genes on the heatmap and gene ontology graph. Therefore, the proposed tool can be used for precision healthcare. Full article

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12 pages, 3108 KiB

Open AccessArticle

Split-And-Delay Unit for FEL Interferometry in the XUV Spectral Range

by Sergey Usenko^1,2, Andreas Przystawik¹, Leslie Lamberto Lazzarino³, Markus Alexander Jakob^2,3, Florian Jacobs³, Christoph Becker³, Christian Haunhorst⁴, Detlef Kip⁴ and Tim Laarmann^1,2,*

¹ Photon Science Division, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany

² The Hamburg Centre for Ultrafast Imaging CUI, 22761 Hamburg, Germany

³ Department of Physics, University of Hamburg, 22761 Hamburg, Germany

⁴ Faculty of Electrical Engineering, Helmut Schmidt University, 22043 Hamburg, Germany

Appl. Sci. 2017, 7(6), 544; https://doi.org/10.3390/app7060544 - 25 May 2017

Cited by 10 | Viewed by 6575

Abstract

In this work we present a reflective split-and-delay unit (SDU) developed for interferometric time-resolved experiments utilizing an (extreme ultraviolet) XUV pump–XUV probe scheme with focused free-electron laser beams. The developed SDU overcomes limitations for phase-resolved measurements inherent to conventional two-element split mirrors by [...] Read more.

In this work we present a reflective split-and-delay unit (SDU) developed for interferometric time-resolved experiments utilizing an (extreme ultraviolet) XUV pump–XUV probe scheme with focused free-electron laser beams. The developed SDU overcomes limitations for phase-resolved measurements inherent to conventional two-element split mirrors by a special design using two reflective lamellar gratings. The gratings produce a high-contrast interference signal controlled by the grating displacement in every diffraction order. The orders are separated in the focal plane of the focusing optics, which enables one to avoid phase averaging by spatially selective detection of a single interference state of the two light fields. Interferometry requires a precise relative phase control of the light fields, which presents a challenge at short wavelengths. In our setup the phase delay is determined by an in-vacuum white light interferometer (WLI) that monitors the surface profile of the SDU in real time and thus measures the delay for each laser shot. The precision of the WLI is 1 nm as determined by optical laser interferometry. In the presented experimental geometry it corresponds to a time delay accuracy of 3 as, which enables phase-resolved XUV pump–XUV probe experiments at free-electron laser (FEL) repetition rates up to 60 Hz. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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12 pages, 2898 KiB

Open AccessArticle

Effects of Three Different Additives and Two Different Bulk Densities on Maize Silage Characteristics, Temperature Profiles, CO₂ and O₂–Dynamics in Small Scale Silos during Aerobic Exposure

by Kerstin Helena Jungbluth^1,*, Manfred Trimborn¹

, Gerd-Christian Maack¹, Wolfgang Büscher¹

, Menghua Li², Hong Cheng², Qiang Cheng² and Yurui Sun²

¹ Institute of Agricultural Engineering, Bonn University, Bonn 53115, Germany

² College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China

Appl. Sci. 2017, 7(6), 545; https://doi.org/10.3390/app7060545 - 25 May 2017

Cited by 16 | Viewed by 5257

Abstract

Silage quality and aerobic stability are sometimes insufficient. If management requirements are not met, or to improve silage quality, additives are often used. The objective of this study is to investigate the effects of different factors on silage during aerobic conditions. Whole-crop forage [...] Read more.

Silage quality and aerobic stability are sometimes insufficient. If management requirements are not met, or to improve silage quality, additives are often used. The objective of this study is to investigate the effects of different factors on silage during aerobic conditions. Whole-crop forage maize was harvested and 24 buckets (65 L) were filled and assigned to one of four treatment groups: (1) control (no treatment); (2) chemical additive (sodium benzoate, potassium sorbate, sodium acetate); (3) a mixed biological inoculant containing Lactobacillus buchneri, L. plantarum, and Pediococcus acidilacti; and (4) a mixed biological inoculant containing L. buchneri, L. plantarum, and L. rhamnosus. An untreated variation was also ensiled. Two different densities were adjusted during ensiling. After opening, the temperature was measured for seven days and O₂ and CO₂ concentrations were analysed. The findings show that the chemical additive very effectively prevented silage from reheating and deteriorating. Aerobic reheating of silage was also successfully inhibited through biological additives and high density. Full article

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

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16 pages, 5374 KiB

Open AccessArticle

Control of the Polymorphism of Calcium Carbonate Produced by Self-Healing in the Cracked Part of Cementitious Materials

by Heesup Choi¹

, Hyeonggil Choi^2,*, Masumi Inoue¹ and Risa Sengoku¹

¹ Department of Civil and Environmental Engineering, Kitami Institute of Technology, Hokkaido 090-8507, Japan

² Faculty of Environmental Technology, Muroran Institute of Technology, Hokkaido 090-8585, Japan

Appl. Sci. 2017, 7(6), 546; https://doi.org/10.3390/app7060546 - 25 May 2017

Cited by 30 | Viewed by 5935

Abstract

Cracking is an inherent development in reinforced concrete structures and can lead to serious damages during their service period. The repeated occurrence of such damages can enlarge the cracks, thereby allowing other deteriorating elements such as CO₂ and Cl⁻ to further [...] Read more.

Cracking is an inherent development in reinforced concrete structures and can lead to serious damages during their service period. The repeated occurrence of such damages can enlarge the cracks, thereby allowing other deteriorating elements such as CO₂ and Cl⁻ to further infiltrate the concrete, which can seriously compromise the concrete structure. This study focuses on the type of calcium carbonate (CaCO₃) crystals generated by the self-healing phenomenon. Owing to polymorphism, CaCO₃ has three types of crystal forms—calcite, vaterite, and aragonite—whose formation can be controlled by the temperature and pH. Vaterite has the highest density among these crystals, and it is expected to be capable of self-healing. Therefore, experiments were conducted to establish the conditions required to promote the generation of vaterite. A saturated Ca(OH)₂ solution with CO₂ nanobubbles (CN) was employed for effective self-healing. The temperature was controlled at 20, 40, and 60 °C, and the pH was controlled at 9.0, 10.5, and 12.0. The results showed that the self-healing of cracks occurred both on the surface and internally, and the main product of the self-healing phenomenon was vaterite in CaCO₃ crystals at a pH of 9.0 and a temperature of 40 °C. Furthermore, the addition of a saturated Ca(OH)₂ solution with CO₂ nanobubbles (CN) resulted in the most effective self-healing of the surface and internal cracks. Full article

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16 pages, 2929 KiB

Open AccessArticle

Modular and Offsite Construction of Piping: Current Barriers and Route

by Xiaodan Li¹, Zhongfu Li¹ and Guangdong Wu^2,*

¹ Department of Construction Management, Dalian University of Technology, Dalian 116024, China

² Department of Tourism and Urban Management, Jiangxi University of Finance & Economics, Nanchang 330013, China

Appl. Sci. 2017, 7(6), 547; https://doi.org/10.3390/app7060547 - 26 May 2017

Cited by 25 | Viewed by 10401

Abstract

To investigate current practices and identify challenges of piping prefabrication, this paper conducts a comprehensive survey to mechanical, electrical, and plumbing (MEP) contractors. This paper is performed in three main steps. First, the current state of piping prefabrication, the attitude of MEP contractors [...] Read more.

To investigate current practices and identify challenges of piping prefabrication, this paper conducts a comprehensive survey to mechanical, electrical, and plumbing (MEP) contractors. This paper is performed in three main steps. First, the current state of piping prefabrication, the attitude of MEP contractors to piping prefabrication, and the challenges of piping prefabrication are identified through a comprehensive data collection process that included semi-structured interviews, case studies, site visits, and questionnaires. The second step included suggesting a pattern and roadway of piping prefabrication. The results showed that: (1) The attitudes to feasibility of piping prefabrication differ in piping systems, piping connector modes, and types of project; and (2) building information modelling (BIM) promotes the adoption of piping prefabrication. Integrated project delivery (IPD), and distributor’s early involvement into projects have significant effects on the successful implementation of piping prefabrication. (3) The main barriers and challenges were identified including the low level of standardization of design, lack of preferential policy, economies of scale, low-skilled workers, as well as the availability of fittings and valves. In the final step, a four-phase route of piping prefabrication is suggested for MEP contractors to expand the prefabrication capacity incrementally. The main contributions of this paper include: (1) This paper proposes a route for MEP contractors to improve their piping construction through the Modular and offsite construction (MOC) method. (2) This paper finds that the level of feasibility of piping prefabrication differs in piping systems, connection modes, and types of project. Challenges and barriers of piping prefabrication are firstly identified. Full article

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

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13 pages, 2906 KiB

Open AccessFeature PaperArticle

Bioimaging Using Full Field and Contact EUV and SXR Microscopes with Nanometer Spatial Resolution

by Przemysław Wachulak^1,*, Alfio Torrisi¹

, Mesfin Ayele¹, Joanna Czwartos¹, Andrzej Bartnik¹, Łukasz Węgrzyński¹, Tomasz Fok¹, Tomáš Parkman², Šárka Salačová², Jana Turňová², Michal Odstrčil³ and Henryk Fiedorowicz¹

¹ Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw, Poland

² Faculty of Biomedical Engineering, Czech Technical University in Prague, 272 01 Kladno, Czech Republic

³ Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

Appl. Sci. 2017, 7(6), 548; https://doi.org/10.3390/app7060548 - 26 May 2017

Cited by 18 | Viewed by 5925

Abstract

We present our recent results, related to nanoscale imaging in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges and demonstrate three novel imaging systems recently developed for the purpose of obtaining high spatial resolution images of nanoscale objects with the EUV [...] Read more.

We present our recent results, related to nanoscale imaging in the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges and demonstrate three novel imaging systems recently developed for the purpose of obtaining high spatial resolution images of nanoscale objects with the EUV and SXR radiations. All the systems are based on laser-plasma EUV and SXR sources, employing a double stream gas puff target. The EUV and SXR full field microscopes—operating at 13.8 nm and 2.88 nm wavelengths, respectively—are currently capable of imaging nanostructures with a sub-50 nm spatial resolution with relatively short (seconds) exposure times. The third system is a SXR contact microscope, operating in the “water-window” spectral range (2.3–4.4 nm wavelength), to produce an imprint of the internal structure of the investigated object in a thin surface layer of SXR light sensitive poly(methyl methacrylate) photoresist. The development of such compact imaging systems is essential to the new research related to biological science, material science, and nanotechnology applications in the near future. Applications of all the microscopes for studies of biological samples including carcinoma cells, diatoms, and neurons are presented. Details about the sources, the microscopes, as well as the imaging results for various objects will be shown and discussed. Full article

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

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16 pages, 3582 KiB

Open AccessArticle

Effect of Load Transfer Section to Toughness for Steel Fiber-Reinforced Concrete

by Yoon-Jung Han, Sang-Keun Oh

and Byoungil Kim^*

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

Appl. Sci. 2017, 7(6), 549; https://doi.org/10.3390/app7060549 - 26 May 2017

Cited by 10 | Viewed by 4548

Abstract

This study analyzed the correlation between the load transfer properties and the overall toughness in the flexural behavior of steel fiber-reinforced concrete after concrete matrix cracking. Beam specimens with identical aspect ratios were made with three different types of steel fiber, each of [...] Read more.

This study analyzed the correlation between the load transfer properties and the overall toughness in the flexural behavior of steel fiber-reinforced concrete after concrete matrix cracking. Beam specimens with identical aspect ratios were made with three different types of steel fiber, each of which had different properties, and were used for the flexural test. The load displacement graph from the test was divided into sections by behavioral properties, and the regression model by mix was analyzed to extract the correlation between the load transfer section (concrete-fiber) and the overall toughness. The analysis results showed three types of load displacement curve based on the fiber type and fiber content, and confirmed that the load reduction section towards fiber after concrete cracking and the slope and area of the load reascension section had a huge impact on the overall toughness. The regression model of the whole toughness (T_b) was then acquired by proposing the resulting correlation as the load transfer factor (LTF). Full article

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

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19 pages, 19354 KiB

Open AccessArticle

Pore Characteristics and Their Effects on the Material Properties of Foamed Concrete Evaluated Using Micro-CT Images and Numerical Approaches

by Sang-Yeop Chung^1,*

, Christian Lehmann¹, Mohamed Abd Elrahman^1,2 and Dietmar Stephan¹

¹ Building Materials and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany

² Structural Engineering Department, Mansoura University, Elgomhouria St., Mansoura City 35516, Egypt

Appl. Sci. 2017, 7(6), 550; https://doi.org/10.3390/app7060550 - 26 May 2017

Cited by 93 | Viewed by 11657

Abstract

Foamed concrete contains numerous pores inside the material, and these pores are a significant factor determining the material characteristics. In particular, the pore distribution characteristics of foamed concrete significantly affect its thermal and mechanical properties. Therefore, an appropriate investigation is necessary for a [...] Read more.

Foamed concrete contains numerous pores inside the material, and these pores are a significant factor determining the material characteristics. In particular, the pore distribution characteristics of foamed concrete significantly affect its thermal and mechanical properties. Therefore, an appropriate investigation is necessary for a more detailed understanding of foamed concrete. Here, a set of foamed concrete samples with different densities is used in order to investigate the density effects on the pore characteristics, as well as the physical properties of the materials. The pore distribution characteristics of these samples are investigated using an X-ray micro-computed tomography (micro-CT) imaging technique with probabilistic and quantitative methods. Using these methods, the anisotropy, the pore circularity factor and the relative density of cell thickness are examined. The thermal (thermal conductivity) and mechanical (directional modulus and strength) properties of each foamed specimen are computed using numerical simulations and compared with experimental results. From the obtained results, the effects of the pore sizes and shapes on the local and global properties of the foamed concrete are examined for developing advanced foamed concrete with lower thermal conductivity by minimizing the strength reduction. Full article

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

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15 pages, 2728 KiB

Open AccessArticle

The Aerodynamic Analysis of a Rotating Wind Turbine by Viscous-Coupled 3D Panel Method

by Bryan Nelson^1,2,*

and Jen-Shiang Kouh¹

¹ Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 106, Taiwan

² Research Department, CR Classification Society, 8th Fl., No. 103, Sec. 3, Nanking E. Rd., Taipei 104, Taiwan

Appl. Sci. 2017, 7(6), 551; https://doi.org/10.3390/app7060551 - 26 May 2017

Cited by 5 | Viewed by 5761

Abstract

In addition to the many typical failure mechanisms that afflict wind turbines, units in Taiwan are also susceptible to catastrophic failure from typhoon-induced extreme loads. A key component of the strategy to prevent such failures is a fast, accurate aerodynamic analysis tool through [...] Read more.

In addition to the many typical failure mechanisms that afflict wind turbines, units in Taiwan are also susceptible to catastrophic failure from typhoon-induced extreme loads. A key component of the strategy to prevent such failures is a fast, accurate aerodynamic analysis tool through which a fuller understanding of aerodynamic loads acting on the units may be derived. To this end, a viscous-coupled 3D panel method is herewith proposed, which introduces a novel approach to simulating the severe flow separation so prevalent around wind turbine rotors. The validity of the current method’s results was assessed by code-to-code comparison with RANS data for a commercial 2 MW wind turbine rotor. Along the outboard and inboard regions of the rotor, pressure distributions predicted by the current method showed excellent agreement with the RANS data, while pressure data along the midspan region were slightly more conservative. The power curve predicted by the current method was also more conservative than that predicted by the RANS solver, but correlated very well with that provided by the turbine manufacturer. Taking into account the high degree of comparability with the more sophisticated RANS solver, the excellent agreement with the official data, and the considerably reduced computational expense, the author believes the proposed method could be a powerful standalone tool for the design and analysis of wind turbine blades, or could be applied to the emerging field of wind farm layout design by providing accurate body force input to actuator line rotors within full Navier-Stokes models of multi-unit wind farms. Full article

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

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14 pages, 3319 KiB

Open AccessArticle

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

by Cosmin Sinescu^1,†

, Adrian Bradu^2,†

, Virgil-Florin Duma^3,4,*,†

, Florin Topala¹, Meda Negrutiu¹

and Adrian Gh. Podoleanu²

¹ School of Dental Medicine, Victor Babes University of Medicine and Pharmacy of Timisoara, 2A Eftimie Murgu Place, Timisoara 300070, Romania

² Applied Optics Group, School of Physical Sciences, University of Kent, Canterbury CT2 7NH, UK

³ 3OM Optomechatronics Group, Faculty of Engineering, Aurel Vlaicu University of Arad, 77 Revolutiei Ave., Arad 310130, Romania

⁴ Doctoral School, Polytechnic University of Timisoara, 1 Mihai Viteazu Ave., Timisoara 300222, Romania

^† These authors had equal contributions.

Appl. Sci. 2017, 7(6), 552; https://doi.org/10.3390/app7060552 - 26 May 2017

Cited by 19 | Viewed by 5289

Abstract

Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based [...] Read more.

Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based on firing supplemental control samples are subjective, time-consuming, and rely entirely on the technician’s skills. The aim of this study was to propose an alternative procedure for such evaluations. Fifty prostheses were sintered in a ceramic oven at a temperature lower, equal to or larger than the temperature prescribed by the manufacturer. A non-destructive imaging method, swept source (SS) optical coherence tomography (OCT) was used to evaluate comparatively the internal structure of prostheses so fabricated. A quantitative assessment procedure is proposed, based on en-face OCT images acquired at similar depths inside the samples. Differences in granulation and reflectivity depending on the oven temperature are used to establish rules-of-thumb on judging the correct calibration of the oven. OCT evaluations made on a regular basis allow an easy and objective monitoring of correct settings in the sintering process. This method can serve rapid identification of the need to recalibrate the oven and avoid producing prostheses with defects. Full article

(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))

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15 pages, 5421 KiB

Open AccessArticle

Modeling of Heat Transfer and Oscillating Flow in the Regenerator of a Pulse Tube Cryocooler Operating at 50 Hz

by Xiufang Liu¹, Chen Chen¹, Qian Huang¹, Shubei Wang², Yu Hou¹ and Liang Chen^1,*

¹ State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² Xi’an Jiaotong University Su Zhou Academy, Suzhou 215123, China

Appl. Sci. 2017, 7(6), 553; https://doi.org/10.3390/app7060553 - 5 Jun 2017

Cited by 7 | Viewed by 6536

Abstract

The regenerator of the pulse tube refrigerator (PTR) operates with oscillating pressure and mass flow, so a proper description of the heat transfer characteristics of the oscillating flow in the regenerator is crucial. In this paper, a one-dimensional model based on Lagrangian representation [...] Read more.

The regenerator of the pulse tube refrigerator (PTR) operates with oscillating pressure and mass flow, so a proper description of the heat transfer characteristics of the oscillating flow in the regenerator is crucial. In this paper, a one-dimensional model based on Lagrangian representation is developed to simulate the oscillating flow in the regenerator of the PTR. The continuity equation, momentum equation and energy equation are solved iteratively using the SIMPLER algorithm. The Darcy-Brinkman-Forchheimer model is used in the momentum equation, and a thermal non-equilibrium model is implemented in the energy equation. Lagrangian representation is employed to describe the thermodynamics of fluid parcels while the Eulerian representation (control volume method) is adopted for the energy equation of the solid matrix. The boundary conditions are set as the periodic flow of the sine function. The thermodynamic parameters of the gas parcels are obtained, which reveal the critical processes of the heat transfer in the regenerator under oscillating flow. The performance of the regenerator with different geometries is evaluated based on the numerical results. The present study provides insight for better understanding the physical process in the regenerator of the PTR, and the proposed model serves as a useful tool for the design and optimization of the cryogenic regenerator. Full article

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

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20 pages, 3364 KiB

Open AccessArticle

Optimal Design of an Air-to-Air Heat Exchanger with Cross-Corrugated Triangular Ducts by Using a Particle Swarm Optimization Algorithm

by Caihang Liang^1,*

, Xiaoman Tong¹, Tengyue Lei¹, Zhenxing Li² and Guoshan Wu³

¹ School of Mechano-Electronic Engineering, Guilin University of Electronic Technology, Guilin 541004, China

² Department of Environmental Engineering, Shan Xi University, Taiyuan 030006, China

³ Department of Energy and Built Environment, Guilin University of Aerospace Technology, Guilin 541004, China

Appl. Sci. 2017, 7(6), 554; https://doi.org/10.3390/app7060554 - 26 May 2017

Cited by 26 | Viewed by 7877

Abstract

Air-to-air heat exchangers with cross-corrugated triangular ducts are widely used in various industrial fields to recover waste heat. The geometric parameters of the heat exchangers greatly affect the performance and total annual cost of these systems. In this study, the effectiveness-number of transfer [...] Read more.

Air-to-air heat exchangers with cross-corrugated triangular ducts are widely used in various industrial fields to recover waste heat. The geometric parameters of the heat exchangers greatly affect the performance and total annual cost of these systems. In this study, the effectiveness-number of transfer units (ε-NTU) method was utilized to develop the thermal mathematical model, which was verified by comparing it with previous research. The configuration parameters of the heat exchanger were optimized in this study. The particle swarm optimization (PSO) algorithm was applied using both single and multi-objective algorithm. The colburn factor (j factor), friction factor (f factor), and comprehensive thermal hydraulic performance index (JF factor) were considered as objective functions to be optimized using a single objective and multi-objective algorithm. Then, the entropy generation rate and total annual cost were optimized by using a multi-objective PSO algorithm. In addition, to identify the influential geometric parameters, a global sensitivity analysis was performed. The sensitivity analysis showed that the apex angle θ, channel height H, and heat exchanger height L_h influenced the performance and annual total cost of these systems. Full article

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

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16 pages, 7070 KiB

Open AccessArticle

Construction of Nonblocking Wavelength/Space Switches with AWGs and WSSes

by Bey-Chi Lin^1,* and Chin-Tau Lea²

¹ Department of Applied Math, National University of Tainan, Tainan 70005, Taiwan

² Department of ECE, Hong Kong University of Science of Technology, Hong Kong, China

Appl. Sci. 2017, 7(6), 555; https://doi.org/10.3390/app7060555 - 26 May 2017

Cited by 4 | Viewed by 5767

Abstract

In this paper, we how to use two technologies, AWG (arrayed-waveguide grating) and WSS (wavelength selective switches), to design nonblocking wavelength/space optical cross connects. An AWG is a passive device and can route multiple wavelengths simultaneously. However, to apply AWGs, there are several [...] Read more.

In this paper, we how to use two technologies, AWG (arrayed-waveguide grating) and WSS (wavelength selective switches), to design nonblocking wavelength/space optical cross connects. An AWG is a passive device and can route multiple wavelengths simultaneously. However, to apply AWGs, there are several issues to consider, including the wavelength conversion range, crosstalk, and switch size constraint. We show a decomposition technique for designing an AWG-based nonblocking wavelength/space switch. The decomposition is carried out in a transformed space network. The new technique is simpler in concept and more flexible in setting switch sizes. We also study another class of wavelength/space switches that are based on WSSes and compare the two approaches in terms of the scalability, switch size constraint, and number of WCs (wavelength converters) required. Full article

(This article belongs to the Special Issue Optical Interconnects)

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16 pages, 5367 KiB

Open AccessReview

Ultrafast Optical Signal Processing with Bragg Structures

by Yikun Liu¹, Shenhe Fu², Boris A. Malomed^3,4

, Iam Choon Khoo⁵ and Jianying Zhou^1,*

¹ State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China

² Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China

³ Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel

⁴ Laboratory of Nonlinear-Optical Informatics, ITMO University, St. Petersburg 197101, Russia

⁵ Electrical Engineering Department, Pennsylvania State University, University Park, PA 16802, USA

Appl. Sci. 2017, 7(6), 556; https://doi.org/10.3390/app7060556 - 27 May 2017

Cited by 13 | Viewed by 4669

Abstract

The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various [...] Read more.

The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various optical phenomena in several exemplary 1D Bragg gratings. Important examples are resonantly absorbing photonic structures, chirped Bragg grating, and cholesteric liquid crystals; their unique operation capabilities and key issues are considered in detail. These Bragg structures are expected to be used in wide-spread applications involving light field modulations, especially in the rapidly advancing field of ultrafast optical signal processing. Full article

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

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13 pages, 1834 KiB

Open AccessArticle

Energy-Efficient Caching for Mobile Edge Computing in 5G Networks

by Zhaohui Luo¹, Minghui LiWang¹, Zhijian Lin¹, Lianfen Huang^1,*, Xiaojiang Du² and Mohsen Guizani³

¹ Department of Communications Engineering, Xiamen University, Xiamen 361005, China

² Department of Computer and Information Sciences, Temple University, Philadelphia, PA 19122, USA

³ Department of Electrical and Computer Engineering, University of Idaho, Moscow, ID 83844, USA

Appl. Sci. 2017, 7(6), 557; https://doi.org/10.3390/app7060557 - 27 May 2017

Cited by 41 | Viewed by 9368

Abstract

Mobile Edge Computing (MEC), which is considered a promising and emerging paradigm to provide caching capabilities in proximity to mobile devices in 5G networks, enables fast, popular content delivery of delay-sensitive applications at the backhaul capacity of limited mobile networks. Most existing studies [...] Read more.

Mobile Edge Computing (MEC), which is considered a promising and emerging paradigm to provide caching capabilities in proximity to mobile devices in 5G networks, enables fast, popular content delivery of delay-sensitive applications at the backhaul capacity of limited mobile networks. Most existing studies focus on cache allocation, mechanism design and coding design for caching. However, grid power supply with fixed power uninterruptedly in support of a MEC server (MECS) is costly and even infeasible, especially when the load changes dynamically over time. In this paper, we investigate the energy consumption of the MECS problem in cellular networks. Given the average download latency constraints, we take the MECS’s energy consumption, backhaul capacities and content popularity distributions into account and formulate a joint optimization framework to minimize the energy consumption of the system. As a complicated joint optimization problem, we apply a genetic algorithm to solve it. Simulation results show that the proposed solution can effectively determine the near-optimal caching placement to obtain better performance in terms of energy efficiency gains compared with conventional caching placement strategies. In particular, it is shown that the proposed scheme can significantly reduce the joint cost when backhaul capacity is low. Full article

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

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22 pages, 2652 KiB

Open AccessArticle

Low Frequency Interactive Auralization Based on a Plane Wave Expansion

by Diego Mauricio Murillo Gómez^*,†

, Jeremy Astley and Filippo Maria Fazi

¹ Institute of Sound and Vibration Research, University of Southampton, SO17 1BJ, UK

^† Current address: Faculty of Engineering, Universidad de San Buenaventura Medellín, Cra 56C No 51-110, 050010 Medellín, Colombia.

Appl. Sci. 2017, 7(6), 558; https://doi.org/10.3390/app7060558 - 27 May 2017

Cited by 7 | Viewed by 5330

Abstract

This paper addresses the problem of interactive auralization of enclosures based on a finite superposition of plane waves. For this, room acoustic simulations are performed using the Finite Element (FE) method. From the FE solution, a virtual microphone array is created and an [...] Read more.

This paper addresses the problem of interactive auralization of enclosures based on a finite superposition of plane waves. For this, room acoustic simulations are performed using the Finite Element (FE) method. From the FE solution, a virtual microphone array is created and an inverse method is implemented to estimate the complex amplitudes of the plane waves. The effects of Tikhonov regularization are also considered in the formulation of the inverse problem, which leads to a more efficient solution in terms of the energy used to reconstruct the acoustic field. Based on this sound field representation, translation and rotation operators are derived enabling the listener to move within the enclosure and listen to the changes in the acoustic field. An implementation of an auralization system based on the proposed methodology is presented. The results suggest that the plane wave expansion is a suitable approach to synthesize sound fields. Its advantage lies in the possibility that it offers to implement several sound reproduction techniques for auralization applications. Furthermore, features such as translation and rotation of the acoustic field make it convenient for interactive acoustic renderings. Full article

(This article belongs to the Special Issue Spatial Audio)

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12 pages, 2809 KiB

Open AccessArticle

Rogue Wave Modes for the Coupled Nonlinear Schrödinger System with Three Components: A Computational Study

by Hiu Ning Chan^* and Kwok Wing Chow

Department of Mechanical Engineering, University of Hong Kong, Pokfulam, Hong Kong, China

Appl. Sci. 2017, 7(6), 559; https://doi.org/10.3390/app7060559 - 29 May 2017

Cited by 11 | Viewed by 4989

Abstract

The system of “integrable” coupled nonlinear Schrödinger equations (Manakov system) with three components in the defocusing regime is considered. Rogue wave solutions exist for a restricted range of group velocity mismatch, and the existence condition correlates precisely with the onset of baseband modulation [...] Read more.

The system of “integrable” coupled nonlinear Schrödinger equations (Manakov system) with three components in the defocusing regime is considered. Rogue wave solutions exist for a restricted range of group velocity mismatch, and the existence condition correlates precisely with the onset of baseband modulation instability. This assertion is further elucidated numerically by evidence based on the generation of rogue waves by a single mode disturbance with a small frequency. This same computational approach can be adopted to study coupled nonlinear Schrödinger equations for the “non‐integrable” regime, where the coefficients of self‐phase modulation and cross‐phase modulation are different from each other. Starting with a wavy disturbance of a finite frequency corresponding to the large modulation instability growth rate, a breather can be generated. The breather can be symmetric or asymmetric depending on the magnitude of the growth rate. Under the presence of a third mode, rogue wave can exist under a larger group velocity mismatch between the components as compared to the two‐component system. Furthermore, the nonlinear coupling can enhance the maximum amplitude of the rogue wave modes and bright four‐petal configuration can be observed. Full article

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

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16 pages, 4158 KiB

Open AccessArticle

Evaluation of a Novel Controlled Cutting Fluid Impinging Supply System When Machining Titanium Alloys

by Salah Gariani¹, Islam Shyha^1,*

, Fawad Inam¹ and Dehong Huo²

¹ Department of Mechanical and Construction Engineering, Northumbria University at Newcastle; Newcastle upon Tyne, NE1 8ST, UK

² School of Mechanical and Systems Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK

Appl. Sci. 2017, 7(6), 560; https://doi.org/10.3390/app7060560 - 29 May 2017

Cited by 19 | Viewed by 6379

Abstract

Following a comprehensive review on titanium machining and methods of cutting fluid application, this paper presents a new Controlled cutting fluid impinging supply system (Cut‐list) developed to deliver an accurate amount of cutting fluid into the machining zone via wellpositioned coherent nozzles based [...] Read more.

Following a comprehensive review on titanium machining and methods of cutting fluid application, this paper presents a new Controlled cutting fluid impinging supply system (Cut‐list) developed to deliver an accurate amount of cutting fluid into the machining zone via wellpositioned coherent nozzles based on the calculation of the heat generated. The performance of the new system was evaluated against a conventional flood cutting fluid supply system during step shoulder milling of Ti‐6Al‐4V using vegetable oil‐based cutting fluid. The comparison was performed at different cutting speeds and feed rates. Comparison measures/indicators were cutting force, workpiece temperature, tool flank wear, burr formation and average surface roughness (Ra). The new system provided significant reductions in cutting fluid consumption of up to 42%. Additionally, reductions in cutting force, tool flank wear and burr height of 16.41%, 46.77%, and 31.70% were recorded, respectively. Smaller Ra values were also found with the use of the new system. Full article

(This article belongs to the Section Mechanical Engineering)

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11 pages, 5757 KiB

Open AccessArticle

Waveguiding Light into Silicon Oxycarbide

by Faisal Ahmed Memon^1,2,*, Francesco Morichetti¹

and Andrea Melloni¹

¹ Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, via Ponzio 34/5, 20133 Milan, Italy

² Department of Telecommunications Engineering, Mehran University of Engineering & Technology, Jamshoro 76062, Sindh, Pakistan

Appl. Sci. 2017, 7(6), 561; https://doi.org/10.3390/app7060561 - 30 May 2017

Cited by 13 | Viewed by 6275

Abstract

In this work, we demonstrate the fabrication of single mode optical waveguides in silicon oxycarbide (SiOC) with a high refractive index n = 1.578 on silica (SiO₂), exhibiting an index contrast of Δn = 8.2%. Silicon oxycarbide layers were deposited by [...] Read more.

In this work, we demonstrate the fabrication of single mode optical waveguides in silicon oxycarbide (SiOC) with a high refractive index n = 1.578 on silica (SiO₂), exhibiting an index contrast of Δn = 8.2%. Silicon oxycarbide layers were deposited by reactive RF magnetron sputtering of a SiC target in a controlled process of argon and oxygen gases. The optical properties of SiOC film were measured with spectroscopic ellipsometry in the near-infrared range and the acquired refractive indices of the film exhibit anisotropy on the order of 10⁻². The structure of the SiOC films is investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The channel waveguides in SiOC are buried in SiO₂ (n = 1.444) and defined with UV photolithography and reactive ion etching techniques. Propagation losses of about 4 dB/cm for both TE and TM polarizations at telecommunication wavelength 1550 nm are estimated with cut-back technique. Results indicate the potential of silicon oxycarbide for guided wave applications. Full article

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

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20 pages, 5007 KiB

Open AccessArticle

Damage Assessment Using Information Entropy of Individual Acoustic Emission Waveforms during Cyclic Fatigue Loading

by Christine M. Sauerbrunn^*, Ali Kahirdeh, Huisung Yun and Mohammad Modarres

Center for Risk and Reliability, Department of Mechanical Engineering, University of Maryland, 2181 Glenn L. Martin Hall, 4298 Campus Dr., College Park, MD 20742, USA

Appl. Sci. 2017, 7(6), 562; https://doi.org/10.3390/app7060562 - 30 May 2017

Cited by 35 | Viewed by 5584

Abstract

Information entropy measured from acoustic emission (AE) waveforms is shown to be an indicator of fatigue damage in a high-strength aluminum alloy. Three methods of measuring the AE information entropy, regarded as a direct measure of microstructural disorder, are proposed and compared with [...] Read more.

Information entropy measured from acoustic emission (AE) waveforms is shown to be an indicator of fatigue damage in a high-strength aluminum alloy. Three methods of measuring the AE information entropy, regarded as a direct measure of microstructural disorder, are proposed and compared with traditional damage-related AE features. Several tension–tension fatigue experiments were performed with dogbone samples of aluminum 7075-T6, a commonly used material in aerospace structures. Unlike previous studies in which fatigue damage is measured based on visible crack growth, this work investigated fatigue damage both prior to and after crack initiation through the use of instantaneous elastic modulus degradation. Results show that one of the three entropy measurement methods appears to better assess the damage than the traditional AE features, whereas the other two entropies have unique trends that can differentiate between small and large cracks. Full article

(This article belongs to the Special Issue Advances in Acoustic Emission and Health Monitoring of Materials and Structures)

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16 pages, 3737 KiB

Open AccessArticle

Prediction of Maximum Story Drift of MDOF Structures under Simulated Wind Loads Using Artificial Neural Networks

by Omar Payán-Serrano, Edén Bojórquez^*, Juan Bojórquez, Robespierre Chávez, Alfredo Reyes-Salazar, Manuel Barraza, Arturo López-Barraza, Héctor Rodríguez-Lozoya and Edgar Corona

Facultad de Ingeniería, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa 80040, Mexico

Appl. Sci. 2017, 7(6), 563; https://doi.org/10.3390/app7060563 - 30 May 2017

Cited by 13 | Viewed by 4158

Abstract

The aim of this paper is to investigate the prediction of maximum story drift of Multi-Degree of Freedom (MDOF) structures subjected to dynamics wind load using Artificial Neural Networks (ANNs) through the combination of several structural and turbulent wind parameters. The maximum story [...] Read more.

The aim of this paper is to investigate the prediction of maximum story drift of Multi-Degree of Freedom (MDOF) structures subjected to dynamics wind load using Artificial Neural Networks (ANNs) through the combination of several structural and turbulent wind parameters. The maximum story drift of 1600 MDOF structures under 16 simulated wind conditions are computed with the purpose of generating the data set for the networks training with the Levenberg–Marquardt method. The Shinozuka and Newmark methods are used to simulate the turbulent wind and dynamic response, respectively. In order to optimize the computational time required for the dynamic analyses, an array format based on the Shinozuka method is presented to perform the parallel computing. Finally, it is observed that the already trained ANNs allow for predicting adequately the maximum story drift with a correlation close to 99%. Full article

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26 pages, 2470 KiB

Open AccessFeature PaperArticle

Scheduling of Crude Oil Operations in Refinery without Sufficient Charging Tanks Using Petri Nets

by Yan An, NaiQi Wu^*

, Chi Tin Hon and ZhiWu Li

Macau Institute of Systems Engineering, Macau University of Science and Technology, Macau, China

Appl. Sci. 2017, 7(6), 564; https://doi.org/10.3390/app7060564 - 30 May 2017

Cited by 11 | Viewed by 5945

Abstract

A short-term schedule for crude oil operations in a refinery should define and sequence the activities in detail. Each activity involves both discrete-event and continuous variables. The combinatorial nature of the scheduling problem makes it difficult to solve. For such a scheduling problem, [...] Read more.

A short-term schedule for crude oil operations in a refinery should define and sequence the activities in detail. Each activity involves both discrete-event and continuous variables. The combinatorial nature of the scheduling problem makes it difficult to solve. For such a scheduling problem, charging tanks are a type of critical resources. If the number of charging tanks is not sufficient, the scheduling problem is further complicated. This work conducts a study on the scheduling problem of crude oil operations without sufficient charging tanks. In this case, to make a refinery able to operate, a charging tank has to be in simultaneous charging and feeding to a distiller for some time, called simultaneously-charging-and-feeding (SCF) mode, leading to disturbance to the oil distillation in distillers. A hybrid Petri net model is developed to describe the behavior of the system. Then, a scheduling method is proposed to find a schedule such that the SCF mode is minimally used. It is computationally efficient. An industrial case study is given to demonstrate the obtained results. Full article

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

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14 pages, 2749 KiB

Open AccessArticle

Detection of Eccentricity Faults in Five-Phase Ferrite-PM Assisted Synchronous Reluctance Machines

by Carlos López-Torres¹, Jordi-Roger Riba^1,*

, Antonio Garcia¹

and Luís Romeral²

¹ Electrical Engineering Department, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain

² Electronic Engineering Department, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain

Appl. Sci. 2017, 7(6), 565; https://doi.org/10.3390/app7060565 - 31 May 2017

Cited by 12 | Viewed by 5769

Abstract

Air gap eccentricity faults in five-phase ferrite-assisted synchronous reluctance motors (fPMa-SynRMs) tend to distort the magnetic flux in the air gap, which in turn affects the spectral content of both the stator currents and the ZSVC (zero-sequence voltage component). However, there is a [...] Read more.

Air gap eccentricity faults in five-phase ferrite-assisted synchronous reluctance motors (fPMa-SynRMs) tend to distort the magnetic flux in the air gap, which in turn affects the spectral content of both the stator currents and the ZSVC (zero-sequence voltage component). However, there is a lack of research dealing with the topic of fault diagnosis in multi-phase PMa-SynRMs, and in particular, those focused on detecting eccentricity faults. An analysis of the spectral components of the line currents and the ZSVC allows the development of fault diagnosis algorithms to detect eccentricity faults. The effect of the operating conditions is also analyzed, since this paper shows that it has a non-negligible impact on the effectivity and sensitivity of the diagnosis based on an analysis of the stator currents and the ZSVC. To this end, different operating conditions are analyzed. The paper also evaluates the influence of the operating conditions on the harmonic content of the line currents and the ZSVC, and determines the most suitable operating conditions to enhance the sensitivity of the analyzed methods. Finally, fault indicators employed to detect eccentricity faults, which are based on the spectral content of the stator currents and the ZSVC, are derived and their performance is assessed. The approach presented in this work may be useful for developing fault diagnosis strategies based on the acquisition and subsequent analysis and interpretation of the spectral content of the line currents and the ZSVC. Full article

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

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13 pages, 7422 KiB

Open AccessArticle

Analyzing the Characteristics of Soil Moisture Using GLDAS Data: A Case Study in Eastern China

by Jingze Cai¹, Yuanzhi Zhang^1,2,*, Yu Li^3,*, X. San Liang¹ and Tingchen Jiang⁴

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

² Center for Housing Innovations, Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China

³ Faculty of Information Science, Beijing University of Technology, Beijing 100124, China

⁴ Department of Surveying, Huaihai Institute of Technology, Lianyungang 222005, China

Appl. Sci. 2017, 7(6), 566; https://doi.org/10.3390/app7060566 - 31 May 2017

Cited by 41 | Viewed by 5493

Abstract

In this paper, we use GLDAS (Global Land Data Assimilation System) to analyze the effects of air temperature and precipitation on the characteristics of soil moisture in the eastern region of China from 1961 to 2011. We find that the temperature and precipitation [...] Read more.

In this paper, we use GLDAS (Global Land Data Assimilation System) to analyze the effects of air temperature and precipitation on the characteristics of soil moisture in the eastern region of China from 1961 to 2011. We find that the temperature and precipitation in different seasons have different degrees of influence on the characteristics of soil moisture in each layer. The results show that over the last 50 years, the soil moisture in eastern China has a tendency to dry out, especially between the late 1970s to the early 1980s. The change of soil moisture with the depth of soil layer has similar inter-annual and seasonal patterns. Soil moisture in different depths (0–200 cm) positively correlates with the air temperatures of spring, summer and autumn, but negatively correlates with the air temperature in winter at 0–10 cm, 40–100 cm and 100–200 cm. Similarly, soil moisture is positively related to the precipitation in spring, summer and autumn, and the opposite is true in winter. The results also show that precipitation has a significant effect on the shallow soil moisture (0–10 cm), while air temperature most affects the deep soil moisture (100–200 cm). Full article

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16 pages, 5353 KiB

Open AccessArticle

A New Framework of Human Interaction Recognition Based on Multiple Stage Probability Fusion

by Xiaofei Ji^1,*, Changhui Wang¹ and Zhaojie Ju²

¹ School of Automation, Shenyang Aerospace University, Shenyang 110036, China

² School of Computing, University of Portsmouth, Portsmouth PO1 3HE, UK

Appl. Sci. 2017, 7(6), 567; https://doi.org/10.3390/app7060567 - 1 Jun 2017

Cited by 15 | Viewed by 5191

Abstract

Visual-based human interactive behavior recognition is a challenging research topic in computer vision. There exist some important problems in the current interaction recognition algorithms, such as very complex feature representation and inaccurate feature extraction induced by wrong human body segmentation. In order to [...] Read more.

Visual-based human interactive behavior recognition is a challenging research topic in computer vision. There exist some important problems in the current interaction recognition algorithms, such as very complex feature representation and inaccurate feature extraction induced by wrong human body segmentation. In order to solve these problems, a novel human interaction recognition method based on multiple stage probability fusion is proposed in this paper. According to the human body’s contact in interaction as a cut-off point, the process of the interaction can be divided into three stages: start stage, execution stage and end stage. Two persons’ motions are respectively extracted and recognizes in the start stage and the finish stage when there is no contact between those persons. The two persons’ motion is extracted as a whole and recognized in the execution stage. In the recognition process, the final recognition results are obtained by the weighted fusing these probabilities in different stages. The proposed method not only simplifies the extraction and representation of features, but also avoids the wrong feature extraction caused by occlusion. Experiment results on the UT-interaction dataset demonstrated that the proposed method results in a better performance than other recent interaction recognition methods. Full article

(This article belongs to the Special Issue Human Activity Recognition)

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15 pages, 855 KiB

Open AccessArticle

Measuring the Reflection Matrix of a Rough Surface

by Kenneth Burgi^1,*, Michael Marciniak¹, Mark Oxley² and Stephen Nauyoks¹

¹ Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson AFB, OH 45433, USA

² Department of Mathematics & Statistics, Air Force Institute of Technology, Wright-Patterson AFB, OH 45433, USA

Appl. Sci. 2017, 7(6), 568; https://doi.org/10.3390/app7060568 - 31 May 2017

Cited by 6 | Viewed by 4345

Abstract

Phase modulation methods for imaging around corners with reflectively scattered light required illumination of the occluded scene with a light source either in the scene or with direct line of sight to the scene. The RM (reflection matrix) allows control and refocusing of [...] Read more.

Phase modulation methods for imaging around corners with reflectively scattered light required illumination of the occluded scene with a light source either in the scene or with direct line of sight to the scene. The RM (reflection matrix) allows control and refocusing of light after reflection, which could provide a means of illuminating an occluded scene without access or line of sight. Two optical arrangements, one focal-plane, the other an imaging system, were used to measure the RM of five different rough-surface reflectors. Intensity enhancement values of up to 24 were achieved. Surface roughness, correlation length, and slope were examined for their effect on enhancement. Diffraction-based simulations were used to corroborate experimental results. Full article

(This article belongs to the Section Optics and Lasers)

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18 pages, 20157 KiB

Open AccessArticle

Infrared Small Moving Target Detection via Saliency Histogram and Geometrical Invariability

by Minjie Wan¹, Kan Ren^1,2,*, Guohua Gu¹, Xiaomin Zhang¹, Weixian Qian¹, Qian Chen¹ and Shuai Yu³

¹ School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

² State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China

³ Xi’an Institute of Applied Optics, Xi’an 710065, China

Appl. Sci. 2017, 7(6), 569; https://doi.org/10.3390/app7060569 - 1 Jun 2017

Cited by 36 | Viewed by 5294

Abstract

In order to detect both bright and dark small moving targets effectively in infrared (IR) video sequences, a saliency histogram and geometrical invariability based method is presented in this paper. First, a saliency map that roughly highlights the salient regions of the original [...] Read more.

In order to detect both bright and dark small moving targets effectively in infrared (IR) video sequences, a saliency histogram and geometrical invariability based method is presented in this paper. First, a saliency map that roughly highlights the salient regions of the original image is obtained by tuning its amplitude spectrum in the frequency domain. Then, a saliency histogram is constructed by means of averaging the accumulated saliency value of each gray level in the map, through which bins corresponding to bright target and dark target are assigned with large values in the histogram. Next, single-frame detection of candidate targets is accomplished by a binarized segmentation using an adaptive threshold, and their centroid coordinates with sub-pixel accuracy are calculated through a connected components labeling method as well as a gray-weighted criterion. Finally, considering the motion characteristics in consecutive frames, an inter-frame false alarm suppression method based on geometrical invariability is developed to improve the precision rate further. Quantitative analyses demonstrate the detecting precision of this proposed approach can be up to 97% and Receiver Operating Characteristic (ROC) curves further verify our method outperforms other state-of-the-arts methods in both detection rate and false alarm rate. Full article

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

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23 pages, 3376 KiB

Open AccessArticle

Influence of Road Excitation and Steering Wheel Input on Vehicle System Dynamic Responses

by Zhen-Feng Wang¹

, Ming-Ming Dong¹, Liang Gu¹, Jagat-Jyoti Rath²

, Ye-Chen Qin^1,* and Bin Bai³

¹ School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China

² LAMIH UMR CNRS 8201, University of Valenciennes, 59314 Valenciennes, France

³ College of Mechanical Engineering & Applied Electronics Technology, Beijing University of Technology, Beijing 100024, China

Appl. Sci. 2017, 7(6), 570; https://doi.org/10.3390/app7060570 - 2 Jun 2017

Cited by 47 | Viewed by 9270

Abstract

Considering the importance of increasing driving safety, the study of safety is a popular and critical topic of research in the vehicle industry. Vehicle roll behavior with sudden steering input is a main source of untripped rollover. However, previous research has seldom considered [...] Read more.

Considering the importance of increasing driving safety, the study of safety is a popular and critical topic of research in the vehicle industry. Vehicle roll behavior with sudden steering input is a main source of untripped rollover. However, previous research has seldom considered road excitation and its coupled effect on vehicle lateral response when focusing on lateral and vertical dynamics. To address this issue, a novel method was used to evaluate effects of varying road level and steering wheel input on vehicle roll behavior. Then, a 9 degree of freedom (9-DOF) full-car roll nonlinear model including vertical and lateral dynamics was developed to study vehicle roll dynamics with or without of road excitation. Based on a 6-DOF half-car roll model and 9-DOF full-car nonlinear model, relationship between three-dimensional (3-D) road excitation and various steering wheel inputs on vehicle roll performance was studied. Finally, an E-Class (SUV) level car model in CARSIM^® was used, as a benchmark, with and without road input conditions. Both half-car and full-car models were analyzed under steering wheel inputs of 5°, 10° and 15°. Simulation results showed that the half-car model considering road input was found to have a maximum accuracy of 65%. Whereas, the full-car model had a minimum accuracy of 85%, which was significantly higher compared to the half-car model under the same scenario. Full article

(This article belongs to the Section Mechanical Engineering)

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20 pages, 5963 KiB

Open AccessArticle

Studies on Seismic Performance of Precast Concrete Columns with Grouted Splice Sleeve

by Zheng Lu

, Zixin Wang, Jianbao Li^* and Biao Huang

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

Appl. Sci. 2017, 7(6), 571; https://doi.org/10.3390/app7060571 - 2 Jun 2017

Cited by 45 | Viewed by 10024

Abstract

In order to validate the seismic performance of precast concrete members with steel sleeve connections, pseudo-static tests on four prefabricated columns with vertical grouted splice sleeve connections and on a control group of two cast-in-situ columns have been conducted. The test results indicated [...] Read more.

In order to validate the seismic performance of precast concrete members with steel sleeve connections, pseudo-static tests on four prefabricated columns with vertical grouted splice sleeve connections and on a control group of two cast-in-situ columns have been conducted. The test results indicated that the failure modes of the prefabricated columns and of the cast-in-situ columns are basically identical but differences exist in their crack distribution. The cast-in-situ columns mainly crack horizontally at the bottom of the column, whereas the prefabricated columns have horizontal cracks above the sleeves, and then form diagonal cracks downwards and develop many wider cracks within the range of height of 300 mm at the bottom of the column. The hysteresis curves of the prefabricated columns are plump, which demonstrates that prefabricated columns have satisfactory energy-dissipating capacity. Moreover, the stiffness degradation of the prefabricated specimens is slower than that of the cast-in-situ specimens. The ultimate displacement angle of the prefabricated columns is up to 1/104–1/54, which satisfies the requirements of the inter-story drift ratio during major earthquakes. Finally, some recommendations on practical seismic design pertinent to the precast concrete members with grouted splice sleeves are proposed. Full article

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17 pages, 5269 KiB

Open AccessArticle

The Use of the Surface Roughness Value to Quantify the Extent of Supercritical CO₂ Involved Geochemical Reaction at a CO₂ Sequestration Site

by Jinyoung Park¹

, Kyoungbae Baek², Minhee Lee^2,*, Chul-Woo Chung³ and Sookyun Wang⁴

¹ Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Korea

² Department of Earth Environmental Sciences, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48513, Korea

³ Department of Architectural Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48513, Korea

⁴ Department of Energy Resources Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48513, Korea

Appl. Sci. 2017, 7(6), 572; https://doi.org/10.3390/app7060572 - 2 Jun 2017

Cited by 9 | Viewed by 4613

Abstract

Changes in the physical properties of the supercritical CO₂ (scCO₂) reservoir rock is one of the most important factors in controlling the storage safety at a scCO₂ sequestration site. According to recent studies, it is probable that geochemical reactions [...] Read more.

Changes in the physical properties of the supercritical CO₂ (scCO₂) reservoir rock is one of the most important factors in controlling the storage safety at a scCO₂ sequestration site. According to recent studies, it is probable that geochemical reactions influence changes in the rock properties after a CO₂ injection in the subsurface, but quantitative data that reveal the interrelationship of the factors involved and the parameters needed to evaluate the extent of scCO₂-rock-groundwater reactions have not yet been presented. In this study, the potential for employing the surface roughness value (SR_RMS) to quantify the extent of the scCO₂ involved reaction was evaluated by lab-scale experiments. For a total of 150 days of a simulation of the scCO₂-sandstone-groundwater reaction at 100 bar and 50 °C, the trends in changes in the physical rock properties, pH change, and cation concentration change followed similar logarithmic patterns that were significantly correlated with the logarithmic increase in the SR_RMS value. These findings suggest that changes in surface roughness can quantify the extent of the geochemical weathering process and can be used to evaluate leakage safety due to the progressive changes in rock properties at scCO₂ storage sites. Full article

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

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19 pages, 2527 KiB

Open AccessArticle

Multi-Objective Optimization of Voltage-Stability Based on Congestion Management for Integrating Wind Power into the Electricity Market

by Jin-Woo Choi and Mun-Kyeom Kim^*

Department of Energy System Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea

Appl. Sci. 2017, 7(6), 573; https://doi.org/10.3390/app7060573 - 2 Jun 2017

Cited by 10 | Viewed by 5290

Abstract

This paper proposes voltage-stability based on congestion management (CM) for electricity market environments and considers the incorporation of wind farms into systems as well. A probabilistic voltage-stability constrained optimal power flow (P-VSCOPF) is formulated to maximize both social welfare and voltage stability. To [...] Read more.

This paper proposes voltage-stability based on congestion management (CM) for electricity market environments and considers the incorporation of wind farms into systems as well. A probabilistic voltage-stability constrained optimal power flow (P-VSCOPF) is formulated to maximize both social welfare and voltage stability. To reflect the probabilistic influence of CM in the presence of wind farms on voltage stability, Monte Carlo simulations (MCS) are used to analyze both the system load and the wind speed from their probability distribution functions. A multi-objective particle-swarm optimization (MOPSO) algorithm is implemented to solve the P-VSCOPF problem. A contingency analysis based on the voltage stability index (VSI) for line outages is employed to find the vulnerable line of congestion in power systems. The congestion distribution factor (CDF) is also used to find the optimal location of a wind farm in CM. The optimal pricing expression, which is obtained, with respect to preserving voltage stability, by calculating both the locational marginal prices (LMPs) and the nodal congestion prices (NCPs), is demonstrated in terms of congestion solutions. Simultaneously, the voltage stability margin (VSM) is considered within the CM framework. The proposed approach is implemented on a modified IEEE 24-bus system, and the results obtained are compared with the results of other optimal power flow methods. Full article

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

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12 pages, 4931 KiB

Open AccessArticle

Synergistically-Enhanced Thermal Conductivity of Shape-Stabilized Phase Change Materials by Expanded Graphite and Carbon Nanotube

by Zhang-Peng Liu and Rui Yang^*

Department of Chemical Engineering, Tsinghua University, Beijing 100084, China

Appl. Sci. 2017, 7(6), 574; https://doi.org/10.3390/app7060574 - 2 Jun 2017

Cited by 39 | Viewed by 6560

Abstract

The thermal conductivity of expanded graphite plate (EGP) and/or multi-wall carbon nanotube (MWCNT)-filled, shape-stabilized, phase change material (SSPCM), based on paraffin, high-density polyethylene (HDPE), and styrene-butadiene-styrene copolymer (SBS), was investigated. The results demonstrated that both EGP and MWCNT increased the thermal conductivity of [...] Read more.

The thermal conductivity of expanded graphite plate (EGP) and/or multi-wall carbon nanotube (MWCNT)-filled, shape-stabilized, phase change material (SSPCM), based on paraffin, high-density polyethylene (HDPE), and styrene-butadiene-styrene copolymer (SBS), was investigated. The results demonstrated that both EGP and MWCNT increased the thermal conductivity of the SSPCM. EGP showed a greater thermal conductivity improvement than MWCNT. The conductivity of EGP-filled SSPCM reached 0.574 W/mK at 9 wt %, while that of MWCNT was just 0.372 W/mK at the same loading. Furthermore a series of EGP/MWCNT hybrid fillers were prepared and introduced into the SSPCM, and a synergistic effect was observed between the two fillers. When the EGP/MWCNT ratio was 8:2, the most significant thermal conductivity enhancement to the SSPCM was obtained. The thermal conductivity was 0.674 W/mK, 288% that of the SSPCM and 117% that of 9 wt % EGP-filled SSPCM. The SEM photos showed that a bridging of two-dimensional (2D) planar EGP by flexible one-dimensional (1D) MWCNT was constructed. The so-formed EGP-MWCNT network favored heat transfer along it and led to a decreased thermal interface resistance due to the increased EGP-MWCNT junctions. Full article

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

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11 pages, 5007 KiB

Open AccessArticle

Bionic Walking Foot and Mechanical Performance on Soil

by Ying Wang¹, Jianqiao Li¹, Xiujuan Li^1,*

, Han Huang¹ and Feng Qiu²

¹ Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130025, China

² Key Laboratory of Automobile Materials, Ministry of Education, Department of Materials Science and Engineering, Jilin University, Changchun 130025, China

Appl. Sci. 2017, 7(6), 575; https://doi.org/10.3390/app7060575 - 2 Jun 2017

Cited by 4 | Viewed by 4011

Abstract

The surface structure of the Chinese mitten crab dactylopodite was investigated. The results indicated that the Chinese mitten crab dactylopodite has grooves with variable section structure on the surface of dactylopodite for achieving good traveling behavior on soft terrain. Surface structure plays a [...] Read more.

The surface structure of the Chinese mitten crab dactylopodite was investigated. The results indicated that the Chinese mitten crab dactylopodite has grooves with variable section structure on the surface of dactylopodite for achieving good traveling behavior on soft terrain. Surface structure plays a key role in the walking performance of the leg mechanism. Based on the bionics coupling theory, three bionic walking feet with different section shapes, including circular (Bio 1), circular with grooves (Bio 2), hexagon (Bio 3) and a cylinder foot used for comparison on the aluminum alloy, were designed and fabricated successfully. Meanwhile, comparative experiments on intrusion, extraction and propulsion for walking feet were conducted on different soil. Experimental results show that a bionic walking foot reduced the energy consumption of insertion and extraction, which topped out to 93.95% and 92.78% of cylinder foot, and Bio 2 behaves better. Propulsion is closely correlated with intrusion depth; therefore, compared with cylinder foot, the sinkage of a bionic walking foot helps to achieve a larger propulsion force with the same pressure. Furthermore, the proper depth in balancing the sinkage and propulsion was discussed, which enables us to optimize the structure and performance of a walking foot. Full article

(This article belongs to the Section Mechanical Engineering)

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11 pages, 2433 KiB

Open AccessArticle

Dual Functionalized Freestanding TiO₂ Nanotube Arrays Coated with Ag Nanoparticles and Carbon Materials for Dye-Sensitized Solar Cells

by Ho-Sub Kim^1,†, Myeung-Hwan Chun^1,†, Jung Sang Suh¹, Bong-Hyun Jun^2,*

and Won-Yeop Rho^1,2,*

¹ Department of Chemistry, Seoul National University, Seoul 151-747, Korea

² Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Korea

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 576; https://doi.org/10.3390/app7060576 - 2 Jun 2017

Cited by 19 | Viewed by 4967

Abstract

Highly ordered, freestanding TiO₂ nanotube arrays (TiO₂ NTAs) were prepared using an electrochemical method. The barrier layer was etched to open the bottom of each array, aptly named “open-ended TiO₂ NTAs”. These arrays were coated with silver nanoparticles (Ag NPs) [...] Read more.

Highly ordered, freestanding TiO₂ nanotube arrays (TiO₂ NTAs) were prepared using an electrochemical method. The barrier layer was etched to open the bottom of each array, aptly named “open-ended TiO₂ NTAs”. These arrays were coated with silver nanoparticles (Ag NPs) and/or carbon materials to enhance electron generation and transport. The energy conversion efficiency of the resulting dye-sensitized solar cells (DSSCs) with open-ended freestanding TiO₂ NTAs, when coated with Ag NPs, increased from 5.32% to 6.14% (by 15%) due to plasmonic interactions. Meanwhile, coating the open-ended freestanding TiO₂ NTAs with carbon materials increased the energy conversion efficiency from 5.32% to 6.07% (by 14%), due to π-π conjugation. When the Ag NPs and carbon materials were simultaneously applied to the open-ended freestanding TiO₂ NTAs, the energy conversion efficiency increased from 5.32% to 6.91%—an enhancement of 30%, due to the additive effects of plasmonics and π-π conjugation. Full article

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

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3 pages, 146 KiB

Open AccessEditorial

Special Issue on Advancing Grid-Connected Renewable Generation Systems

by Frede Blaabjerg^*

and Yongheng Yang^*

Department of Energy Technology, Aalborg University, Pontoppidanstraede 111, DK9220 Aalborg, Denmark

Appl. Sci. 2017, 7(6), 577; https://doi.org/10.3390/app7060577 - 3 Jun 2017

Cited by 1 | Viewed by 5587

Abstract

Renewables are heavily involved in power generation, as an essential component for today’s energy paradigm. Energy structure—both national and international—has been undergoing significant changes over the past few decades.[...] Full article

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

19 pages, 14314 KiB

Open AccessArticle

Computational Fluid Dynamics Analysis of Cold Plasma Plume Mixing with Blood Using Level Set Method Coupled with Heat Transfer

by Mehrdad Shahmohammadi Beni and Kwan Ngok Yu^*

Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China

Appl. Sci. 2017, 7(6), 578; https://doi.org/10.3390/app7060578 - 3 Jun 2017

Cited by 10 | Viewed by 6942

Abstract

Cold plasmas were proposed for treatment of leukemia. In the present work, conceptual designs of mixing chambers that increased the contact between the two fluids (plasma and blood) through addition of obstacles within rectangular-block-shaped chambers were proposed and the dynamic mixing between the [...] Read more.

Cold plasmas were proposed for treatment of leukemia. In the present work, conceptual designs of mixing chambers that increased the contact between the two fluids (plasma and blood) through addition of obstacles within rectangular-block-shaped chambers were proposed and the dynamic mixing between the plasma and blood were studied using the level set method coupled with heat transfer. Enhancement of mixing between blood and plasma in the presence of obstacles was demonstrated. Continuous tracking of fluid mixing with determination of temperature distributions was enabled by the present model, which would be a useful tool for future development of cold plasma devices for treatment of blood-related diseases such as leukemia. Full article

(This article belongs to the Special Issue Advances in Thermal System Analysis and Optimization)

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14 pages, 4407 KiB

Open AccessArticle

Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and Structure

by Michael Arthur Cuiffo¹, Jeffrey Snyder², Alicia M. Elliott¹

, Nicholas Romero³, Sandhiya Kannan¹ and Gary P. Halada^1,*

¹ Engineering Bldg. Rm 309, Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794-2275, USA

² Department of Physics, SUNY New Paltz, New Paltz, NY 12561, USA

³ Department of Materials Science and Engineering, Binghamton University, Binghamton, NY 13901, USA

Appl. Sci. 2017, 7(6), 579; https://doi.org/10.3390/app7060579 - 4 Jun 2017

Cited by 252 | Viewed by 18886

Abstract

Polylactic acid (PLA) is an organic polymer commonly used in fused deposition (FDM) printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in [...] Read more.

Polylactic acid (PLA) is an organic polymer commonly used in fused deposition (FDM) printing and biomedical scaffolding that is biocompatible and immunologically inert. However, variations in source material quality and chemistry make it necessary to characterize the filament and determine potential changes in chemistry occurring as a result of the FDM process. We used several spectroscopic techniques, including laser confocal microscopy, Fourier transform infrared (FTIR) spectroscopy and photoacousitc FTIR spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) in order to characterize both the bulk and surface chemistry of the source material and printed samples. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were used to characterize morphology, cold crystallinity, and the glass transition and melting temperatures following printing. Analysis revealed calcium carbonate-based additives which were reacted with organic ligands and potentially trace metal impurities, both before and following printing. These additives became concentrated in voids in the printed structure. This finding is important for biomedical applications as carbonate will impact subsequent cell growth on printed tissue scaffolds. Results of chemical analysis also provided evidence of the hygroscopic nature of the source material and oxidation of the printed surface, and SEM imaging revealed micro- and submicron-scale roughness that will also impact potential applications. Full article

(This article belongs to the Special Issue Materials for 3D Printing)

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9 pages, 4179 KiB

Open AccessArticle

A Polarization-Dependent Frequency-Selective Metamaterial Absorber with Multiple Absorption Peaks

by Guangsheng Deng

, Tianyu Xia, Yong Fang, Jun Yang

and Zhiping Yin^*

Academy of Photoelectric Technology, Hefei University of Technology, Key Lab of Special Display Technology, Ministry of Education, No. 193, Tunxi Road, Hefei 230009, China

Appl. Sci. 2017, 7(6), 580; https://doi.org/10.3390/app7060580 - 4 Jun 2017

Cited by 13 | Viewed by 4834

Abstract

A polarization-dependent, frequency-selective metamaterial (MM) absorber based on a single-layer patterned resonant structure intended for F frequency band is proposed. The design, fabrication, and measurement for the proposed absorber are presented. The absorber’s absorption properties at resonant frequencies have unique characteristics of a [...] Read more.

A polarization-dependent, frequency-selective metamaterial (MM) absorber based on a single-layer patterned resonant structure intended for F frequency band is proposed. The design, fabrication, and measurement for the proposed absorber are presented. The absorber’s absorption properties at resonant frequencies have unique characteristics of a single-band, dual-band, or triple-band absorption for different polarization of the incident wave. The calculated surface current distributions and power loss distribution provide further understanding of physical mechanism of resonance absorption. Moreover, a high absorption for a wide range of TE-polarized oblique incidence was achieved. Hence, the MM structure realized on a highly flexible polyimide film, makingthe absorber suitable for conformal geometry applications. The proposed absorber has great potential in the development of polarization detectors and polarizers. Full article

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

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11 pages, 3402 KiB

Open AccessArticle

Cycling Segments Multimodal Analysis and Classification Using Neural Networks

by Aleš Procházka^1,2,*

, Saeed Vaseghi¹, Hana Charvátová³

, Ondřej Ťupa¹ and Oldřich Vyšata^1,2,4

¹ Department of Computing and Control Engineering, University of Chemistry and Technology in Prague, 166 28 Prague, Czech Republic

² Czech Institute of Informatics, Robotics and Cybernetics, Czech Technical University in Prague, 166 36 Prague, Czech Republic

³ Faculty of Applied Informatics, Tomas Bata University in Zlín, 760 05 Zlín, Czech Republic

⁴ Department of Neurology, Faculty of Medicine in Hradec Králové, Charles University, 500 05 Prague, Czech Republic

Appl. Sci. 2017, 7(6), 581; https://doi.org/10.3390/app7060581 - 4 Jun 2017

Cited by 19 | Viewed by 5030

Abstract

This paper presents methodology for the processing of GPS and heart rate signals acquired during long-term physical activities. The data analysed include geo-positioning and heart rate multichannel signals recorded for 272.2 h of cycling across the Andes mountains over a 5694-km long expedition. [...] Read more.

This paper presents methodology for the processing of GPS and heart rate signals acquired during long-term physical activities. The data analysed include geo-positioning and heart rate multichannel signals recorded for 272.2 h of cycling across the Andes mountains over a 5694-km long expedition. The proposed computational methods include multimodal data de-noising, visualization, and analysis in order to determine specific biomedical features. The results include the correspondence between the heart rate and slope for downhill and uphill cycling and the mean heart rate evolution on flat segments: a regression coefficient of

- 0.014

bpm/h related to time and

6.3

bpm/km related to altitude. The classification accuracy of selected cycling features by neural networks, support vector machine, and k-nearest neighbours methods is between 91.3% and 98.6%. The proposed methods allow the analysis of data during physical activities, enabling an efficient human–machine interaction. Full article

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29 pages, 6912 KiB

Open AccessFeature PaperArticle

Solution Strategies for Linear Inverse Problems in Spatial Audio Signal Processing

by Mingsian R. Bai^1,*, Chun Chung¹, Po-Chen Wu¹, Yi-Hao Chiang¹ and Chun-May Yang²

¹ Department of Power Mechanical Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan

² Department of Electrical Engineering, National Chiao Tung University, No. 1001, Ta-Hsueh Road, Hsinchu 30013, Taiwan

Appl. Sci. 2017, 7(6), 582; https://doi.org/10.3390/app7060582 - 5 Jun 2017

Cited by 11 | Viewed by 4977

Abstract

The aim of this study was to compare algorithms for solving inverse problems generally encountered in spatial audio signal processing. Tikhonov regularization is typically utilized to solve overdetermined linear systems in which the regularization parameter is selected by the golden section search (GSS) [...] Read more.

The aim of this study was to compare algorithms for solving inverse problems generally encountered in spatial audio signal processing. Tikhonov regularization is typically utilized to solve overdetermined linear systems in which the regularization parameter is selected by the golden section search (GSS) algorithm. For underdetermined problems with sparse solutions, several iterative compressive sampling (CS) methods are suggested as alternatives to traditional convex optimization (CVX) methods that are computationally expensive. The focal underdetermined system solver (FOCUSS), the steepest descent (SD) method, Newton’s (NT) method, and the conjugate gradient (CG) method were developed to solve CS problems more efficiently in this study. These algorithms were compared in terms of problems, including source localization and separation, noise source identification, and analysis and synthesis of sound fields, by using a uniform linear array (ULA), a uniform circular array (UCA), and a random array. The derived results are discussed herein and guidelines for the application of these algorithms are summarized. Full article

(This article belongs to the Special Issue Spatial Audio)

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22 pages, 6746 KiB

Open AccessArticle

A Study on Evaluation and Application of Snowmelt Performance of Anti-Icing Asphalt Pavement

by Mulian Zheng^1,*, Shujuan Wu^1,2, Chongtao Wang³, Yifeng Li⁴, Zonghui Ma⁵ and Lei Peng⁶

¹ Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an 710064, China

² Lanzhou University of Technology, Lanzhou 730050, China

³ First Highway Consultants Co., Ltd.,63 Kejier Road Hi-Tech Industries Development Zone, Xi’an 710075, China

⁴ Highway Administration Bureau of Rizhao City, 7 Yantai Road, Rizhao 276826, China

⁵ Highway Administration Bureau of Dezhou City, 1255 Mid Dongfeng Road Decheng District, Dezhou 253006, China

⁶ Hubei Urban Construction Design Institute Co. Ltd., 1 Longxiang Street, Hanyang District, Wuhan 430051, China

Appl. Sci. 2017, 7(6), 583; https://doi.org/10.3390/app7060583 - 5 Jun 2017

Cited by 35 | Viewed by 4874

Abstract

This paper presents a quantitative estimation of anti-icing asphalt mixture snow-melting performance and provides the application guidance for the mixture under study. The regression model of snowmelt quality evolution was established and experimentally verified for different values of snowfall intensity, temperature and blending [...] Read more.

This paper presents a quantitative estimation of anti-icing asphalt mixture snow-melting performance and provides the application guidance for the mixture under study. The regression model of snowmelt quality evolution was established and experimentally verified for different values of snowfall intensity, temperature and blending content of anti-icing filler. The deicing performance of anti-icing asphalt mixtures was evaluated via the impact load tests. The results obtained indicate that the application temperatures of the anti-icing asphalt mixture should exceed −10 °C for moderate or light snow conditions and exceed 0 °C for heavy or blizzard snow conditions. A linear dependence between the snowmelt quality of anti-icing asphalt mixture and time is observed for all tested values of snowfall intensity and temperature. On the other hand, under the same snowfall intensity conditions, a two- to threefold increase of the melting rate with temperature is observed. The available records for the last 30 years in different regions under study concerning variation ranges of three meteorological factors (namely, the extremely minimum temperature, snowfall intensity and the coldest month’s average temperature), the most suitable temperature for application of anti-icing asphalt pavement was identified for each particular region. Full article

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5 pages, 971 KiB

Open AccessCommunication

Measurement of the X-ray Spectrum of a Free Electron Laser with a Wide-Range High-Resolution Single-Shot Spectrometer

by Yuichi Inubushi^1,2,*, Ichiro Inoue², Jangwoo Kim^3,4

, Akihiko Nishihara³, Satoshi Matsuyama³, Hirokatsu Yumoto^1,2, Takahisa Koyama^1,2, Kensuke Tono^1,2, Haruhiko Ohashi^1,2, Kazuto Yamauchi³ and Makina Yabashi^1,2

¹ Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan

² RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan

³ Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan

⁴ Pohang Accelerator Laboratory (PAL), POSTECH, 127-80 Jigokro, Nam-gu, Pohang, Gyeongbuk 37673, Korea

Appl. Sci. 2017, 7(6), 584; https://doi.org/10.3390/app7060584 - 6 Jun 2017

Cited by 36 | Viewed by 5945

Abstract

We developed a single-shot X-ray spectrometer for wide-range high-resolution measurements of Self-Amplified Spontaneous Emission (SASE) X-ray Free Electron Laser (XFEL) pulses. The spectrometer consists of a multi-layer elliptical mirror for producing a large divergence of 22 mrad around 9070 eV and a silicon [...] Read more.

We developed a single-shot X-ray spectrometer for wide-range high-resolution measurements of Self-Amplified Spontaneous Emission (SASE) X-ray Free Electron Laser (XFEL) pulses. The spectrometer consists of a multi-layer elliptical mirror for producing a large divergence of 22 mrad around 9070 eV and a silicon (553) analyzer crystal. We achieved a wide energy range of 55 eV with a fine spectral resolution of 80 meV, which enabled the observation of a whole SASE-XFEL spectrum with fully-resolved spike structures. We found that a SASE-XFEL pulse has around 60 longitudinal modes with a pulse duration of 7.7 ± 1.1 fs. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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15 pages, 8701 KiB

Open AccessArticle

Effect of Different Gradings of Lightweight Aggregates on the Properties of Concrete

by Sang-Yeop Chung¹

, Mohamed Abd Elrahman^1,2,* and Dietmar Stephan¹

¹ Building Materials and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany

² Structural Engineering Department, Mansoura University, Elgomhouria St., Mansoura City 35516, Egypt

Appl. Sci. 2017, 7(6), 585; https://doi.org/10.3390/app7060585 - 7 Jun 2017

Cited by 22 | Viewed by 6469

Abstract

Lightweight aggregate concrete is a material with very low density and good thermal insulation, and several types of lightweight aggregates have been used for lightweight concrete. Since the characteristics of lightweight aggregates strongly affect the properties of lightweight concrete, a proper consideration for [...] Read more.

Lightweight aggregate concrete is a material with very low density and good thermal insulation, and several types of lightweight aggregates have been used for lightweight concrete. Since the characteristics of lightweight aggregates strongly affect the properties of lightweight concrete, a proper consideration for the use of lightweight aggregate is very important for development of lightweight materials. In particular, the sizes and spatial distributions of lightweight aggregates can influence the material responses of lightweight concrete, such as compressive strength and thermal conductivity. In this study, different types of gradings of lightweight aggregates are adopted to investigate the effect of gradings on the material properties. Liaver

^{®}

, an expanded glass granulate, is used as a lightweight aggregate for the specimens. Virtual models of the lightweight specimens with different gradings are numerically generated, and both mechanical and thermal properties are evaluated using experimental and numerical approaches for more detailed investigation. The obtained results can be utilized to suggest an optimal grading that satisfies both the mechanical and thermal properties of lightweight concrete specimen. Full article

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

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39 pages, 1150 KiB

Open AccessFeature PaperArticle

Computational Vibroacoustics in Low- and Medium- Frequency Bands: Damping, ROM, and UQ Modeling

by Roger Ohayon¹ and Christian Soize^2,*

¹ Structural Mechanics and Coupled Systems Laboratory, Conservatoire National des Arts et Metiers (CNAM), 2 rue Conte, 75003 Paris, France

² Laboratoire Modélisation et Simulation Multi-Echelle (MSME UMR 8208 CNRS), Université Paris-Est, 5 bd Descartes, 77454 Marne-la-Vallée, France

Appl. Sci. 2017, 7(6), 586; https://doi.org/10.3390/app7060586 - 7 Jun 2017

Cited by 14 | Viewed by 4852

Abstract

Within the framework of the state-of-the-art, this paper presents a summary of some common research works carried out by the authors concerning computational methods for the prediction of the responses in the frequency domain of general linear dissipative vibroacoustics (structural-acoustic) systems for liquid [...] Read more.

Within the framework of the state-of-the-art, this paper presents a summary of some common research works carried out by the authors concerning computational methods for the prediction of the responses in the frequency domain of general linear dissipative vibroacoustics (structural-acoustic) systems for liquid and gas in the low-frequency (LF) and medium-frequency (MF) domains, including uncertainty quantification (UQ) that plays an important role in the MF domain. The system under consideration consists of a deformable dissipative structure, coupled with an internal dissipative acoustic fluid including a wall acoustic impedance, and surrounded by an infinite acoustic fluid. The system is submitted to given internal and external acoustic sources and to prescribed mechanical forces. An efficient reduced-order computational model (ROM) is constructed using a finite element discretization (FEM) for the structure and the internal acoustic fluid. The external acoustic fluid is treated using a symmetric boundary element method (BEM) in the frequency domain. All the required modeling aspects required for the analysis in the MF domain have been introduced, in particular the frequency-dependent damping phenomena and model uncertainties. An industrial application to a complex computational vibroacoustic model of an automobile is presented. Full article

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

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13 pages, 2952 KiB

Open AccessArticle

Photon Propagation through Linearly Active Dimers

by José Delfino Huerta Morales^1,† and Blas Manuel Rodríguez-Lara^1,2,*,†

¹ Instituto Nacional de Astrofísica, Óptica y Electrónica, Calle Luis Enrique Erro No. 1, Sta. Ma. Tonantzintla, Puebla CP 72840, Mexico

² Photonics and Mathematical Optics Group, Tecnológico de Monterrey, Monterrey 64849, Mexico

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 587; https://doi.org/10.3390/app7060587 - 7 Jun 2017

Cited by 7 | Viewed by 4408

Abstract

We provide an analytic propagator for non-Hermitian dimers showing linear gain or losses in the quantum regime. In particular, we focus on experimentally feasible realizations of the

PT

-symmetric dimer and provide their mean photon number and second order two-point correlation. We study [...] Read more.

We provide an analytic propagator for non-Hermitian dimers showing linear gain or losses in the quantum regime. In particular, we focus on experimentally feasible realizations of the

PT

-symmetric dimer and provide their mean photon number and second order two-point correlation. We study the propagation of vacuum, single photon spatially-separable, and two-photon spatially-entangled states. We show that each configuration produces a particular signature that might signal their possible uses as photon switches, semi-classical intensity-tunable sources, or spatially entangled sources to mention a few possible applications. Full article

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

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17 pages, 895 KiB

Open AccessArticle

Stochastic Model Predictive Control for Urban Traffic Networks

by Bao-Lin Ye^1,*, Weimin Wu², Huimin Gao¹, Yixia Lu³, Qianqian Cao¹ and Lijun Zhu¹

¹ College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001, China

² Institute of Cyber-Systems and Control, College of Control Science and Engineering, Zhejiang University, Hangzhou 310024, China

³ College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, China

Appl. Sci. 2017, 7(6), 588; https://doi.org/10.3390/app7060588 - 7 Jun 2017

Cited by 27 | Viewed by 5399

Abstract

This paper proposes a stochastic model predictive control (MPC) framework for traffic signal coordination and control in urban traffic networks. One of the important features of the proposed stochastic MPC model is that uncertain traffic demands and stochastic disturbances are taken into account. [...] Read more.

This paper proposes a stochastic model predictive control (MPC) framework for traffic signal coordination and control in urban traffic networks. One of the important features of the proposed stochastic MPC model is that uncertain traffic demands and stochastic disturbances are taken into account. Aiming to effectively model the uncertainties and avoid queue spillback in traffic networks, we develop a stochastic expected value model with chance constraints for the objective function of the stochastic MPC model. The objective function is defined to minimize the queue length and the oscillation of green time between any two control steps. Furthermore, by embedding the stochastic simulation and neural networks into a genetic algorithm, we propose a hybrid intelligent algorithm to solve the stochastic MPC model. Finally, numerical results by means of simulation on a road network are presented, which illustrate the performance of the proposed approach. Full article

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13 pages, 2713 KiB

Open AccessArticle

Thermal Management of Concentrated Multi-Junction Solar Cells with Graphene-Enhanced Thermal Interface Materials

by Mohammed Saadah^1,2, Edward Hernandez^2,3 and Alexander A. Balandin^1,2,3,*

¹ Nano-Device Laboratory (NDL), Department of Electrical and Computer Engineering, University of California, Riverside, CA 92521, USA

² Phonon Optimized Engineered Materials (POEM) Center, Bourns College of Engineering, University of California, Riverside, CA 92521, USA

³ Materials Science and Engineering Program, University of California, Riverside, CA 92521, USA

Appl. Sci. 2017, 7(6), 589; https://doi.org/10.3390/app7060589 - 7 Jun 2017

Cited by 56 | Viewed by 8897

Abstract

We report results of experimental investigation of temperature rise in concentrated multi-junction photovoltaic solar cells with graphene-enhanced thermal interface materials. Graphene and few-layer graphene fillers, produced by a scalable environmentally-friendly liquid-phase exfoliation technique, were incorporated into conventional thermal interface materials. Graphene-enhanced thermal interface [...] Read more.

We report results of experimental investigation of temperature rise in concentrated multi-junction photovoltaic solar cells with graphene-enhanced thermal interface materials. Graphene and few-layer graphene fillers, produced by a scalable environmentally-friendly liquid-phase exfoliation technique, were incorporated into conventional thermal interface materials. Graphene-enhanced thermal interface materials have been applied between a solar cell and heat sink to improve heat dissipation. The performance of the multi-junction solar cells has been tested using an industry-standard solar simulator under a light concentration of up to 2000 suns. It was found that the application of graphene-enhanced thermal interface materials allows one to reduce the solar cell temperature and increase the open-circuit voltage. We demonstrated that the use of graphene helps in recovering a significant amount of the power loss due to solar cell overheating. The obtained results are important for the development of new technologies for thermal management of concentrated photovoltaic solar cells. Full article

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

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20 pages, 4840 KiB

Open AccessFeature PaperArticle

Developing Computational Fluid Dynamics (CFD) Models to Evaluate Available Energy in Exhaust Systems of Diesel Light-Duty Vehicles

by Pablo Fernández-Yáñez¹, Octavio Armas^1,*

, Arántzazu Gómez¹ and Antonio Gil²

¹ Universidad de Castilla La Mancha, Campus de Excelencia Internacional en Energía y Medioambiente, Escuela de Ingeniería Industrial, Real Fábrica de Armas, Edificio Sabatini, Av. Carlos III, s/n 45071 Toledo, Spain

² Universitat Politècnica de València, Instituto CMT-Motores Térmicos, Camino de Vera, s/n 46022 Valencia, Spain

Appl. Sci. 2017, 7(6), 590; https://doi.org/10.3390/app7060590 - 8 Jun 2017

Cited by 28 | Viewed by 14134

Abstract

Around a third of the energy input in an automotive engine is wasted through the exhaust system. Since numerous technologies to harvest energy from exhaust gases are accessible, it is of great interest to find time- and cost-efficient methods to evaluate available thermal [...] Read more.

Around a third of the energy input in an automotive engine is wasted through the exhaust system. Since numerous technologies to harvest energy from exhaust gases are accessible, it is of great interest to find time- and cost-efficient methods to evaluate available thermal energy under different engine conditions. Computational fluid dynamics (CFD) is becoming a very valuable tool for numerical predictions of exhaust flows. In this work, a methodology to build a simple three-dimensional (3D) model of the exhaust system of automotive internal combustion engines (ICE) was developed. Experimental data of exhaust gas in the most used part of the engine map in passenger diesel vehicles were employed as input for calculations. Sensitivity analyses of different numeric schemes have been conducted in order to attain accurate results. The model built allows for obtaining details on temperature and pressure fields along the exhaust system, and for complementing the experimental results for a better understanding of the flow phenomena and heat transfer through the system for further energy recovery devices. Full article

(This article belongs to the Special Issue Internal Combustion Engines (ICE) for Ground Transport)

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28 pages, 8901 KiB

Open AccessArticle

Systematic Design Method and Experimental Validation of a 2-DOF Compliant Parallel Mechanism with Excellent Input and Output Decoupling Performances

by Yao Jiang^1,2, Tiemin Li^2,3,*, Liping Wang^2,3 and Feifan Chen¹

¹ Department of Precision Instrument, Institute of Instrument Science and Technology, Tsinghua University, Beijing 10084, China

² Beijing Key Lab of Precision/Ultra-Precision Manufacturing, Equipments and Control, Tsinghua University, Beijing 100084, China

³ Department of Mechanical Engineering, Institute of Manufacturing Engineering, Tsinghua University, Beijing 100084, China

Appl. Sci. 2017, 7(6), 591; https://doi.org/10.3390/app7060591 - 8 Jun 2017

Cited by 5 | Viewed by 5351

Abstract

The output and input coupling characteristics of the compliant parallel mechanism (CPM) bring difficulty in the motion control and challenge its high performance and operational safety. This paper presents a systematic design method for a 2-degrees-of-freedom (DOFs) CPM with excellent decoupling performance. A [...] Read more.

The output and input coupling characteristics of the compliant parallel mechanism (CPM) bring difficulty in the motion control and challenge its high performance and operational safety. This paper presents a systematic design method for a 2-degrees-of-freedom (DOFs) CPM with excellent decoupling performance. A symmetric kinematic structure can guarantee a CPM with a complete output decoupling characteristic; input coupling is reduced by resorting to a flexure-based decoupler. This work discusses the stiffness design requirement of the decoupler and proposes a compound flexure hinge as its basic structure. Analytical methods have been derived to assess the mechanical performances of the CPM in terms of input and output stiffness, motion stroke, input coupling degree, and natural frequency. The CPM’s geometric parameters were optimized to minimize the input coupling while ensuring key performance indicators at the same time. The optimized CPM’s performances were then evaluated by using a finite element analysis. Finally, a prototype was constructed and experimental validations were carried out to test the performance of the CPM and verify the effectiveness of the design method. The design procedure proposed in this paper is systematic and can be extended to design the CPMs with other types of motion. Full article

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35 pages, 2987 KiB

Open AccessFeature PaperArticle

Photon Beam Transport and Scientific Instruments at the European XFEL

by Thomas Tschentscher^*, Christian Bressler, Jan Grünert, Anders Madsen, Adrian P. Mancuso, Michael Meyer, Andreas Scherz, Harald Sinn and Ulf Zastrau

European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany

Appl. Sci. 2017, 7(6), 592; https://doi.org/10.3390/app7060592 - 9 Jun 2017

Cited by 264 | Viewed by 16166

Abstract

European XFEL is a free-electron laser (FEL) user facility providing soft and hard X-ray FEL radiation to initially six scientific instruments. Starting user operation in fall 2017 European XFEL will provide new research opportunities to users from science domains as diverse as physics, [...] Read more.

European XFEL is a free-electron laser (FEL) user facility providing soft and hard X-ray FEL radiation to initially six scientific instruments. Starting user operation in fall 2017 European XFEL will provide new research opportunities to users from science domains as diverse as physics, chemistry, geo- and planetary sciences, materials sciences or biology. The unique feature of European XFEL is the provision of high average brilliance in the soft and hard X-ray regime, combined with the pulse properties of FEL radiation of extreme peak intensities, femtosecond pulse duration and high degree of coherence. The high average brilliance is achieved through acceleration of up to 27,000 electron bunches per second by the super-conducting electron accelerator. Enabling the usage of this high average brilliance in user experiments is one of the major instrumentation drivers for European XFEL. The radiation generated by three FEL sources is distributed via long beam transport systems to the experiment hall where the scientific instruments are located side-by-side. The X-ray beam transport systems have been optimized to maintain the unique features of the FEL radiation which will be monitored using build-in photon diagnostics. The six scientific instruments are optimized for specific applications using soft or hard X-ray techniques and include integrated lasers, dedicated sample environment, large area high frame rate detector(s) and computing systems capable of processing large quantities of data. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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17 pages, 5046 KiB

Open AccessArticle

Shake Table Test for the Collapse Investigation of a Typical Multi-Story Reinforced Concrete Frame Structure in the Meizoseismal Area

by Weixiao Xu

, Weisong Yang^*, Chunwei Zhang^* and Dehu Yu

¹ School of Civil Engineering, Qingdao University of Technology, No.11 Fushun Road, Shibei District, Qingdao 266033, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 593; https://doi.org/10.3390/app7060593 - 8 Jun 2017

Cited by 11 | Viewed by 8792

Abstract

According to statistics from past earthquakes, it is observed that multi-story reinforced concrete (RC) frames represent a large proportion of the structural failures or collapses in seismic events. Hence, research on seismic collapse mechanisms and risks of RC frame structures subjected to extreme [...] Read more.

According to statistics from past earthquakes, it is observed that multi-story reinforced concrete (RC) frames represent a large proportion of the structural failures or collapses in seismic events. Hence, research on seismic collapse mechanisms and risks of RC frame structures subjected to extreme earthquakes is of foremost importance. Both experimental and numerical studies have been substantially carried out in this field. In order to represent an actual process of structural damage in an actual seismic event and provide a calibration test for numerical studies, a shake table collapse test of a typical multi-story RC frame structural model, which is scaled from a nearly collapsed building in the 2010 Ms 7.1 Yushu earthquake in China, was performed. Both the test and earthquake field investigation indicate that severe damage mainly occurred at the column ends. As dual structural systems, i.e., systems combining frames and additional members that mainly carry seismic loading, could be a better way to solve the unexpected damage mechanism of RC frames, a practical stiffness iteration design method based on the nonlinear static analysis to obtain the optimal stiffness demanding of the lateral load-resisting members in each story is proposed. This approach aims to control the structural deformation pattern along the height. The outcome of this study provides some intrinsic understanding of the inherent collapse mechanisms of similar RC frames during strong earthquakes. It also offers a practical design method to improve the seismic collapse resistance of RC frames. Full article

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16 pages, 3572 KiB

Open AccessArticle

Zwitterionic Polymer P(AM-DMC-AMPS) as a Low-Molecular-Weight Encapsulator in Deepwater Drilling Fluid

by Xin Zhao^1,2,*, Zhengsong Qiu^1,2, Yongjun Zhang³, Hanyi Zhong^1,2, Weian Huang^1,2 and Zhichuan Tang¹

¹ School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China

² National Engineering Laboratory for Testing and Detection Technology of Subsea Equipments, Qingdao 266580, China

³ Tianjin Ruiyang Offshore Engineering Company Limited, Tianjin 300450, China

Appl. Sci. 2017, 7(6), 594; https://doi.org/10.3390/app7060594 - 8 Jun 2017

Cited by 42 | Viewed by 6545

Abstract

In deepwater oil and gas drilling, the high-molecular-weight encapsulator aggravates the thickening of the drilling fluid at low temperatures. Therefore, it is hard to manage the downhole pressure, and drilling fluid loss occurs. In this paper, a zwitterionic polymer P(AM-DMC-AMPS) which was the [...] Read more.

In deepwater oil and gas drilling, the high-molecular-weight encapsulator aggravates the thickening of the drilling fluid at low temperatures. Therefore, it is hard to manage the downhole pressure, and drilling fluid loss occurs. In this paper, a zwitterionic polymer P(AM-DMC-AMPS) which was the terpolymer of acrylamide, methacrylatoethyl trimethyl ammonium chloride, and 2-acrylamido-2-methylpropane sulfonic acid, was developed as a low-molecular-weight encapsulator. It was characterized by Fourier transform infrared spectrum analysis, nuclear magnetic resonance, and gel permeation chromatography. Moreover, the low-temperature rheology, shale inhibition and filtration properties of water-based drilling fluids (WBDFs) containing different encapsulators were experimentally investigated and compared. The results showed that the molecular weight of P(AM-DMC-AMPS) was about 260,000, much lower than that of the conventional encapsulators. In the deepwater drilling temperature range 4–75 °C, WBDF containing P(AM-DMC-AMPS) had lower and more stable rheological property because of its short molecular chains. The high shale recovery rate and low swelling rate indicated its strong shale inhibition performance, owing to its adsorption on the clay surface and the wrapping effect through both hydrogen bonding and electrostatic interaction. It also improved the filtration property of WBDF, and was compatible with other WBDF components. This product is expected to simultaneously realize the good encapsulation performance and low-temperature rheological property for deepwater drilling fluid. Full article

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

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28 pages, 11693 KiB

Open AccessFeature PaperArticle

Scattering Characteristics of X-, C- and L-Band PolSAR Data Examined for the Tundra Environment of the Tuktoyaktuk Peninsula, Canada

by Tobias Ullmann^1,*

, Sarah N. Banks², Andreas Schmitt³ and Thomas Jagdhuber⁴

¹ Institute Geography and Geology, University of Wuerzburg, D-97074 Wuerzburg, Germany

² National Wildlife Research Center (NWRC), Carleton University, Ottawa, ON K1A 0H3, Canada

³ Department of Geoinformatics, University of Applied Sciences Munich, D-80333 Munich, Germany

⁴ German Aerospace Center (DLR), Microwaves and Radar Institute, D-82234 Wessling, Germany

Appl. Sci. 2017, 7(6), 595; https://doi.org/10.3390/app7060595 - 8 Jun 2017

Cited by 24 | Viewed by 6260

Abstract

In this study, polarimetric Synthetic Aperture Radar (PolSAR) data at X-, C- and L-Bands, acquired by the satellites: TerraSAR-X (2011), Radarsat-2 (2011), ALOS (2010) and ALOS-2 (2016), were used to characterize the tundra land cover of a test site located close to the [...] Read more.

In this study, polarimetric Synthetic Aperture Radar (PolSAR) data at X-, C- and L-Bands, acquired by the satellites: TerraSAR-X (2011), Radarsat-2 (2011), ALOS (2010) and ALOS-2 (2016), were used to characterize the tundra land cover of a test site located close to the town of Tuktoyaktuk, NWT, Canada. Using available in situ ground data collected in 2010 and 2012, we investigate PolSAR scattering characteristics of common tundra land cover classes at X-, C- and L-Bands. Several decomposition features of quad-, co-, and cross-polarized data were compared, the correlation between them was investigated, and the class separability offered by their different feature spaces was analyzed. Certain PolSAR features at each wavelength were sensitive to the land cover and exhibited distinct scattering characteristics. Use of shorter wavelength imagery (X and C) was beneficial for the characterization of wetland and tundra vegetation, while L-Band data highlighted differences of the bare ground classes better. The Kennaugh Matrix decomposition applied in this study provided a unified framework to store, process, and analyze all data consistently, and the matrix offered a favorable feature space for class separation. Of all elements of the quad-polarized Kennaugh Matrix, the intensity based elements K0, K1, K2, K3 and K4 were found to be most valuable for class discrimination. These elements contributed to better class separation as indicated by an increase of the separability metrics squared Jefferys Matusita Distance and Transformed Divergence. The increase in separability was up to 57% for Radarsat-2 and up to 18% for ALOS-2 data. Full article

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

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26 pages, 4504 KiB

Open AccessArticle

IoT-Based Information System for Healthcare Application: Design Methodology Approach

by Damian Dziak^1,*, Bartosz Jachimczyk² and Wlodek J. Kulesza³

¹ Faculty of Electrical and Control Engineering, Gdansk University of Technology, G. Narutowicza 11/12, 80-233 Gdansk, Poland

² BetterSolutions S.A., Al. Grunwaldzka 472, 80-309 Gdansk, Poland

³ Department of Applied Signal Processing, Blekinge Institute of Technology, 371 79 Karlskrona, Sweden

Appl. Sci. 2017, 7(6), 596; https://doi.org/10.3390/app7060596 - 8 Jun 2017

Cited by 103 | Viewed by 13680

Abstract

Over the last few decades, life expectancy has increased significantly. However, elderly people who live on their own often need assistance due to mobility difficulties, symptoms of dementia or other health problems. In such cases, an autonomous supporting system may be helpful. This [...] Read more.

Over the last few decades, life expectancy has increased significantly. However, elderly people who live on their own often need assistance due to mobility difficulties, symptoms of dementia or other health problems. In such cases, an autonomous supporting system may be helpful. This paper proposes the Internet of Things (IoT)-based information system for indoor and outdoor use. Since the conducted survey of related works indicated a lack of methodological approaches to the design process, therefore a Design Methodology (DM), which approaches the design target from the perspective of the stakeholders, contracting authorities and potential users, is introduced. The implemented solution applies the three-axial accelerometer and magnetometer, Pedestrian Dead Reckoning (PDR), thresholding and the decision trees algorithm. Such an architecture enables the localization of a monitored person within four room-zones with accuracy; furthermore, it identifies falls and the activities of lying, standing, sitting and walking. Based on the identified activities, the system classifies current activities as normal, suspicious or dangerous, which is used to notify the healthcare staff about possible problems. The real-life scenarios validated the high robustness of the proposed solution. Moreover, the test results satisfied both stakeholders and future users and ensured further cooperation with the project. Full article

(This article belongs to the Special Issue Smart Healthcare)

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12 pages, 3027 KiB

Open AccessArticle

Research on the Robustness of Interdependent Networks under Localized Attack

by Junde Wang^1,*, Songyang Lao¹, Yirun Ruan¹, Liang Bai¹ and Lvlin Hou²

¹ Science and Technology on Information Systems Engineering Laboratory, National University of Defense Technology, Changsha 410073, China

² Department of logistics command, The Logistics Academy, Beijing 100858, China

Appl. Sci. 2017, 7(6), 597; https://doi.org/10.3390/app7060597 - 9 Jun 2017

Cited by 9 | Viewed by 4362

Abstract

Critical infrastructures (CI) are the cornerstone of modern society, and they are connected with each other through material, energy, or information. The robustness of interdependent CI systems under attack has been a hot topic in recent years, but previous studies mainly focused on [...] Read more.

Critical infrastructures (CI) are the cornerstone of modern society, and they are connected with each other through material, energy, or information. The robustness of interdependent CI systems under attack has been a hot topic in recent years, but previous studies mainly focused on malicious attacks or random failure. To analyze the impact of some natural disasters whose destructive force is mainly related to distance with respect to interdependent CI systems, we present a new localized attack mode considering destructive force decays with distance, and carry out simulations on several interdependent networks constructed by artificial and real world networks. Furthermore, this article analyzes the influence of coupling strength and coupling pattern on the robustness of interdependent system. The results show that dependency links between networks decrease the robustness of interdependence networks, but the robustness under failure probability degradation is not vulnerable like that under malicious attack or random failure. In addition, the coupling preference has little effect on the robustness of interdependent networks under the new localized attack strategy; when the average degree of subnetworks is large, the same conclusion can be obtained for the coupling strength. Full article

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22 pages, 4650 KiB

Open AccessArticle

Performance Analysis of a Forecasting Relocation Model for One-Way Carsharing

by Ganjar Alfian^1,*

, Jongtae Rhee², Muhammad Fazal Ijaz²

, Muhammad Syafrudin²

and Norma Latif Fitriyani²

¹ u-SCM Research Center, Nano Information Technology Academy, Dongguk University, Seoul 100-715, Korea

² Department of Industrial and Systems Engineering, Dongguk University, Seoul 100-715, Korea

Appl. Sci. 2017, 7(6), 598; https://doi.org/10.3390/app7060598 - 9 Jun 2017

Cited by 21 | Viewed by 6801

Abstract

A carsharing service can be seen as a transport alternative between private and public transport that enables a group of people to share vehicles based at certain stations. The advanced carsharing service, one-way carsharing, enables customers to return the car to another station. [...] Read more.

A carsharing service can be seen as a transport alternative between private and public transport that enables a group of people to share vehicles based at certain stations. The advanced carsharing service, one-way carsharing, enables customers to return the car to another station. However, one-way implementation generates an imbalanced distribution of cars in each station. Thus, this paper proposes forecasting relocation to solve car distribution imbalances for one-way carsharing services. A discrete event simulation model was developed to help evaluate the proposed model performance. A real case dataset was used to find the best simulation result. The results provide a clear insight into the impact of forecasting relocation on high system utilization and the reservation acceptance ratio compared to traditional relocation methods. Full article

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

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21 pages, 10919 KiB

Open AccessArticle

Bridge Expansion Joint in Road Transition Curve: Effects Assessment on Heavy Vehicles

by Paola Di Mascio

, Giuseppe Loprencipe^*

, Laura Moretti

, Lorenzo Puzzo and Pablo Zoccali

Department of Civil, Constructional and Environmental Engineering, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy

Appl. Sci. 2017, 7(6), 599; https://doi.org/10.3390/app7060599 - 9 Jun 2017

Cited by 17 | Viewed by 6798

Abstract

Properly-designed road surfaces provide a durable surface on which traffic can pass smoothly and safely. In fact, the main causes that determine the structural decay of the pavement and its parts are the traffic loads. These repeated actions can create undesirable unevennesses on [...] Read more.

Properly-designed road surfaces provide a durable surface on which traffic can pass smoothly and safely. In fact, the main causes that determine the structural decay of the pavement and its parts are the traffic loads. These repeated actions can create undesirable unevennesses on the road surface, which induce vertical accelerations on vehicles, up to hindering contact between pavement and tire, with dangerous consequences on traffic safety. The dynamic actions transmitted by the vehicles depend on these irregularities: often, a bridge expansion joint (BEJ), introducing a necessary discontinuity between different materials, determines from the beginning a geometric irregularity in the running surface. Besides, some structural conditions could emphasize the problem (e.g., local cracking due to the settlement of the subgrade near the abutment or the discontinuity of stiffness due to the presence of different materials). When the BEJ is located in a transition curve, an inevitable vertical irregularity between road and joint can reach values of some centimeters, with serious consequences for the road safety. This paper deals with the analysis of a case study of a BEJ. Several test surveys were performed in order to fully characterize the effects on both vehicles and pavement. The three-dimensional representation of the pavement surface and the acceleration measurements on a heavy test vehicle were performed to analyze the joint behavior under traffic. Finally, a finite element model was implemented to evaluate the stress contribution on vehicle components induced by the vertical irregularities. Full article

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18 pages, 53813 KiB

Open AccessArticle

Endoscopic Laser-Based 3D Imaging for Functional Voice Diagnostics

by Marion Semmler^1,*, Stefan Kniesburges¹

, Jonas Parchent¹, Bernhard Jakubaß¹, Maik Zimmermann^2,3, Christopher Bohr¹, Anne Schützenberger¹ and Michael Döllinger¹

¹ University Hospital Erlangen, Medical School, Division of Phoniatrics and Pediatric Audiology at the Department of Otorhinolaryngology, Head & Neck Surgery, Waldstr. 1, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany

² Bayerisches Laserzentrum GmbH, Konrad-Zuse-Str. 2-6, 91052 Erlangen, Germany

³ Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen, Germany

Appl. Sci. 2017, 7(6), 600; https://doi.org/10.3390/app7060600 - 9 Jun 2017

Cited by 23 | Viewed by 7466

Abstract

Recently, we reported on the in vivo application of a miniaturized measuring device for 3D visualization of the superior vocal fold vibrations from high-speed recordings in combination with a laser projection unit (LPU). As a long-term vision for this proof of principle, we [...] Read more.

Recently, we reported on the in vivo application of a miniaturized measuring device for 3D visualization of the superior vocal fold vibrations from high-speed recordings in combination with a laser projection unit (LPU). As a long-term vision for this proof of principle, we strive to integrate the further developed laserendoscopy as a diagnostic method in daily clinical routine. The new LPU mainly comprises a Nd:YAG laser source (532 nm/CW/2

ω

) and a diffractive optical element (DOE) generating a regular laser grid (31 × 31 laser points) that is projected on the vocal folds. By means of stereo triangulation, the 3D coordinates of the laser points are reconstructed from the endoscopic high-speed footage. The new design of the laserendoscope constitutes a compromise between robust image processing and laser safety regulations. The algorithms for calibration and analysis are now optimized with respect to their overall duration and the number of required interactions, which is objectively assessed using binary classifiers. The sensitivity and specificity of the calibration procedure are increased by 40.1% and 22.3%, which is statistically significant. The overall duration for the laser point detection is reduced by 41.9%. The suggested semi-automatic reconstruction software represents an important stepping-stone towards potential real time processing and a comprehensive, objective diagnostic tool of evidence-based medicine. Full article

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

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12 pages, 1980 KiB

Open AccessArticle

A Statistical Model Updating Method of Beam Structures with Random Parameters under Static Load

by Zhifeng Wu, Bin Huang^*, Yejun Li and Wuchuan Pu

School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China

Appl. Sci. 2017, 7(6), 601; https://doi.org/10.3390/app7060601 - 9 Jun 2017

Cited by 6 | Viewed by 4190

Abstract

This paper presents a new statistical model updating method of beam structures with random parameters under static load. The new updating method considers structural parameters and measurement errors to be random. To reduce the unmeasured degrees of freedom in the finite element model, [...] Read more.

This paper presents a new statistical model updating method of beam structures with random parameters under static load. The new updating method considers structural parameters and measurement errors to be random. To reduce the unmeasured degrees of freedom in the finite element model, a static condensation technique is used in this method. A statistical model updating equation with respect to element updated factors is established afterwards. The element updated factors are expanded as random multivariate power series. Using a high-order perturbation technique, the statistical model updating equation can be solved to obtain the coefficients of the power series expansions of the element updated factors. The results of two numerical examples show that for the solution of the statistical model updating equation, the accuracy of the proposed method agrees with that of the Monte Carlo simulation method very well. The static responses obtained by the updated finite element model coincide with the measured results very well. Finally, a series of static load tests of the concrete beam are conducted to testify the effectiveness of the proposed method. Full article

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9 pages, 3182 KiB

Open AccessArticle

A Multi-Year Study on Rice Morphological Parameter Estimation with X-Band Polsar Data

by Onur Yuzugullu^1,*, Esra Erten²

and Irena Hajnsek^1,3

¹ Institute of Environmental Engineering ETH Zurich, 8093 Zurich, Switzerland

² Faculty of Civil Engineering, Istanbul Technical University, 34469 Istanbul, Turkey

³ Microwaves and Radar Institute, German Aerospace Center (DLR), 82234 Oberpfaffenhofen, Germany

Appl. Sci. 2017, 7(6), 602; https://doi.org/10.3390/app7060602 - 9 Jun 2017

Cited by 13 | Viewed by 4305

Abstract

Rice fields have been monitored with spaceborne Synthetic Aperture Radar (SAR) systems for decades. SAR is an essential source of data and allows for the estimation of plant properties such as canopy height, leaf area index, phenological phase, and yield. However, the information [...] Read more.

Rice fields have been monitored with spaceborne Synthetic Aperture Radar (SAR) systems for decades. SAR is an essential source of data and allows for the estimation of plant properties such as canopy height, leaf area index, phenological phase, and yield. However, the information on detailed plant morphology in meter-scale resolution is necessary for the development of better management practices. This letter presents the results of the procedure that estimates the stalk height, leaf length and leaf width of rice fields from a copolar X-band TerraSAR-X time series data based on a priori phenological phase. The methodology includes a computationally efficient stochastic inversion algorithm of a metamodel that mimics a radiative transfer theory-driven electromagnetic scattering (EM) model. The EM model and its metamodel are employed to simulate the backscattering intensities from flooded rice fields based on their simplified physical structures. The results of the inversion procedure are found to be accurate for cultivation seasons from 2013 to 2015 with root mean square errors less than 13.5 cm for stalk height, 7 cm for leaf length, and 4 mm for leaf width parameters. The results of this research provided new perspectives on the use of EM models and computationally efficient metamodels for agriculture management practices. Full article

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

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16 pages, 2922 KiB

Open AccessArticle

A New Life for Cross-Linked Plastic Waste as Aggregates and Binder Modifier for Asphalt Mixtures

by Liliana M. B. Costa¹, Joana Peralta², Joel R. M. Oliveira¹

and Hugo M. R. D. Silva^1,*

¹ CTAC, Centre for Territory, Environment and Construction, University of Minho, Guimarães 4800 058, Portugal

² Wacker Chemical Corporation, 6870 Tilghman Street, Allentown, PA 18106-9346, USA

Appl. Sci. 2017, 7(6), 603; https://doi.org/10.3390/app7060603 - 10 Jun 2017

Cited by 37 | Viewed by 6080

Abstract

Every year, millions of tons of plastic waste, with potential to be reused, are wasted in landfills. Based on a literature review and in a local market analysis, cross-linked polyethylene (PEX) waste arose as the material with the greatest potential to be tested [...] Read more.

Every year, millions of tons of plastic waste, with potential to be reused, are wasted in landfills. Based on a literature review and in a local market analysis, cross-linked polyethylene (PEX) waste arose as the material with the greatest potential to be tested for incorporation in asphalt mixtures due to the difficulty in its recycling and the lack of solutions for its reuse. Thus, in the present work, mixtures produced with and without PEX were tested in order to compare their performance, aiming at understanding if this waste could successfully be used as an alternative material for this type of application. Thus, water sensitivity, rutting resistance, stiffness modulus and fatigue cracking resistance tests were carried out on asphalt mixtures with up to 5% PEX. Based on the results obtained, it can be concluded that the incorporation of PEX in asphalt mixtures is a viable solution for paving works, especially when high service temperatures are expected. It also decreases the density of the mixture, which can be attractive to lighten structures. Thus, this technology contributes to give new life to cross-linked polyethylene plastic waste. Full article

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

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10 pages, 2140 KiB

Open AccessFeature PaperReview

Status of the SACLA Facility

by Makina Yabashi^1,*

, Hitoshi Tanaka¹

, Kensuke Tono² and Tetsuya Ishikawa¹

¹ RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan

² Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan

Appl. Sci. 2017, 7(6), 604; https://doi.org/10.3390/app7060604 - 10 Jun 2017

Cited by 33 | Viewed by 6373

Abstract

This article reports the current status of SACLA, SPring-8 Angstrom Compact free electron LAser, which has been producing stable X-ray Free Electron Laser (XFEL) light since 2012. A unique injector system and a short-period in-vacuum undulator enable the generation of ultra-short coherent X-ray [...] Read more.

This article reports the current status of SACLA, SPring-8 Angstrom Compact free electron LAser, which has been producing stable X-ray Free Electron Laser (XFEL) light since 2012. A unique injector system and a short-period in-vacuum undulator enable the generation of ultra-short coherent X-ray pulses with a wavelength shorter than 0.1 nm. Continuous development of accelerator technologies has steadily improved XFEL performance, not only for normal operations but also for fast switching operation of the two beamlines. After upgrading the broadband spontaneous-radiation beamline to produce soft X-ray FEL with a dedicated electron beam driver, it is now possible to operate three FEL beamlines simultaneously. Beamline/end-station instruments and data acquisition/analyzation systems have also been upgraded to allow advanced experiments. These efforts have led to the production of novel results and will offer exciting new opportunities for users from many fields of science. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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18 pages, 4691 KiB

Open AccessArticle

Effect of Seasonal Temperature on the Performance and on the Microbial Community of a Novel AWFR for Decentralized Domestic Wastewater Pretreatment

by Juanhong Li

and Xiwu Lu^*

School of Energy and Environment, Southeast University, Nanjing 210096, China

Appl. Sci. 2017, 7(6), 605; https://doi.org/10.3390/app7060605 - 11 Jun 2017

Cited by 8 | Viewed by 5000

Abstract

Due to environmental burden and human health risks in developing countries, the treatment of decentralized domestic wastewater has been a matter of great concern in recent years. A novel pilot-scale three-stage anaerobic wool-felt filter reactor (AWFR) was designed to treat real decentralized domestic [...] Read more.

Due to environmental burden and human health risks in developing countries, the treatment of decentralized domestic wastewater has been a matter of great concern in recent years. A novel pilot-scale three-stage anaerobic wool-felt filter reactor (AWFR) was designed to treat real decentralized domestic wastewater at seasonal temperature variations of 8 to 35 °C for 364 days. The results showed that the average chemical oxygen demand (COD) removal efficiencies of AWFR in summer and winter were 76 ± 7.2% and 52 ± 5.9% at one day and three days Hydraulic Retention Time (HRT), respectively. COD mass balance analysis demonstrated that even though COD removal was lower in winter, approximately 43.5% of influent COD was still converted to methane. High-throughput MiSeq sequencing analyses indicated that Methanosaeta, Methanobacterium, and Methanolinea were the predominant methanogens, whereas the genus Bacillus probably played important roles in fermentation processes throughout the whole operation period. The performance and microbial community composition study suggested the application potential of the AWFR system for the pretreatment of decentralized domestic wastewater. Full article

(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)

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21 pages, 4219 KiB

Open AccessArticle

Effects of Nozzle Configuration on Rock Erosion Under a Supercritical Carbon Dioxide Jet at Various Pressures and Temperatures

by Man Huang^1,2,3, Yong Kang^1,2,3,*, Xiaochuan Wang^1,2,3, Yi Hu^1,2,3, Deng Li^1,2,3, Can Cai^1,2,3 and Feng Chen^1,2,3

¹ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China

² Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan 430072, China

³ School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China

Appl. Sci. 2017, 7(6), 606; https://doi.org/10.3390/app7060606 - 12 Jun 2017

Cited by 24 | Viewed by 7351

Abstract

The supercritical carbon dioxide (SC-CO₂) jet offers many advantages over water jets in the field of oil and gas exploration and development. To take better advantage of the SC-CO₂ jet, effects of nozzle configuration on rock erosion characteristics were experimentally [...] Read more.

The supercritical carbon dioxide (SC-CO₂) jet offers many advantages over water jets in the field of oil and gas exploration and development. To take better advantage of the SC-CO₂ jet, effects of nozzle configuration on rock erosion characteristics were experimentally investigated with respect to the erosion volume. A convergent nozzle and two Laval nozzles, as well as artificial cores were employed in the experiments. It was found that the Laval nozzle can enhance rock erosion ability, which largely depends on the pressure and temperature conditions. The enhancement increases with rising inlet pressure. Compared with the convergent nozzle, the Laval-1 nozzle maximally enhances the erosion volume by 10%, 21.2% and 30.3% at inlet pressures of 30, 40 and 50 MPa, respectively; while the Laval-2 nozzle maximally increases the erosion volume by 32.5%, 49.2% and 60%. Moreover, the enhancement decreases with increasing ambient pressure under constant inlet pressure or constant pressure drop. The growth of fluid temperature above the critical value can increase the enhancement. In addition, the jet from the Laval-2 nozzle with a smooth inner profile always has a greater erosion ability than that from the Laval-1 nozzle. Full article

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

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13 pages, 5175 KiB

Open AccessFeature PaperProject Report

Status of the SXFEL Facility

by Zhentang Zhao^*, Dong Wang, Qiang Gu, Lixin Yin, Ming Gu, Yongbin Leng and Bo Liu

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China

Appl. Sci. 2017, 7(6), 607; https://doi.org/10.3390/app7060607 - 12 Jun 2017

Cited by 66 | Viewed by 8055

Abstract

The Shanghai soft X-ray Free-Electron Laser facility (SXFEL) is being developed in two steps; the SXFEL test facility (SXFEL-TF), and the SXFEL user facility (SXFEL-UF). The SXFEL-TF is a critical development step towards the construction a soft X-ray FEL user facility in China, [...] Read more.

The Shanghai soft X-ray Free-Electron Laser facility (SXFEL) is being developed in two steps; the SXFEL test facility (SXFEL-TF), and the SXFEL user facility (SXFEL-UF). The SXFEL-TF is a critical development step towards the construction a soft X-ray FEL user facility in China, and is under commissioning at the Shanghai Synchrotron Radiation Facility (SSRF) campus. The test facility is going to generate 8.8 nm FEL radiation using an 840 MeV electron linac passing through the two-stage cascaded HGHG-HGHG or EEHG-HGHG (high-gain harmonic generation, echo-enabled harmonic generation) scheme. The construction of the SXFEL-TF started at the end of 2014. Its accelerator tunnel and klystron gallery were ready for equipment installation in April 2016, and the installation of the SXFEL-TF linac and radiator undulators were completed by the end of 2016. In the meantime, the SXFEL-UF, with a designated wavelength in the water window region, began construction in November 2016. This was based on upgrading the linac energy to 1.5 GeV, and the building of a second undulator line and five experimental end-stations. Construction status and the future plans of the SXFEL are reported in this paper. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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12 pages, 5347 KiB

Open AccessArticle

The Influences of Assisting Gas Type and Process Parameters on the Fiber Laser Microprofiling of Thin CoCr Tubes for Vascular Stents

by Lei Liu^1,2, Dongbo Li¹, Yifei Tong^1,*

and Yufu Zhu²

¹ School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

² Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai’an 223001, China

Appl. Sci. 2017, 7(6), 608; https://doi.org/10.3390/app7060608 - 12 Jun 2017

Cited by 4 | Viewed by 4823

Abstract

Cobalt chromium (CoCr) alloy tubes have been widely used in manufacturing of vascular stents, due to their excellent bio-mechanical properties, especially their high strength. In recent years, fiber lasers have been used in the micro-machining of vascular stents, given their better cutting quality [...] Read more.

Cobalt chromium (CoCr) alloy tubes have been widely used in manufacturing of vascular stents, due to their excellent bio-mechanical properties, especially their high strength. In recent years, fiber lasers have been used in the micro-machining of vascular stents, given their better cutting quality than neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. A comparison study of CoCr fiber laser cutting with oxygen and argon is presented, and the differences, such as surface topography, chemical composition, and kerfs geometry, between the oxygen cuts and argon cuts are studied. Three types of topographies are obtained for the oxygen cuts, and the underlying reason for the different topographies are discussed. The influences of key parameters including power, repetition rate, pulse width, and cutting speed on the cutting quality are analyzed. The present research can also provide an optimization guideline for the micro-profiling of CoCr vascular stents. Full article

(This article belongs to the Section Optics and Lasers)

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11 pages, 1667 KiB

Open AccessArticle

Kinetics Study of Gas Pollutant Adsorption and Thermal Desorption on Silica Gel

by Rong A¹, Meng Liu¹, Liping Pang^1,*, Dongsheng Yang², Jun Wang¹ and Yue Zhou³

¹ School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

² Beijing Spacecrafts, Beijing 100094, China

³ Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration, Nanjing 211102, China

Appl. Sci. 2017, 7(6), 609; https://doi.org/10.3390/app7060609 - 12 Jun 2017

Cited by 8 | Viewed by 5812

Abstract

Silica gel is a typical porous desiccant material. Its adsorption performance for gaseous air pollutants was investigated to determine its potential contribution to reducing such pollutants. Three gaseous air pollutants, toluene, carbon dioxide, and methane, were investigated in this paper. A thermogravimetric analyzer [...] Read more.

Silica gel is a typical porous desiccant material. Its adsorption performance for gaseous air pollutants was investigated to determine its potential contribution to reducing such pollutants. Three gaseous air pollutants, toluene, carbon dioxide, and methane, were investigated in this paper. A thermogravimetric analyzer was used to obtain the equilibrium adsorption capacity of gases on single silica gel particles. The silica gel adsorption capacity for toluene is much higher than that for carbon dioxide and methane. To understand gas pollutant thermal desorption from silica gel, the thermogravimetric analysis of toluene desorption was conducted with 609 ppm toluene vapor at 313 K, 323 K, and 333 K. The overall regeneration rate of silica gel was strongly dependent on temperature and the enthalpy of desorption. The gas pollutant adsorption performance and thermal desorption on silica gel material may be used to estimate the operating and design parameters for gas pollutant adsorption by desiccant wheels. Full article

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

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11 pages, 7373 KiB

Open AccessFeature PaperArticle

Vibro-Acoustic Numerical Analysis for the Chain Cover of a Car Engine

by Enrico Armentani^1,*

, Raffaele Sepe¹, Antonio Parente² and Mauro Pirelli²

¹ Department of Chemical, Materials and Production Engineering University of Naples Federico II, P.le V. Tecchio 80, 80125 Naples, Italy

² Fiat Chrysler Automobiles (FCA) Powertrain S.p.A., via ex Aeroporto, 80038 Pomigliano D’Arco, Italy

Appl. Sci. 2017, 7(6), 610; https://doi.org/10.3390/app7060610 - 12 Jun 2017

Cited by 19 | Viewed by 6879

Abstract

In this work, a vibro-acoustic numerical and experimental analysis was carried out for the chain cover of a low powered four-cylinder four-stroke diesel engine, belonging to the FPT (FCA Power Train) family called SDE (Small Diesel Engine). By applying a methodology used in [...] Read more.

In this work, a vibro-acoustic numerical and experimental analysis was carried out for the chain cover of a low powered four-cylinder four-stroke diesel engine, belonging to the FPT (FCA Power Train) family called SDE (Small Diesel Engine). By applying a methodology used in the acoustic optimization of new FPT engine components, firstly a finite element model (FEM) of the engine was defined, then a vibration analysis was performed for the whole engine (modal analysis), and finally a forced response analysis was developed for the only chain cover (separated from the overall engine). The boundary conditions applied to the chain cover were the accelerations experimentally measured by accelerometers located at the points of connection among chain cover, head cover, and crankcase. Subsequently, a boundary element (BE) model of the only chain cover was realized to determine the chain cover noise emission, starting from the previously calculated structural vibrations. The numerical vibro-acoustic outcomes were compared with those experimentally observed, obtaining a good correlation. All the information thus obtained allowed the identification of those critical areas, in terms of noise generation, in which to undertake necessary improvements. Full article

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

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17 pages, 3476 KiB

Open AccessArticle

Application of Finite Layer Method in Pavement Structural Analysis

by Pengfei Liu¹

, Qinyan Xing²

, Yiyi Dong², Dawei Wang^1,3,*

, Markus Oeser¹ and Si Yuan²

¹ Institute of Highway Engineering, RWTH Aachen University, Mies-van-der-Rohe-Street 1, D52074 Aachen, Germany

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

³ Institute of Highway Engineering, Paul-Bonatz-Street 9–11, University of Siegen, D57076 Siegen, Germany

Appl. Sci. 2017, 7(6), 611; https://doi.org/10.3390/app7060611 - 13 Jun 2017

Cited by 21 | Viewed by 8579

Abstract

The finite element (FE) method has been widely used in predicting the structural responses of asphalt pavements. However, the three-dimensional (3D) modeling in general-purpose FE software systems such as ABAQUS requires extensive computations and is relatively time-consuming. To address this issue, a specific [...] Read more.

The finite element (FE) method has been widely used in predicting the structural responses of asphalt pavements. However, the three-dimensional (3D) modeling in general-purpose FE software systems such as ABAQUS requires extensive computations and is relatively time-consuming. To address this issue, a specific computational code EasyFEM was developed based on the finite layer method (FLM) for analyzing structural responses of asphalt pavements under a static load. Basically, it is a 3D FE code that requires only a one-dimensional (1D) mesh by incorporating analytical methods and using Fourier series in the other two dimensions, which can significantly reduce the computational time and required resources due to the easy implementation of parallel computing technology. Moreover, a newly-developed Element Energy Projection (EEP) method for super-convergent calculations was implemented in EasyFEM to improve the accuracy of solutions for strains and stresses over the whole pavement model. The accuracy of the program is verified by comparing it with results from BISAR and ABAQUS for a typical asphalt pavement structure. The results show that the predicted responses from ABAQUS and EasyFEM are in good agreement with each other. The EasyFEM with the EEP post-processing technique converges faster compared with the results derived from ordinary EasyFEM applications, which proves that the EEP technique can improve the accuracy of strains and stresses from EasyFEM. In summary, the EasyFEM has a potential to provide a flexible and robust platform for the numerical simulation of asphalt pavements and can easily be post-processed with the EEP technique to enhance its advantages. Full article

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

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14 pages, 2857 KiB

Open AccessArticle

Composite Kernel Method for PolSAR Image Classification Based on Polarimetric-Spatial Information

by Xianyuan Wang¹, Zongjie Cao^1,*

, Yao Ding¹ and Jilan Feng²

¹ Center for Information Geoscience, University of Electronic Science and Technology of China, Chengdu 611731, China

² Huiding Technology Co. Ltd., Chengdu 611731, China

Appl. Sci. 2017, 7(6), 612; https://doi.org/10.3390/app7060612 - 13 Jun 2017

Cited by 5 | Viewed by 4725

Abstract

The composite kernel feature fusion proposed in this paper attempts to solve the problem of classifying polarimetric synthetic aperture radar (PolSAR) images. Here, PolSAR images take into account both polarimetric and spatial information. Various polarimetric signatures are collected to form the polarimetric feature [...] Read more.

The composite kernel feature fusion proposed in this paper attempts to solve the problem of classifying polarimetric synthetic aperture radar (PolSAR) images. Here, PolSAR images take into account both polarimetric and spatial information. Various polarimetric signatures are collected to form the polarimetric feature space, and the morphological profile (MP) is used for capturing spatial information and constructing the spatial feature space. The main idea is that the composite kernel method encodes diverse information within a new kernel matrix and tunes the contribution of different types of features. A support vector machine (SVM) is used as the classifier for PolSAR images. The proposed approach is tested on a Flevoland PolSAR data set and a San Francisco Bay data set, which are in fine quad-pol mode. For the Flevoland PolSAR data set, the overall accuracy and kappa coefficient of the proposed method, compared with the traditional method, increased from 95.7% to 96.1% and from 0.920 to 0.942, respectively. For the San Francisco Bay data set, the overall accuracy and kappa coefficient of the proposed method increased from 92.6% to 94.4% and from 0.879 to 0.909, respectively. Experimental results verify the benefits of using both polarimetric and spatial information via composite kernel feature fusion for the classification of PolSAR images. Full article

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

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15 pages, 4102 KiB

Open AccessArticle

Energy Regeneration Hydraulic System via a Relief Valve with Energy Regeneration Unit

by Tianliang Lin¹, Qiang Chen¹, Haoling Ren^1,2,*, Yi Zhao¹, Cheng Miao¹, Shengjie Fu¹ and Qihuai Chen^1,2

¹ College of Mechanical Engineering and Automation, Huaqiao University, Xiamen 361021, China

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

Appl. Sci. 2017, 7(6), 613; https://doi.org/10.3390/app7060613 - 13 Jun 2017

Cited by 17 | Viewed by 6556

Abstract

Relief valves are widely used in industrial machinery. Due to the outlet of the relief valve being connected to the tank, the pressure drop of the relief valve is frequently equal to the inlet pressure. Accordingly, the energy loss of the relief valve [...] Read more.

Relief valves are widely used in industrial machinery. Due to the outlet of the relief valve being connected to the tank, the pressure drop of the relief valve is frequently equal to the inlet pressure. Accordingly, the energy loss of the relief valve is very high in some cases and this will worsen with an increase in the rated pressure of the hydraulic system. In order to overcome the disadvantage of overflow energy loss in a relief valve, a hydraulic energy regeneration unit (HERU) is connected to the outlet of the relief valve to decrease the pressure drop between the inlet and outlet of the relief valve. The overflow loss, which is characterized by the pressure drop, can be reduced accordingly. The approach is to convert the overflow energy loss in hydraulic form and allow for release when needed. The configuration and working principle of the relief valve with HERU is introduced in this present study. The mathematical model is established to obtain the factors influencing the stability of the relief valve. The working pressure of the hydraulic accumulator (HA) is explored. Furthermore, the control process of the operating state of the HA is scheduled to decide whether to regenerate the energy via the HERU. The software AMESim is utilized to analyze the performance and characteristics of the relief valve with HERU. Following this, the test rig is built and used to verify the effectiveness of the proposed relief valve with HERU. The experimental results show that the relief valve with the HERU connected to its outlet can still achieve better pressure-regulating characteristics. The energy regeneration efficiency saved by the HA is up to 83.6%, with a higher pre-charge pressure of the HA. This indicates that the proposed structure of the relief valve with HERU can achieve a better performance and higher regeneration efficiency. Full article

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

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11 pages, 3536 KiB

Open AccessArticle

Terawatt-Isolated Attosecond X-ray Pulse Using a Tapered X-ray Free Electron Laser

by Sandeep Kumar^1,2, Alexandra S. Landsman^2,3 and Dong Eon Kim^1,2,*

¹ Department of Physics, Center for Attosecond Science and Technology, Pohang University of Science and Technology, Pohang 790-784, Korea

² Max Planck Center for Attosecond Science, Pohang 790-784, Korea

³ Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, 01187 Dresden, Germany

Appl. Sci. 2017, 7(6), 614; https://doi.org/10.3390/app7060614 - 13 Jun 2017

Cited by 4 | Viewed by 5226

Abstract

High power attosecond (as) X-ray pulses are in great demand for ultrafast dynamics and high resolution microscopy. We numerically demonstrate the generation of a ~230 attosecond, 1.5 terawatt (TW) pulse at a photon energy of 1 keV, and a 115 attosecond, 1.2 TW [...] Read more.

High power attosecond (as) X-ray pulses are in great demand for ultrafast dynamics and high resolution microscopy. We numerically demonstrate the generation of a ~230 attosecond, 1.5 terawatt (TW) pulse at a photon energy of 1 keV, and a 115 attosecond, 1.2 TW pulse at a photon energy of 12.4 keV, using the realistic electron beam parameters such as those of Korean X-ray free electron laser (XFEL) in a tapered undulator configuration. To compensate the energy loss of the electron beam and maximize its radiation power, a tapering is introduced in the downstream section of the undulator. It is found that the tapering helps in not only amplifying a target radiation pulse but also suppressing the growth of satellite radiation pulses. Tapering allows one to achieve a terawatt-attosecond pulse only with a 60 m long undulator. Such an attosecond X-ray pulse is inherently synchronized to a driving optical laser pulse; hence, it is well suited for the pump-probe experiments for studying the electron dynamics in atoms, molecules, and solids on the attosecond time-scale. For the realization of these experiments, a high level of synchronization up to attosecond precision between optical laser and X-ray pulse is demanded, which can be possible by using an interferometric feedback loop. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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8 pages, 2203 KiB

Open AccessArticle

Non-Pulse-Leakage 100-kHz Level, High Beam Quality Industrial Grade Nd:YVO₄ Picosecond Amplifier

by Zhenao Bai^1,2,3,†, Zhenxu Bai^4,5,†, Zhijun Kang^1,2, Fuqiang Lian^1,2, Weiran Lin^1,2 and Zhongwei Fan^1,2,3,6,*

¹ Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100094, China

² National Engineering Research Center for DPSSL, Beijing 102211, China

³ Sino-HG Applied Laser Technology Institute Company, Ltd., Tianjin 300304, China

⁴ National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001, China

⁵ MQ Photonics Research Centre, Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia

⁶ University of Chinese Academy of Sciences, Beijing 100049, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 615; https://doi.org/10.3390/app7060615 - 14 Jun 2017

Cited by 12 | Viewed by 7029

Abstract

A non-pulse-leakage optical fiber pumped 100-kHz level high beam quality Nd:YVO₄ picosecond amplifier has been developed. An 80 MHz, 11.5 ps mode-locked picosecond laser is used as the seed with single pulse energy of 1 nJ. By harnessing the double β-BaB₂ [...] Read more.

A non-pulse-leakage optical fiber pumped 100-kHz level high beam quality Nd:YVO₄ picosecond amplifier has been developed. An 80 MHz, 11.5 ps mode-locked picosecond laser is used as the seed with single pulse energy of 1 nJ. By harnessing the double β-BaB₂O₄ (BBO) crystal Pockels cells in both the pulse picker and regenerative amplifier, the seed pulse leakage of the output is suppressed effectively with an adjustable repetition rate from 200 to 500 kHz. Through one stage traveling-wave amplifier, a maximum output power of 24.5 W is generated corresponding to the injected regenerative amplified power of 9.73 W at 500 kHz. The output pulse duration is 16.9 ps, and the beam quality factor M² is measured to be 1.25 with near-field roundness higher than 99% at the full output power. Full article

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

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18 pages, 2325 KiB

Open AccessArticle

Smartphones as a Light Measurement Tool: Case of Study

by Jose-Maria Gutierrez-Martinez

, Ana Castillo-Martinez^*

, Jose-Amelio Medina-Merodio

, Juan Aguado-Delgado

and Jose-Javier Martinez-Herraiz

Department of Computer Sciences, Polytechnic School, University of Alcala, 28871 Alcalá de Henares, Spain

Appl. Sci. 2017, 7(6), 616; https://doi.org/10.3390/app7060616 - 14 Jun 2017

Cited by 33 | Viewed by 12175

Abstract

In recent years, smartphones have become the main computing tool for most of the population, making them an ideal tool in many areas. Most of these smartphones are equipped with cutting-edge hardware on their digital cameras, sensors and processors. For this reason, this [...] Read more.

In recent years, smartphones have become the main computing tool for most of the population, making them an ideal tool in many areas. Most of these smartphones are equipped with cutting-edge hardware on their digital cameras, sensors and processors. For this reason, this paper discusses the possibility of using smartphones as an accessible and accurate tool, focusing on the measurement of light, which is an element that has a high impact on human behavior, which promotes conformance and safety, or alters human physiology when it is inappropriate. To carry out this study, three different ways to measure light through smartphones have been checked: the ambient light sensor, the digital camera and an external Bluetooth luxmeter connected with the smartphone. As a result, the accuracy of these methods has been compared to check if they can be used as accurate measurement tools. Full article

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15 pages, 5945 KiB

Open AccessArticle

Synthesis and Biophysical Insights into the Binding of a Potent Anti-Proliferative Non-symmetric Bis-isatin Derivative with Bovine Serum Albumin: Spectroscopic and Molecular Docking Approaches

by Ali Saber Abdelhameed^1,*

, Ahmed H. Bakheit¹

, Mostafa S. Mohamed¹, Wagdy M. Eldehna²

, Hatem A. Abdel-Aziz³

and Mohamed I. Attia^1,4,*

¹ Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia

² Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Kafrelsheikh University, Kafrelsheikh 33516, Egypt

³ Department of Applied Organic Chemistry, National Research Centre, Dokki, Giza 12622, Egypt

⁴ Medicinal and Pharmaceutical Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Giza 12622, Egypt

Appl. Sci. 2017, 7(6), 617; https://doi.org/10.3390/app7060617 - 14 Jun 2017

Cited by 21 | Viewed by 4708

Abstract

As part of the research endeavors to combat cancer, a non-symmetric bis-isatin derivative (compound 3) was synthesized and showed a significant anti-proliferative potency. The current study provides a comprehensive characterization of the interaction of compound 3 with the drug-transporting protein bovine serum [...] Read more.

As part of the research endeavors to combat cancer, a non-symmetric bis-isatin derivative (compound 3) was synthesized and showed a significant anti-proliferative potency. The current study provides a comprehensive characterization of the interaction of compound 3 with the drug-transporting protein bovine serum albumin (BSA) via the use of spectroscopic tools along with molecular docking studies. Fluorescence spectral measurements showed that the BSA intrinsic fluorescence can be significantly quenched by the addition of compound 3 and the formation of a non-fluorescent complex. Further measurements revealed a static type of quenching with Stern–Volmer and Linweaver–Burk constants of 10⁵. The thermodynamic parameters of the binding were calculated to be ΔS° 105.09 ± 5.32 with ΔH° of −0.72 ± 0.71 and negative ΔG° values. In addition, synchronous fluorescence and 3D fluorescence spectroscopy suggested that compound 3 did not induce conformational changes in BSA. Site competition experiments revealed that compound 3 competes with warfarin within the BSA binding domain (Sudlow site I). This was further confirmed by the molecular docking results showing a binding energy of −25.93 kJ/mol for compound 3-BSA. Hence, the observed results in the present study assumed that the compound 3-BSA binding is spontaneous, involving electrostatic forces and hydrogen bonding. Full article

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

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11 pages, 1122 KiB

Open AccessFeature PaperArticle

Iridescent Perfect Absorption in Critically-Coupled Acoustic Metamaterials Using the Transfer Matrix Method

by Noé Jiménez^*

, Jean-Philippe Groby, Vincent Pagneux and Vicent Romero-García

Laboratoire d’Acoustique de l’Université du Maine (LAUM)-CNRS UMR 6613, Av. Olivier Messiaen, 72085 Le Mans, France

Appl. Sci. 2017, 7(6), 618; https://doi.org/10.3390/app7060618 - 14 Jun 2017

Cited by 23 | Viewed by 6359

Abstract

The absorption performance of a locally-reacting acoustic metamaterial under oblique incidence is studied. The metamaterial is composed of a slotted panel, each slit being loaded by an array of Helmholtz resonators. The system is analytically studied using the transfer matrix method, accounting for [...] Read more.

The absorption performance of a locally-reacting acoustic metamaterial under oblique incidence is studied. The metamaterial is composed of a slotted panel, each slit being loaded by an array of Helmholtz resonators. The system is analytically studied using the transfer matrix method, accounting for the viscothermal losses both in the resonator elements and in the slits, allowing the representation of the reflection coefficient in the complex frequency plane. We show that by tuning the geometry of the metamaterial, perfect absorption peaks can be obtained on demand at selected frequencies and different angles of incidence. When tilting the incidence angle, the peaks of perfect absorption are shifted in frequency, producing an acoustic iridescence effect similar to the optic iridescence achieved by incomplete band gap. Effectively, we show that in this kind of locally-reacting metamaterial, perfect and omnidirectional absorption for a given frequency is impossible to achieve because the metamaterial impedance does not depend on the incidence angle (i.e., the impedance is a locally reacting one). The system is interpreted in the complex frequency plane by analysing the trajectories of the zeros of the reflection coefficient. We show that the trajectories of the zeros do not overlap under oblique incidence, preventing the observation of perfect and omnidirectional absorption in locally reacting metamaterials. Moreover, we show that for any locally resonant material, the absorption in diffuse field takes a maximal value of 0.951, which is achieved by a material showing perfect absorption for an incidence angle of 50.34 degrees. Full article

(This article belongs to the Section Acoustics and Vibrations)

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17 pages, 10063 KiB

Open AccessArticle

Simulation Investigation on Combustion Characteristics in a Four-Point Lean Direct Injection Combustor with Hydrogen/Air

by Jianzhong Li^1,*, Li Yuan² and Hukam C. Mongia³

¹ Key Laboratory of Aero-engine Thermal Environment and Structure, Ministry of Industry and Information Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

² School of National Defense Engineering, PLA University of Science and Technology, 88 Biaoying Rd., Nanjing 210007, China

³ School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088, USA

Appl. Sci. 2017, 7(6), 619; https://doi.org/10.3390/app7060619 - 14 Jun 2017

Cited by 14 | Viewed by 8334

Abstract

To investigate the combustion characteristics in multi-point lean direct injection (LDI) combustors with hydrogen/air, two swirl–venturi 2 × 2 array four-point LDI combustors were designed. The four-point LDI combustor consists of injector assembly, swirl–venturi array and combustion chamber. The injector, swirler and venturi [...] Read more.

To investigate the combustion characteristics in multi-point lean direct injection (LDI) combustors with hydrogen/air, two swirl–venturi 2 × 2 array four-point LDI combustors were designed. The four-point LDI combustor consists of injector assembly, swirl–venturi array and combustion chamber. The injector, swirler and venturi together govern the rapid mixing of hydrogen and air to form the mixture for combustion. Using clockwise swirlers and anticlockwise swirlers, the co-swirling and count-swirling swirler arrays LDI combustors were achieved. Using Reynolds-Averaged Navier–Stokes (RANS) code for steady-state reacting flow computations, the four-point LDI combustors with hydrogen/air were simulated with an 11 species and 23 lumped reaction steps H₂/Air reaction mechanism. The axial velocity, turbulence kinetic energy, total pressure drop coefficient, outlet temperature, mass fraction of OH and emission of pollutant NO of four-point LDI combustors, with different equivalence ratios, are here presented and discussed. As the equivalence ratios increased, the total pressure drop coefficient became higher because of increasing heat loss. Increasing equivalence ratios also corresponded with the rise in outlet temperature of the four-point LDI combustors, as well as an increase in the emission index of NO EI_NO in the four-point LDI combustors. Along the axial distance, the EI_NO always increased and was at maximum at the exit of the dump. Along the chamber, the EI_NO gradually increased, maximizing at the exit of chamber. The total temperature of four-point LDI combustors with different equivalence ratios was identical to the theoretical equilibrium temperature. The EI_NO was an exponential function of the equivalence ratio. Full article

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

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13 pages, 5667 KiB

Open AccessArticle

Experimental Investigations of Composite Adsorbent 13X/CaCl₂ on an Adsorption Cooling System

by Huizhong Zhao^1,*

, Shaolong Jia¹, Junfeng Cheng¹, Xianghu Tang¹, Min Zhang², Haoxin Yan¹ and Wenting Ai²

¹ Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China

² College of Food Science and Technology, Shanghai Ocean University, Shanghai 201306, China

Appl. Sci. 2017, 7(6), 620; https://doi.org/10.3390/app7060620 - 14 Jun 2017

Cited by 15 | Viewed by 4875

Abstract

A new experimental device which tests the adsorption performance of the 13X/CaCl₂ composite adsorbent under vacuum conditions was established. In this device, heat transfer characteristics in the adsorbent bed have a great influence on the adsorbent performance, the temperature of the bottom [...] Read more.

A new experimental device which tests the adsorption performance of the 13X/CaCl₂ composite adsorbent under vacuum conditions was established. In this device, heat transfer characteristics in the adsorbent bed have a great influence on the adsorbent performance, the temperature of the bottom outside bed is very close to the temperature of the bottom inside bed and the temperature difference between them at the end of heating and cooling are 5.66 °C and 0.303 °C, respectively. The following conclusions could be drawn: the equilibrium water uptake of composite adsorbent CA10X (zeolite 13X impregnated with 10 wt % CaCl₂ solution) was increased 5.7% compared with that of 13X, and the water uptake was 0.37 g/g. The composite adsorbent CA10X has a better performance in the adsorption refrigeration system. Full article

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

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9 pages, 419 KiB

Open AccessArticle

Application of Matched-Filter Concepts to Unbiased Selection of Data in Pump-Probe Experiments with Free Electron Lasers

by Carlo Callegari^1,2,*,†, Tsukasa Takanashi^3,†, Hironobu Fukuzawa³, Koji Motomura^3,‡, Denys Iablonskyi³, Yoshiaki Kumagai^3,§, Subhendu Mondal³, Tetsuya Tachibana³, Kiyonobu Nagaya⁴, Toshiyuki Nishiyama⁴, Kenji Matsunami⁴, Per Johnsson⁵, Paolo Piseri⁶, Giuseppe Sansone^7,8, Antoine Dubrouil^7,‖, Maurizio Reduzzi⁷, Paolo Carpeggiani⁷, Caterina Vozzi⁷, Michele Devetta⁷

, Davide Faccialà⁷, Francesca Calegari^7,9, Mattea Carmen Castrovilli⁷, Marcello Coreno^1,2, Michele Alagia¹⁰, Bernd Schütte¹¹, Nora Berrah¹², Oksana Plekan¹, Paola Finetti¹, Eugenio Ferrari^1,¶, Kevin Charles Prince^1,10 and Kiyoshi Ueda³ Show full author list Hide full author list

¹ Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14–km 163.5 in Area Science Park, 34149 Basovizza, Trieste, Italy

² CNR-ISM, Area Science Park, 34149 Basovizza, Trieste, Italy

³ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan

⁴ Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan

⁵ Department of Physics, Lund University, P.O. Box 118, 22100 Lund, Sweden

⁶ CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy

⁷ CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

⁸ Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany

⁹ Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany

¹⁰ CNR-IOM, Area Science Park, 34149 Basovizza, Trieste, Italy

¹¹ Max-Born-Institut, Max-Born-Strasse 2 A, 12489 Berlin, Germany

¹² Department of Physics, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269, USA

^† These authors contributed equally to this work.

^‡ Current address: RIKEN SPring-8 Center, Kouto, Sayo, Hyogo 679-5148, Japan.

^§ Current address: Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA.

^‖ Current address: Femto Easy, Parc scientifique Laseris 1, 33114 Le Barp, France.

^¶ Current address: Particle Accelerator Physics Laboratory, École Polytechnique Fédérale de Lausanne EPFL, CH-1015 Lausanne, Switzerland.

Show full affiliation list Hide full affiliation list

Appl. Sci. 2017, 7(6), 621; https://doi.org/10.3390/app7060621 - 16 Jun 2017

Cited by 2 | Viewed by 5165

Abstract

Pump-probe experiments are commonly used at Free Electron Lasers (FEL) to elucidate the femtosecond dynamics of atoms, molecules, clusters, liquids and solids. Maximizing the signal-to-noise ratio of the measurements is often a primary need of the experiment, and the aggregation of repeated, rapid, [...] Read more.

Pump-probe experiments are commonly used at Free Electron Lasers (FEL) to elucidate the femtosecond dynamics of atoms, molecules, clusters, liquids and solids. Maximizing the signal-to-noise ratio of the measurements is often a primary need of the experiment, and the aggregation of repeated, rapid, scans of the pump-probe delay is preferable to a single long-lasting scan. The limited availability of beamtime makes it impractical to repeat measurements indiscriminately, and the large, rapid flow of single-shot data that need to be processed and aggregated into a dataset, makes it difficult to assess the quality of a measurement in real time. In post-analysis it is then necessary to devise unbiased criteria to select or reject datasets, and to assign the weight with which they enter the analysis. One such case was the measurement of the lifetime of Intermolecular Coulombic Decay in the weakly-bound neon dimer. We report on the method we used to accomplish this goal for the pump-probe delay scans that constitute the core of the measurement; namely we report on the use of simple auto- and cross-correlation techniques based on the general concept of “matched filter”. We are able to unambiguously assess the signal-to-noise ratio (SNR) of each scan, which then becomes the weight with which a scan enters the average of multiple scans. We also observe a clear gap in the values of SNR, and we discard all the scans below a SNR of 0.45. We are able to generate an average delay scan profile, suitable for further analysis: in our previous work we used it for comparison with theory. Here we argue that the method is sufficiently simple and devoid of human action to be applicable not only in post-analysis, but also for the real-time assessment of the quality of a dataset. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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13 pages, 2790 KiB

Open AccessArticle

ANN Sizing Procedure for the Day-Ahead Output Power Forecast of a PV Plant

by Francesco Grimaccia

, Sonia Leva

, Marco Mussetta

and Emanuele Ogliari^*

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

Appl. Sci. 2017, 7(6), 622; https://doi.org/10.3390/app7060622 - 15 Jun 2017

Cited by 50 | Viewed by 6093

Abstract

Since the beginning of this century, the share of renewables in Europe’s total power capacity has almost doubled, becoming the largest source of its electricity production. In 2015 alone, photovoltaic (PV) energy generation rose with a rate of more than 5%; nowadays, Germany, [...] Read more.

Since the beginning of this century, the share of renewables in Europe’s total power capacity has almost doubled, becoming the largest source of its electricity production. In 2015 alone, photovoltaic (PV) energy generation rose with a rate of more than 5%; nowadays, Germany, Italy, and Spain account together for almost 70% of total European PV generation. In this context, the so-called day-ahead electricity market represents a key trading platform, where prices and exchanged hourly quantities of energy are defined 24 h in advance. Thus, PV power forecasting in an open energy market can greatly benefit from machine learning techniques. In this study, the authors propose a general procedure to set up the main parameters of hybrid artificial neural networks (ANNs) in terms of the number of neurons, layout, and multiple trials. Numerical simulations on real PV plant data are performed, to assess the effectiveness of the proposed methodology on the basis of statistical indexes, and to optimize the forecasting network performance. Full article

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

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17 pages, 5705 KiB

Open AccessFeature PaperArticle

Combined CFD-Stochastic Analysis of an Active Fluidic Injection System for Jet Noise Reduction

by Mattia Barbarino^1,*, Mario Ilsami², Raffaele Tuccillo² and Luigi Federico¹

¹ Department of Air Transport Environmental Impact, Italian Aerospace Research Center (CIRA), 81043 Capua, Italy

² Department of Industrial Engineering, University of Naples “Federico II”, 80138 Naples, Italy

Appl. Sci. 2017, 7(6), 623; https://doi.org/10.3390/app7060623 - 16 Jun 2017

Cited by 12 | Viewed by 6575

Abstract

In the framework of DANTE project (Development of Aero-Vibroacoustics Numerical and Technical Expertise), funded under the Italian Aerospace Research Program (PRORA), the prediction and reduction of noise from subsonic jets through the reconstruction of turbulent fields from Reynolds Averaged Navier Stokes (RANS) calculations [...] Read more.

In the framework of DANTE project (Development of Aero-Vibroacoustics Numerical and Technical Expertise), funded under the Italian Aerospace Research Program (PRORA), the prediction and reduction of noise from subsonic jets through the reconstruction of turbulent fields from Reynolds Averaged Navier Stokes (RANS) calculations are addressed. This approach, known as Stochastic Noise Generation and Radiation (SNGR), reconstructs the turbulent velocity fluctuations by RANS fields and calculates the source terms of Vortex Sound acoustic analogy. In the first part of this work, numerical and experimental jet-noise test cases have been reproduced by means RANS simulations and with different turbulence models in order to validate the approach for its subsequent use as a design tool. The noise spectra, predicted with SNGR, are in good agreement with both the experimental data and the results of Large-Eddy Simulations (LES). In the last part of this work, an active fluid injection technique, based on extractions from turbine and injections of high-pressure gas into the main stream of exhausts, has been proposed and finally assessed with the aim of reducing the jet-noise through the mixing and breaking of the turbulent eddies. Some tests have been carried out in order to set the best design parameters in terms of mass flow rate and injection velocity and to design the system functionalities. The SNGR method is, therefore, suitable to be used for the early design phase of jet-noise reduction technologies and a right combination of the fluid injection design parameters allows for a reduction of the jet-noise to 3.5 dB, as compared to the baseline case without injections. Full article

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

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14 pages, 1718 KiB

Open AccessArticle

Efficiency Evaluation of Operation Analysis Systems Based on Dynamic Data Envelope Analysis Models from a Big Data Perspective

by Yixin Sun^1,2, Xiaobao Yu^1,*, Zhongfu Tan^1,3, Xiaofei Xu⁴ and Qingyou Yan¹

¹ School of Economics and Management, North China Electric Power University, Beijing 102206, China

² State Grid Energy Research Institute, Beijing 102209, China

³ Department of Economics and Management, Yan’an University, Shanxi 716000, China

⁴ Deltac Energy Technology Co. Ltd., Beijing 100084, China

Appl. Sci. 2017, 7(6), 624; https://doi.org/10.3390/app7060624 - 16 Jun 2017

Cited by 13 | Viewed by 4787

Abstract

The operating environment of power grid enterprises is complex with a range of monitoring indicators. To grasp the overall operational status in time and find the key affecting factors, Balanced Scorecard Card (BSC), Interpretive Structural Model (ISM), Principal component analysis (PCA) should be [...] Read more.

The operating environment of power grid enterprises is complex with a range of monitoring indicators. To grasp the overall operational status in time and find the key affecting factors, Balanced Scorecard Card (BSC), Interpretive Structural Model (ISM), Principal component analysis (PCA) should be applied. This paper proposed several grid enterprise operators and monitoring indicator systems (which include achievement indicators and driver indicators), and applied PCA for verification and evaluation. The achievement indicators mainly reflected the effectiveness of business operations, which included corporate value, social value, customer value, and so on. Driver indicators mainly reflected the core resources and operations process management of business operations, which have a direct impact on the achievement indicators. The driver and achievement indicators were used as input and output indicators for the provinces to assess the efficiency of operations, and appropriate measures were proposed for improvement. The results showed that the dynamic data envelopment analysis (DEA) model could reflect the time lag of the grid enterprises operating investment and income much better than the other two methods, and the static changes compared to assess efficiency had an average around 4%. Full article

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

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12 pages, 992 KiB

Open AccessArticle

Large Earthquake Magnitude Prediction in Chile with Imbalanced Classifiers and Ensemble Learning

by Manuel Jesús Fernández-Gómez, Gualberto Asencio-Cortés

, Alicia Troncoso

and Francisco Martínez-Álvarez^*

Division of Computer Science, Pablo de Olavide University, Seville ES-41013, Spain

Appl. Sci. 2017, 7(6), 625; https://doi.org/10.3390/app7060625 - 16 Jun 2017

Cited by 23 | Viewed by 5269

Abstract

This work presents a novel methodology to predict large magnitude earthquakes with horizon of prediction of five days. For the first time, imbalanced classification techniques are applied in this field by attempting to deal with the infrequent occurrence of such events. So far, [...] Read more.

This work presents a novel methodology to predict large magnitude earthquakes with horizon of prediction of five days. For the first time, imbalanced classification techniques are applied in this field by attempting to deal with the infrequent occurrence of such events. So far, classical classifiers were not able to properly mine these kind of datasets and, for this reason, most of the methods reported in the literature were only focused on moderate magnitude prediction. As an additional step, outputs from different algorithms are combined by applying ensemble learning. Since false positives are quite undesirable in this field, due to the social impact that they might cause, ensembles have been designed in order to reduce these situations. The methodology has been tested on different cities of Chile, showing very promising results in terms of accuracy. Full article

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18 pages, 5265 KiB

Open AccessArticle

A Wireless Sensor Network Using GNSS Receivers for a Short-Term Assessment of the Modal Properties of the Neckartal Bridge

by Timo Kumberg^1,*

, Sascha Schneid² and Leonhard Reindl¹

¹ Laboratory for Electrical Instrumentation, Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany

² VMT GmbH Stegwiesenstr. 24, 76646 Bruchsal, Germany

Appl. Sci. 2017, 7(6), 626; https://doi.org/10.3390/app7060626 - 16 Jun 2017

Cited by 21 | Viewed by 5826

Abstract

In this article, we present a novel structural health monitoring system based on a wireless sensor network for GNSS (global navigation satellite system) receivers. The GNSS network presented here consists of three GNSS rover stations and one base station that are deployed at [...] Read more.

In this article, we present a novel structural health monitoring system based on a wireless sensor network for GNSS (global navigation satellite system) receivers. The GNSS network presented here consists of three GNSS rover stations and one base station that are deployed at the Neckartal bridge on the Autobahn A81 in southwest Germany. The newly-developed GNSS sensor nodes support satellite data logging up to a sampling rate of 20 Hz. Due to the ultra-low-power consumption achieved by the wake-up receiver during inactive periods, the nodes offer a lifetime from 20 to almost 200 days, without energy harvesting and depending on the satellite data logging period. By performing differential post-processing, precise positioning information in the millimeter range could be achieved. Using the GNSS sensors, we determined resonant frequencies at 0.33 Hz and 1.31 Hz, mainly in the lateral direction of the bridge. To verify the GNSS results, we placed an accelerometer on the bridge. The frequencies detected by the acceleration sensor correspond well to the frequencies found by the GNSS sensors, although the accelerometer measured further higher frequencies as it is probably more sensitive to small amplitudes. Full article

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

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22 pages, 2430 KiB

Open AccessFeature PaperReview

Spatial Audio for Soundscape Design: Recording and Reproduction

by Joo Young Hong^1,*

, Jianjun He²

, Bhan Lam¹

, Rishabh Gupta¹ and Woon-Seng Gan¹

¹ School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

² Maxim Integrated Products Inc., San Jose, CA 95129, USA

Appl. Sci. 2017, 7(6), 627; https://doi.org/10.3390/app7060627 - 16 Jun 2017

Cited by 95 | Viewed by 21698

Abstract

With the advancement of spatial audio technologies, in both recording and reproduction, we are seeing more applications that incorporate 3D sound to create an immersive aural experience. Soundscape design and evaluation for urban planning can now tap into the extensive spatial audio tools [...] Read more.

With the advancement of spatial audio technologies, in both recording and reproduction, we are seeing more applications that incorporate 3D sound to create an immersive aural experience. Soundscape design and evaluation for urban planning can now tap into the extensive spatial audio tools for sound capture and 3D sound rendering over headphones and speaker arrays. In this paper, we outline a list of available state-of-the-art spatial audio recording techniques and devices, spatial audio physical and perceptual reproduction techniques, emerging spatial audio techniques for virtual and augmented reality, followed by a discussion on the degree of perceptual accuracy of recording and reproduction techniques in representing the acoustic environment. Full article

(This article belongs to the Special Issue Spatial Audio)

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14 pages, 3253 KiB

Open AccessArticle

Entropy Analysis for Damage Quantification of Hysteretic Dampers Used as Seismic Protection of Buildings

by Elisabet Suarez^1,*

, Andrés Roldán²

, Antolino Gallego¹ and Amadeo Benavent-Climent³

¹ Department of Applied Physics, University of Granada, 18071 Granada, Spain

² Department of Electronics and Computing Science, University of Granada, 18071 Granada, Spain

³ Department of Mechanical Engineering, Technical University of Madrid, 28006 Madrid, Spain

Appl. Sci. 2017, 7(6), 628; https://doi.org/10.3390/app7060628 - 17 Jun 2017

Cited by 13 | Viewed by 5759

Abstract

Relative wavelet energy entropy (RWEE) is proposed to detect and quantify damage to hysteretic dampers used for the passive seismic control of building structures. Hysteretic dampers have the role of dissipating most of the energy input of an earthquake. Minor or moderate earthquakes [...] Read more.

Relative wavelet energy entropy (RWEE) is proposed to detect and quantify damage to hysteretic dampers used for the passive seismic control of building structures. Hysteretic dampers have the role of dissipating most of the energy input of an earthquake. Minor or moderate earthquakes do not exhaust the energy dissipation capacity of the dampers, yet they damage them. For this reason, continuous or periodic damper-health evaluation is required to decide if they need to be replaced. Such evaluation calls for the application of efficient structural health monitoring techniques (SHM). This paper focuses on the well-known vibration technique, which is applied to a particular type of hysteretic damper called Web Plastifying Damper (WPD), patented by the University of Granada. Vibration signals, properly recorded by piezoelectric sensors attached around the damaged area of the dampers, are decomposed by means of wavelet packet analysis. Then, the relative wavelet energy entropy of these decompositions is used to calculate the proposed index. Validation of RWEE for this particular application involved dampers installed in two different specimens of reinforced concrete structures subjected to earthquake sequences of increasing intensity. When compared with a well-established mechanical energy-based damage index, results demonstrate that RWEE is a successful and low-cost technique for reliable in-situ monitoring of dampers. Full article

(This article belongs to the Section Mechanical Engineering)

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19 pages, 4848 KiB

Open AccessArticle

Experimental Study and Numerical Simulation of a Laminated Reinforced Concrete Shear Wall with a Vertical Seam

by Jianbao Li, Yan Wang, Zheng Lu^*

and Junzuo Li

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

Appl. Sci. 2017, 7(6), 629; https://doi.org/10.3390/app7060629 - 17 Jun 2017

Cited by 49 | Viewed by 7542

Abstract

In this paper, 12 laminated reinforced concrete shear walls are designed for cyclic loading tests. Seismic performance of laminated reinforced concrete shear walls with vertical seams are evaluated by the failure mode, deformability, hysteresis curve, stiffness degradation, and energy dissipation capacity. In addition, [...] Read more.

In this paper, 12 laminated reinforced concrete shear walls are designed for cyclic loading tests. Seismic performance of laminated reinforced concrete shear walls with vertical seams are evaluated by the failure mode, deformability, hysteresis curve, stiffness degradation, and energy dissipation capacity. In addition, two different construction measures and construction techniques are designed to study their influence on the wall behavior, which provides a reference for the construction of laminated reinforced concrete shear walls. The numerical simulation of the specimen is carried out with ABAQUS, which is in good agreement with the experimental results. These results provide a technical basis for the design, application, and construction of the laminated reinforced concrete shear wall structure. Full article

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

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11 pages, 5789 KiB

Open AccessArticle

Comparative Study of Stator Configurations of a Permanent Magnet Linear Oscillating Actuator for Orbital Friction Vibration Actuator

by Jianhui Hu^*, Meng Zhao, Jibin Zou and Yong Li

School of Electrical Engineering and Automation, Harbin Institute of Technology, 150006, China

Appl. Sci. 2017, 7(6), 630; https://doi.org/10.3390/app7060630 - 17 Jun 2017

Cited by 5 | Viewed by 4199

Abstract

A PM orbital friction vibration actuator (OFVA) which composes four linear oscillating actuators (LOA) is proposed in this paper. This paper presents the design, analysis, and experimental validation of stator configuration of a permanent magnet LOA to improve its thrust force characteristics. First, [...] Read more.

A PM orbital friction vibration actuator (OFVA) which composes four linear oscillating actuators (LOA) is proposed in this paper. This paper presents the design, analysis, and experimental validation of stator configuration of a permanent magnet LOA to improve its thrust force characteristics. First, the magnetized topology and the coil configuration are interpreted. The optimization design goal of the LOA was established and the end effects of the actuator are illustrated. The influences of stator design parameters on the performance of LOA were investigated and the optimal parameters have been identified with reference to the thrust force density and thrust force ripple. Results showed that a quasi‐Halbach magnetized E‐cored LOA with obtrapezoid teeth has the best electromagnetic performances of all the LOAs examined here. Finally, the predicted thrust force characteristics were validated by measurements on a prototype actuator. Full article

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8 pages, 2276 KiB

Open AccessArticle

Demonstration of High-Speed Optical Transmission at 2 µm in Titanium Dioxide Waveguides

by Manon Lamy, Christophe Finot

, Julien Fatome, Juan Arocas, Jean-Claude Weeber and Kamal Hammani^*

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

Appl. Sci. 2017, 7(6), 631; https://doi.org/10.3390/app7060631 - 17 Jun 2017

Cited by 23 | Viewed by 5501

Abstract

We demonstrate the transmission of a 10-Gbit/s optical data signal in the 2 µm waveband into titanium dioxide waveguides. Error-free transmissions have been experimentally achieved taking advantage of a 23-dB insertion loss fiber-to-fiber grating-based injection test-bed platform. Full article

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

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13 pages, 739 KiB

Open AccessArticle

Supercritical Transesterification of Waste Vegetable Oil: Characteristic Comparison of Ethanol and Methanol as Solvents

by Sujeeta Karki¹, Nawaraj Sanjel², Jeeban Poudel³

, Ja Hyung Choi¹ and Sea Cheon Oh^1,*

¹ Department of Environmental Engineering, Kongju National University, 1223-24 Cheonan-Daero, Seobuk, Chungnam 31080, Korea

² Energize Nepal Programme, Kathmandu University, Dhulikhel 45200, Nepal

³ Waste & Biomass Energy Technology Center, Kongju National University, 1223-24 Cheonan-Daero, Seobuk, Chungnam 31080, Korea

Appl. Sci. 2017, 7(6), 632; https://doi.org/10.3390/app7060632 - 17 Jun 2017

Cited by 24 | Viewed by 7615

Abstract

Transesterification of waste vegetable oil is one of the promising partial substitutes for fossil fuels. The degradation characteristics of waste vegetable oil using supercritical alcohols (ethanol and methanol) have been studied in this research. The elementary target was to conduct comparative analysis of [...] Read more.

Transesterification of waste vegetable oil is one of the promising partial substitutes for fossil fuels. The degradation characteristics of waste vegetable oil using supercritical alcohols (ethanol and methanol) have been studied in this research. The elementary target was to conduct comparative analysis of the effect of supercritical methanol and supercritical ethanol as solvents on the transesterification along with the analysis of product obtained in terms of carbon number. The experiments were carried out at transesterification temperatures of 250, 270 and 290 °C, retention time of 0 to 60 min at an interval of 15 min and oil to alcohol molar ratios of 1:6, 1:12 and 1:18 for both alcohols. The conversion increased with increase in transesterification temperature and retention time. At 290 °C, almost 99% conversion was achieved for 60-min holding time for both alcohols. Increase in conversion of waste vegetable oil was observed as the molar ratio increased. Supercritical transesterification resulted into ester yield higher than 95% with non-ester composition and glycerol collectively less than 5%. Full article

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

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13 pages, 6411 KiB

Open AccessArticle

Experimental Investigation on the Effects of DBD Plasma on the Film Cooling Effectiveness of a 30-Degree Slot

by Ye Jee Kim¹, Gi Mun Kim¹, Youhwan Shin² and Jae Su Kwak^1,*

¹ School of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang 10417, Korea

² Center for Urban Energy Research, Korea Institute of Science and Technology, Seoul 02792, Korea

Appl. Sci. 2017, 7(6), 633; https://doi.org/10.3390/app7060633 - 19 Jun 2017

Cited by 5 | Viewed by 4721

Abstract

The effects of dielectric barrier discharge (DBD) plasma on the film cooling effectiveness of a 30-degree slot was experimentally investigated in a low-speed wind tunnel. The pressure sensitive paint (PSP) technique was used to measure the film cooling effectiveness, and two blowing ratios [...] Read more.

The effects of dielectric barrier discharge (DBD) plasma on the film cooling effectiveness of a 30-degree slot was experimentally investigated in a low-speed wind tunnel. The pressure sensitive paint (PSP) technique was used to measure the film cooling effectiveness, and two blowing ratios (0.5 and 1.0) were tested. A sinusoidal waveform with a 1-kHz frequency was supplied to the exposed electrode. Two input voltages (6 and 7 kV) and two exposed electrode locations were considered. The results showed that the film cooling effectiveness of the slot was higher for the blowing ratio of the 1.0 case than that for the blowing ratio of the 0.5 case regardless of plasma operation. The higher input voltage case (7 kV) showed higher film cooling effectiveness than the lower input voltage case (6 kV). The improvement in film cooling effectiveness facilitated by the DBD plasma was more significant when the coolant had less momentum. The maximum improvement of the area averaged film cooling effectiveness was 2.3% for the case with the exposed electrode located at the slot exit and a blowing ratio of 0.5. Full article

(This article belongs to the Special Issue Advances in Thermal System Analysis and Optimization)

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12 pages, 5116 KiB

Open AccessArticle

Optimized Design of Thermoelectric Energy Harvesting Systems for Waste Heat Recovery from Exhaust Pipes

by Marco Nesarajah^* and Georg Frey

Chair of Automation and Energy Systems, Saarland University, Campus A5 1, 66123 Saarbruecken, Germany

Appl. Sci. 2017, 7(6), 634; https://doi.org/10.3390/app7060634 - 19 Jun 2017

Cited by 22 | Viewed by 7767

Abstract

With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert [...] Read more.

With the increasing interest in energy efficiency and resource protection, waste heat recovery processes have gained importance. Thereby, one possibility is the conversion of the heat energy into electrical energy by thermoelectric generators. Here, a thermoelectric energy harvesting system is developed to convert the waste heat from exhaust pipes, which are very often used to transport the heat, e.g., in automobiles, in industrial facilities or in heating systems. That is why a mockup of a heating is built-up, and the developed energy harvesting system is attached. To build-up this system, a model-based development process is used. The setup of the developed energy harvesting system is very flexible to test different variants and an optimized system can be found in order to increase the energy yield for concrete application examples. A corresponding simulation model is also presented, based on previously developed libraries in Modelica^®/Dymola^®. In the end, it can be shown—with measurement and simulation results—that a thermoelectric energy harvesting system on the exhaust pipe of a heating system delivers extra energy and thus delivers a contribution for a more efficient usage of the inserted primary energy carrier. Full article

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

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22 pages, 3704 KiB

Open AccessFeature PaperReview

Soliton Content of Fiber-Optic Light Pulses

by Fedor Mitschke^*,†, Christoph Mahnke^† and Alexander Hause^†

¹ Institut für Physik, Universität Rostock, A.-Einstein-Str. 23, 18059 Rostock, Germany

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(6), 635; https://doi.org/10.3390/app7060635 - 19 Jun 2017

Cited by 26 | Viewed by 9522

Abstract

This is a review of fiber-optic soliton propagation and of methods to determine the soliton content in a pulse, group of pulses or a similar structure. Of central importance is the nonlinear Schrödinger equation, an integrable equation that possesses soliton solutions, among others. [...] Read more.

This is a review of fiber-optic soliton propagation and of methods to determine the soliton content in a pulse, group of pulses or a similar structure. Of central importance is the nonlinear Schrödinger equation, an integrable equation that possesses soliton solutions, among others. Several extensions and generalizations of this equation are customary to better approximate real-world systems, but this comes at the expense of losing integrability. Depending on the experimental situation under discussion, a variety of pulse shapes or pulse groups can arise. In each case, the structure will contain one or several solitons plus small amplitude radiation. Direct scattering transform, also known as nonlinear Fourier transform, serves to quantify the soliton content in a given pulse structure, but it relies on integrability. Soliton radiation beat analysis does not suffer from this restriction, but has other limitations. The relative advantages and disadvantages of the methods are compared. Full article

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

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16 pages, 927 KiB

Open AccessArticle

Random Forest Prediction of IPO Underpricing

by David Quintana^*

, Yago Sáez and Pedro Isasi

Department of Computer Science and Engineering, Universidad Carlos III de Madrid, 28903 Madrid, Spain

Appl. Sci. 2017, 7(6), 636; https://doi.org/10.3390/app7060636 - 20 Jun 2017

Cited by 27 | Viewed by 7179

Abstract

The prediction of initial returns on initial public offerings (IPOs) is a complex matter. The independent variables identified in the literature mix strong and weak predictors, their explanatory power is limited, and samples include a sizable number of outliers. In this context, we [...] Read more.

The prediction of initial returns on initial public offerings (IPOs) is a complex matter. The independent variables identified in the literature mix strong and weak predictors, their explanatory power is limited, and samples include a sizable number of outliers. In this context, we suggest that random forests are a potentially powerful tool. In this paper, we benchmark this algorithm against a set of eight classic machine learning algorithms. The results of this comparison show that random forests outperform the alternatives in terms of mean and median predictive accuracy. The technique also provided the second smallest error variance among the stochastic algorithms. The experimental work also supports the potential of random forests for two practical applications: IPO pricing and IPO trading. Full article

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15 pages, 7234 KiB

Open AccessArticle

Functionalization of a Hydrophilic Commercial Membrane Using Inorganic-Organic Polymers Coatings for Membrane Distillation

by Lies Eykens^1,2,*

, Klaus Rose³

, Marjorie Dubreuil¹, Kristien De Sitter¹, Chris Dotremont¹, Luc Pinoy⁴ and Bart Van der Bruggen^2,5

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

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

³ Fraunhofer Institute for Silicate Research ISC, Neunerplatz 2, 97082 Würzburg, Germany

⁴ Department of Chemical Engineering, Cluster Sustainable Chemical Process Technology, KU Leuven, Gebroeders Desmetstraat 1, B-9000 Ghent, Belgium

⁵ Faculty of Engineering and the Built Environment, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa

Appl. Sci. 2017, 7(6), 637; https://doi.org/10.3390/app7060637 - 20 Jun 2017

Cited by 11 | Viewed by 5694

Abstract

Membrane distillation is a thermal separation technique using a microporous hydrophobic membrane. One of the concerns with respect to the industrialization of the technique is the development of novel membranes. In this paper, a commercially available hydrophilic polyethersulfone membrane with a suitable structure [...] Read more.

Membrane distillation is a thermal separation technique using a microporous hydrophobic membrane. One of the concerns with respect to the industrialization of the technique is the development of novel membranes. In this paper, a commercially available hydrophilic polyethersulfone membrane with a suitable structure for membrane distillation was modified using available hydrophobic coatings using ORMOCER^® technology to obtain a hydrophobic membrane that can be applied in membrane distillation. The surface modification was performed using a selection of different components, concentrations, and application methods. The resulting membranes can have two hydrophobic surfaces or a hydrophobic and hydrophilic surface depending on the application method. An extensive characterization procedure confirmed the suitability of the coating technique and the obtained membranes for membrane distillation. The surface contact angle of water could be increased from 27° up to 110°, and fluxes comparable to membranes commonly used for membrane distillation were achieved under similar process conditions. A 100 h test demonstrated the stability of the coating and the importance of using sufficiently stable base membranes. Full article

(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)

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22 pages, 5227 KiB

Open AccessArticle

Levels of Organic Pollution Indicators in Groundwater at the Old Landfill and Waste Management Site

by Eugeniusz Koda

, Anna Miszkowska and Anna Sieczka^*

Department of Geotechnical Engineering, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences, Nowoursynowska 159 St., 02-776 Warsaw, Poland

Appl. Sci. 2017, 7(6), 638; https://doi.org/10.3390/app7060638 - 20 Jun 2017

Cited by 76 | Viewed by 10035

Abstract

The aim of this paper was to assess groundwater quality in a landfill and waste management site, with special regard to levels of organic pollution indicators: chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC). Analysis of specific indicators [...] Read more.

The aim of this paper was to assess groundwater quality in a landfill and waste management site, with special regard to levels of organic pollution indicators: chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC). Analysis of specific indicators was conducted for piezometers located in the area of the Radiowo landfill, the composting plant and the facilities adjacent to the landfill. The article discusses the temporal and spatial changes of selected organic pollution indicators. Based on the results of groundwater monitoring, several maps of COD, BOD and TOC areal distribution were provided. Statistical distribution of monitoring data was presented using box-and-whisker plots. Pearson’s correlation coefficients between selected pollution indicators were measured with a significance level set at p < 0.01 and p < 0.05. The strongest correlation was observed between BOD and COD. The maximum BOD/COD ratio was observed at the level of 1.561 before the closure of the vertical barrier, whereas, at present, average values of this ratio are below 0.18. The results indicate significant improvement of groundwater quality in the landfill site after the closure of the vertical barrier. In particular, this refers to BOD values, which decreased even 160 times in the 1998–2016 monitoring period. Full article

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

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18 pages, 11695 KiB

Open AccessArticle

Multidisciplinary Aerodynamic Design of a Rotor Blade for an Optimum Rotor Speed Helicopter

by Jiayi Xie, Zhifeng Xie, Ming Zhou and Jun Qiu^*

Institute for Aero-Engine, School of Aerospace Engineering, Tsinghua University, Tsinghua Yuan No. 1, Beijing 100084, China

Appl. Sci. 2017, 7(6), 639; https://doi.org/10.3390/app7060639 - 20 Jun 2017

Cited by 15 | Viewed by 11722

Abstract

The aerodynamic design of rotor blades is challenging, and is crucial for the development of helicopter technology. Previous aerodynamic optimizations that focused only on limited design points find it difficult to balance flight performance across the entire flight envelope. This study develops a [...] Read more.

The aerodynamic design of rotor blades is challenging, and is crucial for the development of helicopter technology. Previous aerodynamic optimizations that focused only on limited design points find it difficult to balance flight performance across the entire flight envelope. This study develops a global optimum envelope (GOE) method for determining blade parameters—blade twist, taper ratio, tip sweep—for optimum rotor speed helicopters (ORS-helicopters), balancing performance improvements in hover and various freestream velocities. The GOE method implements aerodynamic blade design by a bi-level optimization, composed of a global optimization step and a secondary optimization step. Power loss as a measure of rotor performance is chosen as the objective function, referred to as direct power loss (DPL) in this study. A rotorcraft comprehensive code for trim simulation with a prescribed wake method is developed. With the application of the GOE method, a DPL reduction of as high as 16.7% can be achieved in hover, and 24% at high freestream velocity. Full article

(This article belongs to the Section Mechanical Engineering)

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16 pages, 3206 KiB

Open AccessFeature PaperArticle

FERMI: Present and Future Challenges

by Luca Giannessi^1,2,*

and Claudio Masciovecchio²

¹ ENEA C.R. Frascati, Via E. Fermi 45, Frascati, 00044 Rome, Italy

² Elettra Sincrotrone Trieste, I-34149 Basovizza, Trieste, Italy

Appl. Sci. 2017, 7(6), 640; https://doi.org/10.3390/app7060640 - 21 Jun 2017

Cited by 16 | Viewed by 5715

Abstract

We present an overview of the FERMI (acronym of Free Electron laser Radiation for Multidisciplinary Investigations) seeded free electron laser (FEL) facility located at the Elettra laboratory in Trieste. FERMI is now in user operation with both the FEL lines FEL-1 and FEL-2, [...] Read more.

We present an overview of the FERMI (acronym of Free Electron laser Radiation for Multidisciplinary Investigations) seeded free electron laser (FEL) facility located at the Elettra laboratory in Trieste. FERMI is now in user operation with both the FEL lines FEL-1 and FEL-2, covering the wavelength range between 100 nm and 4 nm. The seeding scheme adopted for photon pulse production makes FERMI unique worldwide and allows the extension of table top laser experiments in the extreme ultraviolet/soft X-ray region. In this paper, we discuss how advances in the performance of the FELs, with respect to coherent control and multi-colour pulse production, may push the development of original experimental strategies to study non-equilibrium behaviour of matter at the attosecond-nanometer time-length scales. This will have a tremendous impact as an experimental tool to investigate a large array of phenomena ranging from nano-dynamics in complex materials to phenomena that are at the heart of the conversion of light into other forms of energy. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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16 pages, 6972 KiB

Open AccessArticle

Design and Implementation of an Interactive Interface for Demand Response and Home Energy Management Applications

by Barış Yener¹, Akın Taşcıkaraoğlu¹, Ozan Erdinç^1,2,*, Mustafa Baysal¹ and João P. S. Catalão^2,3,4

¹ Department of Electrical Engineering, Faculty of Electric-Electronics, Yildiz Technical University Davutpasa Campus, Esenler, Istanbul 34220, Turkey

² INESC-ID, Instituto Superior Técnico, University of Lisbon, Lisbon 1049-001, Portugal

³ INESC TEC and the Faculty of Engineering of the University of Porto, Porto 4200-465, Portugal

⁴ Centre for Mechanical and Aerospace Science and Technologies (C-MAST), University of Beira Interior, Covilhã 6201-001, Portugal

Appl. Sci. 2017, 7(6), 641; https://doi.org/10.3390/app7060641 - 21 Jun 2017

Cited by 11 | Viewed by 6158

Abstract

Demand response (DR) implementations have recently found wide application areas in the context of smart grids. The effectiveness of these implementations is primarily based on the willingness of end-users to be involved in such programs. In this paper, an interactive and user-friendly interface [...] Read more.

Demand response (DR) implementations have recently found wide application areas in the context of smart grids. The effectiveness of these implementations is primarily based on the willingness of end-users to be involved in such programs. In this paper, an interactive and user-friendly interface is presented in order to facilitate and accordingly to increase the participation of end-users in DR programs. The proposed interface has the capability of providing the targeted information about the DR events to end-users and system operators, as well as allowing end-users to interactively monitor and control the progress of their appliances. In addition to its benefits to system operators and thus to the improved operation of power systems, the proposed interface particularly aims to exploit the potential energy-related cost savings by providing the required information and resources to end-users via mobile phone. A separate interface apart from the mentioned end-user oriented interface has also been developed for the system operator to more effectively check the status of DR applications in detail. The capabilities of the proposed concept are evaluated in a real smart home in terms of various aspects. Full article

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

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21 pages, 2800 KiB

Open AccessArticle

Computational Analysis and Artificial Neural Network Optimization of Dry Turning Parameters—AA2024-T351

by Waqas Saleem^1,*

, Muhammad Zain-ul-abdein¹, Hassan Ijaz¹

, Abdullah Salmeen Bin Mahfouz², Anas Ahmed³, Muhammad Asad⁴

and Tarek Mabrouki⁵

¹ Mechanical Engineering Department, University of Jeddah, Jeddah 21589, Saudi Arabia

² Chemical Engineering Department, University of Jeddah, Jeddah 21589, Saudi Arabia

³ Industrial Engineering Department, University of Jeddah, Jeddah 21589, Saudi Arabia

⁴ Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al Khobar 31952, Saudi Arabia

⁵ Mechanical Engineering Department, National Engineers School of Tunis, University of Tunis El Manar, Tunis 2092, Tunisia

Appl. Sci. 2017, 7(6), 642; https://doi.org/10.3390/app7060642 - 21 Jun 2017

Cited by 23 | Viewed by 6096

Abstract

In dry turning operation, various parameters influence the cutting force and contribute in machining precision. Generally, the numerical cutting models are adopted to establish the optimum cutting parameters and results are substantiated with the experimental findings. In this paper, the optimal turning parameters [...] Read more.

In dry turning operation, various parameters influence the cutting force and contribute in machining precision. Generally, the numerical cutting models are adopted to establish the optimum cutting parameters and results are substantiated with the experimental findings. In this paper, the optimal turning parameters of AA2024-T351 alloy are determined through Abaqus/Explicit numerical cutting simulations by employing the Johnson-Cook thermo-viscoplastic-damage material model. Turning simulations were verified with published experimental data. Considering the constrained and nonlinear optimization problem, the artificial neural networks (ANN) were executed for training, testing, and performance evaluation of the numerical simulations data. Two feedforward backpropagation neural networks were developed with ten hidden neutrons in each hidden layer. The Log-Sigmoid transfer function and the Levenberg-Marquardt algorithm were applied in the model. The ANN models were studied with four input parameters: the cutting speed (200, 400, and 800 m/min), tool rake angle (5°, 10°, 14.8°, and 17.5°), cutting feed (0.3 and 0.4 mm), and the contact friction coefficients (0.1 and 0.15).The two target parameters include the tool-chip interface temperature and the cutting reaction force. The performance of the trained data was evaluated using root-mean-square error and correlation coefficients. The ANN predicted values were compared both with the Abaqus simulations and the published experimental findings. All of the results are found in good approximation to each other. The performance of the ANN models demonstrated the fidelity of solving and predicting the optimum process parameters. Full article

(This article belongs to the Section Mechanical Engineering)

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