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Appl. Sci., Volume 8, Issue 4 (April 2018) – 180 articles

Cover Story (view full-size image): The figure displays a schematic of a third generation (3G) artificial turf surface used for sporting applications. The surface is constructed in a layered format consisting of (bottom to top): an elastomeric shockpad to enhance the surface shock absorption properties; a carpet layer consisting of polymer fibres stitched into a geotextile carpet backing to prevent migration of infill and act as an interface for ball interactions; a layer of sand infill to help support the fibres in an upright position; a performance infill layer consisting of rubber granules to provide an interface for player and ball interactions. View the paper here.
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14 pages, 3459 KiB  
Article
External Field Response and Applications of Metal Coated Hemispherical Janus Particles
by So Aizawa, Keisuke Seto and Eiji Tokunaga
Appl. Sci. 2018, 8(4), 653; https://doi.org/10.3390/app8040653 - 23 Apr 2018
Cited by 3 | Viewed by 4792
Abstract
Hemispherical Janus particles that were coated with silver or nickel on the equatorial plane of hemispherical polymer microparticles were prepared and dispersed in water and the responses to AC electric and stationary magnetic fields applied were investigated. Both of the particles are so [...] Read more.
Hemispherical Janus particles that were coated with silver or nickel on the equatorial plane of hemispherical polymer microparticles were prepared and dispersed in water and the responses to AC electric and stationary magnetic fields applied were investigated. Both of the particles are so oriented that the equatorial plane is parallel to the AC electric field, owing to electric-field induced dipole orientation, which is the response proportional to the quadratic electric field. The nickel coated particles are self-assembled to make a chain-like structure aligned in the direction of the stationary magnetic field. In addition, when both AC electric and stationary magnetic fields are applied, the orientation of a nickel-coated hemispherical particle is uniquely determined in such a way that the equatorial plane is parallel to both electric and magnetic fields. Because the particle is magnetized on the plane, its direction is reversed when the magnetic field is reversed, which is the response that is proportional to the magnetic field. Utilizing these features, mirrors are fabricated that can switch the transmittance and reflectance with electric and magnetic fields. Such features of the Janus particles as to be controlled by an electric and magnetic fields will find wide applications in the fields of microoptics and microfluidics. Full article
(This article belongs to the Section Optics and Lasers)
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13 pages, 878 KiB  
Article
Rapid High-Resolution Wavenumber Extraction from Ultrasonic Guided Waves Using Adaptive Array Signal Processing
by Shigeaki Okumura, Vu-Hieu Nguyen, Hirofumi Taki, Guillaume Haïat, Salah Naili and Toru Sato
Appl. Sci. 2018, 8(4), 652; https://doi.org/10.3390/app8040652 - 23 Apr 2018
Cited by 21 | Viewed by 4303
Abstract
Quantitative ultrasound techniques for assessment of bone quality have been attracting significant research attention. The axial transmission technique, which involves analysis of ultrasonic guided waves propagating along cortical bone, has been proposed for assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect [...] Read more.
Quantitative ultrasound techniques for assessment of bone quality have been attracting significant research attention. The axial transmission technique, which involves analysis of ultrasonic guided waves propagating along cortical bone, has been proposed for assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect the elastic parameters of the medium, high-resolution estimation of the wavenumbers is required at each frequency with low computational cost. We use an adaptive array signal processing method and propose a technique that can be used to estimate the numbers of propagation modes that exist at each frequency without the need for time-consuming calculations. An experimental study of 4-mm-thick copper and bone-mimicking plates showed that the proposed method estimated the wavenumbers accurately with estimation errors of less than 4% and a calculation time of less than 0.5 s when using a laptop computer. Full article
(This article belongs to the Special Issue Ultrasonic Guided Waves)
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15 pages, 9735 KiB  
Article
On the Statistical Characterization of Lightning-Induced Voltages
by Amedeo Andreotti, Fabio Mottola, Antonio Pierno and Daniela Proto
Appl. Sci. 2018, 8(4), 651; https://doi.org/10.3390/app8040651 - 23 Apr 2018
Cited by 11 | Viewed by 4046
Abstract
Protection against lightning-induced voltages is a particularly critical issue, especially for smart grids, due to the presence of electronic-based equipment, as well as control and monitoring devices. Analysis of the severity of the induced voltages is then imperative; on the other hand, the [...] Read more.
Protection against lightning-induced voltages is a particularly critical issue, especially for smart grids, due to the presence of electronic-based equipment, as well as control and monitoring devices. Analysis of the severity of the induced voltages is then imperative; on the other hand, the random nature of the lightning phenomenon cannot be disregarded. In this paper, the severity of lightning-induced voltage is analyzed by means of a probabilistic approach which, starting from closed-form solutions, uses a Monte Carlo procedure. Parametric distributions that best fit the distributions of the induced voltages are investigated as well. The results show that the lognormal and the generalized extreme value distributions are the best candidates. Full article
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22 pages, 11454 KiB  
Article
Dynamic Response of a Long-Span Concrete-Filled Steel Tube Tied Arch Bridge and the Riding Comfort of Monorail Trains
by Hongye Gou, Wen Zhou, Changwei Yang, Yi Bao and Qianhui Pu
Appl. Sci. 2018, 8(4), 650; https://doi.org/10.3390/app8040650 - 23 Apr 2018
Cited by 37 | Viewed by 8338
Abstract
In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to [...] Read more.
In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to investigate the dynamic behaviors of the bridge under moving trains. A refined three-dimensional finite element model is built for the bridge and a 15 degrees-of-freedom vehicle model is presented for the train. The numerical model is validated using in-situ test results and then used to analyze the dynamic displacement and acceleration of the bridge and the trains on the bridge. Based on the simulation results, the impact factor of the bridge is investigated and the riding comfort of the trains is evaluated. The investigation results show that the impact factor of vehicle loads reaches the maximum value when the resonance of the bridge is induced by the moving vehicles. The effect of train braking predominates the longitudinal vibration of the bridge but is negligible in the transverse and vertical directions. The vehicle speed is the dominating factor for the riding comfort of the train. Full article
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22 pages, 11977 KiB  
Article
Lyapunov Equivalent Representation Form of Forced, Damped, Nonlinear, Two Degree-of-Freedom Systems
by Alex Elías-Zúñiga, Luis M. Palacios-Pineda, Daniel Olvera-Trejo and Oscar Martínez-Romero
Appl. Sci. 2018, 8(4), 649; https://doi.org/10.3390/app8040649 - 21 Apr 2018
Cited by 11 | Viewed by 4213
Abstract
The aim of this paper focuses on finding equivalent representation forms of forced, damped, two degree-of-freedom, nonlinear systems in the sense of Lyapunov by using a nonlinear transformation approach that provides decoupled, forced, damped, nonlinear equations of the Duffing type, under the assumption [...] Read more.
The aim of this paper focuses on finding equivalent representation forms of forced, damped, two degree-of-freedom, nonlinear systems in the sense of Lyapunov by using a nonlinear transformation approach that provides decoupled, forced, damped, nonlinear equations of the Duffing type, under the assumption that the driving frequency and the external forces are equal in both systems. The values of Lyapunov characteristic exponents (LCEs), Lyapunov largest exponents (LLE), and time-amplitude and frequency-amplitude curves computed from numerical integration solutions, indicate that the decoupled Duffing-type equations are equivalent, in the sense of Lyapunov, to the original dynamic system, since both set of motion equations tend to have the same qualitative and quantitative behaviors. Full article
(This article belongs to the Section Mechanical Engineering)
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23 pages, 2160 KiB  
Article
Energy Management Scheme for an EV Smart Charger V2G/G2V Application with an EV Power Allocation Technique and Voltage Regulation
by Saad Ullah Khan, Khawaja Khalid Mehmood, Zunaib Maqsood Haider, Syed Basit Ali Bukhari, Soon-Jeong Lee, Muhammad Kashif Rafique and Chul-Hwan Kim
Appl. Sci. 2018, 8(4), 648; https://doi.org/10.3390/app8040648 - 21 Apr 2018
Cited by 46 | Viewed by 9730
Abstract
The increasing penetration of electric vehicles (EVs) in the distribution grid has established them as a prospective resource for ancillary services. These services require adequate control strategies for prompt and efficient operation. In this study, an energy management scheme (EMS) has been proposed [...] Read more.
The increasing penetration of electric vehicles (EVs) in the distribution grid has established them as a prospective resource for ancillary services. These services require adequate control strategies for prompt and efficient operation. In this study, an energy management scheme (EMS) has been proposed to employ an off-board EV smart charger to support the grid during short-term variance of renewables and reactive load onset. The scheme operates by calculating power references for the charger instantaneously. The EMS incorporates a proportional power division methodology, proposed to allocate power references to the individual EVs connected to the charger DC-bus. This methodology considers the state-of-charge and battery sizes of the EVs, and it can aggregate energy from various types of EVs. The proposed scheme is compared with another power allocation method, and the entire EMS is tested under the scenarios of power mismatch and voltage sag/swell events. The results show that the proposed scheme achieves the goal of the aggregation of EVs at the charger level to support the grid. The EMS also fulfills the objectives of voltage regulation and four-quadrant operation of the smart charger. Full article
(This article belongs to the Special Issue Developing and Implementing Smart Grids: Novel Technologies, Techniques and Models)
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18 pages, 4663 KiB  
Article
Novel Guidance CPS Based on the FatBeacon Protocol
by Moisés Lodeiro-Santiago, Iván Santos-González, Cándido Caballero-Gil, Pino Caballero-Gil and Félix Herrera-Priano
Appl. Sci. 2018, 8(4), 647; https://doi.org/10.3390/app8040647 - 20 Apr 2018
Cited by 4 | Viewed by 4029
Abstract
Throughout this work, the use of a new technology is proposed to give an innovative solution to the problem of indoor and outdoor positioning and a guidance system in areas where there is no coverage of Internet or global positioning systems. This novel [...] Read more.
Throughout this work, the use of a new technology is proposed to give an innovative solution to the problem of indoor and outdoor positioning and a guidance system in areas where there is no coverage of Internet or global positioning systems. This novel solution is based on the Bluetooth protocol called FatBeacon, created by Google, which can be used in places such as subway stations located below ground, outdoor areas where even 2G coverage is unreachable or simply as an alternative to current technologies that may require an additional cost, such as the Internet in some countries. In particular, this work describes a new solution for supporting tourism called Smart Tourism for which an interactive and non-intrusive guidance application based on the FatBeacon protocol is presented. The developed application informs the users about the way to reach their destination without getting lost and can be used to obtain user data tracking anonymously. In this way, the cooperation between the different systems and components of the scheme creates a distributed ecosystem that is independent of an Internet connection. Since no FatBeacon implementations can be found yet, an experimental implementation was developed to test the proposal, and the obtained results are promising. Full article
(This article belongs to the Special Issue Security and Privacy for Cyber Physical Systems)
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32 pages, 9373 KiB  
Article
Proposing Enhanced Feature Engineering and a Selection Model for Machine Learning Processes
by Muhammad Fahim Uddin, Jeongkyu Lee, Syed Rizvi and Samir Hamada
Appl. Sci. 2018, 8(4), 646; https://doi.org/10.3390/app8040646 - 20 Apr 2018
Cited by 37 | Viewed by 9032
Abstract
Machine Learning (ML) requires a certain number of features (i.e., attributes) to train the model. One of the main challenges is to determine the right number and the type of such features out of the given dataset’s attributes. It is not uncommon for [...] Read more.
Machine Learning (ML) requires a certain number of features (i.e., attributes) to train the model. One of the main challenges is to determine the right number and the type of such features out of the given dataset’s attributes. It is not uncommon for the ML process to use dataset of available features without computing the predictive value of each. Such an approach makes the process vulnerable to overfit, predictive errors, bias, and poor generalization. Each feature in the dataset has either a unique predictive value, redundant, or irrelevant value. However, the key to better accuracy and fitting for ML is to identify the optimum set (i.e., grouping) of the right feature set with the finest matching of the feature’s value. This paper proposes a novel approach to enhance the Feature Engineering and Selection (eFES) Optimization process in ML. eFES is built using a unique scheme to regulate error bounds and parallelize the addition and removal of a feature during training. eFES also invents local gain (LG) and global gain (GG) functions using 3D visualizing techniques to assist the feature grouping function (FGF). FGF scores and optimizes the participating feature, so the ML process can evolve into deciding which features to accept or reject for improved generalization of the model. To support the proposed model, this paper presents mathematical models, illustrations, algorithms, and experimental results. Miscellaneous datasets are used to validate the model building process in Python, C#, and R languages. Results show the promising state of eFES as compared to the traditional feature selection process. Full article
(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)
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20 pages, 12320 KiB  
Review
A Review of MEMS Scale Piezoelectric Energy Harvester
by Wenchao Tian, Zongyu Ling, Wenbo Yu and Jing Shi
Appl. Sci. 2018, 8(4), 645; https://doi.org/10.3390/app8040645 - 20 Apr 2018
Cited by 72 | Viewed by 10027
Abstract
Piezoelectric energy harvester (PEH) is emerging as a novel device which can convert mechanical energy into electrical energy. It is mainly used to collect ambient vibration energy to power sensors, chips and some other small applications. This paper first introduces the working principle [...] Read more.
Piezoelectric energy harvester (PEH) is emerging as a novel device which can convert mechanical energy into electrical energy. It is mainly used to collect ambient vibration energy to power sensors, chips and some other small applications. This paper first introduces the working principle of PEH. Then, the paper elaborates the research progress of PEH from three aspects: piezoelectric materials, piezoelectric modes and energy harvester structures. Piezoelectric material is the core of the PEH. The piezoelectric and mechanical properties of piezoelectric material determine its application in energy harvesting. There are three piezoelectric modes, d31, d33 and d15, the choice of which influences the maximum output voltage and power. Matching the external excitation frequency maximizes the conversion efficiency of the energy harvester. There are three approaches proposed in this paper to optimize the PEH’s structure and match the external excitation frequency, i.e., adjusting the resonant frequency, frequency up-converting and broadening the frequency bandwidth. In addition, harvesting maximum output power from the PEH requires impedance matching. Finally, this paper analyzes the above content and predicts PEH’s future development direction. Full article
(This article belongs to the Section Energy Science and Technology)
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10 pages, 5501 KiB  
Article
Camera Calibration with Phase-Shifting Wedge Grating Array
by Jiayuan Tao, Yuwei Wang, Bolin Cai and Keyi Wang
Appl. Sci. 2018, 8(4), 644; https://doi.org/10.3390/app8040644 - 20 Apr 2018
Cited by 8 | Viewed by 4688
Abstract
Planar targets with known features have been widely used for camera calibration in various vision systems. This paper utilizes phase-shifting wedge grating (PWG) arrays as an active calibration target. Features points are encoded into the carrier phase, which can be accurately calculated using [...] Read more.
Planar targets with known features have been widely used for camera calibration in various vision systems. This paper utilizes phase-shifting wedge grating (PWG) arrays as an active calibration target. Features points are encoded into the carrier phase, which can be accurately calculated using the phase-shifting algorithm. The 2π-phase points are roughly extracted with edge detection and then optimized by windowed bicubic fitting with sub-pixel accuracy. Two 2π-phase lines for each PWG are obtained using linear fitting method. The PWG centers that are used as feature points are detected through computing the intersections of 2π-phase lines. Experiment results indicate that the proposed method is accurate and reliable. Full article
(This article belongs to the Section Optics and Lasers)
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6 pages, 2830 KiB  
Communication
Carbon Nanotube Mode-Locked Fiber Laser Generating Cylindrical Vector Beams with a Two-Mode Fiber Bragg Grating
by Yu Cai, Jiaojiao Zhang, Changle Wang, Lin Zhang and Zuxing Zhang
Appl. Sci. 2018, 8(4), 643; https://doi.org/10.3390/app8040643 - 20 Apr 2018
Cited by 2 | Viewed by 3960
Abstract
We propose and demonstrate a compact all-fiber laser generating cylindrical vector beam (CVB) using carbon nanotubes as the saturable absorber for mode-locking and a two-mode fiber Bragg grating (TM-FBG) as the mode discriminator. Both radially and azimuthally polarized beams with a polarization purity [...] Read more.
We propose and demonstrate a compact all-fiber laser generating cylindrical vector beam (CVB) using carbon nanotubes as the saturable absorber for mode-locking and a two-mode fiber Bragg grating (TM-FBG) as the mode discriminator. Both radially and azimuthally polarized beams with a polarization purity of 90% were obtained by simply adjusting the polarization controllers. The CVB mode-locked fiber laser operates at 1552.9 nm with a 3-dB line width of less than 0.02 nm, generating ns CVB pulses. The all-fiber CVB laser may have potential applications from fundamental research to practical applications, such as particle capture, high-resolution measurement and material processing. Full article
(This article belongs to the Special Issue Erbium-doped Fiber Lasers)
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13 pages, 4401 KiB  
Article
Stability Analysis of Stagnation-Point Flow in a Nanofluid over a Stretching/Shrinking Sheet with Second-Order Slip, Soret and Dufour Effects: A Revised Model
by Najwa Najib, Norfifah Bachok, Norihan Md Arifin and Fadzilah Md Ali
Appl. Sci. 2018, 8(4), 642; https://doi.org/10.3390/app8040642 - 20 Apr 2018
Cited by 32 | Viewed by 4985
Abstract
The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were [...] Read more.
The mathematical model of the two-dimensional steady stagnation-point flow over a stretching or shrinking sheet of nanofluid in the presence of the Soret and Dufour effects and of second-order slip at the boundary was considered in this paper. The partial differential equations were transformed into the ordinary differential equations by applying a suitable similarity transformation. The numerical results were obtained by using bvp4c codes in Matlab. The skin friction coefficient, heat transfer coefficient, mass transfer coefficient, as well as the velocity, temperature, and concentration profiles were presented graphically for different values of slip parameters, Soret effect, Dufour effect, Brownian motion parameter, and thermophoresis parameter. A dual solution was obtained in this present paper. The presence of the slip parameters (first- and second-order slip parameters) was found to expand the range of solutions. However, the presence of the slip parameters led to a decrease in the skin friction coefficient, whereas the heat transfer coefficient increased. Besides that, a larger Soret effect (smallest Dufour effect) led to the decrement of the heat transfer coefficient. The effects of the Brownian motion and thermophoresis parameters on the heat transfer coefficient were also studied in this paper. A stability analysis was performed in this paper to verify the stability of the solutions obtained. Full article
(This article belongs to the Special Issue Nanofluids and Their Applications)
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18 pages, 3854 KiB  
Article
Power System Voltage Correction Scheme Based on Adaptive Horizon Model Predictive Control
by Yan Zhang, Meng Liu, Wen Zhang, Wenchuan Sun, Xingwang Hu and Gang Kong
Appl. Sci. 2018, 8(4), 641; https://doi.org/10.3390/app8040641 - 20 Apr 2018
Cited by 2 | Viewed by 4002
Abstract
Model predictive control (MPC) is commonly used to compensate for modeling inaccuracies and measurement noise in voltage control problems. The length of the prediction horizon and control horizon of a MPC-based method has significant impact on the control performances. In existing relevant works, [...] Read more.
Model predictive control (MPC) is commonly used to compensate for modeling inaccuracies and measurement noise in voltage control problems. The length of the prediction horizon and control horizon of a MPC-based method has significant impact on the control performances. In existing relevant works, those horizon parameters are determined off-line based on experience or enumeration, and keeps constant during the entire receding-horizon optimization process. This paper presents a system voltage correction scheme based on adaptive horizon model predictive control (AH-MPC). The reactive power compensation and voltage regulation devices are coordinated to maintain the system voltages within a desired range. An evaluation index is proposed to determine the horizon parameters, which reflects the maximum voltage regulation ability with the current parameter configuration. Within each sampling interval, the horizon parameters are updated according to the evaluation index and real-time measurements periodically, which comprehensively considers the system uncertainties and voltage recovery speed, and the computational effort is remarkably reduced. The validation and effectiveness of the proposed method is verified by the simulation analysis on the test system. Full article
(This article belongs to the Special Issue Smart Grid and Smart Cities Activities)
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12 pages, 10870 KiB  
Article
Fusion of Spectra and Texture Data of Hyperspectral Imaging for the Prediction of the Water-Holding Capacity of Fresh Chicken Breast Filets
by Yi Yang, Wei Wang, Hong Zhuang, Seung-Chul Yoon and Hongzhe Jiang
Appl. Sci. 2018, 8(4), 640; https://doi.org/10.3390/app8040640 - 20 Apr 2018
Cited by 32 | Viewed by 5155
Abstract
This study investigated the fusion of spectra and texture data of hyperspectral imaging (HSI, 1000–2500 nm) for predicting the water-holding capacity (WHC) of intact, fresh chicken breast filets. Three physical and chemical indicators—drip loss, expressible fluid, and salt-induced water gain—were measured to be [...] Read more.
This study investigated the fusion of spectra and texture data of hyperspectral imaging (HSI, 1000–2500 nm) for predicting the water-holding capacity (WHC) of intact, fresh chicken breast filets. Three physical and chemical indicators—drip loss, expressible fluid, and salt-induced water gain—were measured to be different WHC references of chicken meat. Different partial least squares regression (PLSR) models were established with corresponding input variables including the full spectra, key wavelengths, and texture variables, as well as the fusion data of key wavelengths and the corresponding texture variables, respectively. The results demonstrated that for drip loss and expressible fluid, texture data was an effective supplement to spectra data, and fusion data as an input variable could effectively improve the predictive ability of the independent prediction set (Rp = 0.80, RMSEp = 0.80; Rp = 0.56, RMSEp = 2.10). While the best model to predict salt-induced water gain was based on key wavelengths (Rp = 0.69, RMSEp = 18.04), this was mainly because salt-induced water gain was measured on mince samples, which lacked the important physical structure to represent the texture information of meat. Our results of this study demonstrated the potential to further improve the evaluation of the WHC of chicken meat by HSI. Full article
(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)
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17 pages, 7586 KiB  
Article
Development of Proportional Pressure Control Valve for Hydraulic Braking Actuator of Automobile ABS
by Che-Pin Chen and Mao-Hsiung Chiang
Appl. Sci. 2018, 8(4), 639; https://doi.org/10.3390/app8040639 - 20 Apr 2018
Cited by 18 | Viewed by 11271
Abstract
This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high [...] Read more.
This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high controllability and ease of production, the driver of this proportional valve was designed with a small volume and powerful solenoid force to control braking pressure and flow. Since the proportional valve can have closed-loop control, the proportional valve can replace a conventional solenoid valve in current brake actuators. With the proportional valve controlling braking and pressure relief mode, it can narrow the space of hydraulic braking actuator, and precisely control braking force to achieve safety objectives. Finally, the proposed novel proportional pressure control valve of an automobile hydraulic braking actuator was implemented and verified experimentally. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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15 pages, 5871 KiB  
Article
Trouton’s Rule for Vapor Sorption in Solids
by Ard-Jan De Jong and Hartmut Fischer
Appl. Sci. 2018, 8(4), 638; https://doi.org/10.3390/app8040638 - 20 Apr 2018
Cited by 2 | Viewed by 6920
Abstract
Hygroscopic salts exhibiting fast and reversible hydration are promising systems for seasonal heat storage, providing the possibility of storing excess solar energy from the warm season for later use during the cold season. For heat storage, the salt is dehydrated with the available [...] Read more.
Hygroscopic salts exhibiting fast and reversible hydration are promising systems for seasonal heat storage, providing the possibility of storing excess solar energy from the warm season for later use during the cold season. For heat storage, the salt is dehydrated with the available heat, and for heat recovery, the salt is rehydrated. There are many salt hydration transitions and for selecting the most suited ones with respect to the envisaged use cases, temperatures of dehydration and rehydration are needed, as well as the heat storage density. Estimation of these properties requires entropy and enthalpy changes of the transitions. Collections of hydration entropies and enthalpies have been published, but not all data seems reliable for various reasons, and it is often hard to access original sources and experimental conditions. For the necessary data validation, we propose the use of Trouton’s rule, known to hold for the evaporation of classes of fluids. Besides data validation, Trouton’s rule is useful for predicting heat storage densities and vapor pressures when only the transition enthalpy is known. We discuss the validity of Trouton’s rule for salt hydration and ammoniation transitions by theoretical and experimental evidence on the available extensive data collections. Full article
(This article belongs to the Special Issue Materials for Thermal Energy Storage)
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18 pages, 32924 KiB  
Article
Multi-Plane Ultrafast Compound 3D Strain Imaging: Experimental Validation in a Carotid Bifurcation Phantom
by Stein Fekkes, Anne E. C. M. Saris, Jan Menssen, Maartje M. Nillesen, Hendrik H. G. Hansen and Chris L. De Korte
Appl. Sci. 2018, 8(4), 637; https://doi.org/10.3390/app8040637 - 20 Apr 2018
Cited by 9 | Viewed by 4559
Abstract
Strain imaging of the carotid artery (CA) has demonstrated to be a technique capable of identifying plaque composition. This study assesses the performance of volumetric strain imaging derived from multi-plane acquisitions with a single transducer, with and without displacement compounding. These methods were [...] Read more.
Strain imaging of the carotid artery (CA) has demonstrated to be a technique capable of identifying plaque composition. This study assesses the performance of volumetric strain imaging derived from multi-plane acquisitions with a single transducer, with and without displacement compounding. These methods were compared to a reference method using two orthogonally placed transducers. A polyvinyl alcohol phantom was created resembling a stenotic CA bifurcation. A realistic pulsatile flow was imposed on the phantom, resulting in fluid pressures inducing 10% strains. Two orthogonally aligned linear array transducers were connected to two Verasonics systems and fixed in a translation stage. For 120 equally spaced elevational positions, ultrasound series were acquired for a complete cardiac cycle and synchronized using a trigger. Each series consisted of ultrafast plane-wave acquisitions at 3 alternating angles. Inter-frame displacements were estimated using a 3D cross-correlation-based tracking algorithm. Horizontal displacements were acquired using the single probe lateral displacement estimate, the single probe compounded by axial displacement estimates obtained at angles of 19.47 and −19.47 degrees, and the dual probe registered axial displacement estimate. After 3D tracking, least squares strain estimations were performed to compare compressive and tensile principal strains in 3D for all methods. The compounding technique clearly outperformed the zero-degree method for the complete cardiac cycle and resulted in more accurate 3D strain estimates. Full article
(This article belongs to the Special Issue Ultrafast Ultrasound Imaging)
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19 pages, 6961 KiB  
Article
Forecasting of Power Grid Investment in China Based on Support Vector Machine Optimized by Differential Evolution Algorithm and Grey Wolf Optimization Algorithm
by Shuyu Dai, Dongxiao Niu and Yaru Han
Appl. Sci. 2018, 8(4), 636; https://doi.org/10.3390/app8040636 - 19 Apr 2018
Cited by 40 | Viewed by 5647
Abstract
In recent years, the construction of China’s power grid has experienced rapid development, and its scale has leaped into the first place in the world. Accurate and effective prediction of power grid investment can not only help pool funds and rationally arrange investment [...] Read more.
In recent years, the construction of China’s power grid has experienced rapid development, and its scale has leaped into the first place in the world. Accurate and effective prediction of power grid investment can not only help pool funds and rationally arrange investment in power grid construction, but also reduce capital costs and economic risks, which plays a crucial role in promoting power grid investment planning and construction process. In order to forecast the power grid investment of China accurately, firstly on the basis of analyzing the influencing factors of power grid investment, the influencing factors system for China’s power grid investment forecasting is constructed in this article. The method of grey relational analysis is used for screening the main influencing factors as the prediction model input. Then, a novel power grid investment prediction model based on DE-GWO-SVM (support vector machine optimized by differential evolution and grey wolf optimization) algorithm is proposed. Next, two cases are taken for empirical analysis to prove that the DE-GWO-SVM model has strong generalization capacity and has achieved a good prediction effect for power grid investment forecasting in China. Finally, the DE-GWO-SVM model is adopted to forecast power grid investment in China from 2018 to 2022. Full article
(This article belongs to the Section Energy Science and Technology)
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11 pages, 27259 KiB  
Article
Histological and Bone Morphometric Evaluation of Osseointegration Aspects by Alkali Hydrothermally-Treated Implants
by Hanako Umehara, Reiko Kobatake, Kazuya Doi, Yoshifumi Oki, Yusuke Makihara, Takayasu Kubo and Kazuhiro Tsuga
Appl. Sci. 2018, 8(4), 635; https://doi.org/10.3390/app8040635 - 19 Apr 2018
Cited by 6 | Viewed by 4112
Abstract
The purpose of this study was to investigate the osseointegration aspects of alkali-treated implants by histological and bone morphometric evaluations. Titanium implants (control) and alkali hydrothermally-treated titanium implants were used. Samples were evaluated by surface structure observation and wettability tests. Both implants were [...] Read more.
The purpose of this study was to investigate the osseointegration aspects of alkali-treated implants by histological and bone morphometric evaluations. Titanium implants (control) and alkali hydrothermally-treated titanium implants were used. Samples were evaluated by surface structure observation and wettability tests. Both implants were placed into the femurs of five rabbits, and osseointegration was assessed by measurement of removal torque (RT), bone–implant contact ratio (BIC), and bone tissue area ratio (BTA). Measurements were performed at the whole portion around the implant, the cortical bone portion, and the bone marrow portion. The surface structure of alkali-group showed nanoscale pores and super hydrophilicity. RT, BIC, and BTA values of alkali-group were significantly higher than those of control-group at the whole portion. In the cortical bone portion, the BIC value was higher in the alkali-group than in the control-group, and BTA showed no significant difference between groups. In the bone marrow portion, even though no significant difference between control and alkali groups, the latter had higher ratio of BIC than the former. These results indicate that alkali treated implants enhance bone integration in areas where the implant is in contact with bone, and may promote osteoinduction in the non-bone marrow portion. Full article
(This article belongs to the Section Materials Science and Engineering)
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11 pages, 2317 KiB  
Article
Enhancement of Neuroprotective Effects of Spirulina platensis Extract from a High-Pressure Homogenization Process
by Woon Yong Choi and Hyeon Yong Lee
Appl. Sci. 2018, 8(4), 634; https://doi.org/10.3390/app8040634 - 19 Apr 2018
Cited by 8 | Viewed by 3877
Abstract
This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear [...] Read more.
This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear stress of approximately 20,000 (1/s) compared to 5.27 mg/g from conventional 70% ethanol extraction (EE) at 40 °C for 24 h. However, a higher input pressure did not increase the extraction yield and in fact decreased it, possibly due to the destruction of chlorophyll a at a high shear stress of approximately 50,000 (1/s) under 1370 bar of input pressure. Chlorophyll a and other components of the extract had additive effects, showing higher antioxidant activities of ca. 56% of DPPH radical scavenging activities than 10 μg/mL chlorophyll a alone, which corresponded to the same chlorophyll a content that existed in the extract. It was also confirmed that the high antioxidant activities of the HP extract reduced the production of reactive oxygen species (ROS) from glutamate-induced HT22 cells, which resulted in increased neuroprotective activity compared to EE and even chlorophyll a alone, in addition to effectively reducing the release of Ca2+ from nerve cells. Full article
(This article belongs to the Special Issue Acoustic and Hydrodynamic Effects in Food Processing)
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19 pages, 5055 KiB  
Article
Experimental Investigation of the Creep Behaviour of Coal by Monitoring Changes of Acoustic Properties
by Sen Yang, Nong Zhang, Xiaowei Feng and Jiaguang Kan
Appl. Sci. 2018, 8(4), 633; https://doi.org/10.3390/app8040633 - 19 Apr 2018
Cited by 7 | Viewed by 3916
Abstract
Time-dependent deformation of coal is a major concern for deep coal mining. When experiencing high stress conditions, the enhanced time-dependent deformation of coal will become a very possible factor to trigger the violent failure of underground openings. For this study, the inner structural [...] Read more.
Time-dependent deformation of coal is a major concern for deep coal mining. When experiencing high stress conditions, the enhanced time-dependent deformation of coal will become a very possible factor to trigger the violent failure of underground openings. For this study, the inner structural variation of an extremely inhomogeneous coal subjected to incremental creep stress has been experimentally investigated by monitoring both the macroscopic deformation and acoustic property. Results show the following: (1) The pronounced inhomogeneity of coal induces considerable irregularities in creep strain data collected during the increase of stress level. These flawed data highlight the shortcomings of conventional strain-time relationship experiments for deciphering the mechanisms that control creep; (2) The mechanical response of samples under creep compression is the result of competition between compaction and cracking. Cracking deteriorates the structure and increases the ultrasonic attenuation, whilst the compaction causes the densification along the axial axis and reduces attenuation; (3) Long-term creep involves multiple structural deformations that alter the internal structure of the coal. This results in fluctuations of the ultrasonic velocities and their dynamic moduli; (4) During uploading phase of short term creep, vertical cracks develop and transform the sample into a structure consisting of separated columns. Further deterioration of the coal increases the possibility of tensile and shear failure of individual columns, which can trigger the violent collapse of an already fragile structure. Full article
(This article belongs to the Section Acoustics and Vibrations)
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6 pages, 18867 KiB  
Article
New Instrument for Oral Hygiene of Children with Cleft Lip and Palate
by Rita Rodrigues, Maria Helena Fernandes, António Bessa Monteiro, Rowney Furfuro, Cátia Carvalho Silva, César Soares, Ricardo Vardasca, Joaquim Mendes and Maria Conceição Manso
Appl. Sci. 2018, 8(4), 576; https://doi.org/10.3390/app8040576 - 19 Apr 2018
Cited by 2 | Viewed by 7293
Abstract
Patients with cleft lip and palate (CLP) have several oral alterations that make the removal of bacterial plaque in the cleft area difficult, which is the main cause of the high incidence of oral health problems. The aim of this study is to [...] Read more.
Patients with cleft lip and palate (CLP) have several oral alterations that make the removal of bacterial plaque in the cleft area difficult, which is the main cause of the high incidence of oral health problems. The aim of this study is to develop a toothbrush especially designed to perform the hygiene of the cleft area. This device, called Cleft Toothbrush, is an add-on to a conventional toothbrush to clean hard-to-reach areas that are not accessible by using conventional brush shapes. The design was made in SOLIDWORKS® (Waltham, MA, USA) 3D and a sample of this device was produced by CURAPROX (Kriens, Switzerland). The efficacy of the Cleft Toothbrush was tested in a preliminary study performed in a four years old child with CLP, compared to that of a conventional toothbrush. A significantly higher reduction of the bacterial plaque was achieved with the Cleft Toothbrush. The child’s parents also felt more confident with this device, as it deals better with sensitive areas, as it did not hurt the child. This innovative toothbrush adapter appears to greatly improve the cleaning areas of high bacterial plaque retention in patients with CLP, together with excellent acceptance. Full article
(This article belongs to the Section Materials Science and Engineering)
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14 pages, 2156 KiB  
Article
A Novel Swarm Optimisation Algorithm Based on a Mixed-Distribution Model
by Xiaoming Zhang, Tinghao Feng, Qingsong Niu and Xijin Deng
Appl. Sci. 2018, 8(4), 632; https://doi.org/10.3390/app8040632 - 18 Apr 2018
Cited by 9 | Viewed by 3741
Abstract
Many swarm intelligence optimisation algorithms have been inspired by the collective behaviour of natural and artificial, decentralised, self-organised systems. Swarm intelligence optimisation algorithms have unique advantages in solving certain complex problems that cannot be easily solved by traditional optimisation algorithms. Inspired by the [...] Read more.
Many swarm intelligence optimisation algorithms have been inspired by the collective behaviour of natural and artificial, decentralised, self-organised systems. Swarm intelligence optimisation algorithms have unique advantages in solving certain complex problems that cannot be easily solved by traditional optimisation algorithms. Inspired by the adaptive phenomena of plants, a novel evolutionary algorithm named the bean optimisation algorithm (BOA) is proposed, which combines natural evolutionary tactics and limited random searches. It demonstrates stable behaviour in experiments and is a promising alternative to existing optimisation methods for engineering applications. A novel distribution model for BOA is built through research and study on the relevant research results of biostatistics. This model is based on a combination of the negative binomial and normal distributions, and the resulting algorithm is called NBOA. To validate NBOA, function optimisation experiments are carried out, which include ten typical benchmark functions. The results indicate that NBOA performs better than particle swarm optimisation (PSO) and BOA. We also investigate the characteristics of NBOA and conduct a contrast analysis to verify our conclusions about the relationship between its parameters and its performance. Full article
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14 pages, 5225 KiB  
Article
Adaptive CoMP with Spatial Phase Coding for Interference Mitigation in the Heterogeneous Network
by Won-Chang Kim, Min-Jae Paek, Jae-Hyun Ro and Hyoung-Kyu Song
Appl. Sci. 2018, 8(4), 631; https://doi.org/10.3390/app8040631 - 18 Apr 2018
Cited by 4 | Viewed by 3288
Abstract
This paper proposes an adaptive coordinated multi point (CoMP) scheme using pre-coding in order to improve the reliability of wireless communication systems based on orthogonal frequency division multiplexing (OFDM). In the conventional scheme, the received signal to noise ratio (SNR) of the mobile [...] Read more.
This paper proposes an adaptive coordinated multi point (CoMP) scheme using pre-coding in order to improve the reliability of wireless communication systems based on orthogonal frequency division multiplexing (OFDM). In the conventional scheme, the received signal to noise ratio (SNR) of the mobile is degraded due to the interference signal. Therefore, the bit error rate (BER) performance is degraded, as is, the reliability of the system, due to inter-cell interference (ICI). Therefore, the BER performance of the system is reduced and the transmitter must perform unnecessary re-transmission. The proposed scheme uses the CoMP scheme to improve reliability in a heterogeneous network (HetNet) system. Additionally, the proposed scheme uses the constructive spatial phase coding (SPC) scheme to mitigate the received SNR reduction due to the interference signal. Therefore, the proposed scheme can prevent performance degradation caused by the interference signal. When a mobile is located in the cell edge, the transmission signal is distorted by the transmitted signal from the adjacent cell. The proposed scheme can reduce the SNR of the interference signal by using the destructive SPC scheme. Therefore, this scheme can improve the reliability of the system. The simulation results show that the BER performance of the proposed scheme is better than that of the conventional scheme. As a result, the proposed scheme improves the reliability of systems by adaptively applying the CoMP and SPC schemes. Full article
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21 pages, 18311 KiB  
Article
Reconstruct Recurrent Neural Networks via Flexible Sub-Models for Time Series Classification
by Ye Ma, Qing Chang, Huanzhang Lu and Junliang Liu
Appl. Sci. 2018, 8(4), 630; https://doi.org/10.3390/app8040630 - 18 Apr 2018
Cited by 5 | Viewed by 4385
Abstract
Recurrent neural networks (RNNs) remain challenging, and there is still a lack of long-term memory or learning ability in sequential data classification and prediction. In this paper, we propose a flexible recurrent model, BIdirectional COnvolutional RaNdom RNNs (BICORN-RNNs), incorporating a series of sub-models: [...] Read more.
Recurrent neural networks (RNNs) remain challenging, and there is still a lack of long-term memory or learning ability in sequential data classification and prediction. In this paper, we propose a flexible recurrent model, BIdirectional COnvolutional RaNdom RNNs (BICORN-RNNs), incorporating a series of sub-models: random projection, convolutional operation, and bidirectional transmission. These subcategories advance classification accuracy, which was limited by the gradient vanishing and the exploding problem. Experiments on public time series datasets demonstrate that our proposed method substantially outperforms a variety of existing models. Furthermore, the coordination of the accuracy and efficiency concerning a variety of factors, including SNR, length, data missing, and overlapping, is also discussed. Full article
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8 pages, 9949 KiB  
Article
Blue and Orange Two-Color CW Laser Based on Single-Pass Second-Harmonic and Sum-Frequency Generation in MgO:PPLN
by Dismas K. Choge, Huai-Xi Chen, Yi-Bin Xu, Lei Guo, Guang-Wei Li and Wan-Guo Liang
Appl. Sci. 2018, 8(4), 629; https://doi.org/10.3390/app8040629 - 18 Apr 2018
Cited by 8 | Viewed by 4618
Abstract
We demonstrate a compact blue and orange-two color continuous wave laser source emitting at 487 nm and from 597.4 to 600.3 nm, respectively. The temperature tunable coherent orange radiation is achieved by frequency mixing 974 nm laser diode (LD) and a C-band amplified [...] Read more.
We demonstrate a compact blue and orange-two color continuous wave laser source emitting at 487 nm and from 597.4 to 600.3 nm, respectively. The temperature tunable coherent orange radiation is achieved by frequency mixing 974 nm laser diode (LD) and a C-band amplified spontaneous emission laser source while the temperature insensitive blue radiation is generated by second-order quasi-phase-matching frequency doubling of 974 nm LD. We implement the simultaneous nonlinear processes in a single magnesium oxide doped periodically poled lithium niobate bulk crystal without the need of an aperiodic design. Full article
(This article belongs to the Section Optics and Lasers)
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13 pages, 2072 KiB  
Article
Multi-Attributes, Utility-Based, Channel Quality Ranking Mechanism for Cognitive Radio Networks
by Youness Arjoune, Zakaria El Mrabet and Naima Kaabouch
Appl. Sci. 2018, 8(4), 628; https://doi.org/10.3390/app8040628 - 17 Apr 2018
Cited by 14 | Viewed by 3949
Abstract
Cognitive radio is an intelligent wireless solution that aims to enhance the access to the radio spectrum. In this technology, secondary users sense the radio spectrum, select the best channel among a pool of free channels, and determine the optimal transmission parameters to [...] Read more.
Cognitive radio is an intelligent wireless solution that aims to enhance the access to the radio spectrum. In this technology, secondary users sense the radio spectrum, select the best channel among a pool of free channels, and determine the optimal transmission parameters to meet their quality-of-service requirements while maximizing the spectral efficiency. Over the past decade, several channel-ranking mechanisms have been proposed. However, these mechanisms consider only the remaining idle time of the channel and exclude some crucial parameters. This convincingly demonstrates a strong need for a new channel quality-ranking model that jointly considers several parameters to select the best communication channel for transmission. This paper proposes a utility model that integrates several important parameters for ranking channels. First, we underline the importance of the process of the channel quality ranking. Then, we describe a multi-attributes, utility-based, channel quality-ranking model. Finally, we describe a series of experiments and their results, which show that our model effectively ranks the best communication channels first. Full article
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27 pages, 15039 KiB  
Article
Solar Radiation Parameters for Assessing Temperature Distributions on Bridge Cross-Sections
by Junqing Xue, Jianhui Lin, Bruno Briseghella, Habib Tabatabai and Baochun Chen
Appl. Sci. 2018, 8(4), 627; https://doi.org/10.3390/app8040627 - 17 Apr 2018
Cited by 33 | Viewed by 4895
Abstract
Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost- or time-prohibitive to obtain. A [...] Read more.
Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost- or time-prohibitive to obtain. A review of literature was carried out on estimation models for solar radiation parameters, including the global solar radiation, beam solar radiation and diffuse solar radiation. Solar radiation data from eight cities in Fujian Province in southeastern China were obtained on site. Solar radiation models applicable to Fujian, China were proposed and verified using the measured data. The linear Ångström–Page model (based on sunshine duration) can be used to estimate the daily global solar radiation. The Collares-Pereira and Rabl model and the Hottel model can be used to estimate the hourly global solar radiation and the beam solar radiation, respectively. Three bridges were chosen as case study, for which the temperature distribution on girder cross-sections were monitored on site. Finite element models (FEM) of cross-sections of bridge girders were implemented using the Midas program. The temperature–time curves obtained from FEM showed very close agreement with the measured values for summertime. Ignoring the solar radiation effect would result in lower and delayed temperature peaks. However, the influence of solar radiation on the temperature distribution in winter is negligible. Full article
(This article belongs to the Section Energy Science and Technology)
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10 pages, 272 KiB  
Article
Ultrasound-Based Liver Stiffness Surveillance in Patients Treated for Chronic Hepatitis B or C
by Sheng-Hung Chen and Cheng-Yuan Peng
Appl. Sci. 2018, 8(4), 626; https://doi.org/10.3390/app8040626 - 17 Apr 2018
Cited by 3 | Viewed by 5001
Abstract
Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining [...] Read more.
Evolving modes of ultrasound-based elastography have achieved promising validity and reliability for evaluating liver fibrosis. Liver stiffness (LS) is a valuable biomarker for modeling liver disease progression and regression on a continuous noncategorical scale as changes in LS per year or for determining the LS progression or regression rate for refining LS measurement (LSM)-based prognostics. The paradigm of LSMs has altered the focus from liver fibrosis staging alone to comprehensive liver-relevant risk estimations. However, diverse ranges of cohort characteristics, disease types, surveillance protocols and timeframes, necroinflammatory resolutions or biochemical responses (BRs), factors explaining the magnitude or kinetics in LS change, virologic responses (VRs), fibrosis reversals (FRs), and noninvasive surveillance results have rarely been reviewed collectively. Elastography-based LS surveillance alone conveys chronological and valuable patient information and assists in characterizing worldwide patient cohorts under antiviral treatment by delineating the concurrent time elapsed, VR, BR, and FR. In groups with uniform VRs to direct-acting antivirals for chronic hepatitis C and nucleoside and nucleotide analogs for chronic hepatitis B, decline in LS can be explained using concurrent BR from 24 weeks to 3 years, followed by FR and the time elapsed. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
15 pages, 19577 KiB  
Article
Diagnostics of Hydrogen-Containing Mixture Compression by a Two-Stage Piston Compressor with Cooling Demand Prediction
by Tomáš Brestovič, Mária Čarnogurská, Miroslav Příhoda, Peter Lukáč, Marián Lázár, Natália Jasminská and Romana Dobáková
Appl. Sci. 2018, 8(4), 625; https://doi.org/10.3390/app8040625 - 17 Apr 2018
Cited by 7 | Viewed by 4734
Abstract
The present article describes the diagnostics of a compressor that is compressing a mixture of H2 and N2 on the basis of the results that were obtained by operational measurements of the flow rates and temperatures at selected compressor sites, as [...] Read more.
The present article describes the diagnostics of a compressor that is compressing a mixture of H2 and N2 on the basis of the results that were obtained by operational measurements of the flow rates and temperatures at selected compressor sites, as well as of the acoustic pressure levels during the full loading thereof. The obtained data were subsequently used to determine the limit conditions of the compressor operations in terms of the cooling capacity. A thermodynamic analysis of the compression of the H2/N2 gas mixture was carried out with subsequent heat and energy flow calculation and the determination of the minimum cooling water flow rate that is required to ensure the continuous compressor operations. Full article
(This article belongs to the Special Issue Green Energy and Applications)
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