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Appl. Sci., Volume 7, Issue 10 (October 2017)

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Cover Story Since the proposed actuator is so soft and flexible, it can be easily embedded into flexible or [...] Read more.
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Editorial

Jump to: Research, Review, Other

Open AccessEditorial Editorial for Special Issue: “Heat Transfer Processes in Oscillatory Flow Conditions”
Appl. Sci. 2017, 7(10), 994; doi:10.3390/app7100994
Received: 22 September 2017 / Accepted: 25 September 2017 / Published: 26 September 2017
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Abstract
Heat exchange processes in steady flows have been studied extensively over the last two hundred years, and are now part of undergraduate syllabi of most engineering courses [...]
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(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)
Open AccessEditorial Imagining the Future of the Internal Combustion Engine for Ground Transport in the Current Context
Appl. Sci. 2017, 7(10), 1001; doi:10.3390/app7101001
Received: 20 September 2017 / Revised: 21 September 2017 / Accepted: 26 September 2017 / Published: 28 September 2017
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Abstract
Internal Combustion Engines (ICEs) are the main propulsion systems for ground transport, both in on-road and off-road applications [...]
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(This article belongs to the Special Issue Internal Combustion Engines (ICE) for Ground Transport)
Open AccessEditorial Special Feature Development and Application of Optical Coherence Tomography (OCT)
Appl. Sci. 2017, 7(10), 1507; doi:10.3390/app7101507
Received: 8 October 2017 / Revised: 12 October 2017 / Accepted: 12 October 2017 / Published: 13 October 2017
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Abstract
To celebrate the 25th anniversary of the introduction of OCT, the special feature issue entitled “Development and Application of Optical Coherence Tomography (OCT)” had been initiated [...]
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(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))

Research

Jump to: Editorial, Review, Other

Open AccessArticle Indistinguishability Operators Applied to Task Allocation Problems in Multi-Agent Systems
Appl. Sci. 2017, 7(10), 963; doi:10.3390/app7100963
Received: 2 August 2017 / Revised: 1 September 2017 / Accepted: 16 September 2017 / Published: 21 September 2017
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Abstract
In this paper we show an application of indistinguishability operators to model response functions. Such functions are used in the mathematical modeling of the task allocation problem in multi-agent systems when the stimulus, perceived by the agent, to perform a task is assessed
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In this paper we show an application of indistinguishability operators to model response functions. Such functions are used in the mathematical modeling of the task allocation problem in multi-agent systems when the stimulus, perceived by the agent, to perform a task is assessed by means of the response threshold model. In particular, we propose this kind of operators to represent a response function when the stimulus only depends on the distance between the agent and a determined task, since we prove that two celebrated response functions used in the literature can be reproduced by appropriate indistinguishability operators when the stimulus only depends on the distance to each task that must be carried out. Despite the fact there is currently no systematic method to generate response functions, this paper provides, for the first time, a theoretical foundation to generate them and study their properties. To validate the theoretical results, the aforementioned indistinguishability operators have been used to simulate, with MATLAB, the allocation of a set of tasks in a multi-robot system with fuzzy Markov chains. Full article
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Open AccessArticle Bar-Wave Calibration of Acoustic Emission Sensors
Appl. Sci. 2017, 7(10), 964; doi:10.3390/app7100964
Received: 30 August 2017 / Revised: 16 September 2017 / Accepted: 18 September 2017 / Published: 21 September 2017
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Abstract
This study extended a bar-wave calibration method for acoustic emission (AE) sensors. It combined laser interferometer displacement measurements and the wave propagation medium of a long bar, excited at its end with an ultrasonic transducer driven by a pulser. Receiving bar-wave sensitivities of
[...] Read more.
This study extended a bar-wave calibration method for acoustic emission (AE) sensors. It combined laser interferometer displacement measurements and the wave propagation medium of a long bar, excited at its end with an ultrasonic transducer driven by a pulser. Receiving bar-wave sensitivities of 16 types of AE sensors were measured and compared to their receiving sensitivities to normally incident waves. The two types of the receiving sensitivity always differed for a given AE sensor. The bar-wave sensitivities of R6a sensors resembled their surface-wave sensitivities, indicating that the bar-wave sensitivities can represent the surface-wave sensitivities in typical AE applications. Some bar-wave modes were identified by comparing peaks found on observed Choi-Williams transform spectrograms with the positions on the dispersion curves for bar waves, calculated with the SAFE procedure. However, numerous bar-wave modes prevented exact identification, especially above 500 kHz. Aperture effects contributed to the sensitivity reduction at higher frequencies and to more fluctuating bar-wave receiving sensitivities even for sensors with smooth or flat receiving sensitivities to normally incident waves. Spectral dips observed in bar-wave results can be accounted for by aperture effect predictions reasonably well. For the selection of AE sensors, one needs to use the appropriate type of sensitivities considering waves to be detected. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Registration of Urban Aerial Image and LiDAR Based on Line Vectors
Appl. Sci. 2017, 7(10), 965; doi:10.3390/app7100965
Received: 30 July 2017 / Revised: 14 September 2017 / Accepted: 19 September 2017 / Published: 21 September 2017
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Abstract
In a traditional registration of a single aerial image with airborne light detection and ranging (LiDAR) data using linear features that regard line direction as a control or linear features as constraints in the solution, lacking the constraint of linear position leads to
[...] Read more.
In a traditional registration of a single aerial image with airborne light detection and ranging (LiDAR) data using linear features that regard line direction as a control or linear features as constraints in the solution, lacking the constraint of linear position leads to the error propagation of the adjustment model. To solve this problem, this paper presents a line vector-based registration mode (LVR) in which image rays and LiDAR lines are expressed by a line vector that integrates the line direction and the line position. A registration equation of line vector is set up by coplanar imaging rays and corresponding control lines. Three types of datasets consisting of synthetic, theInternational Society for Photogrammetry and Remote Sensing (ISPRS) test project, and real aerial data are used. A group of progressive experiments is undertaken to evaluate the robustness of the LVR. Experimental results demonstrate that the integrated line direction and the line position contributes a great deal to the theoretical and real accuracies of the unknowns, as well as the stability of the adjustment model. This paper provides a new suggestion that, for a single image and LiDAR data, registration in urban areas can be accomplished by accommodating rich line features. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Hospital Recommendation System Based on Patient Satisfaction Survey
Appl. Sci. 2017, 7(10), 966; doi:10.3390/app7100966
Received: 28 July 2017 / Revised: 10 September 2017 / Accepted: 11 September 2017 / Published: 21 September 2017
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Abstract
Surveys are used by hospitals to evaluate patient satisfaction and to improve general hospital operations. Collected satisfaction data is usually represented to the hospital administration by using statistical charts and graphs. Although such visualization is helpful, typically no deeper data analysis is performed
[...] Read more.
Surveys are used by hospitals to evaluate patient satisfaction and to improve general hospital operations. Collected satisfaction data is usually represented to the hospital administration by using statistical charts and graphs. Although such visualization is helpful, typically no deeper data analysis is performed to identify important factors which contribute to patient satisfaction. This work presents an unsupervised data-driven methodology for analyzing patient satisfaction survey data. The goal of the proposed exploratory data analysis is to identify patient communities with similar satisfaction levels and the major factors, which contribute to their satisfaction. This type of data analysis will help hospitals to pinpoint the prevalence of certain satisfaction factors in specific patient communities or clusters of individuals and to implement more proactive measures to improve patient experience and care. To this end, two layers of data analysis is performed. In the first layer, patients are clustered based on their responses to the survey questions. Each cluster is then labeled according to its salient features. In the second layer, the clusters of first layer are divided into sub-clusters based on patient demographic data. Associations are derived between the salient features of each cluster and its sub-clusters. Such associations are ranked and validated by using standard statistical tests. The associations derived by this methodology are turned into comments and recommendations for healthcare providers and patients. Having applied this method on patient and survey data of a hospital resulted in 19 recommendations where 10 of them were statistically significant with chi-square test’s p-value less than 0.5 and an odds ratio z-test’s p-value of more than 2 or less than −2. These associations not only are statistically significant but seems rational too. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle Computational and Experimental Study on Molecular Structure of Benzo[g]pyrimido[4,5-b]quinoline Derivatives: Preference of Linear over the Angular Isomer
Appl. Sci. 2017, 7(10), 967; doi:10.3390/app7100967
Received: 22 August 2017 / Revised: 11 September 2017 / Accepted: 16 September 2017 / Published: 21 September 2017
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Abstract
A series of 5-aryl-2-methylthio-5,12-dihydrobenzo[g]pyrimido[4,5-b]quinoline-4,6,11(3H)-trione was synthesized through an environmental friendly multicomponent methodology and characterized with FT-IR (Fourier Transform infrared spectroscopy), 1H NMR (Nuclear Magnetic Resonance ), 13C NMR and GC-MS (gas chromatography-mass spectrometry). The 5-(4-methoxyphenyl)-2-methylthio-5,12-dihydrobenzo[
[...] Read more.
A series of 5-aryl-2-methylthio-5,12-dihydrobenzo[g]pyrimido[4,5-b]quinoline-4,6,11(3H)-trione was synthesized through an environmental friendly multicomponent methodology and characterized with FT-IR (Fourier Transform infrared spectroscopy), 1H NMR (Nuclear Magnetic Resonance ), 13C NMR and GC-MS (gas chromatography-mass spectrometry). The 5-(4-methoxyphenyl)-2-methylthio-5,12-dihydrobenzo[g]pyrimido[4,5-b]quinoline-4,6,11(3H)-trione 4c compound was characterized by X-ray single crystal diffraction. The geometry of 4c has been fully optimized using DFT (Density functional theory), B3LYP functional and 6-31G(d,p) basis set, thus establishing the ground state energy and thermodynamic features for the mentioned compound, which are in accordance with the experimental data and the crystal structure. The experimental results reveal a strong preference for the regioselective formation of 4c linear four fused rings over the angular four fused and suggest a possible kinetic control in product formation. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Application of Deep Networks to Oil Spill Detection Using Polarimetric Synthetic Aperture Radar Images
Appl. Sci. 2017, 7(10), 968; doi:10.3390/app7100968
Received: 29 July 2017 / Revised: 10 September 2017 / Accepted: 15 September 2017 / Published: 21 September 2017
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Abstract
Polarimetric synthetic aperture radar (SAR) remote sensing provides an outstanding tool in oil spill detection and classification, for its advantages in distinguishing mineral oil and biogenic lookalikes. Various features can be extracted from polarimetric SAR data. The large number and correlated nature of
[...] Read more.
Polarimetric synthetic aperture radar (SAR) remote sensing provides an outstanding tool in oil spill detection and classification, for its advantages in distinguishing mineral oil and biogenic lookalikes. Various features can be extracted from polarimetric SAR data. The large number and correlated nature of polarimetric SAR features make the selection and optimization of these features impact on the performance of oil spill classification algorithms. In this paper, deep learning algorithms such as the stacked autoencoder (SAE) and deep belief network (DBN) are applied to optimize the polarimetric feature sets and reduce the feature dimension through layer-wise unsupervised pre-training. An experiment was conducted on RADARSAT-2 quad-polarimetric SAR image acquired during the Norwegian oil-on-water exercise of 2011, in which verified mineral, emulsions, and biogenic slicks were analyzed. The results show that oil spill classification achieved by deep networks outperformed both support vector machine (SVM) and traditional artificial neural networks (ANN) with similar parameter settings, especially when the number of training data samples is limited. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle A Precise Positioning Method for a Puncture Robot Based on a PSO-Optimized BP Neural Network Algorithm
Appl. Sci. 2017, 7(10), 969; doi:10.3390/app7100969
Received: 18 July 2017 / Revised: 12 September 2017 / Accepted: 18 September 2017 / Published: 21 September 2017
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Abstract
The problem of inverse kinematics is fundamental in robot control. Many traditional inverse kinematics solutions, such as geometry, iteration, and algebraic methods, are inadequate in high-speed solutions and accurate positioning. In recent years, the problem of robot inverse kinematics based on neural networks
[...] Read more.
The problem of inverse kinematics is fundamental in robot control. Many traditional inverse kinematics solutions, such as geometry, iteration, and algebraic methods, are inadequate in high-speed solutions and accurate positioning. In recent years, the problem of robot inverse kinematics based on neural networks has received extensive attention, but its precision control is convenient and needs to be improved. This paper studies a particle swarm optimization (PSO) back propagation (BP) neural network algorithm to solve the inverse kinematics problem of a UR3 robot based on six degrees of freedom, overcoming some disadvantages of BP neural networks. The BP neural network improves the convergence precision, convergence speed, and generalization ability. The results show that the position error is solved by the research method with respect to the UR3 robot inverse kinematics with the joint angle less than 0.1 degrees and the output end tool less than 0.1 mm, achieving the required positioning for medical puncture surgery, which demands precise positioning of the robot to less than 1 mm. Aiming at the precise application of the puncturing robot, the preliminary experiment has been conducted and the preliminary results have been obtained, which lays the foundation for the popularization of the robot in the medical field. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle Supporting an Object-Oriented Approach to Unit Generator Development: The Csound Plugin Opcode Framework
Appl. Sci. 2017, 7(10), 970; doi:10.3390/app7100970
Received: 31 July 2017 / Revised: 8 September 2017 / Accepted: 18 September 2017 / Published: 21 September 2017
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Abstract
This article presents a new framework for unit generator development for Csound, supporting a full object-oriented programming approach. It introduces the concept of unit generators and opcodes, and its centrality with regards to music programming languages in general, and Csound in specific. The
[...] Read more.
This article presents a new framework for unit generator development for Csound, supporting a full object-oriented programming approach. It introduces the concept of unit generators and opcodes, and its centrality with regards to music programming languages in general, and Csound in specific. The layout of an opcode from the perspective of the Csound C-language API is presented, with some outline code examples. This is followed by a discussion which places the unit generator within the object-oriented paradigm and the motivation for a full C++ programming support, which is provided by the Csound Plugin Opcode Framework (CPOF). The design of CPOF is then explored in detail, supported by several opcode examples. The article concludes by discussing two key applications of object-orientation and their respective instances in the Csound code base. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater
Appl. Sci. 2017, 7(10), 971; doi:10.3390/app7100971
Received: 25 August 2017 / Revised: 15 September 2017 / Accepted: 19 September 2017 / Published: 22 September 2017
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Abstract
This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This
[...] Read more.
This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This study also examined the progressive changes in the pore structures of the FSW and SSW samples over time. The results show that the SSW sample is significantly more effective in the uptake of chloride ions compared to the FSW sample at 28 days of curing. While the FSW sample forms Cl-bearing zeolites (Cl-chabazite and Cl-sodalite) (possibly with similar types of geopolymeric gels), the SSW sample synthesizes Cl-bearing, layered double hydroxides (LDH) (Cl-hydrocalumite and Cl-hydrotalcite). Although both samples involve Cl-binding phases, the FSW sample is likely to be less efficient because it largely produces zeolites (or similar geopolymeric gels) with no Cl-binding capability (i.e., zeolites X and Y). Meanwhile, the SSW sample produces Cl-bearing LDH phases as well as C-S-H(I), which can physically adsorb chloride. The SSW sample exhibits both pore-size refinement and porosity reduction over time, while the FSW sample only exhibits pore-size refinement. Therefore, the SSW system is more advantageous in the use of seawater because it more effectively prevents Cl ingression due to greater impermeability. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Enhanced Design of a Soft Thin-Film Vibrotactile Actuator Based on PVC Gel
Appl. Sci. 2017, 7(10), 972; doi:10.3390/app7100972
Received: 26 August 2017 / Revised: 19 September 2017 / Accepted: 20 September 2017 / Published: 22 September 2017
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Abstract
We fabricated a soft thin-film vibrotactile actuator, which can be easily inserted into wearable devices, based on an electroactive PVC gel. One of the most important factors in fabricating a soft and thin vibrotactile actuator is to create vibrational force strong enough to
[...] Read more.
We fabricated a soft thin-film vibrotactile actuator, which can be easily inserted into wearable devices, based on an electroactive PVC gel. One of the most important factors in fabricating a soft and thin vibrotactile actuator is to create vibrational force strong enough to stimulate human skin in a wide frequency range. To achieve this, we investigate the working principle of the PVC gel and suggest a new structure in which most of electric energy contributes to the deformation of the PVC gel. Due to this structure, the vibrational amplitude of the proposed PVC gel actuator could considerably increase (0.816 g (g = 9.8 m/s2) at resonant frequency). The vibrotactile amplitude is proportional to the amount of input voltage. It increased from 0.05 g up to 0.416 g with increasing applied voltages from 200 V to 1 kV at 1 Hz. The experimental results show that the proposed actuator can create a variety of haptic sensations. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Multivariate Analysis of Laser-Induced Tissue Ablation: Ex Vivo Liver Testing
Appl. Sci. 2017, 7(10), 974; doi:10.3390/app7100974
Received: 8 September 2017 / Revised: 13 September 2017 / Accepted: 20 September 2017 / Published: 22 September 2017
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Abstract
A number of laser parameters are often regulated to enhance ablation efficiency during laser surgery. As one of clinical treatments, laser removal of benign prostate hyperplasia has been well accepted by surgical urologists. However, due to complex interactions of the surgical parameters, the
[...] Read more.
A number of laser parameters are often regulated to enhance ablation efficiency during laser surgery. As one of clinical treatments, laser removal of benign prostate hyperplasia has been well accepted by surgical urologists. However, due to complex interactions of the surgical parameters, the procedure is still lengthy and dependent upon the surgeon’s skill and experience. The aim of the current study is to evaluate the feasibility of response surface method (RSM) to comprehend ablative interactions of multi-parameters and to identify the optimal ablation rate (AR). As a surrogate model in the feasibility study, bovine liver tissue was utilized for ex vivo ablation testing. Three laser parameters pertinent to laser prostatectomy were selected: power (P), treatment speed (TS), and beam spot (BS). As a three-level fractional factorial RSM, Box Behnken design (BBD) was employed to identify the range of each parameter for achieving the optimal AR. The results showed that regardless of TS, AR was linearly contingent on both P and BS due to high irradiance. TS of 6~7 mm/s induced the maximal AR when P of 180 W and BS of 0.4 mm2. The corresponding volumetric density energy yielded an ablation volume of 80 mm2, which was close to a transition to volumetric saturation. The BBD-based model showed a good agreement with the experimental data in terms of ablation volume. The proposed multivariate parametric analysis can be an efficient design method to identify the optimal conditions for laser therapeutics. Further investigations will be performed on prostatic tissue to validate the proposed approach and to explore various optimization processes. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Assessing the Performance of Thermal Inertia and Hydrus Models to Estimate Surface Soil Water Content
Appl. Sci. 2017, 7(10), 975; doi:10.3390/app7100975
Received: 18 August 2017 / Revised: 15 September 2017 / Accepted: 19 September 2017 / Published: 22 September 2017
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Abstract
The knowledge of soil water content (SWC) dynamics in the upper soil layer is important for several hydrological processes. Due to the difficulty of assessing the spatial and temporal SWC dynamics in the field, some model-based approaches have been proposed during the last
[...] Read more.
The knowledge of soil water content (SWC) dynamics in the upper soil layer is important for several hydrological processes. Due to the difficulty of assessing the spatial and temporal SWC dynamics in the field, some model-based approaches have been proposed during the last decade. The main objective of this work was to assess the performance of two approaches to estimate SWC in the upper soil layer under field conditions: the physically-based thermal inertia and the Hydrus model. Their validity was firstly assessed under controlled laboratory conditions. Thermal inertia was firstly validated in laboratory conditions using the transient line heat source (TLHS) method. Then, it was applied in situ to analyze the dynamics of soil thermal properties under two extreme conditions of soil-water status (well-watered and air-dry), using proximity remote-sensed data. The model performance was assessed using sensor-based measurements of soil water content acquired through frequency (FDR) and time domain reflectometry (TDR). During the laboratory experiment, the Root Mean Square Error (RMSE) was 0.02 m3 m−3 for the Hydrus model and 0.05 m3 m−3 for the TLHS model approach. On the other hand, during the in situ experiment, the temporal variability of SWCs simulated by the Hydrus model and the corresponding values measured by the TDR method evidenced good agreement (RMSE ranging between 0.01 and 0.005 m3 m−3). Similarly, the average of the SWCs derived from the thermal diffusion model was fairly close to those estimated by Hydrus (spatially averaged RMSE ranging between 0.03 and 0.02 m3 m−3). Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle New Chaotic Dynamical System with a Conic-Shaped Equilibrium Located on the Plane Structure
Appl. Sci. 2017, 7(10), 976; doi:10.3390/app7100976
Received: 25 August 2017 / Revised: 11 September 2017 / Accepted: 20 September 2017 / Published: 22 September 2017
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Abstract
This paper presents a new autonomous deterministic dynamical system with equilibrium degenerated into a plane-oriented hyperbolic geometrical structure. It is demonstrated via numerical analysis and laboratory experiments that the discovered system has both a structurally stable strange attractor and experimentally measurable chaotic behavior.
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This paper presents a new autonomous deterministic dynamical system with equilibrium degenerated into a plane-oriented hyperbolic geometrical structure. It is demonstrated via numerical analysis and laboratory experiments that the discovered system has both a structurally stable strange attractor and experimentally measurable chaotic behavior. It is shown that the evolution of complex dynamics can be associated with a single parameter of a mathematical model and, due to one-to-one correspondence, to a single circuit parameter. Two-dimensional high resolution plots of the largest Lyapunov exponent and basins of attraction expressed in terms of final state energy are calculated and put into the context of the discovered third-order mathematical model and real chaotic oscillator. Both voltage- and current-mode analog chaotic oscillators are presented and verified by visualization of the typical chaotic attractor in a different fashion. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Film Thickness Estimation for the Oil Applied to the Inner Surface of Slim Tubes
Appl. Sci. 2017, 7(10), 977; doi:10.3390/app7100977
Received: 2 August 2017 / Revised: 19 September 2017 / Accepted: 20 September 2017 / Published: 22 September 2017
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Abstract
The article deals with the approximation of the results of experimental measurement of coating of the inner surface of slim pipes with special oil, using a dispersion oil fraction. The reason for such treatment of the inner surface of the tubes is the
[...] Read more.
The article deals with the approximation of the results of experimental measurement of coating of the inner surface of slim pipes with special oil, using a dispersion oil fraction. The reason for such treatment of the inner surface of the tubes is the anti-corrosion protection or various other requirements. The oil manufacturer prescribes the minimum required layer to guarantee the anti-corrosion protection parameters. Therefore, it is advisable to know the most exact coating parameters for different pipe diameters. The measured results give us an assumption of how much oil is sufficient to coat the inside of a pipe. The main idea lies in the correct estimation of coefficients in the three-parameter exponential dependence. For the initial estimates, Nelder–Mead’s minimization method was used. The condition for meeting the lower estimate of the minimum thickness of the oil layer was determined. Following graphic processing of minimization of individual pipe diameters, in some cases, the coefficients were adjusted manually. The result is that the oil thickness depends on the distance of the investigated point from the beginning of the tube, or on the point of entry of the dispersion oil fraction. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle CEPP: Perceiving the Emotional State of the User Based on Body Posture
Appl. Sci. 2017, 7(10), 978; doi:10.3390/app7100978
Received: 22 August 2017 / Revised: 6 September 2017 / Accepted: 18 September 2017 / Published: 22 September 2017
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Abstract
Much research has been conducted in the area of face and gesture recognition in order to classify one’s emotional state. Surprisingly, utilizing computerized algorithms which recognize emotional conditions based on body postures has not yet been systematically developed. In this paper, we propose
[...] Read more.
Much research has been conducted in the area of face and gesture recognition in order to classify one’s emotional state. Surprisingly, utilizing computerized algorithms which recognize emotional conditions based on body postures has not yet been systematically developed. In this paper, we propose a novel method, Computerized Emotion Perception based on Posture (CEPP), to determine the emotional state of the user. This method extracts features from body postures and estimates the emotional state by computing a similarity distance. With the proposed algorithm, we will provide new insights into automatically recognizing one’s emotional state. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle 3D-Printed Super-Wideband Spidron Fractal Cube Antenna with Laminated Copper
Appl. Sci. 2017, 7(10), 979; doi:10.3390/app7100979
Received: 3 August 2017 / Revised: 4 September 2017 / Accepted: 19 September 2017 / Published: 22 September 2017
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Abstract
In this paper, a 3D-printed super-wideband (SWB) Spidron fractal cube antenna is proposed. The Spidron fractal configuration is utilized as a self-complementary structure on each face of a 3D frame to attain SWB characteristics. The antenna is excited through a tapered microstrip balun
[...] Read more.
In this paper, a 3D-printed super-wideband (SWB) Spidron fractal cube antenna is proposed. The Spidron fractal configuration is utilized as a self-complementary structure on each face of a 3D frame to attain SWB characteristics. The antenna is excited through a tapered microstrip balun for both mode transforming and impedance matching. A prototype of the proposed antenna, including the 3D frame fabricated with the help of a 3D printer and Spidron fractal patches made of copper tape, is experimentally verified. The measured −10 dB reflection ratio bandwidth is 34:1 (0.44–15.38 GHz). The peak gain varies from 3.42 to 9.29 dBi within the operating frequency bandwidth. The measured radiation patterns are nearly omnidirectional at all operating frequency bands. Full article
(This article belongs to the Special Issue 3D Printed Antennas)
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Open AccessArticle Postharvest Behavior of Bioactive Compounds in Tomato Fruits Treated with Cu Nanoparticles and NaCl Stress
Appl. Sci. 2017, 7(10), 980; doi:10.3390/app7100980
Received: 28 August 2017 / Revised: 14 September 2017 / Accepted: 20 September 2017 / Published: 23 September 2017
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Abstract
Tomatoes are important for human diet due to their content of bioactive compounds. However, is little known about behavior of these compounds during fruit shelf life. The goal of this research was to evaluate the effects on bioactive compounds of tomato fruits stored
[...] Read more.
Tomatoes are important for human diet due to their content of bioactive compounds. However, is little known about behavior of these compounds during fruit shelf life. The goal of this research was to evaluate the effects on bioactive compounds of tomato fruits stored during different times and conditions, obtained from tomato plants developed under conditions of saline stress and with the application of copper nanoparticles. Four treatments were evaluated: foliar spray of copper nanoparticles (250 mg L−1) with or without saline stress, only saline stress, and the absolute control. The results show that application of copper nanoparticles has a positive effect on the accumulation of bioactive compounds such as total phenols, β-carotene, and vitamin C. The saline stress during the development of tomato plants causes a decrease of the bioactive compounds as well as antioxidant capacity in tomato fruits. However, this negative effect can be reduced with the application of copper nanoparticles. The application of copper nanoparticles may be a technique to increase and maintain the content of bioactive compounds in tomato fruits and can be an effective alternative to diminish the negative effects on bioactive compounds caused by saline stress. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
Open AccessArticle Methods for Determination of the Degree of Iron Oxidation in LiFePO4
Appl. Sci. 2017, 7(10), 981; doi:10.3390/app7100981
Received: 23 August 2017 / Revised: 20 September 2017 / Accepted: 20 September 2017 / Published: 24 September 2017
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Abstract
The disposal of LiFePO4 (LFP) cathode material through oxidation in an air atmosphere is explained by its high chemical activity and high surface area (especially for nanoparticles). In this article, new methods for the determination of the degree of iron oxidation in
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The disposal of LiFePO4 (LFP) cathode material through oxidation in an air atmosphere is explained by its high chemical activity and high surface area (especially for nanoparticles). In this article, new methods for the determination of the degree of iron oxidation in LFP (oxidation degree) are taken into consideration, specifically those which do not require complicated hardware support. The proposed methods are based on electrochemical oxidation (coulometric method) and chemical oxidation (chemical oxidation in alkaline and acidic solutions). As an arbitration method for analyzing the iron state, the method of Mössbauer spectroscopy (being the most proven and reliable method) was chosen. With respect to the proposed methods for determination of the oxidation degree, the most reliable and quick approach is the titrimetric method (oxidation in an acidic medium), which is in good correlation with Mossbauer spectroscopy. The coulometric method is also able to determine the material oxidation degree (with some approximation), but it requires a number of conditions in order to eliminate errors. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Residual Stress and Deformation Analysis in Butt Welding on 6 mm SUS304 Steel with Jig Constraints Using Gas Metal Arc Welding
Appl. Sci. 2017, 7(10), 982; doi:10.3390/app7100982
Received: 13 August 2017 / Revised: 20 September 2017 / Accepted: 20 September 2017 / Published: 23 September 2017
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Abstract
This article proposes a novel method for analyzing residual stress and deformation in butt welding on 6 mm SUS304 stainless steel plates, using MSC.MARC, a commercial finite element method software, to find the best location for jig fixtures that will minimize welding deformation.
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This article proposes a novel method for analyzing residual stress and deformation in butt welding on 6 mm SUS304 stainless steel plates, using MSC.MARC, a commercial finite element method software, to find the best location for jig fixtures that will minimize welding deformation. Simulation and experimental studies show that a distance of 100 mm between the jig center and the welding bead center is best for inhibiting welding deformation when the jigs experience downward displacement at 0 mm on the steel plate; the total displacement is only about 1.1 mm in the case of a 300 × 250 × 6 mm SUS304 steel plate. In addition, a numerical model shows that four jigs with pitches of 200 mm can better reduce welding deformation than six jigs with pitches of 100 mm. The largest residual stress after welding occurs around the weld bead center, and the residual stress away from the welding bead center increases gradually when jigs have been applied on the steel plate to prevent deformation. The reaction force of the jigs on the steel plate has no further effect in reducing deformation. We conclude that commercially available jigs can inhibit deformation during the welding process. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)
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Open AccessArticle A Software Reliability Model with a Weibull Fault Detection Rate Function Subject to Operating Environments
Appl. Sci. 2017, 7(10), 983; doi:10.3390/app7100983
Received: 21 August 2017 / Revised: 20 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
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Abstract
When software systems are introduced, these systems are used in field environments that are the same as or close to those used in the development-testing environments; however, they may also be used in many different locations that may differ from the environment in
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When software systems are introduced, these systems are used in field environments that are the same as or close to those used in the development-testing environments; however, they may also be used in many different locations that may differ from the environment in which they were developed and tested. As such, it is difficult to improve software reliability for a variety of reasons, such as a given environment, or a bug location in code. In this paper, we propose a new software reliability model that takes into account the uncertainty of operating environments. The explicit mean value function solution for the proposed model is presented. Examples are presented to illustrate the goodness of fit of the proposed model and several existing non-homogeneous Poisson process (NHPP) models and confidence intervals of all models based on two sets of failure data collected from software applications. The results show that the proposed model fits the data more closely than other existing NHPP models to a significant extent. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Production of Aerated Foamed Concrete with Industrial Waste from the Gems and Jewels Sector of Rio Grande do Sul-Brazil
Appl. Sci. 2017, 7(10), 985; doi:10.3390/app7100985
Received: 29 August 2017 / Accepted: 21 September 2017 / Published: 26 September 2017
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Abstract
The use of solid waste for the development of new building materials has been an alternative to reduce environmental impacts through the preservation of natural resources. In this context, this paper evaluates the possibility of using agate gemstone waste, called rolled powder, which
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The use of solid waste for the development of new building materials has been an alternative to reduce environmental impacts through the preservation of natural resources. In this context, this paper evaluates the possibility of using agate gemstone waste, called rolled powder, which basically consists of silica (SiO2), in the manufacture of aerated foamed concrete blocks completely replacing the natural sand. Preformed foam was used as the air entrained by mechanical stirring with a mixture of natural foaming agents derived from coconut. To produce test specimens, the water/cement ratio and foam concentrations were varied, with three and four levels, respectively. The specimens were left for 28 days at room temperature to be cured, and then underwent analysis to determine their compressive strength, density, and the distribution of air-voids. The experiments demonstrated that the best water/cement ratio was 1.28 for 18% (of total solid mass) addition of foam, which generated a sample with a density of 430 kg/m3, and a compressive strength of 1.07 MPa. The result for compressive strength is 11% smaller than the requirements of the Brazilian standard (NBR 13438) for autoclaved aerated concrete blocks, but the results are promising. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Experimental Study on Vibration Control of a Submerged Pipeline Model by Eddy Current Tuned Mass Damper
Appl. Sci. 2017, 7(10), 987; doi:10.3390/app7100987
Received: 4 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
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Abstract
Undesirable vibrations occurring in undersea pipeline structures due to ocean currents may shorten the lifecycle of pipeline structures and even lead to their failure. Therefore, it is desirable to find a feasible and effective device to suppress the subsea vibration. Eddy current tuned
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Undesirable vibrations occurring in undersea pipeline structures due to ocean currents may shorten the lifecycle of pipeline structures and even lead to their failure. Therefore, it is desirable to find a feasible and effective device to suppress the subsea vibration. Eddy current tuned mass damper (ECTMD), which employs the damping force generated by the relative movement of a non-magnetic conductive metal (such as copper or aluminum) through a magnetic field, is demonstrated to be an efficient way in structural vibration control. However, the feasibility and effectiveness of ECTMD in a seawater environment has not been reported on before. In this paper, an experiment is conducted to validate the feasibility of an eddy current damper in a seawater environment. A submerged pipeline is used as the controlled structure to experimentally study the effectiveness of ECTMD. The dynamic properties of the submerged pipeline are obtained from dynamic tests and the finite element method (FEM). The optimum design of TMD with a linear spring-damper element for a damped primary structure is carried out through numerical optimization procedures and is used to determine the optimal frequency tuning ratio and damping ratio of ECTMD. In addition, the performance of ECTMD to control the submerged pipeline model is respectively studied in free vibration case and forced vibration case. The results show that the damping provided by eddy current in a seawater environment is only slightly varied compared to that in an air environment. With the optimal ECTMD control, vibration response of the submerged pipeline is significantly decreased. Full article
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Open AccessArticle A 2D-View Depth Image- and CNN-Based 3D Model Identification Method
Appl. Sci. 2017, 7(10), 988; doi:10.3390/app7100988
Received: 9 August 2017 / Revised: 15 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
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Abstract
With the rapid development of three-dimensional (3D) technology and an increase in the number of available models, issues with copyright protection of 3D models are inevitable. In this paper, we propose a 2D-view depth image- and convolutional neural network (CNN)-based 3D model identification
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With the rapid development of three-dimensional (3D) technology and an increase in the number of available models, issues with copyright protection of 3D models are inevitable. In this paper, we propose a 2D-view depth image- and convolutional neural network (CNN)-based 3D model identification method. To identify a 3D model, we first need an adequate number of the modified versions that could be made by copyright infringers. Then, they can be represented by a number of 2D-view depth images that are captured from evenly distributed vertices on a regular convex polyhedron. Finally, a CNN is trained by these depth images to acquire the capability of identifying the 3D model. The experiment carried out with the dataset of Shape Retrieval Contest 2015 (SHREC’15): Non-Rigid 3D Shape Retrieval shows the practicability of our method, which yields 93.5% accuracy. The effectiveness of the proposed method is demonstrated via evaluation in the latest standard benchmark SHREC’17 Deformable Shape Retrieval with Missing Parts. It clearly shows superior or comparable performance to state-of-the-art methods, shown by the fact that it is in the top three of the 11 participating methods (without counting different runs). Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Robust Background Subtraction via the Local Similarity Statistical Descriptor
Appl. Sci. 2017, 7(10), 989; doi:10.3390/app7100989
Received: 5 September 2017 / Revised: 19 September 2017 / Accepted: 21 September 2017 / Published: 25 September 2017
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Abstract
Background subtraction based on change detection is the first step in many computer vision systems. Many background subtraction methods have been proposed to detect foreground objects through background modeling. However, most of these methods are pixel-based, which only use pixel-by-pixel comparisons, and a
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Background subtraction based on change detection is the first step in many computer vision systems. Many background subtraction methods have been proposed to detect foreground objects through background modeling. However, most of these methods are pixel-based, which only use pixel-by-pixel comparisons, and a few others are spatial-based, which take the neighborhood of each analyzed pixel into consideration. In this paper, inspired by a illumination- invariant feature based on locality-sensitive histograms proposed for object tracking, we first develop a novel texture descriptor named the Local Similarity Statistical Descriptor (LSSD), which calculates the similarity between the current pixel and its neighbors. The LSSD descriptor shows good performance in illumination variation and dynamic background scenes. Then, we model each background pixel representation with a combination of color features and LSSD features. These features are then embedded in a low-cost and highly efficient background modeling framework. The color and texture features have their own merits and demerits; they can compensate each other, resulting in better performance. Both quantitative and qualitative evaluations carried out on the change detection dataset are provided to demonstrate the effectiveness of our method. Full article
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Open AccessArticle A Study of Two Dimensional Tomography Reconstruction of Temperature and Gas Concentration in a Combustion Field Using TDLAS
Appl. Sci. 2017, 7(10), 990; doi:10.3390/app7100990
Received: 30 July 2017 / Revised: 11 September 2017 / Accepted: 20 September 2017 / Published: 25 September 2017
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Abstract
Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas concentration and temperature are realized using an algebraic reconstruction technique (ART). The influence of the beam distribution and grid size on combustion field reconstruction is investigated to attain optimal
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Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas concentration and temperature are realized using an algebraic reconstruction technique (ART). The influence of the beam distribution and grid size on combustion field reconstruction is investigated to attain optimal reconstruction results with a limited number of beams. Under limited optical-path numbers, it shows that a better spatial resolution is attainable only when the laser beam paths are vertical and parallel to the symmetry axis of the combustion field. Furthermore, experiments with 16 beam paths using one and two flat flame combustion fields are carried out in different fuel-air equivalence ratios under room temperature. The results are in agreement with the simulation results, and the time resolution is less than 1 s. Full article
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Open AccessArticle Analysis of the Aging Processes of Writing Ink: Raman Spectroscopy versus Gas Chromatography Aspects
Appl. Sci. 2017, 7(10), 991; doi:10.3390/app7100991
Received: 23 August 2017 / Revised: 14 September 2017 / Accepted: 19 September 2017 / Published: 26 September 2017
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Abstract
This work is devoted to the extremely popular but poorly developed scientific and forensic problem of the estimation of the actual dates of inscriptions placed on paper and made by ballpoint pens. It is shown that the degradation of writing inks with time
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This work is devoted to the extremely popular but poorly developed scientific and forensic problem of the estimation of the actual dates of inscriptions placed on paper and made by ballpoint pens. It is shown that the degradation of writing inks with time may be controlled via Raman spectroscopy and gas chromatography. The time intervals for the implementation of each of these methods were determined using the ratios of the Raman peak intensities as degradation characteristics rather than their absolute values. In turn, this eliminates the effect of the concentration of a dye. The mutual influence of the volatile components and dyes of writing inks was also investigated and the time interval within which such influence is critical was found. According to the obtained results, a new methodological scheme for determining the age of documents, which were created at least 40 months ago, was proposed. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Classification of Architectural Heritage Images Using Deep Learning Techniques
Appl. Sci. 2017, 7(10), 992; doi:10.3390/app7100992
Received: 7 September 2017 / Revised: 21 September 2017 / Accepted: 21 September 2017 / Published: 26 September 2017
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Abstract
The classification of the images taken during the measurement of an architectural asset is an essential task within the digital documentation of cultural heritage. A large number of images are usually handled, so their classification is a tedious task (and therefore prone to
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The classification of the images taken during the measurement of an architectural asset is an essential task within the digital documentation of cultural heritage. A large number of images are usually handled, so their classification is a tedious task (and therefore prone to errors) and habitually consumes a lot of time. The availability of automatic techniques to facilitate these sorting tasks would improve an important part of the digital documentation process. In addition, a correct classification of the available images allows better management and more efficient searches through specific terms, thus helping in the tasks of studying and interpreting the heritage asset in question. The main objective of this article is the application of techniques based on deep learning for the classification of images of architectural heritage, specifically through the use of convolutional neural networks. For this, the utility of training these networks from scratch or only fine tuning pre-trained networks is evaluated. All this has been applied to classifying elements of interest in images of buildings with architectural heritage value. As no datasets of this type, suitable for network training, have been located, a new dataset has been created and made available to the public. Promising results have been obtained in terms of accuracy and it is considered that the application of these techniques can contribute significantly to the digital documentation of architectural heritage. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A New Approach to Fall Detection Based on the Human Torso Motion Model
Appl. Sci. 2017, 7(10), 993; doi:10.3390/app7100993
Received: 26 July 2017 / Accepted: 18 September 2017 / Published: 26 September 2017
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Abstract
This paper presents a new approach for fall detection based on two features and their motion characteristics extracted from the human torso. The 3D positions of the hip center joint and the shoulder center joint in depth images are used to build a
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This paper presents a new approach for fall detection based on two features and their motion characteristics extracted from the human torso. The 3D positions of the hip center joint and the shoulder center joint in depth images are used to build a fall detection model named the human torso motion model (HTMM). Person’s torso angle and centroid height are imported as key features in HTMM. Once a person comes into the scene, the positions of these two joints are fetched to calculate the person’s torso angle. Whenever the angle is larger than a given threshold, the changing rates of the torso angle and the centroid height are recorded frame by frame in a given period of time. A fall can be identified when the above two changing rates reach the thresholds. By using the new feature, falls can be accurately and effectively distinguished from other fall-like activities, which are very difficult for other computer vision-based approaches to differentiate. Experiment results show that our approach achieved a detection accuracy of 97.5%, 98% true positive rate (TPR) and 97% true negative rate (TNR). Furthermore, the approach is time efficient and robust because of only calculating the changing rate of gravity and centroid height. Full article
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Open AccessArticle Principles and Application of Polyimide Fiber Bragg Gratings for Surface Strain Measurement
Appl. Sci. 2017, 7(10), 995; doi:10.3390/app7100995
Received: 11 August 2017 / Revised: 21 September 2017 / Accepted: 22 September 2017 / Published: 26 September 2017
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Abstract
Although theoretical investigation has demonstrated that fewer strain transfer layers imply a greater strain transfer ratio, as well as increased accuracy, most researchers are still focused on investigating encapsulated Fiber Bragg gratings (FBGs) in surface strain measurements. This is because, in a traditional
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Although theoretical investigation has demonstrated that fewer strain transfer layers imply a greater strain transfer ratio, as well as increased accuracy, most researchers are still focused on investigating encapsulated Fiber Bragg gratings (FBGs) in surface strain measurements. This is because, in a traditional view, bare FBGs are too fragile to be mounted on the substrate for measuring surface strain. Polyimide FBGs may provide a better balance point between accuracy and protection. A new method to measure surface strain with polyimide fiber Bragg gratings is proposed. Bare polyimide FBGs have a polyimide coating, but like regular non-coated FBGs. This gives polyimide FBGs a higher strain transfer ratio and response frequency. Bare polyimide FBGs can be considered as uncoated FBGs. The coupling of the matrix material of polyimide FBGs is improved as compared to FBGs without coating. In order to verify the capacity for surface strain measurement, polyimide FBGs are mounted to obtain the surface strain of a concrete specimen with SM130-700 interrogator from Micron Optics Incorporation (MOI) with a sampling frequency maximum of 2000 Hz. The experiment demonstrates that polyimide FBGs work well even in dynamic surface strain measurements such as explosion measurement. Validation experiment in this paper also proposed that fewer strain transfer layers can increase dynamic response frequency and coupling between FBG and substrate. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Elastohydrodynamic Performance of a Bio-Based, Non-Corrosive Ionic Liquid
Appl. Sci. 2017, 7(10), 996; doi:10.3390/app7100996
Received: 30 August 2017 / Revised: 22 September 2017 / Accepted: 25 September 2017 / Published: 27 September 2017
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Abstract
To improve performance of machine components, lubrication is one of the most important factors. Especially for use in extreme environments, researchers look for other solutions rather than common lubricant base stocks like mineral oils or vegetable oils. One such example is ionic liquids.
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To improve performance of machine components, lubrication is one of the most important factors. Especially for use in extreme environments, researchers look for other solutions rather than common lubricant base stocks like mineral oils or vegetable oils. One such example is ionic liquids. Ionic liquids have been defined as molten salts with melting points below 100 C that are entirely ionic in nature, comprising both cationic and anionic species. The industrial use of ionic liquids is mostly as solvents, electrolytes, extractants and catalysts. In tribological applications, ionic liquids are mainly studied in boundary lubrication and in pure sliding contacts. In this work, the elastohydrodynamic performance of a bio-based, non-corrosive, [choline][l-proline] ionic liquid is evaluated in terms of pressure-viscosity response, film forming capability and friction. The results show a pressure-viscosity coefficient of below 8 GPa 1 at 25 C, among the lowest reported for any ionic liquid. The ionic liquid generated up to 70% lower friction than a reference paraffin oil with a calculated difference in film thickness of 11%. It was also shown that this ionic liquid is very hygroscopic, which is believed to explain part of the low friction results, but also has to be considered in practical applications since the water content will influence the properties and thus the performance of the lubricant. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle A High-Energy, 100 Hz, Picosecond Laser for OPCPA Pumping
Appl. Sci. 2017, 7(10), 997; doi:10.3390/app7100997
Received: 31 August 2017 / Accepted: 25 September 2017 / Published: 27 September 2017
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Abstract
A high-energy diode-pumped picosecond laser system centered at 1064 nm for optical parametric chirped pulse amplifier (OPCPA) pumping was demonstrated. The laser system was based on a master oscillator power amplifier configuration, which contained an Nd:YVO4 mode-locked seed laser, an LD-pumped Nd:YAG
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A high-energy diode-pumped picosecond laser system centered at 1064 nm for optical parametric chirped pulse amplifier (OPCPA) pumping was demonstrated. The laser system was based on a master oscillator power amplifier configuration, which contained an Nd:YVO4 mode-locked seed laser, an LD-pumped Nd:YAG regenerative amplifier, and two double-pass amplifiers. A reflecting volume Bragg grating with a 0.1 nm reflective bandwidth was used in the regenerative amplifier for spectrum narrowing and pulse broadening to suit the pulse duration of the optical parametric amplifier (OPA) process. Laser pulses with an energy of 316.5 mJ and a pulse duration of 50 ps were obtained at a 100 Hz repetition rate. A top-hat beam distribution and a 0.53% energy stability (RMS) were achieved in this system. Full article
(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)
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Open AccessArticle Organic Electrochemical Transistor Microplate for Real-Time Cell Culture Monitoring
Appl. Sci. 2017, 7(10), 998; doi:10.3390/app7100998
Received: 20 July 2017 / Revised: 26 August 2017 / Accepted: 18 September 2017 / Published: 27 September 2017
PDF Full-text (1478 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Human cell cultures provide a potentially powerful means for pharmacological and toxicological research. A microplate with a multielectrode array of 96 organic electrochemical transistors (OECTs) based on the semiconductive polymer poly(3,4-ethylenedioxythio-phene):poly(styrene sulfonic acid) PEDOT:PSS was developed and fabricated by the screen printing method.
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Human cell cultures provide a potentially powerful means for pharmacological and toxicological research. A microplate with a multielectrode array of 96 organic electrochemical transistors (OECTs) based on the semiconductive polymer poly(3,4-ethylenedioxythio-phene):poly(styrene sulfonic acid) PEDOT:PSS was developed and fabricated by the screen printing method. It consists of a microplate of a 12 × 8 chimney–well array with transistors on the bottom. The OECT is circular with a channel of 1.5 mm2 in the centre surrounded by the circular gate electrode. The device is designed for electrogenic cell monitoring. Simulations with the electrolyte revealed good electrical characteristics and indicated the setup information of the experimental conditions. A transconductance of g = 1.4 mS was achieved in the wide range of gate voltages Vgs = ±0.4 V when the drain potential Vds = −0.735 V was set and the long term relaxation was compensated for. The time constant 0.15 s limited by the channel-electrolyte charge electrical double layer (EDL) capacitance was measured. The device was tested on a 3T3 fibroblast cell culture and the sudden environmental changes were recorded. The living cells can be observed on the channel of the OECT and during electrical stimulation by gate voltage, as well as during the source current response. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Bit- and Power-Loading—A Comparative Study on Maximizing the Capacity of RSOA Based Colorless DMT Transmitters
Appl. Sci. 2017, 7(10), 999; doi:10.3390/app7100999
Received: 6 August 2017 / Accepted: 4 September 2017 / Published: 27 September 2017
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Abstract
We present a comparative study of the capacity increase brought by bit- and power-loading discrete multi-tone (DMT) modulation for low-cost colorless transmitters. Three interesting reflective semiconductor optical amplifier (RSOA) based colorless transmitter configurations are compared: First, an amplified spontaneous emission (ASE) spectrum-sliced source;
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We present a comparative study of the capacity increase brought by bit- and power-loading discrete multi-tone (DMT) modulation for low-cost colorless transmitters. Three interesting reflective semiconductor optical amplifier (RSOA) based colorless transmitter configurations are compared: First, an amplified spontaneous emission (ASE) spectrum-sliced source; second, a self-seeded RSOA fiber cavity laser (FCL) and third, an externally seeded RSOA. With bit- and power-loaded DMT, we report record high line rates of 6.25, 20.1 and 30.7 Gbit/s and line rates of 4.17, 10.1 and 24.5 Gbit/s in a back-to-back and in a 25 km nonzero dispersion shifted fiber (NZDSF) transmission experiments for the three transmitter configurations, respectively. In all the experiments, BER (bit error ratios) below an FEC (forward error correction) limit of 7.5 × 10−3 were achieved. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessArticle Shallow Landslide Susceptibility Modeling Using the Data Mining Models Artificial Neural Network and Boosted Tree
Appl. Sci. 2017, 7(10), 1000; doi:10.3390/app7101000
Received: 18 July 2017 / Revised: 14 September 2017 / Accepted: 21 September 2017 / Published: 28 September 2017
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Abstract
The main purpose of this paper is to present some potential applications of sophisticated data mining techniques, such as artificial neural network (ANN) and boosted tree (BT), for landslide susceptibility modeling in the Yongin area, Korea. Initially, landslide inventory was detected from visual
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The main purpose of this paper is to present some potential applications of sophisticated data mining techniques, such as artificial neural network (ANN) and boosted tree (BT), for landslide susceptibility modeling in the Yongin area, Korea. Initially, landslide inventory was detected from visual interpretation using digital aerial photographic maps with a high resolution of 50 cm taken before and after the occurrence of landslides. The debris flows were randomly divided into two groups: training and validation sets with a 50:50 proportion. Additionally, 18 environmental factors related to landslide occurrence were derived from the topography, soil, and forest maps. Subsequently, the data mining techniques were applied to identify the influence of environmental factors on landslide occurrence of the training set and assess landslide susceptibility. Finally, the landslide susceptibility indexes from ANN and BT were compared with a validation set using a receiver operating characteristics curve. The slope gradient, topographic wetness index, and timber age appear to be important factors in landslide occurrence from both models. The validation result of ANN and BT showed 82.25% and 90.79%, which had reasonably good performance. The study shows the benefit of selecting optimal data mining techniques in landslide susceptibility modeling. This approach could be used as a guideline for choosing environmental factors on landslide occurrence and add influencing factors into landslide monitoring systems. Furthermore, this method can rank landslide susceptibility in urban areas, thus providing helpful information when selecting a landslide monitoring site and planning land-use. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Comparative Research on RC Equivalent Circuit Models for Lithium-Ion Batteries of Electric Vehicles
Appl. Sci. 2017, 7(10), 1002; doi:10.3390/app7101002
Received: 18 August 2017 / Accepted: 25 September 2017 / Published: 28 September 2017
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Abstract
Equivalent circuit models are a hot research topic in the field of lithium-ion batteries for electric vehicles, and scholars have proposed a variety of equivalent circuit models, from simple to complex. On one hand, a simple model cannot simulate the dynamic characteristics of
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Equivalent circuit models are a hot research topic in the field of lithium-ion batteries for electric vehicles, and scholars have proposed a variety of equivalent circuit models, from simple to complex. On one hand, a simple model cannot simulate the dynamic characteristics of batteries; on the other hand, it is difficult to apply a complex model to a real-time system. At present, there are few systematic comparative studies on equivalent circuit models of lithium-ion batteries. The representative first-order resistor-capacitor (RC) model and second-order RC model commonly used in the literature are studied comparatively in this paper. Firstly, the parameters of the two models are identified experimentally; secondly, the simulation model is built in Matlab/Simulink environment, and finally the output precision of these two models is verified by the actual data. The results show that in the constant current condition, the maximum error of the first-order RC model is 1.65% and the maximum error for the second-order RC model is 1.22%. In urban dynamometer driving schedule (UDDS) condition, the maximum error of the first-order RC model is 1.88%, and for the second-order RC model the maximum error is 1.69%. This is of great instructional significance to the application in practical battery management systems for the equivalent circuit model of lithium-ion batteries of electric vehicles. Full article
(This article belongs to the Special Issue Battery Management and State Estimation)
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Open AccessArticle A Cubature-Principle-Assisted IMM-Adaptive UKF Algorithm for Maneuvering Target Tracking Caused by Sensor Faults
Appl. Sci. 2017, 7(10), 1003; doi:10.3390/app7101003
Received: 20 July 2017 / Revised: 2 September 2017 / Accepted: 26 September 2017 / Published: 28 September 2017
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Abstract
Aimed at solving the problem of decreased filtering precision while maneuvering target tracking caused by non-Gaussian distribution and sensor faults, we developed an efficient interacting multiple model-unscented Kalman filter (IMM-UKF) algorithm. By dividing the IMM-UKF into two links, the algorithm introduces the cubature
[...] Read more.
Aimed at solving the problem of decreased filtering precision while maneuvering target tracking caused by non-Gaussian distribution and sensor faults, we developed an efficient interacting multiple model-unscented Kalman filter (IMM-UKF) algorithm. By dividing the IMM-UKF into two links, the algorithm introduces the cubature principle to approximate the probability density of the random variable, after the interaction, by considering the external link of IMM-UKF, which constitutes the cubature-principle-assisted IMM method (CPIMM) for solving the non-Gaussian problem, and leads to an adaptive matrix to balance the contribution of the state. The algorithm provides filtering solutions by considering the internal link of IMM-UKF, which is called a new adaptive UKF algorithm (NAUKF) to address sensor faults. The proposed CPIMM-NAUKF is evaluated in a numerical simulation and two practical experiments including one navigation experiment and one maneuvering target tracking experiment. The simulation and experiment results show that the proposed CPIMM-NAUKF has greater filtering precision and faster convergence than the existing IMM-UKF. The proposed algorithm achieves a very good tracking performance, and will be effective and applicable in the field of maneuvering target tracking. Full article
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Open AccessArticle A Rolling Bearing Fault Diagnosis Method Based on Variational Mode Decomposition and an Improved Kernel Extreme Learning Machine
Appl. Sci. 2017, 7(10), 1004; doi:10.3390/app7101004
Received: 2 August 2017 / Accepted: 19 September 2017 / Published: 29 September 2017
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Abstract
Rolling bearings are key components of rotary machines. To ensure early effective fault diagnosis for bearings, a new rolling bearing fault diagnosis method based on variational mode decomposition (VMD) and an improved kernel extreme learning machine (KELM) is proposed in this paper. A
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Rolling bearings are key components of rotary machines. To ensure early effective fault diagnosis for bearings, a new rolling bearing fault diagnosis method based on variational mode decomposition (VMD) and an improved kernel extreme learning machine (KELM) is proposed in this paper. A fault signal is decomposed via VMD to obtain the intrinsic mode function (IMF) components, and the approximate entropy (ApEn) of the IMF component containing the main fault information is calculated. An eigenvector is created from the approximate entropy of each component. A bearing diagnosis model is created via a KELM; the KELM parameters are optimized using the particle swarm optimization (PSO) algorithm to obtain a KELM diagnosis model with optimal parameters. Finally, the effectiveness of the diagnosis method proposed in this paper is verified via a fan bearing fault diagnosis test. Under identical conditions, the result is compared with the results obtained using a back propagation (BP) neural network, a conventional extreme learning machine (ELM), and a support vector machine (SVM). The test result shows that the method proposed in this paper is superior to the other three methods in terms of diagnostic accuracy. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Design and Experimental Development of a Pneumatic Stiffness Adjustable Foot System for Biped Robots Adaptable to Bumps on the Ground
Appl. Sci. 2017, 7(10), 1005; doi:10.3390/app7101005
Received: 20 August 2017 / Revised: 8 September 2017 / Accepted: 26 September 2017 / Published: 29 September 2017
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Abstract
Walking on rough terrains still remains a challenge that needs to be addressed for biped robots because the unevenness on the ground can easily disrupt the walking stability. This paper proposes a novel foot system with passively adjustable stiffness for biped robots which
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Walking on rough terrains still remains a challenge that needs to be addressed for biped robots because the unevenness on the ground can easily disrupt the walking stability. This paper proposes a novel foot system with passively adjustable stiffness for biped robots which is adaptable to small-sized bumps on the ground. The robotic foot is developed by attaching eight pneumatic variable stiffness units to the sole separately and symmetrically. Each variable stiffness unit mainly consists of a pneumatic bladder and a mechanical reversing valve. When walking on rough ground, the pneumatic bladders in contact with bumps are compressed, and the corresponding reversing valves are triggered to expel out the air, enabling the pneumatic bladders to adapt to the bumps with low stiffness; while the other pneumatic bladders remain rigid and maintain stable contact with the ground, providing support to the biped robot. The performances of the proposed foot system, including the variable stiffness mechanism, the adaptability on the bumps of different heights, and the application on a biped robot prototype are demonstrated by various experiments. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle The Effect of Magnetic Field on Thermal-Reaction Kinetics of a Paramagnetic Metal Hydride Storage Bed
Appl. Sci. 2017, 7(10), 1006; doi:10.3390/app7101006
Received: 4 August 2017 / Accepted: 7 September 2017 / Published: 29 September 2017
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Abstract
A safe and efficient method for storing hydrogen is solid state storage through a chemical reaction in metal hydrides. A good amount of research has been conducted on hydrogenation properties of metal hydrides and possible methods to improve them. Background research shows that
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A safe and efficient method for storing hydrogen is solid state storage through a chemical reaction in metal hydrides. A good amount of research has been conducted on hydrogenation properties of metal hydrides and possible methods to improve them. Background research shows that heat transfer is one of the reaction rate controlling parameters in a metal hydride hydrogen storage system. Considering that some very well-known hydrides like lanthanum nickel (LaNi5) and magnesium hydride (MgH2) are paramagnetic materials, the effect of an external magnetic field on heat conduction and reaction kinetics in a metal hydride storage system with such materials needs to be studied. In the current paper, hydrogenation properties of lanthanum nickel under magnetism were studied. The properties which were under consideration include reaction kinetics, hydrogen absorption capacity, and hydrogenation time. Experimentation has proven the positive effect of applying magnetic fields on the heat conduction, reaction kinetics, and hydrogenation time of a lanthanum nickel bed. However, magnetism did not increase the hydrogenation capacity of lanthanum nickel, which is evidence to prove that elevated hydrogenation characteristics result from enhanced heat transfer in the bed. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle An Analytical Solution for Block Toppling Failure of Rock Slopes during an Earthquake
Appl. Sci. 2017, 7(10), 1008; doi:10.3390/app7101008
Received: 7 August 2017 / Revised: 9 September 2017 / Accepted: 20 September 2017 / Published: 29 September 2017
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Abstract
Toppling failure is one of the most common failure types in the field. It always occurs in rock masses containing a group of dominant discontinuities dipping into the slope. Post-earthquake investigation has shown that many toppling rock slope failures have occurred during earthquakes.
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Toppling failure is one of the most common failure types in the field. It always occurs in rock masses containing a group of dominant discontinuities dipping into the slope. Post-earthquake investigation has shown that many toppling rock slope failures have occurred during earthquakes. In this study, an analytical solution is presented on the basis of limit equilibrium analysis. The acceleration of seismic load as well as joint persistence within the block base, were considered in the analysis. The method was then applied into a shake table test of an anti-dip layered slope model. As predicted from the analytical method, blocks topple or slide from slope crest to toe progressively and the factor of safety decreases as the inputting acceleration increases. The results perfectly duplicate the deformation features and stability condition of the physical model under the shake table test. It is shown that the presented method is more universal than the original one and can be adopted to evaluate the stability of the slope with potential toppling failure under seismic loads. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle B4C-Al Composites Fabricated by the Powder Metallurgy Process
Appl. Sci. 2017, 7(10), 1009; doi:10.3390/app7101009
Received: 27 August 2017 / Accepted: 19 September 2017 / Published: 29 September 2017
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Abstract
Due to the large thermal neutron absorption cross section of 10B, B4C-Al composites have been used as neutron absorbing materials in nuclear industries, which can offer not only good neutron shielding performance but also excellent mechanical properties. The distribution of
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Due to the large thermal neutron absorption cross section of 10B, B4C-Al composites have been used as neutron absorbing materials in nuclear industries, which can offer not only good neutron shielding performance but also excellent mechanical properties. The distribution of B4C particles affects the mechanical performance and efficiency of the thermal neutron absorption of the composite materials. In this study, 15 wt % B4C-Al and 20 wt % B4C-Al composites were prepared using a powder metallurgy process, i.e., ball milling followed by pressing, sintering, hot-extrusion, and hot-rolling. The yield and tensile strengths of the composites were markedly increased with an increase in the milling energy and the percentages of B4C particles. Microstructure analysis and neutron radiography revealed that the high-energy ball milling induced the homogeneous distribution of B4C particles in the Al matrix and good bonding between the Al matrix and the B4C particles. The load transfer ability and mechanical properties of the composites were consequently improved. The results showed the high-energy ball milling process is an appropriate fabrication procedure to prevent the agglomeration of the reinforcement particles even if the matrix to reinforcement particle size ratio was nearly 10. Full article
(This article belongs to the Special Issue Radiation Effects of Materials with Laser, Ion Beam and Rays)
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Open AccessArticle Effect of Steel Fiber and Different Environments on Flexural Behavior of Reinforced Concrete Beams
Appl. Sci. 2017, 7(10), 1011; doi:10.3390/app7101011
Received: 14 August 2017 / Revised: 16 September 2017 / Accepted: 26 September 2017 / Published: 30 September 2017
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Abstract
The main kind of deterioration in marine Reinforced Concrete (RC) structures and other infrastructures is steel bar corrosion due to cracks in concrete surfaces, which leads to the reduction of the load carrying capacity, ductility, and structural safety. It seems that steel fibers
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The main kind of deterioration in marine Reinforced Concrete (RC) structures and other infrastructures is steel bar corrosion due to cracks in concrete surfaces, which leads to the reduction of the load carrying capacity, ductility, and structural safety. It seems that steel fibers can reduce and delay the cracking, and increase the flexural strength and ductility of marine RC structures. To do so, in marine atmosphere and the tidal zone of the Oman Sea and fresh water, the flexural behavior of beams containing Plain Concrete (PC), Concrete with Steel fiber Reinforcement (SFRC), RC, Concrete with Steel fiber, and bar Reinforcement ((R+S)C) at 28, 90 and 180 days were determined. Beams were 99 un-cracked and pre-cracked beams, with dimensions of 200 × 200 × 750 mm. Based on results and at 180 days, the flexural strength and toughness of pre-cracked (R+S)C beams were 22%–43% higher than the pre-cracked RC beams. The effect of steel fiber on the increment of load capacity and the toughness of pre-cracked RC beams were approximately the same. By addition of steel fiber to un-cracked RC beams, load capacity and toughness were increased up to 20%. The load capacity and toughness in marine atmosphere and tidal zone were approximately 15% lower than the fresh water condition. Full article
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Open AccessArticle Physicochemical, Mineralogical and Microscopic Evaluation of Sustainable Bricks Manufactured with Construction Wastes
Appl. Sci. 2017, 7(10), 1012; doi:10.3390/app7101012
Received: 3 September 2017 / Revised: 27 September 2017 / Accepted: 27 September 2017 / Published: 30 September 2017
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Abstract
At an international level, enormous volumes of construction and demolition wastes are generated: 170 million tons/year in the USA, 500 million tons/year in the European Union (EU) and 12 million tons/year in Mexico. Alternative uses for these heterogeneous materials, such as the manufacture
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At an international level, enormous volumes of construction and demolition wastes are generated: 170 million tons/year in the USA, 500 million tons/year in the European Union (EU) and 12 million tons/year in Mexico. Alternative uses for these heterogeneous materials, such as the manufacture of sustainable bricks, are potential solutions to this growing environmental issue. Based on previous studies, and in compliance with Mexican standards, four different types of secondary materials were utilized in the composition of a sustainable brick matrix. Temperature and solar radiation used for drying purposes were determined, as well as weight loss, resistance and initial maximum absorption. In order to characterize the resulting matrix, observations were made with a scanning electron microscope, and the chemical composition of the samples was determined by detecting basic compounds using mapping through SEM-EDS microanalysis, connected to the SEM unit. Finally, thermogravimetric analyses were performed to correlate mechanical and chemical behavior, and resistance to high temperatures of the mixtures. The results obtained showed that all-in-one (AiO) is the most appropriate material for brick manufacturing, Opuntia ficus-indica mucilage improves physical properties, such as increased compressive strength and reduced water absorption, while wood residues, clay minerals and illite enhance mechanical properties. Full article
(This article belongs to the Section Materials)
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Open AccessArticle 2,1 Norm and Hessian Regularized Non-Negative Matrix Factorization with Discriminability for Data Representation
Appl. Sci. 2017, 7(10), 1013; doi:10.3390/app7101013
Received: 4 September 2017 / Revised: 26 September 2017 / Accepted: 26 September 2017 / Published: 30 September 2017
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Abstract
Matrix factorization based methods have widely been used in data representation. Among them, Non-negative Matrix Factorization (NMF) is a promising technique owing to its psychological and physiological interpretation of spontaneously occurring data. On one hand, although traditional Laplacian regularization can enhance the performance
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Matrix factorization based methods have widely been used in data representation. Among them, Non-negative Matrix Factorization (NMF) is a promising technique owing to its psychological and physiological interpretation of spontaneously occurring data. On one hand, although traditional Laplacian regularization can enhance the performance of NMF, it still suffers from the problem of its weak extrapolating ability. On the other hand, standard NMF disregards the discriminative information hidden in the data and cannot guarantee the sparsity of the factor matrices. In this paper, a novel algorithm called 2 , 1 norm and Hessian Regularized Non-negative Matrix Factorization with Discriminability ( 2 , 1 HNMFD), is developed to overcome the aforementioned problems. In 2 , 1 HNMFD, Hessian regularization is introduced in the framework of NMF to capture the intrinsic manifold structure of the data. 2 , 1 norm constraints and approximation orthogonal constraints are added to assure the group sparsity of encoding matrix and characterize the discriminative information of the data simultaneously. To solve the objective function, an efficient optimization scheme is developed to settle it. Our experimental results on five benchmark data sets have demonstrated that 2 , 1 HNMFD can learn better data representation and provide better clustering results. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Comparative Study of Clustering Analysis Method for Driver’s Steering Intention Classification and Identification under Different Typical Conditions
Appl. Sci. 2017, 7(10), 1014; doi:10.3390/app7101014
Received: 22 August 2017 / Revised: 28 September 2017 / Accepted: 28 September 2017 / Published: 30 September 2017
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Abstract
Driver’s intention classification and identification is identified as the key technology for intelligent vehicles and is widely used in a variety of advanced driver assistant systems (ADAS). To study driver’s steering intention under different typical operating conditions, five driving school coaches of different
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Driver’s intention classification and identification is identified as the key technology for intelligent vehicles and is widely used in a variety of advanced driver assistant systems (ADAS). To study driver’s steering intention under different typical operating conditions, five driving school coaches of different ages and genders are selected as the test drivers for a real vehicle test. Four kinds of typical car steering condition test data with four different vehicles are collected. Test data are filtered by the Butterworth filter and are used for extracting the driver steering characteristic parameters. Based on Principal Component Analysis (PCA), the three kinds of clustering analysis methods, including the Fuzzy C-Means algorithm (FCM), the Gustafson Full article
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Open AccessFeature PaperArticle Material Optimization for a High Power Thermoelectric Generator in Wearable Applications
Appl. Sci. 2017, 7(10), 1015; doi:10.3390/app7101015
Received: 13 September 2017 / Revised: 26 September 2017 / Accepted: 26 September 2017 / Published: 30 September 2017
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Abstract
Thermoelectric power generation using human body heat can be applied to wearable sensors, and various applications are possible. Because the thermoelectric generator (TEG) is highly dependent on the thermoelectric material, research on improving the performance of the thermoelectric material has been conducted. Thus
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Thermoelectric power generation using human body heat can be applied to wearable sensors, and various applications are possible. Because the thermoelectric generator (TEG) is highly dependent on the thermoelectric material, research on improving the performance of the thermoelectric material has been conducted. Thus far, in developing thermoelectric materials, the researchers have focused on improving the figure of merit, ZT. For a TEG placed on the human body, however, the power density does not always increase as the material ZT increases. In this study, the material properties and ZT of P-type BiSbTe3 were simulated for carrier concentration ranging from 3 × 1017 to 3 × 1020 cm−3, and the power density of a TEG fabricated from the material dataset was calculated using a thermoelectric resistance model for human body application. The results revealed that the maximum ZT and the maximum power density were formed at different carrier concentrations. The material with maximum ZT showed 28.8% lower power density compared to the maximum obtainable power density. Further analysis confirmed that the mismatch in the optimum carrier concentration for the maximum ZT and maximum power density can be minimized when a material with lower thermal conductivity is used in a TEG. This study shows that the ZT enhancement of materials is not the highest priority in the production of a TEG for human body application, and material engineering to lower the thermal conductivity is required to reduce the optimum point mismatch problem. Full article
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Open AccessArticle Experimental Study on the Performance of Polyurethane-Steel Sandwich Structure under Debris Flow
Appl. Sci. 2017, 7(10), 1018; doi:10.3390/app7101018
Received: 7 September 2017 / Revised: 28 September 2017 / Accepted: 29 September 2017 / Published: 2 October 2017
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Abstract
Polyurethane-steel sandwich structure, which creatively uses the polyurethane-steel sandwich composite as a structural material, is proposed to strengthen the impact resistance of buildings under debris flow. The impact resistance of polyurethane-steel sandwich structure under debris flow is investigated by a series of impact
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Polyurethane-steel sandwich structure, which creatively uses the polyurethane-steel sandwich composite as a structural material, is proposed to strengthen the impact resistance of buildings under debris flow. The impact resistance of polyurethane-steel sandwich structure under debris flow is investigated by a series of impact loading tests, compared with that of traditional steel frame structures. Additionally, further discussions regarding the hidden mechanism are performed. During the whole impact process, as for steel frame structure, the impacted column appeared obvious local deformation both at its column base and on the impact surface, leading to remarkable decrease of its impact resistance; while the stress and strain of polyurethane-steel sandwich structure develops more uniformly and distribute further in the whole structure, maintaining excellent integrity and impact transmission capability. The impact loading tests confirm that polyurethane-steel sandwich structure possesses superior impact resistance under debris flow. This is of great practical significance for the prevention and reduction of geological disasters. Full article
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Open AccessArticle Evaluation of Anti-Wear Properties of Metalworking Fluids Enhanced with Halloysite Nanotubes
Appl. Sci. 2017, 7(10), 1019; doi:10.3390/app7101019
Received: 22 August 2017 / Revised: 24 September 2017 / Accepted: 25 September 2017 / Published: 3 October 2017
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Abstract
The study of nanoparticles as additives for metalworking fluids (MWFs) with applications in the metal removal processes, or machining, has received increasing attention due to the possible enhancements on tribological properties. In this study, low-cost and environmentally friendly nanoparticle additives of halloysite clay
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The study of nanoparticles as additives for metalworking fluids (MWFs) with applications in the metal removal processes, or machining, has received increasing attention due to the possible enhancements on tribological properties. In this study, low-cost and environmentally friendly nanoparticle additives of halloysite clay nanotubes (HNTs) were dispersed in metalworking fluids utilized for milling processes. Concentrations of 0.01, 0.05, 0.10 wt. % were incorporated into a mineral oil (MO) and a semi-synthetic fluid (SF) by ultrasonication. The anti-wear properties of metalworking nanofluids were characterized with a T-05 block-on-ring tribotester at a contact pressure of 0.5 GPa. Surface roughness of worn block materials was obtained with an optical 3D surface measurement system. Results showed that at a concentration of 0.10 wt. % HNTs block mass loss was lowered by 24% for the MO + HNTs nanofluids. For the SF + HNTs, a reduction of 63% and 32% in wear mass loss and coefficient of friction (COF), respectively, were found at the same concentration. The tribological enhancing mechanism for the applied contact pressure was proposed to be due to a reduction of the area of contact and nanoparticle sliding between surfaces with no HNT deposition, evidenced by energy dispersive spectrometry (EDS). Furthermore, surface roughness studies of worn blocks showed smoother surfaces with lower groove density with the addition of nanoparticle additives. The results of this study demonstrate that HNTs can improve the lubricity of metalworking cutting fluids used for machining processes, enhancing tool life and providing better surface finish of products. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessCommunication Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption
Appl. Sci. 2017, 7(10), 1020; doi:10.3390/app7101020
Received: 31 August 2017 / Revised: 22 September 2017 / Accepted: 29 September 2017 / Published: 3 October 2017
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Abstract
A facile heat-up synthesis route is used to synthesize environmentally friendly Ag2S colloidal quantum dots (CQDs) that are applied as light absorbing material in solid state p-i-n junction solar cell devices. The as-synthesized Ag2S CQDs have an average size
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A facile heat-up synthesis route is used to synthesize environmentally friendly Ag2S colloidal quantum dots (CQDs) that are applied as light absorbing material in solid state p-i-n junction solar cell devices. The as-synthesized Ag2S CQDs have an average size of around 3.5 nm and exhibit broad light absorption covering ultraviolet, visible, and near infrared wavelength regions. The solar cell devices are constructed with a device architecture of FTO/TiO2/Ag2S CQDs/hole transport material (HTM) /Au using a solution-processed approach. Different HTMs, N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl)-9,9′-spirobi(9H-fluorene)-2,2′,7,7′ tetramine (spiro-OMeTAD), poly(3-hexylthiophene-2,5-diyl) (P3HT), and poly((2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl)-2,5-thiophenediyl) TQ1 are studied for maximizing the device photovoltaic performance. The solar cell device with P3HT as a hole transport material gives the highest performance and the solar cell exhibit broad spectral absorption. These results indicate that Ag2S CQD have high potential for utilization as environmentally friendly light absorbing materials for solar cell application and that the hole transport material is critical to maximize the solar cell photovoltaic performance. Full article
(This article belongs to the Special Issue Quantum Materials)
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Open AccessArticle Application of Improved Hilbert–Huang Transform to Partial Discharge Defect Model Recognition of Power Cables
Appl. Sci. 2017, 7(10), 1021; doi:10.3390/app7101021
Received: 28 August 2017 / Revised: 28 September 2017 / Accepted: 1 October 2017 / Published: 4 October 2017
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Abstract
As a key concern in a power system, a deteriorated insulation is likely to bring about a partial discharge phenomenon and hence degrades the power supply quality. Thus, a partial discharge test has been turned into an approach of significance to protect a
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As a key concern in a power system, a deteriorated insulation is likely to bring about a partial discharge phenomenon and hence degrades the power supply quality. Thus, a partial discharge test has been turned into an approach of significance to protect a power system from an unexpected malfunction. An improved Hilbert–Huang Transformation (HHT) is proposed in this work as an effective way to address the issues of an optimal shifting number and illusive components, both suffered in a conventional HHT approach, and is then applied to a defect mode recognition for a partial discharge signal analysis in the case of a cross-linked polyethylene insulated power cable. As the first step, the partial discharge signal detected is converted through the proposed improved HHT to a time-frequency-energy 3D spectrum. Then as the second step, the fractal features contained therein are extracted by way of a fractal theory, and in the end the defect modes are recognized as intended by use of an extension method. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Investigation of Effective Modification Treatments for Titanium Membranes
Appl. Sci. 2017, 7(10), 1022; doi:10.3390/app7101022
Received: 4 September 2017 / Revised: 25 September 2017 / Accepted: 2 October 2017 / Published: 4 October 2017
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Abstract
Titanium membranes are used for guided bone regeneration in implant therapy. However, as a bioinert material, titanium does not have the ability to accelerate bone formation. Various titanium surface treatments to confer bioactivity have been demonstrated; however, there are concerns about the influence
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Titanium membranes are used for guided bone regeneration in implant therapy. However, as a bioinert material, titanium does not have the ability to accelerate bone formation. Various titanium surface treatments to confer bioactivity have been demonstrated; however, there are concerns about the influence of chemical treatments for thin titanium membranes. This study investigated the influence of surface modifications on the structure of titanium membranes. Titanium membranes of 20 μm thickness were treated with acid or alkali solutions, and we evaluated their surface structure, wettability, thickness, and mechanical strength compared to non-treated membranes. Alkali-treated titanium membranes displayed the formation of nanoscale pore structures on their surfaces, enhanced hydrophilicity, and almost same thickness compared with acid-treated membranes. Furthermore, the tensile strength of alkali-treated membranes was comparable to non-treated membranes. These results suggest that alkali treatment is an appropriate surface modification method for titanium membranes. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Strategies to Automatically Derive a Process Model from a Configurable Process Model Based on Event Data
Appl. Sci. 2017, 7(10), 1023; doi:10.3390/app7101023
Received: 31 August 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 4 October 2017
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Abstract
Configurable process models are frequently used to represent business workflows and other discrete event systems among different branches of large organizations: they unify commonalities shared by all branches and describe their differences, at the same time. The configuration of such models is usually
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Configurable process models are frequently used to represent business workflows and other discrete event systems among different branches of large organizations: they unify commonalities shared by all branches and describe their differences, at the same time. The configuration of such models is usually done manually, which is challenging. On the one hand, when the number of configurable nodes in the configurable process model grows, the size of the search space increases exponentially. On the other hand, the person performing the configuration may lack the holistic perspective to make the right choice for all configurable nodes at the same time, since choices influence each other. Nowadays, information systems that support the execution of business processes create event data reflecting how processes are performed. In this article, we propose three strategies (based on exhaustive search, genetic algorithms and a greedy heuristic) that use event data to automatically derive a process model from a configurable process model that better represents the characteristics of the process in a specific branch. These strategies have been implemented in our proposed framework and tested in both business-like event logs as recorded in a higher educational enterprise resource planning system and a real case scenario involving a set of Dutch municipalities. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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Open AccessFeature PaperArticle Modelling and numerical simulation of Supercritical CO2 debinding of Inconel 718 components elaborated by Metal Injection Molding
Appl. Sci. 2017, 7(10), 1024; doi:10.3390/app7101024
Received: 13 July 2017 / Revised: 22 September 2017 / Accepted: 29 September 2017 / Published: 6 October 2017
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Abstract
A debinding step using the supercritical state of a fluid has been increasingly investigated for extracting organic binders from components obtained by metal-injection molding. It consists of placing the component in an enclosure subjected to pressure and temperatures higher than the critical point
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A debinding step using the supercritical state of a fluid has been increasingly investigated for extracting organic binders from components obtained by metal-injection molding. It consists of placing the component in an enclosure subjected to pressure and temperatures higher than the critical point to perform polymer extraction of the Metal-injection molding (MIM) component. It is an alternative to conventional solvent debinding. The topic of this study is to model and simulate the supercritical debinding stage to elucidate the mechanism of polymer degradation and stabilization with a three-dimensional model. Modelling this extraction process would optimize the process on an industrial scale. It can be physically described by Fick’s law of diffusion. The model’s main parameter is the diffusion coefficient, which is identified by using linear regression based on the least-squares method. In the model, an effective length scale is specially developed to take into account the diffusion in all directions. The tests were performed for extracting polyethylene glycol, an organic additive, using supercritical CO2 in injected components. The feedstock is composed of polypropylene, polyethylene glycol, and stearic-acid as binder mixed with Inconel 718 super-alloy powders. The identified parameters were used to calculate the diffusion coefficient and simulate the supercritical debinding step on the Comsol Multiphysics® finite-element software platform to predict the remaining binder. The obtained numerical simulation results are in good agreement with the experimental data. The proposed numerical simulations allow for the determination of the remaining polyethylene glycol (PEG) binder distribution with respect to processing parameters for components during the supercritical debinding process at any time. Moreover, this approach can be used in other formulation, powder, and binder systems. Full article
(This article belongs to the Special Issue Powder Injection Moulding)
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Open AccessArticle Fault Diagnosis of a Reconfigurable Crawling–Rolling Robot Based on Support Vector Machines
Appl. Sci. 2017, 7(10), 1025; doi:10.3390/app7101025
Received: 1 August 2017 / Revised: 11 September 2017 / Accepted: 25 September 2017 / Published: 6 October 2017
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Abstract
As robots begin to perform jobs autonomously, with minimal or no human intervention, a new challenge arises: robots also need to autonomously detect errors and recover from faults. In this paper, we present a Support Vector Machine (SVM)-based fault diagnosis system for a
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As robots begin to perform jobs autonomously, with minimal or no human intervention, a new challenge arises: robots also need to autonomously detect errors and recover from faults. In this paper, we present a Support Vector Machine (SVM)-based fault diagnosis system for a bio-inspired reconfigurable robot named Scorpio. The diagnosis system needs to detect and classify faults while Scorpio uses its crawling and rolling locomotion modes. Specifically, we classify between faulty and non-faulty conditions by analyzing onboard Inertial Measurement Unit (IMU) sensor data. The data capture nine different locomotion gaits, which include rolling and crawling modes, at three different speeds. Statistical methods are applied to extract features and to reduce the dimensionality of original IMU sensor data features. These statistical features were given as inputs for training and testing. Additionally, the c-Support Vector Classification (c-SVC) and nu-SVC models of SVM, and their fault classification accuracies, were compared. The results show that the proposed SVM approach can be used to autonomously diagnose locomotion gait faults while the reconfigurable robot is in operation. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Analysis of Powertrain Loading Dynamic Characteristics and the Effects on Fatigue Damage
Appl. Sci. 2017, 7(10), 1027; doi:10.3390/app7101027
Received: 5 September 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 6 October 2017
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Abstract
The objective of this study is to investigate the effects of key factors on the powertrain loading dynamic characteristics and fatigue damage. First, the engine and the transmission output shaft torque of a multi-axle vehicle powertrain system were measured by proving grounds (PG)
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The objective of this study is to investigate the effects of key factors on the powertrain loading dynamic characteristics and fatigue damage. First, the engine and the transmission output shaft torque of a multi-axle vehicle powertrain system were measured by proving grounds (PG) testing and analyzed with a conclusion that the powertrain loading changes were mainly related to three key factors: the mean engine torque, the harmonic engine torque, and the vibration properties of the system. Subsequently, a dynamic model considering the three factors was built and validated by the test data. Finally, fatigue damage of shaft parts and gear parts were calculated to investigate the influence degrees of the three factors. The results show that, the harmonic engine torque and the vibration properties of the powertrain system have a great influence on the fatigue damage of shaft parts, and the mean engine torque is the main factor causing the fatigue damage of gear parts. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Optimal Tilt Angle and Orientation of Photovoltaic Modules Using HS Algorithm in Different Climates of China
Appl. Sci. 2017, 7(10), 1028; doi:10.3390/app7101028
Received: 6 September 2017 / Revised: 25 September 2017 / Accepted: 29 September 2017 / Published: 6 October 2017
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Abstract
Solar energy technologies play an important role in shaping a sustainable energy future, and generating clean, renewable, and widely distributed energy sources. This paper determines the optimum tilt angle and optimum azimuth angle of photovoltaic (PV) panels, employing the harmony search (HS) meta-heuristic
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Solar energy technologies play an important role in shaping a sustainable energy future, and generating clean, renewable, and widely distributed energy sources. This paper determines the optimum tilt angle and optimum azimuth angle of photovoltaic (PV) panels, employing the harmony search (HS) meta-heuristic algorithm. In this study, the ergodic method is first conducted to obtain the optimum tilt angle and the optimum azimuth angle in several cities of China based on the model of Julian dating. Next, the HS algorithm is applied to search for the optimum solution. The purpose of this research is to maximize the extraterrestrial radiation on the collector surface for a specific period. The sun’s position is predicted by the proposed model at different times, and then solar radiation is obtained on various inclined planes with different orientations in each city. The performance of the HS method is compared with that of the ergodic method and other optimization algorithms. The results demonstrate that the tilt angle should be changed once a month, and the best orientation is usually due south in the selected cities. In addition, the HS algorithm is a practical and reliable alternative for estimating the optimum tilt angle and optimum azimuth angle of PV panels. Full article
(This article belongs to the Special Issue Computational Intelligence in Photovoltaic Systems)
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Open AccessFeature PaperArticle Evaluation of Adhesion and Hysteresis Friction of Rubber–Pavement System
Appl. Sci. 2017, 7(10), 1029; doi:10.3390/app7101029
Received: 1 September 2017 / Revised: 25 September 2017 / Accepted: 30 September 2017 / Published: 7 October 2017
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Abstract
Tire-pavement friction is a key component in road safety. Adhesion and hysteresis are the two main mechanisms that affect the friction between rubber tires and pavements. This study experimentally examined the relationship between rubber–pavement adhesion and friction. The adhesive bond energy between rubber
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Tire-pavement friction is a key component in road safety. Adhesion and hysteresis are the two main mechanisms that affect the friction between rubber tires and pavements. This study experimentally examined the relationship between rubber–pavement adhesion and friction. The adhesive bond energy between rubber and pavement surfaces was calculated by measuring the surface energy components of rubber and aggregates. The friction was measured in the laboratory using a dynamic friction tester. The results revealed that there is a fair correlation between the adhesive bond energy and measured coefficient of friction. A rubber–pavement system with higher adhesion provided higher friction at low speed. In addition, the results demonstrated that there is a strong correlation between rubber–pavement friction and rubber properties. Softer rubber provided higher friction and vice versa. The results of this study provide an experimental verification of the relationship between adhesion and pavement surface friction. The adhesive bond energy and rubber rheological properties could be incorporated in computational models to study tire-pavement friction in different conditions (e.g., speed and temperature). Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle From Point Clouds to Building Information Models: 3D Semi-Automatic Reconstruction of Indoors of Existing Buildings
Appl. Sci. 2017, 7(10), 1030; doi:10.3390/app7101030
Received: 13 September 2017 / Revised: 1 October 2017 / Accepted: 2 October 2017 / Published: 12 October 2017
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Abstract
The creation of as-built Building Information Models requires the acquisition of the as-is state of existing buildings. Laser scanners are widely used to achieve this goal since they permit to collect information about object geometry in form of point clouds and provide a
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The creation of as-built Building Information Models requires the acquisition of the as-is state of existing buildings. Laser scanners are widely used to achieve this goal since they permit to collect information about object geometry in form of point clouds and provide a large amount of accurate data in a very fast way and with a high level of details. Unfortunately, the scan-to-BIM (Building Information Model) process remains currently largely a manual process which is time consuming and error-prone. In this paper, a semi-automatic approach is presented for the 3D reconstruction of indoors of existing buildings from point clouds. Several segmentations are performed so that point clouds corresponding to grounds, ceilings and walls are extracted. Based on these point clouds, walls and slabs of buildings are reconstructed and described in the IFC format in order to be integrated into BIM software. The assessment of the approach is proposed thanks to two datasets. The evaluation items are the degree of automation, the transferability of the approach and the geometric quality of results of the 3D reconstruction. Additionally, quality indexes are introduced to inspect the results in order to be able to detect potential errors of reconstruction. Full article
(This article belongs to the Special Issue Laser Scanning)
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Open AccessArticle Modeling Coloration of a Radiochromic Film with Molecular Dynamics-Coupled Finite Element Method
Appl. Sci. 2017, 7(10), 1031; doi:10.3390/app7101031
Received: 13 September 2017 / Revised: 28 September 2017 / Accepted: 1 October 2017 / Published: 7 October 2017
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Abstract
Radiochromic films change color upon exposures to radiation doses as a result of solid-state polymerization (SSP). Commercially available radiochromic films are primarily designed for, and have become widely used in, clinical X-ray dosimetry. However, many intriguing properties of radiochromic films are not yet
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Radiochromic films change color upon exposures to radiation doses as a result of solid-state polymerization (SSP). Commercially available radiochromic films are primarily designed for, and have become widely used in, clinical X-ray dosimetry. However, many intriguing properties of radiochromic films are not yet fully understood. The present work aimed at developing a theoretical model at both atomic and macroscopic scales to provide a platform for future works to understand these intriguing properties. Despite the fact that radiochromic films were primarily designed for clinical X-ray dosimetry, dose-response curves for the Gafchromic EBT3 film obtained for ultraviolet (UV) radiation were employed to develop our model in order to avoid complications of ionization, non-uniform energy deposition, as well as dispersed doses caused by secondary electrons set in motion by the indirectly ionizing X-ray photons, which might introduce added uncertainties to the model and overshadow the basic SSP processes. The active layer in the EBT3 film consisted of diacetylene (DA) pentacosa-10,12-diynoate monomers, which were modelled using molecular dynamics (MD). The degrees of SSP in the atomic scale upon different UV exposures were obtained to determine the absorption coefficients of the active layer, which were then input into the finite element method (FEM). The classical steady-state Helmholtz equation was engaged to model the reflection from the active layer using the FEM technique. The multifrontal massively parallel sparse direct solver (MUMPS) was employed to solve the present numerical problem. Very good agreement between experimentally and theoretically obtained coloration in terms of net reflective optical density was achieved for different UV exposures. In particular, for UV exposures larger than ~40 J/cm2, the reflected light intensity decreased at a lower rate when compared to other UV exposure values, which was explained by the densely cross-linked structure under near-complete polymerization, and thus the lower efficiency for further bond formation between DA monomer strands. Full article
(This article belongs to the Special Issue Radiation Effects of Materials with Laser, Ion Beam and Rays)
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Open AccessArticle Fast Frequency Acquisition and Phase Locking of Nonplanar Ring Oscillators
Appl. Sci. 2017, 7(10), 1032; doi:10.3390/app7101032
Received: 26 August 2017 / Revised: 30 September 2017 / Accepted: 4 October 2017 / Published: 9 October 2017
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Abstract
Optical phase locking is a critical technique in space coherent optical communication and active coherent laser beam combining. In a typical optical phase locking loop based on nonplanar ring oscillators, the pull-in range is normally less than 1 MHz, limited by loop delay
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Optical phase locking is a critical technique in space coherent optical communication and active coherent laser beam combining. In a typical optical phase locking loop based on nonplanar ring oscillators, the pull-in range is normally less than 1 MHz, limited by loop delay and frequency tuning bandwidth of the laser source. Phase locking cannot be achieved at large initial frequency differences. In this work, a fast laser frequency acquisition method is demonstrated. The frequency difference between the signal and local lasers was measured via frequency dividing and period counting, and the frequency control signal was generated by a frequency discrimination and control module, to reduce the frequency difference to the pull-in range of the loop. Under the coordinating function of the loop filter and the frequency discrimination and control module, phase locking under a large initial frequency difference was achieved. The frequency acquisition range reached 164 MHz, and the acquisition and locking time was measured to be 440 ms. Additionally, the acquisition time was shortened with the decrease in initial frequency difference. Full article
(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)
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Open AccessArticle Fast Reconfigurable SOA-Based Wavelength Conversion of Advanced Modulation Format Data
Appl. Sci. 2017, 7(10), 1033; doi:10.3390/app7101033
Received: 31 August 2017 / Revised: 28 September 2017 / Accepted: 3 October 2017 / Published: 10 October 2017
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Abstract
We theoretically analyze the phase noise transfer issue between the pump and the wavelength-converted idler for a nondegenerate four-wave mixing (FWM) scheme, as well as study the vector theory in nonlinear semiconductor optical amplifiers (SOAs), in order to design a polarization-insensitive wavelength conversion
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We theoretically analyze the phase noise transfer issue between the pump and the wavelength-converted idler for a nondegenerate four-wave mixing (FWM) scheme, as well as study the vector theory in nonlinear semiconductor optical amplifiers (SOAs), in order to design a polarization-insensitive wavelength conversion system employing dual co-polarized pumps. A tunable sampled grating distributed Bragg reflector (SG-DBR) pump laser has been utilized to enable fast wavelength conversion in the sub-microsecond timescale. By using the detailed characterization of the SGDBR laser, we discuss the phase noise performance of the SGDBR laser. Finally, we present a reconfigurable SOA-based all-optical wavelength converter using the fast switching SGDBR tunable laser as one of the pump sources and experimentally study the wavelength conversion of the single polarization quadrature phase shift keying (QPSK) and polarization multiplexed (Pol-Mux) QPSK signals at 12.5-Gbaud. A wide tuning range (>10 nm) and less than 50 ns and 160 ns reconfiguration time have been achieved for the wavelength conversion system for QPSK and PM-QPSK signals, respectively. The performance under the switching environment after the required reconfiguration time is the same as the static case when the wavelengths are fixed. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessArticle Communication Architecture for Grid Integration of Cyber Physical Wind Energy Systems
Appl. Sci. 2017, 7(10), 1034; doi:10.3390/app7101034
Received: 4 September 2017 / Accepted: 8 October 2017 / Published: 10 October 2017
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Abstract
As we move toward increasing the grid integration of large-scale wind farms (WFs), reliable monitoring, protection, and control are needed to ensure grid stability. WFs are considered to be large and complex cyber physical systems owing to coupling between the electric power system
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As we move toward increasing the grid integration of large-scale wind farms (WFs), reliable monitoring, protection, and control are needed to ensure grid stability. WFs are considered to be large and complex cyber physical systems owing to coupling between the electric power system and information and communication technologies (ICT). In this study, we proposed a framework for a cyber physical wind energy system (CPWES), which consists of four layers: a WF power system layer, data acquisition and monitoring layer, communication network layer, and application layer. We performed detailed network modeling for the WF system, including the wind turbines, meteorological mast (met-mast), and substation based on IEC 61400-25 and IEC 61850 standards. Network parameters and configuration were based on a real WF (Korean Southwest offshore project). The simulation results of the end-to-end delay were obtained for different WF applications, and they were compared with the timing requirements of the IEC 1646 standard. The proposed architecture represents a reference model for WF systems, and it can be used to enable the design of future CPWESs. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Parameters Sensitivity Analysis of Position-Based Impedance Control for Bionic Legged Robots’ HDU
Appl. Sci. 2017, 7(10), 1035; doi:10.3390/app7101035
Received: 2 September 2017 / Revised: 27 September 2017 / Accepted: 30 September 2017 / Published: 10 October 2017
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Abstract
For the hydraulic drive unit (HDU) on the joints of bionic legged robots, this paper proposes the position-based impedance control method. Then, the impedance control performance is tested by a HDU performance test platform. Further, the method of first-order sensitivity matrix is proposed
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For the hydraulic drive unit (HDU) on the joints of bionic legged robots, this paper proposes the position-based impedance control method. Then, the impedance control performance is tested by a HDU performance test platform. Further, the method of first-order sensitivity matrix is proposed to analyze the dynamic sensitivity of four main control parameters under four working conditions. To research the parameter sensitivity quantificationally, two sensitivity indexes are defined, and the sensitivity analysis results are verified by experiments. The results of the experiments show that, when combined with corresponding optimization strategies, the dynamic compliance composition theory and the results from sensitivity analysis can compensate for the control parameters and optimize the control performance in different working conditions. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle Macroporous Activated Carbon Derived from Rapeseed Shell for Lithium–Sulfur Batteries
Appl. Sci. 2017, 7(10), 1036; doi:10.3390/app7101036
Received: 12 September 2017 / Accepted: 28 September 2017 / Published: 10 October 2017
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Abstract
Lithium–sulfur batteries have drawn considerable attention because of their extremely high energy density. Activated carbon (AC) is an ideal matrix for sulfur because of its high specific surface area, large pore volume, small-size nanopores, and simple preparation. In this work, through KOH activation,
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Lithium–sulfur batteries have drawn considerable attention because of their extremely high energy density. Activated carbon (AC) is an ideal matrix for sulfur because of its high specific surface area, large pore volume, small-size nanopores, and simple preparation. In this work, through KOH activation, AC materials with different porous structure parameters were prepared using waste rapeseed shells as precursors. Effects of KOH amount, activated temperature, and activated time on pore structure parameters of ACs were studied. AC sample with optimal pore structure parameters was investigated as sulfur host materials. Applied in lithium–sulfur batteries, the AC/S composite (60 wt % sulfur) exhibited a high specific capacity of 1065 mAh g−1 at 200 mA g−1 and a good capacity retention of 49% after 1000 cycles at 1600 mA g−1. The key factor for good cycling stability involves the restraining effect of small-sized nanopores of the AC framework on the diffusion of polysulfides to bulk electrolyte and the loss of the active material sulfur. Results demonstrated that AC materials derived from rapeseed shells are promising materials for sulfur loading. Full article
(This article belongs to the Special Issue Electrode Materials for Lithium-ion Batteries/Super-capacitors)
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Open AccessArticle An Integrated Risk Index Model Based on Hierarchical Fuzzy Logic for Underground Risk Assessment
Appl. Sci. 2017, 7(10), 1037; doi:10.3390/app7101037
Received: 7 September 2017 / Revised: 2 October 2017 / Accepted: 7 October 2017 / Published: 11 October 2017
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Abstract
Available space in congested cities is getting scarce due to growing urbanization in the recent past. The utilization of underground space is considered as a solution to the limited space in smart cities. The numbers of underground facilities are growing day by day
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Available space in congested cities is getting scarce due to growing urbanization in the recent past. The utilization of underground space is considered as a solution to the limited space in smart cities. The numbers of underground facilities are growing day by day in the developing world. Typical underground facilities include the transit subway, parking lots, electric lines, water supply and sewer lines. The likelihood of the occurrence of accidents due to underground facilities is a random phenomenon. To avoid any accidental loss, a risk assessment method is required to conduct the continuous risk assessment and report any abnormality before it happens. In this paper, we have proposed a hierarchical fuzzy inference based model for under-ground risk assessment. The proposed hierarchical fuzzy inference architecture reduces the total number of rules from the rule base. Rule reduction is important because the curse of dimensionality damages the transparency and interpretation as it is very tough to understand and justify hundreds or thousands of fuzzy rules. The computation time also increases as rules increase. The proposed model takes 175 rules having eight input parameters to compute the risk index, and the conventional fuzzy logic requires 390,625 rules, having the same number of input parameters to compute risk index. Hence, the proposed model significantly reduces the curse of dimensionality. Rule design for fuzzy logic is also a tedious task. In this paper, we have also introduced new rule schemes, namely maximum rule-based and average rule-based; both schemes can be used interchangeably according to the logic needed for rule design. The experimental results show that the proposed method is a virtuous choice for risk index calculation where the numbers of variables are greater. Full article
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Open AccessArticle Deterministic and Robust Optimization Approach for Single Artillery Unit Fire Scheduling Problem
Appl. Sci. 2017, 7(10), 1038; doi:10.3390/app7101038
Received: 28 August 2017 / Revised: 22 September 2017 / Accepted: 9 October 2017 / Published: 11 October 2017
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Abstract
In this study, deterministic and robust optimization models for single artillery unit fire scheduling are developed to minimize the total enemy threat to friendly forces by considering the enemy target threat level, enemy target destruction time, and target firing preparation time simultaneously. Many
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In this study, deterministic and robust optimization models for single artillery unit fire scheduling are developed to minimize the total enemy threat to friendly forces by considering the enemy target threat level, enemy target destruction time, and target firing preparation time simultaneously. Many factors in war environments are uncertain. In particular, it is difficult to evaluate the threat levels of enemy targets definitively. We consider the threat level of an enemy target to be an uncertain parameter and propose a robust optimization model that minimizes the total enemy threat to friendly forces. The robust optimization model represents a semi-infinite problem that has infinitely many constraints. Therefore, we reformulate the robust optimization model into a tractable robust counterpart formulation with a finite number of constraints. In the robust counterpart formulation with cardinality-constrained uncertainty, the conservativeness and robustness of the solution can be adjusted with an uncertainty degree, Γ. Further, numerical experiments are conducted to verify that the robust counterpart formulation with cardinality-constrained uncertainty can be made equivalent to the deterministic optimization model and the robust counterpart formulation with box uncertainty by setting Γ accordingly. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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Open AccessArticle A Kriging Model Based Finite Element Model Updating Method for Damage Detection
Appl. Sci. 2017, 7(10), 1039; doi:10.3390/app7101039
Received: 29 August 2017 / Accepted: 1 October 2017 / Published: 11 October 2017
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Abstract
Model updating is an effective means of damage identification and surrogate modeling has attracted considerable attention for saving computational cost in finite element (FE) model updating, especially for large-scale structures. In this context, a surrogate model of frequency is normally constructed for damage
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Model updating is an effective means of damage identification and surrogate modeling has attracted considerable attention for saving computational cost in finite element (FE) model updating, especially for large-scale structures. In this context, a surrogate model of frequency is normally constructed for damage identification, while the frequency response function (FRF) is rarely used as it usually changes dramatically with updating parameters. This paper presents a new surrogate model based model updating method taking advantage of the measured FRFs. The Frequency Domain Assurance Criterion (FDAC) is used to build the objective function, whose nonlinear response surface is constructed by the Kriging model. Then, the efficient global optimization (EGO) algorithm is introduced to get the model updating results. The proposed method has good accuracy and robustness, which have been verified by a numerical simulation of a cantilever and experimental test data of a laboratory three-story structure. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Pipeline Damage Identification Based on Additional Virtual Masses
Appl. Sci. 2017, 7(10), 1040; doi:10.3390/app7101040
Received: 26 August 2017 / Revised: 25 September 2017 / Accepted: 1 October 2017 / Published: 11 October 2017
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Abstract
To improve the identification sensitivity of local damages in pipelines, we propose an added virtual mass method thatprevents adding real masses to the pipeline. First, we develop a method of adding virtual masses to pipelines based on the virtual distortion method (VDM). Second,
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To improve the identification sensitivity of local damages in pipelines, we propose an added virtual mass method thatprevents adding real masses to the pipeline. First, we develop a method of adding virtual masses to pipelines based on the virtual distortion method (VDM). Second, a frequency response to the added mass is constructed using the excitation and acceleration responses. The quantity of mass and the corresponding selected natural frequency with high sensitivity are both determined by the analyzing the sensitivity of the relationship between mass and natural frequency. Finally, the degree of damage can be accurately identified by adding virtual masses on the substructure of the pipeline combined with sensitivity and frequency. Using numerical simulations and experiments, we verify the feasibility of the added virtual mass method for the identification of damages to pipeline structures. Full article
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Open AccessArticle Interactions of Insolation and Shading on Ability to Use Fluorescence Imaging to Detect Fecal Contaminated Spinach
Appl. Sci. 2017, 7(10), 1041; doi:10.3390/app7101041
Received: 29 September 2017 / Accepted: 10 October 2017 / Published: 12 October 2017
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Abstract
Fecal contamination of produce in fields is a recognized food safety risk, and it is a requirement that fields be surveyed for evidence of fecal contamination. It may be possible to increase the efficacy of such surveys using imaging techniques that rely on
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Fecal contamination of produce in fields is a recognized food safety risk, and it is a requirement that fields be surveyed for evidence of fecal contamination. It may be possible to increase the efficacy of such surveys using imaging techniques that rely on detection of fluorescence responses of fecal material to UV excitation. However, fluorescence responses are easily masked by ambient illumination. This study investigated the potential of using a shroud to reduce the impact of ambient illumination on responses measured using relatively inexpensive optical components. During periods of near peak insolation, even with full shrouding, results indicate that reliable detection would be problematic. Towards dusk, effective imaging could be accomplished even with a gap of 250 cm at the bottom of the shroud. Results suggest that imaging using relatively inexpensive components could provide the basis for detection of fecal contamination in produce fields if surveys were conducted during dawn or dusk, or at night. Full article
(This article belongs to the Special Issue Hyperspectral Chemical Imaging for Food Authentication)
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Open AccessArticle Obstacle Avoidance with Potential Field Applied to a Rendezvous Maneuver
Appl. Sci. 2017, 7(10), 1042; doi:10.3390/app7101042
Received: 31 July 2017 / Revised: 26 September 2017 / Accepted: 26 September 2017 / Published: 12 October 2017
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Abstract
This paper outlines a method based on the theory of artificial potential fields combined with sliding mode techniques for spacecraft maneuvers in the presence of obstacles. Guidance and control algorithms are validated with a six degree-of-freed (dof) omorbital simulator. The idea of this
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This paper outlines a method based on the theory of artificial potential fields combined with sliding mode techniques for spacecraft maneuvers in the presence of obstacles. Guidance and control algorithms are validated with a six degree-of-freed (dof) omorbital simulator. The idea of this paper is to provide computationally efficient algorithms for real time applications, in which the combination of Artificial potential field (APF) and sliding mode control shows the ability of plan trajectories, even in the presence of external disturbances and model uncertainties. A reduced frequency of the proposed controllers and a pulse width modulation (PWM) of the thrusters are considered to verify the performance of the system. The computational performance of APF as a guidance algorithm is discussed and the algorithms are verified by simulations of a complete rendezvous maneuver. The proposed algorithm appears suitable for the autonomous, real-time control of complex maneuvers with a minimum on-board computational effort. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Synthesis and Thermoelectric Properties of TiO2/Cu2SnSe3 Composites
Appl. Sci. 2017, 7(10), 1043; doi:10.3390/app7101043
Received: 1 September 2017 / Accepted: 10 October 2017 / Published: 12 October 2017
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Abstract
Thermoelectric (TE) materials are a kind of energy material which can directly convert waste heat into electricity based on TE effects. Ternary Cu2SnSe3 material with diamond-like structure has become one of the potential TE materials due to its low thermal
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Thermoelectric (TE) materials are a kind of energy material which can directly convert waste heat into electricity based on TE effects. Ternary Cu2SnSe3 material with diamond-like structure has become one of the potential TE materials due to its low thermal conductivity and adjustable electrical conductivity. In this study, the Cu2SnSe3 powder was prepared by vacuum melting-quenching-annealing-grinding process. The nano-TiO2 particles were introduced into the Cu2SnSe3 matrix by ball milling. Spark plasma sintering (SPS) was employed to fabricate the TiO2/Cu2SnSe3 composites. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to study the phase and microstructure of TiO2/Cu2SnSe3 composites. Electrical resistivity, Seebeck coefficient, and thermal conductivity measurement were applied to analyze the thermoelectric properties. For the 1.4%TiO2/Cu2SnSe3 composite, the electrical conductivity was improved whereas the Seebeck coefficient was lower than that of pure Cu2SnSe3. For other TiO2/Cu2SnSe3 samples, the Seebeck coefficient was improved while the electrical conductivity was reduced. The thermal conductivity of TiO2/Cu2SnSe3 composites was lower than that of Cu2SnSe3 matrix, which is attributed to the lower carrier conductivity. A maximum ZT of 0.30 at 700 K for the 1.0%TiO2/Cu2SnSe3 composite was obtained, which was 17% higher than that of the pure Cu2SnSe3 at 700 K. Full article
(This article belongs to the Special Issue Recent Progress in the Development of Thermoelectric Materials)
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Open AccessArticle Soil–Structure–Equipment Interaction and Influence Factors in an Underground Electrical Substation under Seismic Loads
Appl. Sci. 2017, 7(10), 1044; doi:10.3390/app7101044
Received: 25 July 2017 / Revised: 27 August 2017 / Accepted: 25 September 2017 / Published: 12 October 2017
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Abstract
Underground electrical substations play an increasingly significant role in urban economic development for the power supply of subways. However, in recent years, there have been few studies on the seismic performance of underground electrical substations involving the interaction of soil–structure–equipment. To conduct the
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Underground electrical substations play an increasingly significant role in urban economic development for the power supply of subways. However, in recent years, there have been few studies on the seismic performance of underground electrical substations involving the interaction of soil–structure–equipment. To conduct the study, three-dimensional finite element models of an underground substation are established. The implicit dynamic numerical simulation analysis is performed by changing earthquake input motions, soil characteristics, electrical equipment type and structure depths. According to a seismic response analysis, acceleration amplification coefficients, displacements, stresses and internal forces are obtained and analyzed. It is found that (1) as a boundary condition of soil–structure, the coupling boundary is feasible in the seismic response of an underground substation; (2) the seismic response of an underground substation is sensitive to burial depth and elastic modulus; (3) the oblique incidence of input motion has a slight influence on the horizontal seismic response, but has a significant impact on the vertical seismic response; and (4) the bottom of the side wall is the seismic weak part of an underground substation, so it is necessary to increase the stiffness of this area. Full article
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