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Appl. Sci., Volume 7, Issue 8 (August 2017)

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Editorial

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Open AccessEditorial Special Issue on Polarimetric SAR Techniques and Applications
Appl. Sci. 2017, 7(8), 768; doi:10.3390/app7080768
Received: 26 July 2017 / Revised: 27 July 2017 / Accepted: 27 July 2017 / Published: 28 July 2017
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Abstract
Synthetic Aperture Radar (SAR) polarimetry is an active and fruitful field of research in Earth observation. [...]
Full article
(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)
Open AccessEditorial Guest Editors’ Note—Special Issue on Spatial Audio
Appl. Sci. 2017, 7(8), 788; doi:10.3390/app7080788
Received: 1 August 2017 / Revised: 2 August 2017 / Accepted: 2 August 2017 / Published: 3 August 2017
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(This article belongs to the Special Issue Spatial Audio)
Open AccessEditorial Structural Health Monitoring (SHM) of Civil Structures
Appl. Sci. 2017, 7(8), 789; doi:10.3390/app7080789
Received: 31 July 2017 / Revised: 31 July 2017 / Accepted: 31 July 2017 / Published: 4 August 2017
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Abstract
As newer and more reliable ways of construction were developed, civilization began to spread out further and retain functional infrastructure for longer periods of time.[...] Full article
(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)
Open AccessEditorial Energy Dissipation and Vibration Control: Modeling, Algorithm, and Devices
Appl. Sci. 2017, 7(8), 801; doi:10.3390/app7080801
Received: 31 July 2017 / Revised: 1 August 2017 / Accepted: 2 August 2017 / Published: 7 August 2017
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Abstract
The topic of vibration control and energy dissipation is among the oldest and most relevant in the field of engineering [...] Full article

Research

Jump to: Editorial, Review, Other

Open AccessArticle Needle Segmentation in Volumetric Optical Coherence Tomography Images for Ophthalmic Microsurgery
Appl. Sci. 2017, 7(8), 748; doi:10.3390/app7080748
Received: 22 June 2017 / Revised: 17 July 2017 / Accepted: 18 July 2017 / Published: 25 July 2017
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Abstract
Needle segmentation is a fundamental step for needle reconstruction and image-guided surgery. Although there has been success stories in needle segmentation for non-microsurgeries, the methods cannot be directly extended to ophthalmic surgery due to the challenges bounded to required spatial resolution. As the
[...] Read more.
Needle segmentation is a fundamental step for needle reconstruction and image-guided surgery. Although there has been success stories in needle segmentation for non-microsurgeries, the methods cannot be directly extended to ophthalmic surgery due to the challenges bounded to required spatial resolution. As the ophthalmic surgery is performed by finer and smaller surgical instruments in micro-structural anatomies, specifically in retinal domains, difficulties are raised for delicate operation and sensitive perception. To address these challenges, in this paper we investigate needle segmentation in ophthalmic operation on 60 Optical Coherence Tomography (OCT) cubes captured during needle injection surgeries on ex-vivo pig eyes. Furthermore, we developed two different approaches, a conventional method based on morphological features (MF) and a specifically designed full convolution neural networks (FCN) method, moreover, we evaluate them on the benchmark for needle segmentation in the volumetric OCT images. The experimental results show that FCN method has a better segmentation performance based on four evaluation metrics while MF method has a short inference time, which provides valuable reference for future works. Full article
(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))
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Open AccessArticle Prediction of Ultimate Strain and Strength of FRP-Confined Concrete Cylinders Using Soft Computing Methods
Appl. Sci. 2017, 7(8), 751; doi:10.3390/app7080751
Received: 13 June 2017 / Revised: 14 July 2017 / Accepted: 18 July 2017 / Published: 25 July 2017
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Abstract
This paper investigates the effectiveness of four different soft computing methods, namely radial basis neural network (RBNN), adaptive neuro fuzzy inference system (ANFIS) with subtractive clustering (ANFIS-SC), ANFIS with fuzzy c-means clustering (ANFIS-FCM) and M5 model tree (M5Tree), for predicting the ultimate strength
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This paper investigates the effectiveness of four different soft computing methods, namely radial basis neural network (RBNN), adaptive neuro fuzzy inference system (ANFIS) with subtractive clustering (ANFIS-SC), ANFIS with fuzzy c-means clustering (ANFIS-FCM) and M5 model tree (M5Tree), for predicting the ultimate strength and strain of concrete cylinders confined with fiber-reinforced polymer (FRP) sheets. The models were compared according to the root mean square error (RMSE), mean absolute relative error (MARE) and determination coefficient (R2) criteria. Similar accuracy was obtained by RBNN and ANFIS-FCM, and they provided better estimates in modeling ultimate strength of confined concrete. The ANFIS-SC, however, performed slightly better than the RBNN and ANFIS-FCM in estimating ultimate strain of confined concrete, and M5Tree provided the worst strength and strain estimates. Finally, the effects of strain ratio and the confinement stiffness ratio on strength and strain were investigated, and the confinement stiffness ratio was shown to be more effective. Full article
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Open AccessFeature PaperArticle Automated Diatom Classification (Part A): Handcrafted Feature Approaches
Appl. Sci. 2017, 7(8), 753; doi:10.3390/app7080753
Received: 31 May 2017 / Revised: 11 July 2017 / Accepted: 18 July 2017 / Published: 25 July 2017
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Abstract
This paper deals with automatic taxa identification based on machine learning methods. The aim is therefore to automatically classify diatoms, in terms of pattern recognition terminology. Diatoms are a kind of algae microorganism with high biodiversity at the species level, which are useful
[...] Read more.
This paper deals with automatic taxa identification based on machine learning methods. The aim is therefore to automatically classify diatoms, in terms of pattern recognition terminology. Diatoms are a kind of algae microorganism with high biodiversity at the species level, which are useful for water quality assessment. The most relevant features for diatom description and classification have been selected using an extensive dataset of 80 taxa with a minimum of 100 samples/taxon augmented to 300 samples/taxon. In addition to published morphological, statistical and textural descriptors, a new textural descriptor, Local Binary Patterns (LBP), to characterize the diatom’s valves, and a log Gabor implementation not tested before for this purpose are introduced in this paper. Results show an overall accuracy of 98.11% using bagging decision trees and combinations of descriptors. Finally, some phycological features of diatoms that are still difficult to integrate in computer systems are discussed for future work. Full article
(This article belongs to the Special Issue Automated Analysis and Identification of Phytoplankton Images)
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Open AccessArticle Modified Chaos Particle Swarm Optimization-Based Optimized Operation Model for Stand-Alone CCHP Microgrid
Appl. Sci. 2017, 7(8), 754; doi:10.3390/app7080754
Received: 21 June 2017 / Revised: 17 July 2017 / Accepted: 19 July 2017 / Published: 25 July 2017
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Abstract
The optimized dispatch of different distributed generations (DGs) in stand-alone microgrid (MG) is of great significance to the operation’s reliability and economy, especially for energy crisis and environmental pollution. Based on controllable load (CL) and combined cooling-heating-power (CCHP) model of micro-gas turbine (MT),
[...] Read more.
The optimized dispatch of different distributed generations (DGs) in stand-alone microgrid (MG) is of great significance to the operation’s reliability and economy, especially for energy crisis and environmental pollution. Based on controllable load (CL) and combined cooling-heating-power (CCHP) model of micro-gas turbine (MT), a multi-objective optimization model with relevant constraints to optimize the generation cost, load cut compensation and environmental benefit is proposed in this paper. The MG studied in this paper consists of photovoltaic (PV), wind turbine (WT), fuel cell (FC), diesel engine (DE), MT and energy storage (ES). Four typical scenarios were designed according to different day types (work day or weekend) and weather conditions (sunny or rainy) in view of the uncertainty of renewable energy in variable situations and load fluctuation. A modified dispatch strategy for CCHP is presented to further improve the operation economy without reducing the consumers’ comfort feeling. Chaotic optimization and elite retention strategy are introduced into basic particle swarm optimization (PSO) to propose modified chaos particle swarm optimization (MCPSO) whose search capability and convergence speed are improved greatly. Simulation results validate the correctness of the proposed model and the effectiveness of MCPSO algorithm in the optimized operation application of stand-alone MG. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Development of a Magnetostrictive FeNi Coated Surface Acoustic Wave Current Sensor
Appl. Sci. 2017, 7(8), 755; doi:10.3390/app7080755
Received: 7 July 2017 / Revised: 19 July 2017 / Accepted: 20 July 2017 / Published: 25 July 2017
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Abstract
A magnetostrictive FeNi-coated surface acoustic wave (SAW)-based current sensor was proposed in this work. The weak remanence and hysteresis effect of the FeNi itself contributes to suppress the asymmetry in sensor response at increasing and decreasing current. The sensor response was simulated by
[...] Read more.
A magnetostrictive FeNi-coated surface acoustic wave (SAW)-based current sensor was proposed in this work. The weak remanence and hysteresis effect of the FeNi itself contributes to suppress the asymmetry in sensor response at increasing and decreasing current. The sensor response was simulated by solving the coupled electromechanical field equation in layered structure considering the magnetostrictive effect and an approach of effective dielectric constant. The effects from the aspect ratio and thickness of the FeNi film on sensor response were analyzed to determine the optimal design parameters. Differential oscillation structure was used to form the sensor, in which, the FeNi thin film was deposited along the SAW propagation of the sensor chip by using RF magnetron sputtering. The magnetostrictive effect of the FeNi coating induced by the magnetic loading generates the perturbation in SAW velocity, and corresponding oscillation frequency. High sensitivity of 10.7 KHz/A, good linearity and repeatability, lower hysteresis error of 0.97% were obtained from the developed prototype 150 MHz SAW FeNi coated current sensor. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle A Real Model of a Micro-Grid to Improve Network Stability
Appl. Sci. 2017, 7(8), 757; doi:10.3390/app7080757
Received: 30 June 2017 / Revised: 14 July 2017 / Accepted: 22 July 2017 / Published: 26 July 2017
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Abstract
This paper discusses the smart energy model of a smart grid using a significant share of renewable energy sources combined with intelligent control that processes information from a smart metering subsystem. An algorithm to manage the microgrid via the demand-response strategy is proposed,
[...] Read more.
This paper discusses the smart energy model of a smart grid using a significant share of renewable energy sources combined with intelligent control that processes information from a smart metering subsystem. An algorithm to manage the microgrid via the demand-response strategy is proposed, accentuating the requirement that the total volume of energy produced from renewable sources is consumed. Thus, the system utilizes the maximum of renewable sources to reduce CO2 emissions. Another major benefit provided by the algorithm lies in applying the current weather forecast to predict the amount of energy in the grid; electricity can then be transferred between the local and the main backup batteries within the grid, and this option enables the control elements to prepare for a condition yet to occur. Individual parts of the grid are described in this research report together with the results provided by the relevant algorithm. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Performance Analysis and Design Strategy for a Second-Order, Fixed-Gain, Position-Velocity-Measured (α-β-η-θ) Tracking Filter
Appl. Sci. 2017, 7(8), 758; doi:10.3390/app7080758
Received: 29 June 2017 / Revised: 21 July 2017 / Accepted: 21 July 2017 / Published: 26 July 2017
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Abstract
We present a strategy for designing an α-β-η-θ filter, a fixed-gain moving-object tracking filter using position and velocity measurements. First, performance indices and stability conditions for the filter are analytically derived. Then, an optimal gain design strategy
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We present a strategy for designing an α - β - η - θ filter, a fixed-gain moving-object tracking filter using position and velocity measurements. First, performance indices and stability conditions for the filter are analytically derived. Then, an optimal gain design strategy using these results is proposed and its relationship to the position-velocity-measured (PVM) Kalman filter is shown. Numerical analyses demonstrate the effectiveness of the proposed strategy, as well as a performance improvement over the traditional position-only-measured α - β filter. Moreover, we apply an α - β - η - θ filter designed using this strategy to ultra-wideband Doppler radar tracking in numerical simulations. We verify that the proposed strategy can easily design the gains for an α - β - η - θ filter based on the performance of the ultra-wideband Doppler radar and a rough approximation of the target’s acceleration. Moreover, its effectiveness in predicting the steady state performance in designing the position-velocity-measured Kalman filter is also demonstrated. Full article
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Open AccessArticle A Novel Hybrid Approach to Deal with DVL Malfunctions for Underwater Integrated Navigation Systems
Appl. Sci. 2017, 7(8), 759; doi:10.3390/app7080759
Received: 14 June 2017 / Revised: 12 July 2017 / Accepted: 22 July 2017 / Published: 26 July 2017
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Abstract
As a common device for underwater integrated navigation systems, Doppler velocity log (DVL) has the risk of malfunction. To improve the reliability of navigation systems, a hybrid approach is presented to forecast the measurements of the DVL while it malfunctions. The approach employs
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As a common device for underwater integrated navigation systems, Doppler velocity log (DVL) has the risk of malfunction. To improve the reliability of navigation systems, a hybrid approach is presented to forecast the measurements of the DVL while it malfunctions. The approach employs partial least squares regression (PLSR) coupled with support vector regression (SVR) to build a hybrid predictor. As the current and past calculating velocities of strapdown inertial navigation system (SINS) are taken as the predictor’s inputs, PLSR is applied to cope with the situation where there exists intense relativity among independent variables. Since PLSR is a linear regression, SVR is used to predict the residual components of the PLSR prediction to improve the accuracy. When the DVL works well, the hybrid predictor is trained online as a backup, whereas during malfunctions, the predictor offers the estimation of the DVL measurements for information fusion. The performance of the proposed approach is verified with simulations based on SINS/DVL/MCP/pressure sensor (PS) integrated navigation system. The comparison results indicate that the PLSR-SVR hybrid predictor can correctly provide the estimated DVL measurements and effectively extend the tolerance time on DVL malfunctions, thereby improving the navigation accuracy and reliability. Full article
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Open AccessArticle The Static Frictional Behaviors of Rubber for Pipe-Laying Operation
Appl. Sci. 2017, 7(8), 760; doi:10.3390/app7080760
Received: 9 June 2017 / Revised: 7 July 2017 / Accepted: 20 July 2017 / Published: 26 July 2017
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Abstract
Experimental research is carried out to reveal the static frictional behaviors of rubber pipe contact systems. This research is motivated by deep water pipe-laying operations where rubber blocks are used to clamp the pipe to supply sufficient static friction. Within this context, a
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Experimental research is carried out to reveal the static frictional behaviors of rubber pipe contact systems. This research is motivated by deep water pipe-laying operations where rubber blocks are used to clamp the pipe to supply sufficient static friction. Within this context, a friction testing instrument has been designed to mimic a situation of the beginning of the pipe-laying installation. Using this instrument, the maximum static friction forces (F) of a rubber pipe contact system are tested. The results show that the ultimate values of the static frictions fluctuate due to the increasing rate of the tangential load (FT). The evolution of contact between rubber and polymethyl methacrylate (PMMA) pipe is observed to identify the formation and propagation of the folds within the apparent contact area. In addition, it is confirmed that the evolution of contact is influenced by the folds and creep of the rubber surface. The creep deformation takes primary effect in accelerating the separation of the interfaces of contact during relative high normal loads (20, 30, 40 N) and low increasing rate of FT; whereas for all of the testing normal loads (10–40 N), the propagation of the folds release the energy which is stored in the interface of rubber when the increasing rate of FT is high. Therefore, the fluctuation of the maximum static friction of the contact system can be regarded as a consequence of interaction of the creep and folds. Furthermore, the instability of the coefficient of static friction in this test has been examined, and it indicated that the creep and folds could affect the static friction distinctly within a certain range of a normal load. This research is beneficial for arranging appropriate normal loads and laying speeds to avoid pipes slipping during a pipe-laying operation. Full article
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Open AccessArticle A Tuning Method for Diatom Segmentation Techniques
Appl. Sci. 2017, 7(8), 762; doi:10.3390/app7080762
Received: 6 May 2017 / Revised: 14 June 2017 / Accepted: 22 June 2017 / Published: 27 July 2017
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Abstract
Phytoplankton such as diatoms or desmids are useful for monitoring water quality. Manual image analysis is impractical due to the huge diversity of this group of microalgae and its great morphological plasticity, hence the importance of automating the analysis procedure. High-resolution images of
[...] Read more.
Phytoplankton such as diatoms or desmids are useful for monitoring water quality. Manual image analysis is impractical due to the huge diversity of this group of microalgae and its great morphological plasticity, hence the importance of automating the analysis procedure. High-resolution images of phytoplankton cells can now be acquired by digital microscopes, which facilitate automating the analysis and identification process of specimens. Therefore, new systems of image analysis are potentially advantageous compared to manual methods of counting for solution identification. Segmentation is an important step in the analysis of phytoplankton images. Many standard techniques like thresholding and edge detection are employed in the segmentation of diatoms and other phytoplankton, which are crucial organisms in microscopy images. However, in general, they require several parameters to be fixed beforehand by the user in order to get the best results. This process is usually done by comparing results and looking for the best parameters. To automatize this process, we propose an automatic tuning method to find the optimal parameters in an iterative procedure, called Parametric Segmentation Tuning (PST). This technique compares successive segmentation results, choosing the ones that gets the maximal similarity. In this paper, tuning is formulated as an optimization problem using a similarity function within the solution space. This space consists of the set of binary images that are generated by the segmentation technique to be tuned, where these binary images are seen as a function of the original images and the segmentation parameters. The PST technique was tested with two of the most popular techniques employed to segment phytoplankton images: the Canny edge detection and a binarisation method. The results of the thresholding technique were validated by comparing them to those of the Otsu method and the Canny method with a ground truth. They show that PST is effective to find the best parameters. Full article
(This article belongs to the Special Issue Automated Analysis and Identification of Phytoplankton Images)
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Open AccessArticle Evaluation of Mechanical Properties of Recycled Material for Utilization in Asphalt Mixtures
Appl. Sci. 2017, 7(8), 763; doi:10.3390/app7080763
Received: 28 June 2017 / Revised: 17 July 2017 / Accepted: 18 July 2017 / Published: 27 July 2017
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Abstract
With an expanding world, the demand for extensive road networks is increasing. As natural resources become scarce, the necessity of finding alternative resources has led to the idea of applying recycled material to pavement construction including asphalt pavements. Amongst all asphalt components, aggregate
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With an expanding world, the demand for extensive road networks is increasing. As natural resources become scarce, the necessity of finding alternative resources has led to the idea of applying recycled material to pavement construction including asphalt pavements. Amongst all asphalt components, aggregate constitutes the largest part of asphalt mixtures. Therefore, the utilization of recycled material for aggregate will represent an important opportunity to save virgin material and divert material away from landfills. Because of the large amount of construction waste generation around the world, using recycled construction aggregate (RCA) in asphalt mixtures appears to be an effective utilization of RCA. However, as aggregate plays an important role in the final performance of the asphalt mixture, an understanding of their properties is essential in designing an asphalt mixture. Therefore, in this research, the properties of RCA have been evaluated through laboratory investigations. Based on the test results, it is required that combination of RCA with some other targeted waste materials be considered in asphalt mixture. This paper presents the results of an experimental study to evaluate the RCA properties as an alternative for virgin aggregate in asphalt mixture under different percentages and combination with other aggregates, such as reclaimed asphalt pavement (RAP) and basalt. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle 3D Model Identification Using Weighted Implicit Shape Representation and Panoramic View
Appl. Sci. 2017, 7(8), 764; doi:10.3390/app7080764
Received: 7 July 2017 / Revised: 21 July 2017 / Accepted: 25 July 2017 / Published: 27 July 2017
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Abstract
In this paper, we propose a 3 dimensional (3D) model identification method based on weighted implicit shape representation (WISR) and panoramic view. The WISR is used for 3D shape normalization. The 3D shape normalization method normalizes a 3D model by scaling, translation, and
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In this paper, we propose a 3 dimensional (3D) model identification method based on weighted implicit shape representation (WISR) and panoramic view. The WISR is used for 3D shape normalization. The 3D shape normalization method normalizes a 3D model by scaling, translation, and rotation with respect to the scale factor, center, and principal axes. The major advantage of the WISR is reduction of the influences caused by shape deformation and partial removal. The well-known scale-invariant feature transform descriptors are extracted from the panoramic view of the 3D model for feature matching. The panoramic view is a range image obtained by projecting a 3D model to the surface of a cylinder which is parallel to a principal axis determined by the 3D shape normalization. Because of using only one range image, the proposed method can provide small size of features and fast matching speed. The precision of the identification is 92% with 1200 models that consist of 24 deformed versions of 50 classes. The average feature size and matching time are 4.1 KB and 1.9 s. Full article
(This article belongs to the Special Issue Swarm Robotics)
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Open AccessArticle A Study on the Stall Detection of an Axial Compressor through Pressure Analysis
Appl. Sci. 2017, 7(8), 766; doi:10.3390/app7080766
Received: 5 June 2017 / Revised: 18 July 2017 / Accepted: 22 July 2017 / Published: 28 July 2017
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Abstract
In order to research the inherent working laws of compressors nearing stall state, a series of compressor experiments are conducted. With the help of fast Fourier transform, the amplitude–frequency characteristics of pressures at the compressor inlet, outlet and blade tip region outlet are
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In order to research the inherent working laws of compressors nearing stall state, a series of compressor experiments are conducted. With the help of fast Fourier transform, the amplitude–frequency characteristics of pressures at the compressor inlet, outlet and blade tip region outlet are analyzed. Meanwhile, devices imitating inlet distortion were applied in the compressor inlet distortion disturbance. The experimental results indicated that compressor blade tip region pressure showed a better performance than the compressor’s inlet and outlet pressures in regards to describing compressor characteristics. What’s more, compressor inlet distortion always disturbed the compressor pressure characteristics. Whether with inlet distortion or not, the pressure characteristics of pressure periodicity and amplitude frequency could always be maintained in compressor blade tip pressure. For the sake of compressor real-time stall detection application, a compressor stall detection algorithm is proposed to calculate the compressor pressure correlation coefficient. The algorithm also showed a good monotonicity in describing the relationship between the compressor surge margin and the pressure correlation coefficient. Full article
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Open AccessArticle Chinese Medical Question Answer Matching Using End-to-End Character-Level Multi-Scale CNNs
Appl. Sci. 2017, 7(8), 767; doi:10.3390/app7080767
Received: 4 July 2017 / Revised: 22 July 2017 / Accepted: 26 July 2017 / Published: 28 July 2017
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Abstract
This paper focuses mainly on the problem of Chinese medical question answer matching, which is arguably more challenging than open-domain question answer matching in English due to the combination of its domain-restricted nature and the language-specific features of Chinese. We present an end-to-end
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This paper focuses mainly on the problem of Chinese medical question answer matching, which is arguably more challenging than open-domain question answer matching in English due to the combination of its domain-restricted nature and the language-specific features of Chinese. We present an end-to-end character-level multi-scale convolutional neural framework in which character embeddings instead of word embeddings are used to avoid Chinese word segmentation in text preprocessing, and multi-scale convolutional neural networks (CNNs) are then introduced to extract contextual information from either question or answer sentences over different scales. The proposed framework can be trained with minimal human supervision and does not require any handcrafted features, rule-based patterns, or external resources. To validate our framework, we create a new text corpus, named cMedQA, by harvesting questions and answers from an online Chinese health and wellness community. The experimental results on the cMedQA dataset show that our framework significantly outperforms several strong baselines, and achieves an improvement of top-1 accuracy by up to 19%. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle The Synchrosqueezing Algorithm Based on Generalized S-transform for High-Precision Time-Frequency Analysis
Appl. Sci. 2017, 7(8), 769; doi:10.3390/app7080769
Received: 4 July 2017 / Revised: 23 July 2017 / Accepted: 26 July 2017 / Published: 28 July 2017
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Abstract
In this paper, a new time-frequency analysis method—Synchrosqueezing Generalized S-transform (SSGST)—is proposed to meet the needs of high-resolution seismic signal processing and interpretation. The basic wavelet of the generalized S-transform (GST) in the paper is a modulated harmonic wave with four undetermined parameters
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In this paper, a new time-frequency analysis method—Synchrosqueezing Generalized S-transform (SSGST)—is proposed to meet the needs of high-resolution seismic signal processing and interpretation. The basic wavelet of the generalized S-transform (GST) in the paper is a modulated harmonic wave with four undetermined parameters that can be constructed by adjusting the four parameters to make the GST more suitable for seismic signals processing. The SSGST method squeezes and reconstructs the complex coefficient spectra of GST results along the frequency direction so that the energy distributions on the time-frequency spectra are concentrated around the real instantaneous frequency of the signal; thus, the time-frequency resolution can be improved. Based on mathematical theory, the basic principle of the new transformation method is given, and the mathematical expressions of the positive transformation and lossless inverse transformation of the method are strictly deduced. The experimental results of numerical signals illustrate that the proposed method can correctly decompose signals with different spectral characteristics into a high time-frequency resolution spectrum and can recovery the original signal from the time-frequency spectrum with satisfying reconstructing accuracy. Application on field seismic data shows the superiority of the new method in seismic time-frequency analysis for hydrocarbon detection. Full article
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Open AccessArticle Using a Molecular Dynamics Simulation to Investigate Asphalt Nano-Cracking under External Loading Conditions
Appl. Sci. 2017, 7(8), 770; doi:10.3390/app7080770
Received: 8 June 2017 / Revised: 6 July 2017 / Accepted: 26 July 2017 / Published: 28 July 2017
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Abstract
Recent research shows that macro-scale cracking in asphalt binder may originate from its intrinsic defects at the nano-scale. In this paper, a molecular dynamics (MD) simulation was conducted to evaluate the nucleation of natural defects in asphalt. The asphalt microstructure was modeled using
[...] Read more.
Recent research shows that macro-scale cracking in asphalt binder may originate from its intrinsic defects at the nano-scale. In this paper, a molecular dynamics (MD) simulation was conducted to evaluate the nucleation of natural defects in asphalt. The asphalt microstructure was modeled using an ensemble of three different types of molecules to represent a constituent species: asphaltenes, naphthene aromatics and saturates, where the weight proportion of 20:60:20 was used to create an asphalt-like ensemble of molecules. Tension force was then applied on the molecular boundaries to study the crack initiation and propagation. It was discovered that the natural distribution of atoms at microscale would affect the intrinsic defects in asphalt and further influence crack initiation and propagation in asphalt. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle A Biomechanical Study for Developing Wearable-Sensor System to Prevent Hip Fractures among Seniors
Appl. Sci. 2017, 7(8), 771; doi:10.3390/app7080771
Received: 27 April 2017 / Revised: 20 July 2017 / Accepted: 27 July 2017 / Published: 30 July 2017
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Abstract
As the population ages, falls are becoming a major health problem, not only for those with some degree of balance or mobility impairment, but also among healthy active seniors. Previous studies suggest that the degradation of human sensorimotor function related to age contributes
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As the population ages, falls are becoming a major health problem, not only for those with some degree of balance or mobility impairment, but also among healthy active seniors. Previous studies suggest that the degradation of human sensorimotor function related to age contributes to falls. Hip bones are among the most frequently fractured body parts resulting from falls. Hip fractures are a frequent cause of early death, functional dependence, and high medical care costs. The current prevention method is to use hip protectors. Unfortunately, it often fails to do so because the pocket containing the pad can move away from the area during falls. Additionally, some seniors refuse to use hip protectors because they find them constraining. Hence, a new protector that is only activated during a fall is much desired. The current study explored the possibility via biomechanical analyses for building a wearable sensor system that triggers a mini-airbag system during a fall, i.e., the air-pad is only present for protection when a fall occurs. The results have revealed that two sensors placed on the left and right shoulder would be best for a detection of any-direction fall and could be applied for building a wearable sensor system for prevention of hip fractures resulting from falls. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Monitoring of Land-Surface Deformation in the Karamay Oilfield, Xinjiang, China, Using SAR Interferometry
Appl. Sci. 2017, 7(8), 772; doi:10.3390/app7080772
Received: 23 June 2017 / Revised: 26 July 2017 / Accepted: 27 July 2017 / Published: 30 July 2017
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Abstract
Synthetic Aperture Radar (SAR) interferometry is a technique that provides high-resolution measurements of the ground displacement associated with various geophysical processes. To investigate the land-surface deformation in Karamay, a typical oil-producing city in the Xinjiang Uyghur Autonomous Region, China, Advanced Land Observing Satellite
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Synthetic Aperture Radar (SAR) interferometry is a technique that provides high-resolution measurements of the ground displacement associated with various geophysical processes. To investigate the land-surface deformation in Karamay, a typical oil-producing city in the Xinjiang Uyghur Autonomous Region, China, Advanced Land Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) data were acquired for the period from 2007 to 2009, and a two-pass differential SAR interferometry (D-InSAR) process was applied. The experimental results showed that two sites in the north-eastern part of the city exhibit a clear indication of land deformation. For a further evaluation of the D-InSAR result, the Persistent Scatterer (PS) and Small Baseline Subset (SBAS)-InSAR techniques were applied for 21 time series Environmental Satellite (ENVISAT) C-band Advanced Synthetic Aperture Radar (ASAR) data from 2003 to 2010. The comparison between the D-InSAR and SBAS-InSAR measurements had better agreement than that from the PS-InSAR measurement. The maximum deformation rate attributed to subsurface water injection for the period from 2003 to 2010 was up to approximately 33 mm/year in the line of sight (LOS) direction. The interferometric phase change from November 2007 to June 2010 showed a clear deformation pattern, and the rebound center has been expanding in scale and increasing in quantity. Full article
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Open AccessArticle Thermal Energy Diffusion Incorporating Generalized Einstein Relation for Degenerate Semiconductors
Appl. Sci. 2017, 7(8), 773; doi:10.3390/app7080773
Received: 13 June 2017 / Revised: 18 July 2017 / Accepted: 25 July 2017 / Published: 31 July 2017
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Abstract
The currently used generalized Einstein relation for degenerate semiconductors with isotropic nonparabolic energy bands produces physically improper results, as well as losing numerical accuracy for large values of nonparabolicity parameters at room temperature. Therefore, a new generalized Einstein relation (a macroscopic equation and
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The currently used generalized Einstein relation for degenerate semiconductors with isotropic nonparabolic energy bands produces physically improper results, as well as losing numerical accuracy for large values of nonparabolicity parameters at room temperature. Therefore, a new generalized Einstein relation (a macroscopic equation and a formula) is derived from the semiclassical momentum balance equation based on a drift-diffusion approximation, by introducing a new concept of the effective temperature of a carrier gas for generalization of the classical kinetic theory for nonideal gases of carriers in semiconductors. The proposed formula takes into account the carrier thermal energy diffusion effect completely, so that it can accurately reflect the effect of band nonparabolicity on the ratio of the diffusion coefficient to the mobility for carriers in degenerate semiconductors. From the results evaluated with the formula, new and critically important nonparabolicity effects are observed. It is shown that the new generalized Einstein relation is valid for applied electrical fields of the full linear regime. In addition, useful figures are also presented, from which the ratio of the diffusion coefficient to mobility, as well as the Fermi energy, can be easily determined from the electron concentration, or doping density, for a given semiconductor material. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Electromagnetic Field Analysis of an Electric Dipole Antenna Based on a Surface Integral Equation in Multilayered Dissipative Media
Appl. Sci. 2017, 7(8), 774; doi:10.3390/app7080774
Received: 27 June 2017 / Revised: 19 July 2017 / Accepted: 27 July 2017 / Published: 30 July 2017
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Abstract
In this paper, a novel method based on the Poggio–Miller–Chang-Harrington–Wu–Tsai (PMCHWT) integral equation is presented to study the electromagnetic fields excited by vertical or horizontal electric dipoles in the presence of a layered region which consists of K-layered dissipative media and the
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In this paper, a novel method based on the Poggio–Miller–Chang-Harrington–Wu–Tsai (PMCHWT) integral equation is presented to study the electromagnetic fields excited by vertical or horizontal electric dipoles in the presence of a layered region which consists of K-layered dissipative media and the air above. To transform the continuous integral equation into a block tridiagonal matrix with the feature of convenient solution, the Rao–Wilton–Glisson (RWG) functions are introduced as expansion and testing functions. The electromagnetic fields excited by an electric dipole are calculated and compared with the available results, where the electric dipole antenna is buried in the non-planar air–sea–seabed, air–rock–earth–mine, and multilayered sphere structures. The analysis and computations demonstrate that the method exhibits high accuracy and solving performance in the near field propagation region. Full article
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Open AccessArticle Planetary Gearbox Fault diagnosis via Joint Amplitude and Frequency Demodulation Analysis Based on Variational Mode Decomposition
Appl. Sci. 2017, 7(8), 775; doi:10.3390/app7080775
Received: 26 June 2017 / Revised: 24 July 2017 / Accepted: 27 July 2017 / Published: 30 July 2017
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Abstract
Planetary gearbox vibration signals have strong modulation features due to the amplitude modulation and frequency modulation (AM-FM) effect of gear faults, as well as the amplitude modulation (AM) effect of time-varying vibration transfer paths, on gear meshing vibrations. This results in an involute
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Planetary gearbox vibration signals have strong modulation features due to the amplitude modulation and frequency modulation (AM-FM) effect of gear faults, as well as the amplitude modulation (AM) effect of time-varying vibration transfer paths, on gear meshing vibrations. This results in an involute sidebands structure in Fourier spectrum, possibly misleading fault diagnosis. The modulating frequency of both amplitude modulation (AM) and frequency modulation (FM) parts is closely related to the gear fault characteristic frequency. This inspires the idea of joint amplitude and frequency demodulation analysis, thus addressing the complex sidebands issue inherent in Fourier spectrum. Demodulation analysis requires mono-component signals for accurate estimation of instantaneous frequency, and proper selection of an AM-FM component sensitive to gear fault. To this end, we firstly decompose the complex signal into intrinsic mode functions (IMFs) via variational mode decomposition (VMD), by exploiting its capability in decomposing complex modulated signal into constituent AM-FM components. For effective application of VMD in complex planetary gearbox signal analysis, we propose a method to determine a key parameter in VMD, i.e. the number of IMFs to be separated. For accurate instantaneous frequency estimation, we decompose IMFs via empirical AM-FM decomposition, to remove the influence of AM on instantaneous frequency estimation. Then, we select the sensitive IMF that contains the main gear fault information for further demodulation analysis. In order to properly select the sensitive IMF, we propose a criterion based on the gear vibration characteristics and the VMD properties. Finally, we obtain the amplitude and frequency demodulated spectra by applying Fourier transform to the amplitude envelope and instantaneous frequency of the selected sensitive IMF. According to the characteristics exhibited in the demodulated spectra, we can detect planetary gearbox fault. The proposed method is illustrated via a numerical simulated planetary gearbox vibration signal, and is further validated using lab experimental vibration signals of a planetary gearbox. Faults on all the three types of gear (sun, planet and ring) are successfully identified. Full article
(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)
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Open AccessArticle Remote Servo Tuning System for Multi-Axis CNC Machine Tools Using a Virtual Machine Tool Approach
Appl. Sci. 2017, 7(8), 776; doi:10.3390/app7080776
Received: 14 June 2017 / Revised: 17 July 2017 / Accepted: 20 July 2017 / Published: 30 July 2017
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Abstract
Servo systems affect the performances of machining in accuracy and surface quality for high speed and precision machine tools. This study introduces an efficient servo tuning technique for Computer Numerical Control (CNC) feed drive systems using particle swarm optimization (PSO) algorithm by virtual
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Servo systems affect the performances of machining in accuracy and surface quality for high speed and precision machine tools. This study introduces an efficient servo tuning technique for Computer Numerical Control (CNC) feed drive systems using particle swarm optimization (PSO) algorithm by virtual machine tool approach. The proposed approach contained a system identification phase and a servo tuning phase based on the same bandwidth for all axes feed drive systems. The PSO algorithm was adopted to obtain the system parameters and maximize the corresponding bandwidth. An efficient two-step servo tuning method based on gain and phase margins was proposed for high speed and precision requirements. All feed drive systems controller gains were optimized simultaneously for synchronization. A remote system called Machine Dr. was established for servo tuning and monitoring. Simulation and experimental results were introduced to illustrate the effectiveness of the proposed approach. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessArticle A Framework for Proactive Resource Provisioning in IaaS Clouds
Appl. Sci. 2017, 7(8), 777; doi:10.3390/app7080777
Received: 30 June 2017 / Revised: 23 July 2017 / Accepted: 26 July 2017 / Published: 31 July 2017
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Abstract
Cloud computing is an emerging technology for rapidly provisioning and releasing resources on-demand from a shared resource pool. When big data is analyzed/mined on the cloud platform, the efficiency of resource provisioning would affect the system performance. This work proposes a framework for
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Cloud computing is an emerging technology for rapidly provisioning and releasing resources on-demand from a shared resource pool. When big data is analyzed/mined on the cloud platform, the efficiency of resource provisioning would affect the system performance. This work proposes a framework for proactive resource provisioning in IaaS (Infrastructure as a Service) clouds to improve system performance. The proposed framework consists of the virtual cluster computing system, the profiling system, the resource management system, and the monitoring system. In this framework, the over-commit mechanism is applied to improve resource utilization. Furthermore, a proactive task scheduling approach is also present to prevent the postponement of tasks in critical stages, especially when the amount of aggregated resources requested by virtual machines exceeds that of available resources on the over-committed physical machines. Experimental results show that the over-commit approach indeed improves the resource utilization. However, when the degree of applying the over-commit approach increases, the burden of this proposed approach also conceivably increases. Therefore, the proposed framework further applies the proactive task scheduling approach to execute the time-critical tasks earlier to shorten the processing time. A small-scale cloud system including 3 servers is built for experiments. Preliminary experimental results show the performance improvement of our proposed framework in IaaS clouds. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessFeature PaperArticle Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet
Appl. Sci. 2017, 7(8), 778; doi:10.3390/app7080778
Received: 29 June 2017 / Revised: 22 July 2017 / Accepted: 24 July 2017 / Published: 31 July 2017
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Abstract
Reverse osmosis (RO) concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2) and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate
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Reverse osmosis (RO) concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2) and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO2/zeolite composite sheet. The RO concentrate was obtained from a pilot-scale municipal secondary effluent reclamation plant. Effective immobilization of the two powders in the sheet made it easy to handle and to separate the photocatalyst and adsorbent from purified water. The TiO2/zeolite composite sheet showed excellent performance for crotamiton adsorption without obvious inhibition by other components in the RO concentrate. With ultraviolet irradiation, crotamiton was simultaneously removed through adsorption and photocatalysis. The photocatalytic decomposition of crotamiton in the RO concentrate was significantly inhibited by the water matrix at high initial crotamiton concentrations, whereas rapid decomposition was achieved at low initial crotamiton concentrations. The major degradation intermediates were also adsorbed by the composite sheet. This result provides a promising method of mitigating secondary pollution caused by the harmful intermediates produced during advanced oxidation processes. The cyclic use of the HSZ-385/P25 composite sheet indicated the feasibility of continuously removing crotamiton from RO concentrate. Full article
(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)
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Open AccessFeature PaperArticle Mechanical Resilience of Modified Bitumen at Different Cooling Rates: A Rheological and Atomic Force Microscopy Investigation
Appl. Sci. 2017, 7(8), 779; doi:10.3390/app7080779
Received: 8 July 2017 / Revised: 26 July 2017 / Accepted: 28 July 2017 / Published: 31 July 2017
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Abstract
Due to the wide variation in geographic and climatic conditions, the search for high-performance bituminous materials is becoming more and more urgent to increase the useful life of pavements and reduce the enormous cost of road maintenance. Extensive research has been done by
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Due to the wide variation in geographic and climatic conditions, the search for high-performance bituminous materials is becoming more and more urgent to increase the useful life of pavements and reduce the enormous cost of road maintenance. Extensive research has been done by testing various bitumen modifiers, although most of them are petroleum-derived additives, such as polymers, rubbers and plastic, which in turn do not prevent oxidative aging of the binder. Thus, as an alternative to the most common polymeric rheological modifiers, selected binder additives falling in the categories of organosilane (P2KA), polyphosphoric acid (PPA) and food grade phospholipids (LCS) were homogeneously mixed to a base bitumen. The goal was to analyse the micro-morphology of the bitumens (neat and modified) subjected to different cooling rates and to find the corresponding correlations in the mechanical response domain. Therefore, microstructural investigations carried out by Atomic Force Microscopy (AFM) and fundamental rheological tests based on oscillatory dynamic rheology, were used to evaluate the effect of additives on the bitumen structure and compared with pristine binder as a reference. The tested bitumen additives have been shown to elicit different mechanical behaviours by varying the cooling rate. By comparing rheological data, analysed in the framework of the “weak gel” model, and AFM images, it was found that both P2KA and PPA altered the material structure in a different manner whereas LCS revealed superior performances, acting as “mechanical buffer” in the whole explored range of cooling rates. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle An Improved Dispatching Method (a-HPDB) for Automated Material Handling System with Active Rolling Belt for 450 mm Wafer Fabrication
Appl. Sci. 2017, 7(8), 780; doi:10.3390/app7080780
Received: 9 July 2017 / Revised: 28 July 2017 / Accepted: 29 July 2017 / Published: 31 July 2017
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Abstract
The semiconductor industry is facing the transition from 300 mm to 450 mm wafer fabrication. Due to the increased size and weight, 450 mm wafers will pose unprecedented challenges on semiconductor wafer fabrication. To better handle and transport 450 mm wafers, an advanced
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The semiconductor industry is facing the transition from 300 mm to 450 mm wafer fabrication. Due to the increased size and weight, 450 mm wafers will pose unprecedented challenges on semiconductor wafer fabrication. To better handle and transport 450 mm wafers, an advanced Automated Material Handling System (AMHS) is definitely required. Though conveyor-based AMHS is expected to be suitable for 450 mm wafer fabrication, still it faces two main problems, traffic-jam problem and lot-prioritization. To address the two problems, in this research we have proposed an improved dispatching method, termed Heuristic Preemptive Dispatching Method using Activated Roller Belt (a-HPDB). We have developed some effective rules for the a-HPDB based on Activated Roller Belt (ARB). In addition, we have conducted experiments to investigate its effectiveness. Compared with the HPDB and R-HPD, two dispatching rules proposed in previous studies, our experimental results showed the a-HPDB had a better performance in terms of average lot delivery time (ALDT). For hot lots and normal lots, the a-HPDB had advantages of 4.14% and 8.92% over the HPDB and advantages of 4.89% and 8.52% over R-HPD, respectively. 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 New Damage Assessment Method by Means of Neural Network and Multi-Sensor Satellite Data
Appl. Sci. 2017, 7(8), 781; doi:10.3390/app7080781
Received: 29 June 2017 / Revised: 24 July 2017 / Accepted: 26 July 2017 / Published: 1 August 2017
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Abstract
Artificial Neural Network (ANN) is a valuable and well-established inversion technique for the estimation of geophysical parameters from satellite images. After training, ANNs are able to generate very fast products for several types of applications. Satellite remote sensing is an efficient way to
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Artificial Neural Network (ANN) is a valuable and well-established inversion technique for the estimation of geophysical parameters from satellite images. After training, ANNs are able to generate very fast products for several types of applications. Satellite remote sensing is an efficient way to detect and map strong earthquake damage for contributing to post-disaster activities during emergency phases. This work aims at presenting an application of the ANN inversion technique addressed to the evaluation of building collapse ratio (CR), defined as the number of collapsed buildings with respect to the total number of buildings in a city block, by employing optical and SAR satellite data. This is done in order to directly relate changes in images with damage that has occurred during strong earthquakes. Furthermore, once they have been trained, neural networks can be used rapidly at application stage. The goal was to obtain a general tool suitable for re-use in different scenarios. An ANN has been implemented in order to emulate a regression model and to estimate the CR as a continuous function. The adopted ANN has been trained using some features obtained from optical and Synthetic Aperture Radar (SAR) images, as inputs, and the corresponding values of collapse ratio obtained from the survey of the 2010 M7 Haiti Earthquake, i.e., as target output. As regards the optical data, we selected three change parameters: the Normalized Difference Index (NDI), the Kullback–Leibler divergence (KLD), and Mutual Information (MI). Concerning the SAR images, the Intensity Correlation Difference (ICD) and the KLD parameters have been considered. Exploiting an object-oriented approach, a segmentation of the study area into several regions has been performed. In particular, damage maps have been generated by considering a set of polygons (in which satellite parameters have been calculated) extracted from the open source Open Street Map (OSM) geo-database. The trained ANN has been proposed for the M6.0 Amatrice earthquake that occurred on 24 August 2016, in central Italy, by using the features extracted from Sentinel-2 and COSMO-SkyMed images as input. The results show that the ANN is able to retrieve a building collapse ratio with good accuracy. In particular, the fusion approach modelled the collapse ratio characterized by high values of CR (more than 0.5) over the historical center that agrees with observed damages. Since the technique is independent from different typologies of input data (i.e., for radiometric or spatial resolution characteristics), the study demonstrated the strength of the proposed approach for estimating damaged areas and its importance in near real time monitoring activities, owing to its fast application. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Enhancement of Sea Wave Potential Energy with Under-Sea Periodic Structures: A Simulation and Laboratory Study
Appl. Sci. 2017, 7(8), 782; doi:10.3390/app7080782
Received: 29 June 2017 / Revised: 26 July 2017 / Accepted: 28 July 2017 / Published: 2 August 2017
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Abstract
This paper is devoted to a theoretical investigation on the wave amplitude enhancement of surface sea water waves with under-sea periodic arrays of cylinders. A two-dimensional shallow water wave equation is derived and solved by using the plane-wave expansion method. The lattice types
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This paper is devoted to a theoretical investigation on the wave amplitude enhancement of surface sea water waves with under-sea periodic arrays of cylinders. A two-dimensional shallow water wave equation is derived and solved by using the plane-wave expansion method. The lattice types studied here include triangular, square and hexagonal lattices. These under-sea structures alter the sea bottom topography and induce constructive interference on the surface water waves. Given that the wave potential energy is dependent on the square of the wave amplitude, this mechanism can thus be used to increase the potential energy. It is shown that the enhancement factor depends on two geometric parameters and the maximum wave amplitude can be found by adjusting the two geometric parameters. Among the lattice types, the triangular and square lattice structures can induce more wave amplitude enhancement (and thus potential energy) than the hexagonal structures. Guided by numerical simulations, we have performed a reduced-scale water tank experiment to demonstrate the feasibility of the proposed idea. Preliminary experimental results show promising evidence of the predicted wave amplitude enhancement, suggesting perspective real-scale nearshore deployment and test. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessFeature PaperArticle Comparison of Basic Notch Filters for Semiconductor Optical Amplifier Pattern Effect Mitigation
Appl. Sci. 2017, 7(8), 783; doi:10.3390/app7080783
Received: 12 July 2017 / Revised: 28 July 2017 / Accepted: 28 July 2017 / Published: 2 August 2017
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Abstract
We conduct a thorough comparison of two basic notch filters employed to mitigate the pattern effect that manifests when semiconductor optical amplifiers (SOAs) serve linear amplification purposes. The filters are implemented using as the building architecture the optical delay interferometer (ODI) and the
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We conduct a thorough comparison of two basic notch filters employed to mitigate the pattern effect that manifests when semiconductor optical amplifiers (SOAs) serve linear amplification purposes. The filters are implemented using as the building architecture the optical delay interferometer (ODI) and the microring resonator (MRR). We formulate and follow a rational procedure, which involves identifying and applying the appropriate conditions for the filters’ spectral response slope related to the SOA pattern effect suppression mechanism. We thus extract the values of the free spectral range and detuning of each filter, which allow one to equivocally realize the pursued comparison. We define suitable performance metrics and obtain simulation results for each filter. The quantitative comparison reveals that most employed metrics are better with the MRR than with the ODI. Although the difference in performance is small, it is sufficient to justify considering also using the MRR for the intended purpose. Finally, we concisely discuss practical implementation issues of these notch filters and further make a qualitative comparison between them in terms of their inherent advantages and disadvantages. This discussion reveals that each scheme has distinct features that render it appropriate for supporting SOA direct signal amplification applications with a suppressed pattern effect. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessArticle Comparative Performance of Thermoacoustic Heat Exchangers with Different Pore Geometries in Oscillatory Flow. Implementation of Experimental Techniques
Appl. Sci. 2017, 7(8), 784; doi:10.3390/app7080784
Received: 24 July 2017 / Revised: 31 July 2017 / Accepted: 31 July 2017 / Published: 2 August 2017
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Abstract
Heat exchangers (HXs) constitute key components of thermoacoustic devices and play an important role in determining the overall engine performance. In oscillatory flow conditions, however, standard heat transfer correlations for steady flows cannot be directly applied to thermoacoustic HXs, for which reliable and
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Heat exchangers (HXs) constitute key components of thermoacoustic devices and play an important role in determining the overall engine performance. In oscillatory flow conditions, however, standard heat transfer correlations for steady flows cannot be directly applied to thermoacoustic HXs, for which reliable and univocal design criteria are still lacking. This work is concerned with the initial stage of a research aimed at studying the thermal performance of thermoacoustic HXs. The paper reports a detailed discussion of the design and fabrication of the experimental set-up, measurement methodology and test-HXs characterized by two different pore geometries, namely a circular pore geometry and a rectangular (i.e., straight fins) pore geometry. The test rig is constituted by a standing wave engine where the test HXs play the role of ambient HXs. The experiment is conceived to allow the variation of a range of testing conditions such as drive ratio, operation frequency, acoustic particle velocity, etc. The procedure for estimating the gas side heat transfer coefficient for the two involved geometries is described. Some preliminary experimental results concerning the HX with straight fins are also shown. The present research could help in achieving a deeper understanding of the heat transfer processes affecting HXs under oscillating flow regime and in developing design optimization procedures. Full article
(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)
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Open AccessArticle An Efficient Synthesis of Novel Pyrazole-Based Heterocycles as Potential Antitumor Agents
Appl. Sci. 2017, 7(8), 785; doi:10.3390/app7080785
Received: 22 July 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
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Abstract
A new series of pyrazolylpyridines was prepared by reaction of ethyl-3-acetyl-1,5-diphenyl-1H-pyrazole-4-carboxylate with the appropriate aldehyde, malononitrile, or ethyl acetoacetate and an excess of ammonium acetate under reflux in acetic acid. Similarly, two novel bipyridine derivatives were prepared by the above reaction
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A new series of pyrazolylpyridines was prepared by reaction of ethyl-3-acetyl-1,5-diphenyl-1H-pyrazole-4-carboxylate with the appropriate aldehyde, malononitrile, or ethyl acetoacetate and an excess of ammonium acetate under reflux in acetic acid. Similarly, two novel bipyridine derivatives were prepared by the above reaction using terephthaldehyde in lieu of benzaldehyde derivatives. In addition, a series of 1,2,4-triazolo[4,3-a]pyrimidines was synthesized by a reaction of 6-(pyrazol-3-yl)pyrimidine-2-thione with a number of hydrazonoyl chlorides in dioxane and in the presence of triethylamine. The structure of the produced compounds was established by elemental analyses and spectral methods, and the mechanisms of their formation was discussed. Furthermore, the pyrazolyl-pyridine derivatives were tested as anticancer agents and the results obtained showed that some of them revealed high activity against human hepatocellular carcinoma (HEPG2) cell lines. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle A Feature-Based Structural Measure: An Image Similarity Measure for Face Recognition
Appl. Sci. 2017, 7(8), 786; doi:10.3390/app7080786
Received: 4 July 2017 / Revised: 25 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
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Abstract
Facial recognition is one of the most challenging and interesting problems within the field of computer vision and pattern recognition. During the last few years, it has gained special attention due to its importance in relation to current issues such as security, surveillance
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Facial recognition is one of the most challenging and interesting problems within the field of computer vision and pattern recognition. During the last few years, it has gained special attention due to its importance in relation to current issues such as security, surveillance systems and forensics analysis. Despite this high level of attention to facial recognition, the success is still limited by certain conditions; there is no method which gives reliable results in all situations. In this paper, we propose an efficient similarity index that resolves the shortcomings of the existing measures of feature and structural similarity. This measure, called the Feature-Based Structural Measure (FSM), combines the best features of the well-known SSIM (structural similarity index measure) and FSIM (feature similarity index measure) approaches, striking a balance between performance for similar and dissimilar images of human faces. In addition to the statistical structural properties provided by SSIM, edge detection is incorporated in FSM as a distinctive structural feature. Its performance is tested for a wide range of PSNR (peak signal-to-noise ratio), using ORL (Olivetti Research Laboratory, now AT&T Laboratory Cambridge) and FEI (Faculty of Industrial Engineering, São Bernardo do Campo, São Paulo, Brazil) databases. The proposed measure is tested under conditions of Gaussian noise; simulation results show that the proposed FSM outperforms the well-known SSIM and FSIM approaches in its efficiency of similarity detection and recognition of human faces. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Novel Reactive Power Optimization in Distribution Network Based on Typical Scenarios Partitioning and Load Distribution Matching Method
Appl. Sci. 2017, 7(8), 787; doi:10.3390/app7080787
Received: 8 June 2017 / Revised: 25 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
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Abstract
This paper proposed an entropy weight optimum seeking method (EWOSM) based on the typical scenarios partitioning and load distribution matching, to solve the reactive power optimization problem in distribution network under the background of big data. Firstly, the mathematic model of reactive power
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This paper proposed an entropy weight optimum seeking method (EWOSM) based on the typical scenarios partitioning and load distribution matching, to solve the reactive power optimization problem in distribution network under the background of big data. Firstly, the mathematic model of reactive power optimization is provided to analyze the relationship between the data source and the optimization schemes in distribution network, which illustrate the feasibility of using large amount of historical data to solve reactive power optimization. Then, the typical scenarios partitioning method and load distribution matching method are presented, which can select out some loads that have the same or similar distributions with the load to be optimized from historical database rapidly, and the corresponding historical optimization schemes are used as the alternatives. As the reactive power optimization is a multi-objective problem, the multi-attribute decision making method based on entropy weight method is used to select out the optimal scheme from the alternatives. The objective weights of evaluation indexes are determined by entropy weight method, and then the multi-attribute decision making problem is transformed to a single attribute decision making problem. Finally, the proposed method is tested on several systems with different scales and compared with existing methods to prove the validity and superiority. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Experimental Tests and Aeroacoustic Simulations of the Control of Cavity Tone by Plasma Actuators
Appl. Sci. 2017, 7(8), 790; doi:10.3390/app7080790
Received: 18 July 2017 / Revised: 2 August 2017 / Accepted: 3 August 2017 / Published: 4 August 2017
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Abstract
A plasma actuator comprising a dielectric layer sandwiched between upper and lower electrodes can induce a flow from the upper to lower electrode by means of an externally-applied electric field. Our objective is to clarify the mechanism by which such actuators can control
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A plasma actuator comprising a dielectric layer sandwiched between upper and lower electrodes can induce a flow from the upper to lower electrode by means of an externally-applied electric field. Our objective is to clarify the mechanism by which such actuators can control the cavity tone. Plasma actuators, with the electrodes elongated in the streamwise direction and aligned in the spanwise direction, were placed in the incoming boundary of a deep cavity with a depth-to-length ratio of 2.5. By using this experimental arrangement, the amount of sound reduction (“control effect”) produced by actuators of differing dimensions was measured. Direct aeroacoustic simulations were performed for controlling the cavity tone by using these actuators, where the distributions of the body forces applied by the actuators were determined from measurements of the plasma luminescence. The predicted control effects on the flow and sound fields were found to agree well with the experimental results. The simulations show that longitudinal streamwise vortices are introduced in the incoming boundary by the actuators, and the vortices form rib structures in the cavity flow. These vortices distort and weaken the two-dimensional vortices responsible for producing the cavity tone, causing the tonal sound to be reduced. Full article
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Open AccessArticle Reliability-Based and Cost-Oriented Product Optimization Integrating Fuzzy Reasoning Petri Nets, Interval Expert Evaluation and Cultural-Based DMOPSO Using Crowding Distance Sorting
Appl. Sci. 2017, 7(8), 791; doi:10.3390/app7080791
Received: 4 July 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 4 August 2017
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Abstract
In reliability-based and cost-oriented product optimization, the target product reliability is apportioned to subsystems or components to achieve the maximum reliability and minimum cost. Main challenges to conducting such optimization design lie in how to simultaneously consider subsystem division, uncertain evaluation provided by
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In reliability-based and cost-oriented product optimization, the target product reliability is apportioned to subsystems or components to achieve the maximum reliability and minimum cost. Main challenges to conducting such optimization design lie in how to simultaneously consider subsystem division, uncertain evaluation provided by experts for essential factors, and dynamic propagation of product failure. To overcome these problems, a reliability-based and cost-oriented product optimization method integrating fuzzy reasoning Petri net (FRPN), interval expert evaluation and cultural-based dynamic multi-objective particle swarm optimization (DMOPSO) using crowding distance sorting is proposed in this paper. Subsystem division is performed based on failure decoupling, and then subsystem weights are calculated with FRPN reflecting dynamic and uncertain failure propagation, as well as interval expert evaluation considering six essential factors. A mathematical model of reliability-based and cost-oriented product optimization is established, and the cultural-based DMOPSO with crowding distance sorting is utilized to obtain the optimized design scheme. The efficiency and effectiveness of the proposed method are demonstrated by the numerical example of the optimization design for a computer numerically controlled (CNC) machine tool. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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Open AccessArticle Contact Pressure and Strain Energy Density of Hyperelastic U-shaped Monolithic Seals under Axial and Radial Compressions in an Insulating Joint: A Numerical Study
Appl. Sci. 2017, 7(8), 792; doi:10.3390/app7080792
Received: 7 July 2017 / Revised: 26 July 2017 / Accepted: 1 August 2017 / Published: 4 August 2017
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Abstract
In insulation joints, elastomeric U-shaped monolithic seals (UMSs) are replacing O-ring systems because of their enhanced sealing capabilities for the oil and gas industries. UMSs are compressed axially during assembly and radially when pressurized in operation. The reliability of UMSs due to the
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In insulation joints, elastomeric U-shaped monolithic seals (UMSs) are replacing O-ring systems because of their enhanced sealing capabilities for the oil and gas industries. UMSs are compressed axially during assembly and radially when pressurized in operation. The reliability of UMSs due to the displacement imposed during assembly and the internal pressure in operation is influenced by the axial compression ratio, thickness ratio (TR), and geometric complexity. In this study, the hyperelastic behavior of elastomeric UMSs under axial and radial compressions is investigated using axisymmetric finite-element analysis. Twelve examples of UMSs with three geometric restraints (open grooves on both sides (type 1), an open groove on one side only (type 2), and no groove (type 3)) and four thickness ratios (TR = 0.25, 0.50, 1.00, and 1.50) are evaluated. To analyze nonlinear elastomeric materials, neo-Hookean constitutive equations are applied and the UMSs are considered as being a nearly incompressible hyperelastic material with a Poisson’s ratio of 0.499. The failure and detachment risks of UMSs are analyzed in terms of the equivalent stress, gap distance, contact pressure, and strain energy density. It is advantageous that the smaller the TR, the smaller the stress distribution. However, the generation of broader detachment regions is observed. Type 1 symmetrically shows the lowest stress distribution and the smallest detachment region, whereas type 3 symmetrically shows the highest values. Type 3 (TR = 0.25) shows the broadest detachment region in the arc-length range from −15.7 to 15.7 mm, whereas the largest gap of 0.7 mm is observed in type 2 (TR = 0.5). For all types, the detachment region disappears completely at TR = 1.0 or higher, which implies that full sealing is occurring. The average contact pressure increases exponentially during axial compression (in assembly) and linearly during radial compression (in operation). The largest contact pressure of 31.5 MPa is observed in type 3 (TR = 1.5), while the lowest is observed in type 1 (TR = 0.25). As for the strain energy density, type 3 at TR = 0.25 shows the largest increase in the strain energy density with 1.75 MJ/m3, while type 1 shows the most stable values of all cases. In conclusion, the lowest risk of failure of a nonlinear hyperelastic UMS was investigated numerically with minor equivalent stress and detachment region with higher contact pressure, which can be taken into account to ensure the reliability of the UMS. Full article
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Open AccessFeature PaperArticle Effect of Organic Stabilizers on Silver Nanoparticles Fabricated by Femtosecond Pulsed Laser Ablation
Appl. Sci. 2017, 7(8), 793; doi:10.3390/app7080793
Received: 16 June 2017 / Revised: 28 July 2017 / Accepted: 2 August 2017 / Published: 4 August 2017
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Abstract
Laser ablation has several advantages over the chemical synthesis of nanoparticles due to its simplicity and because it is a faster and cleaner process. In this paper, we use femtosecond laser ablation to generate highly concentrated silver colloidal nanoparticle solutions. Those high concentrations
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Laser ablation has several advantages over the chemical synthesis of nanoparticles due to its simplicity and because it is a faster and cleaner process. In this paper, we use femtosecond laser ablation to generate highly concentrated silver colloidal nanoparticle solutions. Those high concentrations usually lead to agglomeration of the nanoparticles, rendering the solution nearly useless. We employ two different organic stabilizers (hexadecyltrimethylammonium bromide, CTAB, and polyvinylpyrrolidone, PVP) to avoid this problem and study their effect on the nanoparticle size distribution, structural characteristics, and the solution concentration. Full article
(This article belongs to the Special Issue Laser Interaction with Plasmonic Nanostructures)
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Open AccessArticle Improving Asphalt Mixture Performance by Partially Replacing Bitumen with Waste Motor Oil and Elastomer Modifiers
Appl. Sci. 2017, 7(8), 794; doi:10.3390/app7080794
Received: 21 July 2017 / Revised: 1 August 2017 / Accepted: 2 August 2017 / Published: 5 August 2017
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Abstract
The environmental concern about waste generation and the gradual decrease of oil reserves has led the way to finding new waste materials that may partially replace the bitumens used in the road paving industry. Used motor oil from vehicles is a waste product
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The environmental concern about waste generation and the gradual decrease of oil reserves has led the way to finding new waste materials that may partially replace the bitumens used in the road paving industry. Used motor oil from vehicles is a waste product that could answer that demand, but it can also drastically reduce the viscosity, increasing the asphalt mixture’s rutting potential. Therefore, polymer modification should be used in order to avoid compromising the required performance of asphalt mixtures when higher amounts of waste motor oil are used. Thus, this study was aimed at assessing the performance of an asphalt binder/mixture obtained by replacing part of a paving grade bitumen (35/50) with 10% waste motor oil and 5% styrene-butadiene-styrene (SBS) as an elastomer modifier. A comparison was also made with the results of a previous study using a blend of bio-oil from fast pyrolysis and ground tire rubber modifier as a partial substitute for usual PG64-22 bitumen. The asphalt binders were tested by means of Fourier infrared spectra and dynamic shear rheology, namely by assessing their continuous high-performance grade. Later, the water sensitivity, fatigue cracking resistance, dynamic modulus and rut resistance performance of the resulting asphalt mixtures was evaluated. It was concluded that the new binder studied in this work improves the asphalt mixture’s performance, making it an excellent solution for paving works. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle An Innovative Dual-Column System for Heavy Metallic Ion Sorption by Natural Zeolite
Appl. Sci. 2017, 7(8), 795; doi:10.3390/app7080795
Received: 7 July 2017 / Revised: 1 August 2017 / Accepted: 2 August 2017 / Published: 5 August 2017
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Abstract
This study investigates the design and performance of a novel sorption system containing natural zeolite. The apparatus consists of packed, fixed-bed, dual-columns with custom automated controls and sampling chambers, connected in series and stock fed by a metering pump at a controlled adjustable
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This study investigates the design and performance of a novel sorption system containing natural zeolite. The apparatus consists of packed, fixed-bed, dual-columns with custom automated controls and sampling chambers, connected in series and stock fed by a metering pump at a controlled adjustable distribution. The purpose of the system is to remove heavy metallic ions predominately found in acid mine drainage, including lead (Pb2+), copper (Cu2+), iron (Fe3+), nickel (Ni2+) and zinc (Zn2+), combined in equal equivalence to form an acidified total 10 meq/L aqueous solution. Reported trends on the zeolite’s preference to these heavy metallic ions is established in the system breakthrough curve, as Pb2+ >> Fe3+ > Cu2+ > Zn2+ >> Ni2+. Within a 3-h contact period, Pb2+ is completely removed from both columns. Insufficient Ni2+ removal is achieved by either column with the promptest breakthrough attained, as zeolite demonstrates the least affinity towards it; however, a 48.97% removal is observed in the cumulative collection at the completion of the analysis period. The empty bed contact times for the first and second columns are 20 and 30 min, respectively; indicating a higher bed capacity at breakthrough and a lower usage rate of the zeolite mineral in the second column. This sorption system experimentally demonstrates the potential for industrial wastewater treatment technology development. Full article
(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)
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Open AccessArticle A Method for Ferulic Acid Production from Rice Bran Oil Soapstock Using a Homogenous System
Appl. Sci. 2017, 7(8), 796; doi:10.3390/app7080796
Received: 30 June 2017 / Revised: 31 July 2017 / Accepted: 31 July 2017 / Published: 5 August 2017
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Abstract
Ferulic acid (FA) is widely used as an antioxidant, e.g., as a Ultraviolet (UV) protectant in cosmetics and in various medical applications. It has been produced by the hydrolysis of γ-oryzanol found in rice bran oil soapstock. In this study, the base-catalyzed, homogenous
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Ferulic acid (FA) is widely used as an antioxidant, e.g., as a Ultraviolet (UV) protectant in cosmetics and in various medical applications. It has been produced by the hydrolysis of γ-oryzanol found in rice bran oil soapstock. In this study, the base-catalyzed, homogenous hydrolysis of γ-oryzanol was conducted using various ratios of potassium hydroxide (KOH) to γ-oryzanol, initial concentrations of γ-oryzanol in the reaction mixture, and ratios of ethanol (EtOH) (as cosolvent)/ethyl acetate (EtOAc) (γ-oryzanol solution). Acceleration of the reaction using a planar type of ultrasound sonicator (78 and 130 kHz) at different reaction temperatures was explored. By using a heating method, the 80% yield of FA was attained at 75 °C in 4 h under homogeneous conditions (initial concentration of γ-oryzanol 12 mg/mL, the KOH/γ-oryzanol ratio (wt/wt) 10/1, and EtOH/EtOAc ratio (v/v) 5/1). With the assistance of 78 and 130 kHz irradiation, the yields reached 90%. The heating method was applied for the γ-oryzanol-containing extract prepared from rice bran oil soapstock. From soapstock, the 74.3% yield of FA was obtained, but 20% of the trans-FA in the reaction mixture was transformed into cis-form within one month. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Dynamic Performance Analysis for an Absorption Chiller under Different Working Conditions
Appl. Sci. 2017, 7(8), 797; doi:10.3390/app7080797
Received: 4 July 2017 / Revised: 31 July 2017 / Accepted: 31 July 2017 / Published: 5 August 2017
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Abstract
Due to the merits of energy saving and environmental protection, the absorption chiller (AC) has attracted a lot of attention, and previous studies only concentrated on the dynamic response of the AC under a single working condition. However, the working conditions are usually
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Due to the merits of energy saving and environmental protection, the absorption chiller (AC) has attracted a lot of attention, and previous studies only concentrated on the dynamic response of the AC under a single working condition. However, the working conditions are usually variable, and the dynamic performance under different working conditions is beneficial for the adjustment of AC and the control of the whole system, of which the stabilization can be affected by the AC transient process. Therefore, the steady and dynamic models of a single-effect H2O-LiBr absorption chiller are built up, the thermal inertia and fluid storage are also taken into consideration. And the dynamic performance analyses of the AC are completed under different external parameters. Furthermore, a whole system using AC in a process plant is analyzed. As a conclusion, the time required to reach a new steady-state (relaxation time) increases when the step change of the generator inlet temperature becomes large, the cooling water inlet temperature rises, or the evaporator inlet temperature decreases. In addition, the control strategy considering the AC dynamic performance is favorable to the operation of the whole system. Full article
(This article belongs to the Special Issue Sciences in Heat Pump and Refrigeration)
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Open AccessFeature PaperArticle Real-Time Recognition of Calling Pattern and Behaviour of Mobile Phone Users through Anomaly Detection and Dynamically-Evolving Clustering
Appl. Sci. 2017, 7(8), 798; doi:10.3390/app7080798
Received: 31 July 2017 / Revised: 2 August 2017 / Accepted: 2 August 2017 / Published: 5 August 2017
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Abstract
In the competitive telecommunications market, the information that the mobile telecom operators can obtain by regularly analysing their massive stored call logs, is of great interest. Although the data that can be extracted nowadays from mobile phones have been enriched with much information,
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In the competitive telecommunications market, the information that the mobile telecom operators can obtain by regularly analysing their massive stored call logs, is of great interest. Although the data that can be extracted nowadays from mobile phones have been enriched with much information, the data solely from the call logs can give us vital information about the customers. This information is usually related with the calling behaviour of their customers and it can be used to manage them. However, the analysis of these data is normally very complex because of the vast data stream to analyse. Thus, efficient data mining techniques need to be used for this purpose. In this paper, a novel approach to analyse call detail records (CDR) is proposed, with the main goal to extract and cluster different calling patterns or behaviours, and to detect outliers. The main novelty of this approach is that it works in real-time using an evolving and recursive framework. Full article
(This article belongs to the Special Issue Human Activity Recognition)
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Open AccessArticle An Experimental Study on Hysteresis Characteristics of a Pneumatic Braking System for a Multi-Axle Heavy Vehicle in Emergency Braking Situations
Appl. Sci. 2017, 7(8), 799; doi:10.3390/app7080799
Received: 27 June 2017 / Revised: 24 July 2017 / Accepted: 2 August 2017 / Published: 6 August 2017
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Abstract
This study aims to investigate the hysteresis characteristics of a pneumatic braking system for multi-axle heavy vehicles (MHVs). Hysteresis affects emergency braking performance severely. The fact that MHVs have a large size and complex structure leads to more nonlinear coupling property of the
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This study aims to investigate the hysteresis characteristics of a pneumatic braking system for multi-axle heavy vehicles (MHVs). Hysteresis affects emergency braking performance severely. The fact that MHVs have a large size and complex structure leads to more nonlinear coupling property of the pneumatic braking system compared to normal two-axle vehicles. Thus, theoretical analysis and simulation are not enough when studying hysteresis. In this article, the hysteresis of a pneumatic brake system for an eight-axle vehicle in an emergency braking situation is studied based on a novel test bench. A servo drive device is applied to simulate the driver’s braking intensions normally expressed by opening or moving speed of the brake pedal. With a reasonable arrangement of sensors and the NI LabVIEW platform, both the delay time of eight loops and the response time of each subassembly in a single loop are detected in real time. The outcomes of the experiment show that the delay time of each loop gets longer with the increase of pedal opening, and a quadratic relationship exists between them. Based on this, the pressure transient in the system is fitted to a first-order plus time delay model. Besides, the response time of treadle valve and controlling pipeline accounts for more than 80% of the loop’s total delay time, indicating that these two subassemblies are the main contributors to the hysteresis effect. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessArticle Research on Performance of a Dense Graded Ultra-Thin Wearing Course Mixture
Appl. Sci. 2017, 7(8), 800; doi:10.3390/app7080800
Received: 7 July 2017 / Revised: 31 July 2017 / Accepted: 2 August 2017 / Published: 7 August 2017
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Abstract
This paper focused on the design and performance characterization of a modified ultra-thin wearing course mixture (M-UWM). A dense graded ultra-thin wearing course mixture with nominal maximum aggregate size of 10 mm was designed and named as UWM10. A multi-chain polyolefin modifier was
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This paper focused on the design and performance characterization of a modified ultra-thin wearing course mixture (M-UWM). A dense graded ultra-thin wearing course mixture with nominal maximum aggregate size of 10 mm was designed and named as UWM10. A multi-chain polyolefin modifier was used to modify the performance of UWM10 to get M-UWM10. Based on different laboratory performance tests including wheel tracking tests, low-temperature bending beam tests, immersion Marshall tests and freeze-thaw splitting tests, the high temperature rutting resistance, low-temperature cracking resistance and moisture resistance of the designed M-UWM10 were evaluated. The texture depth tests and wheel tracking tests were combined to characterize the degradation behaviour of the surface texture depth of M-UWM10. Based on test roads, the bonding conditions between the wearing course layer that consisted of M-UWM10 and its sublayer were evaluated by computed tomography (CT) scanning test and pull out test. Filed texture depth tests were also conducted on the test roads. It is proved that the designed wearing course mixture M-UWM10 shows excellent pavement performance as well as better wearing resistance and interlayer bonding than the traditional wearing course mixture. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Effects of Vibration on the Electrical Performance of Lithium-Ion Cells Based on Mathematical Statistics
Appl. Sci. 2017, 7(8), 802; doi:10.3390/app7080802
Received: 20 June 2017 / Revised: 23 July 2017 / Accepted: 5 August 2017 / Published: 7 August 2017
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Abstract
Lithium-ion batteries are increasingly used in mobile applications where mechanical vibrations and shocks are a constant companion. There is evidence both in the academic and industrial communities to suggest that the electrical performance and mechanical properties of the lithium-ion cells of an electric
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Lithium-ion batteries are increasingly used in mobile applications where mechanical vibrations and shocks are a constant companion. There is evidence both in the academic and industrial communities to suggest that the electrical performance and mechanical properties of the lithium-ion cells of an electric vehicle (EV) are affected by the road-induced vibration. However, only a few studies related to the effects of vibration on the degradation of electrical performance of lithium-ion batteries have been approached. Therefore, this paper aimed to investigate the effects of vibration on the DC resistance, 1C capacity and consistency of NCR18650BE lithium-ion cells. Based on mathematical statistics, the method changes of the DC resistance and the capacity of the cells both before and after the test were analyzed with a large sample size. The results identified that a significant increase in DC resistance was observed as a result of vibration at the 95% confidence level, while typically a reduction in 1C capacity was also noted. In addition, based on a multi-feature quantity, a clustering algorithm was adopted to analyze the effect of vibration on cell consistency; the results show that the cell consistency had deteriorated after the vibration test. Full article
(This article belongs to the Special Issue Solid-State Batteries)
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Open AccessArticle A Compact and Multi-Stack Electromagnetic Bandgap Structure for Gigahertz Noise Suppression in Multilayer Printed Circuit Boards
Appl. Sci. 2017, 7(8), 804; doi:10.3390/app7080804
Received: 28 June 2017 / Revised: 25 July 2017 / Accepted: 31 July 2017 / Published: 7 August 2017
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Abstract
In modern printed electronics, the performances of a circuit and a device are severely deteriorated by the electromagnetic noise in the gigahertz (GHz) frequency range, such as the simultaneous switching noise and ground bounce noise. A compact and multi-stack electromagnetic bandgap (CMS-EBG) structure
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In modern printed electronics, the performances of a circuit and a device are severely deteriorated by the electromagnetic noise in the gigahertz (GHz) frequency range, such as the simultaneous switching noise and ground bounce noise. A compact and multi-stack electromagnetic bandgap (CMS-EBG) structure is proposed to suppress the electromagnetic noise over the GHz frequency range with a short distance between a noise source and a victim on multilayer printed circuit boards (MPCBs). The original configuration of the stepped impedance resonators is presented to efficiently form multiple stacks of EBG cells. The noise suppression characteristics of the CMS-EBG structure are rigorously examined using Floquet-Bloch analysis. In the analysis, dispersion diagrams are extracted from an equivalent circuit model and a full-wave simulation model. It is experimentally verified that the CMS-EBG structure suppresses the resonant modes over the wideband frequency range with a short source-to-victim distance; thus, this structure substantially mitigates GHz electromagnetic noise in compact MPCBs. Full article
(This article belongs to the Special Issue Printed Electronics 2017)
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Open AccessArticle Accelerated Sine-on-Random Vibration Test Method of Ground Vehicle Components over Conventional Single Mode Excitation
Appl. Sci. 2017, 7(8), 805; doi:10.3390/app7080805
Received: 10 July 2017 / Revised: 29 July 2017 / Accepted: 31 July 2017 / Published: 7 August 2017
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Abstract
Automotive manufacturers typically assess the mechanical durability performance of ground vehicle components for vibration excitation using either random or harmonic spectral loading patterns, such as the loading patterns suggested in international standards (e.g., ISO-16750-3). Selection of the correct excitation profile is dependent on
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Automotive manufacturers typically assess the mechanical durability performance of ground vehicle components for vibration excitation using either random or harmonic spectral loading patterns, such as the loading patterns suggested in international standards (e.g., ISO-16750-3). Selection of the correct excitation profile is dependent on the service condition of the component of interest. However, in the instance where the vehicle component is exposed to both harmonic excitations and background noise, the severity of impact of the in-service environment cannot be satisfied via a single random or harmonic test alone. In this case, the optimal test strategy is to evaluate the vehicle component under a sine-on-random excitation. Within this study, a uniaxial excitation test was conducted for a notched simple specimen under three spectral loading cases (harmonic, random, and sine-on-random), and the test severity was determined based on two kinds of fatigue damage: the physical damage from measured strain and the calculated pseudo-damage from acceleration measurements, as indicated in ISO-16750-3. Based on this comparison of accumulated fatigue damage, the efficiency of the proposed sine-on random vibration was proved against conventional single spectral pattern test methods. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Aging Characteristics of Rubber Modified Asphalts in Different Environmental Factors Combinations
Appl. Sci. 2017, 7(8), 806; doi:10.3390/app7080806
Received: 30 June 2017 / Revised: 3 August 2017 / Accepted: 3 August 2017 / Published: 7 August 2017
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Abstract
Two kinds of rubber modified asphalts were investigated and compared with virgin asphalt. In order to get closer to engineering practice, different combinations of four environmental factors were merged into the laboratory aging simulation. Subsequently, conventional property tests, including softening point, viscosity, creep
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Two kinds of rubber modified asphalts were investigated and compared with virgin asphalt. In order to get closer to engineering practice, different combinations of four environmental factors were merged into the laboratory aging simulation. Subsequently, conventional property tests, including softening point, viscosity, creep stiffness, creep rate, and fatigue cracking were conducted on asphalt samples. The performance difference of asphalt before and after aging was selected as an evaluation index for asphalt aging degree. The results indicate that two kinds of rubber modified asphalts show stronger resistant ability to temperature deformation and better resistance to traffic loading than virgin asphalt in all kinds of environmental factors combinations. Tests on chemical analyses were conducted to investigate the asphalt aging characteristics. The apparent morphology of rubber modified asphalts are described in detail under an environment scanning electron microscope (ESEM). The damage condition reflected in images reveals the aging degree caused by multiple environmental factors. Moreover, the thermogravimetric analysis (TG) confirms that three kinds of asphalts can maintain thermal stability in various environments. Additionally, new characteristic functional groups were not detected in the infrared (IR) spectra of rubber modified asphalts, which means they have stable antioxidant properties given that their oxidation degrees change slightly throughout the aging processes. Full article
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Open AccessArticle New Insights into the Short Pitch Corrugation Enigma Based on 3D-FE Coupled Dynamic Vehicle-Track Modeling of Frictional Rolling Contact
Appl. Sci. 2017, 7(8), 807; doi:10.3390/app7080807
Received: 13 June 2017 / Revised: 28 July 2017 / Accepted: 31 July 2017 / Published: 7 August 2017
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Abstract
A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine
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A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine the system responses in terms of vibration modes, contact forces and the resulting wear with smooth rail and corrugated rail with progressively increasing amplitude to infer the conditions for consistent corrugation initiation and growth. Wear is assumed to be the damage mechanism, and short pitch corrugation is modeled using wavelengths from field observations of a Dutch railway. The contribution of this paper is a global perspective of the consistency conditions that govern the evolution of short pitch corrugation. The main insights are as follows: (1) the longitudinal vibration modes are probably dominant for short pitch corrugation initiation; (2) during short pitch corrugation evolution, the interaction and consistency between longitudinal and vertical modes should determine the development of short pitch corrugation, and once a certain severity is reached, vertical modes become dominant; and (3) in the case simulated in this paper, corrugation does not grow probably due to not only the different resulting main frequencies of the vertical and longitudinal contact forces, but also the inconsistency between the frequencies of the vertical and longitudinal vibration modes and the resulting wear. It is inferred that in the continuous process of initiation and growth of the corrugation, there should be a consistency between them, and this could be done by the control of certain track parameters. Full article
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Open AccessArticle Experimental Study on Effectiveness of a Prototype Seismic Isolation System Made of Polymeric Bearings
Appl. Sci. 2017, 7(8), 808; doi:10.3390/app7080808
Received: 5 June 2017 / Revised: 31 July 2017 / Accepted: 3 August 2017 / Published: 8 August 2017
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Abstract
Seismic isolation is identified as one of the most popular and effective methods of protecting structures under strong dynamic excitations. Base isolators, such as Lead Rubber Bearings, High Damping Rubber Bearings, and Friction Pendulum Bearings, are widely used in practice in many earthquake-prone
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Seismic isolation is identified as one of the most popular and effective methods of protecting structures under strong dynamic excitations. Base isolators, such as Lead Rubber Bearings, High Damping Rubber Bearings, and Friction Pendulum Bearings, are widely used in practice in many earthquake-prone regions of the world to mitigate structural vibrations, and therefore minimize loss of life and property damage during seismic events. The present paper reports the results of the comprehensive experimental investigation designed to verify the effectiveness of a prototype base isolation system made of Polymeric Bearings in reducing structural vibrations. In order to construct seismic bearings considered in this study, a specially prepared polymeric material with improved damping properties was used. The dynamic behaviour of a single-storey and two-storey experimental model, both fixed-base and base-isolated, under a number of different ground motions, was extensively studied. The reduction in lateral response was measured by comparing the peak accelerations recorded at the top of the analyzed model structures with and without a base isolation system. The results of this research clearly demonstrate that the application of the prototype Polymeric Bearings leads to significant improvement in seismic response by reducing the lateral acceleration. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle ANCR—An Adaptive Network Coding Routing Scheme for WSNs with Different-Success-Rate Links
Appl. Sci. 2017, 7(8), 809; doi:10.3390/app7080809
Received: 1 July 2017 / Revised: 3 August 2017 / Accepted: 4 August 2017 / Published: 8 August 2017
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Abstract
As the underlying infrastructure of the Internet of Things (IoT), wireless sensor networks (WSNs) have been widely used in many applications. Network coding is a technique in WSNs to combine multiple channels of data in one transmission, wherever possible, to save node’s energy
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As the underlying infrastructure of the Internet of Things (IoT), wireless sensor networks (WSNs) have been widely used in many applications. Network coding is a technique in WSNs to combine multiple channels of data in one transmission, wherever possible, to save node’s energy as well as increase the network throughput. So far most works on network coding are based on two assumptions to determine coding opportunities: (1) All the links in the network have the same transmission success rate; (2) Each link is bidirectional, and has the same transmission success rate on both ways. However, these assumptions may not be true in many actual WSNs—the wireless links among nodes are often subject to all kinds of disturbance, obstruction, etc., and may transmit with different success rates. This paper proposes a new routing strategy, named Adaptive Network Coding Routing (ANCR). ANCR firstly establishes a routing path with the traditional network coding routing (NCR), and then applies the neighborhood search algorithm to adaptively determine nodes’ coding opportunities based on the links’ transmission success rates, with the target of reducing the total number of transmission. The simulation results show that, in WSNs with different-success-rate links, ANCR can reduce the network delay by about 50%, and increase the network throughput by about 67%, compared with the traditional NCR. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Chlorine Tolerance and Inactivation of Escherichia coli recovered from Wastewater Treatment Plants in the Eastern Cape, South Africa
Appl. Sci. 2017, 7(8), 810; doi:10.3390/app7080810
Received: 13 June 2017 / Revised: 30 July 2017 / Accepted: 1 August 2017 / Published: 8 August 2017
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Abstract
This study investigated the survival of Escherichia coli (E. coli) recovered from secondary effluents of two wastewater treatment plants in the Eastern Cape Province, South Africa, in the presence of different chlorine concentrations. The bacterial survival, chlorine lethal dose and inactivation
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This study investigated the survival of Escherichia coli (E. coli) recovered from secondary effluents of two wastewater treatment plants in the Eastern Cape Province, South Africa, in the presence of different chlorine concentrations. The bacterial survival, chlorine lethal dose and inactivation kinetics at lethal doses were examined. The bacterial isolates were identified by 16S rRNA gene sequencing. Comparison of the nucleotide sequences of 16S rRNA gene of bacteria with known taxa in the GenBank revealed the bacterial isolates to belong to Escherichia coli. At the recommended free chlorine of 0.5 mg/L, reduction of E. coli isolates (n = 20) initial bacterial concentration of 8.35–8.75 log was within a range of 3.88–6.0 log at chlorine residuals of 0.14–0.44 mg/L after 30 min. At higher doses, a marked reduction (p < 0.05) in the viability of E. coli isolates was achieved with a greater than 7.3 log inactivation of the bacterial population. Inactivation kinetics revealed a high rate of bacterial kill over time (R2 > 0.9) at chlorine dose of 1.5 mg/L. This study indicates poor removal of bacteria at free chlorine at 0.5 mg/L and a greater efficacy of 1.5 mg/L in checking E. coli tolerance. Full article
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Open AccessArticle Experimental Evaluation of Thermal Performance and Durability of Thermally-Enhanced Concretes
Appl. Sci. 2017, 7(8), 811; doi:10.3390/app7080811
Received: 10 July 2017 / Revised: 1 August 2017 / Accepted: 2 August 2017 / Published: 8 August 2017
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Abstract
The thermal performance and durability of the thermally-enhanced concrete with various insulating materials were evaluated through a series of tests. Three types of insulating materials—diatomite powder, hollow micro-spheres, and a micro-foam agent—were used for both normalweight aggregate concrete (NWAC) and lightweight aggregate concrete
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The thermal performance and durability of the thermally-enhanced concrete with various insulating materials were evaluated through a series of tests. Three types of insulating materials—diatomite powder, hollow micro-spheres, and a micro-foam agent—were used for both normalweight aggregate concrete (NWAC) and lightweight aggregate concrete (LWAC). The thermal conductivity was measured by two different test methods: quick thermal conductivity meter (QTM) and guarded hot wire (GHW) methods. Then, the results were compared with each other. All insulating materials used in this study proved their ability to reduce the thermal conductivity. Additionally, it can be found that the trend of a decrease in air-dry density is similar to that of thermal conductivity of thermally-enhanced concrete. Additional thermal transmission tests with seven large-scale specimens were conducted by using the calibrated hot box (CHB). However, from this tests, it was seen that thermal transmission reduction for tested specimens were not large compared to the thermal conductivity reduction measured by QTM and GHW, due to multiple heat transfer. To examine the durability of thermally-enhanced concretes, accelerated carbonation and freeze-thaw cycle tests were conducted. From the results, it can be found that the thermally-enhanced concrete shows good freeze-thaw resistance. However, the carbonation rates of the concretes increased rapidly and additional methods to improve the carbonation resistance should be considered. Full article
(This article belongs to the Section Energy)
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Open AccessFeature PaperArticle Time Behaviour of Helium Atmospheric Pressure Plasma Jet Electrical and Optical Parameters
Appl. Sci. 2017, 7(8), 812; doi:10.3390/app7080812
Received: 7 July 2017 / Revised: 1 August 2017 / Accepted: 4 August 2017 / Published: 9 August 2017
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Abstract
Low temperature plasma jets gained increased interest in the last years as a potential device in many life science applications, including here human or veterinary medicine. Standardisation of plasma sources and biological protocols are necessary for quality assurance reasons, due to the fact
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Low temperature plasma jets gained increased interest in the last years as a potential device in many life science applications, including here human or veterinary medicine. Standardisation of plasma sources and biological protocols are necessary for quality assurance reasons, due to the fact that this type of atmospheric pressure plasma source is available in multiple configurations and their operational parameters span also on a broad range of items, such as all characteristics of high voltage pulses used for gas breakdown, geometrical characteristics, gas feed composition and conductive or biological target characteristics. In this paper we present results related to electrical, optical and molecular beam mass spectrometry diagnosis of a helium plasma jet, emphasising the influence of various operational parameters of the high voltage pulses on plasma jet properties. Discussion on physical parameters that influence the biological response is included, together with important results on plasma sources statistical behaviour until reaching a quasi-stationary working regime. The warm-up period of the plasma jet, specific to many other plasma sources, must be precisely known and specified whenever the plasma jets are used as a tool for life science applications. Full article
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Open AccessArticle Optimal Control of Wastewater Treatment Plants Using Economic-Oriented Model Predictive Dynamic Strategies
Appl. Sci. 2017, 7(8), 813; doi:10.3390/app7080813
Received: 1 July 2017 / Revised: 25 July 2017 / Accepted: 1 August 2017 / Published: 9 August 2017
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Abstract
This paper addresses the implementation of economic-oriented model predictive controllers for the dynamic real-time optimization of the operation of wastewater treatment plants (WWTP). Both the economic-optimizing controller (pure-EMPC) and the economic-oriented tracking controller (Hybrid-EMPC, or HEMPC) formulations are validated in the benchmark simulation
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This paper addresses the implementation of economic-oriented model predictive controllers for the dynamic real-time optimization of the operation of wastewater treatment plants (WWTP). Both the economic-optimizing controller (pure-EMPC) and the economic-oriented tracking controller (Hybrid-EMPC, or HEMPC) formulations are validated in the benchmark simulation model (BSM1) platform that represents the behavior of a characteristic activated sludge process. The objective of the controllers is to ensure the appropriate operation of the plant, while minimizing the energy consumption and the fines for violations of the limits of the ammonia concentration in the effluent along the full operating period. A non-linear reduced model of the activated sludge process is used for predictions to obtain a reasonable computing effort, and techniques to deal with model-plant mismatch are incorporated in the controller algorithm. Different designs and structures are compared in terms of process performance and energy costs, which show that the implementation of the proposed control technique can produce significant economic and environmental benefits, depending on the desired performance criteria. Full article
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Open AccessArticle Modeling Non-Equilibrium Dynamics and Saturable Absorption Induced by Free Electron Laser Radiation
Appl. Sci. 2017, 7(8), 814; doi:10.3390/app7080814
Received: 31 May 2017 / Revised: 22 July 2017 / Accepted: 27 July 2017 / Published: 9 August 2017
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Abstract
Currently available X-ray and extreme ultraviolet free electron laser (FEL) sources provide intense ultrashort photon pulses. Those sources open new exciting perspectives for experimental studies of ultrafast non-equilibrium processes at the nanoscale in condensed matter. Theoretical approaches and computer simulations are being developed
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Currently available X-ray and extreme ultraviolet free electron laser (FEL) sources provide intense ultrashort photon pulses. Those sources open new exciting perspectives for experimental studies of ultrafast non-equilibrium processes at the nanoscale in condensed matter. Theoretical approaches and computer simulations are being developed to understand the complicated dynamical processes associated with the interaction of FEL pulses with matter. In this work, we present the results of the application of a simplified three-channel model to the non-equilibrium dynamics of ultrathin aluminum films excited by FEL radiation at 33.3, 37 and 92 eV photon energy. The model includes semi-classical rate equations coupled with the equation of propagation of the photon wave packets. X-ray transmission measurements are found to be in agreement with present simulations, which are also able to shed light on temporal dynamics (in the fs range) in nano-sized Al films strongly interacting with the photon pulse. We also expanded our non-linear model, explicitly including the two-photon absorption cross-section and the effect of including electron heating for reproducing transmission measurements. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle Laser Irradiation Responses of a Single-Crystal Diamond Produced by Different Crystal Growth Methods
Appl. Sci. 2017, 7(8), 815; doi:10.3390/app7080815
Received: 18 June 2017 / Revised: 3 August 2017 / Accepted: 7 August 2017 / Published: 9 August 2017
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Abstract
Responses of two types of single-crystal diamonds, prepared by chemical vapour deposition (CVD) and high pressure high temperature synthesis (HPHT) methods, respectively, to a nanosecond pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser were investigated and compared. It was found that due to the
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Responses of two types of single-crystal diamonds, prepared by chemical vapour deposition (CVD) and high pressure high temperature synthesis (HPHT) methods, respectively, to a nanosecond pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser were investigated and compared. It was found that due to the difference in the transmission rate and refractive index, the laser-induced surface/subsurface features of the two types of samples were distinctly different. For the CVD sample, destructive interference takes place on the upper surface, leading to direct ablation of smooth grooves with deposition of graphite. For the HPHT sample, however, laser-induced grooves were formed on the reverse side of the irradiation surface (namely, the lower surface) at certain laser fluences due to the constructive interference phenomenon of the laser and the high refractive index of the material. The reverse-side irradiation resulted in the formation of deep and sharp grooves with rough bottoms and insignificant deposition of graphite on the area surrounding the groove. The machining thresholds for the upper and lower surfaces of both types of diamonds were experimentally obtained and theoretically verified. The findings of this study provide important process criteria for laser machining of different kinds of diamonds. The reverse-side irradiation method enables efficient machining of deep grooves in diamonds using a lower power laser. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Analysis of the Energy Efficiency of a Pneumatic Booster Regulator with Energy Recovery
Appl. Sci. 2017, 7(8), 816; doi:10.3390/app7080816
Received: 27 June 2017 / Revised: 27 July 2017 / Accepted: 7 August 2017 / Published: 9 August 2017
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Abstract
Pneumatic booster regulators (PBR) are in great demand in modern pneumatic systems for their energy-saving abilities. A new booster regulator with energy recovery (VBA-R) was proposed, and its energy efficiency was investigated by introducing the concept of air power. On the basis of
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Pneumatic booster regulators (PBR) are in great demand in modern pneumatic systems for their energy-saving abilities. A new booster regulator with energy recovery (VBA-R) was proposed, and its energy efficiency was investigated by introducing the concept of air power. On the basis of quality-alterable gas thermodynamics, an energy efficiency assessment and pressure response model for VBA-R was proposed. First, a model was solved using MATLAB/Simulink software, and an alternative experiment was designed to verify the mathematical model and performance improvement. The results showed that the simulation was consistent with the experiment. We also can conclude that, first of all, the energy efficiency decreases with the increasing of supply pressure and flow-rate consumption; a VBA-R has the highest efficiency when its diameter ratio is closest to 1.3. Finally, a recovery chamber helped to improve the performance of the VBA-R, which included a boost ratio improvement of 15–25% and an efficiency improvement of 5–10% compared with a conventional VBA booster regulator. This research lays the foundation for optimism regarding the proposed booster regulator. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessArticle An Efficient Network Coding-Based Fault-Tolerant Mechanism in WBAN for Smart Healthcare Monitoring Systems
Appl. Sci. 2017, 7(8), 817; doi:10.3390/app7080817
Received: 12 July 2017 / Revised: 5 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
As a key technology in smart healthcare monitoring systems, wireless body area networks (WBANs) can pre-embed sensors and sinks on body surface or inside bodies for collecting different vital signs parameters, such as human Electrocardiograph (ECG), Electroencephalograph (EEG), Electromyogram (EMG), body temperature, blood
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As a key technology in smart healthcare monitoring systems, wireless body area networks (WBANs) can pre-embed sensors and sinks on body surface or inside bodies for collecting different vital signs parameters, such as human Electrocardiograph (ECG), Electroencephalograph (EEG), Electromyogram (EMG), body temperature, blood pressure, blood sugar, blood oxygen, etc. Using real-time online healthcare, patients can be tracked and monitored in normal or emergency conditions at their homes, hospital rooms, and in Intensive Care Units (ICUs). In particular, the reliability and effectiveness of the packets transmission will be directly related to the timely rescue of critically ill patients with life-threatening injuries. However, traditional fault-tolerant schemes either have the deficiency of underutilised resources or react too slowly to failures. In future healthcare systems, the medical Internet of Things (IoT) for real-time monitoring can integrate sensor networks, cloud computing, and big data techniques to address these problems. It can collect and send patient’s vital parameter signal and safety monitoring information to intelligent terminals and enhance transmission reliability and efficiency. Therefore, this paper presents a design in healthcare monitoring systems for a proactive reliable data transmission mechanism with resilience requirements in a many-to-one stream model. This Network Coding-based Fault-tolerant Mechanism (NCFM) first proposes a greedy grouping algorithm to divide the topology into small logical units; it then constructs a spanning tree based on random linear network coding to generate linearly independent coding combinations. Numerical results indicate that this transmission scheme works better than traditional methods in reducing the probability of packet loss, the resource redundant rate, and average delay, and can increase the effective throughput rate. Full article
(This article belongs to the Special Issue Smart Healthcare)
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Open AccessArticle Experimental Study on Mechanical Behavior of Shear Connectors of Square Concrete Filled Steel Tube
Appl. Sci. 2017, 7(8), 818; doi:10.3390/app7080818
Received: 17 July 2017 / Revised: 31 July 2017 / Accepted: 3 August 2017 / Published: 10 August 2017
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Abstract
In order to quantitatively evaluate the shear-bearing capacity of shear connectors of square concrete filled steel tube (CFST), push-out tests on 14 square CFSTs with shear connectors have been carried out. Among the 14 CFSTs, there are 13 specimens with steel plate connectors
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In order to quantitatively evaluate the shear-bearing capacity of shear connectors of square concrete filled steel tube (CFST), push-out tests on 14 square CFSTs with shear connectors have been carried out. Among the 14 CFSTs, there are 13 specimens with steel plate connectors and one specimen with steel bar connectors. The following factors are investigated to figure out their influences on the performance of CFSTs, which are the width to thickness ratio of steel tube, thickness of steel plate, length of steel plate, strength of concrete, welding condition of steel plate, number of steel plate layer and interlayer spacing. The test results show that the ultimate bearing capacity and the elastic stiffness increase with decreasing width to thickness ratio of the steel tube, and increasing thickness and length of the steel plate. With increasing concrete strength, the ultimate bearing capacity also increases. However, the welding condition has no effect on the ultimate bearing capacity. The ultimate bearing capacity of the CFST with double-layer steel plate is greater than that with single-layer steel plate. The ultimate bearing capacity of steel bar type shear connector is 87% greater than that of the steel plate type shear connector, and the steel bar specimen shows good ductility. A formula for calculating the shear-bearing capacity of shear connectors has been developed, and the calculated shear-bearing capacities are in good agreement with the test data. Full article
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Open AccessArticle Size Characterisation Method and Detection Enhancement of Plasmonic Nanoparticles in a Pump–Probe System
Appl. Sci. 2017, 7(8), 819; doi:10.3390/app7080819
Received: 5 July 2017 / Revised: 3 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
The optical resonance of metal nanoparticles can be used to enhance the generation and detection of their main vibrational mode. In this work, we show that this method allows the accurate characterisation of the particle’s size because the vibrational frequency of plasmonic nanoparticles
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The optical resonance of metal nanoparticles can be used to enhance the generation and detection of their main vibrational mode. In this work, we show that this method allows the accurate characterisation of the particle’s size because the vibrational frequency of plasmonic nanoparticles only depends on their mechanical properties. Moreover, by a careful selection of the particle size and/or probe laser wavelength, the detected signal can be increased by a large factor (∼9 for the particles used in this work) under the same illumination conditions. Finally, we show experimentally that particles of different sizes inside the point spread function can be observed due to the differences in their vibrational states, which could provide a feasible route to super-resolution. Full article
(This article belongs to the Special Issue Laser Interaction with Plasmonic Nanostructures)
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Open AccessArticle High Conductivity and Adhesion of Cu-Cr-Zr Alloy for TFT Gate Electrode
Appl. Sci. 2017, 7(8), 820; doi:10.3390/app7080820
Received: 10 June 2017 / Revised: 22 July 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
The characteristics of Cu alloy (0.3 wt. % Cr, 0.2 wt. % Zr) thin film deposited by direct current (DC) magnetron sputtering deposition were investigated. The conductivity and adhesion of the Cu-0.3%Cr-0.2%Zr films were optimized by increasing the sputter power to 150 W
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The characteristics of Cu alloy (0.3 wt. % Cr, 0.2 wt. % Zr) thin film deposited by direct current (DC) magnetron sputtering deposition were investigated. The conductivity and adhesion of the Cu-0.3%Cr-0.2%Zr films were optimized by increasing the sputter power to 150 W and reducing the sputter pressure to 2 mTorr. With an annealing process (at 300 °C for 1 h in argon ambient atmosphere), the resistivity of the alloy film decreased from 4.80 to 2.96 μΩ·cm, and the adhesion classification increased from 2B to 4B on glass substrate. X-ray photoelectron spectroscopy (XPS) analysis showed that Cr aggregated toward the surface of the film and formed a self-protection layer in the annealing process. Transmission electron microscopy (TEM) indicated the aggregation and migration of Cr in the annealing process. A further X-ray diffraction (XRD) analysis showed that Cu2O appeared when the annealing temperature reached above 350 °C, which accounts for the increase of the resistivity. Based on Al2O3 and SiO2 substrate surfaces, the Cu-0.3%Cr-0.2%Zr film also showed high conductivity and adhesion, which has a potential in the application of Cu gate electrodes for thin film transistor (TFT). Full article
(This article belongs to the Special Issue Thin-Film Transistors)
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Open AccessArticle Enhancing Interpretation of Ambiguous Voice Instructions based on the Environment and the User’s Intention for Improved Human-Friendly Robot Navigation
Appl. Sci. 2017, 7(8), 821; doi:10.3390/app7080821
Received: 20 June 2017 / Revised: 24 July 2017 / Accepted: 2 August 2017 / Published: 10 August 2017
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Abstract
Human-friendly interactive features are preferred for domestic service robots. Humans prefer to use verbal communication in order to convey instructions to peers. Those voice instructions often include uncertain terms such as “little” and “far”. Therefore, the ability to quantify such information is mandatory
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Human-friendly interactive features are preferred for domestic service robots. Humans prefer to use verbal communication in order to convey instructions to peers. Those voice instructions often include uncertain terms such as “little” and “far”. Therefore, the ability to quantify such information is mandatory for human-friendly service robots. The meaning of such voice instructions depends on the environment and the intention of the user. Therefore, this paper proposes a method in order to interpret the ambiguities in user instructions based on the environment and the intention of the user. The actual intention of the user is identified by analyzing the pointing gestures accompanied with the voice instructions since pointing gestures can be used in order to express the intention of the user. A module called the motion intention switcher (MIS) has been introduced in order to switch the intention of the robot based on the arrangement of the environment and the point referred by the gesture. Experiments have been carried out in an artificially-created domestic environment. According to the experimental results, the behavior of the MIS is effective in identifying the actual intention of the user and switching the intention of the robot. Moreover, the proposed concept is capable of enhancing the uncertain information evaluation ability of robots. Full article
(This article belongs to the Special Issue Social Robotics)
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Open AccessArticle Picosecond Photoacoustic Metrology of SiO2 and LiNbO3 Layer Systems Used for High Frequency Surface-Acoustic-Wave Filters
Appl. Sci. 2017, 7(8), 822; doi:10.3390/app7080822
Received: 7 July 2017 / Revised: 1 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
Many applications of thin films necessitate detailed information about their thicknesses and sound velocities. Here, we study SiO2/LiNbO3 layer systems by picosecond photoacoustic metrology and measure the sound velocities of the respective layers and the film thickness of SiO2
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Many applications of thin films necessitate detailed information about their thicknesses and sound velocities. Here, we study SiO2/LiNbO3 layer systems by picosecond photoacoustic metrology and measure the sound velocities of the respective layers and the film thickness of SiO2, which pose crucial information for the fabrication of surface-acoustic-wave filters for communication technology. Additionally, we utilize the birefringence and the accompanying change in the detection sensitivity of coherent acoustic phonons in the LiNbO3 layer to infer information about the LiNbO3 orientation and the layer interface. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Pollutant Recognition Based on Supervised Machine Learning for Indoor Air Quality Monitoring Systems
Appl. Sci. 2017, 7(8), 823; doi:10.3390/app7080823
Received: 3 July 2017 / Revised: 29 July 2017 / Accepted: 8 August 2017 / Published: 11 August 2017
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Abstract
Indoor air may be polluted by various types of pollutants which may come from cleaning products, construction activities, perfumes, cigarette smoke, water-damaged building materials and outdoor pollutants. Although these gases are usually safe for humans, they could be hazardous if their amount exceeded
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Indoor air may be polluted by various types of pollutants which may come from cleaning products, construction activities, perfumes, cigarette smoke, water-damaged building materials and outdoor pollutants. Although these gases are usually safe for humans, they could be hazardous if their amount exceeded certain limits of exposure for human health. A sophisticated indoor air quality (IAQ) monitoring system which could classify the specific type of pollutants is very helpful. This study proposes an enhanced indoor air quality monitoring system (IAQMS) which could recognize the pollutants by utilizing supervised machine learning algorithms: multilayer perceptron (MLP), K-nearest neighbour (KNN) and linear discrimination analysis (LDA). Five sources of indoor air pollutants have been tested: ambient air, combustion activity, presence of chemicals, presence of fragrances and presence of food and beverages. The results showed that the three algorithms successfully classify the five sources of indoor air pollution (IAP) with a classification rate of up to 100 percent. An MLP classifier with a model structure of 9-3-5 has been chosen to be embedded into the IAQMS. The system has also been tested with all sources of IAP presented together. The result shows that the system is able to classify when single and two mixed sources are presented together. However, when more than two sources of IAP are presented at the same period, the system will classify the sources as ‘unknown’, because the system cannot recognize the input of the new pattern. Full article
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Open AccessArticle Effect of Prestress Levels and Jacking Methods on Friction Losses in Curved Prestressed Tendons
Appl. Sci. 2017, 7(8), 824; doi:10.3390/app7080824
Received: 21 June 2017 / Revised: 28 July 2017 / Accepted: 8 August 2017 / Published: 11 August 2017
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Abstract
The effects of prestressing methods and prestress levels on the friction losses of prestressed tendons were evaluated in this study. Two full-scale prestressed concrete girders were fabricated and used for the friction loss experiment. The prestress level was varied from 13% to 45%
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The effects of prestressing methods and prestress levels on the friction losses of prestressed tendons were evaluated in this study. Two full-scale prestressed concrete girders were fabricated and used for the friction loss experiment. The prestress level was varied from 13% to 45% of the ultimate tensile strength of the prestressing tendon, and prestressing was performed by jacking one or both ends. The test results indicated that the actual friction loss measured at low prestress levels was up to 4.3 times higher than the theoretical friction loss. As the prestress level increased, the difference between the measured and theoretical friction losses gradually decreased, and the two eventually converged. On average, the ratio of the prestress force at the jacking end to the prestress force measured at midspan was 85.4% with jacking at both ends, and 81.1% with jacking at one end. Full article
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Open AccessArticle Energy Prediction of Access Points in Wi-Fi Networks According to Users’ Behaviour
Appl. Sci. 2017, 7(8), 825; doi:10.3390/app7080825
Received: 22 June 2017 / Revised: 30 July 2017 / Accepted: 9 August 2017 / Published: 11 August 2017
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Abstract
Some maintenance tasks in Wi-Fi networks may involve removing an access point due to several reasons. As a result, the new infrastructure registers a different number of roamings in the access points according to the users’ behaviour, with a certain energy impact added
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Some maintenance tasks in Wi-Fi networks may involve removing an access point due to several reasons. As a result, the new infrastructure registers a different number of roamings in the access points according to the users’ behaviour, with a certain energy impact added to the consumption caused by the own operations of the devices. This energy effect should be understood in order to tackle the measures aimed at planning the infrastructure deployment. In this work, we propose a methodology to predict the energy consumption in the access points of a Wi-Fi network when we remove a particular device, based on a twofold support. We predict the number of roamings following a method previously validated; on the other hand, we assess the relationship between roamings and energy in the full infrastructure, using the data collected from a high number of network users during a given time in order to reflect the users’ behaviour with the maximum accuracy. From this knowledge, we can infer the energy prediction for a different environment where the roamings are predicted using techniques based on recommender systems and machine learning. Full article
(This article belongs to the Special Issue Green Wireless Networks)
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Open AccessArticle Optimized Deep Neural Networks for Real-Time Object Classification on Embedded GPUs
Appl. Sci. 2017, 7(8), 826; doi:10.3390/app7080826
Received: 19 July 2017 / Revised: 7 August 2017 / Accepted: 10 August 2017 / Published: 11 August 2017
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Abstract
Convolution is the most computationally intensive task of the Convolutional Neural Network (CNN). It requires a lot of memory storage and computational power. There are different approaches to compute the solution of convolution and reduce its computational complexity. In this paper, a matrix
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Convolution is the most computationally intensive task of the Convolutional Neural Network (CNN). It requires a lot of memory storage and computational power. There are different approaches to compute the solution of convolution and reduce its computational complexity. In this paper, a matrix multiplication-based convolution (ConvMM) approach is fully parallelized using concurrent resources of GPU (Graphics Processing Unit) and optimized, considerably improving the performance of the image classifiers and making them applicable to real-time embedded applications. The flow of this CUDA (Compute Unified Device Architecture)-based scheme is optimized using unified memory and hardware-dependent acceleration of matrix multiplication. Proposed flow is evaluated on two different embedded platforms: first on an Nvidia Jetson TX1 embedded board and then on a Tegra K1 GPU of an Nvidia Shield K1 Tablet. The performance of this optimized and accelerated convolutional layer is compared with its sequential and heterogeneous versions. Results show that the proposed scheme significantly improves the overall results including energy efficiency, storage requirement and inference performance. In particular, the proposed scheme on embedded GPUs is hundreds of times faster than the sequential version and delivers tens of times higher performance than the heterogeneous approach. Full article
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Open AccessArticle A Power Processing Circuit for Indoor Wi-Fi Energy Harvesting for Ultra-Low Power Wireless Sensors
Appl. Sci. 2017, 7(8), 827; doi:10.3390/app7080827
Received: 13 July 2017 / Revised: 6 August 2017 / Accepted: 7 August 2017 / Published: 11 August 2017
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Abstract
This article proposes a complete power processing circuit for an indoor 2.45 GHz Wi-Fi energy harvesting system. The proposed power processing circuit works by using power harvested from indoor Wi-Fi transmitters. The overall system of this work is simplified as an equivalent circuit
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This article proposes a complete power processing circuit for an indoor 2.45 GHz Wi-Fi energy harvesting system. The proposed power processing circuit works by using power harvested from indoor Wi-Fi transmitters. The overall system of this work is simplified as an equivalent circuit and analyzed mathematically. A two-port network is analyzed in formulating the relevant equations of the equivalent circuit. The importance of matching the impedance of a harvesting antenna to the rectifier circuit is highlighted by using simulation analysis, and it is shown that the impedance matching for both components has satisfied the conditions for a high sensitivity circuit and radio frequency-to-direct current (RF-to-DC) power conversion. Actual experiments showed that the proposed power processing circuit could operate with an incident power as low as −50 dBm. It has been found that the proposed harvesting system stored 0.11 J in a 200 mF supercapacitor as the storage device in 20 hours of the experimentation periods. Moreover, actual results for the overall energy harvesting system is compared with previous research, and it has been found that the proposed system has advantages over the listed works. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Preparation, Physicochemical Properties, and Long-Term Performance of Photocatalytic Ceramsite Sand in Cementitious Materials
Appl. Sci. 2017, 7(8), 828; doi:10.3390/app7080828
Received: 26 July 2017 / Revised: 7 August 2017 / Accepted: 7 August 2017 / Published: 11 August 2017
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Abstract
Incorporation of TiO2 into cementitious materials is an important technology in the field of photocatalytic pollution mitigation; however, the photocatalytic activity of TiO2 is limited by specific surface area, poor gas diffusion and light transmission performance of cementitious materials. In this
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Incorporation of TiO2 into cementitious materials is an important technology in the field of photocatalytic pollution mitigation; however, the photocatalytic activity of TiO2 is limited by specific surface area, poor gas diffusion and light transmission performance of cementitious materials. In this study, a novel photocatalytic lightweight aggregate—photocatalytic ceramsite sand (PCS) was synthesized by loading TiO2 on activated porous ceramsite sand (CS) with negative pressure method to solve problems in application of photocatalysts in cementitious materials. Photocatalytic cement material (PCM) was prepared by loading PCS on the surface of cementitious materials, which improved the photocatalytic activity and efficiency of TiO2 in cementitious materials. It was found that the pore structure (pore volume, size distribution and interconnectivity) of ceramsite sand (CS) varies with particle size. The photocatalytic removal rate of benzene on PCS increased significantly through adjusting ceramsite sands in appropriate pore structure and TiO2 at best coating ratio. The photocatalytic activity of PCS slightly decreased but still remained active after incorporated into concrete. 2 μL benzene was degraded completely in 200 min by 5 g 4PCS-1.25~2.35 and 300 min by PCM-5, and was still degraded over 80% in 400 min by PCM-5 after exposure to natural environment for 6 months. The results suggested that the photocatalytic activity of TiO2 in cementitious materials was enhanced by the preparation of PCS and PCM, which could provide more gas diffusion, higher specific surface area, more TiO2 active sites, and prevent TiO2 particles from being influenced by the envelope of cement hydration products and the carbonation of cement. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Neutral Copper Gas Resistivity Measurements by Means of an Exploding Wire in Air
Appl. Sci. 2017, 7(8), 829; doi:10.3390/app7080829
Received: 14 July 2017 / Revised: 4 August 2017 / Accepted: 8 August 2017 / Published: 12 August 2017
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Abstract
In this work, we present experimentally obtained limits for the values of the neutral copper gas electrical resistivity as a function of the temperature. When a current of about 103 A or larger flows through a metallic wire in a microsecond
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In this work, we present experimentally obtained limits for the values of the neutral copper gas electrical resistivity as a function of the temperature. When a current of about 10 3 A or larger flows through a metallic wire in a microsecond or shorter time, the wire performs a phase change from solid to plasma, through intermediate states of metallic liquid and vapor. If the wire is surrounded by a non-conductive dense medium that inhibits the circulation of current outside the wire (e.g., air at room temperature and standard pressure, as in our experiments), the electric current stops when part of the metallic wire becomes gas. This process is known as dark pause, and it has a duration that depends on the experiment parameters. By means of a suitable choice of parameters, we achieved a duration of the dark pause of ≈1 μ s, which allowed us to determine the limits of the electrical resistivity of the metallic gas. The range of measured values starts from the resistivity of liquid copper at boiling temperature, and goes up to ≈0.01 ± 20 % Ohm·m at the maximum measured temperature. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Graphene as a Prototypical Model for Two-Dimensional Continuous Mechanics
Appl. Sci. 2017, 7(8), 830; doi:10.3390/app7080830
Received: 26 July 2017 / Revised: 11 August 2017 / Accepted: 11 August 2017 / Published: 13 August 2017
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Abstract
This paper reviews a few problems where continuous-medium theory specialized to two-dimensional media provides a qualitatively correct picture of the mechanical behavior of graphene. A critical analysis of the parameters involved is given. Among other results, a simple mathematical description of a folded
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This paper reviews a few problems where continuous-medium theory specialized to two-dimensional media provides a qualitatively correct picture of the mechanical behavior of graphene. A critical analysis of the parameters involved is given. Among other results, a simple mathematical description of a folded graphene sheet is proposed. It is also shown how the graphene–graphene adhesion interaction is related to the cleavage energy of graphite and its C 33 bulk elastic constant. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Improved Diagnostic Process of Multiple Sclerosis Using Automated Detection and Selection Process in Magnetic Resonance Imaging
Appl. Sci. 2017, 7(8), 831; doi:10.3390/app7080831
Received: 17 July 2017 / Revised: 6 August 2017 / Accepted: 11 August 2017 / Published: 13 August 2017
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Abstract
In this paper, we present a new method of displaying Magnetic Resonance (MR) images taken from Multiple Sclerosis (MS) patients. We show that our method can potentially make the diagnostic process far more focused and concise. The method is implemented as an algorithm-based
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In this paper, we present a new method of displaying Magnetic Resonance (MR) images taken from Multiple Sclerosis (MS) patients. We show that our method can potentially make the diagnostic process far more focused and concise. The method is implemented as an algorithm-based application, which automatically detects MS lesions and reduces the amount of reviewed images by 98% or more. In contrast to existing detection algorithms, our application utilizes five different types of MR images as well as the Digital Imaging and Communications in Medicine (DICOM) standard, supporting a wide range of data sets. After images are selected for file type and relevant brain region, each image is subjected to four separate algorithms, the results of which are combined into a single displayed image for the use of the diagnosing physician. Full article
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Open AccessArticle Modelling the Interruption on HCI Using BDI Agents with the Fuzzy Perceptions Approach: An Interactive Museum Case Study in Mexico
Appl. Sci. 2017, 7(8), 832; doi:10.3390/app7080832
Received: 27 July 2017 / Revised: 9 August 2017 / Accepted: 9 August 2017 / Published: 13 August 2017
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Abstract
Technological advancements have revolutionized the proliferation and availability of information to users, which has created more complex and intensive interactions between users and systems. The learning process of users is essential in the construction of new knowledge when pursuing improvements in user experience.
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Technological advancements have revolutionized the proliferation and availability of information to users, which has created more complex and intensive interactions between users and systems. The learning process of users is essential in the construction of new knowledge when pursuing improvements in user experience. In this paper, the interruption factor is considered in relation to interaction quality due to human–computer interaction (HCI) being seen to affect the learning process. We present the results obtained from 500 users in an interactive museum in Tijuana, Mexico as a case study. We model the HCI of an interactive exhibition using belief–desire–intention (BDI) agents; we adapted the BDI architecture using the Type-2 fuzzy inference system to add perceptual human-like capabilities to agents, in order to describe the interaction and interruption factor on user experience. The resulting model allows us to describe content adaptation through the creation of a personalized interaction environment. We conclude that managing interruptions can enhance the HCI, producing a positive learning process that influences user experience. A better interaction may be achieved if we offer the right kind of content, taking the interruptions experienced into consideration. Full article
(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)
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Open AccessArticle Influence of Curing Conditions on the Strength Properties of Polysulfide Polymer Concrete
Appl. Sci. 2017, 7(8), 833; doi:10.3390/app7080833
Received: 26 July 2017 / Revised: 10 August 2017 / Accepted: 11 August 2017 / Published: 14 August 2017
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Abstract
In this study, the effects of curing temperature and curing time on the mechanical properties of polysulfide polymer concrete were investigated. For this purpose, several laboratory tests were conducted to measure the compressive, flexural, and bond strengths of the concrete. The ranges of
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In this study, the effects of curing temperature and curing time on the mechanical properties of polysulfide polymer concrete were investigated. For this purpose, several laboratory tests were conducted to measure the compressive, flexural, and bond strengths of the concrete. The ranges of curing temperature and curing time considered were −10–60 °C and 3–672 h (28 days), respectively. The test results show that a curing temperature above 20 °C adversely affects the strength of the concrete. Regression equations derived from the test results demonstrate the reliability of the results for the estimation of flexural and bond strengths from a given value of compressive strength. Full article
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