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Appl. Sci., Volume 8, Issue 5 (May 2018)

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Editorial

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Open AccessEditorial Special Issue on Wastewater Treatment and Reuse Technologies
Appl. Sci. 2018, 8(5), 695; https://doi.org/10.3390/app8050695
Received: 25 April 2018 / Revised: 28 April 2018 / Accepted: 28 April 2018 / Published: 1 May 2018
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Abstract
Wastewater treatment allows for the safe disposal of municipal and industrial wastewater to protect public health and the ecosystem[...] Full article
(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)
Open AccessEditorial Recent Developments in Mechanical Engineering
Appl. Sci. 2018, 8(5), 773; https://doi.org/10.3390/app8050773
Received: 9 May 2018 / Revised: 9 May 2018 / Accepted: 9 May 2018 / Published: 12 May 2018
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Abstract
Welcome to the section Mechanical Engineering in Applied Sciences.[...] Full article
(This article belongs to the Section Mechanical Engineering)
Open AccessEditorial Special Feature on Bio-Inspired Robotics
Appl. Sci. 2018, 8(5), 817; https://doi.org/10.3390/app8050817 (registering DOI)
Received: 4 May 2018 / Revised: 14 May 2018 / Accepted: 14 May 2018 / Published: 18 May 2018
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(This article belongs to the Special Issue Bio-Inspired Robotics)

Research

Jump to: Editorial, Review, Other

Open AccessFeature PaperArticle Deep Neural Networks for Document Processing of Music Score Images
Appl. Sci. 2018, 8(5), 654; https://doi.org/10.3390/app8050654
Received: 28 February 2018 / Revised: 13 April 2018 / Accepted: 20 April 2018 / Published: 24 April 2018
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Abstract
There is an increasing interest in the automatic digitization of medieval music documents. Despite efforts in this field, the detection of the different layers of information on these documents still poses difficulties. The use of Deep Neural Networks techniques has reported outstanding results
[...] Read more.
There is an increasing interest in the automatic digitization of medieval music documents. Despite efforts in this field, the detection of the different layers of information on these documents still poses difficulties. The use of Deep Neural Networks techniques has reported outstanding results in many areas related to computer vision. Consequently, in this paper, we study the so-called Convolutional Neural Networks (CNN) for performing the automatic document processing of music score images. This process is focused on layering the image into its constituent parts (namely, background, staff lines, music notes, and text) by training a classifier with examples of these parts. A comprehensive experimentation in terms of the configuration of the networks was carried out, which illustrates interesting results as regards to both the efficiency and effectiveness of these models. In addition, a cross-manuscript adaptation experiment was presented in which the networks are evaluated on a different manuscript from the one they were trained. The results suggest that the CNN is capable of adapting its knowledge, and so starting from a pre-trained CNN reduces (or eliminates) the need for new labeled data. Full article
(This article belongs to the Special Issue Digital Audio and Image Processing with Focus on Music Research)
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Open AccessArticle Photovoltaic Cell and Module I-V Characteristic Approximation Using Bézier Curves
Appl. Sci. 2018, 8(5), 655; https://doi.org/10.3390/app8050655
Received: 23 March 2018 / Revised: 30 March 2018 / Accepted: 12 April 2018 / Published: 24 April 2018
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Abstract
The aim of this work was to introduce new ways to model the I-V characteristic of a photovoltaic (PV) cell or PV module using straight lines and Bézier curves. This is a complete novel approach, Bézier curves being previously used mainly for computer
[...] Read more.
The aim of this work was to introduce new ways to model the I-V characteristic of a photovoltaic (PV) cell or PV module using straight lines and Bézier curves. This is a complete novel approach, Bézier curves being previously used mainly for computer graphics. The I-V characteristic is divided into three sections, modeled with lines and a quadratic Bézier curve in the first case and with three cubic Bézier curves in the second case. The result proves to be accurate and relies on the fundamental points usually present in the PV cell datasheets: V o c (the open circuit voltage), I s c (the short circuit current), V m p (the maximum power corresponding voltage) and I m p (the maximum power corresponding current), and the parasitic resistances R s h 0 (shunt resistance at I s c ) and R s 0 (series resistance at V o c ). The proposed algorithm completely defines all the implied control points and the error is analyzed. The temperature and irradiance influence is also analyzed. The model is also compared using the least squares fitting method. The final validation shows how to use Bézier cubic curves to accurately represent the I-V curves of an extensive range of PV cells and arrays. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Analytical Point-Cloud Based Geometric Modeling for Additive Manufacturing and Its Application to Cultural Heritage Preservation
Appl. Sci. 2018, 8(5), 656; https://doi.org/10.3390/app8050656
Received: 28 March 2018 / Revised: 20 April 2018 / Accepted: 22 April 2018 / Published: 24 April 2018
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Abstract
Point-cloud is a valuable piece of information for geometric modeling and additive manufacturing of different types of objects. In most cases, a point-cloud is obtained by using the 3D scanners or by using image processing. Alternatively, one can rely on an analytical approach
[...] Read more.
Point-cloud is a valuable piece of information for geometric modeling and additive manufacturing of different types of objects. In most cases, a point-cloud is obtained by using the 3D scanners or by using image processing. Alternatively, one can rely on an analytical approach for creating the required point-cloud. In this study, we develop an analytical method that uses both equation and algorithm-based approaches for creating a point-cloud for modeling a given object (or shape). The analytically created point-cloud can then be processed by using a commercially available CAD package to create a virtual model (or solid CAD model) of the object. Finally, the virtual model can be used to create a physical model (or replica) of the underlying object using a commercially available additive manufacturing device (e.g., a 3D printer). The abovementioned procedure of analytical point-cloud based geometric modeling for additive manufacturing can be applied to preserve artifacts having cultural significance. In particular, we consider the Ainu motifs that represent the cultural heritage of Ainus living in the northern part of Japan (Hokkaido). We first classify the motifs and then model them in the form of a point-clouds using both equations and a recursive process (algorithm) proposed in this study. Finally, we create the CAD model and physical models of the artifacts having Ainu motifs on them. This way, we show the effectiveness of the analytical point-cloud based geometric modeling for additive manufacturing. Full article
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Open AccessArticle One Layer Nonlinear Economic Closed-Loop Generalized Predictive Control for a Wastewater Treatment Plant
Appl. Sci. 2018, 8(5), 657; https://doi.org/10.3390/app8050657
Received: 21 February 2018 / Revised: 15 April 2018 / Accepted: 18 April 2018 / Published: 24 April 2018
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Abstract
The main scope of this paper is the proposal of a new single layer Nonlinear Economic Closed-Loop Generalized Predictive Control (NECLGPC) as an efficient advanced control technique for improving economics in the operation of nonlinear plants. Instead of the classic dual-mode MPC (model
[...] Read more.
The main scope of this paper is the proposal of a new single layer Nonlinear Economic Closed-Loop Generalized Predictive Control (NECLGPC) as an efficient advanced control technique for improving economics in the operation of nonlinear plants. Instead of the classic dual-mode MPC (model predictive controller) schemes, where the terminal control law defined in the terminal region is obtained offline solving a linear quadratic regulator problem, here the terminal control law in the NECLGPC is determined online by an unconstrained Nonlinear Generalized Predictive Control (NGPC). In order to make the optimization problem more tractable two considerations have been made in the present work. Firstly, the prediction model consisting of a nonlinear phenomenological model of the plant is expressed with linear structure and state dependent matrices. Secondly, instead of including the nonlinear economic cost in the objective function, an approximation of the reduced gradient of the economic function is used. These assumptions allow us to design an economic unconstrained nonlinear GPC analytically and to state the NECLGPC allow for the design of an economic problem as a QP (Quadratic Programing) problem each sampling time. Four controllers based on GPC that differ in designs and structures are compared with the proposed control technique in terms of process performance and energy costs. Particularly, the methodology is implemented in the N-Removal process of a Wastewater Treatment Plant (WWTP) and the results prove the efficiency of the method and that it can be used profitably in practical cases. Full article
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Open AccessArticle Investigation into the Effects of the Variable Displacement Mechanism on Swash Plate Oscillation in High-Speed Piston Pumps
Appl. Sci. 2018, 8(5), 658; https://doi.org/10.3390/app8050658
Received: 6 March 2018 / Revised: 30 March 2018 / Accepted: 20 April 2018 / Published: 24 April 2018
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Abstract
High-speed, pressure-compensated variable displacement piston pumps are widely used in aircraft hydraulic systems for their high power density. The swash plate is controlled by the pressure-compensated valve, which uses pressure feedback so that the instantaneous output flow of the pump is exactly enough
[...] Read more.
High-speed, pressure-compensated variable displacement piston pumps are widely used in aircraft hydraulic systems for their high power density. The swash plate is controlled by the pressure-compensated valve, which uses pressure feedback so that the instantaneous output flow of the pump is exactly enough to maintain a presetting pressure. The oscillation of the swash plate is one of the major excitation sources in the high-speed piston pump, which may cause lower efficiency, shorter service life, and even serious damage. This paper presents an improved model to investigate the influence of the variable displacement mechanism on the swash plate oscillation and introduces some feasible ways to reduce oscillation of the swash plate. Most of the variable structural parameters of the variable displacement mechanism are taken into consideration, and their influences on swash plate oscillation are discussed in detail. The influence of the load pipe on the oscillation of the swash plate is considered in the improved model. A test rig is built and similarities between the experiments and simulated results prove that the simulation model can effectively predict the variable displacement mechanism state. The simulation results show that increasing the volume of the outlet chamber, the spring stiffness of the control valve, the action area of the actuator piston, and offset distance of the actuator piston can significantly reduce the oscillation amplitude of the swash plate. Furthermore, reducing the diameter of the control valve spool and the dead volume of the actuator piston chamber can also have a positive effect on oscillation amplitude reduction. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Quantitative Analysis of Patellar Tendon Abnormality in Asymptomatic Professional “Pallapugno” Players: A Texture-Based Ultrasound Approach
Appl. Sci. 2018, 8(5), 660; https://doi.org/10.3390/app8050660
Received: 30 March 2018 / Revised: 20 April 2018 / Accepted: 23 April 2018 / Published: 25 April 2018
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Abstract
Abnormalities in B-mode ultrasound images of the patellar tendon often take place in asymptomatic athletes but it is still not clear if these modifications forego or can predict the development of tendinopathy. Subclinical tendinopathy can be arbitrarily defined as either (1) the presence
[...] Read more.
Abnormalities in B-mode ultrasound images of the patellar tendon often take place in asymptomatic athletes but it is still not clear if these modifications forego or can predict the development of tendinopathy. Subclinical tendinopathy can be arbitrarily defined as either (1) the presence of light structural changes in B-mode ultrasound images in association with mild neovascularization (determined with Power Doppler images) or (2) the presence of moderate/severe structural changes with or without neovascularization. Up to now, the structural changes and neovascularization of the tendon are evaluated qualitatively by visual inspection of ultrasound images. The aim of this study is to investigate the capability of a quantitative texture-based approach to determine tendon abnormality of “pallapugno” players. B-mode ultrasound images of the patellar tendon were acquired in 14 players and quantitative texture parameters were calculated within a Region of Interest (ROI) of both the non-dominant and the dominant tendon. A total of 90 features were calculated for each ROI, including 6 first-order descriptors, 24 Haralick features, and 60 higher-order spectra and entropy features. These features on the dominant and non-dominant side were used to perform a multivariate linear regression analysis (MANOVA) and our results show that the descriptors can be effectively used to determine tendon abnormality and, more importantly, the occurrence of subclinical tendinopathy. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Feasibility of LED-Assisted CMOS Camera: Contrast Estimation for Laser Tattoo Treatment
Appl. Sci. 2018, 8(5), 661; https://doi.org/10.3390/app8050661
Received: 28 March 2018 / Revised: 19 April 2018 / Accepted: 21 April 2018 / Published: 25 April 2018
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Abstract
Understanding the residual tattoo ink in skin after laser treatment is often critical for achieving good clinical outcomes. The current study aims to investigate the feasibility of a light-emitting diode (LED)-assisted CMOS camera to estimate the relative variations in tattoo contrast after the
[...] Read more.
Understanding the residual tattoo ink in skin after laser treatment is often critical for achieving good clinical outcomes. The current study aims to investigate the feasibility of a light-emitting diode (LED)-assisted CMOS camera to estimate the relative variations in tattoo contrast after the laser treatment. Asian mice were tattooed using two color inks (black and red). The LED illumination was a separate process from the laser tattoo treatment. Images of the ink tattoos in skin were acquired under the irradiation of three different LED colors (red, green, and blue) for pre- and post-treatment. The degree of contrast variation due to the treatment was calculated and compared with the residual tattoo distribution in the skin. The black tattoo demonstrated that the contrast consistently decreased after the laser treatment for all LED colors. However, the red tattoo showed that the red LED yielded an insignificant contrast whereas the green and blue LEDs induced a 30% (p < 0.001) and 26% (p < 0.01) contrast reduction between the treatment conditions, respectively. The proposed LED-assisted CMOS camera can estimate the relative variations in the image contrast before and after the laser tattoo treatment. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Iterative 2D Tissue Motion Tracking in Ultrafast Ultrasound Imaging
Appl. Sci. 2018, 8(5), 662; https://doi.org/10.3390/app8050662
Received: 7 March 2018 / Revised: 17 April 2018 / Accepted: 21 April 2018 / Published: 25 April 2018
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Abstract
In order to study longitudinal movement and intramural shearing of the arterial wall with a Lagrangian viewpoint using ultrafast ultrasound imaging, a new tracking scheme is required. We propose the use of an iterative tracking scheme based on temporary down-sampling of the frame-rate,
[...] Read more.
In order to study longitudinal movement and intramural shearing of the arterial wall with a Lagrangian viewpoint using ultrafast ultrasound imaging, a new tracking scheme is required. We propose the use of an iterative tracking scheme based on temporary down-sampling of the frame-rate, anteroposterior tracking, and unbiased block-matching using two kernels per position estimate. The tracking scheme was evaluated on phantom B-mode cine loops and considered both velocity and displacement for a range of down-sampling factors (k = 1–128) at the start of the iterations. The cine loops had a frame rate of 1300–1500 Hz and were beamformed using delay-and-sum. The evaluation on phantom showed that both the mean estimation errors and the standard deviations decreased with an increasing initial down-sampling factor, while they increased with an increased velocity or larger pitch. A limited in vivo study shows that the major pattern of movement corresponds well with state-of-the-art low frame rate motion estimates, indicating that the proposed tracking scheme could enable the study of longitudinal movement of the intima–media complex using ultrafast ultrasound imaging, and is one step towards estimating the propagation velocity of the longitudinal movement of the arterial wall. Full article
(This article belongs to the Special Issue Ultrafast Ultrasound Imaging)
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Open AccessArticle Investigation on a Sensitive Chemiluminescence System Based on Ni(IV) Complex to Determine Two β2-Agonist Drugs in Urine and Swine Feed and Their Mechanism
Appl. Sci. 2018, 8(5), 663; https://doi.org/10.3390/app8050663
Received: 15 March 2018 / Revised: 1 April 2018 / Accepted: 10 April 2018 / Published: 25 April 2018
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Abstract
Veterinary drug residues, particularly traces of β2-agonists, can cause various kinds of harmful impact to the environment and public health. Here, a sensitive chemiluminescence (CL) method incorporated with a flow injection analysis is developed for the determination of two β2
[...] Read more.
Veterinary drug residues, particularly traces of β2-agonists, can cause various kinds of harmful impact to the environment and public health. Here, a sensitive chemiluminescence (CL) method incorporated with a flow injection analysis is developed for the determination of two β2-agonists [i.e., salbutamol (SAL) and terbutaline (TEB)]. The system is based on the CL reaction of Ni(IV) complex with luminol in alkaline solutions, whereas SAL and TEB can significantly enhance CL intensities. Under optimum conditions, CL intensities are proportional to the SAL and TEB concentration in the range of 1.0 × 10−9 M to 5.0 × 10−7 M and 1.0 × 10−9 M to 1.0 × 10−7 M, respectively. The limits of detection (3σ) are 1.0 × 10−11 M for TEB, and 1.3 × 10−11 for SAL respectively. Relative standard deviations (n = 11) are less than 2% for 5.0 × 10−8 M SAL and TEB. Possible reaction mechanisms for the CL system are suggested based on the CL system spectra, Ni(IV) complex oxidation characteristics, and electron spin resonance (ESR) techniques. The proposed method has been applied to the analysis of urine and swine feed samples with satisfactory results. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle DF Relayed Subcarrier FSO Links over Malaga Turbulence Channels with Phase Noise and Non-Zero Boresight Pointing Errors
Appl. Sci. 2018, 8(5), 664; https://doi.org/10.3390/app8050664
Received: 16 February 2018 / Revised: 5 April 2018 / Accepted: 13 April 2018 / Published: 25 April 2018
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Abstract
Subcarrier free-space optical (FSO) systems using coherent recovery techniques at the receiver have acquired growing research interest in recent times. However, their optimal performance is diminished by the non-perfect synchronization of carrier frequency and phase, which is mainly due to phase noise problems.
[...] Read more.
Subcarrier free-space optical (FSO) systems using coherent recovery techniques at the receiver have acquired growing research interest in recent times. However, their optimal performance is diminished by the non-perfect synchronization of carrier frequency and phase, which is mainly due to phase noise problems. Moreover, turbulence and pointing error effects further deteriorate the overall performance. However, relay transmission schemes can extend the coverage distance and offer substantial improvements over fading conditions. In this respect, we consider a serially relayed network using decode-and-forward relays, and investigate its performance by means of average symbol error probability and mean outage duration. Turbulence is modeled by the recently unified M(alaga) distribution, which constitutes a very general statistical model that accurately describes the irradiance fluctuations from weak-to-strong turbulence conditions. Additionally, the presence of non-zero boresight pointing errors due to misalignment between the transmitter–receiver pair is considered, while the effect of phase noise is specified by a Tikhonov distribution. A comparison between single line-of-sight and serially relayed FSO configurations is provided as well. Novel approximated mathematical expressions are deduced, which are proved to be accurate enough over a wide range of turbulence strengths and signal-to-noise values. Finally, proper numerical results are presented and validated by Monte Carlo simulations. Full article
(This article belongs to the Special Issue Optical Wireless Communications)
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Open AccessArticle Propagation Characteristics of High-Power Vortex Laguerre-Gaussian Laser Beams in Plasma
Appl. Sci. 2018, 8(5), 665; https://doi.org/10.3390/app8050665
Received: 3 April 2018 / Revised: 19 April 2018 / Accepted: 19 April 2018 / Published: 25 April 2018
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Abstract
The propagation characteristics of high-power laser beams in plasma is an important research topic and has many potential applications in fields such as laser machining, laser-driven accelerators and laser-driven inertial confined fusion. The dynamic evolution of high-power Laguerre-Gaussian (LG) beams in plasma is
[...] Read more.
The propagation characteristics of high-power laser beams in plasma is an important research topic and has many potential applications in fields such as laser machining, laser-driven accelerators and laser-driven inertial confined fusion. The dynamic evolution of high-power Laguerre-Gaussian (LG) beams in plasma is numerically investigated by using the finite-difference time-domain (FDTD) method based on the nonlinear Drude model, with both plasma frequency and collision frequency modulated by the light intensity of laser beam. The numerical algorithms and implementation techniques of FDTD method are presented for numerically simulating the nonlinear permittivity model of plasma and generating the LG beams with predefined parameters. The simulation results show that the plasma has different field modulation effects on the two exemplified LG beams with different cross-sectional patterns. The self-focusing and stochastic absorption phenomena of high-power laser beam in plasma are also demonstrated. This research also provides a new means for the field modulation of laser beams by plasma. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Optimization of Two-Level Disassembly/Remanufacturing/Assembly System with an Integrated Maintenance Strategy
Appl. Sci. 2018, 8(5), 666; https://doi.org/10.3390/app8050666
Received: 27 March 2018 / Revised: 16 April 2018 / Accepted: 22 April 2018 / Published: 25 April 2018
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Abstract
With an increase of environmental pressure on economic activities, reverse flow is increasingly important. It seeks to save resources, eliminate waste, and improve productivity. This paper investigates the optimization of the disassembly, remanufacturing and assembly system, taking into account assembly-disassembly system degradation. An
[...] Read more.
With an increase of environmental pressure on economic activities, reverse flow is increasingly important. It seeks to save resources, eliminate waste, and improve productivity. This paper investigates the optimization of the disassembly, remanufacturing and assembly system, taking into account assembly-disassembly system degradation. An analytical model is developed to consider disassembly, remanufacturing of used/end-of-life product and assembly of the finished product. The finished product is composed of remanufactured and new components. A maintenance policy is sequentially integrated to reduce the system unavailability. The aim of this study is to help decision-makers, under certain conditions, choose the most cost-effective process for them to satisfy the customer as well as to adapt to the potential risk that can perturb the disassembly-assembly system. A heuristic is developed to determine the optimal ordered date of the used end-of-life product as well as the optimum release dates of new external components. The results reveal that considering some remanufacturing and purchase components costs, the proposed model is more economical in comparison with a model without remanufactured parts. Numerical results are provided to illustrate the impact of the variation of the ordering cost and quality of the used end-of-life product on the system profitability. Finally, the risk due to system repair periods is discussed, which has an impact on managerial decision-making. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Application of Mastic Asphalt Waterproofing Layer in High-Speed Railway Track in Cold Regions
Appl. Sci. 2018, 8(5), 667; https://doi.org/10.3390/app8050667
Received: 13 March 2018 / Revised: 13 April 2018 / Accepted: 23 April 2018 / Published: 26 April 2018
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Abstract
Freeze-thaw damage is a typical distress incurred in road and railway engineering in cold regions. Concrete waterproofing layer is commonly used in high-speed railway tracks to prevent the penetration of surface water, however, it cracks easily under thermal stress, especially in cold regions.
[...] Read more.
Freeze-thaw damage is a typical distress incurred in road and railway engineering in cold regions. Concrete waterproofing layer is commonly used in high-speed railway tracks to prevent the penetration of surface water, however, it cracks easily under thermal stress, especially in cold regions. Recently solutions have been proposed to increase the waterproofing layer’s cracking resistance by using asphalt layers. Nonetheless, the use of emulsified asphalt as well as dense-graded asphalt mixture were not effective enough. To improve the effectiveness, in this study, mastic asphalt was designed for application as the waterproofing layer on the subgrade surface of high-speed railway tracks in cold regions. The overall performance of mastic asphalt was preliminarily evaluated by laboratory tests, then a 200-m test section was constructed for field validation in northeastern China as part of a new high-speed railway line, and water content sensors were placed inside the subgrade to monitor the performance of the mastic asphalt waterproofing layer (MAWL). The subsequent field investigation and monitoring data during the two years operation showed that MAWL dramatically outperformed the conventional concrete waterproofing layer in terms of waterproof performance. Plenty of serious cracks were found in the conventional concrete waterproofing layer, but only a limited number of local cracks were observed in MAWL. As a result, MAWL keeps the water content of subgrade at a stable level. In addition, MAWL showed relatively high stability during the two years investigation period, and no obvious deterioration was observed in the test section. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Nature Inspired Plasmonic Structures: Influence of Structural Characteristics on Sensing Capability
Appl. Sci. 2018, 8(5), 668; https://doi.org/10.3390/app8050668
Received: 15 March 2018 / Revised: 13 April 2018 / Accepted: 23 April 2018 / Published: 26 April 2018
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Abstract
Surface enhanced Raman scattering (SERS) is a powerful analytical technique that allows the enhancement of a Raman signal in a molecule or molecular assemblies placed in the proximity of nanostructured metallic surfaces, due to plasmonic effects. However, laboratory methods to obtain of these
[...] Read more.
Surface enhanced Raman scattering (SERS) is a powerful analytical technique that allows the enhancement of a Raman signal in a molecule or molecular assemblies placed in the proximity of nanostructured metallic surfaces, due to plasmonic effects. However, laboratory methods to obtain of these prototypes are time-consuming, expensive and they do not always lead to the desired result. In this work, we analyse structures existing in nature that show, on a nanoscale, characteristic conformations of photonic crystals. We demonstrate that these structures, if covered with gold, change into plasmonic nanostructures and are able to sustain the SERS effect. We study three different structures with this property: opal, a hydrated amorphous form of silica (SiO2·nH2O); diatoms, a kind of unicellular alga; and peacock tail feather. Rhodamine 6G (down to 10−12 M) is used to evaluate their capability to increase the Raman signal. These results allow us to define an alternative way to obtain a high sensitivity in Raman spectroscopy, currently achieved by a long and expensive technique, and to fabricate inexpensive nanoplasmonic structures which could be integrated into optical sensors. Full article
(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)
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Open AccessArticle Experimental Study on Dynamic Effects of a Long-span Railway Continuous Beam Bridge
Appl. Sci. 2018, 8(5), 669; https://doi.org/10.3390/app8050669
Received: 7 March 2018 / Revised: 4 April 2018 / Accepted: 14 April 2018 / Published: 26 April 2018
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Abstract
Studies on impact effects of trains on the railway bridge are important for ensuring the reliability of bridge and the safety of train operation. This paper presents an experimental study on the dynamic effects of moving trains on a long-span railway continuous beam
[...] Read more.
Studies on impact effects of trains on the railway bridge are important for ensuring the reliability of bridge and the safety of train operation. This paper presents an experimental study on the dynamic effects of moving trains on a long-span railway continuous beam bridge. The dynamic responses of the bridge under the moving trains were measured through in-situ testing and finite element analysis. The influences of the moving trains and track irregularity are considered. The investigated influencing factors include the weight and speed of the train and the irregularity of the track on the bridge. The results indicate that the train’s speed does not have obvious influence on the impact factor, while train’s weight and track irregularity have notable effects on the impact factor. But from the overall development law, with the increase of train speed, the impact factor increases. The impact factors obtained in this study are larger than the values provided by the China bridge design codes, which indicates that the bridge code underestimates the impact effect of the train on the bridge. The design value of the impact factor should be properly improved in the bridge design. Full article
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Open AccessFeature PaperArticle Strained Silicon Single Nanowire Gate-All-Around TFETs with Optimized Tunneling Junctions
Appl. Sci. 2018, 8(5), 670; https://doi.org/10.3390/app8050670
Received: 15 March 2018 / Revised: 11 April 2018 / Accepted: 20 April 2018 / Published: 26 April 2018
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Abstract
In this work, we demonstrate a strained Si single nanowire tunnel field effect transistor (TFET) with gate-all-around (GAA) structure yielding Ion-current of 15 μA/μm at the supply voltage of Vdd = 0.5V with linear onset at low drain voltages. The
[...] Read more.
In this work, we demonstrate a strained Si single nanowire tunnel field effect transistor (TFET) with gate-all-around (GAA) structure yielding Ion-current of 15 μA/μm at the supply voltage of Vdd = 0.5V with linear onset at low drain voltages. The subthreshold swing (SS) at room temperature shows an average of 76 mV/dec over 4 orders of drain current Id from 5 × 10−6 to 5 × 10−2 µA/µm. Optimized devices also show excellent current saturation, an important feature for analog performance. Full article
(This article belongs to the Special Issue Silicon Nanowires and Their Applications)
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Open AccessArticle Synthesis, Characterization, and Self-Assembly of a Tetrathiafulvalene (TTF)–Triglycyl Derivative
Appl. Sci. 2018, 8(5), 671; https://doi.org/10.3390/app8050671
Received: 3 April 2018 / Revised: 18 April 2018 / Accepted: 23 April 2018 / Published: 26 April 2018
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Abstract
In this work, we describe the synthesis, characterization, and self-assembly properties of a new tetrathiafulvalene (TTF)–triglycyl low-molecular-weight (LMW) gelator. Supramolecular organogels were obtained in various solvents via a heating–cooling cycle. Critical gelation concentrations (CGC) (range ≈ 5–50 g/L) and thermal gel-to-sol
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In this work, we describe the synthesis, characterization, and self-assembly properties of a new tetrathiafulvalene (TTF)–triglycyl low-molecular-weight (LMW) gelator. Supramolecular organogels were obtained in various solvents via a heating–cooling cycle. Critical gelation concentrations (CGC) (range ≈ 5–50 g/L) and thermal gel-to-sol transition temperatures (Tgel) (range ≈ 36–51 °C) were determined for each gel. Fourier transform infrared (FT-IR) spectroscopy suggested that the gelator is also aggregated in its solid state via a similar hydrogen-bonding pattern. The fibrillar microstructure and viscoelastic properties of selected gels were demonstrated by means of field-emission electron microscopy (FE-SEM) and rheological measurements. As expected, exposure of a model xerogel to I2 vapor caused the oxidation of the TTF unit as confirmed by UV-vis-NIR analysis. However, FT-IR spectroscopy showed that the oxidation was accompanied with concurrent alteration of the hydrogen-bonded network. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Noise Attenuation Based on Wave Vector Characteristics
Appl. Sci. 2018, 8(5), 672; https://doi.org/10.3390/app8050672
Received: 15 March 2018 / Revised: 17 April 2018 / Accepted: 17 April 2018 / Published: 26 April 2018
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Abstract
Polarization filtering has been widely used to enhance signal-to-noise ratios for multicomponent seismic data. Polarization filters routinely depend on the ellipticity and directionality of spatial particle motions. However, factors such as noise and formation heterogeneity often make the polarization characteristics of body waves
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Polarization filtering has been widely used to enhance signal-to-noise ratios for multicomponent seismic data. Polarization filters routinely depend on the ellipticity and directionality of spatial particle motions. However, factors such as noise and formation heterogeneity often make the polarization characteristics of body waves hard to distinguish. Here, we introduce a technique in the time domain for the separation of valid body waves and noise based on wave vector characteristics. First, we characterise the ground-roll polarization by the median wave vectors derived in large-scale moving time windows. For the suppression of ground roll, we fit the particle trajectory of ground roll by the least square method using all components simultaneously. Second, we apply three-stage smoothing to the ground-roll-removed multicomponent records. In each stage, we use mean or median vectors derived in small-scale moving-time or moving-trace windows to attenuate random noise and other non-ground-roll related coherent noise. The filter in the proposed method is not devised according to ellipticity and directionality. Instead, we use the wave vector decomposition to distinguish between noise and valid signals. Synthetic data and field data examples confirm that the proposed method can effectively suppress noise without damaging the high and low frequencies of a valid signal. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Microstructure and Mechanical Properties of the Dactylopodites of the Chinese Mitten Crab (Eriocheir sinensis)
Appl. Sci. 2018, 8(5), 674; https://doi.org/10.3390/app8050674
Received: 1 April 2018 / Revised: 18 April 2018 / Accepted: 21 April 2018 / Published: 26 April 2018
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Abstract
The dactylopodites of the Chinese mitten crab (Eriocheir sinensis) have evolved extraordinary resistance to wear and impact loading after direct contact with rough surfaces or clashing with hard materials. In this study, the microstructure, components, and mechanical properties of the dactylopodites
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The dactylopodites of the Chinese mitten crab (Eriocheir sinensis) have evolved extraordinary resistance to wear and impact loading after direct contact with rough surfaces or clashing with hard materials. In this study, the microstructure, components, and mechanical properties of the dactylopodites of the Chinese mitten crab were investigated. Images from a scanning electron microscope show that the dactylopodites’ exoskeleton was multilayered, with an epicuticle, exocuticle, and endocuticle. Cross sections and longitudinal sections of the endocuticle revealed a Bouligand structure, which contributes to the dactylopodites’ mechanical properties. The main organic constituents of the exoskeleton were chitin and protein, and the major inorganic compound was CaCO3, crystallized as calcite. Dry and wet dactylopodites were brittle and ductile, respectively, characteristics that are closely related to their mechanical structure and composition. The findings of this study can be a reference for the bionic design of strong and durable structural materials. Full article
(This article belongs to the Section Materials)
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Open AccessArticle In Situ Experimental Study of the Friction of Sea Ice and Steel on Sea Ice
Appl. Sci. 2018, 8(5), 675; https://doi.org/10.3390/app8050675
Received: 9 April 2018 / Revised: 21 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
The kinetic coefficient of friction μk was measured for sea ice, stainless steel, and coated steel sliding on a natural sea ice cover. The effects of normal stress (3.10–8.11 kPa), ice columnar grain orientation (vertical and parallel to the sliding direction), sliding
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The kinetic coefficient of friction μk was measured for sea ice, stainless steel, and coated steel sliding on a natural sea ice cover. The effects of normal stress (3.10–8.11 kPa), ice columnar grain orientation (vertical and parallel to the sliding direction), sliding velocity (0.02–2.97 m·s–1), and contact material were investigated. Air temperature was higher than −5.0 °C for the test duration. The results showed a decline of μk with increasing normal stress with μk independent of ice grain orientation. The μk of different materials varied, partly due to distinct surface roughnesses, but all cases showed a similar increasing trend with increasing velocity because of the viscous resistance of melt-water film. The velocity dependence of μk was quantified using the rate- and state- dependent model, and μk was found to increase logarithmically with increasing velocity. In addition, μk obtained at higher air temperatures was greater than at lower temperatures. The stick-slip phenomenon was observed at a relatively high velocity compared with previous studies, which was partly due to the low-stiffness device used in the field. Based on the experimental data, the calculation of physical models can be compared. Full article
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Open AccessArticle Improved Deep Belief Networks (IDBN) Dynamic Model-Based Detection and Mitigation for Targeted Attacks on Heavy-Duty Robots
Appl. Sci. 2018, 8(5), 676; https://doi.org/10.3390/app8050676
Received: 31 March 2018 / Revised: 19 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
In recent years, the robots, especially heavy-duty robots, have become the hardest-hit areas for targeted attacks. These attacks come from both the cyber-domain and the physical-domain. In order to improve the security of heavy-duty robots, this paper proposes a detection and mitigation mechanism
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In recent years, the robots, especially heavy-duty robots, have become the hardest-hit areas for targeted attacks. These attacks come from both the cyber-domain and the physical-domain. In order to improve the security of heavy-duty robots, this paper proposes a detection and mitigation mechanism which based on improved deep belief networks (IDBN) and dynamic model. The detection mechanism consists of two parts: (1) IDBN security checks, which can detect targeted attacks from the cyber-domain; (2) Dynamic model and security detection, used to detect the targeted attacks which can possibly lead to a physical-domain damage. The mitigation mechanism was established on the base of the detection mechanism and could mitigate transient and discontinuous attacks. Moreover, a test platform was established to carry out the performance evaluation test for the proposed mechanism. The results show that, the detection accuracy for the attack of the cyber-domain of IDBN reaches 96.2%, and the detection accuracy for the attack of physical-domain control commands reaches 94%. The performance evaluation test has verified the reliability and high efficiency of the proposed detection and mitigation mechanism for heavy-duty robots. Full article
(This article belongs to the Special Issue Security and Privacy for Cyber Physical Systems)
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Open AccessArticle Capability of the Direct Dimethyl Ether Synthesis Process for the Conversion of Carbon Dioxide
Appl. Sci. 2018, 8(5), 677; https://doi.org/10.3390/app8050677
Received: 21 March 2018 / Revised: 23 April 2018 / Accepted: 23 April 2018 / Published: 26 April 2018
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Abstract
The direct synthesis of dimethyl ether (DME) is an ideal process to achieve the environmental objective of CO2 conversion together with the economic objective of DME production. The effect of the reaction conditions (temperature, pressure, space time) and feed composition (ternary mixtures
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The direct synthesis of dimethyl ether (DME) is an ideal process to achieve the environmental objective of CO2 conversion together with the economic objective of DME production. The effect of the reaction conditions (temperature, pressure, space time) and feed composition (ternary mixtures of H2 + CO + CO2 with different CO2/CO and H2/COx molar ratios) on the reaction indices (COx conversion, product yield and selectivity, CO2 conversion) has been studied by means of experiments carried out in a fixed-bed reactor, with a CuO-ZnO-MnO/SAPO-18 catalyst, in order to establish suitable ranges of operating conditions for enhancing the individual objectives of CO2 conversion and DME yield. The optimums of these two objectives are achieved in opposite conditions, and for striking a good balance between both objectives, the following conditions are suitable: 275–300 °C; 20–30 bar; 2.5–5 gcat h (molC)−1 and a H2/COx molar ratio in the feed of 3. CO2/CO molar ratio in the feed is of great importance. Ratios below 1/3 are suitable for enhancing DME production, whereas CO2/CO ratios above 1 improve the conversion of CO2. This conversion of CO2 in the overall process of DME synthesis is favored by the reverse water gas shift equation, since CO is more active than CO2 in the methanol synthesis reaction. Full article
(This article belongs to the Special Issue Carbon Capture Utilization and Sequestration (CCUS))
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Open AccessArticle Forecasting of Energy Consumption in China Based on Ensemble Empirical Mode Decomposition and Least Squares Support Vector Machine Optimized by Improved Shuffled Frog Leaping Algorithm
Appl. Sci. 2018, 8(5), 678; https://doi.org/10.3390/app8050678
Received: 6 March 2018 / Revised: 15 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
For social development, energy is a crucial material whose consumption affects the stable and sustained development of the natural environment and economy. Currently, China has become the largest energy consumer in the world. Therefore, establishing an appropriate energy consumption prediction model and accurately
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For social development, energy is a crucial material whose consumption affects the stable and sustained development of the natural environment and economy. Currently, China has become the largest energy consumer in the world. Therefore, establishing an appropriate energy consumption prediction model and accurately forecasting energy consumption in China have practical significance, and can provide a scientific basis for China to formulate a reasonable energy production plan and energy-saving and emissions-reduction-related policies to boost sustainable development. For forecasting the energy consumption in China accurately, considering the main driving factors of energy consumption, a novel model, EEMD-ISFLA-LSSVM (Ensemble Empirical Mode Decomposition and Least Squares Support Vector Machine Optimized by Improved Shuffled Frog Leaping Algorithm), is proposed in this article. The prediction accuracy of energy consumption is influenced by various factors. In this article, first considering population, GDP (Gross Domestic Product), industrial structure (the proportion of the second industry added value), energy consumption structure, energy intensity, carbon emissions intensity, total imports and exports and other influencing factors of energy consumption, the main driving factors of energy consumption are screened as the model input according to the sorting of grey relational degrees to realize feature dimension reduction. Then, the original energy consumption sequence of China is decomposed into multiple subsequences by Ensemble Empirical Mode Decomposition for de-noising. Next, the ISFLA-LSSVM (Least Squares Support Vector Machine Optimized by Improved Shuffled Frog Leaping Algorithm) model is adopted to forecast each subsequence, and the prediction sequences are reconstructed to obtain the forecasting result. After that, the data from 1990 to 2009 are taken as the training set, and the data from 2010 to 2016 are taken as the test set to make an empirical analysis for energy consumption prediction. Four models, ISFLA-LSSVM, SFLA-LSSVM (Least Squares Support Vector Machine Optimized by Shuffled Frog Leaping Algorithm), LSSVM (Least Squares Support Vector Machine), and BP(Back Propagation) neural network (Back Propagation neural network), are selected to compare with the EEMD-ISFLA-LSSVM model based on the evaluation indicators of mean absolute percentage error (MAPE), root mean square error (RMSE), and mean absolute error (MAE), which fully prove the practicability of the EEMD-ISFLA-LSSVM model for energy consumption forecasting in China. Finally, the EEMD-ISFLA-LSSVM model is adopted to forecast the energy consumption in China from 2018 to 2022, and, according to the forecasting results, it can be seen that China’s energy consumption from 2018 to 2022 will have a trend of significant growth. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Experimental Study of Ground Subsidence Mechanism Caused by Sewer Pipe Cracks
Appl. Sci. 2018, 8(5), 679; https://doi.org/10.3390/app8050679
Received: 14 March 2018 / Revised: 14 April 2018 / Accepted: 19 April 2018 / Published: 26 April 2018
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Abstract
Simultaneous leakage of soil particles and groundwater into underground vacant spaces caused by sewer pipe defects and cracks can cause underground cavities and even ground collapse on the surface. Numerical studies of this problem are limited, and the mechanism of ground subsidence caused
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Simultaneous leakage of soil particles and groundwater into underground vacant spaces caused by sewer pipe defects and cracks can cause underground cavities and even ground collapse on the surface. Numerical studies of this problem are limited, and the mechanism of ground subsidence caused by leakage of soil and groundwater into construction sites has yet to be verified. In this study, the factors affecting the mechanism of ground subsidence are verified via physical modelling of a sewer pipe defect. Through visual inspection and particle image velocimetry analysis, it has been found that the groundwater flow direction, hydraulic gradient around the leakage point, and strength of the ground to support itself are the main factors that dominate the mechanism of ground subsidence. These factors can affect ground deformation and cavity expansion direction, ground subsidence development and collapse speed, and occurrence of sudden ground collapse, respectively. It was also found that pore pressure fluctuates when cavity cavern collapse and cavity expansion occur. Full article
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Open AccessArticle An Effective Directional Residual Interpolation Algorithm for Color Image Demosaicking
Appl. Sci. 2018, 8(5), 680; https://doi.org/10.3390/app8050680
Received: 12 March 2018 / Revised: 20 April 2018 / Accepted: 21 April 2018 / Published: 26 April 2018
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Abstract
In this paper, we propose an effective directional Bayer color filter array (CFA) demosaicking algorithm based on residual interpolation (RI). The proposed directional interpolation algorithm aims to reduce computational complexity and get more accurate interpolated pixel values in the complex edge areas. We
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In this paper, we propose an effective directional Bayer color filter array (CFA) demosaicking algorithm based on residual interpolation (RI). The proposed directional interpolation algorithm aims to reduce computational complexity and get more accurate interpolated pixel values in the complex edge areas. We use the horizontal and vertical weights to combine and smooth color difference estimations. Compared with four directional weights in minimized Laplacian residual interpolation, the proposed algorithm not only guarantees the quality of color images but also reduces the computational complexity. Generally, the directional estimations may be inaccurately calculated because of the false edge information in irregular edges. We alleviate it by using a new method to calculate the directional color difference estimations. Experimental results show that the proposed algorithm provides outstanding performance compared with some previous algorithms, especially in the complex edge areas. In addition, it has lower computational complexity and better visual effect. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessCommunication Experimental and Simulation Identification of Xanthohumol as an Inhibitor and Substrate of ABCB1
Appl. Sci. 2018, 8(5), 681; https://doi.org/10.3390/app8050681
Received: 30 March 2018 / Revised: 11 April 2018 / Accepted: 15 April 2018 / Published: 27 April 2018
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Abstract
Xanthohumol (XN) is a well-known prenylated flavonoid found in Humulus lupulus L. It is involved in several pharmacological activities, including the sensitization of doxorubicin-resistant breast cancer (MCF-7/ADR) cells to doxorubicin (DOX) through a reduction in cell viability and stemness. In the present study,
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Xanthohumol (XN) is a well-known prenylated flavonoid found in Humulus lupulus L. It is involved in several pharmacological activities, including the sensitization of doxorubicin-resistant breast cancer (MCF-7/ADR) cells to doxorubicin (DOX) through a reduction in cell viability and stemness. In the present study, we revealed another mechanism to further explain the reverse of the drug resistance of XN. In the MCF-7/ADR cell line, we found that XN inhibited the efflux functions of ATP-binding cassette subfamily B member 1 (ABCB1). We also observed that XN was a substrate of ABCB1 and stimulated its ATPase activity. Moreover, our results revealed that XN showed a synergic effect with the ABCB1 substrate colchicine (COL) in the MCF-7/ADR cell line. Further, we showed that XN bound to the central transmembrane domain (TMD) site, overlapping with the DOX binding site. This mechanism was supported by molecular modeling and simulation data, which revealed that XN bound to the ABCB1 transmembrane domain, where doxorubicin also binds, and its binding affinity was stronger than that of doxorubicin, resulting in less protein and ligand position fluctuation. These results support the XN-induced reversal of drug resistance via the inhibition of ABCB1-mediated transport of doxorubicin, stimulating ABCB1 ATPase activity and acting as a substrate of ABCB1. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Performance Evaluation of a Chinese Lean Iron Ore as the Oxygen Carrier in Multi and Short-Time Redox Cycles
Appl. Sci. 2018, 8(5), 682; https://doi.org/10.3390/app8050682
Received: 9 March 2018 / Revised: 21 April 2018 / Accepted: 25 April 2018 / Published: 27 April 2018
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Abstract
The performance of a Chinese lean iron ore as the oxygen carrier in chemical looping combustion was investigated in a fixed bed reactor. Considering the short contact time between the fuel gas and oxygen carrier in the sub-pilot experimental setup, the short injection
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The performance of a Chinese lean iron ore as the oxygen carrier in chemical looping combustion was investigated in a fixed bed reactor. Considering the short contact time between the fuel gas and oxygen carrier in the sub-pilot experimental setup, the short injection time of CO was employed in the reactor to simulate this event. The injection time of CO was set to 60 s, 50 s and 40 s respectively, to investigate its effects on the reactivity of the oxygen carrier. A total of 100 cyclic reactions under each condition were carried out to test the reactivity stability of the oxygen carrier. The oxygen carriers prior and after reactions were characterized using SEM, XRD and BET. Results showed that there was an activation process of the reactivity during initial cycles. The extension of the reaction time was beneficial to the diffusion of CO into the oxygen carrier and could improve the conversion of CO. Also, it could form larger pore volumes for gas diffusion in the oxygen carrier. However, it led to the formation of the Fe2SiO4 and severe sintering on the surface, which was harmful to the stability of the oxygen carrier’s reactivity. Full article
(This article belongs to the Special Issue Advances in Oxygen Carrier for Energy Applications)
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Open AccessArticle Experimental Analysis on Pre-Stress Friction Loss of Crushed Limestone Sand Concrete Beams
Appl. Sci. 2018, 8(5), 683; https://doi.org/10.3390/app8050683
Received: 21 March 2018 / Revised: 19 April 2018 / Accepted: 19 April 2018 / Published: 27 April 2018
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Abstract
This paper presents an experimental research work that evaluates the pre-stress loss caused by friction in crushed limestone sand (CLS) concrete members with post-tensioning. A total of 26 full-scale pre-stressed concrete beams were constructed and tested for the friction loss experiment. The considered
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This paper presents an experimental research work that evaluates the pre-stress loss caused by friction in crushed limestone sand (CLS) concrete members with post-tensioning. A total of 26 full-scale pre-stressed concrete beams were constructed and tested for the friction loss experiment. The considered variables mainly included the duct-forming materials, wires of tendons and arrangement of ducts. The tensile forces at both active and passive ends of specimen were recorded by steps, and then the pre-stress friction loss for each case was calculated. The result shows that the proportion of pre-stress friction loss in specimen with multi-wire tendons is in the range of 10–40%, with the trend first increasing before decreasing. The pre-stress friction loss in specimen with curve duct accounts for 10–30%. The pressure on the curved part definitely increases the friction when compared with the straight duct. The pre-stress friction loss in specimen with rubber hose reaches nearly 40%, which is larger than the metal bellow and plastic bellow. The suggested values for each case are proposed for a deviation coefficient κ of 0.0017–0.007 and a friction coefficient μ of 0.108–0.858. This can provide reliable theoretical support for the design and construction. Full article
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Open AccessArticle CFD Simulation of Vortex Induced Vibration for FRP Composite Riser with Different Modeling Methods
Appl. Sci. 2018, 8(5), 684; https://doi.org/10.3390/app8050684
Received: 18 March 2018 / Revised: 18 April 2018 / Accepted: 24 April 2018 / Published: 27 April 2018
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Abstract
Steel risers are widely used in offshore oil and gas industry. However, the production capacity and depths are limited due to their extreme weight and poor fatigue and corrosion resistance. Nowadays, it is confirmed that fiber reinforced polymer (FRP) composite risers have apparent
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Steel risers are widely used in offshore oil and gas industry. However, the production capacity and depths are limited due to their extreme weight and poor fatigue and corrosion resistance. Nowadays, it is confirmed that fiber reinforced polymer (FRP) composite risers have apparent advantages over steel risers. However, the study of vortex induced vibration (VIV) for composite risers is rarely involved. Three different risers (one steel riser and two composite risers) were compared for their VIV characteristics. The effects of 2D and 3D models and fluid–structure interaction (FSI) were considered. The models of composite risers are established by effective modulus method (EMM) and layered-structure method (LSM). It is found that 2D model are only suitable for ideal condition, while, for real situation, 3D model with FSI has to be considered. The results show that the displacements of the FRP composite risers are significantly larger than those of the steel riser, while the stresses are reversed. In addition, the distributions of the displacements and stresses depend on the geometries, material properties, top-tension force, constraints, etc. In addition, it is obvious that EMM are suitable to study the global working condition while LSM can be utilized to obtain the results in every single composite layer. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Active Noise Control Using Modified FsLMS and Hybrid PSOFF Algorithm
Appl. Sci. 2018, 8(5), 686; https://doi.org/10.3390/app8050686
Received: 4 March 2018 / Revised: 17 April 2018 / Accepted: 19 April 2018 / Published: 27 April 2018
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Abstract
Active noise control is an efficient technique for noise cancellation of the system, which has been defined in this paper with the aid of Modified Filtered-s Least Mean Square (MFsLMS) algorithm. The Hybrid Particle Swarm Optimization and Firefly (HPSOFF) algorithm are used to
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Active noise control is an efficient technique for noise cancellation of the system, which has been defined in this paper with the aid of Modified Filtered-s Least Mean Square (MFsLMS) algorithm. The Hybrid Particle Swarm Optimization and Firefly (HPSOFF) algorithm are used to identify the stability factor of the MFsLMS algorithm. The computational difficulty of the modified algorithm is reduced when compared with the original Filtered-s Least Mean Square (FsLMS) algorithm. The noise sources are removed from the signal and it is compared with the existing FsLMS algorithm. The performance of the system is established with the normalized mean square error for two different types of noises. The proposed method has also been compared with the existing algorithms for the same purposes. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Dynamic Multiple Junction Selection Based Routing Protocol for VANETs in City Environment
Appl. Sci. 2018, 8(5), 687; https://doi.org/10.3390/app8050687
Received: 23 January 2018 / Revised: 14 February 2018 / Accepted: 16 February 2018 / Published: 28 April 2018
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Abstract
VANET (Vehicular Ad-hoc Network) is an emerging offshoot of MANETs (Mobile Ad-hoc Networks) with highly mobile nodes. It is envisioned to play a vital role in providing safety communications and commercial applications to the on-road public. Establishing an optimal route for vehicles to
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VANET (Vehicular Ad-hoc Network) is an emerging offshoot of MANETs (Mobile Ad-hoc Networks) with highly mobile nodes. It is envisioned to play a vital role in providing safety communications and commercial applications to the on-road public. Establishing an optimal route for vehicles to send packets to their respective destinations in VANETs is challenging because of quick speed of vehicles, dynamic nature of the network, and intermittent connectivity among nodes. This paper presents a novel position based routing technique called Dynamic Multiple Junction Selection based Routing (DMJSR) for the city environment. The novelty of DMJSR as compared to existing approaches comes from its novel dynamic multiple junction selection mechanism and an improved greedy forwarding mechanism based on one-hop neighbors between the junctions. To the best of our knowledge, it is the first ever attempt to study the impact of multiple junction selection mechanism on routing in VANETs. We present a detailed depiction of our protocol and the improvements it brings as compared to existing routing strategies. The simulation study exhibits that our proposed protocol outperforms the existing protocols like Geographic Source Routing Protocol (GSR), Enhanced Greedy Traffic Aware Routing Protocol (E-GyTAR) and Traffic Flow Oriented Routing Protocol (TFOR) in terms of packet delivery ratio, end-to-end delay, and routing overhead. Full article
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Open AccessArticle Development of Semantic Web-Enabled BDI Multi-Agent Systems Using SEA_ML: An Electronic Bartering Case Study
Appl. Sci. 2018, 8(5), 688; https://doi.org/10.3390/app8050688
Received: 4 March 2018 / Revised: 8 April 2018 / Accepted: 25 April 2018 / Published: 28 April 2018
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Abstract
In agent-oriented software engineering (AOSE), the application of model-driven development (MDD) and the use of domain-specific modeling languages (DSMLs) for Multi-Agent System (MAS) development are quite popular since the implementation of MAS is naturally complex, error-prone, and costly due to the autonomous and
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In agent-oriented software engineering (AOSE), the application of model-driven development (MDD) and the use of domain-specific modeling languages (DSMLs) for Multi-Agent System (MAS) development are quite popular since the implementation of MAS is naturally complex, error-prone, and costly due to the autonomous and proactive properties of the agents. The internal agent behavior and the interaction within the agent organizations become even more complex and hard to implement when the requirements and interactions for the other agent environments such as the Semantic Web are considered. Hence, in this study, we propose a model-driven MAS development methodology which is based on a domain-specific modeling language (called SEA_ML) and covers the whole process of analysis, modeling, code generation and implementation of a MAS working in the Semantic Web according to the well-known Belief-Desire-Intention (BDI) agent principles. The use of new SEA_ML-based MAS development methodology is exemplified with the development of a semantic web-enabled MAS for electronic bartering (E-barter). Achieved results validated the generation and the development-time performance of applying this new MAS development methodology. More than half of the all agents and artifacts needed for fully implementing the E-barter MAS were automatically obtained by just using the generation features of the proposed methodology. Full article
(This article belongs to the Special Issue Multi-Agent Systems)
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Open AccessArticle A Short-Term Photovoltaic Power Prediction Model Based on the Gradient Boost Decision Tree
Appl. Sci. 2018, 8(5), 689; https://doi.org/10.3390/app8050689
Received: 20 March 2018 / Revised: 26 April 2018 / Accepted: 26 April 2018 / Published: 28 April 2018
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Abstract
Due to the development of photovoltaic (PV) technology and the support from governments across the world, the conversion efficiency of solar energy has been improved. However, the PV power output is influenced by environment factors, resulting in features of randomness and intermittency. These
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Due to the development of photovoltaic (PV) technology and the support from governments across the world, the conversion efficiency of solar energy has been improved. However, the PV power output is influenced by environment factors, resulting in features of randomness and intermittency. These features may have a negative influence on power systems. As a result, accurate and timely power prediction data is necessary for power grids to absorb solar energy. In this paper, we propose a new PV power prediction model based on the Gradient Boost Decision Tree (GBDT), which ensembles several binary trees by the gradient boosting ensemble method. The Gradient Boost method builds a strong learner by combining weak learners through iterative methods and the Decision Tree is a basic classification and regression method. As an ensemble machine learning algorithm, the Gradient Boost Decision Tree algorithm can offer higher forecast accuracy than one single learning algorithm. So GBDT is of value in both theoretical research and actual practice in the field of photovoltaic power prediction. The prediction model based on GBDT uses historical weather data and PV power output data to iteratively train the model, which is used to predict the future PV power output based on weather forecast data. Simulation results show that the proposed model based on GBDT has advantages of strong model interpretation, high accuracy, and stable error performance, and thus is of great significance for supporting the secure, stable and economic operation of power systems. Full article
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Open AccessArticle Optimal Power Allocation with Hybrid Relaying Based on the Channel Condition
Appl. Sci. 2018, 8(5), 690; https://doi.org/10.3390/app8050690
Received: 18 March 2018 / Revised: 22 April 2018 / Accepted: 26 April 2018 / Published: 29 April 2018
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Abstract
This paper considers a hybrid relay network consisting of the source, the amplify-and-forward (AF) relay, the decode-and-forward (DF) relay, and the destination. In hybrid three-hop relay systems, the transmitted signal from source can be received at the destination after processing the signals through
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This paper considers a hybrid relay network consisting of the source, the amplify-and-forward (AF) relay, the decode-and-forward (DF) relay, and the destination. In hybrid three-hop relay systems, the transmitted signal from source can be received at the destination after processing the signals through two relays. If the first relay amplifies and forwards the received signal, and the second relay decodes and forwards the received signal, the system model is considered to be an AF-DF relay system. The reverse case is considered for the DF-AF relay system. The AF-DF and DF-AF relay systems have different error rates and achievable throughput with respect to the channel conditions between two nodes. We propose optimal power allocation schemes for two different relays in order to maximize the achievable rate under a sum relay power constraint for given channel gains and transmit power from the source. By solving the optimization problem to maximize the achievable rate for each relay network, the transmit power values in closed form are derived. When the channel gains are the same, the optimal power allocation scheme for the AF-DF relay network proves that greater power should be allocated at the first relay to maximize the achievable rate. In the case of the DF-AF relay network, we derive an optimal power allocation scheme for the four possible cases. Under the same signal-to-noise ratio (SNR) condition, at the first hop we show that the achievable rate of the AF-DF relay network is greater than that of the DF-AF relay network when the channel gain between two relays is greater than that between the second relay and destination. Simulation results show that the proposed power allocation schemes provide a higher achievable rate than the equal power allocation scheme and the grid search schemes. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Fatigue Equation of Cement-Treated Aggregate Base Materials under a True Stress Ratio
Appl. Sci. 2018, 8(5), 691; https://doi.org/10.3390/app8050691
Received: 4 April 2018 / Revised: 26 April 2018 / Accepted: 26 April 2018 / Published: 29 April 2018
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Abstract
The objective of this article is to establish a fatigue equation based on the true stress ratio for cement-treated aggregate base materials. The true stress ratio herein means the ratio of the stress and the true strength of the cement-treated aggregate base materials
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The objective of this article is to establish a fatigue equation based on the true stress ratio for cement-treated aggregate base materials. The true stress ratio herein means the ratio of the stress and the true strength of the cement-treated aggregate base materials related to loading rates and curing times. The unconfined compressive strength tests and compressive resilience modulus tests were carried out under various loading rates and curing times of 3, 7, 14, 28, 60, 90 days, respectively. According to the test results, the relationship between the unconfined compressive strength (a mix design parameter in China) and the compressive resilience modulus (a structural design parameter and the construction quality control parameter in China) of the cement-treated aggregate base material with different curing times was established. However, it was found that the strengths varied with the loading rates, which is not reflected in the existing fatigue equations. Therefore, it is questionable to obtain the stress ratio of fatigue tests with a fixed strength value obtained from the standard strength test where the loading rate is fixed (in China, the fixed loading rate is 1 mm/min for cement-treated aggregate base materials). Thus, in this paper, the four-point bending strength (i.e., flexural strength) test was carried out at different loading rates to resolve such deficiencies. Based on the strength test results at different loading rates, the true stress ratio of the fatigue test corresponding to the fatigue loading rate can be calculated. Then the four-point bending fatigue test was conducted to establish an improved fatigue equation characterized by the true stress ratio. The results show that the patterns of variation for unconfined compressive strength increasing with the curing time were similar to that of the compressive resilience modulus. The fatigue equation curve based on the true stress ratio can be extended to the strength failure point of (1, 1), where both the true stress ratio and the fatigue life value are one. The internal relationship between the strength failure and the fatigue failure was unified. This article provides a theoretical method and basis for unifying the mix design parameters and the construction quality control parameters. Full article
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Open AccessArticle An Ultrasonic Through-Metal-Wall Power Transfer System with Regulated DC Output
Appl. Sci. 2018, 8(5), 692; https://doi.org/10.3390/app8050692
Received: 13 February 2018 / Revised: 22 April 2018 / Accepted: 26 April 2018 / Published: 29 April 2018
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Abstract
This paper presents a novel and efficient system capable of transmitting medium-power electric energy through a solid metal wall and generating a regulated direct current (DC) output. The electric power is transmitted using radio frequency (RF) ultrasound without physical penetration. An RF alternating
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This paper presents a novel and efficient system capable of transmitting medium-power electric energy through a solid metal wall and generating a regulated direct current (DC) output. The electric power is transmitted using radio frequency (RF) ultrasound without physical penetration. An RF alternating current to direct current converter with input impedance matching is used to convert the transmitted RF signal to a DC output, which is directly suitable as a power supply for electronic devices. The system is constructed from commercial off-the-shelf components, and a computer-controlled measurement method is designed to test the effectiveness of the full system. The measurement results show that the system is able to transfer power through a 40-mm-thick stainless steel plate and generate 5-V, 15.7-W regulated DC output power with an overall power transfer efficiency of 27.7%. In addition, the effectiveness of the system is successfully demonstrated by powering ARM® evaluation boards with liquid-crystal display panels. A discussion of potential enhancements that could be made to improve the transfer capability and efficiency of the system is also presented. This system could be applied to improve safety and preserve structural integrity in many industrial and military applications, such as submarines, space crafts, planes, nuclear storage facilities, etc. Full article
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Open AccessArticle Mechanical Construction and Propulsion Analysis of a Rescue Underwater Robot in the case of Drowning Persons
Appl. Sci. 2018, 8(5), 693; https://doi.org/10.3390/app8050693
Received: 13 February 2018 / Revised: 4 April 2018 / Accepted: 26 April 2018 / Published: 30 April 2018
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Abstract
This paper presents the design of an unmanned and tele-operated robotized life-saving system aimed to work as a recovery tool in case of water-related disasters. The device is designed to save people in distress in the water, either conscious or unconscious, without exposing
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This paper presents the design of an unmanned and tele-operated robotized life-saving system aimed to work as a recovery tool in case of water-related disasters. The device is designed to save people in distress in the water, either conscious or unconscious, without exposing the rescuer’s life to risk. The data of in water accidents show that the greatest number of casualties occurs because of dangerous predicaments conducted by people who want to save other lives. All present solutions are based on aerial, surface or submarine systems needing a crew and able to save only conscious people. This paper intends to fill this gap in the literature by analyzing the main critical issues in the design of a marine autonomous rescue vehicle in terms of performance, capabilities of maneuver in rough sea conditions and the costs. The proposed robot is fully electric and tele-manipulated, from the shore in case of accidents near dry land, or directly from boats or helicopters if drowning is occurring in the open sea. The paper demonstrates the feasibility of a system and its readiness for prototyping phases while presenting a trade-off and cost analysis between six different configurations as well as illustrating in detail the design of the selected layout. The motivations behind the choice of diving strategy to tackle rough sea conditions are described along with the design and the numerical validations of the hydroplane and propulsion systems. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Surface State Dynamics of Topological Insulators Investigated by Femtosecond Time- and Angle-Resolved Photoemission Spectroscopy
Appl. Sci. 2018, 8(5), 694; https://doi.org/10.3390/app8050694
Received: 11 April 2018 / Revised: 26 April 2018 / Accepted: 27 April 2018 / Published: 30 April 2018
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Abstract
Topological insulators (TI) are known for striking quantum phenomena associated with their spin-polarized topological surface state (TSS). The latter in particular forms a Dirac cone that bridges the energy gap between valence and conduction bands, providing a unique opportunity for prospective device applications.
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Topological insulators (TI) are known for striking quantum phenomena associated with their spin-polarized topological surface state (TSS). The latter in particular forms a Dirac cone that bridges the energy gap between valence and conduction bands, providing a unique opportunity for prospective device applications. In TI of the BixSb2−xTeySe3−y (BSTS) family, stoichiometry determines the morphology and position of the Dirac cone with respect to the Fermi level. In order to engineer specific transport properties, a careful tuning of the TSS is highly desired. Therefore, we have systematically explored BSTS samples with different stoichiometries by time- and angle-resolved photoemission spectroscopy (TARPES). This technique provides snapshots of the electronic structure and discloses the carrier dynamics in surface and bulk states, providing crucial information for the design of electro-spin current devices. Our results reveal the central role of doping level on the Dirac cone structure and its femtosecond dynamics. In particular, an extraordinarily long TSS lifetime is observed when the the vertex of the Dirac cone lies at the Fermi level. Full article
(This article belongs to the Special Issue Extreme Time Scale Photonics)
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Open AccessArticle Fault Detection in a Multistage Gearbox Based on a Hybrid Demodulation Method Using Modulation Intensity Distribution and Variational Mode Decomposition
Appl. Sci. 2018, 8(5), 696; https://doi.org/10.3390/app8050696
Received: 16 March 2018 / Revised: 22 April 2018 / Accepted: 27 April 2018 / Published: 1 May 2018
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Abstract
It is critical to detect hidden, periodically impulsive signatures caused by tooth defects in a gearbox. A hybrid demodulation method for detecting tooth defects has been developed in this work based on the variational mode decomposition algorithm combined with modulation intensity distribution. An
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It is critical to detect hidden, periodically impulsive signatures caused by tooth defects in a gearbox. A hybrid demodulation method for detecting tooth defects has been developed in this work based on the variational mode decomposition algorithm combined with modulation intensity distribution. An original multi-component signal is first non-recursively decomposed into a number of band-limited mono-components with specific sparsity properties in the spectral domain using variational mode decomposition. The hidden meaningful cyclostationary features can be clearly identified in the bi-frequency domain via the modulation intensity distribution (MID) technique. Moreover, the reduced frequency aliasing effect of variational mode decomposition is evaluated as well, which is very useful for separating noise and harmonic components in the original signal. The influences of the spectral coherence density and the spectral correlation density of the modulation intensity distribution on the demodulation were also investigated. The effectiveness and noise robustness of the proposed method have been well-verified using a simulated signal compared with the empirical mode decomposition algorithm associated with modulation intensity distribution. The proposed technique is then applied to detect four different defects in a multi-stage gearbox. The results demonstrated that the demodulated numerical information and pigmentation directly illustrated in the bi-frequency plot of the modulation intensity distribution can be successfully used to quantitatively differentiate the four gear defects. Full article
(This article belongs to the Special Issue Fault Detection and Diagnosis in Mechatronics Systems)
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Open AccessArticle Multi-Class Sleep Stage Analysis and Adaptive Pattern Recognition
Appl. Sci. 2018, 8(5), 697; https://doi.org/10.3390/app8050697
Received: 2 April 2018 / Revised: 26 April 2018 / Accepted: 27 April 2018 / Published: 1 May 2018
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Abstract
Multimodal signal analysis based on sophisticated sensors, efficient communication systems and fast parallel processing methods has a rapidly increasing range of multidisciplinary applications. The present paper is devoted to pattern recognition, machine learning, and the analysis of sleep stages in the detection of
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Multimodal signal analysis based on sophisticated sensors, efficient communication systems and fast parallel processing methods has a rapidly increasing range of multidisciplinary applications. The present paper is devoted to pattern recognition, machine learning, and the analysis of sleep stages in the detection of sleep disorders using polysomnography (PSG) data, including electroencephalography (EEG), breathing (Flow), and electro-oculogram (EOG) signals. The proposed method is based on the classification of selected features by a neural network system with sigmoidal and softmax transfer functions using Bayesian methods for the evaluation of the probabilities of the separate classes. The application is devoted to the analysis of the sleep stages of 184 individuals with different diagnoses, using EEG and further PSG signals. Data analysis points to an average increase of the length of the Wake stage by 2.7% per 10 years and a decrease of the length of the Rapid Eye Movement (REM) stages by 0.8% per 10 years. The mean classification accuracy for given sets of records and single EEG and multimodal features is 88.7% ( standard deviation, STD: 2.1) and 89.6% (STD:1.9), respectively. The proposed methods enable the use of adaptive learning processes for the detection and classification of health disorders based on prior specialist experience and man–machine interaction. Full article
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Open AccessArticle Predicting the Failure of Dental Implants Using Supervised Learning Techniques
Appl. Sci. 2018, 8(5), 698; https://doi.org/10.3390/app8050698
Received: 6 April 2018 / Revised: 26 April 2018 / Accepted: 27 April 2018 / Published: 2 May 2018
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Abstract
Prosthodontic treatment has been a crucial part of dental treatment for patients with full mouth rehabilitation. Dental implant surgeries that replace conventional dentures using titanium fixtures have become the top choice. However, because of the wide-ranging scope of implant surgeries, patients’ body conditions,
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Prosthodontic treatment has been a crucial part of dental treatment for patients with full mouth rehabilitation. Dental implant surgeries that replace conventional dentures using titanium fixtures have become the top choice. However, because of the wide-ranging scope of implant surgeries, patients’ body conditions, surgeons’ experience, and the choice of implant system should be considered during treatment. The higher price charged by dental implant treatments compared to conventional dentures has led to a rush among medical staff; therefore, the future impact of surgeries has not been analyzed in detail, resulting in medial disputes. Previous literature on the success factors of dental implants is mainly focused on single factors such as patients’ systemic diseases, operation methods, or prosthesis types for statistical correlation significance analysis. This study developed a prediction model for providing an early warning mechanism to reduce the chances of dental implant failure. We collected the clinical data of patients who received artificial dental implants at the case hospital for a total of 8 categories and 20 variables. Supervised learning techniques such as decision tree (DT), support vector machines, logistic regressions, and classifier ensembles (i.e., Bagging and AdaBoost) were used to analyze the prediction of the failure of dental implants. The results show that DT with both Bagging and Adaboost techniques possesses the highest prediction performance for the failure of dental implant (area under the receiver operating characteristic curve, AUC: 0.741); the analysis also revealed that the implant systems affect dental implant failure. The model can help clinical surgeons to reduce medical failures by choosing the optimal implant system and prosthodontics treatments for their patients. Full article
(This article belongs to the Special Issue Deep Learning and Big Data in Healthcare)
Open AccessArticle Vacuum Ultraviolet Single-Photon Postionization of Amino Acids
Appl. Sci. 2018, 8(5), 699; https://doi.org/10.3390/app8050699
Received: 29 March 2018 / Revised: 25 April 2018 / Accepted: 27 April 2018 / Published: 2 May 2018
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Abstract
In this study, ultraviolet (UV) laser desorption and vacuum UV single-photon (VUV SP) postionization were performed to ionize and successfully analyze 20 common amino acids. The analytical merit and efficiency of the ionization was compared with those of conventional UV matrix-assisted laser desorption
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In this study, ultraviolet (UV) laser desorption and vacuum UV single-photon (VUV SP) postionization were performed to ionize and successfully analyze 20 common amino acids. The analytical merit and efficiency of the ionization was compared with those of conventional UV matrix-assisted laser desorption ionization (UV-MALDI). A VUV light source (118 nm) was generated from the ninth harmonic of a Q-switched Nd:YAG laser, and the photon number was determined to be larger than 1012 for each laser pulse in the ionization region. In general, the detection sensitivity of VUV-SP-postionization was 10–100 times higher than that of conventional UV-MALDI. In particular, the ion signal from VUV-SP-postionization was considerably larger than that from UV-MALDI for analytes with low proton affinity such as glycine. However, some fragmentation of intact ions was observed in VUV-SP-postionization. Quantitative analysis performed using a glycine/histidine mixture and tryptophan/phenylalanine mixture revealed that the dynamic range of VUV-SP-postionization was one order of magnitude larger than that of UV-MALDI, indicating that VUV-SP-postionization is suitable for the quantitative analysis of amino acids. Full article
(This article belongs to the Special Issue Photoionization Mass Spectrometry)
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Open AccessArticle Time Dependence of Wetting Behavior Upon Applying Hierarchic Nano-Micro Periodic Surface Structures on Brass Using Ultra Short Laser Pulses
Appl. Sci. 2018, 8(5), 700; https://doi.org/10.3390/app8050700
Received: 28 March 2018 / Revised: 20 April 2018 / Accepted: 25 April 2018 / Published: 2 May 2018
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Abstract
We present a comprehensive experimental study on laser-induced hierarchic nano-micro periodic surface structures on brass that influences wetting behavior. Using ultra short laser pulses with a wavelength of 1030 nm, large scaled areas completely covered by laser-induced periodic surface structures (LIPSS) are generated
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We present a comprehensive experimental study on laser-induced hierarchic nano-micro periodic surface structures on brass that influences wetting behavior. Using ultra short laser pulses with a wavelength of 1030 nm, large scaled areas completely covered by laser-induced periodic surface structures (LIPSS) are generated with these areas being superimposed by ablation trenches and u-ripples. The influence of the incident laser fluence and pulse overlap on the apparent contact angle for coverage of the surface with distilled water with a surface tension of 74 mN/m are examined with its temporal evolution being observed over a period of two weeks. Our results show an initial drop in the apparent contact angle below the angle of an unstructured surface. Using atomic force microscopy, the roughness factor described by the Wenzel model is determined and compared to the roughness factor given by the apparent contact angle measurement. The ascertained difference in roughness cannot be entirely attributed to the topography of the laser-structured surface. We suggest that changes in the surface chemistry additionally alter the wetting behavior as confirmed by X-ray photoelectron spectroscopy (XPS) measurements. On a time scale of days after laser irradiation, the apparent contact angle increases into the hydrophobic range. Both the absolute apparent contact angle and this temporal change reveal a pronounced dependence on the applied laser fluence and pulse overlap. In particular, increasing both, the fluence and the pulse overlap leads to smaller apparent contact angles directly after the irradiation and to higher apparent contact angles after an observation period of two weeks. Full article
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Open AccessArticle Rapid and Quantitative Determination of Soil Water-Soluble Nitrogen Based on Surface-Enhanced Raman Spectroscopy Analysis
Appl. Sci. 2018, 8(5), 701; https://doi.org/10.3390/app8050701
Received: 9 March 2018 / Revised: 26 April 2018 / Accepted: 27 April 2018 / Published: 2 May 2018
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Abstract
An accurate and rapid determination of soil water-soluble nitrogen is conducive to scientific fertilization in precision agriculture. Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive fingerprint with the advantages of simple operation and high detection efficiency. In this paper, partial least squares (PLS),
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An accurate and rapid determination of soil water-soluble nitrogen is conducive to scientific fertilization in precision agriculture. Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive fingerprint with the advantages of simple operation and high detection efficiency. In this paper, partial least squares (PLS), principal components analysis (PCA), and least squares supports vector machine (LS-SVM) were applied to analyze the relationship between soil water-soluble nitrogen concentration and SERS. The results showed that the SERS-enhancing effect based on Opto Trace Raman 202 (OTR 202) was better than that of silver nanosubstrate and gold nanosubstrate. In addition, the prediction accuracy of soil water-soluble nitrogen in PLS was the highest ( R p 2 = 0.91 ,   RMSE p = 8.76   mg / L , R P D = 3.00 ) when the original spectra were preprocessed with first-derivative. Moreover, 1028, 1370, 1436, and 1636 cm−1 could be determined as characteristic peaks of soil water-soluble nitrogen, the association between soil water-soluble nitrogen concentration and a SERS intensity of 1370 cm−1 was the highest   ( R p 2 = 0.94 ) , and the regression equation was y = 93.491x + 1771.5. Beyond that, the prediction accuracy of distinguishing between a low soil water-soluble nitrogen concentration (22.7–63.7 mg/L) and a high soil water-soluble nitrogen concentration (70.5–118.3 mg/L) based on PCA and LS-LVM was 86.67%. In conclusion, soil water-soluble nitrogen could be detected rapidly and quantitatively using SERS, which was beneficial to provide a rapid, accurate, and reliable scheme for scientific and precise fertilization. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Virtual Diagnostic Sensors Design for an Automated Guided Vehicle
Appl. Sci. 2018, 8(5), 702; https://doi.org/10.3390/app8050702
Received: 13 March 2018 / Revised: 16 April 2018 / Accepted: 27 April 2018 / Published: 2 May 2018
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Abstract
In recent years, Automated Guided Vehicles (AGVs) have been playing an increasingly important role in producing industry and infrastructure and will soon arrive to other areas of human life such as the transportation of goods and people. However, several challenges still aggravate the
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In recent years, Automated Guided Vehicles (AGVs) have been playing an increasingly important role in producing industry and infrastructure and will soon arrive to other areas of human life such as the transportation of goods and people. However, several challenges still aggravate the operation of AGVs, which limit the amount of implementation. One major challenge is the realization of reliable sensors that can capture the different aspects of the state of an AGV as well as its surroundings. One promising approach towards more reliable sensors is the supplementary application of virtual sensors, which are able to generate virtual measurements by using other sources of information such as actuator states and already existing sensors together with appropriate mathematical models. The focus of the research described in this paper is the design of virtual sensors determining forces and torques acting on an AGV. The proposed novel approach is using a quadratic boundedness approach, which makes it possible to include bounded disturbances acting on the AGV. One major advantage of the presented approach is that the use of complex tire models can be avoided. Information from acceleration and yaw rate sensors is processed in order to realize reliable virtual force and torque sensors. The resulting force and torque information can be used for several diagnostic purposes such as fault detection or fault prevention. The presented approach is explained and verified on the basis of an innovative design of an AGV. This innovative design addresses another major challenge for AGVs, which is the limited maneuvering possibilities of many AGV designs. The innovative design allows nearly unlimited maneuvering possibilities but requires reliable sensor data. The application of the approach in the AGV resulted in the insight that the generated estimates are consistent with the longitudinal forces and torques obtained by a proven reference model. Full article
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Open AccessArticle Vibrometry Assessment of the External Thermal Composite Insulation Systems Influence on the Façade Airborne Sound Insulation
Appl. Sci. 2018, 8(5), 703; https://doi.org/10.3390/app8050703
Received: 21 February 2018 / Revised: 26 March 2018 / Accepted: 30 March 2018 / Published: 2 May 2018
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Abstract
This paper verifies the impact of the use of an external thermal composite system (ETICS) on air-borne sound insulation. For optimum accuracy over a wide frequency range, classical microphone based transmission measurements are combined with accelerometer based vibrometry measurements. Consistency is found between
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This paper verifies the impact of the use of an external thermal composite system (ETICS) on air-borne sound insulation. For optimum accuracy over a wide frequency range, classical microphone based transmission measurements are combined with accelerometer based vibrometry measurements. Consistency is found between structural resonance frequencies and bending wave velocity dispersion curves determined by vibrometry on the one hand and spectral features of the sound reduction index, the ETICS mass-spring-mass resonance induced dip in the acoustic insulation spectrum, and the coincidence induced dip on the other hand. Scanning vibrometry proves to be an effective tool for structural assessment in the design phase of ETICS systems. The measured spectra are obtained with high resolution in wide frequency range, and yield sound insulation values are not affected by the room acoustic features of the laboratory transmission rooms. The complementarity between the microphone and accelerometer based results allows assessing the effect of ETICS on the sound insulation spectrum in an extended frequency range from 20 Hz to 10 kHz. The modified engineering ΔR prediction model for frequency range up to coincidence frequency of external plaster layer is recommended. Values for the sound reduction index obtained by a modified prediction method are consistent with the measured data. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle User-In-The-Loop Content Delivery in Cellular Communication Networks with Heterogeneous User Behaviors
Appl. Sci. 2018, 8(5), 704; https://doi.org/10.3390/app8050704
Received: 25 March 2018 / Revised: 23 April 2018 / Accepted: 23 April 2018 / Published: 2 May 2018
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Abstract
User-in-the-loop (UiL) content delivery is a recently proposed scheme for personalized content retrieval over mobile communication networks. It is a promising scheme that can better manage the overall user quality-of-experience (QoE) throughout the entire content retrieval process. The performance of the scheme, however,
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User-in-the-loop (UiL) content delivery is a recently proposed scheme for personalized content retrieval over mobile communication networks. It is a promising scheme that can better manage the overall user quality-of-experience (QoE) throughout the entire content retrieval process. The performance of the scheme, however, has only been investigated in a simplified system model that assumed synchronized user behavior, inflexible delay constraint, and identical quality-of-service (QoS) requirement among users. This paper studies the performance of UiL content delivery scheme in a generalized and realistic system model with asynchronous user behavior, flexible outage delay constraint, and customized user QoS. Heuristic algorithms and theoretical bounds are investigated for the UiL content delivery problem. The proposed system is shown to be effective in managing the user QoE in generalized practical scenarios. Full article
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Open AccessArticle Numerical Simulation of Temperature Fields in a Three-Dimensional SiC Crystal Growth Furnace with Axisymmetric and Spiral Coils
Appl. Sci. 2018, 8(5), 705; https://doi.org/10.3390/app8050705
Received: 9 April 2018 / Revised: 20 April 2018 / Accepted: 20 April 2018 / Published: 2 May 2018
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Abstract
Three-dimensional numerical simulation platform for silicon carbide crystal growth furnace was established using C programing language, where a physical model of the furnace was built based on cylindrical coordinates; governing equations for electromagnetic and temperature fields were discretized by finite volume method; radiation
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Three-dimensional numerical simulation platform for silicon carbide crystal growth furnace was established using C programing language, where a physical model of the furnace was built based on cylindrical coordinates; governing equations for electromagnetic and temperature fields were discretized by finite volume method; radiation characteristics were studied with the help of S2S model (surface to surface radiation model); and the least distance method was proposed to check radiation faces visibility efficiently. LU decomposition algorithm based on graphic processing unit (GPU) technology was developed to accelerate the solving process of surface to surface radiation. Then the radiation heat transfer in silicon carbide crystal (SiC) growth chamber and temperature field of silicon carbide growth furnace were studied quantificationally at I = 1250 A and F = 16 kHz. The effects of coil structures (axisymmetric and spiral) on temperature field and its gradient distributions were investigated by standard deviation method. The simulation results demonstrate that spiral electromagnetic coil generates non-axisymmetric temperature field easily; the radiation heat flux is 102~103 times more than conduction heat flux, radiation heat transfer is helpful to increase temperature evenness; the spiral temperature field on the SiC crystal cross-section reduces the poor homogeneity of temperature gradient, which will cause crystal to generate large defects. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Calibrated Phase-Shifting Digital Holographic Microscope Using a Sampling Moiré Technique
Appl. Sci. 2018, 8(5), 706; https://doi.org/10.3390/app8050706
Received: 31 March 2018 / Revised: 18 April 2018 / Accepted: 27 April 2018 / Published: 3 May 2018
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Abstract
A calibrated phase-shifting digital holographic microscope system capable of improving the quality of reconstructed images is proposed. Phase-shifting errors are introduced in phase-shifted holograms for numerous reasons, such as the non-linearity of piezoelectric transducers (PZTs), wavelength fluctuations in lasers, and environmental disturbances, leading
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A calibrated phase-shifting digital holographic microscope system capable of improving the quality of reconstructed images is proposed. Phase-shifting errors are introduced in phase-shifted holograms for numerous reasons, such as the non-linearity of piezoelectric transducers (PZTs), wavelength fluctuations in lasers, and environmental disturbances, leading to poor-quality reconstructions. In our system, in addition to the camera used to record object information, an extra camera is used to record interferograms, which are used to analyze phase-shifting errors using a sampling Moiré technique. The quality of the reconstructed object images can be improved by the phase-shifting error compensation algorithm. Both the numerical simulation and experiment demonstrate the effectiveness of the proposed system. Full article
(This article belongs to the Special Issue Applications of Digital Holographic Microscopy)
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Open AccessArticle Real-Time Estimation for Cutting Tool Wear Based on Modal Analysis of Monitored Signals
Appl. Sci. 2018, 8(5), 708; https://doi.org/10.3390/app8050708
Received: 23 March 2018 / Revised: 27 April 2018 / Accepted: 27 April 2018 / Published: 3 May 2018
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Abstract
There is a growing body of literature that recognizes the importance of product safety and the quality problems during processing. The working status of cutting tools may lead to project delay and cost overrun if broken down accidentally, and tool wear is crucial
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There is a growing body of literature that recognizes the importance of product safety and the quality problems during processing. The working status of cutting tools may lead to project delay and cost overrun if broken down accidentally, and tool wear is crucial to processing precision in mechanical manufacturing, therefore, this study contributes to this growing area of research by monitoring condition and estimating wear. In this research, an effective method for tool wear estimation was constructed, in which, the signal features of machining process were extracted by ensemble empirical mode decomposition (EEMD) and were used to estimate the tool wear. Based on signal analysis, vibration signals that had better linear relationship with tool wearing process were decomposed, then the intrinsic mode functions (IMFs), frequency spectrums of IMFs and the features relating to amplitude changes of frequency spectrum were obtained. The trend that tool wear changes with the features was fitted by Gaussian fitting function to estimate the tool wear. Experimental investigation was used to verify the effectiveness of this method and the results illustrated the correlation between tool wear and the modal features of monitored signals. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Optic Disc Detection from Fundus Photography via Best-Buddies Similarity
Appl. Sci. 2018, 8(5), 709; https://doi.org/10.3390/app8050709
Received: 22 March 2018 / Revised: 19 April 2018 / Accepted: 25 April 2018 / Published: 3 May 2018
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Abstract
Robust and effective optic disc (OD) detection is a necessary processing step in the research work of the automatic analysis of fundus images. In this paper, we propose a novel and robust method for the automated detection of ODs from fundus photographs. It
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Robust and effective optic disc (OD) detection is a necessary processing step in the research work of the automatic analysis of fundus images. In this paper, we propose a novel and robust method for the automated detection of ODs from fundus photographs. It is essentially carried out by performing template matching using the Best-Buddies Similarity (BBS) measure between the hand-marked OD region and the small parts of target images. For well characterizing the local spatial information of fundus images, a gradient constraint term was introduced for computing the BBS measurement. The performance of the proposed method is validated with Digital Retinal Images for Vessel Extraction (DRIVE) and Standard Diabetic Retinopathy Database Calibration Level 1 (DIARETDB1) databases, and quantitative results were obtained. Success rates/error distances of 100%/10.4 pixel and of 97.7%/12.9 pixel, respectively, were achieved. The algorithm has been tested and compared with other commonly used methods, and the results show that the proposed method shows superior performance. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Development of a Combined Trifluoroacetic Acid Hydrolysis and HPLC-ELSD Method to Identify and Quantify Inulin Recovered from Jerusalem artichoke Assisted by Ultrasound Extraction
Appl. Sci. 2018, 8(5), 710; https://doi.org/10.3390/app8050710
Received: 26 March 2018 / Revised: 12 April 2018 / Accepted: 2 May 2018 / Published: 3 May 2018
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Abstract
Over the last years, inulin, a fructan mixture consisting of oligosaccharides and polysaccharides, has attracted more and more attention from both food industry and researchers, due to its unique functional properties as a natural resource. Therefore, there is an increased interest in the
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Over the last years, inulin, a fructan mixture consisting of oligosaccharides and polysaccharides, has attracted more and more attention from both food industry and researchers, due to its unique functional properties as a natural resource. Therefore, there is an increased interest in the extraction and quantification of inulin for its valorization from inulin rich plants, wastes and by-products. In this work, ultrasonic treatment was applied for inulin extraction, observing a great impact of extraction temperature and ultrasonic power on the inulin content in the obtained extracts. A combined process including trifluoroacetic acid (TFA)-assisted hydrolysis and analysis with high performance liquid chromatography equipped with evaporative light scattering detector (HPLC-ELSD) was developed to quantify inulin content. The effect of hydrolysis parameters was investigated, obtaining the optimal conditions after using TFA at a concentration of 1 mg/mL, hydrolysis temperature of 90 °C, and hydrolysis duration of 60 min. The good linearity (>0.995), precision, recovery (100.27%), and stability obtained during the validation process showed that this developed method allows the quantification of total inulin content in the samples analyzed. This combined method may also contribute to the investigation of the functional properties of inulin (e.g., as prebiotic). Full article
(This article belongs to the Special Issue Acoustic and Hydrodynamic Effects in Food Processing)
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Open AccessArticle Comparison of Heuristic Algorithms in Discrete Search and Surveillance Tasks Using Aerial Swarms
Appl. Sci. 2018, 8(5), 711; https://doi.org/10.3390/app8050711
Received: 24 March 2018 / Revised: 24 April 2018 / Accepted: 2 May 2018 / Published: 3 May 2018
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Abstract
The search of a given area is one of the most studied tasks in swarm robotics. Different heuristic methods have been studied in the past taking into account the peculiarities of these systems (number of robots, limited communications and sensing and computational capacities).
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The search of a given area is one of the most studied tasks in swarm robotics. Different heuristic methods have been studied in the past taking into account the peculiarities of these systems (number of robots, limited communications and sensing and computational capacities). In this work, we introduce a behavioral network made up of different well-known behaviors that act together to achieve a good performance, while adapting to different scenarios. The algorithm is compared with six strategies based on movement patterns in terms of three performance models. For the comparison, four scenario types are considered: plain, with obstacles, with the target location probability distribution and a combination of obstacles and the target location probability distribution. For each scenario type, different variations are considered, such as the number of agents and area size. Results show that although simplistic solutions may be convenient for the simplest scenario type, for the more complex ones, the proposed algorithm achieves better results. Full article
(This article belongs to the Special Issue Swarm Robotics)
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