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Appl. Sci., Volume 7, Issue 11 (November 2017)

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Editorial

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Open AccessFeature PaperEditorial Smart Healthcare
Appl. Sci. 2017, 7(11), 1176; doi:10.3390/app7111176
Received: 13 November 2017 / Revised: 14 November 2017 / Accepted: 14 November 2017 / Published: 15 November 2017
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Abstract
Medicine is undergoing a sector-wide transformation thanks to the advances in computing and networking technologies [...]
Full article
(This article belongs to the Special Issue Smart Healthcare)

Research

Jump to: Editorial, Review, Other

Open AccessArticle The Dynamic Optimization of the Departure Times of Metro Users during Rush Hour in an Agent-Based Simulation: A Case Study in Shenzhen, China
Appl. Sci. 2017, 7(11), 1102; doi:10.3390/app7111102
Received: 13 September 2017 / Accepted: 18 October 2017 / Published: 25 October 2017
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Abstract
As serious traffic problems have increased throughout the world, various types of studies, especially traffic simulations, have been conducted to investigate this issue. Activity-based traffic simulation models, such as MATSim (Multi-Agent Transport Simulation), are intended to identify optimal combinations of activities in time
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As serious traffic problems have increased throughout the world, various types of studies, especially traffic simulations, have been conducted to investigate this issue. Activity-based traffic simulation models, such as MATSim (Multi-Agent Transport Simulation), are intended to identify optimal combinations of activities in time and space. It is also necessary to examine commuting-based traffic simulations. Such simulations focus on optimizing travel times by adjusting departure times, travel modes or travel routes to present travel suggestions to the public. This paper examines the optimal departure times of metro users during rush hour using a newly developed simulation tool. A strategy for identifying relatively optimal departure times is identified. This study examines 103,637 person agents (passengers) in Shenzhen, China, and reports their average departure time, travel time and travel utility, as well as the numbers of person agents who are late and miss metro trips in every iteration. The results demonstrate that as the number of iterations increases, the average travel time of these person agents decreases by approximately 4 min. Moreover, the latest average departure time with no risk of being late when going to work is approximately 8:04, and the earliest average departure time with no risk of missing metro trips when getting off work is approximately 17:50. Full article
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Open AccessArticle Shear Wave Elastography Combining with Conventional Grey Scale Ultrasound Improves the Diagnostic Accuracy in Differentiating Benign and Malignant Thyroid Nodules
Appl. Sci. 2017, 7(11), 1103; doi:10.3390/app7111103
Received: 11 September 2017 / Revised: 30 September 2017 / Accepted: 13 October 2017 / Published: 25 October 2017
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Abstract
Shear wave elastography provides information about the stiffness of thyroid nodules that could be a new indicator of malignancy. The current study aimed to investigate the feasibility of using shear wave elastography (SWE) alone and in conjunction with grey scale ultrasound (GSU) to
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Shear wave elastography provides information about the stiffness of thyroid nodules that could be a new indicator of malignancy. The current study aimed to investigate the feasibility of using shear wave elastography (SWE) alone and in conjunction with grey scale ultrasound (GSU) to predict malignancy in 111 solitary thyroid nodules. Malignant thyroid nodules tended to have microcalcification, hypoechogenicity, tall to width ratio >1, and irregular borders (p < 0.05). SWE indices (Emaximum and Emean) of malignant nodules (median ± standard error: 85.2 ± 8.1 kPa and 26.6 ± 2.5 kPa) were significantly higher than those of benign nodules (median ± standard error: 50.3 ± 3.1 kPa and 20.2 ± 1 kPa) (p < 0.05). The optimal cut-off of Emaximum and Emean for distinguishing benign and malignant nodules was 67.3 kPa and 23.1 kPa, respectively. Diagnostic performances for GSU + Emaximum, GSU + Emean, GSU, Emaximum and Emean were: 70.4%, 74.1%, 96.3%, 70.4% and 74.1% for sensitivity, 83.3%, 79.8%, 46.4%, 70.2%, and 66.7% for specificity, and 80.2%, 78.4%, 58.5%, 70.3%, and 68.5% for accuracy, respectively. Our results suggested that combining GSU with SWE (using Emaximum or Emean) increased the overall diagnostic accuracy in distinguishing benign and malignant thyroid nodules. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Technologies and Principles of Hot Recycling and Investigation of Preheated Reclaimed Asphalt Pavement Batching Process in an Asphalt Mixing Plant
Appl. Sci. 2017, 7(11), 1104; doi:10.3390/app7111104
Received: 18 September 2017 / Accepted: 23 October 2017 / Published: 25 October 2017
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Abstract
More and more recycled asphalt mixtures with high reclaimed asphalt pavement (RAP) content are used in road pavement. Having determined and evaluated RAP composition (aged bitumen content and aggregate gradation) and properties, a suitable recycling agent and virgin materials are selected in the
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More and more recycled asphalt mixtures with high reclaimed asphalt pavement (RAP) content are used in road pavement. Having determined and evaluated RAP composition (aged bitumen content and aggregate gradation) and properties, a suitable recycling agent and virgin materials are selected in the design process. The gradation of hot mix asphalt (HMA) mixture that is recycled in an asphalt mixing plant (AMP) shall correspond to its optimal gradation set out in its job-mix formula (JMF). When RAP is recycled in an AMP, inevitable systematic and random errors of performed technological operations and inhomogeneity of virgin materials and RAP have a significant influence. These factors influence the variation of components quantities of recycled hot mix asphalt (RHMA) mixture and deviations from JMF. In this study, the principles of asphalt pavement hot recycling are systematized, which allows analysis of the factors of components’ interaction influencing the results of the recycling process. The paper also presents and analyses asphalt recycling technologies in AMP and their comparative analysis. During the season of asphalt mixture production in 2014, statistical parameters were calculated according to the data obtained from one of the companies, which collected and systematized RAP batch masses, when before batching it was pre-dried and pre-heated in an additional dryer. These parameters of batch mass and RAP content in RHMA position and variation were used when evaluating the accuracy and precision of the recycling process in AMP. The obtained data showed that when RHMA mixtures are produced in a modern batch-type AMP, RAP is batched accurately, but not precisely enough. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Settlement Prediction of Footings Using VS
Appl. Sci. 2017, 7(11), 1105; doi:10.3390/app7111105
Received: 29 September 2017 / Revised: 17 October 2017 / Accepted: 23 October 2017 / Published: 25 October 2017
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Abstract
The shear wave velocity (VS) is a key parameter for estimating the deformation characteristics of soil. In order to predict the settlement of shallow footings in granular soil, the VS and the concept of Schmertmann’s framework were adopted. The
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The shear wave velocity (VS) is a key parameter for estimating the deformation characteristics of soil. In order to predict the settlement of shallow footings in granular soil, the VS and the concept of Schmertmann’s framework were adopted. The VS was utilized to represent soil stiffness instead of cone tip resistance (qc) because the VS can be directly related to the small-strain shear modulus. By combining the VS measured in the field and the modulus reduction curve measured in the laboratory, the deformation characteristics of soil can be reliably estimated. Vertical stress increments were determined using two different profiles of the strain influence factor (Iz) proposed in Schmertmann’s method and that calculated from the theory of elasticity. The corresponding modulus variation was determined by considering the stress level and strain at each depth. This state-dependent stress-strain relationship was utilized to calculate the settlement of footings based on the theory of elasticity. To verify the developed method, geotechnical centrifuge tests were carried out. The VS profiles were measured before each loading test, and the load-settlement curves were obtained during the tests. Comparisons between the measured and estimated load-settlement curves showed that the developed method adequately predicts the settlement of footings, especially for over-consolidated ground conditions. Full article
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Open AccessArticle A Hardware-Efficient Vector Quantizer Based on Self-Organizing Map for High-Speed Image Compression
Appl. Sci. 2017, 7(11), 1106; doi:10.3390/app7111106
Received: 28 September 2017 / Revised: 22 October 2017 / Accepted: 24 October 2017 / Published: 25 October 2017
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Abstract
This paper presents a compact vector quantizer based on the self-organizing map (SOM), which can fulfill the data compression task for high-speed image sequence. In this vector quantizer, we solve the most severe computational demands in the codebook learning mode and the image
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This paper presents a compact vector quantizer based on the self-organizing map (SOM), which can fulfill the data compression task for high-speed image sequence. In this vector quantizer, we solve the most severe computational demands in the codebook learning mode and the image encoding mode by a reconfigurable complete-binary-adder-tree (RCBAT), where the arithmetic units are thoroughly reused. In this way, the hardware efficiency of our proposed vector quantizer is greatly improved. In addition, by distributing the codebook into the multi-parallel processing sub-blocks, our design obtains a high compression speed successfully. Furthermore, a mechanism of partial vector-component storage (PVCS) is adopted to make the compression ratio adjustable. Finally, the proposed vector quantizer has been implemented on the field programmable gate array (FPGA). The experimental results indicate that it respectively achieves a compression speed of 500 frames/s and a million connections per second (MCPS) of 28,494 (compression ratio is 64) when working at 79.8 MHz. Besides, compared with the previous scheme, our proposed quantizer achieves a reduction of 8% in hardware usage and an increase of 33% in compression speed. This means the proposed quantizer is hardware-efficient and can be used for high-speed image compression. Full article
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Open AccessArticle Thermal and Performance Analysis of a Photovoltaic Module with an Integrated Energy Storage System
Appl. Sci. 2017, 7(11), 1107; doi:10.3390/app7111107
Received: 19 September 2017 / Revised: 18 October 2017 / Accepted: 23 October 2017 / Published: 25 October 2017
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Abstract
This paper is proposing and analyzing an electric energy storage system fully integrated with a photovoltaic PV module, composed by a set of lithium-iron-phosphate (LiFePO4) flat batteries, which constitutes a generation-storage PV unit. The batteries were surface-mounted on the back side
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This paper is proposing and analyzing an electric energy storage system fully integrated with a photovoltaic PV module, composed by a set of lithium-iron-phosphate (LiFePO4) flat batteries, which constitutes a generation-storage PV unit. The batteries were surface-mounted on the back side of the PV module, distant from the PV backsheet, without exceeding the PV frame size. An additional low-emissivity sheet was introduced to shield the batteries from the backsheet thermal irradiance. The challenge addressed in this paper is to evaluate the PV cell temperature increase, due to the reduced thermal exchanges on the back of the module, and to estimate the temperature of the batteries, verifying their thermal constraints. Two one-dimensional (1D) thermal models, numerically implemented by using the thermal library of Simulink-Matlab accounting for all the heat exchanges, are here proposed: one related to the original PV module, the other related to the portion of the area of the PV module in correspondence of the proposed energy-storage system. Convective and radiative coefficients were then calculated in relation to different configurations and ambient conditions. The model validation has been carried out considering the PV module to be at the nominal operating cell temperature (NOCT), and by specific experimental measurements with a thermographic camera. Finally, appropriate models were used to evaluate the increasing cell batteries temperature in different environmental conditions. Full article
(This article belongs to the Special Issue Computational Intelligence in Photovoltaic Systems)
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Open AccessArticle Low Reynolds Number Flow Around Tori of Different Slenderness Γ
Appl. Sci. 2017, 7(11), 1108; doi:10.3390/app7111108
Received: 25 September 2017 / Accepted: 20 October 2017 / Published: 26 October 2017
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Abstract
We present the results of axisymmetric and three-dimensional numerical simulations of the flow around a torus in the low Reynolds number regime [102; 3×103] and aspect-ratio 0<Γ=2a/R
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We present the results of axisymmetric and three-dimensional numerical simulations of the flow around a torus in the low Reynolds number regime [ 10 2 ; 3 × 10 3 ] and aspect-ratio 0 < Γ = 2 a / R 2 (core diameter over toroidal radius). It is shown that as Γ 0 , consistent with intuition and the results from the literature, the flow tends to that of a two-dimensional circular cylinder while for Γ 2 the flow is that around a bluff obstacle. It has been observed that in a small region of the R e Γ phase space, the flow develops an axisymmetric recirculation detached from the torus and with a vorticity distribution that resembles the Hill vortex. In the range 0 < Γ 2 , several different regimes have been observed; the peculiarities of each regime are analyzed and, whenever possible, similarities and differences with other classical flows are discussed. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Synthesis and Electroluminescence Properties of 3-(Trifluoromethyl)phenyl-Substituted 9,10-Diarylanthracene Derivatives for Blue Organic Light-Emitting Diodes
Appl. Sci. 2017, 7(11), 1109; doi:10.3390/app7111109
Received: 28 September 2017 / Revised: 12 October 2017 / Accepted: 23 October 2017 / Published: 26 October 2017
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Abstract
Diaryl-substituted anthracene derivatives containing 3-(trifluoromethyl)phenyl) groups, 9,10-diphenyl-2-(3-(trifluoromethyl)phenyl)anthracene (1), 9,10-di([1,1′-biphenyl]-4-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (2), and 9,10-di(naphthalen-2-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (3) were synthesized and characterized. The compounds 13 possessed high thermal stability and proper frontier-energy levels, which make them suitable as host materials
[...] Read more.
Diaryl-substituted anthracene derivatives containing 3-(trifluoromethyl)phenyl) groups, 9,10-diphenyl-2-(3-(trifluoromethyl)phenyl)anthracene (1), 9,10-di([1,1′-biphenyl]-4-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (2), and 9,10-di(naphthalen-2-yl)-2-(3-(trifluoromethyl)phenyl)anthracene (3) were synthesized and characterized. The compounds 13 possessed high thermal stability and proper frontier-energy levels, which make them suitable as host materials for blue organic light-emitting diodes. The electroluminescent (EL) emission maximum of the three N,N-diphenylamino phenyl vinyl biphenyl (DPAVBi)-doped (8 wt %) devices for compounds 13 was exhibited at 488 nm (for 1) and 512 nm (for 2 and 3). Among them, the 1-based device displayed the highest device performances in terms of brightness (Lmax = 2153.5 cd·m−2), current efficiency (2.1 cd·A−1), and external quantum efficiency (0.8%), compared to the 2- and 3-based devices. Full article
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Open AccessArticle Soil Dynamic Constitutive Model for Characterizing the Nonlinear-Hysteretic Response
Appl. Sci. 2017, 7(11), 1110; doi:10.3390/app7111110
Received: 6 October 2017 / Revised: 24 October 2017 / Accepted: 24 October 2017 / Published: 27 October 2017
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Abstract
Characterization of nonlinear hysteretic responses plays a significant role in predicting soil behaviors. They are mostly described with either simple empirical functions or complex constitutive models. However, the input parameters lack both a physical basis and robustness, and the use of these models
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Characterization of nonlinear hysteretic responses plays a significant role in predicting soil behaviors. They are mostly described with either simple empirical functions or complex constitutive models. However, the input parameters lack both a physical basis and robustness, and the use of these models is limited to some typical soils. Therefore, there is a need for a simple but robust model that uses only a small number of physically meaningful parameters. This study proposes explicit formulas to capture different nonlinear hysteretic soil responses, including a constitutive model, backbone curve, tangent shear modulus, secant shear modulus, and damping ratio. In particular, the Davidenkov model, with two physically meaningful parameters, is adopted to assess the constitutive relationships of soils under steady-state cyclic loading. The proposed models are validated with resonant column test (RCT) data (shear modulus and damping ratio). This paper finds that the use of the linear characteristic equation to calculate the shear modulus from the resonance frequency in the RCT, which is clearly irrelevant and approximate, produces data interpretation errors. Full article
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Open AccessArticle N-Type Semiconducting Behavior of Copper Octafluorophthalocyanine in an Organic Field-Effect Transistor
Appl. Sci. 2017, 7(11), 1111; doi:10.3390/app7111111
Received: 14 September 2017 / Revised: 13 October 2017 / Accepted: 25 October 2017 / Published: 27 October 2017
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Abstract
Based on the crystal structure analysis, the overlap integral between the frontier molecular orbitals of adjacent F8CuPcs in the one-dimensional chain is estimated: the overlap integral between the lowest unoccupied molecular orbitals is 5.4 × 10−3, which is larger
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Based on the crystal structure analysis, the overlap integral between the frontier molecular orbitals of adjacent F8CuPcs in the one-dimensional chain is estimated: the overlap integral between the lowest unoccupied molecular orbitals is 5.4 × 10−3, which is larger than that in a typical n-type semiconducing material F16CuPc (2.1 × 10−3), whereas that between the highest occupied molecular orbitals is 2.9 × 10−4. Contrary to previous studies in air, we found that an organic field-effect transistor (OFET) composed of F8CuPc essentially shows clear n-type semiconducting behavior in vacuum. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Model-Based Requirements Management in Gear Systems Design Based On Graph-Based Design Languages
Appl. Sci. 2017, 7(11), 1112; doi:10.3390/app7111112
Received: 30 August 2017 / Revised: 20 October 2017 / Accepted: 25 October 2017 / Published: 27 October 2017
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Abstract
For several decades, a wide-spread consensus concerning the enormous importance of an in-depth clarification of the specifications of a product has been observed. A weak clarification of specifications is repeatedly listed as a main cause for the failure of product development projects. Requirements,
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For several decades, a wide-spread consensus concerning the enormous importance of an in-depth clarification of the specifications of a product has been observed. A weak clarification of specifications is repeatedly listed as a main cause for the failure of product development projects. Requirements, which can be defined as the purpose, goals, constraints, and criteria associated with a product development project, play a central role in the clarification of specifications. The collection of activities which ensure that requirements are identified, documented, maintained, communicated, and traced throughout the life cycle of a system, product, or service can be referred to as “requirements engineering”. These activities can be supported by a collection and combination of strategies, methods, and tools which are appropriate for the clarification of specifications. Numerous publications describe the strategy and the components of requirements management. Furthermore, recent research investigates its industrial application. Simultaneously, promising developments of graph-based design languages for a holistic digital representation of the product life cycle are presented. Current developments realize graph-based languages by the diagrams of the Unified Modelling Language (UML), and allow the automatic generation and evaluation of multiple product variants. The research presented in this paper seeks to present a method in order to combine the advantages of a conscious requirements management process and graph-based design languages. Consequently, the main objective of this paper is the investigation of a model-based integration of requirements in a product development process by means of graph-based design languages. The research method is based on an in-depth analysis of an exemplary industrial product development, a gear system for so-called “Electrical Multiple Units” (EMU). Important requirements were abstracted from a gear system specification list and were analyzed in detail. As a second basis, the research method uses a conscious expansion of graph-based design languages towards their applicability for requirements management. This expansion allows the handling of requirements through a graph-based design language model. The first two results of the presented research consist of a model of the gear system and a detailed model of requirements, both modelled in a graph-based design language. Further results are generated by a combination of the two models into one holistic model. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Applied Engineering Using Schumann Resonance for Earthquakes Monitoring
Appl. Sci. 2017, 7(11), 1113; doi:10.3390/app7111113
Received: 14 September 2017 / Revised: 19 October 2017 / Accepted: 25 October 2017 / Published: 27 October 2017
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Abstract
For populations that may be affected, the risks of earthquakes and tsunamis are a major concern worldwide. Therefore, early detection of an event of this type in good time is of the highest priority. The observatories that are capable of detecting Extremely Low
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For populations that may be affected, the risks of earthquakes and tsunamis are a major concern worldwide. Therefore, early detection of an event of this type in good time is of the highest priority. The observatories that are capable of detecting Extremely Low Frequency (ELF) waves (<300 Hz) today represent a breakthrough in the early detection and study of such phenomena. In this work, all earthquakes with tsunami associated in history and all existing ELF wave observatories currently located worldwide are represented. It was also noticed how the southern hemisphere lacks coverage in this matter. In this work, the most suitable locations are proposed to cover these geographical areas. Also, ELF data processed obtained from the observatory of the University of Almeria in Calar Alto, Spain are shown. This is a contribution to help protect against natural disasters such as those caused by earthquakes and tsunamis. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle The FLASH Facility: Advanced Options for FLASH2 and Future Perspectives
Appl. Sci. 2017, 7(11), 1114; doi:10.3390/app7111114
Received: 10 September 2017 / Revised: 13 October 2017 / Accepted: 16 October 2017 / Published: 28 October 2017
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Abstract
Since 2016, the two free-electron laser (FEL) lines FLASH1 and FLASH2 have been run simultaneously for users at DESY in Hamburg. With the installation of variable gap undulators in the new FLASH2 FEL line, many new possibilities have opened up in terms of
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Since 2016, the two free-electron laser (FEL) lines FLASH1 and FLASH2 have been run simultaneously for users at DESY in Hamburg. With the installation of variable gap undulators in the new FLASH2 FEL line, many new possibilities have opened up in terms of photon parameters for experiments. What has been tested so far is post-saturation tapering, reverse tapering, harmonic lasing, harmonic lasing self-seeding and two-color lasing. At the moment, we are working on concepts to enhance the capabilities of the FLASH facility even further. A major part of the upgrade plans, known as FLASH2020, will involve the exchange of the fixed gap undulators in FLASH1 and the implementation of a new flexible undulator scheme aimed at providing coherent radiation for multi-color experiments over a broad wavelength range. The recent achievements in FLASH2 and the current status of plans for the further development of the facility are presented. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle Preparation of the Nanostructured Radioisotope Metallic Oxide by Neutron Irradiation for Use as Radiotracers
Appl. Sci. 2017, 7(11), 1115; doi:10.3390/app7111115
Received: 18 September 2017 / Revised: 19 October 2017 / Accepted: 23 October 2017 / Published: 28 October 2017
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Abstract
Metallic oxides manganese dioxide (MnO2), samarium oxide (Sm2O3), and dysprosium oxide (Dy2O3) with nanorod-like structures were synthesized by the hydrothermal synthesis method, respectively. Subsequently, the nanostructured radioisotopes MnO2 with Mn-56, Sm2
[...] Read more.
Metallic oxides manganese dioxide (MnO2), samarium oxide (Sm2O3), and dysprosium oxide (Dy2O3) with nanorod-like structures were synthesized by the hydrothermal synthesis method, respectively. Subsequently, the nanostructured radioisotopes MnO2 with Mn-56, Sm2O3 with Sm-153, and Dy2O3 with Dy-165 were prepared by neutron irradiation from the HANARO research reactor, respectively. The three different elements, Mn, Sm, and Dy, were selected as radiotracers because these elements can be easily gamma-activated from neutrons (activation limits: 1 picogram (Dy), 1–10 picogram (Mn), 10–100 picogram (Sm)). Furthermore, the synthesized radioisotopes can be used as radiotracers in Prompt Gamma Neutron Activation Analysis as the rare earth metals Dy and Sm were not present in the Korean environment. The successful synthesis of the radioisotope metallic oxides was confirmed by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectrometry (EDS), X-ray Diffraction (XRD) analysis, and gamma spectroscopy analysis. The synthesized nanostructured radioisotope metallic oxides may be used as radiotracers in scientific, environmental, engineering, and industrial fields. Full article
(This article belongs to the Section Chemistry)
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Open AccessFeature PaperArticle Multi-Layer Metallization Structure Development for Highly Efficient Polycrystalline SnSe Thermoelectric Devices
Appl. Sci. 2017, 7(11), 1116; doi:10.3390/app7111116
Received: 19 September 2017 / Revised: 13 October 2017 / Accepted: 23 October 2017 / Published: 28 October 2017
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Abstract
Recently, SnSe material with an outstanding high ZT (Figure of merit) of 2.6 has attracted much attention due to its strong applicability for highly efficient thermoelectric devices. Many studies following the first journal publication have been focused on SnSe materials, not on thermoelectric
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Recently, SnSe material with an outstanding high ZT (Figure of merit) of 2.6 has attracted much attention due to its strong applicability for highly efficient thermoelectric devices. Many studies following the first journal publication have been focused on SnSe materials, not on thermoelectric devices. Particularly, to realize highly efficient intermediate-temperature (600~1000 K) thermoelectric modules with this promising thermoelectric material, a more thermally and electrically reliable interface bonding technology needs to be developed so that the modules can stably perform their power generation in this temperature range. In this work, we demonstrate several approaches to develop metallization layers on SnSe thermoelectric legs. The single-layer metallization shows limitations in their electrical contact resistances and elemental diffusions. The Ag/Co/Ti multi-layer metallization results in lowering their electrical contact resistances, in addition to providing more robust interfaces. Moreover, it is found to maintain the interfacial characteristics without any significant degradation, even after heat treatment at 723 K for 20 h. These results can be effectively applied in the fabrication of thermoelectric devices or modules that are made of the SnSe thermoelectric materials. Full article
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Open AccessArticle Incipient Fault Feature Extraction of Rolling Bearings Using Autocorrelation Function Impulse Harmonic to Noise Ratio Index Based SVD and Teager Energy Operator
Appl. Sci. 2017, 7(11), 1117; doi:10.3390/app7111117
Received: 2 September 2017 / Accepted: 25 October 2017 / Published: 30 October 2017
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Abstract
The periodic impulse feature is the most typical fault signature of the vibration signal from fault rolling element bearings (REBs). However, it is easily contaminated by noise and interference harmonics. In order to extract the incipient impulse feature from the fault vibration signal,
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The periodic impulse feature is the most typical fault signature of the vibration signal from fault rolling element bearings (REBs). However, it is easily contaminated by noise and interference harmonics. In order to extract the incipient impulse feature from the fault vibration signal, this paper presented an autocorrelation function periodic impulse harmonic to noise ratio (ACFHNR) index based on the SVD-Teager energy operator (TEO) method. Firstly, the Hankel matrix is constructed based on the raw vibration fault signal of rolling bearing, and the SVD method is used to obtain the singular components. Afterwards, the ACFHNR index is employed to measure the abundance of the periodic impulse fault feature for the singular components, and the component with the largest ACFHNR index value is extracted. Moreover, the properties of the ACFHNR index are demonstrated by simulations and the full life cycle of the experiment, showing its superiority over the traditional kurtosis and root mean square (RMS) index for extracting and detecting incipient periodic impulse features. Finally, the Teager energy operator spectrum of the extracted informative signal is gained. The simulation and experimental results indicated that the proposed ACFHNR index based method can effectively detect the incipient fault feature of the rolling bearing, and it shows better performance than the kurtosis and RMS index based methods. Full article
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Open AccessArticle Roller-Integrated Acoustic Wave Detection Technique for Rockfill Materials
Appl. Sci. 2017, 7(11), 1118; doi:10.3390/app7111118
Received: 3 September 2017 / Accepted: 26 October 2017 / Published: 30 October 2017
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Abstract
This paper proposes a roller-integrated acoustic wave detection technique for rockfill materials. This technique can be divided into two parts: theoretical analysis and technical implementation. Based on Lamb’s problem and an infinite baffle piston radiation acoustic field model, a relationship model between the
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This paper proposes a roller-integrated acoustic wave detection technique for rockfill materials. This technique can be divided into two parts: theoretical analysis and technical implementation. Based on Lamb’s problem and an infinite baffle piston radiation acoustic field model, a relationship model between the sound compaction value (SCV) and the dry density of the natural gravel materials (NGM) was established, namely, A-model. During the modeling process, an innovative differential pulse excitation method (DPEM) was used to find the numerical solution of the vertical displacement of the soil surface under harmonic loads. In this research, a continuous compaction control acoustic wave detection system (CAWDS) was developed and utilized along with real-time kinematic global positioning systems (RTK-GPS). The SCV was adopted as a characterization index for the compaction quality of rockfill materials. A case study on a reservoir project in Luoyang, China indicated that the SCV is highly linearly correlated with the number of compaction times, dry density, and compactness of the NGM. This new technique demonstrated several advantages, such as higher accuracy, discreetness, convenience, and suitability for detecting the compactness of the NGM. This technique is an effective tool for compaction quality control of rockfill materials and has a great potential for further applications. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Influence of Odd and Even Alkyl Chains on Supramolecular Nanoarchitecture via Self-Assembly of Tetraphenylethylene-Based AIEgens
Appl. Sci. 2017, 7(11), 1119; doi:10.3390/app7111119
Received: 22 September 2017 / Revised: 19 October 2017 / Accepted: 25 October 2017 / Published: 30 October 2017
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Abstract
The Tetraphenylethylene (TPE) based dumbbell shaped molecules TPE-Pi, TPE-Su, TPE-Az, and TPE-Se were synthesised bearing odd-even alkyl chains containing 7, 8, 9 and 10 carbons respectively. These molecules reveal typical Aggregation Induced Emission (AIE) behaviour. The influence of the odd or
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The Tetraphenylethylene (TPE) based dumbbell shaped molecules TPE-Pi, TPE-Su, TPE-Az, and TPE-Se were synthesised bearing odd-even alkyl chains containing 7, 8, 9 and 10 carbons respectively. These molecules reveal typical Aggregation Induced Emission (AIE) behaviour. The influence of the odd or even alkyl chain length was shown by studying the morphology of self-assembled nanostructures formed in a range of tetrahydrofuran (THF)/water solvent systems. For example, with a water fraction of 80%, TPE derivatives with odd alkyl chains (TPE-Pi and TPE-Az) self-assembled into nanosphere structures, while TPE-Su with 8 alkyl chains formed microbelts and TPE-Se with 10 alkyl chains aggregated into flower-like superstructures. These TPE derivatives also revealed interesting mechanochromic properties upon grinding, fuming and heating, which reveal the importance of molecular stacking in the crystal structure to the luminescent properties of the aggregates .The mechanochromic properties of TPE-Pi, TPE-Su, and TPE-Az were also demonstrated by the process of grounding, fuming, and heating. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Study on the Hydrodynamic Performance of Typical Underwater Bionic Foils with Spanwise Flexibility
Appl. Sci. 2017, 7(11), 1120; doi:10.3390/app7111120
Received: 22 September 2017 / Revised: 25 October 2017 / Accepted: 26 October 2017 / Published: 30 October 2017
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Abstract
Bionic foils are usually similar in shape to the locomotive organs of animals living in fluid media, which is helpful in the analysis of the motion mode and hydrodynamic mechanisms of biological prototypes. With the design of underwater vehicles as the research background,
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Bionic foils are usually similar in shape to the locomotive organs of animals living in fluid media, which is helpful in the analysis of the motion mode and hydrodynamic mechanisms of biological prototypes. With the design of underwater vehicles as the research background, bionic foils are adopted as research objects in this paper. A geometric model and a motion model are established depending on the biological prototype. In the model, two typical bionic foils―a NACA foil and a crescent-shaped foil―are chosen as research objects. Simulations of the bionic foils are performed using a numerical method based on computational fluid dynamics software. The hydrodynamic forces acting on the foils and flow field characteristics behind the foils are used to analyze the propulsion performance and hydrodynamic mechanism. Furthermore, a spanwise flexibility model is introduced into the motion model. Next, the hydrodynamic mechanism is further analyzed on the basis of hydrodynamic forces and flow field characteristics with different spanwise flexibility parameters. Finally, an experimental verification platform is designed and built to verify the reliability of the numerical results. Agreement between the experimental and numerical results indicates that the numerical results are reliable and that the analysis of the paper is reasonable. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Low-Frequency Noise Reduction by Earmuffs with Coir and Coir/Carbon Fibre-Reinforced Polypropylene Ear Cups
Appl. Sci. 2017, 7(11), 1121; doi:10.3390/app7111121
Received: 15 September 2017 / Revised: 25 October 2017 / Accepted: 27 October 2017 / Published: 31 October 2017
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Abstract
Natural fibres have been extensively studied due to their potential in a wide range of applications. This study aims to demonstrate the viability of composite earmuffs for low-frequency noise reduction in continuous and transient noise environments. Pink noise and aircraft take-off exterior noise
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Natural fibres have been extensively studied due to their potential in a wide range of applications. This study aims to demonstrate the viability of composite earmuffs for low-frequency noise reduction in continuous and transient noise environments. Pink noise and aircraft take-off exterior noise were considered for the former and the latter, respectively. The assembly components of the composite earmuffs were kept identical to a commercial earmuff, which served as a reference for results comparison. Based on the profile of the ear cups from the commercial earmuff, composite ear cups were fabricated from coir fibre and coir/carbon fibre fabrics reinforced with polypropylene. In contrast to the commercial earmuff, the composite earmuffs showed improvements in insertion loss at specific frequencies in the respective noise environments. In pink noise, up to 12 dB improvement in insertion loss was achieved. In aircraft take-off exterior noise, up to 8.6 dB improvement in insertion loss was achieved at 160–544 Hz particularly by the coir fibre-reinforced polypropylene earmuff. Consequently, the proposed earmuffs may find applications in areas where noise exposure is predominantly low-frequency—in some vehicle cabins, at airports, and at construction sites, for example. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Performance Evaluation of Submerged Floating Tunnel Subjected to Hydrodynamic and Seismic Excitations
Appl. Sci. 2017, 7(11), 1122; doi:10.3390/app7111122
Received: 24 September 2017 / Accepted: 27 October 2017 / Published: 31 October 2017
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Abstract
Submerged floating tunnels (SFTs) are innovative structural solutions to waterway crossings, such as sea-straits, fjords and lakes. As the width and depth of straits increase, the conventional structures such as cable-supported bridges, underground tunnels or immersed tunnels become uneconomical alternatives. For the realization
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Submerged floating tunnels (SFTs) are innovative structural solutions to waterway crossings, such as sea-straits, fjords and lakes. As the width and depth of straits increase, the conventional structures such as cable-supported bridges, underground tunnels or immersed tunnels become uneconomical alternatives. For the realization of SFT, the structural response under extreme environmental conditions needs to be evaluated properly. This study evaluates the displacements and internal forces of SFT under hydrodynamic and three-dimensional seismic excitations to check the global performance of an SFT in order to conclude on the optimum design. The formulations incorporate modeling of ocean waves, currents and mooring cables. The SFT responses were evaluated using three different mooring cable arrangements to determine the stability of the mooring configuration, and the most promising configuration was then used for further investigations. A comparison of static, hydrodynamic and seismic response envelope curves of the SFT is provided to determine the dominant structural response. The study produces useful conclusions regarding the structural behavior of the SFT using a three-dimensional numerical model. Full article
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Open AccessArticle Tire-Pavement Friction Characteristics with Elastic Properties of Asphalt Pavements
Appl. Sci. 2017, 7(11), 1123; doi:10.3390/app7111123
Received: 16 September 2017 / Revised: 26 October 2017 / Accepted: 26 October 2017 / Published: 1 November 2017
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Abstract
The skid-resisting performance of pavement is a critical factor in traffic safety. Recent studies primarily analyze this behavior by examining the macro or micro texture of the pavement. It is inevitable that skid-resistance declines with time because the texture of pavement deteriorates throughout
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The skid-resisting performance of pavement is a critical factor in traffic safety. Recent studies primarily analyze this behavior by examining the macro or micro texture of the pavement. It is inevitable that skid-resistance declines with time because the texture of pavement deteriorates throughout its service life. The primary objective of this paper is to evaluate the use of different asphalt pavements, varying in resilience, to optimize braking performance on pavement. Based on the systematic dynamics of tire-pavement contact, and analysis of the tire-road coupled friction mechanism and the effect of enlarging the tire-pavement contact area, road skid resistance was investigated by altering the elastic modulus of asphalt pavement. First, this research constructed the kinetic contact model to simulate tire-pavement friction. Next, the following aspects of contact behaviors were studied when braking: tread deformation in the tangential pavement interface, actual tire-pavement contact in the course, and the frictional braking force transmitted from the pavement to the tires. It was observed that with improvements in pavement elasticity, the actual tire-pavement contact area increased, which gives us the ability to effectively strengthen the frictional adhesion of the tire to the pavement. It should not be overlooked that the improvement in skid resistance was caused by an increase in pavement elasticity. This research approach provides a theoretical basis and design reference for the anti-skid research of asphalt pavements. Full article
(This article belongs to the Special Issue Advanced Asphalt Materials and Paving Technologies)
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Open AccessArticle Qualitative and Quantitative Changes of Carbonate Rocks Exposed to SC CO2 (Basque-Cantabrian Basin, Northern Spain)
Appl. Sci. 2017, 7(11), 1124; doi:10.3390/app7111124
Received: 30 September 2017 / Accepted: 27 October 2017 / Published: 1 November 2017
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Abstract
This study aims at the qualitative and quantitative determination of porosity, mineralogical and textural changes in carbonate rock samples after injection of (i) supercritical CO2-rich brine and (ii) dry supercritical CO2, under similar experimental conditions (P ≈ 75
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This study aims at the qualitative and quantitative determination of porosity, mineralogical and textural changes in carbonate rock samples after injection of (i) supercritical CO2-rich brine and (ii) dry supercritical CO2, under similar experimental conditions (P ≈ 75 bar, T ≈ 35 °C, 970 h exposure time and no CO2 flow). The studied rocks were sampled in the western Basque-Cantabrian Basin, North Spain, and consist of vuggy carbonates (“Carniolas”) of the Puerto de la Palombera formation (Hettangian). Mineralogical and pore space characterization is completed using optical microscopy, scanning electron microscopy and optical image analysis. In addition, X-ray fluorescence analyses are performed to refine the mineralogical information and to obtain whole rock geochemical data and the brine composition is analysed before and after the experiment. Mineralogical and chemical results indicate that the carbonate rocks exposed to supercritical CO2 in dry conditions do not suffer significant changes. However, the injection of supercritical CO2-rich brine induces chemical and physical changes in the rock due to the high reactivity of calcite at the low pH conditions produced by the acidified brine. Numerical modelling validates the experimental observations. These results can be used to characterize the behaviour of carbonate rocks under conditions similar to the vicinity of a CO2 injection well. The results should be considered only at the scale of the studied samples and not at reservoir scale. Full article
(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)
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Open AccessArticle A Static Displacement Monitoring System for VLBI Antenna Using Close-Range Photogrammetry
Appl. Sci. 2017, 7(11), 1125; doi:10.3390/app7111125
Received: 25 September 2017 / Revised: 31 October 2017 / Accepted: 31 October 2017 / Published: 1 November 2017
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Abstract
In this study, a static displacement monitoring program was developed to maintain the accurate performance of a Very Long Baseline Interferometry (VLBI) antenna by monitoring its structural stability. The monitoring program was designed to measure static displacement, among the many displacements of the
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In this study, a static displacement monitoring program was developed to maintain the accurate performance of a Very Long Baseline Interferometry (VLBI) antenna by monitoring its structural stability. The monitoring program was designed to measure static displacement, among the many displacements of the antenna’s main reflector, which can directly affect its performance. The program measures the position of a monitored object with mm-level accuracy through close-range photogrammetry that uses high-resolution Charge Coupled Device (CCD) cameras. The developed program will be used to evaluate the structural soundness of an antenna based on continuous displacement measurements, which can also be used as basic data for repair and reinforcement work in the future. Full article
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Open AccessArticle ABS-SOCI: An Agent-Based Simulator of Student Sociograms
Appl. Sci. 2017, 7(11), 1126; doi:10.3390/app7111126
Received: 22 September 2017 / Revised: 15 October 2017 / Accepted: 27 October 2017 / Published: 1 November 2017
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Abstract
Sociograms can represent the social relations between students. Some kinds of sociograms are more suitable than others for achieving a high academic performance of students. However, for now, at the beginning of an educative period, it is not possible to know for sure
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Sociograms can represent the social relations between students. Some kinds of sociograms are more suitable than others for achieving a high academic performance of students. However, for now, at the beginning of an educative period, it is not possible to know for sure how the sociogram of a group of students will be or evolve during a semester or an academic year. In this context, the current approach presents an Agent-Based Simulator (ABS) that predicts the sociogram of a group of students taking into consideration their psychological profiles, by evolving an initial sociogram through time. This simulator is referred to as ABS-SOCI (ABS for SOCIograms). For instance, this can be useful for organizing class groups for some subjects of engineering grades, anticipating additional learning assistance or testing some teaching strategies. As experimentation, ABS-SOCI has been executed 100 times for each one of four real scenarios. The results show that ABS-SOCI produces sociograms similar to the real ones considering certain sociometrics. This similarity has been corroborated by statistical binomial tests that check whether there are significant differences between the simulations and the real cases. This experimentation also includes cross-validation and an analysis of sensitivity. ABS-SOCI is free and open-source to (1) ensure the reproducibility of the experiments; (2) to allow practitioners to run simulations; and (3) to allow developers to adapt the simulator for different environments. Full article
(This article belongs to the Special Issue Multi-Agent Systems)
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Open AccessArticle CSO Based Solution for Load Kickback Effect in Deregulated Power Systems
Appl. Sci. 2017, 7(11), 1127; doi:10.3390/app7111127
Received: 18 September 2017 / Accepted: 25 October 2017 / Published: 1 November 2017
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Abstract
With increase in power demand, load demand values have also risen to a greater extent. Sometimes, these demands are met with the great difficulties. All these difficulties drive us to seek other alternative ways. One such a way demand response (DR) is considered
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With increase in power demand, load demand values have also risen to a greater extent. Sometimes, these demands are met with the great difficulties. All these difficulties drive us to seek other alternative ways. One such a way demand response (DR) is considered in this paper, it is a new concept that is introduced in the system in order to reduce peak hour stresses. When implementing the demand response, the main setbacks that arise is the load kickback effect, which the sudden rise in demand during non-peak hours that is caused by the overuse of power by consumers, after their constant reduction of power during peak hours. This paper discusses the various kickback load types, and an effective approach to avoid and tackle kickback effect, by an effective method Cat Swarm Optimization (CSO), which is based on studying the movement of cats. The optimization has been implemented on an IEEE 30 bus and 75 bus Indian utility system, and the results are discussed. Full article
(This article belongs to the Special Issue Distribution Power Systems)
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Open AccessArticle Preparation of Robust Superhydrophobic Halloysite Clay Nanotubes via Mussel-Inspired Surface Modification
Appl. Sci. 2017, 7(11), 1129; doi:10.3390/app7111129
Received: 20 September 2017 / Accepted: 25 October 2017 / Published: 2 November 2017
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Abstract
In this study, a novel and convenient bio-inspired modification strategy was used to create stable superhydrophobic structures on halloysite clay nanotubes (HNTs) surfaces. The polydopamine (PDA) nanoparticles can firmly adhere on HNTs surfaces in a mail environment of pH 8.5 via the oxidative
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In this study, a novel and convenient bio-inspired modification strategy was used to create stable superhydrophobic structures on halloysite clay nanotubes (HNTs) surfaces. The polydopamine (PDA) nanoparticles can firmly adhere on HNTs surfaces in a mail environment of pH 8.5 via the oxidative self-polymerization of dopamine and synthesize a rough nano-layer assisted with vitamin M, which provides a catechol functional platform for the secondary reaction to graft hydrophobic long-chain alkylamine for preparation of hierarchical micro/nano structures with superhydrophobic properties. The micromorphology, crystal structure, and surface chemical composition of the resultant superhydrophobic HNTs were characterized by field emission scanning electron (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The as-formed surfaces exhibited outstanding superhydrophobicity with a water contact angle (CA) of 156.3 ± 2.3°, while having little effect on the crystal structures of HNTs. Meanwhile, the resultant HNTs also showed robust stability that can conquer various harsh conditions including strong acidic/alkaline solutions, organic solvents, water boiling, ultrasonic cleaning, and outdoor solar radiation. In addition, the novel HNTs exhibited excellent packaged capabilities of phase change materials (PCMs) for practical application in thermal energy storage, which improved the mass fractions by 22.94% for stearic acid and showed good recyclability. These HNTs also exhibited good oil/water separation ability. Consequently, due to the superior merits of high efficiency, easy operation, and non-toxicity, this bionic surface modification approach may make HNTs have great potentials for extensive applications. Full article
(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)
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Open AccessArticle Bio-Inspired Real-Time Prediction of Human Locomotion for Exoskeletal Robot Control
Appl. Sci. 2017, 7(11), 1130; doi:10.3390/app7111130
Received: 7 September 2017 / Revised: 25 October 2017 / Accepted: 31 October 2017 / Published: 2 November 2017
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Abstract
Human motion detection is of fundamental importance for control of human–robot coupled systems such as exoskeletal robots. Inertial measurement units have been widely used for this purpose, although delay is a major challenge for inertial measurement unit-based motion capture systems. In this paper,
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Human motion detection is of fundamental importance for control of human–robot coupled systems such as exoskeletal robots. Inertial measurement units have been widely used for this purpose, although delay is a major challenge for inertial measurement unit-based motion capture systems. In this paper, we use previous and current inertial measurement unit readings to predict human locomotion based on their kinematic properties. Human locomotion is a synergetic process of the musculoskeletal system characterized by smoothness, high nonlinearity, and quasi-periodicity. Takens’ reconstruction method can well characterize quasi-periodicity and nonlinear systems. With Takens’ reconstruction framework, we developed improving methods, including Gaussian coefficient weighting and offset correction (which is based on the smoothness of human locomotion), Kalman fusion with complementary joint data prediction and united source of historical embedding generation (which is synergy-inspired), and Kalman fusion with the Newton-based method with a velocity and acceleration high-gain observer (also based on smoothness). After thorough analysis of the parameters and the effect of these improving techniques, we propose a novel prediction method that possesses the combined advantages of parameter robustness, high accuracy, trajectory smoothness, zero dead time, and adaptability to irregularities. The proposed methods were tested and validated by experiments, and the real-time applicability in a human locomotion capture system was also validated. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle An Experimental Platform for Autonomous Bus Development
Appl. Sci. 2017, 7(11), 1131; doi:10.3390/app7111131
Received: 26 September 2017 / Revised: 27 October 2017 / Accepted: 30 October 2017 / Published: 2 November 2017
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Abstract
Nowadays, with highly developed instrumentation, sensing and actuation technologies, it is possible to foresee an important advance in the field of autonomous and/or semi-autonomous transportation systems. Intelligent Transport Systems (ITS) have been subjected to very active research for many years, and Bus Rapid
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Nowadays, with highly developed instrumentation, sensing and actuation technologies, it is possible to foresee an important advance in the field of autonomous and/or semi-autonomous transportation systems. Intelligent Transport Systems (ITS) have been subjected to very active research for many years, and Bus Rapid Transit (BRT) is one area of major interest. Among the most promising transport infrastructures, the articulated bus is an interesting, low cost, high occupancy capacity and friendly option. In this paper, an experimental platform for research on the automatic control of an articulated bus is presented. The aim of the platform is to allow full experimentation in real conditions for testing technological developments and control algorithms. The experimental platform consists of a mobile component (a commercial articulated bus) fully instrumented and a ground test area composed of asphalt roads inside the Consejo Superior de Investigaciones Científicas (CSIC) premises. This paper focuses also on the development of a human machine interface to ease progress in control system evaluation. Some experimental results are presented in order to show the potential of the proposed platform. Full article
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Open AccessArticle A Time-Varying Potential-Based Demand Response Method for Mitigating the Impacts of Wind Power Forecasting Errors
Appl. Sci. 2017, 7(11), 1132; doi:10.3390/app7111132
Received: 3 October 2017 / Revised: 24 October 2017 / Accepted: 27 October 2017 / Published: 3 November 2017
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Abstract
The uncertainty of wind power results in wind power forecasting errors (WPFE) which lead to difficulties in formulating dispatching strategies to maintain the power balance. Demand response (DR) is a promising tool to balance power by alleviating the impact of WPFE. This paper
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The uncertainty of wind power results in wind power forecasting errors (WPFE) which lead to difficulties in formulating dispatching strategies to maintain the power balance. Demand response (DR) is a promising tool to balance power by alleviating the impact of WPFE. This paper offers a control method of combining DR and automatic generation control (AGC) units to smooth the system’s imbalance, considering the real-time DR potential (DRP) and security constraints. A schematic diagram is proposed from the perspective of a dispatching center that manages smart appliances including air conditioner (AC), water heater (WH), electric vehicle (EV) loads, and AGC units to maximize the wind accommodation. The presented model schedules the AC, WH, and EV loads without compromising the consumers’ comfort preferences. Meanwhile, the ramp constraint of generators and power flow transmission constraint are considered to guarantee the safety and stability of the power system. To demonstrate the performance of the proposed approach, simulations are performed in an IEEE 24-node system. The results indicate that considerable benefits can be realized by coordinating the DR and AGC units to mitigate the WPFE impacts. Full article
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Open AccessArticle Snake-Like Robot with Fusion Gait for High Environmental Adaptability: Design, Modeling, and Experiment
Appl. Sci. 2017, 7(11), 1133; doi:10.3390/app7111133
Received: 22 September 2017 / Revised: 30 October 2017 / Accepted: 31 October 2017 / Published: 3 November 2017
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Abstract
A snake changes its gait to adapt to different environments. A snake-like robot that is able to perform as many or more gaits than a real-life snake has the potential to successfully adapt to a range of environments, similar to a real-life snake.
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A snake changes its gait to adapt to different environments. A snake-like robot that is able to perform as many or more gaits than a real-life snake has the potential to successfully adapt to a range of environments, similar to a real-life snake. However, only a few mechanisms in the current snake-like framework can perform common gaits. In this paper, a novel snake-like robot is developed to resolve this problem. A multi-gait is established and used as a reference for the articulation design. A non-snake-like mechanism with linear articulation is combined with the classical swing joint. A prototype is designed and constructed for verification and analysis. Two basic main gaits, namely, serpentine and rectilinear locomotion, are fused, and a novel obstacle-aided locomotion based on rectilinear motion is developed. The experiment demonstrates that the robot can generate all of the expected gaits with high movement efficiency. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle 3-D Printed Fabry–Pérot Resonator Antenna with Paraboloid-Shape Superstrate for Wide Gain Bandwidth
Appl. Sci. 2017, 7(11), 1134; doi:10.3390/app7111134
Received: 23 September 2017 / Revised: 22 October 2017 / Accepted: 1 November 2017 / Published: 4 November 2017
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Abstract
A three-dimensional (3-D) printed Fabry–Pérot resonator antenna (FPRA), which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition
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A three-dimensional (3-D) printed Fabry–Pérot resonator antenna (FPRA), which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition of the FPRA in a wide frequency band. A FPRA working at 6 GHz is designed, fabricated, and tested. Considering the fabrication difficulty caused by its complex structure, the prototype antenna was fabricated by using the 3-D printing technology, i.e., all components of the prototype antenna were printed with photopolymer resin and then treated by the surface metallization process. Measurement results agree well with the simulation results, and show the 3-D printed FPRA has a |S11| < −10 dB impedance bandwidth of 12.4%, and a gain of 16.8 dBi at its working frequency of 6 GHz. Moreover, in comparison with the planar superstrate adopted in traditional FPRAs, the paraboloid-shape superstrate of the proposed FPRA significantly improves the 3-dB gain bandwidth from 6% to 22.2%. Full article
(This article belongs to the Special Issue 3D Printed Antennas)
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Open AccessArticle SymCHM—An Unsupervised Approach for Pattern Discovery in Symbolic Music with a Compositional Hierarchical Model
Appl. Sci. 2017, 7(11), 1135; doi:10.3390/app7111135
Received: 13 September 2017 / Revised: 25 October 2017 / Accepted: 1 November 2017 / Published: 4 November 2017
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Abstract
This paper presents a compositional hierarchical model for pattern discovery in symbolic music. The model can be regarded as a deep architecture with a transparent structure. It can learn a set of repeated patterns within individual works or larger corpora in an unsupervised
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This paper presents a compositional hierarchical model for pattern discovery in symbolic music. The model can be regarded as a deep architecture with a transparent structure. It can learn a set of repeated patterns within individual works or larger corpora in an unsupervised manner, relying on statistics of pattern occurrences, and robustly infer the learned patterns in new, unknown works. A learned model contains representations of patterns on different layers, from the simple short structures on lower layers to the longer and more complex music structures on higher layers. A pattern selection procedure can be used to extract the most frequent patterns from the model. We evaluate the model on the publicly available JKU Patterns Datasetsand compare the results to other approaches. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Robust Optimization Strategy for Domestic Electric Water Heater Load Scheduling under Uncertainties
Appl. Sci. 2017, 7(11), 1136; doi:10.3390/app7111136
Received: 3 October 2017 / Revised: 31 October 2017 / Accepted: 1 November 2017 / Published: 5 November 2017
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Abstract
In this paper, a robust optimization strategy is developed to handle the uncertainties for domestic electric water heater load scheduling. At first, the uncertain parameters, including hot water demand and ambient temperature, are described as the intervals, and are further divided into different
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In this paper, a robust optimization strategy is developed to handle the uncertainties for domestic electric water heater load scheduling. At first, the uncertain parameters, including hot water demand and ambient temperature, are described as the intervals, and are further divided into different robust levels in order to control the degree of the conservatism. Based on this, traditional load scheduling problem is rebuilt by bringing the intervals and robust levels into the constraints, and are thus transformed into the equivalent deterministic optimization problem, which can be solved by existing tools. Simulation results demonstrate that the schedules obtained under different robust levels are of complete robustness. Furthermore, in order to offer users the most optimal robust level, the trade-off between the electricity bill and conservatism degree are also discussed. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Wavenumber-Frequency Analysis of Internal Aerodynamic Noise in Constriction-Expansion Pipe
Appl. Sci. 2017, 7(11), 1137; doi:10.3390/app7111137
Received: 27 September 2017 / Revised: 31 October 2017 / Accepted: 2 November 2017 / Published: 5 November 2017
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Abstract
High-pressure gas is produced during the oil production process at offshore plants, and pressure relief devices, such as valves, are widely used to protect related systems from it. The high-pressure gas in the pipes connected to the flare head is burned at the
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High-pressure gas is produced during the oil production process at offshore plants, and pressure relief devices, such as valves, are widely used to protect related systems from it. The high-pressure gas in the pipes connected to the flare head is burned at the flare stack, or, if it is nontoxic, is vented to the atmosphere. During this process, excessive noise is generated by the pressure relief valves that are used to quickly discharge the high-pressure gas to the atmosphere. This noise sometimes causes severe acoustic-induced vibration in the pipe wall. This study estimated the internal aerodynamic noise due to valve flow in a simple constriction-expansion pipe, by combining the large eddy simulation technique with a wavenumber-frequency analysis, which made it possible to decompose the fluctuating pressure into the incompressible hydrodynamic pressure and compressible acoustic pressure. First, the steady-state flow was numerically simulated, and the result was compared with a quasi-one-dimensional theoretical solution, which confirmed the validity of the current numerical method. Then, an unsteady simulation analysis was performed to predict the fluctuating pressure inside a pipe. Finally, the acoustic pressure modes in a pipe were extracted by applying the wavenumber-frequency transform to the total pressure field. The results showed that the acoustic pressure fluctuations in a pipe could be separated from the incompressible ones. This made it possible to obtain accurate information about the acoustic power, which could be used to assess the likelihood of a piping system failure due to acoustic-induced vibration, along with information about the acoustic power spectrum of each acoustic mode, which could be used to facilitate the systematic mitigation of the potential acoustic-induced vibration in piping systems. Full article
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Open AccessArticle Network Defense Strategy Selection with Reinforcement Learning and Pareto Optimization
Appl. Sci. 2017, 7(11), 1138; doi:10.3390/app7111138
Received: 10 October 2017 / Revised: 29 October 2017 / Accepted: 30 October 2017 / Published: 6 November 2017
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Abstract
Improving network security is a difficult problem that requires balancing several goals, such as defense cost and need for network efficiency, in order to achieve proper results. In this paper, we devise method of modeling network attack in a zero-sum multi-objective game and
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Improving network security is a difficult problem that requires balancing several goals, such as defense cost and need for network efficiency, in order to achieve proper results. In this paper, we devise method of modeling network attack in a zero-sum multi-objective game and attempt to find the best defense against such an attack. We combined Pareto optimization and Q-learning methods to determine the most harmful attacks and consequently to find the best defense against those attacks. The results should help network administrators in search of a hands-on method of improving network security. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Energy Performance Analysis of an Integrated Distributed Variable-Frequency Pump and Water Storage System for District Cooling Systems
Appl. Sci. 2017, 7(11), 1139; doi:10.3390/app7111139
Received: 30 September 2017 / Revised: 28 October 2017 / Accepted: 3 November 2017 / Published: 6 November 2017
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Abstract
In a district cooling system (DCS), the distribution system (i.e., cooling water system or chilled water system) will continue to be a critical consideration because it substantially contributes to the total energy consumption. Thus, in this paper, a new distributed variable-frequency pump (DVFP)
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In a district cooling system (DCS), the distribution system (i.e., cooling water system or chilled water system) will continue to be a critical consideration because it substantially contributes to the total energy consumption. Thus, in this paper, a new distributed variable-frequency pump (DVFP) system with water storage (WS) for cooling water is adapted to a DCS with large end-use cooling load fluctuations. The basic principle and energy saving potential of the new system is analyzed. A case study of a DCS with a conventional central circulating pump (CCCP) system is presented to compare the energy consumption and the operating performance of CCCP and DVFP systems that are exposed to various weather conditions. The methods to perform this case study include, cooling load simulation and the modeling of two water distribution networks and systems via several commercial software packages. By replacing the throttling valves with a DVFP, the pump efficiency is increased and transportation energy consumption is reduced. Additionally, by introducing water tank storage, the cooling water is cooled at night and is released at a peak hour during the daytime, thereby further reducing the energy cost. As compared to the field test results of the CCCP system, the daily electrical energy saved by the DVFP and WS system is approximately 57% for a cooling water pump system on the hottest day in summer. This value also corresponds to approximately 10% of the energy saved for the entire system. Furthermore, additional energy could be saved under partial loading conditions. Full article
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Open AccessArticle Control Strategies for Enhancing Frequency Stability by DFIGs in a Power System with High Percentage of Wind Power Penetration
Appl. Sci. 2017, 7(11), 1140; doi:10.3390/app7111140
Received: 8 October 2017 / Revised: 28 October 2017 / Accepted: 2 November 2017 / Published: 6 November 2017
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Abstract
Nowadays, regarding high percentage of wind power penetration in power systems, operating conditions of power system necessitates wind turbine generators (WTGs) to contribute in frequency regulation of the system, similar to the conventional units. To reach this goal, active power output of WTGs
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Nowadays, regarding high percentage of wind power penetration in power systems, operating conditions of power system necessitates wind turbine generators (WTGs) to contribute in frequency regulation of the system, similar to the conventional units. To reach this goal, active power output of WTGs must be controlled, but this issue distances the operating conditions of WTGs from maximum power point tracking (MPPT) mode. This paper initially presents a completed model of doubly fed induction generator (DFIG) for dynamic studies in frequency stability analysis. Next, a coordinated control strategy to regulate active power command set point (Pcmd) for individual WTGs in a wind farm (WF) and a control strategy to regulate wind power output of DFIG upon operator’s request is presented. Stability is assured under different wind conditions in the proposed control strategy. Individual WTGs set point allocation is performed applying fuzzy logic controller (FLC), while emotional learning based intelligent controller is used in regulation of the coefficient in the DFIG to reach the best stability conditions. Simulation results, performed on a test system consisting of both conventional units and WTGs, validate the effectiveness of the proposed control strategy in comparison with other mentioned solutions. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Predicting Project’s Uncertainty Risk in the Bidding Process by Integrating Unstructured Text Data and Structured Numerical Data Using Text Mining
Appl. Sci. 2017, 7(11), 1141; doi:10.3390/app7111141
Received: 29 September 2017 / Revised: 3 November 2017 / Accepted: 3 November 2017 / Published: 6 November 2017
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Abstract
The construction bidding process takes place in the early stages of a construction project. The bidding process involves many uncertainties since the construction risk factors are predicted and reflected in the bid price before construction commences. Therefore, bidders should thoroughly understand the uncertainty
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The construction bidding process takes place in the early stages of a construction project. The bidding process involves many uncertainties since the construction risk factors are predicted and reflected in the bid price before construction commences. Therefore, bidders should thoroughly understand the uncertainty factors of the project before make bidding decisions. The uncertainty risk of construction projects is determined by the content that is contained in the bidding document. If the information provided in the bidding document is not accurate and is unclear, the uncertainty of the projects increases. Thus, this study is performed to predict risks in the bidding process of construction projects by analyzing the uncertainty of the bidding document and using it as factors to predict a project’s bidding risk. To achieve this, bidding risk prediction modeling was conducted using the pre-bid clarification information of each project. In addition, text mining on pre-bid RFI documents, which are in an unstructured text data format, was performed and the results of text mining were used as major influencing factors for the risk prediction models. As a result, the accuracy of the risk prediction model including text data was improved (72.92%) when compared to the prediction model using only numeric data (52.08%). The results of this study are expected to strengthen the possibility of further similar studies in the future since it enhances the predictive accuracy by incorporating the uncertainty of the bidding document, which is rarely considered in previous studies. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Simulation of Wind-Battery Microgrid Based on Short-Term Wind Power Forecasting
Appl. Sci. 2017, 7(11), 1142; doi:10.3390/app7111142
Received: 13 October 2017 / Revised: 26 October 2017 / Accepted: 30 October 2017 / Published: 6 November 2017
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Abstract
The inherently intermittent and highly variable nature of wind necessitates the use of wind power forecasting tools in order to facilitate the integration of wind turbines in microgrids, among others. In this direction, the present paper describes the development of a short-term wind
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The inherently intermittent and highly variable nature of wind necessitates the use of wind power forecasting tools in order to facilitate the integration of wind turbines in microgrids, among others. In this direction, the present paper describes the development of a short-term wind power forecasting model based on artificial neural network (ANN) clustering, which uses statistical feature parameters in the input vector, as well as an enhanced version of this approach that adjusts the ANN output with the probability of lower misclassification (PLM) method. Moreover, it employs the Monte Carlo simulation to represent the stochastic variation of wind power production and assess the impact of energy management decisions in a residential wind-battery microgrid using the proposed wind power forecasting models. The results indicate that there are significant benefits for the microgrid when compared to the naïve approach that is used for benchmarking purposes, while the PLM adjustment method provides further improvements in terms of forecasting accuracy. Full article
(This article belongs to the Special Issue Applications of Artificial Neural Networks for Energy Systems)
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Open AccessArticle Polyvinyl Alcohol/Lithospermum Erythrorhizon Nanofibrous Membrane: Characterizations, In Vitro Drug Release, and Cell Viability
Appl. Sci. 2017, 7(11), 1143; doi:10.3390/app7111143
Received: 6 October 2017 / Accepted: 2 November 2017 / Published: 6 November 2017
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Abstract
This study proposes an optimization process of the Lithospermum erythrorhizon (LE) extraction with a higher purity of shikonin (SK). The influence of extraction temperature on the concentration of SK is examined, and an in vitro cell viability assay is used to examine the
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This study proposes an optimization process of the Lithospermum erythrorhizon (LE) extraction with a higher purity of shikonin (SK). The influence of extraction temperature on the concentration of SK is examined, and an in vitro cell viability assay is used to examine the optimal concentration of SK. Afterwards, polyvinyl alcohol (PVA)/LE solutions at ratios of 90/10, 80/20, and 70/30 w/w are electrospun into LE electrospun nanofibrous membranes (LENMs). The optimal manufacture parameters of LENMs are evaluated based on the test results of in vitro drug release test and cell viability assay. The optimal concentration occurs when the extraction temperature is −10 °C. The purity of the LE extract reaches 53.8% and the concentration of SK is 1.07 mg/mL. Moreover, the cell viability of nanofibrous membranes significantly increases to 136.8% when 0.7 μM SK is used. The diameter of nanofibers of LENM is decreased by 43.9% when the ratio of PVA solution to LE extract is 70/30 (w/w). 80/20 (w/w) LENM has the maximum amount of drug release of 79% for a continuous period of 48 h. In particular, 90/10 (w/w) LENM can create the maximum cell proliferation of 157.5% in a 24-h in vitro cell viability assay. This suggests that LENM has great potential to be used in facilitating tissue regeneration and wound healing. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Effect of Control Measures on Wheel/Rail Noise When the Vehicle Curves
Appl. Sci. 2017, 7(11), 1144; doi:10.3390/app7111144
Received: 12 October 2017 / Revised: 28 October 2017 / Accepted: 3 November 2017 / Published: 6 November 2017
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Abstract
This paper developed a time domain simplified model to study the effect of control measures on wheel/rail noise when the vehicle curves. The time domain model consists of two parts, one being a vehicle-track coupling dynamic model for wheel/rail interaction, the other being
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This paper developed a time domain simplified model to study the effect of control measures on wheel/rail noise when the vehicle curves. The time domain model consists of two parts, one being a vehicle-track coupling dynamic model for wheel/rail interaction, the other being a transient finite element and boundary element domain model for vibration and sound radiation. Wheel/rail noise under wheel/rail lateral creep force is predicted for a narrowly curved section of a conventional underground railway, and compared with measurement. Based on the developed model, the effect of wheel/rail friction modification on squeal noise is investigated. In addition, effectiveness of resilient wheel and embedded track to control curve squeal noise are also assessed. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Analysis of the Macroscopic Behavior of Server Systems in the Internet Environment
Appl. Sci. 2017, 7(11), 1145; doi:10.3390/app7111145
Received: 23 September 2017 / Revised: 19 October 2017 / Accepted: 3 November 2017 / Published: 6 November 2017
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Abstract
Elasticity is one of the key features of cloud-hosted services built on virtualization technology. To utilize the elasticity of cloud environments, administrators should accurately capture the operational status of server systems, which changes constantly according to service requests incoming irregularly. However, it is
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Elasticity is one of the key features of cloud-hosted services built on virtualization technology. To utilize the elasticity of cloud environments, administrators should accurately capture the operational status of server systems, which changes constantly according to service requests incoming irregularly. However, it is difficult to detect and avoid in advance that operating services are falling into an undesirable state. In this paper, we focus on the management of server systems that include cloud systems, and propose a new method for detecting the sign of undesirable scenarios before the system becomes overloaded as a result of various causes. In this method, a measure that utilizes the fluctuation of the macroscopic operational state observed in the server system is introduced. The proposed measure has the property of drastically increasing before the server system is in an undesirable state. Using the proposed measure, we realize a function to detect that the server system is falling into an overload scenario, and we demonstrate its effectiveness through experiments. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle On the Seismic Design of Structures with Tilting Located within a Seismic Region
Appl. Sci. 2017, 7(11), 1146; doi:10.3390/app7111146
Received: 13 September 2017 / Revised: 27 October 2017 / Accepted: 30 October 2017 / Published: 7 November 2017
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Abstract
A reliability-based criterion to estimate strength amplification factors for buildings with asymmetric yielding located within a seismic region presenting different soil conditions is proposed and applied. The approach involves the calculation of the mean annual rate of exceedance of structural demands of systems
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A reliability-based criterion to estimate strength amplification factors for buildings with asymmetric yielding located within a seismic region presenting different soil conditions is proposed and applied. The approach involves the calculation of the mean annual rate of exceedance of structural demands of systems with different levels of asymmetric yielding. Two simplified mathematical expressions are developed considering different soil conditions of the valley of Mexico. The mathematical expressions depend on the ductility of the structural systems, their level of asymmetric yielding, their fundamental vibration period and the dominant period of the soil. In addition, the proposed expressions are compared with that recommended by the current Mexico City Building Code (MCBC). Since the expressions are developed with the help of simplified structural systems, the validity of such expressions is corroborated by comparing the expected ductility demand of multi-degree of freedom (MDOF) structural systems with respect to that of their equivalent simplified systems. Both structural representations are associated with a given annual rate of exceedance value of an engineering demand parameter. The expressions proposed in this study will be incorporated in the new version of the MCBC. Full article
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Open AccessArticle Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures
Appl. Sci. 2017, 7(11), 1147; doi:10.3390/app7111147
Received: 17 July 2017 / Revised: 20 October 2017 / Accepted: 26 October 2017 / Published: 7 November 2017
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Abstract
Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions
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Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles) make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths) to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Theoretical Analysis for the Flow Ripple of a Tandem Crescent Pump with Index Angles
Appl. Sci. 2017, 7(11), 1148; doi:10.3390/app7111148
Received: 16 October 2017 / Revised: 31 October 2017 / Accepted: 3 November 2017 / Published: 8 November 2017
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Abstract
This paper presents a theoretical approach for lowering the outlet flow ripple of a crescent pump by applying a tandem crescent pump consisting of two gear pairs with an index angle between them. The outlet flow of the tandem pump is obtained by
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This paper presents a theoretical approach for lowering the outlet flow ripple of a crescent pump by applying a tandem crescent pump consisting of two gear pairs with an index angle between them. The outlet flow of the tandem pump is obtained by summing the flow produced by the two gear pairs, and the flow ripple of the tandem pump can be attenuated by properly selecting the design parameters in terms of the index angle and the displacement ratio between the two gear pairs. A lumped parameter model is presented for evaluating the crescent pump’s flow ripples, and experiments were performed on a single crescent pump to validate the model from the aspects of the steady-state flow-pressure characteristics and the outlet pressure ripples. In this way, the main causes of the flow ripple could be identified by comparing the kinematic flow with the actual flow evaluated by the model. Additionally, simulation results suggested that a tandem pump with an index angle of 13.85° and displacement ratio of 0.5 could lead to a more than 45% decrease in the outlet flow ripple than a single pump with the same displacement in a wide range of operating conditions. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessArticle A Negative Index Metamaterial to Enhance the Performance of Miniaturized UWB Antenna for Microwave Imaging Applications
Appl. Sci. 2017, 7(11), 1149; doi:10.3390/app7111149
Received: 2 October 2017 / Revised: 2 November 2017 / Accepted: 6 November 2017 / Published: 8 November 2017
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Abstract
A new, compact planar wideband negative index metamaterial based on a modified split ring resonator (SRR) is studied to enhance performance of ultrawideband antenna. A compact, metamaterial (MTM)-inspired microstrip antenna is presented for microwave imaging system (MIS) application. Two layers of left-handed metamaterial
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A new, compact planar wideband negative index metamaterial based on a modified split ring resonator (SRR) is studied to enhance performance of ultrawideband antenna. A compact, metamaterial (MTM)-inspired microstrip antenna is presented for microwave imaging system (MIS) application. Two layers of left-handed metamaterial array (2 × 4) of the unit cell are placed on the radiating patch and the ground plane, respectively. Each left-handed metamaterial (LHM) unit cell was constructed by modifying a square split ring resonator (SRR), resulting in negative permeability and permittivity with a stable negative refractive index. The results shows that it has a significant impact on the performance of conventional patch antenna in terms of transmission co-efficient, efficiency and low loss. Compared to antenna without LHM, it is shown that the bandwidth is significantly broadened up to a few megahertz and becomes more convergent leading to the achievement of desired properties for ultra-wideband (UWB) applications leading to microwave imaging. The proposed MTM antenna structure is fabricated on commercially-available, flame-retardant material of size 26 × 22 × 1.6 mm3 with 4.6 dielectric constants, due to its low cost and convenience for making multilayer printed circuit boards (PCBs). The antenna achieves 3.1 GHz to 10.71 GHz of impedance bandwidth (−10 dB), which covers the full UWB band. The use of double-layer negative index MTM unit cells enhances UWB performance, and the improved radiation efficiency, nearly directional radiation pattern, acceptable gain, stable surface current and negative refractive index make this MTM antenna a suitable candidate for UWB applications. Full article
(This article belongs to the Section Materials)
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Open AccessArticle The Stability of New Single-Layer Combined Lattice Shell Based on Aluminum Alloy Honeycomb Panels
Appl. Sci. 2017, 7(11), 1150; doi:10.3390/app7111150
Received: 16 October 2017 / Revised: 31 October 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
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Abstract
This article proposes a new type of single-layer combined lattice shell (NSCLS); which is based on aluminum alloy honeycomb panels. Six models with initial geometric defect were designed and precision made using numerical control equipment. The stability of these models was tested. The
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This article proposes a new type of single-layer combined lattice shell (NSCLS); which is based on aluminum alloy honeycomb panels. Six models with initial geometric defect were designed and precision made using numerical control equipment. The stability of these models was tested. The results showed that the stable bearing capacity of NSCLS was approximately 16% higher than that of a lattice shell with the same span without a reinforcing plate. At the same time; the properties of the NSCLS were sensitive to defects. When defects were present; its stable bearing capacity was decreased by 12.3% when compared with the defect-free model. The model with random defects following a truncated Gaussian distribution could be used to simulate the distribution of defects in the NSCLS. The average difference between the results of the nonlinear analysis and the experimental results was 5.7%. By calculating and analyzing nearly 20,000 NSCLS; the suggested values of initial geometric defect were presented. The results of this paper could provide a theoretical basis for making and revising the design codes for this new combined lattice shell structure. Full article
(This article belongs to the Special Issue Mechanical Behaviour of Aluminium Alloys)
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Open AccessArticle Quality Changes of N-3 PUFAs Enriched and Conventional Eggs under Different Home Storage Conditions with Wireless Sensor Network
Appl. Sci. 2017, 7(11), 1151; doi:10.3390/app7111151
Received: 1 October 2017 / Revised: 3 November 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
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Abstract
Omega-3 polyunsaturated fatty acids (n-3 PUFAs) enriched eggs are popular for their enrichment of PUFAs, but their freshness and quality are prone to decline with time, particularly if storage conditions are not well maintained. Home storage is the last but a neglected important
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Omega-3 polyunsaturated fatty acids (n-3 PUFAs) enriched eggs are popular for their enrichment of PUFAs, but their freshness and quality are prone to decline with time, particularly if storage conditions are not well maintained. Home storage is the last but a neglected important tach in eggs supply chain, but few studies are available on the egg storage in the home stage. This study aimed to evaluate the internal quality change of both n-3 PUFAs enriched and conventional eggs by simulating eggs stored at consumers’ home in refrigeration and under room temperature. The egg quality indices (Haugh unit, yolk index, weight, and albumen pH) were adopted and analyzed for both storage conditions. Wireless sensor network (WSN) was used for real-time monitoring of the temperature and humidity during storage. The results showed that temperature, humidity and time of storage all have an influence on the freshness of both n-3 PUFAs enriched and conventional eggs and there is no significant difference happened to n-3 PUFAs enriched eggs and conventional eggs. Refrigeration can decelerate the quality deterioration of both n-3 PUFAs enriched and conventional eggs and consumers should be educated about how to maintain the internal quality of eggs during home storage. Full article
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Open AccessArticle Moving-Target Position Estimation Using GPU-Based Particle Filter for IoT Sensing Applications
Appl. Sci. 2017, 7(11), 1152; doi:10.3390/app7111152
Received: 18 September 2017 / Accepted: 7 November 2017 / Published: 9 November 2017
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Abstract
A particle filter (PF) has been introduced for effective position estimation of moving targets for non-Gaussian and nonlinear systems. The time difference of arrival (TDOA) method using acoustic sensor array has normally been used to for estimation by concealing the location of a
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A particle filter (PF) has been introduced for effective position estimation of moving targets for non-Gaussian and nonlinear systems. The time difference of arrival (TDOA) method using acoustic sensor array has normally been used to for estimation by concealing the location of a moving target, especially underwater. In this paper, we propose a GPU -based acceleration of target position estimation using a PF and propose an efficient system and software architecture. The proposed graphic processing unit (GPU)-based algorithm has more advantages in applying PF signal processing to a target system, which consists of large-scale Internet of Things (IoT)-driven sensors because of the parallelization which is scalable. For the TDOA measurement from the acoustic sensor array, we use the generalized cross correlation phase transform (GCC-PHAT) method to obtain the correlation coefficient of the signal using Fast Fourier Transform (FFT), and we try to accelerate the calculations of GCC-PHAT based TDOA measurements using FFT with GPU compute unified device architecture (CUDA). The proposed approach utilizes a parallelization method in the target position estimation algorithm using GPU-based PF processing. In addition, it could efficiently estimate sudden movement change of the target using GPU-based parallel computing which also can be used for multiple target tracking. It also provides scalability in extending the detection algorithm according to the increase of the number of sensors. Therefore, the proposed architecture can be applied in IoT sensing applications with a large number of sensors. The target estimation algorithm was verified using MATLAB and implemented using GPU CUDA. We implemented the proposed signal processing acceleration system using target GPU to analyze in terms of execution time. The execution time of the algorithm is reduced by 55% from to the CPU standalone operation in target embedded board, NVIDIA Jetson TX1. Also, to apply large-scaled IoT sensing applications, we use NVIDIA Tesla K40c as target GPU. The execution time of the proposed multi-state-space model-based algorithm is similar to the one-state-space model algorithm because of GPU-based parallel computing. Experimental results show that the proposed architecture is a feasible solution in terms of high-performance and area-efficient architecture. Full article
(This article belongs to the Special Issue Advanced Internet of Things for Smart Infrastructure System)
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Open AccessArticle Effects of Viewing Displays from Different Distances on Human Visual System
Appl. Sci. 2017, 7(11), 1153; doi:10.3390/app7111153
Received: 3 October 2017 / Revised: 1 November 2017 / Accepted: 6 November 2017 / Published: 9 November 2017
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Abstract
The current stereoscopic 3D displays have several human-factor issues including visual-fatigue symptoms such as eyestrain, headache, fatigue, nausea, and malaise. The viewing time and viewing distance are factors that considerably affect the visual fatigue associated with 3D displays. Hence, this study analyzes the
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The current stereoscopic 3D displays have several human-factor issues including visual-fatigue symptoms such as eyestrain, headache, fatigue, nausea, and malaise. The viewing time and viewing distance are factors that considerably affect the visual fatigue associated with 3D displays. Hence, this study analyzes the effects of display type (2D vs. 3D) and viewing distance on visual fatigue during a 60-min viewing session based on electroencephalogram (EEG) relative beta power, and alpha/beta power ratio. In this study, twenty male participants watched four videos. The EEGs were recorded at two occipital lobes (O1 and O2) of each participant in the pre-session (3 min), post-session (3 min), and during a 60-min viewing session. The results showed that the decrease in relative beta power of the EEG and the increase in the alpha/beta ratio from the start until the end of the viewing session were significantly higher when watching the 3D display. When the viewing distance was increased from 1.95 m to 3.90 m, the visual fatigue was decreased in the case of the 3D-display, whereas the fatigue was increased in the case of the 2D-display. Moreover, there was approximately the same level of visual fatigue when watching videos in 2D or 3D from a long viewing distance (3.90 m). Full article
(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)
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Open AccessArticle Stochastic Unit Commitment of Wind-Integrated Power System Considering Air-Conditioning Loads for Demand Response
Appl. Sci. 2017, 7(11), 1154; doi:10.3390/app7111154
Received: 3 October 2017 / Revised: 25 October 2017 / Accepted: 6 November 2017 / Published: 10 November 2017
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Abstract
As a result of extensive penetration of wind farms into electricity grids, power systems face enormous challenges in daily operation because of the intermittent characteristics of wind energy. In particular, the load peak-valley gap has been dramatically widened in wind energy-integrated power systems.
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As a result of extensive penetration of wind farms into electricity grids, power systems face enormous challenges in daily operation because of the intermittent characteristics of wind energy. In particular, the load peak-valley gap has been dramatically widened in wind energy-integrated power systems. How to quickly and efficiently meet the peak-load demand has become an issue to practitioners. Previous literature has illustrated that the demand response (DR) is an important mechanism to direct customer usage behaviors and reduce the peak load at critical times. This paper introduces air-conditioning loads (ACLs) as a load shedding measure in the DR project. On the basis of the equivalent thermal parameter model for ACLs and the state-queue control method, a compensation cost calculation method for the ACL to shift peak load is proposed. As a result of the fluctuation and uncertainty of wind energy, a two-stage stochastic unit commitment (UC) model is developed to analyze the ACL users’ response in the wind-integrated power system. A simulation study on residential and commercial ACLs has been performed on a 10-generator test system. The results illustrate the feasibility of the proposed stochastic programming strategy and that the system peak load can be effectively reduced through the participation of ACL users in DR projects. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Preparation and Properties of Asphalt Binders Modified by THFS Extracted From Direct Coal Liquefaction Residue
Appl. Sci. 2017, 7(11), 1155; doi:10.3390/app7111155
Received: 3 October 2017 / Revised: 31 October 2017 / Accepted: 3 November 2017 / Published: 10 November 2017
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Abstract
This paper aims to study the preparation and viscoelastic properties of asphalt binder modified by tetrahydrofuran soluble fraction (THFS) extracted from direct coal liquefaction residue. The modified asphalt binders, which blended with SK-90 (control asphalt binder) and 4%, 6%, 8% and 10% THFS
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This paper aims to study the preparation and viscoelastic properties of asphalt binder modified by tetrahydrofuran soluble fraction (THFS) extracted from direct coal liquefaction residue. The modified asphalt binders, which blended with SK-90 (control asphalt binder) and 4%, 6%, 8% and 10% THFS (by weight of SK-90), were fabricated. The preparation process for asphalt binder was optimized in terms of the orthogonal array test strategy and gray correlation analysis results. The properties of asphalt binder were measured by applying Penetration performance grade and Superpave performance grade specifications. In addition, the temperature step and frequency sweep test in Dynamic Shear Rheometer were conducted to predict the rheological behavior, temperature and frequency susceptibility of asphalt binder. The test results suggested the optimal preparation process, such as 150 °C shearing temperature, 45 min shearing time and 4000 rpm shearing rate. Subsequently, the addition of THFS was beneficial in increasing the high-temperature properties but decreased the low-temperature properties and resistance to fatigue. The content analysis of THFS showed the percentage of 4~6% achieved a balance in the high-and-low temperature properties of asphalt binder. The asphalt binder with higher THFS content exhibited higher resistance to rutting and less sensitivity to frequency and temperature. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Automated Defect Recognition as a Critical Element of a Three Dimensional X-ray Computed Tomography Imaging-Based Smart Non-Destructive Testing Technique in Additive Manufacturing of Near Net-Shape Parts
Appl. Sci. 2017, 7(11), 1156; doi:10.3390/app7111156
Received: 4 September 2017 / Revised: 2 November 2017 / Accepted: 3 November 2017 / Published: 10 November 2017
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Abstract
In this paper, a state of the art automated defect recognition (ADR) system is presented that was developed specifically for Non-Destructive Testing (NDT) of powder metallurgy (PM) parts using three dimensional X-ray Computed Tomography (CT) imaging, towards enabling online quality assurance and enhanced
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In this paper, a state of the art automated defect recognition (ADR) system is presented that was developed specifically for Non-Destructive Testing (NDT) of powder metallurgy (PM) parts using three dimensional X-ray Computed Tomography (CT) imaging, towards enabling online quality assurance and enhanced integrity confidence. PM parts exhibit typical defects such as microscopic cracks, porosity, and voids, internal to components that without an effective detection system, limit the growth of industrial applications. Compared to typical testing methods (e.g., destructive such as metallography that is based on sampling, cutting, and polishing of parts), CT provides full coverage of defect detection. This paper establishes the importance and advantages of an automated NDT system for the PM industry applications with particular emphasis on image processing procedures for defect recognition. Moreover, the article describes how to establish a reference library based on real 3D X-ray CT images of net-shape parts. The paper follows the development of the ADR system from processing 2D image slices of a measured 3D X-ray image to processing the complete 3D X-ray image as a whole. The introduced technique is successfully integrated into an automated in-line quality control system highly sought by major industry sectors in Oil and Gas, Automotive, and Aerospace. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Impact of Graphene on the Polarizability of a Neighbour Nanoparticle: A Dyadic Green’s Function Study
Appl. Sci. 2017, 7(11), 1158; doi:10.3390/app7111158
Received: 15 October 2017 / Revised: 7 November 2017 / Accepted: 9 November 2017 / Published: 11 November 2017
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Abstract
We discuss the renormalization of the polarizability of a nanoparticle in the presence of either: (1) a continuous graphene sheet; or (2) a plasmonic graphene grating, taking into account retardation effects. Our analysis demonstrates that the excitation of surface plasmon polaritons in graphene
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We discuss the renormalization of the polarizability of a nanoparticle in the presence of either: (1) a continuous graphene sheet; or (2) a plasmonic graphene grating, taking into account retardation effects. Our analysis demonstrates that the excitation of surface plasmon polaritons in graphene produces a large enhancement of the real and imaginary parts of the renormalized polarizability. We show that the imaginary part can be changed by a factor of up to 100 relative to its value in the absence of graphene. We also show that the resonance in the case of the grating is narrower than in the continuous sheet. In the case of the grating it is shown that the resonance can be tuned by changing the grating geometric parameters. Full article
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Open AccessArticle Micro-Focusing of Broadband High-Order Harmonic Radiation by a Double Toroidal Mirror
Appl. Sci. 2017, 7(11), 1159; doi:10.3390/app7111159
Received: 10 October 2017 / Revised: 2 November 2017 / Accepted: 7 November 2017 / Published: 12 November 2017
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Abstract
We present an optical system based on two toroidal mirrors in a Wolter configuration to focus broadband extreme ultraviolet (XUV) radiation. Optimization of the focusing optics alignment is carried out with the aid of an XUV wavefront sensor. Back-propagation of the optimized wavefront
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We present an optical system based on two toroidal mirrors in a Wolter configuration to focus broadband extreme ultraviolet (XUV) radiation. Optimization of the focusing optics alignment is carried out with the aid of an XUV wavefront sensor. Back-propagation of the optimized wavefront to the focus yields a focal spot of 3.6 × 4.0 µm2 full width at half maximum, which is consistent with ray-tracing simulations that predict a minimum size of 3.0 × 3.2 µm2. This work is important for optimizing the intensity of focused high-order harmonics in order to reach the nonlinear interaction regime. Full article
(This article belongs to the Special Issue Advanced EUV and X-Ray Optics)
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Open AccessArticle Machine Learning for Identifying Demand Patterns of Home Energy Management Systems with Dynamic Electricity Pricing
Appl. Sci. 2017, 7(11), 1160; doi:10.3390/app7111160
Received: 16 October 2017 / Revised: 4 November 2017 / Accepted: 6 November 2017 / Published: 12 November 2017
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Abstract
Energy management plays a crucial role in providing necessary system flexibility to deal with the ongoing integration of volatile and intermittent energy sources. Demand Response (DR) programs enhance demand flexibility by communicating energy market price volatility to the end-consumer. In such environments, home
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Energy management plays a crucial role in providing necessary system flexibility to deal with the ongoing integration of volatile and intermittent energy sources. Demand Response (DR) programs enhance demand flexibility by communicating energy market price volatility to the end-consumer. In such environments, home energy management systems assist the use of flexible end-appliances, based upon the individual consumer’s personal preferences and beliefs. However, with the latter heterogeneously distributed, not all dynamic pricing schemes are equally adequate for the individual needs of households. We conduct one of the first large scale natural experiments, with multiple dynamic pricing schemes for end consumers, allowing us to analyze different demand behavior in relation with household attributes. We apply a spectral relaxation clustering approach to show distinct groups of households within the two most used dynamic pricing schemes: Time-Of-Use and Real-Time Pricing. The results indicate that a more effective design of smart home energy management systems can lead to a better fit between customer and electricity tariff in order to reduce costs, enhance predictability and stability of load and allow for more optimal use of demand flexibility by such systems. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Thickness Dependence of Switching Behavior in Ferroelectric BiFeO3 Thin Films: A Phase-Field Simulation
Appl. Sci. 2017, 7(11), 1162; doi:10.3390/app7111162
Received: 26 September 2017 / Revised: 23 October 2017 / Accepted: 6 November 2017 / Published: 13 November 2017
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Abstract
A phase-field approach to the analysis of the thickness effects in electric-field-induced domain switching in BiFeO3 thin films has been formulated. Time evolutions of domain switching percentage for films with different thicknesses were explored to reveal the primary switching path and its
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A phase-field approach to the analysis of the thickness effects in electric-field-induced domain switching in BiFeO3 thin films has been formulated. Time evolutions of domain switching percentage for films with different thicknesses were explored to reveal the primary switching path and its dependence on film thickness. In addition, hysteresis loop for these films were calculated to obtain their coercive fields. Results show a nonlinear thickness dependence of coercive field for ultrathin films. A parametric study of the interactions between film thickness, coercive field, current-voltage (I-V) response, and polarization switching behavior is herein discussed, which could provide physical insights into materials engineering. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Experimental Study of Real-Time Classification of 17 Voluntary Movements for Multi-Degree Myoelectric Prosthetic Hand
Appl. Sci. 2017, 7(11), 1163; doi:10.3390/app7111163
Received: 4 October 2017 / Revised: 31 October 2017 / Accepted: 8 November 2017 / Published: 13 November 2017
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Abstract
The myoelectric prosthetic hand is a powerful tool developed to help people with upper limb loss restore the functions of a biological hand. Recognizing multiple hand motions from only a few electromyography (EMG) sensors is one of the requirements for the development of
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The myoelectric prosthetic hand is a powerful tool developed to help people with upper limb loss restore the functions of a biological hand. Recognizing multiple hand motions from only a few electromyography (EMG) sensors is one of the requirements for the development of prosthetic hands with high level of usability. This task is highly challenging because both classification rate and misclassification rate worsen with additional hand motions. This paper presents a signal processing technique that uses spectral features and an artificial neural network to classify 17 voluntary movements from EMG signals. The main highlight will be on the use of a small set of low-cost EMG sensor for classification of a reasonably large number of hand movements. The aim of this work is to extend the capabilities to recognize and produce multiple movements beyond what is currently feasible. This work will also show and discuss about how tailoring the number of hand motions for a specific task can help develop a more reliable prosthetic hand system. Online classification experiments have been conducted on seven male and five female participants to evaluate the validity of the proposed method. The proposed algorithm achieves an overall correct classification rate of up to 83%, thus, demonstrating the potential to classify 17 movements from 6 EMG sensors. Furthermore, classifying 9 motions using this method could achieve an accuracy of up to 92%. These results show that if the prosthetic hand is intended for a specific task, limiting the number of motions can significantly increase the performance and usability. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Interpretation US Elastography in Chronic Hepatitis B with or without Anti-HBV Therapy
Appl. Sci. 2017, 7(11), 1164; doi:10.3390/app7111164
Received: 15 September 2017 / Revised: 29 October 2017 / Accepted: 30 October 2017 / Published: 13 November 2017
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Abstract
Inflammation has significant impacts on liver fibrosis measurement by ultrasound elastography. The interpretation requires further optimization in patients with or without anti-viral therapy. We prospectively enrolled a consecutive series of patients with chronic hepatitis B who received liver histology analysis and acoustic radiation
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Inflammation has significant impacts on liver fibrosis measurement by ultrasound elastography. The interpretation requires further optimization in patients with or without anti-viral therapy. We prospectively enrolled a consecutive series of patients with chronic hepatitis B who received liver histology analysis and acoustic radiation force impulse (ARFI). 146 patients who underwent liver biopsy (50.9%) or tumor resection (49.1%) were enrolled. 34 patients (23.3%) had been receiving anti-hepatitis B therapy of various duration. The areas under the receiver-operating characteristic (AUROC) for the diagnosis of Metavir F4 by mean ARFI was 0.820 in the non-treatment group and 0.796 in the treatment group. The ARFI tended to be not lower (100%) than the corresponding Metavir grading in patients with treatment within 12 months, equal (75%) from 13 to 31 months, and lower (71.4%) after 32 months. We conclude that ARFI is a reliable tool for measurement of liver fibrosis in chronic hepatitis B patients with ALT (alanine aminotransferase) <5x the upper limit of normal. For those patients under anti-HBV therapy, the optimal timing for ARFI analysis will be over 1–2.5 years of nucleos(t)ide analogue therapy. The ARFI measurement after 2.5 years tends to be lower than the corresponding histology grading. Full article
(This article belongs to the Special Issue Ultrasound Elastography)
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Open AccessArticle Atmospheric Attenuation Correction Based on a Constant Reference for High-Precision Infrared Radiometry
Appl. Sci. 2017, 7(11), 1165; doi:10.3390/app7111165
Received: 11 September 2017 / Revised: 6 November 2017 / Accepted: 9 November 2017 / Published: 13 November 2017
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Abstract
Infrared (IR) radiometry technology is an important method for characterizing the IR signature of targets, such as aircrafts or rockets. However, the received signal of targets could be reduced by a combination of atmospheric molecule absorption and aerosol scattering. Therefore, atmospheric correction is
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Infrared (IR) radiometry technology is an important method for characterizing the IR signature of targets, such as aircrafts or rockets. However, the received signal of targets could be reduced by a combination of atmospheric molecule absorption and aerosol scattering. Therefore, atmospheric correction is a requisite step for obtaining the real radiance of targets. Conventionally, the atmospheric transmittance and the air path radiance are calculated by an atmospheric radiative transfer calculation software. In this paper, an improved IR radiometric method based on constant reference correction of atmospheric attenuation is proposed. The basic principle and procedure of this method are introduced, and then the linear model of high-speed calibration in consideration of the integration time is employed and confirmed, which is then applicable in various complex conditions. To eliminate stochastic errors, radiometric experiments were conducted for multiple integration times. Finally, several experiments were performed on a mid-wave IR system with Φ600 mm aperture. The radiometry results indicate that the radiation inversion precision of the novel method is 4.78–4.89%, while the precision of the conventional method is 10.86–13.81%. Full article
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Open AccessArticle Numerical Characterisation of Active Drag and Lift Control for a Circular Cylinder in Cross-Flow
Appl. Sci. 2017, 7(11), 1166; doi:10.3390/app7111166
Received: 11 September 2017 / Revised: 31 October 2017 / Accepted: 8 November 2017 / Published: 13 November 2017
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Abstract
Synthetic jet actuators have shown promise to control drag and lift for a bluff body in cross-flow. Using unsteady RANS CFD modelling, a significant modification of the drag coefficient for a circular cylinder in cross-flow at Re = 3900 is achieved by
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Synthetic jet actuators have shown promise to control drag and lift for a bluff body in cross-flow. Using unsteady RANS CFD modelling, a significant modification of the drag coefficient for a circular cylinder in cross-flow at R e = 3900 is achieved by varying the actuation frequency. The variation in actuation frequency corresponds to a range in Stokes number of 2.4 < S t o < 6.4. The trends in drag coefficient modification largely agree with the findings of past publications, achieving a maximum drag reduction at S t o = 4.9 for a fixed jet Reynolds number of the synthetic jet of R e U ¯ o = 12. A decrease in the adverse pressure gradient near the jet orifice correlated with a momentum increase in the viscous sublayer and stronger vortical structures at the rear of the cylinder. In these same conditions, a decrease in turbulence intensity was observed in the far field wake, which is a relevant finding in the context of wind and tidal turbine arrays. Full article
(This article belongs to the Special Issue Active Flow Control Technologies for Energy and Propulsive Systems)
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Open AccessArticle Design and Characterization of a Birefringent-Type Compact Displacement Sensor for Improving Measurement Sensitivity by a Guided-Wave Beam
Appl. Sci. 2017, 7(11), 1167; doi:10.3390/app7111167
Received: 14 October 2017 / Revised: 28 October 2017 / Accepted: 6 November 2017 / Published: 14 November 2017
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Abstract
A compact displacement sensor (CDS) fabricated with the combinations of a birefringent KTP and cylindrical lens is proposed to be applied for optical displacement measurements in a common-path interferometer. To overcome the beam distortion issues of an original laser beam (OLB) in the
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A compact displacement sensor (CDS) fabricated with the combinations of a birefringent KTP and cylindrical lens is proposed to be applied for optical displacement measurements in a common-path interferometer. To overcome the beam distortion issues of an original laser beam (OLB) in the small radius of the lens, a guided-wave beam (GWB) is proposed to demonstrate that the GWB (having better measurement characteristics than the OLB) is essential to achieve the improved sensitivity of displacement measurements performed by the CDS. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Structural Performance Optimization and Verification of an Improved Thin-Walled Storage Tank for a Pico-Satellite
Appl. Sci. 2017, 7(11), 1168; doi:10.3390/app7111168
Received: 16 October 2017 / Revised: 7 November 2017 / Accepted: 9 November 2017 / Published: 14 November 2017
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Abstract
This paper presents an improved mesh storage tank structure obtained using 3D metal printing. The storage tank structure is optimized using a multi-objective uniform design method. Each parameter influencing the storage tank is considered as the optimization factor, and the compression stress (
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This paper presents an improved mesh storage tank structure obtained using 3D metal printing. The storage tank structure is optimized using a multi-objective uniform design method. Each parameter influencing the storage tank is considered as the optimization factor, and the compression stress ( σ ), volume utilization ratio ( v ), and weight ( m , are considered as the optimization objectives. Regression equations were established between the optimization factors and targets, the orders of the six factors affecting three target values are analyzed, and the relative deviations between the regression equation and calculation results for σ , v , and m were 9.72%, 4.15%, and 2.94%, respectively. The optimization results showed that the regression equations can predict the structure performance of the improved storage tank, and the values of the influence factors obtained through the optimization are effective. In addition, the compression stress was improved by 24.98%, the volume utilization ratio was increased by 26.86%, and the weight was reduced by 26.83%. The optimized storage tank was developed through 3D metal printing, and the compressive stress was improved by 58.71%, the volume utilization ratio was increased by 24.52%, and the weight was reduced by 11.67%. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Energy-Neutral Data Collection Rate Control for IoT Animal Behavior Monitors
Appl. Sci. 2017, 7(11), 1169; doi:10.3390/app7111169
Received: 19 October 2017 / Revised: 5 November 2017 / Accepted: 7 November 2017 / Published: 14 November 2017
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Abstract
Energy-neutral operation (ENO) is a major concern for Internet of things (IoT) sensor systems. Animals can be tagged with IoT sensors to monitor their movement and behavior. These sensors wirelessly upload collected data and can receive parameters to change their operation. Typically, the
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Energy-neutral operation (ENO) is a major concern for Internet of things (IoT) sensor systems. Animals can be tagged with IoT sensors to monitor their movement and behavior. These sensors wirelessly upload collected data and can receive parameters to change their operation. Typically, the behavior monitors are powered by a battery where the system relies upon harvesting solar radiation for sustainable operation. Solar panels typically are used as the harvesting mechanism and can have a level of uncertainty regarding consistent energy delivery due to factors such as adverse weather, foliage, time of day, and individual animal behavior. The variability of available energy inevitably creates a trade-off in the rate at which data can be collected with respect to incoming and stored energy. The objective of this research was to investigate and simulate methods and parameters that can control the data collection rate of an IoT behavior monitor to achieve sustained operation with unknown and random energy harvesting. Analysis and development of a control system were performed by creating a software model of energy consumption and then simulating using different initial conditions and random energy harvesting rates for evaluation. The contribution of this effort was the exploration into the usage of a discrete-time gain scheduled Proportional–Integral–Derivative (PID) that was tuned to a specific device configuration, using battery state of charge as an input, and found to maintain a battery level set-point, reject small solar harvesting energy disturbances, and maintain a consistent data collection rate throughout the day. Full article
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Open AccessArticle Backstepping Based Formation Control of Quadrotors with the State Transformation Technique
Appl. Sci. 2017, 7(11), 1170; doi:10.3390/app7111170
Received: 4 October 2017 / Revised: 3 November 2017 / Accepted: 8 November 2017 / Published: 14 November 2017
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Abstract
In this paper, a backstepping-based formation control of quadrotors with the state transformation technique is proposed. First, the dynamics of a quadrotor is derived by using the Newton–Euler formulation. Next, a backstepping-based formation control for quadrotors using a state transformation technique is presented.
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In this paper, a backstepping-based formation control of quadrotors with the state transformation technique is proposed. First, the dynamics of a quadrotor is derived by using the Newton–Euler formulation. Next, a backstepping-based formation control for quadrotors using a state transformation technique is presented. In the position control, which is the basis of formation control, it is possible to derive the reference attitude angles employing a state transformation technique without the small angle assumption or the simplified dynamics usually used. Stability analysis based on the Lyapunov theorem shows that the proposed formation controller can provide a quadrotor formation error system that is asymptotically stabilized. Finally, we verify the performance of the proposed formation control method through comparison simulations. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Simulation of Magnetically-Actuated Functional Gradient Nanocomposites
Appl. Sci. 2017, 7(11), 1171; doi:10.3390/app7111171
Received: 14 September 2017 / Revised: 13 November 2017 / Accepted: 10 November 2017 / Published: 14 November 2017
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Abstract
Magnetically-actuated functional gradient nanocomposites can be locally modulated to generate unprecedented mechanical gradients that can be applied to various interfaces and surfaces through following the design principles of natural biological materials. However, a key question is how to modulate the concentration of magnetic
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Magnetically-actuated functional gradient nanocomposites can be locally modulated to generate unprecedented mechanical gradients that can be applied to various interfaces and surfaces through following the design principles of natural biological materials. However, a key question is how to modulate the concentration of magnetic particles using an external magnetic field. Here, we propose a model to obtain the gradient concentration distribution of magnetic particles and mechanical gradients. The results show that three states exist when the magnetic force changes in the z direction, including the unchanging state, the stable gradient state, and the over-accumulation state, which are consistent with experiment results. If both radial and axial magnetic forces are present, the inhomogeneity of magnetic–particle distribution in two dimensions was found to break the functional gradient. Furthermore, the size effects of a functional gradient sample were studied, which indicated that adjusting the magnetic force and diffusion constant would enable larger nanocomposites samples to generate functional gradients. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Enhanced Prognostic Model for Lithium Ion Batteries Based on Particle Filter State Transition Model Modification
Appl. Sci. 2017, 7(11), 1172; doi:10.3390/app7111172
Received: 12 September 2017 / Accepted: 7 November 2017 / Published: 15 November 2017
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Abstract
This paper focuses on predicting the End of Life and End of Discharge of Lithium ion batteries using a battery capacity fade model and a battery discharge model. The proposed framework will be able to estimate the Remaining Useful Life (RUL) and the
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This paper focuses on predicting the End of Life and End of Discharge of Lithium ion batteries using a battery capacity fade model and a battery discharge model. The proposed framework will be able to estimate the Remaining Useful Life (RUL) and the Remaining charge through capacity fade and discharge models. A particle filter is implemented that estimates the battery’s State of Charge (SOC) and State of Life (SOL) by utilizing the battery’s physical data such as voltage, temperature, and current measurements. The accuracy of the prognostic framework has been improved by enhancing the particle filter state transition model to incorporate different environmental and loading conditions without retuning the model parameters. The effect of capacity fade in the reduction of the EOD (End of Discharge) time with cycling has also been included, integrating both EOL (End of Life) and EOD prediction models in order to get more accuracy in the estimations. Full article
(This article belongs to the Special Issue Battery Management and State Estimation)
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Open AccessArticle Large Scale Community Detection Using a Small World Model
Appl. Sci. 2017, 7(11), 1173; doi:10.3390/app7111173
Received: 27 September 2017 / Revised: 1 November 2017 / Accepted: 2 November 2017 / Published: 15 November 2017
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Abstract
In a social network, small or large communities within the network play a major role in deciding the functionalities of the network. Despite of diverse definitions, communities in the network may be defined as the group of nodes that are more densely connected
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In a social network, small or large communities within the network play a major role in deciding the functionalities of the network. Despite of diverse definitions, communities in the network may be defined as the group of nodes that are more densely connected as compared to nodes outside the group. Revealing such hidden communities is one of the challenging research problems. A real world social network follows small world phenomena, which indicates that any two social entities can be reachable in a small number of steps. In this paper, nodes are mapped into communities based on the random walk in the network. However, uncovering communities in large-scale networks is a challenging task due to its unprecedented growth in the size of social networks. A good number of community detection algorithms based on random walk exist in literature. In addition, when large-scale social networks are being considered, these algorithms are observed to take considerably longer time. In this work, with an objective to improve the efficiency of algorithms, parallel programming framework like Map-Reduce has been considered for uncovering the hidden communities in social network. The proposed approach has been compared with some standard existing community detection algorithms for both synthetic and real-world datasets in order to examine its performance, and it is observed that the proposed algorithm is more efficient than the existing ones. Full article
(This article belongs to the Special Issue Socio-Cognitive and Affective Computing)
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Open AccessFeature PaperArticle Sound Synthesis of Objects Swinging through Air Using Physical Models
Appl. Sci. 2017, 7(11), 1177; doi:10.3390/app7111177
Received: 12 October 2017 / Accepted: 10 November 2017 / Published: 16 November 2017
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Abstract
A real-time physically-derived sound synthesis model is presented that replicates the sounds generated as an object swings through the air. Equations obtained from fluid dynamics are used to determine the sounds generated while exposing practical parameters for a user or game engine to
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A real-time physically-derived sound synthesis model is presented that replicates the sounds generated as an object swings through the air. Equations obtained from fluid dynamics are used to determine the sounds generated while exposing practical parameters for a user or game engine to vary. Listening tests reveal that for the majority of objects modelled, participants rated the sounds from our model as plausible as actual recordings. The sword sound effect performed worse than others, and it is speculated that one cause may be linked to the difference between expectations of a sound and the actual sound for a given object. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle Modified Local Linear Embedding Algorithm for Rolling Element Bearing Fault Diagnosis
Appl. Sci. 2017, 7(11), 1178; doi:10.3390/app7111178
Received: 11 September 2017 / Revised: 14 November 2017 / Accepted: 13 November 2017 / Published: 15 November 2017
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Abstract
Due to the noise accompanied with rolling element bearing fault signal, it can reduce the accuracy of faulty diagnoses. In order to improve the robustness of a faulty diagnosis, this study proposed a fault diagnosis model based on modified local linear embedding (M-LLE)
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Due to the noise accompanied with rolling element bearing fault signal, it can reduce the accuracy of faulty diagnoses. In order to improve the robustness of a faulty diagnosis, this study proposed a fault diagnosis model based on modified local linear embedding (M-LLE) algorithm. Aiming at the characteristics of rolling element bearing fault data, the vibration signal was first analyzed in time domain and frequency domain to construct high dimension eigenvectors. Next, the high-dimensional eigenvectors can be reduced to low-dimensional eigenvectors by M-LLE algorithm. In the M-LLE algorithm, the Mahalanobis distance (MD) metric is adopted to replace Euclidean distance in traditional neighborhood construction and L1-norm is used to standardize weight matrix, which can enhance the anti-noise ability of the Local Linear Embedding (LLE) algorithm. Finally, fault diagnosis results can be obtained when low-dimensional rolling element bearing fault data is classified by K-Nearest Neighbor (KNN) classifier. By simulating the noisy artificial data sets in different degrees, the proposed algorithm can get the perfect local structure of manifolds. The effectiveness of M-LLE algorithm can be proved. In addition, experimental results of real rolling element bearing data which provided by the University of Cincinnati show that the accuracies of all kinds of faults can reach 100%. It can be deemed that the proposed fault diagnosis model can effectively improve the accuracy of fault diagnosis. Full article
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Open AccessArticle Determination of the Constants of GTN Damage Model Using Experiment, Polynomial Regression and Kriging Methods
Appl. Sci. 2017, 7(11), 1179; doi:10.3390/app7111179
Received: 8 October 2017 / Revised: 9 November 2017 / Accepted: 10 November 2017 / Published: 15 November 2017
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Abstract
Damage models, particularly the Gurson–Tvergaard–Needleman (GTN) model, are widely used in numerical simulation of material deformations. Each damage model has some constants which must be identified for each material. The direct identification methods are costly and time consuming. In the current work, a
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Damage models, particularly the Gurson–Tvergaard–Needleman (GTN) model, are widely used in numerical simulation of material deformations. Each damage model has some constants which must be identified for each material. The direct identification methods are costly and time consuming. In the current work, a combination of experimental, numerical simulation and optimization were used to determine the constants. Quasi-static and dynamic tests were carried out on notched specimens. The experimental profiles of the specimens were used to determine the constants. The constants of GTN damage model were identified through the proposed method and using the results of quasi-static tests. Numerical simulation of the dynamic test was performed utilizing the constants obtained from quasi-static experiments. The results showed a high precision in predicting the specimen’s profile in the dynamic testing. The sensitivity analysis was performed on the constants of GTN model to validate the proposed method. Finally, the experiments were simulated using the Johnson–Cook (J–C) damage model and the results were compared to those obtained from GTN damage model. Full article
(This article belongs to the Special Issue Soft Computing Techniques in Structural Engineering and Materials)
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Open AccessArticle Performance of Time Reversal Based Underwater Target Detection in Shallow Water
Appl. Sci. 2017, 7(11), 1180; doi:10.3390/app7111180
Received: 30 September 2017 / Accepted: 13 November 2017 / Published: 16 November 2017
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Abstract
In this paper, a scheme based on the time reversal technique is proposed to improve the detection performance for detecting a cylindrical object bottoming at the seafloor in shallow water. When the time reversal technique is applied to the response of the clutter
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In this paper, a scheme based on the time reversal technique is proposed to improve the detection performance for detecting a cylindrical object bottoming at the seafloor in shallow water. When the time reversal technique is applied to the response of the clutter with the strong time-varying characteristic of shallow water, it is difficult to obtain a high peak response. However, in the case where a cylindrical object is placed on the seafloor because the time-invariant property of the target response is stronger than the time-varying property of the reverberation by the clutters, the time reversal technique can be applied to enhance the target signal. In this paper, it is demonstrated that the peak due to the target that is contacted at the seabed becomes higher when applying the time reversal technique. The performance is investigated by using numerical computation of the probability of detection for various probabilities of false alarm and computer simulation. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Viscoelastic Dampers for Rotors: Modeling and Validation at Component and System Level
Appl. Sci. 2017, 7(11), 1181; doi:10.3390/app7111181
Received: 20 October 2017 / Revised: 10 November 2017 / Accepted: 13 November 2017 / Published: 16 November 2017
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Abstract
The aim of this paper is to propose a methodology for the modelling, testing, and the parameter identification of viscoelastic supports for rotating machines at the component and system level. Although the use of this type of dampers is common in rotordynamic applications,
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The aim of this paper is to propose a methodology for the modelling, testing, and the parameter identification of viscoelastic supports for rotating machines at the component and system level. Although the use of this type of dampers is common in rotordynamic applications, the strict dependence on the working frequency of the material parameters makes their behavior hard to predict and recommends grounding the design on experimental data of the characteristics. A dedicated test rig is adopted to characterize the supports and validate the modelling approach at component level. A parameter identification procedure is carried out from the experimental results to extract the mechanical properties of the supports. To this end, a Genetic Algorithm (GA) is adopted to search the most fitting values of damping and stiffness of the reference model. The choice of GA is motivated by the need of adopting a technique that can be easily implemented on industrial control units, being that the dedicated machine is supposed to be used in production lines for testing procedures. The results are obtained in terms of complex stiffness as a function of the frequency and are then translated in classical stiffness and damping components that are commonly used in rotordynamics. Afterwards, they are introduced in the model of a turbo-molecular pump adopted as a case study to evaluate the correctness of the proposed methodology at system level at stand-still and with the pump in rotation. The proposed approach is effective, showing a good match between the numerical model and the experimental results even with a relatively low order model of the viscoelastic supports and on a complex rotordynamic system. Full article
(This article belongs to the Section Acoustics)