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Appl. Sci., Volume 7, Issue 12 (December 2017)

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Open AccessArticle LPaMI: A Graph-Based Lifestyle Pattern Mining Application Using Personal Image Collections in Smartphones
Appl. Sci. 2017, 7(12), 1200; doi:10.3390/app7121200
Received: 10 October 2017 / Revised: 25 November 2017 / Accepted: 17 November 2017 / Published: 27 November 2017
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Abstract
Normally, individuals use smartphones for a variety of purposes like photography, schedule planning, playing games, and so on, apart from benefiting from the core tasks of call-making and short messaging. These services are sources of personal data generation. Therefore, any application that utilises
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Normally, individuals use smartphones for a variety of purposes like photography, schedule planning, playing games, and so on, apart from benefiting from the core tasks of call-making and short messaging. These services are sources of personal data generation. Therefore, any application that utilises personal data of a user from his/her smartphone is truly a great witness of his/her interests and this information can be used for various personalised services. In this paper, we present Lifestyle Pattern MIning (LPaMI), which is a personalised application for mining the lifestyle patterns of a smartphone user. LPaMI uses the personal photograph collections of a user, which reflect the day-to-day photos taken by a smartphone, to recognise scenes (called objects of interest in our work). These are then mined to discover lifestyle patterns. The uniqueness of LPaMI lies in our graph-based approach to mining the patterns of interest. Modelling of data in the form of graphs is effective in preserving the lifestyle behaviour maintained over the passage of time. Graph-modelled lifestyle data enables us to apply variety of graph mining techniques for pattern discovery. To demonstrate the effectiveness of our proposal, we have developed a prototype system for LPaMI to implement its end-to-end pipeline. We have also conducted an extensive evaluation for various phases of LPaMI using different real-world datasets. We understand that the output of LPaMI can be utilised for variety of pattern discovery application areas like trip and food recommendations, shopping, and so on. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Low-Complexity QRD-M with Path Eliminations in MIMO-OFDM Systems
Appl. Sci. 2017, 7(12), 1206; doi:10.3390/app7121206
Received: 18 September 2017 / Revised: 21 November 2017 / Accepted: 21 November 2017 / Published: 23 November 2017
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Abstract
The QR decomposition-M algorithm (QRD-M) is a popular signal detector which has similar error performance with maximum likelihood (ML) in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The QRD-M uses M candidates at each layer, unlike the
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The QR decomposition-M algorithm (QRD-M) is a popular signal detector which has similar error performance with maximum likelihood (ML) in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The QRD-M uses M candidates at each layer, unlike the ML. However, the complexity of the QRD-M is high in huge MIMO-OFDM systems due to unnecessary survival paths at each layer. In this paper, a low-complexity QRD-M with variable number of survival paths at each layer is proposed. In the conventional QRD-M, path eliminations at the previous layer reduce the number of calculations for accumulated squared Euclidean distance (ASED) in subsequent layers. The proposed QRD-M eliminates unnecessary survival paths by comparing the ASED and the calculated threshold at each layer. The simulation results show that the proposed QRD-M maintains the error performance for the conventional QRD-M and has a very low complexity. Full article
(This article belongs to the Special Issue Advanced Internet of Things for Smart Infrastructure System)
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Open AccessArticle The Effect of Rice Straw Gasification Temperature on the Release and Occurrence Modes of Na and K in a Fluidized Bed
Appl. Sci. 2017, 7(12), 1207; doi:10.3390/app7121207
Received: 12 September 2017 / Accepted: 20 November 2017 / Published: 23 November 2017
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Abstract
Rice straw gasification was carried out in a laboratory fluidized bed reactor system from 600 to 800 °C in order to well-understand the release and occurrence mode of alkali metals as a function of temperature during the gasification process. Inductively coupled plasma atomic
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Rice straw gasification was carried out in a laboratory fluidized bed reactor system from 600 to 800 °C in order to well-understand the release and occurrence mode of alkali metals as a function of temperature during the gasification process. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was applied to analyze the original rice straw and obtained fly ash at different temperatures. The results show that the Water-Soluble, Ammonium acetate-Soluble, Hydrochloric acid-Soluble, and Aluminosilicate Combination-Soluble modes of the Na and K contents in rice straw decreased in sequence. The content of Water-Soluble salts of Na and K accounts for more than 50%, while the content of the Aluminosilicate Combination-Soluble mode is the lowest: less than 5%. The release rate of Na appears to be consistent but nonlinear, increasing with gasification conversion ranges between 50.2% and 70.8%, from which we can deduce that temperature is not the only factor that impacts Na emission. The release of K can be divided into two stages at 700 °C. At the first stage, the release rate of K is almost invariable, ranging from 23.3% to 26%. At the second stage, the release rate increases sharply: up to 55.9%. The concentration and the proportion of the Water-Soluble, Ammonium acetate-Soluble, and Hydrochloric acid-Soluble modes of Na in fly ash decrease with a temperature increase. The release of K can be explained as follows: one path is an organic form of K converted into its gaseous phase; the other path is a soluble inorganic form of K that is volatile at a high temperature. With a temperature increase, the Aluminosilicate Combination-Soluble mode of both Na and K increases. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Analysis of the Dynamic Wheel Loads in Railway Transition Zones Considering the Moisture Condition of the Ballast and Subballast
Appl. Sci. 2017, 7(12), 1208; doi:10.3390/app7121208
Received: 28 October 2017 / Revised: 20 November 2017 / Accepted: 21 November 2017 / Published: 23 November 2017
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Abstract
Transition zones in railway tracks are the locations with considerable changes in vertical support structures, e.g., near bridges. Due to possible water flow constrictions in transition zone structures, there is frequently an increased moisture level in the ballast/subballast layers, which is a potential
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Transition zones in railway tracks are the locations with considerable changes in vertical support structures, e.g., near bridges. Due to possible water flow constrictions in transition zone structures, there is frequently an increased moisture level in the ballast/subballast layers, which is a potential source of track degradation. This paper presents results of the moisture condition measured in three transition zones using ground penetrating radar, where the ballast/subballast are analyzed. The relationship between the moisture condition and track degradation in the transition zones is studied by comparing it to the longitudinal track level that is measured by the track inspection coaches. A strong connection is found between the high moisture condition and track degradation in the transition zones. The dynamic behavior of the transition zones with high moisture condition is analyzed using the Finite Element method. Differential stiffness and settlement are taken into consideration in the transition zone model, which is also coupled with a vehicle. The ballast/subballast layers are modelled as solid elements. Increased moisture conditions are considered as a reduction of elastic modulus, according to laboratory findings. Results show that high moisture leads to an increase of dynamic wheel loads in the transition zone, which explains the connection and confirms that the high moisture condition is a source of transition zone problems. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Methods to Evaluate the Aging Grades of Reclaimed Asphalt Binder
Appl. Sci. 2017, 7(12), 1209; doi:10.3390/app7121209
Received: 18 October 2017 / Revised: 15 November 2017 / Accepted: 20 November 2017 / Published: 23 November 2017
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Abstract
The use of reclaimed asphalt pavement (RAP) is of great significance for alleviating the problem of resource waste and land space occupation in the context of asphalt pavement. However, the use rate of RAP is still low in many countries because of limited
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The use of reclaimed asphalt pavement (RAP) is of great significance for alleviating the problem of resource waste and land space occupation in the context of asphalt pavement. However, the use rate of RAP is still low in many countries because of limited understanding and no unified recycling guidelines, especially in terms of materials classification and aging grades. In this study, reclaimed asphalt pavements from sixteen different sections in southern China were collected, including with base and polymer modified asphalt (PMA). The performance of the reclaimed asphalt binder (RAB) at low, average and high temperatures was tested, using various methods, to find suitable indexes for categorizing aging grades. The viscosity (135 °C) and penetration (25 °C) were found to distinguish the aging degree of RAB the most consistently, and served as the indices to classify the RAB into different grades. To simplify the evaluation of aging grades, a comprehensive service life was determined using the Analytic Hierarchy Process, taking service years and surface levels into account. As a result, a good correlation was found between comprehensive service life and the aging grades. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Simultaneous Dual-Arm Motion Planning for Minimizing Operation Time
Appl. Sci. 2017, 7(12), 1210; doi:10.3390/app7121210
Received: 23 October 2017 / Revised: 22 November 2017 / Accepted: 22 November 2017 / Published: 23 November 2017
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Abstract
Dual-arm robots are expected to perform work in a dynamic environment. One of the most basic tasks that a dual-arm robot does is pick-and-place work. However, this work is more complicated when there are several objects in the robot’s workspace. Additionally, it is
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Dual-arm robots are expected to perform work in a dynamic environment. One of the most basic tasks that a dual-arm robot does is pick-and-place work. However, this work is more complicated when there are several objects in the robot’s workspace. Additionally, it is likely to take a long time to finish the work as the number of objects increases. Therefore, we propose a method using a combination of two approaches to achieve efficient pick-and-place performance by a dual-arm robot to minimize its operation time. First, we use mixed integer linear programming (MILP) for the pick-and-place work to determine which arm should move an object and in which order these objects should be moved while considering the dual-arm robot’s operation range. Second, we plan the path using the rapidly exploring random tree so that the arms do not collide, enabling the robot to perform efficient pick-and-place work based on the MILP planning solution. The effectiveness of the proposed method is confirmed by simulations and experiments using an actual dual-arm robot. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle The Deep Belief and Self-Organizing Neural Network as a Semi-Supervised Classification Method for Hyperspectral Data
Appl. Sci. 2017, 7(12), 1212; doi:10.3390/app7121212
Received: 12 September 2017 / Accepted: 8 November 2017 / Published: 24 November 2017
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Abstract
Hyperspectral data is not linearly separable, and it has a high characteristic dimension. This paper proposes a new algorithm that combines a deep belief network based on the Boltzmann machine with a self-organizing neural network. The primary features of the hyperspectral image are
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Hyperspectral data is not linearly separable, and it has a high characteristic dimension. This paper proposes a new algorithm that combines a deep belief network based on the Boltzmann machine with a self-organizing neural network. The primary features of the hyperspectral image are extracted with a deep belief network. The weights of the network are fine-tuned using the labeled sample. Feature vectors extracted by the deep belief network are classified by a self-organizing neural network. The method reduces the spectral dimension of the data while preserving the large amount of original information in the data. The method overcomes the long training time required when using self-organizing neural networks for clustering, as well as the training difficulties of Deep Belief Networks (DBN) when the labeled sample size is small, thereby improving the accuracy and robustness of the semi-supervised classification. Simulation results show that the structure of the network can achieve higher classification accuracy when the labeled sample is deficient. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Comparative Exergoeconomic Evaluation of the Synthesis Routes for Methanol Production from Natural Gas
Appl. Sci. 2017, 7(12), 1213; doi:10.3390/app7121213
Received: 30 October 2017 / Accepted: 20 November 2017 / Published: 24 November 2017
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Abstract
Methanol is one of the most important feedstocks for the chemical, petrochemical, and energy industries. Abundant and widely distributed resources as well as a relative low price level make natural gas the predominant feedstock for methanol production. Indirect synthesis routes via reforming of
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Methanol is one of the most important feedstocks for the chemical, petrochemical, and energy industries. Abundant and widely distributed resources as well as a relative low price level make natural gas the predominant feedstock for methanol production. Indirect synthesis routes via reforming of methane suppress production from bio resources and other renewable alternatives. However, the conventional technology for the conversion of natural gas to methanol is energy intensive and costly in investment and operation. Three design cases with different reforming technologies in conjunction with an isothermal methanol reactor are investigated. Case I is equipped with steam methane reforming for a capacity of 2200 metric tons per day (MTPD). For a higher production capacity, a serial combination of steam reforming and autothermal reforming is used in Case II, while Case III deals with a parallel configuration of CO2 and steam reforming. A sensitivity analysis shows that the syngas composition significantly affects the thermodynamic performance of the plant. The design cases have exergetic efficiencies of 28.2%, 55.6% and 41.0%, respectively. The plants for higher capacity can produce at a competitive price, while the design in Case I is hardly economically feasible. An exergoeconomic analysis reveals a high cost impact of the reforming unit, air and syngas compressors. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Investigation of Heat Loss from the Finned Housing of the Electric Motor of a Vacuum Pump
Appl. Sci. 2017, 7(12), 1214; doi:10.3390/app7121214
Received: 30 September 2017 / Revised: 20 November 2017 / Accepted: 22 November 2017 / Published: 24 November 2017
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Abstract
Investigation of the heat transfer by conduction and convection through a finned housing of an electric motor rated 373 W operated in the drive unit of a vacuum pump was carried out. As the speed is changed, so is the velocity of air
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Investigation of the heat transfer by conduction and convection through a finned housing of an electric motor rated 373 W operated in the drive unit of a vacuum pump was carried out. As the speed is changed, so is the velocity of air flow, and consequently, the coefficient of heat transfer across the housing surface is changed too. To predict the values of the average heat transfer coefficient and to determine the heat flow that was dissipated at variable motor speed is a complex task, for which no reliable tools can be found in the literature. Using finite element approximation, the heat transfer was numerically simulated and the temperature distribution on the housing surface was determined. In order to validate the simulation model, an experimental set-up was assembled, including the vacuum pump complete with its driving unit, that is, electrical motor and frequency converter, and FLIR SC7600 thermovision camera. Using the validated simulation model, the heat flux transferred through the housing to the environment and the share of heat dissipation in the power consumed by the vacuum pump drive was determined. The combination of numerical simulation and thermographic measurements is an effective tool. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Effect of Various Silica Nanofluids: Reduction of Fines Migrations and Surface Modification of Berea Sandstone
Appl. Sci. 2017, 7(12), 1216; doi:10.3390/app7121216
Received: 7 November 2017 / Revised: 20 November 2017 / Accepted: 21 November 2017 / Published: 24 November 2017
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Abstract
This work is aimed at addressing surface modification of berea sandstone by silica nanofluids (NFs). Three types of nanofluids were used: silica/deionized water (DIW), silica in DIW with a stabilizer fluid (3-Mercaptopropyl Trimethoxysilane) and sulfonate-functionalized silica in DIW. Core flood studies showed that
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This work is aimed at addressing surface modification of berea sandstone by silica nanofluids (NFs). Three types of nanofluids were used: silica/deionized water (DIW), silica in DIW with a stabilizer fluid (3-Mercaptopropyl Trimethoxysilane) and sulfonate-functionalized silica in DIW. Core flood studies showed that application of silica nanoparticles (NPs) improved water injectivity in sandstone. The change in the measured zeta potential indicated surface modification of sandstone by application of NPs. Computation of the surface forces showed that the modified berea sandstone has net attractive potential with fines (obtained from water/rock interaction) leading to reduction of fines migration, hence improvement of water injectivity. It was also observed that the silica NPs have greater affinity to adhere/adsorb on quartz surfaces than kaolinite in berea core. This was confirmed by scanning electron microscope imaging and isothermal static adsorption tests. Although the stabilizing of NFs almost did not reduce the fine migration, as was qualitatively indicated by the pressure drop, it enhanced the NPs adsorption on the minerals as obtained by isothermal static adsorption tests. The reduction of fines migration due surface modification by silica NP suggests that NPs can be utilized to overcome the problem of formation damage induced during low salinity flooding in sandstones. Full article
(This article belongs to the Special Issue Nanotech for Oil and Gas)
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Open AccessFeature PaperArticle Bloch Surface Waves for MoS2 Emission Coupling and Polariton Systems
Appl. Sci. 2017, 7(12), 1217; doi:10.3390/app7121217
Received: 30 October 2017 / Revised: 18 November 2017 / Accepted: 20 November 2017 / Published: 24 November 2017
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Abstract
Due to their extraordinary quality factor and extreme sensitivity to surface perturbations, Bloch surface waves (BSW) have been widely investigated for sensing applications so far. Over the last few years, on-chip control of optical signals through BSW has experienced a rapidly-expanding interest in
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Due to their extraordinary quality factor and extreme sensitivity to surface perturbations, Bloch surface waves (BSW) have been widely investigated for sensing applications so far. Over the last few years, on-chip control of optical signals through BSW has experienced a rapidly-expanding interest in the scientific community, attesting to BSW’s position at the forefront towards on-chip optical operations. The backbone of on-chip optical devices requires the choice of integrated optical sources with peculiar optic/optoelectronic properties, the efficient in-plane propagation of the optical signal and the possibility to dynamic manipulate the signal through optical or electrical driving. In this paper, we discuss our approach in addressing these requirements. Regarding the optical source integration, we demonstrate the possibility to couple the MoS2 mono- and bi-layers emission—when integrated on top of a 1D photonic crystal—to a BSW. Afterward, we review our results on BSW-based polariton systems (BSWP). We show that the BSWPs combine long-range propagation with energy tuning of their dispersion through polariton–polariton interactions, paving the way for logic operations. Full article
(This article belongs to the Special Issue Surface Waves on Planar Photonic Crystals)
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Open AccessArticle Exploring the Effects of Pitch Layout on Learning a New Musical Instrument
Appl. Sci. 2017, 7(12), 1218; doi:10.3390/app7121218
Received: 27 October 2017 / Revised: 21 November 2017 / Accepted: 21 November 2017 / Published: 24 November 2017
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Abstract
Although isomorphic pitch layouts are proposed to afford various advantages for musicians playing new musical instruments, this paper details the first substantive set of empirical tests on how two fundamental aspects of isomorphic pitch layouts affect motor learning: shear, which makes the
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Although isomorphic pitch layouts are proposed to afford various advantages for musicians playing new musical instruments, this paper details the first substantive set of empirical tests on how two fundamental aspects of isomorphic pitch layouts affect motor learning: shear, which makes the pitch axis vertical, and the adjacency (or nonadjacency) of pitches a major second apart. After receiving audio-visual training tasks for a scale and arpeggios, performance accuracies of 24 experienced musicians were assessed in immediate retention tasks (same as the training tasks, but without the audio-visual guidance) and in a transfer task (performance of a previously untrained nursery rhyme). Each participant performed the same tasks with three different pitch layouts and, in total, four different layouts were tested. Results show that, so long as the performance ceiling has not already been reached (due to ease of the task or repeated practice), adjacency strongly improves performance accuracy in the training and retention tasks. They also show that shearing the layout, to make the pitch axis vertical, worsens performance accuracy for the training tasks but, crucially, it strongly improves performance accuracy in the transfer task when the participant needs to perform a new, but related, task. These results can inform the design of pitch layouts in new musical instruments. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessFeature PaperArticle Energy Saving Potential of PCMs in Buildings under Future Climate Conditions
Appl. Sci. 2017, 7(12), 1219; doi:10.3390/app7121219
Received: 27 October 2017 / Revised: 21 November 2017 / Accepted: 22 November 2017 / Published: 25 November 2017
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Abstract
Energy consumption reduction under changing climate conditions is a major challenge in buildings design, where excessive energy consumption creates an economic and environmental burden. Improving thermal performance of the buildings through support applying phase change material (PCM) is a promising strategy for reducing
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Energy consumption reduction under changing climate conditions is a major challenge in buildings design, where excessive energy consumption creates an economic and environmental burden. Improving thermal performance of the buildings through support applying phase change material (PCM) is a promising strategy for reducing building energy consumption under future climate change. Therefore, this study aims to investigate the energy saving potentials in buildings under future climate conditions in the humid and snowy regions in the hot continental and humid subtropical climates of the east Asia (Seoul, Tokyo and Hong Kong) when various PCMs with different phase change temperatures are applied to a lightweight building envelope. Methodology in this work is implemented in two phases: firstly, investigation of energy saving potentials in buildings through inclusion of three types of PCMs with different phase temperatures into the building envelop separately and use weather file in the present (2017); and, secondly, evaluation of the effect of future climate change on the performance of PCMs by analyzing energy saving potentials of PCMs with 2020, 2050 and 2080 weather data. The results show that the inclusion of PCM into the building envelope is a promising strategy to increase the energy performance in buildings during both heating and cooling seasons in Seoul, Tokyo and Hong Kong under future climate conditions. The energy savings achieved by using PCMs in those regions are electricity savings of 4.48–8.21%, 3.81–9.69%, and 1.94–5.15%, and gas savings of 1.65–16.59%, 7.60–61.76%), and 62.07–93.33% in Seoul, Tokyo and Hong Kong, respectively, for the years 2017, 2020, 2050 and 2080. In addition, BioPCM and RUBITHERMPCM are the most efficient for improving thermal performance and saving energy in buildings in the tested regions and years. Full article
(This article belongs to the Special Issue Phase Change Material (PCM) 2017)
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Open AccessArticle Design of a Road Simulator for Motorcycle Applications
Appl. Sci. 2017, 7(12), 1220; doi:10.3390/app7121220
Received: 16 October 2017 / Revised: 18 November 2017 / Accepted: 23 November 2017 / Published: 25 November 2017
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Abstract
Four-wheeled vehicles are often tested on indoor, four-poster road simulator rigs. Road loads are simulated with the use of servo-hydraulic systems for suspension set-up optimisation, NVH analysis, and fatigue life cycles. The use of a road simulator is not such a common practice
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Four-wheeled vehicles are often tested on indoor, four-poster road simulator rigs. Road loads are simulated with the use of servo-hydraulic systems for suspension set-up optimisation, NVH analysis, and fatigue life cycles. The use of a road simulator is not such a common practice for two-wheeled vehicles despite problems to be faced being extremely similar. The paper presents a device for testing motorcycles on a Servotest® four-poster. A dedicated restraint system had to be devised in order to support the motorcycle without altering its inertial characteristics. Additional pneumatic actuators with a purposely developed instrumentation have been designed to reproduce braking and power thrusts. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle An Organizational-Based Model and Agent-Based Simulation for Co-Traveling at an Aggregate Level
Appl. Sci. 2017, 7(12), 1221; doi:10.3390/app7121221
Received: 3 November 2017 / Accepted: 21 November 2017 / Published: 27 November 2017
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Abstract
Carpooling is an environmentally friendly and sustainable emerging traveling mode that enables commuters to save travel time and travel expenses. In order to co-travel, individuals or agents need to communicate, interpret information, and negotiate to achieve co-operation to find matching partners. This paper
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Carpooling is an environmentally friendly and sustainable emerging traveling mode that enables commuters to save travel time and travel expenses. In order to co-travel, individuals or agents need to communicate, interpret information, and negotiate to achieve co-operation to find matching partners. This paper offers the scheme of a carpooling model for a set of candidate carpoolers. The model is interpreted using an agent-based simulation to analyze several effects of agents’ interaction and behavior adaptations. Through communication and negotiation processes, agents can reach dynamic contracts in an iterative manner. The start of the negotiation process relies on the agents’ intention to emit an invitation for carpooling. The realization of the negotiation process depends significantly on the departure time choice, on the agents’ profile, and on route optimization. The schedule or agenda adaptation relies on the preferences among the realistic schedules of the agents and usually depends on both the participation of the trip and on the time of day. From the considerations, it is possible to reveal the actual representation of the possible carpoolers during the simulated period. Experiments demonstrate the nearly-polynomial relationship between computation time and the number of agents. Full article
(This article belongs to the Special Issue Multi-Agent Systems)
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Open AccessArticle Genetic Algorithm-Based Optimization Methodology of Bézier Curves to Generate a DCI Microscale-Model
Appl. Sci. 2017, 7(12), 1222; doi:10.3390/app7121222
Received: 23 October 2017 / Revised: 20 November 2017 / Accepted: 24 November 2017 / Published: 28 November 2017
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Abstract
The aim of this article is to develop a methodology that is capable of generating micro-scale models of Ductile Cast Irons, which have the particular characteristic to preserve the smoothness of the graphite nodules contours that are lost by discretization errors when the
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The aim of this article is to develop a methodology that is capable of generating micro-scale models of Ductile Cast Irons, which have the particular characteristic to preserve the smoothness of the graphite nodules contours that are lost by discretization errors when the contours are extracted using image processing. The proposed methodology uses image processing to extract the graphite nodule contours and a genetic algorithm-based optimization strategy to select the optimal degree of the Bézier curve that best approximate each graphite nodule contour. To validate the proposed methodology, a Finite Element Analysis (FEA) was carried out using models that were obtained through three methods: (a) using a fixed Bézier degree for all of the graphite nodule contours, (b) the present methodology, and (c) using a commercial software. The results were compared using the relative error of the equivalent stresses computed by the FEA, where the proposed methodology results were used as a reference. The present paper does not have the aim to define which models are the correct and which are not. However, in this paper, it has been shown that the errors generated in the discretization process should not be ignored when developing geometric models since they can produce relative errors of up to 35.9% when an estimation of the mechanical behavior is carried out. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessFeature PaperArticle Thermal Buckling of Nanocomposite Stiffened Cylindrical Shells Reinforced by Functionally Graded Wavy Carbon Nanotubes with Temperature-Dependent Properties
Appl. Sci. 2017, 7(12), 1223; doi:10.3390/app7121223
Received: 27 October 2017 / Accepted: 23 November 2017 / Published: 27 November 2017
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Abstract
We study the thermal buckling behavior of cylindrical shells reinforced with Functionally Graded (FG) wavy Carbon NanoTubes (CNTs), stiffened by stringers and rings, and subjected to a thermal loading. The equilibrium equations of the problem are built according to the Third-order Shear Deformation
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We study the thermal buckling behavior of cylindrical shells reinforced with Functionally Graded (FG) wavy Carbon NanoTubes (CNTs), stiffened by stringers and rings, and subjected to a thermal loading. The equilibrium equations of the problem are built according to the Third-order Shear Deformation Theory (TSDT), whereas the stiffeners are modeled as Euler Bernoulli beams. Different types of FG distributions of wavy CNTs along the radial direction of the cylinder are herein considered, and temperature-dependent material properties are estimated via a micromechanical model, under the assumption of uniform distribution within the shell and through the thickness. A parametric investigation based on the Generalized Differential Quadrature (GDQ) method aims at investigating the effects of the aspect ratio and waviness index of CNTs on the thermal buckling of FG nanocomposite stiffened cylinders, reinforced with wavy single-walled CNTs. Some numerical examples are here provided in order to verify the accuracy of the proposed formulation and to investigate the effects of several parameters—including the volume fraction, the distribution pattern of wavy CNTs, and the cylinder thickness—on the thermal buckling behavior of the stiffened cylinders made of CNT-reinforced composite (CNTRC) material. Full article
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Open AccessArticle Could We Realize the Fully Flexible System by Real-Time Computing with Thin-Film Transistors?
Appl. Sci. 2017, 7(12), 1224; doi:10.3390/app7121224
Received: 31 October 2017 / Revised: 21 November 2017 / Accepted: 24 November 2017 / Published: 27 November 2017
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Abstract
Flexible electronic devices, such as the typical thin-film transistors, are widely adopted in the area of sensors, displayers, wearable equipment, and such large-area applications, for their features of bending and stretching; additionally, in some applications of lower-resolution data converters recently, where a trend
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Flexible electronic devices, such as the typical thin-film transistors, are widely adopted in the area of sensors, displayers, wearable equipment, and such large-area applications, for their features of bending and stretching; additionally, in some applications of lower-resolution data converters recently, where a trend appears that implementing more parts of system with flexible devices to realize the fully flexible system. Nevertheless, relatively fewer works on the computation parts with flexible electronic devices are reported, due to their poor carrier mobility, which blocks the way to realize the fully flexible systems with uniform manufacturing process. In this paper, a novel circuit architecture for image processing accelerator using Oxide Thin-film transistor (TFT), which could realize real-time image pre-processing and classification in the analog domain, is proposed, where the performance and fault-tolerance of image signal processing is exploited. All of the computation is done in the analog signal domain and no clock signal is needed. Therefore, certain weaknesses of flexible electronic devices, such as low carrier mobility, could be remedied dramatically. In this paper, Simulations based on Oxide TFT device model have demonstrated that the flexible computing parts could perform 5 × 5 Gaussian convolution operation at a speed of 3.3 MOPS/s with the energy efficiency of 1.83 TOPS/J, and realize image classification at a speed of 10 k fps, with the energy efficiency of 5.25 GOPS/J, which means that the potential applications to realize real-time computing parts of complex algorithms with flexible electronic devices, as well as the future fully flexible systems containing sensors, data converters, energy suppliers, and real-time signal processing modules, all with flexible devices. Full article
(This article belongs to the Special Issue Thin-Film Transistors)
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Open AccessArticle Dynamic Shear Degradation of Geosynthetic–Soil Interface in Waste Landfill Sites
Appl. Sci. 2017, 7(12), 1225; doi:10.3390/app7121225
Received: 17 October 2017 / Revised: 15 November 2017 / Accepted: 16 November 2017 / Published: 27 November 2017
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Abstract
Geosynthetics and soil particles inevitably come into contact, resulting in a geosynthetic–soil interface. The discontinuity of the materials at the interface causes an intricate shear response, especially under dynamic loads. In the present study, the effects of chemical aggressors of the leachate from
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Geosynthetics and soil particles inevitably come into contact, resulting in a geosynthetic–soil interface. The discontinuity of the materials at the interface causes an intricate shear response, especially under dynamic loads. In the present study, the effects of chemical aggressors of the leachate from a waste landfill site on the cyclic shear behaviors of a geosynthetic–soil interface were investigated. The Multi-Purpose Interface Apparatus (M-PIA) that can simulate cyclic simple shear conditions was utilized, and 72 sets of cyclic simple shear tests were conducted. The Disturbed State Concept (DSC) was employed to quantitatively estimate the shear stress degradation. As a result, new disturbance functions and parameters that represent the characteristics of the dynamic shear degradation at the interface were evaluated. Additionally, a numerical back-prediction was performed to verify the accuracy and applicability of the DSC parameters. Numerical interpolation procedures were suggested and enabled to reproduce the degradation successfully. Consequently, a general methodology was established to estimate the cyclic shear stress degradation of the geosynthetic–soil interface in consideration of chemical effects. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Evaluation of the Cooling and Pavement Performance of Basic Oxygen Furnace Slag Used in Asphalt Mixture
Appl. Sci. 2017, 7(12), 1226; doi:10.3390/app7121226
Received: 15 September 2017 / Revised: 13 November 2017 / Accepted: 14 November 2017 / Published: 27 November 2017
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Abstract
Basic oxygen furnace slag (BOF) is widely used in road construction, but there is a lack of characteristics in different asphalt mixtures. This study investigates the properties of hot-mixed asphalt (HMA), containing stone mastic asphalt (SMA), porous asphalt (PA), and dense-graded BOF as
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Basic oxygen furnace slag (BOF) is widely used in road construction, but there is a lack of characteristics in different asphalt mixtures. This study investigates the properties of hot-mixed asphalt (HMA), containing stone mastic asphalt (SMA), porous asphalt (PA), and dense-graded BOF as a partial substitution for natural aggregates. The purpose of this study is to evaluate various BOF slag contents in the asphalt mixtures that would affect the cooling behavior after compaction. Asphalt mixture specimens contained 0%, 20%, 40% and 60% BOF slag, respectively, as coarse aggregate. Test results showed that BOF slag has a lipophilic property, so that it can be adsorbed by asphalt cement, thereby reducing the cost of asphalt. The stability value of all the asphalt mixtures increases with the proportion of BOF slag replacement. In addition, the voids in the mineral aggregate (VMA) value variable exhibited significant differences among asphalt mixtures, and could determine the deviation of the cooling trend of asphalt mixtures. Furthermore, it was found that the cooling procedure of the BOF slag used in dense-graded asphalt mixture takes about 100 min, and that the temperature tends to be moderate; however, it took about 120 min of cooling the SMA and PA mixture with BOF slag. In addition, the distribution of voids of the dense asphalt mixture was not uniform. This would result in various locations of inconsistent thermal energy temperature on asphalt mixtures. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle Enhancement of Skin Anti-Inflammatory Activities of Eclipta prostrata L. from the Ultrasonic Extraction Process
Appl. Sci. 2017, 7(12), 1227; doi:10.3390/app7121227
Received: 17 November 2017 / Accepted: 21 November 2017 / Published: 28 November 2017
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Abstract
This work first showed that the skin anti-inflammatory activities of Eclipta prostrata L. (E. prostrata L.)n be increased through an ultrasonic extraction process at a frequency of 120 kHz with 70% ethanol at 40 °C for 6 h. The extract from the
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This work first showed that the skin anti-inflammatory activities of Eclipta prostrata L. (E. prostrata L.)n be increased through an ultrasonic extraction process at a frequency of 120 kHz with 70% ethanol at 40 °C for 6 h. The extract from the ultrasound extraction (UE) contained 378.6 mg/100 g of wedelolactone (a major bioactive substance in E. prostrata L.), compared with the 172.9 mg/100 g from a conventional extraction process with 70% ethanol at 80 °C for 12 h (EE). The UE showed less than 10% of low cytotoxicity against normal fibroblast cells, and also exhibited much higher antioxidant activities than that from the EE when treating with 0.3 mg/mL of the extracts. It was proved that the high antioxidant activities of the UE were closely correlated with the enhancement of skin anti-inflammatory activities by effectively suppressing the production of tumor necrosis factor-alpha and interleukin-6 from macrophages. The production of prostaglandin E2 from human skin cells was also greatly reduced, compared with the EE for all ranges of the treatments. These results strongly indicate that the various biological activities of E. prostrata L. can be improved by a simple ultrasound extraction process because of the high elution of bioactive substances even at a low temperature. Full article
(This article belongs to the Special Issue Ultrasound in Extraction Processing)
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Open AccessFeature PaperArticle Influence of Winkler-Pasternak Foundation on the Vibrational Behavior of Plates and Shells Reinforced by Agglomerated Carbon Nanotubes
Appl. Sci. 2017, 7(12), 1228; doi:10.3390/app7121228
Received: 28 October 2017 / Revised: 10 November 2017 / Accepted: 23 November 2017 / Published: 28 November 2017
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Abstract
This paper aims to investigate the effect of the Winkler-Pasternak elastic foundation on the natural frequencies of Carbon Nanotube (CNT)-reinforced laminated composite plates and shells. The micromechanics of reinforcing CNT particles are described by a two-parameter agglomeration model. CNTs are gradually distributed along
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This paper aims to investigate the effect of the Winkler-Pasternak elastic foundation on the natural frequencies of Carbon Nanotube (CNT)-reinforced laminated composite plates and shells. The micromechanics of reinforcing CNT particles are described by a two-parameter agglomeration model. CNTs are gradually distributed along the thickness direction according to various functionally graded laws. Elastic foundations are modeled according to the Winkler-Pasternak theory. The theoretical model considers several Higher-order Shear Deformation Theories (HSDTs) based on the so-called Carrera Unified Formulation (CUF). The theory behind CNTs is explained in detail. The theoretical model presented is solved numerically by means of the Generalized Differential Quadrature (GDQ) method. Several parametric studies are conducted, and their results are discussed. Full article
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Open AccessFeature PaperArticle Infrared Spectroscopy as Molecular Probe of the Macroscopic Metal-Liquid Interface
Appl. Sci. 2017, 7(12), 1229; doi:10.3390/app7121229
Received: 7 October 2017 / Revised: 13 November 2017 / Accepted: 23 November 2017 / Published: 28 November 2017
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Abstract
Metal-liquid interfaces are of the utmost importance in a number of scientific areas, including electrochemistry and catalysis. However, complicated analytical methods and sample preparation are usually required to study the interfacial phenomena. We propose an infrared spectroscopic approach that enables investigating the molecular
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Metal-liquid interfaces are of the utmost importance in a number of scientific areas, including electrochemistry and catalysis. However, complicated analytical methods and sample preparation are usually required to study the interfacial phenomena. We propose an infrared spectroscopic approach that enables investigating the molecular interactions at the interface, but needing only minimal or no sample preparation. For this purpose, the internal reflection element (IRE) is wetted with a solution as first step. Second, a small plate of the metal of interest is put on top and pressed onto the IRE. The tiny amount of liquid that is remaining between the IRE and the metal is sufficient to produce an IR spectrum with good signal to noise ratio, from which information about molecular interactions, such as hydrogen bonding, can be deduced. Proof-of-concept experiments were carried out with aqueous salt and acid solutions and an aluminum plate. Full article
(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)
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Open AccessArticle Value Systems Alignment Analysis in Collaborative Networked Organizations Management
Appl. Sci. 2017, 7(12), 1231; doi:10.3390/app7121231
Received: 19 October 2017 / Revised: 17 November 2017 / Accepted: 20 November 2017 / Published: 28 November 2017
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Abstract
The assessment of value systems alignment can play an important role in the formation and evolution of collaborative networks, contributing to reduce potential risks of collaboration. For this purpose, an assessment tool is proposed as part of a collaborative networks information system, supporting
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The assessment of value systems alignment can play an important role in the formation and evolution of collaborative networks, contributing to reduce potential risks of collaboration. For this purpose, an assessment tool is proposed as part of a collaborative networks information system, supporting both the formation and evolution of long-term strategic alliances and goal-oriented networks. An implementation approach for value system alignment analysis is described, which is intended to assist managers in virtual and networked organizations management. The implementation of the assessment and analysis methods is supported by a set of software services integrated in the information system that supports the management of the networked organizations. A case study in the solar energy sector was conducted, and the data collected through this study allow us to confirm the practical applicability of the proposed methods and the software services. Full article
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Open AccessArticle Adaptive LOS Path Following for a Podded Propulsion Unmanned Surface Vehicle with Uncertainty of Model and Actuator Saturation
Appl. Sci. 2017, 7(12), 1232; doi:10.3390/app7121232
Received: 3 October 2017 / Accepted: 23 November 2017 / Published: 28 November 2017
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Abstract
This paper addresses three related issues concerning the path following control of a podded propulsion unmanned surface vehicle (USV), namely modeling, guidance and control. The pod is different from the general propeller-rudder propulsion device, and its essence is a vector thruster. Therefore, first,
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This paper addresses three related issues concerning the path following control of a podded propulsion unmanned surface vehicle (USV), namely modeling, guidance and control. The pod is different from the general propeller-rudder propulsion device, and its essence is a vector thruster. Therefore, first, through various assumptions and simplification, the three-degree of freedom (DOFs) planar motion model of the podded propulsion USV is established. Then, the classical line-of-sight (LOS) guidance strategy is improved by adaptive sideslip angle and a time-varying lookahead distance. Based on the guidance system, the corresponding controllers for yaw rate and surge speed are presented, which are combined by backstepping technology, the neural network minimum parameter learning method and the neural shunting model. Specifically, the neural network minimum parameter learning method is proposed to compensate the uncertainty of the model and the immeasurability of external disturbances, and the neural shunting model is employed to cope with the “explosion of complexity” problem of backstepping. Meanwhile, an auxiliary dynamic system is introduced to prevent actuator saturation (input saturation). All error signals of the system are proven to be uniformly ultimately bounded (UUB) by employing Lyapunov stability theory. Finally, two numerical simulations are given to prove the correctness of the proposed scheme. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Evaluation and Optimization of a Hybrid Manufacturing Process Combining Wire Arc Additive Manufacturing with Milling for the Fabrication of Stiffened Panels
Appl. Sci. 2017, 7(12), 1233; doi:10.3390/app7121233
Received: 30 October 2017 / Accepted: 23 November 2017 / Published: 28 November 2017
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Abstract
This paper proposes a hybrid WAAM (wire arc additive manufacturing) and milling process (HWMP), and highlights its application in the fabrication of stiffened panels that have wide applications in aviation, aerospace, and automotive industries, etc. due to their light weight and strong load-bearing
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This paper proposes a hybrid WAAM (wire arc additive manufacturing) and milling process (HWMP), and highlights its application in the fabrication of stiffened panels that have wide applications in aviation, aerospace, and automotive industries, etc. due to their light weight and strong load-bearing capability. In contrast to existing joining or machining methods, HWMP only deposits stiffeners layer-by-layer onto an existing thin plate, followed by minor milling of the irregular surfaces, which provides the possibility to significantly improve material utilization and efficiency without any loss of surface quality. In this paper, the key performances of HWMP in terms of surface quality, material utilization and efficiency are evaluated systematically, which are the results of the comprehensive effects of the deposition parameters (e.g., travel speed, wire-feed rate) and the milling parameters (e.g., spindle speed, tool-feed rate). In order to maximize its performances, the optimization is also performed to find the best combination of the deposition and the milling parameters. The case study shows that HWMP with the optimal process parameters improves the material utilization by 57% and the efficiency by 32% compared against the traditional machining method. Thus, HWMP is believed to be a more environmental friendly and sustainable method for the fabrication of stiffened panels or other similar structures. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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Open AccessArticle Time-Domain Functional Diffuse Optical Tomography System Based on Fiber-Free Silicon Photomultipliers
Appl. Sci. 2017, 7(12), 1235; doi:10.3390/app7121235
Received: 2 October 2017 / Revised: 2 November 2017 / Accepted: 24 November 2017 / Published: 29 November 2017
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Abstract
Based on recent developments in both single-photon detectors and timing electronic circuits, we designed a compact and cost effective time-domain diffuse optical tomography system operated at 1 Hz acquisition rate, based on eight silicon photomultipliers and an 8-channel time-to-digital converter. The compact detectors
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Based on recent developments in both single-photon detectors and timing electronic circuits, we designed a compact and cost effective time-domain diffuse optical tomography system operated at 1 Hz acquisition rate, based on eight silicon photomultipliers and an 8-channel time-to-digital converter. The compact detectors are directly hosted on the probe in a circular arrangement around a single light injection fiber, so to maximize light harvesting. Tomography is achieved exploiting the depth sensitivity that is encoded in the arrival time of detected photons. The system performances were evaluated on simulations to assess possible the limitations arising from the use of a single injection point, and then on phantoms and in vivo to prove the eligibility of these technologies for diffuse optical tomography. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle A New Online Secondary Path Modeling Method with An Auxiliary Noise Power Scheduling Strategy for Narrowband Active Noise Control Systems
Appl. Sci. 2017, 7(12), 1236; doi:10.3390/app7121236
Received: 10 October 2017 / Revised: 9 November 2017 / Accepted: 27 November 2017 / Published: 29 November 2017
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Abstract
In recent years, the online secondary path modeling (SPM) method with an auxiliary noise power scheduling strategy has been crucial for active noise control (ANC) systems and has also become a popular research topic. However, most scheduling strategies have been designed for broadband
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In recent years, the online secondary path modeling (SPM) method with an auxiliary noise power scheduling strategy has been crucial for active noise control (ANC) systems and has also become a popular research topic. However, most scheduling strategies have been designed for broadband active noise control (BANC), and these ideas may not be directly applied to narrowband active noise control (NANC) systems due to the difference in structure between BANC and NANC systems. In this paper, a new online SPM method with auxiliary noise power scheduling is proposed. Here, the controlled system is adapted using the filtered-x weighted accumulated least mean square (FXWALMS) algorithm proposed by the authors. Moreover, the auxiliary noise power is scheduled based on the convergence status of the forgetting factor to accurately track the change in the NANC system. As a result, the proposed method not only achieves good modeling accuracy and fast convergence but also considerably increases noise attenuation. Extensive simulations are conducted to prove the superior performance of the proposed method in various scenarios. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle AIM: A Computational Tool for the Automatic Quantification of Scratch Wound Healing Assays
Appl. Sci. 2017, 7(12), 1237; doi:10.3390/app7121237
Received: 30 October 2017 / Revised: 15 November 2017 / Accepted: 20 November 2017 / Published: 29 November 2017
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Abstract
Cell invasiveness quantification is of paramount importance in cancer research and is often evaluated in vitro through scratch wound healing assays that determine the rate at which a population of cells fills a gap created in a confluent 2D culture. The quantification of
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Cell invasiveness quantification is of paramount importance in cancer research and is often evaluated in vitro through scratch wound healing assays that determine the rate at which a population of cells fills a gap created in a confluent 2D culture. The quantification of the results of this experiment, however, lacks standardization and is often highly time consuming and user dependent. To overcome these limitations, we have developed AIM (Automatic Invasiveness Measure), a freely-available software tool for the automatic quantification of the cell-free region in scratch wound healing assays. This study will completely describe AIM and will show its equivalence to three analysis methods commonly used for the quantification of the scratch area and the measure of true wound extension. Furthermore, the analysis time and the dependency of the results of these techniques on the structure of the time course (total duration and number of points) will be studied. To the best of our knowledge, AIM is the first entirely-automated analysis method for scratch wound healing assays and represents a significant improvement of this technique both in terms of results’ quality and reliability. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Base Pounding Model and Response Analysis of Base-Isolated Structures under Earthquake Excitation
Appl. Sci. 2017, 7(12), 1238; doi:10.3390/app7121238
Received: 31 October 2017 / Revised: 26 November 2017 / Accepted: 27 November 2017 / Published: 29 November 2017
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Abstract
In order to study the base pounding effects of base-isolated structure under earthquake excitations, a base pounding theoretical model with a linear spring-gap element is proposed. A finite element analysis program is used in numerical simulation of seismic response of based-isolated structure when
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In order to study the base pounding effects of base-isolated structure under earthquake excitations, a base pounding theoretical model with a linear spring-gap element is proposed. A finite element analysis program is used in numerical simulation of seismic response of based-isolated structure when considering base pounding. The effects of the structure pounding against adjacent structures are studied, and the seismic response of a base-isolated structure with lead-rubber bearing and a base-isolated structure with friction pendulum isolation bearing are analyzed. The results indicate that: the model offers much flexibility to analyze base pounding effects. There is a most clearance unfavorable width between adjacent structures. The structural response increases with pounding. Significant amplification of the story shear-force, velocity, and acceleration were observed. Increasing the number of stories in a building leads to an initial increase in impact force, followed by a decrease in such force. As a result, it is necessary to consider base pounding in the seismic design of base-isolated structures. Full article
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Open AccessArticle A Transplantable Frequency Selective Metasurface for High-Order Harmonic Suppression
Appl. Sci. 2017, 7(12), 1240; doi:10.3390/app7121240
Received: 5 November 2017 / Revised: 17 November 2017 / Accepted: 23 November 2017 / Published: 1 December 2017
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Abstract
A transplantable frequency selective metasurface element (FSMSE) for high-order harmonic suppression (HS) is presented in this paper. The proposed harmonic free FSMSE can be integrated with arbitrary frequency selective surfaces (FSSs) operating at the same frequency band. The designed HS-FSMSE is applied to
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A transplantable frequency selective metasurface element (FSMSE) for high-order harmonic suppression (HS) is presented in this paper. The proposed harmonic free FSMSE can be integrated with arbitrary frequency selective surfaces (FSSs) operating at the same frequency band. The designed HS-FSMSE is applied to two different types of FSSs for verification of harmonic suppression, respectively. One is a multilayer sub-wavelength patch-grid FSS that has weak resonant behavior, and the other is a complementary resonant loop FSS which has strong resonant behavior, especially for high-order harmonic waves. By integrating with HS-FSMSE, the two kinds of FSSs operating at 10 GHz are free of harmonic transmission bands up to 30 GHz. The simulation and measurement results show feasibility of the harmonic suppression FSMSW and good polarization and angle stabilities. Full article
(This article belongs to the Special Issue Metasurfaces: Physics and Applications)
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Open AccessFeature PaperArticle Targeted Molecular Imaging of Pancreatic Cancer with a Miniature Endoscope
Appl. Sci. 2017, 7(12), 1241; doi:10.3390/app7121241
Received: 10 October 2017 / Revised: 27 November 2017 / Accepted: 28 November 2017 / Published: 30 November 2017
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Abstract
It is highly desirable to develop novel approaches to improve patient survival rate of pancreatic cancer through early detection. Here, we present such an approach based on photoacoustic and fluorescence molecular imaging of pancreatic tumor using a miniature multimodal endoscope in combination with
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It is highly desirable to develop novel approaches to improve patient survival rate of pancreatic cancer through early detection. Here, we present such an approach based on photoacoustic and fluorescence molecular imaging of pancreatic tumor using a miniature multimodal endoscope in combination with targeted multifunctional iron oxide nanoparticles (IONPs). A novel fan-shaped scanning mechanism was developed to minimize the invasiveness for endoscopic imaging of pancreatic tumors. The results show that the enhancements in photoacoustic and fluorescence signals using amino-terminal fragment (ATF) targeted IONPs were ~four to six times higher compared to that using non-targeted IONPs. Our study indicates the potential of the combination of the multimodal photoacoustic-fluorescence endoscopy and targeted multifunctional nanoparticles as an efficient tool to provide improved specificity and sensitivity for pancreatic cancer detection. Full article
(This article belongs to the Special Issue Biological Applications of Magnetic Nanoparticles)
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Open AccessArticle Melodic Similarity and Applications Using Biologically-Inspired Techniques
Appl. Sci. 2017, 7(12), 1242; doi:10.3390/app7121242
Received: 30 September 2017 / Revised: 23 November 2017 / Accepted: 27 November 2017 / Published: 1 December 2017
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Abstract
Music similarity is a complex concept that manifests itself in areas such as Music Information Retrieval (MIR), musicological analysis and music cognition. Modelling the similarity of two music items is key for a number of music-related applications, such as cover song detection and
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Music similarity is a complex concept that manifests itself in areas such as Music Information Retrieval (MIR), musicological analysis and music cognition. Modelling the similarity of two music items is key for a number of music-related applications, such as cover song detection and query-by-humming. Typically, similarity models are based on intuition, heuristics or small-scale cognitive experiments; thus, applicability to broader contexts cannot be guaranteed. We argue that data-driven tools and analysis methods, applied to songs known to be related, can potentially provide us with information regarding the fine-grained nature of music similarity. Interestingly, music and biological sequences share a number of parallel concepts; from the natural sequence-representation, to their mechanisms of generating variations, i.e., oral transmission and evolution respectively. As such, there is a great potential for applying scientific methods and tools from bioinformatics to music. Stripped-down from biological heuristics, certain bioinformatics approaches can be generalized to any type of sequence. Consequently, reliable and unbiased data-driven solutions to problems such as biological sequence similarity and conservation analysis can be applied to music similarity and stability analysis. Our paper relies on such an approach to tackle a number of tasks and more notably to model global melodic similarity. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials
Appl. Sci. 2017, 7(12), 1243; doi:10.3390/app7121243
Received: 1 November 2017 / Revised: 24 November 2017 / Accepted: 27 November 2017 / Published: 30 November 2017
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Abstract
The smectites represent a versatile class of clay minerals with broad usage in industrial applications, e.g., cosmetics, drug delivery, bioimaging, etc. Synthetic hectorite Na0.7(Mg5.5Li0.3)[Si8O20](OH)4 is a distinct material from this class due
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The smectites represent a versatile class of clay minerals with broad usage in industrial applications, e.g., cosmetics, drug delivery, bioimaging, etc. Synthetic hectorite Na0.7(Mg5.5Li0.3)[Si8O20](OH)4 is a distinct material from this class due to its low-cost production method that allows to design its structure to match better the applications. In the current work, we have synthesized for the first time ever nanoclay materials based on the hectorite structure but with the hydroxyl groups (OH) replaced by Br or I, yielding bromohectorite (Br-Hec) and iodohectorite (I-Hec). It was aimed that these materials would be used as phosphors. Thus, OH replacement was done to avoid luminescence quenching by multiphonon de-excitation. The crystal structure is similar to nanocrystalline fluorohectorite, having the d001 spacing of 14.30 Å and 3 nm crystallite size along the 00l direction. The synthetic materials studied here show strong potential to act as host lattices for optically active species, possessing mesoporous structure with high specific surface area (385 and 363 m2 g−1 for Br-Hec and I-Hec, respectively) and good thermal stability up to 800 °C. Both materials also present strong blue-green emission under UV radiation and short persistent luminescence (ca. 5 s). The luminescence features are attributed to Ti3+/TiIV impurities acting as the emitting center in these materials. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Simulation and Fabrication of HfO2 Thin Films Passivating Si from a Numerical Computer and Remote Plasma ALD
Appl. Sci. 2017, 7(12), 1244; doi:10.3390/app7121244
Received: 31 October 2017 / Revised: 24 November 2017 / Accepted: 27 November 2017 / Published: 1 December 2017
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Abstract
Recombination of charge carriers at silicon surfaces is one of the biggest loss mechanisms in crystalline silicon (c-Si) solar cells. Hafnium oxide (HfO2) has attracted much attention as a passivation layer for n-type c-Si because of its positive fixed charges and
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Recombination of charge carriers at silicon surfaces is one of the biggest loss mechanisms in crystalline silicon (c-Si) solar cells. Hafnium oxide (HfO2) has attracted much attention as a passivation layer for n-type c-Si because of its positive fixed charges and thermal stability. In this study, HfO2 films are deposited on n-type c-Si using remote plasma atomic layer deposition (RP-ALD). Post-annealing is performed using a rapid thermal processing system at different temperatures in nitrogen ambient for 10 min. The effects of post-annealing temperature on the passivation properties of the HfO2 films on c-Si are investigated. Personal computer one dimension numerical simulation for the passivated emitter and rear contact (PERC) solar cells with the HfO2 passivation layer is also presented. By means of modeling and numerical computer simulation, the influence of different front surface recombination velocity (SRV) and rear SRV on n-type silicon solar cell performance was investigated. Simulation results show that the n-type PERC solar cell with HfO2 single layer can have a conversion efficiency of 22.1%. The PERC using silicon nitride/HfO2 stacked passivation layer can further increase efficiency to 23.02% with an open-circuit voltage of 689 mV. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)
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Open AccessArticle Structural Damage Detection with Different Objective Functions in Noisy Conditions Using an Evolutionary Algorithm
Appl. Sci. 2017, 7(12), 1245; doi:10.3390/app7121245
Received: 12 October 2017 / Revised: 21 November 2017 / Accepted: 28 November 2017 / Published: 1 December 2017
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Abstract
Dynamic properties such as natural frequencies and mode shapes are directly affected by damage in structures. In this paper, changes in natural frequencies and mode shapes were used as the input to various objective functions for damage detection. Objective functions related to natural
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Dynamic properties such as natural frequencies and mode shapes are directly affected by damage in structures. In this paper, changes in natural frequencies and mode shapes were used as the input to various objective functions for damage detection. Objective functions related to natural frequencies, mode shapes, modal flexibility and modal strain energy have been used, and their performances have been analyzed in varying noise conditions. Three beams were analyzed: two of which were simulated beams with single and multiple damage scenarios and one was an experimental beam. In order to do this, SAP 2000 (v14, Computers and Structures Inc., Berkeley, CA, United States, 2009) is linked with MATLAB (r2015, The MathWorks, Inc., Natick, MA, United States, 2015). The genetic algorithm (GA), an evolutionary algorithm (EA), was used to update the damaged structure for damage detection. Due to the degradation of the performance of objective functions in varying noisy conditions, a modified objective function based on the concept of regularization has been proposed, which can be effectively used in combination with EA. All three beams were used to validate the proposed procedure. It has been found that the modified objective function gives better results even in noisy and actual experimental conditions. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Wavelength Conversion Enhancement Achieved by Using Resonance in an Array of Nanocylinders
Appl. Sci. 2017, 7(12), 1246; doi:10.3390/app7121246
Received: 15 October 2017 / Revised: 13 November 2017 / Accepted: 27 November 2017 / Published: 1 December 2017
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Abstract
Upconversion (UC) materials are promising for harvesting visual light. However, the efficiency of UC processes is very low when applied to practical devices. Therefore, we propose an array of UC nanocylinders on a gold substrate and induce electric dipole (ED) and magnetic dipole
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Upconversion (UC) materials are promising for harvesting visual light. However, the efficiency of UC processes is very low when applied to practical devices. Therefore, we propose an array of UC nanocylinders on a gold substrate and induce electric dipole (ED) and magnetic dipole (MD) resonances to increase the UC process efficiency by increasing light-matter interactions via the nanostructures. The nanocylinders not only increase the absorption of infrared light with a wavelength of 980 nm but also enhance the emission of visible light with a wavelength of 660 nm through surface plasmons and electric dipole resonances. The absorbance of the UC material can be enhanced by coupling with the surface plasmons and coupling with the MDs of each nanocylinder. On the other hand, the emission of visible light can be largely enhanced by increasing the spontaneous emission rate of the Purcell effect in electric dipole resonances and tailoring the output efficiency of the emitted light. In summary, we obtained an absorption enhancement of ×7.3, an average effective upward emission enhancement of ×21, and an improved total UC process of the proposed nanocylinder of ×155. Full article
(This article belongs to the Special Issue Dielectric Metamaterials)
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Open AccessArticle A Thermographic Measurement Approach to Assess Supercapacitor Electrical Performances
Appl. Sci. 2017, 7(12), 1247; doi:10.3390/app7121247
Received: 17 October 2017 / Revised: 24 November 2017 / Accepted: 28 November 2017 / Published: 1 December 2017
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Abstract
This paper describes a proposal for the qualitative assessment of condition of supercapacitors based on the conducted thermographic measurements. The presented measurement stand was accompanied by the concept of methodology of performing tests. Necessary conditions, which were needed to minimize the influence of
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This paper describes a proposal for the qualitative assessment of condition of supercapacitors based on the conducted thermographic measurements. The presented measurement stand was accompanied by the concept of methodology of performing tests. Necessary conditions, which were needed to minimize the influence of disturbing factors on the performance of thermal imaging measurements, were also indicated. Mentioned factors resulted from both: the hardware limitations and from the necessity to prepare samples. The algorithm that was used to determine the basic parameters for assessment has been presented. The article suggests to use additional factors that may facilitate the analysis of obtained results. Measuring the usefulness of the proposed methodology was tested on commercial samples of supercapacitors. All of the tests were taken in conjunction with the classical methods based on capacitance (C) and equivalent series resistance (ESR) measurements, which were also presented in the paper. Selected results presenting the observed changes occurring in both: basic parameters of supercapacitors and accompanying fluctuations of thermal fields, along with analysis, were shown. The observed limitations of the proposed assessment method and the suggestions for its development were also described. Full article
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Open AccessArticle Estimation of Compressive Strength of High Strength Concrete Using Non-Destructive Technique and Concrete Core Strength
Appl. Sci. 2017, 7(12), 1249; doi:10.3390/app7121249
Received: 16 October 2017 / Revised: 29 November 2017 / Accepted: 30 November 2017 / Published: 2 December 2017
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Abstract
Estimating the compressive strength of high strength concrete (HSC) is an essential investigation for the maintenance of nuclear power plant (NPP) structures. This study intends to evaluate the compressive strength of HSC using two approaches: non-destructive tests and concrete core strength. For non-destructive
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Estimating the compressive strength of high strength concrete (HSC) is an essential investigation for the maintenance of nuclear power plant (NPP) structures. This study intends to evaluate the compressive strength of HSC using two approaches: non-destructive tests and concrete core strength. For non-destructive tests, samples of HSC were mixed to a specified design strength of 40, 60 and 100 MPa. Based on a dual regression relation between ultrasonic pulse velocity (UPV) and rebound hammer (RH) measurements, an estimation expression is developed. In comparison to previously published estimation equations, the equation proposed in this study shows the highest accuracy and the lowest root mean square error (RMSE). For the estimation of compressive strength using concrete core specimens, three different concrete core diameters were examined: 30, 50, and 100 mm. Based on 61 measured compressive strengths of core specimens, a simple strength correction factor is investigated. The compressive strength of a concrete core specimen decreases as the core diameter reduces. Such a relation is associated with the internal damage of concrete cores and the degree of coarse aggregate within the core diameter from the extracting process of the cores. The strength estimation expressions was formulated using the non-destructive technique and the core strength estimation can be updated with further test results and utilized for the maintenance of NPP. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Effect of Equal Channel Angular Pressing (ECAP) on Erosion-Corrosion of Pure Copper
Appl. Sci. 2017, 7(12), 1250; doi:10.3390/app7121250
Received: 21 October 2017 / Revised: 29 November 2017 / Accepted: 30 November 2017 / Published: 2 December 2017
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Abstract
During the past few decades, ultrafine-grained materials (UFG) have experienced rapid development. Enhanced mechanical and surface properties, such as strength, ductility and erosion-corrosion (E-C) resistance by refining the grain to ultra-fine/nanometer size has been achieved. The equal channel angular pressing (ECAP) is a
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During the past few decades, ultrafine-grained materials (UFG) have experienced rapid development. Enhanced mechanical and surface properties, such as strength, ductility and erosion-corrosion (E-C) resistance by refining the grain to ultra-fine/nanometer size has been achieved. The equal channel angular pressing (ECAP) is a popular severe plastic deformation (SPD) method to fabricate UFG bulk materials. In this research, the E-C behavior of commercial annealed pure copper subject to four passes of ECAP have been investigated. Hardness measurement of the copper specimen after four passes of ECAP showed an increase of 200% on the hardness value as compared with annealed condition. Simulated seawater was used as an E-C medium. The effect of different E-C parameters such as time, slurry flow velocity, impact angle, and solid particle concentration on ECAP process is studied. The results showed that ECAP enhances the E-C resistance of copper, and this behavior improves with increasing the pass number. Generally, a 30% rise in resistance to E-C was achieved after four ECAP passes as compared to coarse grain copper for the parameters studied in this work. Optical microscopy was used to examine the microstructure and material removal mechanism of the annealed copper. Scanning electron microscopy (SEM) was used to validate the reduction of grain size due to ECAP process. Furthermore, examination of the surface roughness of the copper at different ECAP passes showed that for the same E-C condition the increment of ECAP passes leads to a smoother surface. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Cellular Automaton Modeling of the Transition of Multi-Crystalline Silicon from a Planar Faceted Front to Equiaxed Growth
Appl. Sci. 2017, 7(12), 1251; doi:10.3390/app7121251
Received: 24 October 2017 / Revised: 24 November 2017 / Accepted: 24 November 2017 / Published: 2 December 2017
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Abstract
A modeling approach combining the lattice Boltzmann (LB) method and the cellular automaton (CA) technique are developed to simulate the faceted front to equiaxed structure transition (FET) of directional solidification of multi-crystalline silicon. The LB method is used for the coupled calculation of
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A modeling approach combining the lattice Boltzmann (LB) method and the cellular automaton (CA) technique are developed to simulate the faceted front to equiaxed structure transition (FET) of directional solidification of multi-crystalline silicon. The LB method is used for the coupled calculation of velocity, temperature and solute content field, while the CA method is used to compute the nucleation at the silicon-crucible interface and on SiC particles, as well as the mechanism of growth and capturing. For silicon, the interface kinetic coefficient is rather low, which means that the kinetic undercooling can be large. A strong anisotropy in the surface tension and interfacial kinetics are considered in the model. A faceted front in conjunction with a sufficiently high carbon content can lead to equiaxed growth by nucleation on SiC. The temperature gradient in Si melt at the interface is negative, which leads to the occurrence of a faceted interface. The higher the absolute value of thermal gradients, the faster the growth velocity. Due to differences in the degree of undercooling, there will be the unification of facets in front of the solid-liquid interface. Transitions from faceted front to thermal equiaxed dendrites or faceted equiaxed grains are observed with smaller or larger impurity contents, respectively. Full article
(This article belongs to the Section Optics and Lasers)
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Open AccessArticle Free Vibration Analysis of Functionally Graded Porous Doubly-Curved Shells Based on the First-Order Shear Deformation Theory
Appl. Sci. 2017, 7(12), 1252; doi:10.3390/app7121252
Received: 28 October 2017 / Revised: 27 November 2017 / Accepted: 29 November 2017 / Published: 2 December 2017
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Abstract
Due to some technical issues that can appear during the manufacturing process of Functionally Graded Materials (FGMs), it can be extremely difficult to produce perfect materials. Indeed, one of the biggest problems is the presence of porosities. For this purpose, the vibrational behavior
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Due to some technical issues that can appear during the manufacturing process of Functionally Graded Materials (FGMs), it can be extremely difficult to produce perfect materials. Indeed, one of the biggest problems is the presence of porosities. For this purpose, the vibrational behavior of doubly-curved shells made of FGM including porosities is investigated in this paper. With respect to previous research, the porosity has been added to the mechanical model that characterizes the through-the-thickness distribution of the graded constituents and applied to doubly-curved shell structures. Few papers have been published on this topic. In fact, it is easier to find works related to one-dimensional structures and beam models that take account the effect of porosities. The First-order Shear Deformation Theory (FSDT) is considered as the theoretical framework. In addition, the mechanical properties of the constituents vary along the thickness direction. For this purpose, two power-law distributions are employed to characterize their volume fraction. Strain components are established in an orthogonal curvilinear coordinate system and the governing equations are derived according to the Hamilton’s principle. Finally, Navier’s solution method is used and the numerical results concerning three different types of shell structures are presented. Full article
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Open AccessFeature PaperArticle Non-Destructive Infrared Evaluation of Thermo-Physical Parameters in Bamboo Specimens
Appl. Sci. 2017, 7(12), 1253; doi:10.3390/app7121253
Received: 1 November 2017 / Revised: 24 November 2017 / Accepted: 27 November 2017 / Published: 2 December 2017
PDF Full-text (1108 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The estimation of heat conduction properties has considerable importance in the characterization of bamboo with respect to its potential use as an alternative construction material. Even though traditional methods such as hot plates have successfully measured thermal parameters, like thermal diffusivity and conductivity
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The estimation of heat conduction properties has considerable importance in the characterization of bamboo with respect to its potential use as an alternative construction material. Even though traditional methods such as hot plates have successfully measured thermal parameters, like thermal diffusivity and conductivity in bamboo samples, it is still necessary to transform the cylindrical bamboo specimen into a piece with special geometry and size. This requirement makes this method impractical in applications where several bamboo specimens need to be measured in their original cylindrical shape. This paper presents the estimation of thermo-physical parameters k and ρ c p in Guadua angustifolia kunth (Guadua a.k.) bamboo through nonlinear least square optimization and infrared thermography. A sensitivity analysis was carried out to determine how the temperature on the bamboo surface is affected by changes in the convection coefficient h, thermal conductivity k, and volumetric heat capacity ρ c p . In spite of the nonlinearity and high correlation in the parameters of the inverse heat conduction problem (IHCP), the estimation of such parameters is robust and consistent with those reported in the literature. Full article
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Open AccessArticle The Effects of Thermoplastic Polyurethane on the Structure and Mechanical Properties of Modified Polypropylene Blends
Appl. Sci. 2017, 7(12), 1254; doi:10.3390/app7121254
Received: 25 October 2017 / Revised: 19 November 2017 / Accepted: 29 November 2017 / Published: 3 December 2017
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Abstract
In this study, a melt-compounding process was used to produce ordinary polypropylene (PP)/thermoplastic polyurethane (TPU) blends and modified impact-resistant polypropylene (MPP)/TPU blends. The influences of TPU on the blending morphology, melting behavior, crystallization behavior, and mechanical properties of these blends were investigated. Differential
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In this study, a melt-compounding process was used to produce ordinary polypropylene (PP)/thermoplastic polyurethane (TPU) blends and modified impact-resistant polypropylene (MPP)/TPU blends. The influences of TPU on the blending morphology, melting behavior, crystallization behavior, and mechanical properties of these blends were investigated. Differential scanning calorimetry results show that using TPU influences the crystalline and melting behavior of PP/TPU blends, but not of MPP/TPU blends. X-ray diffraction analysis indicated that the presence of TPU neither influences the crystalline structure of PP nor creates new crystalline peaks. The mechanical property test results revealed that PP/TPU blends demonstrate better tensile strength, Young’s modulus, and flexural strength, whereas MPP/TPU blends exhibit higher energy absorption and impact strength. This study is expected to produce optimal products with the preferred continuous and dispersive phases for end users, designing multiple and compatible functionalities of blends. Full article
(This article belongs to the Section Materials)
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Open AccessFeature PaperArticle Elution of Artificial Sputum from Swab by Rotating Magnetic Field-Induced Mechanical Impingement
Appl. Sci. 2017, 7(12), 1255; doi:10.3390/app7121255
Received: 2 October 2017 / Revised: 29 November 2017 / Accepted: 30 November 2017 / Published: 3 December 2017
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Abstract
Cotton-tipped applicator swabs are used as a collection device for many biological samples and its complete elution is a desired step for clinical and forensic diagnostics. Swabs are used to collect infectious body fluids, where the concentration of pathogens can range from 1
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Cotton-tipped applicator swabs are used as a collection device for many biological samples and its complete elution is a desired step for clinical and forensic diagnostics. Swabs are used to collect infectious body fluids, where the concentration of pathogens can range from 1 × 104 CFU/mL (colony forming units/mL) in respiratory-tract infections and 1 × 105 in urinary-tract infections, to up to 1 × 109 CFU/mL in salivary samples. These samples are then eluted and lysed, prior to DNA (De-oxy Ribonucleic Acid) analysis. The recovery of micro-organisms from a matrix of swab fibres depends on the nature of the body fluid, the type of the swab fibres, and the process of elution. Various methods to elute samples from swab include chemical digestion of fibres (~20% recovery), centrifugation (~58% recovery), piezoelectric vibration, or pressurized fluid-flow (~60% recovery). This study reports a magnetically-actuated physical impingement method for elution and recovery of artificial sputum samples from cotton fibres. A device has been fabricated to induce a rotating magnetic field on smaller magnetic particles in a vial that strikes the swab within a confined gap. Elution from the swab in this device was characterized using 2% Methyl cellulose in deionised water, loaded with fluorescent-tagged polystyrene beads and E. coli at various concentrations. The recovery efficiency was found to increase with both rotational speed and elution time, but plateaus after 400 RPM (Revolutions per minute) and 120 s, respectively. At a higher concentration of polystyrene beads (5 × 108 particles/mL), a maximum recovery of ~85% was achieved. With lower concentration, (1 × 105 particles/mL) the maximum efficiency (~92.8%) was found to be almost twice of passive elution (46.7%). In the case of E. coli, the corresponding recovery efficiency at 3.35 × 105 CFU/mL is 90.4% at 500 RPM and 120 s. This elution method is expected to have a wide applicability in clinical diagnostics. Full article
(This article belongs to the Special Issue Microsystems for Bio Applications)
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Open AccessArticle Closed Form Solutions for Thermal Buckling of Functionally Graded Rectangular Thin Plates
Appl. Sci. 2017, 7(12), 1256; doi:10.3390/app7121256
Received: 31 October 2017 / Revised: 27 November 2017 / Accepted: 30 November 2017 / Published: 3 December 2017
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Abstract
This work concerns the critical buckling temperature of functionally graded rectangular thin plates; the properties of functionally graded material vary continuously in accordance with the power law of thickness z. Closed form solutions for the critical thermal parameter are obtained for the
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This work concerns the critical buckling temperature of functionally graded rectangular thin plates; the properties of functionally graded material vary continuously in accordance with the power law of thickness z. Closed form solutions for the critical thermal parameter are obtained for the plate with the following boundary condition combinations: simply supported, clamped and guided edges, under uniform, linear and nonlinear temperature fields via the separation-of-variable method. Furthermore, a new method is proposed to determine the critical buckling temperature from the critical thermal parameter. The present results coincide well with those in the literature, verifying the correctness of the present method. The influences of the length–thickness ratio, length–width ratio, power law index and initial temperature on critical buckling temperature are investigated. Full article
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Open AccessArticle Simultaneous Extraction, Enrichment and Removal of Dyes from Aqueous Solutions Using a Magnetic Aqueous Micellar Two-Phase System
Appl. Sci. 2017, 7(12), 1257; doi:10.3390/app7121257
Received: 10 November 2017 / Revised: 24 November 2017 / Accepted: 29 November 2017 / Published: 10 December 2017
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Abstract
The magnetic aqueous micellar two-phase system (MAMTPS) has the advantages combined of magnetic solid phase extraction (MSPE) and aqueous micellar two-phase system (AMTPS). Thus, MAMTPS based on Fe3O4 magnetic nanoparticles (MNPs) and a nonionic surfactant Triton X-114 (TX-114) was developed
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The magnetic aqueous micellar two-phase system (MAMTPS) has the advantages combined of magnetic solid phase extraction (MSPE) and aqueous micellar two-phase system (AMTPS). Thus, MAMTPS based on Fe3O4 magnetic nanoparticles (MNPs) and a nonionic surfactant Triton X-114 (TX-114) was developed for the extraction, enrichment and removal of three dyes (Congo red, methyl blue, and methyl violet) from aqueous solutions in this study. The MNPs Fe3O4@NH2 was screened as the optimal MNPs benefiting the extraction. Then, the influencing factors of MNPs amount, TX-114 concentration, vibration time, and extraction temperature were investigated in detail. The results showed that the extraction efficiencies of three dyes almost reached 100% using MAMTPS under the optimal conditions; MAMTPS had higher extraction ability than the individual MSPE or AMTPS. Thus, MAMTPS had the advantages of simple operation, high extraction ability, easy recycling of MNPs, and short phase-separation time, which showspotential for use in the extraction and analysis of contaminants from water samples. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Synthesis and Properties of Shape Memory Poly(γ-Benzyl-l-Glutamate)-b-Poly(Propylene Glycol)-b-Poly(γ-Benzyl-l-Glutamate)
Appl. Sci. 2017, 7(12), 1258; doi:10.3390/app7121258
Received: 31 October 2017 / Revised: 18 November 2017 / Accepted: 30 November 2017 / Published: 4 December 2017
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Abstract
Shape memory polymers (SMPs) have attracted much attention as an important class of stimuli-responsive materials for biomedical applications. For SMP-based biomaterials, in addition to suitable shape recovery performances, their mechanical properties, biodegradability, biocompatibility, and sterilizability needs to be considered. Polypeptides can satisfy the
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Shape memory polymers (SMPs) have attracted much attention as an important class of stimuli-responsive materials for biomedical applications. For SMP-based biomaterials, in addition to suitable shape recovery performances, their mechanical properties, biodegradability, biocompatibility, and sterilizability needs to be considered. Polypeptides can satisfy the requirements outlined above. However, there are few reports on shape memory polypeptides. In this paper, shape memory poly(γ-benzyl-l-glutamate) (PBLG-PPG-PBLG) was synthesized by ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydrides (BLG-NCA) with poly(propylene glycol) bis(2-aminopropyl ether) as the macroinitiator. 1H Nuclear Magnetic Resonance (NMR) and Fourier-Transform Infrared Spectroscopy (FTIR) were used to characterize the structure of the obtained PBLG-PPG-PBLG. The FTIR analysis showed that PBLG-PPG-PBLG has α-helical and β-sheet structures. PBLG-PPG-PBLG has good shape memory properties, its shape recovery time is less than 120 s, and its shape recovery rate is 100%. In this study, we reported a simple synthetic method to obtain intelligent polypeptide materials, which will be used in many biomedical applications. Full article
(This article belongs to the Special Issue Shape Memory Polymers)
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Open AccessArticle Observation and Simulation of Axle Box Acceleration in the Presence of Rail Weld in High-Speed Railway
Appl. Sci. 2017, 7(12), 1259; doi:10.3390/app7121259
Received: 17 October 2017 / Revised: 7 November 2017 / Accepted: 30 November 2017 / Published: 4 December 2017
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Abstract
Rail welds are widely used in high-speed railways and short-wave irregularities usually appear due to limitations in welding technology. These irregularities can excite a high wheel/rail force and are regarded as the main cause of deterioration in track structures. To measure this fierce
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Rail welds are widely used in high-speed railways and short-wave irregularities usually appear due to limitations in welding technology. These irregularities can excite a high wheel/rail force and are regarded as the main cause of deterioration in track structures. To measure this fierce force (or deterioration of the rail weld), axle box acceleration is treated as an effective and economic measure, though an exact quantitative relation between these two quantities remains elusive. This paper aims to develop such a relation in order to provide a new theoretical basis and an analysis method for monitoring and controlling weld geometry irregularity. To better understand the characteristics of axle box acceleration, the paper consists of two parts: an observation and a numerical simulation of axle box acceleration by rail welds. Based on measured data from field tests, axle box acceleration at rail welds was found to have high-frequency vibrations in two frequency bands (i.e., 350–500 Hz and 1000–1200 Hz). Upon analyzing the vibration characteristics in time–frequency domains, the exact location of the rail weld irregularity could be identified. Subsequently, a 3D high-speed wheel/rail rolling contact finite element model was employed to investigate the effect of rail weld geometry on axle box acceleration, and led to the discovery that the weld length and depth determine the vibration frequency and amplitude of the axle box acceleration, respectively. A quantitative relation between axle box acceleration and wheel/rail force has also been determined. Finally, we propose an approach for real-time health detection of rail welds and discuss the influence of other defects and rail welds on the acceleration signal of the axle box. Full article
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Open AccessArticle Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes
Appl. Sci. 2017, 7(12), 1260; doi:10.3390/app7121260
Received: 30 September 2017 / Revised: 28 November 2017 / Accepted: 29 November 2017 / Published: 4 December 2017
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Abstract
Significant differences in the heat transfer behaviors of supercritical carbon dioxide in a heated channel have been observed at different mass fluxes. At low mass fluxes, a unique heat transfer characteristic is accompanied by a monotonously smooth temperature variation without any temperature peak,
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Significant differences in the heat transfer behaviors of supercritical carbon dioxide in a heated channel have been observed at different mass fluxes. At low mass fluxes, a unique heat transfer characteristic is accompanied by a monotonously smooth temperature variation without any temperature peak, even though the ratio of heat flux to mass flux (q/G) is high. In this study, experimental and numerical investigations explore the hidden mechanism of the peculiar heat transfer characteristics of supercritical carbon dioxide at low mass fluxes in vertically upward tubes with inside diameters (ID) of 5 mm. The range of operating conditions examined within the study include a mass flux (G) between 0–200 kg/m2s, and a heat flux (q) of up to 120 kW/m2. The parametric effects within these experimental conditions were analyzed on the basis of the obtained heat transfer data. Furthermore, a qualitative modeling force analysis and quantitative numerical simulation of vertical flow at low mass flux reveal the heat transfer mechanism for these temperature profiles. In addition, the distribution of flow parameters and thermo-physical properties (such as shear stress, density, and specific heat) in the near-wall region were also studied. It is found that the heat transfer behavior of supercritical CO2 at low mass flux is similar to “film boiling” at subcritical pressure, where “vapor-like” fluid occupies the sublayer region. Due to reduced buoyancy, the fluid does not cause enough mixing/instability to bring it to the bulk flow. Full article
(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)
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Open AccessArticle Off-Line Optimization Based Active Control of Torsional Oscillation for Electric Vehicle Drivetrain
Appl. Sci. 2017, 7(12), 1261; doi:10.3390/app7121261
Received: 26 September 2017 / Revised: 25 November 2017 / Accepted: 29 November 2017 / Published: 4 December 2017
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Abstract
As there is no clutch or hydraulic torque converter in electric vehicles to buffer and absorb torsional vibrations. Oscillation will occur in electric vehicle drivetrains when drivers tip in/out or are shifting. In order to improve vehicle response to transients, reduce vehicle jerk
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As there is no clutch or hydraulic torque converter in electric vehicles to buffer and absorb torsional vibrations. Oscillation will occur in electric vehicle drivetrains when drivers tip in/out or are shifting. In order to improve vehicle response to transients, reduce vehicle jerk and reduce wear of drivetrain parts, torque step changes should be avoided. This article mainly focuses on drivetrain oscillations caused by torque interruption for shifting in a Motor-Transmission Integrated System. It takes advantage of the motor responsiveness, an optimal active control method is presented to reduce oscillations by adjusting motor torque output dynamically. A rear-wheel-drive electric vehicle with a two gear automated manual transmission is considered to set up dynamic differential equations based on Newton’s law of motion. By linearization of the affine system, a joint genetic algorithm and linear quadratic regulator method is applied to calculate the real optimal motor torque. In order to improve immediacy of the control system, time consuming optimization process of parameters is completed off-line. The active control system is tested in AMEsim® and limitation of motor external characteristics are considered. The results demonstrate that, compared with the open-loop system, the proposed algorithm can reduce motion oscillation to a satisfied extent when unloading torque for shifting. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle A New Compact Octagonal Shape Perfect Metamaterial Absorber for Microwave Applications
Appl. Sci. 2017, 7(12), 1263; doi:10.3390/app7121263
Received: 31 October 2017 / Revised: 22 November 2017 / Accepted: 29 November 2017 / Published: 6 December 2017
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Abstract
A new compact octagonal shape perfect metamaterial absorber (PMA) design, numerical simulation, fabrication, and investigational verification of unit cell that is based on a simple structure are presented in this paper. The suggested structure comprised of three layers, in which interact to produce
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A new compact octagonal shape perfect metamaterial absorber (PMA) design, numerical simulation, fabrication, and investigational verification of unit cell that is based on a simple structure are presented in this paper. The suggested structure comprised of three layers, in which interact to produce the plasmonic resonances. The finite-integration technique (FIT) based Computer Simulation Technology (CST) microwave electromagnetic simulator was utilized to examine the design parameters and conduct absorption analysis. The design structure exhibited peak absorption values as 99.64% and 99.95% at frequencies 8.08 GHz and 11.41 GHz, respectively. The absorption characteristics were analysed using the polarization angle of the structure, layer thickness, PMA with resistive load, and number of rings. An N5227A vector network analyser was used for the measurement. The measured results of the fabricated prototype were in good agreement with the simulation results. The suggested perfect absorber structure enables innumerable application aimed at X-band for applications like, defence, security, and stealth technology. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle Joint QoS and Congestion Control Based on Traffic Prediction in SDN
Appl. Sci. 2017, 7(12), 1265; doi:10.3390/app7121265
Received: 3 November 2017 / Revised: 28 November 2017 / Accepted: 29 November 2017 / Published: 5 December 2017
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Abstract
Due to the various network requirements of applications, quality of service (QoS)-aware routing plays an important role in the networks. Recently proposed resource allocation algorithms focus on the current traffic matrix, which is not applicable for dynamic networks. In this paper, we exploit
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Due to the various network requirements of applications, quality of service (QoS)-aware routing plays an important role in the networks. Recently proposed resource allocation algorithms focus on the current traffic matrix, which is not applicable for dynamic networks. In this paper, we exploit an estimation of flow matrix that gives our scheme the ability to sufficiently reduce the total packet loss and simultaneously raise the network throughput. In this way, we mathematically formulate the QoS-aware resource reallocation in software-defined networking (SDN) networks based on the traffic prediction. To solve this optimization problem, two schemes are proposed: (i) exact solution; and (ii) fast suboptimal one. The proposed schemes are compared with the accuracy perspective. Moreover, the impact of prediction on resource reallocation is discussed. In this regard, it is shown that, compared with the conventional scheme, the proposed scheme decreases the packet loss and increases the throughput significantly. Full article
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Open AccessArticle Modeling and Dynamic Analysis on the Direct Operating Solenoid Valve for Improving the Performance of the Shifting Control System
Appl. Sci. 2017, 7(12), 1266; doi:10.3390/app7121266
Received: 7 November 2017 / Revised: 27 November 2017 / Accepted: 1 December 2017 / Published: 5 December 2017
PDF Full-text (5300 KB) | HTML Full-text | XML Full-text
Abstract
The dynamic characteristics and energy loss in a shifting control system is important and necessary in the performance improvement of an automatic transmission. The direct operating solenoid valve has been considered as a potential component applying in the shifting control system in vehicle.
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The dynamic characteristics and energy loss in a shifting control system is important and necessary in the performance improvement of an automatic transmission. The direct operating solenoid valve has been considered as a potential component applying in the shifting control system in vehicle. The previous method can solve only a specific physical field or use the test results of the magnetic force as input curve. The paper presents a numerical approach for solving the multi-domain physical problem of the valve. A precise model of the direct acting solenoid valve considering different physical field is developed. An experimental study is also performed to evaluate and confirm the simulation. Based on the model, the influences on the dynamic characteristics of the valve are analyzed by calculating forces acting on the valve. The systematic analysis of forces and energy loss characteristics are performed for three different flow conditions varying clearance height from 10 µm to 30 µm. The results demonstrate that the pressure response time can be improved with smaller clearance between the spool and the sleeve. Moreover, the leakage of the shifting control system employing the direct acting solenoid valve can be reduced by 60% compared to the conventional two-stage pilot valve in our previous product. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessFeature PaperArticle Storage Stability of Bimodal Emulsions vs. Monomodal Emulsions
Appl. Sci. 2017, 7(12), 1267; doi:10.3390/app7121267
Received: 13 September 2017 / Revised: 30 November 2017 / Accepted: 2 December 2017 / Published: 5 December 2017
PDF Full-text (5281 KB) | HTML Full-text | XML Full-text
Abstract
Storage stability is a very important parameter that has to be considered in the formulation of asphalt emulsions. When monomodal emulsions are formulated, Stokes’ law is fulfilled, therefore the higher the viscosity the less sedimentation, or the lower average droplet size the less
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Storage stability is a very important parameter that has to be considered in the formulation of asphalt emulsions. When monomodal emulsions are formulated, Stokes’ law is fulfilled, therefore the higher the viscosity the less sedimentation, or the lower average droplet size the less sedimentation. But when bimodal emulsions are formulated, this rule does not apply. In this paper, two types of different emulsions are formulated: monomodal emulsions and bimodal emulsions. Bimodal emulsions are a combination of one large bitumen size and a small one. For this study, hard penetration bitumens were used, B35/50 and B15/25, because they are the most difficult bitumen to emulsify and, consequently, the worst sedimentation values are expected. Once the emulsions are manufactured, they are diluted to a bitumen rate concentration of 60% and 70%. Results show that bimodal emulsions, although having lower viscosity than their monomodal counterparts, have higher storage stability. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Precision Obtained Using an Artificial Neural Network for Predicting the Material Removal Rate in Ultrasonic Machining
Appl. Sci. 2017, 7(12), 1268; doi:10.3390/app7121268
Received: 15 September 2017 / Revised: 27 October 2017 / Accepted: 8 November 2017 / Published: 5 December 2017
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Abstract
The present study proposes a back propagation artificial neural network (BPANN) to provide improved precision for predicting the material removal rate (MRR) in ultrasonic machining. The BPANN benefits from the advantage of artificial neural networks (ANNs) in dealing with complex input-output relationships without
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The present study proposes a back propagation artificial neural network (BPANN) to provide improved precision for predicting the material removal rate (MRR) in ultrasonic machining. The BPANN benefits from the advantage of artificial neural networks (ANNs) in dealing with complex input-output relationships without explicit mathematical functions. In our previous study, a conventional linear regression model and improved nonlinear regression model were established for modelling the MRR in ultrasonic machining to reflect the influence of machining parameters on process response. In the present work, we quantitatively compare the prediction precision obtained by the previously proposed regression models and the presently proposed BPANN model. The results of detailed analyses indicate that the BPANN model provided the highest prediction precision of the three models considered. The present work makes a positive contribution to expanding the applications of ANNs and can be considered as a guide for modelling complex problems of general machining. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Investigating the Role of Shell Thickness and Field Cooling on Saturation Magnetization and Its Temperature Dependence in Fe3O4/γ-Fe2O3 Core/Shell Nanoparticles
Appl. Sci. 2017, 7(12), 1269; doi:10.3390/app7121269
Received: 31 October 2017 / Revised: 15 November 2017 / Accepted: 21 November 2017 / Published: 5 December 2017
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Abstract
Understanding saturation magnetization and its behavior with particle size and temperature are essential for medical applications such magnetic hyperthermia. We report the effect of shell thickness and field cooling on the saturation magnetization and its behavior with temperature in Fe3O4
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Understanding saturation magnetization and its behavior with particle size and temperature are essential for medical applications such magnetic hyperthermia. We report the effect of shell thickness and field cooling on the saturation magnetization and its behavior with temperature in Fe3O4/γ-Fe2O3 core/shell nanoparticles of fixed core diameter (8 nm) and several shell thicknesses. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM)) were used to investigate the phase and the morphology of the samples. Selected area electron diffraction (SAED) confirmed the core/shell structure and phases. Using a SQUID (San Diego, CA, USA), magnetic measurements were conducted in the temperature range of 2 to 300 K both under zero field-cooling (ZFC) and field-cooling (FC) protocols at several field-cooling values. In the ZFC state, considerable enhancement of saturation magnetization was obtained with the increase of shell thickness. After field cooling, we observed a drastic enhancement of the saturation magnetization in one sample up to 120 emu/g (50% larger than the bulk value). In both the FC and ZFC states, considerable deviations from the original Bloch’s law were observed. These results are discussed and attributed to the existence of interface spin-glass clusters which are modified by the changes in the shell thickness and the field-cooling. Full article
(This article belongs to the Special Issue Biological Applications of Magnetic Nanoparticles)
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Open AccessArticle Modeling of Cyclic Strength for the Asphalt Concrete Considering Damage Accumulation
Appl. Sci. 2017, 7(12), 1270; doi:10.3390/app7121270
Received: 14 November 2017 / Revised: 27 November 2017 / Accepted: 30 November 2017 / Published: 5 December 2017
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Abstract
The expression is obtained for determination of cyclic tensile strength for asphalt concrete, which considers damage accumulation and history of loading, using the long-term strength curve for asphalt concrete obtained according to the test results of more than 110 samples to failure at
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The expression is obtained for determination of cyclic tensile strength for asphalt concrete, which considers damage accumulation and history of loading, using the long-term strength curve for asphalt concrete obtained according to the test results of more than 110 samples to failure at stresses from 0.05 to 0.31 MPa and by introduction of damage kernel in this paper. Cyclic strength depends on the stress, parameters of long-term strength, frequency of loading, durations of loading and relax periods, and ratio of loading period to the long-term strength. Evaluation of accuracy for the obtained expression for the cyclic strength has been performed by comparison with the results of a series for experimental tests of asphalt concrete samples at a temperature of 22 °С and cyclic loading conditions. The stress is 0.31 MPa, and the durations of loading and relax periods are 5 and 60 s, respectively. Calculations performed with the obtained expressions at real road conditions (the stress is 0.31 MPa, and the durations of loading and relax periods are 0.1 and 9.9 s respectively) showed the possibility of its use for the prediction of fatigue (multicyclic) strength of an asphalt concrete pavement for a highway. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Structural Health Monitoring of a Road Tunnel Intersecting a Large and Active Landslide
Appl. Sci. 2017, 7(12), 1271; doi:10.3390/app7121271
Received: 10 October 2017 / Revised: 13 November 2017 / Accepted: 1 December 2017 / Published: 5 December 2017
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Abstract
Dealing with engineering structures that are not easily replaceable requires frequent assessment of the damage state of the construction in order to estimate its durability and reliability. The procedures that allow damage to be detected and identified are broadly defined as Structural Health
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Dealing with engineering structures that are not easily replaceable requires frequent assessment of the damage state of the construction in order to estimate its durability and reliability. The procedures that allow damage to be detected and identified are broadly defined as Structural Health Monitoring (SHM). In this work, a SHM network has been deployed in a road tunnel that intersects a massive landslide, whose movements are causing the formation of cracks along the tunnel lining. The monitoring system measures in real time the displacements across major cracks and the rotation of the tunnel segments; data are gathered and made easily accessible through a web-based platform. The mechanisms by which the tunnel deforms under the landslide-induced stress have been defined through the analysis of three years of monitoring data. The factors triggering an increase in deformation rates and causing damage to the structure have also been investigated. This evidence will support the design of mitigation works to extend the life-span of the tunnel. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Design and Implementation of Model Predictive Control for a Gyroscopic Inverted Pendulum
Appl. Sci. 2017, 7(12), 1272; doi:10.3390/app7121272
Received: 10 October 2017 / Revised: 20 November 2017 / Accepted: 4 December 2017 / Published: 6 December 2017
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Abstract
This study proposes the design of an active stabilizing system (ASAS) for a single-track vehicle. Using the gyroscopic effects of two flywheels, this system can generate control torque to stabilize the vehicle in cases where there is centrifugal force of turning. To control
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This study proposes the design of an active stabilizing system (ASAS) for a single-track vehicle. Using the gyroscopic effects of two flywheels, this system can generate control torque to stabilize the vehicle in cases where there is centrifugal force of turning. To control the flywheel gimbals to generate stabilizing torque, a model predictive controller (MPC) is applied to control the system. For the controller design and performance evaluations, a model of a gyroscopic inverted pendulum is developed. Control strategies are proposed to stabilize the vehicle in the cases of straight running, circular motion, and path following. The results of the proposed stratgies when controlling the gyroscopic inverted pendulum showed good performance even with physical limitations of the control torques. In order to evaluate the real-time performance and the feasibility of the MPC, a real-time simulator is employed, which includes two embedded STM32F407 boards. The dynamic system and the control algorithms are respectively embedded into two STM32F407 boards for real-time simulation. Implementations of the MPC in this study demonstrate that the proposed controllers are feasible for real-time applications. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle A Performance Test and Internal Flow Field Simulation of a Vortex Pump
Appl. Sci. 2017, 7(12), 1273; doi:10.3390/app7121273
Received: 17 September 2017 / Revised: 29 November 2017 / Accepted: 1 December 2017 / Published: 7 December 2017
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Abstract
Vortex pumps have good non-clogging performance and are widely used in the fluid transportation of food, sewage treatment, and mineral and coal slurry transportation. In order to design and manufacture a vortex pump with good performance and establish a method of optimum design,
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Vortex pumps have good non-clogging performance and are widely used in the fluid transportation of food, sewage treatment, and mineral and coal slurry transportation. In order to design and manufacture a vortex pump with good performance and establish a method of optimum design, we must master the internal flow rules of the pump. Based on the self-design vortex pump (32WB8-12) experiment, the discharge-pump head (qv-H), discharge-pump shaft power (qv-P), discharge-pump efficiency (qv-η), and discharge-critical net positive suction head (qv-NPSHc) curves are obtained, and the qv-NPSHc curve shows an opposite tendency compared with the centrifugal pump. With the mathematical model selected with respect to the optimal condition, the three-dimensional internal flow within the vortex pump has been numerically simulated by a renormalization group k-ε (RNG k-ε) turbulence model. The static pressure (ps) and velocity distribution of the impeller and the middle section of the volute at 0°, 90°, 180°, and 270° are obtained, and the performance curves have been fitted using a CFX-calculated energy parameter. It was illustrated that the velocity field is relatively disordered and the flow in the impeller region is of a forced vortex character. The flow in the volute is similar to that of the combined vortex with backflow, which is a non-axisymmetric unsteady flow with quite high turbulence intensity. These factors are the main reasons for the relatively low efficiency of the vortex pump. The measurement of flow field in volute with a five-hole probe was conducted, and it is demonstrated that the numerical results are in good agreement with the flow field measurement data. An upward pressure gradient forms in the portal area of the impeller, and it is confirmed that the lowest pressure point is located in the upper position of the impeller hub. It is revealed that for the vortex pump to have advanced suction and anti-cavitation performance, the lowest pressure in the pump should be −4 × 104 Pa and it should be located at the center of the vortex chamber cavity. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessArticle Fatigue Analysis of Greenhouse Structure under Wind Load and Self-Weight
Appl. Sci. 2017, 7(12), 1274; doi:10.3390/app7121274
Received: 7 November 2017 / Revised: 28 November 2017 / Accepted: 29 November 2017 / Published: 7 December 2017
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Abstract
The design strength of a greenhouse structure is generally determined by analyzing strength after applying wind load using the wind pressure coefficient according to a design guide. Until now, the stability analysis for wind load has been performed through static structural analysis. However,
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The design strength of a greenhouse structure is generally determined by analyzing strength after applying wind load using the wind pressure coefficient according to a design guide. Until now, the stability analysis for wind load has been performed through static structural analysis. However, a greenhouse is subjected to dynamic wind loads of various amplitudes, and it is reasonable to judge stability through fatigue analysis. For fatigue analysis, a stress-normalized model was constructed based on the square of wind speed, and the value obtained by squaring wind speed was used as dynamic load time data. Life cycle was calculated under stress generated by self-weight by compensating fatigue estimation stress. Furthermore, the effect of self-weight was examined and errors of up to 21% were obtained depending on the configuration of the stress-normalized model. When self-weight and wind speed were applied simultaneously, the effect of self-weight reduced when the stress-normalized model was used at high wind speed. Therefore, it is appropriate that the fatigue analysis is based on the fatigue stress model normalized by the square of wind speed, fatigue estimation stress is corrected to the static stress due to self-weight, and the square of wind speed is used as the dynamic load. Full article
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Open AccessArticle Effects of Low Intensity Continuous Ultrasound (LICU) on Mouse Pancreatic Tumor Explants
Appl. Sci. 2017, 7(12), 1275; doi:10.3390/app7121275
Received: 25 October 2017 / Revised: 29 November 2017 / Accepted: 4 December 2017 / Published: 8 December 2017
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Abstract
This paper describes the effects of low intensity continuous ultrasound (LICU) on the inflammatory response of mouse pancreatic tumor explants. While there are many reports focusing on the application of low-intensity pulsed ultrasound (LIPUS) on cell cultures and tissues, the effects of continuous
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This paper describes the effects of low intensity continuous ultrasound (LICU) on the inflammatory response of mouse pancreatic tumor explants. While there are many reports focusing on the application of low-intensity pulsed ultrasound (LIPUS) on cell cultures and tissues, the effects of continuous oscillations on biological tissues have never been investigated. Here we present an exploratory study of the effects induced by LICU on mouse pancreatic tumor explants. We show that LICU causes significant upregulation of IFN-γ, IL-1β, and TNF-α on tumor explants. No detectable effects were observed on tumor vasculature or collagen I deposition, while thermal and mechanical effects were not apparent. Tumor explants responded as a single unit to acoustic waves, with spatial pressure variations smaller than their size. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle High Power Fiber Laser Welding of Single Sided T-Joint on Shipbuilding Steel with Different Processing Setups
Appl. Sci. 2017, 7(12), 1276; doi:10.3390/app7121276
Received: 2 November 2017 / Revised: 29 November 2017 / Accepted: 4 December 2017 / Published: 8 December 2017
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Abstract
Laser welding of thick plates in production environments is one of the main applications of high power lasers; however, the process has certain limitations. The small spot size of the focused beam produces welds with high depth-to-width aspect ratio but at times fails
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Laser welding of thick plates in production environments is one of the main applications of high power lasers; however, the process has certain limitations. The small spot size of the focused beam produces welds with high depth-to-width aspect ratio but at times fails to provide sufficient reinforcement in certain applications because of poor gap bridging ability. The results of welding shipbuilding steel AH36 with thickness of 8 mm as a single-sided T-joint using a 10 kW fiber laser are presented and discussed in this research paper. Three optical setups with process fibers of 200 µm, 300 µm and 600 µm core diameters were used to study the possibilities and limitations set by the beam delivery system. The main parameters studied were beam inclination angle, beam offset from the joint plane and focal point position. Full penetration joints were produced and the geometry of the welds was examined. It was found that process fibers with smaller core diameter produce deeper penetration but suffer from sensitivity to beam positioning deviation. Larger fibers are less sensitive and produce wider welds but have, in turn, lower penetration at equivalent power levels. Full article
(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)
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Open AccessFeature PaperArticle Wearable Current-Based ECG Monitoring System with Non-Insulated Electrodes for Underwater Application
Appl. Sci. 2017, 7(12), 1277; doi:10.3390/app7121277
Received: 30 September 2017 / Revised: 21 November 2017 / Accepted: 21 November 2017 / Published: 8 December 2017
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Abstract
The second most common cause of diving fatalities is cardiovascular diseases. Monitoring the cardiovascular system in actual underwater conditions is necessary to gain insights into cardiac activity during immersion and to trigger preventive measures. We developed a wearable, current-based electrocardiogram (ECG) device in
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The second most common cause of diving fatalities is cardiovascular diseases. Monitoring the cardiovascular system in actual underwater conditions is necessary to gain insights into cardiac activity during immersion and to trigger preventive measures. We developed a wearable, current-based electrocardiogram (ECG) device in the eco-system of the FitnessSHIRT platform. It can be used for normal/dry ECG measuring purposes but is specifically designed to allow underwater signal acquisition without having to use insulated electrodes. Our design is based on a transimpedance amplifier circuit including active current feedback. We integrated additional cascaded filter components to counter noise characteristics specific to the immersed condition of such a system. The results of the evaluation show that our design is able to deliver high-quality ECG signals underwater with no interferences or loss of signal quality. To further evaluate the applicability of the system, we performed an applied study with it using 12 healthy subjects to examine whether differences in the heart rate variability exist between sitting and supine positions of the human body immersed in water and outside of it. We saw significant differences, for example, in the RMSSD and SDSD between sitting outside the water (36 ms) and sitting immersed in water (76 ms) and the pNN50 outside the water (6.4%) and immersed in water (18.2%). The power spectral density for the sitting positions in the TP and HF increased significantly during water immersion while the LF/HF decreased significantly. No significant changes were found for the supine position. Full article
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Open AccessArticle The Effects of Musical Experience and Hearing Loss on Solving an Audio-Based Gaming Task
Appl. Sci. 2017, 7(12), 1278; doi:10.3390/app7121278
Received: 23 October 2017 / Revised: 2 December 2017 / Accepted: 5 December 2017 / Published: 10 December 2017
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Abstract
We conducted an experiment using a purposefully designed audio-based game called the Music Puzzle with Japanese university students with different levels of hearing acuity and experience with music in order to determine the effects of these factors on solving such games. A group
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We conducted an experiment using a purposefully designed audio-based game called the Music Puzzle with Japanese university students with different levels of hearing acuity and experience with music in order to determine the effects of these factors on solving such games. A group of hearing-impaired students (n = 12) was compared with two hearing control groups with the additional characteristic of having high (n = 12) or low (n = 12) engagement in musical activities. The game was played with three sound sets or modes; speech, music, and a mix of the two. The results showed that people with hearing loss had longer processing times for sounds when playing the game. Solving the game task in the speech mode was found particularly difficult for the group with hearing loss, and while they found the game difficult in general, they expressed a fondness for the game and a preference for music. Participants with less musical experience showed difficulties in playing the game with musical material. We were able to explain the impacts of hearing acuity and musical experience; furthermore, we can promote this kind of tool as a viable way to train hearing by focused listening to sound, particularly with music. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Hardware-in-the-Loop Based Co-Simulation Platform of Cyber-Physical Power Systems for Wide Area Protection Applications
Appl. Sci. 2017, 7(12), 1279; doi:10.3390/app7121279
Received: 24 October 2017 / Revised: 4 December 2017 / Accepted: 6 December 2017 / Published: 8 December 2017
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Abstract
With the development of smart grid technology, there has been an increasingly strong tendency towards the integration between the aspects of power and communication. The traditional power system has gradually transformed into the cyber-physical power system (CPPS), where co-simulation technologies can be utilized
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With the development of smart grid technology, there has been an increasingly strong tendency towards the integration between the aspects of power and communication. The traditional power system has gradually transformed into the cyber-physical power system (CPPS), where co-simulation technologies can be utilized as an effective measure to describe the computation, communication, and integration processes of a power grid. In this paper, the construction methods and application scenarios of co-simulation platforms in the current research are first summarized. Then, a scheme of the real-time hardware-in-the-loop co-simulation platform is put forward. On the basis of power grid simulation developed with the Real-Time Laboratory (RT-LAB), and the communication network simulation developed with OPNET, the control center was developed with hardware devices to realize real-world control behavior instead of digital simulations. Therefore, the mixed-signal platform is capable of precisely simulating the dynamic features of CPPS with high speed. The distributed simulation components can be coordinated in a unified environment with high interoperability and reusability. Moreover, through a case study of a wide area load control system, the performance of the proposed platform under various conditions of control strategies, communication environments, and sampling frequencies was revealed and compared. As a result, the platform provided an intuitive and accurate way to reconstruct the CPPS environment where the influence of the information side of the CPPS control effects was verified. Full article
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Open AccessFeature PaperArticle Conscious, Pre-Conscious and Unconscious Mechanisms in Emotional Behaviour. Some Applications to the Mindfulness Approach with Wearable Devices
Appl. Sci. 2017, 7(12), 1280; doi:10.3390/app7121280
Received: 29 October 2017 / Revised: 1 December 2017 / Accepted: 4 December 2017 / Published: 8 December 2017
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Abstract
Conscious, pre-conscious, and unconscious mechanisms are implicated in modulating affective processing in daily activities. Specifically, mental practice fostering awareness and control of affective reactions to external stimuli and stressful events (such as mindfulness and neurofeedback protocols) can be used to improve our ability
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Conscious, pre-conscious, and unconscious mechanisms are implicated in modulating affective processing in daily activities. Specifically, mental practice fostering awareness and control of affective reactions to external stimuli and stressful events (such as mindfulness and neurofeedback protocols) can be used to improve our ability to manage unconscious negative emotions. Indeed, it is possible to empower self-monitoring and regulation skills, as well as our ability to manage stress and negative emotions coming from everyday events and activities. This can be accomplished, on the one hand, by regularly practicing self-observation and by promoting bodily awareness and an awareness of automatic responses (e.g., uncontrolled affective reactions); on the other hand, by undergoing implicit training protocols that take advantage of brain responses. The present paper elucidates the contribution of both conscious and unconscious levels in emotion regulation and stress management, with a focus on their neural correlates and their role in mindfulness practice and on the potential of body-sensing devices for supporting meditation sessions, for fostering motivation to practice, and for making meditation more appealing and sustainable. We will finally present preliminary evidence on the effect of an intensive technology-mediated meditation protocol based on mindfulness practices and supported by a brain-sensing wearable device. The experimental procedure included three levels of outcome indices: psychometric measures related to perceived stress; neuropsychological and behavioural measures related to cognitive performance; and instrumental measures (resting-state and task-related electroencephalographic markers—EEG-ERPs). Full article
(This article belongs to the Special Issue Sub- and Unconscious Information Processing in the Human Brain)
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Open AccessArticle Experimental Investigation on the Influence of a Double-Walled Confined Width on the Velocity Field of a Submerged Waterjet
Appl. Sci. 2017, 7(12), 1281; doi:10.3390/app7121281
Received: 7 November 2017 / Revised: 30 November 2017 / Accepted: 6 December 2017 / Published: 8 December 2017
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Abstract
The current research on confined submerged waterjets mainly focuses on the flow field of the impinging jet and wall jet. The double-sided wall vertically confined waterjet, which is widely used in many fields such as mining, cleaning and surface strengthening, has rarely been
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The current research on confined submerged waterjets mainly focuses on the flow field of the impinging jet and wall jet. The double-sided wall vertically confined waterjet, which is widely used in many fields such as mining, cleaning and surface strengthening, has rarely been studied so far. In order to explore the influence of a double-sided wall confined width on the velocity field of submerged waterjet, an experiment was conducted with the application of 2D particle image velocimetry (PIV) technology. The distribution of mean velocity and turbulent velocity in both horizontal and vertical planes was used to characterize the flow field under various confined widths. The results show that the vertical confinement has an obvious effect on the decay rate of the mean centerline velocity. When the confined width changes from 15 to 5, the velocity is reduced by 20%. In addition, with the decrease of the confined width, the jet has a tendency to spread horizontally. The vertically confined region induces a space hysteresis effect which changes the location of the transition region moving downstream. There are local negative pressure zones separating the fluid and the wall. This study of a double-walled confined jet provides some valuable information with respect to its mechanism and industrial application. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessFeature PaperArticle Optimization of Virtual Loudspeakers for Spatial Room Acoustics Reproduction with Headphones
Appl. Sci. 2017, 7(12), 1282; doi:10.3390/app7121282
Received: 31 October 2017 / Revised: 24 November 2017 / Accepted: 5 December 2017 / Published: 9 December 2017
PDF Full-text (579 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The use of headphones in reproducing spatial sound is becoming more and more popular. For instance, virtual reality applications often use head-tracking to keep the binaurally reproduced auditory environment stable and to improve externalization. Here, we study one spatial sound reproduction method over
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The use of headphones in reproducing spatial sound is becoming more and more popular. For instance, virtual reality applications often use head-tracking to keep the binaurally reproduced auditory environment stable and to improve externalization. Here, we study one spatial sound reproduction method over headphones, in particular the positioning of the virtual loudspeakers. The paper presents an algorithm that optimizes the positioning of virtual reproduction loudspeakers to reduce the computational cost in head-tracked real-time rendering. The listening test results suggest that listeners could discriminate the optimized loudspeaker arrays for renderings that reproduced a relatively simple acoustic conditions, but optimized array was not significantly different from equally spaced array for a reproduction of a more complex case. Moreover, the optimization seems to change the perceived openness and timbre, according to the verbal feedback of the test subjects. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Model-Assisted Reduced-Order ESO Based Cascade Controller for Sensorless Control of Independent Gear-Shifting Actuators
Appl. Sci. 2017, 7(12), 1283; doi:10.3390/app7121283
Received: 26 October 2017 / Revised: 17 November 2017 / Accepted: 7 December 2017 / Published: 9 December 2017
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Abstract
Independent gear-shifting actuation systems, which are based on linear electromagnetic actuators (LEMAs), have tremendous potential to minimize the shifting duration of automated mechanical transmission (AMT). A velocity estimator based on the measurements of current is designed to achieve sensorless control of the actuator
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Independent gear-shifting actuation systems, which are based on linear electromagnetic actuators (LEMAs), have tremendous potential to minimize the shifting duration of automated mechanical transmission (AMT). A velocity estimator based on the measurements of current is designed to achieve sensorless control of the actuator by using only electrical subsystem, thus avoiding the use of a complete system model that contains mechanical uncertainties. The elimination of the position sensor simplifies the structure of the gear-shifting system and reduces the manufacturing cost. To enhance the robustness of the position control, model-assisted reduced-order extended state observer (ESO) based cascade controller is constructed, which take parameter uncertainties and external load force as the lumped disturbance to observe and compensate them dynamically. Finally, simulation and experimental results are shown to demonstrate the effectiveness of the proposed velocity estimator and control method. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle Nanostructured Ceramic Photocatalytic Membrane Modified with a Polymer Template for Textile Wastewater Treatment
Appl. Sci. 2017, 7(12), 1284; doi:10.3390/app7121284
Received: 5 November 2017 / Revised: 27 November 2017 / Accepted: 5 December 2017 / Published: 9 December 2017
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Abstract
Photocatalytic ceramic membranes have attracted considerable attention for industrial wastewater treatment. However, morphological control of the membrane surface to improve its photocatalytic reactivity for the degradation of organic pollutants remains a challenge. Herein, we report a new nanostructured TiO2/Al2O
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Photocatalytic ceramic membranes have attracted considerable attention for industrial wastewater treatment. However, morphological control of the membrane surface to improve its photocatalytic reactivity for the degradation of organic pollutants remains a challenge. Herein, we report a new nanostructured TiO2/Al2O3 composite ceramic membrane prepared from a poly(oxyethylene methacrylate) (POEM) template through a sol–gel method and its photocatalytic performance in the treatment of a model dye compound. The POEM polymeric template allowed the homogeneous distribution of catalytic sites, i.e., the TiO2 layer, on the Al2O3 membrane surface, resulting in improved organic dye degradation along with effective fouling mitigation. The immobilization of a TiO2 layer on the Al2O3 membrane support also significantly enhanced the membrane adsorption capacity toward dye organic compounds. An organic removal efficiency of over 96% was achieved with the TiO2/Al2O3 composite membrane under Ultraviolet (UV) irradiation. In addition, the self-cleaning efficiency of the TiO2/Al2O3 composite membrane was remarkably improved by the degradation of organic foulants on the membrane under UV illumination. Full article
(This article belongs to the Special Issue Nanotechnology in Wastewater Treatment Technology)
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Open AccessFeature PaperArticle Automatic Transcription of Polyphonic Vocal Music
Appl. Sci. 2017, 7(12), 1285; doi:10.3390/app7121285
Received: 31 October 2017 / Revised: 1 December 2017 / Accepted: 4 December 2017 / Published: 11 December 2017
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Abstract
This paper presents a method for automatic music transcription applied to audio recordings of a cappella performances with multiple singers. We propose a system for multi-pitch detection and voice assignment that integrates an acoustic and a music language model. The acoustic model performs
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This paper presents a method for automatic music transcription applied to audio recordings of a cappella performances with multiple singers. We propose a system for multi-pitch detection and voice assignment that integrates an acoustic and a music language model. The acoustic model performs spectrogram decomposition, extending probabilistic latent component analysis (PLCA) using a six-dimensional dictionary with pre-extracted log-spectral templates. The music language model performs voice separation and assignment using hidden Markov models that apply musicological assumptions. By integrating the two models, the system is able to detect multiple concurrent pitches in polyphonic vocal music and assign each detected pitch to a specific voice type such as soprano, alto, tenor or bass (SATB). We compare our system against multiple baselines, achieving state-of-the-art results for both multi-pitch detection and voice assignment on a dataset of Bach chorales and another of barbershop quartets. We also present an additional evaluation of our system using varied pitch tolerance levels to investigate its performance at 20-cent pitch resolution. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Novel Fractional Fourier Transform-Based ASK-OFDM System for Underwater Acoustic Communications
Appl. Sci. 2017, 7(12), 1286; doi:10.3390/app7121286
Received: 29 October 2017 / Revised: 3 December 2017 / Accepted: 6 December 2017 / Published: 11 December 2017
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Abstract
A key research area in wireless transmission is underwater communications. It has a vital role in applications such as underwater sensor networks (UWSNs) and disaster detection. The underwater channel is very unique as compared to other alternatives of transmission channels. It is characterized
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A key research area in wireless transmission is underwater communications. It has a vital role in applications such as underwater sensor networks (UWSNs) and disaster detection. The underwater channel is very unique as compared to other alternatives of transmission channels. It is characterized by path loss, multipath fading, Doppler spread and ambient noise. Thus, the bit error rate (BER) is increased to a large extent when compared to its counterpart of cellular communications. Acoustic signals are the current best solution for underwater communications. The use of electromagnetic or optical waves obviously entails a much higher data rate. However, they suffer from high attenuation, absorption or scattering. This paper proposes a novel fractional fast Fourier transform (FrFT)—orthogonal frequency division multiplexing (FrFT-OFDM) system for underwater acoustic (UWA) communication—which employs the amplitude shift keying (ASK) modulation technique (FrFT-ASK-OFDM). Specifically, ASK achieves a better bandwidth efficiency as compared to other commonly used modulation techniques, such as quadrature amplitude modulation (QAM) and phase shift keying (PSK). In particular, the system proposed in this article can achieve a very promising BER performance, and can reach higher data rates when compared to other systems proposed in the literature. The BER performance of the proposed system is evaluated numerically, and is compared to the corresponding M-ary QAM system in the UWA channel for the same channel conditions. Moreover, the performance of the proposed system is compared to the conventional fast Fourier transform (FFT)-OFDM (FFT-OFDM) system in the absence and presence of the effect of carrier frequency offset (CFO). Numerical results show that the proposed system outperforms the conventional FFT-based systems for UWA channels, even in channels dominated by CFO. Moreover, the spectral efficiency and data rate of the proposed system are approximately double the values of the corresponding conventional OFDM systems for the same parameters. Full article
(This article belongs to the Special Issue Underwater Acoustics, Communications and Information Processing)
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Open AccessArticle Functional Elastic Knits Made of Bamboo Charcoal and Quick-Dry Yarns: Manufacturing Techniques and Property Evaluations
Appl. Sci. 2017, 7(12), 1287; doi:10.3390/app7121287
Received: 2 October 2017 / Revised: 29 November 2017 / Accepted: 5 December 2017 / Published: 11 December 2017
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Abstract
Conventional sportswear fabrics are functional textiles that can mitigate the impaired muscles caused by exercises for the wearers, but they can also cause discomfort and skin allergy. This study proposes combining two yarns to form functional composite yarns, by using a twisting or
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Conventional sportswear fabrics are functional textiles that can mitigate the impaired muscles caused by exercises for the wearers, but they can also cause discomfort and skin allergy. This study proposes combining two yarns to form functional composite yarns, by using a twisting or wrapping process. Moreover, a different twist number is used in order to adjust the performance of functional composite yarns. A crochet machine is used to make the functional composite yarns into functional elastic knits that are suitable for use in sportswear. The test results show that, in comparison to the non-processed yarns, using the twisted or wrapped yarns can considerably decrease the water vapor transmission rate of functional elastic knits by 38%, while also improving their far infrared emissivity by 13%, water absorption rate by 39%, and air permeability by 136%. In particular, the functional elastic knits that are made of B-wrapped yarns (bamboo charcoal- wrapped yarns), composed of 20 twists per inch, have the optimal diverse functions. Full article
(This article belongs to the Special Issue Sports Materials)
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