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Appl. Sci., Volume 7, Issue 9 (September 2017)

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Editorial

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Open AccessEditorial Editorial: Guided-Wave Optics
Appl. Sci. 2017, 7(9), 962; doi:10.3390/app7090962
Received: 11 September 2017 / Revised: 15 September 2017 / Accepted: 15 September 2017 / Published: 20 September 2017
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Abstract
Guided waves represent a vast class of phenomena in which the propagation of collective excitations in various media is steered in required directions by fixed (or, sometimes, reconfigurable) conduits [...]
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(This article belongs to the Special Issue Guided-Wave Optics)

Research

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Open AccessFeature PaperArticle SOA Based Photonic Integrated WDM Cross-Connects for Optical Metro-Access Networks
Appl. Sci. 2017, 7(9), 865; doi:10.3390/app7090865
Received: 30 July 2017 / Revised: 17 August 2017 / Accepted: 18 August 2017 / Published: 23 August 2017
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Abstract
We present a novel optical metro node architecture that exploits the Wavelength Division Multiplexing (WDM) optical cross-connect nodes for interconnecting network elements, as well as computing and storage resources. The photonic WDM cross-connect node based on semiconductor optical amplifiers (SOA) allows switching data
[...] Read more.
We present a novel optical metro node architecture that exploits the Wavelength Division Multiplexing (WDM) optical cross-connect nodes for interconnecting network elements, as well as computing and storage resources. The photonic WDM cross-connect node based on semiconductor optical amplifiers (SOA) allows switching data signals in wavelength, space, and time for fully exploiting statistical multiplexing. The advantages of using an SOA to realize the WDM cross-connect switch in terms of transparency, switching speed, photonic integrated amplification for loss-less operation, and gain equalization are verified experimentally. The experimental assessment of a 4 × 4 photonic integrated WDM cross-connect confirmed the capability of the cross-connect chip to switch the WDM signal in space and wavelength. Experimental results show lossless operation, low cross-talk <−30 dB, and dynamically switch within few nanoseconds. Moreover, the operation of the cross-connect switch with multiple WDM channels and diverse modulation formats is also investigated and reported. Error-free operation with less than a 2 dB power penalty for a single channel, as well as WDM input operation, has been measured for multiple 10/20/40 Gb/s NRZ-OOK, 20 Gb/s PAM4, and data-rate adaptive DMT traffic. Compensation of the losses indicates that the modular architecture could scale to a larger number of ports. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessArticle A Unified Approach for Reformulations of LRM/LRMM/LRRM Calibration Algorithms Based on the T-Matrix Representation
Appl. Sci. 2017, 7(9), 866; doi:10.3390/app7090866
Received: 9 August 2017 / Revised: 18 August 2017 / Accepted: 19 August 2017 / Published: 24 August 2017
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Abstract
This paper investigates a unified theory to derive vector network analyzer calibration algorithms based on the T-matrix representation, by which means the line-reflect-match (LRM), line-reflect-match-match (LRMM), and the line-reflect-reflect-match (LRRM) calibrations are formulated. The proposed calibration theory is more general than other versions
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This paper investigates a unified theory to derive vector network analyzer calibration algorithms based on the T-matrix representation, by which means the line-reflect-match (LRM), line-reflect-match-match (LRMM), and the line-reflect-reflect-match (LRRM) calibrations are formulated. The proposed calibration theory is more general than other versions of LRM, LRMM, and LRRM in that an arbitrary known two-port device can be used as the line standard L, rather than a perfect thru or transmission line. Experimental verifications of the proposed theory using on-wafer calibrations from 0.5 GHz to 110 GHz are given. Full article
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Open AccessArticle Observer-Based Rejection of Cogging Torque Disturbance for Permanent Magnet Motors
Appl. Sci. 2017, 7(9), 867; doi:10.3390/app7090867
Received: 9 July 2017 / Revised: 15 August 2017 / Accepted: 21 August 2017 / Published: 25 August 2017
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Abstract
In order to prove the speed regulation for permanent magnet motor systems, a control method is proposed to reject the disturbance by cogging torque, which arises from the interaction of the rotor magnets with the steel teeth on the stator. Toward this aim,
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In order to prove the speed regulation for permanent magnet motor systems, a control method is proposed to reject the disturbance by cogging torque, which arises from the interaction of the rotor magnets with the steel teeth on the stator. Toward this aim, we present a state observer with an internal model which has harmonics of sinusoids, and it follows from the proposed observer that the information of the cogging disturbance is obtained. It shows that the disturbance is efficiently compensated by a suitable additional control input based on the estimated information. Simulation and experimental results with an actual permanent magnet motor verify the effectiveness of the proposed observer-based algorithm. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle A Neural Networks Approach for Improving the Accuracy of Multi-Criteria Recommender Systems
Appl. Sci. 2017, 7(9), 868; doi:10.3390/app7090868
Received: 28 July 2017 / Revised: 15 August 2017 / Accepted: 16 August 2017 / Published: 25 August 2017
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Abstract
Accuracy improvement has been one of the most outstanding issues in the recommender systems research community. Recently, multi-criteria recommender systems that use multiple criteria ratings to estimate overall rating have been receiving considerable attention within the recommender systems research domain. This paper proposes
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Accuracy improvement has been one of the most outstanding issues in the recommender systems research community. Recently, multi-criteria recommender systems that use multiple criteria ratings to estimate overall rating have been receiving considerable attention within the recommender systems research domain. This paper proposes a neural network model for improving the prediction accuracy of multi-criteria recommender systems. The neural network was trained using simulated annealing algorithms and integrated with two samples of single-rating recommender systems. The paper presents the experimental results for each of the two single-rating techniques together with their corresponding neural network-based models. To analyze the performance of the approach, we carried out a comparative analysis of the performance of each single rating-based technique and the proposed multi-criteria model. The experimental findings revealed that the proposed models have by far outperformed the existing techniques. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Assessment of Sustainability Indicators for Biodiesel Production
Appl. Sci. 2017, 7(9), 869; doi:10.3390/app7090869
Received: 31 July 2017 / Revised: 20 August 2017 / Accepted: 22 August 2017 / Published: 25 August 2017
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Abstract
Biodiesel production may provide a sustainable route to reduce environmental pollution caused by fossil fuel consumption. In order to minimize environmental impacts of biodiesel production, the chemical process should be optimized to minimize waste generation and energy consumption. Therefore, it is important to
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Biodiesel production may provide a sustainable route to reduce environmental pollution caused by fossil fuel consumption. In order to minimize environmental impacts of biodiesel production, the chemical process should be optimized to minimize waste generation and energy consumption. Therefore, it is important to design biodiesel chemical reactions and processes using green chemistry and green engineering principles to develop sustainable chemical processes. This study provides the results of the synergistic effect of microwave and ultrasound irradiations to produce biodiesel using ethanol or methanol as the alcohol donor. The biodiesel yields are presented along with their respective green metrics, such as atom economy, environmental factor (E-factor), atom economy (utilization) or atomic efficiency, mass intensity, reaction mass efficiency, atom utilization, and stoichiometric factor. These green metrics are crucial to determine the sustainability and environmental impact of biodiesel production. Evaluation of these green metrics indicates that methanol is a better alternative for biodiesel production provided it is derived from renewable sources. Sustainability indicator concepts used for biodiesel production in this study can be applied to various biofuels and other chemical reaction designs, synthesis and process development. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Analytical Calculation of Photovoltaic Systems Maximum Power Point (MPP) Based on the Operation Point
Appl. Sci. 2017, 7(9), 870; doi:10.3390/app7090870
Received: 24 July 2017 / Revised: 14 August 2017 / Accepted: 18 August 2017 / Published: 25 August 2017
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Abstract
This work proposes a new analytical model to extract the 1-Diode/2-Resistor solar cell/panel equivalent circuit parameters. The methodology is based on a reduced amount of experimentally measured information: short-circuit current, the slope of the I-V curve at that point, the open-circuit voltage, and
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This work proposes a new analytical model to extract the 1-Diode/2-Resistor solar cell/panel equivalent circuit parameters. The methodology is based on a reduced amount of experimentally measured information: short-circuit current, the slope of the I-V curve at that point, the open-circuit voltage, and the current and voltage levels, together with the slope of the I-V curve at the instantaneous operation point. This procedure is specially designed to analyze the performance of autonomous photovoltaic systems, which are most of the primary sources for spacecraft power. Results show good agreement with experimental data. Furthermore, this methodology allows for fast and accurate I-V curve maximum power point (MPP) identification. Full article
(This article belongs to the Section Energy)
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Open AccessCommunication Effect of Enzymatic Beech Fagus Sylvatica Wood Hydrolysate on Chlorella Biomass, Fatty Acid and Pigment Production
Appl. Sci. 2017, 7(9), 871; doi:10.3390/app7090871
Received: 11 July 2017 / Revised: 13 August 2017 / Accepted: 18 August 2017 / Published: 25 August 2017
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Abstract
This work evaluates the possibility of applying enzymatic beech wood (Fagus sylvatica) hydrolysate as a feedstock for Chlorella sorokiniana growth, and fatty acid and pigment production. Beech wood solids were pretreated with NaOH at high temperature to partially remove xylose and
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This work evaluates the possibility of applying enzymatic beech wood (Fagus sylvatica) hydrolysate as a feedstock for Chlorella sorokiniana growth, and fatty acid and pigment production. Beech wood solids were pretreated with NaOH at high temperature to partially remove xylose and Klason lignin, and enable production of glucose during subsequent enzymatic hydrolysis. Neutralized wood enzymatic hydrolysate containing glucose (TGP-Enz10), was tested on Chlorella growth during heterotrophic cultivation and compared with microalgae growth in a medium containing synthetic glucose (TGP). Results show that enzymatic hydrolysate enabled Chlorella growth in the dark for biomass, fatty acid and pigment production due to the presence of glucose, although the productivity obtained was smaller, if compared to heterotrophic cultivation in a synthetic TGP medium. Partial growth inhibition and diminished productivity in wood hydrolysate supplemented Chlorella culture was due to the presence of neutralized citrate buffer. Neutralized citrate buffer (TGP-Cit10) was found to partially inhibit heterotrophic growth and also strongly suppress mixotrophic growth in Chlorella culture. This buffer was also shown to alter fatty acid composition and to slightly affect ChlTotal/CarTotal ratio during heterotrophic cultivation. Heterotrophic Chlorella cultivation with TGP-Enz10 showed that wood enzymatic hydrolysate can constitute a potential feedstock for microalgae cultivation, although the composition of the buffer used during enzymatic hydrolysis should be taken into consideration. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Modified Adversarial Hierarchical Task Network Planning in Real-Time Strategy Games
Appl. Sci. 2017, 7(9), 872; doi:10.3390/app7090872
Received: 31 July 2017 / Revised: 18 August 2017 / Accepted: 20 August 2017 / Published: 25 August 2017
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Abstract
The application of artificial intelligence (AI) to real-time strategy (RTS) games includes considerable challenges due to the very large state spaces and branching factors, limited decision times, and dynamic adversarial environments involved. To address these challenges, hierarchical task network (HTN) planning has been
[...] Read more.
The application of artificial intelligence (AI) to real-time strategy (RTS) games includes considerable challenges due to the very large state spaces and branching factors, limited decision times, and dynamic adversarial environments involved. To address these challenges, hierarchical task network (HTN) planning has been extended to develop a method denoted as adversarial HTN (AHTN), and this method has achieved favorable performance. However, the HTN description employed cannot express complex relationships among tasks and accommodate the impacts of the environment on tasks. Moreover, AHTN cannot address task failures during plan execution. Therefore, this paper proposes a modified AHTN planning algorithm with failed task repair functionality denoted as AHTN-R. The algorithm extends the HTN description by introducing three additional elements: essential task, phase, and exit condition. If any task fails during plan execution, the AHTN-R algorithm identifies and terminates all affected tasks according to the extended HTN description, and applies a novel task repair strategy based on a prioritized listing of alternative plans to maintain the validity of the previous plan. In the planning process, AHTN-R generates the priorities of alternative plans by sorting all nodes of the game search tree according to their primary features. Finally, empirical results are presented based on a µRTS game, and the performance of AHTN-R is compared to that of AHTN and to the performances of other state-of-the-art search algorithms developed for RTS games. Full article
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Open AccessArticle Monitoring Sound Levels and Soundscape Quality in the Living Rooms of Nursing Homes: A Case Study in Flanders (Belgium)
Appl. Sci. 2017, 7(9), 874; doi:10.3390/app7090874
Received: 28 July 2017 / Revised: 17 August 2017 / Accepted: 24 August 2017 / Published: 26 August 2017
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Abstract
Recently there has been an increasing interest in the acoustic environment and its perceptual counterpart (i.e., the soundscape) of care facilities and their potential to affect the experience of residents with dementia. There is evidence that too loud sounds or poor soundscape quality
[...] Read more.
Recently there has been an increasing interest in the acoustic environment and its perceptual counterpart (i.e., the soundscape) of care facilities and their potential to affect the experience of residents with dementia. There is evidence that too loud sounds or poor soundscape quality more generally can affect negatively the quality of life of people with dementia and increase agitation. The AcustiCare project aims to use the soundscape approach to enhance the Quality of Life (QoL) of residents and to reduce Behavioral and Psychological Symptoms of Dementia (BPSD), as well as improving the everyday experience of nursing homes for both residents and staff members. In order to gain further insights into the sound environments of such facilities, sound level monitoring and soundscape data collection campaigns were conducted in the living rooms of five nursing homes in Flanders. Results showed that sound levels (dB) and loudness levels (sone) did not vary significantly between days of the week, but they did so between moments of the day and between living rooms. From the perceptual point of view, several soundscape attributes and the perceived prominence of different sound source types varied significantly between the living rooms investigated, and a positive correlation was found between sound levels and the number of persons present in the living rooms. These findings claim for further attention on the potential role of the sound domain in nursing homes, which should promote (and not only permit) better living and working conditions for residents and staff members of nursing homes. Full article
(This article belongs to the Section Acoustics)
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Open AccessArticle A Robust Asynchronous Sampled-Data Control Design for Nonlinear Systems with Actuator Failures
Appl. Sci. 2017, 7(9), 875; doi:10.3390/app7090875
Received: 3 August 2017 / Revised: 19 August 2017 / Accepted: 25 August 2017 / Published: 26 August 2017
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Abstract
This paper presents a recent self-sampled-data control algorithm applied to nonlinear systems with actuator failures. Our approach uses the linear model of a given nonlinear system, and based on a granted actuator fault observer method, an asynchronous sampled-data fault compensator controller is then
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This paper presents a recent self-sampled-data control algorithm applied to nonlinear systems with actuator failures. Our approach uses the linear model of a given nonlinear system, and based on a granted actuator fault observer method, an asynchronous sampled-data fault compensator controller is then formulated. The proposed sampling rule is realized by using an event-detector monitoring signal invention. On this way, the sampled rate is self governed and asynchronous by nature. Hence, our contribution is twofold. Fist, a new auto-generated non-uniform sampled-data mechanism is stated. Second, we grant an event-triggered control law with actuator failure observation and compensation. Our findings are completely supported by employing Lyapunov’s theory. Finally, according to our numerical experiments applied to an undamped torsional pendulum, our design is able to detect a failure in the actuator device and it can stabilize the undamped torsional pendulum system presenting better performance in comparison to its open-loop deployment. Full article
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Open AccessArticle Gender Differences in Electroencephalographic Activity in Response to the Earthy Odorants Geosmin and 2-Methylisoborneol
Appl. Sci. 2017, 7(9), 876; doi:10.3390/app7090876
Received: 8 August 2017 / Revised: 23 August 2017 / Accepted: 25 August 2017 / Published: 26 August 2017
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Abstract
Geosmin and 2-methylisoborneol, molecules with the same odor characteristics, are mainly responsible for the smell of soil and cause odor problems worldwide in drinking water supplies. However, the effect of these odor molecules on human brain function is still unclear. The present investigation
[...] Read more.
Geosmin and 2-methylisoborneol, molecules with the same odor characteristics, are mainly responsible for the smell of soil and cause odor problems worldwide in drinking water supplies. However, the effect of these odor molecules on human brain function is still unclear. The present investigation aimed to evaluate the effect of inhalation of geosmin and 2-methylisoborneol on human electroencephalographic (EEG) activity in order to understand whether their action on brain wave activity is the same or different. A total of 20 healthy volunteers (10 women and 10 men) were selected to determine the EEG power spectrum changes. The EEG data were recorded from 32 channels according to the International 10–20 system and 25 EEG power spectrum indices were analyzed. The inhalation of geosmin and 2-methylisoborneol exhibited different EEG activity by producing changes in different EEG indicators as well as brain regions. In both genders, significant changes in EEG power spectra were observed during the inhalation of geosmin when compared with 2-methylisoborneol. Absolute waves such as beta, fast alpha, low beta, high beta, and gamma significantly decreased, particularly in the centro-parietal (Cp6) region, due to the exposure to geosmin. According to gender variation, geosmin produced significant changes in the absolute low beta and high beta waves at the Cp6 region in women. In the case of 2-methylisoborneol, a significant increase in absolute alpha and absolute fast alpha activity was observed at the F8 region in men. However, there were no significant changes in absolute waves for men and women during the inhalation of geosmin and 2-methylisoborneol. Although both components are responsible for soil smell, they exhibit significantly different EEG activity according to gender. Full article
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Open AccessArticle A Low Cost Wireless Acoustic Sensor for Ambient Assisted Living Systems
Appl. Sci. 2017, 7(9), 877; doi:10.3390/app7090877
Received: 31 July 2017 / Revised: 24 August 2017 / Accepted: 25 August 2017 / Published: 27 August 2017
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Abstract
Ambient Assisted Living (AAL) has become an attractive research topic due to growing interest in remote monitoring of older people. Development in sensor technologies and advances in wireless communications allows to remotely offer smart assistance and monitor those people at their own home,
[...] Read more.
Ambient Assisted Living (AAL) has become an attractive research topic due to growing interest in remote monitoring of older people. Development in sensor technologies and advances in wireless communications allows to remotely offer smart assistance and monitor those people at their own home, increasing their quality of life. In this context, Wireless Acoustic Sensor Networks (WASN) provide a suitable way for implementing AAL systems which can be used to infer hazardous situations via environmental sounds identification. Nevertheless, satisfying sensor solutions have not been found with the considerations of both low cost and high performance. In this paper, we report the design and implementation of a wireless acoustic sensor to be located at the edge of a WASN for recording and processing environmental sounds which can be applied to AAL systems for personal healthcare because it has the following significant advantages: low cost, small size, audio sampling and computation capabilities for audio processing. The proposed wireless acoustic sensor is able to record audio samples at least to 10 kHz sampling frequency and 12-bit resolution. Also, it is capable of doing audio signal processing without compromising the sample rate and the energy consumption by using a new microcontroller released at the last quarter of 2016. The proposed low cost wireless acoustic sensor has been verified using four randomness tests for doing statistical analysis and a classification system of the recorded sounds based on audio fingerprints. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle A Novel Approach to Extract Significant Patterns of Travel Time Intervals of Vehicles from Freeway Gantry Timestamp Sequences
Appl. Sci. 2017, 7(9), 878; doi:10.3390/app7090878
Received: 8 August 2017 / Revised: 12 August 2017 / Accepted: 14 August 2017 / Published: 28 August 2017
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Abstract
It is attractive to extract and determine the key features of traffic patterns for mitigating road congestion and predicting travel time of vehicles in traffic analysis. Based on the previous work that is a scalable approach via a Hadoop MapReduce programming model, this
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It is attractive to extract and determine the key features of traffic patterns for mitigating road congestion and predicting travel time of vehicles in traffic analysis. Based on the previous work that is a scalable approach via a Hadoop MapReduce programming model, this paper aims to extract significant patterns of travel time intervals of vehicles from freeway traffic in Taiwan, and meanwhile to compute the statistics of these patterns from the point of view one may concern. Experimental resources are the records of timestamp gantry sequences of vehicles passed in five months from 2016/11 to 2017/3 that were downloaded from the Traffic Data Collection System, one of Taiwan government open data platforms. To select one specific gantry sequence for demonstration, the longest sequence on the trip within the Taiwan National Freeway No. 5 is selected. Experimental results show that some statistics of vehicle travel time intervals according to 24 h per day are computed for illustration. These statistics can not only provide clues to experts to analyze traffic congestions, but also help drivers how to avoid rush hours. Furthermore, this work is able to handle a larger amount of real data and be promising for further traffic and transportation research in the future. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)
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Open AccessArticle Degradation of Trace Organic Contaminants by a Membrane Distillation—Enzymatic Bioreactor
Appl. Sci. 2017, 7(9), 879; doi:10.3390/app7090879
Received: 31 July 2017 / Revised: 24 August 2017 / Accepted: 25 August 2017 / Published: 28 August 2017
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Abstract
A high retention enzymatic bioreactor was developed by coupling membrane distillation with an enzymatic bioreactor (MD-EMBR) to investigate the degradation of 13 phenolic and 17 non-phenolic trace organic contaminants (TrOCs). TrOCs were effectively retained (90–99%) by the MD membrane. Furthermore, significant laccase-catalyzed degradation
[...] Read more.
A high retention enzymatic bioreactor was developed by coupling membrane distillation with an enzymatic bioreactor (MD-EMBR) to investigate the degradation of 13 phenolic and 17 non-phenolic trace organic contaminants (TrOCs). TrOCs were effectively retained (90–99%) by the MD membrane. Furthermore, significant laccase-catalyzed degradation (80–99%) was achieved for 10 phenolic and 3 non-phenolic TrOCs that contain strong electron donating functional groups. For the remaining TrOCs, enzymatic degradation ranged from 40 to 65%. This is still higher than those reported for enzymatic bioreactors equipped with ultrafiltration membranes, which retained laccase but not the TrOCs. Addition of three redox-mediators, namely syringaldehyde (SA), violuric acid (VA) and 1-hydroxybenzotriazole (HBT), in the MD-EMBR significantly broadened the spectrum of efficiently degraded TrOCs. Among the tested redox-mediators, VA (0.5 mM) was the most efficient and versatile mediator for enhanced TrOC degradation. The final effluent (i.e., membrane permeate) toxicity was below the detection limit, although there was a mediator-specific increase in toxicity of the bioreactor media. Full article
(This article belongs to the Special Issue Wastewater Treatment and Reuse Technologies)
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Open AccessArticle Simulation of Underwater Explosions Initiated by High-Pressure Gas Bubbles of Various Initial Shapes
Appl. Sci. 2017, 7(9), 880; doi:10.3390/app7090880
Received: 26 June 2017 / Revised: 19 August 2017 / Accepted: 22 August 2017 / Published: 28 August 2017
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Abstract
UNDerwater EXplosions (UNDEXs) are widely used in many areas of applied engineering including oil production and warship protection. However, the three-dimensional computations of UNDEXs, especially for explosives with complex initial shapes are still lacking, which is mainly due to the difficulty in capturing
[...] Read more.
UNDerwater EXplosions (UNDEXs) are widely used in many areas of applied engineering including oil production and warship protection. However, the three-dimensional computations of UNDEXs, especially for explosives with complex initial shapes are still lacking, which is mainly due to the difficulty in capturing the multi-medium interface with high pressure ratio. In this study, we conducted a series of three-dimensional numerical simulations of UNDEXs with different initial shapes of a high-pressure gas bubble surrounded with water, to investigate the dynamics of the explosion caused by the shape change of the gas bubble. The movement of the interface was traced with the level-set method, and the conditions at the gas–water interface were treated using the Real Ghost Fluid Method (RGFM). As a result, the temporal evolution of the pressure field during the explosion and the pressure exerted at the boundaries of the computational domain in each simulation scenario were obtained. It was found that an initial shock wave is generated by the explosion and transmitted in the water, leading to an increase of the pressure and density. Meanwhile, inside the gas bubble, a rarefaction wave is formed, causing a pressure drop of the explosive gas. The results also show that if the initial shape of the bubble filled with the explosive gas is simple (e.g., spherical, cylindrical, cuboidal), the peak pressure of the shock wave is dominated by the cross-sectional area of the initial bubble along each direction. In addition, the duration of the high pressure phase of the shock wave is dictated by the thickness of the bubble. Moreover, the simulation of a bubble with an initially bullet-like shape revealed that this specific shape enables a concentration of the energy in a well-defined direction. The peak of the pressure generated by the gas bubble of this more complex shape is approximately twice than that of the other scenarios. However, the high pressure was found to drop more rapidly than that of the other cases, which might be attributed to the comparably small thickness of the initial bubble. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Design of 1-Bit Digital Reconfigurable Reflective Metasurface for Beam-Scanning
Appl. Sci. 2017, 7(9), 882; doi:10.3390/app7090882
Received: 1 August 2017 / Revised: 24 August 2017 / Accepted: 25 August 2017 / Published: 28 August 2017
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Abstract
A 1-bit digital reconfigurable reflective metasurface (RRM) with 20 × 20 cells is presented, fabricated and measured for beam-scanning performance in this paper. The cell is designed with a single layer structure and one varactor diode, controlled electronically. The cell’s phase compensation is
[...] Read more.
A 1-bit digital reconfigurable reflective metasurface (RRM) with 20 × 20 cells is presented, fabricated and measured for beam-scanning performance in this paper. The cell is designed with a single layer structure and one varactor diode, controlled electronically. The cell’s phase compensation is over 180° between 3 GHz and 4 GHz and the two states with 180° phase difference are selected as coding “0” and coding “1”. By the fuzzy quantification theory, all the elements on the RRM are set to be coding “0” or coding “1” according to the phase compensation calculated by MATLAB. Furthermore, by changing the coding of the RRM, it can achieve beam-scanning. The simulation results show that the beam-scanning range is over ±60°. The RRM prototype is fabricated and experimentally tested for principle. The gain of the RRM is 18 dB and the 3 dB bandwidth is about 16.6%. The 1-bit digital RRM is preferred in practical implementations due to less error and much easier bias voltage control. The proposed RRM successfully balances the performance and system complexity, especially in the large-scale antenna designs. The experimental and simulated results are in good agreement to prove the correctness and feasibility of the design of the 1-bit digital RRM. Full article
(This article belongs to the Special Issue Metasurfaces: Physics and Applications)
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Open AccessArticle Real-time Monitoring for Disk Laser Welding Based on Feature Selection and SVM
Appl. Sci. 2017, 7(9), 884; doi:10.3390/app7090884
Received: 26 July 2017 / Revised: 25 August 2017 / Accepted: 25 August 2017 / Published: 28 August 2017
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Abstract
In order to automatically evaluate the welding quality during high-power disk laser welding, a real-time monitoring system was developed. The images of laser-induced metal vapor during welding were captured and fifteen features were extracted. A feature selection method based on a sequential forward
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In order to automatically evaluate the welding quality during high-power disk laser welding, a real-time monitoring system was developed. The images of laser-induced metal vapor during welding were captured and fifteen features were extracted. A feature selection method based on a sequential forward floating selection algorithm was employed to identify the optimal feature subset, and a support vector machine (SVM) classifier was built to recognize the welding quality. The experiment results demonstrated that this method had satisfactory performance, and could be applied in laser welding monitoring applications. Full article
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Open AccessArticle Reduction of Bias and Light Instability of Mixed Oxide Thin-Film Transistors
Appl. Sci. 2017, 7(9), 885; doi:10.3390/app7090885
Received: 31 July 2017 / Revised: 14 August 2017 / Accepted: 25 August 2017 / Published: 29 August 2017
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Abstract
Despite their potential use as pixel-switching elements in displays, the bias and light instability of mixed oxide semiconductor thin-film transistors (TFTs) still limit their application to commercial products. Lack of reproducible results due to the sensitivity of the mixed oxides to air exposure
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Despite their potential use as pixel-switching elements in displays, the bias and light instability of mixed oxide semiconductor thin-film transistors (TFTs) still limit their application to commercial products. Lack of reproducible results due to the sensitivity of the mixed oxides to air exposure and chemical contamination during or after fabrication hinders any progress towards the achievement of stable performance. Consequently, one finds in literature several theories and mechanisms, all justified, but most of them conflict despite being on the same subject matter. In this study, we show that under an optimized fabrication process, which involves the in situ passivation of a mixed oxide semiconductor, we can reduce the bias and light instability of the mixed-oxide semiconductor TFTs by decreasing the semiconductor thickness. We achieve a negligible threshold voltage shift under negative bias combined with light illumination stress when the mixed oxide semiconductor thickness is around three nanometers. The improvement of stability in the thin mixed-oxide semiconductor TFTs is due to a reduced number of oxygen-vacancy defects in the bulk of the semiconductor, as their total number decreases with decreasing thickness. Under the optimized fabrication process, bulk, rather than interfacial defects, thus seem to be the main source of the bias and light instability in mixed oxide TFTs. Full article
(This article belongs to the Special Issue Thin-Film Transistors)
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Open AccessArticle Road Safety Risk Evaluation Using GIS-Based Data Envelopment Analysis—Artificial Neural Networks Approach
Appl. Sci. 2017, 7(9), 886; doi:10.3390/app7090886
Received: 31 July 2017 / Revised: 20 August 2017 / Accepted: 22 August 2017 / Published: 29 August 2017
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Abstract
Identification of the most significant factors for evaluating road risk level is an important question in road safety research, predominantly for decision-making processes. However, model selection for this specific purpose is the most relevant focus in current research. In this paper, we proposed
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Identification of the most significant factors for evaluating road risk level is an important question in road safety research, predominantly for decision-making processes. However, model selection for this specific purpose is the most relevant focus in current research. In this paper, we proposed a new methodological approach for road safety risk evaluation, which is a two-stage framework consisting of data envelopment analysis (DEA) in combination with artificial neural networks (ANNs). In the first phase, the risk level of the road segments under study was calculated by applying DEA, and high-risk segments were identified. Then, the ANNs technique was adopted in the second phase, which appears to be a valuable analytical tool for risk prediction. The practical application of DEA-ANN approach within the Geographical Information System (GIS) environment will be an efficient approach for road safety risk analysis. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Stochastic and Higher-Order Effects on Exploding Pulses
Appl. Sci. 2017, 7(9), 887; doi:10.3390/app7090887
Received: 27 June 2017 / Revised: 21 July 2017 / Accepted: 22 July 2017 / Published: 30 August 2017
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Abstract
The influence of additive noise, multiplicative noise, and higher-order effects on exploding solitons in the framework of the prototype complex cubic-quintic Ginzburg-Landau equation is studied. Transitions from explosions to filling-in to the noisy spatially homogeneous finite amplitude solution, collapse (zero solution), and periodic
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The influence of additive noise, multiplicative noise, and higher-order effects on exploding solitons in the framework of the prototype complex cubic-quintic Ginzburg-Landau equation is studied. Transitions from explosions to filling-in to the noisy spatially homogeneous finite amplitude solution, collapse (zero solution), and periodic exploding dissipative solitons are reported. Full article
(This article belongs to the Special Issue Guided-Wave Optics)
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Open AccessArticle Impacts of Sample Design for Validation Data on the Accuracy of Feedforward Neural Network Classification
Appl. Sci. 2017, 7(9), 888; doi:10.3390/app7090888
Received: 20 July 2017 / Revised: 11 August 2017 / Accepted: 21 August 2017 / Published: 30 August 2017
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Abstract
Validation data are often used to evaluate the performance of a trained neural network and used in the selection of a network deemed optimal for the task at-hand. Optimality is commonly assessed with a measure, such as overall classification accuracy. The latter is
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Validation data are often used to evaluate the performance of a trained neural network and used in the selection of a network deemed optimal for the task at-hand. Optimality is commonly assessed with a measure, such as overall classification accuracy. The latter is often calculated directly from a confusion matrix showing the counts of cases in the validation set with particular labelling properties. The sample design used to form the validation set can, however, influence the estimated magnitude of the accuracy. Commonly, the validation set is formed with a stratified sample to give balanced classes, but also via random sampling, which reflects class abundance. It is suggested that if the ultimate aim is to accurately classify a dataset in which the classes do vary in abundance, a validation set formed via random, rather than stratified, sampling is preferred. This is illustrated with the classification of simulated and remotely-sensed datasets. With both datasets, statistically significant differences in the accuracy with which the data could be classified arose from the use of validation sets formed via random and stratified sampling (z = 2.7 and 1.9 for the simulated and real datasets respectively, for both p < 0.05%). The accuracy of the classifications that used a stratified sample in validation were smaller, a result of cases of an abundant class being commissioned into a rarer class. Simple means to address the issue are suggested. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessFeature PaperArticle An Investigation of Oxide Coating Synthesized on an Aluminum Alloy by Plasma Electrolytic Oxidation in Molten Salt
Appl. Sci. 2017, 7(9), 889; doi:10.3390/app7090889
Received: 9 August 2017 / Revised: 22 August 2017 / Accepted: 28 August 2017 / Published: 30 August 2017
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Abstract
Plasma electrolytic oxidation (PEO) is a surface treatment process for obtaining oxide coatings with a high performance on valve metals. PEO is mostly performed in an aqueous solution electrolyte that limits the size of treated parts due to the fact that the system
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Plasma electrolytic oxidation (PEO) is a surface treatment process for obtaining oxide coatings with a high performance on valve metals. PEO is mostly performed in an aqueous solution electrolyte that limits the size of treated parts due to the fact that the system is heated. Therefore, the coating of large surfaces cannot be synthesized in an aqueous electrolyte. In the current work, an alternative approach of PEO treatment, whereby an aluminum 1050 alloy in nitrate molten salt at a temperature of 280 °C is applied, was investigated. The microstructure, phase and chemical compositions, and micro-hardness were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and micro-hardness tests. The obtained results show that formed coating contains from two sub-layers: one is the outer sub-layer of the α-Al2O3 phase and the second is its inner sub-layer. It was found that the formed coating was free of any contaminants originating from the electrolyte and had no cracks or pores, which are usually present in coatings formed by PEO treatment in an aqueous solution electrolyte. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Characterization of Piezoelectric Microgenerator with Nanobranched ZnO Grown on a Polymer Coated Flexible Substrate
Appl. Sci. 2017, 7(9), 890; doi:10.3390/app7090890
Received: 31 July 2017 / Revised: 29 August 2017 / Accepted: 29 August 2017 / Published: 1 September 2017
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Abstract
In this paper, results from the fabrication and study of a piezoelectric microgenerator using nanobranched zinc oxide (ZnO) film grown on poly(3,4-ethylenedioxythiphene) doped with a sulfonate (PEDOT:PSS)-coated flexible substrate are presented. The aim of the study is to extract information about the electrical
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In this paper, results from the fabrication and study of a piezoelectric microgenerator using nanobranched zinc oxide (ZnO) film grown on poly(3,4-ethylenedioxythiphene) doped with a sulfonate (PEDOT:PSS)-coated flexible substrate are presented. The aim of the study is to extract information about the electrical behavior of the harvester at different frequencies, temperatures, and positions, as related to the ZnO nanostructure, as well as to examine its piezoelectric response. Radiofrequency (RF) sputtering with oxygen deficit during growth on an amorphous sublayer was used to obtain the nanobranched structure. The microdevice was studied at frequencies ranging from 1 Hz to 1 MHz for temperatures in the range of −10 °C to 40 °C, in both a non-bended position, and a radius of curvature position bended to 12 mm. It was found that non-ordered ZnO nanoformations facilitate the dipoles’ motion, thus leading to low dielectric losses of 10−3, and a higher relative permittivity of εr ~15, compared with typically known values. The losses increase with one order of magnitude at bending, but still remain low. Dielectric characteristics indicate that the favorable working range of the microgenerator is within the lower frequency region, from 10 Hz to 10 kHz. The results were confirmed by the measured open circuit voltage, which reaches approximately 1 V within this range, versus 300 mV out of the range. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Precision Irrigation System (PIS) Using Sensor Network Technology Integrated with IOS/Android Application
Appl. Sci. 2017, 7(9), 891; doi:10.3390/app7090891
Received: 18 July 2017 / Revised: 22 August 2017 / Accepted: 25 August 2017 / Published: 1 September 2017
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Abstract
One of the most important factors for successful agricultural production is the irrigation system in place. In this study, a precision irrigation system, which takes advantage of the various phases of plant growth, was developed and implemented using the sensor network technology integrated
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One of the most important factors for successful agricultural production is the irrigation system in place. In this study, a precision irrigation system, which takes advantage of the various phases of plant growth, was developed and implemented using the sensor network technology integrated with IOS/Android. The amount of water in the soil was measured via sensors that were placed on certain points of the area to be irrigated. These sensors were placed near the root of the product. Data from sensors was transmitted via Wi-Fi in real-time to a mobile phone based on IOS/Android. In the light of obtained data, the seasonal precision irrigation system was created depending on the amount of water required by the plants at each stage of their growth stage. The required energy of the system was provided by solar energy. The system can be controlled by smart phones, which increases the usability of the system. When design performance was analyzed, it was observed that some important advantages such as obtaining high efficiency with water, time and energy saving and reducing the workforce were ensured. Five separate laterals were used for the irrigation system. There were valves on each lateral, which realized the opening and closing process depending on the water need. A total of 16 humidity sensors were used in the irrigation system and the data from these sensors was transferred to the IOS/Android server via the programmable controller (PLC). The basic electrical equipment in the irrigation system was monitored and controlled via mobile devices. Control parameters were obtained by comparing the real values and reference values by a closed-loop system and determine the new working status of the irrigation system. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Temporally Programmable Hybrid MOPA Laser with Arbitrary Pulse Shape and Frequency Doubling
Appl. Sci. 2017, 7(9), 892; doi:10.3390/app7090892
Received: 6 August 2017 / Revised: 24 August 2017 / Accepted: 28 August 2017 / Published: 1 September 2017
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Abstract
An arbitrary pulse shape by compensating gain saturation in a solid-state Master oscillator power amplifier (MOPA) system made up of three Neodymium doped yttrium vanadate (Nd:YVO4) amplifiers is demonstrated. By investigating the amplifier dynamics in detail, car-shaped pulse shapes were obtained
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An arbitrary pulse shape by compensating gain saturation in a solid-state Master oscillator power amplifier (MOPA) system made up of three Neodymium doped yttrium vanadate (Nd:YVO4) amplifiers is demonstrated. By investigating the amplifier dynamics in detail, car-shaped pulse shapes were obtained with compensated pulse distortion. Desired pulse shapes, such as multiple-step, square, parabolic, and Gaussian pulses, were achieved, with a high peak power level of 41.6 kW and a narrow linewidth less than 0.06 nm. In addition, through second harmonic generation (SHG), a green laser with different pulse shapes was obtained, with a maximum conversion efficiency of 42.6%. Full article
(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)
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Open AccessFeature PaperArticle Experimental Study on Robustness of an Eddy Current-Tuned Mass Damper
Appl. Sci. 2017, 7(9), 895; doi:10.3390/app7090895
Received: 3 August 2017 / Revised: 25 August 2017 / Accepted: 28 August 2017 / Published: 1 September 2017
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Abstract
In this paper, an eddy current tuned mass damper (ECTMD) is utilized to control the vibration of a cantilever beam. The robustness of the ECTMD against frequency detuning is experimentally studied in cases of both free vibration and forced vibration. The natural frequency
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In this paper, an eddy current tuned mass damper (ECTMD) is utilized to control the vibration of a cantilever beam. The robustness of the ECTMD against frequency detuning is experimentally studied in cases of both free vibration and forced vibration. The natural frequency of the cantilever beam can be adjusted by changing the location of a lumped mass. For purposes of comparison with the ECTMD, the robustness of a tuned mass damper (TMD) is also studied. The experimental results in the free vibration case indicate that the ECTMD works well both in tuned and detuned situations, and the equivalent damping ratio of the cantilever beam equipped with the ECTMD is 2.08~5.91 times that of the TMD. However, the TMD only suppresses the free vibration effectively in the tuned situation. With forced vibration, the experimental results also demonstrate the robustness of the ECTMD in vibration suppression in detuned cases. On the other hand, the cantilever beam with TMD experiences 1.63~2.99 times the peak vibration of that of the ECTMD control. Full article
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Open AccessArticle Properties of Aged GFRP Reinforcement Grids Related to Fatigue Life and Alkaline Environment
Appl. Sci. 2017, 7(9), 897; doi:10.3390/app7090897
Received: 31 July 2017 / Revised: 21 August 2017 / Accepted: 30 August 2017 / Published: 1 September 2017
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Abstract
In recent years, even if Fiber Reinforced Polymer (FRP) composites have been widely used for strengthening of civil buildings, a new generation of materials has been studied and proposed for historical masonry construction. These buildings, mainly made of stone work, are common in
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In recent years, even if Fiber Reinforced Polymer (FRP) composites have been widely used for strengthening of civil buildings, a new generation of materials has been studied and proposed for historical masonry construction. These buildings, mainly made of stone work, are common in many areas of Europe and Asia and recent earthquakes has been the cause of many catastrophic failures. The brittleness of unreinforced historic masonry can be considerably reduced using new retrofitting lighter-weight materials such FRP, even if limitations were evidenced due to material and mechanical compatibility with poor substrates. Thus, fibrous reinforcements were used as long fibres incorporated into a cement or lime matrix, which better match with the properties of ancient masonry. The use of low strength fibers such as glass and basalt, respect to carbon, in presence of an alkaline matrix brought out durability issues, due to the chemical vulnerability of common glass and basalt fibres. The objective of this research is to explore the effects of selected aqueous environments and fatigue loading on the mechanical and physical properties of composite grids, made of E-CR (Electrical/Chemical Resistance) glass fibers and epoxy-vinylester resin, used as tensile reinforcement in new composite reinforced mortar systems. Glass-fiber-reinforced polymer (GFRP) coupons were subjected to tensile testing and a severe protocol of durability tests, including alkaline environment and fatigue tensile loads. Accelerated ageing tests were used to simulate long-term degradation in terms of chemical attack and consequent reduction of tensile strength. The ageing protocol consisted of immersion at 40 °C in alkaline bath made by deionized water and Ca(OH)2, 0.16% in weight, solution for 30 days. GFRP specimens aged and unaged were also tested under tensile fatigue cycles up to 1,000,000 cycles and a nominal frequency of 7.5 Hz. After this severe conditioning the tests indicate a good tensile strength retention of the GFRP in absence of fatigue loads, while a significant loss in fatigue life was experienced when both alkaline exposure and fatigue loads were applied. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Comparative Study of Two Dynamics-Model-Based Estimation Algorithms for Distributed Drive Electric Vehicles
Appl. Sci. 2017, 7(9), 898; doi:10.3390/app7090898
Received: 21 July 2017 / Revised: 24 August 2017 / Accepted: 29 August 2017 / Published: 1 September 2017
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Abstract
The effect of vehicle active safety systems is subject to the accurate knowledge of vehicle states. Therefore, it is of great importance to develop a precise and robust estimation approach so as to deal with nonlinear vehicle dynamics systems. In this paper, a
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The effect of vehicle active safety systems is subject to the accurate knowledge of vehicle states. Therefore, it is of great importance to develop a precise and robust estimation approach so as to deal with nonlinear vehicle dynamics systems. In this paper, a planar vehicle model with a simplified tire model is established first. Two advanced model-based estimation algorithms, an unscented Kalman filter and a moving horizon estimation, are developed for distributed drive electric vehicles. Using the proposed algorithms, vehicle longitudinal velocity, lateral velocity, yaw rate as well as lateral tire forces are estimated based on information fusion of standard sensors in today’s typical vehicle and feedback signals from electric motors. Computer simulations are implemented in the environment of CarSim combined with Matlab/Simulink. The performance of both estimators regarding convergence, accuracy, and robustness against an incorrect initial estimate of longitudinal velocity is compared in detail. The comparison results demonstrate that both estimation approaches have favourable coincidence with the corresponding reference values, while the moving horizon estimation is more accurate and robust, and owns faster convergence. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessFeature PaperArticle A Dispersive Inelastic X-ray Scattering Spectrometer for Use at X-ray Free Electron Lasers
Appl. Sci. 2017, 7(9), 899; doi:10.3390/app7090899
Received: 14 July 2017 / Revised: 25 August 2017 / Accepted: 26 August 2017 / Published: 1 September 2017
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Abstract
We report on the application of a short working distance von Hamos geometry spectrometer to measure the inelastic X-ray scattering (IXS) signals from solids and liquids. In contrast to typical IXS instruments where the spectrometer geometry is fixed and the incoming beam energy
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We report on the application of a short working distance von Hamos geometry spectrometer to measure the inelastic X-ray scattering (IXS) signals from solids and liquids. In contrast to typical IXS instruments where the spectrometer geometry is fixed and the incoming beam energy is scanned, the von Hamos geometry allows measurements to be made using a fixed optical arrangement with no moving parts. Thanks to the shot-to-shot capability of the spectrometer setup, we anticipate its application for the IXS technique at X-ray free electron lasers (XFELs). We discuss the capability of the spectrometer setup for IXS studies in terms of efficiency and required total incident photon flux for a given signal-to-noise ratio. The ultimate energy resolution of the spectrometer, which is a key parameter for IXS studies, was measured to the level of 150 meV at short crystal radius thanks to the application of segmented crystals for X-ray diffraction. The short working distance is a key parameter for spectrometer efficiency that is necessary to measure weak IXS signals. Full article
(This article belongs to the Special Issue X-Ray Free-Electron Laser)
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Open AccessArticle Distinguishing Different Cancerous Human Cells by Raman Spectroscopy Based on Discriminant Analysis Methods
Appl. Sci. 2017, 7(9), 900; doi:10.3390/app7090900
Received: 20 July 2017 / Revised: 30 August 2017 / Accepted: 30 August 2017 / Published: 1 September 2017
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Abstract
An approach to distinguish eight kinds of different human cells by Raman spectroscopy was proposed and demonstrated in this paper. Original spectra of suspension cells in the frequency range of 623~1783 cm−1 were acquired and pre-processed by baseline calibration, and principal component
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An approach to distinguish eight kinds of different human cells by Raman spectroscopy was proposed and demonstrated in this paper. Original spectra of suspension cells in the frequency range of 623~1783 cm−1 were acquired and pre-processed by baseline calibration, and principal component analysis (PCA) was employed to extract the useful spectral information. To develop a robust discrimination model, a linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA) were attempted comparatively in the work. The results showed that the QDA model is better than the LDA model. The optimal QDA model was generated with 12 principal components. The classification rates are 100% in the calibration and prediction set, respectively. From the experimental results, it is concluded that Raman spectroscopy combined with appropriate discriminant analysis methods has significant potential in human cell detection. Full article
(This article belongs to the Special Issue Optics and Spectroscopy for Fluid Characterization)
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Open AccessArticle A Two-Stage Approach to Note-Level Transcription of a Specific Piano
Appl. Sci. 2017, 7(9), 901; doi:10.3390/app7090901
Received: 22 July 2017 / Revised: 25 August 2017 / Accepted: 29 August 2017 / Published: 2 September 2017
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Abstract
This paper presents a two-stage transcription framework for a specific piano, which combines deep learning and spectrogram factorization techniques. In the first stage, two convolutional neural networks (CNNs) are adopted to recognize the notes of the piano preliminarily, and note verification for the
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This paper presents a two-stage transcription framework for a specific piano, which combines deep learning and spectrogram factorization techniques. In the first stage, two convolutional neural networks (CNNs) are adopted to recognize the notes of the piano preliminarily, and note verification for the specific individual is conducted in the second stage. The note recognition stage is independent of piano individual, in which one CNN is used to detect onsets and another is used to estimate the probabilities of pitches at each detected onset. Hence, candidate pitches at candidate onsets are obtained in the first stage. During the note verification, templates for the specific piano are generated to model the attack of note per pitch. Then, the spectrogram of the segment around candidate onset is factorized using attack templates of candidate pitches. In this way, not only the pitches are picked up by note activations, but the onsets are revised. Experiments show that CNN outperforms other types of neural networks in both onset detection and pitch estimation, and the combination of two CNNs yields better performance than a single CNN in note recognition. We also observe that note verification further improves the performance of transcription. In the transcription of a specific piano, the proposed system achieves 82% on note-wise F-measure, which outperforms the state-of-the-art. Full article
(This article belongs to the Special Issue Sound and Music Computing)
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Open AccessArticle Fabrication and Characterizations of Hot-Melt Extruded Nanocomposites Based on Zinc Sulfate Monohydrate and Soluplus
Appl. Sci. 2017, 7(9), 902; doi:10.3390/app7090902
Received: 20 July 2017 / Revised: 30 August 2017 / Accepted: 1 September 2017 / Published: 4 September 2017
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Abstract
Zinc sulfate monohydrate (ZnSO4)-loaded nanocomposites (NCs) were fabricated by using a hot-melt extruder (HME) system. Soluplus (SP) was adopted as an amphiphilic polymer matrix for HME processing. The micro-size of ZnSO4 dispersion was reduced to nano-size by HME processing with
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Zinc sulfate monohydrate (ZnSO4)-loaded nanocomposites (NCs) were fabricated by using a hot-melt extruder (HME) system. Soluplus (SP) was adopted as an amphiphilic polymer matrix for HME processing. The micro-size of ZnSO4 dispersion was reduced to nano-size by HME processing with the use of SP. ZnSO4 could be homogeneously dispersed in SP through HME processing. ZnSO4/SP NCs with a 75 nm mean diameter, a 0.1 polydispersity index, and a −1 mV zeta potential value were prepared. The physicochemical properties of ZnSO4/SP NCs and the existence of SP in ZnSO4/SP NCs were further investigated by solid-state studies. Nano-size range of ZnSO4/SP NC dispersion was maintained in the simulated gastrointestinal environments (pH 1.2 and 6.8 media). No severe toxicity in intestinal epithelium after oral administration of ZnSO4/SP NCs (at 100 mg/kg dose of ZnSO4, single dosing) was observed in rats. These results imply that developed ZnSO4/SP NC can be used as a promising nano-sized zinc supplement formulation. In addition, developed HME technology can be widely applied to fabricate nanoformulations of inorganic materials. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle Collision Avoidance from Multiple Passive Agents with Partially Predictable Behavior
Appl. Sci. 2017, 7(9), 903; doi:10.3390/app7090903
Received: 14 July 2017 / Revised: 21 August 2017 / Accepted: 30 August 2017 / Published: 4 September 2017
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Abstract
Navigating a robot in a dynamic environment is a challenging task, especially when the behavior of other agents such as pedestrians, is only partially predictable. Also, the kinodynamic constraints on robot motion add an extra challenge. This paper proposes a novel navigational strategy
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Navigating a robot in a dynamic environment is a challenging task, especially when the behavior of other agents such as pedestrians, is only partially predictable. Also, the kinodynamic constraints on robot motion add an extra challenge. This paper proposes a novel navigational strategy for collision avoidance of a kinodynamically constrained robot from multiple moving passive agents with partially predictable behavior. Specifically, this paper presents a new approach to identify the set of control inputs to the robot, named control obstacle, which leads it towards a collision with a passive agent moving along an arbitrary path. The proposed method is developed by generalizing the concept of nonlinear velocity obstacle (NLVO), which is used to avoid collision with a passive agent, and takes into account the kinodynamic constraints on robot motion. Further, it formulates the navigational problem as an optimization problem, which allows the robot to make a safe decision in the presence of various sources of unmodelled uncertainties. Finally, the performance of the algorithm is evaluated for different parameters and is compared to existing velocity obstacle-based approaches. The simulated experiments show the excellent performance of the proposed approach in term of computation time and success rate. Full article
(This article belongs to the Special Issue Multi-Agent Systems)
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Open AccessArticle Effects of Using Different Sources of Remote Sensing and Geographic Information System Data on Urban Stormwater 2D–1D Modeling
Appl. Sci. 2017, 7(9), 904; doi:10.3390/app7090904
Received: 29 July 2017 / Revised: 29 August 2017 / Accepted: 31 August 2017 / Published: 5 September 2017
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Abstract
Remote sensing (RS) and geographic information system (GIS) data is increasingly used in urban stormwater modeling. The undirected use of such data may waste economic and human resources. In order to provide guidance for practitioners to efficiently use different data collection resources, as
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Remote sensing (RS) and geographic information system (GIS) data is increasingly used in urban stormwater modeling. The undirected use of such data may waste economic and human resources. In order to provide guidance for practitioners to efficiently use different data collection resources, as well as give a reference for future works, this paper aims to assess the effects of using free access GIS data and ad hoc RS data on urban 2D–1D stormwater modeling. The 2D-surface Two-dimensional Runoff, Erosion, and Export model (TREX) model was published in Science of the Total Environment in 2008. The 1D-sewer CANOE (Logiciel intégré de conception et de diagnostic des réseaux d’assainissement) model was published in Journal of Hydrology in 2004. The two models are integrated in the TRENOE (TREX-CANOE) platform. The modeling approach is applied to a small urban catchment near Paris (Le Perreux sur Marne, 0.12 km2). Simulation results reveal that the detailed land-use information derived from multiple data sources is a crucial factor for accurate simulations. Nevertheless, using the very high resolution LiDAR (light detection and ranging) data is not equally significant for the water flow simulations at sewage outlets. Finally, we suggest that using the free access GIS data accompanying the urban sewer network design might be an acceptable low-cost solution for accurate urban 2D–1D stormwater modeling during moderate rainfall events. Further studies of urban stormwater modeling could focus on the development of “suitable” models with “enough” input data, depending on the management/research objectives. Full article
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Open AccessArticle Analysis of MTF in TDI-CCD Subpixel Dynamic Super-Resolution Imaging by Beam Splitter
Appl. Sci. 2017, 7(9), 905; doi:10.3390/app7090905
Received: 14 July 2017 / Revised: 22 August 2017 / Accepted: 30 August 2017 / Published: 5 September 2017
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Abstract
The subpixel dynamic imaging technique of a beam splitter is one of the most effective super-resolution imaging methods. Aiming to create a linear time delay integration charge coupled device (TDI–CCD) subpixel imaging system based on the optical assembly method, its modulation transfer function
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The subpixel dynamic imaging technique of a beam splitter is one of the most effective super-resolution imaging methods. Aiming to create a linear time delay integration charge coupled device (TDI–CCD) subpixel imaging system based on the optical assembly method, its modulation transfer function (MTF) is analyzed based on the spatial over-sampling theory. Firstly, Fourier transformation of the sampling point is used to describe the frequency domain characteristics of TDI–CCD, which transform a unit cell of the spatial sampling lattice into a bandwidth cell in the spatial–frequency domain. Considering the effects of velocity mismatch and misalignment, the best subpixel staggering position of the linear TDI–CCD pair is given. Moreover, according to the analysis of the MTF of super-resolution reconstruction results from multiple subpixel images with random spatial offsets, the condition of sampling in the limitation of the enhancement of MTF is obtained. The numerical simulation and real experimental analysis reveal results that are consistent with the theoretical model. Full article
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Open AccessArticle LiDARgrammetry: A New Method for Generating Synthetic Stereoscopic Products from Digital Elevation Models
Appl. Sci. 2017, 7(9), 906; doi:10.3390/app7090906
Received: 16 May 2017 / Revised: 10 August 2017 / Accepted: 4 September 2017 / Published: 12 September 2017
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Abstract
There are currently several new technologies being used to generate digital elevation models that do not use photogrammetric techniques. For example, LiDAR (Laser Imaging Detection and Ranging) and RADAR (RAdio Detection And Ranging) can generate 3D points and reflectivity information of the surface
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There are currently several new technologies being used to generate digital elevation models that do not use photogrammetric techniques. For example, LiDAR (Laser Imaging Detection and Ranging) and RADAR (RAdio Detection And Ranging) can generate 3D points and reflectivity information of the surface without using a photogrammetric approach. In the case of LiDAR, the intensity level indicates the amount of energy that the object reflects after a laser pulse is transmitted. This energy mainly depends on the material and the wavelength used by LiDAR. This intensity level can be used to generate a synthetic image colored by this attribute (intensity level), which can be viewed as a RGB (red, green and blue) picture. This work presents the outline of an innovative method, designed by the authors, to generate synthetic pictures from point clouds to use in classical photogrammetric software (digital restitution or stereoscopic vision). This is conducted using available additional information (for example, the intensity level of LiDAR). This allows mapping operators to view the LiDAR as if it were stereo-imagery, so they can manually digitize points, 3D lines, break lines, polygons and so on. Full article
(This article belongs to the Special Issue Laser Scanning)
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Open AccessArticle Inverse Optimal Design for Position Control of a Quadrotor
Appl. Sci. 2017, 7(9), 907; doi:10.3390/app7090907
Received: 18 June 2017 / Revised: 11 August 2017 / Accepted: 26 August 2017 / Published: 5 September 2017
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Abstract
In this paper, we propose an inverse optimal design method for the position control of a quadrotor. First, we derive the dynamics of a quadrotor using the Newton-Euler formulation. Second, we present the state transformation technique to derive the position dynamics from the
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In this paper, we propose an inverse optimal design method for the position control of a quadrotor. First, we derive the dynamics of a quadrotor using the Newton-Euler formulation. Second, we present the state transformation technique to derive the position dynamics from the kinematic and dynamic models of a quadrotor. Then, we present the nonlinear inverse optimal position control of a quadrotor. The stability analysis based on Lyapunov theorem shows that the proposed control method can realize a quadrotor system that is exponentially stabilized. In addition, we show the inverse optimality of the proposed inverse optimal controller for the position control of a quadrotor. The inverse optimality can simply and clearly be shown using the state transformation technique. Finally, we present some simulation results to verify the effectiveness of the proposed control method. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessFeature PaperArticle Estimation of the Performance Improvement of Pre-Amplified PAM4 Systems When Using Multi-Section Semiconductor Optical Amplifiers
Appl. Sci. 2017, 7(9), 908; doi:10.3390/app7090908
Received: 1 August 2017 / Revised: 29 August 2017 / Accepted: 31 August 2017 / Published: 5 September 2017
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Abstract
Multi-section semiconductor optical amplifiers (SOA) have been shown to have superior noise and linearity performance compared with single section SOAs. We show how to create a simplified numerical model for multi-section SOAs that is suitable for optical communication system simulations and use that
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Multi-section semiconductor optical amplifiers (SOA) have been shown to have superior noise and linearity performance compared with single section SOAs. We show how to create a simplified numerical model for multi-section SOAs that is suitable for optical communication system simulations and use that model to investigate the amplification performance of 56 Gbit/s four-level pulse amplitude modulation signals. We find that a multi-section SOA could provide an improvement in input power dynamic range exceeding 3 dB compared to a single section SOA that has the same unsaturated gain. Full article
(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)
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Open AccessArticle Properties of Extrusion Concrete Panel Using Waste Concrete Powder
Appl. Sci. 2017, 7(9), 910; doi:10.3390/app7090910
Received: 30 July 2017 / Revised: 25 August 2017 / Accepted: 31 August 2017 / Published: 5 September 2017
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Abstract
There has been an increasing amount of waste concrete generated in recent years, which has made recycling more important. Waste concrete is generally recycled as recycled aggregates, and many studies have been conducted to seek ways to improve their quality. Such quality improvement
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There has been an increasing amount of waste concrete generated in recent years, which has made recycling more important. Waste concrete is generally recycled as recycled aggregates, and many studies have been conducted to seek ways to improve their quality. Such quality improvement processes has led to the generation of byproducts such as waste concrete powder, which needs to be recycled efficiently based on further research. Accordingly, this study was conducted with the aim to use waste concrete powder (WCP) to substitute silica powder in the manufacturing of the extrusion concrete panels in cases where high SiO2 content is not a requirement. The results of this study showed a negative correlation between flexural strength and silica powder-WCP substitution ratio. For example, 50% substitution resulted in a product that satisfied the required flexural strength over 14 MPa as stipulated by the Korean Industrials Standards, and it gave rise to properties such as specific gravity, absorption ratio, length change, thermal conductivity, and fire-resistance that were similar to those of plain specimens. Based on these results, it was deemed that it would be possible to use WCP as an alternative material in place of siliceous fillers in cases where high-purity is not required. Full article
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Open AccessArticle The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems
Appl. Sci. 2017, 7(9), 911; doi:10.3390/app7090911
Received: 19 July 2017 / Revised: 11 August 2017 / Accepted: 26 August 2017 / Published: 5 September 2017
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Abstract
In practice, it is usually difficult to obtain the physical model of nonlinear, rotor-bearing systems due to uncertain nonlinearities. In order to solve this issue to conduct the analysis and design of nonlinear, rotor-bearing systems, in this study, a data driven NARX (Nonlinear
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In practice, it is usually difficult to obtain the physical model of nonlinear, rotor-bearing systems due to uncertain nonlinearities. In order to solve this issue to conduct the analysis and design of nonlinear, rotor-bearing systems, in this study, a data driven NARX (Nonlinear Auto-Regressive with exogenous inputs) model is identified. Due to the lack of the random input signal which is required in the identification of a system′s NARX model, for nonlinear, rotor-bearing systems, a new multi-harmonic input based model identification approach is introduced. Moreover, the identification results of NARX models on the nonlinear, rotor-bearing systems are validated under different conditions (such as: low speed, critical speed, and over critical speed), illustrating the applicability of the proposed approach. Finally, an experimental test is conducted to identify the NARX model of the nonlinear rotor test rig, showing that the NARX model can be used to reproduce the characteristics of the underlying system accurately, which provides a reliable model for dynamic analysis, control, and fault diagnosis of the nonlinear, rotor-bearing system. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessFeature PaperArticle Habitat Potential Mapping of Marten (Martes flavigula) and Leopard Cat (Prionailurus bengalensis) in South Korea Using Artificial Neural Network Machine Learning
Appl. Sci. 2017, 7(9), 912; doi:10.3390/app7090912
Received: 15 July 2017 / Revised: 18 August 2017 / Accepted: 31 August 2017 / Published: 5 September 2017
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Abstract
This study developed habitat potential maps for the marten (Martes flavigula) and leopard cat (Prionailurus bengalensis) in South Korea. Both species are registered on the Red List of the International Union for Conservation of Nature, which means that they
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This study developed habitat potential maps for the marten (Martes flavigula) and leopard cat (Prionailurus bengalensis) in South Korea. Both species are registered on the Red List of the International Union for Conservation of Nature, which means that they need to be managed properly. Various factors influencing the habitat distributions of the marten and leopard were identified to create habitat potential maps, including elevation, slope, timber type and age, land cover, and distances from a forest stand, road, or drainage. A spatial database for each species was constructed by preprocessing Geographic Information System (GIS) data, and the spatial relationship between the distribution of leopard cats and environmental factors was analyzed using an artificial neural network (ANN) model. This process used half of the existing habitat location data for the marten and leopard cat for training. Habitat potential maps were then created considering the relationships. Using the remaining half of the habitat location data for each species, the model was validated. The results of the model were relatively successful, predicting approximately 85% for the marten and approximately 87% for the leopard cat. Therefore, the habitat potential maps can be used for monitoring the habitats of both species and managing these habitats effectively. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets
Appl. Sci. 2017, 7(9), 913; doi:10.3390/app7090913
Received: 16 August 2017 / Revised: 30 August 2017 / Accepted: 4 September 2017 / Published: 6 September 2017
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Abstract
Laser drilling and laser engraving are common manufacturing processes that are found in many applications. With the continuous progress of additive manufacturing (3D printing), these processes can now be applied to the materials used in 3D printing. However, there is a lack of
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Laser drilling and laser engraving are common manufacturing processes that are found in many applications. With the continuous progress of additive manufacturing (3D printing), these processes can now be applied to the materials used in 3D printing. However, there is a lack of knowledge about how these new materials behave when processed or machined. In this study, sheets of 316L stainless steel produced by both the traditional cold rolling method and by powder bed fusion (PBF) were laser drilled by a nanosecond pulsed fiber laser. Results were then analyzed to find out whether there are measurable differences in laser processing parts that are produced by either PBF (3D printing) or traditional steel parts. Hole diameters, the widths of burn effects, material removal rates, and hole tapers were measured and compared. Additionally, differences in microstructures of the samples were also analyzed and compared. Results show negligible differences in terms of material processing efficiency. The only significant differences were that the PBF sample had a wider burn effect, and had some defects in the microstructure that were more closely analyzed. The defects were found to be shallow recesses in the material. Some of the defects were deep within the material, at the end and start points of the laser lines, and some were close to the surfaces of the sample. Full article
(This article belongs to the Special Issue 3D Printing of Metals)
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Open AccessArticle Investigation of Laser Cutting Width of LiCoO2 Coated Aluminum for Lithium-Ion Batteries
Appl. Sci. 2017, 7(9), 914; doi:10.3390/app7090914
Received: 25 July 2017 / Revised: 30 August 2017 / Accepted: 31 August 2017 / Published: 6 September 2017
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Abstract
Lithium-ion batteries are widely used for many applications such as portable electronic devices and Electric Vehicles, because they have lighter weight, higher energy density, higher power density, and a higher energy-to-weight ratio than other types of batteries. Conventional contact-based cutting technology may be
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Lithium-ion batteries are widely used for many applications such as portable electronic devices and Electric Vehicles, because they have lighter weight, higher energy density, higher power density, and a higher energy-to-weight ratio than other types of batteries. Conventional contact-based cutting technology may be inefficient whenever cell design is changed since lithium-ion battery cells are not standardized. Furthermore, the conventional cutting may result in process instability and a poor cut quality due to the tool wear so that it leads to short circuits and local heat generation. These process instability and inefficiency may be solved by laser cutting due to advantages such as clean cutting edge, less deformation, applicability to almost all materials, possibility of precision processing, and easy modification of cutting path. Despite the importance of the laser cutting research, no clear definition of cutting widths has been presented, and there is lack of knowledge to understand the effect of laser parameters on cutting widths. Therefore, this research examines the surface of cathode cut by a laser and defines cutting widths such as top width, melting width, and kerf width. The relationship between the laser parameters and cutting characteristics with defined widths are studied. When the volume energy is less than 6.0172 × 10 10 J / m 3 , no active electrode material is removed. When the laser power is greater or equal to 100 W, both the top and melting widths are clearly observed. The laser power of 50 W can selectively ablate the active electrode material with the material removal rate of 32.14–55.71 mm 3 / min . The threshold volume energy to fully penetrate the 50 μm-thick current collector is between 9.6275 × 10 10 8.0229 × 10 10 J / m 3 . All clearance width is less than 20 μm, while the clearance width interestingly exceeds 20 μm when the laser power is 200 W. The effect of material properties on heat transfer using the one dimensional transient semi-infinite conduction model is investigated. In addition, five types of physical characteristics are defined and discussed. Full article
(This article belongs to the Special Issue Electrode Materials for Lithium-ion Batteries/Super-capacitors)
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Open AccessArticle Ion-Mediated Aggregation of Gold Nanoparticles for Light-Induced Heating
Appl. Sci. 2017, 7(9), 916; doi:10.3390/app7090916
Received: 5 August 2017 / Revised: 1 September 2017 / Accepted: 4 September 2017 / Published: 7 September 2017
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Abstract
Photothermal therapy is proposed as a straightforward manner of killing cancer cells, which a plasmon field of gold nanoparticles is activated by incoming light resonance leading to a local increase of temperature. This photothermal effect is strongly dependent on the plasmonic features of
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Photothermal therapy is proposed as a straightforward manner of killing cancer cells, which a plasmon field of gold nanoparticles is activated by incoming light resonance leading to a local increase of temperature. This photothermal effect is strongly dependent on the plasmonic features of the nanoparticles. Herein, we study the effect of the ion-mediated aggregation of citrate-capped small spherical gold nanoparticles on the plasmonic band and the photothermal performance. An intermediate value of ionic strength has been found to be optimum with respect to the photothermal capabilities of the gold nanoparticles. Full article
(This article belongs to the Special Issue Laser Interaction with Plasmonic Nanostructures)
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Open AccessArticle Simulation of Tail Boom Vibrations Using Main Rotor-Fuselage Computational Fluid Dynamics (CFD)
Appl. Sci. 2017, 7(9), 918; doi:10.3390/app7090918
Received: 25 July 2017 / Revised: 29 August 2017 / Accepted: 1 September 2017 / Published: 7 September 2017
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Abstract
In this work, fully-resolved rotor-fuselage interactional aerodynamics is used as the forcing term in a model based on the Euler-Bernoulli equation, aiming to simulate helicopter tail-boom vibration. The model is based on linear beam analysis and captures the effect of the blade-passing as
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In this work, fully-resolved rotor-fuselage interactional aerodynamics is used as the forcing term in a model based on the Euler-Bernoulli equation, aiming to simulate helicopter tail-boom vibration. The model is based on linear beam analysis and captures the effect of the blade-passing as well as the effect of the changing force direction on the boom. The Computational Fluid Dynamics (CFD) results were obtained using a well-validated helicopter simulation tool. Results for the tail-boom vibration are not validated due to lack of experimental data, but were obtained using an established analytical approach and serve to demonstrate the strong effect of aerodynamics on tail-boom aeroelastic behavior. Full article
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Open AccessArticle Flow Characteristics of Steam and Gas Push in the Presence of Heat Thief Zones Overlying Oil Sands Deposits
Appl. Sci. 2017, 7(9), 919; doi:10.3390/app7090919
Received: 19 July 2017 / Revised: 24 August 2017 / Accepted: 6 September 2017 / Published: 7 September 2017
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Abstract
This paper presents the effects of the top water-bearing zone on the performance of the steam and gas push, i.e., nitrogen as a non-condensable gas injected with steam into an oil sands deposit. The flow characteristics of fluid mixtures are examined in the
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This paper presents the effects of the top water-bearing zone on the performance of the steam and gas push, i.e., nitrogen as a non-condensable gas injected with steam into an oil sands deposit. The flow characteristics of fluid mixtures are examined in the presence of different-sized water-bearing formations overlying oil sands deposits, i.e., a finite aquifer with no-flow boundaries and an infinite aquifer with continuous mass flux. The performance efficiency is investigated by respectively implementing the cumulative steam to oil ratio, a simple thermal efficiency parameter, and the oil production on the surface. The top water-bearing area serves as a heat thief zone and negatively impacts bitumen recovery; furthermore, it increases the cumulative steam to oil ratio while decreasing the simple thermal efficiency parameter, as well as the oil production rate. When the steam chamber encounters the top aquifer, a severe heat loss occurs. As increasing mol % of nitrogen, the producing time with energy efficiency increases but the chamber growth is limited. The specific operational conditions would be possible for the finite-sized aquifer, while the continuous water influx and the significant heat loss obstructs the thermal processes for the infinite aquifer. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Enhancement of Energy Harvesting Performance by a Coupled Bluff Splitter Body and PVEH Plate through Vortex Induced Vibration near Resonance
Appl. Sci. 2017, 7(9), 921; doi:10.3390/app7090921
Received: 21 June 2017 / Revised: 30 August 2017 / Accepted: 4 September 2017 / Published: 7 September 2017
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Abstract
Inspired by vortex induced vibration energy harvesting development as a new source of renewable energy, a T-shaped design vibration energy harvester is introduced with the aim of enhancing its performance through vortex induced vibration at near resonance conditions. The T-shaped structural model designed
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Inspired by vortex induced vibration energy harvesting development as a new source of renewable energy, a T-shaped design vibration energy harvester is introduced with the aim of enhancing its performance through vortex induced vibration at near resonance conditions. The T-shaped structural model designed consists of a fixed boundary aluminum bluff splitter body coupled with a cantilever piezoelectric vibration energy harvesters (PVEH) plate model which is a piezoelectric bimorph plate made of a brass plate sandwiched between 2 lead zirconate titanate (PZT) plates. A 3-dimensional Fluid-Structure Interaction simulation analysis is carried out with Reynolds Stress Turbulence Model under wind speed of 7, 10, 12, 14, 16, 18, 19, 20, 22.5, and 25 m/s. The results showed that with 19 m/s wind speed, the model generates 75.758 Hz of vortex frequency near to the structural model’s natural frequency of 76.9 Hz. Resonance lock-in therefore occurred, generating a maximum displacement amplitude of 2.09 mm or a 49.76% increment relatively in vibrational amplitude. Under the effect of resonance at the PVEH plate’s fundamental natural frequency, it is able to generate the largest normalized power of 13.44 mW/cm3g2. Full article
(This article belongs to the Section Energy)
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Open AccessArticle Real-Time Transportation Mode Identification Using Artificial Neural Networks Enhanced with Mode Availability Layers: A Case Study in Dubai
Appl. Sci. 2017, 7(9), 923; doi:10.3390/app7090923
Received: 30 July 2017 / Revised: 31 August 2017 / Accepted: 6 September 2017 / Published: 8 September 2017
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Abstract
Traditionally, departments of transportation (DOTs) have dispatched probe vehicles with dedicated vehicles and drivers for monitoring traffic conditions. Emerging assisted GPS (AGPS) and accelerometer-equipped smartphones offer new sources of raw data that arise from voluntarily-traveling smartphone users provided that their modes of transportation
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Traditionally, departments of transportation (DOTs) have dispatched probe vehicles with dedicated vehicles and drivers for monitoring traffic conditions. Emerging assisted GPS (AGPS) and accelerometer-equipped smartphones offer new sources of raw data that arise from voluntarily-traveling smartphone users provided that their modes of transportation can correctly be identified. By introducing additional raster map layers that indicate the availability of each mode, it is possible to enhance the accuracy of mode detection results. Even in its simplest form, an artificial neural network (ANN) excels at pattern recognition with a relatively short processing timeframe once it is properly trained, which is suitable for real-time mode identification purposes. Dubai is one of the major cities in the Middle East and offers unique environments, such as a high density of extremely high-rise buildings that may introduce multi-path errors with GPS signals. This paper develops real-time mode identification ANNs enhanced with proposed mode availability geographic information system (GIS) layers, firstly for a universal mode detection and, secondly for an auto mode detection for the particular intelligent transportation system (ITS) application of traffic monitoring, and compares the results with existing approaches. It is found that ANN-based real-time mode identification, enhanced by mode availability GIS layers, significantly outperforms the existing methods. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessCommunication Low-Cost Nanocarbon-Based Peroxidases from Graphite and Carbon Fibers
Appl. Sci. 2017, 7(9), 924; doi:10.3390/app7090924
Received: 7 August 2017 / Revised: 5 September 2017 / Accepted: 6 September 2017 / Published: 8 September 2017
PDF Full-text (3421 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A low-cost and facile preparation of water-soluble carbon nanomaterials from commercial available graphite and polypropylene carbon fibers was achieved. N-doped graphene quantum dot was also prepared as a comparable agent. The resultant carbon nanomaterials were characterized by vital techniques such as transmission
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A low-cost and facile preparation of water-soluble carbon nanomaterials from commercial available graphite and polypropylene carbon fibers was achieved. N-doped graphene quantum dot was also prepared as a comparable agent. The resultant carbon nanomaterials were characterized by vital techniques such as transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, Fourier transform infrared (FT-IR) and Raman spectra. The prepared carbon nanomaterials can make hydrogen peroxide degradation produce hydroxyl radicals, thus possess intrinsic peroxidase-like activity for colorimetric and UV-vis absorption detection of hydrogen peroxide. These carbon nanomaterials exhibit excellent sensitivity toward hydrogen peroxide with the limit of detection as low as 0.024 mM (by Carbon nanomaterials-1 from carbon fibers), 0.0042 mM (by Carbon nanomaterials-2 from graphite) and 0.014 mM (by Carbon nanomaterials-3 from nitrogen doped graphene oxide), respectively. The practical use of these carbon nanomaterials for phenolic compounds removal in aqueous solution is also demonstrated successfully. The extraordinary catalytic performance and low cost of these carbon nanomaterials make them a powerful tool for a wide range of potential applications. Full article
(This article belongs to the Special Issue Graphene and Graphene Oxide in Biomedical Application)
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Open AccessArticle An Event Reporting and Early-Warning Safety System Based on the Internet of Things for Underground Coal Mines: A Case Study
Appl. Sci. 2017, 7(9), 925; doi:10.3390/app7090925
Received: 3 August 2017 / Revised: 1 September 2017 / Accepted: 5 September 2017 / Published: 8 September 2017
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Abstract
Fatal accidents associated with underground coal mines require the implementation of high-level gas monitoring and miner’s localization approaches to promote underground safety and health. This study introduces a real-time monitoring, event-reporting and early-warning platform, based on cluster analysis for outlier detection, spatiotemporal statistical
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Fatal accidents associated with underground coal mines require the implementation of high-level gas monitoring and miner’s localization approaches to promote underground safety and health. This study introduces a real-time monitoring, event-reporting and early-warning platform, based on cluster analysis for outlier detection, spatiotemporal statistical analysis, and an RSS range-based weighted centroid localization algorithm for improving safety management and preventing accidents in underground coal mines. The proposed platform seamlessly integrates monitoring, analyzing, and localization approaches using the Internet of Things (IoT), cloud computing, a real-time operational database, application gateways, and application program interfaces. The prototype has been validated and verified at the operating underground Hassan Kishore coal mine. Sensors for air quality parameters including temperature, humidity, CH4, CO2, and CO demonstrated an excellent performance, with regression constants always greater than 0.97 for each parameter when compared to their commercial equivalent. This framework enables real-time monitoring, identification of abnormal events (>90%), and verification of a miner’s localization (with <1.8 m of error) in the harsh environment of underground mines. The main contribution of this study is the development of an open source, customizable, and cost-effective platform for effectively promoting underground coal mine safety. This system is helpful for solving the problems of accessibility, serviceability, interoperability, and flexibility associated with safety in coal mines. Full article
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Open AccessArticle Detecting Anatomical Leg Length Discrepancy Using the Plug-in-Gait Model
Appl. Sci. 2017, 7(9), 926; doi:10.3390/app7090926
Received: 12 August 2017 / Revised: 4 September 2017 / Accepted: 4 September 2017 / Published: 8 September 2017
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Abstract
Leg length discrepancy (LLD) is a significant factor influencing several pathological conditions. Gait analysis is based on biomechanical gait models calculating joint kinematics; however, no previous study has validated its ability to detect anatomical LLD. The aim of the present study was to
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Leg length discrepancy (LLD) is a significant factor influencing several pathological conditions. Gait analysis is based on biomechanical gait models calculating joint kinematics; however, no previous study has validated its ability to detect anatomical LLD. The aim of the present study was to compare the validity of the Vicon® Plug-in-Gait-model (PGM) in measuring femur and tibia segmental length discrepancy with measurements attained by X-ray. Fifteen participants with suspected leg length discrepancies underwent a lower limb X-ray and a standing calibration trial using a motion analysis system (Vicon®, Oxford Metrics, UK). Femur and tibia segment lengths were deducted from both measurements. No differences were found when measuring the discrepancies between sides for the femur (p = 0.3) and tibia (p = 0.45) segmental length. A high correlation was found between methods (r = 0.808–0.962, p < 0.001), however, a significant difference was observed when measuring the femur and tibia length (p < 0.0001). PGM was found to be a valid model in detecting segmental length discrepancy when based on the location of the joint centers compared to X-ray. A variance was noted in the femur and tibial segmental length. The impact of this inconsistency in segmental length on kinematics and kinetics should be further evaluated. Full article
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Open AccessArticle Optimal Control and Operation Strategy for Wind Turbines Contributing to Grid Primary Frequency Regulation
Appl. Sci. 2017, 7(9), 927; doi:10.3390/app7090927
Received: 23 June 2017 / Revised: 29 August 2017 / Accepted: 5 September 2017 / Published: 8 September 2017
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Abstract
This study introduces a frequency regulation strategy to enable the participation of wind turbines with permanent magnet synchronous generators (PMSGs). The optimal strategy focuses on developing the frequency support capability of PMSGs connected to the power system. Active power control is performed using
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This study introduces a frequency regulation strategy to enable the participation of wind turbines with permanent magnet synchronous generators (PMSGs). The optimal strategy focuses on developing the frequency support capability of PMSGs connected to the power system. Active power control is performed using maximum power point tracking (MPPT) and de-loaded control to supply the required power reserve following a disturbance. A kinetic energy (KE) reserve control is developed to enhance the frequency regulation capability of wind turbines. The coordination with the de-loaded control prevents instability in the PMSG wind system due to excessive KE discharge. A KE optimization method that maximizes the sum of the KE reserves at wind farms is also adopted to determine the de-loaded power reference for each PMSG wind turbine using the particle swarm optimization (PSO) algorithm. To validate the effectiveness of the proposed optimal control and operation strategy, three different case studies are conducted using the PSCAD/EMTDC simulation tool. The results demonstrate that the optimal strategy enhances the frequency support contribution from PMSG wind turbines. Full article
(This article belongs to the Special Issue Energy Saving)
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Open AccessArticle Agent-Based Model for Automaticity Management of Traffic Flows across the Network
Appl. Sci. 2017, 7(9), 928; doi:10.3390/app7090928
Received: 1 July 2017 / Revised: 9 August 2017 / Accepted: 4 September 2017 / Published: 9 September 2017
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Abstract
This paper presents an agent-based model that performs the management of traffic flows in a network with the purpose of observing in a simulation of distinctive congestion scenarios how the automation of the monitoring task improves the network performance. The model implements a
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This paper presents an agent-based model that performs the management of traffic flows in a network with the purpose of observing in a simulation of distinctive congestion scenarios how the automation of the monitoring task improves the network performance. The model implements a decision-making algorithm to determine the path that the data flows will follow to reach their destination, according to the results of the negotiation between the agents. In addition, we explain how the behavior of the network is affected by its topology. The aim of this paper is to propose an agent-based model that simplifies the management of the traffic flows in a communications network towards the automaticity of the system. Full article
(This article belongs to the Special Issue Multi-Agent Systems)
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Open AccessArticle Air Entrainment and Air Demand in the Spillway Tunnel at the Jinping-I Dam
Appl. Sci. 2017, 7(9), 930; doi:10.3390/app7090930
Received: 3 August 2017 / Revised: 31 August 2017 / Accepted: 7 September 2017 / Published: 10 September 2017
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Abstract
Artificial air entrainment has been widely used to avoid cavitation damage in spillways where high-velocity flow occurs, and its performance is very important for spillway safety. In order to evaluate the performance of the aeration system in the spillway tunnel of the Jinping-I
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Artificial air entrainment has been widely used to avoid cavitation damage in spillways where high-velocity flow occurs, and its performance is very important for spillway safety. In order to evaluate the performance of the aeration system in the spillway tunnel of the Jinping-I Dam, which is the highest arched dam in the world to date, systematic prototype observation was conducted. Ventilation characteristics of the air supply system and aeration-related characteristics of the aeration devices were examined at the prototype scale. The results showed that air flows smoothly in the air intake well and the real effect of air entrainment of the aeration device was desirable. In contrast with results from laboratory tests with a physical model at a scale of 1/30 following the gravity similarity, it was found that air demand in the prototype is much greater, clearly indicating the scale effect. By summing up and analyzing the air demand ratio of the prototype to the model in some projects, the scale effect was found to be ignorable when the model scale was greater than 1/10. In addition, based on a series of prototype data on air demand, a brief evaluation of present calculation methods for air demand was conducted and a new form of calculation method for air demand related to unit width flow rate was established. The present prototype results can be used as a reference for similar engineering design, and to validate and verify numerical simulations as well as model tests. Full article
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Open AccessArticle Changes in Pore Structure of Coal Associated with Sc-CO2 Extraction during CO2-ECBM
Appl. Sci. 2017, 7(9), 931; doi:10.3390/app7090931
Received: 21 August 2017 / Revised: 5 September 2017 / Accepted: 7 September 2017 / Published: 10 September 2017
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Abstract
Supercritical CO2 (Sc-CO2), a supercritical solvent, can extract small organic molecules (fluid) from coal, changing pore structures to affect gases storage and migration in the coal matrix. Five undeformed coals before and after the second coalification jump were collected to
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Supercritical CO2 (Sc-CO2), a supercritical solvent, can extract small organic molecules (fluid) from coal, changing pore structures to affect gases storage and migration in the coal matrix. Five undeformed coals before and after the second coalification jump were collected to simulate Sc-CO2 extraction performed with supercritical extraction equipment. Pore structures of the samples before and after Sc-CO2 extraction were characterized using mercury porosimetry. The results show that there are significant changes in pore size distribution of samples. ΔVMa and ΔVMe of coal samples are positive, ΔVTr and ΔVMi are positive for most coals, and ΔVMi of higher coals are negative; the ΔSMa and ΔSMe are positive with small values, the ΔSTr and ΔSMi are positive and negative before and after the second coalification jump; thus, the pore connectivity is improved. These results indicate that Sc-CO2 extraction not only increases the numbers of micropores, but also enlarges the pore diameter size; these changes in the pore structure are influenced by the second coalification. The changes in the pore structure by Sc-CO2 extraction provide more spaces for gas storage and may improve the pore throats for gas migration. Full article
(This article belongs to the Special Issue The Applications of Supercritical Carbon Dioxide)
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Open AccessArticle Frequency Modulation and Erosion Performance of a Self-Resonating Jet
Appl. Sci. 2017, 7(9), 932; doi:10.3390/app7090932
Received: 7 August 2017 / Revised: 7 September 2017 / Accepted: 7 September 2017 / Published: 10 September 2017
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Abstract
The self-resonating water jet offers the advantages of both a cavitation jet and a pulsed jet, and thus has been widely used for many practical applications. In the present study, the 120° -impinging edge Helmholtz nozzle was investigated for better erosion performance. The
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The self-resonating water jet offers the advantages of both a cavitation jet and a pulsed jet, and thus has been widely used for many practical applications. In the present study, the 120° -impinging edge Helmholtz nozzle was investigated for better erosion performance. The oscillating mechanism was analyzed from both numerical and experimental perspectives. The results showed that the cavitation clouds in the chamber dominate the oscillating frequency. The frequency resulting from the non-linear interaction was also observed in the simulation. The dominant frequency increases linearly as pressure decreases without entrained air. The frequency modulation was achieved through various inspiratory methods, and the modulation range was dependent on the pressure drop. The erosion performance was improved with entrained air, and the improvement was effected by the inspiratory method. The oscillating frequency was determined by the forced frequency of entrained air, and the best erosion performance was achieved at the frequency closest to the fundamental frequency. A feasible method to improve the erosion performance was investigated in this preliminary study, which could provide a guide for practical applications. Full article
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Open AccessArticle Measurement Matrix Analysis and Radiation Improvement of a Metamaterial Aperture Antenna for Coherent Computational Imaging
Appl. Sci. 2017, 7(9), 933; doi:10.3390/app7090933
Received: 26 July 2017 / Revised: 18 August 2017 / Accepted: 7 September 2017 / Published: 12 September 2017
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Abstract
A metamaterial aperture antenna (MAA) that generates frequency-diverse radiation field patterns has been introduced in the context of microwave wave imaging to perform compressive image reconstruction. This paper presents a new metamateriapl aperture design, which includes two kinds of metamaterial elements with random
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A metamaterial aperture antenna (MAA) that generates frequency-diverse radiation field patterns has been introduced in the context of microwave wave imaging to perform compressive image reconstruction. This paper presents a new metamateriapl aperture design, which includes two kinds of metamaterial elements with random distribution. One is a high-Q resonant element whose resonant frequency is agile, and the other one is a low-Q element that has a high radiation efficiency across frequency band. Numerical simulations and measurements show that the radiation efficiency of up to 60% can be achieved for the MAA and the far-field patterns owns good orthogonality, when using the complementary electric-field-coupled (CELC) element and the complementary Jerusalem cross (CJC) element with a random distribution ratio of 4 to 1, which could be effectively used to reconstruct the target scattering scene. Full article
(This article belongs to the Special Issue Metasurfaces: Physics and Applications)
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Open AccessArticle Experimental Study on Milling CFRP with Staggered PCD Cutter
Appl. Sci. 2017, 7(9), 934; doi:10.3390/app7090934
Received: 31 July 2017 / Revised: 31 August 2017 / Accepted: 7 September 2017 / Published: 11 September 2017
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Abstract
Carbon fiber reinforced plastics (CFRP) have good physical properties, such as high specific strength and high specific modulus. However, cutting delamination, tearing and burr, etc. often occur in the machining process of CFRP, which results in the uncontrollability of machining surface quality and
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Carbon fiber reinforced plastics (CFRP) have good physical properties, such as high specific strength and high specific modulus. However, cutting delamination, tearing and burr, etc. often occur in the machining process of CFRP, which results in the uncontrollability of machining surface quality and serious tool wear. In this paper, milling of CFRP with a staggered cutter was carried out, the cutting-edge radius was investigated in order to characterize the tool wear; the effect of the cutting-edge wear radius on the milling force and surface quality was found, and the formation mechanisms of the 3D surface topography and surface defects were analyzed under the wear state. Experimental results showed that the wear of the staggered PCD cutter was mainly concentrated in the cutting-edge area. With the increase in milling length, the radius of cutting edge gradually became largeer under the action of abrasive wear mechanism, and the flank wear was not obvious. With the intension of tool wear, milling force gradually increased and the machining surface quality of the CFRP deteriorated distinctly, i.e., defects such as bare fiber fracture, groove and hole appeared, and burrs were gradually generated on the workpiece surface. Finally, through a comparative analysis of cutting performance, it was found that the staggered PCD cutter possessed better performance for wear resistance and burr suppression than the straight-teeth cutter. This finding can provide theoretical and technical support for improving the machining quality of carbon fiber composite materials. Full article
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Open AccessArticle Analysis of the Pyroclastic Flow Deposits of Mount Sinabung and Merapi Using Landsat Imagery and the Artificial Neural Networks Approach
Appl. Sci. 2017, 7(9), 935; doi:10.3390/app7090935
Received: 25 July 2017 / Revised: 7 September 2017 / Accepted: 8 September 2017 / Published: 11 September 2017
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Abstract
Volcanic eruptions cause pyroclastic flows, which can destroy plantations and settlements. We used image data from Landsat 7 Bands 7, 4 and 2 and Landsat 8 Bands 7, 5 and 3 to observe and analyze the distribution of pyroclastic flow deposits for two
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Volcanic eruptions cause pyroclastic flows, which can destroy plantations and settlements. We used image data from Landsat 7 Bands 7, 4 and 2 and Landsat 8 Bands 7, 5 and 3 to observe and analyze the distribution of pyroclastic flow deposits for two volcanos, Mount Sinabung and Merapi, over a period of 10 years (2001–2017). The satellite data are used in conjunction with an artificial neural network method to produce maps of pyroclastic precipitation for Landsat 7 and 8, then we calculated the pyroclastic precipitation area using an artificial neural network method after dividing the images into four classes based on color. Red, green, blue and yellow were used to indicate pyroclastic deposits, vegetation and forest, water and cloud, and farmland, respectively. The area affected by a volcanic eruption was deduced from the neural network processing, including calculating the area of pyroclastic deposits. The main differences between the pyroclastic flow deposits of Mount Sinabung and Mount Merapi are: the sediment deposits of the pyroclastic flows of Mount Sinabung tend to widen, whereas those of Merapi elongated; the direction of pyroclastic flow differed; and the area affected by an eruption was greater for Mount Merapi than Mount Sinabung because the VEI (Volcanic Explosivity Index) during the last 10 years of Mount Merapi was larger than Mount Sinabung. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Localization in Low Power Wide Area Networks Using Wi-Fi Fingerprints
Appl. Sci. 2017, 7(9), 936; doi:10.3390/app7090936
Received: 13 July 2017 / Revised: 2 September 2017 / Accepted: 7 September 2017 / Published: 12 September 2017
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Abstract
Supply chain management requires regular updates of the location of assets, which can be enabled by low power wide area networks, such as Sigfox. While it is useful to localize a device simply by its communication signals, this is very difficult to do
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Supply chain management requires regular updates of the location of assets, which can be enabled by low power wide area networks, such as Sigfox. While it is useful to localize a device simply by its communication signals, this is very difficult to do with Sigfox because of wide area and ultra narrowband nature. On the other hand, installing a satellite localization element on the device greatly increases its power consumption. We investigated using information about nearby Wi-Fi access points as a way to localize the asset over the Sigfox network, so without connecting to those Wi-Fi networks. This paper reports the location error that can be achieved by this type of outdoor localization. By using a combination of two databases, we could localize the device on all 36 test locations with a median location error of 39 m . This shows that the localization accuracy of this method is promising enough to warrant further study, most specifically the minimal power consumption. Full article
(This article belongs to the Special Issue Advanced Internet of Things for Smart Infrastructure System)
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Open AccessArticle Weak Fault Feature Extraction Scheme for Intershaft Bearings Based on Linear Prediction and Order Tracking in the Rotation Speed Difference Domain
Appl. Sci. 2017, 7(9), 937; doi:10.3390/app7090937
Received: 7 August 2017 / Revised: 10 September 2017 / Accepted: 10 September 2017 / Published: 12 September 2017
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Abstract
Because both the inner and outer rings rotate, the intershaft bearings used in gas turbines do not have fixed bearing housings. As a result, the vibration of intershaft bearings cannot be measured directly. Therefore, a vibration signal can only be collected through indirect
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Because both the inner and outer rings rotate, the intershaft bearings used in gas turbines do not have fixed bearing housings. As a result, the vibration of intershaft bearings cannot be measured directly. Therefore, a vibration signal can only be collected through indirect measurement. First, it must be transferred to adjacent bearings through the shafting. Then, it should be transferred by the elastic supports and complex structure of the thin-walled strut. The vibration signal is severely weakened during transmission under the influences of the transfer path. In the meantime, in the vibration of other components, a huge amount of noise is produced by the air flow, and the variable speeds of the inner and outer rings of the intershaft bearings make it harder to analyze the signal. Hence, it is very difficult to extract the vibration fault features of intershaft bearings. To deal with the variable speed of dual rotors, as well as the weak signal, a fault feature extraction scheme for the weak fault signals of intershaft bearings is proposed in this paper. This scheme is based on linear prediction, spectral kurtosis, and order tracking in the rotation speed difference domain. First, a prewhitening process, based on linear prediction, is applied to the fault signal of the intershaft bearings to eliminate the stationary component. Thus, the remaining components, including the impulse signal of faulty bearings and nonstationary noise, can retain the features of the vibrational bearings, in addition to reducing the noise. Second, the optimal center frequency and bandwidth of the band-pass filter, applied to resonant demodulation, are selected by spectral kurtosis. Subsequently, the enveloped signal containing the features of the faults found in the intershaft bearings is obtained by resonance demodulation. The quasi-stationary signal in the angle domain is acquired by the even angle resampling of the nonstationary envelope signal, as a result of the variable speed. The final order spectrum is obtained through a Fourier transform. Fault diagnosis can be conducted for the intershaft bearings by comparing this spectrum with the feature order of the bearing fault. Experiments were conducted to verify the validity of the proposed scheme. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Ultralow Friction of ZrO2 Ball Sliding against DLC Films under Various Environments
Appl. Sci. 2017, 7(9), 938; doi:10.3390/app7090938
Received: 14 August 2017 / Revised: 4 September 2017 / Accepted: 5 September 2017 / Published: 12 September 2017
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Abstract
Ultralow friction is achieved by ZrO2 as the friction mate material for DLC (Diamond like carbon) films under various environments. Coefficient of friction (CoF) of ZrO2/DLC films is as ultra low as 0.02 in ambient air at the temperature of
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Ultralow friction is achieved by ZrO2 as the friction mate material for DLC (Diamond like carbon) films under various environments. Coefficient of friction (CoF) of ZrO2/DLC films is as ultra low as 0.02 in ambient air at the temperature of 200 °C, and 0.03, 0.04 and 0.05 in hydrogen, nitrogen and vacuum environments at the temperature of 100 °C, respectively. It is concluded that the transferred films are formed on the worn surface of ZrO2 ball and amorphous carbon films. Ultralow friction of the friction pair is related with hydrogen, which is derived from DLC films, hydrogen environment or the liberation hydrogen due to hydrothermal oxidation. The ultralow friction mechanism is attributed to the formation of hydrogenated amorphous carbon films on ZrO2 ball and the shielding action of hydrogen from DLC films and the transferred films simultaneously. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle Structure and Capacitance of Electrical Double Layers at the Graphene–Ionic Liquid Interface
Appl. Sci. 2017, 7(9), 939; doi:10.3390/app7090939
Received: 25 August 2017 / Revised: 6 September 2017 / Accepted: 6 September 2017 / Published: 12 September 2017
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Abstract
Molecular dynamics simulations are carried out to investigate the structure and capacitance of the electrical double layers (EDLs) at the interface of vertically oriented graphene and ionic liquids [EMIM]+/[BF4]. The distribution and migration of the ions in
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Molecular dynamics simulations are carried out to investigate the structure and capacitance of the electrical double layers (EDLs) at the interface of vertically oriented graphene and ionic liquids [EMIM]+/[BF4]. The distribution and migration of the ions in the EDL on the rough and non-rough electrode surfaces with different charge densities are compared and analyzed, and the effect of the electrode surface morphology on the capacitance of the EDL is clarified. The results suggest that alternate distributions of anions and cations in several consecutive layers are formed in the EDL on the electrode surface. When the electrode is charged, the layers of [BF4] anions experience more significant migration than those of [EMIM]+ cations. These ion layers can be extended deeper into the bulk electrolyte solution by the stronger interaction of the rough electrode, compared to those on the non-rough electrode surface. The potential energy valley of ions on the neutral electrode surface establishes a potential energy difference to compensate the energy cost of the ion accumulation, and is capable of producing a potential drop across the EDL on the uncharged electrode surface. Due to the greater effective contact area between the ions and electrode, the rough electrode possesses a larger capacitance than the non-rough one. In addition, it is harder for the larger-sized [EMIM]+ cations to accumulate in the narrow grooves on the rough electrode, when compared with the smaller [BF4]. Consequently, the double-hump-shaped C–V curve (which demonstrates the relationship between differential capacitance and potential drop across the EDL) for the rough electrode is asymmetric, where the capacitance increases more significantly when the electrode is positively charged. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle Competitive Evaluation of Planar Embedded Glass and Polymer Waveguides in Data Center Environments
Appl. Sci. 2017, 7(9), 940; doi:10.3390/app7090940
Received: 20 June 2017 / Revised: 31 August 2017 / Accepted: 1 September 2017 / Published: 13 September 2017
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Abstract
Optical printed circuit board (OPCB) waveguide materials and fabrication methods have advanced considerably over the past 15 years, giving rise to two classes of embedded planar graded index waveguide based on polymer and glass. We consider the performance of these two emerging waveguide
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Optical printed circuit board (OPCB) waveguide materials and fabrication methods have advanced considerably over the past 15 years, giving rise to two classes of embedded planar graded index waveguide based on polymer and glass. We consider the performance of these two emerging waveguide classes in view of the anticipated deployment in data center environments of optical transceivers based on directly modulated multimode short wavelength VCSELs against those based on longer wavelength single-mode photonic integrated circuits. We describe the fabrication of graded index polymer waveguides, using the Mosquito and photo-addressing methods, and graded index glass waveguides, using ion diffusion on thin glass foils. A comparative characterization was carried out on the waveguide classes to show a clear reciprocal dependence of the performance of different waveguide classes on wavelength. Furthermore, the different waveguide types were connected into an optically disaggregated data switch and storage system to evaluate and validate their suitability for deployment in future data center environments. Full article
(This article belongs to the Special Issue Optical Interconnects)
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Open AccessArticle A New Method for Analysing the Pressure Response Delay in a Pneumatic Brake System Caused by the Influence of Transmission Pipes
Appl. Sci. 2017, 7(9), 941; doi:10.3390/app7090941
Received: 29 July 2017 / Revised: 2 September 2017 / Accepted: 9 September 2017 / Published: 13 September 2017
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Abstract
This study aims to propose an analysis method for resolving the pressure response of a pneumatic brake circuit considering the effect of a transmission pipe. Pneumatic brake systems (PBS) are widely used in commercial vehicles. The pressure response characteristic of the PBS is
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This study aims to propose an analysis method for resolving the pressure response of a pneumatic brake circuit considering the effect of a transmission pipe. Pneumatic brake systems (PBS) are widely used in commercial vehicles. The pressure response characteristic of the PBS is the key factor affecting braking performance. By using the thermodynamics of a variable-quality system, the pressure response model of the brake chamber is established, which includes the dynamic model of the pipe considering the unsteady friction and heat transfer. The partial-differential control equations of pipe are solved by introducing the constrained interpolation profile (CIP) method, and a virtual chamber model is proposed to set the boundary condition so as to solve the pressure response in the brake chamber simultaneously. Thus, the regularity of the brake pressure response is obtained by considering the influence of the pipe. Lastly, the model is verified experimentally. The present study indicates that the main factors that affect the pressure response delay are the pipe length and the combination forms of the sonic conductances of the orifices inlet and outlet. Furthermore, it helps to verify that the CIP method is an effective way of solving the pressure response of a brake circuit because of its high accuracy. The present study serves as a foundation for the design and analysis of a PBS. Full article
(This article belongs to the Special Issue Power Transmission and Control in Power and Vehicle Machineries)
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Open AccessArticle Open Source 3-D Printed Nutating Mixer
Appl. Sci. 2017, 7(9), 942; doi:10.3390/app7090942
Received: 30 August 2017 / Revised: 11 September 2017 / Accepted: 11 September 2017 / Published: 13 September 2017
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Abstract
As the open source development of additive manufacturing has led to low-cost desktop three-dimensional (3-D) printing, a number of scientists throughout the world have begun to share digital designs of free and open source scientific hardware. Open source scientific hardware enables custom experimentation,
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As the open source development of additive manufacturing has led to low-cost desktop three-dimensional (3-D) printing, a number of scientists throughout the world have begun to share digital designs of free and open source scientific hardware. Open source scientific hardware enables custom experimentation, laboratory control, rapid upgrading, transparent maintenance, and lower costs in general. To aid in this trend, this study describes the development, design, assembly, and operation of a 3-D printable open source desktop nutating mixer, which provides a fixed 20° platform tilt angle for a gentle three-dimensional (gyrating) agitation of chemical or biological samples (e.g., DNA or blood samples) without foam formation. The custom components for the nutating mixer are designed using open source FreeCAD software to enable customization. All of the non-readily available components can be fabricated with a low-cost RepRap 3-D printer using an open source software tool chain from common thermoplastics. All of the designs are open sourced and can be configured to add more functionality to the equipment in the future. It is relatively easy to assemble and is accessible to both the science education of younger students as well as state-of-the-art research laboratories. Overall, the open source nutating mixer can be fabricated with US$37 in parts, which is 1/10th of the cost of proprietary nutating mixers with similar capabilities. The open source nature of the device allow it to be easily repaired or upgraded with digital files, as well as to accommodate custom sample sizes and mixing velocities with minimal additional costs. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Coordinated Control of the Energy Router-Based Smart Home Energy Management System
Appl. Sci. 2017, 7(9), 943; doi:10.3390/app7090943
Received: 2 August 2017 / Revised: 3 September 2017 / Accepted: 12 September 2017 / Published: 13 September 2017
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Abstract
Home area energy networks will be an essential part of the future Energy Internet in terms of energy saving, demand-side management and stability improvement of the distribution network, while an energy router will be the perfect choice to serve as an intelligent and
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Home area energy networks will be an essential part of the future Energy Internet in terms of energy saving, demand-side management and stability improvement of the distribution network, while an energy router will be the perfect choice to serve as an intelligent and multi-functional energy interface between the home area energy network and power grid. This paper elaborates on the design, analysis and implementation of coordinated control of the low-voltage energy router-based smart home energy management system (HEMS). The main contribution of this paper is to develop a novel solution to make the energy router technically feasible and practical for the HEMS to make full use of the renewable energy sources (RESs), while maintaining “operational friendly and beneficial” to the power grid. The behaviors of the energy router-based HEMS in correlation with the power grid are investigated, then the coordinated control scheme composed of a reference voltage and current compensation strategy and a fuzzy logic control-based power management strategy is developed. The system model is built on the MATLAB/Simulink platform, simulation results have demonstrated that the presented control scheme is a strong performer in making full use of the RES generations for the HEMS while maintaining the operational stability of the whole system, as well as in collaboration with the power grid to suppress the impact of RES output fluctuations and load consumption variations. Full article
(This article belongs to the Special Issue Smart Home and Energy Management Systems)
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Open AccessArticle Characterization of Surface Ozone Behavior at Different Regimes
Appl. Sci. 2017, 7(9), 944; doi:10.3390/app7090944
Received: 25 July 2017 / Revised: 31 August 2017 / Accepted: 12 September 2017 / Published: 14 September 2017
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Abstract
Previous studies showed that the influence of meteorological variables and concentrations of other air pollutants on O3 concentrations changes at different O3 concentration levels. In this study, threshold models with artificial neural networks (ANNs) were applied to characterize the O3
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Previous studies showed that the influence of meteorological variables and concentrations of other air pollutants on O3 concentrations changes at different O3 concentration levels. In this study, threshold models with artificial neural networks (ANNs) were applied to characterize the O3 behavior at an urban site (Porto, Portugal), describing the effect of environmental and meteorological variables on O3 concentrations. ANN characteristics, and the threshold variable and value, were defined by genetic algorithms (GAs). The considered predictors were hourly average concentrations of NO, NO2, and O3, and meteorological variables (temperature, relative humidity, and wind speed) measured from January 2012 to December 2013. Seven simulations were performed and the achieved models considered wind speed (at 4.9 m·s−1), temperature (at 17.5 °C) and NO2 (at 26.6 μg·m−3) as the variables that determine the change of O3 behavior. All the achieved models presented a similar fitting performance: R2 = 0.71–0.72, RMSE = 14.5–14.7 μg·m−3, and the index of agreement of the second order of 0.91. The combined effect of these variables on O3 concentration was also analyzed. This statistical model was shown to be a powerful tool for interpreting O3 behavior, which is useful for defining policy strategies for human health protection concerning this air pollutant. Full article
(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)
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Open AccessArticle Study of the Direct Metal Deposition of AA2024 by ElectroSpark for Coating and Reparation Scopes
Appl. Sci. 2017, 7(9), 945; doi:10.3390/app7090945
Received: 20 July 2017 / Revised: 15 August 2017 / Accepted: 18 August 2017 / Published: 14 September 2017
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Abstract
ElectroSpark Deposition (ESD) is a pulsed micro-welding process that is capable of depositing wear and corrosion resistance deposit to repair, improve, and to extend the service life of the components and tools. Major new applications have taken place in gas turbine blades and
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ElectroSpark Deposition (ESD) is a pulsed micro-welding process that is capable of depositing wear and corrosion resistance deposit to repair, improve, and to extend the service life of the components and tools. Major new applications have taken place in gas turbine blades and steam turbine blade protection and repair, and in military, medical, metal-working, and recreational equipment applications. In this study, the ESD technique was exploited to fabricate 2024 aluminum alloy deposit on a similar substrate. The deposits were deposited using different process parameters. Heat input was varied on three levels. The outcoming microstructure was analyzed by optical and scanning electron microscopies. The deposit was characterized by the overlapping of layers with a mixed microstructure. The average hardness was independent from the process parameters. Both porosity inside the deposits and cracks at the deposit/substrate interface were detected. The porosity lowered with the heat input and increased the average length of cracks. Full article
(This article belongs to the Section Materials)
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Open AccessArticle Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone
Appl. Sci. 2017, 7(9), 946; doi:10.3390/app7090946
Received: 28 July 2017 / Revised: 5 September 2017 / Accepted: 11 September 2017 / Published: 14 September 2017
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Abstract
Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer) is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock
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Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer) is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China. Full article
(This article belongs to the Special Issue Clean Energy and Fuel (Hydrogen) Storage)
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Open AccessArticle Model-Based Design and Evaluation of a Brachiating Monkey Robot with an Active Waist
Appl. Sci. 2017, 7(9), 947; doi:10.3390/app7090947
Received: 4 July 2017 / Revised: 19 August 2017 / Accepted: 7 September 2017 / Published: 14 September 2017
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Abstract
We report on the model-based development of a monkey robot that is capable of performing continuous brachiation locomotion on swingable rod, as the intermediate step toward studying brachiation on the soft rope or on horizontal ropes with both ends fixed. The work is
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We report on the model-based development of a monkey robot that is capable of performing continuous brachiation locomotion on swingable rod, as the intermediate step toward studying brachiation on the soft rope or on horizontal ropes with both ends fixed. The work is different from other previous works where the model or the robot swings on fixed bars. The model, which is composed of two rigid links, was inspired by the dynamic motion of primates. The model further served as the design guideline for a robot that has five degree of freedoms: two on each arm for rod changing and one on the waist to initiate a swing motion. The model was quantitatively formulated, and its dynamic behavior was analyzed in simulation. Further, a two-stage controller was developed within the simulation environment, where the first stage used the natural dynamics of a two-link pendulum-like model, and the second stage used the angular velocity feedback to regulate the waist motion. Finally, the robot was empirically built and evaluated. The experimental results confirm that the robot can perform model-like swing behavior and continuous brachiation locomotion on rods. Full article
(This article belongs to the Special Issue Bio-Inspired Robotics)
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Open AccessArticle On the Optimisation of Practical Wireless Indoor and Outdoor Microcells Subject to QoS Constraints
Appl. Sci. 2017, 7(9), 948; doi:10.3390/app7090948
Received: 24 July 2017 / Revised: 25 August 2017 / Accepted: 13 September 2017 / Published: 15 September 2017
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Abstract
Wireless indoor and outdoor microcells (WIOMs) have emerged as a promising means to deal with a high demand of mobile users for a variety of services. Over such heterogeneous networks, the deployment of WIOMs costs mobile/telecommunications company high capital expenditures and operating expenses.
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Wireless indoor and outdoor microcells (WIOMs) have emerged as a promising means to deal with a high demand of mobile users for a variety of services. Over such heterogeneous networks, the deployment of WIOMs costs mobile/telecommunications company high capital expenditures and operating expenses. This paper aims at optimising the WIOMs taking into account various network communication environments. We first develop an optimisation problem to minimise the number of cells as well as determining their optimal locations subject to the constraints of the coverage and quality-of-service (QoS) requirements. In particular, we propose a binary-search based cell positioning (BSCP) algorithm to find the optimal number of cells given a preset candidate antenna positions. The proposed BSCP algorithm is shown to not only reduce the number of cells for saving resources but also requires a low computational complexity compared to the conventional approaches with exhaustive search over all available sites. Moreover, EDX SignalPro is exploited as a simulation platform to verify the effectiveness of the proposed BSCP for the WIOMs with respect to various propagation modes and antenna parameters of different types, including isotropic, multiple-input single-output and multiple-input multiple-output. Full article
(This article belongs to the Section Computer Science and Electrical Engineering)
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Open AccessArticle Stochastic Investigation of Consolidation Process in Spatially Correlated Heterogeneous Soils
Appl. Sci. 2017, 7(9), 949; doi:10.3390/app7090949
Received: 22 August 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 15 September 2017
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Abstract
Soil consolidation as the dissipation of excess pore water pressure is mainly affected by the relative hydraulic conductivity among the layers. Geostatistical parameters such as the mean, the standard deviation, and the correlation length are physical indicators for each sedimentation and formation history.
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Soil consolidation as the dissipation of excess pore water pressure is mainly affected by the relative hydraulic conductivity among the layers. Geostatistical parameters such as the mean, the standard deviation, and the correlation length are physical indicators for each sedimentation and formation history. The effects of spatial variability on the excessive pore water pressure dissipation during consolidation process are investigated using numerical parametric studies, where multiple realizations are tested for selected hydraulic conductivity parameter using lognormal distribution. Numerical simulations show that the greater heterogeneity in hydraulic conductivity distribution applied, the longer time taken for the excess pore water pressure to dissipate, and the longer correlated variability encourages the greater variation in consolidation time. Such differences can be reduced significantly with the coupled drainage allowed by vertical drain method. Full article
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Open AccessArticle Decision Support Simulation Method for Process Improvement of Intermittent Production Systems
Appl. Sci. 2017, 7(9), 950; doi:10.3390/app7090950
Received: 20 August 2017 / Revised: 2 September 2017 / Accepted: 13 September 2017 / Published: 15 September 2017
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Abstract
Nowadays production system processes are undergoing sweeping changes. The trends include an increase in the number of product variants to be produced, as well as the reduction of the production’s lead time. These trends were induced by new devices of the industry’s 4.0,
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Nowadays production system processes are undergoing sweeping changes. The trends include an increase in the number of product variants to be produced, as well as the reduction of the production’s lead time. These trends were induced by new devices of the industry’s 4.0, namely the Internet of Things and cyber physical systems. The companies have been applying intermittent production systems (job production, batch production) because of the increase in the number of product variants. Consequently, increasing the efficiency of these systems has become especially important. The aim of development in the long term—not achievable in many cases—is the realization of unique production, with mass production’s productivity and lower cost. The improvement of complex production systems can be realized efficiently only through simulation modeling. A standardized simulation method for intermittent production systems has not been elaborated so far. In this paper, I introduce a simulation method for system improvement and present its application possibilities and a practical example. Full article
(This article belongs to the Special Issue Modeling, Simulation, Operation and Control of Discrete Event Systems)
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