Applied Sciences

13 pages, 6358 KiB

Open AccessFeature PaperArticle

SOA Based Photonic Integrated WDM Cross-Connects for Optical Metro-Access Networks

by Nicola Calabretta^*, Wang Miao, Ketemaw Mekonnen and Kristif Prifti

IPI—Institute of Photonic Integration, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands

Appl. Sci. 2017, 7(9), 865; https://doi.org/10.3390/app7090865 - 23 Aug 2017

Cited by 35 | Viewed by 7242

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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14 pages, 1474 KiB

Open AccessArticle

A Unified Approach for Reformulations of LRM/LRMM/LRRM Calibration Algorithms Based on the T-Matrix Representation

by Wei Zhao¹, Song Liu^2,†, Hai Wang³, Yan Liu^1,*, Shengkang Zhang², Chunyue Cheng², Keming Feng², Ilja Ocket⁴, Dominique Schreurs⁴

, Bart Nauwelaers⁴, Hongbo Qin¹ and Xiaodong Yang⁵

¹ Key Laboratory of Electronic Equipment Structure Design, Ministry of Education, Xidian University, Xi’an 710071, China

² Science and Technology on Metrology and Calibration Laboratory, Beijing Institute of Metrology and Measurement, Beijing 100854, China

³ School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

⁴ Department of Electrical Engineering, University of Leuven, 3000 Leuven, Belgium

⁵ School of Electronic Engineering, Xidian University, Xi’an 710071, China

^† Current address: No. 9, North Pudong Road, Zhenzhou, Yizheng 211400, China.

Appl. Sci. 2017, 7(9), 866; https://doi.org/10.3390/app7090866 - 24 Aug 2017

Cited by 6 | Viewed by 6202

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 [...] Read more.

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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10 pages, 3221 KiB

Open AccessArticle

Observer-Based Rejection of Cogging Torque Disturbance for Permanent Magnet Motors

by Kyung-Tae Nam^1,2,†, Hyungjong Kim^3,*,†, Seung-Joon Lee² and Tae-Yong Kuc⁴

¹ Department of Electronic Engineering, Sungkyunkwan Univerity, Suwon 440-746, Korea

² Korea Institute of Industrial Technology, Ansan 426-171, Korea

³ Samsung Electronics Co., Ltd., Hwaseong 18448, Korea

⁴ Department of Electronic Engineering, Sungkyunkwan Univerity, Suwon 440-746, Korea

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(9), 867; https://doi.org/10.3390/app7090867 - 25 Aug 2017

Cited by 6 | Viewed by 3899

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, [...] Read more.

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

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18 pages, 1085 KiB

Open AccessArticle

A Neural Networks Approach for Improving the Accuracy of Multi-Criteria Recommender Systems

by Mohammed Hassan^*,† and Mohamed Hamada^†

¹ Software Engineering Lab, Graduate School of Computer Science and Engineering, University of Aizu, Aizuwakamatsu-city 965-8580, Japan

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(9), 868; https://doi.org/10.3390/app7090868 - 25 Aug 2017

Cited by 57 | Viewed by 6042

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 [...] Read more.

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

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14 pages, 3657 KiB

Open AccessArticle

Assessment of Sustainability Indicators for Biodiesel Production

by Edith Martinez-Guerra^1,2 and Veera Gnaneswar Gude^1,*

¹ Department of Civil and Environmental Engineering, Mississippi State University, Starkville, MS 39759, USA

² Environmental Laboratory, Engineer Research and Development Center, Vicksburg, MS 39180, USA

Appl. Sci. 2017, 7(9), 869; https://doi.org/10.3390/app7090869 - 25 Aug 2017

Cited by 40 | Viewed by 9592

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 [...] Read more.

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 Science and Technology)

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15 pages, 3334 KiB

Open AccessArticle

Analytical Calculation of Photovoltaic Systems Maximum Power Point (MPP) Based on the Operation Point

by Javier Cubas^1,2

, Santiago Pindado^1,2,*

and Felix Sorribes-Palmer¹

¹ Instituto Universitario de Microgravedad “Ignacio Da Riva” (IDR/UPM), Universidad Politécnica de Madrid, ETSI Aeronáutica y del Espacio, Plaza del Cardenal Cisneros 3, 28040 Madrid, Spain

² Departamento de Sistemas Aeroespaciales, Transporte Aéreo y Aeropuertos (SATAA), Universidad Politécnica de Madrid, ETSI Aeronáutica y del Espacio, Plaza del Cardenal Cisneros 3, 28040 Madrid, Spain

Appl. Sci. 2017, 7(9), 870; https://doi.org/10.3390/app7090870 - 25 Aug 2017

Cited by 35 | Viewed by 4559

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 [...] Read more.

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 Science and Technology)

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9 pages, 581 KiB

Open AccessCommunication

Effect of Enzymatic Beech Fagus Sylvatica Wood Hydrolysate on Chlorella Biomass, Fatty Acid and Pigment Production

by Krystian Miazek^1,*, Claire Remacle², Aurore Richel³

and Dorothee Goffin¹

¹ TERRA, AgricultureIsLife, University of Liege-Gembloux Agro-Bio Tech, Passage des Déportés 2, B-5030 Gembloux, Belgium

² Genetics and Physiology of Microalgae, Institute of Botany, University of Liege, B22, Chemin de la vallée, B-4000 Liège, Belgium

³ Unit of Biological and Industrial Chemistry, University of Liege-Gembloux Agro-Bio Tech, Passage des Déportés 2, B-5030 Gembloux, Belgium

Appl. Sci. 2017, 7(9), 871; https://doi.org/10.3390/app7090871 - 25 Aug 2017

Cited by 1 | Viewed by 3664

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 [...] Read more.

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 Chl_Total/Car_Total 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 Chemical and Molecular Sciences)

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24 pages, 3703 KiB

Open AccessArticle

Modified Adversarial Hierarchical Task Network Planning in Real-Time Strategy Games

by Lin Sun, Peng Jiao, Kai Xu, Quanjun Yin^* and Yabing Zha

College of Information System and Management, National University of Defense Technology, Changsha 410073, China

Appl. Sci. 2017, 7(9), 872; https://doi.org/10.3390/app7090872 - 25 Aug 2017

Cited by 10 | Viewed by 5696

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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23 pages, 2927 KiB

Open AccessReview

Survey on Modelling and Techniques for Friction Estimation in Automotive Brakes

by Vincenzo Ricciardi^1,*

, Klaus Augsburg¹, Sebastian Gramstat²

, Viktor Schreiber¹ and Valentin Ivanov¹

¹ Automotive Engineering Group, Technische Universität Ilmenau, 98693 Ilmenau, Germany

² Development Foundation Brake, AUDI AG I/EF-51, 85045 Inglostadt, Germany

Appl. Sci. 2017, 7(9), 873; https://doi.org/10.3390/app7090873 - 25 Aug 2017

Cited by 31 | Viewed by 6446

Abstract

The increased use of disc brakes in passenger cars has led the research world to focus on the prediction of brake performance and wear under different working conditions. A proper model of the brake linings’ coefficient of friction (BLCF) is important to monitor [...] Read more.

The increased use of disc brakes in passenger cars has led the research world to focus on the prediction of brake performance and wear under different working conditions. A proper model of the brake linings’ coefficient of friction (BLCF) is important to monitor the brake operation and increase the performance of control systems such as ABS, TC and ESP by supplying an accurate estimate of the brake torque. The literature of the last decades is replete with semi-empirical and analytical friction models whose derivation comes from significant research that has been conducted into the direction of friction modelling of pin-disc couplings. On the contrary, just a few models have been developed and used for the prediction of the automotive BLCF without obtaining satisfactory results. The present work aims at collecting the current state of art of the estimation techniques for the BLCF, with special attention to the models for automotive brakes. Moreover, the work proposes a classification of the several existing approaches and discusses the relative pro and cons. Finally, based on evidence of the limitations of the model-based approach and the potentialities of the neural networks, the authors propose a new state observer for BLCF estimation as a promising solution among the supporting tools of the control engineering. Full article

(This article belongs to the Section Mechanical Engineering)

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18 pages, 1424 KiB

Open AccessArticle

Monitoring Sound Levels and Soundscape Quality in the Living Rooms of Nursing Homes: A Case Study in Flanders (Belgium)

by Francesco Aletta^1,*

, Dick Botteldooren¹, Pieter Thomas¹

, Tara Vander Mynsbrugge², Patricia De Vriendt^2,3,4, Dominique Van de Velde^2,3

and Paul Devos¹

¹ Department of Information Technology, Ghent University, 9052 Ghent, Belgium

² Department of Occupational Therapy, Artevelde University College, 9000 Ghent, Belgium

³ Department of Rehabilitation Sciences and Physiotherapy, Ghent University, 9000 Ghent, Belgium

⁴ Department Gerontology and Frailty in Ageing, Vrije Universiteit Brussel, 1090 Brussels, Belgium

Appl. Sci. 2017, 7(9), 874; https://doi.org/10.3390/app7090874 - 26 Aug 2017

Cited by 48 | Viewed by 6577

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 and Vibrations)

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9 pages, 425 KiB

Open AccessArticle

A Robust Asynchronous Sampled-Data Control Design for Nonlinear Systems with Actuator Failures

by Leonardo Acho^*,†

and Pablo Buenestado^†

¹ Department of Mathematics, Universitat Politècnica de Catalunya-BarcelonaTech (EEBE), 08034 Barcelona, Spain

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(9), 875; https://doi.org/10.3390/app7090875 - 26 Aug 2017

Cited by 2 | Viewed by 3327

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 [...] Read more.

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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14 pages, 1116 KiB

Open AccessArticle

Gender Differences in Electroencephalographic Activity in Response to the Earthy Odorants Geosmin and 2-Methylisoborneol

by Minju Kim¹, Kandhasamy Sowndhararajan¹, Taehee Kim², Jai Eun Kim², Jae E. Yang¹ and Songmun Kim^1,3,*

¹ School of Natural Resources and Environmental Sciences, Kangwon National University, Chuncheon 24341, Gangwon-do, Korea

² Agro-Food Research Institute, Gangwondo Agricultural Research and Extension Services, Chuncheon 24203, Gangwon-do, Korea

³ Gangwon Perfume Alchemy Ltd. Co., Chuncheon 24341, Gangwon-do, Korea

Appl. Sci. 2017, 7(9), 876; https://doi.org/10.3390/app7090876 - 26 Aug 2017

Cited by 16 | Viewed by 7714

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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15 pages, 1629 KiB

Open AccessArticle

A Low Cost Wireless Acoustic Sensor for Ambient Assisted Living Systems

by Miguel A. Quintana-Suárez^1,†, David Sánchez-Rodríguez^1,2,*,†

, Itziar Alonso-González^1,2,†

and Jesús B. Alonso-Hernández^2,3,†

¹ Telematic Engineering Department, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Spain

² Institute for Technological Development and Innovation in Communications, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Spain

³ Signal and Communications Department, University of Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Spain

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(9), 877; https://doi.org/10.3390/app7090877 - 27 Aug 2017

Cited by 23 | Viewed by 6973

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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16 pages, 24196 KiB

Open AccessArticle

A Novel Approach to Extract Significant Patterns of Travel Time Intervals of Vehicles from Freeway Gantry Timestamp Sequences

by Jing-Doo Wang^1,*,‡ and Ming-Chorng Hwang²

¹ Department of Computer Science and Information Engineering, Asia University, Taichung 41354, Taiwan

² Intelligent Transport System Research Center, China Engineering Consultants, INC., Taipei 10637, Taiwan

^‡ Department of Medical Research, China Medical University Hospital, China Medical University,

Appl. Sci. 2017, 7(9), 878; https://doi.org/10.3390/app7090878 - 28 Aug 2017

Cited by 4 | Viewed by 5484

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 [...] Read more.

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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15 pages, 1288 KiB

Open AccessArticle

Degradation of Trace Organic Contaminants by a Membrane Distillation—Enzymatic Bioreactor

by Muhammad B. Asif¹

, Faisal I. Hai^1,*, Jinguo Kang^1,2, Jason P. Van de Merwe³, Frederic D. L. Leusch³, Kazuo Yamamoto⁴, William E. Price² and Long D. Nghiem¹

¹ Strategic Water Infrastructure Lab, School of Civil, Mining and Environmental Engineering, University of Wollongong, Wollongong NSW 2522, Australia

² Strategic Water Infrastructure Lab, School of Chemistry, University of Wollongong, Wollongong NSW 2522, Australia

³ Australian Rivers Institute and Griffith School of Environment, Griffith University, Gold Coast QLD 4222, Australia

⁴ Environmental Science Centre, Department of Urban Engineering, University of Tokyo, Tokyo 113-0033, Japan

Appl. Sci. 2017, 7(9), 879; https://doi.org/10.3390/app7090879 - 28 Aug 2017

Cited by 27 | Viewed by 6411

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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22 pages, 3257 KiB

Open AccessArticle

Simulation of Underwater Explosions Initiated by High-Pressure Gas Bubbles of Various Initial Shapes

by Le Cao^1,*, Wenli Fei¹, Holger Grosshans² and Nianwen Cao¹

¹ Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China

² Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium

Appl. Sci. 2017, 7(9), 880; https://doi.org/10.3390/app7090880 - 28 Aug 2017

Cited by 15 | Viewed by 8040

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 Science and Technology)

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19 pages, 4436 KiB

Open AccessReview

Using Canola Oil Biodiesel as an Alternative Fuel in Diesel Engines: A Review

by Jun Cong Ge¹, Sam Ki Yoon^2,* and Nag Jung Choi^1,*

¹ Division of Mechanical Design Engineering, Chonbuk National University, 567 Baekje-daero, Jeonjusi 561-756, Korea

² Technical Education Center, GM Korea Company, 72 Saengmuol-ro, Gunsansi 573-882, Korea

Appl. Sci. 2017, 7(9), 881; https://doi.org/10.3390/app7090881 - 28 Aug 2017

Cited by 90 | Viewed by 22760

Abstract

Due to the rapid development of the global economy, fossil oil is widely used, leading to its depletion and gradual deterioration of the global environment, including global warming, the greenhouse effect, fog, and haze. Therefore, many researchers have been interested in studying alternative [...] Read more.

Due to the rapid development of the global economy, fossil oil is widely used, leading to its depletion and gradual deterioration of the global environment, including global warming, the greenhouse effect, fog, and haze. Therefore, many researchers have been interested in studying alternative fuels in an attempt to develop an eco-friendly fuel to replace traditional fuel and solve the above environmental problems. Biodiesel is a renewable and eco-friendly fuel that is the most promising alternative fuel for diesel engines, and a significant amount of research and development has focused on biodiesel. Canola oil biodiesel (COB) is one type of biodiesel, and it has an advantage in oil production per unit area compared with other biodiesels. This paper summarizes and reviews studies related to the use of COB in different diesel engines under a variety of operating conditions. We focus on evaluating the combustion and emission characteristics of COB based on a large number of papers (including our previous studies). In addition, this paper serves as a valuable reference for in-depth studies of COB use in diesel engines, as it covers the topic from the production of COB to its use in diesel engines. Full article

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8 pages, 2127 KiB

Open AccessArticle

Design of 1-Bit Digital Reconfigurable Reflective Metasurface for Beam-Scanning

by Shuncheng Tian

, Haixia Liu^* and Long Li^*

Key Laboratory of High Speed Circuit Design and EMC of Ministry of Education, School of Electronic Engineering, Collaborative Innovation Center of Information Sensing and Understanding, Xidian University, Xi’an 710071, China

Appl. Sci. 2017, 7(9), 882; https://doi.org/10.3390/app7090882 - 28 Aug 2017

Cited by 37 | Viewed by 7319

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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23 pages, 37269 KiB

Open AccessReview

An Overview of Additive Manufacturing of Titanium Components by Directed Energy Deposition: Microstructure and Mechanical Properties

by Abdollah Saboori^*

, Donato Gallo, Sara Biamino

, Paolo Fino

and Mariangela Lombardi

Department of Applied Science and Technology, Politecnico Di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy

Appl. Sci. 2017, 7(9), 883; https://doi.org/10.3390/app7090883 - 28 Aug 2017

Cited by 299 | Viewed by 25754

Abstract

The directed energy deposition (DED) process can be employed to build net shape components or prototypes starting from powder or wires, through a layer-by-layer process. This process provides an opportunity to fabricate complex shaped and functionally graded parts that can be utilized in [...] Read more.

The directed energy deposition (DED) process can be employed to build net shape components or prototypes starting from powder or wires, through a layer-by-layer process. This process provides an opportunity to fabricate complex shaped and functionally graded parts that can be utilized in different engineering applications. DED uses a laser as a focused heat source to melt the in-situ delivered powder or wire-shaped raw materials. In the past years extensive studies on DED have shown that this process has great potential in order to be used for (i) rapid prototyping of metallic parts, (ii) fabrication of complex and customized parts, (iii) repairing/cladding valuable components which cannot be repaired by other traditional techniques. However, the industrial adoption of this process is still challenging owing to the lack of knowledge on the mechanical performances of the constructed components and also on the trustworthiness/durability of engineering parts produced by DED. This manuscript provides an overview of the additive manufacturing (AM) of titanium alloys and focuses in particular on the mechanical properties and microstructure of components fabricated by DED. Full article

(This article belongs to the Section Materials Science and Engineering)

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11 pages, 2013 KiB

Open AccessArticle

Real-time Monitoring for Disk Laser Welding Based on Feature Selection and SVM

by Teng Wang^1,*, Juequan Chen¹, Xiangdong Gao² and Yuxin Qin³

¹ School of Computer, South China Normal University, Guangzhou 510631, China

² School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510090, China

³ College of Information Science and Engineering, Central South University, Changsha 410083, China

Appl. Sci. 2017, 7(9), 884; https://doi.org/10.3390/app7090884 - 28 Aug 2017

Cited by 20 | Viewed by 4044

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 [...] Read more.

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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14 pages, 3850 KiB

Open AccessArticle

Reduction of Bias and Light Instability of Mixed Oxide Thin-Film Transistors

by Mallory Mativenga^*, Jae Gwang Um and Jin Jang

Department of Information Display, Kung Hee University, Seoul 02447, Korea

Appl. Sci. 2017, 7(9), 885; https://doi.org/10.3390/app7090885 - 29 Aug 2017

Cited by 28 | Viewed by 10051

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 [...] Read more.

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 Transistor)

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19 pages, 23512 KiB

Open AccessArticle

Road Safety Risk Evaluation Using GIS-Based Data Envelopment Analysis—Artificial Neural Networks Approach

by Syyed Adnan Raheel Shah^1,2,*, Tom Brijs¹

, Naveed Ahmad², Ali Pirdavani⁴

, Yongjun Shen³ and Muhammad Aamir Basheer¹

¹ Transportation Research Institute (IMOB), Hasselt University, Diepenbeek 3590, Belgium

² Taxila Institute of Transportation Engineering, Department of Civil Engineering, University of Engineering & Technology, Taxila 47050, Pakistan

³ School of Transportation, Southeast University, Nanjing 210096, China

⁴ Faculty of Engineering Technology, Hasselt University, Diepenbeek 3590, Belgium

Appl. Sci. 2017, 7(9), 886; https://doi.org/10.3390/app7090886 - 29 Aug 2017

Cited by 38 | Viewed by 9496

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 [...] Read more.

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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9 pages, 1407 KiB

Open AccessArticle

Stochastic and Higher-Order Effects on Exploding Pulses

by Orazio Descalzi^* and Carlos Cartes

Complex Systems Group, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Av. Mons. Álvaro del Portillo 12.455, Las Condes, Santiago 7620001, Chile

Appl. Sci. 2017, 7(9), 887; https://doi.org/10.3390/app7090887 - 30 Aug 2017

Cited by 8 | Viewed by 3674

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 [...] Read more.

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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15 pages, 684 KiB

Open AccessArticle

Impacts of Sample Design for Validation Data on the Accuracy of Feedforward Neural Network Classification

by Giles M. Foody

School of Geography, University of Nottingham, University Park, Nottingham NG7 2RD, UK

Appl. Sci. 2017, 7(9), 888; https://doi.org/10.3390/app7090888 - 30 Aug 2017

Cited by 16 | Viewed by 5361

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 [...] Read more.

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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9 pages, 3543 KiB

Open AccessFeature PaperArticle

An Investigation of Oxide Coating Synthesized on an Aluminum Alloy by Plasma Electrolytic Oxidation in Molten Salt

by Alexander Sobolev, Alexey Kossenko, Michael Zinigrad and Konstantin Borodianskiy^*

Zimin Advanced Materials Laboratory, Department of Chemical Engineering, Biotechnology and Materials, Ariel University, Ariel 40700, Israel

Appl. Sci. 2017, 7(9), 889; https://doi.org/10.3390/app7090889 - 30 Aug 2017

Cited by 25 | Viewed by 8342

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 [...] Read more.

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 Science and Engineering)

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11 pages, 2042 KiB

Open AccessArticle

Characterization of Piezoelectric Microgenerator with Nanobranched ZnO Grown on a Polymer Coated Flexible Substrate

by Mariya Aleksandrova^1,*

, Georgi Kolev¹, Yordanka Vucheva¹, Habib Pathan²

and Krassimir Denishev¹

¹ Department of Microelectronics, Technical University of Sofia, 1000 Sofia, Bulgaria

² Department of Physics, Savitribai Phule Pune University, Pune 411007, India

Appl. Sci. 2017, 7(9), 890; https://doi.org/10.3390/app7090890 - 1 Sep 2017

Cited by 12 | Viewed by 5529

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 [...] Read more.

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 ε_r ~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 Science and Engineering)

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14 pages, 3003 KiB

Open AccessArticle

Precision Irrigation System (PIS) Using Sensor Network Technology Integrated with IOS/Android Application

by Mehmet Fatih Işık^1,*

, Yusuf Sönmez², Cemal Yılmaz³, Veysel Özdemir⁴ and Ercan Nurcan Yılmaz³

¹ Electric-Electronics Engineering, Hitit University Faculty of Engineering, Çorum 19030, Turkey

² Electrical Department, Technical Sciences Vocational College, Gazi University, Ankara 06560, Turkey

³ Department of Electrical Engineering, Technology Faculty, Gazi University, Ankara 06560, Turkey

⁴ Department of Industrial Design Engineering, Technology Faculty, Gazi University, Ankara 06560, Turkey

Appl. Sci. 2017, 7(9), 891; https://doi.org/10.3390/app7090891 - 1 Sep 2017

Cited by 35 | Viewed by 8521

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 [...] Read more.

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

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10 pages, 15425 KiB

Open AccessArticle

Temporally Programmable Hybrid MOPA Laser with Arbitrary Pulse Shape and Frequency Doubling

by Mingming Nie

, Qiang Liu^*, Encai Ji

, Xuezhe Cao and Xing Fu

State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China

Appl. Sci. 2017, 7(9), 892; https://doi.org/10.3390/app7090892 - 1 Sep 2017

Cited by 4 | Viewed by 6509

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 [...] Read more.

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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11 pages, 2720 KiB

Open AccessReview

Multi-Scale Evaluation of the Interphase Zone between the Overlay and Concrete Substrate: Methods and Descriptors

by Łukasz Sadowski

Faculty of Civil Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspianskiego 27, 50-370 Wroclaw, Poland

Appl. Sci. 2017, 7(9), 893; https://doi.org/10.3390/app7090893 - 1 Sep 2017

Cited by 22 | Viewed by 5578

Abstract

This article presents the problem of examining the interphase zone between the overlay and concrete substrate at different levels of observation. The possibility of applying available modern research methods in order to examine the interphase zone with regard to the level of observation [...] Read more.

This article presents the problem of examining the interphase zone between the overlay and concrete substrate at different levels of observation. The possibility of applying available modern research methods in order to examine the interphase zone with regard to the level of observation is presented. These levels were defined in the paper. Examples of tests that show a possible approach to the examination of the interphase zone are also presented. Full article

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18 pages, 3781 KiB

Open AccessReview

Perspective on Double Pulsed Gas Metal Arc Welding

by Leilei Wang^*

and Jiaxiang Xue^*

School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China

Appl. Sci. 2017, 7(9), 894; https://doi.org/10.3390/app7090894 - 1 Sep 2017

Cited by 34 | Viewed by 10123

Abstract

Aluminum alloy welding suffers from problems such as solidification cracking and hydrogen-induced porosity, which are sufficiently severe to limit its potential applications. Because mitigated porosity incidence and solidification cracking are observed in aluminum welds using double pulsed gas metal arc welding (DP-GMAW), a [...] Read more.

Aluminum alloy welding suffers from problems such as solidification cracking and hydrogen-induced porosity, which are sufficiently severe to limit its potential applications. Because mitigated porosity incidence and solidification cracking are observed in aluminum welds using double pulsed gas metal arc welding (DP-GMAW), a comprehensive review of the mechanism is necessary, but absent from the literature. The oscillation of arc force and droplet pressure causes a weld pool stir effect. The expansion and shrinkage of the weld pool cause unusual remelting and resolidification of the previously solidified metal. DP-GMAW has an increased solidification growth rate and cooling rate, compared with conventional pulsed welding at same heat input. Both numerical and experimental results reveal the remarkable concept that refined microstructure in the fusion zone is obtained by using DP-GMAW. The mechanism of microstructural refinement is revealed as a weld pool stir effect and increased cooling rate. Hydrogen bubbles easily float out and then release from the weld pool originated from the weld pool stir effect. Reduced solidification cracking is achieved due to the refined solidification structure that originated from the increased cooling rate. The advantages, evolution process, and future trend of DP-GMAW are discussed. Full article

(This article belongs to the Special Issue Gas Tungsten Arc Welding)

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11 pages, 2858 KiB

Open AccessFeature PaperArticle

Experimental Study on Robustness of an Eddy Current-Tuned Mass Damper

by Junda Chen¹, Guangtao Lu^1,2,*, Yourong Li¹, Tao Wang², Wenxi Wang^3,4 and Gangbing Song^3,*

¹ Key Laboratory for Metallurgical Equipment and Control of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China

² Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China

³ Smart Materials and Structures Laboratory, Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA

⁴ Key Laboratory for Bridge and Wind Engineering of Hunan Province, College of Civil Engineering, Hunan University, Changsha 410082, China

Appl. Sci. 2017, 7(9), 895; https://doi.org/10.3390/app7090895 - 1 Sep 2017

Cited by 34 | Viewed by 8117

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 [...] Read more.

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

(This article belongs to the Special Issue Development and Application of Nonlinear Dissipative Device in Structural Vibration Control)

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42 pages, 11574 KiB

Open AccessFeature PaperReview

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

by Luca Schenato

National Research Council, Research Institute for Geo-Hydrological Protection, Corso Stati Uniti 4, I-35127 Padova, Italy

Appl. Sci. 2017, 7(9), 896; https://doi.org/10.3390/app7090896 - 1 Sep 2017

Cited by 217 | Viewed by 18245

Abstract

Distributed optical fibre sensing, employing either Rayleigh, Raman, or Brillouin scattering, is the only physical-contact sensor technology capable of accurately estimating physical fields with spatial continuity along the fibre. This unique feature and the other features of standard optical fibre sensors (e.g., minimal [...] Read more.

Distributed optical fibre sensing, employing either Rayleigh, Raman, or Brillouin scattering, is the only physical-contact sensor technology capable of accurately estimating physical fields with spatial continuity along the fibre. This unique feature and the other features of standard optical fibre sensors (e.g., minimal invasiveness and lightweight, remote powering/interrogating capabilities) have for many years promoted the technology to be a promising candidate for geo-hydrological monitoring. Relentless research efforts are being undertaken to bring the technology to complete maturity through laboratory, physical models, and in-situ tests. The application of distributed optical fibre sensors to geo-hydrological monitoring is here reviewed and discussed, along with basic principles and main acquisition techniques. Among the many existing geo-hydrological processes, the emphasis is placed on those related to soil levees, slopes/landslide, and ground subsidence that constitute a significant percentage of current geohazards. Full article

(This article belongs to the Special Issue Distributed Optical Fiber Sensors)

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13 pages, 8651 KiB

Open AccessArticle

Properties of Aged GFRP Reinforcement Grids Related to Fatigue Life and Alkaline Environment

by Francesco Micelli¹, Marco Corradi^2,*

, Maria Antonietta Aiello^1,* and Antonio Borri²

¹ Department of Innovation Engineering, University of Salento, Via per Monteroni, 73100 Lecce, Italy

² Department of Engineering, Perugia University, Via Duranti, 92, 06125 Perugia, Italy

Appl. Sci. 2017, 7(9), 897; https://doi.org/10.3390/app7090897 - 1 Sep 2017

Cited by 13 | Viewed by 4577

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 [...] Read more.

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 Science and Engineering)

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21 pages, 12936 KiB

Open AccessArticle

Comparative Study of Two Dynamics-Model-Based Estimation Algorithms for Distributed Drive Electric Vehicles

by Xudong Zhang, Dietmar Göhlich^* and Chenrui Fu

Product Development Methods and Mechatronics, Technical University of Berlin, 10623 Berlin, Germany

Appl. Sci. 2017, 7(9), 898; https://doi.org/10.3390/app7090898 - 1 Sep 2017

Cited by 9 | Viewed by 5684

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 [...] Read more.

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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10 pages, 2073 KiB

Open AccessArticle

A Dispersive Inelastic X-ray Scattering Spectrometer for Use at X-ray Free Electron Lasers

by Jakub Szlachetko^1,2,*, Maarten Nachtegaal¹, Daniel Grolimund¹, Gregor Knopp¹, Sergey Peredkov³, Joanna Czapla–Masztafiak⁴ and Christopher J. Milne^1,*

¹ Paul Scherrer Institut, 5232 Villigen, Switzerland

² Institute of Physics, Jan Kochanowski University, 25-001 Kielce, Poland

³ Max-Planck-Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany

⁴ The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31342 Kraków, Poland

Appl. Sci. 2017, 7(9), 899; https://doi.org/10.3390/app7090899 - 1 Sep 2017

Cited by 14 | Viewed by 6063

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 [...] Read more.

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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9 pages, 1444 KiB

Open AccessArticle

Distinguishing Different Cancerous Human Cells by Raman Spectroscopy Based on Discriminant Analysis Methods

by Mingjie Tang¹, Liangping Xia^1,2,*, Dongshan Wei¹, Shihan Yan¹, Chunlei Du^1,* and Hong-Liang Cui^1,3

¹ Chongqing Key Laboratory of Multi-Scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China

² School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China

³ College of Instrumentation Science and Electrical Engineering, Jilin University, Changchun 130061, China

Appl. Sci. 2017, 7(9), 900; https://doi.org/10.3390/app7090900 - 1 Sep 2017

Cited by 16 | Viewed by 5444

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 [...] Read more.

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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19 pages, 12209 KiB

Open AccessArticle

A Two-Stage Approach to Note-Level Transcription of a Specific Piano

by Qi Wang^1,2, Ruohua Zhou^1,2,* and Yonghong Yan^1,2,3

¹ Key Laboratory of Speech Acoustics and Content Understanding, Institute of Acoustics, Chinese Academyof Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100190, China

³ Xinjiang Laboratory of Minority Speech and Language Information Processing, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumchi 830001, China

Appl. Sci. 2017, 7(9), 901; https://doi.org/10.3390/app7090901 - 2 Sep 2017

Cited by 17 | Viewed by 7743

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 [...] Read more.

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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10 pages, 5176 KiB

Open AccessArticle

Fabrication and Characterizations of Hot-Melt Extruded Nanocomposites Based on Zinc Sulfate Monohydrate and Soluplus

by Song Yi Lee^1,†, Suyeong Nam^1,†, Yohan Choi², Minju Kim², Ja Seong Koo¹, Byung-Jo Chae², Wie-Soo Kang³ and Hyun-Jong Cho^1,*

¹ College of Pharmacy, Kangwon National University, Chuncheon, Gangwon 24341, Korea

² Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Gangwon 24341, Korea

³ School of Bioscience and Biotechnology, Kangwon National University, Chuncheon, Gangwon 24341, Korea

^† These authors equally contributed to this work.

Appl. Sci. 2017, 7(9), 902; https://doi.org/10.3390/app7090902 - 4 Sep 2017

Cited by 38 | Viewed by 6707

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 [...] Read more.

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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18 pages, 2229 KiB

Open AccessArticle

Collision Avoidance from Multiple Passive Agents with Partially Predictable Behavior

by Khalil Muhammad Zuhaib¹, Abdul Manan Khan², Junaid Iqbal¹, Mian Ashfaq Ali³, Muhammad Usman¹, Ahmad Ali¹, Sheraz Yaqub¹, Ji Yeong Lee² and Changsoo Han^2,*

¹ Department of Mechatronics Engineering, Hanyang University ERICA Campus, Ansan 15588, Korea

² Department of Robot Engineering, Hanyang University ERICA Campus, Ansan 15588, Korea

³ School of Mechanical and Manufacturing Engineering (SMME), National University of Science and Techonology (NUST), Islamabad 44000, Pakistan

Appl. Sci. 2017, 7(9), 903; https://doi.org/10.3390/app7090903 - 4 Sep 2017

Cited by 7 | Viewed by 5482

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 [...] Read more.

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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12 pages, 3380 KiB

Open AccessArticle

Effects of Using Different Sources of Remote Sensing and Geographic Information System Data on Urban Stormwater 2D–1D Modeling

by Yi Hong^1,*

, Céline Bonhomme¹, Bahman Soheilian² and Ghassan Chebbo^1,3

¹ LEESU, MA 102, École des Ponts, Agro Paris Tech, UPEC, UPE, 77455 Champs-sur-Marne, France

² LASTIG MATIS, IGN, ENSG, University Paris-Est, F-94160 Saint-Mande, France

³ Faculté de Génie, Université Libanaise, Faculté de Génie, Campus Rafic Hariri 6573, Hadat, Lebanon

Appl. Sci. 2017, 7(9), 904; https://doi.org/10.3390/app7090904 - 5 Sep 2017

Cited by 7 | Viewed by 4679

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 [...] Read more.

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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16 pages, 4129 KiB

Open AccessArticle

Analysis of MTF in TDI-CCD Subpixel Dynamic Super-Resolution Imaging by Beam Splitter

by Kun Gao^*, Lu Han, Hongmiao Liu, Zeyang Dou, Guoqiang Ni and Yingjie Zhou

Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Beijing Institute of Technology, Beijing 100081, China

Appl. Sci. 2017, 7(9), 905; https://doi.org/10.3390/app7090905 - 5 Sep 2017

Cited by 2 | Viewed by 6985

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 [...] Read more.

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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19 pages, 10102 KiB

Open AccessArticle

LiDARgrammetry: A New Method for Generating Synthetic Stereoscopic Products from Digital Elevation Models

by Ricardo Rodríguez-Cielos¹, José Luis Galán-García^2,*

, Yolanda Padilla-Domínguez²

, Pedro Rodríguez-Cielos², Ana Belén Bello-Patricio³

and José Antonio López-Medina¹

¹ Universidad Politécnica de Madrid, University of Madrid, 28040 Madrid, Spain

² Escuela de Ingenierías Industriales, University of Málaga, 29071 Málaga, Spain

³ Universidad Complutense de Madrid, University of Madrid, 28040 Madrid, Spain

Appl. Sci. 2017, 7(9), 906; https://doi.org/10.3390/app7090906 - 12 Sep 2017

Cited by 5 | Viewed by 6179

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 [...] Read more.

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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24 pages, 2341 KiB

Open AccessArticle

Inverse Optimal Design for Position Control of a Quadrotor

by Keun Uk Lee¹, Yoon Ho Choi² and Jin Bae Park^1,*

¹ School of Electrical and Electronic Engineering, Yonsei University, Seodaemun-Gu, Seoul 03722, Korea

² Department of Electronic Engineering, Kyonggi University, Suwon, Kyonggi-Do 16227, Korea

Appl. Sci. 2017, 7(9), 907; https://doi.org/10.3390/app7090907 - 5 Sep 2017

Cited by 12 | Viewed by 4919

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 [...] Read more.

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

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13 pages, 3050 KiB

Open AccessFeature PaperArticle

Estimation of the Performance Improvement of Pre-Amplified PAM4 Systems When Using Multi-Section Semiconductor Optical Amplifiers

by Seán P. Ó Dúill^*

, Pascal Landais

and Liam P. Barry

Radio and optics research laboratory, School of Electronic Engineering, Dublin City University, Dublin 9 D09 W6Y4, Ireland

Appl. Sci. 2017, 7(9), 908; https://doi.org/10.3390/app7090908 - 5 Sep 2017

Cited by 9 | Viewed by 7042

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 [...] Read more.

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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17 pages, 5677 KiB

Open AccessReview

Laser Welding under Vacuum: A Review

by Meng Jiang, Wang Tao^* and Yanbin Chen^*

State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China

Appl. Sci. 2017, 7(9), 909; https://doi.org/10.3390/app7090909 - 5 Sep 2017

Cited by 41 | Viewed by 14867

Abstract

Laser welding has been widely used in various industry fields. In order to further alter and broaden its applicability, a novel technology of laser welding under vacuum is introduced. The combination of high power laser and low ambient pressure provides an excellent welding [...] Read more.

Laser welding has been widely used in various industry fields. In order to further alter and broaden its applicability, a novel technology of laser welding under vacuum is introduced. The combination of high power laser and low ambient pressure provides an excellent welding performance and quality. In this paper, an overview on laser welding under vacuum is presented. It begins with a short introduction about the research status of laser welding under vacuum. Next, the equipment of laser welding under vacuum is introduced. Then, the fundamental phenomena of laser welding under vacuum, including penetration depth, weld geometry, plasma plume, molten pool and keyhole behaviors, are summarized in detail. Finally, the applications and prospects of laser welding under vacuum are proposed. Full article

(This article belongs to the Special Issue Solid State Lasers Materials, Technologies and Applications)

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13 pages, 3548 KiB

Open AccessArticle

Properties of Extrusion Concrete Panel Using Waste Concrete Powder

by Ha-Seog Kim¹, Sea-Hyun Lee² and Byoungil Kim^3,*

¹ Department of Architectural Engineering, Kongju National University, 275 Cheonan-daero, Cheonan City, Chungcheongnam-do 330-717, Korea

² Building and Urban Research Institute, Korea Institute of Civil Engineering and Building Technology, Ilsanseo-gu, Goyang 411-712, Korea

³ School of Architecture, Seoul National University of Science & Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Korea

Appl. Sci. 2017, 7(9), 910; https://doi.org/10.3390/app7090910 - 5 Sep 2017

Cited by 16 | Viewed by 4653

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 [...] Read more.

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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15 pages, 5322 KiB

Open AccessArticle

The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems

by Ying Ma^1,2, Haopeng Liu^1,2, Yunpeng Zhu³

, Fei Wang^1,2 and Zhong Luo^1,2,*

¹ School of Mechanical Engineering & Automation, Northeastern University, Shenyang 110819, China

² Key Laboratory of Vibration and Control of Aero-Propulsion System Ministry of Education, Northeastern University, Shenyang 110819, China

³ Department of Automatic Control and System Engineering, University of Sheffield, Sheffield S13JD, UK

Appl. Sci. 2017, 7(9), 911; https://doi.org/10.3390/app7090911 - 5 Sep 2017

Cited by 37 | Viewed by 6276

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 [...] Read more.

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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15 pages, 4656 KiB

Open AccessFeature PaperArticle

Habitat Potential Mapping of Marten (Martes flavigula) and Leopard Cat (Prionailurus bengalensis) in South Korea Using Artificial Neural Network Machine Learning

by Saro Lee^1,2

, Sunmin Lee^3,4

, Wonkyong Song⁵ and Moung-Jin Lee^4,*

¹ Geological Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 124, Gwahak-ro Yuseong-gu, Daejeon 34132, Korea

² Korea University of Science and Technology, 217 Gajeong-ro Yuseong-gu, Daejeon 34113, Korea

³ Department of Geoinformatics, University of Seoul, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul 02504, Korea

⁴ Center for Environmental Assessment Monitoring, Environmental Assessment Group, Korea Environment Institute (KEI), 370 Sicheong-daero, Sejong 30147, Korea

⁵ Department of Landscape Architecture, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan-si, Chungnam 31116, Korea

Appl. Sci. 2017, 7(9), 912; https://doi.org/10.3390/app7090912 - 5 Sep 2017

Cited by 19 | Viewed by 6328

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 [...] Read more.

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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14 pages, 7258 KiB

Open AccessArticle

Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

by Matti Manninen^1,*, Marika Hirvimäki¹, Ville-Pekka Matilainen¹ and Antti Salminen^1,2

¹ Laboratory of Laser Processing, School of Energy Systems, Lappeenranta University of Technology, 53850 Lappeenranta, Finland

² Machine Technology Center Turku Ltd., 20520 Turku, Finland

Appl. Sci. 2017, 7(9), 913; https://doi.org/10.3390/app7090913 - 6 Sep 2017

Cited by 3 | Viewed by 7189

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 [...] Read more.

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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12 pages, 14392 KiB

Open AccessArticle

Investigation of Laser Cutting Width of LiCoO₂ Coated Aluminum for Lithium-Ion Batteries

by Dongkyoung Lee^1,*

and Sanghoon Ahn²

¹ Department of Mechanical and Automotive Engineering, Kongju National University, Cheonan 31080, Korea

² Department of Laser and Electron Beam Application, Korean Institute of Machinery & Materials (KIMM), Daejeon 34103, Korea

Appl. Sci. 2017, 7(9), 914; https://doi.org/10.3390/app7090914 - 6 Sep 2017

Cited by 26 | Viewed by 6554

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 [...] Read more.

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 \times 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 \times 10^{10} - 8.0229 \times 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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41 pages, 10966 KiB

Open AccessReview

Ultrashort Free-Electron Laser X-ray Pulses

by Wolfram Helml^1,2, Ivanka Grguraš³, Pavle N. Juranić⁴, Stefan Düsterer⁵, Tommaso Mazza⁶, Andreas R. Maier⁷, Nick Hartmann⁸, Markus Ilchen⁶, Gregor Hartmann⁹, Luc Patthey⁴, Carlo Callegari¹⁰, John T. Costello¹¹, Michael Meyer⁶, Ryan N. Coffee¹², Adrian L. Cavalieri³ and Reinhard Kienberger^2,*

¹ Department für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching, Germany

² Physik-Department E11, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany

³ Center for Free-Electron Laser Science, Notkestraße 85, 22607 Hamburg, Germany

⁴ Paul Scherrer Institut, 5232 Villigen, Switzerland

⁵ Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany

⁶ European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany

⁷ Center for Free-Electron Laser Science & Department of Physics, University of Hamburg, 22761 Hamburg, Germany

⁸ Coherent Inc., 5100 Patrick Henry Drive, Santa Clara, CA 95054, USA

⁹ Institut für Physik und CINSaT, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany

¹⁰ Elettra—Sincrotrone Trieste, Strada Statale 14–km 163.5 in AREA Science Park, 34149 Basovizza, Trieste, Italy

¹¹ National Center for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9, Ireland

¹² SLAC National Accelerator Laboratory, Linac Coherent Light Source, Menlo Park, CA 94025, USA

Show full affiliation list Hide full affiliation list

Appl. Sci. 2017, 7(9), 915; https://doi.org/10.3390/app7090915 - 6 Sep 2017

Cited by 31 | Viewed by 13399

Abstract

For the investigation of processes happening on the time scale of the motion of bound electrons, well-controlled X-ray pulses with durations in the few-femtosecond and even sub-femtosecond range are a necessary prerequisite. Novel free-electron lasers sources provide these ultrashort, high-brightness X-ray pulses, but [...] Read more.

For the investigation of processes happening on the time scale of the motion of bound electrons, well-controlled X-ray pulses with durations in the few-femtosecond and even sub-femtosecond range are a necessary prerequisite. Novel free-electron lasers sources provide these ultrashort, high-brightness X-ray pulses, but their unique aspects open up concomitant challenges for their characterization on a suitable time scale. In this review paper we describe progress and results of recent work on ultrafast pulse characterization at soft and hard X-ray free-electron lasers. We report on different approaches to laser-assisted time-domain measurements, with specific focus on single-shot characterization of ultrashort X-ray pulses from self-amplified spontaneous emission-based and seeded free-electron lasers. The method relying on the sideband measurement of X-ray electron ionization in the presence of a dressing optical laser field is described first. When the X-ray pulse duration is shorter than half the oscillation period of the streaking field, few-femtosecond characterization becomes feasible via linear streaking spectroscopy. Finally, using terahertz fields alleviates the issue of arrival time jitter between streaking laser and X-ray pulse, but compromises the achievable temporal resolution. Possible solutions to these remaining challenges for single-shot, full time–energy characterization of X-ray free-electron laser pulses are proposed in the outlook at the end of the review. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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6 pages, 1646 KiB

Open AccessArticle

Ion-Mediated Aggregation of Gold Nanoparticles for Light-Induced Heating

by David Alba-Molina, María T. Martín-Romero, Luis Camacho and Juan J. Giner-Casares^*

Institute of Fine Chemistry and Nanochemistry, Department of Physical Chemistry and Applied Thermodynamics, University of Córdoba, Campus Universitario de Rabanales, Edificio Marie Curie, E-14014 Córdoba, Spain

Appl. Sci. 2017, 7(9), 916; https://doi.org/10.3390/app7090916 - 7 Sep 2017

Cited by 25 | Viewed by 8324

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 [...] Read more.

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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15 pages, 389 KiB

Open AccessPerspective

A Review of Mixture Theory for Deformable Porous Media and Applications

by Javed Iqbal Siddique¹, Aftab Ahmed², Asim Aziz³ and Chaudry Masood Khalique^4,*

¹ Department of Mathematics, York Campus, Penn State University, York, PA 17403-3326, USA

² Department of Mathematics, Capital University of Science and Technology, Islamabad 44000, Pakistan

³ College of Electrical and Mechanical Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan

⁴ International Institute for Symmetry Analysis and Mathematical Modelling, Department of Mathematical Sciences, Mafikeng Campus, North-West University, Private Bag X 2046, Mmabatho 2735, South Africa

Appl. Sci. 2017, 7(9), 917; https://doi.org/10.3390/app7090917 - 9 Sep 2017

Cited by 35 | Viewed by 7124

Abstract

Mixture theory provides a continuum framework to model a multi-phase system. The basic assumption is, at any instant of time all phases are present at every material point and momentum and mass balance equations are postulated. This paper reviews the recent developments in [...] Read more.

Mixture theory provides a continuum framework to model a multi-phase system. The basic assumption is, at any instant of time all phases are present at every material point and momentum and mass balance equations are postulated. This paper reviews the recent developments in mixture theory and focuses on the applications of the theory in particular areas of biomechanics, composite manufacturing and infiltration into deformable porous materials. The complexity based upon different permeability and stress functions is also addressed. The review covers the literature presented in the past fifty years and summarizes applications of mixture theory in specific areas of interest, for the sake of brevity, only necessary details are provided rather than complete modeling and simulation. Full article

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20 pages, 5658 KiB

Open AccessArticle

Simulation of Tail Boom Vibrations Using Main Rotor-Fuselage Computational Fluid Dynamics (CFD)

by Andrey Batrakov¹, Alexander Kusyumov^1,*, Sergey Kusyumov¹, Sergey Mikhailov¹ and George N. Barakos²

¹ Aerohydrodynamics Department, Kazan National Research Technical University n.a. A.N. Tupolev (KNRTU-KAI), 10 Karl Marx St., Kazan 420111, Russia

² School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK

Appl. Sci. 2017, 7(9), 918; https://doi.org/10.3390/app7090918 - 7 Sep 2017

Cited by 5 | Viewed by 6212

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 [...] Read more.

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

(This article belongs to the Special Issue Advances in Vibroacoustics and Aeroacustics of Aerospace and Automotive Systems)

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14 pages, 1858 KiB

Open AccessArticle

Flow Characteristics of Steam and Gas Push in the Presence of Heat Thief Zones Overlying Oil Sands Deposits

by Changsoo Lee, Changhyup Park^*

and Soobin Park

Department of Energy and Resources Engineering, Kangwon National University, Chuncheon, Kangwon 24341, Korea

Appl. Sci. 2017, 7(9), 919; https://doi.org/10.3390/app7090919 - 7 Sep 2017

Cited by 9 | Viewed by 3777

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 [...] Read more.

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 Science and Technology)

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15 pages, 3606 KiB

Open AccessFeature PaperReview

Towards Large-Scale Fast Reprogrammable SOA-Based Photonic Integrated Switch Circuits

by Ripalta Stabile

Eindhoven University of Technology, Institute for Photonic Integration (IPI), Department of Electrical Engineering, 5612 AZ Eindhoven, The Netherlands

Appl. Sci. 2017, 7(9), 920; https://doi.org/10.3390/app7090920 - 7 Sep 2017

Cited by 13 | Viewed by 5679

Abstract

Due to the exponentially increasing connectivity and bandwidth demand from the Internet, the most advanced examples of medium-scale fast reconfigurable photonic integrated switch circuits are offered by research carried out for data- and computer-communication applications, where network flexibility at a high speed and [...] Read more.

Due to the exponentially increasing connectivity and bandwidth demand from the Internet, the most advanced examples of medium-scale fast reconfigurable photonic integrated switch circuits are offered by research carried out for data- and computer-communication applications, where network flexibility at a high speed and high connectivity are provided to suit network demand. Recently we have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip for high connectivity. In this paper, the current status of fast reconfigurable medium-scale indium phosphide (InP) integrated photonic switch matrices based on the use of semiconductor optical amplifier (SOA) gates is reviewed, focusing on broadband and cross-connecting monolithic implementations, granting a connectivity of up to sixteen input ports, sixteen output ports, and sixty-four channels, respectively. The opportunities for increasing connectivity, enabling nanosecond order reconfigurability, and introducing distributed optical power monitoring at the physical layer are highlighted. Complementary architecture based on resonant switching elements on the same material platform are also discussed for power efficient switching. Performance projections related to the physical layer are presented and strategies for improvements are discussed in view of opening a route towards large-scale power efficient fast reprogrammable photonic integrated switching circuits. Full article

(This article belongs to the Special Issue Applications of Semiconductor Optical Amplifiers)

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31 pages, 11574 KiB

Open AccessArticle

Enhancement of Energy Harvesting Performance by a Coupled Bluff Splitter Body and PVEH Plate through Vortex Induced Vibration near Resonance

by Wei Ken Chin¹, Zhi Chao Ong^1,2,*

, Keen Kuan Kong¹, Shin Yee Khoo¹

, Yu-Hsi Huang³ and Wen Tong Chong¹

¹ Department of Mechanical Engineering, Engineering Faculty, University of Malaya, Kuala Lumpur 50603, Malaysia

² Advanced Shock and Vibration Research Group, Applied Vibration Laboratory, Block R, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia

³ Department of Mechanical Engineering, National Taiwan University of Science and Technology, 106, Taiwan

Appl. Sci. 2017, 7(9), 921; https://doi.org/10.3390/app7090921 - 7 Sep 2017

Cited by 14 | Viewed by 6516

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 [...] Read more.

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 Science and Technology)

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13 pages, 1215 KiB

Open AccessReview

Near-Infrared Spectroscopy Applied to Complex Systems and Human Hyperscanning Networking

by Davide Crivelli^1,2,*

and Michela Balconi^1,2

¹ Research Unit in Affective and Social Neuroscience, Catholic University of the Sacred Heart, Largo Gemelli 1, 20123 Milano, Italy

² Department of Psychology, Catholic University of the Sacred Heart, Largo Gemelli 1, 20123 Milano, Italy

Appl. Sci. 2017, 7(9), 922; https://doi.org/10.3390/app7090922 - 8 Sep 2017

Cited by 27 | Viewed by 7023

Abstract

Concepts and techniques developed to investigate complex systems have found practical implications in the study of many complex physical, biological, and social phenomena. Social neuroscience is coherently moving to new investigation and analysis approaches to properly explore social dynamics and to qualify neural [...] Read more.

Concepts and techniques developed to investigate complex systems have found practical implications in the study of many complex physical, biological, and social phenomena. Social neuroscience is coherently moving to new investigation and analysis approaches to properly explore social dynamics and to qualify neural processes that mediate and define them. The present paper aims to sketch a global picture of the application of the concept of synchronization to study complex social systems and the neural signatures of interpersonal coupling during interaction dynamics. We then focus on an innovative experimental paradigm—hyperscanning—that allows researchers to sample, compare, and integrate information flows related to the bodily activities of two (or more) individuals involved in a shared naturalistic or experimentally-controlled task, thus giving the opportunity to explore inter-individual synchronization and inter-brain coupling. In particular, the potential of functional Near-Infrared Spectroscopy (fNIRS) as a primary investigation tool in the field is discussed. Finally, we introduce the most-used quantification and analysis methods for hyperscanning applications. Full article

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17 pages, 6307 KiB

Open AccessArticle

Real-Time Transportation Mode Identification Using Artificial Neural Networks Enhanced with Mode Availability Layers: A Case Study in Dubai

by Young-Ji Byon^1,*

, Jun Su Ha², Chung-Suk Cho¹

, Tae-Yeon Kim¹ and Chan Yeob Yeun³

¹ Department of Civil Infrastructure and Environmental Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi L2017E, UAE

² Department of Nuclear Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi L2017E, UAE

³ Department of Electrical and Computer Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi L2017E, UAE

Appl. Sci. 2017, 7(9), 923; https://doi.org/10.3390/app7090923 - 8 Sep 2017

Cited by 58 | Viewed by 8280

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 [...] Read more.

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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11 pages, 3421 KiB

Open AccessCommunication

Low-Cost Nanocarbon-Based Peroxidases from Graphite and Carbon Fibers

by Yan Zeng, Feifan Miao, Zhiyong Zhao, Yuting Zhu, Tao Liu, Rongsheng Chen, Simin Liu

, Zaosheng Lv and Feng Liang^*

The State Key Laboratory of Refractories and Metallurgy, School of Chemistry & Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, China

Appl. Sci. 2017, 7(9), 924; https://doi.org/10.3390/app7090924 - 8 Sep 2017

Cited by 14 | Viewed by 5302

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 [...] Read more.

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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25 pages, 6205 KiB

Open AccessArticle

An Event Reporting and Early-Warning Safety System Based on the Internet of Things for Underground Coal Mines: A Case Study

by Byung Wan Jo and Rana Muhammad Asad Khan^*

Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea

Appl. Sci. 2017, 7(9), 925; https://doi.org/10.3390/app7090925 - 8 Sep 2017

Cited by 56 | Viewed by 11348

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 [...] Read more.

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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8 pages, 837 KiB

Open AccessArticle

Detecting Anatomical Leg Length Discrepancy Using the Plug-in-Gait Model

by Sam Khamis^1,2,*

, Barry Danino^3,4, Shmuel Springer⁵

, Dror Ovadia^3,4 and Eli Carmeli²

¹ Gait and Motion Analysis Laboratory, Department of Pediatric Orthopaedics, Dana Children’s Hospital, Tel Aviv Sourasky Medical Center, 6, Weizman St., Tel Aviv 64239, Israel

² Department of Physical Therapy, University of Haifa, Haifa 31000, Israel

³ Department of Pediatric Orthopaedics, Dana Children’s Hospital, Tel Aviv Sourasky Medical Center, 6, Weizman St., Tel Aviv 64239, Israel

⁴ Sackler Faculty of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel

⁵ Physical Therapy Department, Faculty of Health Sciences Ariel University, Ariel 40700, Israel

Appl. Sci. 2017, 7(9), 926; https://doi.org/10.3390/app7090926 - 8 Sep 2017

Cited by 6 | Viewed by 7951

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 [...] Read more.

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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23 pages, 4335 KiB

Open AccessArticle

Optimal Control and Operation Strategy for Wind Turbines Contributing to Grid Primary Frequency Regulation

by Mun-Kyeom Kim

School of Energy System Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea

Appl. Sci. 2017, 7(9), 927; https://doi.org/10.3390/app7090927 - 8 Sep 2017

Cited by 27 | Viewed by 5888

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 [...] Read more.

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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18 pages, 3403 KiB

Open AccessArticle

Agent-Based Model for Automaticity Management of Traffic Flows across the Network

by Karina Raya-Díaz^1,*

, Carelia Gaxiola-Pacheco¹

, Manuel Castañón-Puga¹

, Luis E. Palafox¹, Juan R. Castro¹ and Dora-Luz Flores²

¹ Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Calzada Universidad 14418, Tijuana 22390, Mexico

² Facultad de Ingeniería, Arquitectura y Diseño, Universidad Autónoma de Baja California, Carretera Transpeninsular Ensenada, Tijuana 3917, Colonia Playitas, Ensenada, Baja California, Mexico

Appl. Sci. 2017, 7(9), 928; https://doi.org/10.3390/app7090928 - 9 Sep 2017

Cited by 7 | Viewed by 4876

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 [...] Read more.

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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13 pages, 4164 KiB

Open AccessReview

High Performance MRAM with Spin-Transfer-Torque and Voltage-Controlled Magnetic Anisotropy Effects

by Hao Cai^1,2,*, Wang Kang^3,*, You Wang², Lirida Alves De Barros Naviner², Jun Yang¹ and Weisheng Zhao³

¹ National ASIC System Engineering Center, Southeast University, Nanjing 210096, China

² Département Communications et Electronique, Télécom ParisTech, Université Paris-Saclay, 75013 Paris, France

³ Fert Beijing Institute, Beijing Advanced Innovation Center for Big Data and Brain Computing and School of Electronic and Information Engineering, Beihang Univeristy, Beijing 100191, China

Appl. Sci. 2017, 7(9), 929; https://doi.org/10.3390/app7090929 - 11 Sep 2017

Cited by 46 | Viewed by 10161

Abstract

The Internet of Things (IoTs) relies on efficient node memories to process data among sensors, cloud and RF front-end. Both mainstream and emerging memories have been developed to achieve this energy efficiency target. Spin transfer torque magnetic tunnel junction (STT-MTJ)-based nonvolatile memory (NVM) [...] Read more.

The Internet of Things (IoTs) relies on efficient node memories to process data among sensors, cloud and RF front-end. Both mainstream and emerging memories have been developed to achieve this energy efficiency target. Spin transfer torque magnetic tunnel junction (STT-MTJ)-based nonvolatile memory (NVM) has demonstrated great performance in terms of zero standby power, switching power efficiency, infinite endurance and high density. However, it still has a big performance gap; e.g., high dynamic write energy, large latency, yield and reliability. Recently, voltage-controlled magnetic anisotropy (VCMA) has been introduced to achieve improved energy-delay efficiency and robust non-volatile writing control with an electric field or a switching voltage. VCMA-MTJ-based MRAM could be a promising candidate in IoT node memory for high-performance, ultra-low power consumption targets. Full article

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23 pages, 7485 KiB

Open AccessArticle

Air Entrainment and Air Demand in the Spillway Tunnel at the Jinping-I Dam

by Jijian Lian¹, Chunfeng Qi¹, Fang Liu^1,*

, Wenjuan Gou¹, Shunqi Pan²

and Qunan Ouyang¹

¹ State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Civil Engineering, Tianjin University, Tianjin 300072, China

² School of Engineering, Cardiff University, Cardiff CF24 3AA, UK

Appl. Sci. 2017, 7(9), 930; https://doi.org/10.3390/app7090930 - 10 Sep 2017

Cited by 22 | Viewed by 7196

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 [...] Read more.

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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11 pages, 3136 KiB

Open AccessArticle

Changes in Pore Structure of Coal Associated with Sc-CO₂ Extraction during CO₂-ECBM

by Run Chen^1,2,*

, Yong Qin², Chongtao Wei², Linlin Wang¹, Youyang Wang² and Pengfei Zhang²

¹ Key Laboratory of Coal-based CO2 Capture & Geological Storage, Low Carbon Energy Institute, China University of Mining and Technology, Xuzhou 221008, China

² Key Laboratory of Coalbed Methane Resource & Reservoir Formation History, School of Resource and Geoscience, China University of Mining and Technology, Xuzhou 221008, China

Appl. Sci. 2017, 7(9), 931; https://doi.org/10.3390/app7090931 - 10 Sep 2017

Cited by 34 | Viewed by 5121

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 [...] Read more.

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. ΔV_Ma and ΔV_Me of coal samples are positive, ΔV_Tr and ΔV_Mi are positive for most coals, and ΔV_Mi of higher coals are negative; the ΔS_Ma and ΔS_Me are positive with small values, the ΔS_Tr and ΔS_M_i 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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21 pages, 8134 KiB

Open AccessArticle

Frequency Modulation and Erosion Performance of a Self-Resonating Jet

by Wenchuan Liu^1,2,3, Yong Kang^1,2,3,*, Mingxing Zhang⁴, Yongxiang Zhou⁵, Xiaochuan Wang^1,2,3

and Deng Li^1,2,3

¹ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China; chuan@whu.edu.cn (W.L.); xcw001@whu.edu.cn (X.W.); 2008lee@whu.edu.cn (D.L.)

² Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan 430072, China

³ School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China

⁴ Shanghai Marine Equipment Research Institute, Shanghai 200030, China; mingxing1991zhang@163.com

⁵ Wuhan Hangda Aero Science & Technology Development CO., LTD, Wuhan 430072, China; zhouyongxiang@whu.edu.cn

Appl. Sci. 2017, 7(9), 932; https://doi.org/10.3390/app7090932 - 10 Sep 2017

Cited by 20 | Viewed by 4730

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 [...] Read more.

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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10 pages, 14386 KiB

Open AccessArticle

Measurement Matrix Analysis and Radiation Improvement of a Metamaterial Aperture Antenna for Coherent Computational Imaging

by Na Kou

, Long Li^*

, Shuncheng Tian

and Yuanchang Li

Key Laboratory of High Speed Circuit Design and EMC of Ministry of Education, School of Electronic Engineering, Collaborative Innovation Center of Information Sensing and Understanding, Xidian University, Xi’an 710071, China

Appl. Sci. 2017, 7(9), 933; https://doi.org/10.3390/app7090933 - 12 Sep 2017

Cited by 7 | Viewed by 5022

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 [...] Read more.

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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10 pages, 8479 KiB

Open AccessArticle

Experimental Study on Milling CFRP with Staggered PCD Cutter

by Tao Chen^*, Daoyuan Wang, Fei Gao and Xianli Liu

School of Mechanical and Power Engineering, Harbin University of Science and Technology, 150080 Harbin, China

Appl. Sci. 2017, 7(9), 934; https://doi.org/10.3390/app7090934 - 11 Sep 2017

Cited by 8 | Viewed by 4516

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 [...] Read more.

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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14 pages, 12161 KiB

Open AccessArticle

Analysis of the Pyroclastic Flow Deposits of Mount Sinabung and Merapi Using Landsat Imagery and the Artificial Neural Networks Approach

by Prima Riza Kadavi¹, Won-Jin Lee² and Chang-Wook Lee^1,*

¹ Division of Science Education, Kangwon National University, 1 Kangwondaehak-gil, Chuncheon-si, Gangwon-do 24341, Korea

² Earthquake Volcano Research Center, Korea Meteorological Administration, 61 16-Gil, Yeouidaebang-ro, Dongjak-Gu, Seoul 07062, Korea

Appl. Sci. 2017, 7(9), 935; https://doi.org/10.3390/app7090935 - 11 Sep 2017

Cited by 18 | Viewed by 8588

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 [...] Read more.

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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16 pages, 835 KiB

Open AccessArticle

Localization in Low Power Wide Area Networks Using Wi-Fi Fingerprints

by Thomas Janssen, Maarten Weyn

and Rafael Berkvens^*

IDLab–Faculty of Applied Engineering, University of Antwerp–imec, Groenenborgerlaan 171, 2020 Antwerpen, Belgium

Appl. Sci. 2017, 7(9), 936; https://doi.org/10.3390/app7090936 - 12 Sep 2017

Cited by 16 | Viewed by 4838

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 [...] Read more.

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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25 pages, 6814 KiB

Open AccessArticle

Weak Fault Feature Extraction Scheme for Intershaft Bearings Based on Linear Prediction and Order Tracking in the Rotation Speed Difference Domain

by Zhinong Jiang, Minghui Hu

, Kun Feng^* and Ya He

College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Chao Yang District, Beijing 100029, China

Appl. Sci. 2017, 7(9), 937; https://doi.org/10.3390/app7090937 - 12 Sep 2017

Cited by 24 | Viewed by 4888

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 [...] Read more.

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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15 pages, 7464 KiB

Open AccessArticle

Ultralow Friction of ZrO₂ Ball Sliding against DLC Films under Various Environments

by Qunfeng Zeng^1,*, Ali Erdemir² and Osman Erylimaz²

¹ Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System and School of Food Equipment Engineering and Science, Xi’an Jiaotong University, Xi’an 710049, China

² Energy Systems, Argonne National Laboratory, Argonne, IL 60439, USA

Appl. Sci. 2017, 7(9), 938; https://doi.org/10.3390/app7090938 - 12 Sep 2017

Cited by 22 | Viewed by 5756

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 [...] Read more.

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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14 pages, 3429 KiB

Open AccessArticle

Structure and Capacitance of Electrical Double Layers at the Graphene–Ionic Liquid Interface

by Pengfei Lu¹, Qiaobo Dai², Liangyu Wu¹ and Xiangdong Liu^1,2,*

¹ School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China

² School of Energy and Environment, Southeast University, Nanjing 210096, China

Appl. Sci. 2017, 7(9), 939; https://doi.org/10.3390/app7090939 - 12 Sep 2017

Cited by 20 | Viewed by 7921

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 [...] Read more.

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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16 pages, 22234 KiB

Open AccessArticle

Competitive Evaluation of Planar Embedded Glass and Polymer Waveguides in Data Center Environments

by Richard Pitwon^1,*

, Kai Wang¹, Akira Yamauchi², Takaaki Ishigure², Henning Schröder³, Marcel Neitz⁴ and Mayank Singh⁵

¹ Photonics Advanced Research Group, Seagate, Havant, Hampshire PO9 1SA, UK

² Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

³ Fraunhofer-Gesellschaft zur Foerderung der Angewandten Forschung e.V, Fraunhofer IZM, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany

⁴ Technische Universität Berlin, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany

⁵ Sumitomo Bakelite, Sumitomo Bakelite Co., Ltd., Tennoz Parkside Building 19 F, Shinagawa-ku, Tokyo 140-0002, Japan

Appl. Sci. 2017, 7(9), 940; https://doi.org/10.3390/app7090940 - 13 Sep 2017

Cited by 6 | Viewed by 6794

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 [...] Read more.

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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20 pages, 3690 KiB

Open AccessArticle

A New Method for Analysing the Pressure Response Delay in a Pneumatic Brake System Caused by the Influence of Transmission Pipes

by Fan Yang¹, Gangyan Li^1,*, Jian Hua¹, Xingli Li¹ and Toshiharu Kagawa²

¹ School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China

² Laboratory for FIRST, Tokyo Institute of Technology, Yokohama 226-8503, Japan

Appl. Sci. 2017, 7(9), 941; https://doi.org/10.3390/app7090941 - 13 Sep 2017

Cited by 19 | Viewed by 11960

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 [...] Read more.

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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14 pages, 9254 KiB

Open AccessArticle

Open Source 3-D Printed Nutating Mixer

by Dhwani K. Trivedi¹ and Joshua M. Pearce^1,2,3,*

¹ Department of Electrical & Computer Engineering, Michigan Technological University, Houghton, MI 49931, USA

² Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, 02150 Espoo, Finland

³ Department of Materials Science & Engineering, Michigan Technological University, Houghton, MI 49931, USA

Appl. Sci. 2017, 7(9), 942; https://doi.org/10.3390/app7090942 - 13 Sep 2017

Cited by 18 | Viewed by 10767

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, [...] Read more.

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 Science and Engineering)

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21 pages, 5032 KiB

Open AccessArticle

Coordinated Control of the Energy Router-Based Smart Home Energy Management System

by Yingshu Liu^1,*

, Jun Li¹, Yao Wu¹ and Feng Zhou²

¹ School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China

² State Grid Chongqing Electric Power CO., Electric Power Research Institute, Chongqing 401120, China

Appl. Sci. 2017, 7(9), 943; https://doi.org/10.3390/app7090943 - 13 Sep 2017

Cited by 23 | Viewed by 8002

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 [...] Read more.

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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13 pages, 1925 KiB

Open AccessArticle

Characterization of Surface Ozone Behavior at Different Regimes

by Nádia F. Afonso and José C. M. Pires^*

Laboratório de Engenharia de Processos, Ambiente Biotecnologia e Energia (LEPABE), Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

Appl. Sci. 2017, 7(9), 944; https://doi.org/10.3390/app7090944 - 14 Sep 2017

Cited by 16 | Viewed by 4575

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 [...] Read more.

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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16 pages, 9019 KiB

Open AccessArticle

Study of the Direct Metal Deposition of AA2024 by ElectroSpark for Coating and Reparation Scopes

by Paola Leo¹, Gilda Renna¹ and Giuseppe Casalino^2,*

¹ Innovation Engineering Department, University of Salento, Via per Arnesano s.n., 73100 Lecce, Italy

² DMMM, Politecnico di Bari, Viale Japigia, 182, 70124 Bari, Italy

Appl. Sci. 2017, 7(9), 945; https://doi.org/10.3390/app7090945 - 14 Sep 2017

Cited by 23 | Viewed by 6490

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 [...] Read more.

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 Science and Engineering)

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21 pages, 6465 KiB

Open AccessArticle

Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone

by Hongwu Yin^1,2

, Hongling Ma^1,2,*, Xiangsheng Chen^1,2, Xilin Shi^1,2,*

, Chunhe Yang^1,2, Maurice B. Dusseault³ and Yuhao Zhang^1,2

¹ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ Department of Earth & Environmental Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada

Appl. Sci. 2017, 7(9), 946; https://doi.org/10.3390/app7090946 - 14 Sep 2017

Cited by 18 | Viewed by 6884

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 [...] Read more.

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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15 pages, 6939 KiB

Open AccessArticle

Model-Based Design and Evaluation of a Brachiating Monkey Robot with an Active Waist

by Alex Kai-Yuan Lo

, Yu-Huan Yang^†, Tsen-Chang Lin, Chen-Wen Chu and Pei-Chun Lin^*

¹ Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

^† A.K.-Y.L. and Y.-H.Y. contributed equally to this work.

Appl. Sci. 2017, 7(9), 947; https://doi.org/10.3390/app7090947 - 14 Sep 2017

Cited by 6 | Viewed by 6477

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 [...] Read more.

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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15 pages, 2279 KiB

Open AccessArticle

On the Optimisation of Practical Wireless Indoor and Outdoor Microcells Subject to QoS Constraints

by Adeola Abraham Omorinoye and Quoc-Tuan Vien^*

School of Science and Technology, Middlesex University, The Burroughs, London NW4 4BT, UK

Appl. Sci. 2017, 7(9), 948; https://doi.org/10.3390/app7090948 - 15 Sep 2017

Cited by 5 | Viewed by 4710

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. [...] Read more.

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

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10 pages, 3835 KiB

Open AccessArticle

Stochastic Investigation of Consolidation Process in Spatially Correlated Heterogeneous Soils

by Song-Hun Chong

High Speed Railroad Systems Research Center, Korea Railroad Research Institute, 176, Cheoldo bangmulgwan-ro, Uiwang-si, Gyeonggi-do 437-757, Korea

Appl. Sci. 2017, 7(9), 949; https://doi.org/10.3390/app7090949 - 15 Sep 2017

Cited by 1 | Viewed by 4422

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. [...] Read more.

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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16 pages, 2870 KiB

Open AccessArticle

Decision Support Simulation Method for Process Improvement of Intermittent Production Systems

by Péter Tamás

Faculty of Mechanical Engineering and Informatics, Institute of Logistics, University of Miskolc, 3515 Miskolc-Egyetemváros, Hungary

Appl. Sci. 2017, 7(9), 950; https://doi.org/10.3390/app7090950 - 15 Sep 2017

Cited by 15 | Viewed by 7146

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, [...] Read more.

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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25 pages, 4657 KiB

Open AccessArticle

Practical Challenge of Shredded Documents: Clustering of Chinese Homologous Pieces

by Nan Xing^1,2,*, Jianqi Zhang¹, Furong Cao¹ and Pengfei Liu¹

¹ School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071, China

² School of Automation and Information Engineering, Xi’an University of Technology, Xi’an 710048, China

Appl. Sci. 2017, 7(9), 951; https://doi.org/10.3390/app7090951 - 15 Sep 2017

Cited by 2 | Viewed by 3911

Abstract

When recovering a shredded document that has numerous mixed pieces, the difficulty of the recovery process can be reduced by clustering, which is a method of grouping pieces that originally belonged to the same page. Restoring homologous shredded documents (pieces from different pages [...] Read more.

When recovering a shredded document that has numerous mixed pieces, the difficulty of the recovery process can be reduced by clustering, which is a method of grouping pieces that originally belonged to the same page. Restoring homologous shredded documents (pieces from different pages of the same file) is a frequent problem, and because these pieces have nearly indistinguishable visual characteristics, grouping them is extremely difficult. Clustering research has important practical significance for document recovery because homologous pieces are ubiquitous. Because of the wide usage of Chinese and the huge demand for Chinese shredded document recovery, our research focuses on Chinese homologous pieces. In this paper, we propose a method of completely clustering Chinese homologous pieces in which the distribution features of the characters in the pieces and the document layout are used to correlate adjacent pieces and cluster them in different areas of a document. The experimental results show that the proposed method has a good clustering effect on real pieces. For the dataset containing 10 page documents (a total of 462 pieces), its average accuracy is 97.19%. Full article

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10 pages, 3840 KiB

Open AccessArticle

Study on the High Temperature Interfacial Stability of Ti/Mo/Yb_0.3Co₄Sb₁₂ Thermoelectric Joints

by Ming Gu, Shengqiang Bai^*, Xugui Xia, Xiangyang Huang, Xiaoya Li, Xun Shi and Lidong Chen

State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China

Appl. Sci. 2017, 7(9), 952; https://doi.org/10.3390/app7090952 - 15 Sep 2017

Cited by 24 | Viewed by 4940

Abstract

To improve the interfacial stability at high temperatures, n-type skutterudite (SKD) thermoelectric joints with sandwich structures of Ti/Mo/Yb_0.3Co₄Sb₁₂ were successfully designed and fabricated. In this structure, Mo and Ti were introduced as the barrier layer with the [...] Read more.

To improve the interfacial stability at high temperatures, n-type skutterudite (SKD) thermoelectric joints with sandwich structures of Ti/Mo/Yb_0.3Co₄Sb₁₂ were successfully designed and fabricated. In this structure, Mo and Ti were introduced as the barrier layer with the goal of suppressing the interfacial diffusion and the buffer layer with the goal of enhancing the bonding strength, respectively. To evaluate the high temperature interfacial behavior of the Ti/Mo/Yb_0.3Co₄Sb₁₂ joints, thermal shocking between 0 °C and 600 °C and isothermal aging at a temperature range of 550 °C to 650 °C were carried out in vacuum. During the isothermal aging process, Ti penetrates across the Mo layer, and finally diffuses into the Yb_0.3Co₄Sb₁₂ matrix. By increasing the isothermal aging time, Ti continuously diffuses and reacts with the elements of Sb and Co in the matrix, consequently forming the multilayer-structured intermetallic compounds of Ti₃Sb/Ti₂Sb/TiCoSb. Diffusion kinetics was investigated and it was found that the interfacial evolution of the Ti/Mo/Yb_0.3Co₄Sb₁₂ joints was a diffusion-controlling process. During the diffusion process, the formed Mo-Ti buffer layer acts as a damper, which greatly decelerates the diffusion of Ti towards the Yb_0.3Co₄Sb₁₂ matrix at high temperatures. Meanwhile, it was found that the increase in the contact resistivity of the joints mainly derives from the inter-diffusion between Ti and Yb_0.3Co4Sb₁₂. As a result, the Ti/Mo/Yb_0.3Co₄Sb₁₂ joint demonstrates the excellent stability of the interfacial contact resistivity. Service life prediction was made based on the stability of the contact resistivity, and it was found that the Ti/Mo/Yb_0.3Co₄Sb₁₂ joint is qualified for practical applications at 550 °C. Full article

(This article belongs to the Special Issue Development and Application of Thermoelectric Power Generators, Energy Harvesters and Refrigerators)

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8 pages, 4234 KiB

Open AccessArticle

Pt-Based Nanostructures for Observing Genuine SERS Spectra of p-Aminothiophenol (PATP) Molecules

by Yinong Wang^1,†, Haofei Zhao^2,†, En Cao², Yinghui Sun², Huanyu Ye², Weihua Lin² and Rongming Wang^2,*

¹ Department of Physics, Beihang University, Beijing 100191, China

² Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(9), 953; https://doi.org/10.3390/app7090953 - 15 Sep 2017

Cited by 8 | Viewed by 5080

Abstract

By one-pot wet chemical method, Pt-based hollow nanostructures were synthesized at room temperature. Because of the highly damping optical response of the metal, these Pt-based hollow nanostructures exhibited weak thermal effects with a laser focal spot on 4-aminothiophenol (PATP) molecules limiting dimerisation. The [...] Read more.

By one-pot wet chemical method, Pt-based hollow nanostructures were synthesized at room temperature. Because of the highly damping optical response of the metal, these Pt-based hollow nanostructures exhibited weak thermal effects with a laser focal spot on 4-aminothiophenol (PATP) molecules limiting dimerisation. The isolated surface enhanced Raman scattering (SERS) spectra of PATP, in which the vibrational bands from 4,4′-dimercaptoazobenzene (DMAB) molecules are not observed, were able to be seen, and this was in good agreement with the Raman spectra of PATP powder. In addition, the concentration of PATP molecules was varied, and the illumination time was increased to 2000 s, respectively. It was found that spectra were stable with varied PATP concentrations, and the plasmon-driven chemical conversion of PATP to DMAB was still suppressed, even when the laser illumination time was increased to 2000 s. Full article

(This article belongs to the Special Issue Laser Interaction with Plasmonic Nanostructures)

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16 pages, 7403 KiB

Open AccessArticle

Computational Algorithms Underlying the Time-Based Detection of Sudden Cardiac Arrest via Electrocardiographic Markers

by Annmarie G. Raka¹, Ganesh R. Naik²

and Rifai Chai^3,*

¹ Faculty of Science, University of Technology Sydney, Ultimo, NSW 2007, Australia

² Marcs Institute for Brain, Behaviour & Development, Western Sydney University, Penrith 2750, NSW, Australia

³ School of Biomedical Engineering, Centre for Health Technologies, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW 2007, Australia

Appl. Sci. 2017, 7(9), 954; https://doi.org/10.3390/app7090954 - 16 Sep 2017

Cited by 22 | Viewed by 8530

Abstract

Early detection of sudden cardiac arrest (SCA) is critical to prevent serious repercussion such as irreversible neurological damage and death. Currently, the most effective method involves analyzing electrocardiogram (ECG) features obtained during ventricular fibrillation. In this study, data from 10 normal patients and [...] Read more.

Early detection of sudden cardiac arrest (SCA) is critical to prevent serious repercussion such as irreversible neurological damage and death. Currently, the most effective method involves analyzing electrocardiogram (ECG) features obtained during ventricular fibrillation. In this study, data from 10 normal patients and 10 SCA patients obtained from Physiobank were used to statistically compare features, such as heart rate, R-R interval duration, and heart rate variability (HRV) features from which the HRV features were then selected for classification via linear discriminant analysis (LDA) and linear and fine Gaussian support vector machines (SVM) in order to determine the ideal time-frame in which SCA can be accurately detected. The best accuracy was obtained at 2 and 8 min prior to SCA onset across all three classifiers. However, accuracy rates of 75–80% were also obtained at time-frames as early as 50 and 40 min prior to SCA onset. These results are clinically important in the field of SCA, as early detection improves overall patient survival. Full article

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22 pages, 6069 KiB

Open AccessFeature PaperArticle

CO₂ with Mechanical Subcooling vs. CO₂ Cascade Cycles for Medium Temperature Commercial Refrigeration Applications Thermodynamic Analysis

by Laura Nebot-Andrés^*

, Rodrigo Llopis

, Daniel Sánchez

, Jesús Catalán-Gil

and Ramón Cabello

Department of Mechanical Engineering and Construction, Jaume I University, Campus de Riu Sec s/n, Castellón de la Plana, E-12071, Spain

Appl. Sci. 2017, 7(9), 955; https://doi.org/10.3390/app7090955 - 16 Sep 2017

Cited by 35 | Viewed by 8268

Abstract

A recent trend to spread the use of CO₂ refrigeration cycles in warm regions of the world is to combine a CO₂ cycle with another one using a high performance refrigerant. Two alternatives are being considered: cascade and mechanical subcooling systems. [...] Read more.

A recent trend to spread the use of CO₂ refrigeration cycles in warm regions of the world is to combine a CO₂ cycle with another one using a high performance refrigerant. Two alternatives are being considered: cascade and mechanical subcooling systems. Both respond to a similar configuration of the refrigeration cycle, they being based on the use of two compressors and same number of heat exchangers. However, the compressor, heat exchanger sizes and energy performance differ a lot between them. This work, using experimental relations for CO₂ and R1234yf semi-hermetic compressors analyzes in depth both alternatives under the warm climate of Spain. In general, it was concluded that the CO₂ refrigeration solution with mechanical subcooling would cover all the conditions with high overall energy efficiency, thus it being recommended for further extension of the CO₂ refrigeration applications. Full article

(This article belongs to the Section Mechanical Engineering)

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21 pages, 7175 KiB

Open AccessFeature PaperReview

ECOAL Project—Delivering Solutions for Integrated Monitoring of Coal-Related Fires Supported on Optical Fiber Sensing Technology

by Joana Ribeiro^1,2

, Duarte Viveiros^3,4

, João Ferreira³

, Alexia Lopez-Gil⁵, Alejandro Dominguez-Lopez⁵, Hugo F. Martins⁵, Rosa Perez-Herrera⁶

, Aitor Lopez-Aldaba⁶, Lia Duarte^1,2

, Ana Pinto^6,7, Sonia Martin-Lopez⁵, Hardy Baierl⁸, Raphael Jamier⁸, Sébastien Rougier⁸, Jean-Louis Auguste⁸, Ana Cláudia Teodoro^1,2

, José Alberto Gonçalves^1,9, Oscar Esteban⁵, José Luís Santos^3,4, Philippe Roy⁹, Manuel Lopez-Amo⁶

, Miguel Gonzalez-Herraez⁵, José Manuel Baptista^3,10

and Deolinda Flores^1,2,*

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¹ Department of Geosciences, Environment and Spatial Planning, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal

² Institute of Earth Sciences, Pole of University of Porto, 4169-007 Porto, Portugal

³ Center for Applied Photonics, INESC TEC, 4169-007 Porto, Portugal

⁴ Department of Physics and Astronomy, Faculty of Science at University of Porto, 4169-007 Porto, Portugal

⁵ Departamento de Electrónica, Universidad de Alcalá, 28801 Alcalá de Henares, Spain

⁶ Department of Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra, 31006 Pamplona, Spain

⁷ Federal University of Santa Catarina, Centro de Engenharia da Mobilidade (CEM), Florianopolis 89.218-035, Brazil

⁸ CNRS, XLIM—Département Photonique-Fibre, Faculté des Sciences et Techniques, 87060 Limoges, France

⁹ Interdisciplinary Centre of Marine and Environmental Research, University of Porto, 4450-208 Matosinhos, Portugal

¹⁰ Faculdade de Ciências Exatas e da Engenharia, Universidade da Madeira, 9020-105 Funchal, Portugal

Appl. Sci. 2017, 7(9), 956; https://doi.org/10.3390/app7090956 - 16 Sep 2017

Cited by 16 | Viewed by 7602

Abstract

The combustion of coal wastes resulting from mining is of particular environmental concern, and the importance of proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of the combustion temperature and emission levels of [...] Read more.

The combustion of coal wastes resulting from mining is of particular environmental concern, and the importance of proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of the combustion temperature and emission levels of certain gases allows for the possibility of planning corrective actions to minimize their negative impact on the surroundings. Optical fiber technology is well suited to this purpose and here we describe the main attributes and results obtained from a fiber optic sensing system projected to gather data on distributed temperature and gas emissions in these harsh environments. Full article

(This article belongs to the Special Issue Distributed Optical Fiber Sensors)

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15 pages, 4026 KiB

Open AccessArticle

An On-Line Oxygen Forecasting System for Waterless Live Transportation of Flatfish Based on Feature Clustering

by Yongjun Zhang^1,2

, Chengguo Wang³, Liu Yan⁴, Daoliang Li¹ and Xiaoshuan Zhang^3,*

¹ College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China

² School of Electronic Information, Shandong Institute of Commerce and Technology, Jinan 250103, China

³ College of Engineering, Beijing Lab for Food Quality and Safety, China Agricultural University, Beijing 100083, China

⁴ School of Logistics, Beijing Wuzi University, Beijing 101149, China

Appl. Sci. 2017, 7(9), 957; https://doi.org/10.3390/app7090957 - 18 Sep 2017

Cited by 13 | Viewed by 5227

Abstract

Accurate prediction of forthcoming oxygen concentration during waterless live fish transportation plays a key role in reducing the abnormal occurrence, increasing the survival rate in delivery operations, and optimizing manufacturing costs. The most effective ambient monitoring techniques that are based on the analysis [...] Read more.

Accurate prediction of forthcoming oxygen concentration during waterless live fish transportation plays a key role in reducing the abnormal occurrence, increasing the survival rate in delivery operations, and optimizing manufacturing costs. The most effective ambient monitoring techniques that are based on the analysis of historical process data when performing forecasting operations do not fully consider current ambient influence. This is likely lead to a greater deviation in on-line oxygen level forecasting in real situations. Therefore, it is not advisable for the system to perform early warning and on-line air adjustment in delivery. In this paper, we propose a hybrid method and its implementation system that combines a gray model (GM (1, 1)) with least squares support vector machines (LSSVM) that can be used effectively as a forecasting model to perform early warning effectively according to the dynamic changes of oxygen in a closed system. For accurately forecasting of the oxygen level, the fuzzy C-means clustering (FCM) algorithm was utilized for classification according to the flatfish’s physical features—i.e., length and weight—for more pertinent training. The performance of the gray model-particle swarm optimization-least squares support vector machines (GM-PSO-LSSVM) model was compared with the traditional modeling approaches of GM (1, 1) and LSSVM by applying it to predict on-line oxygen level, and the results showed that its predictions were more accurate than those of the LSSVM and grey model. Therefore, it is a suitable and effective method for abnormal condition forecasting and timely control in the waterless live transportation of flatfish. Full article

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11 pages, 594 KiB

Open AccessArticle

Gas Sensor Design Based on a Line Locked Tunable Fiber Laser and the Dual Path Correlation Spectroscopy Method

by Everardo Vargas-Rodriguez^1,*, Ana Dinora Guzman-Chavez¹, Raja Kamarulzaman Raja-Ibrahim² and Luis Eusebio Cardoso-Lozano¹

¹ Departamento de Estudios Multidisciplinarios, División de Ingenierías, Universidad de Guanajuato, Av. Universidad s/n, Col. Yacatitas, 38940 Yuriria, Gto., Mexico

² Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru 81310, Malaysia

Appl. Sci. 2017, 7(9), 958; https://doi.org/10.3390/app7090958 - 19 Sep 2017

Cited by 5 | Viewed by 4651

Abstract

In this work a hybrid gas sensor based on a tunable fiber laser and a correlation spectroscopy technique is presented. The laser is tuned by varying the temperature of a bulk silicon wafer of 85

μ

m thickness and, once the desired wavelength [...] Read more.

In this work a hybrid gas sensor based on a tunable fiber laser and a correlation spectroscopy technique is presented. The laser is tuned by varying the temperature of a bulk silicon wafer of 85

μ

m thickness and, once the desired wavelength is reached the line, is locked by keeping fixed its temperature. According to experimental results the wafer temperature variation was in the order of 0.02 K, which induced an estimated wavelength deviation of 0.12 pm, which satisfies the high wavelength position accuracy required for gas sensing applications. Additionally, it is shown that errors due to laser intensity fluctuations can be minimized by implementing a simple dual path correlation spectroscopy stage. As a proof of the suitability of our tunable fiber laser for gas sensing applications, a C₂H₂ sensor was implemented. By using a 10 cm gas cell at atmospheric pressure, it was possible to detect concentrations from 0 to 20% with a sensitivity of 521 ppm and sub-minute time response. Moreover, the experimental measurements and simulated results have a high level of agreement. Finally, it is important to point out that, by using doped fiber with different characteristics, other wavelength emissions can be generated. Full article

(This article belongs to the Section Optics and Lasers)

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10 pages, 571 KiB

Open AccessTechnical Note

Which Method Detects Foot Strike in Rearfoot and Forefoot Runners Accurately when Using an Inertial Measurement Unit?

by Christian Mitschke^*

, Tobias Heß and Thomas L. Milani

Department of Human Locomotion, Chemnitz University of Technology, Chemnitz 09126, Germany

Appl. Sci. 2017, 7(9), 959; https://doi.org/10.3390/app7090959 - 19 Sep 2017

Cited by 15 | Viewed by 7332

Abstract

Accelerometers and gyroscopes are used to detect foot strike (FS), i.e., the moment when the foot first touches the ground. However, it is unclear whether different conditions (footwear hardness or foot strike pattern) influence the accuracy and precision of different FS detection methods [...] Read more.

Accelerometers and gyroscopes are used to detect foot strike (FS), i.e., the moment when the foot first touches the ground. However, it is unclear whether different conditions (footwear hardness or foot strike pattern) influence the accuracy and precision of different FS detection methods when using such micro-electromechanical sensors (MEMS). This study compared the accuracy of four published MEMS-based FS detection methods with each other and the gold standard (force plate) to establish the most accurate method with regard to different foot strike patterns and footwear conditions. Twenty-three recreational runners (12 rearfoot and 11 forefoot strikers) ran on a 15-m indoor track at their individual running speed in three footwear conditions (low to high hardness). MEMS and a force plate were sampled at a rate of 3750 Hz. Individual accuracy and precision of FS detection methods were found which were dependent on running styles and footwear conditions. Most of the methods were characterized by a delay which generally increased from rearfoot to forefoot strike pattern and from high to low midsole hardness. It can be concluded that only one of the four methods can accurately determine FS in a variety of conditions. Full article

(This article belongs to the Special Issue Wearable Computing and Machine Learning for Applications in Sports, Health, and Medical Engineering)

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14 pages, 3285 KiB

Open AccessArticle

Antimony Oxide-Doped 0.99Pb(Zr_0.53Ti_0.47)O₃–0.01Bi(Y_1−xSb_x)O₃ Piezoelectric Ceramics for Energy-Harvesting Applications

by Iqbal Mahmud¹, Man-Soon Yoon² and Soon-Chul Ur^2,*

¹ Department of Electrical and Electronic Engineering, Eastern University, Dhaka 1230, Bangladesh

² Department of Materials Science and Engineering/RIC-ReSEM, Korea National University of Transportation, 50 Daehagno, Chungju, Chungbuk 380-702, Korea

Appl. Sci. 2017, 7(9), 960; https://doi.org/10.3390/app7090960 - 19 Sep 2017

Cited by 5 | Viewed by 5588

Abstract

The effects of doping antimony oxides (Sb₂O₃/Sb₂O₅) on the ferroelectric/piezoelectric and energy-harvesting properties of 0.99Pb(Zr_0.53Ti_0.47)O₃–0.01BiYO₃ (PZT–BY) have been studied. The feasibility of doping Sb₂O₃ and [...] Read more.

The effects of doping antimony oxides (Sb₂O₃/Sb₂O₅) on the ferroelectric/piezoelectric and energy-harvesting properties of 0.99Pb(Zr_0.53Ti_0.47)O₃–0.01BiYO₃ (PZT–BY) have been studied. The feasibility of doping Sb₂O₃ and Sb₂O₅ into the PZT–BY ceramics has also been compared by considering factors such as sintering condition, grain size, density, and electrical properties etc. This work discusses a detailed experimental observation using Sb₂O₃, because Sb₂O₅ is relatively expensive and does not follow the stoichiometric reaction mechanism when doped in PZT–BY. The Sb₂O₃-doped specimens were well sintered by oxygen-rich sintering and reached a maximum density of 99.1% of the theoretical value. X-ray diffraction (XRD) analysis showed a complete solid solution for all the specimens. Scanning electron microscope (SEM) observation revealed that the addition of Sb₂O₃ inhibits grain growth, and exhibits a denser and finer microstructure. The 0.1 moles of Sb₂O₃-doped ceramic shows a sharp decrease in the dielectric constant (ε₃₃^T = 690), while the piezoelectric charge constant (d₃₃) and electromechanical coupling factor (k_p) maintained high values of 350 pC/N and 66.0% respectively. The relatively higher value of d₃₃ and lower ε₃₃^T of the 0.99Pb(Zr_0.53Ti_0.47)O₃–0.01Bi(Y_0.9Sb_0.1)O₃ ceramic resulted in an optimum value of piezoelectric voltage constant (g₃₃ = 57.4 × 10⁻³ Vm/N) and a high figure of merit (d₃₃ × g₃₃ = 20075 × 10⁻¹⁵ m²/N). These values are high compared to recently reported works. Therefore, Sb₂O₃-doped PZT–BY ceramic could be a promising candidate material for the future study of power-harvesting devices. Full article

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14 pages, 5024 KiB

Open AccessArticle

Application of Artificial Neural Networks to Ship Detection from X-Band Kompsat-5 Imagery

by Jeong-In Hwang¹, Sung-Ho Chae^1,2, Daeseong Kim¹ and Hyung-Sup Jung^1,*

¹ Department of Geoinformatics, University of Seoul, Seoul 02504, Korea

² Center for Environmental Assessment Monitoring, Environmental Assessment Group, Korea Environment Institute (KEI), Sejong-si 30147, Korea

Appl. Sci. 2017, 7(9), 961; https://doi.org/10.3390/app7090961 - 20 Sep 2017

Cited by 31 | Viewed by 5726

Abstract

For ship detection, X-band synthetic aperture radar (SAR) imagery provides very useful data, in that ship targets look much brighter than surrounding sea clutter due to the corner-reflection effect. However, there are many phenomena which bring out false detection in the SAR image, [...] Read more.

For ship detection, X-band synthetic aperture radar (SAR) imagery provides very useful data, in that ship targets look much brighter than surrounding sea clutter due to the corner-reflection effect. However, there are many phenomena which bring out false detection in the SAR image, such as noise of background, ghost phenomena, side-lobe effects and so on. Therefore, when ship-detection algorithms are carried out, we should consider these effects and mitigate them to acquire a better result. In this paper, we propose an efficient method to detect ship targets from X-band Kompsat-5 SAR imagery using the artificial neural network (ANN). The method produces the ship-probability map using ANN, and then detects ships from the ship-probability map by using a threshold value. For the purpose of getting an improved ship detection, we strived to produce optimal input layers used for ANN. In order to reduce phenomena related to the false detections, the non-local (NL)-means filter and median filter were utilized. The NL-means filter effectively reduced noise on SAR imagery without smoothing edges of the objects, and the median filter was used to remove ship targets in SAR imagery. Through the filtering approaches, we generated two input layers from a Kompsat-5 SAR image, and created a ship-probability map via ANN from the two input layers. When the threshold value of 0.67 was imposed on the ship-probability map, the result of ship detection from the ship-probability map was a 93.9% recall, 98.7% precision and 6.1% false alarm rate. Therefore, the proposed method was successfully applied to the ship detection from the Kompsat-5 SAR image. Full article

(This article belongs to the Special Issue Application of Artificial Neural Networks in Geoinformatics)

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