Applied Sciences

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EISSN : 20763417
Current Publisher: MDPI (10.3390)
Total articles ≅ 14,874
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Ryoko Nojima, Natsuko Sugie, Akira Taguchi, Jun Kokubo
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134552

Abstract:
The main lobby of Hotel Okura Tokyo has a good reputation for its sound environment, which affects the conversations of its users. We assumed that the lobby’s reputation was related to its speech intelligibility. In this study, first, the sound during hotel operations was measured to see if there was a difference in the sound environment between the lobby and the entrance hall. As a result, we clarified that the difference in noise levels affected by the degree of crowdedness of the room was smaller in the lobby than in the other rooms. Subsequently, the indoor noise and speech intelligibility were measured to clarify the correspondence of intelligibility with the lobby’s reputation. As a result, the indoor noise was found to be at a level suitable for hotel lobbies and the intelligibility was good. A comprehensive evaluation that included the results of other acoustical surveys revealed that the lobby of Okura is a space that is suitable for conversations, corresponding to the opinions of users.
Jaroslav Odrobiňák, Matúš Farbák, Jakub Chromčák, Ján Kortiš, Jozef Gocál
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134530

Abstract:
In order to analyse the buckling behaviour of existing bow-string arch bridges, it is necessary to deal with the imperfections that influence the global stability of their superstructures. Direct quantification of the material imperfections represents an extremely difficult task for this type of structure. On the other hand, the geometrical imperfections can be measured in more detail by using special scanners or high-accuracy surveying instruments. This contribution represents a beginning part of the research activities focusing on the real values of geometric imperfections of existing steel arch bridges using three-dimensional (3D) scanning. The possibility of using these data for further theoretical and numerical analysis based on the finite element method (FEM) and for further creating the building information modelling (BIM) of the bridges is proposed. When verifying the stability of bow-string arch bridges, much higher attention has to be paid to the out-of-plane stability of the arches. The numerical models of an existing bridge superstructure were developed to execute a nonlinear analysis with geometrical imperfections included. Both the theoretical and actual imperfections obtained by 3D scanning were taken into account. The obtained data, their comparison and the applicability of the presented method are finally discussed.
M. Scalera, Enrica Gentile, Paola Plantamura, Giovanni DiMauro
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134531

Abstract:
For some years now there has been a growing use of cloud computing technologies in education. This paper reports a systematic mapping study (SMS) about the interest in the innovation of methods, techniques, and tools applied to teaching activities based on the use of cloud computing. The SMS presented here was designed using a consolidated, reliable, rigorous methodology and implemented in a replicable and verifiable manner. The process adopted is based on the selection of papers in accredited online digital libraries. This research made it possible to identify and analyze the empirical evidence in relation to the use of cloud computing in education with the aim of identifying both the main topics currently shared by researchers and the less explored areas to be integrated into a research agenda. The results show that only 17% of the 940 works examined report empirical research about the innovation introduced in educational environments of all levels and degrees by the cloud. The results also show that the type of method most widely used was that of feedback. The areas that have attracted the most interest from the research community are those of the new learning environment, collaboration platforms, and virtual laboratories. However, since the same areas are less supported by empirical research than others, we believe that these should be more closely monitored by the scientific community.
Hussain Shareef, Eslam Al-Hassan, Reza Sirjani
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134533

Abstract:
Despite the increasing utilization of renewable energy resources, such as solar and wind energy, most residential buildings still rely on conventional energy supply by public utility services. Such utility services often use time-of-use energy pricing, which compels residential consumers to reduce their energy usage. This paper presents a wireless home energy management (HEM) system that enables the automatic control of home appliances to reduce energy consumption to assist such energy users. The system consists of multiple smart sockets that measure the energy that is consumed by the connected appliances and are capable of implementing on/off commands. The system includes other support components for supplying data to a central controller, which utilizes a rule-based HEM algorithm. The control rules were designed, such that the lifestyle of the user would be preserved while the energy consumption and daily energy cost were reduced. The experimental results showed that the central controller could effectively receive data and control multiple devices. The system was also found to afford significant reductions of 23.5 kWh and $2.898 in the total daily energy consumption and bill of the considered household setup, respectively. The proposed HEM system promises to be particularly useful for households with a high daily energy consumption.
Yuan Zhu, Ke Lu, Xiezu Su, Gang Yang, Ke Lu, Zhihong Wu
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134539

Abstract:
The modeling of conduction and switching losses for insulated gate bipolar transistors (IGBTs) and free-wheeling diodes (FWDs) in automobile applications is becoming increasingly important, especially for the improvement of the system efficiency and the reliability prediction. The traditional modeling of conduction and switching losses based on the space vector pulse width modulation (SVPWM) is not applicable in practice due to the complex curve-fitting and the computation demands. In this paper, a simple and practical losses model for IGBTs and FWDs is proposed based on the SVPWM algorithm. Firstly, the traditional power losses model is introduced briefly. Then, the piecewise linear switching losses model and the conduction losses model based on the equivalent three-order harmonic model of the duty cycle are proposed. The comparison of experimental results between the traditional model and the proposed model is presented in the experiment validation. Furthermore, the power analyzer is adopted to measure the inverter losses, and the chips losses are further validated when other extra losses are considered. The proposed model shows good modeling accuracy with the large benefit of smaller measurement and lower computation requirements.
Tayyebeh Mesbahzadeh, Ali Salajeghe, Farshad Soleimani Sardoo, Gholamreza Zehtabian, Abbas Ranjbar, Mario Marcello Miglietta, Sara Karami, Nir Y. Krakauer
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134536

Abstract:
Dust and sand storms are among the major threats to central Iran. These phenomena pose irreparable risks to natural ecosystems and human societies, including effects on health. In this study, the spatial and temporal pattern of vertical dust flux (VDF) was used to identify dust sources as well as areas with high potential for dust generation. To simulate VDF, two intense dust storms, from 21 February 2015 and 14 February 2018, were selected using synoptic data and Moderate Resolution Imaging Spectroradiometer (MODIS) images. These dust storms were identified as responsible for a reduction of horizontal visibility to less than 1,000 m, using remote sensing tools and Ackerman Dust Index. MODIS images show that these two storms covered most of Central Plateau of Iran. The Weather Research and Forecasting model with chemistry (WRF-Chem) was used to simulate the storms, with either the Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) or Air Force Weather Agency (AFWA) scheme to calculate VDF. Modeled vertical dust fluxes in both events indicate that the Arabian deserts in Saudi Arabia and in southwestern Iran can be identified as main sources of the dust in the central Iranian plateau. The other source of dust is the Hirmand Basin, located in the country of Afghanistan and in the southeast of Iran. The results of VDF simulations indicate that central southeast Iran could be the main dust source of internal origin. Additionally, over seasonal wetlands in Iran, the amount of VDF was simulated to be sometimes over 4000 μg/(m2s), an indication that these areas are sensitive to wind erosion in dry conditions and can be a source of dust. The WRF-Chem results were compared with the horizontal visibility measured in synoptic stations in the area. The results showed that the coefficients of determination of GOCART results with the measured horizontal visibility on 21 February 2015 and 14 February 2018 were 0.72 and 0.76, respectively, while the coefficient values from the simulations with AFWA scheme on 21 February 2015 and 14 February 2018 with the measured horizontal visibility were lower, 0.44 and 0.50, respectively. Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA2) re-analysis data also showed timing of peak dust levels consistent with the GOCART scheme.
Fernando Fradique Duarte, Nuno Lau, Artur Pereira, Luis Paulo Reis
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134529

Abstract:
In general, games pose interesting and complex problems for the implementation of intelligent agents and are a popular domain in the study of artificial intelligence. In fact, games have been at the center of some of the most well-known achievements in artificial intelligence. From classical board games such as chess, checkers, backgammon and Go, to video games such as Dota 2 and StarCraft II, artificial intelligence research has devised computer programs that can play at the level of a human master and even at a human world champion level. Planning and learning, two well-known and successful paradigms of artificial intelligence, have greatly contributed to these achievements. Although representing distinct approaches, planning and learning try to solve similar problems and share some similarities. They can even complement each other. This has led to research on methodologies to combine the strengths of both approaches to derive better solutions. This paper presents a survey of the multiple methodologies that have been proposed to integrate planning and learning in the context of games. In order to provide a richer contextualization, the paper also presents learning and planning techniques commonly used in games, both in terms of their theoretical foundations and applications.
Edson L. Meyer, Julian C. Nwodo
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134534

Abstract:
This paper presents the design of an autonomous dynamic adaptability system (ADAS) for maintaining the irradiance levels of a steady-state xenon arc lamp solar simulator (SS). The solar simulator is used to carry out indoor testing and accelerated age tests on photovoltaic (PV) cells at the Fort Hare Institute of Technology (FHIT). The ADAS was designed primarily for two reasons: Firstly, to maintain a set irradiance level, irrespective of external effects which may cause unintended irradiance drift or fluctuations, while carrying out indoor tests. Secondly, to achieve the solar simulator set point quicker, thus reducing temperature build up on the target area. At a cold start, the SS runs at 20% of its rated current (145 A). At 20% of 145 A, the simulator gave an irradiance of 145.97 Wm−2 with a non-uniformity of 1.02%, and a cell surface temperature of 24.9 °C. At 50%, the simulator produced irradiance of 501.30 Wm−2, with a non-uniformity of 1.53% and a cell surface temperature of 25.0 °C. The irradiance of 1000 Wm−2, with a non-uniformity of 3.26% and a cell surface temperature of 25.9 °C, was achieved at 90% of the rated current. From the results obtained, the ADAS demonstrates that it can reliably operate the SS with very minimal human–machine interaction. Through the autonomous dynamic adaptability, set irradiance levels are maintained in a steady-state solar simulator once the user supplies operational set points via the supervisory control and data acquisition (SCADA) interface.
Min-Hsien Wang, Ke-Chou Chen, Min-Hao Hung, Chi-Yao Chang, Chin-Shan Ho, Chun-Hao Chang, Kuo-Chuan Lin
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134535

Abstract:
In volleyball matches, there are three minute intervals between sets. Therefore, the improvement of the muscle output ratio is one of the most import foundational physical elements for the players. The purpose of this study was to investigate the effects of plyometric training on the changes in electrical signals in the lower limb muscles of male college volleyball players during continuous blocking and to examine the benefits of plyometric training on blocking agility and maximum vertical jump height. In this study, twenty elite male college volleyball players were recruited and divided into a plyometric training group (PTG) and a control group (CG). The wireless electromyography was used for data acquisition, and the electrodes were applied to the left and right rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius. The median frequency was used as the measurement of the electromyographic signals during the jumping blocks. This study used covariate analysis methods, with previously measured results used as covariates to perform a two-way analysis of covariance for the independent samples. Based on the results of this study, after 6 weeks of training, the median frequency of the rectus femoris (2.13% to 4.75% improved) and that of the tibialis anterior muscles (4.14% to 7.71% improved) were significantly lower in the PTG than in the CG. Additionally, the blocking agility increased by 6.26% and the maximum vertical jump height increased by 3.33% in the PTG compared to the CG. The findings provide important insights on the neuromuscular status for volleyball players during continuous blocking jumps. Six weeks of appropriate plyometric training can facilitate the performance of volleyball players.
Mohammed Mudassir, Faris Tarlochan, Mahmoud Ashraf Mansour
Published: 30 June 2020
by MDPI
Applied Sciences, Volume 10; doi:10.3390/app10134532

Abstract:
This paper discusses the potential of using lightweight nature-inspired cellular structured designs as energy absorbers in crashworthiness applications for electric vehicles (EV). As EVs are becoming popular with their increased battery capacity, these lightweight cellular structures have regained research interest as they may increase mileage by reducing vehicle mass in addition to protecting the battery during collisions. In this paper, a novel lightweight cellular structure for EV battery protection and crashworthiness is designed and simulated. In designing the cellular structure, four different ways of applying the shell thickness have been considered that affects the collapse behavior and the crashworthiness. A numerical study was conducted on 45 samples with varying length, shell thicknesses, and thickness application methods. Four types of shell thickness application methods were investigated: Uniform thickness, strut-wall thickness, gradient thickness, and alternate thickness. Force-displacement curves, energy absorption, specific energy absorption, and collapse behaviors are some of the metrics used for evaluating the crashworthiness of the structures. Shell thickness is found to affect both the collapse behavior and energy absorption capabilities. Energy absorption results are similar to other studies on designed cellular structures. The highest performing cellular structure is reported to have a specific energy absorption of 35kJ/kg, which is comparable to cellular structures reported in the literature.
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