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Development of a hanging pendulum thrust stand for pulsed plasma thrusters

Acta Astronautica 2025年 234卷 368-386页

作者： Yueh-Heng Li Wai-Cheng Lien Sheng-Wen Liu Institute of Space Systems Engineering National Cheng Kung University Tainan 70101 Taiwan Department of Aeronautics and Astronautics National Cheng Kung University Tainan 70101 Taiwan International Doctoral Degree Program on Energy Engineering National Cheng Kung University Tainan 70101 Taiwan

Thrust stands are essential tools for evaluating the performance of propulsion systems, including Hall effect thrusters, ion thrusters, and pulsed plasma thrusters (PPTs). Our thrust stand supports a prototype weighing up to 0.8 kg and measures impulses from 150 to 550 μN s. It generates voltage oscillations with peaks between 5 mV and 35 mV, which, combined with NI voltage modules, minimizes weight constraints on the propulsion system while maintaining accurate measurements under low thrust-to-weight conditions. This design introduces a novel approach compared to conventional torsional thrust stands. By aligning the propulsion system's center of mass with the pendulum arm, we eliminate the need for spring torque. Instead, gravitational torque provides the necessary equivalent spring constant for damping. The eddy-current damper, featuring a copper plate, doubles as both a damping mechanism and a counterweight, allowing adjustments for different propulsion system weights. Unlike elastic pivots, this design avoids performance degradation from material fatigue or thermal effects. Challenges in the current system include non-linear spring and damping coefficients caused by PPT power cables and pulse-width errors during calibration. Future improvements will consist of cable feed-throughs to isolate vibrations without introducing unwanted coefficients. Additionally, the improvement aims to optimize the impulse generator's power supply to eliminate calibration errors caused by high-voltage pulse-width fluctuations.

关键词： Thrust stand Electric propulsion Pulsed plasma thruster Impulse measurement methods

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Key factors affecting people's willingness to participate in water resource protection in the agricultural Ba River Basin – in the highlands of Vietnam

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Journal of Water and Climate Change 2025年第4期16卷 1225-1237页

作者： Anh, Nguyen Tuan Can, Le Duy Schmalz, Britta Luu, Tran Le Doctoral Training Program in Sustainable Urban Development Vietnamese-German University Vanh Dai 4 Quarter 4Binh Duong Province Ben Cat Viet Nam Nong Lam University of Ho Chi Minh City Gia Lai Campus Gia Lai Viet Nam Department of Mechatronics and Sensor Systems Technology Vietnamese-German University Vanh Dai 4 Quarter 4 Thoi Hoa Ward Binh Duong Province Ben Cat Viet Nam Engineering Hydrology and Water Management Technical University of Darmstadt Darmstadt Germany Master Program in Water Technology Reuse and Management Vietnamese-German University Vanh Dai 4 Quarter 4 Thoi Hoa Ward Binh Duong Province Ben Cat Viet Nam

Willingness to participate (WP) in community-based management depends on various factors such as a sense of community, perceptions, beliefs, and demographic characteristics. This study first evaluates the WP of locals (n = 100) in water management in the Ba River Basin – Highlands of Vietnam, where ethnic minority groups are living and working in the agricultural sector. The multivariable linear regression model is applied to explain WP through the factors including the sense of community (SC), dependance on river water (DW), perceptions of current water resource management (PW), level of income (IN), gender (GE), education levels (ED), and place of residence (PR). The results showed that the final regression model explains 67.9% of the variation in WP levels (R2 = 0.679, p 0.05) in this model. Sense of community and perceptions greatly influence community participation. To boost willingness, periodic training and campaigns are needed. Additionally, improving legal frameworks can encourage greater community involvement in water management programs. © 2025 The Authors.

关键词： Multiple linear regression

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Variable-speed teaching–playback as real-world data augmentation for imitation learning

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Advanced Robotics 2025年

作者： Masuya, Nozomu Sato, Hiroshi Yamane, Koki Kusume, Takuya Sakaino, Sho Tsuji, Toshiaki Doctoral Program in Intelligent and Mechanical Interaction Systems Degree Programs in Systems and Information and Engineering Graduate School of Science and Technology University of Tsukuba Tsukuba Japan Master’s Program in Intelligent and Mechanical Interaction Systems Degree Programs in Systems and Information and Engineering Graduate School of Science and Technology University of Tsukuba Tsukuba Japan Department of Intelligent Interaction Technologies Institute of Systems and Information Engineering University of Tsukuba Tsukuba Japan Graduate School of Science and Engineering Saitama University Saitama Japan

Imitation learning’s inevitable reliance on human demonstrations in hard-to-simulate settings has resulted in a shortage of training data, even with a simple change in speed. Although the field of data augmentation has addressed the lack of data, conventional methods of data augmentation for robot manipulation are limited to simulation-based methods or downsampling for position control. This paper proposes a novel method of data augmentation that is applicable to force control and preserves the advantages of real-world datasets. We applied teaching–playback at variable speeds as real-world data augmentation to increase both the quantity and quality of environmental reactions at variable speeds. An experiment was conducted on bilateral control-based imitation learning using a method of imitation learning equipped with position–force control. We evaluated the effect of real-world data augmentation on two tasks, pick-and-place and wiping, at variable speeds, each from two human demonstrations at fixed speed. The results showed that generation of variable-speed movement from human demonstrations with less than 10% variety of durations is feasible, and improved success rate and accuracy along the duration/frequency command by gathering environmental reactions at variable speeds, rather than simply altering speeds of gathered data. © 2025 Informa UK Limited, trading as Taylor & Francis Group and The Robotics Society of Japan.

关键词： Demonstrations

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An Integration of QFD and Fuzzy-AHP approach in Hospital Services, case study: a Hospital in Iran 5

An Integration of QFD and Fuzzy-AHP approach in Hospital Ser...

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5th International Conference on Quality engineering and Management: A Better World with Quality! Quality in the Digital Transformation, ICQEM 2022

作者： Hariri, A. Domingues, J.P.T. Sampaio, P. Doctoral Program in Advanced Engineering Systems for Industry ALGORITMI Research Centre University of Minho Braga Portugal

ISBN: (纸本)9789895491117

Purpose This paper shows a development of an integrated model to identify the customer needs and select the best solution to optimize the quality of healthcare systems, namely at hospitals. Design/methodology/approach After determining the patient's requirements by data gathering from experts and patients, a questionnaire was prepared to implement the Fuzzy Analytic Hierarchy Process (FAHP) method. Afterward, the requirement's weight has determined by the patients. Finally, the most important technical requirements were achieved applying the 3-phases Quality Function Deployment (QFD) model. Findings The results show that by adapting the FAHP on ideas of the patients and hospital's experts to determine the weights of patients' requirements, led to have more flotation in FAHP questionnaires in the hospital services. In this domain, adopting the decision-making tools help more precise ranking of patients' requirements. Originality/value Since high-quality urgent services are vital to the protection of human life, it is significant to precisely rank the patient’s requirements by novel methodologies. By the implementation of an integrated model using FAHP and QFD, we were able to show the improvement of the quality of an hospital in Iran. After precisely ranking the patient requirements, "increasing human resource" and "establishing requirements and instructions in initial measures and reducing medication errors", are obtained as the most important technical requirements. © 2022 Universidade do Minho. All rights reserved.

关键词： FAHP Hospital Services House of Quality (HOQ) QFD Voice of Customer

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Grid environment for computational astrophysics driven by GRAPE-6 with HMCS-G and OmniRPC

Grid environment for computational astrophysics driven by GR...

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19th IEEE International Parallel and Distributed Processing Symposium, IPDPS 2005

作者： Boku, Taisuke Onuma, Kenji Sato, Mitsuhisa Nakajima, Yoshihiro Takahashi, Daisuke Graduate School of Systems and Information Engineering University of Tsukuba Center for Computational Sciences University of Tsukuba Doctoral Program of Systems and Information Engineering University of Tsukuba

ISBN: (纸本)0769523129

In computational astrophysics, the effect of gravity is essential even with very heavy computation of O(N2) for N particles. Several special purpose machines have been implemented as gravity engine to handle this problem extremely fast, however there are few sites in the world to operate such systems. We have developed a grid environment to access such a system based on grid-RFC, named HMCS-G. Using HMCS-G, a multi-physical computational astrophysics simulation can be performed with the combination of a PC-cluster and the gravity engine GRAPE-6. In typical size of problems for galaxy formation, however, the computation power of PC-cluster is much weaker than that of GRAPE-6, and we need multiple sets of PC-clusters to share the power of GRAPE-6 on grid environment. We have developed such a system using OmniRPC, a grid-enabled RPC system. In this system, OmniRPC are used both to distribute jobs for parameter search on multiple PC-clusters and to access GRAPE-6 server from these clusters. We performed an actual problem to search several formations of galaxy on this system, and confirmed such a solution is useful for wide variety of computational astrophysics research.

关键词： Distributed computer systems

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Predicting Solvability and Difficulty of Sokoban Puzzles 43

Predicting Solvability and Difficulty of Sokoban Puzzles

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43rd International Conference of the Chilean Computer Science Society, SCCC 2024

作者： Schaa, Hans Del Solar-Zavala, Jose A. Barriga, Nicolas A. Universidad de Talca Doctoral Program in Engineering Systems Curicó Chile Universidad de Talca Faculty of Engineering Talca Chile

ISBN: (纸本)9798331527891

Knowing if a Sokoban level has a solution requires a high investment of computational resources. This also happens when estimating difficulty;heuristics may not be precise, only work for simplified cases, be discontinuous and take much computing time. The calculation of high-fidelity heuristics is expensive and the performance of optimization systems is reduced by the time they take to deliver the result. In this article, two Convolutional Neural Networks (CNN) are implemented, a classifier of resolvable Sokoban boards and a regressor that predicts the number of pushes necessary to solve them. These obtained an accuracy of 79 % and MAE of 28, respectively. Trained models are useful in systems that do not require optimality, but rather guidance within the search space that balances time and quality. These networks can be used as surrogate methods, replacing high-fidelity heuristics that take too long. © 2024 IEEE.

关键词： Convolutional neural networks

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Using Entropy for Modeling Difficulty in the Asteroid Escape Sliding Puzzle

Using Entropy for Modeling Difficulty in the Asteroid Escape...

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2023 IEEE CHILEAN Conference on Electrical, Electronics engineering, Information and Communication Technologies, ChileCon 2023

作者： Del Solar-Zavala, Jose A. Schaa, Hans Barriga, Nicolas A. Doctoral Program in Engineering Systems Universidad de Talca Curicó Chile Universidad de Talca Faculty of Engineering Talca Chile

ISBN: (纸本)9798350369533

Developing a standarized metric for difficulty that can be applied to a large number of puzzles is not trivial. This does not come as a surprise because of the subjective factors involved in defining difficulty. However, studies that address the design and application of metrics that can be applied to multiple games are still important, because they can still be used to increase the quality of content generated by automated agents. We take a look at applying information entropy concepts in the game Asteroid Escape and compare the results with other metrics to assess difficulty used in games of similar characteristics. This approach is largely based on future work proposal from a previous study done on The Witness puzzles that yielded positive results on using an automatic method to assess the difficulty of user rated puzzles. This study also includes a modification of BFS and A∗ capable of finding every shortest solution. From the implementation, it is possible to look at contradicting results with the literature, where basic metrics had a better result correlating with an official definition of difficulty from the game designers. The impact expected from this study is to propose an update to the the corpus of puzzle games where the uncertainty metric for difficulty has been applied. As having an accurate assessment of difficulty can open the doors to other studies, such as improving the quality of the output from procedural content generation methods in games or propose an automated method of difficulty adjustment based on this metric. © 2023 IEEE.

关键词： Asteroids

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Evaluating Standard Search Enhancements Performance in Zen Puzzle Garden

Evaluating Standard Search Enhancements Performance in Zen P...

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2023 IEEE CHILEAN Conference on Electrical, Electronics engineering, Information and Communication Technologies, ChileCon 2023

作者： Schaa, Hans Del Solar-Zavala, Jose A. Barriga, Nicolas A. Doctoral Program in Engineering Systems Universidad de Talca Curico Chile Universidad de Talca Faculty of Engineering Talca Chile

ISBN: (纸本)9798350369533

Sokoban-type puzzles and their variants involve complex planning and decision-making challenges in wide and deep search spaces. Such scenarios are interesting for testing path-planning algorithms. This document uses A ∗ and IDA ∗ (Iterative Deepening A *) algorithms to solve Zen Puzzle Garden game boards;a Sokoban-type puzzle where you need rake the sandy area completely. The algorithms are evaluated in terms of speed and node expansion in moderately complex boards. Additionally, we implement three improvements: transposition tables, move ordering, and deadlock tables. The results show that IDA ∗ with the three proposed improvements is on average faster than A *. Although its strength is its low memory usage, it can be seen that it is very competitive versus A ∗ in terms of time usage. Transposition tables and deadlocks tables reduce by 500 times the number of nodes expanded by the IDA ∗ without improvements. On the other hand, the ordering of nodes is not very effective for some boards, which causes a worse performance of the IDA ∗ algorithm, giving rise to greater exploration in boards that do not lead to the solution. Studying these algorithms can be beneficial in the field of path-finding for Sokoban-type game domains or solver-based procedural content generators. © 2023 IEEE.

关键词： Decision making

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Preparing future entrepreneurs: reflections about the COVID-19 impacts on the entrepreneurial potential of Brazilian students

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Journal of Work-Applied Management 2021年第2期13卷 277-283页

作者： Cazeri, Gustavo T. Anholon, Rosley Rampasso, Izabela Simon Quelhas, Osvaldo L.G. Leal Filho, Walter School of Mechanical Engineering State University of Campinas Campinas Brazil PNPD/CAPES Program Doctoral Program in Sustainable Management Systems Federal Fluminense University Niterói Brazil Master Program in Management Systems Doctoral Program in Sustainable Management Systems Federal Fluminense University Niterói Brazil Faculty of Life Sciences Hamburg University of Applied Sciences Hamburg Germany

Purpose: This viewpoint aims to present reflections on the coronavirus disease 2019 (COVID-19) pandemic scenario and the entrepreneurial potential of Brazilian students. Guidelines are proposed to support debates in the academic environment and better prepare future entrepreneurs to the labour market. Design/methodology/approach: Since this is a viewpoint article, some statements presented here are characterised by the authors' opinions. However, for a better foundation, bibliographic research related to the theme was carried out. Findings: In the authors' point of view, the COVID-19 pandemic scenario may negatively influence the decisions of Brazilian students that are characterised as potential future entrepreneurs. Educators can use the guidelines presented here to conduct debates with students in order to clarify aspects related to profile, behaviour and other issues. Originality/value: By understanding better entrepreneurial aspects in the COVID-19 pandemic scenario, Brazilian students can make better decisions. This initiative will contribute to future success in the Brazilian entrepreneurial activity and national economy. © 2021, Gustavo T. Cazeri, Rosley Anholon, Izabela Simon Rampasso, Osvaldo L.G. Quelhas and Walter Leal Filho.

关键词： Brazilian higher education institutions COVID-19 pandemic Entrepreneurial activity Labour market

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Dramatic effect of extreme rainfall event and storm on microbial community dynamics in a subtropical coastal region

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Science of the Total Environment 2025年 964卷 178560页

作者： Olivia, Madeline Annabel, Clara Natalie Chen, Patrichka Wei-Yi Hsieh, Chih-hao Chang, Feng-Hsun Ho, Pei-Chi Chien, Chia-Te Chao, Chien-Fu Mukhanov, Vladimir Tsai, An-Yi Institute of Marine Environment and Ecology National Taiwan Ocean University Keelung202-24 Taiwan Doctoral Degree Program in Ocean Resource and Environmental Changes National Taiwan Ocean University Keelung202-24 Taiwan Center of Excellence for the Oceans National Taiwan Ocean University Keelung202-24 Taiwan Institute of Oceanography National Taiwan University Taipei10617 Taiwan Department of Bioenvironmental Systems Engineering National Taiwan University Taipei10617 Taiwan A.O. Kovalevsky Institute of Biology of the Southern Seas Russian Academy of Sciences Sevastopol299011 Russia Laboratory of Marine Ecosystems Institute for Advanced Research Sevastopol State University Sevastopol299053 Russia

Extreme weather events, such as heavy rainfall and typhoons, are becoming more frequent due to climate change and can significantly impact coastal microbial communities. This study examines the short-term alterations in microbial food webs—viruses, bacteria, picophytoplankton, nanoflagellates, ciliates, and diatom—following Typhoon Krathon in Taiwan's coastal waters in October 2024. Daily in situ sampling revealed a significant post-typhoon increased in viral, nanoflagellate, and Synechococcus spp. abundance. Furthermore, viral, Synechococcus spp., and nanoflagellate abundance increased by approximately 4.2 to 12.8-fold, 33.3 to 160 fold, and 0.5 to 9.4 fold in response to these weather events, compared to periods pre-typhoon, respectively. Modified dilution experiments showed that, before the typhoon, nanoflagellate grazing was the major cause of bacterial mortality, while viral lysis was the main cause of Synechococcus spp. mortality. Post-typhoon, there was a notable shift, with nanoflagellate grazing increasing mortality rates of bacteria and Synechococcus spp., suggesting that grazing became the dominant top-down control mechanism after the disturbance. Our findings suggest that extreme weather events shift microbial mortality dynamics, increasing the role of grazing in controlling microbial populations, with potential implications for carbon cycling in coastal ecosystems. © 2025 Elsevier B.V.

关键词： Tropical cyclone

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