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Optical conductivity of the topologically nontrivial MXenes Mo2HfC2O2 and W2HfC2O2: First-principles calculation and effective model analysis

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Physical Review B 2025年第3期111卷 035422-035422页

作者： Tetsuro Habe Department of Mechanical and Electrical Systems Engineering Kyoto University of Advanced Science Kyoto 615-8577 Japan

The optical conductivity and the relevant electronic excitation processes are investigated in topologically nontrivial MXenes Mo2HfC2O2 and W2HfC2O2 utilizing first-principles calculation and effective model analysis. The numerical calculation based on the first-principles band structure reveals the presence of several characteristic features in the spectrum of optical conductivity as a function of photon energy. The drastic dependence on the photon polarization angle is also presented in terms of apparent features. In this paper, an effective model is also generated referring to the crystal symmetries and applied to reveal the microscopic origin of the characteristics. Then, it is shown that some features are strongly related to parity inversion between the conduction and valence bands, the key signature in electronic structures of topologically nontrivial insulators.

关键词： Optical conductivity

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Current Vector Control of AC Servo Motor Considering Output Delay of PWM Inverter

Current Vector Control of AC Servo Motor Considering Output ...

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18th IEEE International Conference on advanced Motion Control, AMC 2024

作者： Shimamoto, Haruta Yoshioka, Takashi Urushihara, Shiro National Institute of Technology Kagawa College Advanced Course in Industrial and Systems Engineering Takamatsu Japan National Institute of Technology Kagawa College Dept. of Electrical and Computer Engineering Takamatsu Japan

ISBN: (纸本)9798350342819

In this paper, to expand a control bandwidth of AC servo motor, a new current vector control considering an output delay of PWM Inverter is proposed. The proposed current control is a I-P control with an additional feedback gain, which is based on an extended state feedback consisted from a d-q motor model, the output delay of PWM inverter and an integrator of ACR. In addition, the proposed method is easy to implement to the existing AC servo system. The effectiveness of proposed method is validated in a computer simulation and an experiments using a 3.7 kW class motor test bench. In the condition that a cut-off frequency of ACR is close to a carrier frequency, the simulation results show that the proposed method dramatically improves the current response at the higher cut-off frequency. Moreover, the experimental results show that the proposed method dramatically improves the current response at each operating point. From the results, the proposed method is effective to the expand the bandwidth of AC servo motor. © 2024 IEEE.

关键词： Electric current control

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Human Assistive Rehabilitation System for Lower-limb using Exoskeleton

Human Assistive Rehabilitation System for Lower-limb using E...

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2023 International Conference on Consumer Electronics - Taiwan, ICCE-Taiwan 2023

作者： Kawai, Yasunori Miyazaki, Takato Miyoshi, Takanori National Institute of Technology Ishikawa College Department of Electrical Engineering Ishikawa Japan National Institute of Technology Ishikawa College Advanced Engineering Course Electronic and Mechanical Engineering Course Ishikawa Japan Nagaoka University of Technology Department of System Safety Niigata Japan

ISBN: (纸本)9798350324174

This paper considers a human assistive system of the rehabilitation for lower-limb using the exoskeleton. When the patient feels the fatigue in the rehabilitation, the power assist is needed to continue and to stop safety. First, the proposed power assist equipment using exoskeleton is indicated. The DC motor, the torsion spring, worm wheel, worm gear are used. Next, the control system using PI controller is proposed. The encoder attached to the knee joint is used as the reference value and the encoder attached to the motor is controlled by the motor. Finally, an experiment of repeated flexion and extension of the knee joint is conducted. It is verified that the motor can be controlled to be same angle of the knee angle. Therefore, the power assist by the exoskeleton is useful for the rehabilitation. © 2023 IEEE.

关键词： DC motors

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Neural Network Trained Cold-plate Models for Modular Converter Exploration

Neural Network Trained Cold-plate Models for Modular Convert...

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2024 IEEE Energy Conversion Congress and Exposition, ECCE 2024

作者： Shabani, Hamed Cuzner, Robert M. Ordonez, Juan Marques, Crístofer Hood University of Wisconsin - Milwaukee Center for Sustainable Electrical Energy Systems Department of Electrical and Computer Engineering MilwaukeeWI United States FAMU-FSU College of Engineering Florida State University Center for Advanced Power Systems Department of Mechanical Engineering TallahasseeFL United States RS Rio Grande Brazil FAMU-FSU College of Engineering Center for Advanced Power Systems TallahasseeFL United States

ISBN: (纸本)9798350376067

Designing power electronics for medium voltage (MV) and applications, such as the Modular Multilevel Converter (MMC) MVac-MVdc converter for Multi-Terminal (MT) MVdc systems, requires a multidisciplinary approach to optimize a highly intricate system. One of the main challenges in this field is exploring various MMC implementations and evaluating them through appropriate metrics to determine the most effective approach. To address this challenge, this paper introduces a Virtual Prototyping Process (VPP) for Power Electronic Building Block (PEBB) based systems that leverages neural network-trained coldplate surrogate models. These coldplate surrogate model is useful in managing the complexity of a single thermal interface point connected to multiple coldplate-cooled elements within an MMC Sub-Module Drawer (SMD) to a system-level thermal management system. This approach enables the correlation of the intrinsic power capability of point of source to point of load Power Trains as a function of coolant approach and thermal management system capability to facilitate solutuion space exploration. This exploration is conducted in an evolutionary environment (within the VPP) that balances competing objectives like power density, efficiency, specific power and specific cost. The shipboard Integrated Power and Energy System (IPES) application is used as a use-case example. © 2024 IEEE.

关键词： Benchmarking

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Non-contact Magnetic Suspension for Edge of Flexible Steel Plate: Experimental Consideration on Stable Levitation 27

Non-contact Magnetic Suspension for Edge of Flexible Steel P...

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27th International Conference on electrical Machines and systems, ICEMS 2024

作者： Kawashima, Kazuma Endo, Ayato Kuroda, Jumpei Uchino, Daigo Ogawa, Kazuki Ikeda, Keigo Kato, Taro Narita, Takayoshi Kato, Hideaki Fukuoka Institute of Technology Course of Electrical Engineering Fukuoka Japan Fukuoka Institute of Technology Department of Electrical Engineering Fukuoka Japan Tokai University Course of Science and Technology Kanagawa Hiratsuka Japan National Institute of Technology Numazu College Department of Mechanical Engineering Shizuoka Numazu Japan Aichi University of Technology Department of Electronic Robot Engineering Aichi Gamagori Japan Hokkaido University of Science Department of Mechanical Engineering Hokkaido Sapporo Japan Tokyo University of Technology Department of Mechanical Engineering Hachioji Tokyo Japan Tokai University Department of Mechanical Systems Engineering Kanagawa Hiratsuka Japan

ISBN: (纸本)9784886864406

Flexible steel plates are widely used in various industrial fields, such as car bodies and reinforcement materials for housing. Currently, rollers are mainly used for contact conveyance in plants where flexible steel plates are used, but this conveyance method causes deterioration of the quality of the steel plate surface due to contact between the plate and the rollers. To solve this problem, a non-contact gripping and transfer method has been proposed that uses the attractive force of electromagnets. We have conducted experiments using a magnetic levitation method in which electromagnets are placed only at the long edges of flexible steel plates to study the steady current levitating through the electromagnets and the levitation characteristics when the controller is changed. © 2024 The Institute of electrical Engineers of Japan.

关键词： Magnetic levitation

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Non-Contact Hanging for Flexible Steel Plate by Magnetic Levitation: Investigation on Levitating Characteristics in Stationary State 27

Non-Contact Hanging for Flexible Steel Plate by Magnetic Lev...

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27th International Conference on electrical Machines and systems, ICEMS 2024

作者： Itoyama, Rintaro Endo, Ayato Kuroda, Jumpei Uchino, Daigo Ogawa, Kazuki Ikeda, Keigo Kato, Taro Narita, Takayoshi Kato, Hideaki Fukuoka Institute of Technology Course of Electrical Engineering Fukuoka Japan Fukuoka Institute of Technology Department of Electrical Engineering Fukuoka Japan Tokai University Course of Science and Technology Kanagawa Hiratsuka Japan National Institute of Technology Numazu College Department of Mechanical Engineering Shizuoka Numazu Japan Aichi University of Technology Department of Electronic Robot Engineering Aichi Gamagori Japan Hokkaido University of Science Department of Mechanical Engineering Hokkaido Sapporo Japan Tokyo University of Technology Department of Mechanical Engineering Hachioji Tokyo Japan Tokai University Department of Mechanical Systems Engineering Kanagawa Hiratsuka Japan

ISBN: (纸本)9784886864406

In the manufacturing process of flexible steel plates, for which high quality is required, contact between rollers and flexible steel plates deteriorates the surface quality. Therefore, non-contact gripping and transport by magnetic levitating has been proposed. In conventional magnetic levitation systems, deflection of a flexible steel plate occurs during levitating, causing the flexible steel plate to fall. Therefore, the authors proposed a system that suppresses deflection of a flexible steel plate better than conventional systems. In a previous study, it was found that the levitating position changes with the magnitude of the current input the electromagnet. In this report, the levitating characteristics of magnetic levitation system gripping one-edge of a flexible steel plate under a vertical disturbance input are considered. As a result, it was clarified that the levitating stability of the magnetic levitation system is not affected by the input of vertical disturbance. © 2024 The Institute of electrical Engineers of Japan.

关键词： Magnetic levitation

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Supernumerary Robotic Limbs to Augment Astronauts Performing Post-Fall Recoveries during Partial-Gravity Spacewalks

Supernumerary Robotic Limbs to Augment Astronauts Performing...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Ballesteros, Erik Carpenter, Kalind Asada, H. Harry Department of Mechanical Engineering Massachusetts Institute of Technology Course 2 CambridgeMA02139 United States Advanced Robotics Systems Group 347Z NASA Jet Propulsion Laboratory PasadenaCA91011 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

This paper investigates the effectiveness of a type of wearable robot, known as Supernumerary Robotic Limbs (SuperLimbs) in assisting an astronaut performing partial-gravity ExtraVehicular Activities (EVAs). SuperLimbs can directly address a key technology gap identified by NASA concerning that of incapacitated crew rescue devices during partial-gravity EVAs. To contextualize SuperLimbs in human spaceflight application, we start by reviewing other forms of wearable robotics technologies and perform a qualitative comparison with SuperLimbs. From there, we present a suite of operational modes that SuperLimbs is capable of delivering in a suited partial-gravity EVA. Within the operational mode suite, we selected the most urgent use-case: that of performing a post-fall recovery, and reviewed the results from a pilot-human study. To validate the effectiveness of SuperLimbs in providing the necessary assistive forces needed for a post-fall recovery, a series of validation experiments was performed with a prototype SuperLimbs system. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： NASA

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Research on workflow recognition for liver rupture repair surgery

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Mathematical Biosciences and engineering 2024年第2期21卷 1844-1856页

作者： Men, Yutao Zhao, Zixian Chen, Wei Wu, Hang Zhang, Guang Luo, Feng Yu, Ming Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China Medical Support Technology Research Department Systems Engineering Institute Academy of Military Sciences People’s Liberation Army Tianjin300161 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China

Liver rupture repair surgery serves as one tool to treat liver rupture, especially beneficial for cases of mild liver rupture hemorrhage. Liver rupture can catalyze critical conditions such as hemorrhage and shock. Surgical workflow recognition in liver rupture repair surgery videos presents a significant task aimed at reducing surgical mistakes and enhancing the quality of surgeries conducted by surgeons. A liver rupture repair simulation surgical dataset is proposed in this paper which consists of 45 videos collaboratively completed by nine surgeons. Furthermore, an end-to-end SA-RLNet, a self attention-based recurrent convolutional neural network, is introduced in this paper. The self-attention mechanism is used to automatically identify the importance of input features in various instances and associate the relationships between input features. The accuracy of the surgical phase classification of the SA-RLNet approach is 90.6%. The present study demonstrates that the SA-RLNet approach shows strong generalization capabilities on the dataset. SA-RLNet has proved to be advantageous in capturing subtle variations between surgical phases. The application of surgical workflow recognition has promising feasibility in liver rupture repair surgery. ©2024 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons.

关键词： Image classification

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Thermal management challenges and approaches for liquid hydrogen-fueled aircraft

Thermal management challenges and approaches for liquid hydr...

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AIAA Aviation Forum and ASCEND, 2024

作者： Ordonez, Juan C. Sailabada, Chaianan Guo, Wei Cooley, Lance Cheetham, Peter Kim, Chul Zheng, Jim P. Gladin, Jonathan Cattafesta, Louis FAMU-FSU College of Engineering Department of Mechanical Engineering Center for Advanced Power Systems and Energy and Sustainability Center Florida State University TallahasseeFL32310 United States Electrical and Computer Engineering FAMU-FSU College of Engineering and Center for Advanced Power Systems Florida State University TallahasseeFL32310 United States Center for Advanced Power Systems FAMU-FSU College of Engineering and Center for Advanced Power Systems Florida State University TallahasseeFL32310 United States Department of Electrical Engineering The State University of New York at Buffalo BuffaloNY14260 United States School of Aerospace Engineering Aerospace Systems Design Laboratory Georgia Institute of Technology AtlantaGA30332 United States Department of Mechanical Materials and Aerospace Engineering Illinois Institute of Technology ChicagoIL60616 United States

ISBN: (数字)9781624107160

ISBN: (纸本)9781624107160

This paper presents an overview of thermal management challenges associated with aircraft that rely on liquid hydrogen as the sole fuel source. The paper discusses strategies that can enhance the overall cooling capacity and enable a larger contribution of fuel cells to the overall power. Design considerations for heat exchangers to integrate cryogenic hydrogen with secondary thermal management loops, outer mold line cooling, and additional thermal management strategies are presented. Cooling requirement estimates for a blended-wing aircraft (112 passengers, 2400 nautical miles) are reported. A finite element simulation using RANS suggests a cooling capacity rate of the order of 10 kW/m2 is available through the Outer Mold Line (OML). The paper also reports on the cooling capacity available by using hydrogen as a heat sink to cool the power train. For the IZEA concept, the hydrogen stream to the fuel cell can handle close to 6% of the fuel cell heat generation. © 2024, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Hydrogen fuels

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Research on Robust Measurement Method of Heart Rate Using Remote Photoplethysmography Based on Adversarial Learning Network with High and Low Frequency Features

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IEEE Transactions on Circuits and systems for Video Technology 2025年第6期35卷 5208-5222页

作者： Zhai, Dezhao Chen, Wei Ding, Yinghao Yu, Ming Li, Qinwei Wu, Hang Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China People's Liberation Army Systems Engineering Institute Academy of Military Sciences Tianjin300161 China Civil Aviation University of China Tianjin Key Laboratory for Advanced Signal Processing Tianjin300300 China Nankai University School of Artificial Intelligence Tianjin300381 China

Remote Photoplethysmography (rPPG) is a non-contact method for measuring heart rate (HR) through facial video, breaking the constraints of contact measurements and offering broad application prospects. However, in real monitoring scenarios, the distance of subjects and facial illumination often vary. This leads to degradation of rPPG signals due to changes in facial resolution and light intensity. This paper presents the High and Low Frequency Feature Adversarial Learning Network (HLFF-AL), which utilizes feature space interpolation and composite feature capture to perform multi-band global and local signal extraction. By adopting an adversarial learning strategy, it enhances the capability to capture semantic information of rPPG under varying resolutions and lighting, bridging the differences in rPPG signal generation due to resolution changes. While maintaining accuracy in HR measuring, the robustness of the network is improved to achieve robust measurement of HR via rPPG. Even under high-resolution conditions, the Mean Absolute Error (MAE) for the three public datasets - unchanging lighting (COHFACE, UBFC-rPPG) and varying lighting (BUAA-MIHR) - reached 1.10 bpm, 1.64 bpm, and 4.41 bpm, respectively, with a mere 0.29 bpm difference in MAE between high and low resolutions on the BUAA-MIHR dataset. This demonstrates that HLFF-AL can predict more robust rPPG signals in various resolutions and lighting scenarios, achieving competitive results compared to state-of-the-art methods. © 1991-2012 IEEE.

关键词： Heart

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