检索结果-内蒙古大学图书馆

SSRN 2022年

作者： Liu, Yun Dong, Yue Li, Tao Zhang, Chuan-Zhi Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology School of Energy Power and Mechanical Engineering North China Electric Power University Baoding071003 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China

The concentrated solar power generation system with supercritical CO 2 as working medium has high cycle efficiency, which can effectively reduce the volume of heat exchange equipment and reduce the investment cost. However, there is no systematic comparative study on the effect of tube structure on the performance of supercritical CO 2 , but the structure of tubes has a significant effect on the heat transfer performance of supercritical CO 2 , so it is necessary to study it. In this contribution, we firstly analyze the effects of different structures of tubes on the performance of supercritical CO 2 . Then, we design a novel alternative elliptical twisted tube. Finally, we further analyze the effects of the novel tube on the heat transfer performance of supercritical CO 2 by using the field synergy principle. The results show that the novel alternative elliptical twisted tube is the best structure. When the mass flow is 0.08 kg·s - © 2022, The Authors. All rights reserved.

关键词： Solar energy

A noble kinetic model of H2/O2 system applicable to liquid rocket engine combustion

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A noble kinetic model of H2/O2 system applicable to liquid r...

45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

作者： Shimizu, Kazuya Hibi, Atsushi Koshi, Mitsuo Morii, Youhi Tsuboi, Nobuyuki University of Tokyo Tokyo 113-8656 Japan Graduate University for Advanced Studies Kanagawa 229-8510 Japan Kyushu Institute of Technology Kitakyushu Fukuoka 804-8550 Japan Department of Chemical System Engineering 7-3-1 Hongo Bunkyo-ku Japan Institute of Engineering Innovation School of Engineering 2-11-6 Yayoi Bunkyo-ku Japan Department of Aero Space Science 3-1-1 Yoshinodai Sagamihara Japan Department of Mechanical and Control Engineering 1-1 Sensui-cho Tobata-ku Japan

ISBN: (纸本)9781563479762

A chemical kinetic model for high pressure combustion of H 2/O2 mixtures has been developed. Some of the rate constants important in high pressure conditions were updated. Particular attention has been paid to different channels of the H+HO2 reaction, and to the third body efficiency in the H+O2+M and H+OH+M reactions. An analysis of the performance of an updated model is presented by comparing with various experimental data. Although the present model could reproduce most of shock tube data of ignition delay with variety of bath gases, there is still some discrepancy in the pressure dependence of flame speed between model predictions and recent experimental data. © 2009 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Ignition

An Adaptive PI control system for an Omnidirectional Mobile Robot

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Journal of Robotics and Mechatronics 1999年第5期11卷 349-355页

作者： Sato, Kazuya Watanabe, Keigo Izumi, Kiyotaka Watanabe, Makoto Department of Advanced Systems and Control Engineering Graduate School of Science and Engineering Saga University 1 Honjo Saga840-8502 Japan Department of Mechanical Engineering Faculty of Science and Engineering Saga University 1 Honjo Saga840-8502 Japan Telecommunication System Engineering Information Technology Division Nitsuko Corporation 2-6-1 Kitamigata Takatsu-ku Kawasaki210 Japan

Resolved acceleration and PID control provide high-performance control in an omnidirectional mobile robot, but most research does not consider plant parameter perturbations requiring that control gains be reacĳusted. We present an adaptive PI control strategy for mobile robots that automatically adjusts PI controller parameters based on error signals. Experiments verify the effectiveness of our method. © 1999, Fuji Technology Press. All rights reserved.

关键词： Mobile robots

Physical limits and information bounds of micro control. I. Quantum filters and non-demolition measurements 8

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Physical limits and information bounds of micro control. I. ...

8th International Symposium on Micromechatronics and Human Science, MHS 1997

作者： Ulyanov, S.V. Arai, F. Yamafuji, K. Fukuda, T. Rizzotto, G.G. Kurawaki, I. Department of Mechanical and Control Engineering University of Electro-Communications 1-5-1 Chofu Tokyo182 Japan Department of Micro Systems Nagoya University Furo-cho Chikusa-ku Nagoya Japan Corporate Advanced System Architectures Groups SGS-THOMSON Microelectronics Via C. Olivetti 2 Agrate Brianza20041 Italy Human Technology Division Research and Development Department Yamaha Motor Co. Ltd 2500 Shingai Iwata Shizuoka438 Japan

ISBN: (纸本)0780341716

The possible accuracy limit of micro control of dynamic systems in which the dominating disturbances are thermal and quantum noises is considered. The optimal control with a Kalman-Bucy filter (KBF) and physical limits of micro control of a macro object are studied. For the individual control of a micro object a quantum prototype of KBF with non-demolition observation on the basis of quantum filtering equation is introduced. © 1997 IEEE.

关键词： Demolition

Robust walking of biped robot on uneven terrain using effect of wobbling mass

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Robust walking of biped robot on uneven terrain using effect...

IEEE International Conference on Robotics and Biomimetics

作者： Terumitsu Hayashi Masaki Yamakita Yuta Hanazawa Fumihiko Asano Dept. of Mechanical and Control Engineering Tokyo Institute of Technology Meguro-ku Tokyo JAPAN Faculty of Engineering Department of Applied Science for Integrated System Engineering Kyushu Institute of Technology Kita-Kyushu Fukuoka Japan School of Information Science Japan Advanced Institute of Science and Technology Nomi Ishikawa JAPAN

ISBN: (纸本)9781479973989

Many studies about improving the performance of biped robots, especially energy efficiency and waking speed have been done. These properties, however, are secondary to the robot ability to prevent falling down on irregular grounds. In this paper, we propose a novel method which uses an active up-and-down wobbling mass to improve walking ability and robustness of biped robot on uneven terrain. We will show improvements that the number of walk steps is increased in numerical simulations using the proposed method. We also evaluate quantitatively walking ability of biped robot on uneven terrain using a performance measure called Gait Sensitivity Norm (GSN) and H ∞ norm. Furthermore, we show the effectiveness of H ∞ norm measure which cannot be evaluated by GSN in a walking example.

关键词： Legged locomotion Limit-cycles Trajectory Robustness Mathematical model Sensitivity

Size-Dependent Strength Superiority in Multi-Principal Element Alloys Versus Constituent Metals: Insights from Machine Learning Potential and Embedded-Atom Model

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SSRN 2024年

作者： Shuang, Fei Ji, Yucheng Laurenti, Luca Dey, Poulumi Department of Materials Science and Engineering Faculty of Mechanical Engineering Delft University of Technology Mekelweg 2 Delft2628 CD Netherlands Beijing Advanced Innovation Center for Materials Genome Engineering National Materials Corrosion and Protection Data Center Institute for Advanced Materials and Technology University of Science and Technology Beijing Beijing100083 China Delft Centre of System and Control Faculty of Mechanical Engineering Delft University of Technology Mekelweg 2 Delft2628 CD Netherlands

Multi-principal element alloys (MPEAs) are renowned for their enhanced mechanical strength compared to their constituent metals, as evidenced by various experimental techniques such as tension/compression tests and instrumental indentation. Nevertheless, atomistic simulations sometimes produce conflicting results, casting doubt on the consistently superior mechanical properties of MPEAs. To address these discrepancies, we develop new machine-learning interatomic potentials (MLIPs) for body-centered cubic refractory MoNbTaW MPEAs, supported by a comprehensive dataset that encompasses extensive defects. We also benchmark the established embedded-atom model (EAM) potential against this dataset and our new MLIPs. Our simulations, covering diverse MoNbTaW compositions, confirm that both MLIPs and EAM accurately capture the critical strengthening mechanisms associated with plastic deformation in MPEAs. Utilizing the EAM potential, we perform reliable large-scale atomistic simulations to investigate various plastic mechanisms. Our findings suggest that generally, MPEAs exhibit superior mechanical strength compared to their constituent metals in macroscale specimens, primarily due to solid solution strengthening and dislocation motion. However, at the nanoscale where plasticity is mainly governed by dislocation nucleation and grain boundary deformation, the constituent metals may outperform MPEAs. This study identifies a critical length scale above which MPEAs demonstrate enhanced mechanical strength relative to their constituent elements. Below this scale, the advantage diminishes, underscoring a significant size-dependent effect that is crucial for optimizing MPEA applications, particularly at the nanoscale. © 2024, The Authors. All rights reserved.

关键词： Grain boundaries

Understanding the Limitations of Thick Electrodes on the Rate Capability of High-Energy Density Lithium-Ion Batteries

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SSRN 2024年

作者： Xie, Wenlong Zhang, Zhengjie Gao, Xinlei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China School of Transportation Science and engineering Beihang University Beijing100191 China Department of Mechanical Engineering Imperial College London LondonSW7 2AZ United Kingdom

As a core component of transportation electrification, lithium-ion batteries need to address two critical challenges: achieving high energy density and enabling fast charging. However, changes in electrode thickness could result in a trade-off between these two characteristics. Herein, the impact of electrode thickness on the electrochemical performance, thermal behavior, as well as energy and power density of LiNi0.8Co0.1Mn0.1O2(NCM)/graphite batteries are investigated through mathematical modeling. Underutilization of active materials of the thick electrode is identified as the primary limitation on rate capability, which can be attributed to the slow solid-state diffusion and poor electrolyte transport within the electrode, especially the enlarged concentration gradients in the solid phase and the lithium depletion in the electrolyte phase during high-rate charging. Evolutions of local current density and heat generation rate along the electrode thickness are compared, identifying the underlying mechanism of inducing uneven reaction kinetics inside the battery. The trade-off between the energy and power density as a function of electrode thickness is investigated based on the limitations of charge transfer and mass transport. Furthermore, the rate-limiting factors under various application requirements are elucidated. This study will provide guidance for the electrode design of high-energy-density batteries with fast-charging capabilities. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

Numerical Investigation on Thermal Characteristics and Energy Efficiency of Lithium-Ion Battery Under Different Charging Stresses

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SSRN 2024年

作者： Xie, Wenlong Gao, Xinlei Zhang, Zhengjie Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China Department of Mechanical Engineering Imperial College London LondonSW7 2AZ United Kingdom School of Transportation Science and engineering Beihang University Beijing100191 China

The thermal characteristics of lithium-ion batteries during the charging process significantly impact their electrochemical performance and safety, particularly under high-rate or extreme temperature conditions. In this study, an electrochemical-thermal coupling model for a 2.5 Ah LiNi0.8Co0.1Mn0.1O2 18650 lithium-ion battery is proposed and experimentally validated. The heat generation and variation patterns of the electrodes at different charging rates and temperatures are evaluated, and the influence mechanisms of various electrode design parameters on charging energy efficiency are elucidated. The results reveal that high-rate charging increases the proportion of irreversible heat in the total heat generation, primarily due to the increase in ohmic heating at the positive electrode. Ambient temperature is less sensitive to heat generation than the C-rate, but low temperatures can also increase irreversible heat and are associated with an increase in positive polarization heat. Analyzing thermal characteristics at the electrode level can contribute to the optimization of battery design and the improvement of thermal safety. Electrode architectures, including electrode thickness, active material porosity, particle radius and negative/positive electrode capacity (N/P) ratio, are determined to analyze their effects on the heat generation of various components within the battery. Thick electrodes or active materials with high porosity induce significant ohmic heating and increase irreversible heat, with a slight effect on reversible heat, which is detrimental to energy efficiency. Large particle radii primarily increase reaction heat and polarization heat, and a high N/P ratio reduces the battery heat generation and is related to the reduction of negative reaction heat. Notably, variations in both two parameters have limited impact on to energy efficiency. Therefore, implementing appropriate thermal management across various charging scenarios is crucial for achievin

关键词： Lithium-ion batteries

Hybrid brain/muscle-actuated control of an intelligent wheelchair

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Hybrid brain/muscle-actuated control of an intelligent wheel...

IEEE International Conference on Robotics and Biomimetics

作者： Zhijun Li Shuangshuang Lei Chun-Yi Su Guanglin Li Key Lab of Autonomous System and Network Control Ministry of Education and College of Automation Science and Engineering South China University of Technology Guangzhou China Department of Mechanical and Industrial Engineering Concordia University Montreal Canada Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen Guangdong China

Brain-computer interface (BCI) controlled wheelchair robots can serve as powerful aids for severely disabled people in their daily life, especially to help them move voluntarily. In order to better understand human “thought”, owing to the development of the hybrid brain/muscle interface technique, in this paper, we present a real-time hybrid brain/muscle interface to control a wheelchair directly to keep the disables recovering several motion capabilities by using noninvasive motor imagery Electroencephalography (EEG) and Electromyography (EMG). The EMG and EEG signals from the users are extracted to control the motion of an intelligent wheelchair. Both signals processing consists of off-line training, online control evaluation, and real-time control. An algorithm called the common spatial patterns (CSP) is used in this human-robot system to extract the most discriminative spatial patterns pairs as features. The extensive experiments were conducted on the developed human-wheelchair systems to verify the proposed approaches.

关键词： Wheelchairs Electroencephalography Electromyography Training Robots Muscles Real-time systems

In-Situ Biaxial Cyclic Loading Behavior of Articular Cartilage and its Microstructure Analysis

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SSRN 2022年

作者： Gao, Lilan Feng, Luming Tan, Yansong Liu, Gang Li, Ruixin Gao, Hong Zhang, Chunqiu Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Tianjin Stomatological Hospital Tianjin300041 China School of Chemical Engineering and Technology Tianjin University Tianjin300350 China

Altered cyclic loading may change the mechanical properties, further inducing damage to articular cartilage. In this study, we studied the biaxial cyclic loading behavior of knee articular cartilage and analyzed the changes of microstructure at fibril level. Firstly, the in-plane biaxial cyclic behaviors of cartilage were investigated with an emphasis on the effects of loading paths to account for complicated loading states in daily activities. The results show that the strain evolution in X-direction is obviously affected by the constraints in Y-direction (orthogonal direction). The loading path has a great influence on the biaxial mean strain, while due to no constraint and the largest stress constraint in Y direction, proportional loading path and uniaxial loading path show the highest and lowest mean strain in X-direction, respectively. Subsequently, the effects of stress amplitude and stress peak holding time on mean strain were probed under square path. It was found that the mean strain of cartilage increases with the increase of stress amplitude or peak stress holding time. In addition, to reveal the inherent deformation mechanism, the collagen fibrils networks before and after biaxial cyclic loading were analyzed. The rearrangement of collagen fibrils networks is related to the stress state of cartilage. Larger stress leads to severer fiber damage in cartilage. © 2022, The Authors. All rights reserved.

关键词： Cartilage