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design of wearable squat booster for automobile assembler based on ergonomics 6

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Design of wearable squat booster for automobile assembler ba...

2020 6th International Forum on Engineering Materials and Manufacturing Technology, IFEMMT 2020

作者： Chen, Zhewen Qiao, Zhifeng Bao, Tianxu Dou, Fuchao Chen, Xinpu Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin China

Aiming at the problem that automobile assembler need to squat for a long time, a wearable squatting assistance system with low cost, simple control and easy to squat and walk is designed. Based on ergonomics and finite element theory, UG was used to draw a three-dimensional solid model of the wearable squatting power system for automobile assemblers. With the help of ANSYS software, the statics analysis of key components is carried out to check their strength and stiffness. It is concluded that the wearable squatting power assist device for automotive fitters based on ergonomics has reached the design requirements in terms of function use and strength and stiffness. © Published under licence by IOP Publishing Ltd.

关键词： Ergonomics

Temperature Control Based on Fuzzy Logic Two-degree-of-freedom Smith Internal Model

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Instrumentation 2020年第2期7卷 1-8页

作者： WANG Zhigang HE Meng Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control Tianjin University of TechnologyTianjin 300384China National Demonstration Centre for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China

According to the characteristics of the large time delay,nonlinearity and the great inertia of temperature control system in biomass pyrolysis reactor,a two-degree-of-freedom Smith internal model controller based on fuzzy control is ***,the mathematical model of the temperature control system is established by using the step response method,and then the two-degree-of-freedom Smith internal model controller is designed,and the good tracking performance and disturbance suppression performance can be obtained by designing the set value tracking controller and interference rejection ***,the fuzzy control algorithm is used to realize the on-line tuning of the control parameters of the two-degree-of-freedom Smith internal model *** simulation results show that,compared with the traditional internal model control,fuzzy internal model PID control and two-degree-of-freedom Smith internal model control,the algorithm proposed in this paper improves the influence of lag time on the control system,realizes the separation control of set point tracking and anti-jamming performance and the self-tuning of control parameters,and improves the control performance of the system.

关键词： Smith Predictive Controller Internal Model Control Two Degrees of Freedom Fuzzy Control Algorithm

Tme: Temporal and Motion Enhancement for Action Recognition

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SSRN 2022年

作者： Wang, Hao Liu, Guohua Zhao, Bin Sensor Technology Intelligent System Lab College of Electronic Information and Optical Engineering Nankai University Tianjin300350 China School of Artificial Intelligence Guilin University of Electronic Technology Guangxi Guilin541004 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin300350 China Engineering Research Center of Thin Film Optoelectronics Technology Ministry of Education Nankai University Tianjin300350 China

The key to video understanding is to capture temporal information. 3D CNNs can achieve good performance by directly fusing spatial and temporal features but are computationally intensive. Conventional 2D CNNs perform well in image recognition, but their inability to extract temporal features leads to poor performance in video action recognition. In this work, we aim to identify temporal relationships for video action recognition. To this end, we propose a temporal and motion enhancement (TME) module consisting of two submodules: multipath temporal enhancement(MTE) module and a long short-range Motion Enhancement(LSME) module. The MTE module consists of four paths: the residual path, temporal aggregation(TA) path, channel-wise temporal excitation(CTE) path and spatial-attention temporal excitation(STE) path. The residual path makes part of the information in the original activation accessible. The TA path employs convolution on the temporal dimension to characterize temporal representation. The CTE path rebuilds channelwise feature relationships in terms of the temporal aspect. The STE path introduces attention mechanisms and explores the temporal modeling. We aggregate features of different paths by splitting channels, which is efficient for model inference. The LSME module calculates feature-level temporal differences between long and short range frames, which enhances the motion-related features. The TME module is plug-and-play and can be inserted into 2D CNNs to form an effective TMENet with limited extra computational cost. The extensive experiments on several action recognition datasets, such as Kinetics400, Something-Something V1&V2, HMDB51, and UCF101, demonstrate that the TMENet achieves the state-of-the-art performance with high efficiency. The code will be released soon. © 2022, The Authors. All rights reserved.

关键词： Image recognition

Vibration Absorption Efficiency and Higher Branches Elimination of Variable-Stiffness Nonlinear Energy Sink

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Journal of Harbin Institute of Technology(New Series) 2020年第1期27卷 76-84页

作者： Rui Zhong Jian’en Chen Weimin Ge Jun Liu Xiaofeng Wang Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China

Vibration absorption efficiency of a variable⁃stiffness nonlinear energy sink(NES)was investigated when the main oscillator was subjected to harmonic and impulse *** slow flow equations of the coupled system were derived by using the complexification⁃averaging method,and the nonlinear equations which describe the steady⁃state response were *** the harmonic excitation force increased,the system which comprises constant⁃stiffness NES generated higher branch responses,greatly reducing the vibration absorption *** influence of nonlinear stiffness on the responses of the system was *** show that,with the increase of harmonic exciting force,a reduction of NES stiffness can eliminate the higher branch responses and even the frequency band of strongly modulated *** vibration absorption efficiency of variable⁃stiffness NES attached to the linear oscillator for different amplitudes of impulse excitation was *** show that the proper reduction of nonlinear stiffness under increasing impulse excitation can greatly increase the vibration absorption efficiency of NES,and the variable⁃stiffness design can effectively mitigate the negative influences of the increase of the excitation amplitude on the efficiency of constant⁃stiffness NES.

关键词： nonlinear energy sink efficiency variable⁃stiffness vibration suppression higher branch

Model Predictive Control for Steering system of Water-Jet Propulsion

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Journal of Shanghai Jiaotong university(Science) 2020年第3期25卷 299-303页

作者： GONG Zhenghua SONG Chenwei LI Gangqiang CHEN Jianping XU Zijing YUAN Jingqi MOE Key Laboratory of Marine Intelligent Equipment and System Shanghai Jiao Tong UniversityShanghai 200240China Laboratory of Science and Technology on Waterjet Propulsion Shanghai 200011China Marine Design&Research Institute of China Shanghai 200011China Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China

Water-jet propulsion is a widely applied ship propulsion *** steering control system has an important impact on manoeuvre *** this paper,transfer function model is firstly established on the basis of mechanism analysis of water-jet steering ***,by considering the variability of model parameters and input constraints in practical operation,a model predictive controller is designed for steering system ***,model based disturbance observer is employed in an attempt to reject environmental *** performance of the proposed model predictive control (MPC) scheme for a particular steering system is compared with that of conventional proportional integral derivative (PID) control *** results demonstrate that the proposed model predictive controller outperforms conventional PID controller,particularly in robustness,response delay and tracking accuracy.

关键词： water-jet propulsion steering system model predictive control(MPC) disturbance observer

Enhanced Toughness and Ductility of T91 Steel after Exposure to Liquid Lbe Saturated by Oxygen at 350-500 °C

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SSRN 2024年

作者： Zhou, Zhikun Tian, Chenwen Dong, Wenbo Du, Juan Liu, Yunpeng Wahab, Magd Abdel Chen, Ziguang Department of Engineering Mechanics School of Aerospace Engineering Huazhong University of Science and Technology Wuhan430074 China Laboratory Soete Faculty of Engineering and Architecture Ghent University Technologiepark Zwijnaarde 46 ZwijnaardeB-9052 Belgium Institute of Intelligent Manufacturing Jianghan University Wuhan430056 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China College of Engineering Yuan Ze University Taiwan Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan430074 China

The mechanical tensile properties of T91 steel after being oxidized in liquid LBE saturated by oxygen at 350-500 °C for up to 1,000 h are studied. Duplex oxide scales are found on T91 steels after the LBE exposure, and the thickness evolution is revealed. Oxidized T91 steels with surface oxide scale yield enhanced toughness and ductility, which is mainly attributed to the inner oxide layer. We show that the enhancing effect relies on the presence of the oxide scale, not its thickness. The possible enhancing effect of the oxide scale on the toughness of T91 steel by impeding the dislocation from emitting out of the steel surfaces is discussed and qualitatively verified by micro-scale elastoplastic simulations based on a newly proposed discrete dislocation dynamics and peridynamics superposition scheme. © 2024, The Authors. All rights reserved.

关键词： Ductility

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

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

A Low SAR, Small size, High gain, Circularly polarized Antenna for Wearable Application 2

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A Low SAR, Small size, High gain, Circularly polarized Anten...

2020 2nd International Conference on Artificial Intelligence Technologies and Application, ICAITA 2020

作者： Wang, Chao Zhang, Liang Cheng, Yi Li, XueMei Wu, Xianliang Key Lab of Ministry of Education of Intelligent Computing and Signal Processing Anhui University Hefei Anhui230601 China AnHui Province Key Laboratory of Simulation and Design for Electronic Information System Hefei Normal University Hefei Anhui230601 China

A planar, small size, high gain, low specific absorption rate (SAR) and circularly-polarized (CP) wearable antenna is proposed in this paper. The antenna is fabricated on a substrate with a dielectric constant of 3.5 with a thickness of 0.5 mm and sized at 42×42 mm only. Both the simulation results show that the overlap bandwidth of impedance and axial ratio of the proposed antenna is 13.7% (5.15-5.91 GHz). To isolate the antenna against the influence of the human body, a artificial magnetic conductor (AMC) plane is added on the reverse side of the radiator. The AMC structure effectively isolates the human body from the radiation of the antenna and reduces the specific absorption rate (SAR) of it by more than 96.1% at 5.5 GHz, which improves the antenna gain and the peak gain reaches 5.09 dBi at 5.5 GHz. The wearable performance of the antenna was analyzed, and it is observed that it can sustain good performance even under human body loading. Beside, the antenna has a small size, which makes it ideal for wearable applications. © 2020 Published under licence by IOP Publishing Ltd.

关键词： Wearable antennas