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SSRN 2022年

作者： Zhang, Kunpeng Xie, Jianwei Hao, Shuying Feng, Jingjing 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

In this paper, we investigate a class of tapered beam micro-gyroscope with electrostatically driven and consider the effects of electrostatic force nonlinearity and fringing field. The governing equations of system are derived by Euler angular transformation and Hamilton principle. The ordinary differential equations with fourth-order variable coefficient are solved by the Adomian decomposition method (ADM). Influence of parameters such as shape factors and DC voltage on static deflection, pull-in voltage and natural frequency of tapered beam micro-gyroscope are investigated. Galerkin discretization is performed on the governing equations of the tapered beam micro-gyroscope. The frequency-response equation of the system is deduced and solved by applying the method of multi-scale (MMS). We obtained the influence regular of DC voltage and fringing field effect on the frequency-response curves. Finally, performance of the tapered beam micro-gyroscope is analyzed in terms of bandwidth, sensitivity, and calibration curve nonlinearity under different shape factors. In static analysis, the pull-in voltage of system gradually decreases with the increase of the shape factors of tapered beam micro-gyroscope, and it will be further reduced by considering the fringing field effect. In the dynamic analysis, the maximum amplitude of motion in the drive and sense directions increases significantly with the shape factors of the tapered beam. Softening characteristics caused by the nonlinearity of the electrostatic force are enhanced. Compared with straight beam micro-gyroscope, the tapered beam micro-gyroscope has the higher amplitude of motion and pronounced nonlinear characteristics. Due to the nonlinearity, the frequency-response curves in the drive direction shifts to the left. The amplitude of motion in the drive direction has a high response over a wide frequency band. By controlling the DC voltage, the natural frequency of the sense mode is matched with the nonlinear natural

关键词： Bandwidth

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Thermal-Economic Optimization and Working Fluid Selection of Subcritical Organic Rankine system for Low-Temperature Waste Heat Recovery

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SSRN 2022年

作者： Zhang, Chao Li, Yongwang Fu, Wencheng Zhiting, Tong 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

In the present study, multi-objective optimization is conducted to search for the best operating condition for a subcritical organic Rankine system with the trade-off between system exergy efficiency and dynamic payback period (PBP). A 150°C wastewater heat source is employed as a typical low-temperature heat source. Five decision variables are considered: turbine inlet temperature and pressure, pinch point temperature differences in evaporator and condenser, and condensing temperature. The multi-objective genetic algorithm combined with the backpropagation neural network method is employed as the optimization approach. In addition, the improved Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) is developed to gain the optimal Pareto front solution for either working fluid and find the optimal working fluid among the candidates investigated. The results show that working fluid R236fa is the optimal solution, despite the minimum PBP for working fluid R123 and the maximum system exergy efficiency for working fluid R1234ze. Under the optimal working condition for working fluid R236fa, the system exergy efficiency and the PBP are 0.465 and 7.377 years, respectively. © 2022, The Authors. All rights reserved.

关键词： Multiobjective optimization

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Research on Feedforward control Based on Robot Dynamics Parameters Identification 17

Research on Feedforward Control Based on Robot Dynamics Para...

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17th IEEE International Conference on mechatronics and Automation, ICMA 2020

作者： Shao, Xingmao Wang, Shoujun Yang, Liusong Liu, Nan Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin300384 China Citic Heavy Industries Company Ltd. Luoyang471003 China

ISBN: (纸本)9781728164151

Accurate robot dynamics model can effectively improve the motion control performance of robot, and accurate dynamics parameters are the basis for establishing dynamics model. This paper discusses the parameter identification method of the tandem manipulator and the feedforward control scheme based on dynamics. First, we deduced the basic parameters of the first three joints of the UR5 manipulator, and identified the parameters through experimental sampling and calculation. Secondly, we established a feedforward control mechanism based on dynamics using the Simulink platform, and simulated and verified the feedforward control of the robot three-axis system. The experimental results show that the feedforward control scheme based on robot dynamics can effectively improve the error convergence performance, which proves the effectiveness of the method. © 2020 IEEE.

关键词： Manipulators

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Study on Mechanical Properties of Dual-Channel Cryogenic 3d Printing Scaffold for Mandibular Defect Repair

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SSRN 2023年

作者： Gao, Lilan Sun, Mengchao Liu, Jie Meng, Lulu Liu, Han Zheng, Xiongfei Liu, Hao Li, Ruixin Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300382 China Tianjin300382 China Beijing Friendship Hospital Capital Medical University 100050 China State Key Laboratory of Robotics Institutes for Robotics and Intelligent Manufacturing Shenyang Institute of Automation Chinese Academy of Sciences Shenyang110017 China Tianjin Key Laboratory of Oral and Maxillofacial Function Reconstruction Tianjin Stomatological Hospital The Affiliated Stomatological Hospital of Nankai University Tianjin300041 China

Mandibular defect repair has always been a clinical challenge, facing technical bottleneck. The new materials directly affect technological breakthroughs in mandibular defect repair field. Our aim is to fabricate a scaffold for mandibular defect repairing with advanced biomaterials. Therefore, a novel dual-channel printed scaffold consisting of silk fibroin/collagen type I /hydroxyapatite (SCH) and polycaprolactone/hydroxyapatite (PCL/HA) was fabricated by 3D printing technology with double nozzles. The mechanical properties and behaviors of dual-channel printed scaffold were investigated by performing uniaxial compression, creep, stress relaxation and ratcheting experiments respectively. The experiments indicated the Young modulus of dual-channel printed scaffold was 60.1 kPa and dual-channel printed scaffold was typical nolinear viscoelastic consistent with bone tissue. Finite Element Analysis (FEA) was employed performing a numerical simulation to evaluate the implantation effect in mandible. The stress distribution of the contact area between scaffold and defect was uniform, the maximum Mises stress of cortical bone and cancellous bone in defect area were 54.52MPa and 3.196MPa, and the maximum displacement of cortical bone and cancellous bone in defect area were 0.1575mm and 0.1555mm, which were distributed in the incisor region. The peak value of the maximum Mises stress for the scaffold implanted was 3.128× MPa and the maximum displacement was 6.453×mm distributed near incisor area. The displacement distribution of the scaffold was consistent with that of cortical and cancellous bone. The scaffold recovered well when the force applied on it disappeared. Above all, dual-channel printed scaffold had excellent bio-mechanical properties in implanting mandible, which provides a new idea for the reconstruction of irregular bone defects in the mandible and has good clinical development prospects. © 2023, The Authors. All rights reserved.

关键词： 3D printing

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Mechanical Properties of Glycated Cracked Articular Cartilage Under Uniaxial and Cyclic Tensile Loading

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SSRN 2025年

作者： Gao, Li-Lan Fang, Yi Lin, Xiang-Long Kong, De-Zhao Tan, Yan-Song Li, Rui-Xin Sun, Kai Zhang, Chun-Qiu Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300382 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300382 China Co. Ltd. Tianjin300190 China Tianjin Key Laboratory of Oral and Maxillofacial Function Reconstruction Tianjin Stomatological Hospital The Affiliated Stomatological Hospital of Nankai University Tianjin300041 China Orthopaedic of Tianjin First Central Hospital Tianjin300190 China

In clinical diagnosis, diabetes, and arthritis were often considered independent, which leads to diabetics getting worse by ignoring early arthritis symptoms. Therefore, the fatigue damage mechanism of articular cartilage in a hyperglycemic environment must be clarified. Under simulating physiological loads, this study delved into glycated cracked cartilage's fracture toughness and damage mechanism. Moreover, by introducing the glucose concentration as a crucial variable, a constitutive model of the ratcheting behavior of glycated cracked cartilage was established, which is utilized to predict the impacts of glycation on cartilage. The findings of this study revealed that the glycation environment causes cartilage hardening, which, in turn, leads to a substantial 38.1% reduction in the initial strain required for crack extension, despite an enhancement in tensile strength. The study of dynamic mechanical behavior further supported this observation. Scanning electron microscopy (SEM) showed that this mechanistic change occurs after collagen fibers harden and adhere to one another in the glycation environment. Overall, these results hold significant implications for understanding osteoarthritis (OA) in diabetic patients and for developing and protecting strategies related to this condition. © 2025, The Authors. All rights reserved.

关键词： Fracture toughness

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Influence of vibration on mechanical polishing micro-structured surface using discrete element method

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International Journal of Machining and Machinability of Materials 2020年第1期22卷 24-46页

作者： Wang, Guilian Lv, Bingrui Liu, Li Liu, Bin Zhou, Haibo 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 Tianjin300384 China Tianjin Laboratory of Control Theory and Applications in Complicated System Tianjin300384 China School of Electrical and Electronic Engineering Tianjin University of Technology Tianjin300384 China

A model using discrete element method (DEM) was conducted to simulate vibration assisted mechanical polishing micro-structured surface process by particle flow code in three dimensions (PFC3D). The effect laws of vibration frequency and amplitude on abrasive grains and polishing force were researched in detail according to the simulation results. The effects of vibration on the particles average motion velocity in one fluid cell were researched, and the simulation results show that average velocity increases with increase of vibration frequency and amplitude on the whole. The effects of vibration on the unbalanced force acting on the workpiece surface were quantified at first. The changes of average unbalanced force obviously increase for low feed rate with increase of frequency and increase approximately linearly with increase of amplitude. It is concluded that vibration with high frequency and great amplitude can significantly increase machining efficiency and improve surface quality in micro-structured surface polishing. Copyright © 2019 Inderscience Enterprises Ltd.

关键词： Finite difference method

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

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

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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

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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

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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

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Reform and Practice in Experimental Teaching from the View of "emerging Engineering": Case Study on the Field of Energy and Power Engineering 2

Reform and Practice in Experimental Teaching from the View o...

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2nd Information Communication Technologies Conference, ICTC 2021

作者： Tian, He Liu, Lijian Tian, Miao Zhou, Shimin Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology School of Mechanical Engineering Tianjin China Tianjin Academy of Educational Science Tianjin China Tianjin Newborn New Energy Technology Co. Ltd Tianjin China

ISBN: (纸本)9780738142876

According to the idea of "Emerging Engineering Education"talent training model of Ministry of Education, students should be trained to have "metaphysical"concept, connection, imagination, macro thinking. Project-driven experiment teaching focuses on a project, and the goal is the completion of the project;the student is the center of teaching activities, which is supported by the inquiry process. This study analyzes the significance of the project-driven method in experimental teaching. This paper describes the implementation process of experimental teaching in the field of energy and power engineering in terms of project design, teaching system construction and so on under the project-driven method. By analyzing the results of a questionnaire survey distributed to students of energy and power in the College of Mechanical Engineering at the Tianjin University of Technology, it is found that the students are satisfied with the effects of project-driven experimental teaching, and the use of experimental teaching has greatly aroused the students' enthusiasm for learning. The ability of the students to engage in autonomous learning, engineering practice and innovation has been greatly improved, and a good teaching effect has been achieved. © 2021 IEEE.

关键词： Students

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