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Flow and thermal modeling of liquid metal in expanded microchannel heat sink

Frontiers in Energy 2023年第6期17卷 796-810页

作者： Mingkuan ZHANG Xudong ZHANG Luna GUO Xuan LI Wei RAO Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084China School of Mechanical Engineering Tianjin University of CommerceTianjin 300134China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China Beijing Key Laboratory of CryoBiomedical Engineering and Key Laboratory of Cryogenics Beijing 100190China

Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (Rt). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (Um) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h_(2) < 0, h_(2) is the height of expanded channel for E-MCHS) and when over plate was raised (h_(2) > 0).

关键词： liquid metal cooling heat sink expanded microchannel flow and thermal modeling

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Effects of Wall Emissivity on Aerodynamic Heating in Scramjets

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Fluid Dynamics & Materials Processing 2020年第6期16卷 206-216页

作者： Yue Zhou Pengfei Ju School of Aeronautical Science and Technology Beihang UniversityBeijing100191China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education(Tianjin University of Technology) Tianjin300384China

The effects of the wall emissivity on aerodynamic heating in a scramjet are *** supersonic turbulent combustion flow including radiation is solved in the framework of a decoupled strategy where the flow field is determined first and the radiation field *** particular,a finite difference method is used for solving the flow while a DOM(iscrete ordinates method)approach combined with a WSGGM(weighted sum of gray gases)model is implemented for radiative *** nonreactive turbulent channel flows are examined for a DLR hydrogen fueled scramjet changing parametrically the wall *** results indicate that the wall radiative heating rises greatly with increasing the wall *** the wall emissivity rises,the radiative source and total absorption increase,while the incident radiation decreases ***,although the radiative heating can reach a significant level,its contribution to the total aerodynamic heating is relatively limited.

关键词： Scramjet aerodynamic heating wall emissivity radiation

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Detection of weld defects based on incremental two-dimensional principal component analysis 15

Detection of weld defects based on incremental two-dimension...

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15th IEEE International Conference on Mechatronics and Automation, ICMA 2018

作者： Shen, Yaohua Ge, Weimin Wang, Xiaofeng School of Mechanical Engineering Tianjin University of Technology China Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechanical System Binshui Xidao 391 Xiqing District Tianjin300384 China

ISBN: (纸本)9781538660720

Aiming at the requirements of the real-time detection of weld defects in the industry, the candid covariance-free incremental PCA (CCIPCA) algorithm was introduced into the Two-Dimensional Principal Component Analysis (2PCA) algorithm, therefore an incremental 2DPCA algorithm (I2DPCA) is proposed. Firstly, the images captured by camera are preprocessed to improve the quality of the images because the captured images might be affected in the process of image acquisition. Then the I2DPCA algorithm is used to achieve feature extraction, and the dimension of the images is reduced. Finally, the recognition of weld defects is implemented using the k-nearest neighbor algorithm (KNN). Compared with the methods of traditional recognition by extracting the sizes of several geometric defects, the proposed algorithm has the advantage of the small memory spaces, the high recognition rate and the strong real-time recognition. The experimental results show that the proposed algorithm has higher recognition rate and is more practical than the 2DPCA, and the recognition rate reaches 94%, which can meet the requirements of the real-time detection. © 2018 IEEE.

关键词： Principal component analysis

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Prediction model of bone drilling temperature based on heat source method in surgical rehabilitation

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Procedia CIRP 2020年 89卷 263-269页

作者： Yahui Hu Zhiqiang Yan Xiangjun Li Chunqiu Zhang Qingchun Zheng Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjing University of Technology Tianjin China School of Mechanical Engineering Tianjin University of Technology Tianjin China

In order to feedback the cutting temperature in real time during the operation with the surgical robot, this study established a temperature prediction model to analyze the temperature distribution of the cortex. In this work, a three-dimensional governing equation for heat transfer of bone tissue during drilling is proposed, and the heat transfer of cortical bone is evaluated by a reverse heat transfer method. The prediction model was validated by experimental methods and the heat affected zone (HAZ) of cortical bone was analyzed. The results show that the prediction results are in good agreement with the relevant experimental results. HAZ increases with increasing rate of penetration; the closer the bone hole is, the earlier the temperature rises; and the temperature at which the cortical bone is difficult to measure (radial distance x < 0.5 mm) is predicted. The predictive model can accurately predict the temperature distribution of the cortical bone and prevent the occurrence of thermal damage. Provide technical support for the development of medical rehabilitation robots. And reduce the patient’s secondary injury, which is conducive to rapid recovery after surgery.

关键词： Cortical bone drilling Temperature estimation Inverse heat transfer problem Thermal damage rehabilitative

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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 vibration and crack propagation control of cracked asymmetric rotor based on three-dimensional finite element model 15

Study on vibration and crack propagation control of cracked ...

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15th IEEE International Conference on Mechatronics and Automation, ICMA 2018

作者： Hu, Rong Liu, Jun Chen, Jianen Wang, Xiaofeng Ge, Weimin School of Mechanical Engineering Tianjin University of Technology China Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechanical System Binshui Xidao 391 Xiqing District Tianjin300384 China

ISBN: (纸本)9781538660720

In order to solve the vibration problems of a cracked asymmetric rotor, the three-dimensional finite element model of the rotor is established combined with a nonlinear contact approach. The free interface modal synthesis method is applied to shorten the computation time by reducing the order of the model. The vibration characteristics of the asymmetric rotor and the cracked asymmetric rotor in different crack locations are analyzed by the simulation. The results of numerical simulation show the appearance of crack will affect the resonance frequency and the range of unstable area on the major critical speed. At the same time, the active control of the rotor is realized by the electromagnetic actuator controlled by neural network PID. Secondly, based on the theory of rotor dynamics, the effects of rotational speed and unbalance on the breathing behavior of the cracked rotor are discussed. In this paper, it proposes a novel method delaying the crack extension effectively. In the process of operation, the electromagnetic actuator (EMA) can effectively control the vibration and can delay the crack propagation. © 2018 IEEE.

关键词： Computation theory

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Path planning for mobile robot using the novel repulsive force algorithm

Path planning for mobile robot using the novel repulsive for...

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2015 5th International Conference on Computer Sciences and Automation Engineering(ICCSAE 2015)

作者： Yunwei Jia Guoqiang Yin Lianyu Zhao Xueping Li Siyue Sun School of Mechanical Engineering Tianjin University of Technology Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System

A new type of repulsive force algorithm is proposed to solve the problem of local minimum and the target unreachable of the classic artificial potential field method in this paper. The Gaussian function that is related to the distance between the robot and the target is added to the traditional repulsive force, solving the problem of the goal unreachable with the obstacle nearby;variable coefficient is added to the repulsive force component to resize the repulsive force, which can solve the local minimum problem when the robot, the obstacle and the target point are in the same line. The effectiveness of the algorithm is verified by simulation experiments based on MATLAB.

关键词： Artificial potential field localminimum goal unreachable mobile robot

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design of an electronic device for detection of exhaled gas concentration 5

Design of an electronic device for detection of exhaled gas ...

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2024 5th International Conference on Electrical, Electronic Information and Communication Engineering, EEICE 2024

作者： Fan, Chuanxiu Liu, Xue Yu, Zhichao Du, Changsong Jia, Shengde Liu, Qing Yan, Pengbo Tianjin Key Laboratory of Film Electronic and Communication Device Tianjin University of Technology Tianjin300384 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China Tianjin Chest Hospital Tianjin300384 China

To enable preliminary diagnosis of various diseases in the human body, detecting the concentrations of targeted components in exhaled gases is an effective way without invasive diagnosis. An exhaled gas concentration detection device is proposed in this paper. Firstly, this device employs a high-accuracy analog front end (AFE) for transmitting the concentrations of targeted components to an electronic voltage signal. The core circuit of AFE is a high-precision and low-current constant current source. Secondly, a heating circuit with controllable temperature is also designed to provide an appropriate operating temperature for different types of gas sensor materials. Thirdly, the system applies a microcontroller to directly read multiple-channel gas concentrations and independently control multiple heating circuits. The performance of the device has been validated through simulations. © Published under licence by IOP Publishing Ltd.

关键词： Computer resource management

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Study on the amplitude-frequency characteristics of a non-planar complex structure

Study on the amplitude-frequency characteristics of a non-pl...

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第八届国际振动工程会议

作者： Ruiqin Wu Wei Zhu Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System School of Mechanical EngineeringTianjin University of Technology

The amplitude-frequency characteristics of a non-planar complex structure composed of a flexible beam and a ring are systematically investigated. The kinetic and strain potential energy expressions are theoretically calculated for the beam-ring system. Hamilton's principle is employed to derive the nonlinear governing equations of motion of the beam-ring structure. The nonlinear partial governing differential equation of motion for the beam-ring system is discretized into two coupled ordinary differential equations including quadratic and cubic nonlinearities by using Galerkin's technique. The method of multiple scales is utilized to approximately analyze the dynamical system and yield a set of autonomous equations. The amplitude-frequency characteristics and the stability of the steady-state solution are studied numerically. The frequency-response curves show that there exist multi-value solution and jump phenomenon in the system and some parameters of the amplitude-frequency equations have significant contributions to the nonlinear responses of the beam-ring system.

关键词： the beam-ring structure amplitude-frequency characteristics steady-state solution jump phenomenon

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Pickup Manipulator design and Its Kinematics Simulation 2

Pickup Manipulator Design and Its Kinematics Simulation

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2018 2nd International Symposium on Resource Exploration and Environmental Science, REES 2018

作者： Zhang, Zhongdang Zhang, Zhaoqiang Ma, Shitai Zhou, Haibo Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin300384 China

In order to improve the flexibility of the pickup manipulator and solve the problem of picking up small sports balls in training ground such as golfing, tennis, and table tennis, a 5-DOF pickup manipulator structure is designed. According to the pickup task requirements of the manipulator, through theoretical calculations, the 86HS series stepping motor is selected as the driving motors of the front end joints. Based on this, the stepping motor control system is designed to realize the closed-loop control of the manipulator. Then the manipulator model is built using D-H method, the inverse kinematics solution is calculated, and the analysis of kinematic theory is conducted. Finally, the targeted pickup point is selected to carry out case simulation analysis of the manipulator, the motion law of the manipulator is verified to be reasonable and the task of picking up small sports balls is completed. © Published under licence by IOP Publishing Ltd.

关键词： Manipulators

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