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2021 International Conference on Materials Genetic engineering and Information science, MGEIS 2021

作者： Wang, Xinyu Shen, Junjie Guo, Xiangru Qiao, Jixin 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

Based on the theory of crystal plasticity, coupled with dislocation and lath hardening models, this paper establishes a crystal plasticity finite element model describing the high temperature creep of P92 steel. Open source software was used to generate lath models with an average size of 350nm, 650nm and 950nm to explore the effect of lath coarsening on the high-temperature creep behavior of P92 steel. The results show that the roughening of the slats increases the rate of creep deformation, resulting in a decrease in the service life of the material. Observing the slat model, it can be seen that the roughening of the slats enlarges the numerical gradient of stress and strain, and aggravates the overall plastic strain of the model. The coarsening of the slats accelerates the movement of dislocations, causing the density of movable dislocations to increase, and at the same time the shear strain amplitude of the slip system increases, thereby reducing the hardening behavior of the material. © Journal of Physics: Conference Series 2021.

关键词： Coarsening

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Exploration and Practice of Hierarchical Graduation Project under the Background of science Collaborative Education and engineering Education Accreditation 5

Exploration and Practice of Hierarchical Graduation Project ...

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5th International Conference on Advances in Artificial Intelligence, ICAAI 2021

作者： Gao, Lilan Tan, Yansong Sun, Yanfang Lv, Linwei Li, Bin Gao, Qijun Wang, Xiaofei Zhao, Yijiao 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

ISBN: (纸本)9781450390699

Graduation project is an important integrated practice segment for undergraduate education, since the quality of undergraduate education can be directly evaluated by the quality of graduation project. Under the background of science collaborative education and engineering education accreditation, it is necessary to explore an intelligent and integrated graduation project system to train students by all sorts of engineering and research projects, thus improve students' practical ability and innovation ability. This paper first analyzed the problems of the graduation project in the major of process equipment and control engineering, then introduced a novel hierarchical graduation project system to adapt to the concept of science collaborative education and engineering education. By putting the novel graduation project system into effect, the quality of graduation project has significantly improved. © 2021 ACM.

关键词： Accreditation

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Neural-Network-Based Filtering with Encoding Mechanisms: Applications to Multiple Unmanned Aerial Vehicles

Neural-Network-Based Filtering with Encoding Mechanisms: App...

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Chinese Automation Congress (CAC)

作者： Kaiqun Zhu Xinpeng Xu Zhiru Cao Ran Sun Ya Yang State Key Laboratory of Internet of Things for Smart City University of Macau Macau China Shanghai Electro-Mechanical Engineering Institute Shanghai China School of Mechatronic Engineering and Automation Shanghai University Shanghai China Department of Control Science and Engineering University of Shanghai for Science and Technology Shanghai China

In this paper, the neural-network-based filtering problem is investigated for multi-sensor systems with dynamic encoding mechanisms. The sensor nodes and the remote filter are connected through bandwidth-constrained communication networks. To alleviate the communication burden, a novel dynamic encoding-based data compression-decompression mechanism is proposed so as to encode the data into a limited number of bits. Then, with the aid of the neural network learning method, a neural-network-based set-membership filter is developed for estimating the system states. Sufficient conditions are obtained to ensure that the filtering error remains within the bounded ellipsoidal set. In addition, the neural network tuning parameters and the filter gains are calculated by solving constrained optimization problems. Finally, the effectiveness of the proposed filtering algorithm is verified through a scenario of maneuvering target tracking using multiple unmanned aerial vehicles.

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Electromagnetic Performance and Vibration Analysis of a Special-shaped External-rotor Machine

Electromagnetic Performance and Vibration Analysis of a Spec...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Ziwei Dong Liang Yan Zhang Lu School of Automation Science and Electrical Engineering Beihang University Beijing China Science and Technology on Aircraft Control Laboratory Beihang University Beijing China Tianmushan Laboratory Hangzhou China Ningbo Institute of Technology Beihang University Ningbo China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Hangzhou China

Permanent magnet synchronous machines have advantages such as small size, light weight, high efficiency, etc. It is more and more widely used in robots, electromagnetic propulsion, electric vehicles and so on. High power density and high torque density are urgent need for those applications. The electromagnetic design of machines mostly adopt multi-pole magnet patterns to reduce the stator yoke size. It helps to decrease the mass of the machine with the same power and improve the torque density. As the number of poles grows larger, the frequency and the core loss of per unit volume will also increase with the same speed, which can aggravate the heat problem of the machine. It is easy to generate the low-order vibration with high flux density. Therefore, the performance of a special-shaped external-rotor machine and comparisons with the traditional machine are analyzed in this paper. Numerical simulation is conduced to validated that the special-shaped magnet pattern can reduce the torque ripple, improve the torque output and power density. From the two-dimensional Fourier analysis of the radial electromagnetic force, it is found that the low-order amplitude of the special-shaped machine is greatly reduced, so the vibration can be avoided. Subsequently, the vibration simulation is carried out to indicate that the magnet pattern can satisfy low level in vibration and noise of the machine.

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Location IoU: A New Evaluation and Loss for Bounding Box Regression in Object Detection

Location IoU: A New Evaluation and Loss for Bounding Box Reg...

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International Joint Conference on Neural Networks (IJCNN)

作者： Lu Yang Kai Zhang Jiaqi Liu Chongke Bi Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin China Autobrain (Tianjin) Technology LTD Tianjin China College of Intelligence and Computing Tianjin University Tianjin China

ISBN: (数字)9798350359312

ISBN: (纸本)9798350359329

In the field of object detection bounding box regression, IoU (Intersection over Union) is a commonly used evaluation metric for measuring the overlap between predicted and ground truth bounding boxes. One limitation of IoU, however, is that the gradient goes to zero when there is no intersection between bounding boxes. Recent evaluation metrics have been developed to overcome this problem by incorporating penalty terms and other techniques for improving IoU. Despite these advances, existing methods still suffer to some degree from the problems of small gradients and slow rate of convergence. In this paper, a new evaluation method named LIoU (Location IoU) is proposed to address these issues. It can maximize the shared area of the intersection when used as the loss function and incorporate a variable gradient parameter to fit to datasets of different sizes. The experimental results indicate that we achieve 0.27% and 3.48% accuracy improvements respectively in SSD and YOLOv5 network on the VOC dataset, and 2.23% in the YOLOv5 network on the COCO dataset. The results of this study highlight the effectiveness of LIoU in improving the performance of object detection models.

关键词： YOLO Measurement Location awareness Accuracy Shape Neural networks Benchmark testing

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Research on Oscillation Suppression Strategy for Grid-forming Power Systems Considering Wind-Energy Storage Coordination

Research on Oscillation Suppression Strategy for Grid-formin...

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Power science and technology (ICPST), IEEE International Conference on

作者： Rongrong Zhan Longhao Liu Sunhua Huang Linyun Xiong Yang Zhou Changyu Ban Luwei Wang National Key Laboratory of Power Grid Safety China Electric Power Research Institute Beijing China Shanghai University School of Mechatronic Engineering and Automation Shanghai China Chongqing University School of Electrical Engineering Chongqing China Changsha University of Science and Technology School of Electrical and Information Engineering Changsha China

ISBN: (数字)9798350349030

ISBN: (纸本)9798350349047

This paper addresses the oscillation problem in a wind-energy storage grid-forming power system and proposes a fractional-order predefined time sliding mode control (FOPTSMC) additional damping method with coordinated wind-energy storage consideration. Firstly, the dynamic models of the energy storage state of charge (SoC) and the grid-forming inverter based on VSG are established. Then, considering the coordinated operation between wind and energy storages, bidirectional droop control based on SoC weighting coefficients is employed to achieve SoC balance, and PI control is taken to guarantee DC voltage stability, respectively. Finally, FOPTSMC is proposed to suppress system oscillations, and the stability of the proposed control method is verified using the Lyapunov function. Simulation results validate the effectiveness of the proposed control method.

关键词： Wind energy Simulation Power system dynamics Power system stability Stability analysis Voltage control Oscillators

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Heterogeneous Aggregation of Carbon and Silicon Nanoparticles with Benzo[A]Pyrene Modulates Their Impacts on the Pulmonary Surfactant Film

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SSRN 2023年

作者： Wang, Wei Luo, Zhen Liu, Xia Dai, Yanhui Hu, Guoqing Zhao, Jian Yue, Tongtao Institute of Coastal Environmental Pollution Control Key Laboratory of Marine Environment and Ecology Ministry of Education Ocean University of China Qingdao266100 China Department of Engineering Mechanics State of Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Hangzhou310027 China Laboratory for Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and Technology Qingdao266237 China

Inhaled nanoparticles (NPs) can deposit in alveoli where they interact with the pulmonary surfactant (PS), potentially inducing toxicity. Although nano-bio interactions are influenced by the physicochemical properties of NPs, isolated NPs used in previous studies cannot accurately represent those found in atmosphere. Here we used molecular dynamics simulations to investigate the interplay between two types of NPs associated with benzo[a]pyrene (BaP) at the PS film. Silicon NPs (SiNPs), regardless of aggregation and adsorption, directly penetrated through the PS film with minimal disturbance. Meanwhile, BaPs adsorbed on SiNPs were rapidly solubilized by PS, increasing the BaP’s bioaccessibility in alveoli. Carbon NPs (CNPs) showed aggregation and adsorption-dependent effects on the PS film. Compared to isolated CNPs, which extracted PS to form biomolecular coronas, aggregated CNPs caused more pronounced PS disruption, especially around irregularly shaped edges. SiNPs in mixture exacerbated the CNP-induced PS perturbation by piercing PS film around the site of CNP interactions. BaPs adsorbed on CNPs were less solubilized and suppressed PS extraction, but aggravated biophysical inhibition and prompted film collapse under compression. These results suggest that for proper assessment of inhalation toxicity of airborne NPs, it is imperative to consider their heterogeneous aggregation and adsorption of pollutants under atmospheric conditions. © 2023, The Authors. All rights reserved.

关键词： Adsorption

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Exploration and Practice of Hierarchical Graduation Project under the Background of science Collaborative Education and engineering Education Accreditation 21

Exploration and Practice of Hierarchical Graduation Project ...

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Proceedings of the 5th International Conference on Advances in Artificial Intelligence

作者： Lilan Gao Yansong Tan Yanfang Sun Linwei Lv Bin Li Qijun Gao Xiaofei Wang Yijiao Zhao School of Mechanical Engineering_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 China School of Mechanical Engineering_Tianjin Key Laboratory for Advanced Mechatronic System Design and intelligent Control Tianjin University of Technology China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China

ISBN: (纸本)9781450390699

关键词： science collaborative education Hierarchical graduation project engineering education accreditation Education reform

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

SSRN

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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

SSRN

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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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