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An Adaptive Physics-Informed Neural Network with Two-Stage Learning Strategy to Solve Partial Differential Equations

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numerical Mathematics(Theory,Methods and Applications) 2023年第2期16卷 298-322页

作者： Shuyan Shi Ding Liu Ruirui Ji Yuchao Han School of Automation and Information Engineering Xi‘an University of TechnologyXi‘an 710048P.R.China National&Local Joint Engineering Research Center of Crystal Growth Equipment and System Integration Xi‘an 710048P.R.China Xi’an University of Technology Shannxi Key Laboratory of Complex System Control and Intelligent Information ProcessingXi‘an 710048P.R.China

Physics-Informed Neural Network(PINN)represents a new approach to solve Partial Differential Equations(PDEs).PINNs aim to solve PDEs by integrating governing equations and the initial/boundary conditions(I/BCs)into a loss ***,the imbalance of the loss function caused by parameter settings usually makes it difficult for PINNs to converge,*** they fall into local *** other words,the presence of balanced PDE loss,initial loss and boundary loss may be critical for the *** addition,existing PINNs are not able to reveal the hidden errors caused by non-convergent boundaries and conduction errors caused by the PDE near the ***,these problems have made PINN-based methods of limited use on practical *** this paper,we propose a novel physics-informed neural network,*** adaptive physics-informed neural network with a two-stage training *** algorithm adds spatio-temporal coefficient and PDE balance parameter to the loss function,and solve PDEs using a two-stage training process:pre-training and formal *** pre-training step ensures the convergence of boundary loss,whereas the formal training process completes the solution of PDE by balancing various loss *** order to verify the performance of our method,we consider the imbalanced heat conduction and Helmholtz equations often appearing in practical *** Klein-Gordon equation,which is widely used to compare performance,reveals that our method is able to reduce the hidden *** results confirm that our algorithm can effectively and accurately solve models with unbalanced loss function,hidden errors and conduction *** codes developed in this manuscript are publicy available at https://***/callmedrcom/ATPINN.

关键词： Physics informed neural networks partial differential equations two-stage learning scientific computing

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Color liquid crystal grating based color holographic 3D display system with large viewing angle

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Light(Science & Applications) 2024年第1期13卷 103-112页

作者： Di Wang Yi-Long Li Fan Chu Nan-Nan Li Zhao-Song Li Sin-Doo Lee Zhong-Quan Nie Chao Liu Qiong-Hua Wang School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China Display Technology Research Center Seoul National UniversityGwanak-ro 1Gwanak-guSeoul 08826Republic of Korea Key Lab of Advanced Transducers and Intelligent Control System Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China

Holographic 3D display is highly desirable for numerous applications ranging from medical treatments to military ***,it is challenging to simultaneously achieve large viewing angle and high-fidelity color reconstruction due to the intractable constraints of existing ***,we conceptually propose and experimentally demonstrate a simple and feasible pathway of using a well-designed color liquid crystal grating to overcome the inevitable chromatic aberration and enlarge the holographic viewing angle,thus enabling large-viewing-angle and color holographic 3D *** use of color liquid crystal grating allows performing secondary diffraction modulation on red,green and blue reproduced images simultaneously and extending the viewing angle in the holographic 3D display *** principle,a chromatic aberration-free hologram generation mechanism in combination with the color liquid crystal grating is proposed to pave the way for on such a superior holographic 3D *** proposed system shows a color viewing angle of~50.12°,which is about 7 times that of the traditional system with a single spatial light *** work presents a paradigm for achieving desirable holographic 3D display,and is expected to provide a new way for the wide application of holographic display.

关键词： holographic angle crystal

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research on workflow recognition for liver rupture repair surgery

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Mathematical Biosciences and engineering 2024年第2期21卷 1844-1856页

作者： Men, Yutao Zhao, Zixian Chen, Wei Wu, Hang Zhang, Guang Luo, Feng Yu, Ming Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China Medical Support Technology Research Department Systems Engineering Institute Academy of Military Sciences People’s Liberation Army Tianjin300161 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China

Liver rupture repair surgery serves as one tool to treat liver rupture, especially beneficial for cases of mild liver rupture hemorrhage. Liver rupture can catalyze critical conditions such as hemorrhage and shock. Surgical workflow recognition in liver rupture repair surgery videos presents a significant task aimed at reducing surgical mistakes and enhancing the quality of surgeries conducted by surgeons. A liver rupture repair simulation surgical dataset is proposed in this paper which consists of 45 videos collaboratively completed by nine surgeons. Furthermore, an end-to-end SA-RLNet, a self attention-based recurrent convolutional neural network, is introduced in this paper. The self-attention mechanism is used to automatically identify the importance of input features in various instances and associate the relationships between input features. The accuracy of the surgical phase classification of the SA-RLNet approach is 90.6%. The present study demonstrates that the SA-RLNet approach shows strong generalization capabilities on the dataset. SA-RLNet has proved to be advantageous in capturing subtle variations between surgical phases. The application of surgical workflow recognition has promising feasibility in liver rupture repair surgery. ©2024 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons.

关键词： Image classification

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Face Detection on Thermal Infrared Images Combined with Visible Images 16th

Face Detection on Thermal Infrared Images Combined with Visi...

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16th International Conference on Bio-Inspired Computing: Theories and Applications, BIC-TA 2021

作者： Chen, Yujia Wang, Liqing Xu, Guangda School of Mathematics and Statistics Xi’an Jiaotong University Xi’an China Infrared Division Wuhan Huazhong Numerical Control Co. Ltd. Wuhan China National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9789811912528

Due to COVID-19, intelligent thermal imagers are widely used all over the world. Since intelligent thermal imagers usually require real-time temperature measurement, it is significant to find a method to quickly and accurately detect human faces in thermal infrared images. This paper mainly proposes two different methods. One is to use image processing methods and face detected from visible images to determine the position of the face in the infrared image, while the other is to use target detection algorithms on infrared images, including YOLOv3 and Faster R-CNN. This paper uses the two methods on a self-collected dataset containing 944 pairs of visible and infrared images and observes the robustness of methods by adding random noise to images. Experiments show that the first one has much lower latency and the latter one has higher accuracy in both cases. © 2022, Springer Nature Singapore Pte Ltd.

关键词： Face recognition

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Quasi-Parallel Resonant Switched Capacitor DC-DC Converter with Continuous Voltage Regulation Capability

Quasi-Parallel Resonant Switched Capacitor DC-DC Converter w...

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2024 IEEE Energy Conversion Congress and Exposition, ECCE 2024

作者： Qi, Jingjing Wu, Xuezhi Xu, Wenzheng Sun, Kai Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing China Beijing Jiaotong University National Active Distribution Network Technology Research Center Beijing China

ISBN: (纸本)9798350376067

Resonant switched capacitor converters have the advantages of small size, light weight and high efficiency, but have poor voltage regulation ability. To overcome this problem, a quasi-parallel resonant switched capacitor DC-DC converter is proposed in this paper, which mainly incorporates a resonant switched capacitor converter with soft-switching and variable voltage ratio and a Buck converter. Most of the power can be transmitted by the resonant switched capacitor converter, while the Buck converter is responsible for output voltage regulation. In addition, the voltage ratio of the resonant switched capacitor converter can be flexibly changed base on the input voltage, which is beneficial for Buck converter to always handle a small portion of power. Furthermore, input voltage feedforward control is incorporated to suppress the input voltage disturbance. The proposed converter can not only continuously regulate the voltage over a wide range, but also perform high efficiency and achieve rapid dynamic response. The operating principle of the converter is introduced, the circuit characteristic is analyzed, and the correctness of the theoretical analysis is verified by experiments. © 2024 IEEE.

关键词： Capacitor bank

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Trajectory Prediction of High-Speed Train Group Tracking Based on LSTM-KF Hybrid Model 27

Trajectory Prediction of High-Speed Train Group Tracking Bas...

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27th IEEE International Conference on Intelligent Transportation systems, ITSC 2024

作者： Yang, Boyu Lv, Jidong Liu, Hongjie Chai, Ming Zhang, Qinglong Tang, Tao Lv, Jiahui National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University Beijing China School of Civil and Resource Engineering University of Science and Technology Beijing China Beijing Jiaotong University The Associate Director of the Rail Traffic Control and Safety State Key Laboratory China

ISBN: (纸本)9798331505929

Operating multiple trains as a group under Train-to-Train communication is an efficient way in sparse railway networks. However, it is a barrier to accurate tracking for follower trains with the uncertain status of the preceding trains under communication delay. Therefore, we proposed a train trajectory prediction approach, aiming to obtain an accurate state of preceeding trains in a long time horizon. Firstly, we established a hybrid prediction model combined Long Short-Term Memory (LSTM) with the Kalman Filter (KF) and using the sliding window mechanism to enhance future prediction accuracy. Secondly, to fusion LSTM prediction data and the Kalman calculation model, we proposed the Hybrid Train Trajectory Prediction algorithm by adopting real-time calculation of the covariance matrix using real data and predicted data. Finally, we apply an experiment considering network characteristics in Western China. The result shows that the Mean Absolute Error (MAE) of series prediction in the longer time domain is 44% of the Recurrent Neural Network (RNN) model and 88% of the traditional LSTM model. © 2024 IEEE.

关键词： Kalman filters

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A Model Predictive control Approach for Virtually Coupled Train Set Based on Multi-Phase Trajectory Planning 21

A Model Predictive Control Approach for Virtually Coupled Tr...

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21st International Conference on Networking, Sensing and control, ICNSC 2024

作者： Li, Bosi Liu, Hongjie Lang, Yinghui Jia, Qingdong Zhang, Kun Li, Kaixuan School of Automation and Intelligence Beijing Jiaotong University Beijing100044 China Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing100044 China Traffic Control Technology Co. Ltd. Beijing100070 China

ISBN: (纸本)9798350365221

Virtual coupling (VC) is an emerging technology that enhances railway operations by dynamically and accurately matching line capacity with passenger demand. However, challenges arise in coordinating the virtually coupled train set (VCTS) during inter-station operations and maintaining accurate control of the VCTS. To address this issue, we propose a multi-phase trajectory planning control approach to generate the reference trajectories for VCTS to enhance the synchronicity of interstation operations. However, during speed-varying inter-station operations, it remains challenging to control VCTS accurately under disturbances while adhering to safety constraints. The control layer employs a model predictive control (MPC) approach to ensure precise reference tracking, based on the optimized reference trajectories for all train units. The effectiveness of this approach is validated through experimental results. © 2024 IEEE.

关键词： Predictive control systems

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Progress in models for coupled human and natural systems

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Science China Earth Sciences 2024年第11期67卷 3631-3637页

作者： Tianxiang YUE Chenchen WU Wenjiao SHI Yongzhong TIAN Qing WANG Yimin LU Lili ZHANG State Key Laboratory of Resources and Environment Information System Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 101408China School of Geographical Sciences Southwest UniversityChongqing 400715China National Institute of Environmental Health Chinese Center for Disease Control and PreventionBeijing 100021China National Engineering Research Center of Geospatial Information Technology Fuzhou UniversityFuzhou 350108China The Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China

1. Introduction Malthus (1798) was one of the earliest researchers to propose a coupled human-natural system (CHANS) model, particularly in his analysis of the relationship between population growth and food supply. He argued that while population grows geometrically, food supply increases only arithmetically, suggesting that this imbalance could eventually lead to a food crisis due to diminishing per capita food availability (Malthus, 1798).

关键词： Malthus eventually population

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Fault Diagnosis of On-board Equipment in CTCS-3 Based on CNN-LSTM Model

Fault Diagnosis of On-board Equipment in CTCS-3 Based on CNN...

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2022 Chinese Automation Congress, CAC 2022

作者： Zhang, Daqian Cao, Yuan Zhang, Miao Chai, Ming Lv, Jidong Beijing Jiaotong University National Engineering Research Center of Rail Transportation Operation and Control System Beijing China China Academy of Railway Sciences Corporation Limited National Research Center of Railway Intelligence Transportation System Engineering Technology Beijing China

ISBN: (纸本)9781665465335

Data-driven methods based on deep learning have achieved remarkable results of fault diagnosis of train control system due to their superiority in feature extraction. However, it still faces uneven data distribution problem, which afects the detection accuracy of fault diagnosis. In this paper, by considering different failures both in system and subsystem level of train control system, we propose a novel two-stages fault diagnosis method based on a combination of Convolutional Neural Network (CNN) and Long Short-Term Memory Network (LSTM). Firstly, samples are obtained by segmenting and vectorizing the text form faulty data set, and fed into the proposed CNN-LSTM model. Then, in the first stage, the features of the processed data are extracted through the CNN layer, whereas the correlation between the sample data are derived through the LSTM layer. Thus, the classification of first-level faults, respect as system level, are realized with high accuracy of diagnosis. Finally, in the second stage, to solve the problem of data imbalance, we reconsider part of data from the CNN layer, and put them into the new LSTM layer for secondary faults diagnosis. We apply this method on a real CTCS-3 On-board equipment and the experimental results show that the accuracy rate of our proposed model reaches 96.7% and the accuracy of small data faults is also higher when compare with other neural network models,such as TextCNN, ANN, LSTM and RNN. © 2022 IEEE.

关键词： Failure analysis

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Development of a PLCopen-Based controller for Flexible Fatigue Test Applications

Development of a PLCopen-Based Controller for Flexible Fatig...

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International Conference on Mechatronics and Machine Vision in Practice (M2VIP)

作者： Xiaofan Lyu Pingjiang Wang Chaoyang Gao Donglin Zhao Peng Wei Wenbin Luo School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan China Quanzhou HUST Research Institute of Intelligent Manufacturing QuanZhou China

ISBN: (数字)9798350391916

ISBN: (纸本)9798350391923

Aiming at the flexibility and reconfigurability needs for fatigue test applications, the demand for a PLCopen-based development framework arises. In this study, we utilize the IEC 61131-3 programmable language and PLCopen specifications to design the controller for electro-hydraulic servo loading system. Firstly, PLCopen group function block diagrams are proposed in accordance with experiments. Multiple groups can manage different experiments simultaneously. Then, PLCopen channel function block diagrams are designed to manage district channels in a group. To correct tracking errors, each channel incorporates a peak-valley phase compensator. Peak-valley phase compensator could potentially be used to adjust for multi-frequency sinusoidal spectrum. Finally, simulation and experiment results verify that tracking error could be kept within a defined neighbourhood region.

关键词： Mechatronics Machine vision Loading Fatigue IEC Standards Servomotors

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