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Small-Target Infrastructure Detection with Spatial Tracking and Multi-Level Feature Extraction of Railway Track Scenes

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Small-Target Infrastructure Detection with Spatial Tracking ...

Intelligent Communication, Sensing and Electromagnetics (ICSE), International Conference on

作者： Heng Du Huaiming Cang Yiwen Bai Xinyi Wang Beijing Elephant Technology Co. Ltd Beijing China School of Transportation Science and Engineering Beihang University Beijing China The State Key Lab of Intelligent Transportation System Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354935

ISBN: (纸本)9798350354942

In the field of railway transportation, with the continuous improvement of train running speed and the continuous increase of operating mileage, it becomes particularly important to ensure the safety and integrity of small-target infrastructure along the railway train. Although many small-target detection methods have been proposed, the research on small-target infrastructure detection along rail trains is very rare. To solve this problem, this paper proposes a small-target infrastructure detection network with spatial tracking and multi-level feature extraction based on Yolov8n. The experimental results show that ST-YOLO has a 3.6% mAP improvement on the OSDaR23 dataset compared to the baseline Yolov8n, and shows significant advantages over other state-of-the-art methods.

关键词： Rails Transportation Railway safety Switches Feature extraction Rail transportation Real-time systems Sensors Safety Monitoring

Experimental Study on the Characteristics of Annular Fluid Film in a Locally Deformed Narrow Rectangular Channel

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SSRN 2024年

作者： Wang, Fenze Ren, Quanyao Liu, Haidong Xiao, Yi Chen, Deqi Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing400044 China Department of Nuclear Engineering and Technology School of Energy and Power Engineering Chongqing University Chongqing400044 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Liangjiang International College Chongqing University of Technology Chongqing401135 China Chongqing Research Institute of HIT Chongqing401151 China School of Flight Technology Civil Aviation Flight University of China Sichuan618307 China China

The study of the characteristics of the annular flow film in the narrow rectangular channel under the localized deformation can provide a research basis for the heat and mass transfer and the hydrodynamic characteristics of the locally deformed narrow flow channel. In this study, the annular flow liquid film characterization experiments are carried out in a narrow rectangular channel without local deformation, ellipsoidal deformation and pillow-shaped deformation, and different annular flow liquid film parameters liquid film thickness, disturbance wave height, and disturbance wave wavelength are obtained by high-speed camera acquisition system and intelligent image processing technology. Analyze the effects of flow conditions and local deformation on the liquid film parameters of each annular flow. Local deformation impact factor functions for liquid film thickness, disturbance wave height, and disturbance wave wavelength are obtained. The error of the impact factor function is within ±30%. © 2024, The Authors. All rights reserved.

关键词： Liquid films

Two-stage optimization model of emergency power supply for improving resilience of the distribution network under flood disaster 3

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Two-stage optimization model of emergency power supply for i...

3rd International Academic Exchange Conference on Science and technology Innovation, IAECST 2021

作者： Liu, Chao Zhou, Ping Zhou, Yongzhong Liao, Qinan Tang, Libo Tao, Anqi Wang, Qianggang Chongqing Electric Power Design Institute Company of Limited Liability Chongqing China Chongqing University State Key Laboratory of Power Transmission Equipment and System Safety and New Technology Chongqing China

ISBN: (纸本)9781665402675

Flood disaster will cause large area power outage of the distribution network, causing huge economic loss. Emergency power supply is an effective strategy to improve the ability of distribution network to deal with flood disaster. However, due to the limitation of flood water, it is difficult for emergency power to reach the accident site, so mobile emergency power needs to be configured in advance. In this paper, a two-stage optimization model of emergency power supply for improving the resilience of distribution network is proposed. Considering the vulnerability modeling of different equipment under flood disaster, multiple island micro-networks are formed by combining medium and low mobile emergency generators and network reconstruction, and power supply can be quickly restored according to load priority order. © 2021 IEEE.

关键词： Outages

Experimental Study on the Characteristics of Annular Fluid Film in a Locally Deformed Narrow Rectangular Channel

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SSRN 2024年

The local deformation of plate fuel assembly due to neutron irradiation will lead to the deterioration of heat transfer in the flow channel. Studying the characteristics of annular flow films in narrow rectangular channels under localized deformation provides a foundation for understanding the heat and mass transfer and the hydrodynamic characteristics of the locally deformed narrow flow channel. In this study, the annular flow liquid film characterization experiments were conducted in a narrow rectangular channel under three conditions: no local deformation, ellipsoidal deformation, and pillow-shaped deformation. Various parameters of the annular flow liquid films, including liquid film thickness, disturbance wave height, and disturbance wave wavelength, were obtained using a high-speed camera acquisition system and advanced image processing techniques. The effects of flow conditions and local deformation on the liquid film parameters of each annular flow were analyzed. As the radial size of the local deformation increases relative to the liquid film thickness, the viscous bottom layer of the liquid film disintegrates, resulting in a reduction of the total liquid film thickness. When the gas-phase velocity is low, the local deformation exerts a greater shear force on the disturbance wave, prolonging the action time and increasing the likelihood of wave disintegration. Under conditions of no channel deformation, the disturbance wave wavelength is negatively correlated with the gas-phase velocity;conversely, under localized channel deformation, the wavelength is positively correlated with the gas-phase velocity. Thus, the effect of localized deformation on wavelength is bidirectional. Local deformation impact factor functions for liquid film thickness, disturbance wave height, and disturbance wave wavelength have been derived, with the error of these impact factor functions maintained within ±30%. © 2024, The Authors. All rights reserved.

关键词： Neutron irradiation

Vibration simulation and test of shunt reactor under DC bias

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Vibration simulation and test of shunt reactor under DC bias

International Conference on Mechanical Engineering, Measurement Control, and Instrumentation 2021

作者： Zhou, Yuan Tian, Tian Yu, Xiongfei Ren, Ran Zhou, Liangcai Xu, Changjian Chongqing Electric Power Design Institute Co.Ltd Chongqing401121 China State Key Laboratory of Power Transmission Equipment &system Security and New Technology Chongqing400044 China

ISBN: (数字)9781510647299

ISBN: (纸本)9781510647282

Shunt reactor plays an important role in transmission system, which can provide reactive power compensation for transmission line and improve the quality of transmission line. But in the field operation, the shunt reactor will produce a large degree of vibration and noise, and even endanger the safety of indoor substation floor. Therefore, based on the vibration effect of shunt reactor, this paper puts forward the vibration variation law of shunt reactor under different DC bias. In this paper, the finite element model of reactor is built by COMSOL finite element simulation software to analyze the flux density distribution of reactor core under different direct flow injection, and then analyze the change trend of stress and strain. Then the reactor vibration test system is built on site, and the vibration acceleration curve of the reactor is collected and analyzed. The correctness of the reactor model is verified from the side. This study can provide a strong reference for the reactor vibration and noise reduction. © 2021 SPIE.

关键词： Electric lines

Sensitivity Study of Thermal Hydraulics to Corrosion of Heat Exchange Tubes in Steam Generator

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SSRN 2022年

作者： Wang, Weibing Cheng, Kun Wang, Bo Zhang, Meng Tian, Ruifeng College of Nuclear Science and Technology Harbin Engineering University Harbin150001 China Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150001 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

A leakage accident occurs in the circulating water system in PWRs, impurity ions enter the SG with the secondary circuit feed water and cause electrochemical corrosion of the heat transfer tubes(HTTs). Based on the hide out and return mathematical model in the SG, a coupled mathematical model of mass transfer-electromigration-hydrodynamics of impurity ions in the secondary boiling channel of SG is deduced. The accuracy of the mathematical model is verified by experiments, and the effects of heat flux density ( Pe q ), flow velocity ( Pe u ), impurity ion concentration ( Pe c ) and relative solubility of impurity ions ( K p ) on impurity ions migration and electrochemical corrosion are analyzed and discussed. The results show that P e q mainly controls the diffusion of impurity ions and thus affects the migration rate of impurity ions, and the mass transfer of impurity ions driven by Pe q can enhance the reduction of H + , thereby accelerating the corrosion rate of HTTs. The synergistic effect of convective mass transfer and electromigration during impurity ions migration is mainly affected by Pe u , and the electrochemical corrosion of the surface of HTTs is mainly controlled by charge transfer with the increase of Pe u . The Pe c on the surface of HTTs changes linearly with time, and the corrosion rate increases with the increase of Pe c . The corrosion rate of HTTs is proportional to K p , and K p is a main factor that causes different corrosion rates in different location of HTTs. In this paper, a coupled model for the sensitivity of thermal-hydraulic parameters ( Pe q , Pe u , Pe c and K p ) in SG to electrochemical corrosion of HTTs is proposed for the first time. The research results can provide important support for the development of corresponding response strategies, schemes for the life prediction of HTTs and the safety maintenance of nuclear power plants. © 2022, The Authors. All rights reserved.

关键词： Steam generators

EAN-MapNet: Efficient Vectorized HD Map Construction with Anchor Neighborhoods

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arXiv

arXiv 2024年

作者： Xiong, Huiyuan Shen, Jun Zhu, Taohong Pan, Yuelong School of Intelligent Systems Engineering Sun Yat-sen University China Guangdong Provincial Key Laboratory of Intelligent Transport System China China Nuclear Power Design Co. Ltd. China State Key Laboratory of Nuclear Power Safety Technology and Equipment China Nuclear Power Engineering Co. Ltd. Guangdong Shenzhen518172 China

High-definition (HD) map is crucial for autonomous driving systems. Most existing works design map elements detection heads based on the DETR decoder. However, the initial queries lack explicit incorporation of physical positional information, and vanilla self-attention entails high computational complexity. Therefore, we propose EAN-MapNet for Efficiently constructing HD map using Anchor Neighborhoods. Firstly, we design query units based on the anchor neighborhoods, allowing non-neighborhood central anchors to effectively assist in fitting the neighborhood central anchors to the target points representing map elements. Then, we propose grouped local self-attention (GL-SA) by leveraging the relative instance relationship among the queries. This facilitates direct feature interaction among queries of the same instances, while innovatively employing local queries as intermediaries for interaction among queries from different instances. Consequently, GL-SA significantly reduces the computational complexity of self-attention while ensuring ample feature interaction among queries. On the nuScenes dataset, EAN-MapNet achieves a state-of-the-art performance with 63.0 mAP after training for 24 epochs, surpassing MapTR by 12.7 mAP. Furthermore, it considerably reduces memory consumption by 8198M compared to MapTRv2. Copyright © 2024, The Authors. All rights reserved.

关键词： Computational complexity

Predicting Reverse Flow Characteristics in Equal-Height-Difference Passive Heat Removal system for Ocean Nuclear Power

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SSRN 2022年

作者： Wang, Zhiwei He, Yanping Duan, Zhongdi Huang, Chao Li, Mingzhi Liu, Shiwen Hao, Chengming State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China Institute of Marine Equipment Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The equal-height-difference passive heat removal system (EHDPHRS) via natural circulation driving and utilizes ocean as infinite heat sink for heat dissipation, showing broad application prospect in ocean nuclear power field;but the heat removal pipe normally encounters the reverse flow of the cold seawater into the pipe, leading to operation instability and even condensation-induced water hammer. In this study, the integration of the volume of fluid model and the condensation model based on surface renewal theory is used to simulate the reverse flow characteristics in heat removal pipe under single-and two-phase natural circulation conditions. The interfacial heat and mass transfer are calculated by user-defined functions. The numerical results reveal that the buoyancy force ( [[EQUATION]] ) and condensation driving force ( [[EQUATION]] ) both accelerate the reverse flow, while the inertial force ( [[EQUATION]] ) restrains the reverse flow;the reverse flow length presents monotonous decrease with increasing flow velocity under single-phase conditions and parabolic-like trend for two-phase flow. A prediction correlation for reverse length is developed using dimensionless Reynolds number, Grashof number and vapor volume fraction, covering single- and two-phase conditions. The predicted reverse length by the correlation agrees with 94% of the results within deviations of [[EQUATION]] 15%. © 2022, The Authors. All rights reserved.

关键词： Forecasting

Explicit design optimization of air rudders for maximizing stiffness and fundamental frequency

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arXiv

arXiv 2024年

作者： Jia, Yibo Meng, Wen Du, Zongliang Liu, Chang Li, Shanwei Wang, Conglei Ge, Zhifu Su, Ruiyi Guo, Xu State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian116023 China Ningbo Institute of Dalian University of Technology Ningbo315016 China Beijing System Design Institute of Electro-Mechanic Engineering Beijing100854 China

In aerospace engineering, there is a growing demand for lightweight design through topology optimization. This paper presents a novel design optimization method for stiffened air rudders, commonly used for aircraft attitude control, based on the Moving Morphable Components (MMC) method. The stiffeners within the irregular enclosed design domain are modeled as MMCs and discretized by shell elements, accurately capturing their geometry and evolution during optimization process using explicit parameters. In order to maximize the stiffness and fundamental frequency of the rudder structures, numerical analysis algorithms were developed with shape sensitivity analysis conducted. To comply with the manufacturing requirement, a minimum thickness is prescribed for the stiffeners. Penalty strategies were developed for the thickness and density of stiffeners with thickness smaller than the threshold to meet the thickness requirement and suppress spurious modes. The method's effectiveness was demonstrated through optimization examples of two typical air rudders, illustrating the significance of stiffener’s distribution on design objectives. The explicit modeling characteristics allow for directly importing the optimization results into CAD systems, significantly enhancing the engineering applicability. Copyright © 2024, The Authors. All rights reserved.

关键词： Stiffness