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Dictionary-Labeled A∗: Optimal Path-and-Posture Planning for Mobile Robots with Turning Radius Constraints

IEEE Robotics and Automation Letters 2024年第12期9卷 10740-10747页

作者： Yang, Chen Lin, Zhiyun Southern University of Science and Technology School of System Design and Intelligent Manufacturing Shenzhen518055 China Southern University of Science and Technology Shenzhen Key Laboratory of Control Theory and Intelligent Systems Shenzhen518055 China Peng Cheng Laboratory Shenzhen518066 China

In this study, we introduce an algorithm called Dictionary-Labeled A∗ (DL-A∗), which addresses the critical problem of path-and-posture planning for mobile robots with turning radius constraints. DL-A∗ utilizes a dictionary to store and process multi-element information within an enhanced topological map. The algorithm categorizes the edges in the map into forward driving and reverse driving states, and constructs sets of successive states that adhere to road segment constraints through map pre-processing. Subsequently, the A∗ algorithm is employed to find an optimal path to reach the endpoint while satisfying the end posture constraint, with the objective of minimizing the total travelling cost. Simulation results demonstrate that, in comparison to other popular algorithms, our algorithm offers the capability to adapt the robot's forward and reverse driving postures to minimize total cost, and exhibits exceptional searching efficiency. © 2016 IEEE.

关键词： Robot programming

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UAV-Assisted Dynamic Avatar Task Migration for Vehicular Metaverse Services: A Multi-Agent Deep Reinforcement Learning Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 430-445页

作者： Jiawen Kang Junlong Chen Minrui Xu Zehui Xiong Yutao Jiao Luchao Han Dusit Niyato Yongju Tong Shengli Xie IEEE School of Automation Guangdong University of TechnologyGuangzhou 510006China 111 Center for Intelligent Batch Manufacturing based on IoT Technology Guangzhou 510006China Key Laboratory of Intelligent Information Processing and System Integration of IoT Ministry of EducationGuangzhou 510006China School of Computer Science and Engineering Nanyang Technological UniversitySingaporeSingapore Pillar of Information Systems Technology and Design Singapore University of Technology and DesignSingaporeSingapore College of Communication Engineering Army Engineering University of PLANanjing 210007China National Natural Science Foundation of China Beijing 100085China Key Laboratory of Intelligent Detection and IoT in Manufacturing Ministry of EducationGuangzhou 510006China Guangdong Key Laboratory of IoT Information Technology Guangzhou 510006China

Avatars, as promising digital representations and service assistants of users in Metaverses, can enable drivers and passengers to immerse themselves in 3D virtual services and spaces of UAV-assisted vehicular Metaverses. However, avatar tasks include a multitude of human-to-avatar and avatar-to-avatar interactive applications, e.g., augmented reality navigation,which consumes intensive computing resources. It is inefficient and impractical for vehicles to process avatar tasks locally. Fortunately, migrating avatar tasks to the nearest roadside units(RSU)or unmanned aerial vehicles(UAV) for execution is a promising solution to decrease computation overhead and reduce task processing latency, while the high mobility of vehicles brings challenges for vehicles to independently perform avatar migration decisions depending on current and future vehicle status. To address these challenges, in this paper, we propose a novel avatar task migration system based on multi-agent deep reinforcement learning(MADRL) to execute immersive vehicular avatar tasks dynamically. Specifically, we first formulate the problem of avatar task migration from vehicles to RSUs/UAVs as a partially observable Markov decision process that can be solved by MADRL algorithms. We then design the multi-agent proximal policy optimization(MAPPO) approach as the MADRL algorithm for the avatar task migration problem. To overcome slow convergence resulting from the curse of dimensionality and non-stationary issues caused by shared parameters in MAPPO, we further propose a transformer-based MAPPO approach via sequential decision-making models for the efficient representation of relationships among agents. Finally, to motivate terrestrial or non-terrestrial edge servers(e.g., RSUs or UAVs) to share computation resources and ensure traceability of the sharing records, we apply smart contracts and blockchain technologies to achieve secure sharing management. Numerical results demonstrate that the proposed approach

关键词： Avatar blockchain metaverses multi-agent deep reinforcement learning transformer UAVs

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Study on the Influence of reactor system LOCA Modeling Mode on Dynamic Analysis 23rd

Study on the Influence of Reactor System LOCA Modeling Mode ...

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23rd Pacific Basin Nuclear Conference, PBNC 2022

作者： Shuai, Liu Xuan, Huang Zhipeng, Feng Zhongxiu, Zeng Huanhuan, Qi Xiaozhou, Jiang Harbin Engineering University Harbin China Science and Technology on Reactor System Design Technology Laboratory Sichuan Chengdu China

ISBN: (纸本)9789811987793

The reactor system has a large scale of components. And the system dynamic analysis model for loss of coolant accidents (LOCA) contains many non-linear factors. The transient calculation analysis takes a long time and the convergence is difficult to guarantee. In this paper, two different analysis models (complete three-loop model and single-loop model) of the first loop system of reactor are established for comparative analysis. The analysis shows that the calculation error of the main position load in the two different model is within 10%. The decoupling influence of the wave tube and the reactor inlet and outlet on the system dynamic characteristics is within an acceptable range. When the single loop model is used, it is necessary to decouple the reactor pressure vessel and pressurizer. And the simplified boundary is adapted to simulate its effect on the whole loop. The single-loop dynamic analysis model based on the decoupling criterion can greatly reduce the calculation scale and meet the calculation accuracy, which can be used to calculate the LOCA dynamic characteristics of the reactor system quickly. The model can also be used for seismic analysis of reactor system. And using this model for reactor system dynamic analysis can greatly improve the calculation efficiency. Please copy you summary here. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Loss of coolant accidents

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Preliminary Development of a Simulation Capability for Zircaloy Clad Ballooning in LOCA

Preliminary Development of a Simulation Capability for Zirca...

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International Conference on Water reactor Fuel Performance Meeting, WRFPM 2023

作者： Li, A. Wei Wu, B. Xiaoli State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

ISBN: (纸本)9789819971565

Zircaloy clad is widely known to be vulnerable to ballooning and burst in a loss-of-coolant accident (LOCA) typical of high-temperature steam environment, due to internal and external pressure difference and degraded strength. Ballooning can be detrimental in light of nuclear reactor safety. Due to the large deformation and complex constitute models in the ballooning process, detailed numerical simulation of Zircaloy clad ballooning has long been a challenge. This paper presented a preliminary Finite-Element-Method (FEM) implementation for analyzing Zircaloy clad ballooning. The developed capability can be used to predict progressive clad ballooning up to failure determined by empirical burst limit. Included physic models are currently phase transformation and high-temperature creep. Especially, anisotropic creep was considered for the α phase Zircaloy. The stress update algorithm is implicit in time integration, which ensures relatively large time increment during the simulation. The PUZRY separate effect tests were used to validate the FEM capability. The predicted time to failure (burst) is acceptable when compared with the experimental data. Besides, it was found that the effect of anisotropic coefficients is significant on the prediction of ballooning. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2024.

关键词： Loss of coolant accidents

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Fault Severity Classification based on Information Flow and Support Vector Machines 8

Fault Severity Classification based on Information Flow and ...

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8th International Conference on Energy system, Electricity, and Power, ESEP 2023

作者： Yang, Xiaohua Liu, Zhikun Fang, Weiyang Huang, Tao Liu, Jie Yang, Jinghua Ren, Changan Department of Compute Science University of South China Hengyang421001 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

ISBN: (数字)9781510679801

ISBN: (纸本)9781510679795

Fault severity describes the level of impact caused by a fault. In the event of a malfunction in a nuclear power plant, a vast amount of data and alarms are generated, making it challenging for operators to identify and determine the state of the power plant in a short time. If the fault severity can be effectively identified during a malfunction, it would allow the operators to respond quickly and prevent further losses. Compared to other machine learning methods, the Support Vector Machine (SVM) has superior classification capability in scenarios with limited nuclear power samples. However, if the feature representation of the SVM training sample is inadequate, resulting in similar, indistinguishable training data, it will affect the SVM's classification of fault severity. To address this issue, using the Liang-Kleeman Information Flow (IF) can characterize information transmission from a causal perspective. By introducing IF to combine features of the training data, insufficient sample features can be replaced with the IF that describes information from a causal viewpoint, thereby enhancing the SVM's accuracy in fault severity classification. This paper takes the Main Steam Line Break accident in the primary loop of the nuclear reactor as an example and conducts simulation experiments on the PCTRAN simulation platform. The experimental results show that under 5 different fault degrees, the accuracy of fault degree evaluation of SVM model combined with IF is improved. This method can effectively improve the classification accuracy of different fault severity degrees in MSLB steam flow data with similar changes. © 2024 SPIE.

关键词： Steam piping systems

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Emergent antisymmetric wrinkling patterns in films on ridged substrates

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science china(Physics,Mechanics & Astronomy) 2023年第11期66卷 179-187页

作者： Jiahui Zhang Yi Sun Linghui He Yong Ni CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei230026China

We report the formation of antisymmetric wrinkling patterns in films on ridged substrates induced by the buckling instability of the substrates via finite element simulations and *** simulated results reveal that the uniaxial compression along the ridge can trigger both the wrinkling instability of the film and the lateral buckling instability of the *** latter could change the wrinkles from a symmetric pattern to an antisymmetric pattern in a range of film-substrate modulus ratio and aspect ratio of the ridge profile,as validated by the experimental observations.A three-dimensional phase diagram with four buckling patterns,i.e.,sole ridge buckling pattern,antisymmetric wrinkling pattern with different wavelengths from ridge buckling,symmetric wrinkling pattern without ridge buckling,and antisymmetric wrinkling pattern with the same wavelength as ridge buckling,is built with respect to the uniaxial compression,modulus ratio,and aspect *** results not only elucidate how and when the interplay between the wrinkling instability and the ridge instability results in the formation of the antisymmetric wrinkling pattern but also offer a way to generate controllable complex wrinkling patterns.

关键词： wrinkling pattern buckling instability ridged film-substrate system antisymmetric wrinkles

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Study on the characteristics of aerosol diffusiophoresis deposition on the outer surface of a vertical circular tube

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International Journal of Advanced Nuclear reactor design and technology 2024年第3期6卷 212-221页

作者： Chen, Junyan Tian, Chao Cheng, Shisi Gu, Haifeng Ying, Dongchuan Zhai, Zian National Key Laboratory of Nuclear Reactor Technology Nuclear Power Institute of China Chengdu610213 China Nuclear Power Institute of China Chengdu610213 China Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150006 China

The deposition behavior of aerosols due to diffusiophoresis directly influences the migration and deposition of radioactive materials following an accident. This is critical in analyzing source term migration and the precise evaluation of radiological consequences for personnel. Several aerosol deposition experiments were conducted under steam condensation conditions on the external surface of the cooling tube to investigate the diffusiophoresis deposition characteristics of particles in the containment vessel when the PCS system is activated. The experiments demonstrated that the diffusiophoresis deposition rate on the external surface of the cooling tube decreases with increasing steam density but increases with the rise in steam volume fraction. Theoretical analysis combined with data extraction techniques determined the aerosol concentration decay rate on the external surface of the cooling tube under the sole influence of diffusiophoresis. An improved diffusiophoresis deposition model incorporating suction effects was proposed based on relevant heat transfer studies involving non-condensable gases. The comparison of model results showed that the deviation between the improved model and experimental values is within ±10 %, outperforming the predictions of the original model. According to the improved model and experimental results, it was found that a 38 mm tube diameter is more susceptible to the accumulation of incondensable gases, and the suction effect has a more significant promoting influence on diffusiophoresis deposition compared to a 19 mm tube diameter. © 2025 Xi'an Jiaotong University

关键词： Steam

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Experimental Study on Startup Characteristics of Sodium Heat Pipe with Large Length-diameter Ratio 12

Experimental Study on Startup Characteristics of Sodium Heat...

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12th Academic Conference of Geology Resource Management and Sustainable Development, GRMSD 2024

作者： Li, Wenjun Zhang, Zhuohua Su, Dongchuan Wu, Ge Tang, Qizhong Wu, Junjie College of Chemical Safety North China Institute of Science and Technology Hebei Sanhe065201 China Key Laboratory of Nuclear Reactor System Design Technology Nuclear Power Research and Design Institute of China Sichuan Chengdu610213 China

ISBN: (纸本)9798331314545

Underground in-situ pyrolysis of oil-rich coal can extract oil and gas resources in coal, which is an important measure for clean and low-carbon utilization of coal resources. The efficiency and energy consumption of underground in-situ pyrolysis of oil-rich coal depend on the heating equipment. The sodium heat pipe with large length-diameter ratio can complete the efficient long-distance heat transfer at high temperature, and has broad application prospects in the field of underground in-situ pyrolysis of oil-rich coal. Compared with the conventional high temperature heat pipe, the evaporation section of the sodium heat pipe with large length-diameter ratio is more likely to burn out during cold start-up, which leads to the failure of cold start-up. Therefore, for the sodium heat pipe with an aspect ratio of 115 (outer diameter D = 20 mm, axial length L = 2300 mm), the start-up characteristics of sodium heat pipes with three filling rates (5 %, 10 %, 15 %) under different heating powers were investigated. The results show that with the increase of the filling rate, the longer the start-up time of the sodium heat pipe with large length-diameter ratio, the more likely it is to produce temperature oscillation. Increasing the heating power can reduce the start-up time gap of the three liquid-filled sodium heat pipes, weaken the temperature oscillation phenomenon, and improve the temperature uniformity and steady-state operating temperature of the sodium heat pipe with large length-diameter ratio. In addition, the decrease of the filling rate of sodium with large length-diameter ratio and the increase of heating power can reduce the equivalent thermal resistance of sodium heat pipe with large length-diameter ratio, and improve the start-up characteristics and heat transfer effect of sodium heat pipe with large length-diameter ratio. When the heating power is 3.5 kW, the start-up time of sodium heat pipe with 5 % filling rate is as low as 450 s. © 2024 Proceedings of the

关键词： Coal deposits

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A Transformer-based Time Series Prediction Model with Contrastive Learning for Nuclear Power system State Monitoring 15

A Transformer-based Time Series Prediction Model with Contra...

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15th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Beijing 2024

作者： Gou, Pengfei Zheng, Daiwei Tang, Lei Liu, Mengjuan School of Information and Software Engineering University of Electronic Science and Technology of China UESTC Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China NPIC Chengdu China

ISBN: (纸本)9798350354010

Prognostics and Health Management (PHM) is currently the mainstream solution for the condition monitoring and maintenance of industrial systems. In PHM, the system condition is monitored by monitoring the operational status parameters of the system to diagnose equipment faults, predict the remaining useful life, etc. Utilizing sequential operational status parameters to complete prediction and classification tasks is usually modeled as a time series processing task. Therefore, a high-performance time series prediction model is crucial for PHM. This paper focuses on the use of time series prediction models to achieve the prediction of key state parameters of the nuclear power system. However, there are still some challenges when directly applying existing time series prediction models to industrial systems. First, obtaining operational data on the nuclear power system is relatively difficult, resulting in a small amount of training data, which causes many models to face the risk of insufficient training or overfitting. Second, most of the existing time series prediction models are composed of high- and low-frequency decoupling modules, while the operational data of nuclear power systems often have fewer high-frequency components, making it difficult for many existing SOTA models to achieve good results. In order to address these challenges, we have developed a Transformer-based time series prediction model with contrastive learning for monitoring the status of nuclear power systems. We evaluated the new model on three nuclear power simulation datasets and four power transformer datasets. The experimental results show that the new model's performance is superior to baseline models. We also proved the effectiveness of our improvement through ablation experiments. © 2024 IEEE.

关键词： Prediction models

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Simulation Method for Multiscale Failure of Optocoupler Based on Aging of Solder Layer in Photovoltaic MOSFET 2

Simulation Method for Multiscale Failure of Optocoupler Base...

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2nd IEEE International Power Electronics and Application Symposium, PEAS 2023

作者： Chen, Xuan Yao, Ran Li, Hui Lai, Wei Min, Yuan Yang, Cheng Duan, Zeyu Chen, Siyu Xing, Zhen Chongqing University State Key Laboratory of Power Transmission Equipment Technology Chongqing China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China

ISBN: (纸本)9798350313765

This paper presents a simulation method for investigating the failure of optocoupler equipment (OCEP) in multi-physical fields. The method is based on the aging of the solder layer of the photosensitive field-effect tube (PFET) and aims to analyze the performance degradation of the PFET. Firstly, a comprehensive multi-physical field model of the OCEP is developed using the actual structure of the CT test OCEP, taking into account the conductivity of the chip. Next, an OCEP failure simulation method is proposed, which takes into account the shedding of the PFET solder layer caused by the failure mechanism of the OCEP. Finally, the simulation results demonstrate that the degree of solder layer shedding reaches 70%, resulting in the failure of the OCEP. © 2023 IEEE.

关键词： multi-physics modeling optocoupler solder layer failure

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