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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Yin, Chunyu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China No.328 section 1 changshun avenue Chengdu China

ISBN: (纸本)9780791883761

SiC has become a candidate cladding material of Accident Tolerant Fuels (ATF) due to its excellent irradiation stability and corrosion resistance. However, because SiC is a ceramic material with low toughness, brittle failure is a significant concern. In order to improve the toughness, SiC fiber is required to manufacture multi-layer SiC composites. But the current performance model or analysis tool is not available for SiC composites cladding due to its obviously difference with Zr alloy cladding. On one side, Finite element method was used in this paper to analyze the performance of SiC composites cladding under operation conditions which include normal, transient conditions and LOCA conditions;on the other side, this paper gives the performance of the SiC composites with two layers under multiple operating conditions. The result showed that the temperature was stable and the maximum hoop stress was reached at about 70d under normal condition. The power ramp can increase the cladding temperature and has visible influence on the stress distribution. The hoop stress of the cladding reversed under LOCA condition. The tensile hoop stress on the outer surface significantly increased, which caused the obvious increase of failure probability of monolithic SiC, and the failure probability of SiC layer is significantly increased. The conclusion of the analysis has guiding significance for the theoretical design of SiC composites. Copyright © 2020 ASME.

关键词： Silicon carbide

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Joint Beamforming and Offloading design for Integrated Sensing, Communication and Computation system

arXiv

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arXiv 2024年

作者： Liu, Peng Fei, Zesong Wang, Xinyi Zhou, Yiqing Zhang, Yan Liu, Fan The School of Information and Electronics Beijing Institute of Technology Beijing100081 China The State Key Laboratory of Processors The Beijing Key Laboratory of Mobile Computing and Pervasive Device Institute of Computing Technology Chinese Academy of Sciences Beijing100190 China The School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen518055 China

Mobile edge computing (MEC) is powerful to alleviate the heavy computing tasks in integrated sensing and communication (ISAC) systems. In this paper, we investigate joint beamforming and offloading design in a three-tier integrated sensing, communication and computation (ISCC) framework comprising one cloud server, multiple mobile edge servers, and multiple terminals. While executing sensing tasks, the user terminals can optionally offload sensing data to either MEC server or cloud servers. To minimize the execution latency, we jointly optimize the transmit beamforming matrices and offloading decision variables under the constraint of sensing performance. An alternating optimization algorithm based on multidimensional fractional programming is proposed to tackle the non-convex problem. Simulation results demonstrates the superiority of the proposed mechanism in terms of convergence and task execution latency reduction, compared with the state-of-the-art two-tier ISCC framework. Copyright © 2024, The Authors. All rights reserved.

关键词： Beamforming

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Multiscale microstructure-based constitutive modeling of high-temperature creep rupture in post-irradiated ODS steels

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Journal of Materials Research and technology 2025年 36卷 8037-8047页

作者： Xiaobao Fu Zhenyu Zhao Zeyuan Yan Yuntao Zhong Dengke Chen Ruiqian Zhang Bin Liu Qihong Fang Jia Li State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 PR China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 PR China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of China Chengdu 610213 PR China Department of Engineering Mechanics School of Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 PR China

Oxide dispersion strengthened (ODS) steel exhibits the great potential as structural materials in nuclear energy production, owing to the complex interface between the oxide particles and the matrix to enhance the resistance of radiation damage. However, the impact of irradiation-induced defects on the thermal creep rate and resistance of ODS steel currently remains inadequately understood. The point defect concentration with the increasing time is predicted, and the coarsening of oxide particles is quantitatively evaluated during the creep using the Ostwald ripening theory. Considering the irradiation-induced microstructure, a modified thermal creep rate model is proposed, and the thermal creep rate and creep strain of irradiated ODS steel are predicted at different temperatures. The results show that the thermal creep rate reaches 3 × 10 −5 s −1 at the temperature of 500 °C and stress of 200 MPa, while the thermal creep strain does not exceed 3 % at the temperature of 800 °C. The average size and number density of the irradiated ODS steel are 8.34 nm and 2.72 × 10 18 m −3 . Meanwhile, the effect of the activation energy on the thermal creep life is predicted at different temperatures. The thermal creep life is maintained in the higher temperature range, even exceeding 10,000 h at 600 °C for irradiated ODS steels. High temperature causes the increased dislocation activity, and the coarsened oxide particles effectively hinder dislocation motion, thereby maintaining structural stability. This work aims to shed light on the influence of post-irradiation microstructure on the thermal creep performance of irradiated ODS steels, ultimately leading to the improved prediction of creep life.

关键词： Irradiation Oxide dispersion strengthening Point defect Thermal creep rate

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Effect of residual pore on the performance of UN kernel TRISO particle fuel 14

Effect of residual pore on the performance of UN kernel TRIS...

引用

14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Liu, Shichao Chen, Ping Zhou, Yi Pang, Hua Xi, Yong Tang, Changbing Zhao, Yanli Qiu, Xi Guo, Zixuan Nuclear power institute of China Science and Technology on Reactor System Design Technology Laboratory Changshun Stress No.1 Chengdu Sichuan610200 China

The thermal-mechanical performance of uranium nitride (UN) tri-isotropic (TRISO) particle with residual pore used in Light Water reactor (LWR) was investigated. The effect of pore size and location on the performance of inner dense pyrolytic carbon (IPyC) layer, SiC layer and outer dense pyrolytic carbon (OPyC) layer was studied. The dimensional changes, fission gas release and internal pressure of the fuel particle layers were calculated. Residual pore size can affect the stress distribution of coated layers obviously. The residual pore especially the big ones may be the source of cracks on the SiC layer, which can break or loss the capacity of SiC layer. Residual pore location has little influence on the stress distribution of the coated layer. In order to maintain the fission retention capacity of TRISO particle, the big residual pore should be avoided during fabrication process. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Silicon carbide

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Numerical Investigation into the Transient Behavior of the Spike-Type Rotating Stall for a Transonic Compressor Rotor

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Fluid Dynamics & Materials Processing 2022年第3期18卷 761-773页

作者： Pengfei Ju Fangfei Ning Zhiting Tong Jingying Wang 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 Research Institute of Aero-Engine Beihang UniversityBeijing100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing100191China School of Energy and Power Engineering Shandong UniversityJinan250061China Shandong Engineering Laboratory for High-Efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJinan250061China

In this paper,a numerical investigation into a spike-type rotating stall process is carried out considering a transonic compressor rotor(the NASA Rotor 37).Through solution of the Unsteady Reynolds-Averaged Navier-Stokes(URANS)equations,the evolution process from an initially circumferentially-symmetric near-stall flow field to a stable stall condition is simulated without adding any artificial *** the near-stall operating point,periodic fluctuations are present in the overall flow of the ***,the blockage region in the channel periodically shifts from middle span to the *** fluctuating condition does not directly lead to stall,while the full-annulus calculation eventually evolves to ***,a kind of“early disturbance”feature appears in the dynamic signals,which propagates forward ahead of the rotor.

关键词： Transonic compressor spike stall numerical simulation early disturbance dynamic signal

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被动标量湍流的约束亚格子模型

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Acta Mechanica Sinica 2023年第4期39卷 184-194页

作者：黄鹏陈宽宇彭怀午 Hsu-Chew Lee 史一蓬肖左利陈十一万敏平 Guangdong Provincial Key Laboratory of Turbulence Research and Applications Department of Mechanics and Aerospace EngineeringSouthern University of Science and TechnologyShenzhen518055China Guangdong-Hong Kong-Macao Joint Laboratory for Data-Driven Fluid Mechanics and Engineering Applications Southern University of Science and TechnologyShenzhen518055China State Key Laboratory for Turbulence and Complex System College of EngineeringPeking UniversityBeijing100871China Northwest Survey and Design Research Institute Xi’an710065China Eastern Institute for Advanced Study Ningbo315200China

本文采用约束大涡模拟(C-LES)模型来模拟湍流中的被动标量.通过施加一个基于被动标量大涡模拟(LES)中标量方差通量标度不变量的物理约束来计算动态混合非线性模型(MNLM)的系数.将约束亚格子(SGS)模型与不同的SGS模型在不可压各向同性湍... 详细信息

本文采用约束大涡模拟(C-LES)模型来模拟湍流中的被动标量.通过施加一个基于被动标量大涡模拟(LES)中标量方差通量标度不变量的物理约束来计算动态混合非线性模型(MNLM)的系数.将约束亚格子(SGS)模型与不同的SGS模型在不可压各向同性湍流被动标量中进行比较.此外,C-LES模型减少了SGS标量方差通量在惯性-对流尺度以及较大的黏性-扩散尺度上的变化.先验测试表明,C-LES模型在预测SGS标量通量的方向和大小方面表现最好.此外,C-LES模型减少了SGS标量方差通量在惯性-对流范围内以及粘性-扩散范围内大尺度的变化.在后验测试中,与传统的动态Smagorinsky(DSM)和MNLM模型相比,C-LES模型在预测标量谱和内部间歇性的演变中表现明显更好.这些结果表明,在SGS模型中施加物理约束是在被动标量湍流大涡模拟中的一种有前途的方法.

关键词： SGS模型亚格子模型 LES模型各向同性湍流物理约束扩散范围非线性模型动态混合

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PATH OPTIMIZATION FOR DYNAMIC OBSTACLE AVOIDANCE OF PIONEER ROBOT BASED ON DDPG SMART AGENT

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UPB Scientific Bulletin, Series D: Mechanical Engineering 2023年第2期85卷 29-42页

作者： Zheng, Qingchun Peng, Zhi Zhu, Peihao Zhao, Yangyang Ma, Wenpeng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China China School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China School of Computer Science and Engineering Tianjin University of Technology Tianjin300384 China

To improve the path efficiency for dynamic obstacle avoidance algorithms of Pioneer robots, this paper proposes an approach to create deep deterministic policy gradient (DDPG) smart agents with recurrent neural networks (RNN) to optimize the path strategy. This approach is realized by training RNN with the backpropagation (BP) algorithm to train the agent. First, the SolidWorks model and obstacle avoidance model of the Pioneer robot is established. The LIDAR sensor is used to obtain environmental information. Further, deep reinforcement learning obstacle avoidance algorithm based on RNN is presented. The dynamic obstacle avoidance path of the Pioneer robot is further simulated in two different virtual robot experiment platform (V-REP) scenarios. The simulation results show that the proposed algorithm shortens the training time by 26.3% compared with the DDPG algorithm. Our proposed scheme can improve the path efficiency for dynamic obstacle avoidance of the Pioneer robot. © 2023, Politechnica University of Bucharest. All rights reserved.

关键词： Reinforcement learning

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Fast Decentralized Multi-Agent Collision Avoidance Based on Safe-Reachable Sets

Fast Decentralized Multi-Agent Collision Avoidance Based on ...

引用

IEEE Conference on Decision and Control

作者： Zikai Ouyang Junwei Liu Haibo Lu Wei Zhang Shenzhen Key Laboratory of Control Theory and Intelligent Systems School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Peng Cheng Laboratory Shenzhen China

This paper presents a decentralized multi-agent collision avoidance method for systems with single integrator dynamics and identical maximum speeds. The key to our approach lies in the concept of safe-reachable sets, which define the set of positions that each agent can reach while avoiding collisions with its neighbors for any admissible controllers. With this concept, we develop a distributed controller by solving an online convex program, which is shown to guarantee collision-free trajectories. Furthermore, under a no temporary deadlock condition, we establish that each agent converges to its target position. Our approach is also efficient in terms of makespan, representing the total time needed for convergence. Simulation results demonstrate the effectiveness of our approach in terms of safety, convergence, and efficiency.

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Thermal Management and Dynamic Performance of a Cooler design for the Supercritical CO2 Turbine Shaft Cooling

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FRONTIERS IN ENERGY RESEARCH 2022年 10卷

作者： Li, Jun Gurgenci, Hal Guan, Zhiqiang Li, Jishun Xue, Yujun Li, Lun School of Mechatronics Engineering Henan University of Science and Technology Henan Key Laboratory for Machinery Design and Transmission System Henan University of Science and Technology Luoyang China School of Mechanical and Mining Engineering University of Queensland Brisbane QLD Australia

This paper presents the results of a numerical study on a supercritical CO2 (SCO2) turboshaft cooling device by considering heat transfer and hydrodynamics. A micro-cooling device with a radius clearance of 50 micron and a nozzle diameter of 4 mm was designed and used to investigate the heat transfer characteristics of a micro-spacing impinging and gas film dynamics. Sixteen nozzles (N = 16) are equally spaced around the shaft in single or double rows. Investigations include journal speed- and eccentricity-dependent forward and cross-coupled force coefficients, and the effects of nozzle layouts and mass flow rate on the heat transfer efficiency. Analysis of the correlation coefficient shows that the gas density in the radial clearance is the dominant factor affecting the convective heat transfer performance, while the fluid velocity is a secondary factor. And the cooling efficiency (mass flow utilization rate) at low cooling pressure (p(s) < 0.7 MPa) is significantly greater than that at high cooling pressure (p(s) > 0.7 MP). In addition, considering the structure alone, a dual-row cooler exhibits a higher average Nusselt number, also registers a higher mass flow rate at the same pressure. Once the shaft is heated only one end, the difference in effectiveness between single- and dual-row cooling is not significant, so coolers with a single-row configuration should be preferred. Then, experimental values for the temperature of the heated rotor are provided under specific cooling airflow conditions. Dynamic analysis results show that the force coefficient of the single-row configuration is more dependent on the journal rotation speed and eccentricity ratio, and exhibits a negative direct stiffness coefficient at higher inlet pressure and journal rotation speed. Moreover, cross-coupled terms (stiffness coefficient) generally have a more explicit variation tendency than direct terms, and are more sensitive to changes in shaft speed and eccentricity. Small clearance cool

关键词： shaft cooling gas film stiffness heat transfer cooler jet impingement

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Corrosion Behavior of Micro-Arc Oxidation Coating on Zirconium Alloy in Superheated Steam Condition

SSRN

引用

SSRN 2022年

作者： Li, Zheng-Yang Zheng, Mei-Yin Yang, Zhong-Bo Ren, Quan-Yao Cai, Zhen-Bing Jiao, Yong-Jun Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Tribology Research Institute Key Lab of Advanced Technologies of Materials Southwest Jiaotong University Chengdu610031 China

The corrosion behavior of MAO coating on Zr alloy was investigated in 400 ºC/10.3 MPa condition. The surface morphology, phase composition, and element distribution of MAO coating were analyzed. The results indicate that the oxide layer on MAO coating presents fewer cracks and pores than Zr alloy, because the high compressive stress can stabilize the t-ZrO2 and restrain the phase transformation, thus reducing the volume expansion and future decreasing defect. Based on the XRD, Raman mapping, SEM, XPS, and TEM results, the formation mechanism of t-ZrO2 and phase transformation process of MAO coating in superheated steam condition was summarized. © 2022, The Authors. All rights reserved.

关键词： Phase transitions

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