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In-Situ Study on Factors Impeding Dislocation Motion in Fe9cr1.5w0.4si F/M Steel During High Temperature Heating

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SSRN 2023年

作者： Ding, Yifan Yuan, Fan Cao, Ziqi Ren, Jiacheng Li, Yuanmin Xin, Yong Ran, Guang College of Energy Xiamen University Xiamen361102 China Fujian Provincial Nuclear Energy Engineering Technology Research Center Xiamen361102 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China Nuclear Power Institute of China Chengdu610213 China

Plastic deformation is driven by the movement of dislocations on a microscopic scale, and the mobility of these dislocations determine the strength of the material. Forest dislocations and dislocation loops are often considered to be important factors that impede dislocation movement, but their effectiveness is called into question at high temperature. Here, in-situ heating was performed on irradiated Fe9Cr1.5W0.4Si ferritic martensitic steel in the temperature range of 873-923 K, and the interaction between dislocation lines and obstacles was investigated to reveal the mechanism that led to easier dislocation gliding. Dislocations tended to glide in several planes at the same time and only glided as a whole in one plane occasionally. It was discovered that dislocations usually glided in high index planes such as {123} planes. When moving dislocations intersected with forest dislocations, a new mechanism was found where the segments for different dislocations with the same Burgers vector could exchange, which was important for the moving dislocation to cut through the forest dislocations without decreasing their mobility. The reactions between dislocations and loops included absorption, break away and rebound. Meanwhile, statistical results indicated that the highest ratio was about 48% for the case where loops were restored and dislocations broke away, demonstrating that the loops were not strong obstacles when interacting with moving dislocations at high temperature. © 2023, The Authors. All rights reserved.

关键词： Chromium alloys

Applying multi-scale simulations to materials research of nuclear fuels:A review

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Materials Reports(Energy) 2021年第3期1卷 64-80页

作者： Chunyang Wen Di Yun Xinfu He Yong Xin Wenjie Li Zhipeng Sun School of Nuclear Science and Technology Xi'an Jiaotong UniversityXi'an710049China State Key Laboratory of Multiphase Flow Xi'an Jiaotong UniversityXi'an710049China China Institute of Atomic Energy Beijing102413China Key Laboratory of Nuclear Reactor System Design Technology Nuclear Power Institute of ChinaChengdu610213China

Computational simulation is an important technical means in research of nuclear fuel *** nuclear fuel issues are inherently multi-scopic,it is imperative to study them with multi-scale simulation *** present,the development of multi-scale simulation for nuclear fuel materials calls for a more systematic approach,in which lies the main purpose of this *** most important thing in multi-scale simulation is to accurately formulate the goals to be achieved and the types of methods to be *** this regard,we first summarize the basic principles and applicability of the simulation methods which are commonly used in nuclear fuel research and are based on different scales ranging from micro to macro,***-Principles(FP),Molecular Dynamics(MD),Kinetic Monte Carlo(KMC),Phase Field(PF),Rate Theory(RT),and Finite Element Method(FEM).And then we discuss the major material issues in this field,also ranging from micro-scale to macro-scale and covering both pellets and claddings,with emphasis on what simulation method would be most suitable for solving each of the ***,we give our prospective analysis and understanding about the feasible ways of multi-scale integration and relevant handicaps and challenges.

关键词： Computational simulation Nuclear fuel Multi-scale modeling Irradiation behavior

Wireless Edge Content Broadcast via Integrated Terrestrial and Non-terrestrial Networks

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arXiv

arXiv 2023年

作者： Wang, Feng Geraci, Giovanni Li, Lingxiang Wang, Peng Quek, Tony Q.S. The Information System Technology and Design Pillar Singapore University of Technology and Design 487372 Singapore Barcelona Spain National Key Laboratory of Wireless Communications University of Electronic Science and Technology of China Chengdu611731 China

Non-terrestrial networks (NTN) have emerged as a transformative solution to bridge the digital divide and deliver essential services to remote and underserved areas. In this context, low Earth orbit (LEO) satellite constellations offer remarkable potential for efficient cache content broadcast in remote regions, thereby extending the reach of digital services. In this paper, we introduce a novel approach to optimize wireless edge content placement using NTN. Despite wide coverage, the varying NTN transmission capabilities must be carefully aligned with each content placement to maximize broadcast efficiency. In this paper, we introduce a novel approach to optimize wireless edge content placement using NTN, positioning NTN as a complement to TN for achieving optimal content broadcasting. Specifically, we dynamically select content for placement via NTN links. This selection is based on popularity and suitability for delivery through NTN, while considering the orbital motion of LEO satellites. Our system-level case studies, based on a practical LEO constellation, demonstrate the significant improvement in placement speed compared to existing methods, which neglect network mobility. We also demonstrate that NTN links significantly outperform standalone wireless TN solutions, particularly in the early stages of content delivery. This advantage is amplified when there is a higher correlation of content popularity across geographical regions. Copyright © 2023, The Authors. All rights reserved.

关键词： Hydrogeology

Q-Learning for Finite-Horizon H8Tracking Control of Unknown Linear Discrete-Time systems 42

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Q-Learning for Finite-Horizon H8Tracking Control of Unknown ...

42nd Chinese Control Conference, CCC 2023

作者： Liu, Mingxiang Cai, Qianqian Meng, Wei Li, Dandan Fu, Minyue Han, Zhimin School of Automation Guangdong University of Technology Guangzhou510006 China Guangdong Province Key Laboratory of Intelligent Decision and Cooperative Control Guangzhou510006 China School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen518055 China School of Automation Hangzhou Dianzi University Hangzhou310018 China

ISBN: (纸本)9789887581543

In this paper, we present a Q-learning algorithm for finite-horizon H8 tracking control of unknown linear discrete-time systems. Finite horizon control is challenging due to its correspondence with a time-varying Riccati equation. The proposed algorithm can determine the solution of the time-varying Riccati equation with unknown system dynamics. We first establish the time-varying Q-function, then propose a corresponding Q-learning algorithm and prove its convergence. Finally, the proposed algorithm is proved to be effective through numerical examples. © 2023 Technical Committee on Control Theory, Chinese Association of Automation.

关键词： Riccati equations

Capillary Evaporating Film Model for a Screen-Wick Heat Pipe

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SSRN 2022年

作者： Ma, Yugao Zhang, Yingnan Yu, Hongxing Huang, Shanfang Deng, Jian Chai, Xiaoming Zeng, Chang Zhang, Zhuohua He, Xiaoqiang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering Physics Tsinghua University Beijing100084 China

Screen-wick heat pipes are efficient passive heat transfer devices. The heat transfer capacity is determined by the capillary pressure, which is related to the film curvature inside the screen wick. A capillary evaporating film model was developed for the screen wick that divided the film into a capillary pressure microlayer region and a macroscopic film. The film surface shape in the capillary pressure microlayer region is mainly influenced by the long-range molecular forces (disjoining pressure) and the surface tension, while the film surface shape in the macroscopic film is affected by the wick geometry. The numerical results show that the present model more accurately predicts the three-dimensional characteristics of the liquid film inside the screen wick than the classical model. The wire opening distance and the wire diameter affect the capillary pressure and the flow path in the wick. As the liquid film recedes into the wick, the capillary force first increases and then decreases. The film dynamics in the wick are related to the liquid height, which automatically adapts to the required evaporation and pressure balance for a given heat load. High operating temperatures can lead to a mismatch between the capillary head and the pressure loss, leading to dry out in the wick. Thus, this work provides a reference for operating alkali-metal wick heat pipes. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

Study on the Load Following Control of SMR with Flexible Load 5th

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Study on the Load Following Control of SMR with Flexible Loa...

5th International Symposium on Software Reliability, Industrial Safety, Cyber Security and Physical Protection of Nuclear Power Plant, ISNPP 2020

作者： Liu, Ming-Ming Sun, Ao-Di Qiu, Lei-Lei Zhang, Ru Wei, Xin-Yu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Key Laboratory of Advanced Nuclear Energy and Technology and Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789811634550

The load following requirement will be increased greatly while the Small Modular reactor (SMR) is used for isolated island operation mode. In order to improve the load following ability of the system, the flexible load (FL) is presented in this study to follow the electricity load during load follow. The definition of FL is a type of power consuming system that can change the needed power discretionary. For example, the hydrogen manufacture plant, the desalination facility, the district heating system, and other industrial process heat supply system are all FLs. In order to analyze the dynamic characters of the system, pressurized water reactor (PWR) type SMR (comprised with reactor core and once-through steam generator), balance of plant (BOP), and FL are modeled first. Based on these dynamic models, a SMR-FL dynamic simulation program is built in MATLAB/Simulink environment. According to different system characteristics, two types of FL are considered, and the related load allocation control systems are designed. A typical electricity load is used to verify the designed control systems for the two types of FL. The simulation results show that the designed control systems can achieve load following by adjusting the power consuming of FL and maintaining a constant or moderate changing output of SMR. Obviously, this character can make the SMR-FL system more flexible and efficiency. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Control systems

Perceived vs. Objective Human Performance in Diagnostic Tasks: Under-Confidence or Over-Confidence?

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SSRN 2022年

作者： Lyu, Xi Li, Zhizhong Ma, Quan She, Manrong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Industrial Engineering Tsinghua University Beijing100084 China

Humans are not very good at assessing their own performance, and usually exhibit over-confidence. Little effort has been done to investigate how and how well diagnosticians perceive their performance of sub-processes of diagnosis, for example information seeking and information integration. This study analyzed the performance data of an experiment of diagnosing an accident in a simulated nuclear power plant. The objective performance was measured by eight indicators and the perceived performance was measured by three indicators. Difference relations and correlations between these indictors were explored. Results showed that on one hand there were systematic deviations between perceived and objective performance, on the other hand the perceptions did have some validity. Perceptions of information seeking manifested under-confidence while perceptions of information integration and the overall diagnosis manifested over-confidence. The authors argue that these two biases were mutually complementary and facilitating rather than contradictory. The findings could be used to help diagnosis-related training, operation and decision making. © 2022, The Authors. All rights reserved.

关键词： Information retrieval

Influence of Si Addition on the Microstructure, Mechanical and LBE Corrosion Properties of an Amorphous AlCrFeMoTi High-Entropy Alloy Coating

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SSRN 2022年

作者： Yang, Jian Bai, Fan Zhou, Mingyang Deng, Jiuguo Zhong, Yilong Chen, Qingsong Zhang, Wei Zhu, Changda Liu, Ning Yang, Jijun Key Laboratory of Radiation Physics and Technology Ministry of Education Institute of Nuclear Science and Technology Sichuan University Chengdu610064 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The effect of the Si addition content ranging from 3.3 to 9.1 at.% on the microstructure, mechanical properties and LBE corrosion behaviour of AlCrFeMoTi HEA coatings was investigated. The AlCrFeMoTiSix coatings still maintained an amorphous structure, and their mechanical properties were improved. The Si addition greatly contributed to the enhancement of the LBE corrosion resistance of the coatings, which could be attributed to the formation of a more continuous and protective Cr2O3 and Al2O3 layer. However, the improved efficiency was related to the Si addition content, with an oxidation process model put forwards to well explain this phenomenon. © 2022, The Authors. All rights reserved.

关键词： Corrosive effects

Influence of Si Addition on the Microstructure, Mechanical and Lbe Corrosion Properties of an Amorphous Alcrfemoti High-Entropy Alloy Coating

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SSRN 2022年

作者： Yang, Jian Zhou, Mingyang Liu, Ning Yang, Jijun Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University Chengdu610064 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

关键词： Corrosive effects