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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Deng, Jian Zhang, Xisi Wang, Xinan Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

To increase power density in nuclear reactors, the helical cruciform fuel (HCF) is designed as a fundamental element. HCF takes advantages of strong mixing effects, self-supporting features, and strengthened heat transfer, potential to increase the fuel performance in nuclear reactors. In this paper, friction factor and heat transfer coefficient empirical correlations of HCF single rod cooled by water were proposed using a geometric dimensionless number based on numerical simulation. The velocity field, and temperature distribution were obtained to discuss influences of geometric sizes on the fuel performance. Finally, correlations with a geometric dimensionless number were validated with various cases, whose application conditions were also proposed and discussed. This paper provides a guide for study of heat transfer and fluid flow in helical structures, and a reference for establishment of reactor system model using helical cruciform fuels. © 2024, The Authors. All rights reserved.

关键词： Heat transfer coefficients

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An Efficiency Optimization Control Method for Three-Phase Interleaved DC-DC Converter

An Efficiency Optimization Control Method for Three-Phase In...

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IEEE Asia Power and Energy Engineering Conference (APEEC)

作者： Jinxin Wang Renyong Peng Chen Cai Haitao Yu Meiyuan Chen Yiyi Liu Ke Wu Shihan Tang Hongyang Wei Jie Chen Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

Because of the environmental friendliness of electric vehicles, research on electric vehicles has become a hot spot in recent years. How to charge electric vehicles faster is critical to the widespread use of electric vehicles. Electric vehicle integrated power unit can use bidirectional DC-DC converter for driving to achieve integrated charging. In order to improve the power density and efficiency of the integrated system, the bidirectional DC-DC for electric vehicle driving uses three-phase interleaved parallel technology. This paper proposes a method to select different interleaved phase numbers according to different output powers of the converter to improve the working efficiency of three-phase interleaved parallel DC-DC converters. This method improves the efficiency of the three-phase interleaved parallel converter under light load and widens the high-efficiency working area of the converter. Finally, simulations and experimental results are conducted to validate the efficiency of the design.

关键词： Power system measurements Simulation DC-DC power converters Switches Electric vehicles Software Electron tubes

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Influence of Different Factors on Fault Current Under DC Side Fault of Photo voltaic Grid Connected system

Influence of Different Factors on Fault Current Under DC Sid...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Yongyi Luo Xianguo Qing Renyong Peng Yuzhao Huangfu Ao Cui Zhaosu Wang Zhiqiang Zhang Ziheng Peng Chengyu Liao Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9781665434263

Modular multilevel converter (MMC) has many advantages, such as low loss, flexible control and so on, which has been widely used in photovoltaic grid connected system. However, the photovoltaic output has some instability, and the damping of the flexible DC system is also low, which puts forward a severe test for the stable operation of the power grid. Firstly, this paper describes the basic structure of the photovoltaic system connected by MMC. Secondly, the photovoltaic grid connected system model based on PSCAD illustrates the fault current characteristics under DC side fault, and simulates and analyzes the influence of different factors in the system on the fault current.

关键词： Photovoltaic systems Analytical models Multilevel converters system integration Power grids Internet Circuit faults

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

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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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Position-and-Torque-Sensorless Admittance Control with State Estimation Considering dq-axis Cross-Coupling Factors

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IFAC-PapersOnLine 2023年第2期56卷 6075-6080页

作者： Keita Shimamoto Toshiyuki Murakami Tsukuba Research Lab. YASKAWA Electric Corp. Ibaraki Japan and Graduate School of Science and Technology Keio University Kanagawa Japan Department of System Design Engineering Keio University Kanagawa Japan

This paper presents a position estimation compensation method considering dq-axis cross-coupling factors of Interior Permanent Magnet Synchronous Motors (IPMSMs) inductance for position-and-torque-sensorless admittance control. The cross-coupling factors are from dq-axis mutual inductance and deteriorate control and position estimation performance in control methods without the model. Since dq-axis cross-coupling factors of inductance vary with the rotor position and the current, measurement and estimation of the values are difficult. The proposed method estimates the cross-coupling factors and position estimation errors using dq-axis current variation from the injected voltage. In addition, the proposed method compensates the estimated position based on a voltage equation, including the dq-axis cross-coupling factors, by adding the estimated error. As a result, the vibration of current, velocity, and estimated reaction torque were reduced, and the performance of a position-and-torque-sensorless admittance control system was improved. The experimental results show the proposed method's validity and response by the sensorless admittance control.

关键词： Motion estimation Inductances Parameter estimation Motor Control Force control Position control

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Evolution and Characteristics of Defect Clusters in H2+ Irradiated Al-Based Gd2o3-W Composites Used as Spent Fuel Shielding Materials

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SSRN 2023年

作者： Wang, Zuojiang Cao, Ziqi Wu, Mengjie Li, Yuanming Ran, Guang College of Energy Xiamen University Fujian Province Xiamen City361102 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China Fujian Provincial Nuclear Energy Engineering Technology Research Center Xiamen361102 China Nuclear Power Institute of China Chengdu610213 China

Al-based composites containing high neutron absorption cross section elements are the most promising shielding materials for spent fuel storage, but their irradiation performance is the key to their long-term service stability. In the present work, an in-situ study on the evolution and characteristics of irradiation defect clusters including dislocation loops, gas bubbles and hydrogen platelets in Al-based Gd2O3-W composites during 30 keV H2+ irradiation was carried out in a transmission electron microscope and analyzed in detail. The delamination of bubbles and the formation of tunnel structure in Al matrix were found for the first time. Hydrogen platelets in Al5W particles was first observed, and their formation and evolution and corresponding mechanism were investigated in detail. Platelets with different orientation had different growth rates, and the relationship between growth rate and dose was constructed. Besides, the irradiation-induced increment of yield strength in Al matrix was estimated. This study will provide new insights for the design and development of new Al-based rare earth composites with high resistance to irradiation damage. © 2023, The Authors. All rights reserved.

关键词： Platelets

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Forming Circle Formations of Multi-agent systems Under Actuator Faults 5th

Forming Circle Formations of Multi-agent Systems Under Actu...

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5th Chinese Conference on Swarm Intelligence and Cooperative Control, CCSICC 2021

作者： Liu, Jiajun Ru, Xinfeng Xia, Weiguo Wang, Chen China National Aeronautical Radio Electronic Research Institute and National Key Laboratory of Science and Technology on Avionics System Integration Shanghai China Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education and School of Control Science and Engineering Dalian University of Technology Dalian China National Engineering Research Center of Software Engineering and the State Key Laboratory of Turbulence and Complex Systems Intelligent Biomimetic Design Lab College of Engineering Peking University Beijing China

ISBN: (纸本)9789811939976

A distributed fault-tolerant formation control law is designed in this paper for multi-agent systems under external disturbances and actuator faults including time-varying loss of effectiveness faults. The initial position of each agent is already on a circle and the control purpose is to form a desired formation on this circle. Based on this local information, a distributed adaptive formation control law is designed by employing the congelation of variables method to deal with time-varying actuator faults. Finally, a simulation example is given to verify the effectiveness of the adaptive fault-tolerant control design method. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Multi agent systems

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BDGSE: A Symbolic Execution Technique for High MC/DC

BDGSE: A Symbolic Execution Technique for High MC/DC

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IEEE International Conference on Software Quality, Reliability and Security (QRS)

作者： Huangli Cai Zhiyi Zhang Yifan Jian Dan Li Zhiqiu Huang Collage of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China Ministry Key Laboratory for Safety-Critical Software Development and Verification Nanjing University of Aeronautics and Astronautics Nanjing China

Modified Condition/Decision Coverage (MC/DC) is a test coverage standard with excellent fault detection capability, which is widely used in testing safety-critical software. Symbolic execution generates test cases automatically to achieve high code coverage. However, since symbolic execution uses short-circuit evaluation to evaluate decisions, it fails to guarantee the consistency of other conditions in a decision required by the MC/DC criterion. As a result, it is incapable of generating MC/DC test cases to test safety-critical systems adequately. To solve this problem, we propose Branch Dependence Guided Symbolic Execution (BDGSE), a symbolic execution technique for high MC/DC. The approach utilizes static analysis to compute the branch dependencies, then guides symbolic execution to selectively explore paths and simplify test cases, and finally generates a small number of test cases to achieve high MC/DC coverage. Our experimental results show that BDGSE can generate high-quality test cases. Although BDGSE generates fewer test cases, it can achieve higher MC/DC coverage than SPF and random methods, and the fault detection capability of test cases generated by BDGSE is comparable to that of test cases generated by SPF.

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An Adaptive Bionic Sensor: Enhancing Ankle Joint Tracking with High Sensitivity and Superior Cushioning Performance

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SSRN 2024年

作者： Jin, Jianqiao Zhang, Chen Zhao, Jianyuan Yu, Minghan Lei, Ming Jin, Chun Yin, Rui Zhao, Weiwei Sauvage Laboratory for Smart Materials The School of Integrated Circuit Harbin Institute of Technology Shenzhen518055 China Shenzhen Key Laboratory of Flexible Printed Electronics Technology Harbin Institute of Technology Shenzhen518055 China State Key Laboratory of Advanced Welding & Joining Harbin Institute of Technology Harbin150001 China Human-Computer Interaction Design Lab School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen518055 China

Flexible sensors are renowned for their rapid responsiveness, high flexibility, and outstanding mechanical properties, making them ideal for applications in wearable devices, sports and health monitoring, and human-machine interfaces. To enhance the sensing performance of these flexible sensors, researchers have drawn inspiration from nature, creating various bionic microstructures. However, these structures often manifest in the macroscopic form of thin films, which do little to improve impact resistance and joint protection. In response, this work achieves a highly sensitive and impact-resistant pressure sensor by integrating bionic principles at both micro and macro levels. Specifically, at the micro level, a muscle-like hydrogel system consisting of MXene nanosheets incorporated into the double network of polyvinyl alcohol and sodium alginate matrix is selected. At the macro level, the bionic prototypes of mimosa leaves and durian spikes with good energy absorption structure, together with octopus’ sucker with good adsorption capacity are selected, and the synergistic construction of the three structures is realized through 3D printing methods. The obtained sensor has an appropriate response range, sensitivity and stability. More importantly, the displacement deformation of the hydrogel can be reduced by 91.22%, while its adhesion strength can be increased by 57.5% compared to the unstructured hydrogel. As a proof-of-concept, the proposed bionic flexible sensor can be used to monitor the motion status of the human ankle joint in real-time, thereby assisting users in making real-time judgments on gait health. © 2024, The Authors. All rights reserved.

关键词： Sodium alginate

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Numerical study of fuel melting and molten migration based on the mps method

Numerical study of fuel melting and molten migration based o...

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

作者： Lei, Zhong Deng, Jian Li, Wei Wu, Xiaoli Deng, Chunrui Nuclear Power Institute of China Chengdu Sichuan China Science and Technology on Reactor System Design Technology Laboratory Chengdu Sichuan China

ISBN: (纸本)9780791883785

Core melting and molten migration behavior are hot and difficult issues in the field of nuclear reactor severe accident research. The Moving Particle Semi-implicit (MPS) meshless method has potential to simulate free-surface and multiphase flows. In this study, the MPS method was utilized to simulate the melting process of UO2-Zr rod-type fuel elements. The models of heat conduction with phase change, simplified UO2-Zr eutectic reaction, viscous flow and surface tension were implemented with the framework of standard MPS method. Then, the improved MPS code was used to simulate and analyze the process of high-temperature melting and characteristics of molten migration and solidification in the coolant channel, aiming at revealing the severe accidents for light water reactors (LWR), particularly the early core damage. The results showed that compared with the case of higher initial temperature, when the initial temperature of molten UO2 is lower, more molten UO2 will solidify on the surface of rod cluster, and the blockage of upper flow channel caused by molten UO2 is more serious. In addition, this study also demonstrated the potential of the MPS method for the study of complicated severe accident phenomena in not only traditional LWR but also advanced nuclear reactors in the future. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Solidification

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