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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Zhao, Xingyu Liu, Minyun Cui, Rongyi Huang, Shanfang Wang, Kan Lu, Chuan Department of Engineering Physics Tsinghua University Beijing China Cnnc Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu China China Nuclear Power Engineering Co. Ltd Beijing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791886502

This study analyzed an yttrium hydride (YH2) moderated supercritical carbon dioxide cooled reactor loaded with pin-type, beryllium oxide diluted oxide fuel elements to reduce the critical enrichment. The impact of the YH2 on the coolant void reactivity was studied along with a moderator zoning scheme to flatten the radial power distribution. The YH2 was added as hexagonal moderating rods at the center of the fuel assemblies. The core was modeled using the continuous-energy reactor Monte Carlo code, RMC, with the On-The-Fly cross sections treatment. The results showed that the YH2 moderator increased the thermal fission and reduced the critical enrichment of the core with the same diluent volume fraction by more than 30%. The YH2 moderator significantly softened the neutron energy spectrum and reduced the neutron leakage upon core voiding, resulting in both a weaker positive spectral reactivity feedback and a weaker negative leakage reactivity feedback during core depressurization. For an UO2-loaded core, the YH2 gave a lower negative coolant void reactivity, while for a MOX-loaded core with diluent volume fractions smaller than 35%, the spectral feedback was more important and the YH2 strongly reduced the positive coolant void reactivity to less than $1. Arranging the YH2 in the peripheral assemblies reduced the radial power peaking factor to 1.319. The study shows that the YH2 moderator can reduce the critical enrichment, make the core less sensitive to voiding, and can flatten the radial power distribution of a single-enrichment core through moderator zoning. © 2022 by ASME.

关键词： Carbon dioxide

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Fault diagnosis of PEMFC based on fatal and recoverable failures using multi-scale convolutional neural networks

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International Journal of Hydrogen Energy 2024年 80卷 916-925页

作者： Xu, Jiang-Hai Zhang, Ben-Xi Zhu, Kai-Qi Zheng, Xiu-Yan Zhang, Cong-Lei Chen, Zhang-Liang Yang, Yan-Ru Huang, Tai-Ming Bo, Zheng Wan, Zhong-Min Hsu, Shu-Han Yan, Wei-Mon Wang, Xiao-Dong State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing102206 China Research Center of Engineering Thermophysics North China Electric Power University Beijing102206 China College of Mechanical Engineering Hunan Institute of Science and Technology Yueyang414006 China State Key Laboratory of Clean Energy Utilization College of Energy Engineering Zhejiang University Zhejiang Province Hangzhou310027 China Department of Mechanical Engineering National Taipei University of Technology Taipei10608 Taiwan Department of Energy and Refrigerating Air-Conditioning Engineering National Taipei University of Technology Taipei10608 Taiwan

This study introduces a multi-scale convolutional neural network (MCNN) for diagnosing various faults in proton exchange membrane fuel cell (PEMFC) systems. Using simulated fault data from a 240 kW PEMFC stack, the MCNN method is validated. Compared to traditional methods like backpropagation neural network (BP), support vector machine (SVM), and temporal convolutional neural network (TCNN), MCNN achieves an average accuracy of 96.31%, outperforming BP (88.88%), SVM (90.67%), and TCNN (93.80%). The study demonstrates MCNN's effectiveness in diagnosing recoverable faults, fatal faults, and multiple faults in PEMFC systems, achieving fault diagnosis accuracies of over 97%. By leveraging its inherent advantages such as multi-channel processing, automatic feature learning, and parameter sharing, MCNN provides an effective solution for accurately diagnosing faults in PEMFC. The utilization of these advantages has enabled MCNN to perform efficient and accurate fault diagnosis in PEMFC systems. © 2024 Hydrogen Energy Publications LLC

关键词： Failure analysis

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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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Nonlinear Dynamic Behavior and Vibration Mechanism of a Large Range Rotating Elastic Beam Under Parallel Misalignment Constraints 10

Nonlinear Dynamic Behavior and Vibration Mechanism of a Larg...

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10th International Conference on Advances in Machinery, Material science and Engineering Application, MMSE 2024

作者： Zhao, Lei Xu, Meiye Zhai, Ran Jiao, Likuan Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China School of Mechanic Engineering Tianjin University of Technology Tianjin300384 China

ISBN: (纸本)9781643685465

Large rotating flexible machines are prone to vibration at high speeds, which is a difficult engineering problem. In this study, we have deeply explored its nonlinear dynamic behavior and vibration mechanism, especially considering the effect of parallel misalignment. Through mathematical modeling and MATLAB simulations, we found that the rotational speed and the amount of misalignment are the key parameters affecting the stability of the system. The results show that the rotational speed and parallel misalignment are the sensitive parameters of the system. When the amount of misalignment is 0.002 mm, with the increase of rotational speed, the elastic beam exhibits nonlinear M-type vibration, doubly periodic and chaotic behaviors, which show high-frequency abrupt excitation;when the angular speed is 50 rad/s, with the increase of the amount of misalignment from 0.001 mm to 0.1 mm, the system exhibits the transformation of doubly periodic, chaotic and proposed periodic motions, and the characteristics of intermittent vibration are significant. These results provide an important theoretical basis for suppressing its nonlinear vibration. © 2024 The Authors.

关键词： Rotating machinery

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Thermochemical non-equilibrium flow characteristics of high Mach number inlet in a wide operation range

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Chinese Journal of Aeronautics 2023年第12期36卷 164-184页

作者： Chunliang DAI Bo SUN Lianjie YUE Shengbing ZHOU Changfei ZHUO Changsheng ZHOU Jianyi YU School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China College of Aerospace Engineering Chongqing UniversityChongqing 400044China Beijing System Design Institute of Electro-mechanic Engineering Beijing 102308China

The high-temperature non-equilibrium effect is a novel and significant issue in the flows over a high Mach number(above Mach 8)air-breathing ***,this study attempts to investigate the high-temperature non-equilibrium flows of a curved compression two-dimensional scramjet inlet at Mach 8 to 12 utilizing the two-dimensional non-equilibrium RANS ***,the thermochemical non-equilibrium gas model can predict the actual high-temperature flows,and the numerical results of the other four thermochemical gas models are only used for comparative ***,the thermochemical non-equilibrium flow fields and work performance of the inlet at Mach 8 to 12 are ***,the influences of high-temperature non-equilibrium effects on the starting characteristics of the inlet are *** results reveal that a large separation bubble caused by the cowl shock/lower wall boundary layer interaction appears upstream of the shoulder,at Mach *** separation zone size is smaller,and its location is closer to the downstream area while the thermal process changes from frozen to non-equilibrium and then to *** the increase of inflow Mach number,the thermochemical non-equilibrium effects in the whole inlet flow field gradually strengthen,so their influences on the overall work performance of the high Mach number inlet are more *** vibrational relaxation or thermal non-equilibrium effects can yield more visible influences on the inlet performance than the chemical non-equilibrium *** inlet in the thermochemical non-equilibrium flow can restart more easily than that in the thermochemical frozen *** work should provide a basis for the design and starting ability prediction of the high Mach number inlet in the wide operation range.

关键词： Non-equilibrium Scramjet inlet Starting ability Thermochemical Work performance

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The Influence of Turbulators on the Flow and Heat Transfer Characteristic of Helium-Xenon Mixture Inside the Tight Lattice Rod Bundles

SSRN

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SSRN 2024年

作者： Wang, Lanxin Shi, Xinhuan Li, Zhongchun Wu, Xiaoli Ding, Shuhua Chen, Wei School of Aeronautics and Astronautics Sichuan University Chengdu610065 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China

The gas-cooled nuclear reactor combined with the closed Brayton cycle is the ideal choice for future high-power space missions, while the helium-xenon mixture is a suitable working medium for the reactor due to its good compressibility and heat transfer capacity. For further development and application of more lightweight compact reactor, the influence mechanism of turbulator structures with different angle and layout on the heat transfer enhancement of helium-xenon mixture in the sub-channel of gas-cooled nuclear reactor is numerically studied. The results show that, due to the vortex and secondary flow induced by the turbulator, the heat transfer is enhanced effectively, and the Nusselt number is fluctuated periodically. Compare the result with different angle, the heat transfer enhancement by the turbulator with 90°angle is relatively small, and the pressure drop is large. Because of the secondary flow in narrow triangular space induced by turbulator with 45°angle, the mixing between the high and low temperature fluids will effective enhanced, the heat transfer enhancement is more significant. The heat transfer performance and thermal efficiency index of different turbulator layout are summarized and compared, which provides the reference for heat transfer design of gas-cooled nuclear reactor. © 2024, The Authors. All rights reserved.

关键词： Helium

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Towards Effective and Efficient Error Handling Code Fuzzing Based on Software Fault Injection 31

Towards Effective and Efficient Error Handling Code Fuzzing ...

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31st IEEE International Conference on Software Analysis, Evolution and Reengineering, SANER 2024

作者： Chen, Kang Wen, Ming Jia, Haoxiang Wu, Rongxin Jin, Hai Wuhan430074 China Jin YinHu Laboratory Wuhan430074 China School of Informatics Xiamen University Xiamen361005 China School of Computer Science and Technology HUST Wuhan430074 China National Engineering Research Center for Big Data Technology and System Services Computing Technology and System Lab China Hubei Engineering Research Center on Big Data Security Hubei Key Laboratory of Distributed System Security China Cluster and Grid Computing Lab China

ISBN: (纸本)9798350330663

Software systems often encounter various errors or exceptions in practice, and thus proper error handling code is essential to ensure the reliability of software systems. Unfortunately, error handling code is often bug-prone, while sufficiently testing them is challenging as such code often cannot be triggered under normal conditions. Motivated by this, recent studies have proposed to leverage software fault injection (SFI) based fuzzing to discover potential bugs in complicated error handling code. Despite the promising results achieved, their effectiveness and efficiency are still compromised in practice due to the huge search space of error sites, inadequate fuzzing guidance, and the overhead induced by context-sensitive SFI. To achieve effective and efficient testing of error handling code, this study presents AFL-FI, which first utilizes a similarity-based method to identify suspicious error sites, and then incorporates the idea of error site coverage to guide the fuzzing process. Finally, the design of lightweight context-sensitive SFI enables AFL-FI to execute test cases efficiently. We evaluate AFL-FI on eight large-scale open-source projects, and the results show that it can outperform existing state-of-the-art fuzzing tools significantly in terms of branch code coverage. More importantly, AFL-FI has discovered 13 previously unknown bugs, and all of them have been confirmed while 12 of them have been fixed. Besides, our evaluation also demonstrates that all the key designs of AFL-F I are effective that contribute significantly to its overall performance. © 2024 IEEE.

关键词： Errors

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Neural Network-Based Terminal Sliding Mode Controller design for Manipulator systems 1

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UNIfied Conference of International Workshop on Defence Applications of Multi-Agent systems, DAMAS 2023, International Conference on Maintenance Engineering, IncoME-V 2023, International conference on the Efficiency and Performance Engineering Network, TEPEN 2023

作者： Qu, Lufeng Fan, Qiming Kang, Yang Yang, Jun Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China School of Intelligent Manufacturing Tianjin Sino-German University of Applied Technology Tianjin300350 China School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9783031494130

ISBN: (纸本)9783031494123

In the context of nonlinear and uncertain manipulator systems, achieving fast and accurate desired trajectories for each joint of the manipulator is crucial. Our study aims to improve current control methods by combining sliding mode control and neural network techniques. Specifically, we leverage the neural networks’ approximation capabilities to estimate both the modeling error and external disturbance in our research. These estimates are then integrated into the synovial control as additional gains. This approach allows for the sliding mode controller’s switch gain to adapt to changing modeling error and external disturbance, thereby avoiding the vibration production typically associated with traditional sliding mode controllers. It can be observed from the simulation results that the combination of the proposed nonsingular terminal sliding mode controller and neural network achieves fast and precise tracking of desired trajectories. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.

关键词： Sliding mode control

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An Interpretable Dynamic Feature Search Methodology for Accelerating Computational Process of Control Rod Descent in Nuclear reactors

SSRN

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SSRN 2023年

作者： Huang, Qingyu Xiao, Cong Pang, Zhixin Lin, Yuanfeng Liu, Jia Zhang, Zhuo Zhao, Mengwei Liu, Xiaobo Wang, Yuanmei Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Within the operational dynamics of a nuclear reactor, the customary approach involves modulating the reactor's power output by means of control rod manipulation, which effectively alters the neutron density across the core. The descent behavior of the control rod drive lines pertains to the intricate motion exhibited by the control rod components within the reactor during its operational lifespan, characterized by conditions of heightened irradiation, temperature, pressure, and complex fluid dynamics. The precise calculation of the control rod descent process is an integral facet of reactor structural design to ensure the safe and reliable operation of the reactor. However, the current computational fluid dynamics-based simulation methods employed for this purpose necessitate extensive grid computations, imposing significant computational burdens in terms of resources and time. In light of this challenge, we present a novel and interpretative algorithm rooted in dynamic similarity feature search. Through comprehensive validation, this algorithm demonstrates remarkable precision with computational results exhibiting an error margin within 10%, while simultaneously achieving a substantial enhancement in computational efficiency of nearly three orders of magnitude when compared to conventional computational fluid dynamics techniques. Notably, this algorithm showcases exceptional versatility, holding immense promise for broad applicability across various operational scenarios encountered during the intricate process of nuclear reactor design. © 2023, The Authors. All rights reserved.

关键词： Control rods

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Thinning air-water films stabilized by bacterial particles

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Acta Mechanica Sinica 2021年第1期37卷 27-34,I0001页

作者： Song Wu Yuehua Yang Hongyuan Jiang Hefei National Laboratory for Physical Science at the Microscale CAS Key Laboratory of Mechanical Behavior and Design of MaterialsDepartment of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei230026China

The ability of particles to stabilize liquid films has broad applications in many fields,such as drug delivery,biofuel catalysis,and crude-oil *** mechanism of particles to stabilize emulsions has been widely ***,how particles affect the stability of suspension films is still ***,the dynamics of bacterial particles on free liquid films during evaporation is obtained by direct microscopic *** find that the initial concentration of the bacterial solution affects the evolution of the shapes and stabilities of liquid *** liquid film with a low bacterial concentration exhibits a drainage and rupture process similar to pure water,and bacteria would be evacuated during the evaporation of liquid ***,when the bacterial concentration is high,bacteria form a single-layer array in the center of the film and greatly enhance the stability of the liquid *** demonstrate that these two distinct film evaporation dynamics are caused by the difference in the lateral capillary force of the particles at different positions on the liquid film,which is not affected by the active motility of ***,our research reveals the critical role of bacteria concentration in stabilizing suspension liquid film.

关键词： Bacterial concentration Evaporation dynamics Film stability Lateral capillary force

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