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SSRN 2022年

作者： Qu, Wenhai Xie, Hao Shen, Danhong Wang, Zefeng Xiong, Jinbiao School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

Experimental study of coherent structures downstream of a spacer grid with different inclination angles of mixing vanes in a 5×5 rod bundle was conducted by TR-PIV under four Reynolds *** coherent structures downstream of spacer grid change with several patterns. The developments of lateral time-averaged velocity, Reynolds stress, dominant frequency, integral spatial length scales and integral temporal length scales are determined by coherent structures. Smaller coherent structures are generated with Reynolds number increasing, and time-averaged velocity, Reynolds stress, St numbers, spatial and temporal length scales decrease. Larger inclination angle generates larger coherent structures, and spatial and temporal length scales increase with inclination angle increasing. The coherent structures indicate strong anisotropy of turbulent flow in rod *** experimental findings provide valuable information for understanding sub-channel mixing phenomena caused by mixing vaned spacer grids. The experimental data can be used for sub-channel mixing model developments and validations of turbulent models. © 2022, The Authors. All rights reserved.

关键词： Reynolds number

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Exploring the effects of work zone on vehicular flow on ring freeways with a tunnel using a three-lane continuum model

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International Journal of Transportation science and technology 2024年第2期14卷 27-41页

作者： Shan Li M.N.Smirnova Shanjun Yang N.N.Smirnov Zuojin Zhu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230022China Faculty of Mechanics and Mathematics Lomonosov Moscow State UniversityMoscow 119992Russia Scientific Research Institute for System Analysis Russian Academy of SciencesMoscow 117218Russia Moscow Center for Fundamental and Applied Mathematics Moscow 119991Russia Physical Education Center USTCHefei 230026China

Freeway work zone forms as a result of traffic crash or road *** ascertain the effects of work zone with lane II completely blocked on vehicular flow on ring freeways with a tunnel,a three-lane continuum model is put *** mandatory net lanechanging rate from lane II to lane I or III just upstream of the work zone is described by a random number model,with the random number being produced within a small range around a median based on a golden section *** net-changing rate between adjacent lanes is described using a lane-changing time on the basis of an assumption:the time ratio to relaxation time equals infinity when the absolute value of traffic densities between the two adjacent lanes is less than 1 veh/km,implying that the net-changing rate is zero;otherwise,the time ratio is inversely proportional to the vehicular spatial headway,which is equal to unity for traffic flow at saturation state,but infinity when the traffic flow is completely *** is assumed that the freeway is a three lane ring with a total length of 100 km,and has a tunnel with a speed limit of 60 km/h and a length of 1.6 km located downstream the work zone with a length of 0.16 *** free flow speeds on lanes I,II,and III are 120 km/h,100 km/h,and 85 km/h,*** the vehicular flow on the ring freeway with a tunnel,numerical simulations based on the three-lane continuum model are carried out with a reliable numerical method of high *** is found that the vehicular flow has two thresholds of traffic jam formation,one depending upon the tunnel and the other upon the work *** tunnel triggers a traffic jam when the initial density normalized by jam density is equal to the first threshold 0.15,and the work zone originates another traffic jam when the normalized initial density equals the second threshold *** freeway tunnel plays a dominant role in the prediction of mean travel time as soon as the tunnel has generated a traffic jam at the tunn

关键词： Work zone Three-lane continuum model Vehicular lane changing time Vehicle fuel consumption Threshold of traffic jam formation

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Research on Data Optimization technology of Multi-Source Sensing Signal in Nuclear Power Plants

SSRN

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SSRN 2023年

作者： Liu, Yongchao Li, Tong Xiao, Kai Chen, Jie Tan, Xin Cheng, Jiahao Tan, Sichao Wang, Bo He, Zhengxi Shen, Jihong Gao, Puzhen Tian, Ruifeng College of Nuclear Science and Technology Harbin Engineering University Harbin150001 China Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150001 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Insitute of China Chengdu610213 China College of Mathematical Sciences Harbin Engineering University Harbin150001 China

The sensor signals collected by the nuclear power plant system equipment are mixed with complex noise information. The uncertainty of sensing data directly affects the application effect of artificial intelligence on nuclear power data mining. Traditional denoising methods have poor adaptability to different noisy data, are highly dependent on researchers, and take a long time. This paper proposes a data optimization technology based on a hybrid adaptive real-time denoising model, which can realize data distribution self-adaptation and algorithm super-parameter self-optimization according to the characteristics of noisy source data. Partition denoising processing of source data. The application of examples and simulation experiments show that this technology can effectively realize the optimization of nuclear power operation data, and provide important technical support for the engineering application of artificial intelligence technology in the complex noise environment of nuclear power plants. © 2023, The Authors. All rights reserved.

关键词： Nuclear energy

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Significant Wave Height Prediction Based on VMD-SA-MLP-BP

Significant Wave Height Prediction Based on VMD-SA-MLP-BP

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2023 China Automation Congress, CAC 2023

作者： Wu, Yining Zhang, Runfeng Liu, Fang Liu, Zhenzhong Wu, Jianguo Dong, Haonan School of Mechanical Engineering Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China Tianjin University of Technology National Demonstration Center for Experimental Mechanical and Electrical Engineering Education China Yichang Research Institute of Testing Technology Yichang443003 China Tianjin Hanhailanfan Marine Technology Co. Ltd. Tianjin300457 China School of Computer Science and Engineering Tianjin University of Technology Tianjin300384 China

ISBN: (纸本)9798350303759

Waves seriously impact port construction, worldwide route planning, military activities, and wave power generation. To improve the accuracy of significant wave height prediction, we proposed a novel prediction method, a multi-layer perceptron combined with a backpropagation adjustment (MLP-BP) prediction model that combines mutation mode decomposition (VMD) and a simulated annealing optimization algorithm (SA). Firstly, we use the variable modulus method to decompose the significant wave height sequence data and transform the wave height sequence into multiple different sub-modes (IMF) to reduce the complexity and non-stationarity of the data. Secondly, the simulated annealing algorithm (SA) is used to optimize the weight and bias of the MLP-BP neural network to find the optimal parameter configuration and improve the performance and generalization ability of the prediction model. Finally, the decomposed sub-modal components of each significant wave height sequence are inserted into the MLP-BP neural network and the predicted values of each element are summed to obtain the final significant wave height prediction. The prediction results of the SSA-MLP-BP, PSO-MLP-BP, SA-MLP-BP, and VMD-SA-MLP-BP were compared and demonstrated that the VMD-SA-MLP-BP model performed best. The MAE, MAPE, MSE, RMSE, and R2 of the prediction evaluation indexes were 0.036 m, 11.7%, 0.004 m2, 0.067 m, and 0.983, respectively, which performed well in predicting significant wave height. © 2023 IEEE.

关键词： Variational mode decomposition

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In-situ Thermal Oxidation of Fusion PFM Tungsten Using Atmospheric Environmental TEM

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Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2023年第1期29卷 1462-1463页

作者： Sainju, Rajat Togaru, Maanas Zhang, Lichun Jiang, Weilin Setyawan, Wahyu Atwani, Osman El Zhu, Yuanyuan Department of Materials Science and Engineering University of Connecticut Storrs CT United States Institute of Materials Science University of Connecticut Storrs CT United States Reactor Materials and Mechanical Design Group Nuclear Sciences Division Pacific Northwest National Laboratory Richland WA United States Materials Science and Technology Los Alamos National Lab Los Alamos NM United States

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

arXiv

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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

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STUDY ON AUTOMATIC DEPRESSURIZATON system OF SMR

STUDY ON AUTOMATIC DEPRESSURIZATON SYSTEM OF SMR

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2020 International Topical Meeting on Advances in Thermal Hydraulics, ATH 2020

作者： Yin, Shasha Sun, Yan Li, Yi Yang, Hongfa Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu China

ISBN: (纸本)9780894487774

Small modular reactor (SMR) is highly cared and researched by people all over the world. There are many differences during reactor operating between the small modular reactor and the traditional large-scale pressurized water reactor, because of the differences in structure and design issues for both reactors. This means that more and better research especially on SMR will be needed. The continued improvements in designing conception of SMR, the research of SMR get to be more in depth and detail. Passive safety system is commonly accepted in the present study, and developed into an indispensable system for the advance nuclear reactor. However, automatic depressurization system (ADS) as an important part of a passive safety system also is a unique system compared with conventional PWR. So ADS system is worthy of comprehensive and in-depth study. In this paper, the severe accident analysis model was established based on the design characteristics of the small modular nuclear. Then, the severe accident process, the thermalhydraulic phenomena and the system safety were researched. Then, based on the results of the severe accident process for SMR, analyze the depressurization capability of ADS system during a station blackout initiated severe accident in SMR, and analysis the effect on accident process. Finally, this paper proposed the optimization and improvement of the automatic depressurization system (ADS). The results of this study are the necessary foundations for the development of small modular reactor severe accident prevention and mitigation measures. © ATH 2020 - International Topical Meeting on Advances in Thermal *** rights reserved.

关键词： Pressurized water reactors

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Study on Uniaxial Tension and Cyclic Deformation Behavior of TA16 at Room Temperature and High Temperature

Study on Uniaxial Tension and Cyclic Deformation Behavior of...

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作者： Shao, Xuejiao Juan, Du kuang, Linyuan Lu, Yuechuan Lu, Jiang Yu, Mingda Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

TA16 is a new type of titanium alloy material, which is widely used in pipeline systems of aerospace, ship and nuclear reactor with high temperature and high pressure. In this paper, the basic mechanical properties and cyclic deformation characteristics of TA16 were obtained by uniaxial tensile test and cyclic loading test at room temperature and high temperature. The Chaboche constitutive model can reasonably describe the cyclic plastic cumulative effect of materials and is provided in ANSYS which is a commercial finite element analysis software. The constitutive model of Chaboche presents a very important evolution criterion of follow-up hardening for ratchet simulation. Based on steady cyclic stress-strain curves which is got by strain control at different temperatures, the material parameters of Chaboche model are obtained by least multiplication fitting for TA16 at room and high temperatures. The constitutive model can used in elastic and elastic finite element analysis of TA16 materials. The experiment results show that TA16 exhibits slight cyclic softening under symmetrical strain cycles, and obvious ratcheting behavior under asymmetric stress cycles. When ratcheting strain of the structure reaches a certain saturation state, plastic accumulation will lead to accidental damage of the structure and lead to serious consequences. The stable cyclic stress-strain curves of TA16 at room temperature and high temperature are simulated by Chaboche model. The simulation results are in good agreement with the experimental results, which provides the basic data for the finite element simulation of cyclic deformation behavior of TA16 titanium alloy structure. © Springer Nature Switzerland AG 2020.

关键词： Constitutive models

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Enhancing Mechanical Properties and Microstructure Evolution of Hybrid Az61-5sic-0.5cnts Composite During Equal Channel Angular Pressing

SSRN

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SSRN 2024年

作者： Zhou, Mingyang Zhao, Yanli Sun, Dan Long, Ziyao Gen, Laiyao Fan, Lingling Gao, Shixin Xin, Yong Quan, Gaofeng Gupta, Manoj Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Mechanical Engineering Chengdu University Chengdu Sichuan610106 China School of Materials Science and Engineering Southwest Jiaotong University Chengdu610031 China 9 Engineering Drive 1 Singapore117576 Singapore

Equal channel angular pressing (ECAP) is one of widely used severe plastic deformation methods for improving performance of metallic materials. In this work, the effects of the ECAP on the microstructural evolution and mechanical properties of the AZ61-5SiC-0.5CNTs composite were studied systematically. The results revealed that ECAP can effectively reduce the porosity of the AZ61-5SiC-0.5CNTs composite, refine grains, weaken basal texture, and promote the further dispersion of CNTs, which can optimize the microstructure of the composite. However, the large shear effect of ECAP also leads to the destruction of the structural integrity of the CNTs and thus reduces the strengthening effect. Due to the combined effects of grain refinement, porosity changes, texture evolution, and structural damage of CNTs, the composites reached the highest strength after 2 ECAP passes at 250 °C. The yield and tensile strengths were increased to 383 MPa (+11.0%) and 445 MPa (+8.0%), respectively, while the elongation was marginally reduced, but remained around 6%. © 2024, The Authors. All rights reserved.

关键词： Equal channel angular pressing

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A simplified two-node coarse-mesh finite difference method for pin-wise calculation with SP3

A simplified two-node coarse-mesh finite difference method f...

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2020 International Conference on Physics of reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020

作者： Zhao, Wenbo Yu, Yingrui Chai, Xiaoming Ning, Zhonghao Zhang, Bin Cai, Yun Liu, Kun Peng, Xingjie Yu, Junchong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

ISBN: (纸本)9781713827245

For accurate and efficient pin-by-pin core calculation of SP3 equations, a simplified two-node Coarse Mesh Finite Difference (CMFD) method with the nonlinear iterative strategy is proposed. In this study, the two-node method is only used for discretization of Laplace operator of the 0th moment in the first equation, while the fine mesh finite difference (FMFD) is used for the 2nd moment flux and the second equation. In the two-node problem, transverse flux is expanded to second-order Legendre polynomials. In addition, the associated transverse leakage is approximated with flat distribution. Then the current coupling coefficients are updated in nonlinear iterations. The generalized eigenvalue problem from CMFD is solved using Jacobi-Davidson method. A protype code CORCA-PIN is developed. FMFD scheme is implemented in CORCA-PIN as well. The 2D KAIST 3A benchmark problem and extended 3D problem, which are cell homogenized problems with strong absorber, are tested. Numerical results show that the solution of the simplified two-node method with 1×1 mesh per cell has comparable accuracy of FMFD with 4×4 meshes per cell, but cost less time. The method is suitable for whole core pin-wise calculation. © The Authors, published by EDP sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://***/licenses/by/4.0/).

关键词： Nonlinear equations

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