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A non-probabilistic reliability topology optimization method based on aggregation function and matrix multiplication considering buckling response constraints

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 321-336页

作者： Lei WANG Yingge LIU Juxi HU weimin chen Bing HAN Institute of Solid Mechanics School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China Aircraft and Propulsion Laboratory Ningbo Institute of TechnologyBeihang UniversityNingbo 315100Zhejiang ProvinceChina State Key Laboratory of Navigation and Safety technology Shanghai Ship and Shipping Research InstituteShanghai 200135China National Engineering Research Center of Ship&Shipping Control System Shanghai Ship and Shipping Research InstituteShanghai 200135China

A non-probabilistic reliability topology optimization method is proposed based on the aggregation function and matrix *** expression of the geometric stiffness matrix is derived,the finite element linear buckling analysis is conducted,and the sensitivity solution of the linear buckling factor is *** a specific problem in linear buckling topology optimization,a Heaviside projection function based on the exponential smooth growth is developed to eliminate the gray *** aggregation function method is used to consider the high-order eigenvalues,so as to obtain continuous sensitivity information and refined structural *** cyclic matrix programming,a fast topology optimization method that can be used to efficiently obtain the unit assembly and sensitivity solution is *** maximize the buckling load,under the constraint of the given buckling load,two types of topological optimization columns are *** variable density method is used to achieve the topology optimization solution along with the moving asymptote optimization *** vertex method and the matching point method are used to carry out an uncertainty propagation analysis,and the non-probability reliability topology optimization method considering buckling responses is developed based on the transformation of non-probability reliability indices based on the characteristic ***,the differences in the structural topology optimization under different reliability degrees are illustrated by examples.

关键词： buckling topology optimization aggregation function uncertainty propagation analysis non-probabilistic reliability

High-Level Security Dimension Evaluation of Blockchain BaaS System and Key technology

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china Communications 2024年第6期21卷 176-191页

作者： chen Wanfa zheng Qing’an chen Shuzhen Fu Hongyi chen Liang Fujian Police College Fuzhou 350007China Computer science and Information Security Management department Fujian Police CollegeFuzhou 350007China Fujian Province Key Laboratory for Digital Network Crime Supervision and Prevention Fuzhou 350007China beijing university of Posts and Telecommunications Beijing 100876China Fujian Provincial Prison Administration Fuzhou 350002China

In recent years,blockchain technology integration and application has gradually become an important driving force for new technological innovation and industrial *** blockchain technology and applications are developing rapidly,the emerging security risks and obstacles have gradually become *** can still find security issues in blockchain systems and conduct attacks,causing increasing losses from network attacks every *** response to the current demand for blockchain application security detection and assessment in all industries,and the insufficient coverage of existing detection technologies such as smart contract detectiontechnology,this paper proposes a blockchain core technology security assessment system model,and studies the relevant detection and assessment key technologies and systems.A security assessment scheme based on a smart contract and consensus mechanism detection scheme is *** the underlying blockchain architecture supports the traceability of detection results using super ***,the functionality and performance of the system were tested,and the test results show that the model and solutions proposed in this paper have good feasibility.

关键词： blockchain security consensus mechanis smart contract

Remarkable Wear Resistance in a Complex Concentrated Alloy with Nanohierarchical Architecture and Composition Undulation

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Research 2024年第1期2023卷 403-416页

作者： Yushan Geng Wenyuan chen Hui Tan Jun cheng Shengyu Zhu Jun Yang weimin Liu State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000PR China Center of Materials science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049PR China Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing Yantai 264000PR China

Sustained wear damages on the sliding surfaces of alloys are generally the culprit responsible for the failure of various mechanical *** by high-entropy effects,here we deliberately deploy nanohierarchical architecture with composition undulation in a Ni50(AlNbTiV)_(50) complex concentrated alloy,which yields ultralow wear rate within the order of 10^(−7) to 10^(−6) mm^(3./Nm between room temperature and 800℃.Such remarkable wear resistance heretofore represents one of the highest wear resistance reported for the bulk alloys or composites,and originates from the multi-type adaptive friction interface protection governed by intrinsically nano-coupled grains and *** cooperative heterostructure releases gradient frictional stress in stages upon wear at room temperature through the coexistence of multiple deformation pathways while activating a dense nanocrystalline glaze layer upon wear at 800℃ to minimize adhesive and oxidative *** work uncovers a practical avenue for tailoring wear properties with multicomponent heterostructures over a wide temperature range.

关键词： wear alloys friction

Building a High-Performance Graph Storage on Top of Tree-Structured Key-Value Stores

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Big Data Mining and Analytics 2024年第1期7卷 156-170页

作者： Heng Lin Zhiyong Wang Shipeng Qi Xiaowei Zhu Chuntao Hong wenguang chen Yingwei Luo School of Computer science Peking UniversityBeijing 100871China Ant Group Beijing 100020China department of Computer science and technology Tsinghua UniversityBeijing 100084China

Graph databases have gained widespread adoption in various industries and have been utilized in a range of applications,including financial risk assessment,commodity recommendation,and data lineage *** the principles and design of these databases have been the subject of some investigation,there remains a lack of comprehensive examination of aspects such as storage layout,query language,and *** present study focuses on the design and implementation of graph storage layout,with a particular emphasis on tree-structured key-value *** also examine different design choices in the graph storage layer and present our findings through the development of TuGraph,a highly efficient single-machine graph database that significantly outperforms well-known Graph DataBase Management System(GDBMS).Additionally,TuGraph demonstrates superior performance in the Linked Data Benchmark Council(LDBC)Social Network Benchmark(SNB)interactive benchmark.

关键词： graph database high-performance graph storage

Who could and should give exercise prescription:Physicians,exercise and health scientists,fitness trainers,or ChatGPT?

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Journal of Sport and Health science 2024年第3期13卷 368-372页

作者： Weimo Zhu wenguang Geng Lingling Huang Xiong Qin Zezhao chen Hai Yan Yunnan Plateau Thermal Health Industry Innovation Research Institute Tengchong 679100China department of Kinesiology&Community Health University of Illinois at Urbana-ChampaignUrbanaIL 61801USA department of Physical Education Nanjing Agricultural UniversityNanjing 210095China School of Sports Engineering Beijing Sport UniversityBeijing 100084China School of Strength and Conditioning Training Beijing Sport UniversityBeijing 100084China

Benefits of exercise for personal health,as well as preventing and treating chronic diseases,have been well documented during the past several decades.1 Exercise prescription is a specialized field that involves assessing an individual’s health status,fitness level,and specific goals to create a tailored exercise program based often on the FITT-VP principle.

关键词： prescription diseases assessing

The impact of the Rural Minimum Living Standard Guarantee(Rural Dibao)Program on child nutrition outcomes

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Journal of Integrative Agriculture 2024年第2期23卷 444-456页

作者： Dian chen Xiangming Fang Yu chen Xiaodong zheng Zhuo chen Rodney B.W.Smith Academy of Global Food Economics and Policy China Agricultural UniversityBeijing 100083China School of Public Health Georgia State UniversityAtlanta 30303USA School of Economics Zhejiang Gongshang UniversityHangzhou 310018China College of Public Health University of GeorgiaAthens 30602USA department of Applied Economics University of MinnesotaSaint Paul 55108USA

The Rural Minimum Living Standard Guarantee(Rural Dibao)is an important unconditional cash transfer program to alleviate poverty in rural *** the importance of children’s nutrition in breaking poverty cycles,little is known about the impact of Rural Dibao on child nutrition *** china Family Panel Studies(CFPS),this paper examines the effects of Rural Dibao on child nutrition outcomes and investigates potential pathways and heterogeneous *** exploit propensity score matching and difference-in-differences techniques to evaluate the effects of the Rural Dibao program on child nutrition *** results suggest that Rural Dibao significantly impacts the nutrition outcomes of children up to 15 years of ***,our results suggest that Rural Dibao improves child height-to-age z-scores by 1.05 standard deviations and lowers the probability of stunting by 11.9 percentage *** analyses suggest that increased protein intake is the main pathway through which Rural Dibao participation contributes to better nutrition *** also find that the effect of the program is more pronounced among girls,children who are non-left-behind or live with highly educated mothers,and those from low-income families and poor *** findings suggest that Rural Dibao participation helps improve child nutrition outcomes through improving diet quality.

关键词： Rural Minimum Living Standard Guarantee nutrition height-to-age z-scores stunting rural china

Gradient coil design with enhanced shielding constraint for a cryogen-free superconducting MRI system

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Magnetic Resonance Letters 2024年第1期4卷 1-9页

作者： Yaohui Wang weimin Wang Hui Liu Shunzhong chen Feng Liu Qiuliang Wang Institute of Electrical Engineering Chinese Academy of SciencesBeijing100190China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing100049China School of Electronics&Institute of Biomedical Engineering Peking University&Shenzhen Graduate SchoolShenzhen518055China School of Information technology and Electrical Engineering The University of QueenslandSt LuciaBrisbaneQLD4072Australia

The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI *** this study,we present an enhanced shielding method incorporating a regionalized stray field constraining *** optimizing the constraint parameters,we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by *** real measurement in an integrated MRI system,the developed gradient assembly demonstrated good performance and supported to output images of excellent *** findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.

关键词： MRI Gradient coil Superconducting magnet Cryogen-free Magnetic shielding

An introduction to tsinghua Cloud

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science china(Information sciences) 2010年第7期53卷 1481-1486页

作者： zheng weimin1,2 1department of Computer {3. and technology, tsinghua university, beijing 100084, china 2tsinghua National Laboratory for Information {3. and technology, beijing 100084, china 1. department of Computer science and technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Cloud computing has become a trend that draws attention from both academia and industry all over the world. This paper unveils details of tsinghua Cloud, a comprehensive solution for cloud computing developed by Tsing... 详细信息

关键词： cloud computing distributed file system virtual computing environment data sharing

Optimizing write operation on replica in data grid

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science china(Information sciences) 2011年第1期54卷 1-11页

作者： XU PengZhi,WU YongWei,HUANG XiaoMeng, YANG GuangWen & zheng weimin department of Computer {3. and technology,tsinghua university,beijing 100084,china 1. department of Computer science and technology Tsinghua University Beijing 100084 China

Replication technique can improve access performance and data availability of data grid systems. So far,most related work on data replication in data grid systems focuses on read-only *** write operations have been widely used in practice,its optimization problem has not been suciently *** this paper,we show that write requests from users can be processed by a nearest site,regardless of the location of latest written *** policy of write nearby instead of write to the latest replica can improve the performance of write operations,while inconsistency is caused between multiple ***,we propose two metadata management algorithms to make sure that users can retrieve up-to-date datasets at any *** extend OptorSim to support the implementation and evaluation of our *** results of simulation show that our scheme achieves performance gains up to 3.3.compared with WriteMaster scheme.

关键词： replication data grid simulation access latency