检索结果-南通市图书馆

Science China(Technological Sciences) 2019年第5期62卷 721-728页

作者： yu zhijie WEI yueGuang Department of Mechanics and Engineering Science College of Engineering Peking University

Indentation hardness is found to be related to indentation depth when indentation test is applied on homogeneous materials under small indentation depth, which shows strong size effect in the indentation. While in contrast, indentation hardness has a very limited relationship with indentation depth when it is large, showing distinct scaling relationships between hardness and material properties. Previous studies on scaling relationships under deep indentation condition of elastic-perfectly plastic homogeneous materials have been carried out systematically by finite element analysis. In this paper, a heterogeneous material, particlereinforced matrix composite is detailed studied to investigate its scaling relationships under deep indentation with different particle positions and material properties by finite element analysis.

关键词： conical indentation elastic-perfect plastic grain composite scaling relationships

Cross-scale indentation scaling relationships of strain gradient plastic solids:Influence of inclusions near the indenter tip

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Acta Mechanica Sinica 2022年第1期38卷 50-58页

作者： zhijie yu yueguang Wei Department of Mechanics and Engineering Science College of EngineeringB/C-ESATPeking UniversityBeijing 100871China

The indentation test is a localized testing technique;therefore,the role of the material size-effect and local non-uniformity is of much *** influence of the heterogeneity in size-independent materials has been studied *** present work detailedly investigated the influence of the material size-effect and heterogeneity(inclusions near the indenter tip)on the indentation hardness using a size-dependent strain gradient plastic *** it was found that when considering the material size-ffect,shallow hard inclusions in the heterogeneous materials more significantly enhance the material indentation hardness compared with the size-independent materials which are based on the conventional plastic *** hardening effect is be-lieved to be related to the elevation of the load and local constraints of large *** effect of material inhomogeneity mainly comes from the non-uniformity of the structure rather than the inclusion modulus itself especially when the size-effect is involved,and the transition range of the inclusion modulus'influence is pretty *** effect of non-uniformity becomes negligible after the initial inclusion depth is larger than its *** horizontal offset of the indenter from the inclusion is also of much sensitivity to the influence of the heterogeneous *** paper focuses on the scaling relationships in micro-and nanoindentation,the influence of non-uniformity in microscopic materials is studied and supplemented as well.

关键词： Scaling relationships Conical nanoindentation Material size-effect Strain gradient theory

Evaluation of Economical and Intensive Use of Construction Land in a County Town:A case study of Wan’an County,Ji’an City

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Journal of Landscape Research 2024年第1期16卷 51-54页

作者： yu zhijie Jiangxi Normal University NanchangJiangxi 330022China

Taking the changes of construction land in Wan’an County over the years as the research object,the quantity and spatial characteristics of construction land in Wan’an County were analyzed,and the overall situation and regional differences of construction land utilization in Wan’an County were *** the aspects of main influencing factors such as land use structure,land use intensity,land input intensity and output benefit,an evaluation indicator system was established to evaluate the economical and intensive use level of construction land in Wan’an *** results show that the score of the economical and intensive use level of construction land in Wan’an County was 56.92,which was the lowest among all the districts and counties in Ji’an *** on the evaluation results,the corresponding economizing and intensive strategies were put forward,and the safeguard measures for its implementation were *** purpose is to provide some support for the preparation of territorial spatial planning,the delineation of urban development boundaries,and the potential exploitation of construction land stock,hoping to improve the utilization efficiency and benefit of construction land in Wan’an County,and promote the economic growth of Wan’an County to the stage of high-quality development.

关键词： Construction land Economical and intensive utilization Evaluation

Investigation on cross-scale indentation scaling relationships

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Investigation on cross-scale indentation scaling relationshi...

中国力学大会-2021+1

作者： zhijie yu Zhongya Lin Kuanjie Ding yueguang ei Department of Mechanics and Engineering Science BIC-ESATPeking University

Introduction Indentation scaling relationships provide normalized guidance for measuring and predicting mechanical properties in indentation *** the nano-scale,the material sizeeffect is significant,while conventional scaling relationships fail to depict this phenomenon in nanoindentation ***,the indentation test is a localized testing technique;hence the role of the material size-effect and local non-uniformity is of much ***,therefore,investigate the influence of material size-effect and heterogeneity on the indentation tests,and provide a series of closed-form indentation scaling relationships of the size-dependent materials considered by a strain gradient theory.

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固体跨尺度压痕标度律的研究与展望

力学学报 2022年第8期54卷 2085-2100页

作者：於之杰魏悦广北京大学力学与工程科学系北京100871

压痕标度律是对通过压痕试验方法测定固体材料力学性能参量问题所给出的一般性结论,具有重要的理论意义,是探寻材料力学性能潜在规律的方法论研究.本综述论文系统而简要地介绍如下主要内容:采用传统理论对传统固体材料压痕标度律的研究... 详细信息

压痕标度律是对通过压痕试验方法测定固体材料力学性能参量问题所给出的一般性结论,具有重要的理论意义,是探寻材料力学性能潜在规律的方法论研究.本综述论文系统而简要地介绍如下主要内容:采用传统理论对传统固体材料压痕标度律的研究回顾;采用跨尺度力学理论对先进固体材料的跨尺度压痕标度律的研究回顾.总结并得到了如下主要结论:传统固体材料压痕标度律可由一空间曲面完整描绘,若进一步已知某类无量纲独立参量的取值范围,则该空间曲面可退化为系列平面曲线族;先进固体材料(新材料)的跨尺度压痕标度律可由一个三维函数关系完整描绘,若存在某类独立无量纲参量取值范围已知,则该三维函数关系将退化为系列空间曲面族.压痕标度律的未来研究发展仍将重点集中在建立新材料的跨尺度压痕标度律上,以试图从根本上解决新材料力学性能标准规范难以建立的理论问题.除此之外也将重点关注建立各类功能新材料的多尺度及跨尺度压痕标度律规律.

关键词：压痕标度律压痕实验先进材料跨尺度力学理论量纲分析

Research on the Innovation of Ideological and Political Practice Teaching in Universities

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Research on the Innovation of Ideological and Political Prac...

作者： Liping Jiang zhijie yu Qing Jin Hao Zhang Liju Li Heihe University

The characteristic of traditional ideological and political education in colleges and universities is that it focuses on theoretical teaching and emphasizes the teaching of ideological and political theory. The ideological and political theory course is the process of entering the inner life of college students. Based on the traditional ideas, the narrow sense of ideological and political practice teaching will not be able to get rid of the subordinate position of theoretical teaching. In the classroom, video teaching, group discussion and practical homework are all effectively served by ideological and political theory, while the ideological and political theory course's final educational purpose is to train socialism successor. By combing the basic goals of ideological and political education, this paper divides the respective fields of theoretical teaching and practical teaching, thus revealing the particularity of the ideological and political practice class in the organization, training environment and evaluation method, and making useful exploration for the innovation of ideological and political education in colleges and universities.

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地下大空间结构经济性能比较

工业建筑 2006年第z1期36卷 805-808页

作者：俞志杰袁勇上海市城市建设设计研究院上海200433 同济大学地下建筑与工程系上海200092

随着中国城市化的发展,城市地下空间也得到大力开发,大空间、大规模的地下结构应用越来越广泛,从而对地下结构形式提出一些新的问题。根据地下结构的埋深和跨度,探讨了地下大空间的定义和意义;简单概述了目前应用较广的地下结构形式和... 详细信息

随着中国城市化的发展,城市地下空间也得到大力开发,大空间、大规模的地下结构应用越来越广泛,从而对地下结构形式提出一些新的问题。根据地下结构的埋深和跨度,探讨了地下大空间的定义和意义;简单概述了目前应用较广的地下结构形式和现在新兴的地下结构形式,并阐述了它们的优缺点。还从结构经济的角度对各种地下结构体系在不同环境下的各项技术经济指标进行比较,并为工程设计提供参考意见,最后举出两个具体工程实例。

关键词：地下结构地下大空间结构经济实例结构设计

Maternal serum branched-chain amino acids in early pregnancy and offspring growth patterns from 1 year to 8 years of age

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Chinese Medical Journal 2024年第15期137卷 1876-1878页

作者： Ninghua Li Junhong Leng Rui Zhang Hui Wang Weiqin Li Shuang Zhang Yijuan Qiao Jing Li zhijie yu Gang Hu Zhongze Fang Xilin Yang Department of Epidemiology and Biostatistics School of Public HealthTianjin Medical UniversityTianjin 300070China Project Office Tianjin Women and Children’s Health CenterTianjin 300070China Tianjin Key Laboratory of Environment Nutrition and Public HealthTianjin 300070China Tianjin Center for International Collaborative Research on Environment Nutrition and Public HealthTianjin 300070China Population Cancer Research Program and Department of Pediatrics Dalhousie University15000HalifaxCanada Chronic Disease Epidemiology Laboratory Pennington Biomedical Research CenterBaton RougeLA 70808USA Department of Toxicology and Sanitary Chemistry School of Public HealthTianjin Medical UniversityTianjin 300070China

to persist into adulthood and be associated with many adverse health outcomes later in adulthood,including cardiovascular diseases and type 2 diabetes.[1]In utero exposure to“undernutrition”or“over-nutrition”plays an important role in obesity in childhood and diseases in adulthood.[2]It is established that high branchedchain amino acids(BCAAs)are associated with insulin resistance and gestational diabetes mellitus(GDM).[3]However,it is largely unknown whether in utero exposure to high BCAAs also plays a role in adverse childhood growth *** used 8-year children follow-up data of a case-control study nested within a population-based prospective cohort of pregnant women in Tianjin,China,to examine associations between maternal BCAAs levels in early pregnancy and obesity-related growth patterns if any,in offspring at 1-8 years of age.

关键词： BCAA pregnancy obesity

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上海房地产交易服务网的应用与研究

计算机应用与软件 2007年第12期24卷 210-211,221页

作者：俞旨捷周忠上海市房地产交易中心上海200120 上海市计算技术研究所上海200040

介绍和研究了上海房地产交易服务网站的系统架构,系统各子系统功能的应用、系统的安全措施以及对将来可能发展的探索。

关键词：上海房地产交易网站系统架构系统功能系统安全措施

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地方政府债务的问责监管与制度完善

金融发展研究 2023年第9期 48-53页

作者：于志洁王茂庆中共潍坊市委党校山东潍坊262406 山东科技大学文法学院山东青岛266590

问责制被运用于地方政府债务领域,对加强地方政府债务监管、防范化解债务风险具有重要意义。从现行制度看,问责监管集中在隐性债务领域,显性债务领域存在问责缺位问题。由于显性债务规模急剧扩张、偿债压力日益显现、债务风险愈加现实,... 详细信息

问责制被运用于地方政府债务领域,对加强地方政府债务监管、防范化解债务风险具有重要意义。从现行制度看,问责监管集中在隐性债务领域,显性债务领域存在问责缺位问题。由于显性债务规模急剧扩张、偿债压力日益显现、债务风险愈加现实,应当确立对隐性债务进行风险问责、对显性债务进行绩效问责的合并问责监管,同时积极推进问责监管的制度化、法治化,并确立穿透式监管原则。

关键词：隐性债务显性债务问责监管制度完善

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