温度应力、自收缩对高性能混凝土早期开裂的影响

根据高性混凝土的水化特性、物理力学特性及自收缩特性，分析了高性能混凝土早期开裂机理和影响早期开裂的主要因素．并结合工程实例，借助混凝土温度和应力有限元仿真计算方法分析研究了表面适度保温和水管冷却技术在高性能混凝土温控防裂中的应用效果．研究结果表明，表面适度保温与水管冷却相结合能有效降低混凝土的内外温差，减小混凝土早期表面拉应力与后期内部拉应力，防裂效果明显，对类似的工程具有借鉴作用．     

三峡工程大坝混凝土长龄期耐久性能试验研究

混凝土的耐久性能直接影响混凝土结构的使用寿命。本文通过对三峡工程大坝混凝土进行龄期长达10年的耐久性能试验研究,分析了混凝土抗冻性能、抗渗性能以及混凝土碳化深度,抗冻性能随龄期的变化规律,不同养护条件对混凝土耐久性能随龄期发展规律的影响。研究表明,自然养护对混凝土长龄期耐久性能不利。研究结论可为长期工作条件下大坝混凝土的真实性能和结构安全性评价提供参考。     

Towards the use of chronological age in research – A cautionary comment

In recent years, this journal published several articles that used chronological age in their models to distinguish customer behavior between younger and older people. While all these articles are in line with the growing importance of age-related research, chronological age is not discriminant when behavior and motivations enter the fray. By taking two recent articles in this journal as examples, this short note calls for a cautious application of chronological age and highlights other age-related constructs for research. The note ends with practical implications and avenues for further research in age-related projects.     

存款保险制度在我国的实行和相关配套政策

存款保险制度的建立和实行对我国银行业的发展具有极其重要的作用.主要结论有:一、现行银行制度在其承担流动性保险功能时有其固有的脆弱性,存款保险制度则可以为类型存款人取款提供一种有效的制度保障;二、我国隐性"超级"存款保险制度的现状加剧了道德风险,亟待出台显性存款保险制度;三、风险预警机制替代市场监控能较好地解决存款保险制度无法解决的信息不对称问题,为存款保险降低道德风险创造条件.     

Perceived Determinants of Well-Being and Enjoyment Level of Leisure Activities

Two facets of leisure, perceived determinants of well-being and enjoyment of common leisure activities, were investigated in 388 participants. For well-being, a principal components (PCA) analysis yielded five components: competence, relatedness and health, wealth, personal values, and freedom of choice. For the enjoyment of leisure activities, another PCA generated seven components: wellness, sedentary leisure, intellectual leisure, social leisure, routine activities, self-realization, and inner peace. Different leisure enjoyment of young adults (18–30 years old) in contrast to adults and seniors was attributed to social transformations as also predicted by several theories of social change. The relationship between the determinants of well-being and enjoyment of leisure activities was statistically significant but meaningfully debatable.     

新冠肺炎疫情对供应链弹性管理的启示

新冠肺炎疫情将对中国产业供应链的持续竞争力形成挑战,使企业面临人力短缺、成本增加、现金流紧张和供应链不确定性增高等问题,在企业供应链的原材料供应、采购管理、生产复工、物流以及市场等方面均会产生一定的负面影响,这对供应链弹性管理提出了新的要求。在政府层面,应建立综合、协同性的产业供应链风险管理和沟通机制,构建基于事件的产业供应链预警体系,保障企业供应链运营的资源体系,推动产业平台和产业集群带动供应链参与者建立供应链弹性体系。在企业层面,应建立基于企业事件的供应链预警体系,根据供应链预警信息和状况,合理规划供应链运营方式,运用数字化能力建设企业供应链弹性体系,稳定供应链运营,提升供应链效率。     

Application of early risk detection concepts and methods to environmental health. A German feasibility study

Early risk detection is essential for being able to address the most important environmental health risk‐topics in a persistent and prospective manner. In support of the action programme “Environment and Health” (APUG) of the German Federal Ministry of Health and Social Security (BMGS) and the Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU) which recommended that a detection and evaluation system for the timely recognition of emerging risk problems be developed, a qualitative feasibility study was commissioned. The results of this study are presented here and support the development of an early risk detection system based on the insights gained from the investigation of case studies and the differentiation and presentation of a risk typology, methods, tools, and suggested organizational processes.

The study has shown that early risk detection includes the identification, characterization, evaluation and dissemination of information on possible risks as well as the circumstances of appearance and distribution. The goal is the recognition of possible risks in order for risk management to be able to introduce swift and appropriate measures. Consequently, it can also serve as an instrument towards further development of a balanced and structured implementation of the precautionary principle in the environmental health policy.     

浅谈企业财务预警系统的构建

当前国内外不少企业陷入危机甚至倒闭 ,笔者认为建立企业财务预警系统已势在必行。本文就如何构建企业财务预警系统作了一些探讨 ,并提出完善企业财务预警系统的几点建议     

基于改进粒子群优化算法的BP神经网络在大坝变形分析中的应用

BP神经网络以其对非线性系统的强大映射能力而被广泛应用于模糊性、随机性强的大坝变形预测分析中。传统的BP神经网络由于初始权值和阈值的随机性,容易导致网络在训练过程中极易陷入局部最小值,同时存在网络收敛速度慢等缺点。针对传统算法的不足,采用改进的粒子群算法(IPSO)对BP网络的初始权值和阈值给予优化,建立大坝变形预测的IPSO-BP模型,并与PSO-BP网络模型进行对比。结果表明,改进的IPSO-BP模型具有收敛速度更快、预测精度更高的优点。该方法可供大坝安全监测和预警分析参考。     

新老混凝土缝面切向刚度早龄期发展规律

由于缺乏新老混凝土缝面早龄期力学性能发展规律的研究,一般认为大体积混凝土浇筑块间歇面强度与浇筑块相同,由此导致间歇面上下层新老混凝土相互约束偏大,从而使浇筑块内部的应力计算值偏大。设计了新老混凝土缝面早龄期剪切试验, 获取了需要的参数历时曲线,然后将该成果应用到实际混凝土坝工程的施工期温度场和应力场仿真计算。计算结果表明,在间歇面上设置缝面单元,并考虑其早龄期强度发展,可以相对合理地模拟约束情况,计算得到的浇筑块拉应力值相对较小,更符合实际情况。