基于机会成本的终端用户可靠性电价测算

文章基于可靠性电价"高质高价"的市场化原则,根据供电可靠率和限电序位表,运用机会成本的原理,设计出终端用户的加权可靠率指标,作为用户可靠性电价的成本分摊依据,从而构建出终端用户的可靠性电价测算模型.文章以国内某地区电网公司的实际数据,选取高中低不同可靠性的样本用户,测算了各类用户适用的可靠性电价.研究结果表明,实施终端用户可靠性电价的改革有助于提高整个社会的用电经济效益;测算结果对于中国优化销售电价结构的市场化改革具有实践上的参考价值.     

教育问卷调查的测量学思考

教育问卷调查法是一种教育研究的常用方法。但该方法在使用过程中往往存在着一些问题 ,影响了问卷调查法的科学性。本文认为重视问卷设计中的理论构思 ,使问卷的量化过程符合测理学原理 ,并对问卷进行信度和效度的考证 ,将有助于提高问卷调查法的科学性     

Career decision-making,career exploration behaviors,and self-regulated learning

Helping individuals make a career decision is a key aim of career counseling. Determining how to encourage self-regulated learning and behaviors needed to achieve this goal often underlies career interventions. The English version of the Career Exploration Behavior survey (CEB-E) measures activities individuals engage in to learn about career options. The present study explored the psychometric properties of the CEB and its impact on various career outcomes. In the first study (N = 498), a good-fitting second-order factor model with four group-level scales and loadings was retained as the best model. In the second study (N = 143), convergent validity and incremental validity of the CEB dimensions were explored through correlation and regression analyses. The CEB predicted commitment making, metacognitions, and vocational identity. Results suggest the CEB-E is a psychometrically sound assessment of career exploration behaviors with potential utility for theory development, program evaluation, and monitoring client progress.     

汉英语篇思维差异对大学英语写作的影响

探讨了汉英思维差异及汉英语篇思维差异对大学英语写作的影响,并进一步分析了汉英语篇思维差异在非英语专业学生的英语写作中表现出的各种形式,指出消除汉语式作文的关键在于提高学生跨文化意识,重视语篇教学并把语法教学同培养语言实际能力结合起来。     

周转件构成的可修复系统的可靠性分析

系统在运行期间因部件失效而发生故障,进行更换维修后,系统部件的使用时间分布发生变化,系统可靠性指标的值也随之变化,对此情况下系统可靠性分析方法进行了研究。将一定范围内同类部件的整体看作系统,并考察全部由周转件构成的系统,通过对各个时刻系统内部件的使用时间以及维修次数分布建立数学模型,得到了系统可靠度随系统运行时间的增加而减小,系统部件更换率随系统运行时间增加而增加的结论。并通过航空公司的实际数据对结果进行了验证。分析结果为备件采购计划、部件梯次使用计划和维修策略的制订具有重要意义。     

自评一般健康的信度和效度分析

本文利用2008年“中国流动与健康调查”（IMHC）数据,分析了自评一般健康指标的信度和效度。研究发现,自评一般健康具有较好的信度,被访者先后两次回答的结果高度一致,两次回答结果的微小变动表现为随机性的波动,而非系统性偏差。该指标在一定程度上会受到调查中题目次序效应的影响。关于自评一般健康指标效度的分析发现,该指标能够有效反映被访者自我感知的各种健康状态和个体既有的关于自身健康的知识,但不能很好地反映个体无法感知的机体变化等健康问题。自评一般健康存在较为复杂的回答偏误问题,受不同年龄、社会经济地位群体关于健康的评价标准、期望与认知差异的影响,其回答结果在不同人群中的可比性值得商榷。     

大型工程项目施工系统可靠性评估

施工系统的可靠性评估有助于减少项目风险、优化工程目标。文章综合考虑项目质量、成本、时间和安全目标,提出基于有序二元决策图(OBDD)的施工系统可靠性评估方法。该方法便于计算机实现,具有很高的计算效率,适合大型工程项目。最后,通过算例演示了施工系统可靠性的评估过程,并验证了该方法。     

基于M/M/s/N/∞顾客排队的供应链系统可靠度研究

论文研究了带有M/M/s/N/∞排队系统的零售商一制造商混联供应链系统的可靠度,研究发现零售商一制造商混联供应链系统的可靠度随着零售商服务强度的增大而减小,随着制造商服务台数目和系统容量的增大而增大;可以通过提高服务台平均服务速率,增加制造商服务台数目和系统容量提高该混联供应链系统的可靠度;最后还考虑了该混联供应链系统的可靠度优化问题。该研究对于丰富供应链系统的可靠度理论和指导供应链系统可靠度控制实践有一定的参考意义和应用价值。     

Phase type stress–strength models with reliability applications

The stress–strength model has attracted a great deal of attention in reliability analysis, and it has been studied under various modeling assumptions. In this article, the stress–strength reliability is studied for both single unit and multicomponent systems when stress and strength distributions are of phase type. Phase-type distributions, besides their analytical tractability, are a versatile tool for modeling a wide range of real life systems/processes. In particular, matrix-based expressions are obtained for the stress–strength reliability, and mean residual strength for an operating system. The results are illustrated for Erlang-type stress–strength distributions for a single unit system and a system having a general coherent structure. An example on the comparison of two multi-state units in stress–strength ordering is also presented.     

Copula-based reliability analysis for a parallel system with a cold standby

The traditional reliability models cannot well reflect the effect of performance dependence of subsystems on the reliability of system, and neglect the problems of initial reliability and standby redundancy. In this paper, the reliability of a parallel system with active multicomponents and a single cold-standby unit has been investigated. The simultaneously working components are dependent and the dependence is expressed by a copula function. Based on the theories of conditional probability, the explicit expressions for the reliability and the MTTF of the system, in terms of the copula function and marginal lifetime distributions, are obtained. Let the copula function be the FGM copula and the marginal lifetime distribution be exponential distribution, a system with two parallel dependent units and a single cold-standby unit is taken as an example. The effect of different degrees of dependence among components on system reliability is analyzed, and the system reliability can be expressed as the linear combination of exponential reliability functions with different failure rates. For investigating how the degree of dependence affects the mean lifetime, furthermore, the parallel system with a single cold standby, comprising different number of active components, is also presented. The effectiveness of the modeling method is verified, and the method presented provides a theoretical basis for reliability design of engineering systems and physics of failure.