Bayes prediction of number of failures in weibull samples

This work is concerned with the Bayesian prediction problem of the number of components which will fail in a future time interval, when the failure times are Weibull distributed. Both the 1-sample and the 2-sample prediction problems are dealed with, and some choices of the prior densities on the distribution parameters are discussed which are relatively easy to work with and allow different degrees of knowledge on the failure mechanism to be incorporated in the predictive procedure. Useful relations between the predictive distribution on the number of future failures and the predictive distribution on the future failure times are derived. Numerical examples are also given.     

认知语境视角下社交语用失误成因分析

跨文化交际的本质是人与人之间的交际,对社交语用失误的解读必须考虑交际参与者的主观能动性和认知能力.在跨文化交际中,若认知心理状态不同的交际者对彼此制约交际的社交文化规约的心理可及程度较低,加上交际的瞬时性和省力原则的作用,说话人对听话人的认知语境假设选择的判断可能与听话人的真实认知语境假设选择不符,使得听话人推理出的说话人交际意图和说话人真实的交际意图不一致,从而导致社交语用失误.     

跨文化交际中的语用失误及策略研究

随着跨国交际日益增多,跨文化交际中的语用失误问题突显,由于思维方向不同,文化背景差异、母语负迁移等原因造成交际的冲突和失败。跨文化交际的语用失误需要依靠交际双方的顺应和宽容,提高对目的语文化的领悟力和敏感性去解决。     

三牙轮钻头滑动轴承失效分析

三牙轮钻头轴承的使用寿命直接决定了钻头的寿命。为了弄清三牙轮钻头轴承的失效形式、原因及机理，进一步提高三牙轮钻头轴承的寿命，分别对现场失效的三牙轮钻头轴承进行宏观和微观分析。结果表明，密封系统失效是轴承失效的主要原因之一。同时，轴承所受载荷过大且分布不均，温度过高导致材料表面金属强度和耐磨性降低，以及轴承与牙轮之间配合间隙过大，工作时晃动导致受力不均等原因也是造成牙轮钻头轴承的快速失效的主要原因。     

Reliability Research of Dependent Failure Systems Using Copula

The computation of reliability characteristics of a system that consists of dependent components sometimes becomes difficult, especially when a specific type of dependence is not identified. In this paper, some systems with arbitrary dependent components are studied using copula. In the system, the components are dependent on each other and the dependent relations may be either linear or nonlinear correlation. The efficient formulas are presented to compute the reliability characteristics, such as reliability function, failure rate and meantime to failure of series, parallel and k-out-of-n systems. The reliability functions of dependant systems are compared with independent system. At last, the numerical examples are presented to illustrate the results obtained in this paper.     

A class of semiparametric transormation frailty models with application to estimating treatment effects and heterogenity in aids clinical traials

Muitivariate failure time data are common in medical research; com¬monly used statistical models for such correlated failure-time data include frailty and marginal models. Both types of models most often assume pro¬portional hazards (Cox, 1972); but the Cox model may not fit the data well This article presents a class of linear transformation frailty models that in¬cludes, as a special case, the proportional hazards model with frailty. We then propose approximate procedures to derive the best linear unbiased es¬timates and predictors of the regression parameters and frailties. We apply the proposed methods to analyze results of a clinical trial of different dose levels of didansine (ddl) among HIV-infected patients who were intolerant of zidovudine (ZDV). These methods yield estimates of treatment effects and of frailties corresponding to patient groups defined by clinical history prior to entry into the trial.     

对学生学业成绩实施标准分处理与定比例淘汰制初探

根据教育统计学的思想 ,改革现行的学生学业成绩管理办法 ,将竞争激励机制引入教学管理过程中 ,提出了对学生学业成绩实施标准分处理与定比例淘汰的新的成绩管理模式 ,从而使长期以来形成的“60分万岁”的不良现象 ,基本上得到了解决。     

论行政行为补正制度

行政行为补正是行政主体在一定期限内对程序存在轻微瑕疵的行政行为进行的补救,通过补正使原来违法的行政行为成为合法行政行为并维持其法律效力。行政行为补正的理论依据有行政程序双重价值理论、信赖保护原则、公正与效率的价值目标三个方面。目前我国行政行为补正制度并不完善,有必要借鉴国外相关立法经验,构建我国统一的行政行为补正制度。     

Probabilistic Reliability Modeling for Oil Exploration & Production (E&P) Facilities in the Tallgrass Prairie Preserve

The aging domestic oil production infrastructure represents a high risk to the environment because of the type of fluids being handled (oil and brine) and the potential for accidental release of these fluids into sensitive ecosystems. Currently, there is not a quantitative risk model directly applicable to onshore oil exploration and production (E&P) facilities. We report on a probabilistic reliability model created for onshore exploration and production (E&P) facilities. Reliability theory, failure modes and effects analysis (FMEA), and event trees were used to develop the model estimates of the failure probability of typical oil production equipment. Monte Carlo simulation was used to translate uncertainty in input parameter values to uncertainty in the model output. The predicted failure rates were calibrated to available failure rate information by adjusting probability density function parameters used as random variates in the Monte Carlo simulations. The mean and standard deviation of normal variate distributions from which the Weibull distribution characteristic life was chosen were used as adjustable parameters in the model calibration. The model was applied to oil production leases in the Tallgrass Prairie Preserve, Oklahoma. We present the estimated failure probability due to the combination of the most significant failure modes associated with each type of equipment (pumps, tanks, and pipes). The results show that the estimated probability of failure for tanks is about the same as that for pipes, but that pumps have much lower failure probability. The model can provide necessary equipment reliability information for proactive risk management at the lease level by providing quantitative information to base allocation of maintenance resources to high-risk equipment that will minimize both lost production and ecosystem damage.     

公共选择理论视角下的政府失灵及对策

公共选择理论指出,政府的自利性是造成政府失灵的重要原因。因此,要治理政府失灵,必须从制度上克制其自利性,一方面限制政府经济职权范围和立法活动,并加强对政府行为的监督;另一方面引入竞争机制,打破行政垄断,移植市场化的经营模式改进政府运作,通过法治化和市场化的手段提高政府干预经济活动的效率。