Bayesian System Reliability Prediction

In system reliability studies a common problem is the coherent assessment of system reliability, based on generic database information from components and on failure data from a system and its components in a common, but unknown, environment. A solution to this problem is given.     

Conservatism of the Accident Sequence Evaluation Program HRA Procedure

This paper presents a limited assessment of the conservatism of the Accident Sequence Evaluation Program (ASEP) human reliability analysis (HRA) procedure described in NUREG/CR-4772. The data for this study are derived from simulator examination reports from the NRC requalification examination cycle for nuclear power plant operators. The ASEP procedure was used to estimate human error probability (HEP) values for critical tasks, and the HEP results were compared with the failure rates observed in the examinations. The ASEP procedure was applied by PNNL operator license examiners who supplemented the limited information in the examination reports with expert judgment based upon their extensive simulator examination experience. Comparison of the average of the ASEP HEP values with the fraction of the population actually failed and demonstrated that the ASEP HEP values are larger (conservative) by a statistically significant average factor of two. Partitioning of tasks into subgroups based on the ASEP HEP values and comparison of the subgroup average ASEP HEP values with observed subgroup failure rates showed little or no conservatism for small ASEP HEP values, but considerable conservatism for larger ASEP HEP values.     

外语学习策略研究中存在的主要问题及其对策

探讨了当前国内外外语学习策略研究中存在的一些主要问题,包括术语问题、分类问题、效度和信度问题、研究内容问题、研究方法问题和代表性问题,并针对这些问题提出了相应的对策.     

TEM-8人文知识项目试题评析及其反拨效应

本文结合近两年TEM-8实考试题,针对其新增题型(人文知识项目),从必要性、信度、效度与反拨效应等几个方面进行了简要评析.     

An alternative estimator for multiple characteristics in PPS sampling

The problem considered relates to large-scale sample surveys. A new estimator of population total for the characteristics that are poorly correlated with the selection probabilities has been developed for the PPSWR sampling scheme. The relative efficiency of the proposed estimator has been studied under a super-population model. A numerical investigation into the performance of the estimator has also been made.     

对大学英语一份试卷的分析

IntroductionThis analysis first presents the relevant infor-mation about the test paper that the author used inChina in 2003.Then it evaluates the test in the as-pects of content validity,construct validity and re-liability in scoring.For those deficiencies exhibitedby the test,some suggestions are provided on howto improve the test in order to achieve validity,re-liability and practicality.Background informationThe test purpose.This was an achievement testfirmly based on the syllabus and th…     

Effects of Remanufacturable Product Design on Market Segmentation and the Environment

Despite documented benefits of remanufacturing, many manufacturers have yet to embrace the idea of tapping into remanufactured‐goods markets. In this article, we explore this dichotomy and analyze the effect of remanufacturable product design on market segmentation and product and trade‐in prices by studying a two‐stage profit‐maximization problem in which a price‐setting manufacturer can choose whether or not to open a remanufactured‐goods market for its product. Our results suggest that it is optimal for a manufacturer to design a remanufacturable product when the value‐added from remanufacturing is relatively high but product durability is relatively low and innovation is nominal. In addition, we find that entering a remanufactured‐goods market in and of itself does not necessarily translate into environmental friendliness. On the one hand, the optimal trade‐in program could result in low return and/or remanufacturing rates. On the other hand, a low price for remanufactured products could attract higher demand and thereby potentially result in more damage to the environment. Meanwhile, external restrictions imposed on total greenhouse gas emissions draw criticism in their own right because they risk stifling growth or reducing overall consumer welfare. Given these trade‐offs, we therefore develop and compare several measures of environmental efficiency and conclude that emissions per revenue can serve as the best proxy for emissions as a metric for measuring overall environmental stewardship.     

涡旋压缩机异形封头可靠性设计

为评估异形封头结构在涡旋压缩机运行过程中的可靠性,参考压力容器椭圆形封头设计理论,采用常规设计方 法对封头进行了结构设计和强度校核;基于封头材料性能、结构尺寸等设计参数的分散性,将各参数作为正态分布的基 本变量,对封头结构进行了可靠性设计,并对基本变量分布参数的灵敏度进行分析。计算结果表明,与常规设计方法相 比,可靠性设计在确保结构安全性的前提下,同时保证了设计的经济性;影响封头可靠度的主要因素是材料屈服极限、工 作压力和壁厚。     

二阶电路完全响应的计算机辅助教学研究

本文从理论上研究了二阶电路完全响应的检测理论，讨论了用MCS－51单片机控制的二阶电路辅助教学系统的设计思想以及MCS－51单片机辅助教学系统的实现方案。     

Objective Tests versus Subjective tests

objective test has only one correct answer, while subjective test has a range of possible answers. Because of this feature, reliability will not be difficult to achieve in the marking of the objective item, while the marking of the subjective items is reliable. On the whole, a good test must contain both subjective and objective test items.