基于研发型项目区间算法的进度计划方法研究

制定工序工期不确定的项目进度计划问题是一件十分复杂的计划问题,对于这一类问题一直没有较好的计划方法。对于工序工期藩在一个区间内特殊情况的工序不确定型的项目,并给出了基于区间算法的进度计划方法。     

区间指派问题的研究

在分析传统意义的指派问题存在不足的基础上,文章定义了区间指派问题,证明了区间指派问题存在区间最优指派的充分必要条件,并给出了存在区间最优指派的几种情况;另外,通过定义一般区间指派问题的区间悲观最优指派和区间乐观最优指派,从一个方面解决了没有区间最优指派的区间指派问题.     

三元区间网络中的关键线路法研究

在工程项目进度控制中,关键线路上的工序数难以达到PERT对工序数足够大的要求,而二元区间网络又将工序时间参数处理成均匀分布区间数。为了克服这些缺陷,提出了三元区间网络,有效地克服了对关键线路工序数的要求,并且按照中间大,两端小的原则处理工序时间参数。通过对三元区间网络的理论分析,运用MATLAB编程,实现了此类网络求解的自动化。最后的实例分析表明:三元区间网络求解算法具有很强的可操作性和通用性,所得完工可能度能够很好地反映进度风险。     

基于区间数的后勤装备采购决策方法研究

基于区间数的可能度及相离度理论建立了后勤装备采购的不确定多属性决策模型,以区间数的形式综合考虑决策指标权重及指标值,更多地保留了决策信息,使评价结果更为客观、真实可靠,并结合案例,讨论了运用该决策模型进行决策的方法和详细步骤。     

Evaluation of USDA Interval Forecasts of Corn and Soybean Prices

USDA World Agricultural Supply and Demand Estimates (WASDE) price forecasts are published as an interval, but are typically analyzed as point estimates. Thus, all information about uncertainty imbedded in the forecast is ignored. The purpose of this article is to evaluate the accuracy of WASDE corn and soybean price forecasts using methodology suitable for testing judgmental interval forecasts. Accuracy tests suggest that WASDE forecasts are not calibrated at the 95% confidence level for both commodities and generally not calibrated for corn, but calibrated for soybeans, at the implied confidence level elicited from the survey of forecast providers.     

A Note on the Prediction Intervals for a Future Ordered Observation from a Pareto Distribution

In the researching of products' reliability, the result of life testing is used as the basis for the evaluation and improvement of reliability. During life testing, however, the future observation in an ordered sample is often expected to be predicted so as to show how long a sample of units might run until all fail in life testing. Therefore, we propose five new pivotal quantities to obtain prediction intervals of future order statistics based on right type II censored samples from the Pareto distribution with known shape parameter, then compares the lengths of the prediction intervals when using the pivotal quantity of Ouyang and Wu (1994) based on best linear unbiased estimator (BLUE) of scale parameter, and these five pivotal quantities. An advantage of these five pivotal quantities is that these are easier to calculate than the pivotal quantity of Ouyang and Wu (1994) based on BLUE of scale parameter, since they need to compute the tables of coefficients of BLUE of scale parameter.     

The effectiveness of randomized complete block design

This paper examines the relative efficiency of randomized complete block design as compared with that of completely randomized design. The most widely used measure of relative efficiency considers only the error variances of the two designs, therefore it does not provide the complete information concerning the sensitivity of the experiment in the final results. We study three alternative criteria related to the sensitivity issue and design planning consideration. The proposed relative measures employ the p -value, Scheffé confidence interval estimation and power of both designs. The distinct feature of this study is the focus on the estimated relative efficiency measures and their relation with the coefficient of partial determination between responses and block effects, given that treatment effects are present in the models. Furthermore, informative visual representations and numerical assessments of various aspects of their properties are also presented.     

75吨吊钩超声波探伤及安全评价

提出对75吨吊钩的探伤工艺,用断裂力学评价了探伤结果,指出了合理的检修周期。     

The Meanings of ‘Yes’ and ‘No’. An Explanation for the Forbid/Allow Asymmetry

Survey questions worded with the verb ‘forbid’ prove not to elicit opposite answers to equivalent questions worded with the verb ‘allow’ (Rugg 1941). Although ‘forbid’ and ‘allow’ are generally considered each other’s counterparts, respondents rather answer ‘no, not forbid’ than ‘yes, allow’. In order to find out which question is a more valid measure of the underlying attitude, this asymmetry in the answers has to be explained. Experiments show that the asymmetry arises because respondents translate similar attitudes differently into the answering options to forbid/allow questions are equally valid, but the way the attitudes are expressed on the answering scale differs due to the use of ‘forbid’ or ‘allow’. How does this translation process work? The leading hypothesis in forbid/allow research predicts that respondents holding moderate opinions feel that ‘yes forbid’ and ‘yes allow’ are very extreme, causing moderate respondents to prefer answering ‘not forbid’, or ‘not allow’. This article presents the results of 10 experiments investigating the meanings of the answering options to forbid/allow questions. Extreme connotations are shown to only provide part of the explanation for the occurrence of the forbid/allow asymmetry. In order to describe the answering process for forbid/allow questions, well-definedness of meanings proves to be an important additional factor. The meanings of answering options to allow questions are ill-defined compared of those to forbid questions, which causes allow questions to be less homogeneous measures of the underlying attitude than forbid questions.     

Asymptotic second-order efficiency of three-stage procedure with a warranted confidence level

This paper considers a three-stage procedure which was proposed by Holm (1995) to yield a fixed-width confidence interval of the normal mean with a precise confidence level. The procedure is shown to be asymptotically second-order efficient. The procedure is also applied to such problems as bounded risk and hypothesis testing