Estimating probabilities from invariant permutation distributions

Summary We introduce variance reduction techniques as general tools for estimating probabilities from invariant permutation distributions. The paper discusses importance sampling, antithetic sampling and control variates sampling as alternatives to uniform Monte Carlo sampling for estimating exact critical values orP-values in a broad class of permutation tests. Results may be extended to permutation confidence intervals and linear rank tests. An asymptotic theory is provided for each proposed variance reduction method. Invited paper at the Conference held in Bologna, Italy, 27–28 May 1993, on ?Statistical Tests: Methodology and Econometric Applications?.     

机器人动力学自动建模软件系统

提出了一种用数字一符号法建立机器人动力学模型的简便、高效方法，该方法将模型矩阵中各元素的推导问题转化为特定条件下应用动力学递推公式求解驱动力和驱动力矩的问题。文中引入了一种线性链表的动态数据结构，将建模过程中复杂的数字、符号混合处理过程转化为简单的矩阵运算过程，降低了建模的复杂性。研制了自动建立机器人动力学模型的计算机软件，可自动生成动力学模型的各矩阵元素，并以实时代码形式输出。     

Multi-item inventory model with quantity-dependent inventory costs and demand-dependent unit cost under imprecise objective and restrictions: A geometric programming approach

A multi-item inventory model with constant demand and infinite replenishment is developed under the restrictions on storage area, total average shortage cost and total average inventory investment cost. These restrictions may be precise or imprecise. Here, it is assumed that inventory costs are directly proportional to the respective quantities, and unit purchase/production cost is inversely related to the demand. Restricted shortages are allowed but fully backlogged. First, the problem is formulated in crisp environment taking the deterministic and precise inventory parameters. It is solved by both geometric programming (GP) and gradient-based non-linear programming (NLP) methods. Later, the problem is formulated with fuzzy goals on constraints and objectives where impreciseness is introduced through linear membership functions. It is solved using the fuzzy geometric programming (FGP) method. The inventory models are illustrated with numerical values and compared with the crisp results. A sensitivity analysis on the optimum order quantity and average cost is also presented due to the variation in the tolerance of total average inventory investment cost and total average shortage cost following Dutta et al., 1993, Fuzzy Sets and Systems, 55, 133-142.     

Critical review and comparison of continuity correction methods: The normal approximation to the binomial distribution

We provide a comprehensive and critical review of Yates’ continuity correction for the normal approximation to the binomial distribution, in particular emphasizing its poor ability to approximate extreme tail probabilities. As an alternative method, we also review Cressie's finely tuned continuity correction. In addition, we demonstrate how Yates’ continuity correction is used to improve the coverage probability of binomial confidence limits, and propose new confidence limits by applying Cressie's continuity correction. These continuity correction methods are numerically compared and illustrated by data examples arising from industry and medicine.     

宗教信仰与心理治疗:社会认知的角度

宗教信仰在心理疾病患者生活中扮演重要角色.信仰宗教的人往往表现出直觉思维的模式特点.这种思维的结果是假说偏差和组内/组外偏差.宗教对心理治疗积极的作用表现在宗教可以提供积极的应对策略;宗教还提供了替代依恋对象;宗教倡导宽恕,有助于调节情绪和行为.宗教信仰产生的认知偏差和偏见会影响心理治疗过程,而且宗教也会成为导致心理疾病的原因之一,宗教的负面影响还体现在宗教都是外部控制的,这与心理治疗倡导的自由探究和自我发展的原则相矛盾.心理咨询师和心理疾病患者在宗教上的差异主要体现在对待宗教的态度和应对方式上,是导致二者潜在冲突的根本原因.心理健康从业者需要对宗教信仰及其与心理治疗的关系重新再认识.     

《水污染控制原理》理论－实验—实践教学模式探讨

对贵州民族学院环境科学专业《水污染控制原理》课程教学现存的问题进行深入分析，并针对该课程的教学内容、教学手段以及实践等环节进行了初步探讨，从而提出了全新的教学模式。     

Relationship between job control,work pressure and strain: Studies in the USA and in The Netherlands

The purpose of this study was to test a model of job control, work pressure and strain in two samples in the USA and in The Netherlands. According to the proposed model, work pressure has a mediating role between job control and worker strain. The present model specifies three types of job control: task or instrumental control, conceptual or resource control, and decision organization control. Task and resource control are assumed to reduce the stressor of work pressure which, in turn, is related to high strain. Organization control is assumed to be positively related to work pressure. The model was tested in two samples : one US sample of 273office employees and one Dutch sample of 958 employees in a variety of jobs. The same measure of job control was used in both samples. Resultspartially confirm the proposed model. As predicted by the proposed model, high task control was related to low work pressure, whereas high organization control was related to high work pressure. The effects of task control and organization control on strain were mediated by work pressure for the measure of anxiety in the US sample and for the measure of stress in the Dutch sample. However, the mediating effect of work pressure was not found for job satisfaction in both samples, for the measure of mood disturbances in the US sample and for the measure of sick days in the Dutch sample. The proposed model is only partially confirmed by the results. These results confirm the importance of differentiating between different dimensions of job control.     

An expert system for a semiconductor manufacturing environment

We developed an expert system to analyse and suggest solutions to problems commonly encountered in the production of integrated circuits. We wrote a PC-based program to implement the expert system. Our goal is to enable interested readers to relate some of the accomplishments realized by a high tech manufacturing company to their own production, manufacturing or maintenance environment. We discuss the difficulties encountered when implementing an expert system as well as the great benefits derived from its use.     

The VL control measure for symmetric networks

In this paper we measure “control” of nodes in a network by solving an associated optimisation problem. We motivate this so-called VL control measure by giving an interpretation in terms of allocating resources optimally to the nodes in order to maximise some search probability. We determine the VL control measure for various classes of networks. Furthermore, we provide two game theoretic interpretations of this measure. First it turns out that the VL control measure is a particular proper Shapley value of the associated cooperative network game. Secondly, we relate the measure to optimal strategies in an associated matrix search game.