Robustness of a Class of Partial Diallel Cross Designs to the Unavailability of a Complete Block of Observations

Complete and partial diallel cross designs are examined as to their construction and robustness against the loss of a block of observations. A simple generalized inverse is found for the information matrix of the line effects, which allows evaluation of expressions for the variances of the line-effect differences with and without the missing block. A-efficiencies, based on average variances of the elementary contrasts of the line-effects, suggest that these designs are fairly robust. The loss of efficiency is generally less than 10%, but it is shown that specific comparisons might suffer a loss of efficiency of as much as 40%.     

Children's gender- and age-based categorization in similarity and induction tasks

The present studies examined children's and adults' preferences for gender- or age-based categorization using similarity and inductive inference tasks. Four-year-olds, 6-year-olds, and adults looked at pictures of people and decided which of two was more like a target (similarity condition) or which shared a novel age- or gender-related property with the target (inference condition). Age or gender-based matches were possible. The results are consistent with previous findings that gender-based classification decreases with age. However, they also demonstrate that children use gender more for judging similarity than for making inferences about novel properties. Distinct patterns emerge from the two tasks: 6-year-olds and adults in both conditions categorize more by age than gender; 4-year-olds categorize by gender more than age in the similarity task, but by age more in the induction task. Only adults differentiated by property in the inference condition. These findings suggest that the salience of gender categories cannot entirely be attributed to their inductive potential. Gender has a salience beyond what would be predicted by its power for directing novel generalizations.     

中国城市化的重要发展趋势:城市群(圈)的出现及对投资的需求

由于经济全球化的影响和科学技术的进步,以及中国经济的高速发展、经济体制日趋市场化和对外开放的不断扩大,中国的城市化出现了一些新的发展趋势,那就是城市群(圈)的涌现。城市群(圈)的发育和发展,要求有完善的交通、通讯及其他基础设施的支撑,需要大量的投资。     

Solving the part families problem in discrete-parts manufacture by simulated annealing

In the production planning and control of discrete-parts manufacture, aggregation of parts into families, on the basis of similarity, is carried out to ease both long-horizon planning and short-horizon scheduling. Additional advantages are related to those of group technology (GT), such as simplifying the flow of parts and tools and reducing both set-up and production costs. The problem of formally forming part families is presented and discussed. Previous work is reviewed and assessed. Two solution approaches, one based on a location model, the other on simulated annealing, are presented and compared along with test results. The location formulation, which results in an integer programming model solved by Lagrangian relaxation, proved capable of producing solutions of excellent quality, but only for relatively small problem instances. In contrast, simulated annealing, which is a general heuristic approach to combinatorial optimization, produced solutions of comparable quality and could handle realistically large problem instances. However, careful design of the simulated annealing algorithm is crucially important. An effective design is presented.     

异形词群系统的意义结构研究

根据词语的义位理论,揭示异形词群系统的内外部意义结构规律,指出异形词系统各组内部"同素同构"与非"同素同构"共存的现象,其他各层级系统间以及异形词群系统与非异形词群系统之间几乎都有一个共同的语素,以利异形词的规范、教学和应用。     

傈僳族新创文字研究综述

新傈僳文自1957年创制试行,已历经半个世纪。有关傈僳文的研究积累了翔实的调查资料,并在此基础上取得了可观的研究成果,但尚存在一些不足之处:第一,视野狭窄,方法单一。当前的研究应从多学科的角度,运用多种、多重研究方法,力求在研究中有所创新和突破。第二,描述性研究较多,解释性研究较少。今后的新傈僳文研究应多关注傈僳族文化传承与发展、语言文字多样性保护、文化价值及现实意义等问题。第三,回顾性研究多,前瞻性研究少。学界应对新傈僳文的使用现状进行深层次的前瞻性研究,提出适合现代社会发展规律的、具有应用意义和可操作性的应对策略。     

从制度和文化层面看现代企业集团的经济性

现代企业集团是世界经济发展过程中的一个普遍现象,它对于推动社会生产力的发展具有重要意义。本文首先从企业集团的特征入手,分析了现代企业集团的实质;其次,从制度和文化两个层面,分析了现代企业集团的组织经济性和名牌经济性     

Ranked set sampling with concomitant variables

Ranked set sampling is a procedure which may be used to improve the precision of the estimator of the mean. It is useful in cases where the variable of interest is much more difficult to measure than to order. However, even if ordering is difficult, but there is an easily ranked concomitant variable available, then it may be used to “judgment order” the original variable. The amount of increase in the precision of the estimator is dependent upon the correlation between the 2 variables.     

Maximal Invariant and Weakly Equivariant Estimators

Equivariant functions can be useful for constructing of maximal invariant statistic. In this article, we discuss construction of maximal invariants based on a given weakly equivariant function under some additional conditions. The theory easily extends to the case of two or more weakly equivariant functions. Also, we derive a maximal invariant statistic when the group contains a sharply transitive and a characteristic subgroup. Finally, we consider the independence of invariant and weakly equivariant functions under some special conditions.     

Three-stage designs for monitoring clinical trials

Optimal three-stage designs with equal sample sizes at each stage are presented and compared to fixed sample designs, fully sequential designs, designs restricted to use the fixed sample critical value at the final stage, and to modifications of other group sequential designs previously proposed in the literature. Typically, the greatest savings realized with interim analyses are obtained by the first interim look. More than 50% of the savings possible with a fully sequential design can be realized with a simple two-stage design. Three-stage designs can realize as much as 75% of the possible savings. Without much loss in efficiency, the designs can be modified so that the critical value at the final stage equals the usual fixed sample value while maintaining the overall level of significance, alleviating some potential confusion should a final stage be necessary. Some common group sequential designs, modified to allow early acceptance of the null hypothesis, are shown to be nearly optimal in some settings while performing poorly in others. An example is given to illustrate the use of several three-stage plans in the design of clinical trials.