Characterization of singular balanced fractional sm factorial designs derivable from balanced arrays with maximum number of constraints

An upper bound on the maximum number of constraints for s-symbol balanced arrays is derived. It is shown that balanced fractional s^m factorial designs derived from some balanced arrays with the maximum possible number of constraints become singular.     

HRD in 2020: a hop-on,hop-off city tour

This article reports on the outcome of a Future Search Conference in the UK to consider human resource development (HRD) in 2020 and beyond. We firstly consider themes from the past into the present. This includes the persistence of solutions in HRD that are systematic, predictable, how apprenticeships in the UK have had to accommodate government policies to ameliorate youth unemployment and the long-standing difficulty for HRD of failing to demonstrate a return on investment (ROI) on activities. We then present four scenarios based on key questions for the future relating to value of HRD and whether this will be a future for HRD. Reponses to the questions form scenario logics which we present against the theme of city tour. Each scenario is explained against the presented logic with positive, negative, ambiguous and uncertain implications for HRD. We suggest that each scenario carries a glimpse of what might be.     

On the existence of linear trend free block designs

We present a class of counerexamples for a conjecture on the existence or linear trend free block designs we will also prove a considerably weakened version of this conjecture which will determine all combinations of designs parmetres for which the class of linear trend free block designs is non empty.     

Construction of incomplete Sudoku square and partially balanced incomplete block designs

Abstract

The present article deals with the study of association among the elements of a Sudoku square. In this direction, we have defined an association scheme and constructed incomplete Sudoku square designs which are capable of studying four explanatory variables and also happen to be the designs for two-way elimination of heterogeneity. Some series of Partially Balanced Incomplete Block (PBIB) designs have also been obtained.     

Randomization tests in recursive response-adaptive randomization procedures

In a randomized clinical trial, response-adaptive randomization procedures use the information gathered, including the previous patients' responses, to allocate the next patient. In this setting, we consider randomization-based inference. We provide an algorithm to obtain exact p-values for statistical tests that compare two treatments with dichotomous responses. This algorithm can be applied to a family of response adaptive randomization procedures which share the following property: the distribution of the allocation rule depends only on the imbalance between treatments and on the imbalance between successes for treatments 1 and 2 in the previous step. This family includes some outstanding response adaptive randomization procedures. We study a randomization test to contrast the null hypothesis of equivalence of treatments and we show that this test has a similar performance to that of its parametric counterpart. Besides, we study the effect of a covariate in the inferential process. First, we obtain a parametric test, constructed assuming a logit model which relates responses to treatments and covariate levels, and we give conditions that guarantee its asymptotic normality. Finally, we show that the randomization test, which is free of model specification, performs as well as the parametric test that takes the covariate into account.     

Factor screening in nonregular two-level designs based on projection-based variable selection

In this paper, we focus on the problem of factor screening in nonregular two-level designs through gradually reducing the number of possible sets of active factors. We are particularly concerned with situations when three or four factors are active. Our proposed method works through examining fits of projection models, where variable selection techniques are used to reduce the number of terms. To examine the reliability of the methods in combination with such techniques, a panel of models consisting of three or four active factors with data generated from the 12-run and the 20-run Plackett–Burman (PB) design is used. The dependence of the procedure on the amount of noise, the number of active factors and the number of experimental factors is also investigated. For designs with few runs such as the 12-run PB design, variable selection should be done with care and default procedures in computer software may not be reliable to which we suggest improvements. A real example is included to show how we propose factor screening can be done in practice.     

知识搜索引擎与翻译

信息化进程的纵深发展对翻译行业产生了深刻的影响,译者如何从海量信息中高效获取信息关系到其翻译服务的质量。因此,译者的信息素养和搜索能力显得愈发重要。通过探讨搜索引擎的补充和延伸——知识搜索引擎,着重论述知识搜索引擎相对于传统搜索引擎,在主题分类、一站式知识检索、互动式知识问答、个性化知识库等方面具备的突出优势,并对比国内三大知识搜索引擎,论述其在翻译实践中的重要启示。     

一种求解双目标flow shop排序问题的进化算法

提出一种求解双目标flow shop排序的递进多目标进化算法.算法采用改进的精英复制策略,在实现精英保留的前提下降低了计算复杂性;通过递进进化模式增加群体多样性,改善了算法收敛性;通过群体进化过程中对非劣解集进行竞争型可变邻域启发式搜索,增强了算法局部搜索性能.采用新算法和参照算法NSGA-II对31个标准双目标flow shop算例进行优化.研究结果表明,新算法在所有算例的求解中均获得了优于NSGA-II的非劣解集,验证了算法的有效性.     

工作搜索行为研究的回顾和展望

工作搜索行为是个体付出努力和时间,获取潜在的工作信息的有目的的意志性行为模式.关于工作搜索行为的结构有成分说、阶段说和维度说.影响工作搜索行为的因素主要有个体的自尊、自我效能感、工作搜索动机以及人格特质等,而个体的工作搜索行为又会影响到个体的就业情况和就业质量.未来的研究可以从以下方面做出努力:对不同的亚群体分别进行具体研究;使多种研究方法相互交叉来补充以往研究的不足;进一步拓展研究领域、发展工作搜索行为的理论以及建构完整的模型;在应用领域中进一步研究工作搜索行为的干预与培训措施的有效性.     

Lower bound of average centered L2-discrepancy for U-type designs

Uniform designs are widely used in various scientific investigations and industrial applications. By considering all possible level permutation of the factors, a connection between average centered L₂-discrepancy and generalized wordlength pattern for asymmetrical fractional factorial designs is derived. Moreover, we present new lower bounds to the average centered L₂-discrepancy for symmetrical and asymmetrical U-type designs. For illustration of the theoretical results, the lower bounds for symmetrical and asymmetrical U-type designs are tabulated, and numerical results indicate that our lower bounds behave well and can be recommended for use in practice.