Recent advances in multiple-objective design strategies

Many experiments have several goals and it is important to incorporate these goals at the onset of the study. Design strategies for accomplishing this task are reviewed with examples from the biological sciences.     

涤纶棉制取树脂及在锤纹漆中的应用研究

涤纶工业中的废弃涤纶棉因其分子量大不易降解、处理困难而引起环境污染。根据废弃涤纶棉的成分特点可将其制成树脂并应用于锤纹漆中,应用性能指标较好。文章介绍了此类树脂的配方和合成工艺。该项工艺既可降低生产成本创造经济效益,又可减少环境污染产生环境效益。     

浅析现代商业展示设计中如何推广企业品牌形象

在现代商业展示设计中,设计师往往关注商业空间的规划、商业环境的装饰和商品的展示陈列,而忽略企业品牌形 象在商业空间的大力推广。本文剖析了现代商业展示设计和企业品牌形象二者之间的关系,从艺术设计的角度阐述了如何在现 代商业展示设计中树立企业品牌形象。     

Optimal designs for Cox regression

Optimal designs under a survival analysis framework have been rarely considered in the literature. In this paper, an optimal design theory is developed for the typical Cox regression problem. Failure time is modeled according to a probability distribution depending on some explanatory variables through a linear model. At the end of the study, some units will not have failed and thus their time records will be censored. In order to deal with this problem from an experimental design point of view it will be necessary to assume a probability distribution for the time an experimental unit enters the study. Then an optimal conditional design will be computed at the beginning of the study for any possible given time. Thus, every time a new unit enters the study, there is an experimental design to be determined. A particular and simple case is used throughout the paper in order to illustrate the procedure.     

Return and volatility transmission between world oil prices and stock markets of the GCC countries

This paper investigates the return links and volatility transmission between oil and stock markets in the Gulf Cooperation Council (GCC) countries over the period 2005-2010. We employ a recent generalized VAR-GARCH approach which allows for transmissions in return and volatility. In addition, we analyze the optimal weights and hedge ratios for oil-stock portfolio holdings. On the whole, our results point to the existence of substantial return and volatility spillovers between world oil prices and GCC stock markets, and appear to be crucial for international portfolio management in the presence of oil price risk.     

Optimal extended complete block designs for dependent observations

Optimal designs under general dependence structures are usually difficult to specify theoretically or find algorithmically. However, they can sometimes be found for a specific dependence structure and a particular parameter value. In this paper, a class of generalized binary block designs with t treatments and b blocks of size k>t is considered. Each block consists of h consecutive complete blocks and, at the end, an incomplete block of size k−ht (if k > ht). For a suitable number of blocks, a universally optimal design is found for a first-order stationary autoregressive process with positive correlations. Optimal generalized binary designs and balanced block designs are also considered. Some constructions for a universally optimal design are described. A negative dependence parameter, and some other dependence structures, are also considered.     

On optimal allocations for estimating the surface of a random field

In general, the construction of optimal designs is apparently a difficult task for the approximation of a random field indexed by more than one dimension. Besides the rate of convergence of the minimum achievable error hardly anything is known until now. However, if there is an immanent structure present in the random field, then, taking this structure into account, improved estimates can be obtained. For this situation we present adequate designs which show, at least, a nearly optimal performance. work supported by 313/ARC/VII/93/151 of the DAAD work supported by Ku719/2-1 of the DFG     

Optimal design for interacting blocks with OAVS incidence

Optimal design is studied for multiway cross classifications in which the blocking factors exhibit interaction and in which the incidence structure of the blocking factors describes an orthogonal array. Assuming the orthogonal array to be of sufficient strength (enough to allow orthogonal estimation of all of the interaction terms), easily used forms of the information matrix for treatment estimation are derived, and optimality conditions are stated. Some illustrative construction examples are given.     

Optimal designs for models with block-block resp. treatment-treatment correlations

Summary In this paper we study optimal designs assuming two special covariance structures of the observations, namely that the covariance between the observations depends only on the blocks resp. the treatments. We show that the weighted least squares estimator equals the ordinary least squares estimator. Then we prove that block-block correlations resp. treatment-treatment correlations do not have any influence on the A- and MV-optimality resp. A-optimality. For the study of the MV-optimality in the case of treatment-treatment correlations we use the idea of invariance to find optimal C-matrices.     

On the role of weights rounding in applications of resampling based on pseudopopulations

Resampling methods are widely studied and increasingly employed in applied research and practice. When dealing with complex sampling designs, common resampling techniques require adjusting noninteger sampling weights in order to construct the so called “pseudopopulation” in order to perform the actual resampling. The practice of rounding, however, has been empirically shown to be harmful under general designs. In this paper, we present asymptotic results concerning, in particular, the practice of rounding resampling weights to the nearest integer, an approach that is commonly adopted by virtue of its reduced computational burden, as opposed to randomization‐based alternatives. We prove that such approach leads to nonconsistent estimation of the distribution function of the survey variable; we provide empirical evidence of the practical consequences of the nonconsistency when the point estimation of the variance of complex estimators is of interest.