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.     

A new approach in constructing orthogonal and nearly orthogonal arrays

Orthogonal arrays have been constructed by a number of mathematical tools such as orthogonal Latin squares, Hadamard matrices, group theory and finite fields. Wang and Wu (1992) proposed the concept of a nearly orthogonal array and found a number of such arrays with high efficiency. In this paper we propose some criteria for non-orthogonality and two algorithms for the construction of orthogonal and nearly orthogonal arrays evincing higher efficiency than that obtained by Wang and Wu. Received: September 1999     

TiO_2纳米管的制备及其降解壬基酚性能的研究

采用阳极氧化法制备TiO2纳米管电极,用SEM等方法对光电极的表面形貌进行了表征。以罗丹明B为目标污染物确定最佳退火温度,制备的电极进行壬基酚降解实验,实验通过添加自然界中分布较广的SO42-、Cl-阴离子来观察对壬基酚降解效果的影响。结果表明在退火温度为550℃时罗丹明B的降解效果最好为67.31%。用TiO2纳米管电极降解壬基酚时,不添加阴离子条件下的对壬基酚的降解效率达到91.66%要高于添加Cl(-65.99%)、SO42-(65.73%)等离子时的降解效果     

采用改进和声搜索算法的稀布线阵综合方法

针对稀布天线阵列中带有阵元数目、阵列孔径、阵元间距上下限和峰值旁瓣电平抑制的多重约束问题，提出了一种基于改进和声搜索算法的综合方法。通过和声变量与阵元间距的矢量映射，原始的强约束优化问题可以转换为仅含双边约束的优化问题，从而在保持可行解空间不变的同时提高了问题的自由度。为了加速收敛过程，采用动态调整参数策略。仿真结果表明，与现有文献中的算例进行比较，所提出的方法能够得到更低的峰值旁瓣电平，且鲁棒性好，收敛速度快。     

用遗传算法优化任意稀布率的平面阵列

通过给经典遗传算法(GA)的变异算子赋予新的功能,实现了任意稀布率的平面阵或线阵方向图的优化.研究了遗传算法参数和优化结果之间的关系,仿真结果表明,同时考虑峰值副瓣电平和波束宽度才能获得更满意的稀布结果.归纳得出一个平面稀布阵峰值副瓣电平的估计公式,并和随机稀布阵的公式进行了比较,数值结果表明该公式有一定的工程意义.     

均匀平面阵下的二维DOA估计与互耦自校正

针对存在互耦效应时均匀平面阵的测向鲁棒性问题,提出了一种基于秩损准则的互耦自校正算法。根据对互耦效应的先验知识,提出的算法只需将受互耦扰动的阵列响应在变换域中重新排列,便可在后续处理中屏蔽掉互耦效应的不利影响,同时也避免了现有工作中存在的阵列孔径损失问题。借助秩损估计原理,在变换域中设计了一种巧妙的计算步骤,使得方位估计的降维操作得以实现;并且,后续还可通过特征分解法得到更精确的互耦系数估计,以进行阵列误差自校正。与现有的研究工作相比,所提算法无论是在估计精度,还是在计算效率上均有着显著的性能优势。     

Projection Properties of Hadamard Matrices of Order 36 Obtained from Paley’s Constructions

In this paper we study the projection properties of 12 inequivalent Hadamard matrices of order 36 obtained from Paley’s constructions, using several statistical criteria. We also present generalized minimum aberration designs with 36 runs and up to 7 columns that are embedded into these Hadamard matrices.     

Projection properties of certain three level orthogonal arrays

Two orthogonal arrays based on 3 symbols are said to be isomorphic or combinatorially equivalent if one can be obtained from the other by a sequence of row permutations, column permutations and permutations of symbols in each column. Orthogonal arrays are used as screening designs to identify active main effects, after which the properties of the subdesign for estimating these effects and possibly their interactions become important. Such a subdesign is known as a ``projection design'. In this paper we have identified all the inequivalent projection designs of an OA(27,13,3,2), an OA(18,7,3,2) and an OA(36,13,3,2) into k=3,4 and 5 factors. It is shown that the generalized wordlength pattern criterion proposed by Ma and Fang [23] can distinguish between most, but not all, inequivalent classes. We propose an extension of the Es² criterion (which is commonly used for measuring efficiency of 2-level designs) to distinguish further between the non-isomorphic classes and to measure the efficiency of the designs in these classes. Some concepts on generalized resolution are also discussed.