Classification of Random Image Fields Using Synthetic Discriminant Functions: Spectral Statistical Approach and Its Computer-Optical Realization

The problem of classification of images that have a perfectly random nature is considered. We propose a new approach to solve this problem that is based on the use of the synthetic discriminant functions being synthesized to separate linearly the power spectra of random image fields to be classified. In the stage of both discriminant function synthesis and classification, the statistical technique of power spectrum estimation is employed. The realization of the proposed approach by means of a hybrid computer-optical technique is discussed, and its efficiency is illustrated by two examples of real-world texture classification.     

波动光学MTF计算误差估计和新的计算方法

用数理统计方法,推导出波动光学MTF数值计算的误差估计式,它适用于对不同的数值计算方法进行自相关积分所求得的MTF值进行误差估计.本文根据波动光学的基本性质,提出了新的MTF数值计算方法,它具有较高的数值精度,更可观的计算量大大减少.     

Using integer programming techniques for the solution of an experimental design problem

Latin hypercube sampling is often used to estimate the distribution function of a complicated function of many random variables. In so doing, it is typically necessary to choose a permutation matrix which minimizes the correlation among the cells in the hypercube layout. This problem can be formulated as a generalized, multi-dimensional assignment problem. For the two-dimensional case, we provide a polynomial algorithm. For higher dimensions, we offer effective heuristic and bounding procedures.Supported in part by a grant from the National Institute of Standards and Technology (60NANB9D-0974).Supported in part by grants from the Office of Naval Research (N00014-90-J-1324) and the Air Force Office of Scientific Research (F49 620-90-C-0022).Research partially performed while visiting the Department of Mathematics, Brunel University, Uxbridge, England.     

Higher order estimation at Lebesgue points

The symmetric derivative of a probability measure at a Lebesgue point can often be specified by an exact relation involving a regularity index. Knowledge of this index is of practical interest, for example to specify the local behavior of the measure under study and to evaluate bandwidths or number of neighbors to take into account in smoothing techniques. This index also determines local rates of convergence of estimators of particular points of curves and surfaces, like minima and maxima. In this paper, we consider the estimation of the d-dimensional regularity index. We introduce an estimator and derive the basic asymptotic results. Our estimator is inspired by an estimator proposed in Drees and Kaufmann (1998, Stochastic Processes and their Applications, 75, 149–172) in the context of extreme value statistics. Then, we show how (estimates of) the regularity index can be used to solve practical problems in nearest neighbor density estimation, such as removing bias or selecting the number of neighbors. Results of simulations are presented.     

Exact algorithms and applications for Tree-like Weighted Set Cover

We introduce an NP-complete special case of the Weighted Set Cover problem and show its fixed-parameter tractability with respect to the maximum subset size, a parameter that appears to be small in relevant applications. More precisely, in this practically relevant variant we require that the given collection C of subsets of a base set S should be “tree-like”. That is, the subsets in C can be organized in a tree T such that every subset one-to-one corresponds to a tree node and, for each element s of S, the nodes corresponding to the subsets containing s induce a subtree of T. This is equivalent to the problem of finding a minimum edge cover in an edge-weighted acyclic hypergraph. Our main result is an algorithm running in O(3^kmn) time where k denotes the maximum subset size, n:=|S|, and m:=|C|. The algorithm also implies a fixed-parameter tractability result for the NP-complete Multicut in Trees problem, complementing previous approximation results. Our results find applications in computational biology in phylogenomics and for saving memory in tree decomposition based graph algorithms.     

An approximate lower tolerance bound for the three-parameter Weibull applied to lumber property characterization

We investigate a large sample approach for obtaining tolerance bounds where the underlying population is a three-parameter Weibull distribution. Accurate tolerance bounds could play an important role in the development of lumber standards. Properties of the maximum likelihood based approach are compared with those of the standard nonparametric tolerance procedure. The asymptotic normal approximation to the tolerance bound was found to be inadequate for most of the cases considered.     

Virtual topology design of shared channel lightwave networks

Channel sharing in a WDM-based lightwaue network provides a way to reduce the number of wauelengths required for the implementation of a large network, while the network virtual connectivity can be dramatically increased. In this paper, we first introduce a so-called group policy that achieves a virtual topology with maximum connectivity and simplifies the optimal design of a trafjic sensitiue virtual topology. We propose a two-stage algorithm: a node-to-group assignment and a wauelength-to-group assignment. The results show that the proposed algorithm is a practical tool that efjiciently reconfigures the connectivity diagram to fit best the current traffic pattern.     

电声技术近年进展

本文讨论近年电声技术的进展，综述电声器件概况，介绍高保真立体声中的环境声和数字声频，并总结迅速发展的声场电声控制技术，最后讨论了主观电声测量方面的动态．     

一个除数问题的推广

本文推广了Ｒ．Ａ．Ｓｍｉｔｈ，Ｍ．Ｖ．Ｓｕｂｂａｒａｏ和Ｇ．Ｎｏｗａｋ所考虑的一个除数问题．令Ｓ＝｛（ａｉ，ｑｉ）｜ａｉ≤ｑｉ｝（ｒ≥３）．定义ｄ（ｎ；Ｓ）＝Σ（１）１，Σ（１）表示对满足ｎ＝ｍ１…ｍｒ，ｍｊ≡ａｊ（ｍｏｄｑｊ），ｊ＝１，２，…，ｒ的诸ｍｊ求和．我们求出了Σｎ≤ｘｄ（ｎ；Ｓ）的渐近公式，并得到了余项估计．     

Nonparametric Estimation for Gibbs Random Fields Specified Through One‐Point Systems

The problem of nonparametric estimation for Gibbs random fields is considered. The field is supposed to be specified through a translation invariant quasilocal one‐point system. An estimator of one‐point system is constructed by the method of sieves, and its exponential and L^p consistencies are proved in different setups. The results hold regardless of non‐uniqueness and translation invariance breaking. This revised version was published online in June 2006 with corrections to the Cover Date.