Numerical performance of block thresholded wavelet estimators

Usually, methods for thresholding wavelet estimators are implemented term by term, with empirical coefficients included or excluded depending on whether their absolute values exceed a level that reflects plausible moderate deviations of the noise. We argue that performance may be improved by pooling coefficients into groups and thresholding them together. This procedure exploits the information that coefficients convey about the sizes of their neighbours. In the present paper we show that in the context of moderate to low signal-to-noise ratios, this block thresholding approach does indeed improve performance, by allowing greater adaptivity and reducing mean squared error. Block thresholded estimators are less biased than term-by-term thresholded ones, and so react more rapidly to sudden changes in the frequency of the underlying signal. They also suffer less from spurious aberrations of Gibbs type, produced by excessive bias. On the other hand, they are more susceptible to spurious features produced by noise, and are more sensitive to selection of the truncation parameter.     

码头靠泊船舶控制参数与确定方法探讨

分析国内现行规范关于船型尺度的有关规定及执行中存在的问题和自身的局限性;介绍发达国家标准、规范、导则对设计船型尺度的规定及使用要求;在此基础上,提出码头设计船型主要参数确定的影响因素、原则、方法;对现行国内规范相应规定提出修改建议,特别提出工程设计文件中应给出更准确、清晰、可控的码头靠泊船舶控制参数。     

一个半离散非齐次核的Hilbert不等式

应用权系数的方法及参量化思想,建立一个推广的具有最佳常数因子的、半离散且含一对共轭指数及单参数非齐次核的Hilbert不等式,并考虑了它的等价式与逆式.     

On Minimum Variance Unbiased Estimators

The problem of finding minimum variance unbiased estimators of various parameters for parametric distributions is an important one in statistics. This article gives analytical formulas for the minimum variance unbiased estimators of parametric functions, which are usually used in a classroom, for two types of densities. The first type is the one-parameter regular exponential family, and the second is a two-parameter family of a continuous random variable whose range depends on the unknown parameters.     

Properties and performance of the c-chart for attributes data

The effects of parameter estimation are examined for the well-known c-chart for attributes data. The exact run length distribution is obtained for Phase II applications, when the true average number of non-conformities, c, is unknown, by conditioning on the observed number of non-conformities in a set of reference data (from Phase I). Expressions for various chart performance characteristics, such as the average run length (ARL), the standard deviation of the run length (SDRL) and the median run length (MDRL) are also obtained. Examples show that the actual performance of the chart, both in terms of the false alarm rate (FAR) and the in-control ARL, can be substantially different from what might be expected when c is known, in that an exceedingly large number of false alarms are observed, unless the number of inspection units (the size of the reference dataset) used to estimate c is very large, much larger than is commonly used or recommended in practice. In addition, the actual FAR and the in-control ARL values can be very different from the nominally expected values such as 0.0027 (or ARL₀=370), particularly when c is small, even with large amounts of reference data. A summary and conclusions are offered.     

广义分式规划的离散化处理方法

首先对紧集Ｈ进行离散化处理，然后重新修正Ｈ上广义分式规划问题（Ｐ）的Ｄｉｎｋｅｌｂａｃｈ型算法     

基于MPEG-4的三维人脸动画

具有真实感的三维人脸动画是计算机图形学研究的一个重要分支,有着广泛的应用领域。如何在三维人脸模型上实时地模拟人脸的运动,产生具有真实感的人脸表情和动作,是其中的一个难点。该文在MPEG-4的三维人脸动画原理的基础上提出一种新的基于MPEG-4的、适宜于任意拓扑结构模型的三维人脸动画实现方法。该方法能够在FAP帧的驱动下实现真实感较强的三维人脸动画。     

Some robust parameter designs from orthogonal arrays

Robust parameter design, originally proposed by Taguchi [System of Experimental Design, Vols. I and II, UNIPUB, New York, 1987], is an offline production technique for reducing variation and improving a product's quality by using product arrays. However, the use of the product arrays results in an exorbitant number of runs. To overcome this drawback, several scientists proposed the use of combined arrays, where the control and noise factors are combined in a single array. In this paper, we use non-isomorphic orthogonal arrays as combined arrays, in order to identify a model that contains all the main effects (control and noise), their control-by-noise interactions and their control-by-control interactions with high efficiency. Some cases where the control-by-control-noise are of interest are also considered.     

Statistical inference about the shape parameter of the Weibull distribution by upper record values

Summary In this paper, we provide some pivotal quantities to test and establish confidence interval of the shape parameter on the basis of the firstn observed upper record values. Finally, we give some examples and the Monte Carlo simulation to assess the behaviors (including higher power and more shorter length of confidence interval) of these pivotal quantities for testing null hypotheses and establishing confidence interval concerning the shape parameter under the given significance level and the given confidence coefficient, respectively.     

Mode type quasi-range and its applications

Building from the consideration of closeness, we propose the mode quasi-range as an alternative scale parameter. Application of this scale parameter to formulate the population standard deviation is investigated leading to an efficient sample estimator of standard deviation from the point of asymptotic variance. Monte Carlo studies, in terms of finite sample efficiency and robustness of breakdown point, have been performed for the sample mode quasi-range. This study reveals that this closeness consideration-based mode, quasi-range, is satisfactory because these statistical procedures based on it are efficient and are less misleading for drawing conclusion from the sample results.