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861.
Despite their diverse applications in many domains, the variable precision rough sets (VPRS) model lacks a feasible method to determine a precision parameter (β) value to control the choice of β-reducts. In this study we propose an effective method to find the β-reducts. First, we calculate a precision parameter value to find the subsets of information system that are based on the least upper bound of the data misclassification error. Next, we measure the quality of classification and remove redundant attributes from each subset. We use a simple example to explain this method and even a real-world example is analyzed. Comparing the implementation results from the proposed method with the neural network approach, our proposed method demonstrates a better performance. 相似文献
862.
毛韶华 《西昌学院学报(社会科学版)》2004,16(1):64-68,74
接地是为了保护人身的安全,设备的正常运行与不遭破坏。在电力系统中、各种设 备上和预防雷电事故的技术里,都被广泛的使用。在今天,城镇化建设不断推进,人口集中程度更 大,建筑楼层普遍提高,各种强功能高价值的设备在办公室、家庭等场所广泛使用的大发展时期,合 理选用接地方式、接地体、布线工艺和确定接地参数对建筑物来说,是至关重要的。本文就是结合实 际,对建筑物中接地方式、接地体、布线工艺及接地参数的选择进行改进优化分析。 相似文献
863.
Estimation of high quantiles of a distribution in the domain of attraction of the Fréchet distribution is based on the extremal distribution of the k largest order statistics. The problem is treated by a local maximum likelihood method on a three parameter model. The estimators are shown to be asymptotically consistent for the whole range of the tail index parameter. 相似文献
864.
在反应体质心系中,依据热化模型并考虑碰撞参量的涨落及核阻止性,对工作在BNL/AGS上E-802合作组给出的中心和周边Si与Au、Cu和AI相互作用的强子快度分布进行了分析和讨论. 相似文献
865.
Yannis G. Yatracos 《Revue canadienne de statistique》1992,20(2):187-200
Practical questions motivate the search for predictors either of an as yet unobserved random vector, or of a random function of a parameter. An extension of the classical UMVUE theory is presented to cover such situations. In includes a Rao-Blackwell-type theorem, a Cramer-Rao-type inequality, and necessary and sufficient conditions for a predictor to minimize the mean squared error uniformly in the parameter. Applications are considered to the problem of selected means, the species problem, and the examination of some u-v estimates of Robbins (1988). 相似文献
866.
J. S. Marron 《Econometric Reviews》1987,6(2):271-283
Partitioned cross-validation is proposed as a method for overcoming the large amounts of across sample variability to which ordinary cross-validation is subject. The price for cutting down on the sample noise is that a type of bias is intriduced. A theory is presented for optimal trade-off of this variance and bias. Comparison with other bandwidth selection methods is given. 相似文献
867.
Summary In this note we deal with some admissibility conditions proved by G. B. Tranquilli to be sufficient in the class of unbiased
estimators of finite population parameters and with respect to (w.r.t.) a quadratic loss function. We show that the same conditions:i) are sufficient for the admissibility of an unbiased estimator with any loss function;ii) imply hyperadmissibility with reference to a particular (critical) population of the. From this fact we deduce that, for
a fixed critical population, there is at most one estimator, in the class of all unbiased estimator of a finite population
parameter, which satisfies Tranquilli condition.
This research was partially supported by a M.U.R.S.T. grant ?Metodi inferenziali basati sul ricampionamento?. 相似文献
868.
The two-parameter gamma model is widely used in reliability, environmental, medical and other areas of statistics. It has a two-dimensional sufficient statistic, and a two-dimensional parameter which can be taken to describe shape and mean. This makes it closely comparable to the normal model, but it differs substantially in that the exact distribution for the minimal sufficient statistic is not available. Some recently developed asymptotic theory is used to derive an approximation for observed levels of significance and confidence intervals for the mean parameter of the model. The approximation is as easy to apply as first-order methods, and substantially more accurate. 相似文献
869.
870.
常辉兰 《上海理工大学学报(社会科学版)》1997,(1)
从电子设备和元件的减振问题出发,利用随机振动理论对双层减振问题作了研究;推导出双自由度系统质点绝对加速度及相对位移均方值的函数表达式,给出了系统结构参数与系统响应间的关系曲线;得出了随机激振下双层减振系统结构参数的确定方法. 相似文献