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1.
本文给出了一个上复习课的新方法,利用变上限定积分函数的性质,系统地复习一元函数的有关知识,可使很多问题得到很容易地解决和统一。 相似文献
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Recently, we developed a GIS-Integrated Integral Risk Index (IRI) to assess human health risks in areas with presence of environmental pollutants. Contaminants were previously ranked by applying a self-organizing map (SOM) to their characteristics of persistence, bioaccumulation, and toxicity in order to obtain the Hazard Index (HI). In the present study, the original IRI was substantially improved by allowing the entrance of probabilistic data. A neuroprobabilistic HI was developed by combining SOM and Monte Carlo analysis. In general terms, the deterministic and probabilistic HIs followed a similar pattern: polychlorinated biphenyls (PCBs) and light polycyclic aromatic hydrocarbons (PAHs) were the pollutants showing the highest and lowest values of HI, respectively. However, the bioaccumulation value of heavy metals notably increased after considering a probability density function to explain the bioaccumulation factor. To check its applicability, a case study was investigated. The probabilistic integral risk was calculated in the chemical/petrochemical industrial area of Tarragona (Catalonia, Spain), where an environmental program has been carried out since 2002. The risk change between 2002 and 2005 was evaluated on the basis of probabilistic data of the levels of various pollutants in soils. The results indicated that the risk of the chemicals under study did not follow a homogeneous tendency. However, the current levels of pollution do not mean a relevant source of health risks for the local population. Moreover, the neuroprobabilistic HI seems to be an adequate tool to be taken into account in risk assessment processes. 相似文献
4.
N. Balakrishnan 《Statistical Papers》1989,30(1):141-146
We derive a simple relation satisfied by the covariances of order statistics in the i.i.d. case and then generalize it to
the case when the variables are independent and non-identically distributed. This relation could be employed successfully
either to check the calculations or to reduce the amount of direct computations involved in evaluating the covariances of
order statistics from an outlier model. 相似文献
5.
Consider the process with, cf. (1.2) on page 265 in B1, X1, …, XN a sample from a distribution F and, for i = 1, …, N, R , the rank of |X1 - q1ø| among |X1 - q1ø|, …, |XN - qNø|. It is shown that, under certain regularity conditions on F and on the constants pi and qi, TøN(t) is asymptotically approximately a linear function of ø uniformly in t and in ø for |ø| ≤ C. The special case where the pi and the qi, are independent of i is considered. 相似文献
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为使国际贸易统计和贸易平衡的研究更为深入和更好地开展,本文建议在研究中要处理好以下三个基本关系:经济发展与统计体系建设的关系,中国贸易统计的国际接轨与促进国际统计制度变革的关系,贸易统计数据生产与贸易统计数据使用的关系。 相似文献
8.
The Kulback-Leibler information has been considered for establishing goodness-of-fit test statistics, which have been shown to perform very well (Arizono & Ohta, 1989; Ebrahimi et al., 1992, etc). In this paper, we propose censored Kullback-Leibler information to generalize the discussion of the Kullback-Leibler information to the censored case. Then we establish a goodness-of-fit test statistic based on the censored Kullback-Leibler information with the type 2 censored data, and compare the test statistics with some existing test statistics for the exponential and normal distributions. 相似文献
9.
Jung SH 《Lifetime data analysis》1999,5(1):67-79
In a clinical trial with the time to an event as the outcome of interest, we may randomize a number of matched subjects, such as litters, to different treatments. The number of treatments equals the number of subjects per litter, two in the case of twins. In this case, the survival times of matched subjects could be dependent. Although the standard rank tests, such as the logrank and Wilcoxon tests, for independent samples may be used to test the equality of marginal survival distributions, their standard error should be modified to accommodate the possible dependence of survival times between matched subjects. In this paper we propose a method of calculating the standard error of the rank tests for paired two-sample survival data. The method is naturally extended to that for K-sample tests under dependence. 相似文献
10.
P. J. Avery & D. A. Henderson 《Journal of the Royal Statistical Society. Series C, Applied statistics》1999,48(4):489-503
Non-coding deoxyribonucleic acid (DNA) can typically be modelled by a sequence of Bernoulli random variables by coding one base, e.g. T, as 1 and other bases as 0. If a segment of a sequence is functionally important, the probability of a 1 will be different in this changed segment from that in the surrounding DNA. It is important to be able to see whether such a segment occurs in a particular DNA sequence and to pin-point it so that a molecular biologist can investigate its possible function. Here we discuss methods for testing the occurrence of such a changed segment and how to estimate the end points of it. Maximum-likelihood-based methods are not very tractable and so a nonparametric method based on the approach of Pettitt has been developed. The problem and its solution are illustrated by a specific DNA example. 相似文献