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41.
In this paper we discuss a new theoretical basis for perturbation methods. In developing this new theoretical basis, we define the ideal measures of data utility and disclosure risk. Maximum data utility is achieved when the statistical characteristics of the perturbed data are the same as that of the original data. Disclosure risk is minimized if providing users with microdata access does not result in any additional information. We show that when the perturbed values of the confidential variables are generated as independent realizations from the distribution of the confidential variables conditioned on the non-confidential variables, they satisfy the data utility and disclosure risk requirements. We also discuss the relationship between the theoretical basis and some commonly used methods for generating perturbed values of confidential numerical variables. 相似文献
42.
遗传算法在入侵检测中的应用 总被引:4,自引:0,他引:4
介绍了基于模型推理和基于模型两种入侵检测系统,提出了一种新的基于智能体技术的入侵检测系统体系结构,解决了传统集中式入侵检测系统的弊病,将任务处理和数据分布到网络各个结点上,充分利用网络资源协同完成入侵检测任务;介绍了遗传算法在该系统中的应用,因系统安全的先验知识体现在对原始数据中有价值特征属性变量集的选择上,故利用遗传算法对特征属性变量子集的选择进行优化,找到相对最优的由特征向量表示的特征属性变量集,以降低入侵检测系统的负荷。 相似文献
43.
The development of a Municipal Information System, or currently better known as a local spatial data infrastructure, is considered complex due to the required inter-institutional relationships. In many developing countries Geographical Information Systems (GISs) are introduced but the benefits are modest as no changes take place in technical and organisational structure of organisations. Digital databases and computer-aided design (CAD) maps are mushrooming in great variety within different private and public institutions, municipal organisations and even within single departments and with structures similar to the paper period and thus operating on a stand-alone basis.Many national mapping agencies are not able to provide large-scale digital urban base maps, while the absence or low quality of cadastres makes those basic core data sets unavailable or inaccessible. The result is that duplication and incompatible data are frequently observed and also donor-driven stand-alone projects have a limited impact through the lack of institutional embedding and are not able to mature from the project to the institutional level. However, a positive sign is that there is an increasing awareness among data producers and consumers that investments in the development of digital data sets should be combined to reduce costs and increase benefits from especially GIS, and information and communication technology (ICT) in general.Within Trujillo a long-term vision was developed to make full use of ICT and GIS to modernise all operations of the Municipality to increase the efficiency and effectiveness of its tasks. However, large investments are not feasible due to the very limited municipal budgets. To guarantee the support of the municipal council, short-term results are required. This paper describes three ‘products’ as part of the vision to develop through a step-by-step approach a local spatial data infrastructure for Trujillo.The three, rather different, products are:
- 1. fiscal cadastre, to increase municipal revenues through property taxation;
- 2. an ‘environmental atlas’ based on a compatible spatial and attribute data sets from a variety of organisations; and
- 3. a municipal website with interactive GIS and meta data information.
44.
Paul Zhang 《Journal of applied statistics》2005,32(2):141-155
A controlled clinical trial was conducted to investigate the efficacy effect of a chemical compound in the treatment of Premenstrual Dysphoric Disorder (PMDD). The data from the trial showed a non-monotone pattern of missing data and an ante-dependence covariance structure. A new analytical method for imputing the missing data with the ante-dependence covariance is proposed. The PMDD data are analysed by the non-imputation method and two imputation methods: the proposed method and the MCMC method. 相似文献
45.
Chandan Saha Michael P. Jones 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2005,67(1):167-182
Summary. In longitudinal studies, missingness of data is often an unavoidable problem. Estimators from the linear mixed effects model assume that missing data are missing at random. However, estimators are biased when this assumption is not met. In the paper, theoretical results for the asymptotic bias are established under non-ignorable drop-out, drop-in and other missing data patterns. The asymptotic bias is large when the drop-out subjects have only one or no observation, especially for slope-related parameters of the linear mixed effects model. In the drop-in case, intercept-related parameter estimators show substantial asymptotic bias when subjects enter late in the study. Eight other missing data patterns are considered and these produce asymptotic biases of a variety of magnitudes. 相似文献
46.
西部高校怎样更好实现计算机与物理实验的整合 总被引:2,自引:0,他引:2
王晓璐 《贵州民族学院学报》2005,(3):159-160
随着计算机的飞速发展,学校里出现了越来越多的多媒体教室;CAI计算机辅助教学、虚拟实验教学等各种软件更是蓬勃发展起来;很多教育工作者提出物理实验中计算机仿真教学、物理实验中应用计算机辅助教学等各种措施.作为西部高校,我们应该根据自身资金有限、学生基础比较薄弱等特点,更好的实现计算机与物理实验的整合. 相似文献
47.
Wing-Kam Fung Zhong-Yi Zhu Bo-Cheng Wei Xuming He 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2002,64(3):565-579
Summary. Semiparametric mixed models are useful in biometric and econometric applications, especially for longitudinal data. Maximum penalized likelihood estimators (MPLEs) have been shown to work well by Zhang and co-workers for both linear coefficients and nonparametric functions. This paper considers the role of influence diagnostics in the MPLE by extending the case deletion and subject deletion analysis of linear models to accommodate the inclusion of a nonparametric component. We focus on influence measures for the fixed effects and provide formulae that are analogous to those for simpler models and readily computable with the MPLE algorithm. We also establish an equivalence between the case or subject deletion model and a mean shift outlier model from which we derive tests for outliers. The influence diagnostics proposed are illustrated through a longitudinal hormone study on progesterone and a simulated example. 相似文献
48.
白族档案史料研究 总被引:6,自引:0,他引:6
陈子丹 《中央民族大学学报(哲学社会科学版)》2002,(2)
白族档案史料是以白族为主的各民族在长期的社会发展进程中形成的。其形成过程大体经历了秦至西汉、东汉至唐初、南诏国和大理国、元明清、近现代几个时期 ,主要包括碑刻、经卷、画卷、家谱、族谱、民俗、名人档案等类别 ,各类档案的形式、内容、价值等 ,又各有其不同的特点。 相似文献
49.
数据挖掘与数据仓库在CRM中的应用 总被引:2,自引:0,他引:2
徐丽娟 《绍兴文理学院学报》2002,22(10):46-48
介绍了客户关系管理的思想、功能组成 ,以及数据挖掘和数据仓库技术在客户关系管理中的应用 相似文献
50.
高校院系资料室的建设及其与校图书馆的共建 总被引:5,自引:0,他引:5
马叶 《中北大学学报(社会科学版)》2005,21(2):103-104
高等院校的院系资料室是图书系统的组成部分,在承担院系教师和学生查阅资料方面,具有图书馆无可比拟的功能和作用。文章主要分析了高校院系资料室存在的问题以及其解决措施,并明确了院系资料室与图书馆之间的关系,对院系资料室的建设提供了借鉴。 相似文献