论农村信息化建设

农村信息化是新形势下现代化发展与信息化战略自然耦合的结果。新农村信息化建设是个复杂的系统工程,加快农村信息化建设是统筹城乡经济社会发展,缩小城乡“数字鸿沟”,促进城乡经济交流、文化交融和农民思想观念更新的一项重要举措,是解决“三农”问题和建设社会主义新农村的重要途径。     

流密码与纠错码联合设计新方向——快速相关攻击译码算法研究进展

快速相关攻击是分析流密码组合生成器最有效的攻击方法,其核心思想是将组合流密码的破译转化为译码问题,利用纠错码的译码技术实现对组合流密码的攻击。近年来,基于纠错码译码技术的流密码快速相关攻击技术有重要的进展和应用,因此总结快速相关攻击技术的发展现状,提出并分析新的快速相关攻击问题,有重要的学术和应用价值。该文首次将流密码快速相关攻击模型应用到纠错码理论中,提出流密码和纠错码联合设计新的研究方向,其研究成果有望解决极低信噪比环境下的可靠通信这一当前通信领域的难题。依据快速相关攻击的基本原理,分析并比较了4类典型快速相关攻击算法,即Meier-Staffelbach型算法,分别基于卷积码和Turbo码的攻击算法,CJS算法和基于LDPC码的快速相关攻击算法。最后得出快速相关攻击算法的一般适用准则,指出了快速相关攻击中尚未解决的问题和进一步的研究内容。     

Effects of correlation and missing data on sample size estimation in longitudinal clinical trials

In longitudinal clinical trials, a common objective is to compare the rates of changes in an outcome variable between two treatment groups. Generalized estimating equation (GEE) has been widely used to examine if the rates of changes are significantly different between treatment groups due to its robustness to misspecification of the true correlation structure and randomly missing data. The sample size formula for repeated outcomes is based on the assumption of missing completely at random and a large sample approximation. A simulation study is conducted to investigate the performance of GEE sample size formula with small sample sizes, damped exponential family of correlation structure and non‐ignorable missing data. Copyright © 2008 John Wiley & Sons, Ltd.     

企业伦理气候、组织承诺与组织公民行为的关系——以温州民营企业为例

企业社会责任等方面存在的问题是造成温州民营企业“民工荒”的重要原因。通过问卷调查,发现员工对企业伦理气候中的法规导向最为认可且看法比较一致,对组织承诺中的情感承诺最为认可且对道德承诺的看法相对一致,对组织公民行为中的组织公益最为认可且看法比较一致。员工对组织承诺、组织公民行为的主张是正向积极的,未发现企业伦理气候、组织承诺对组织公民行为有强烈的正向影响。提出温州民营企业摆脱困境的思路：重视企业伦理气候建设,形成正确的企业文化,增强员工的向心力;强化员工的组织承诺;鼓励员工的组织公民行为。     

A multivariate time series model for the analysis and prediction of carbon monoxide atmospheric concentrations

We use a Bayesian multivariate time series model for the analysis of the dynamics of carbon monoxide atmospheric concentrations. The data are observed at four sites. It is assumed that the logarithm of the observed process can be represented as the sum of unobservable components: a trend, a daily periodicity, a stationary autoregressive signal and an erratic term. Bayesian analysis is performed via Gibbs sampling. In particular, we consider the problem of joint temporal prediction when data are observed at a few sites and it is not possible to fit a complex space–time model. A retrospective analysis of the trend component is also given, which is important in that it explains the evolution of the variability in the observed process.     

Case–control studies with complex sampling

The use of complex sampling designs in population-based case–control studies is becoming more common, particularly for sampling the control population. This is prompted by all the usual cost and logistical benefits that are conferred by multistage sampling. Complex sampling has often been ignored in analysis but, with the advent of packages like SUDAAN, survey-weighted analyses that take account of the sample design can be carried out routinely. This paper explores this approach and more efficient alternatives, which can also be implemented by using readily available software.     

一种选取相空间重构最优延迟时间的算法

利用时间序列的可预测性随预测步长变化的规律,提出了一种选取最优延迟时间的新方法;用已知的混沌系统Lorenz、Rossler等产生的时间序列进行仿真计算,与重建扩展法相比,取得了较好的结果,证明了该方法的有效性。     

子波变换在超宽带雷达中的应用

介绍了连续子波变换的定义和性质：基于子波变换在时域和频域的良好局部化性质;研究其在宽带信号的相关处理和超宽带雷达目标特征提取两个方面的应用,理论分析和试验结果表明,在超宽带雷达信号处理中,宽带相关处理相当于时间尺度域的匹配滤波,采用连续子波变换从频域采样数据中提取目标散射中心是一种较为鲁棒的方法。     

商品期货指数的编制研究及功能检验

在国际期货市场上,商品指数已经成为市场走势重要的风向标。而在国内市场上,商品指数的研究和开发还处于起步阶段。在国内为数不多的商品期货指数中,中科-格林商品期货指数(M-G Commodity futures index)是较为重要的一个。该指数在开发过程中充分借鉴了国际成熟商品指数的经验,同时也考虑了中国期货市场的自身发展特点,具有较强的适用性。本文以中科-格林商品指数为研究对象,阐述了商品期货指数的编制方法,并验证了指数的功能。     

Tests for assessment of agreement using probability criteria

For the assessment of agreement using probability criteria, we obtain an exact test, and for sample sizes exceeding 30, we give a bootstrap-t$t$ test that is remarkably accurate. We show that for assessing agreement, the total deviation index approach of Lin [2000. Total deviation index for measuring individual agreement with applications in laboratory performance and bioequivalence. Statist. Med. 19, 255–270] is not consistent and may not preserve its asymptotic nominal level, and that the coverage probability approach of Lin et al. [2002. Statistical methods in assessing agreement: models, issues and tools. J. Amer. Statist. Assoc. 97, 257–270] is overly conservative for moderate sample sizes. We also show that the nearly unbiased test of Wang and Hwang [2001. A nearly unbiased test for individual bioequivalence problems using probability criteria. J. Statist. Plann. Inference 99, 41–58] may be liberal for large sample sizes, and suggest a minor modification that gives numerically equivalent approximation to the exact test for sample sizes 30 or less. We present a simple and accurate sample size formula for planning studies on assessing agreement, and illustrate our methodology with a real data set from the literature.