现代化进程中古城风貌的保护与延伸

在现代化进程中古城风貌保护与延伸的理论与对策应是社会学学者所关注的一个问题。古城应在动态中进行“城市性格”保护和延伸,在宏观上分异城市功能,在微观上注重“修旧如旧”和“点、线、面”的三位一体,城市社区的建设问题可以在保护和延伸中协调解决。     

从解一个古典概率问题所想到的

文章给出一个古典概率问题的两个解法，从而导出几个有趣的等式。     

The univariate distribution function for a particular bilinear model

The aim of the paper is to find the univariate stationary distribution of a particular bilinear process. In this context, we propose a novel approach to derive the distribution function. It is based on a recursive formula and allows to relax the conditions on the moments of the process. We also show that the derived approximation converges to the true distribution function. The accuracy of the recursive formula is evaluated for finite sample dimensions by a small simulation study.Received: February 2003, Revised: May 2004,     

《60分钟》与《东方时空》节目形态之比较

《60分钟》和《东方时空》是美中两国最具代表性的电视新闻杂志节目。为了进一步揭示这类节目的编辑规律,从四个方面对二者的节目形态进行比较分析。《60分钟》与《东方时空》都非常重视电视语言的合理运用,并逐步形成了各自的风格,但是在栏目设置、节目特征与形象设计、主持技巧等方面存在较大差异。     

货币政策规则的理论发展与启示

货币政策规则(尤其是"泰勒规则")自被提出以来,就深受关注,并在与"相机抉择"的政策决策原则的交锋中不断得到发展。现在的货币政策规则不再局限于货币当局设定固定的货币工具变量的狭隘涵义,而是指货币政策行为的一种指令性的向导,具体包括工具规则与目标规则。经济学家相信,与相机决策相比,规则性的政策能有效减少货币政策的动态不一致性。但是,现阶段在中国建立货币政策规则,尤其是实行通货膨胀目标规则的货币政策的条件并不成熟,而加快金融、财政和计划体制的改革,提高中央银行的独立性,增强政策的透明度,努力提高央行货币政策的一致性的信誉,则是我国的当务之急。     

胀接对管板强度的加强效应

由于胀接使列管与管板紧密连接，管壁厚度的部分或全部可以考虑在管桥 宽度中.本文通过数值计算分析了胀接对管板强度的加强效应.     

Bootstrap confidence regions computed from autoregressions of arbitrary order

Given a linear time series, e.g. an autoregression of infinite order, we may construct a finite order approximation and use that as the basis for confidence regions. The sieve or autoregressive bootstrap, as this method is often called, is generally seen as a competitor with the better-understood block bootstrap approach. However, in the present paper we argue that, for linear time series, the sieve bootstrap has significantly better performance than blocking methods and offers a wider range of opportunities. In particular, since it does not corrupt second-order properties then it may be used in a double-bootstrap form, with the second bootstrap application being employed to calibrate a basic percentile method confidence interval. This approach confers second-order accuracy without the need to estimate variance. That offers substantial benefits, since variances of statistics based on time series can be difficult to estimate reliably, and—partly because of the relatively small amount of information contained in a dependent process—are notorious for causing problems when used to Studentize. Other advantages of the sieve bootstrap include considerably greater robustness against variations in the choice of the tuning parameter, here equal to the autoregressive order, and the fact that, in contradistinction to the case of the block bootstrap, the percentile t version of the sieve bootstrap may be based on the 'raw' estimator of standard error. In the process of establishing these properties we show that the sieve bootstrap is second order correct.     

基于语义扩展的数字图书馆知识推荐系统

构建个性化知识推荐系统是数字图书馆实现个性化信息服务的有效手段,推荐服务的关键在于完整地理解用户兴趣并准确作出推荐.文章提出了一种基于语义扩展的知识推荐方法,通过分析读者文献检索、浏览的行为提取读者偏好.利用扩展激活模型扩充读者偏好档案,对文献信息资源进行匹配和分级,通过文献的级别决定推荐的次序,对推荐信息进行反馈,动态更新读者的偏好档案.     

A Conditional Variance Model for Daily Deviations of an Exchange Rate

A model for the distribution of daily deviations of an exchange rate is suggested. The distribution is Gaussian with a variance that depends on previous deviations. The model is applied to the exchange rate of the U.S. dollar to special drawing rights.