Estimation of Hazard, Density and Survivor Functions for Randomly Censored Data

Maximum likelihood estimation and goodness-of-fit techniques are used within a competing risks framework to obtain maximum likelihood estimates of hazard, density, and survivor functions for randomly right-censored variables. Goodness-of- fit techniques are used to fit distributions to the crude lifetimes, which are used to obtain an estimate of the hazard function, which, in turn, is used to construct the survivor and density functions of the net lifetime of the variable of interest. If only one of the crude lifetimes can be adequately characterized by a parametric model, then semi-parametric estimates may be obtained using a maximum likelihood estimate of one crude lifetime and the empirical distribution function of the other. Simulation studies show that the survivor function estimates from crude lifetimes compare favourably with those given by the product-limit estimator when crude lifetimes are chosen correctly. Other advantages are discussed.     

关于硕士研究生培养“两年制”的思考

我国硕士研究生教育的培养目标一直定位在学术型人才的培养上,但随着国际化进程的发展以及国内现实的需要,硕士研究生的培养模式发生了转变。改革硕士生的培养学制被提上了日程,在国内某些重点高校也进行了试点。然而“两年制”的学制改革也引发了社会各阶层的争议,学制改革是否可行成为争论的焦点。两年制的改革不仅影响到硕士研究生教育未来的发展道路,而且也成为关系教育能否高效、高质的为国家经济、社会建设输送高级人才的重要课题。     

Adaptive tests of regression functions via multiscale generalized likelihood ratios

Many applications of nonparametric tests based on curve estimation involve selecting a smoothing parameter. The author proposes an adaptive test that combines several generalized likelihood ratio tests in order to get power performance nearly equal to whichever of the component tests is best. She derives the asymptotic joint distribution of the component tests and that of the proposed test under the null hypothesis. She also develops a simple method of selecting the smoothing parameters for the proposed test and presents two approximate methods for obtaining its P‐value. Finally, she evaluates the proposed test through simulations and illustrates its application to a set of real data.     

Markov chain Monte Carlo methods for high dimensional inversion in remote sensing

Summary.  We discuss the inversion of the gas profiles (ozone, NO₃, NO₂, aerosols and neutral density) in the upper atmosphere from the spectral occultation measurements. The data are produced by the 'Global ozone monitoring of occultation of stars' instrument on board the Envisat satellite that was launched in March 2002. The instrument measures the attenuation of light spectra at various horizontal paths from about 100 km down to 10–20 km. The new feature is that these data allow the inversion of the gas concentration height profiles. A short introduction is given to the present operational data management procedure with examples of the first real data inversion. Several solution options for a more comprehensive statistical inversion are presented. A direct inversion leads to a non-linear model with hundreds of parameters to be estimated. The problem is solved with an adaptive single-step Markov chain Monte Carlo algorithm. Another approach is to divide the problem into several non-linear smaller dimensional problems, to run parallel adaptive Markov chain Monte Carlo chains for them and to solve the gas profiles in repetitive linear steps. The effect of grid size is discussed, and we present how the prior regularization takes the grid size into account in a way that effectively leads to a grid-independent inversion.     

用声学测量预报等温淬火球墨铸铁强度

等温淬火球墨铸铁的机械性能与其声学性能相关。本文将两种碳当量球铁在８４５，８９９和９４５℃温度进行奥氏体处理，在２６０，３１６和３７１℃温度进行等温淬火得到证实。声学性能测量包括共振频率，声速和内耗。由共振频率转换成动态模量表示出这种关系可以用来预报球墨铸铁不同热处理条件下的机械性能。     

Statistik für bivariate gemischte Poisson–Prozesse am Beispiel der Kraftfahrthaftpflichtversicherung

Zusammenfassung: In diesem Artikel wird der Weg von einem univariaten gemischten Poisson–Prozess, der in vielen Bereichen zum Z?hlen von Ereignissen benutzt wird, zu einem bivariaten gemischten Poisson–Prozess aufgezeigt. Dazu werden einige Eigenschaften des bivariaten Prozesses angegeben. Im zweiten Teil der Arbeit wird gezeigt, wie mit Hilfe dieses Prozesses der übergang von einem herk?mmlichen Bonus–Malus–System in der Kraftfahrthaftpflichtversicherung zu einem Bonus–Malus–System mit Berücksichtigung der Schadenart beschritten werden kann. Dazu wird zuerst eine Modellprüfung der gegebenen Daten vorgenommen und sodann werden für verschiedene mischende Verteilungen die Verteilungsparameter gesch?tzt und Nettopr?mien angegeben sowie die Prognosegenauigkeit getestet.

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Summary: In this paper we show that the model of the bivariate mixed Poisson process arises in a natural way from the univariate mixed Poisson process, which is used in several areas for counting certain events. Furthermore we state some properties of the bivariate process. In the second part of the paper we illustrate how by means of the bivariate mixed Poisson process a bonus–malus system handling different types of accidents can be derived from the classical bonus–malus system in third–party liability insurance. To this end we first check the model on the given data and then estimate distribution parameters and compute net premiums for different mixing distributions as well as test the prediction probabilities.

* Vortrag am Dresdner Forum zur Versicherungsmathematik: Tarifierung in Erst- und Rückversicherung am 25. Juni 2004. Für die Unterstützung zu dieser Arbeit m?chte der Autor Lothar Partzsch, Klaus D. Schmidt (beide Dresden) und Friedemann Spies (München) recht herzlich danken.     

从网络小说看网络文学基本特征

网络文学已登上二十一世纪中国文学的大雅之堂。从最能体现网络文学基本特征的网络小说进行探析 ,认为网络文学的基本特征为 :情感表达的宣泄性 ;著读交流的迅捷性 ;叙事结构的随意性 ;语言表达的能动性等。     

电子商务在煤炭贸易中的应用

电子商务是对整个贸易活动实现电子化 ,具有营运成本低、用户范围广、无时空限制以及能同用户直接互动交流等特点 ,代表着未来贸易发展的方向。电子商务在化工、家电、IT等商品流通领域已得到充分利用 ,而在我国的煤炭销售方面还没有专业性网站。建立专业的煤炭贸易电子商务网站对促进煤炭销售市场规范化、加速煤炭工业的可持续发展有重大意义。本文以中国煤炭贸易电子商务网站 (WWW .JCLC ,COM .CN)建设为例介绍了电子商务在煤炭贸易中的应用     

用Chat Anywhere工具架构局域网内的聊天室

以如何应用ChatAnywhere工具来实现建立一种架设内网聊天服务器的简单方法。     

基于串行通信的双Web服务器冗余系统设计与实现

设计实现了一个基于串行口通信的双Web服务器的冗余系统,详细介绍了基于串行通信口的实现方法,并对冗余系统的原理和实现过程进行了分析。