Kernel Estimation of Rate Function for Recurrent Event Data

Abstract.  Recurrent event data are largely characterized by the rate function but smoothing techniques for estimating the rate function have never been rigorously developed or studied in statistical literature. This paper considers the moment and least squares methods for estimating the rate function from recurrent event data. With an independent censoring assumption on the recurrent event process, we study statistical properties of the proposed estimators and propose bootstrap procedures for the bandwidth selection and for the approximation of confidence intervals in the estimation of the occurrence rate function. It is identified that the moment method without resmoothing via a smaller bandwidth will produce a curve with nicks occurring at the censoring times, whereas there is no such problem with the least squares method. Furthermore, the asymptotic variance of the least squares estimator is shown to be smaller under regularity conditions. However, in the implementation of the bootstrap procedures, the moment method is computationally more efficient than the least squares method because the former approach uses condensed bootstrap data. The performance of the proposed procedures is studied through Monte Carlo simulations and an epidemiological example on intravenous drug users.     

文学意义的消解与重建

在商品化和信息化的时代大潮冲击下 ,文学面临着意义的流失与消解。文学的这种现状是与整个人类文化的困境紧密相关的 ,是人类发展特殊阶段上的必然产物。中国当代文学应致力于意义的探寻与重建 ,这表现为在对现实的清醒认识的基础上对理想的重新肯定 ,对现实中的物欲的批判性把握 ,以及对人类生存意义的重新认识。     

江南古镇商业化倾向及其可持续发展对策——以浙北三镇为例

江南水乡古镇旅游业发展20多年以来,商业化现象日益严重,古镇沿街充斥着服务旅游者的各色同质化的商铺和商品,不仅冲淡古镇原真景观特征,形成古镇因利趋同格局,而且改变了居民生活方式并成为重要的生活基础,直接干扰居民日常生活,破坏古镇整体人文生态系统的和谐,破坏古镇原有自然风貌和景观环境。立足于古镇原真性保护,在商业化快速发展的过程中政府应淡出商业利益,严格控制商业发展;拓展和营造多样化社区参与旅游的方式和途径,调整利益分配体制,建立行业利益平衡机制;鼓励和发展传统手工艺,形成旅游体验与民间非物质文化遗产保护双赢格局。     

飞灰冲蚀条件下材料抗磨性能的试验研究

本文首先综述了国内外学者在研究塑性材料耐冲蚀磨损性能方面所取得的主要成果,并在专门建立的灰磨试验台上,对电站燃煤锅炉对流受热面常用材料20号钢、12Cr_1MoV合金铜以及铜、铝四种塑性材料进行了耐飞灰冲蚀磨损性能的试验研究。提出用材料的体积磨损率来定义材料的耐冲蚀磨损性能系数。并用它表征塑性材料的抗磨性能。该系数可直接应用于计算燃煤锅炉对流受热面的安全烟速。     

铝基化学镀镍的研究

研究了铝基化学镀镍的工艺过程，详细介绍了化学镀镍前的处理过程，其中包括除油，浸蚀，清洗和没锌过程。研究了各因素对化学镀镍镀速的影响因素，并得出最佳配方及工艺条件。在最佳条件下，化学镀镍镀速高，镀层着附力优异，可焊性优良。     

黑龙江省工业资本产出贡献率的实证分析

提高老工业基地的经济增长水平,是一个意义深远的课题。黑龙江省老工业基地发展相对落后的原因在于工业实收资本结构的不合理,国家资本偏高,个人资本绝对性偏低,单位个人资本效率是单位国家资本的五倍。法人资本的多层代理也是造成黑龙江省工业发展相对落后的原因之一。对此,应妥善解决委托代理失灵问题,大力促进民营资本的发展,加快国有经济布局的战略性调整。     

Towards Enhancement of the Economy of a Thermal Power Generating System through Prediction of Plant Efficiency

The plant ‘Heat Rate’ (HR) is a measure of overall efficiency of a thermal power generating system. It depends on a large number of factors, some of which are non-measurable, while data relating to others are seldom available and recorded. However, coal quality (expressed in terms of ‘effective heat value’ (EHV) as kcal/kg) transpires to be one of the important factors that influences HR values and data on EHV are available in any thermal power generating system. In the present work, we propose a prediction interval of the HR values on the basis of only EHV, keeping in mind that coal quality is one of the important (but not the only) factors that have a pronounced effect on the combustion process and hence on HR. The underlying theory borrows the idea of providing simultaneous confidence interval (SCI) to the coefficients of a p-th p(≥1) order autoregressive model (AR(p)). The theory has been substantiated with the help of real life data from a power utility (after suitable base and scale transformation of the data to maintain the confidentiality of the classified document). Scope for formulating strategies to enhance the economy of a thermal power generating system has also been explored.     

关于学报发展中几个问题的思考

在互联网日益普及的情况下，高校学报不应等待观望，而应尽快转变认识，充分利用网络资源进行新的尝试，为自身的发展服务。高校学报要走的个性化特色化之路，通过对可资形成特色的各种条件进行创造性整合，形成刊物的个性与特色。注重提高刊物的学术影响力，提高所刊论文的引用率与引文率，在增强社会效益上做文章。同时，也要重视编排的标准化、规范化等工作，以期使学报的生存与发展进入良性循环。     

A simple procedure for the selection of significant effects

Summary.  Given a large number of test statistics, a small proportion of which represent departures from the relevant null hypothesis, a simple rule is given for choosing those statistics that are indicative of departure. It is based on fitting by moments a mixture model to the set of test statistics and then deriving an estimated likelihood ratio. Simulation suggests that the procedure has good properties when the departure from an overall null hypothesis is not too small.     

Statistical Analyses and Modelling of the Mixing Process of Euro Coins in Germany and Europe

This paper reports on the mixing of Euro coins from different countries of origin in Europe, which started on 1 January 2002. There is an interesting conclusion: that the mobility of small and large denominations is different. The long‐term behaviour of the mixing process is studied using a simple deterministic model and data from Germany, France and the Netherlands. The analysis leads to predictions about the future progress of the mixing process.