我国灾后废墟管理的进程、问题与趋势初探

废墟管理和垃圾废物处理,是灾后恢复重建以及环境保护工作的难点和重要内容。近年来,我国自然灾害频繁,废墟量不断增多,废墟垃圾若不综合利用、处理,不仅影响灾后恢复重建,而且还会加重生态灾难。而我国在废墟管理方面还相对落后,在废墟处理、管理等环节存在突出问题和技术难题。借鉴日本废墟管理有益经验,废墟管理呈现向专业化、市场化、智能化和法制化方向发展的趋势。     

传媒商业化带来的相关问题分析

传媒商业化是当前中国传媒变革中的热点问题.尽管商业化成为传媒业发展的加速器,但其带来的社会负面效应也必须正视:传媒产品娱乐化、低俗化现象严重,商业炒作无处不在,主流媒体"喉舌"功能减弱等,由此造成媒体的社会责任感不断弱化.对于这些问题,应根据我国传媒业发展的阶段性特点进行系统分析,并借鉴发达国家的相关管制经验,找出一个适用性的解决方案.     

Estimation and Inference for Linear Panel Data Models Under Misspecification When Both n and T are Large

This article considers fixed effects (FE) estimation for linear panel data models under possible model misspecification when both the number of individuals, n, and the number of time periods, T, are large. We first clarify the probability limit of the FE estimator and argue that this probability limit can be regarded as a pseudo-true parameter. We then establish the asymptotic distributional properties of the FE estimator around the pseudo-true parameter when n and T jointly go to infinity. Notably, we show that the FE estimator suffers from the incidental parameters bias of which the top order is O(T^{? 1}), and even after the incidental parameters bias is completely removed, the rate of convergence of the FE estimator depends on the degree of model misspecification and is either (nT)^{? 1/2} or n^{? 1/2}. Second, we establish asymptotically valid inference on the (pseudo-true) parameter. Specifically, we derive the asymptotic properties of the clustered covariance matrix (CCM) estimator and the cross-section bootstrap, and show that they are robust to model misspecification. This establishes a rigorous theoretical ground for the use of the CCM estimator and the cross-section bootstrap when model misspecification and the incidental parameters bias (in the coefficient estimate) are present. We conduct Monte Carlo simulations to evaluate the finite sample performance of the estimators and inference methods, together with a simple application to the unemployment dynamics in the U.S.     

民国时期北京商业整体布局与三类商业街区

民国时期北京古都商业街以大型商业街、常规商业街、专业商业街的形态存在，具有强烈的时代印记。商业街的结构因百货业态的出现而向完善方向迈进。以个人技艺为动力的民族商业给商业街增添了活力，外国政治势力破坏了传统的商业街繁荣气氛。     

Expert Systems

Summary

Expert systems are computer programs which embody the expertise of a human expert in order to consult and advise on a specific problem. It is now becoming feasible to apply expert systems technology to problems in the human services. This article describes what expert systems technology is and how it may be applied in human service practice. Finally, some of the promises and pitfalls of this new technology are addressed.     

论琼南黎族地区中学数学教师培训中的瓶颈问题

通过对琼南黎族地区中学数学教师培训现状的分析,研究了制约教师培训效果的瓶颈问题,分析了产生瓶颈问题的原因,并对突破瓶颈问题的关键进行了探讨。     

Computing the probability of hash table/urn overflow

We analyze the probability of a random distribution of n balls into m urns of size b resulting in no overflows. This solves the computational problem associated with a classical combinatorial extreme-value distribution. The problem arose during the analysis of a technique, called perfect hashing, for organizing data in computer files. The results and techniques presented can be used to solve several problems in the analysis of hashing techniques     

Testing for a change in covariance operator

The paper considers a problem of equality of two covariance operators. Using functional principal component analysis, a method for testing equality of K largest eigenvalues and the corresponding eigenfunctions, together with its generalization to a corresponding change point problem is suggested. Asymptotic distributions of the test statistics are presented.     

A class of distribution-free tests for two-way layout

In this article a class of distribution-free tests for the hypothesis of no row (treatment) effect in a two-way layout design, with several observations per cell, is proposed. The tests are based on U-statistics, constructed by considering minima of all possible subsamples of same size from each cell.The proposed class of tests is compared with the parametric test, Mack and Skillings test and Yate's test for two-way layout, in terms of Pitman ARE sense. It is seen that for the case of equal number of observations per cell, the proposed tests have better efficiency for exponential and uniform error distributions.     

辽宁“十二五”工业经济发展规划的战略思考——基于产业竞争力的视角

基于产业竞争理论分析辽宁工业经济发展的现状，针对其中存在的利润率低、工业内部配套能力弱、产业之间发展不协调和民间投资被挤出等结构性问题分析其产生原因，认为政府主导资源推动型的发展方式和政府产业规划的雷同性及路径依赖性是造成结构性失衡的主要原因。为此，建议政府在编制辽宁“十二五”工业经济发展规划时应考虑效益指标，按产业发展周期和要素、需求条件等规划重点发展产业，并处理好支柱产业与支撑产业、相关产业之间的关系。