Nonparametric estimation of variance, skewness and kurtosis of the distribution of a statistic by jackknife and bootstrap techniques

While jackknife and bootstrap estimates of the variance of a statistic are well–known, the author extends these nonparametric maximum likelihood techniques to the estimation of skewness and kurtosis. In addition to the usual negative jackknife also a positive jackknife as proposed by BERAN (1984) receives interest in this work. The performance of the methods is investigated by a Monte Carlo study for Kendall's tau in various situations likely to occur in practice. Possible applications of these developments are discussed.     

基于孔径长度域重采样的快速恒定束宽波束形成

为解决宽带阵列天线波束宽度抖动的问题,在分析阵元权系数和阵列方向图傅里叶变换关系的基础上,提出了一种基于孔径长度域重采样的快速恒定束宽宽带波束形成方法。该方法通过期望方向图的傅里叶反变换获取孔径长度域上的权系数曲线,然后用不同的采样间隔对该权系数曲线进行重采样得到不同频率下的阵元权系数。由于仅需进行一次积分运算,该方法具有运算量小、速度快的特点。为使阵列方向图在恒定束宽的基础上具有更好的方向性,通过对孔径长度域拟合度的分析给出了期望方向图的设计方法。仿真结果表明所提方法可以快速形成方向性较好的宽带阵列恒定束宽方向图。     

战略性新兴产业生态系统耦合模式研究

耦合模式是发展战略性新兴产业的重要方式之一。将物理学中的耦合理论应用于经济社会发展系统中,构建基于特定生态系统的产业耦合模式,并详细阐释产业与要素、产业与城市及空间、产业与产业之间的耦合。最后,以产业与城市为例进行耦合模式实证研究。结果表明,诸暨市战略性新兴产业与创新型城市间的耦合度处于濒临失调区间的上位部分,尚需要进一步加大科技投入、提升规模和科技含量、提高区域熵指数。     

知识立方体模型及激励工具的选择

知识是组织核心竞争力的主要来源,有效利用激励工具促进组织内的知识转移是组织获取竞争优势过程中十分必要及关键的一步。构建了知识的立方体模型,从知识隐性度、知识系统度、知识重要度3个维度分析和理解组织知识,在此基础上提出了在不同维度、不同水平下适用的激励方式。     

HFC-SCDMA抗汇聚噪声干扰能力的重点抽样仿真

基于MATLAB6．1平台，使用重点抽样（Importance Sampling)方法，对采用SCDMA体制的HFC上行信道抗汇聚噪声干扰的性能进行仿真，仿真中常用的Monte-Carlo方法由于受SCDMA系统巨大的计算量限制而不具有实用性，重点抽样技术是一种方差减少技术，它能显著地减少运算时间，SCDMA系统仿真同样的仿真精度条件下，重点抽样与Monte-Carlo仿真相比，重点抽样技术能显著地降低运算量。     

中国移动云计算发展探究

随着云计算概念被Google、Amazofl、IBM等公司高调推出，各主要的IT巨头纷纷提出了自己的云计算计划。现在，云计算的火爆也在向电信领域蔓延。国际上，全球电信运营商正在积极寻找云计算带给电信业的机会，部分运营商甚至已经宣布为客户提供基于云计算的服务。在中国，云计算也被电信运营商提上桌面。本文主要针对云计算这一概念，论述云计算对电信运营商的重要性，中国移动向云计算转型的必要性以及中国移动目前的云计算发展现状。     

Nonlinear dynamical structural equation models

Structural equation models (SEMs) have been widely used in behavioural, educational, medical and socio-psychological research for exploring and confirming relations among observed and latent variables. In the existing SEMs, the unknown coefficients in the measurement and structural equations are assumed to be constant with respect to time. This assumption does not always hold, as the relation among the observed and latent variables varies with time for some situations. In this paper, we propose nonlinear dynamical structural equation models to cope with these situations, and explore the nonlinear dynamic of the relation between the variables involved. A local maximum likelihood-based estimation procedure is proposed. We investigate a bootstrap resampling-based test for the hypothesis that the coefficient is constant with respect to time, as well as confidence bands for the unknown coefficients. Intensive simulation studies are conducted to show the empirical performance of the proposed estimation procedure, hypothesis test statistic and confidence band. Finally, a real example in relation to the stock market of Hong Kong is presented to demonstrate the proposed methodologies.     

Importance‐Performance and Segmentation: An Application at a Biosphere Reserve in Vietnam

This paper examines how importance‐performance analysis (IPA) used with segmentation can be an effective natural resource management tool. Data were obtained from visitors (n = 368, response rate = 66%) to the Can Gio Mangrove Biosphere Reserve, Vietnam. Two distinct user segments were identified according to their preference for facility development within the reserve. The two segments differed in their importance‐performance ratings for (a) attractions, (b) beach facilities and services, (c) facilities in the area, and (d) beauty of the area. Those favoring development rated each of these reserve attributes as more important (p < .001) than those less disposed to additional development. Those favoring development rated the performance of three of four attributes positively, while all four attributes received negative performance scores for those less disposed to additional development. Implications show that segmentation can allow for more accurate planning and decision making.     

电子商务在我国进出口贸易发展中面临的问题及其对策

随着互联网的不断发展,电子商务在世界各国得以迅猛发展。它具有费用低廉、覆盖面广、功能全面、操作灵活、延伸面广的特点。电子商务已经逐渐渗透到国际贸易的每一个角落,出现了虚拟市场、虚拟公司,而且对贸易的方式和经营管理模式产生了重要影响。     

On a crossroad of resampling plans: bootstrapping elementary symmetric polynomials

We investigate the validity of the bootstrap method for the elementary symmetric polynomials S ^{( k )} _n =( ⁿ _k )⁻¹Σ_{1≤ i 1}< ... < i _k ≤ n X _{i 1} ... X _{i k} of i.i.d. random variables X ₁, ..., X _n . For both fixed and increasing order k , as n→∞ the cases where μ=E X ₁[moe2]0, the nondegenerate case, and where μ=E X ₁=0, the degenerate case, are considered.