Sequential facility location with distance dependent demand

Systems providing identical service to many population centers frequently face the issue of where to locate the next retail outlet, branch, store, etc. In such systems the demand for the facilities' service depends mainly on the distance between facilities and customers. It is assumed that there are already m facilities located on a network to respond to the demand at the nodes. The paper addresses the problems of finding a location on the network for the (m +1 )st facility corresponding to a given total expected demand and of determining which demand points will be served by which facility. Also the range of the total expected demand values that can be realized along each link in the m +1 facility system is determined. Examples and a discussion of the results are provided.     

Spatial correlation robust inference with errors in location or distance

This paper presents results from a Monte Carlo study concerning inference with spatially dependent data. We investigate the impact of location/distance measurement errors upon the accuracy of parametric and nonparametric estimators of asymptotic variances. Nonparametric estimators are quite robust to such errors, method of moments estimators perform surprisingly well, and MLE estimators are very poor. We also present and evaluate a specification test based on a parametric bootstrap that has good power properties for the types of measurement error we consider.     

西方城市公共服务设施区位研究进展

通过梳理国外公共服务设施区位理论的发展以及近年来研究的新动向,提出了对我国城市公共服务设施区位研究的展望。     

Small sample behaviour of some nonparametric multi-sample location tests in the presence of dispersion differences

This paper describes the small and moderate sample behaviour of three studentized non-parametric statistics by Sen and a modified Wilcoxon statistic by Potthoff for testing the equality of location parameters in the presence of dispersion differences. Based on the agreement between the asymptotic and small sample distributions of the statistics as well as a comparison of their power under heteroscedasticity, the studentized Wilcoxon and the studentized Brown and Mood tests arc preferred in the two-sample and c-sample situations, respectively.     

On optimal choice of order statistics in large samples for the construction of confidence regions for the location and scale

Given a large sample from a location-scale population we estimate the unknown parameters by means of confidence regions constructed on the basis of two order statistics. The problem of the best choice of those statistics to obtain good estimates, as $n\rightarrow \infty ,$ is considered.     

试论企业文化建设

企业文化不是自然而然地形成起来的,而是要通过主动的建设形成的.所以不能把企业文化当成一种完全可以通过自然而然的方式而形成起来的价值理念,而是要注重对企业文化的建设.     

On a metric in the space of random variables

Van een metriek d(x,y) gedefinieerd op de ruimte Ω van alle stochastische variabelen worden twee interessante eigenschappen bewezen. Deze kunnen soms met vrucht onder meer worden toegepast voor de beoordeling of bij een gegeven monotone functie f, en een benadering y van x, ook f(y) een goede benaderende stochastiek is voor f(x).     

论互联网中法的定位

互联网经过40余年的迅猛发展,已渗透到人们工作、学习以及娱乐等日常生活的方方面面,并孕育出其独特的网络文化。然而,其也隐藏着天生的缺陷。随着国家法制建设不断完善和法治理念的不断加强,对网络进行法律规范已成为一种共识。文章就互联网中法的定位进行粗略的讨论,从法律的角度对互联网进行了初步分析。     

环境预测模型的应用评述

本文综述了目前水资源承载预测和雾霾天气预测的若干种常用方法,传统方法如回归分析,灰色预测,新型智能算法如神经网络、系统动力学法。通过对比这些分析方法的在实际应用中的效果,来评述现有环境预测方法的优势与不足。传统方法,操作简单易于实现,但精度较差;新型算法可做精确预测,但较难实现且预测范围窄。最后,展望环境预测方法发展趋势。     

天津小城镇建设的“华明模式”评析

界定了天津小城镇建设的"华明模式",将其核心内容概括为"以宅基地换房"。认为"华明模式"的成功经验包括尊重农村居民意愿,化解城乡土地利用二元化的突出矛盾,提前实现土地开发的"土地平衡"和"资金平衡",同时这一模式也具有宏观上需要有特定的经济环境、中观上仅适用于城市近郊地域和微观上需要土地周转指标支持的局限性。就"华明模式"在实践中出现的失地农村居民就业不足、物化城镇化超前于思想观念城镇化两方面的问题,提出了"华明模式"的调整方向。     

Notes on consistency of some minimum distance estimators with simulation results

We focus on the minimum distance density estimators \({\widehat{f}}_n\) of the true probability density \(f_0\) on the real line. The consistency of the order of \(n^{-1/2}\) in the (expected) L\(_1\)-norm of Kolmogorov estimator (MKE) is known if the degree of variations of the nonparametric family \(\mathcal {D}\) is finite. Using this result for MKE we prove that minimum Lévy and minimum discrepancy distance estimators are consistent of the order of \(n^{-1/2}\) in the (expected) L\(_1\)-norm under the same assumptions. Computer simulation for these minimum distance estimators, accompanied by Cramér estimator, is performed and the function \(s(n)=a_0+a_1\sqrt{n}\) is fitted to the L\(_1\)-errors of \({\widehat{f}}_n\) leading to the proportionality constant \(a_1\) determination. Further, (expected) L\(_1\)-consistency rate of Kolmogorov estimator under generalized assumptions based on asymptotic domination relation is studied. No usual continuity or differentiability conditions are needed.     

Estimating demand with distance functions: Parameterization in the primal and dual

Our purpose is to investigate the ability of different parametric forms to ‘correctly’ estimate consumer demands based on distance functions using Monte Carlo methods. Our approach combines economic theory, econometrics and quadratic approximation. We begin by deriving parameterizations for transformed quadratic functions which are linear in parameters and characterized by either homogeneity or which satisfy the translation property. Homogeneity is typical of Shephard distance functions and expenditure functions, whereas translation is characteristic of benefit/shortage or directional distance functions. The functional forms which satisfy these conditions and include both first- and second-order terms are the translog and quadratic forms, respectively. We then derive a primal characterization which is homogeneous and parameterized as translog and a dual model which satisfies the translation property and is specified as quadratic. We assess functional form performance by focusing on empirical violations of the regularity conditions. Our analysis corroborates results from earlier Monte Carlo studies on the production side suggesting that the quadratic form more closely approximates the ‘true’ technology or in our context consumer preferences than the translog.     

On the distribution of a distance function on the sphere

Summary The distribution of the square of the distance between a random point and a fixed point on ap-dimensional unit sphere when (i) the two points lie on the whole sphere and (ii) the two points lie in the positive quadrant, has been derived, assuming that the random point is distributed proportionally to exp (ky ₁), wherek is a concentration parameter. Then-th order moment in both cases is also obtained.     

巨型城市区域研究的沿革和新进展

系统地回顾了关于城市区域思想的演变历程,重点介绍了国际城市规划界的前沿动态:巨型城市区、巨型区域的研究新进展。     

Minimum distance estimators for count data based on the probability generating function with applications

This paper studies properties of parameter estimators obtained by minimizing a distance between the empirical probability generating function and the probability generating function of a model for count data. Specifically, it is shown that, under certain not restrictive conditions, the resulting estimators are consistent and, suitably normalized, asymptotically normal. These properties hold even if the model is misspecified. Three applications of the obtained results are considered. First, we revisit the goodness-of-fit problem for count data and propose a weighted bootstrap estimator of the null distribution of test statistics based on the above cited distance. Second, we give a probability generating function version of the model selection test problem for separate, overlapping and nested families of distributions. Finally, we provide an application to the problem of testing for separate families of distributions. All applications are illustrated with numerical examples.     

公路隧道火灾车辆引燃临界距离研究

隧道火灾时如果车辆停靠间距过小,可能导致火源附近的车辆被引燃从而导致更大规模的火灾。文章对隧道火灾中车辆的受热引燃机理进行了分析,并利用火灾动力学软件FDS,以南京过江隧道为背景,对隧道内车辆间的受热引燃进行了数值模拟,得出了不同火灾场景下的车辆引燃临界距离,为控制车距、减小火灾蔓延提供了依据。     

The effect of location on finding a job in the Paris region

Do spatial differences in unemployment duration reflect residential sorting or a true local effect? Focusing on the 1300 municipalities of the Paris region, we apply a methodology that disentangles individual and unspecified municipality effects. Estimating a proportional hazard model stratified by municipality and recovering a survival function for each municipality purged of individual observed heterogeneity, we show that local and individual characteristics add up in their contribution to unemployment duration. While only 30% of the spatial disparities in unemployment duration are explained by individual characteristics, 70% of the remaining disparities are captured by local indicators, mainly correlated with residential segregation. Copyright © 2010 John Wiley & Sons, Ltd.     

我国物流金融发展理论研究述评

物流金融是一项创新型的物流增值服务,它是物流业与金融业发展到一定阶段的产物。文中在对物流金融实践和理论文献的归纳及述评,提出了未来物流金融发展的方向。