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101.
This paper analyses the interrelation between the transport system and measures of resource consumption such as material and energy consumption over a 60-year period (1937–1997) in the UK. Non-motorized transport and time consumption for mobility are estimated in addition to conventional measures of transport. During the period analyzed, the UK population grew by 20% while transport of goods and persons increased more than threefold and material and energy consumption almost doubled. The transport intensity of domestic material input (DMI) doubled to 300 ton-kilometers (tkm) per ton of DMI while the transport intensity of domestic energy consumption (DEC) doubled to 20 tkm per gigajoule (GJ) of DEC. Thus, while the material and energy intensity of GDP declined significantly, a well-established trend in many advanced countries, the transport intensity of materials and energy consumption rose. These findings suggest a close link between transport, economic development, and long-term structural transformations. In the case of personal transport, a rebound effect was also observed: whereas the average speed of transport has greatly increased, the average number of hours per day devoted to personal transport has not declined.  相似文献   
102.
A new approach for constructing tests for association between a random right censored life time variable and a covariate is proposed. The basic idea is to first arrange the observations in increasing order of the covariate and then base the test on a certain point process defined by the observation times. Tests constructed by this approach are robust against outliers in the covariate values or misspecification of the covariate scale since they only use the ordering of the covariate. Of particular interest is a test based on the Anderson-Darling statistic. This test has good power properties both against monotonic and nonmonotonic dependencies between the covariate and the life time variable.  相似文献   
103.
"车站信号自动控制"这一传统的铁路特色专业课程,其课程体系日显陈旧,在教学中存在的问题越来越突出。构建新的课程体系,要重组传统内容、加强新技术内容、拓宽应用。新体系实现途径是:提高理论层次,拓宽知识面,突出主干内容教学、改革教学手段和方法。  相似文献   
104.
考虑到灾后路网受损难以运输应急物资,本文研究了应急响应中车辆-直升机联合调度的路径优化问题。针对受灾地区的实时路况,通往灾区的救援工具受到数量以及装载量的约束,本文将受灾点等待救援的平均时间最短以及应急网络总费用最低设为目标,构建运力受限条件下带通行约束的救援物资联合运输多目标优化模型,然后根据随机邻域搜索变异和分级交叉的思想构建出一种带精英策略的非支配排序混合进化算法(NSHEA-II)得到模型的解,并利用算例分析对该算法进行可行性检验。结果发现,本文构建的NSHEA-II算法相对NSGA-II算法能够得到较好的结果且波动性较小,这为决策者制定救援物资的配送方案提供有效的技术支撑。  相似文献   
105.
利用网络分析工具和新经济地理理论对新古典区域经济增长模型进行修正,通过对交易费用的细分构建外部性和运输网络下的城市群经济增长模型,并利用1990-2008年中国部分城市数据和向量自回归模型(VAR)进行实证检验,得出以下结论。在运输网络影响下,中心城市依靠要素集聚获得增长,非中心城市快速接近中心城市。运输网络的改善,将加速中心城市的要素集聚。同时,在保留部分新增要素的情况下,增加节点集聚系数、降低非中心城市问的运输成本,利于非中心城市对外部性的应用,加速其经济增长,促进与中心城市的协同增长。因此,在建设交通运输基础设施时,不仅要重视非中心城市与中心城市的互联互通,更要重视非中心城市间的相互联结。  相似文献   
106.
Several test criteria are available for testing the hypothesis that the autoregressive polynomial of an autoregressive moving average process has a single unit root. Schwert (1989), using a Monte Carlo study, investigated the performance of some of the available test criteria. He concluded that the actual levels of the test criteria considered in his study are far from the specified levels when the moving average polynomial also has a root close to 1. This article studies the asymptotic null distribution of the test statistics for testing p = 1 in the model Yt = pY t-1 + e t0e t-1 as 0 approaches 1. It is shown that the test statistics differ from one another in their asymptotic properties depending on the rate at which 0 converges to 1.  相似文献   
107.
We study the normal variance-mean mixture model from a semiparametric point of view, i.e. we let the mixing distribution belong to a non-parametric family. The main results are consistency of the non-parametric maximum likelihood estimator and construction of an asymptotically normal and efficient estimator for the Euclidian part of the parameter. We study the model according to the theory outlined in the monograph by Bickel et al. (1993) and apply a general result (based on the theory of empirical processes) for semiparametric models from van der Vaart (1996) to prove asymptotic normality and efficiency of the proposed estimator.  相似文献   
108.
The Kaplan–Meier estimator of a survival function requires that the censoring indicator is always observed. A method of survival function estimation is developed when the censoring indicators are missing completely at random (MCAR). The resulting estimator is a smooth functional of the Nelson–Aalen estimators of certain cumulative transition intensities. The asymptotic properties of this estimator are derived. A simulation study shows that the proposed estimator has greater efficiency than competing MCAR-based estimators. The approach is extended to the Cox model setting for the estimation of a conditional survival function given a covariate.  相似文献   
109.
Is there still something specific East German in the need for counseling? There is a specific East German background, considering the adaption of issues, contents and methods of counseling of East German top management, enterprises and institutions. In the last ten years, development in East Germany was above all a make up for the development of West German conditions. Today the trends in West and East Germany are equally faced with the reorganization of processes resulting from global standards. These are confronted with a hardly stabil economical and social basis in East Germany. The general need for counseling is determined by psychological counseling and change management.  相似文献   
110.
The research on which this paper is based is part of a wider study of quality assurance and the voluntary sector. The focus of this paper is on complaints procedures, as part of quality assurance mechanisms, where voluntary agencies are the contracted service providers. The authors argue that, with the introduction of contracting and particularly with its further development, the way in which complaints mechanisms currently operate will need to be revised if they are to be an effective part of the quality assurance process.  相似文献   
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