交通网络中动态OD矩阵反推算法研究

文章根据极大熵基本原理并运用排列组合理论推导出OD矩阵反推的极大熵模型;然后用拉格朗日乘子法求得该模型的非线性方程组,并运用Newton算法对此非线性方程组求解,得到动态OD估计矩阵。最后,在实例应用中,应用此模型和文章给出的模型解法取得了令人满意的结果。     

基于出租车GPS数据聚类分析醮交通小区动态划分方法研究

对交通出行数据进行优化，抽取出租车载客过程中乘客上下车的GPS位置坐标。基于聚类与交通小区划分的相似性，采用K-Means聚类法进行交通小区的划分。首先，通过聚类得到交通出行OD矩阵，然后据此划分出交通小区。基于Google Maps API，搭建了软件平台。通过试验可以看出，这种动态划分方法得到的区域能够与现有的交通小区相吻合。这种高实时的交通小区划分方法将对动态的OD估计有着极大的参考价值。     

基于模拟退火的OD矩阵估计研究

由路段交通量估计交通起止点矩阵OD时,一般都要求解非线性的目标函数,使用通常的随机搜索算法容易陷入局部最优的陷阱。本文将模拟退火算法应用于OD估计问题,使用双层规划的OD估计模型,并给出了启发性算法。     

利用道路交通流量进行OD矩阵反推的模型与方法综述

分别从静态和动态角度对基于路段交通流量的OD矩阵反推模型与方法进行了综述,并依据不同的分类标准对文献中出现的OD矩阵反推模型与方法进行了分类.     

基于出租车GPS数据聚类分析的交通小区动态划分方法研究

对交通出行数据进行优化,抽取出租车载客过程中乘客上下车的GPS位置坐标.基于聚类与交通小区划分的相似性,采用K-Means聚类法进行交通小区的划分.首先,通过聚类得到交通出行OD矩阵,然后据此划分出交通小区.基于Google Maps API,搭建了软件平台.通过试验可以看出,这种动态划分方法得到的区域能够与现有的交通小区相吻合.这种高实时的交通小区划分方法将对动态的OD估计有着极大的参考价值.     

高频数据下积分波动率矩阵的伪似然估计、预测及应用

研究目标:利用高频数据准确估计和预测高维积分波动率矩阵,并将矩阵的预测值应用于资产投资组合的构造中。研究方法:通过保留p×p维已实现波动率矩阵的特征向量,对积分波动率矩阵的特征值进行预测,本文将积分波动率矩阵的估计和预测问题转化为p个一维积分波动率的估计和预测问题。研究发现:对高维已实现波动率矩阵过于发散的特征值进行调整能够提高矩阵估计的准确性;对资产收益率的积分波动率矩阵建立动态模型可以提高矩阵预测的精度。研究创新:将高维矩阵的估计和预测问题转化为矩阵特征向量的估计以及一维特征值的估计和预测问题;基于高频数据并建立资产收益率积分波动率矩阵的动态模型提高了资产投资组合的样本外表现。研究价值:本文提出的积分波动率矩阵估计和预测方法能够保证矩阵估计值和预测值的正定性;本文的预测方法能够提高矩阵的预测精度,能够在复杂的金融市场中构造低风险的资产组合。     

中观交通仿真建模关键问题分析及应用研究

首先介绍了三种典型的中观仿真模型:INTEGRATION、DYNASMART和DynaMIT,并进行了对比分析;在此基础上,提出了中观仿真建模的三个关键问题,分别是:动态OD估计、动态交通分配和动态交通流参数标定;最后,选取INTEGRATION为研究对象,分析了奥运会开幕式期间在实施交通需求控制和铺设专用道策略之后,奥运大家庭车辆的运行情况,说明中观仿真模型在城市交通管理方面的应用效果.     

基于TransCAD的BPR路阻函数对OD反推影响分析

随着交通信息采集技术的发展,路段流量的获取变得越来越容易。因此,通过路段观测流量来反推OD矩阵的方法成为一种经济实用的方法。本文介绍了基于TransCAD软件OD矩阵反推的方法,并结合苏州市部分特定路网建立了路网模型。运用单因素敏感性分析法,结合选定的均方根误差、相对误差以及模态置信准则(MAC)等三个评价指标,分析BPR路阻函数参数α和β对OD矩阵反推结果精度的影响。在反推过程中建议使用随机用户平衡分配法(SUE),并给出α和β的建议取值范围,可为提高利用TransCAD软件进行OD矩阵反推精度提供参考。     

铁路路网系统运输能力的新算法研究

从系统理论和运输需求的概念出发,分析了国内外铁路路网运输能力的研究成果。从OD流矩阵的角度提出了铁路路网系统运输能力的概念,在此基础上构建了铁路路网系统运输能力的双层规划计算模型,该模型已最大化OD流矩阵乘数从为上层规划模型的目标,以最小化广义运输费用为下层模型目标,并提供了基于Lingo软件和Double-sweep算法的实用解法。最后,以一个铁路路网为例,用模型进行了求解,得出了路网最大能力及实现此最大能力的车流径路,并指出了进一步研究的方向。     

铁路路网系统运输能力的新算法研究

从系统理论和运输需求的概念出发,分析了国内外铁路路网运输能力的研究成果.从OD流矩阵的角度提出了铁路路网系统运输能力的概念,在此基础上构建了铁路路网系统运输能力的双层规划计算模型,该模型已最大化OD流矩阵乘数从为上层规划模型的目标,以最小化广义运输费用为下层模型目标,并提供了基于Lingo软件和Double-sweep算法的实用解法.最后,以一个铁路路网为例,用模型进行了求解,得出了路网最大能力及实现此最大能力的车流径路,并指出了进一步研究的方向.     

Development in Information and Communications Technology (ICT) Statistics at the Australian Bureau of Statistics

This paper outlines the ICT statistical developments that the ABS has undertaken over recent years. These developments have been on both the supply side (ICT industry) and the demand side (use of IT by sector). The content of ABS ICT surveys has changed significantly over the last few years and are expected to develop further in line with industry changes and emerging policy needs.
Recent developments in household collections have been the inclusion of IT use questions in the 2001 Census of Population and Housing and in various ABS social surveys such as Children's Participation in Culture and Leisure Activities. Annual business IT use surveys are now conducted and include topics such as Internet commerce and IT security. Biennial ICT industry surveys are conducted to provide data on ICT production, imports and exports, ICT industry employment, performance and structure information. An Internet activity survey is run every six months and provides regional Internet access details and infrastructure details on Internet service providers.
A major development for 2002–03 will be the compilation of an ICT satellite account. ABS intends to produce an ICT Information Development Plan to guide its future statistical development work in the ICT field.     

Value at Risk in the Suburbs: Eminent Domain and the Geographical Politics of the US Foreclosure Crisis

Several US counties and local governments have recently considered a novel solution to the foreclosure crisis. They plan to use eminent domain to compel the owners of mortgage debt—and specifically of private‐label mortgage‐backed securities—to sell the debt to the government at a price reflecting the loan's market value. The government would then restructure the debt and resell it to new investors. The plans are striking because—in contrast to both development‐driven eminent domain and the federal subprime bank bailout—they would force investors to assume asset devaluation and increased long‐term risk. Notably, the plans have emerged as an instance of financialization‐focused politics in suburbs and suburban cities of color, specifically majority‐black and ‐Latino/a suburbs. Local support for the plans, we argue, is rooted in the long‐term disinvestment of these ‘suburbs of exception', which became targets of subprime lending and eventually sites where the ‘financial exception' has been localized. But these demographic shifts, fragmentation and fiscal pressures have at the same time created a suburban political terrain in which the plans have gained their strongest political support.     

Towards a Theory of Serendipity: A Systematic Review and Conceptualization

Serendipity – the notion of making surprising and valuable discoveries – plays a major role in the success of individuals and organizations alike. Previous research has established the importance of serendipity and identified important individual- and organizational-level antecedents. However, the literature has been dispersed and the boundaries of the concept have been blurry, leading to a lack of conceptual clarity and structure, and thus limiting validity and managerial actionability. Based on a systematic literature review, I synthesize existing management-related research on serendipity and explicate the emergence and composition of serendipity in the organizational context. I first identify three necessary conditions that differentiate serendipity from related concepts such as luck or targeted innovation: agency, surprise, and value. Then, I draw from the literature on sensemaking, event-based theorizing, and quantum-based approaches to management to conceptualize the process of cultivating serendipity in the organizational context as a process of enabling potentiality and materialization, and develop a multi-level theory of (cultivating) serendipity. This conceptualization contributes to our collective understanding of how, why, and when (i.e., under what conditions) organizations can leverage the value in the unexpected, which opens up fruitful avenues for further research.     

Accountability of NGOs in Bangladesh A critical overview

NGOs in Bangladesh have been recognized as effective change agents in the socio-economic arena throughout the world. Their contributions in micro credit, non-formal education and primary health care are widely known. NGOs play a significant role in society. NGO accountability, as a result, has become a critical issue. NGO accountability in Bangladesh has been examined here in relation to patrons, clients and themselves. Of the three relationships only accountability to patrons is in a near satisfactory state. Accountability to clients is handicapped by lack of opportunities of beneficiaries to participate meaningfully in NGO policy making. Accountability to themselves is adversely affected due to the adherence to a strictly hierarchical system and the influence of founding and charismatic NGO leaders.     

Towards an Asian model of human resource management? A comparative analysis of China,Japan and South Korea

There has been much discussion regarding the possible decline and weakening of national systems of human resource management (HRM). Yet, culture and institutions are often cited as the major stumbling blocks to this outcome. Such constraints may dissipate in the analysis, particularly if ‘regional clusters’ are considered where geographic and cultural closeness and ‘openness’ to similar economic pressures exist. In such cases, it might be postulated that convergence in HRM will occur. We argue that China, Japan and South Korea represent such a cluster. This article examines these countries, to see if a degree of convergence is taking place and if it is towards an identifiable ‘Asian’ model of HRM. A model of change is presented that distinguishes between levels of occurrence and acceptance. Details of the development and practice of HRM in each country are then set out. The article ends with a discussion and implications section and a brief conclusion.     

Ansätze und Ergebnisse anglo-amerikanischer M&A-Forschung

Based on a review of established U.S. management journals (1995–2003), six schools of thought are identified within the Anglo-American M&;A research: “Capital Market”, “Principal/Agent”, “Industrial Organization”, “Organizational Behavior”, “Human Resources” and “Strategic Management”. The literature review shows that the definition of M&;A success, the methods applied, and insights from empirical research differ according to the respective school of thought. Empirical studies focus on the resource combinations of merger partners, the specific circumstances of merger negotiations, and on integration management as antecedents of merger performance. Unfortunately, empirical findings have not yet provided reliable explanations for M&;A success. Based on the current state of Anglo-American M&;A research, the authors discuss implications for business practice, identify research gaps, and propose areas for future research.     

Introduction of New Technology with a Sound Transition of the Input-Output Structure

We examine the general equilibrium repercussions associated with the introduction of new technologies, using the generalized Leontief system that allows technological substitutions. We show that an untested introduction of cost-increasing technologies in any industry may result in creating a non-productive technological structure that does not satisfy the Hawkins-Simon condition, following the autonomous dynamic adjustment process with structural transitions in the economic system. Therefore, we propose a practicable control scheme of introducing cost-increasing technologies that strictly avoids the creation of non-productive structures in all periods of structural transition, using the available information on the ex ante technological structure.     

The Creation of the Office for National Statistics

A new Office for National Statistics was created in the United Kingdom in 1996 following a series of developments designed to strengthen the relevance and integrity of statistics. This paper describes these fundamental changes and sets out a blueprint for future progress. It also sets current developments in the United Kingdom in an historical and international context.     

What helps? Women engineers' accounts of staying on

We have considerable understanding of the obstacles that women engineers encounter and the reasons that they leave the field, but we know less about what enables them to remain. Adopting an interpretivist approach, this article examines how a group of British women engineers in two FTSE 100 companies account for “staying on” in their male‐dominated work settings. We delineate four specific forms of help that facilitate women's retention in the field. We argue that exposure to help leads to women developing a habitus that enables them to continue working in engineering. To conclude, we draw on our findings to outline HR practices that will facilitate supportive relationships in the workplace and pave the way towards developing more positive organisational climates.     

论现代物流企业的发展观

物流业经过诸多年的发展目前已经成为最热门的行业之一,物流企业的注册数量也与日俱增,达到前所未有的规模。毋庸置疑,任何企业都希望自己迅速做强做大,并成为真正现代物流企业的典型代表,要实现这一目标一个首要问题就是要解决现代物流企业的发展观问题。