Hierarchical system identification of models for urban dynamics

A critical problem in urban modeling is the validation of system models and identification of system parameters within an assumed structure. This paper applies recent developments in system identification in hierarchical structure to identification of system parameters for two models of urban dynamics.     

Modeling the density variations of urban land uses with transportation network congestion

Perhaps the single most distinctive character of urban activity that distinguishes it from rural and regional activities is the intensive use of urban land. While the nature of density variations of urban land uses and their associated land rents are well understood, there have been few operational urban models that explicitly address the density variations of land uses. The paper presents a combined land use-transportation model, in which transportation congestion costs on networks of various transportation modes are simultaneously determined with the efficient intensity level of land uses. The procedure uses a nonlinear programming approach within the context of a multicommodity flow/input-output model.     

An EM algorithm for the estimation of parametric and nonparametric hierarchical nonlinear models

It is shown how to implement an EM algorithm for maximum likelihood estimation of hierarchical nonlinear models for data sets consisting of more than two levels of nesting. This upward–downward algorithm makes use of the conditional independence assumptions implied by the hierarchical model. It cannot only be used for the estimation of models with a parametric specification of the random effects, but also to extend the two-level nonparametric approach – sometimes referred to as latent class regression – to three or more levels. The proposed approach is illustrated with an empirical application.     

城市社区周边商业环境的特征与评价——基于北京市内7个社区的调查

在我国城市商业业态多元化、商业空间快速扩展并呈"两极化"发展的大趋势下,城市社区周边的商业已成为与居民日常生活密切相关的商业空间,而且伴随着城市居住的空间分异,不同类型的城市社区商业表现出明显的地域差异.论文基于北京市内7个社区周边商业环境的实地调查数据,比较分析了城市社区周边商业环境的现状特征,并将城市社区周边商业环境划分为2个尺度与3种类型.与此同时,采用层次分析法对城市社区周边商业环境进行了定量评价.     

城市出行信息环境分层规划方法

认为出行信息环境的服务水平是影响城市交通效率的重要因素之一,有效的出行信息传递能够显著提高路网的整体效率。系统分析了我国城市出行信息环境现状,在出行信息需求分析的基础上,建立了包含城市路网、交通方式与路线三个层面的出行信息环境分层规划方法,并提出了具体的出行信息环境优化对策。     

国内外城市群发展模式与发展经验探析

本文总结提炼出了国内外城市群的两大发展模式,重点阐析了国内外城市群形成发展中的主导经验,以期能为我们在城市群建设中有所借鉴。     

On the dynamics of industrial evolution

Recent ideas emerging from the Brussels school of non-equilibrium systems analysts are adapted to formulate some simple evolutionary models of a self-organizing industrial system. Certain forms of technological change are represented as structural fluctuations (innovative variations), which can result in quite different development paths for each industry. The chosen approach postulates a random element in the timing and location of industrial innovations, whereas the growth or survival of particular firms is still governed by economic and demographic constraints in the urban or regional marketplace. More complex models of industrial change, which allow for joint consideration of the demographic and industrial dimensions of social development over space and time, are also contemplated.     

A new economic geography model of central places

One of the most striking feature of the space-economy is that cities form a hierarchical system exhibiting some regularity in terms of their size and the array of goods they supply. In order to show how such a hierarchical system may emerge, we consider a model with monopolistically competitive markets for the industrial sectors. As transport costs steadily decrease from large values, the urban system formed by several small cities entails structural changes in that some cities expand at the expense of the others by attracting a growing number of industries. Beyond some threshold, some cities disappear from the space-economy. Such an evolution of the urban system describes fairly well what has been observed in various historical periods that have experienced major changes in transportation technologies and/or political unification.     

Hierarchical integration in production planning: Theory and practice

This paper discusses the issue of integrating various decision levels in hierarchical production planning systems. First the theory is briefly reviewed and then two case studies are presented. It is argued that it is not sufficient to have a good decision model at every level of the decision hierarchy. The different models should be carefully integrated. The potential problems resulting from a lack of integration are discussed. These problems are then illustrated in two case studies in order to be able to focus on actual managerial issues. It is shown how different decision levels supported by decision models were integrated in these two applications. Two important features are the crucial role of crossfunctional managerial committees in the integration process and the introduction of slack to avoid disaggregation problems.We do not claim to be exhaustive in presenting the problems related to integration nor do we claim that the solutions to the cases are the best possible ones. We do, however, hope that this paper motivates production managers to take a serious look at their hierarchical planning procedures.     

徐州都市圈城市体系结构分析

基于2005年统计数据,运用分形理论及GIS技术,从规模结构、空间结构、职能结构三方面,对徐州都市圈城市体系的结构进行分析。结果表明:徐州都市圈城市规模等级结构明显,城市首位度高,小城市发展滞后;城镇密度分布呈带状延伸的特征,空间结构呈较典型的港城"双核结构";城市职能结构单一,类型趋同,资源型城市比重大,属于工矿型城镇体系。最后提出优化徐州都市圈城市体系结构的对策和建议。     

中国城市增长的空间组织模式研究

本文借鉴发达国家城市增长与空间组织的最新理论,根据城市总体规划的实践,演绎出中国城市空间组织的三种典型模式,依次为单中心块聚式模式、主-次中心组团式模式和多中心网络(开敞)式模式.这对城市空间发展战略研究和城市总体布局规划具有重要参考价值.     

基于灰色关联度的城市低碳经济综合评价模型

从社会系统、经济系统、技术系统和环境系统四个方面构建了评价城市低碳经济发展的递阶层次型指标体系,提出了一种基于灰色关联度的城市低碳经济综合评价模型,对每个二级指标类内强关联性指标进行筛选,消除了冗余,减小了评价过程的复杂度。同时将主客观赋权法结合确定各指标的综合权重,提高了评价结果的准确度。以某省公布的各项指标数据进行验证,实例表明了该方法的合理性和有效性。     

School Quality and Real House Prices: Inter- and Intrametropolitan Effects

This study focuses on explaining variations in real constant-quality house prices in jurisdictions located in multiple MSAs. Using a hedonic house price framework, we test competing theories of house price determination. Using two variants of the random coefficients model, we find that public school quality has a very large impact on real constant-quality house prices. Our results suggest that capitalization of school quality differences occurs on a per lot basis rather than per square foot of land. Also important to the explanation of variations in house prices are variables derived from urban theory, such as distance to the CBD, and from the amenity literature, such as a community's crime rate, arts, and recreational opportunities     

论城市房屋拆迁中物权流转模型的构建及保护对策——兼评《国有土地上房屋征收与拆迁补偿条例》

拆迁问题引发的社会矛盾愈演愈烈,制度设计的缺陷难辞其咎.论文在抽离拆迁行为的基础上,构建公益性房屋拆迁模型与商业性房屋拆迁模型,并以物权的变动为线索,剖析现行拆迁制度,旨在对拆迁立法的完善提出更有针对性的建议,以规范相关物权的归属与保护;并对<国有土地上房屋征收与拆迁补偿条例>(征求意见稿)进行评析.     

试论城市地价动态变化与城市动态规划的互动关系

城市地价与城市规划是一种动态互动关系,城市规划及其实施引导城市地价的动态发展趋势,城市地价及其动态变化制约城市开发及其城市规划的实施,文章通过系统分析两者之间动态互动关系及作用机制,探讨城市动态规划编制、实施和管理过程中开展地价动态评估与论证的必要性和现实意义,并为基于城市规划的地价动态评估方法体系建立提供理论依据.     

Urban residential density and income

Spatial variations in income have not been adequately accounted for in urban density regressions. Estimating equations incorporating household income are derived in a monocentric urban model. The technique used also yields an estimate of the income elasticity of demand for housing, found to be less than one.     

Hierarchical models for independence structures of networks

We introduce a new family of network models, called hierarchical network models, that allow us to represent in an explicit manner the stochastic dependence among the dyads (random ties) of the network. In particular, each member of this family can be associated with a graphical model defining conditional independence clauses among the dyads of the network, called the dependency graph. Every network model with dyadic independence assumption can be generalized to construct members of this new family. Using this new framework, we generalize the Erdös–Rényi and the β models to create hierarchical Erdös–Rényi and β models. We describe various methods for parameter estimation, as well as simulation studies for models with sparse dependency graphs.     

Hierarchical Models for the Analysis of Likert Scales in Regression and Item Response Analysis

Appropriate modelling of Likert‐type items should account for the scale level and the specific role of the neutral middle category, which is present in most Likert‐type items that are in common use. Powerful hierarchical models that account for both aspects are proposed. To avoid biased estimates, the models separate the neutral category when modelling the effects of explanatory variables on the outcome. The main model that is propagated uses binary response models as building blocks in a hierarchical way. It has the advantage that it can be easily extended to include response style effects and non‐linear smooth effects of explanatory variables. By simple transformation of the data, available software for binary response variables can be used to fit the model. The proposed hierarchical model can be used to investigate the effects of covariates on single Likert‐type items and also for the analysis of a combination of items. For both cases, estimation tools are provided. The usefulness of the approach is illustrated by applying the methodology to a large data set.     

Application of Hierarchical Linear Models to Meta-Analysis: Study of the Monte Carlo Simulation on the Functioning of Traditional and Empirical-Bayes Effect Size

An empirical study and comparison is made of the functioning of the effect size proposed from the traditional meta-analytical points of view and the hierarchical linear models. These estimators are compared in bias, efficiency and robustness, via a Monte Carlo simulation. The results show the best behaviour of Empirical Bayes estimator (EB). This estimator shows a slightly biased behaviour compared with the traditional, although it is obviously more efficient and robust than the alternative traditionally used. Thus, it is empirically proved that the hierarchical linear models are an alternative to the traditional methods of meta-analytical synthesis.     

国外城市转型的趋势及经验借鉴

城市转型是城市发展道路及发展模式的重大变革。芝加哥、伦敦、新加坡等许多世界先进城市在自身发展的道路上都经历过城市转型的历程。本文概括了国外城市转型的四个基本趋势,即创建生态城市,打造智慧城市,建设文化城市,构建集约城市;简述了国外城市经济转型的三种主要模式,即以芝加哥为典型的产业多元化模式,以伦敦为代表的产业升级替代模式,以新加坡为典型的产业高端化模式;总结了国外在城市转型中的经验,以期对目前正处于经济转型期的我国城市提供一些有益的参考和借鉴。