The core-periphery model: A note on the existence and uniqueness of short-run equilibrium

We consider the core-periphery model [P. Krugman, Increasing returns and economic geography, Journal of Political Economy 199 (1) (1991) 483–499]. The nature and stability of the possible steady states of the model have been made progressively precise; [M. Fujita, P. Krugman, A. Venables, The Spatial Economy. Cities, Regions and International Trade, MIT Press, Cambridge, 1999; R. Baldwin, R. Forslid, Ph. Martin, G. Ottaviano, F. Robert-Nicoud, Economic Geography and Public Policy, Princeton Univ. Press, 2003]. In that model as well as in all the new economic geography models that have been derived from it, the short-run (instantaneous) equilibrium is implicitly determined by the current labor distribution across regions. The numerical computations used so far to determine the short-run equilibrium, tend to suggest its existence. In this paper, an existence and uniqueness proof of short-run equilibrium is provided.     

Economic geography with tariff competition

A simple two-country model of economic geography is constructed in order to examine the effect of tariff competition on the spatial distribution of manufacturing activities as well as on welfare. We show that when the transport cost is small, tariff competition with firm migration leads to a core-periphery economy, where one of the two countries imposes no tariff in Nash equilibrium. We also show that when the transport cost is sufficiently large, both countries impose a positive tariff, which decreases the welfare of both countries.     

系统动力学在项目管理中的应用

针对传统项目管理方法在宏观控制方面存在的不足,分析项目管理的特点,依据系统动力学原理,结合项目动态系统的特征,建立了一个系统动力学模型.它更侧重于项目的宏观管理,侧重于对难以准确量化的复杂因素的分析,使项目管理更加科学化.     

Economic Growth in Transition

This paper sets the contributions to this issue in the context of a large and rapidly growing literature. It argues, on theoretical and empirical grounds, that future research should focus on transitional growth dynamics.     

Escape dynamics and equilibria selection by iterative cycle decomposition

This paper explores the medium-run behaviour of bounded rational players in repeatedly played games when they occasionally experiment or make mistakes. The formal analysis introduces a hierarchical structure of limit sets to characterize the most possible medium-run behaviour over gradually increased time intervals. The paper refines the notion of stochastic stability and offers a precise measure of the speed at which stochastically stable equilibria occur. Finally, the paper applies the results to a 3×3 symmetric game of Young (1993).     

融通仓模式在解决供应链资金约束问题中的应用

应用系统动力学建立一个由制造商、分销商、零售商和顾客组成的供应链系统，考虑当其中一个节点企业面临资金约束时，对整个供应链绩效的影响，并通过引入“融通仓”的运作模式，提出解决供应链中资金约束问题的一种可行方案。     

投资者信念异质性和适应性对股市价格的影响

考察了异质性信念、具有适应性的交易者相互作用下股市价格行为。通过数字模拟,分析实际市场上常用的价值分析和技术分析策略对价格动力学的作用,说明不同参数对价格行为的影响。     

基于产业集群的城市化动力机制研究

产业集群和城市化的内涵都是要素的聚集,二者存在很重要的内在联系。产业集群是城市化发展的重要载体,集群创新是产业结构升级的重要动力。文章从城市化动力机制方面阐述了产业集群对城市化的巨大推动作用,简要介绍我国产业集群的现实状况及存在的问题,提出加强产业集群发展以促进城市化的具体建议。     

南京市城市住房需求的系统动态学分析

目前，对住房需求问题的研究尚缺乏一种全面的、系统的和定量的方法。以南京市为例，通过对住房现实系统的分析，建立城市住房需求的系统动态学模型，并进行相关的模拟实验。     

电子琴键上的情感-数字评价指标研究

电子琴的手感和力度一直以来都是研究者和使用者所关心的内容。电子琴琴键的力度变化可以表现不同的情感。现今所有的电子琴生产商都在以自己的标准来进行生产。对手感和力度的评价指标是需要统一的。就电子琴手感和力度部分,提出了两个指标。     

Analysing tax evasion dynamics via the Ising model

We develop a model of tax evasion based on the Ising model. We augment the model using an appropriate enforcement mechanism that may allow policy makers to curb tax evasion. With a certain probability tax evaders are subject to an audit. If they get caught they behave honestly for a certain number of periods. Simulating the model for a range of parameter combinations, we show that tax evasion may be controlled effectively by using punishment as an enforcement mechanism.     

电子商务退货物流动态行为分析

采用系统动力学的方法构建了一个基于电子商务平台的退货模型,分析了退货政策与电子商务企业的各个运营指标之间的定量关系,并运用Vensim PLE软件进行仿真实验。研究结果表明:1退货政策宽松度越高,退货率和销售率都会相对上升,这与现实相符;2当网络零售商采取有时间限制的退货策略时,如果其退货比例和业内基本一致,其可以通过提供较宽松的退货政策来提高销售量。     

港口竞争力的系统动力学分析

现今港口之间的竞争日趋激烈,提升港口的国际竞争力才能使其生存和发展。为此,文中在对影响港口的主要因素进行分析的基础上,运用系统动力学的方法分析了主要因素之间的因果关系,并建立了系统仿真流图,为港口的发展决策提供了理论依据和可以借鉴的方法。     

区域物流园区规模与效率关系研究

从宏观经济运行角度,运用系统动力学方法建立了物流园区建设规模和国民经济运行的反馈模型,进行了三个方案的模拟,并以南京市为例进行验证,以求在区域层面上探寻物流园区建设规模和国民经济发展的关系,探索物流园区发展战略研究的新思路。     

Bifurcations in regional migration dynamics

The tomahawk bifurcation is used by Fujita et al. [Fujita, M., Krugman P., Venables A.J., 1999, The Spatial Economy: Cities, Regions, and International Trade, MIT Press: Cambridge, MA.] in a model with two regions to explain the formation of a core–periphery urban pattern from an initial uniform distribution. Baldwin et al. [Baldwin, R., Forslid, R., Martin, P., Ottaviano, G.I.P., Robert-Nicoud, F., 2003, Economic Geography and Public Policy, Princeton University Press: Princeton, NJ.] show that the tomahawk bifurcation disappears when the two regions have an uneven population of immobile agricultural workers. Thus, the appearance of this type of bifurcation is the result of assumed exogenous model symmetry. We provide a general analysis in a regional model of the class of bifurcations that have crossing equilibrium loci, including the tomahawk bifurcation, by examining arbitrary smooth parameter paths in a higher dimensional parameter space. We find that, in a parameter space satisfying a mild rank condition, generically in all parameter paths this class of bifurcations does not appear. In other words, conclusions drawn from the use of this bifurcation to generate a core–periphery pattern are not robust.