Urban spatial pattern as self-organizing system: An empirical evaluation of firm location decisions in Cleveland–Akron PMSA,Ohio

Economic models of urban spatial patterns have largely ignored complexity as an attribute of urban systems. Complexity theorists on the other hand have not made sufficiently serious and sustained attempts to verify empirically the relevance of complex systems models for urban spatial patterns. This research bridges this gap by simulating the evolution of an urban employment pattern as a self-organizing complex system and seeking its empirical validation. It estimates the model’s parameters by using firm data aggregated to the level of municipalities in Cleveland-Akron Consolidated Metropolitan Statistical Area in Ohio. The interaction among four parameters, forces of attraction and dispersion and their respective rates of dissipation with distance, are modeled as a two-dimensional complex system. The research compares the states of the modeled system with empirical data to present viable methods for verification, calibration and validation of such models.

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Simple monopoly price theory in a spatial market

One of main conclusions drawn by prior studies is that in a spatial market, the shape of the demand function can fully determine whether one simple pricing policy is superior to another either on the basis of the firm’s preference or social desirability while there is one assumption that is generally stipulated, namely, that the fixed market area assumption under which the market area is exogenously determined and remains the same under alternative pricing policies. In order to fully understand the impact of a demand function, this paper attempts to reexamine the relative economic advantages between two simple spatial pricing policies in a world with variable market area, that is, the market area is endogenously determined the price charged. We show that the fixed market area assumption is valid only where demand is linear, but no longer holds where demand is nonlinear. Moreover, and more importantly, we show that in a world with variable market area, some conclusions drawn by prior studies on the relative economic benefits of two pricing policies cannot remain valid. The main conclusion of this paper is that even the relative economic benefits of two simple spatial pricing policies is concerned, the impact of economic space is significant.

钢筋混凝土现浇薄板变形裂缝的形成机理及其防治方法

钢筋混凝土现浇薄板 (ld 3 5>h >相似文献   

Regional labor markets in Finland: Adjustment to total versus region-specific shocks

This article analyses regional labor market adjustment in the Finnish provinces during 1976–2000. We investigate the inter-relations of employment, unemployment, labor force participation, and migration to see how a change in region-specific and total labor demand is adjusted. The analysis reveals that region-specific labor demand shocks adjust mainly via participation, whereas total shocks are adjusted by unemployment. The region-specific component of labor demand shock has shorter-lived effects on unemployment and participation, but its effect on employment is permanent. Conversely, total shocks leave no permanent effect. Migration is more important in the region-specific case where, after a few years, it acquires a large role in the adjustment process.     

Path-dependent processes and the emergence of the rank size rule

Many things in the natural world consist of an ever-larger number of ever-smaller pieces. This is called a fractal, which implies both the power law and rank size rule. Various models have been applied to explain the power law or ZipfRDER="0">s law in the distribution of city size. GibratRDER="0">s law proposes general and neat interpretations for this regularity in a city distribution, but the homogeneity assumption in GibratRDER="0">s law shows a disregard of the agglomeration effect that is essential in economic interpretation. The purpose of this paper is to examine the relation between the feature of increasing returns in the dynamic growth process and the property of power law in the static limiting distribution. We apply the path-dependent processes in Authur (2000) called nonlinear Polya processes to analyze the relation between the feature of agglomeration in the path-dependent processes and rank-size relations in the limiting distributions. The simulation result shows that the growth process with a diminishing returnsRDER="0"> agglomeration economy or a bounded increasing returnsRDER="0"> agglomeration economy converges to a stable limiting distribution with a constant expected proportion. On the contrary, the growth process with an unbounded increasing returnsRDER="0"> agglomeration economy could generate a fractal kind of limiting distribution with a time variant expected value. The unbounded increasing returnsRDER="0"> agglomeration economy is the necessary condition to generate the rank size rule in the limiting distribution. Given the assumption of agglomeration economies and robust evidence of ZipfRDER="0">s in city distribution, our result suggests that agglomeration benefits increase without a ceiling as residents are added to the city. The increase of the diseconomies of agglomeration (congestion, pollution, crime, etc.) is not too severe to confine the limiting level of the net agglomeration effect.The author acknowledges the National Science Council for the financial support on the study (Project NSC 91–2415-H-004–016).Received: July 2002 / Accepted: March 2003     

A note on export openness and regional wage disparity in Central and Eastern Europe

This paper extends the empirical literature on the effects of trade liberalization on regional disparities within a country. Studying the case of the Central and Eastern European countries, we find significant convergence of real wages in Poland and Bulgaria, only. Furthermore, countries with a faster growing export openness in the period 1991–1998 experienced larger increases in their regional disparities. Especially, intermediate goods trade seems to have been a main driving force. Our estimates suggest that the long run impact of rising intermediate goods export openness in the last decade was a 23% increase in the average economyRDER="0">s variance of real wages.Received: December 2002/Accepted: January 2004The authors are grateful to two anonymous referees for their helpful suggestions.     

重庆市油烟污染现状调查及原因分析和防治对策

餐饮业油烟污染扰民问题一直是近年来重庆市民投诉的热点。为确切了解目前重庆市油烟污染现状及市民对油烟污染问题的反映,为重庆市环保决策提供科学依据,调查了不同性别、不同年龄和不同居住环境的重庆市民对油烟污染和其他环境污染问题的认识以及重庆市民对油烟污染的投诉情况。结果表明,油烟污染是除大气污染和噪声污染以外影响重庆市民生活的最大的污染类型,不同性别、不同年龄和不同居住环境的人们对油烟污染影响的感受不同。最后分析探讨了重庆市油烟污染问题难以有效解决的原因,并提出了治理油烟污染的合理化建议。     

Applying social network analysis in economic geography: framing some key analytic issues

Social network analysis attracts increasing attention in economic geography. We claim social network analysis is a promising tool for empirically investigating the structure and evolution of inter-organizational interaction and knowledge flows within and across regions. However, the potential of the application of network methodology to regional issues is far from exhausted. The aim of our paper is twofold. The first objective is to shed light on the untapped potential of social network analysis techniques in economic geography: we set out some theoretical challenges concerning the static and dynamic analysis of networks in geography. Basically, we claim that network analysis has a huge potential to enrich the literature on clusters, regional innovation systems and knowledge spillovers. The second objective is to describe how these challenges can be met through the application of network analysis techniques, using primary (survey) and secondary (patent) data. We argue that the choice between these two types of data has strong implications for the type of research questions that can be dealt with in economic geography, such as the feasibility of dynamic network analysis.     

工业用钢筋砼贮池的防腐蚀处理

本文针对工业上钢筋砼贮池易受腐蚀的情况,提出了在结构和防腐材料等方面的处理方法。     

Subsidies and welfare maximization tradeoffs in bus transit systems

Under a maximum welfare objective, a fixed route bus system and a flexible route bus system are optimized subject to various financial constraints. For each bus system, the decision variables including fare, headway, route spacing, and service zone area are optimally solved to analyze unconstrained, break-even and subsidy cases. Numerical results and sensitivity analysis are presented in the paper. From the numerical evaluation, it is shown that the effects of subsidies on welfare are quite different for a fixed route bus system versus a flexible route bus system. For the fixed route bus system, the optimal welfare curve is very flat over a wide range of subsidies. However, for the flexible route bus system, the break-even constraint causes a large loss in the social welfare. Thus, with the welfare maximization objective, the break-even policy or low transit subsidy policy may be preferable for the fixed route bus system, but not for the flexible route bus system. The results derived from this study can support effective decision-making on bus transit systems in areas that may experience significant shifts in residential density, as well as geographic or physical changes in their street networks. This paper was presented at the 46th annual meeting of Western Regional Science Association in Newport Beach, California, 21–24 February 2007.