试论环渤海物流网络的形成与运作

在简述物流发展背景与研究现状的基础上,作者界定了物流网络的概念与研究地域的范围,并且分析了环渤海物流网络的构成。同时作者仔细探讨了环渤海物流网络的形成机制和运作模式,通过分析,作者认为网络轮廓-海陆地域形状、网络节点-城市、网络联线-运输通道、网络能量-区域经济和运作主体-物流企业等五个要素共同作用而形成了物流网络,其运作由运作模块、驱动模块和调控模块组成。最后作者提出了相应的发展对策。     

Multiple Allocation Hub Location Model with Fixed Arc Costs

This article formulates a model to analyze the role of fixed costs in the design of optimal transportation hub networks. The primary purpose of this article is to better model costs in hub networks, an issue that has attracted considerable attention. This article allows particular versions of hub networks to emerge from the cost structure, rather than by imposing a rigid predefined connectivity protocol. The article integrates modeling approaches from an environmental hub location model with the three‐index formulation of Ernst and Krishnamoorthy to produce a hub location model with fixed and variable costs for all arcs. Our goal is to demonstrate how the inclusion of a richer cost model in transportation hub location can generate a wide range of different network types, depending on the relative magnitudes of the cost elements. While the existence of special case network solutions is well known and has been exploited in optimization, the current research provides added insight to the cost of flow in a more, or less, connected hub network. Eight fundamental prototype networks are derived as special cases, and some additional unanticipated network types also emerge. The results are illustrated with a standard CAB25 data set.     

Curbing Optimism Bias and Strategic Misrepresentation in Planning: Reference Class Forecasting in Practice

The American Planning Association recently endorsed a new forecasting method called reference class forecasting, which is based on theories of planning and decision-making that won the 2002 Nobel prize in economics. This paper details the method and describes the first instance of reference class forecasting in planning practice. First, the paper documents that inaccurate projections of costs, demand, and other impacts of plans are a major problem in planning. Second, the paper explains inaccuracy in terms of optimism bias and strategic misrepresentation. Third, the theoretical basis is presented for reference class forecasting, which achieves accuracy in projections by basing them on actual performance in a reference class of comparable actions and thereby bypassing both optimism bias and strategic misrepresentation. Fourth, the paper presents the first case of practical reference class forecasting, which concerns cost projections for planning of large transportation infrastructure investments in the UK, including the Edinburgh Tram and London's £15 billion Crossrail project. Finally, potentials for and barriers to reference class forecasting are assessed.     

Finding mobility: women negotiating fear and violence in Mexico City’s public transit system

Feminists have long known that a woman’s confidence, sense of possibility, aspirations, and personal growth depend on their ability to be mobile. Yet gender-based violence and sexual harassment against women commuters greatly limit those freedoms. How then should cities adapt in order increase women’s equal access to mobility? To address this question, this article looks at the case of Mexico City, investigating how women pursue mobility despite hostile and violent conditions that immobilize them. Based on women’s testimonies, comments made on online debate forums, and surveys among women commuters in Mexico City, this article maps the ways women cope with violence and harassment on public transportation. The analysis also pays particular attention to how women’s coping strategies are restructured through state interventions, including women-only transportation. The data reveals that gender-based violence in Mexico City’s public transportation limits women’s mobility and reinforces gender inequality. It also shows, however, that under the right circumstances women-only transportation can be used as a place to create a rights-based movement. The article concludes that Mexico City is an example where women-only transportation has played a role in changing the traditional gender norms which have reinforced violence against women commuters.     

Modeling the Impact of Business-to-Business Electronic Commerce on the Organization of the Logistics Industry

In this article, we analyze patterns and recent trends of the logistics industry with specific emphasis on the impact of business-to-business (B-to-B) electronic commerce on its industrial organization. From this conceptualization, we develop an optimization-based logistics model comprising two interlinked networks representing commodity flow and information flow, respectively. The model is operationalized using Monte Carlo simulation to highlight possible scenarios of logistics industry changes in response to the use of B-to-B e-commerce. Through this endeavor, we examine how new technologies affect the cost of information and transportation transactions in the logistics industry.     

Forecasting in a Small and Unstable Regional Economy Using Regime Shifting Models: The Case of Extremadura

We consider forecasting in a small and unstable regional economy subject to structural breaks. In this context, we work with two types of regime‐shifting databased models using cointegration theory. The objective of the present work is to analyze the out‐of‐sample forecasting performance of the two approaches used to construct a short‐term regional econometric model: stochastic and deterministic time varying parameters models. The forecasting experiments will be illustrated by specifying, and estimating an econometric model for Extremadura, a small and unstable region in southwestern Spain.     

基于综合可达性的北京城市增长模拟与管控模式优化

社会经济活动的空间重构与交通设施配置息息相关,可达性成为优化城市空间结构,调控城市空间开发的重要手段。在以矢栅一体化的综合可达性测度并构建城市增长模型的基础上,对北京城市增长进行了成功模拟,透视了基于综合可达性导向发展模式的基本特征与主要问题,并提出了基于综合可达性的城市增长调控模式优化方案。研究发现：①城市增长密集发生在建成区周围可达性优越的区域,随着与城市中心的距离增加,城市增长的概率降低,反映了北京单中心的城市发展模式;②受城市规划与交通设施规划失调影响,可达性提升程度越大的区域并不一定带来更高的城市增长开发概率,严重削弱了可达性对城市增长的引导作用;③基于综合可达性的城市增长调控模式的优化方案,要以交通设施规划为基础,并合理耦合空间规划,才能更为有效地引导城市空间良性增长并预防规划失效。基于综合可达性的城市增长模型建立与调控模式优化方案的提出,对于确立与提升交通引导城市增长的基础性地位,优化城市空间结构具有重要的理论和现实意义。     

The Pickup Problem: Consumers' Locational Preferences in Flow Interception

This article addresses the pickup problem , wherein patrons briefly interrupt their predetermined journeys to obtain a simple good, such as fast food or a video, and then resume their journeys. This is a problem from the class known as the flow-interception location problems. Traditional flow-interception location models (FILMs) are used to select service locations such that the intercepted flows are maximized. In these traditional models, only flow quantities are considered; these models do not consider where a pickup is made in a journey. However, in the real world, consumers often wish to obtain a product or service at or near a specific location along their trips. The pickup model (PUP) proposed here considers consumers' locational preferences, providing a much broader, more realistic approach than FILM (a special case of PUP) to problems in the private and public sectors. By considering which patrons are served where, PUP transforms the FILM into a flow-interception location-allocation model, providing a fruitful garden for further research. Geographic information systems and optimization engines are integrated to investigate the PUP model in real-world transportation systems. Reported findings demonstrate that the optimal locations identified by traditional models arise solely from network flow structure, whereas the optimal locations identified by PUP result from trade-offs between network flow structure and the importance of proximity to preferred locations. One important discovery is that PUP solutions are superior to those of traditional FILMs if consumers have locational preferences. Up-to-date, real-world transportation networks provide a realistic test-bed for this and other models of the flow-interception type.     

再论环渤海港口运输体系的建设与布局

环渤海地区已经成为我国的发展热点,其中环渤海港口运输体系有着重要作用和地位。本文在论述环渤海港口运输体系发展背景的基础上,探讨了环渤海港口运输体系自"九五计划"以来的发展状况和目前存在的问题,在论述发展现状时注意与1992年的比较,而存在问题有:①港口运量不足,港口生产能力过剩;②缺乏总体规划和宏观调控,港口之间缺乏合理的分工和协作;③三足鼎立的集装箱枢纽港建设局面;④港口运输体系信息化发展速度慢,技术手段落后等。最后就港口运输体系建设与布局的提出了进行总体规划、建设集装箱枢纽港、建设港口物流平台、发展陆桥经济、提高软环境建设等具体的建议和措施。     

MARKET DEFINITION AND ASSESSING THE COMPETITIVE RELATIONSHIP BETWEEN RAIL AND TRUCK TRANSPORTATION*

ABSTRACT. In this paper we develop a method for establishing market definition in studies of intermodal competition. We employ the proposed method in a transportation model that yields estimates of the substitutability between truck and rail services for the transport of fresh fruits and vegetables. The model includes the produce being shipped as an input into the production of delivered produce. Our results demonstrate that fairly disaggregate market definitions are required to characterize adequately the intermodal substitution possibilities of interest. While disaggregate data are required for econometric estimation of the cost function, it is essential that elasticities be calculated at a disaggregate level as well. The elasticities reported are larger than reported in earlier work and provide strong evidence of vigorous intermodal competition in produce transportation markets.     

高速铁路对节点城市旅游业发展的影响研究——以西安市为例

高速铁路的的时空压缩优势有效的提高了节点城市的可达性,扩展了客源范围,必将对旅游产业的供给水平产生影响。本文以西安市作为实证对象,首先,通过灰色关联度和引力测度,说明高速铁路的建设对西安旅游产业产生的重要影响。据此,结合其他高铁节点城市的发展经验和国内外高铁与旅游融合发展的经验,本文着重探讨了高铁影响下西安旅游空间结构演进、旅游商业模式创新和旅游公共服务体系完善的路径,并提出了相应的对策和建议。     

Aggregation of Regional Economic Time Series with Different Spatial Correlation Structures. 具有不同空间相关结构的区域经济时间序列集成

In this article, we compare the relative efficiency of different forecasting methods of space‐time series when variables are spatially and temporally correlated. We consider two cases: (1) univariate forecasting (i.e., a space‐time series aggregated into a single time series) and (2) the more general instance of multivariate forecasting (i.e., a space‐time series aggregated into a coarser spatial partition). We extend the results in the literature by including the consideration of larger datasets and the treatment of edge effects and of negative spatial correlation. We first introduce a statistical framework based on the space‐time autoregressive class of random field models, which constitutes the basis of our simulation study, and we present the various alternative forecasting methods considered in the simulation. We then present the results of a Monte Carlo study related to univariate forecasting. In order to allow a comparison with the findings of Giacomini and Granger (2004), we consider the same forecasting strategies and the same combinations of the parameter values used there, but with a larger parametric set. Finally, we extend our analysis to the case of multivariate forecasting. The outcomes obtained provide operational suggestions about how to choose between alternative forecasting methods in empirical circumstances.     

Cournot Retail Chains

In this paper a model of spatial Cournot competition among retail firms is devised and used to assess the effect of a variety of structural factors on retail prices and profits. The model illustrates the spatial chain of interaction that firms must anticipate to reach equilibrium when organized in chains or as independents. It shows the sensitivity of price to the location of stores, the number of stores per location, and transportation cost.     

A ROBUST APPROACH TO PREDICTING FLUCTUATIONS IN STATE-LEVEL EMPLOYMENT GROWTH*

ABSTRACT. Economic forecasting models are famous for performing well over short time periods and then suffering rapidly deteriorating performance when economic conditions change. This behavior makes composite forecasting models valuable in situations where large forecast errors cause considerable losses. A composite forecasting model for state-level employment is proposed here. This method is designed to protect state budget processes by producing robust forecasts of changes in employment and the related revenue collections. An application to Georgia nonagricultural employment is presented which demonstrates the benefits of this technique. The example shows that the method can forecast such series accurately without the forecaster having to choose in advance a single model specification to all economic conditions.     

Geography Today

In this article, reprinted from the weekly Nedelya [1965, No. 38], the author challenges the view that geography has outlived its usefulness. He sees a broad field of research and applied activity not only in the cataloguing of geographic facts in a ready form suitable for use by other disciplines, but also in the forecasting of changes in the natural environment as a result of economic development plans.     

A Spatial Prior for Bayesian Vector Autoregressive Models

In this paper we develop a Bayesian prior motivated by cross-sectional spatial autoregressive models for use in time-series vector autoregressive forecasting involving spatial variables. We compare forecast accuracy of the proposed spatial prior to that from a vector autoregressive model relying on the Minnesota prior and find a significant improvement. In addition to a spatially motivated prior variance as in LeSage and Pan (1995) we develop a set of prior means based on spatial contiguity. A Theil-Goldberger estimator may be used for the proposed model making it easy to implement.     

Travel-Time Constraints on Destination-Choice Sets

The importance of travel-time constraints in spatial choice is widely recognized in the literature of geography and related disciplines, but little work has been done toward developing operational models of spatial choice wherein these constraints and their effects are made explicit. The purpose of the paper is to test the accuracy of predictions produced by a destination choice model that does not take explicit account of travel constraints under the assumption that observed choices are made from choice sets delineated by a constraint of maximum travel time. Observed choices are generated by simulation from a new random utility model consistent with the constrained nature of individual choice sets. Results show that the characteristics of constraints are a decisive factor in the accuracy of the unconstrained choice model. Choice probabilities of the constrained reality are predicted with a reasonably good accuracy in some instances, but predictions are less impressive, and even poor, in many others.     

基于APSO—SVR的山岳风景区短期客流量预测

根据山岳风景区短期客流量小样本、非线性等特征,本文提出基于自适应粒子群算法（Adaptive Particle Swarm Optimization,APSO）的支持向量回归（Support Vector Regression,SVR）模型,融合SVR处理小样本、非线性预测特性和APSO优化SVR参数的能力对山岳风景区短期客流量进行预测。来自山岳风景区黄山2008年～2011年暑期相关日数据的验证结果表明：与PSO—SVR、GA—SVR和BPNN等模型相比,APSO。SVR模型的预测准确性更高、误差更小,是进行山岳风景区短期客流量预测的有效工具。     

Smart growth strategies,transportation and urban sprawl: simulated futures for Hamilton,Ontario

North American cities have undergone dramatic changes over the last century. Locations that were once inconvenient have become accessible through extensive road networks leading to population decentralization from the traditional urban centre to suburbia, creating polycentric sprawls from once monocentric communities. Hamilton, Ontario is one such city. The decentralization and urban decline of the city is widely attributed to sprawling development. This change in the sociospatial structure creates challenges for transportation planners as we see greater automobile dependency, greater commuting distances and increased congestion. Smart growth policies such as urban residential intensification (URI) aim to increase population densities in the urban core. This exploratory study estimates the benefits of such policies from a transportation aspect. It is predicted that the City of Hamilton will experience household growth of approximately 80,000 households over the period 2005–2031. Using IMULATE, an integrated urban transportation and land‐use model, a variety of development scenarios model this anticipated growth. Changes in vehicular emissions, traffic congestion and energy consumption as a result of URI are examined. Models of the land‐use/transportation relationship demonstrate how increasing population densities within a city's urban centre drastically reduce congestion, emissions and gasoline consumption.     

城市化进程中交通公平的研究进展

在系统分析城市化进程中交通公平内涵的基础上,从弱势群体与社会排斥、交通公平评估与改善策略等方面,梳理交通公平的相关研究成果。结果表明,当前城市交通公平性研究还需从以下几个方面进行完善:交通公平内涵应更加注重改善快速城市化地区居民群体的出行环境;系统分析快速城市化进程中交通公平的演化模式,改善交通公平的基本测度方法;构建交通公平评估的空间分析方法,从经济成本可达性角度剖析交通公平性;关注快速城市化地区交通公平的改善策略,提出可操作性的交通公平优化方法。