The Location of Hubs in Networks

这项研究将整合和概括设施间流量在选址问题中的作用的相互矛盾的观点。一个压倒一切的问题是“为什么构建一个模型来表示现实中如此频繁发生的现象如此困难？”“许多研究工作都致力于开发相互依赖的枢纽设施的位置模型。在这些问题中，由于不理解的原因，有时会遇到非整数解。一些程序产生了高度分数的解决方案，虽然其他人表现得更好。 回答这一问题很重要，因为从理论和实践的角度来看，设施之间的相互依赖是空间经济中集群/聚集的一个关键来源。本研究将完善枢纽系统的数学模型，综合近年来的大量文献，运用最优化法、数学规划法、网络分析法等方法，对经济地理学的基本问题--互动设施的最佳选址问题进行科学研究。对增进知识的潜在影响如下。在相互依赖的活动中，区位模型的失败是理论家们的一个主要难题：事实上，如果仔细、创造性地研究这些问题在轴辐式网络中的表现方式，这一点可能会得到修复。集线器充当地理上分散的节点之间交互的管道。在飞机、卡车、管道或网络连接的容量限制内，额外单位流量的边际成本很小（可能接近于零）。此外，如果更大的流量由更高容量的基础设施处理，则可变成本更低。因此，运输服务提供者通过捆绑流量降低了平均单位成本。

This research will integrate and generalize conflicting views of the role of inter-facility flow in location problems. An over-riding question is 'why is it so difficult to construct a model to represent a phenomenon that occurs so frequently in reality?' Much research effort has been devoted to developing models for the location of interdependent hub facilities. In these problems, for reasons that are not understood, non-integer solutions are sometimes encountered. Some procedures have produced highly fractional solutions, although others have fared better. It is important to answer this question because, for theoretical and practical purposes, interdependence between facilities is a crucial source of clustering/agglomeration in the space economy. The research will refine mathematical models of hub systems, thereby integrating a wide range of recent literature in an effort to enhance scientific understanding of a fundamental problem in economic geography, namely the optimal location of interactive facilities.Methods to be employed include optimization, mathematical programming, and network analysis. The potential impact on advancing knowledge is as follows. The failure of location models for the case of interdependent activities is a major puzzle for theorists: this may in fact be repaired as a result of a careful, creative examination of the way in which these issues play out in the case of hub and spoke networks. Hubs serve as conduits for interactions between geographically dispersed nodes. Within the capacity limits of aircraft, trucks, pipelines, or network links, the marginal cost of an extra unit of flow is small (perhaps close to zero). Furthermore, there are lower variable costs where greater flows are handled by higher capacity infrastructure. Thus, providers of transportation services reduce their average unit costs by bundling flows.