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.     

Extensions to the Hub Location Problem: Formulations and Numerical Examples

Although a tremendous amount of analytical research is being conducted on the hub location problem, few models exist that extend the number of characteristics found in actual hub-and-spoke networks. Four extensions are presented in this paper: (1) a capacitated network model; (2) a minimum threshold model; (3) a model that endogenously determines the number of open hubs for the network; and (4) a model that incorporates a flow-dependent cost function for the spokes as well as the interhub links. Both the capacitated and the minimum threshold models drop the assumption of a completely interconnected network commonly found in hub location models. Numerical results show that total network costs are often minimized by closing a few interhub links. The third extension is the first known hub location model to determine the optimal number of hubs based on the needs of the network. In this model, the number of open hubs depends on the distribution of flows in the network and how cost effectively the flows can be moved across the network. Previous models that endogenously determined the number of open hubs utilized a fixed cost for establishing each hub in order to limit the number of hubs in the network. The final extension recognizes the potential of all links to amalgamate flows and includes a separate flow-dependent cost function for the spokes in addition to the one for the interhub links. Numerical results are shown for all four models.     

空铁型综合交通枢纽地区空间演化特征——以上海虹桥枢纽为例

空铁型综合交通枢纽是将航空枢纽和高铁枢纽有机整合而形成的航空高铁一体化综合交通枢纽,具有较强的经济社会带动作用,对区域空间演化产生重要影响。根据复杂适应系统理论,选取上海虹桥综合交通枢纽地区为案例地,分析了空铁型综合交通枢纽地区地域空间演化阶段性特征。结果表明：交通枢纽地区地域系统通过多个适应性主体之间非线性相互作用形成复杂适应系统,该地域系统演化过程可划分为枢纽地区空间形成阶段、枢纽地区空间生长阶段和枢纽地区空间涌现阶段。上海虹桥综合交通枢纽地区在三个阶段特征不同,配套设施建设、要素集聚与流动、城市功能形成与发展、区域品牌形成等方面不断深化。研究有助于认知综合交通枢纽地域系统空间演化规律,为深化研究和实践发展提供科学借鉴。     

枢纽经济及其发展机制——以中国交通枢纽经济为例

枢纽经济是当前很多省份的重要区域发展战略,但是对枢纽经济内涵、发展机制等核心问题的讨论还不足以指导现实枢纽经济发展。文章构建并检验枢纽经济的发展机制,一方面界定枢纽经济内涵,从系统论的自组织和他组织视角使用区域循环累积因果模型推演出枢纽经济发展的四个阶段;另一方面以交通枢纽经济为例使用省级2007—2017面板数据检验主要变量的定量影响,并判断我国枢纽经济的当前所处阶段。主要结论:枢纽经济发展受经济系统自组织和政府他组织影响,是由初始变化形成阶段、次级强化形成阶段、产业竞合上升发展阶段、成熟阶段组成的循环累积因果过程;经验检验表明劳动力数量、公共基础设施配套、制度创新和技术水平显著影响枢纽经济;当前我国枢纽经济发展处于初始形成阶段,政府政策是触发关键;提高丝绸之路经济带沿线西部省份的枢纽数量和质量能有效拉动枢纽经济发展。     

Reliable p-Hub Location Problems in Telecommunication Networks

Hubs are critical elements of telecommunication and transportation networks because they play a vital role in mass traffic movement. The design of more reliable networks in hub-and-spoke systems is a critical issue because current networks, particularly many commercial Internet backbones, are quite vulnerable. In hub-and-spoke-type topologies, any malfunction at a hub may cause degradation of the entire network's ability to transfer flows. This article presents a new hub location problem, termed the reliable p-hub location problem , which focuses on maximizing network performance in terms of reliability by locating hubs for delivering flows among city nodes. Two submodels, the p-hub maximum reliability model and the p-hub mandatory dispersion model, are formulated. Based on hypothetical and empirical analyses using telecommunication networks in the United States, the relationship between network performance and hub facility locations is explored. The results from these models could give useful insights into telecommunication network design.     

Identifying Critical Facilities in Hub‐and‐Spoke Networks: A Hub Interdiction Median Problem

The hub location problem has been widely used in analyzing hub‐and‐spoke systems. The basic assumption is that a large number of demands exist to travel from origins to destinations via a set of intermediate transshipment nodes. These intermediate nodes can be lost, due to reasons such as natural disasters, outbreaks of disease, labor strikes, and intentional attacks. This article presents a hub interdiction median (HIM) problem. It can be used to identify the set of critical facilities in a hub‐and‐spoke system that, if lost, leads to the maximal disruption of the system's service. The new model is formulated using integer linear programming. Special constraints are constructed to account for origin‐to‐destination demand following the least‐cost route via the remaining hubs. Based on the HIM problem, two hub protection problems are defined that aim to minimize the system cost associated with the worst‐case facility loss. Computational experiment results are presented along with a discussion of possible future work. El problema de la ubicación de la central (hub) ha sido ampliamente analizado para el caso de los sistemas de sistemas radiales (hub‐and‐spoke). La presunción inicial es que existe un gran número de demandas que viajan desde puntos de origen hasta sus puntos de destino a través de un set de nodos intermedios de trasbordo. Estos nodos intermedios pueden perderse por diferentes motivos, como desastres naturales, brotes de enfermedades, huelgas de trabajadores, o ataques intencionales. Este artículo presenta un problema de tipo mediana de interdicción de hub, conocido como hub interdiction median‐HIM. Puede usarse para identificar un set de instalaciones críticas de un sistema tipo hub‐and‐spoke que, si se pierde, conduce a la máxima interrupción del servicio del sistema. El nuevo modelo se ha formulado utilizando programación entera lineal, (integer linear programming‐ILP). El modelo construye restricciones especiales para dar cuenta de la demanda de “origen‐a‐destino” (O‐D), siguiendo la ruta de menor costo, a través de los hubs restantes. Basándonos en el problema de HIM, se definen dos problemas de protección de hub que buscan minimizar el costo asociado al peor caso posible de pérdida de instalaciones. Se presentan además, resultados de experimentos computacionales, así como a una discusión sobre posibles futuros trabajos en la materia. 枢纽区位研究已广泛应用于中枢辐射型系统分析,其基本假设条件为起始点到目的地之间存在大量旅行需求的中间转运节点。但自然灾害、突发疾病、劳务罢工和蓄意攻击等因素可能导致中间转运节点的丧失。本文提出了一种枢纽封闭中心模型（HIM）,可用于识别中枢辐射型系统的重要节点,一旦这些节点丧失,将导致整个系统服务最大程度的瓦解。新模型通过整数线性规划公式建立。模型特殊约束条件的建立基于最小成本路径通过余下枢纽的花费来解释始发到目的地（ origin‐to‐destination）需求量。基于HIM问题,双枢纽保护问题被定义为旨在最小化系统花费及其与之关联的最坏情况下节点丢失问题。最后,根据计算的经验结果讨论未来可能深入的研究。     

全球海洋知识枢纽研究——以上海市为例

21世纪被联合国称为"海洋世纪",海洋已成为国际竞争的主要领域。随着实体物流的增加,货流对城市所带来的交通拥堵、环境污染等负面影响也日益显现。因此在上海大力建设国际航运中心过程中,要由以工业经济为基础的实体枢纽港建设向以知识经济为基础的虚体海洋知识枢纽转变。归纳了全球海洋知识枢纽的内涵、特征和服务范围,以伦敦、挪威、新加坡为三种类型,总结了发达国家建设海洋知识枢纽的经验和原则,提出上海建设全球海洋知识枢纽的战略选择,认为要以建设全球海洋知识枢纽为切入点,一方面要发展航运金融、海上保险等高端航运服务业,另一方面也可以利用雄厚的制造业基础和技术创新能力,大力发展海洋研发,鼓励船舶技术转让、技术开发和与之相关的船舶技术咨询、技术服务等。     

旅游集散地研究初探:整体性、转换机制、自身调节性——以结构主义地理学方法为研究视角

旅游集散地正随着区域旅游的发展,重要程度日益显现。文章基于结构主义人文地理学的研究方法,认为结构是决定区域旅游发展的关键因素,决定内核的是机制,而决定机制的是结构,文章在围绕皮亚杰认为的结构三特性:整体性、转换机制、自身调节性对一直以来关注较少的旅游集散地的形成和功能进行了分析后,提出了旅游集散地地位不应低于旅游目的地,越是高层次的区域,越发体现出旅游开发的结构效益。旅游集散地的建设要强调休闲功能,而不是观光功能,要强调服务价值,而不是资源价值。     

Interfacility Interaction in Models of Hub and Spoke Networks

Providers of transportation services may reduce their average unit costs by bundling flows and channeling them between hubs (also known as concentrators or routers). The resulting facility locations are interdependent because of the flows between them. This paper analyzes mathematical models of hub systems in an effort to enhance understanding of the optimal location of interactive facilities. The paper examines the behavior of solutions to several alternative models that require the location of a hub at either of two similar locations. A model employing a concave cost function favors the assembly of flows, penalizes fractional facility locations, and produces local minima that have integer facilities.     

Hub Location Problem with Allowed Routing between Nonhub Nodes

In this study, we relax one of the general assumptions in the hub location literature by allowing routed flows between nonhub nodes. In hub networks, different flows are consolidated and routed via collection, interhub, and distribution arcs. Due to consolidation, some flows travel long paths despite closeness of their origin and destination. In this study, we allow direct flows by penalizing by a scalar factor of original cost of transshipment between these arcs. We present mathematical models for median, center, and set covering versions of the problem for single‐ and multi‐allocation cases. We test the models with the CAB and TR data sets. We discuss the properties of established direct connections for different models by using another mathematical model where the number of direct flows is bounded and interpret the effect of changes in problem parameters.     

Activity Levels at Hub Facilities in Interacting Networks

Hubs are a special type of central facility which are designed to act as switching points for intemodal flows. For instance, a set of ten interacting cities might all be connected to one of two major hubs. All flows between the cities would then be routed via the hubs. There is an obvious saving in the number of routes necessary to interconnect the cities when hubs are utilized, with a concomitant high level of activity at the facilities. This paper takes a heuristic approach to the evaluation of networks and hub locations to find locally optimal designs. It is shown that minimization of transportation costs may require assignment of nodes to a facility other than the nearest. A discount on the interhub transportation costs promotes a wider spacing of facilities. In a system with several hubs, minimization of total hub usage tends to concentrate demand very heavily into one central facility.     

Race and hospitality: Allied troops of colour on the South African home front during the Second World War

Though often marginalised in histories of the Second World War, South Africa, in addition to contributing manpower and economic support to the Allied war effort, was a transport hub and a site for military training. Millions of Allied servicemen and women spent time in South Africa, which became an important node in both imperial and Allied wartime networks. Examining the varied experiences of Allied personnel of colour in South Africa, with a focus on the Māori battalion, this essay, working towards a transnational social history of the conflict, highlights the ways in which wartime hospitality both reflected and subverted ideologies and practices of racial segregation.     

火车客运站综合流通空间规划探索——以广州市铁路新客站地区规划为例

本文简要回顾了火车客运站地区规划研究的发展。提出火车客运站具有增长极的性质,各种经济流通空间集聚在火车客运站周边,形成了综合流通空间。分析了综合流通空间的内涵与特点。指出综合流通空间由核心功能区、衍生功能区、外围功能区三个层次构成,分析了各个层次的功能构成、服务设施与布局模型。对综合流通空间与其他城市功能空间的关系进行了探讨。以广州铁路新客站地区规划为例,从集聚作用、功能结构与布局、与其他城市功能区的联系三方面对综合流通空间进行了实证分析。     

Political pragmatism and the creative economy: Singapore as a City for the Arts

Can the arts and culture prosper under a less than democratic political regime? This paper looks at the soft authoritarian Singaporean government and the making of Singapore into a ‘City for the Arts’. Many scholars advocate that a culturally vibrant and creative city must also celebrate diversity, tolerance and experimentation. This implies that a democratic space is needed for creative energies to flow. Singapore is not known for its democracy. But Singapore has become relatively successful in being the cultural hub in the region. A more liberal approach to diversity and criticism of the authorities can now be observed but there are still many strong‐handed social and political controls in the city‐state. This paper tries to answer these two questions: has Singapore become democratic because the authorities want the arts and culture to flourish? Is democracy necessary for the creation of a lively cultural city?     

南京博物院藏近代铸币钢模研究

中国近代始有机制币,铸造机制币的核心技术部件是铸币模具,包括祖模(亦称原模、母模)及工作模。由于多种原因,铸币模具存世量稀少,历来为研究者所重视。南京博物院藏有十八件近代铸币钢模,是目前已知世界范围收藏中数量最大的,为研究中国近代经济、货币史提供了重要的资料。     

Carlisle: Function and Change between the First and Seventh Centuries AD

Archaeological excavations combined with antiquarian observations shed considerable light on the evolution of Roman Carlisle. From being a fort in the northern advance under Cerialis and Agricola, Carlisle developed as a nodal hub supported by a number of activity ‘zones’. By the early third century most had become absorbed into the newly created civitas capital. The Roman town declined and stone buildings became ruinous, a process that probably commenced before the fourth century and continued until the land was taken over by the kings of Northumbria and the church in the seventh century. Scanty archaeological records for the sub- and post-Roman periods are supplemented by implications for socio-political structures drawn from texts.     

港口、铁路与近代青岛城市变动:1898-1937

19世纪末20世纪初,随着近代中国社会与经济的现代转型,铁路、轮船等新型交通运输方式应运而生,一批新兴交通型城市逐渐形成,青岛便是其中之一。作为青岛港所在地和胶济铁路起点,青岛市在1898至1937年间的变动与港路休戚相关:港路运输体系的构建,极大改善了当地的交通运输条件,使青岛成为陆上交通枢纽并跃居山东省沿海第一大港;凭借路港联动,物流与人流均以前所未有的速度和规模在内陆—青岛—海外地区间流动,带动了青岛工商经济的飞速发展,也为青岛集聚了人气,大批务工、经商人员移居青岛,青岛市人口规模增大,街市不断扩展。在青岛港和胶济铁路的作用下,青岛完成了由小渔村到现代化城市的嬗变,并由此带动了山东省乃至近代华北地区交通和经济格局的变动。     

盘龙城与早商政权在长江流域的势力扩张

早商时期是商王朝势力开始迅速扩展的时期。早商政权的迅速扩张可以从商文化取代二里头文化及其对周边地区的文化侵略得以展示。跟随二里头文化的推进步伐,早商文化迅速把势力扩张到湖北、江西北部和湖南北部,其主要目的应该是拓展王朝势力和觊觎长江中下游地区丰富的铜矿资源。便利的地理位置和丰富的自然、矿产资源,使盘龙城商城得以在商王朝建立后迅速兴建。盘龙城商城可能就是商王朝把中国南方与中原早商核心地区连接起来的一个交通枢纽,是商王朝赐封诸侯的王国之都及军事据点。中商时期,由于商王室王位更迭引发了政治动乱,导致盘龙城商城这一地区中心聚落的废弃。     

The campus as a public space in the American college town

With its concert halls, museums, sports stadiums, landscaped grounds, and busy calendars of events, the college campus is a hub of activities that serves not only students and staff, but the larger population of a town and region. As such, the campus serves as both an environment for learning and a public space. This is especially true of campuses located outside big cities, because metropolitan institutions often face significant security concerns and demand for their facilities. Campuses in small cities, in contrast, tend to be open and inviting, and help to make the college town a distinctive type of urban place. This study will examine the multifaceted role of the campus, using the University of Oklahoma campus as an example, as a way to demonstrate the centrality of the campus to college town life.     

先唐时代之宣城：江南奥壤,山水诗都

唐代以前的宣城,走过了由县邑到郡治、由江南西部的行政中心到江南地区的政治腹地与经济沃壤的历程。其间几个关键节点是:楚国置爰陵邑,西汉置丹杨郡,孙吴丹杨郡迁治建业,西晋分置宣城郡,六朝时代之宣城既为近畿要地、又逐渐成长为文化名邦。以南齐谢朓为标志人物的山水诗的创作与影响,既反映了南朝时代宣城的文化特色,也使得宣城成为中国文学史上名副其实的"山水诗都"。