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.     

INTERNATIONAL NETWORKS AND ARTS POLICY RESEARCH1

There is a growth of networks in the cultural policy arena. Many of these networks have been formed to share information and to engage in comparative documentation and research. The International Federation of Arts Councils and Culture Agencies (IFACCA) is one such network, established with aims of consolidating the collective knowledge of arts councils and culture agencies, adding value to that knowledge, and improving the management and sharing of information on arts and cultural policy. Networks such as IFACCA impact on the research agenda in two main ways: directly, by undertaking, commissioning or collaborating on research projects, and indirectly, by highlighting the perceived information needs of their constituents or members. IFACCA’s main research programme, D’Art, is used as a case study to evaluate the direct impacts of the network, and this forms the basis for a discussion of the influence of such networks on the global arts policy research agenda.     

A Socio‐Geographic Perspective on Human Activities in Social Media

Location‐based social media make it possible to understand social and geographic aspects of human activities. However, previous studies have mostly examined these two aspects separately without looking at how they are linked. The study aims to connect two aspects by investigating whether there is any correlation between social connections and users' check‐in locations from a socio‐geographic perspective. We constructed three types of networks: a people–people network, a location–location network, and a city–city network from former location‐based social media Brightkite and Gowalla in the U.S., based on users' check‐in locations and their friendships. We adopted some complexity science methods such as power‐law detection and head/tail breaks classification method for analysis and visualization. Head/tail breaks recursively partitions data into a few large things in the head and many small things in the tail. By analyzing check‐in locations, we found that users' check‐in patterns are heterogeneous at both the individual and collective levels. We also discovered that users' first or most frequent check‐in locations can be the representatives of users' spatial information. The constructed networks based on these locations are very heterogeneous, as indicated by the high ht‐index. Most importantly, the node degree of the networks correlates highly with the population at locations (mostly with R² being 0.7) or cities (above 0.9). This correlation indicates that the geographic distributions of the social media users relate highly to their online social connections.     

Nonparametric Significance Test for Discovery of Network‐Constrained Spatial Co‐Location Patterns

Spatial co‐location patterns are useful for understanding positive spatial interactions among different geographical phenomena. Existing methods for detecting spatial co‐location patterns are mostly developed based on planar space assumption; however, geographical phenomena related to human activities are strongly constrained by road networks. Although these methods can be simply modified to consider the constraints of networks by using the network distance or network partitioning scheme, user‐specified parameters or priori assumptions for determining prevalent co‐location patterns are still subjective. As a result, some co‐location patterns may be wrongly reported or omitted. Therefore, a nonparametric significance test without priori assumptions about the distributions of the spatial features is proposed in this article. Both point‐dependent and location‐dependent network‐constrained summary statistics are first utilized to model the distribution characteristics of the spatial features. Then, by using these summary statistics, a network‐constrained pattern reconstruction method is developed to construct the null model of the test, and the prevalence degree of co‐location patterns is modeled as the significance level. The significance test is evaluated using the facility points‐of‐interest data sets. Experiments and comparisons show that the significance test can effectively detect network‐constrained spatial co‐location patterns with less priori knowledge and outperforms two state‐of‐the‐art methods in excluding spurious patterns.     

NETWORKING, KNOWLEDGE ORGANIZATIONS AND AEROMOBILITY

This article explores networking and travel in two international knowledge organizations located in Denmark. It shows that these knowledge organizations are organized in various ways through different types of network on different scales. Therefore the individual employees in both organizations are dependent on their ability to create and maintain relations within networks. The article argues that such networking activities cannot be understood separately from air travel. However, work and travel decisions are also highly individualized, meaning that a number of more individual and non-work rationalities are also significant in employees deciding whether to travel or not. Therefore the article concludes that, in a number of social situations, individual rationalities function as a barrier to the increased use of video technology. It is therefore necessary to create new mechanisms to support the increased use of virtual communications in order to reduce the environmental impact of air travel in knowledge organizations.     

The Performance of Policy Networks: The Relation between Network Structure and Network Performance

The importance of policy networks has long been emphasized within the field of policy analysis. However, few attempts have been made to investigate the explanatory power of policy networks using the tools and theoretical concepts provided by social network analysis (SNA). This paper aims to address this need by determining if a relationship exists between the structural features of policy networks, their organizing capacities, and their performance. A comparative case study of four networks within the higher education policy sector confirms the assumption related to the existence of such a relation. It is proposed that an efficient and innovative policy network consists of a heterogeneous set of actors that are centrally and densely integrated. Furthermore, while the level of network heterogeneity is positively related to the function of resource mobilization in the process of policymaking, the level of centralized integration promotes the function of prioritizing. These findings are believed to contribute to our understanding of policymaking in contemporary society. The current paper indicates that a significant explanatory power exists in the concept of policy networks and that SNA is one way of advancing its possibilities.     

SOME OBSERVATIONS ON THE STRUCTURE OF SOCIO-ECONOMIC CELLULAR NETWORKS

The paper has presented an approach to cellular network pattern analysis which is novel in several respects. First, the approach emphasizes the consideration of the complete geometric structure of the pattern rather than the examination of summary statistics for individual variables or correlations between pairs or other combinations of variables. By comparing empirical structures with model-generated ones it is suggested that the approach offers a way of evaluating the relative impact of the three major forces thought to be responsible for the geometric structure of a network, i.e., the generating process, the phenomena expressed in the network, and the function of the network. It was demonstrated how different processes can lead to diverse geometric structures. Examination of two empirical networks composed of bus service centre hinterlands suggested that the generating process was the dominant determinant of physical structure in this particular instance. However, more research on other cellular networks consisting of different phenomena, and on different generative processes, must be undertaken before any firm conclusions can be reached. The approach taken here would seem to offer one way of undertaking such research.     

The spatiality of trust in EU external cross-border cooperation

This paper argues that effective cross-border cooperation (CBC) networks closely interrelate with the building of ‘trust’ between actors. The aim is to contribute to the CBC literature by investigating the different forms of trust, their spatial attributes and impact on actor relations in the context of the Finnish–Russian European Neighbourhood Instrument (ENI) of CBC. The paper applies a specific spatial approach by identifying the territorial and relational aspects of four different forms of trust: rational-personal decisions, social-cultural understanding, general-personal interactions and the historical–institutional environment. The analysis, based on policy documents and semi-structured interviews with relevant Finnish ENI CBC actors, shows that the study of transnational cooperation networks benefits from a conceptualization of trust recognizing its spatial characteristics. The study concludes that sub-national actors are key agents in the formation and maintenance of trust. These actors negotiate with socio-cultural differences through the development of personal relationships which increase social capital in the actor–network. However, the cooperation network is vulnerable towards geopolitical circumstances affecting foreign relations. The paper demonstrates that Finnish ENI CBC actors are operating in a transnational network in which their activities are challenged by territorial constraints such as national border-crossing regulations.     

归侨侨眷的跨国网络与中越跨境经济合作——以广西东兴为例

论文以广西东兴市归侨侨眷参与中越跨境经济合作为例,探讨了民间力量在推动跨国区域合作中的作用。论文认为,民间力量也是跨国区域合作的重要推动力量之一。归侨侨眷作为民间力量具有独特的优势,是政府力量的有效补充。在归侨侨眷形成的跨国关系网络中,蕴含的信任等无形资源以及嵌入在网络中的信息、资金、客户等有形资源是归侨侨眷得以在跨境经济合作中发挥作用的重要原因。这种跨国网络中的资源降低了市场交易成本,促进了生产要素的跨国流动,从而有利于推动跨境经济合作的快速发展。     

节庆事件对区域旅游流空间网络的影响效应和机制研究

以洛阳牡丹花节为例,通过多源数据的融合,运用社会网络、因子分析方法,探究节庆事件对区域旅游流空间网络的影响效应及机制。结果表明：节庆事件对区域旅游流空间网络影响表现为协同、弱化及蜂聚三种效应,不同效应影响机制不同。其中,节点的等级和知名度优势非常明显的态势下,产生显著的协同效应;节庆游憩区内的低等级节点出现轻微的节庆弱化效应,区域外节点主要受到空间交通距离限制产生了显著的节庆弱化效应;旅游等级很强且旅游承载量优势非常明显的非节庆旅游节点,以及等级、知名度或地理区位较强的节庆旅游节点呈现出强蜂聚效应,以上条件均不强的节庆旅游节点仅发生弱集聚效应。     

Networks of engagement: electronic communication and grassroots environmental activism in Kaliningrad

This paper contributes to a discussion on networks as political spaces by examining the work of an environmental activist group in Kaliningrad, Russia. Drawing from geographic work on communication and from literature on organizational structure and communication technology provides a useful means of understanding and conceptualizing computer networks from a social science perspective. The case study of grassroots activism illustrates how computer-based communication may support a unique space of political activity. Electronic mail (e-mail) communication can be a channel through which activists may overcome the constraints of location as an information container in order to create spaces of interaction and action appropriate to their political agenda. This case study is an example where organization members use e-mail communication to connect their activities, information sources and collaborative partners at different scales to create a viable space for environmental activism and information distribution within a shifting political context.     

Learning in Single Hidden-Layer Feedforward Network Models: Backpropagation in a Spatial Interaction Modeling Context

Learning in neural networks has attracted considerable interest in recent years. Our focus is on learning in single hidden-layer feedforward networks which is posed as a search in the network parameter space for a network that minimizes an additive error function of statistically independent examples. We review first the class of single hidden-layer feedforward networks and characterize the learning process in such networks from a statistical point of view. Then we describe the backpropagation procedure, the leading case of gradient descent learning algorithms for the class of networks considered here, as well as an efficient heuristic modification. Finally, we analyze the applicability of these learning methods to the problem of predicting interregional telecommunication flows. Particular emphasis is laid on the engineering judgment, first, in choosing appropriate values for the tunable parameters, second, on the decision whether to train the network by epoch or by pattern (random approximation), and, third, on the overfitting problem. In addition, the analysis shows that the neural network model whether using either epoch-based or pattern-based stochastic approximation outperforms the classical regression approach to modeling telecommunication flows.     

RESISTANCE AND STRATEGIC RESPONSES IN FOOD SUPPLY NETWORKS: METRO CASH & CARRY IN BANGALORE

The transnational expansion of large retail and wholesale companies such as Metro, Carrefour and Wal‐Mart has caused changes in the market situation and consequent power shifts, not only in the retail sector but also in the supply networks in host countries. These developments at least potentially endanger the livelihoods of old established retailers, intermediaries and employees of these businesses. Thus, it is not surprising that the investments of the transnational companies can result in resistance from those affected. As an analysis of Metro and its activities in the federal state of Karnataka in India shows, this resistance can influence the activities of the company to develop a modern supply network. This study analyses the way in which the actors of resistance develop and exercise power and how this in turn influences Metro. The global production network (GPN) approach is used as an analytical framework. The results emphasize the importance of networks external to the firm for the analysis of processes of globalization. The company's behaviour cannot be understood unless the resistance is taken into account. The study shows that the GPN framework provides the tools to analyse the influence of actors such as civil society groups, trade unions and associations as part of the production network. However, up to now this option has rarely been used.     

Outward foreign direct investment,offshore outsourcing and local network resilience in industrial districts

The internationalization of production activities is having a profound impact on regional economies. In this regard, it is generating externalities not only in the countries where production is offshored, but also in the domestic networks in which the internationalizing firms are located. Therefore, this paper investigates the effects of outward foreign direct investment and offshore outsourcing activities on domestic supplier populations in industrial districts (IDs). The aim is to evaluate the ability of these systems to react to the structural shocks associated with internationalization strategies. The results show that local network resilience is generally higher in advanced forms of IDs, where the role of large firms or service activities is more relevant.     

互联网信息对健身俱乐部连锁店空间竞争的指示研究

以北京浩沙健身连锁俱乐部为例,尝试利用公众在大众点评网、新浪微博等网络社区中发布的关注度、评价等作为加权因子,分析连锁网点之间的竞争状态,建立了一个基于互联网信息的加权因子计算模型,计算各连锁店的市场竞争域,结果显示互联网空间信息能够对连锁店之间的空间竞争产生指示作用,各分店表现出明显的竞争力差异;提出对加权Voronoi图区位意义上的地理学新解释:它不仅反映连锁店基本市场域,而且其边线弯曲度和单元面积的变化还可折射各连锁店在互联网空间中的吸引力差异。     

The ‘Iranian Diaspora’ and the New Media: From Political Action to Humanitarian Help

This article looks at the shifting position of the ‘Iranian diaspora’ in relation to Iran as it is influenced by online and offline transnational networks. In the 1980s the exilic identity of a large part of the Iranian diaspora was the core factor in establishing an extended, yet exclusive form of transnational network. Since then, the patterns of identity within this community have shifted towards a more inclusive network as a result of those transnational connections, leading to more extensive and intense connections and activities between the Iranian diaspora and Iranians in Iran. The main concern of the article is to examine how the narratives of identity are constructed and transformed within Iranian (charity) networks and to identify the factors that contribute to this transformation. The authors use the transnational lens to view diasporic positioning as linked to development issues. New technological sources help diaspora groups, in this case Iranians, to build virtual embedded ties that transcend nation states and borders. Yet, the study also shows that these transnational connections can still be challenged by the nation state, as has been the case with recent developments in Iran.     

Network Management and Information Systems in Promotion of Urban Economic Development: Some Reflections from CityWeb of Tampere

Partnership relations have become more important in promotion of urban economic development. Efforts have been made to create such networks by which to strive for new markets or political arenas and so to extend the resource base of the urban region. The objective in the creation of networks is the most efficient mobilization possible of the know-how and resources in the urban region and external to it. These observations inevitably prompt the following questions: How can the quality of cooperative processes be improved and how can networks and various development projects be managed? It seems evident that information and its conscious management play a crucial role in seeking answers to these questions. Simultaneously such questions emerge as to how network management can respond to the increasing amount of information and the demands for rapid learning. How can the vast flood of information and knowledge in the networks be managed, how can essential features be extracted, i.e. how can a sustainable basis for perceptions be created? One possible answer, among others, to these questions is information systems utilizing modern information technology. This paper focuses on urban development networks and especially at how their efficiency can be promoted by network management and by modern information systems. The case described and tentatively analysed is the information system CityWeb of Tampere urban region, Finland.     

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.     

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.     

广州摊贩空间疏导模式及其成功效应的影响因素——基于沥滘村疏导区的实证研究

摊贩治理是我国城市社会空间矛盾的重要问题。本文在分析广州摊贩空间疏导模式的基础上,以案例研究揭示了疏导区成功的微观要素。与此前的强制性控制不同,空间疏导体现了一种政府主导、社会力量参与、多方利益主体协调的管治模式。研究认为,有效的疏导区需要满足摊贩的需求以使其入区之后获得比入区前更好的收益,具体而言需要包含以下要素:①合适的区位,靠近主要人流路线、使摊贩与正规经济形成集聚和互补关系并延续原有的社会关系;②维持摊贩的低成本优势;③形成规模化的多样商品集市;④清洁、安全和有序的经营空间;⑤提供有保障的空间使用权和经营权。