经济地理学视角下西方产业集群研究的演进及其新动向   总被引：1，自引：0，他引：1  

罗胤晨  谷人旭  王春萌 《世界地理研究》2016,(6):96-108

近30年来,西方经济地理学经历了快速、多元的理论转向,产业集群理论则在汲取相关养分的基础上形成了研究焦点和内容的演进,并持续影响着我国产业集群研究的发展与实践。以经济地理学为研究视角,首先梳理20世纪70年代末以来西方产业集群研究内容的发展脉络,将产业集群理论的演进划分为萌芽、发展和深化三个阶段。其次,对进入21世纪后产业集群研究的新动向进行归纳,发现研究焦点主要集中于网络、时间、空间和技术四个维度,同时在研究内容上呈现出四种变化特征和趋势:①从"集群结构"到"集群网络"的网络复杂性;②从"静态集群"到"集群演化"的时间动态性;③从"持久性集群"到"临时性集群"的空间非嵌入性;④从"实体性集群"到"虚拟性集群"的技术互联网性。最后,在此基础上进一步阐述其对我国产业集群研究的影响和启示。  相似文献   

Activity patterns,socioeconomic status and urban spatial structure: what can social media data tell us?     

Qunying Huang  David W. S. Wong 《International journal of geographical information science》2016,30(9):1873-1898

ABSTRACT

Individual activity patterns are influenced by a wide variety of factors. The more important ones include socioeconomic status (SES) and urban spatial structure. While most previous studies relied heavily on the expensive travel-diary type data, the feasibility of using social media data to support activity pattern analysis has not been evaluated. Despite the various appealing aspects of social media data, including low acquisition cost and relatively wide geographical and international coverage, these data also have many limitations, including the lack of background information of users, such as home locations and SES. A major objective of this study is to explore the extent that Twitter data can be used to support activity pattern analysis. We introduce an approach to determine users’ home and work locations in order to examine the activity patterns of individuals. To infer the SES of individuals, we incorporate the American Community Survey (ACS) data. Using Twitter data for Washington, DC, we analyzed the activity patterns of Twitter users with different SESs. The study clearly demonstrates that while SES is highly important, the urban spatial structure, particularly where jobs are mainly found and the geographical layout of the region, plays a critical role in affecting the variation in activity patterns between users from different communities.  相似文献   

Adapting to changes in volcanic behaviour: Formal and informal interactions for enhanced risk management at Tungurahua Volcano,Ecuador     

《Global Environmental Change》2017

This paper provides an example of how communities can adapt to extreme forms of environmental change and uncertainty over the longer term. We analyse the interactions between scientists, communities and risk managers and examine the interpretation and communication of uncertain scientific information during a long-lived volcanic eruption in Tungurahua, Ecuador. This is complemented with a detailed study of the eruptions of 2006 and 2014, which exemplifies the complexity of interactions during periods of heightened volcanic activity. Our study describes how a ‘shadow network’ has developed outside of, but in interaction with, the formal risk management institutions in Ecuador, improving decision-making in response to heightened volcanic activity.The findings suggest that the interactions have facilitated important adaptations in the scientific advisory response during eruptions (near-real-time interpretation of the volcanic hazards), in hazard communication, and in the evacuation processes. Improved communication between stakeholders and the establishment of thresholds for evacuations have created an effective voluntary evacuation system unique to Tungurahua, allowing people to continue to maintain their livelihoods during heightened volcanic activity and associated periods of uncertainty. Understanding how shadow networks act to minimise the negative consequences of volcanic activity provides valuable insights for increasing societal resilience to other types of hazards.  相似文献   

Upgrading and exploitation in the fishing industry: Contributions of value chain analysis     

《Marine Policy》2016

This article presents a framework for fisheries sector analysis based on the literatures on global value chains (GVCs) and global production networks (GPNs). A value chain approach offers an alternative to focusing primarily on policy as an explanatory variable, by bringing into focus relations among buyers, sellers and other stakeholders as well as their institutional context. After outlining the utility of this approach, the article identifies three questions at the forefront of contemporary debates on the dynamics of GVCs and GPNs. Namely: (1) How institutional context affects distributional and regulatory outcomes; (2) The conditions under which particular institutions that limit or regulate market forces are either productive or perverse; and (3) Why and how particular markets are constituted in the ways that they are. The article then showcases some of the central findings from the case studies brought together in this thematic issue, demonstrating how they contribute to current analytic debates surrounding value chains and core substantive problems facing both fisheries and those engaged in the fishing industry.  相似文献   

Linking Structural Equation Modeling with Bayesian Network and Its Application to Coastal Phytoplankton Dynamics in the Bohai Bay     

徐晓甫  孙健  聂红涛  袁德奎  陶建华 《海洋工程》2016,(5):733-748

Bayesian networks (BN) have many advantages over other methods in ecological modeling, and have become an increasingly popular modeling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modeling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in the Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models, and increases the BN model’s accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in the Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, although the Redfield ratio indicates that phosphorus should be the primary nutrient limiting factor, our results show that silicate plays the most important role in regulating phytoplankton dynamics in the Bohai Bay.  相似文献   

基于模糊小波神经网络算法的汽车滑移率控制研究     

薛艳梅  杨青青  邵珂 《南京气象学院学报》2016,8(5):415-420

防抱死系统是汽车制动过程非常重要的基本安全措施,滑移率控制是汽车防抱死控制的重要组成部分.汽车的制动过程是一个与实时路况相关的时变、非线性、不确定系统.针对该问题开展基于模糊小波神经网络算法的滑移率控制研究.通过采用模糊小波神经网络估计系统模型的非线性、时变不易获知的部分,结合等效控制思想来构造滑模控制法则,从而实现期望的滑移率控制.Matlab-simulink仿真结果表明,所设计的算法具有良好的鲁棒性能,能有效、快速地到达期望的滑移率.  相似文献   

Engaging communities in climate adaptation: the potential of social networks     

Rebecca Cunningham  Christopher Cvitanovic  Thomas Measham  Brent Jacobs  Anne-Maree Dowd  Ben Harman 《Climate Policy》2016,16(7):894-908

There has been a growing recognition regarding the use of social networks to engage communities in government actions. However, despite increasing awareness of social networks, there is very limited evidence for their application in relation to climate policy. This study fills this gap by assessing the potential of social networks for engaging local communities in climate adaptation policy, drawing on a case study of the Shoalhaven region in Australia. Participants from key representative groups were recruited using a purposive snowball sampling technique (N?=?24). By mapping knowledge acquisition and diffusion networks in relation to climate adaption at the local scale, this study identified key nodes within the networks. Findings demonstrate that although climate adaptation information was acquired from a diverse range of sources, the sharing knowledge networks were far more dispersed. Furthermore, although 165 knowledge sources were identified, three nodes had coverage cross the entire network, and as such acted as boundary spanners within the sharing network. This research demonstrates the utility of social network analysis to reveal the underlying knowledge networks and structures that influence community engagement pathways and in doing so outlines key implications in relation to engaging local communities in climate policy and action.

Policy relevance

The rapid development of adaptation as a mainstream strategy for managing the risks of climate change has resulted in the emergence of a broad range of adaptation policies and management strategies globally. However, the success of these initiatives is largely dependent on their acceptance and uptake by local communities, which to date remains a significant challenge. Accordingly, policy makers require novel approaches to overcome barriers to community engagement so as to enhance the likely success of community engagement pathways. This article demonstrates the value of using social network analysis to reveal the underlying knowledge network structures. This approach makes it possible to identify key individuals within a community who can disseminate adaptation information quickly across broad geographic ranges. By utilizing this approach, policy makers globally will be able to increase the extent to which adaption initiatives are accepted and adhered to by local communities, thus increasing their success.  相似文献   

定量成矿预测的人工神经网络模型   总被引：4，自引：0，他引：4       下载免费PDF全文

吕新彪  赵鹏大 《地球科学》1998,23(6):619-623

重点探讨了资源量预测人工神经网络ＢＰ模型（ＢＰ－ＭＲＰ）的建造和预测问题,特别对模型输入层（地质变量）、隐含层和输出层的构置和优选,模型的学习、检验和预测评价等问题作了较深入的讨论,尝试性地提出了模型输入变量的优化方法和模型检验准确率的计算方法,并以长江中下游地区为实例,给出了ＢＰ－ＭＲＰ模型的实际建造步骤和预测。结果证明,人工神经网络模型不仅能够模拟成矿地质因素和矿床特征（值）之间的非线性关系,  相似文献   

绘制水系网及汇水盆地的计算机实现   总被引：2，自引：0，他引：2  

刘光胜  杨永强 《世界地质》1998,17(4):29-32

利用水流向最陡方向的基本原理编制了计算水系网及汇水盆地的程序,实际计算了某地区的水系网及汇水盆地网,计算结果可方便地进入ＧＩＳ。  相似文献   

A conceptual model of hydraulic networks in carbonate rocks, illustrated by examples from Poland   总被引：2，自引：1，他引：1  

J. Motyka 《Hydrogeology Journal》1998,6(4):469-482

 Hydraulic networks of carbonate rocks usually consist of three types of spaces: pores, fissures, and caverns; sometimes filled forms also are present. At sufficiently large scales, the spaces are assumed to be homogeneous with arbitrary boundaries and to be characterized by mean values of parameters. A conceptual model and its schematic presentation demonstrate the importance of particular parameters for flow and solute transport, and they explain the responses of pumping rates and water levels to changes in boundary conditions. Three examples characterize some typical networks: (1) chalk in eastern Poland, representing fissured aquifers with a high storage volume for solutes in stagnant matrix water; (2) Middle Triassic limestones in southern Poland, representing fissured-cavernous aquifers; however, a large storage volume for solute transport is in mostly stagnant matrix water; and (3) Triassic dolomites in the same area, representing porous-fissured-cavernous aquifers with a considerable storage volume in the matrix, which can partly be released (20%), considerably contributing to the total specific yield. For the last two types of aquifers, the hydraulic conductivity near pumping wells and mine galleries usually quickly increases in time due to suffosion of filled forms, which leads to a temporal large increase of the inflows. Received, April 1997 Revised, January 1998, August 1998 Accepted, May 1998  相似文献