A Unifying Augmentation Algorithm for Two-Edge Connectivity and Biconnectivity

Given an undirected graph G and two vertex subsets H1 and H2, the bi-level augmentation problem is that of adding to G the smallest number of edges such that the resulting graph contains two internally vertex-disjoint paths between every pair of vertices in H1 and two edge-disjoint paths between every pair of vertices in H2. We present an algorithm to solve this problem in linear time. By properly setting H1 and H2, this augmentation algorithm subsumes existing optimal algorithms for several graph augmentation problems.     

基于复杂网络的金融传染风险模型研究

随着金融创新向更广和更深层面发展,金融体系中的传染风险和系统性风险越来越大,对此类风险进行准确度量是有效宏观审慎管理的重要内容。本文基于复杂网络理论,采用模拟方法对金融传染风险模型进行系统研究。首先,借鉴复杂网络的Watts级联动力学理论,构建了基于随机网络的金融传染模型,其较大的网络连通度水平不仅为传染提供更多的传播渠道,而且抵消了风险共享的能力。其次,引入Gleeson和Cahalane(2007)的分析框架,探讨了计算预期违约银行节点规模的解析模型,并对Watts模型中各种参数对系统风险的影响效应进行测度。最终,形成一个包括网络模拟方法、模型解析结论,以及网络统计分析方法等较全面的计算算法工具集合。     

生产性服务业网络的国际化水平分析——广州与亚太主要城市的比较

改革开放以来,广州经济实力不断增强,城市国际化水平极大提高,但广州与亚太城市相比,国际化水平有多高,与亚太区域性国际城市间的联系程度怎样,却少有研究。本文把广州放入到亚太区域城市组成的网络中,通过分析城市之间的网络连接度,笔者发现广州生产性服务业的总体发展水平不高,广州与亚太城市间的联系不够紧密;此外广州与香港的联系程度也并没有人们想象的那么高,甚至落后于北京和上海与香港的联系。因此广州要提高城市的国际化水平,必须加快生产性服务业的发展,尤其是要加强与香港、上海和北京这些周边亚太核心城市的联系。     

Critical factors affecting information sharing in supply chains

Abstract

The aim of this paper is to empirically examine a comprehensive list of factors that are anticipated to affect information sharing (IS) in supply chains (SC) in the context of a landlocked developing country Nepal. A survey questionnaire was developed and data were collected from 131 supply chain participants in Nepal. Exploratory factor analysis and path analysis were conducted to examine the fitness of the proposed model and the relationships between the identified factors and information sharing. The results suggest that interaction routines and personal connection influenced both operational and strategic information sharing while organisational compatibility, incentives, project payoffs, commitment (inter-organisational), top management commitment and supply network configuration affected operational IS and government support and monitoring were associated with strategic IS. The paper provides empirical evidence on how information sharing is affected in the context of a landlocked developing country. The paper also identifies and discusses the similarities and differences in the importance of these factors on information sharing between developed and developing countries. The main limitation is the moderate sample size as compared to the large number of variables contained in the study which may have limited the use of analytical tools. The study provides a better understanding of information sharing behaviours of supply chain participants in Nepal which will help firms to develop strategies accordingly to enhance information sharing.     

对称矩阵结合方案中关系图的连通性

设IFq是q个元的域,q是2的幂,S(n,q)是IFq上n×n对称矩阵所成的集合.本文给出了以X=S(n,q)为有限集的两种对称矩阵结合方案,分别讨论了这两种结合方案中结合关系R1和R1的关系图Γ(1)和Γ(1)的连通性.     

互联互通视角下中国-东盟基础设施与国际旅游协调发展研究

基础设施和旅游作为物理联通和人员交流的代表性组成部分,两者的协调发展是互联互通系统内“软”“硬”兼修的体现,也是推动和引导制度联通的重要力量。以中国-东盟基础设施与国际旅游的协调发展为研究对象,实证分析显示中国-东盟主要国家基础设施与国际旅游协调发展水平差异较大。中国基建“走出去”,内化基建于国际旅游将是区域内基础设施与国际旅游协调发展的主要方向。     

新兴的艺术形态及其实践:遥在与远程通信艺术

科学技术的发展,影响着艺术的变革。遥在与远程通信艺术作为新兴的艺术形态,追求远程临场的艺术效果,它代表着未来新媒体艺术发展的重要趋势。遥在与远程通信艺术强调的是一种远距离传播与接受的艺术形式,追求的是远程临场的新的审美心理感受与体验,以期达到就在那里的审美效果并产生别样的美感。     

论话语标记的连接性——以广义语境的视角

话语标记的连接性是话语标记的重要特征之一,但目前对话语标记的连接性存在两种观点：以Schiffrin等为代表的连贯派认为,话语标记的连接性体现在对同一话语中不同的话语语句（片段）的连接上,而以Blakemore等为代表的关联派学者却认为话语标记的连接性不是对不同话语语句的连接,而是一种推理连接。作者在论述这两种观点的基础上,以更广义的语境视角来探讨话语标记的连接性,从而更加全面地论述话语标记的连接性,也能更好地研究话语标记的作用。     

Assessing the Risk of Invasive Spread in Fragmented Landscapes

Little theoretical work has investigated how landscape structure affects invasive spread, even though broad-scale disturbances caused by habitat loss and fragmentation are believed to facilitate the spread of exotic species. Neutral landscape models (NLMs), derived from percolation theory in the field of landscape ecology, provide a tool for assessing the risk of invasive spread in fragmented landscapes. A percolation-based analysis of the potential for invasive spread in fragmented landscapes predicts that invasive spread may be enormously enhanced beyond some threshold level of habitat loss, which depends upon the species' dispersal abilities and the degree of habitat fragmentation. Assuming that invasive species spread primarily through disturbed areas of the landscape, poor dispersers may spread better in landscapes in which disturbances are concentrated in space, whereas good dispersers are predicted to spread better in landscapes where disturbances are small and dispersed (i.e., fragmented landscape). Assessing the risk of invasive spread in fragmented landscapes ultimately requires understanding the relative effects of landscape structure on processes that contribute to invasive spread--dispersal (successful colonization) and demography (successful establishment). Colonization success is predicted to be highest when >20% of the landscape has been disturbed, particularly if disturbances are large or aggregated in space, because propagules are more likely to encounter sites suitable for colonization and establishment. However, landscape pattern becomes less important for predicting colonization success if species are capable of occasional long-distance dispersal events. Invasive species are also more likely to persist and achieve positive population growth rates (successful establishment) in landscapes with clumped disturbance patterns, which can then function as population sources that produce immigrants that invade other landscapes. Finally, the invasibility of communities may be greatest in landscapes with a concentrated pattern of disturbance, especially below some critical threshold of biodiversity. Below the critical biodiversity threshold, the introduction of a single species can trigger a cascade of extinctions among indigenous species. The application of NLMs may thus offer new insights and opportunities for the management and restoration of landscapes so as to slow the spread of invasive species.