Spatial Vulnerability of Network Systems under Spatially Local Hazards

A hazard is often spatially local in a network system, but its impact can spread out through network topology and become global. To qualitatively and quantitatively assess the impact of spatially local hazards on network systems, this article develops a new spatial vulnerability model by taking into account hazard location, area covered by hazard, and impact of hazard (including direct impact and indirect impact), and proposes an absolute spatial vulnerability index (ASVI) and a relative spatial vulnerability index (RSVI). The relationship between the new model and some relevant traditional network properties is also analyzed. A case study on the spatial vulnerability of the Chinese civil aviation network system is conducted to demonstrate the effectiveness of the model, and another case study on the Beijing subway network system to verify its relationship with traditional network properties.     

国有股减持与上市公司经营绩效的关系实证研究

西方国家产权高度分散企业出现的 “ 丑闻”、转轨经济国家私有化的消极影响和我国股份制改革未能提高国有企业经营绩效的实践证明,产权私有化不是提高国有企业经营绩效的“灵丹妙药”,国有股减持不合时宜。为验证该结论,本文以深沪两市 2001年综合类上市公司为样本对国有股、流通股与公司绩效的关系进行了实证分析。结果表明,国有股、流通股与公司绩效之间存在曲线关系,且它们与公司绩效之间均存在负相关关系。其中,国有股对上市公司经营业绩的负影响不显著,流通股的负影响较显著。     

企业治理权的配置:内外部治理的成本收益假说

内外部治理的成本收益假说说明利益相关者的内部治理权和外部治理权存在着一定的替代性关系,而影响这种替代关系的关键要素是非专有的专用性资产、内部治理成本和外部治理成本。     

The canadian traveller problem and its competitive analysis

From the online point of view, we study the Canadian Traveller Problem (CTP), in which the traveller knows in advance the structure of the graph and the costs of all edges. However, some edges may fail and the traveller only observes that upon reaching an adjacent vertex of the blocked edge. The goal is to find the least-cost route from the source O to the destination D, more precisely, to find an adaptive strategy minimizing the competitive ratio, which compares the performance of this strategy with that of a hypothetical offline algorithm that knows the entire topology in advance. In this paper, we present two adaptive strategies—a greedy or myopic strategy and a comparison strategy combining the greedy strategy and the reposition strategy in which the traveller backtracks to the source every time when he/she sees a failed edge. We prove tight competitive ratios of 2 ^k+1−1 and 2k+1 respectively for the two strategies, where k is the number of failed edges in the graph. Finally, we propose an explanation of why the greedy strategy and the comparison strategy are usually preferred by drivers in an urban traffic environment, based on an argument related to the length of the second-shortest path in a grid graph. We would like to acknowledge the support from NSF of China (No. 70525004, No. 70121001 and No. 60736027), and the support from K.C. Wong Education Foundation, Hong Kong.     

区域创新能力及其制约因素解析——基于1997～2007省际面板数据检验

根据我国各省、自治区、直辖市1997～2007年的创新活动面板数据,以专利的授权数量作为创新产出的指标,实证检验区域创新环境对区域创新能力的影响,并解释我国区域创新能力存在差异的原因.实证结果表明:中国30个省(区、市)创新绩效存在显著差异,这种现象的存在不仅是由于各地区研发人员和研发费用的投入差异,也是由于各地区以FDI、市场化程度、累积知识存量和知识流动能力等因素组成的创新环境的差异.在此基础上,提出增强区域创新能力和克服其"瓶颈"的政策建议.     

企业群体行为变化的定性模拟研究

利用定性模拟技术在处理不完备知识和深层知识等方面独有的优势,将定性模拟技术应用于企业群体行为的研究,为复杂管理系统的研究提供了一个有用的工具。针对一个群体工作过程模型,结合专家知识、概率分布设计了模拟规则并进行了模拟,模拟结果比较符合实际。     

燃气涡轮的模糊控制实现

燃气涡轮工作转速受进油量、进气量和试验装置特性等多种因素的影响，由于这些因素之间有很强的交叉耦合，很难建立精确的数学模型，因此按经典控制理论很难对燃气涡轮的转速进行控制。针对燃气涡轮系统的转速控制问题，文中提出了一种实用的自寻优ＦＵＺＺＹＰＩ模糊控制方案。利用模糊推理合成规则，得出了模糊控制结果，并用于实际系统控制，获得了成功。