内生型产业集群中的企业家社会网络和行为研究--理论假定和应用研究   总被引：7，自引：0，他引：7  

王建 《中国软科学》2006,(1):117-123

本文指出经济学对产业集群现象解释的局限,并试图从企业家社会网络的角度来分析这一现象。通过构造环境、网络和行为三者之间的关系,在内生型产业集群环境下,利用“撒网”模型做应用研究,文章得出两点结论：第一,强联系在企业家撒网过程中起主要作用;第二,个体行为的路径依赖现象影响了企业家撒网的过程和结果。  相似文献   

结构洞的前沿探析与未来展望     

王海峰 《科技管理研究》2016,(11):214-219

在跨组织网络备受关注的今日,结构洞已成为企业必须重视的问题。基于国内外结构洞研究的最新进展,在梳理相关文献的基础上,对结构洞的内涵、研究方法、测量与作用机制进行阐释,并提出结构洞研究框架。为中国情境下结构洞研究提出理论依据和启示,指出该领域未来的研究方向。  相似文献   

中国国际贸易的汇率弹性分析——基于人工神经元网络     

宋逢明  王东杰  高峰 《科学学与科学技术管理》2007,28(6):112-117

将人工神经元网络方法运用到汇率问题中,结合协整向量自回归方法,对1994年1月到2006年6月人民币实际有效汇率指数与中国进出口贸易额的关系进行了实证研究。结果表明,我国的马歇尔-勒纳条件(ML条件)成立;人民币升值会小幅度地抑制出口促进进口,对进口的拉动作用大于对出口的抑制作用。  相似文献   

Developing Standards for Emerging Forms of Assessment: The NISO Altmetrics Initiative     

Todd A. Carpenter  Nettie Lagace  Sara Bahnmaier 《期刊图书馆员》2016,70(1-4):85-88

New types of calculation methodologies, called altmetrics, which is short for alternative metrics, are increasingly being used to measure and analyze the scholarly communication networks of researchers, librarians, publishers, and funding organizations. By applying altmetrics to emergent online forums like Twitter, Academia.edu, Mendeley, and ResearchGate, studies have shown that early measures of social attention to a work or body of work can be correlated with later usage and citation statistics to predict the diffusion and impact of research output. However, standards for altmetrics are needed to build confidence and trust among the information community.  相似文献   

Folksonomy模式中紧密型领域知识群落动态演化研究   总被引：1，自引：1，他引：0  

滕广青 《中国图书馆学报》2016,42(4):51-63

具有高度感知易用性的Folksonomy知识组织模式,在实践应用中却呈现离散纷杂的外在表象。对Folksonomy知识组织模式中领域知识群落及其结构关系的研究,对于洞悉领域知识发展过程中的衍生、交叉、融合等现象具有重要意义。本研究以复杂网络分析中的层次派系分析技术为主要研究方法,基于标签共同标注关系构建领域知识网络。从标签间关联关系出发,对特定领域知识网络中紧密型知识群落的发展过程进行时间序列的动态跟踪与分析。研究结果表明:标签数量在领域成熟期趋于饱和,但标签间的连线数量却持续增长,紧密型领域知识群落规模逐渐扩大;紧密型领域知识群落数量总体递增的同时也存在波动,这种波动与知识群落自身的扩张、衰减、派生、融合的演化过程有关;随着领域知识的发展,紧密型知识群落之间的交叠密度呈上升趋势,并基于交叠关系形成了一个更大的知识群落,成为领域知识网络的部分骨架结构,进而能够展示出多个主要发展方向。对领域知识群落演化规律的揭示,有助于把握领域知识演进的发展脉络,并揭示Folksonomy知识组织模式中领域知识的发展模式与规律。  相似文献   

TCP performance evaluation over AODV and DSDV in RW and SN mobility models   总被引：1，自引：0，他引：1  

REN Wei YEUNG D.Y. JIN Hai 《浙江大学学报(A卷英文版)》2006,7(10):1683-1689

INTRODUCTION Widely varying mobility characteristics are ex- pected to have significant impact on the performance of routing protocols. Many previous works focused on the routing protocols and seldom discussed the impact of mobility on the transport layer protocol. On the other hand, the performance of the transport layer protocol over different routing protocols was evalu- ated in some previous works (Ahuja et al., 2000; Dyer and Boppana, 2001), but they always used the Ran- dom Waypoin…  相似文献   

BulkTree: an overlay network architecture for live media streaming     

GONG An  DING Gui-guang  DAI Qiong-hai  LIN Chuang 《浙江大学学报(A卷英文版)》2006,7(Z1)

Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure.  相似文献   

具分布时滞和变系数细胞神经网络周期解的存在性     

王金华 《湘南学院学报》2005,26(5):9-13,15

利用矩阵测度和不动点定理,研究了一类具分布时滞和变系数的神经网络模型ddtxi=-bi(t)xi(t)+∑nj=1aij(t)fj(t,xj)+∑nj=1bij(t)gj(t,μ∫j0∞kij(u)xj(t-u)du)+Ii(t)的周期解,得到了其周期解存在的一个新的充分条件.  相似文献   

广义动态神经网络的绝对指数稳定性   总被引：1，自引：0，他引：1  

孙长银  费树岷  冯纯伯 《东南大学学报》2002,18(2):159-163

本研究了一类具偏李普希兹连续和单调增加激活函数的神经网络绝对指数稳定性问题。所得结果归结为如果联接矩阵T的负矩阵是一个非负对角元的H矩阵，那么在任意输入向量和网络参数的条件下，所选激活函数只要是偏李普希兹连续且单调增加的，广义动态神经网络绝对指数稳定。该广义动态神经网络包含常用的Hopfield神经网络，双向联想记忆神经网络和细胞神经网络作为其特殊情形，所得结论推广了现有献中的有关结论。  相似文献   

Child maltreatment in the “Children of the Nineties:” deprivation, class, and social networks in a UK sample     

Peter Sidebotham  Jon Heron  Jean Golding  The ALSPAC Study Team 《Child abuse & neglect》2002,26(12)

Aim: To determine risk factors for child maltreatment within the socio-economic environment of a contemporary UK child population.Methods: The research is based on a large cohort study, the Avon Longitudinal Study of Parents and Children. Out of 14,256 children participating in the study, 115 have been identified as having been placed on local child protection registers prior to their 6th birthday. Data on the socio-economic environment of the families have been obtained from a series of questionnaires administered during pregnancy and the first 3 years of life. Risk factors have been analyzed using logistic regression analysis.Results: Four indicators of deprivation all showed significant relationships with registration. Adjusted odds ratios were 2.33 for paternal unemployment; 7.65 for council housing; 2.16 for overcrowding; and 2.33 for car ownership. There was a strong relationship between the number of indicators of deprivation and the risk of maltreatment. In a second model, maternal unemployment, high mobility (> 3 house moves in the previous 5 years) and a poor social network were also significant with odds ratios of 2.82, 2.81, and 3.09, respectively.Conclusions: This study confirms the importance of social factors in the etiology of child maltreatment. Social deprivation is an important determinant of child maltreatment, and encompasses a number of different aspects, including financial security, housing situation and material benefits; in addition, the job situation of the parents and the stability and richness of their social networks all have a significant impact on risk of maltreatment. Interventions at both an individual and a community level are important to support families and reduce the risk of maltreatment.  相似文献