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《国家科学评论(英文版)》2014,(3)
Network science has atracted much atention in recent years due to its interdisciplinary applications. We witnessed the revolution of network science in 1998 and 1999 started with small-world and scale-free networks having now thousands of high-proile publications, and it seems that since 2010 studies of‘network of networks'(NON), sometimes called multilayer networks or multiplex, have atracted more and more atention. he analytic framework for NON yields a novel percolation law for n interdependent networks that shows that percolation theory of single networks studied extensively in physics and mathematics in the last 50 years is a speciic limit of the rich and very diferent general case of n coupled networks. Since then, properties and dynamics of interdependent and interconnected networks have been studied extensively, and scientists are inding many interesting results and discovering many surprising phenomena. Because most natural and engineered systems are composed of multiple subsystems and layers of connectivity, it is important to consider these features in order to improve our understanding of such complex systems. Now the study of NON has become one of the important directions in network science.In this paper, we review recent studies on the new emerging area—NON. Due to the fast growth of this ield, there are many deinitions of diferent types of NON, such as interdependent networks,interconnected networks, multilayered networks, multiplex networks and many others. here exist many datasets that can be represented as NON, such as network of diferent transportation networks including light networks, railway networks and road networks, network of ecological networks including species interacting networks and food webs, network of biological networks including gene regulation network,metabolic network and protein–protein interacting network, network of social networks and so on. Among them, many interdependent networks including critical infrastructures are embedded in space, introducing spatial constraints. hus, we also review the progress on study of spatially embedded networks. As a result of spatial constraints, such interdependent networks exhibit extreme vulnerabilities compared with their non-embedded counterparts. Such studies help us to understand, realize and hopefully mitigate the increasing risk in NON. 相似文献
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Recently, series elasticity has been realized using pneumatics in human-robot interaction systems. Pneumatic circuits provide not only a flexible power transmission, but also the elastic element in a series elastic actuator (SEA). Pneumatic series elastic systems involve more than twice the number of parameters that influence system behaviors in comparison with rigid robotic systems. In this study, a position controller that eliminates the need of identifying a system model by employing the time delay estimation (TDE) technique is proposed for pneumatic SEA systems. The TDE technique is effective in compensating for system dynamics and all uncertainties involved in system behaviors without imposing computation load. TDE error is cancelled out through a learning way, which improves control performance and leads to asymptotic stability. A simulation study demonstrates the robustness of the proposed controllers against uncertainties imposed on the motor system as well as uncertainties on the end-effector. The simulation shows the efficacy of the learning compensation for TDE error. 相似文献
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《国家科学评论(英文版)》2014,(3)
Network science has atracted much atention in recent years due to its interdisciplinary applications. We witnessed the revolution of network science in 1998 and 1999 started with small-world and scale-free networks having now thousands of high-proile publications, and it seems that since 2010 studies of‘network of networks'(NON), sometimes called multilayer networks or multiplex, have atracted more and more atention. he analytic framework for NON yields a novel percolation law for n interdependent networks that shows that percolation theory of single networks studied extensively in physics and mathematics in the last 50 years is a speciic limit of the rich and very diferent general case of n coupled networks. Since then, properties and dynamics of interdependent and interconnected networks have been studied extensively, and scientists are inding many interesting results and discovering many surprising phenomena. Because most natural and engineered systems are composed of multiple subsystems and layers of connectivity, it is important to consider these features in order to improve our understanding of such complex systems. Now the study of NON has become one of the important directions in network science.In this paper, we review recent studies on the new emerging area—NON. Due to the fast growth of this ield, there are many deinitions of diferent types of NON, such as interdependent networks,interconnected networks, multilayered networks, multiplex networks and many others. here exist many datasets that can be represented as NON, such as network of diferent transportation networks including light networks, railway networks and road networks, network of ecological networks including species interacting networks and food webs, network of biological networks including gene regulation network,metabolic network and protein–protein interacting network, network of social networks and so on. Among them, many interdependent networks including critical infrastructures are embedded in space, introducing spatial constraints. hus, we also review the progress on study of spatially embedded networks. As a result of spatial constraints, such interdependent networks exhibit extreme vulnerabilities compared with their non-embedded counterparts. Such studies help us to understand, realize and hopefully mitigate the increasing risk in NON. 相似文献
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The effect of an imperfectly bonded laminar composite is examined in terms of the intensification of the torsional stresses operative near the imperfection which is assumed to be a circular shaped area. The laminar composite is modelled by four layers of different materials with the two outer layers being infinite in height and debonding occurs at the interface of the two inner layers. The analysis based on the application of Hankel transforms and the solution of a pair of dual integral equations can be easily extended to a multilayered system. Depending on the size of the layer thickness relative to the radius of the debonded area, delamination may take place either in a stable or unstable fashion. The analytical results also indicate that the influence of lamination tends to lower the stress intensity around an interface imperfection as compared to the stress state in a homogeneous solid containing the same imperfection. Numerical results are obtained for two special laminate geometries and discussed with reference to the pertinent parameters used in the current theory of fracture mechanics. 相似文献
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软件开发是一种创造性很强的活动,由于项目的一次性和独特性的特点,因此在软件项目实施完后,很多在项目实施过程中积累起来的知识经验就会随着项目的结束而消失,从而忽略了让开发小组从历史项目中学习和总结经验的机会。本文对项目后评价的定义以及实施意义进行了描述,并对两种不同的项目后评价方法作出了比较分析,最后以某高校学生选课系统项目为例,阐述了如何实施项目后评价工作,并为该项目的日后改进提出了意见和建议。 相似文献
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A theory is developed to describe the propagation of characteristics waves through an infinite slab of irregularities in a magneto-ionic medium. The theory makes use of the asymptotic Green's dyadic. The results show that mode conversion is possible through scattering from irregularities in an anisotropic background. Some special cases are discussed and an example is given. 相似文献
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朱效民 《科学对社会的影响》2010,(3):59-61
这两年流行一个“被”字,其实在科普领域也广泛存在着“被科普”的情况,表现在科普工作者更多地从自身主观愿望出发,较少考虑科普对象的需求、爱好、习惯、实际条件等, 相似文献
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