Evolving networks for social optima in the “weakest link game”

Previous models have applied evolving networks based on node-level “copy and rewire” rules to simple two player games (e.g. the Prisoner’s Dilemma). It was found that such models tended to evolve toward socially optimal behavior. Here we apply a similar technique to a more tricky co-ordination game (the weakest link game) requiring interactions from several players (nodes) that may play several strategies. We define a variant of the game with several equilibria—each offering increasing social benefit. We found that the evolving network functions to select and spread more optimal equilibria while resisting invasion by lower ones. Hence the network acts as a kind of “social ratchet” selecting for increasing social benefit. Such networks have applications in peer-to-peer computing and may have implications for understanding social systems.

基于量子隐形传态的数据链路层选择重传协议

提出了数据链路层中基于量子隐形传态的量子选择重传协议.即在量子网络的两个站点进行通信时,发送方通过加入辅助量子比特位,把一系列的量子比特分成m帧.在连续传送m个量子帧后,接收方根据发送方所提供的经典信息,判断自己是否收到正确无误的量子帧.若接收方收到了正确的量子帧, 则用量子信道返回确认帧;若接收方没有收到量子帧或收到错误的量子帧, 则不返回否认帧.发送方在设定的时间内,根据收到的确认帧判断需要重发的量子帧.由于只重发丢失或出错的量子帧,该协议减少了通信过程的传播时延,提高了通信效率.在整个通信过程中,仅用经典信道传送测量信息,从而降低了经典信道的负担.     

一种分布反射型大容量WDM星形单跳网

针对现有分布反射型WDM星形单跳网结构上存在的问题,本文提出了一种新的分布反射型WDM星形单跳网.这种WDM网络不仅抗毁性能好、可靠性高,而且网络容量大、组网灵活性强,可实现网络的在线扩容、升级,为未来大容量WDM局域网提供了一个理想的选择.文章首先论述了该分布反射型大容量WDM星形单跳网的结构,其次分析了网络中各个节点之间的通信,进而计算了网络所支持的最大节点数,最后对全文进行了总结.     

基于模型-证据链的科学论证教学研究进展

科学论证教学因致力于学生高阶思维发展和关键能力培养,在国际理科教育教学中备受关注。以“电离理论的产生”主题为例,较为细致地介绍了模型证据链(MEL)这一新颖的科学论证教学模式的结构和要素。在此基础上,深入剖析了该教学模式的功能与价值,即通过证据评估模型的方式发展学生基于模型的推理能力,从而提升批判性评价的水平,并进而促进概念转变。     

Helical and Localised Buckling in Twisted Rods: A Unified Analysis of the Symmetric Case

We review the geometric rod theory for the case of a naturallystraight, linearly elastic, inextensible, circular rod suffering bendingand torsion but no shear. Our primary focus is on the post-bucklingbehaviour of such rods when subjected to end moment and tension.Although this is a classic problem with an extensive literature, datingback to Kirchhoff, the usual approach tends to neglect the physicalinterpretation of solutions (i.e., rod configurations) to the modelsproposed. Here, we explicitly compute geometrical properties of buckledrods. In a unified approach, making use of Kirchhoff's dynamic analogy,both the classical helical and the more recently investigated localisedbuckling are considered. Special attention is given to a consistenttreatment of concepts of link, twist and writhe.     

Milnor link invariants and quantum 3-manifold invariants

Let be the 3-manifold invariant of Le, Murakami and Ohtsuki. We show that , where denotes terms of degree , if M is a homology 3-sphere obtained from by surgery on an n-component Brunnian link whose Milnor -invariants of length vanish.?We prove a realization theorem which is a partial converse to the above theorem.?Using the Milnor filtration on links, we define a new bifiltration on the vector space with basis the set of oriented diffeomorphism classes of homology 3-spheres. This includes the Milnor level 2 filtration defined by Ohtsuki. We show that the Milnor level 2 and level 3 filtrations coincide after reindexing. Received: October 23, 1998.     

复杂网络链路可预测性:基于特征谱视角

近年来链路预测的理论和实证研究发展迅速,大部分工作关注于提出更精确的预测算法.事实上,链路预测的前提是网络的结构本身能够被预测,这种"可被预测的程度"可以看作是网络自身的基本属性.本文拟从特征谱的视角去解释网络的链路可预测性,并刻画网络的拓扑结构信息,通过对网络特征谱进行分析,构造了复杂网络链路可预测性评价指标.通过该指标计算和分析不同网络的链路可预测性,能够在选择算法前获取目标网络能够被预测的难易程度,解决到底是网络本身难以预测还是预测算法不合适的问题,为复杂网络与链路预测算法的选择和匹配问题提供帮助.     

微小型无线光电传感网络的实验系统设计

基于nRF905低功耗、高灵敏度无线收发的一体芯片实现了一种微小型无线光电传感网络实验系统。讨论了实验系统的硬件节点、网络通信协议及软件的设计。实验结果表明,在19.2kbit/s速率下,系统中任意两节点可实现30m(室内)至150m(室外空旷地带)范围内的无线通信。该系统具有硬件设计简单、软件及其协议编程方便等优点,可微型化、低成本的应用于无线光电传感器网络系统。     

Sarkisov links for index 1 Fano 3-folds in codimension 4

We classify Sarkisov links from index 1 Fano 3-folds anticanonically embedded in codimension 4 that start from so-called Type I Tom centres. We apply this to compute the Picard rank of many such Fano 3-folds.