基于可连Cell的无线传感器网络拓扑控制算法

在无线传感器网络的拓扑控制(TC)中,基于Cell的TC算法被认为是一类可以节省传感器节点能量并延长网络生命周期的方法,但是其需要较多的骨干网节点并且无法保证连通性.通过分析现今算法的内在局限性,提出了一种1-Con思想:当一个Cell的头节点被加入当前骨干网时,所有其可以连接的Cell使用该节点连入拓扑结构,然后此新骨干网递归地继续扩大.基于此思想,设计了一种基于可连Cell的拓扑控制算(CCTC),并从理论上证明:1)CCTC可以保证其所形成的拓扑结构维持网络连通;2)每一轮用于形成骨干网的工作节点非常少.CCTC的计算复杂度是线性的,空间复杂度和信息交换量都是常数量级.仿真实验同样显示,CCTC可以在提供良好鲁棒性和较少的消息交换的情况下,更有效地节省节点能耗并延长网络生命周期.     

The internship crisis: An uncommon urgency to build a common solution.

The internship imbalance is a problem of grave individual and professional concern. As the imbalance continues and deepens, many concerted efforts have been directed toward mitigating the imbalance by addressing factors associated with increased demand and insufficient supply of internship positions. These efforts have required the collaboration of groups and organizations that in the past pursued different aims and agendas. Hatcher (this issue, pp. 126–140) moves these efforts forward greatly, by conceptualizing the internship imbalance as a specific example of a scarce resource shared by a large community (a Common Pool Resource) and by providing a framework for development of a governance structure to manage this common resource. This commentary expands on Hatcher (this issue) by highlighting important structural and attitudinal issues underlying the imbalance problem that are evoked by attempts to address the imbalance, and which must be considered when formulating a comprehensive and integrated solution, particularly one that includes an additional governance structure dependent on interorganizational collaboration. (PsycINFO Database Record (c) 2011 APA, all rights reserved)