Analysis of a Cone-Based Distributed Topology Control Algorithm for Wireless Multi-hop Networks

The topology of a wireless multi-hop network can be controlled by varying the transmission power at each node. In this paper, we give a detailed analysis of a cone-based distributed topology control algorithm. This algorithm, introduced in [16], does not assume that nodes have GPS information available; rather it depends only on directional information. Roughly speaking, the basic idea of the algorithm is that a node $u$ transmits with the minimum power $p_{u,\alpha}$ required to ensure that in every cone of degree $\alpha$ around $u$, there is some node that $u$ can reach with power $p_{u,\alpha}$. We show that taking $\alpha = 5\pi/6$ is a necessary and sufficient condition to guarantee that network connectivity is preserved. More precisely, if there is a path from $s$ to $t$ when every node communicates at maximum power, then, if $\alpha <= 5\pi/6$, there is still a path in the smallest symmetric graph $G_\alpha$ containing all edges $(u,v)$ such that $u$ can communicate with $v$ using power $p_{u,\alpha}$. On the other hand, if $\alpha > 5\pi/6$, connectivity is not necessarily preserved. We also propose a set of optimizations that further reduce power consumption and prove that they retain network connectivity. Dynamic reconfiguration in the presence of failures and mobility is also discussed. Simulation results are presented to demonstrate the effectiveness of the algorithm and the optimizations.Comment: 10 page

Promoting Nutrition and Wellness Statewide Through an Electronic Newsletter

The Words on Wellness (WOW) newsletter was designed as an electronic newsletter intended to provide research-based nutrition and wellness information to Iowans. An evaluation was conducted to assess to what extent the newsletter is being used by its readership and whether readers are making lifestyle changes as a result. Those who completed the online survey (n = 154) report making lifestyle changes and finding the information to be current, understandable, and relevant to their lives. These results indicate that the use of indirect nutrition and wellness educational materials (i.e., a newsletter) is effective in promoting research-based information that results in self-reported behavior change

Techniques of Technological Forecasting

Technological forecasts can improve decisions through clearer delineation of future technological opportunities and threats. A review of the various methods applicable in thc area of technology is presented.The limitations of a particular technique must be clearly understood before it is applied. Some defence applications have also been discussed

Stability of Resonant Opto-Mechanical Oscillators

We theoretically study the frequency stability of an opto-mechanical radio frequency oscillator based on resonant interaction of two optical and one mechanical modes of the same optical microcavity. A generalized expression for the phase noise of the oscillator is derived using Langevin formalism and compared to the phase noise of existing electronic oscillators.Comment: 6 pages, 1 figur