Network simulation is an important tool for testing and evaluating wireless sensor network applications. Parallel simulation strategies improve the scalability of these tools. However, achieving high performance depends on reducing the synchronization overhead among simulation processes. In this paper, we present an optimistic simulation algorithm with support for backtracking and re-execution. The algorithm reduces the number of synchronization cycles to the number of transmissions in the network under test. We implement SnapSim, an extension to the popular Avrora simulator, based on this algorithm. The experimental results show that our prototype system improves the performance of Avrora by 2 to 10 times for typical network-centric sensor network applications, and up to three orders of magnitude for applications that use the radio infrequently. We also implement a distributed version of SnapSim, D-SnapSim, which runs on a cluster. The experimental results show that D-SnapSim further improves the performance of SnapSim by up to 10 times for applications that use the radio frequently.

CS Unplugged is a set of active learning activities designed to introduce fundamental computer science principles without the use of computers. The program has gained significant momentum in recent years, with proponents citing deep engagement and enjoyment benefits. With these benefits in mind, we initiated a one-year outreach program involving a local high school, using the CS Unplugged program as the foundation. To our disappointment, the results were at odds with our enthusiasm --- significantly. In this paper, we describe our approach to adapting the CS Unplugged materials for use at the high school level, present our experiences teaching it, and summarize the results of our evaluation.

Sensor networks serve as a powerful recruiting vehicle to excite and engage students in socially-relevant applications of computing. In this paper, we describe a technology-assisted scavenger hunt for introducing young learners --- from grade school through high school--- to sensor networks and computer science. The desired outcome is to expand students' content knowledge and positively impact their impressions of the discipline. We describe the outreach program and present promising evaluation results across three pilots involving 5th graders, 7th graders, and 11th graders.

In the domain of desktop software, design patterns have had a profound impact; they are applied ubiquitously across a broad range of applications. Patterns serve both to promulgate expert knowledge and as a vocabulary for documenting software design. The result is higher-quality software, reduced development effort, and improved documentation.

We present a testbed for visualizing the behavior of sensor network applications constructed using TinyOS 2.0. The testbed enables network designers to capture node-level runtime behaviors and to link the captured behaviors to form a network-level snapshot. A multi-resolution approach based on static selectors and dynamic filters helps to achieve manageable visualizations by including only those network nodes and program actions relevant to a global behavior of interest. We demonstrate the system's utility using a standard network example and summarize its resource usage and performance characteristics.

We present the NePTune approach and supporting system architecture for sensor network optimization. NePTune relies on a control loop strategy with performance monitoring, dynamic source code generation, and network reprogramming. We present an application of the system architecture and explore its efficacy in the context of a resource utilization problem - specifically, to minimize the memory consumption of a neighborhood management service. All experiments are conducted using a physical network testbed consisting of 80 Tmote Sky nodes.