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—Fast and periodic collection of aggregated data is of considerable interest for mission-critical and continuous monitoring applications in sensor networks. In the many-to-one communication paradigm known as convergecast, we consider scenarios where data packets are aggregated at each hop en route to a sink node along a tree-based routing topology and focus(More)
  • Shouwen Lai, Binoy Ravindran, Paul Plassmann, Y Thomas Hou, Anil Vullikanti, Yaling Yang +11 others
  • 2010
(ABSTRACT) In order to save energy consumption in idle states, low duty-cycled operation is widely used in Wireless Sensor Networks (WSNs), where each node periodically switches between sleeping mode and awake mode. Although efficient toward saving energy, duty-cycling causes many challenges , such as difficulty in neighbor discovery due to asynchronous(More)
We describe the design, implementation, and evaluation of EMBERS, an automated, 24x7 continuous system for forecasting civil unrest across 10 countries of Latin America using open source indicators such as tweets, news sources, blogs, economic indicators, and other data sources. Unlike retrospective studies, EMBERS has been making forecasts into the future(More)
Social unrest is endemic in many societies, and recent news has drawn attention to happenings in Latin America, the Middle East, and Eastern Europe. Civilian populations mobilize, sometimes spontaneously and sometimes in an organized manner, to raise awareness of key issues or to demand changes in governing or other organizational structures. It is of key(More)
A proliferation of mobile smartphone platforms, including Android devices, has triggered a rise in mobile application development for a diverse set of situations. Testing of these smartphone applications can be exceptionally difficult, due to the challenges of orchestrating production-scale quantities of smartphones, such as difficulty in managing thousands(More)
Simple diffusion processes on networks have been used to model, analyze and predict diverse phenomena such as spread of diseases, information and memes. More often than not, the underlying network data is noisy and sampled. This prompts the following natural question: how sensitive are the diffusion dynamics and subsequent conclusions to uncertainty in the(More)
Peer-to-peer (P2P) technology provides a scalable solution in multimedia streaming. Many streaming applications , such as IPTV and video conferencing, have rigorous constraints on end-to-end delays. Obtaining assurances on meeting those delay constraints in dynamic and heteroge-nous network environments is a challenge. In this paper, we devise a streaming(More)
The largest eigenvalue of the adjacency matrix of a network (referred to as the spectral radius) is an important metric in its own right. Further, for several models of epidemic spread on networks (e.g., the 'flu-like' SIS model), it has been shown that an epidemic dies out quickly if the spectral radius of the graph is below a certain threshold that(More)
We describe results from a computer simulation-based study of a large-scale, human-initiated crisis in a densely populated urban setting. We focus on the interaction between human behavior and the communication infrastructure in the aftermath of the crisis. We study the effects of sending emergency broadcasts immediately after the event, advising people to(More)