CS Colloq: Geoffrey Challen  Time: 11 AM - 12 PM Location: SAL 222 Talk title: Managing Sensor Network Resource Usage and Monitoring Active Volcanoes Speaker: Ph.D. candidate Geoffrey Challen Host: Prof. Ramesh Govindan Abstract: Sensor networks composed of large numbers of self-organizing embedded devices are an increasingly valuable tool for understanding our world. Deployed networks allow scientists to observe phenomena at a scale and resolution that challenge existing instrumentation. Some call this new instrument the macroscope. My project uses sensor networks to monitor active volcanoes. Due to the high data rates and stringent fidelity requirements of this application, providing output suitable for scientific analysis requires carefully directing the limited resources available at each node. In this talk I will present Lance, a general approach to bandwidth and energy management targeting reliable data collection for sensor networks. By combining an application-level determination of value with a system-level estimation of cost, Lance maximizes the value of the data returned to the application by optimally allocating bandwidth and energy devoted to signal collection. Lance's design decouples data collection policy from mechanism, allowing its optimization metrics to be customized to suit a variety of application goals. I will motivate and describe the Lance architecture, present results from the lab and the field, and discuss continuing efforts in this area, including single-node and network-wide architectures for distributed energy management. Bio: Geoffrey Challen (né Werner-Allen) is a Ph.D. Candidate in Computer Science at the Harvard University School of Engineering and Applied Sciences, advised by Matt Welsh. His research addresses the systems and networking challenges necessary to enable high-fidelity sensing applications, focusing specifically on maximizing the usage of the limited resources available to sensor network nodes. Working with geoscientists, he has helped perform three sensor network deployments on active Ecuadorean volcanoes. He built and maintains MoteLab, a wireless sensor network testbed used by researchers worldwide, and is a co-editor of a forthcoming book on sensor network deployments. Geoffrey is a 2009 Siebel Fellow, and a Resident Tutor at Eliot House. Revelant URL: http://www.eecs.harvard.edu/~werner/ Add this event to your Calendar (iCalendar file)

NN Faculty Meeting  Time: 12 PM - 1:30 PM Location: PHE 223 NN Faculty Meeting (Formerly Senior Faculty Meeting) Add this event to your Calendar (iCalendar file)

CS Colloq: Matt Zucker  Time: 4 PM - 5:30 PM Location: SSL 150 Talk Title: Combining Planning and Optimization for Rough Terrain Locomotion Speaker: Matt Zucker Host: Prof. Stefan Schaal Abstract: Motion planning for rough-terrain legged robots is a difficult task, not only due to the high dimensionality of robot configuration spaces, but also due to the variety of kinematic, dynamic, and collision constraints which need to be met at all times. While producing optimal walking behavior is desirable, searching the space of all posible robot motions remains intractible for non-trival robotic systems. In this talk, I describe a hierarchy of planning and optimization algorithms that decomposes the planning problem into a sequence of decisions which can be efficiently solved in order to produce real-time locomotion over rough terrain. My software architecture has been successfully used over the past year to guide the LittleDog quadruped robot over a variety of terrain types. Beyond this specific software architecture, I will also discuss the ways in which machine learning and optimization techniques can increase the speed and quality of motion planning algorithms, and highlight lessons learned on how to decompose a high-level planning task into a tractable set of sub-problems. Bio: Matt Zucker is a Ph.D. candidate at the Robotics Institute at Carnegie Mellon University, where he works on motion planning for high degree-of-freedom robotic platforms. His research focuses on leveraging numerical optimization and machine learning techniques in order to improve planning speed and quality. Before graduate school, Matt worked from 2000-2005 writing software for autonomous underwater vehicles at Bluefin Robotics Corporation in Cambridge, MA. He expects to graduate from the Robotics Institute in the summer of 2010. Add this event to your Calendar (iCalendar file)

CS Colloq: Prof. Vishal Misra  Time: 4 PM - 5:30 PM Location: SSL 150 Speaker: Prof. Vishal Misra, Columbia University Title: A Shapley Value approach to Internet Economics Host: Prof. Leana Golubchik Abstract: Internet service providers (ISPs) depend on one another to provide global network services. However, the profit-seeking nature of the ISPs leads to selfish behaviors that result in inefficiencies and disputes in the network. From a macroscopic view, this concern is at the heart of the Network Neutrality debate, which asks for an appropriate compensation structure that satisfies all types of ISPs and content providers. In this work, we design a profit-sharing mechanism based on the Shapley value originated from Coalition Game Theory. We derive closed-form profit solutions for structured ISP topologies and develop a dynamic programming procedure to calculate solutions for general topologies. Based on these solutions, we draw some implications on the bilateral settlements between ISPs. In practice, these results provide guidelines for ISPs to solve disputes and negotiate stable and incentive settlements and for governments to establish regulatory policies for the Internet industry. We then further extend the concept of Shapley Values to the scenario of Peer to Peer systems, where the Peers get compensated for reducing the cost of content distribution In general, the drawback of the Shapley Value mechanism is its computational complexity. We prove that this it is not the case for (very) large systems. As the number of peers receiving the service becomes large, the Shapley value received by each player approaches a hybrid fluid- atomic limit, leading to a simple closed form expression for any cost function, and simplifies even further in some scenarios of interest. We apply our technique to several scenarios for wired and wireless networks, proving that it leads to stable structure providing savings for bandwidth and energy costs. Bio: Vishal Misra is an Associate Professor in the Computer Science Department at Columbia University. He has received an NSF CAREER Award, a DoE CAREER Award and IBM Faculty Awards. His research emphasis is on mathematical modeling of computer systems, bridging the gap between practice and analysis. His recent work includes the areas of Internet economics, wireless, scheduling mechanisms and peer to peer systems. He has served as the guest editor for the Journal of Performance Evaluation, was TPC co-chair of Sigmetrics 2008, and serves on the editorial board of IEEE/ACM Transactions on Networking and Elsevir Journal of Performance Evaluation. Add this event to your Calendar (iCalendar file)

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