Lab Talk Schedule -- Summer 2007
- August 9th, 3pm: Real-time Smoke and Flame Detection in (infra-red) Video - A Special Case for Dynamic Texture Detection, by Ugur Toreyin, Bilkent University/University of Minnesota [details]
- August 14th, 2:30pm: Multi-Robot Coverage and Planetary Exploration, Ioannis Rekleitis, Canadian Space Agency. [details]
Lab Talk Schedule -- Spring 2007
| Date | Name | Abstract |
|---|---|---|
| 2/2/2007 |
Evan Shechter |
1. Fabrication update with an outline of some techniques used, and problems encountered. This will include some description of the photolithography/deposition/etching processes. |
| 2/9/2007 |
Steve Martin |
Interactive daylighting simulation can assist architects in designing more energy-efficient buildings. While general global illumination simulation techniques can be used, more effective utilization of compute time can be achieved via specialized algorithms. A selection of these specialized algorithms will be presented. |
| 2/16/2007 |
Yu Sheng |
Shadow Volumes is an important technique in real-time rendering of hard shadows. The talk will be about shadow volume algorithm making using of hardware support, such as stencil buffer. Additionally, the simulation of complex BRDFs using the algorithm will also be presented |
| 2/23/2007 |
Nilanjan Chakraborty |
A simple and compelling model of network of agents interactin via time-dependent communication links. The model finds application in a variety of fields including synchronization, swarming and distributed decision making. [Details] |
| 3/2/2007 |
Steve Berard |
In this paper we present a fully implicit time-stepping scheme for multibody systems with intermittent contact by incorporating the contact constraints as a set of complementarity and algebraic equations within the dynamics model. Two primary sources of stability and accuracy problems in time stepping schemes for differential complementarity models of multibody systems are the use of polyhedral representations of smooth bodies and the approximation of the distance function (arising from the decoupling of collision detection from the solution of the dynamic time-stepping subproblem). Even the simple example of a disc rolling on a table without slip encounters these problems. We model each object as an intersection of convex inequalities and write the contact constraints as a complementarity constraint between the contact force and a distance function dependent on the closest points on the objects. The closest points satisfy a set of algebraic constraints obtained from the KKT conditions of the minimum distance problem. These algebraic equations and the complementarity constraints taken together ensure satisfaction of the contact constraints. This enables us to formulate a fully implicit time-stepping scheme (i.e., we do not need to approximate the distance function) as a nonlinear complementarity problem (NCP). The resulting time-stepper is therefore more accurate and is the first fully implicit time-stepper that does not rely on a closed form expression for the distance function. We present examples validating our approach. |
| 3/9/2007 |
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| 3/16/2007 |
Nikhil Karnad |
We study the role of information available to the players on the outcome of the well-known cops and robbers game. The game takes place on a graph where the players move along the edges in discrete time. The cop wins if he moves onto the robber's vertex. In the standard formulation, it is assumed that the players can .see. each other at all times. A graph G is called cop-win if a single cop can capture the robber on G. We study the effect of reducing the cop's visibility. On the positive side, we show that a cop with small or no visibility can capture the evader on any cop-win graph (even if the robber still has global visibility). On the negative side, we show that the reduction in cop.s visibility can result in an exponential increase in the capture time. Finally, we start the investigation of the variant where the visibility powers of the two players are symmetric and present preliminary results. |
| 3/23/2007 |
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| 3/30/2007 |
Onur Tekdas |
Robots operating in a workspace can localize themselves by querying
nodes of a sensor-network deployed in the same workspace. This paper addresses the
problem of computing the minimum number and placement of sensors so
that the localization uncertainty at every point in the workspace is less than a
given threshold. We focus on triangulation based state estimation
where measurements from two sensors must be combined for
an estimate.
|
| 4/6/2007 |
Selma Sabanovic |
This talk discusses social robotics as a "hybrid science" that encourages interaction and collaboration among many different disiplines: engineering, computer science, the social sciences and humanities, design, the arts, etc. The accompanying article titled "Socially Distributed Perception: GRACE plays social tag at AAAI 2005" (Autonomous Robots, 2007, in print) is provided as an example of work done by an interdisciplinary team consisting of roboticists, a designer and a social scientist. As today's speaker is the social scientist involved, the talk will focus on her work in designing and evaluating human-robot interaction (HRI). She will discuss the use of observation and fine-grained behavioral video analysis of human-robot interaction "in the wild" as a way of testing initial design assumptions for social robots, as well as a method for analyzing emergent social interactions and a tool in iterative design. Futhermore, she will describe some of the challenges and benefits of interdisciplinary collaboration as a way of applying different, yet complementary, forms of expertise to social robot design. [Details] |
| 4/13/2007 |
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| 4/20/2007 |
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| 4/27/2007 |
Megha Gupta |
Digital microfluidic systems (DMFS) are an emerging class of lab-on-a-chip systems for biochemical analysis. A DMFS usually consists of a planar array of electrodes which uses electrowetting to manipulate discrete droplets on the array. We present a greedy algorithm for scheduling batch mode operations on ring layouts with bus-phase addressing. Here, each electrode is not individually addressable, instead a set of electrodes are all controlled by the same signal. Though this hardware design simplifies chip fabrication and reduces production costs, it increases the complexity of scheduling and routing droplets. This algorithm can handle both independent and chain reactions, and it is scalable to larger layouts. Sensor constraints under which droplets need to sit on sensor locations for specified amounts of time are also accounted for. We support the algorithm with simulation results for a few test cases on a ring layout. |
| 5/4/2007 |
Eric Meisner |
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| 5/11/2007 |
Lingzhi Luo |
Digital microfluidic systems (DMFS) are an emerging class of lab-on-a-chip systems that manipulate discrete droplets. A DMFS manipulates individual droplets of chemicals on a planar array of electrodes by using electrowetting. The chemical analysis is performed by repeatedly moving, mixing, and splitting droplets on the electrodes. We focus on minimizing the completion time of biochemical analyses by exploiting the parallelism among the operations. We consider a binary tree representation of chemical analyses to schedule operations and to determine the minimum number of mixers and storage units required to perform an analysis. Using pipelining, we overlap the mixing operations with input and transportation operations. Since mixers and storage units are two resources to perform biochemical analysis on DMFS, we consider the cases when we have only one mixer, and when we have zero storage units. In the first case with one mixer, we calculate the minimum number of storage units for the given analysis and design corresponding scheduling algorithm. In the second case, we find the minimum number of mixers required when we have zero storage units. We calculate the minimal number of mixers required to achieve minimum completion time. We also present a scheduling algorithm for the case with a specified number of mixers, and proved it to be optimal in minimizing mixing completion time. We demonstrate the benefits of our scheduling methods on an example DNA polymerase chain reaction (PCR) analysis. |
| 5/18/2007 |
Barbara Cutler |
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| 5/18/2007 |
Binh Nguyen |