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Events for February 11, 2010
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One Week to E-Week! - Engineering Date Auction
Thu, Feb 11, 2010
Viterbi School of Engineering Student Organizations
University Calendar
Get ready for the 6th Annual Engineering Date Auction! This year, seventeen stunning and talented engineers, along with their limited V-ball tickets, will being auctioned on Thursday, 2/18, to raise money for Aviva*. With Viterbi Ball & Banquet tickets SOLD OUT, be prepared (with your checkbooks ready) for a crazily entertaining night. Auctionee profiles can be found online at http://www-scf.usc.edu/~sweusc/auction/auctionees.htm
Audiences: Everyone Is Invited
Contact: E-WEEK 2010
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Structure-Property Relations in Polymers for Gas Separations
Thu, Feb 11, 2010 @ 12:45 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Lyman Handy Colloquium SeriesPresentsBenny D. FreemanUniversity of Texas at AustinAbstract:This presentation will discuss structural features important in the use of polymers as rate-controlling membranes for gas separations. In particular, materials having desirable combinations of high permeability and high selectivity based upon solubility selectivity (e.g., butane removal from natural gas, CO2 separation from H2 or N2) or diffusivity selectivity (e.g., CO2 removal from natural gas) will be presented. For example, cross-linked poly(ethylene oxide) (XLPEO) polymers, which are flexible, rubbery polymers identified as promising materials to remove polar and acid gases, such as CO2, from mixtures with light gases, such as H2. One member of this family of materials was reported to have a CO2 permeability coefficient of approximately 500 Barrer and a CO2/H2 mixed gas selectivity of 30 at -20C.1 Such materials achieve high selectivity based upon their high solubility selectivity favoring CO2 transport. Prepared by cross-linking low molecular weight poly(ethylene glycol) diacrylate with other poly(ethylene oxide) acrylates, XLPEO polymers exhibit good separation properties thanks to ethylene oxide group interaction with CO2 and suppression of crystallinity normally found in high molecular weight, linear poly(ethylene oxide).
Polymers can also be tailored to achieve high selectivity based upon high diffusivity selectivity. In this case, highly rigid, glassy polymers with proper free volume element size and size distribution are desirable. Polyimides with ortho-position functional groups may be solution-processed to form conventional films and membranes. Such materials can undergo thermal rearrangement to form highly rigid benzoxazole or benzithiazole structures having very high permeability coefficients and high selectivity. For example, one member of this family was prepared having a CO2 permeability coefficient of 1610 Barrer and a CO2/CH4 selectivity, under mixed gas conditions, of 42-46, depending on the partial pressure of CO2 in the mixture.2 These thermally rearranged (TR) polymers are insoluble in common solvents, giving them good chemical stability, and highly thermally stable, which are important attributes for membranes that would be used in chemically or thermally aggressive environments.
The overarching message from this presentation is that polymers can be exquisitely tuned to have favourable permeation properties. Materials may be designed to achieve high selectivity by being more soluble to one molecule than another or by having a strong ability to sieve gas molecules based on minute differences in gas molecule size. In both cases, the structure of the polymer may be optimized to permit rapid permeation.Location: James H. Zumberge Hall Of Science (ZHS) - 159
Audiences: Everyone Is Invited
Contact: Petra Pearce Sapir
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CS DLS: Prof. Tuomas Sandholm
Thu, Feb 11, 2010 @ 04:00 PM - 05:50 PM
Thomas Lord Department of Computer Science
Conferences, Lectures, & Seminars
Talk title: Design and Algorithms for Modern Kidney ExchangesSpeaker: Prof. Tuomas Sandholm (Carnegie Mellon University)Host: Prof. Milind TambeAbstract:
In kidney exchanges, patients with kidney disease can obtain compatible donors by swapping their own willing but incompatible donors. The clearing problem involves finding a social welfare maximizing set of non-overlapping short cycles. We proved this NP-hard. It was one of the main obstacles to a national kidney exchange. We presented the first algorithm capable of clearing these exchanges optimally on a nationwide scale. The key was incremental problem formulation because the formulation that gives tight LP bounds is too large to even store. On top of the branch-and-price paradigm we developed techniques that dramatically improve runtime and memory usage. Furthermore, clearing is actually an online problem where patient-donor pairs and altruistic donors appear and expire over time. We developed trajectory-based online stochastic optimization algorithms (that use our optimal offline solver as a subroutine) for this. I will discuss design parameters and tradeoffs. Our best online algorithms outperform the current practice of solving each batch separately. I will share experiences from using our algorithms as the clearing engine of the largest two kidney exchange networks in the US. We also introduced several design enhancements to the exchanges. For one, we used our algorithms to launch the first never-ending altruistic donor chains. I am also helping UNOS design the nationwide kidney exchange, which will use our algorithms; I will discuss current design considerations.The talk covers material from the following papers:* Online Stochastic Optimization in the Large: Application to Kidney
Exchange. IJCAI-09. (With Awasthi, P.)* A Nonsimultaneous, Extended, Altruistic-Donor Chain. New England
Journal of Medicine 360(11), March 2009. (With Rees, M., Kopke, J., Pelletier, R., Segev, D., Rutter, M., Fabrega, A., Rogers, J., Pankewycz, O., Hiller, J., Roth, A., Ünver, U., and Montgomery, R.)* Clearing Algorithms for Barter Exchange Markets: Enabling Nationwide
Kidney Exchanges. EC-07. (With Blum, A. and Abraham, D.)Bio:
Tuomas Sandholm is Professor in the Computer Science Department at Carnegie Mellon University. He has published over 380 papers on electronic commerce; game theory; artificial intelligence; multiagent systems; auctions and exchanges; automated negotiation and contracting; coalition formation; voting; safe exchange; normative models of bounded rationality; resource-bounded reasoning; machine learning; networks; and combinatorial optimization. He has 19 years of experience building optimization-based electronic marketplaces, and has fielded several of his systems. He is also Founder, Chairman, and Chief Scientist of CombineNet, Inc., which has commercialized over 800 large-scale generalized combinatorial auctions, with over $50 billion in total spend and over $6 billion in generated savings. He received the Ph.D. and M.S. degrees in computer science from the University of Massachusetts at Amherst in 1996 and 1994. He earned an M.S. (B.S. included) with distinction in Industrial Engineering and Management Science from the Helsinki University of Technology, Finland, in 1991. He is recipient of the National Science Foundation Career Award, the inaugural ACM Autonomous Agents Research Award, the Alfred P. Sloan Foundation Fellowship, and the Computers and Thought Award. He is Fellow of the ACM and AAAI.Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: CS Front Desk
