Seminars and Colloquia by Series

Series: Other Talks
Saturday, November 3, 2012 - 13:00 , Location: Emory University , Featured Speaker Penny Haxell , University of Waterloo , Organizer: Xingxing Yu
Emory University, the Georgia Institute of Technology and Georgia State University, with support from the National Security Agency and the National Science Foundation, are hosting a series of 9 mini-conferences from November 2010 - April 2013. The seventh in the series will be held at Emory University on November 3-4, 2012. This mini-conference's featured speaker is Dr. Penny Haxell, who will give two one-hour lectures. Additionally, there will be five one-hour talks and seven half-hour talks given by other invited speakers. See all titles, abstracts, and schedule.
Series: Other Talks
Friday, November 2, 2012 - 14:00 , Location: Skiles 006 , John Etnyre , School of Mathematics, Georgia Tech , Organizer: John Etnyre
This will be an afternoon event, and light refreshments will be served. Students will visit our school, hear about graduate degree options available in the School of Mathematics, learn about requirements for admission, as well as meet our faculty and current graduate students. Check the schedule of events.
Series: Other Talks
Tuesday, October 30, 2012 - 10:00 , Location: Skiles 114 , Christine Heitsch , Georgia Tech , Organizer: Christine Heitsch
A discussion of possible papers for upcoming weeks.
Series: Other Talks
Tuesday, October 23, 2012 - 10:00 , Location: Skiles 114 , David Murrugarra , Georgia Tech , Organizer: Christine Heitsch
A discussion of  the paper "Boolean network models of cellular regulation: prospects and limitations" by Bornholdt (2008).
Series: Other Talks
Tuesday, October 9, 2012 - 13:00 , Location: MRDC Building, Room 4211 , Zi Chen , Washington University in St. Louis , Organizer: John McCuan

<a href=" target="_blank">Speaker's Bio</a>.
Host: David Hu, School of Mechanical Engineering

Mechanical forces play a key role in the shaping of versatile morphologies of thin structures in natural and synthetic systems. The morphology and deformation of thin ribbons, plates and rods and their instabilities are systematically investigated, through both theoretical modeling and table-top experiments. An elasticity theory combining differential geometry and stationarity principles is developed for the spontaneous bending and twisting of ribbons with tunable geometries in presence of mechanical anisotropy. Closed-form predictions are obtained from this theory with no adjustable parameters, and validated with simple, table-top experiments that are in excellent agreement with the theoretical predictions. For large deformation of ribbons and plates, a more general theory is developed to account for mechanical instability (slap-bracelet type) induced by geometric nonlinearity, due to the competition between inhomogeneous bending and mid-plane stretching energy. This comprehensive, reduced parameter model leads to unique predictions about multistability that are validated with a series of table-top experiments. Furthermore, this study has been extended to interpret a different type of snap-through instability that the Venus flytrap has been actively employing to capture insects for millions of years, and the learnt principle is used to guide the design of bio-mimetic flytrap robot.
Series: Other Talks
Tuesday, October 9, 2012 - 10:00 , Location: Skiles 114 , David Murrugarra , Georgia Tech , Organizer: Christine Heitsch
A discussion of the paper "External Control in Markovian Genetic Regulatory Networks" by Datta et al (2003).
Series: Other Talks
Monday, October 8, 2012 - 13:05 , Location: Klaus 1116W , Stephen Young , University of Louisville, Kentucky , , Organizer: Prasad Tetali
Expander graphs are known to facilitate effective routing and most real-world networks have expansion properties. At the other extreme, it has been shown that in some special graphs, removing certain edges can lead to more efficient routing. This phenomenon is known as Braess¹s paradox and is usually regarded as a rare event. In contrast to what one might expect, we show that Braess¹s paradox is ubiquitous in expander graphs. Specifically, we prove that Braess¹s paradox occurs in a large class of expander graphs with continuous convex latency functions. Our results extend previous work which held only when the graph was both denser and random and for random linear latency functions. We identify deterministic sufficient conditions for a graph with as few as a linear number of edges, such that Braess¹s Paradox almost always occurs, with respect to a general family of random latency functions.  Joint work with Fan Chung and Wenbo Zhao. (* Note that this is an ARC/Theory Seminar and is in Klaus 1116W *)
Series: Other Talks
Friday, October 5, 2012 - 16:00 , Location: **Emory University**, Mathematics and Science Center, Rm W201 , Mathias Schacht , Math, University of Hamburg, Germany , Organizer: Prasad Tetali
(**This is at Emory and is a joint Emory - Georgia Tech Combinatorics Seminar. **)  The KLR conjecture of Kohayakawa, Luczak, and Rödl is a statement that allows one to prove that asymptotically almost surely all subgraphs of the random graph G(n,p) satisfy an embedding lemma which complements the sparse regularity lemma of Kohayakawa and Rödl. We prove a variant of this conjecture which is sufficient for most applications to random graphs. In particular, our result implies a number of recent probabilistic threshold results. We also discuss several further applications. This joint work with Conlon, Gowers, and Samotij. 
Series: Other Talks
Friday, October 5, 2012 - 11:00 , Location: MRDC, Room 4211 , Evelyn Wang , Department of Mechanical Engineering, MIT , Organizer: John McCuan

Host: David Hu. Refreshments will be served.
<a href=" target="_blank">Speaker's Bio</a>

Nanoengineered surfaces offer new possibilities to manipulate fluidic and thermal transport processes for a variety of applications including lab-on-a-chip, thermal management, and energy conversion systems. In particular, nanostructures on these surfaces can be harnessed to achieve superhydrophilicity and superhydrophobicity, as well as to control liquid spreading, droplet wetting, and bubble dynamics. In this talk, I will discuss fundamental studies of droplet and bubble behavior on nanoengineered surfaces, and the effect of such fluid-structure interactions on boiling and condensation heat transfer. Micro, nano, and hierarchical structured arrays were fabricated using various techniques to create superhydrophilic and superhydrophobic surfaces with unique transport properties. In pool boiling, a critical heat flux >200W/cm2 was achieved with a surface roughness of ~6. We developed a model that explains the role of surface roughness on critical heat flux enhancement, which shows good agreement with experiments. In dropwise condensation, we elucidated the importance of structure length scale and droplet nucleation density on achieving the desired droplet morphology for heat transfer enhancement. Accordingly, with functionalized copper oxide nanostructures, we demonstrated a 20% higher heat transfer coefficient compared to that of state-of-the-art dropwise condensing copper surfaces. These studies provide insights into the complex physical processes underlying fluid-nanostructure interactions. Furthermore, this work shows significant potential for the development and integration of nanoengineered surfaces to advance next generation thermal and energy systems.
Series: Other Talks
Tuesday, October 2, 2012 - 11:00 , Location: Skiles 114 , David Murrugarra , Georgia Tech , Organizer: Christine Heitsch
A discussion of the paper "Probabilistic Boolean networks: a rule-based uncertainty model for gene regulatory networks" by Shmulevich et al.