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October 2014

Colloquium-Jianjun Huang (WPI)-Interaction between Toroidal Swimmers in Stokes flow
Friday, 10/3/2014 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: The focus of this research has been devoted to study the interaction between two or more self-propelled toroidal swimmers in Stokes flow by applying the method of regularized Stokeslets and also study the effect of a nearby wall to the movement of a helical ring by using the method of regurlarized Stokeslets with images. In the study of the interaction between two or more toroidal swimmers, we interpret these as three-dimensional, zero Reynolds number analogues of finite vortex dipoles in an ideal fluid. Then, we examine the stability of relative equilibria that can form for these swimmers when they are initially placed in tandem or abreast. In addition, we examine the dynamics of the torus when a spherical cell body is placed at its center. This gives us an insight into the mechanical role of the transverse flagellum of dinoflagellates. Moreover, we show that the torus with a sphere moves more efficiently than one without.
For more information, e-mail ma-chair@wpi.edu.

Colloquium-Boris Rozovsky (Brown University)-Title TBA
Friday, 10/10/2014 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: TBA
For more information, e-mail ma-chair@wpi.edu.

Stochastic Analysis Common-Yanlai Chen (UMass Dartmouth)-Certified reduced basis method and reduced collocation method
Monday, 10/13/2014 4:00 PM-5:00 PM
Stratton Hall, 308
ABSTRACT: Models of reduced computational complexity is indispensable in scenarios where a large number of numerical solutions to a parametrized partial differential equation are desired in a fast/real-time fashion. These include simulation-based design, parameter optimization, optimal control, multi-model/scale analysis, uncertainty quantification etc. Thanks to an offline-online procedure and the recognition that the parameter-induced solution manifolds can be well approximated by finite-dimensional spaces, reduced basis method (RBM) and reduced collocation method (RCM) can improve efficiency by several orders of magnitudes. The accuracy of the RBM solution is maintained through a rigorous a posteriori error estimator whose efficient development is critical.

In this talk, I will give a brief introduction of the RBM and discuss recent and ongoing efforts to develop RCM, and the accompanying parametric analytical preconditioning techniques which are capable of improving the quality of the error estimation uniformly on the parameter domain, and speeding up the convergence of the reduced solution to the truth approximation significantly. These results are critical in certifying the accuracy of the reduced model and giving it a reliable predictive value.

For more information, e-mail ma-chair@wpi.edu.

November 2014

Colloquium-Gwen Spencer (Smith College)-Influence Beyond Exposure: Tackling an Economic Variant of Seeding Viral Spread
Friday, 11/7/2014 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: The problem of seeding "contagion" in social networks has attracted substantial attention for its connection to viral marketing. Simple information-spread models yield nice mathematical properties that allow theoretical algorithmic traction. This work often points to some form of "exposure" as the best paradigm for designing seed sets. While exposure-based seeding may spread awareness effectively, being aware of a behavior often doesn't result in a decision to adopt it. When environmental economists describe decisions to engage in green behaviors, when sociologists model norm-spread, and when game theorists consider choices to adopt cooperative strategies in repeated-game-play, a common more-complex spread mechanism emerges. What can we learn about how to virally market biking to work, adopting health-related behaviors, and cooperating at an equilibrium that is mutually beneficial?

I'll mention convergence results for this spread mechanism, (daunting) hardness results for the seeding question, and (heartening) computational results from heuristics derived by truncating an exact (inefficient) Integer Program. Compared to exposure-based seeding, the advantage of a seeding paradigm that establishes "critical mass locally" appears largest when the network is highly clustered (as social networks often are).

For more information, e-mail ma-chair@wpi.edu.

Colloquium-Mert Gürbüzbalaban (MIT)-Title TBA
Friday, 11/14/2014 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: TBA
For more information, e-mail ma-chair@wpi.edu.

December 2014

Colloquium-Jeremy Tyson (UIUC)-Title TBA
Friday, 12/5/2014 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: TBA
For more information, e-mail ma-chair@wpi.edu.

February 2015

Colloquium-Thaleia Zariphopoulou (UT Austin)-Title TBA
Friday, 2/20/2015 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: TBA
For more information, e-mail ma-chair@wpi.edu.

April 2015

Colloquium-Alex Iosevich (University of Rochester)-Title TBA
Friday, 4/10/2015 11:00 AM-12:00 PM
Stratton Hall, 203
ABSTRACT: TBA
For more information, e-mail ma-chair@wpi.edu.

 
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