MONDAY, APRIL 24, 2006

JICS/MATH POSITION CANDIDATE COLLOQUIUM

TIME: 9:00 a. m.
ROOM: Ayres Hall 102
SPEAKER: Professor Franz X. Tanner, Michigan Technological University
TITLE: Computational Engine Research
ABSTRACT: Environmental concerns, health issues and the limited resources of fossil fuels are the main driving forces behind today's engine research. The objectives of this research include the understanding and
description of the flow, spray and combustion processes in order to determine their influence on fuel efficiency, power output and pollution formation. Computer simulations are an expedient and economical way to contribute to the realization of these goals. In this talk, the mathematical formulation of dispersed multiphase flows used in engine simulations will be outlined, followed by a discussion of some of the author's modeling and simulation activities.

Also, an optimization method will be presented where engine operating conditions are sought which minimize the fuel consumption while meeting legislative emission mandates.


TUESDAY, APRIL 25, 2006

JICS/MATH POSITION CANDIDATE COLLOQUIUM

TIME: 3:35 p.m.
ROOM: Ayres Hall 214
SPEAKER: Professor Kathleen Feigl, Michigan Technological University
TITLE: Modeling and Simulation of Flow Processes involving Viscoelastic Fluids
ABSTRACT: Flow processes involving viscoelastic fluids are encountered in a wide range of fields, such as plastics, foods, and pharmaceuticals. Examples of viscoelastic fluids include polymer solutions and polymer melts, along with multiphase systems such as emulsions and polymer blends. In general, the microstructure or morphology of these fluids influences the flow behavior during processing, the rheological properties and material functions (e.g. shear and elongational viscosity), and the properties and quality of the final product. The development of efficient and accurate simulation algorithms for studying viscoelastic flows, including the development of rheological models to describe the complex stress-strain relationship in the fluid caused by its microstructure or morphology, is a main challenge in viscoelastic fluid mechanics and rheology. In this talk,
several simulation algorithms and investigations involving viscoelastic fluids are discussed, including (i) conventional simulations of polymer flows using macroscopic rheological models to describe the stress-strain relationships, (ii) micro-macro (or multiscale) simulations of polymer flow in which a molecular-based, or microscopic, model for polymer stress is coupled to the conservation equations from continuum mechanics, and (iii) simulations of the deformation of surfactant-covered droplets in dilute emulsions. In each case, simulation results are presented and compared to experimental data.

Refreshments will be served in Ayres 119 at 3:00 p.m.

WEDNESDAY, APRIL 26, 2006

TOPOLOGY SEMINAR

TIME: 1:25 p.m. – 2:15 p.m.
ROOM: Ayres Hall 309A
SPEAKER: Dr. Nikolay Brodskiy
TITLE: Amenability of countable groups III


JICS/MATH POSITION CANDIDATE COLLOQUIUM

TIME: 3:35 p.m.
ROOM: Ayres Hall 214
SPEAKER: Professor M. Rauf Gungor, University of Massachusetts, Amherst
TITLE: Challenges and Opportunities for Mutiscale Modeling of Materials Physical Behavior in
Nanotechnological Devices
ABSTRACT: In today’s nanotechnological devices, the development of new self-assembling materials processing methods and materials reliability have become the major challenges against the scaling of the device technologies further into deep-nanometer scale. Multiscale computational methods based on mathematical/physical modeling are indispensable research tools for understanding the materials physical behavior at the nanometer scale and the underlying atomic-scale mechanisms, as such analysis is generally not accessible through experimental methods. Although computational scientific research is taking advantage of decreasing relevant dimensions of computational domains and increasing computational power of modern computers, due to the physical and mathematical complexity of materials models, development of sophisticated numerical methods and algorithms, such as domain decomposition, front tracking, multiscale integration, mesh generation, to achieve the required accuracy and self-consistency remains to be the major challenge. In this presentation, I will give an overview of materials reliability problems in nanoscale devices with a special reference to microelectronic devices from both academic and industrial perspectives. I will also give examples of the multiscale computational analysis from our current and past research that addresses fundamental understanding of the materials physical response to combined effects of electric field and mechanical stress, as well as the predictive modeling of electromigration and thermomechanical materials reliability in nanoscale device structures. Some of the research highlights include a comprehensive analysis of migration and morphological evolution of voids in metallic thin-film interconnects under the combined action of electric field and mechanical stress; strain relaxation in metallic thin films in response to a wide range of applied strains mediated by ductile void growth as well as formation of nanocrystalline domains; and detailed multi-scale modeling of device structures that predict the back-end and front-end materials reliability in modern microelectronic technologies.

Refreshments will be served in Ayres 119 at 3:00 p.m.


FRIDAY APRIL 28, 2006

TOPOLOGY SEMINAR

TIME: 12:20 p.m. – 1:10 p.m.
ROOM: Ayres Hall 209B
SPEAKER: Dr. Craig Jensen, University of New Orleans
TITLE: Brownstein-Lee Conjecture
ABSTRACT: The pure symmetric automorphism group of a free group consists of those automorphisms which send each generator to a conjugate of itself. Another way to view this group is as the group of motions of n unknotted, unlinked circles where each circle returns to its original position. In 1991, Alan Brownstein and Ronnie Lee calculated the first and second cohomology groups (including the cup product structure going from the first to the second) of the group of pure symmetric automorphisms of a free group of finite rank. They further conjectured what the entire cohomology ring should be. Jon McCammond, John Meier and I verified this conjecture.