Conferences, Lectures, & Seminars
Events for March
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Aerospace and Mechanical Engineering Seminar Series
Wed, Mar 04, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Xianyi Zeng, Postdoctoral Associate in the Department of Civil and Environmental Engineering at Duke University, Durham, NC
Talk Title: Multi-Robot Systems for Monitoring and Controlling Large Scale Environments A Variational Multiscale Finite Element Method for Nearly Incompressible Solids and Fluid-Structure Interactions
Series: Aerospace and Mechanical Engineering Seminar Series
Abstract: We present a new approach to stabilize the finite element methods for explicit transient solid mechanics in the nearly incompressible regime using linear simplicial finite elements, and present its extension to fluid-structure interactions. In these problems, triangular/tetrahedral elements are usually preferred because they allow efficient and automated mesh generation for complicated geometries. However, standard Galerkin formulation typically leads to volume locking or instability on these elements in the case of nearly incompressible solid dynamics.
To overcome these difficulties, we describe a stabilized method that is based on a mixed formulation, in which the usual momentum equation is complemented by a rate equation for the evolution of the pressure field. The stabilization term is derived using a variational multiscale approach for isotropic linear elastic materials, and it is shown to greatly improve the stability of the methods without decreasing the order of the accuracy. Next we extend the methodology to nonlinear elastic materials by properly linearizing the variational form, and then to viscoelastic materials by introducing internal variables. Extensive numerical results in these contexts are presented to assess the accuracy and stability properties of the proposed methods for general solid mechanics.
Finally, we describe a similar VMS-based finite element method for shock hydrodynamics, and conclude the presentation by coupling the two methods to perform challenging shock-solid interaction computations.
Biography: Xianyi Zeng obtained a BS in mathematics and applied mathematics from Peking University, and a PhD in computational and mathematical engineering from the Stanford University. Before joining the Civil and Environmental Engineering Department at Duke University as a postdoc, he worked on his dissertation in the Department of Aeronautics and Astronautics at Stanford University while pursuing the doctoral degree. Dr. Zeng has broad interests in computational mechanics and their applications, including computational gas dynamics, computational solid mechanics, fluid-structure interactions, and numerical modeling of inelastic materials, among others.
Host: Paul Ronney
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
Aerospace and Mechanical Engineering Seminar Series
Wed, Mar 11, 2015 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Mac Schwager, Assistant Professor in Mechanical Engineering and Systems Engineering at Boston University, Boston, MA
Talk Title: Multi-Robot Systems for Monitoring and Controlling Large Scale Environments
Series: Aerospace and Mechanical Engineering Seminar Series
Abstract: Groups of aerial, ground, and sea robots working collaboratively have the potential to transform the way we sense and interact with our environment at large scales. They can serve as eyes-in-the-sky for environmental scientists, farmers, and law enforcement agencies, providing critical, real-time information about dynamic environments and cityscapes. They can even help us to control large-scale environmental processes, autonomously cleaning up oil spills, tending to the needs of crop lands, and fighting forest fires, while humans stay at a safe distance. This talk will present an overview of research toward the realization of this vision, giving special attention to recent work on distributed optimization-based control algorithms for groups of aerial robots to monitor large-scale environments. I will describe a general optimization-based control design methodology for synthesizing practical, distributed robot controllers with provable stability and convergence properties. I will also describe low-level control techniques based on differential flatness to coordinate the motion of teams of quadrotors in an agile and computationally efficient manner. Experimental studies with groups of quadrotor robots flying both outdoors and indoors using these controllers will also be discussed.
Biography: Mac Schwager is an assistant professor in the Department of Mechanical Engineering and the Division of Systems Engineering at Boston University. He obtained his BS degree in 2000 from Stanford University, his MS degree from MIT in 2005, and his PhD degree from MIT in 2009. He was a postdoctoral researcher working jointly in the GRASP lab at the University of Pennsylvania and CSAIL at MIT from 2010 to 2012. His research interests are in distributed algorithms for control, perception, and learning in groups of robots and animals. He received the NSF CAREER award in 2014.
Host: Paul Ronney
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
2015 John Laufer Lecture
Thu, Mar 26, 2015 @ 01:00 PM - 03:00 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Harry L. Swinney, Sid Richardson Foundation Regents Chair in Department of Physics at College of Natural Sciences at University of Texas at Austin
Talk Title: Internal Gravity Wave Energy in the Oceans
Abstract: Internal gravity waves occur inside fluids whose density varies with depth, as happens in the atmosphere, oceans, and protoplanetary disks. In the oceans the internal waves produced by tidal flow over bottom topography travel thousands of kilometers, affecting ocean mixing and currents, and ultimately impacting the climate. However, it is difficult to make accurate estimates of the total internal wave energy in the oceans because of the complexity of ocean topography and the constructive and destructive interference of the waves. This talk presents results from laboratory experiments, numerical simulations, and ocean observations that yield insight into internal wave dynamics and improve estimates of the total internal wave energy.
Biography: Harry L. Swinney received a BS in physics from Rhodes College (1961) and a PhD in physics from Johns Hopkins University (1968). He held faculty appointments at New York University and City College of New York before moving in 1978 to the University of Texas at Austin. In the 1970s Swinney and J.P. Gollub found that fluid flow between concentric cylinders with the inner one rotating exhibited a transition from flow characterized by two incommensurate frequencies to chaotic flow; this was the first laboratory study of chaotic behavior. Later, at the University of Texas, Swinney showed that the strange (chaotic) attractors that had been discussed by theorists actually occur in laboratory systems. In the past three decades Swinneyâs research group has examined chaos and pattern formation in a variety of fluid, chemical, solid, granular, and biological systems. He was elected to the National Academy of Sciences in 1992. He is a Fellow of the American Physical Society, the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the Society of Industrial and Applied Mathematics. He was awarded the American Physical Society Fluid Dynamics Prize, the Society of Industrial and Applied Mathematics Moser Lecture Prize, the Lewis Fry Richardson Medal of the European Geophysical Union, and the Boltzmann Medal of the International Union of Pure and Applied Physics.
Location: Ronald Tutor Campus Center (TCC) - Ballroom A
Audiences: Everyone Is Invited
Contact: Valerie Childress
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor.
