Seminars are held Tuesdays and Thursdays in POB 6.304 from 3:30-5:00 pm, unless otherwise noted. Speakers include scientists, researchers, visiting scholars, potential faculty, and ICES/UT Faculty or staff. Everyone is welcome to attend. Refreshments are served at 3:15 pm.
Thursday, Oct 27, 2016 from 3:30PM to 5PM
Finite Element Modeling for Ocean Acoustics Applications
by Marcia J. Isakson
Applied Research Laboratories, The University of Texas at Austin
Since electromagnetic propagation in seawater is very limited, acoustics provide the primary means of remote sensing and communication under the ocean. However, the ocean is a complex environment with large variations both temporally and spatially. Historically, acoustic propagation and scattering for underwater acoustics have been modeled using approximations to the Helmholtz equation. However, with the increase of computing power, finite element models are now accessible for the large-scale problems in ocean acoustics. These models are particularly powerful in these applications because they can capture the complexity of the environment. This talk will provide an overview of the application of finite element modeling for ocean acoustics applications in the underwater environment as well as a glimpse into the future of the discipline.
Marcia J. Isakson (M’09) received the B.S. degree in engineering physics and mathematics from the United States Military Academy at West Point, West Point, NY, USA, in 1992. Upon graduation, she was awarded a Hertz Foundation Fellowship. She earned her master’s degree and Ph.D. in physics from The University of Texas at Austin in 1994 and 2002, respectively. From 1994 to 1997, she served as a captain in the U.S. Army. Currently, Dr. Isakson is a Research Scientist at Applied Research Laboratories as well as a lecturer for the Department of Mechanical Engineering. Her research interests include ocean sediment acoustics, finite element modeling, acoustic scattering, and propagation. Dr. Isakson is a Fellow of the Acoustical Society of America (ASA) and has recently been elected president of the society. She also serves as a Distinguished Lecturer and co-chair of the Underwater Acoustics Technology Committee for the IEEE Oceanic Engineering Society.
ICES Seminar-Numerical Analysis Series
Friday, Oct 28, 2016 from 1PM to 2PM
A Sparse Grid Discontinuous Galerkin Method for High-Dimensional Transport Equations
by Yingda Cheng
Professor, Michigan State University
In this talk, we present a sparse grid discontinuous Galerkin (DG) scheme for transport equations and applied it to kinetic simulations. The method uses the weak formulations of traditional Runge-Kutta DG schemes for hyperbolic problems and is proven to be $L^2$ stable and convergent. A major advantage of the scheme lies in its low computational and storage cost due to the employed sparse finite element approximation space. This attractive feature is explored in simulating Vlasov and Boltzmann transport equations. We also discuss extension of the scheme to adaptive sparse grid methods.
Hosted by Irene Gamba
ICES Seminar-Molecular Biophysics Series
Monday, Oct 31, 2016 from 2PM to 3PM
Continuum and atomistic simulations of protein mediated membrane deformation
by Michael Grabe
Cardiovascular Research Institute, UC-San Francisco
In this talk I will describe recent advances we have made in using fast, continuum elasticity theory to describe membrane deformations around proteins. I will show that our calculations match the deformations predicted from all atom molecular dynamics simulations for two proteins: gramicidin (a small antibiotic ion channel) and nhTMEM16 (a member of the calcium activated chloride channel family). Our calculations reveal that nhTMEM16 produces large distortions in the membrane potentially related to its ability to scramble lipids from one leaflet to the other. This hypothesis is supported by atomistic simulations in which we observe lipids flipping from one leaflet to the other. Experiments to test the lipid flipping mechanism in a mammalian TMEM16 family member will also be discussed.
Hosted by Ron Elber
Tuesday, Nov 8, 2016 from 3:30PM to 5PM
Innovation in patient care - the HeartFlow story
by Christopher Zarins, MD
Co-founder and Sr. VP for Medical Affairs, HeartFlow, Inc.; Professor of Surgery, Emeritus, Stanford University
Computational analysis of coronary blood flow based on coronary CT angiography imaging data provides quantitative information on the functional significance of coronary artery lesions. This enables physicians to determine whether or not a patient needs coronary artery stenting or bypass surgery non-invasively, thus avoiding the need for coronary angiography in many patients. This technology, known as HeartFlow FFRCT analysis, was FDA approved for clinical use in 2014 and is now being used to evaluate patients in the US, Europe and Japan. Recently, a HeartFlow production facility has been established in Austin. The scientific and clinical basis for HeartFlow analysis and its importance to clinical care and health economics will be discussed.
Christopher K. Zarins, MD, is Emeritus Professor of Surgery at Stanford University and former Chief of Vascular Surgery at the Stanford University Medical Center. He was the longstanding director of cardiovascular biomechanics and cardiovascular tissue engineering research in the Bio-X program. His research interests include hemodynamic factors in atherosclerosis, pathogenesis of aortic aneurysms, carotid plaque localization and complication, anastomotic intimal hyperplasia, vascular biology of artery wall, and computational fluid dynamics as applied to blood flow and vascular disease. Dr Zarins’ scientific research was continuously supported by multiple research grants from the National Institutes of Health, National Science Foundation, American Heart Foundation and others over a 35 year period. He has participated in more than 40 clinical studies, including medical device trials and led the groundbreaking studies on endovascular aortic aneurysm repair. Over the past four decades, he has authored more than 360 articles in peer-reviewed medical journals, as well as six books and more than 130 textbook chapters. He has lectured widely at hundreds of regional, national, and international medical meetings and served as President of the Society for Vascular Surgery, President of the International Society for Endovascular Specialists and Editor in Chief of the Journal of Surgical Research. In 2003, he was awarded the Latvian Republic’s Tris Zvaigznu Ordenis (Three Star Order), Latvia’s highest civilian honor for service to the nation in improving healthcare. In 2010, Dr Zarins retired from the full time Stanford faculty to devote his energies to a company he co-founded, HeartFlow, Inc. This company developed a method for computing patient-specific coronary blood flow using computational fluid dynamics and coronary CT angiography imaging data. This provides a non-invasive measure for assessing the functional significance of coronary artery lesions and helps physicians decide on how best to treat patients with coronary artery disease.
Hosted by Tom Hughes
Tuesday, Nov 15, 2016 from 3:30PM to 5PM
Multilevel Monte Carlo methods
by Mike Giles
Mathematical Institute, University of Oxford, UK
Monte Carlo methods are a standard approach for the estimation of the expected value of functions of random input parameters. However, to achieve improved accuracy often requires more expensive sampling (such as a finer timestep discretisation of a stochastic differential equation) in addition to more samples. Multilevel Monte Carlo methods aim to avoid this by combining simulations with different levels of accuracy. In the best cases, the average cost of each sample is independent of the overall target accuracy, leading to very large computational savings. This talk will introduce the key ideas, and survey the progress in the area.
M.B. Giles. 'Multilevel Monte Carlo methods'. Acta Numerica, 24:259-328, 2015.
Hosted by Thaleia Zariphopoulou
Thursday, Nov 17, 2016 from 3:30PM to 5PM
Power Scaling Highly Coherent Fiber Amplifiers
by Jacob Grosek
AFRL Directed Energy Directorate, Laser Division, Modeling & Simulation Kirtland AFB, NM
The Air Force is currently interested in highly coherent, high-power laser systems amenable for use on airborne platforms. Fiber lasers have emerged as excellent candidates for this task, in part, because multiple fiber amplifiers can be readily beam combined (coherently or spectrally) to further increase the output power of the system. However, for simplicity and for minimal size and weight characteristics, it is still important to maximize the power out of each fiber amplifier. In high-power operation, fiber amplifiers suffer from the onset of optical nonlinearities and deleterious thermal effects. Finding state-of-the-art mitigation techniques that can suppress these pernicious issues is accomplished most cost effectively through high-fidelity computer modeling and simulation. This presentation will explore the physics behind high-power fiber amplifiers, the trade-offs associated with overcoming optical nonlinearities and thermal effects, and some of the current computer modeling efforts at the Air Force Research Laboratory.
Jacob Grosek graduated from the University of Washington (Seattle) in 2013 with a doctorate in Applied Mathematics. Since then he has been working for the
Laser Division of the Air Force Research Laboratory at Kirtland Air Force Base, NM where he builds computer models for high-power fiber laser systems with the intent of overcoming detrimental nonlinear and thermal issues that inhibit further power scaling.
Hosted by Leszek Demkowicz
Tuesday, Apr 11, 2017 from 3:30PM to 5PM
by Ioannis Kevrekidis
Hosted by Greg Rodin