Brown University -
Joint Materials/Solid Mechanics Seminar Series
Department of Theoretical and Applied Mechanics, Cornell University | |
Abstract: The stress required to separate an interface (adhesive strength) between soft solids appears to be much lower than that calculated using van der Waals theory. In this talk, I first review van der Waals theory for non-polar solids. I will then explore the hypothesis that the adhesive strength is limited in value by thermal fluctuations. Using a simple model of an interface, where the molecules bridging the two surfaces are represented by linear entropic springs, we use classical statistical mechanics to evaluate the adhesive strength and effective work of adhesion. For stiff materials, adhesive strength is found to be equal to the intrinsic strength. For soft materials, adhesive strength is significantly reduced and is on the order of elastic modulus. The effective work of adhesion agrees with the intrinsic work of adhesion for stiff solids and decays very slowly with increasing compliance.
Special Scientific Computing Seminar
Department of Mathematics and Institute for Computational Engineering and Sciences The University of Texas at Austin Austin, TX | |
PLEASE NOTE CHANGE IN DAY AND TIME FOR THIS SEMIANR ONLY |
Abstract: We study long time dynamics to solutions of initial value problems to rather general Boltzmann kinetic models may describe qualitatively different processes in applications, but have many features in common. In particular we focus in the existence, uniqueness and asymptotics to dynamical scaling (self-similar) solutions and connections to stable laws for non-Gaussian states.
In adition we present a deterministic spectral solver for the non-linear Boltzmann Transport Equation (energy conservative and non-conservative) for rather general collision kernels. The computation of the non-linear Boltzmann Collision integral and the lack of appropriate conservation properties due to spectral methods has been remedied by framing the conservation properties in the form of a constrained minimization problem which is solved easily using a Lagrange multiplier method. We benchmark our code with several examples of models for Maxwell type of interactions, (elastic or inelastic) for which explicit solution formulas are known. The numerical moments are compared with exact moments formulas and the numerical non-equilibrium probability distributions functions are compared to the general asymptotic results. The numerical method also produces accurate results in the case of inelastic hard-sphere interactions.
Brown University --
Center for Statistical Sciences
2007 Lectureship Series
Department of Mathematics and Statistics, Smith College | |
(Refreshments beginning at 3:15 p.m.) |
Abstract: Missing data are a recurring problem that can cause bias or lead to inefficient analyses. The development of statistical methods to address missingness has been actively pursued in recent years, including imputation, likelihood and weighting approaches. Each approach is considerably more complicated when there are many patterns of missing values and both categorical and continuous random variables are involved. Implementations of routines to incorporate observations with incomplete variables in regression models are now widely available. We review these methods in the context of a motivating example from a large health services research dataset. While there are still limitations to the current implementations, and additional efforts are required of the analyst, it is feasible to incorporate partially observed values, and these methods should be more widely utilized in practice.
Sponsored by: The Charles K. Colver Lectureship and Publication Fund
Center for Fluid Mechanics
And
The Fluids, Thermal and Chemical Processes Group
Of
The Division of Engineering
Seminar Series
HHR-Hydroscience and Engineering The University of Iowa Iowa City, IA | |
Abstract: SBD for ship hydrodynamics merges traditional fields of resistance and propulsion, seakeeping, and maneuvering, which with inclusion of environmental effects will revolutionize the design process and offers possibility for innovative out-of-the box concepts for future ships to meet the challenges of the 21st century. Development of SBD involves a new paradigm for hydrodynamics research in which CFD, EFD, and UA investigations are conducted simultaneously for benchmark geometries and conditions using an integrated approach along with optimization methods, all of which serve as an internal engine guaranteeing simulation fidelity. IIHR research in major components of SBD for ship hydrodynamics is described through an overview of the status of their application to traditional fields and future directions.
Brown University,
Center for Computational Molecular Biology
Abstract: I will outline two convergent lines of research in our lab: one a general computational-experimental strategy for identifying epigenetic alterations in upstream regions which can serve as markers for incipient neoplastic lesions; the other the development and application of supervised and unsupervised approaches to identifying the targets of transcriptional regulators. Results for Wilms" tumor and clear cell renal carcinoma will be briefly discussed.
Brown University -
Transatlantic Seminar
Brown University
Graduate School Dissertation Defense Information
Scientific Computing Seminar
Division of Computer and Information Sciences, Rutgers The State University of New Jersey, Piscataway, NJ | |
Abstract: Recent advances in deformable models have lead to new classes of methods that borrow the best features form level sets as well as traditional parametric deformable models. In this talk I will first present a new class of such models termed Metamorphs whose formulation integrates shape, intensity and texture by borrowing ideas from level sets and traditional parametric deformable models. Further extensions to these models include the inclusion of shape and texture priors, as well as parameterless formulations. These new models can be used in medical segmentation and registration where organ boundaries are fuzzy and with no assumptions on the noise distribution. In the second part of the talk we will present a new Eulerian method for handling dynamics of liquids and their surface textures. Our approach is based on a new method for interface advection that we term the Marker Level Set (MLS). The MLS method uses surface markers and a level set for tracking the surface of the liquid, yielding more efficient and accurate results than popular methods like the Particle Level Set method (PLS). Another novelty is that the surface markers allow the MLS to handle surface texture advection as well, a very rare capability in the realm of Eulerian simulation of liquids. We present several simulations of the dynamical evolution of liquids and their texture maps.
Biographical Sketch: Dr. Dimitris Metaxas is a Distinguished Professor in the Division of Computer and Information Sciences and Professor in the Department of Biomedical Engineering at Rutgers University. He is directing the Center for Computational Biomedicine, Imaging and Modeling (CBIM). Dr. Metaxas has been conducting research towards the development of formal methods upon which both computer vision, computer graphics and medical imaging can advance synergistically. His focus is on the development of novel deformable models and algorithms for segmentation, registration, tracking, recognition and simulation in the above areas. Dr. Metaxas has published over 230 research articles in these areas and has graduated 21 PhD students. His research on the modeling of the heart and on fluid modeling has received several best papers awards. He is a recipient of an ONR YIP and is a Fellow of the American Institute of Medical and Biological Engineers. He is also the program chair of ICCV 2007 and SCA 2007 and the general chair of MICCAI 2008.
Mini-conference on Stochastic Analysis
Stochastic Analysis
Michigan State University | |
Break (11:00 - 11:20 am) |
Abstract: See Special Mini-Program Announcement
Stochastic Analysis
LUNCH 12:10 - 2:00 pm |
Abstract: An overview of known results concerning estimating the linear and nonlinear functionals of the density for i.i.d. observations and for functionals of the signal observed in the White Gaussian Noise (WGN) with small intensity will be presented. Then similar problems will be considered for the Poisson observation process. Asymptotically efficient estimates of once Frechet differentiable functionals will be intoduced.
Stochastic Analysis
University of Minnesota | |
Abstract: While teaching an undergraduate course in probability I asked myself if I could explain without using heavy machinery why and how the Gaussian distribution appears. It turns out that such explanation can be given and even turned into a few theorems about some fine estimates. The only knowledge needed is Chebyshev's inequality and Taylor's formula for log x.
<--- 2007 Index