UCLA SIAM Student Chapter Home Events People Links Conferences Activities for 2008-2009 Academic Year Back to main events page. Winter 2009 Monday, March 9th MS 6627, 4-4:50pm Perspectives: Edward Keenan Monday, February 23rd MS 6627, 4-4:50pm Perspectives: Lieven Vandenberghe Thursday, January 29th MS 6620, 4:30-5:30pm Applied Qual Panel Monday, January 12th MS 6627, 4-4:50pm Perspectives: Arthur Szlam Fall 2008 Monday, November 10th MS 6627, 4-4:50pm Perspectives: Adam Oberman - Simon Fraser University Monday, October 20th MS 6627, 4-4:50pm Perspectives: Casey Richardson Thursday, October 16th MS 6943, 5-6pm Grad Experience Panel Monday, October 13th MS 6627, 4-4:50pm Perspectives: Kelly Ward - Disney Feature Animation Perspectives in Mathematics Seminar Series Arthur Szlam, Department of Mathematics, UCLA (W09) Title: A look at the applications of harmonic analysis on graphs to problems in signal processing Abstract: The basic ideas forming the core of harmonic analysis (the relationships between smoothness, scale, and frequency) lift to the setting of weighted graphs. we will explore how this can be used to solve problems in audio and image denoising and machine learning. Adam Oberman, Department of Mathematics, Simon Fraser University (F08) Title: Homogenization of Metric Hamilton-Jacobi Equations Abstract: The objective of this work is the effective numerical solution of front propagation problems in multiscale media. We present a new approach which relates the cell problem for Hamitlon-Jacobi equation, the variational formulation for the Lagrangian, and the variational formulation for the metric. The main advantage of our approach is that we solve just one auxiliary equation to recover the homogenized Hamiltonian $H(p)$. Previous methods require the solution of the cell problem (or a variational problem for each value of $p$. Computational results are presented in the periodic case for the checkerboard pattern, and several other patterns. Exact solutions are recovered numerically. We also present calculations in the random case. This is joint work by Adam Oberman (Simon Fraser), Ryo Takei (UCLA), and Alex Vladimirsky (Cornell) Casey Richardson, Department of Mathematics (F08) Title: Fracture Paths from Front Kinetics: Relaxation and Rate-Independence Abstract: In many engineering models for fracture, crack fronts play a fundamental role: they are the location of both crack growth and the energy dissipation due to growth. However, there has not been a rigorous mathematical definition of crack front, nor rigorous mathematical analysis predicting fracture paths using these fronts as the location of growth and dissipation. I will discuss my work on front based fracture models, which is joint with Chris Larsen (WPI) and Michael Ortiz (Caltech). I will present a natural weak definition of crack front and front speed, and discuss the analysis of models of crack growth in which the energy dissipation is a (non-linear) function of the front speed. Perspectives in Applied Mathematics Series Lieven Vandenberghe, Department of Electrical Engineering, UCLA (W09) Title: Semidefinite programming methods for rank minimization with applications in system theory Abstract: The nuclear norm (sum of singular values) of a matrix is often used in convex heuristics for rank minimization problems in control, system identification, signal processing, and statistics. These heuristics can be seen as generalizations of 1-norm minimization methods for sparse signal reconstruction. In this talk we discuss the implementation of interior-point methods for the solution of linear nuclear norm approximation problems. This problem can be formulated as a semidefinite program that includes large auxiliary matrix variables and is difficult to solve by general-purpose solvers. By exploiting problem structure, we show that the cost per iteration of an interior-point method can be reduced to roughly the cost of solving the approximation problem in Frobenius norm. We will also discuss applications in system identification. Edward Keenan, Department of Linguistics, UCLA (W09) Title: On Logical Types of Quantifiers in Natural Language Abstract: We review results on the logical types of quantifiers (Qs) expressible in English. Qs of type (1,1) include all, some, most as in Most poets daydream. most poets itself is of type (1). Complex (1,1) Qs include all but ten, more than ten, seven out of ten, vague Qs (about a hundred), and non-permutation invariant Qs (John's two, as in John's two children). We find one logical constraint that all such Qs satisfy: Conservativity. This class (Cons) is provably the boolean closure of the generalized universal and generalized existential Qs, themselves isomorphic to type (1) Qs. Cons includes proportionality Qs, generally not first order definable (even over finite models), but which do present novel entailment paradigms, ones that express the action of four operations on Qs (identity, complement, post-complement and dual). We conclude with some type (2) Qs, which express properties of binary relations, as in Different people like different things or John danced with Mary but no one else danced with anyone else. We prove a criterion for determining when type (2) Qs are Fregean reducible to iterated application of type (1) Qs. Different-different and else-else are non-Fregean. Perspectives in Industry Series Kelly Ward, Disney Feature Animation (F08) Title: Hair Simulation at Walt Disney Animation Studios Abstract: Realistic hair modeling is a fundamental part of creating virtual humans in computer graphics; however, realistically representing hair in structure, motion and visual appearance is still an open challenge. In the entertainment industry, such as with feature animation, it is frequently a goal to model a physically impossible hairstyle or motion. In these cases, a high degree of user control is needed to direct the hair in a desired way, which can be a time-consuming and costly endeavor due to the magnitude of the hair volume. In this talk, I will present techniques used for accelerating hair simulation through the use of level-of-detail algorithms as well as discuss the practical day-to-day issues that arise in hair simulation for animated films, specifically addressing hair simulation on Walt Disney Animation Studios' upcoming film "Bolt". Student Seminars Miscellaneous Applied Qual Panel (W09) Come to the graduate lounge to get tips and tricks from graduate students who have experience with the UCLA qualifying exam system. Learn about how much time to give yourself to prepare, what topics to focus on, good reference material, and more. Bring your questions and receieve your answers. Events for Undergraduates Graduate Experience Panel (F08) Panel discussion providing undergraduate students a chance to ask a panel of graduate students questions about their graduate school experience, the application process, funding, exams, and anything else they would like to know. The panel consists of a mix of both pure and applied math graduate students. This is a joint activity with the undergraduate student society. Last updated: