LANS Informal Seminar
"SASSy : Student Argonne Summer Symposium"
DATE: July 22, 2009
TIME: 14:00:00 - 16:45:00 Description:
SPEAKER: MCS Summer Students
LOCATION: Building 221 Conference Room A216, Argonne National Laboratory
Title: Terascale Analysis of Variable Interactions in MODIS
The temporal and spatial dynamics of climatic variables are highly dependent on each other, and it is important to be able to identify multivariate interactions when assessing problems such as drought and fire damage. As climatic datasets grow beyond the terascale, previous serial methods for performing these types of analyses are infeasible to application scientists. To enhance scientific discovery at this magnitude, we developed a parallel framework that closely integrates parallel I/O techniques with an intuitive interface for issuing Boolean range queries on scientific data. Our techniques allowed us to visualize various interactions between two variables in over a terabyte of satellite data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) project. We applied our methods on the entire dataset with scalability up to 16,000 cores and end-to-end execution times consistently around one minute.
Title: Automatic differentiation of the nuclear reactor simulation code MATWS
A tangent linear model is built for the FORTRAN 77 nuclear reactor simulation code MATWS using the automatic differentiation tool ADIFOR. The sensitivities of a few variables of interest are computed, and then validated against finite differences. The resulting derivative information will be used for uncertainty quantification and sensitivity analysis. We also describe the a priori code modifications required by ADIFOR, and the post-processing of the differentiated code.
Luis de la Torre
Title: Carbon Emissions Trading with a Computable General Equilibrium Model
Emissions trading markets seek to reduce pollution levels by setting a cap on total emissions and allowing producers to trade pollution permits. The American Clean Energy and Security Act, passed in the House on June 26, 2009, proposes emissions trading markets for greenhouse gases including carbon dioxide. We use a complementarity problem to model a multi-factor, multi-region economy in which a foreign producer has market power to affect prices, in order to compare policy alternatives between carbon emissions trading markets and production and use taxes. We also discuss a safety valve system, a combination of tax and emissions trading in which emissions permit prices are bounded.
Title: Algorithm for the estimation of Computational Noise
Estimating the computational noise present in the evaluation of a function f could play an important role in the development of convergence criteria for optimization algorithms. There are different reasons for the presence of noise in the evaluation of a function, for example the use of iterative methods in the computation, or single precision operations. In this presentation we will describe an algorithm for estimating stochastic computational noise. Based on our tests, this algorithm can determine the noise level of a nonlinear function with fewer than 10 evaluations (independent of the dimension), with more evaluations providing more precise estimates.
Title: Optimizing Public Health Emergency Logistics with Dynamic Programming
In the event of a public health emergency like pandemic flu or a large-scale bioterrorist attack, it is important that vaccines, antibiotics, or other medical countermeasures be distributed quickly to minimize mortality and morbidity. Federal, state, and local authorities plan to work together to rapidly distribute the necessary supplies from stockpiles to the affected population. We use a stochastic dynamic programming model of the state and local level supply chain to determine an optimal strategy for allocating limited staff, resources, and medical supplies. We also present an approximate algorithm for solving the dynamic program with realistically large data sets.
Title: A Non-monotone Filter Method for Nonlinear Optimization
We propose a non-monotone filter sequential quadratical programming (SQP) algorithm in which the l and g-filters are introduced. The g-filter being a traditional monotone filter guarantees the global convergence. The l-filter is a non-monotone filter that allows more flexibility for accepting a trial point. Under standard conditions,we prove the super-linear local convergence without second order correction (SOC) steps.
Title: FEM automation of Oldroyd-B ﬂuids
Over the past several years the FEniCS projects have developed many advances in the automation of ﬁnite element codes. These techniques allow the researcher to study numerous models and numerical discretizations quite rapidly. With this technology, we study the numerous viscoelastic models and discretizations presented by Baaijens. This allows us to systematically address many stability questions with quick comparisons between numerous test problems. We present both the abstractions for the FEM automation as well as the comparisons for the different Oldroyd-B type models.
Krystal Richards and Seneca Gibson
Title: Experiences On Empirical Performance Tuning of Scientific Applications - S3D and MADNESS
Empirical performance tuning has been emerging as a popular and attractive means of dealing with very complex computer architectures and application programs. Two important scientific application packages, S3D (numerical simulations of turbulent combustion) and MADNESS (simulation framework for solving quantum chemical problems) are installed and tested on target platform (AMD Quad-Core Phenom) for empirical performance tuning. Tasks involving preparation, processing, and methods will be discussed. Some experimental results in profiling, identifying kernels, and tuning the codes will be presented.
TIME: 14:00:00 - 16:45:00
Please send questions or suggestions to Debojyoti Ghosh: ghosh at mcs dot anl dot gov.