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Computational Mathematics: Accelerating the Discovery of Science. Juan Meza Lawrence Berkeley National Laboratory http://www.nersc.gov/~meza. Outline. Quick tour of computational science problems Computational Science research challenges Thoughts on CSME programs CSME Education issues
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Computational Mathematics: Accelerating the Discovery of Science Juan Meza Lawrence Berkeley National Laboratory http://www.nersc.gov/~meza
Outline • Quick tour of computational science problems • Computational Science research challenges • Thoughts on CSME programs • CSME Education issues • Diversity Issues
First problem I ever worked on at SNL • Solution of a linear system of equations derived from a thermal analysis problem • Everybody “knew” that iterative methods would not work • Size of systems they wanted to study was stressing the memory limits of the computer • Iterative methods in fact turned out to work, but for a very interesting reason I’m not saying I’m especially proud of this achievement, but it should be at least indicative of the need for computational mathematicians
The design of a small-batch fast-ramp LPCVD furnace can be posed as an optimization problem • Temperature uniformity across the wafer stack is critical • Independently controlled heater zones regulate temperature • Wafers are radiatively heated • Design parameters: • Number of heater zones • Size / position of heater zones • Pedestal configuration • Wafer pitch • Insulation thickness • Baseplate cooling Heater zones Silicon wafers (200 mm dia.) Thermocouple Quartz pedestal
Optimized power distribution enhances wafer temperature uniformity Target Temp=1027 C
Computational chemistry is used to design and study new molecules and drugs • Drugs are typically small molecules which bind to and inhibit a target receptor • Pharmaceutical design involves screening thousands of potential drugs • A single new drug may cost over $500 million to develop • The design process is time consuming (typically about 13 years) Docking model for environmental carcinogen bound in Pseudomonas Putida cytochrome P450
Drug design: an optimization problem in computational chemistry • The drug design problem can be formulated as an energy minimization problem • Typically there are thousands of parameters with thousands for constraints • There are many (thousands) of local minimum HIV-1 Protease Complexed with Vertex drug VX-478
Extreme UltraViolet Lithography (EUVL) • Find model parameters, satisfying some bounds, for which the simulation matches the observed temperature profiles • Computing objective function requires running thermal analysis code
Data Fitting Example From EUVL • Objective function consists of computing the max temperature difference over 5 curves • Each simulation requires approximately 7 hours on 1 processor • Uncertainty in both the measurements and the model parameters
Observations • Always worked on a (multidisciplinary) team • Learning each other’s jargon was usually the first and biggest hurdle • Projects averaged 2-3 years • Connections between many of the problems Specifics of a particular discipline are not as important as the general concepts for understanding and communication
Thoughts on CSME programs • Need to teach the importance of working on teams • Rarely have a single PI • We need to recognize team efforts • Need more opportunities for students to solve “real” problems in a research environment • We need opportunities for everybody to learn new fields • Integration between agencies as well as integration across disciplines?
Thoughts on CSME research challenges • Biotechnology • Biophysical simulations • Data management • Stochastic dynamical systems • Nanoscience • Multiple scales (time and length) • Scalable algorithms for molecular systems • Optimization and predictability
Communication, Communication, Communication • “A CSE graduate is trained to communicate with and collaborate with an engineer or physicist and/or a computer scientist or mathematician to solve difficult practical problems.”, SIAM Review, Vol 43, No. 1, pp 163-177. • Most graduates are completely unaware of (unprepared for?) the importance of giving good talks • All graduates need more experience in writing
Diversity in CSME • Practical experiences are the best instruments for attracting and retaining students from underrepresented groups • Students need to see what their impact will be on the society and their community • Universities, labs, and agencies need to establish strong, active, continuous communication with under-represented groups
New algorithms have yielded greater reductions in solution time than hardware improvements Gaussian Elimination/CDC 3600 CDC 6600 1.E+3 CDC 7600 Cray 1 1.E+2 Cray YMP 1.E+1 1.E+0 1 GFlop CPU time (sec.) Sparse GE 1.E-1 Jacobi 1.E-2 Gauss-Seidel 1 Teraflop 1.E-3 SOR 1.E-4 PCG Multigrid Computers 1965 1968 1973 Algorithms 1976 1980 1986 1996