Computational Scientist
Computational Earth Sciences Group
Computer Science and Mathematics Division
Oak Ridge National Laboratory
I am currently a computational scientist in the Computational Earth Sciences Group of the Computer Science and Mathematics Division at Oak Ridge National Laboratory. I came to ORNL in 2004 after completing my Ph.D. in computer science (with a specialization in computational science) under the direction of Andreas Stathopoulos at the College of William and Mary in beautiful Williamsburg, Virginia. My graduate studies were supported by a Department of Energy Computational Science Graduate Fellowship administered by the fine folks at Krell Institute, and for this I shall be forever grateful. I was fortunate enough to complete my fellowship practicum at Los Alamos National Laboratory under the masterful tutelage of Peter Lichtner of the Hydrology, Geochemistry and Geology group. Prior to my graduate studies, I studied geology and physics (in addition to Volunteers Football, of course) in the hospitable environs of the University of Tennessee, Knoxville, as a Chancellor's Scholar.
My broad interest is in developing and applying numerical methods and software to enable the solution of very computationally challenging problems that arise in the natural sciences. My specific interests as a computer scientist arise from this broad interest and mostly fall into two categories. The first is numerical methods and software for the solution of partial differential equations, and particularly in iterative methods for solving the sparse algebraic systems that arise from their discretization. The second is parallel implementation issues and the interplay between numerical algorithms and computer architecture. Algorithms designed with one kind of architecture in mind may perform very poorly on another. For instance, codes that are very efficient on superscalar processors might perform extremely poorly on vector processor machines. My interest is in developing scalable, parallel numerical applications that not only possess good numerical properties, but are also tailored to effectively utilize their target resources.
Forrest M. Hoffman, William W. Hargrove, Richard T. Mills, Salil Mahajan, David J. Erickson, and Robert J. Oglesby, 2008. "Multivariate Spatio-Temporal Clustering (MSTC) as a Data Mining Tool for Environmental Applications." Proceedings of the iEMSs Fourth Biennial Meeting: International Congress on Environmental Modelling and Software (iEMSs 2008), ISBN 978-84-7653-074-0, International Environmental Modelling and Software Society, Barcelona, Catalonia, Spain, July 2008.
D. J. Erickson III, R. T. Mills, J. Gregg, T. J. Blasing, F. M. Hoffman, R. J. Andres, M. Devries, Z. Zhu, S. R. Kawa, 2008. "An estimate of monthly global emissions of anthropogenic CO2: Impact on the seasonal cycle of atmospheric CO2". Journal of Geophysical Research - Biogeosciences, v. 113, G01023. DOI 10.1029/2007JG000435.
S. R. Alam, R. F. Barrett, M. R. Fahey, J. A. Kuehn, O. E. B. Messer, R. T. Mills, P. C. Roth, J. S. Vetter, P. H. Worley, 2008. "An evaluation of the Oak Ridge National Laboratory Cray XT3". International Journal of High Performance Computing Applications, February 2008, v. 22, no. 1, pp. 52-80.
R. T. Mills, C. Lu, P. C. Lichtner, and G. E. Hammond, 2007. "Simulating subsurface flow and transport on ultrascale computers using PFLOTRAN". Journal of Physics: Conference Series, v. 78 (Proceedings of SciDAC 2007). DOI 10.1088/1742-6596/78/1/012051. Invited paper.
R. T. Mills, C. Yue, A. Stathopoulos, and D. S. Nikolopoulos, 2007. "Runtime and programming support for memory adaptation in scientific applications via local disk and remote memory". Journal of Grid Computing, v. 5, no. 2, pp. 213-234. DOI 10.1007/s10723-007-9075-7.
P. K. V. V. Nukala, S. Simunovic, and R. T. Mills, 2006. "Statistical physics of fracture: scientific discovery through high-performance computing". Journal of Physics: Conference Series, v. 46, pp. 278-291 (Proceedings of SciDAC 2006). DOI 10.1088/1742-6596/46/1/039. Invited paper.
C. Yue, R. T. Mills, A. Stathopoulos, and D. S. Nikolopoulos, 2006. "Runtime support for memory adaptation in scientific workloads via local disk and remote memory". Proceedings of the 15th IEEE International Symposium on High Performance Distributed Computing. Paris, France, June 2006. Finalist for best paper award.
E. F. D'Azevedo, M. R. Fahey, and R. T. Mills, 2005. "Vectorized sparse matrix multiply for compressed row storage format". Lecture Notes in Computer Science, 3514:99-106, 2005.
R. T. Mills, A. Stathopoulos, and D. S. Nikolopoulos, 2004. "Adapting to memory pressure from within scientific applications on multiprogrammed clusters of workstations". Proceedings of the 18th IEEE International Parallel and Distributed Processing Symposium (IPDPS 2004).
J. R. McCombs, R. T. Mills, and A. Stathopoulos, 2003. "Dynamic load balancing of an iterative eigensolver on networks of heterogeneous clusters". Proceedings of the 17th International Parallel and Distributed Processing Symposium (IPDPS 2003).
H. H. Mills and R. T. Mills, 2001. "Evolution of undercut slopes on abandoned incised meanders in the Eastern Highland Rim of Tennessee, USA". Geomorphology 38, 317-336. DOI 10.1016/S0169-555X(00)00104-5.
R. T. Mills, A. Stathopoulos and E. Smirni, 2001. "Algorithmic modifications to the Jacobi-Davidson parallel eigensolver to dynamically balance external CPU and memory load". Proceedings of the International Conference on Supercomputing (ICS 2001), Sorrento, Italy, June 18-22, (2001), 454--463.
S. D. Ahern, S. R. Alam, M. R. Fahey, R. J. Hartman-Baker, R. F. Barrett, R. A. Kendall, D. B. Kothe, O. E. B. Messer, R. T. Mills, R. Sankaran, A. N. Tharrington, J. B. White III. "Scientific Application Requirements for Leadership Computing at the Exascale". Proceedings of the 2008 Cray User Group Meeting, May 5-8, 2008, Helsinki, Finland. Also available as ORNL/TM-2007/238.
S. R. Alam, R. F. Barrett, M. R. Fahey, O. E. B. Messer, R. T. Mills, P. C. Roth, J. S. Vetter, and P. H. Worley, 2006. "Evaluation of the Cray XT3 at ORNL: a status report". Proceedings of the Cray User Group 2006 Technical Meeting, Lugano, Switzerland, May 8-11, 2006.
S. Akella, M. C. Smith, R. T. Mills, S. R. Alam, R. F. Barrett, and J. S. Vetter, 2005. "Sparse matrix-vector multiplication kernel on a reconfigurable computer". Refereed extended abstract in The 9th Annual Workshop on High Performance Embedded Computing (HPEC), MIT Lincoln Laboratory, Boston, Massachusetts, September 20-22, 2005.
R. T. Mills, E. F. D'Azevedo, and M. R. Fahey, 2005. "Progress towards optimizing the PETSc numerical toolkit on the Cray X1". Proceedings of the Cray User Group 2005 Technical Meeting, Albuquerque, NM, May 16-19, 2005. (Presentation slides also available.)
R. T. Mills, 2004. "Dynamic adaptation to CPU and memory load in scientific applications". Ph.D. dissertation, Department of Computer Science, College of William and Mary, Williamsburg, VA.
P. C. Lichtner, G. E. Hammond, C. Lu, R. T. Mills, J. D. Moulton, B. Philip, B. F. Smith, A. J. Valocchi, S. Yabusaki, 2008. "Towards petascale computing in geosciences: Application to the Hanford 300 Area". SciDAC 2008, Seattle, WA, July 13-17.
P. C. Lichtner, C. Lu, G. E. Hammond, B. Philip, J. D. Moulton, R. T. Mills, B. F. Smith, A. J. Valocchi, K. Nakshatrala, S. Yabusaki, 2008. "The Next-Generation Massively Parallel Reactive Flow and Transport Code PFLOTRAN: Application to CO2 Storage in Saline Aquifers". Joint BES-BER-ASCR-FE Research Symposium on Basic Research Relevant to CO2 Sequestration, Gaithersburg, MD, March 2008.
F. M. Hoffman, S. Mahajan, W. W. Hargrove, R. T. Mills, and A. Del Genio, 2008. "A cluster analysis approach to comparing atmospheric radiation measurement (ARM) data with global climate model (GCM) results". 18th Atmospheric Radiation Measurement (ARM) Science Team Meeting, Norfolk, VA, March 2008. Winner of People's Choice award for best poster.
F. M. Hoffman, W. W. Hargrove, R. T. Mills, A. D. Del Genio, J. V. Pittman, 2007. "From measurements to models: cross-comparison of measured and simulated behavioral states of the atmosphere". 17th Atmospheric Radiation Measurement (ARM) Science Team Meeting, Monterey, CA, March 2007.
P. C. Lichtner, C. Lu, B. Philip, J. D. Moulton, G. E. Hammond, S. Yabusaki, R. T. Mills, B. F. Smith, A. J. Valocchi, 2007. "Modeling multiscale-multiphase-multicomponent subsurface reactive flows using advanced computing". DOE SciDAC-2 Organization Workshop, Atlanta, GA, February 5-6, 2007.
C. Lu, P. C. Lichtner, I. N. Tsimpanogiannis, and R. T. Mills, 2005. "Parametric study of CO2 sequestration in geologic media using the massively parallel computer code PFLOTRAN". AGU Fall Meeting, San Francisco, CA, 2005.
R. T. Mills, P. C. Lichtner, and C. Lu, 2005. "PFLOTRAN: A massively parallel simulator for groundwater flow and transport". SC|05 (SuperComputing 2005), Seattle, WA, 2005.
R. T. Mills, 2006. "An introduction to the Cray X1E". 2006 National Center for Computational Sciences Users Meeting, February 14, 2006.
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