Volume 16 Number 1	Fall 1999

NSF-IGERT Computational Neuroscience First Symposium Supercomputing Institute Research Scholars 1999 Undergraduate Summer Interns Physics of Supersonic Cosmic Flows Flow and Transport in Porous Media Ill-Nitride Semiconductor Devices Structural Studies of Toxins Produced during Staphylococcal Infections Submicron Magnetic Structures Preconditioning Large Sparse Matrix Problems Biomolecular Interactions and Enzymatic Reactions Visitors Research Reports rofessor Hyesung Kang of the Department of Earth Sciences at Pusan National University in Pusan, Korea and Professor Dongsu Ryu of the Astronomy and Space Science Department at Chungnam National University in Daejun, Korea visited Professor Thomas Jones at the Supercomputing Institute. They both worked on Simulations of Particles and Fluids in Astrophysics. This visit was an important step in completing a collaboration that began under NASA support. The researchers have the first stage under test of an innovative Adaptive Mesh Refinement scheme for time dependent simulation of cosmic ray acceleration in shocks. Successful completion of this will open a new frontier in that field. Initial results look excellent. Professor Kang¹s visit helped refine and extend the first version of the code in preparation for the 26th International Cosmic Rays Conference meeting in Salt Lake City. Professor Ryu¹s visit was devoted to refinement of a new collaboration to extend research into cosmological simulations. Professor Ryu has experience in that area, while Professor Jones¹ researchers do not. The group wishes to include for the first time, the physics of high-energy particle acceleration and transport. The importance of these particles is now becoming quite evident. A volume rendering taken from inside a numerical simulation of the expansion of the universe showing the complex web of shock waves that form during gravitational collapse of clusters of galaxies. This section is about one hundred million light years on a side, so an individual galaxy like the Milky Way would be a tiny dot on the same scale. Professor Thomas Jones (left), Professor Dongsu Ryu, Professor Hyesung Kang, and Francesco Miniati (right) pursue their collaboration at the Institute. rofessor Ying Zhang, from the Department of Materials Science at Xiamen University in Fujian, Peoples Republic of China, visited the University of Minnesota to continue ongoing collaborative research with Professor Roger Fosdick of the Aerospace Engineering and Mechanics Department. These researchers have collaborated on problems of stress-induced coexistent phase structures from the point of view of minimization theory. Their work involved both theoretical developments in nonconvex minimization (for nonconvex strain energy functions) and finite element computational schemes. Motivation for this work is based on the idea that the existence and growth of zones of evolving microstructure plays a part not only in the failure of materials, but also in the design of devices and in many emerging applications that depend on sophisticated nonlinear material behavior. Dr. Ying Zhang (left), Professor Roger Fosdick (center), and Darren Mason (right) meet to discuss their work. Concurrently, Professor Fosdick and Professor Darren Mason, from the Department of Materials Science and Mechanics at Michigan State University, began development of a thermodynamical theory related to their earlier work on a long-range nonlocal theory of materials. This work was purely mechanical and included the effect of a local non-convex stored energy function that induced coexistent phase structures and a nonlocal particle-particle interaction energy that provided for a surfacial-like energy contribution between phases. This exhibited definite advantages in modeling material behavior over the earlier well-known gradient theory approach. While the original long range interaction theory was one-dimensional and was restricted to the study of static states, it is currently being generalized to include thermodynamics and apply to three-dimensional continua. They plan to use this generalization to study the time-evolution of phase structures. Professors Fosdick, Mason and Zhang, together, worked to intensify and focus their joint program. Among the many important issues is the most challenging task of developing a highly efficient numerical scheme for nonconvex, spatial dependent energies in order to search for minimal energy states and to characterize the configuration of a body when many interfacial transitions are possible. Professor Zhang began to develop such a scheme during his visit. This is recognized as an important part of the program, because dependable and efficient computational results will motivate a productive direction for our further theoretical developments, the characterization of multiphase static states is not otherwise possible, and we expect that the visualization of developing dynamical structures will shed light on the importance of local vs. global minimizers. r. Muriel Gerbault from the Institute of Geological and Nuclear Science in Lower Hutt, New Zealand visited Supercomputing Institute Fellow Professor David Yuen of the Geology and Geophysics Department at the University of Minnesota. Dr. Gerbault¹s work on finite-element modeling of mountain building processes used abaqus, a package available on the SP system. She worked on the phenomenon of lithospheric buckling within the framework of viscoplastic rheology. She also worked with Professor Yuen¹s undergraduate intern students from both the University of Minnesota Department of Geology and Geophysics program and the Supercomputing Institute program. She helped Liz Starin of the University of Minnesota Department of Geology and Geophysics internship program finish her work on the effects of variable thermal conductivity on the thermal evolution of sedimentary basin. Dr. Gerbault also helped Thomas Wilson, a Supercomputing Institute undergraduate intern, with his work on implementing pV3, the visualization toolkit with Java. Undergraduate intern students Thomas Wilson (left) of the Supercomputing Institute program and Liz Starin of the University of Minnesota Department of Geology and Geophysics program with Professor David Yuen and Dr. Muriel Gerbault (right) from the Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand   HOME | BULLETINS | CONTACT US | PREVIOUS ARTICLE | NEXT ARTICLE | THIS ISSUE

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