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Numerical homogenization on approach for stokesian suspensions.

Description: In this technical report we investigate efficient methods for numerical simulation of active suspensions. The prototypical system is a suspension of swimming bacteria in a Newtonian fluid. Rheological and other macroscopic properties of such suspensions can differ dramatically from the same properties of the suspending fluid alone or of suspensions of similar but inactive particles. Elongated bacteria, such as E. coli or B. subtilis, swim along their principal axis, propelling themselves with the help of flagella, attached at the anterior of the organism and pushing it forward in the manner of a propeller. They interact hydrodynamically with the surrounding fluid and, because of their asymmetrical shape, have the propensity to align with the local flow. This, along with the dipolar nature of bacteria (the two forces a bacterium exerts on a fluid - one due to self-propulsion and the other opposing drag - have equal magnitude and point in opposite directions), causes nearby bacteria to tend to align, resulting in a intermittent local ordering on the mesoscopic scale, which is between the microscopic scale of an individual bacterium and the macroscopic scale of the suspension (e.g., its container). The local ordering is sometimes called a collective mode or collective swimming. Thanks to self-propulsion, collective modes inject momentum into the fluid in a coherent way. This enhances the local strain rate without changing the macroscopic stress applied at the boundary of the container. The macroscopic effective viscosity of the suspension is defined roughly as the ratio of the applied stress to the bulk strain rate. If local alignment and therefore local strain-rate enhancement, are significant, the effective viscosity can be appreciably lower than that of the corresponding passive suspension or even of the surrounding fluid alone. Indeed, a sevenfold decrease in the effective viscosity was observed in experiments with B. subtilis. ...
Date: January 20, 2012
Creator: Haines, B. M.; Berlyand, L. V.; Karpeev, D. A. (Mathematics and Computer Science) & (Department of Mathematics, Pennsylvania State Univ.)
Partner: UNT Libraries Government Documents Department

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[Dr. John Ed Allen]

Description: Photograph of Dr. John Ed Allen, professor of mathematics 1963-2011(?); Chairman of the Department of Mathematics, 1976-1999, and at various times professor, Associate Dean & Director of the Texas Academy of Math and Science 1988-2011(?).
Date: 1976~
Partner: UNT Libraries Special Collections

[President Nolen presents Dr. John Allen with the Honor Professor Award, Honors Day, April 25, 1975]

Description: Photograph of North Texas State University president C.C. Nolen presenting Dr. John Allen of the Department of Mathematics with the Honor Professor Award, April 25, 1975. The presentation was part of the ceremonies of Honors Day, 1975. Both men are seen standing in an interior space.
Date: April 25, 1975
Partner: UNT Libraries Special Collections

Nursery Cultural Practices and Morphological Attributes of Longleaf Pine Bare-Root Stock as Indicators of Early Field Performance

Description: A large study of morphological attributes of longleaf pine nursery stock at the Savannah River site of the various attributes measured, only number of lateral roots and seedling diameters were related to performance. Lateral root pruning in the nursery also improved performance. Both survival and growth during the first two years were strongly correlated with larger stem diameter and larger root system development.
Date: February 1990
Creator: Hatchell, Glyndon E. & Muse, H. David
Partner: UNT Libraries Government Documents Department

Geothermal field's interaction with geophysical fields of another nature

Description: The energy balance of active lithosphere zones is to a large extent determined by nonstationary interaction of mechanical (elastic and hydrodynamic), thermal, electromagnetic, and gravitational geophysical fields. Seismic disturbances of electromagnetic and temperature fields, repeatedly observed before earthquakes are a striking manifestation of this interaction (Sec. 1). Technological processes of exploitation of hydrothermal deposits are determined by the interaction of hydrodynamical and temperature field (Sec. 2). These “fast” interactions (with the characteristic time scale from seconds to years) take place against the background of “slow” thermomechanical interactions (time scale of Myears), the latter determining the formation of regional geothermal fields (Sec. 3).
Date: January 24, 1996
Creator: Novik, Oleg B.; Mikhailovskaya, Irina B.; Repin, Dmitry G. & Yershov, Sergey V.
Partner: UNT Libraries Government Documents Department

Mathematics and string theory

Description: The continuation of the collaboration with Liu and Lian on the calculation of the II A model opened up the possibility to understand calculations for higher genus curves also; many detailed calculations were carried out. They provided evidence that the method is powerful enough to calculate GW invariants in many cases. Local mirror symmetry was worked out with Chiang, Klemm, and Zaslow; it is consistent with physics intuition. Work was carried out to advance the ideas of Stroninger-Yau-Zaslow's geometric version of mirror symmetry in terms of special Lagragian torus fibration. Several papers were written on understanding such duality; it fits well with the predictions, and the ideas are still being studied.
Date: November 25, 2002
Creator: Yau, Shing-Tung
Partner: UNT Libraries Government Documents Department

Hyper-fast interstellar travel via a modification of spacetime geometry

Description: We analyze difficulties with proposals for hyper-fast interstellar travel via modifying the spacetime geometry, using as illustrations the Alcubierre warp drive and the Krasnikov tube. As it is easy to see, no violations of local causality or any other known physical principles are involved as far as motion of spacecrafts is concerned. However, the generation and support of the appropriate spacetime geometry configurations does create problems, the most significant of which are a violation of the weak energy condition, a violation of local causality, and a violation of the global causality protection. The violation of the chronology protection is the most serious of them as it opens a possibility of time travel. We trace the origin of the difficulties to the classical nature of the gravity field. This strongly indicates that hyper-fast interstellar travel should be transferred to the realm of a fully quantized gravitational theory. We outline an approach to further the research in this direction.
Date: August 1, 1997
Creator: Kheyfets, A. & Miller, W.A.
Partner: UNT Libraries Government Documents Department

Phil Wallace and Theoretical Physics at McGill in the 1950's: A Personal Perspective

Description: In 1946 Philip (Phil) Russell Wallace joined the Mathematics Department of McGill University as an Associate Professor of Applied Mathematics, apparently because A. H. S. Gillson, Dean of Arts and Science, wanted theoretical physicists to be in the Mathematics Department. He came with the dream of creating a theoretical physics group at McGill. By the spring of 1949, Phil was authorized to recruit two junior faculty in Mathematics. He hired Theodore (Ted) F. Morris from U. Toronto, who joined in September 1949, and me, who came in January 1950. The group had begun. Phil Wallace was born in Toronto in 1915 and grew up there. He entered the University of Toronto in 1933, earned a B.A. in mathematics in 1937, a M.A. in 1938, and a Ph.D. in applied mathematics in 1940 under Leopold Infeld. His Ph.D. thesis in general relativity was entitled 'On the relativistic equations of motion in electromagnetic theory.' In 1940 World War II had engulfed Europe and was having its effect on Canada, but the US was still at peace. L. J. Synge, Head of the Applied Mathematics Department at Toronto, told Wallace that people such as he would be needed in war work, but things were not ready quite yet. Hold yourself ready. Phil took a two-year position as lecturer in mathematics at the University of Cincinnati (1940-42); in the fall of 1942 he became a lecturer in mathematics at M.I.T. It was from there that he was recruited by Synge to join the war effort from 1943 to 1946 at N.R.C.'s Montreal Laboratory, the genesis of the Canadian Atomic Energy Project. Phil has described those heady wartime years in these pages. Much of the effort of the theoretical physicists was on nuclear reactor theory and the properties of relevant materials, such as graphite, under ...
Date: November 18, 2010
Creator: Jackson, John David
Partner: UNT Libraries Government Documents Department

Final Report for DOE Grant DE-FG02-03ER25579; Development of High-Order Accurate Interface Tracking Algorithms and Improved Constitutive Models for Problems in Continuum Mechanics with Applications to Jetting

Description: Much of the work conducted under the auspices of DE-FG02-03ER25579 was characterized by an exceptionally close collaboration with researchers at the Lawrence Berkeley National Laboratory (LBNL). For example, Andy Nonaka, one of Professor Miller's graduate students in the Department of Applied Science at U. C. Davis (UCD) wrote his PhD thesis in an area of interest to researchers in the Applied Numerical Algorithms Group (ANAG), which is a part of the National Energy Research Supercomputer Center (NERSC) at LBNL. Dr. Nonaka collaborated closely with these researchers and subsequently published the results of this collaboration jointly with them, one article in a peer reviewed journal article and one paper in the proceedings of a conference. Dr. Nonaka is now a research scientist in the Center for Computational Sciences and Engineering (CCSE), which is also part of the National Energy Research Supercomputer Center (NERSC) at LBNL. This collaboration with researchers at LBNL also included having one of Professor Puckett's graduate students in the Graduate Group in Applied Mathematics (GGAM) at UCD, Sarah Williams, spend the summer working with Dr. Ann Almgren, who is a staff scientist in CCSE. As a result of this visit Sarah decided work on a problem suggested by the head of CCSE, Dr. John Bell, for her PhD thesis. Having finished all of the coursework and examinations required for a PhD, Sarah stayed at LBNL to work on her thesis under the guidance of Dr. Bell. Sarah finished her PhD thesis in June of 2007. Writing a PhD thesis while working at one of the University of California (UC) managed DOE laboratories is long established tradition at UC and Professor Puckett has always encouraged his students to consider doing this. Another one of Professor Puckett's graduate students in the GGAM at UCD, Christopher Algieri, was partially supported with ...
Date: October 14, 2012
Creator: Puckett, Elbridge Gerry & Miller, Gregory Hale
Partner: UNT Libraries Government Documents Department

The future of mathematical communication. Final technical report

Description: One of the first fruits of cooperation with LBL was the use of the MBone (Multi-Cast Backbone) to broadcast the Conference on the Future of Mathematical Communication, held at MSRI November 30--December 3, 1994. Late last fall, MSRI brought together more than 150 mathematicians, librarians, software developers, representatives of scholarly societies, and both commercial and not-for-profit publishers to discuss the revolution in scholarly communication brought about by digital technology. The conference was funded by the Department of Energy, the National Science Foundation, and the Paul and Gabriella Rosenbaum Foundation. It focused on the impact of the technological revolution on mathematics, but necessarily included issues of a much wider scope. There were talks on electronic publishing, collaboration across the Internet, economic and intellectual property issues, and various new technologies which promise to carry the revolution forward. There were panel discussions of electronic documents in mathematics, the unique nature of electronic journals, technological tools, and the role of scholarly societies. There were focus groups on Developing Countries, K-12 Education, Libraries, and Te{sub X}. The meeting also embodied the promises of the revolution; it was multicast over the MBone channel of the Internet to hundreds of sites around the world and much information on the conference will be available on their World Wide Web server at the URL http://www.msri.org/fmc. The authors have received many comments about the meeting indicating that it has had a profound impact on how the community thinks about how scientists can communicate and make their work public.
Date: December 31, 1994
Creator: Christy, J.
Partner: UNT Libraries Government Documents Department

[Memorandum from Jean Schaake, July 17, 1987]

Description: Memorandum from Jean Schaake to Alan Moore, John Ed Allen, Gerry O'Donovan, Rogers Redding, Walter Sandefur, Bob Stevens, Le Theriot, Blake Dehart, and Ron Arrington, advising them to leave September 15, 1987 open on their calendars, as they are expecting a visit from Julian C. Stanley.
Date: July 17, 1987
Creator: Schaake, Jean
Partner: Texas Academy of Mathematics and Science

Workshop on Women of Applied Mathematics: Research and Leadership

Description: We held a two and a half day workshop on Women of Applied Mathematics: Research and Leadership at the University of Maryland in College Park, Maryland, October 8--10, 2003. The workshop provided a technical and professional forum for eleven senior women and twenty-four early-career women in applied mathematics. Each participant committed to an outreach activity and publication of a report on the workshop's web site. The final session of the workshop produced recommendations for future action.
Date: September 28, 2004
Creator: O'Leary, Dianne P. & Kolda, Tamara G.
Partner: UNT Libraries Government Documents Department

[Memorandum from Tom Preston, May 4, 1987]

Description: Letter from Tom Preston to John Ed Allen, Frank Kemerer, Gerry O'Donovan, Rogers Redding, Walter Sandefur, Bob Stevens, Le Theriot, and Jean Schaake, on May 4, 1987, asking them to serve on a committee for implementing the curriculum of the Texas Academy of Math and Science.
Date: May 4, 1987
Creator: Preston, Tom
Partner: Texas Academy of Mathematics and Science

[Memorandum from Tom Preston, May 4, 1987]

Description: Memorandum from Tom Preston to John Ed Allen, Frank Kemerer, Gerry O'Donovan, Rogers Redding, Walter Sandefur, Bob Stevens, Le Theriot, and Jean Schaake, on May 4, 1987, asking that they serve on a curriculum committee to implement the Texas Academy of Mathematics and Science.
Date: May 4, 1987
Creator: Preston, Tom
Partner: Texas Academy of Mathematics and Science

The workshop on iterative methods for large scale nonlinear problems

Description: The aim of the workshop was to bring together researchers working on large scale applications with numerical specialists of various kinds. Applications that were addressed included reactive flows (combustion and other chemically reacting flows, tokamak modeling), porous media flows, cardiac modeling, chemical vapor deposition, image restoration, macromolecular modeling, and population dynamics. Numerical areas included Newton iterative (truncated Newton) methods, Krylov subspace methods, domain decomposition and other preconditioning methods, large scale optimization and optimal control, and parallel implementations and software. This report offers a brief summary of workshop activities and information about the participants. Interested readers are encouraged to look into an online proceedings available at http://www.usi.utah.edu/logan.proceedings. In this, the material offered here is augmented with hypertext abstracts that include links to locations such as speakers` home pages, PostScript copies of talks and papers, cross-references to related talks, and other information about topics addresses at the workshop.
Date: December 1, 1995
Creator: Walker, H.F. & Pernice, M.
Partner: UNT Libraries Government Documents Department

Least-cost groundwater remediation design using uncertain hydrogeological information. 1998 annual progress report

Description: 'The objective of the project is to formulate, test, and evaluate a new approach to the least-cost design of groundwater contamination containment and decontamination systems. The proposed methodology employs robust optimization, the outer-approximation method of non-linear programming, and groundwater flow and transport modeling to find the most cost-effective pump-and-treat design possible given the physical parameters describing the groundwater reservoir are known with uncertainty. The result is a methodology that will provide the least-cost groundwater remediation design possible given a specified set of design objectives and physical and sociological constraints. As of the end of the first year of this 3-year project the author has developed and tested the concept of robust optimization within the framework of least-cost groundwater-contamination-containment design. The outer-approximation method has been employed in this context for the relatively simple linear-constraint case associated with the containment problem. In an effort to enhance the efficiency and applicability of this methodology, a new strategy for selecting the various realizations arising out of the Monte-Carlo underpinnings of the robust-optimization technique has been developed and tested. Based upon observations arising out of this work a yet more promising approach has been discovered. The theoretical foundation for this most recent approach has been, and continues to be, the primary focus of the research.'
Date: June 1, 1998
Creator: Pinder, G.F.
Partner: UNT Libraries Government Documents Department

Final Report: Towards Optimal Petascale Simulations (TOPS), ER25785

Description: Multiscale, multirate scientific and engineering applications in the SciDAC portfolio possess resolution requirements that are practically inexhaustible and demand execution on the highest-capability computers available, which will soon reach the petascale. While the variety of applications is enormous, their needs for mathematical software infrastructure are surprisingly coincident; moreover the chief bottleneck is often the solver. At their current scalability limits, many applications spend a vast majority of their operations in solvers, due to solver algorithmic complexity that is superlinear in the problem size, whereas other phases scale linearly. Furthermore, the solver may be the phase of the simulation with the poorest parallel scalability, due to intrinsic global dependencies. This project brings together the providers of some of the world’s most widely distributed, freely available, scalable solver software and focuses them on relieving this bottleneck for many specific applications within SciDAC, which are representative of many others outside. Solver software directly supported under TOPS includes: hypre, PETSc, SUNDIALS, SuperLU, TAO, and Trilinos. Transparent access is also provided to other solver software through the TOPS interface. The primary goals of TOPS are the development, testing, and dissemination of solver software, especially for systems governed by PDEs. Upon discretization, these systems possess mathematical structure that must be exploited for optimal scalability; therefore, application-targeted algorithmic research is included. TOPS software development includes attention to high performance as well as interoperability among the solver components. Support for integration of TOPS solvers into SciDAC applications is also directly supported by this proposal. The role of the UCSD PI in this overall CET, is one of direct interaction between the TOPS software partners and various DOE applications scientists – specifically toward magnetohydrodynamics (MHD) simulations with the Center for Extended Magnetohydrodynamic Modeling (CEMM) SciDAC and Applied Partial Differential Equations Center (APDEC) SciDAC, and toward core-collapse supernova simulations with ...
Date: April 15, 2011
Creator: Reynolds, Daniel R.
Partner: UNT Libraries Government Documents Department