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Articles 3391 - 3420 of 3783

Full-Text Articles in Physical Sciences and Mathematics

Computer Simulation Study Of The Permeability Of Driven Polymers Through Porous Media, Grace M. Foo, Ras B. Pandey Jun 1995

Computer Simulation Study Of The Permeability Of Driven Polymers Through Porous Media, Grace M. Foo, Ras B. Pandey

Faculty Publications

A computer simulation model is used to study the permeability of polymer chains driven by a biased flow field through a porous medium in two dimensions. The chains are modeled by constrained self-avoiding walks, which reptate through the heterogeneous medium with a biased probability imposed by the driven field. A linear response description is used to evaluate an effective permeability. The permeability σ shows an unusual decay behavior on reducing the porosity ps. We find that the permeability decreases on increasing the bias above a characteristic value Bc. This characteristic bias shows a logarithmic decay on …

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On The Equivalence Of Certain Consequences Of The Proper Forcing Axiom, Peter Nyikos, Leszek Piatkiwicz Jun 1995

On The Equivalence Of Certain Consequences Of The Proper Forcing Axiom, Peter Nyikos, Leszek Piatkiwicz

Faculty Publications

No abstract provided.

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Hodographs And Normals Of Rational Curves And Surfaces, Thomas W. Sederberg, Takafumi Saito, Guo-Jin Wang Jun 1995

Hodographs And Normals Of Rational Curves And Surfaces, Thomas W. Sederberg, Takafumi Saito, Guo-Jin Wang

Faculty Publications

Derivatives and normals of rational Bézier curves and surface patches are discussed. A non-uniformly scaled hodograph of a degree m x n tensor-product rational surface, which provides correct derivative direction but not magnitude, can be written as a degree (2m - 2) x 2n or 2m x (2n - 2) vector function in polynomial Bézier form. Likewise, the scaled normal direction is degree (3m - 2) x(3n - 2). Efficient methods are developed for bounding these directions and the derivative magnitude.

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The Effect Of Domain Knowledge On Elementary School Children's Search Behavior On An Information Retrieval System: The Science Library Catalog, Sandra Hirsh May 1995

The Effect Of Domain Knowledge On Elementary School Children's Search Behavior On An Information Retrieval System: The Science Library Catalog, Sandra Hirsh

Faculty Publications

Few information retrieval systems are designed with children’s special needs and capabilities in mind. We need to learn more about children’s information-seeking behavior in order to provide them with information-based tools which support exploratory learning. This dissertation examines children’s search behavior on a hypertext-based automated library catalog designed for elementary school children. The focus of this research is on the effect of domain knowledge on children’s search performance, search behavior, and learning as they look for science books on this system. Reseaxch has shown that level of domain knowledge in~luences the way people search for information. Data was collected through …

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Federal Minimums: Insufficient To Save The Bay, Roy A. Hoagland, Jean G. Watts May 1995

Federal Minimums: Insufficient To Save The Bay, Roy A. Hoagland, Jean G. Watts

Faculty Publications

No abstract provided.

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Accuracy Of Deoxynucleotide Incorporation By Soybean Chloroplast Dna-Polymerases Is Independent Of The Presence Of A 3' To 5' Exonuclease, J. Clinton Bailey Ii, Sabine Heinhorst, Gordon C. Cannon Apr 1995

Accuracy Of Deoxynucleotide Incorporation By Soybean Chloroplast Dna-Polymerases Is Independent Of The Presence Of A 3' To 5' Exonuclease, J. Clinton Bailey Ii, Sabine Heinhorst, Gordon C. Cannon

Faculty Publications

DNA polymerase was purified from soybean (Glycine max) chloroplasts that were actively replicating DNA. The main form (form I) of the enzyme was associated with a low level of 3' to 5' exonuclease activity throughout purification, although the ratio of exonuclease to polymerase activity decreased with each successive purification step. A second form (form II) of DNA polymerase, which elutes from DEAE-cellulose at a higher salt concentration than form I, was devoid of any exonuclease activity. To assess the potential function of the 3' to 5' exonuclease in proofreading, the fidelity of deoxynucleotide incorporation was measured for form I DNA …

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Computer-Simulation Study Of The Permeability Of A Porous Sediment Model, Ras B. Pandey, Jeffrey L. Becklehimer Apr 1995

Computer-Simulation Study Of The Permeability Of A Porous Sediment Model, Ras B. Pandey, Jeffrey L. Becklehimer

Faculty Publications

A computer simulation model is used to study the permeability of fluid flow through porous media generated by the random distribution of the sediments in a two-dimensional lattice. Fluid particles are confined to pore space with the sediments forming the rigid barriers at the pore boundaries. An interaction between the fluid particles and the pore substrate is introduced to incorporate the additional drag in the pore space. The pressure gradient causes a bias to drive the fluid and the Metropolis algorithm is used to hop the fluid particles. The permeability of this system is studied as a function of the …

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A Reverse Isoperimetric Inequality, Stability And Extremal Theorems For Plane-Curves With Bounded Curvature, Ralph Howard, Andrejs Treibergs Apr 1995

A Reverse Isoperimetric Inequality, Stability And Extremal Theorems For Plane-Curves With Bounded Curvature, Ralph Howard, Andrejs Treibergs

Faculty Publications

No abstract provided.

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Are Multifragment Emission Probabilities Reducible To An Elementary Binary Emission Probability, L. G. Moretto, L. Phair, K. Tso, K. Jing, G. J. Wozniak, R. T. Souza, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu Feb 1995

Are Multifragment Emission Probabilities Reducible To An Elementary Binary Emission Probability, L. G. Moretto, L. Phair, K. Tso, K. Jing, G. J. Wozniak, R. T. Souza, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu

Faculty Publications

Experimental intermediate-mass-fragment multiplicity distributions for the EA=80 and 110 MeV Ar36 + Au197reactions are shown to be binomial at all excitation energies. From these distributions, a single binary event probability p can be extracted that has a thermal dependence. Thus, it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with excitation energy implies a contraction of the time scale that is qualitatively consistent with recent fragment-fragment correlation data.

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Multifragment Emission Times In Xe Induced Reactions, A. Moroni, D. R. Bowman, M. Bruno, P. Buttazzo, L. Celano, N. Colonna, M. D'Agostino, J. D. Dinius, A. Ferrero, M. L. Fiandri, K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, Wen-Chien Hsi, M. Huang, I. Iori, M. Lisa, W. G. Lynch, G. V. Margagliotti, P. F. Mastinu, P. M. Milazzo, C. Montoya, Graham F. Peaslee, L. Phair, F. Petruzzelli, R. Rud, R. Scardaoni, C. Schwarz, B. Tsang, G. Vannini, C. Williams Feb 1995

Multifragment Emission Times In Xe Induced Reactions, A. Moroni, D. R. Bowman, M. Bruno, P. Buttazzo, L. Celano, N. Colonna, M. D'Agostino, J. D. Dinius, A. Ferrero, M. L. Fiandri, K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, Wen-Chien Hsi, M. Huang, I. Iori, M. Lisa, W. G. Lynch, G. V. Margagliotti, P. F. Mastinu, P. M. Milazzo, C. Montoya, Graham F. Peaslee, L. Phair, F. Petruzzelli, R. Rud, R. Scardaoni, C. Schwarz, B. Tsang, G. Vannini, C. Williams

Faculty Publications

Multifragment emission is studied in reactions. The emission process for central collisions occurs on a time scale of ≈ 200 fm/c at 30 MeV/n. Intermediate-mass-fragment yields, velocity correlation functions and emission velocities of Z=6 fragments are compared with predictions of statistical decay models.

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Multifragmentation And Flow: Peripheral Vs. Central Collisions, J. Pochodzalla, S. Aiello, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, W. C. Hsi, J. Hubele, G. Imme, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, W. D. Kunze, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, L. G. Moretto, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilive, V. Pappalardo, Graham F. Peaslee, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, W. Seidei, V. Serfling Feb 1995

Multifragmentation And Flow: Peripheral Vs. Central Collisions, J. Pochodzalla, S. Aiello, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, W. C. Hsi, J. Hubele, G. Imme, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, W. D. Kunze, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, L. G. Moretto, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilive, V. Pappalardo, Graham F. Peaslee, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, W. Seidei, V. Serfling

Faculty Publications

Multifragment decays of heavy nuclei have been studied at the ALADIN spectrometer system at beam energies between 100 and 1000 MeV per nucleon. The observed fragment distributions signal a universality of spectator decays at bombarding energies . The role of the radial flow for the fragmentation process is explored by comparing fragment distributions measured for Au+Au collisions at in central collisions and at in more peripheral reactions. At both energies the maximum multiplicity of intermediate mass fragments (IMFs) normalized to the size of the decaying system is about one IMF per 30 nucleons but the element distributions show significant differences. …

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Dynamics Of Order-Parameter-Conserving Ising Models At T > Tc, J.C. Lee Feb 1995

Dynamics Of Order-Parameter-Conserving Ising Models At T > Tc, J.C. Lee

Faculty Publications

http://journals.aps.org/prb/pdf/10.1103/PhysRevB.51.2661

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Phase Coexistence In Multifragmentation?, L. G. Moretto, L. Phair, R. Ghetti, K. Tso, N. Colonna, W. Skulski, G. J. Wozniak, D. R. Bowman, N. Carlin, M. Chartier, C. K. Gelbke, W. G. Gong, W. C. Hsi, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, C. Schwarz, R. T. De Souza, M. B. Tsang, F. Zhu Jan 1995

Phase Coexistence In Multifragmentation?, L. G. Moretto, L. Phair, R. Ghetti, K. Tso, N. Colonna, W. Skulski, G. J. Wozniak, D. R. Bowman, N. Carlin, M. Chartier, C. K. Gelbke, W. G. Gong, W. C. Hsi, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, C. Schwarz, R. T. De Souza, M. B. Tsang, F. Zhu

Faculty Publications

The charge ( Z) distributions from intermediate energy heavy-ion reactions depend upon the multiplicity n of intermediate mass fragments through a factor of the form e−cnZ. Experimentally c starts from zero at low values of the transverse energy Et and reaches a saturation value at high Et. In a liquid-gas phase diagram c=0 for the saturated vapor, while c>0 for the unsaturated vapor. It is suggested that in the c≈0 regime the source evaporates down to a sizable remnant, while for c>0 the source vaporizes completely. Percolation of finite systems and nuclear evaporation portray a behavior similar to …

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Fragment Flow And The Multifragmentation Phase Space, G. J. Kunde, W. C. Hsi, W. D. Kunze, A. Schüttauf, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, J. Hubele, G. Imme, I. Iori, P. Kreutz, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, T. Rubehn, H. Sann, W. Seidei, V. Serfling, L. G. Sobotka, J. Stroth, L. Stuttge, S. Tomasevic Jan 1995

Fragment Flow And The Multifragmentation Phase Space, G. J. Kunde, W. C. Hsi, W. D. Kunze, A. Schüttauf, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, J. Hubele, G. Imme, I. Iori, P. Kreutz, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, T. Rubehn, H. Sann, W. Seidei, V. Serfling, L. G. Sobotka, J. Stroth, L. Stuttge, S. Tomasevic

Faculty Publications

Fragment distributions have been measured for Au + Au collisions at EA=100 and 1000 MeV. A high detection efficiency for fragments was obtained by combining the ALADIN spectrometer and the MSU-Miniball/WU-Miniwall array. At both energies the maximum multiplicity of intermediate mass fragments (IMF) normalized to the size of the decaying system is about one IMF per 30 nucleons but the element distributions show significant differences. Within a coalescence picture the suppression of heavy fragments in central collisions at EA=100 MeV may be related to a reduction of the density in momentum space which is caused by the collective expansion.

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Comment On 'Simulation Of A Two-Dimensional Rayleigh-Bénard System Using The Direct Simulation Monte Carlo Method, Alejandro Garcia, F. Baras, M. Malek Mansour Jan 1995

Comment On 'Simulation Of A Two-Dimensional Rayleigh-Bénard System Using The Direct Simulation Monte Carlo Method, Alejandro Garcia, F. Baras, M. Malek Mansour

Faculty Publications

No abstract provided.

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A Consistent Boltzmann Algorithm, Alejandro Garcia, F. Alexander, B. Alder Jan 1995

A Consistent Boltzmann Algorithm, Alejandro Garcia, F. Alexander, B. Alder

Faculty Publications

The direct simulation Monte Carlo method for the Boltzmann equation is modified by an additional displacement in the advection process and an enhanced collision rate in order to obtain the exact hard sphere equation of state at all densities. This leads to consistent thermodynamic and transport properties in the low density (Boltzmann) regime. At higher densities transport properties are comparable to the predictions of the Enskog model. The algorithm is faster than molecular dynamics at low and moderate densities and readily run on a parallel architecture

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Student Evaluations Of Teaching Effectiveness: The Interpretation Of Observational Data And The Principle Of Faute De Mieux, B. Burt Gerstman Jan 1995

Student Evaluations Of Teaching Effectiveness: The Interpretation Of Observational Data And The Principle Of Faute De Mieux, B. Burt Gerstman

Faculty Publications

Student opinion surveys are important but widely misunderstood tools for evaluating teaching effectiveness. In this brief review, an analogy is drawn between the use and interpretation of observational data for public health and biomedical research and the use of student opinion data in evaluating teach ing effectiveness. Sources of systematic error in the form of selection bias, information bias, and confounding are defined and illustrated. Original data concerning intermittent "quid pro quo" confounding (i.e., the effect of expected grades on student evaluations of teaching) are presented. Finally, the principle of faute de mieux ("lack of anything better") and the interpretation …

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Using Multiple Statistical Prototypes To Classify Continuously Valued Data, Tony R. Martinez, Dan A. Ventura Jan 1995

Using Multiple Statistical Prototypes To Classify Continuously Valued Data, Tony R. Martinez, Dan A. Ventura

Faculty Publications

Multiple Statistical Prototypes (MSP) is a modification of a standard minimum distance classification scheme that generates muItiple prototypes per class using a modified greedy heuristic. Empirical comparison of MSP with other well-known learning algorithms shows MSP to be a robust algorithm that uses a very simple premise to produce good generalization and achieve parsimonious hypothesis representation.

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Waterjet Cutting Of Cross-Linked Glass, Fang Yuan, John A. Johnson, David D. Allred, Robert H. Todd Jan 1995

Waterjet Cutting Of Cross-Linked Glass, Fang Yuan, John A. Johnson, David D. Allred, Robert H. Todd

Faculty Publications

The cutting of cross-linked glasses such as silica and Corning 7059 can be difficult. We conducted an experimental study to determine the feasibility of using a high-speed waterjet to cut thin Corning 7095 glass. Cutting using either pure de-ionized high pressure water at 380 MPa (55 000 psi) or de-ionized water with entrained garnet abrasive was studied. The roughness of the cut surfaces was measured and compared. Photomicrographs were taken of glass examples cut at different traversing rates with pure water and with the abrasive entrained waterjet. Comparative studies of cutting with and without the entrained abrasive material showed that …

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Xenon 147-Nm Resonance Ƒ Value And Trapped Decay Rates, H. M. Anderson, Scott D. Bergeson, D. A. Doughty, J. E. Lawler Jan 1995

Xenon 147-Nm Resonance Ƒ Value And Trapped Decay Rates, H. M. Anderson, Scott D. Bergeson, D. A. Doughty, J. E. Lawler

Faculty Publications

The absorption oscillator strength of the xenon 147-nm resonance transition is measured to be 0.264±0.016. This value is from direct absorption measurements with equivalent widths from ≈ 1 to ≈ 10 cm-1. This ƒ-value measurement is compared to others in the literature and is used in Monte Carlo simulations of trapped decay rates. The simulations include an angle-dependent partial frequency redistribution. The simulation results are compared to trapped decay rates in the literature.

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New Optical Cell Design For Laser Flash Photolysis Studies In Supercritical Fluids, Steven R. Goates, Milton L. Lee, Qin Ji, Edward M. Eyring, Rudi Van Eldik, Kedika Bal Reddy Jan 1995

New Optical Cell Design For Laser Flash Photolysis Studies In Supercritical Fluids, Steven R. Goates, Milton L. Lee, Qin Ji, Edward M. Eyring, Rudi Van Eldik, Kedika Bal Reddy

Faculty Publications

A high-pressure optical cell has been designed that achieves an effective separation between the chemical sample and the pressurizing medium and system. This design limits possible sample contamination and catalytic effects under supercritical fluid sample conditions. Laser flash photolysis experiments were carried out on molybdenum hexacarbonyl dissolved in supercritical CO2. The thermal ring closure reaction of the species Mo(CO)5L, where L is 2,2- bipyridine was found to proceed at rates comparable to those measured previously in liquid benzene or toluene. Much larger activation volumes were found for the reaction in supercritical CO2 than in liquid toluene.

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Slow Motion In One-Dimensional Cahn-Morral Systems, Christopher P. Grant Jan 1995

Slow Motion In One-Dimensional Cahn-Morral Systems, Christopher P. Grant

Faculty Publications

In this paper we study one-dimensional Cahn-Morral systems, which are the multicomponent analogues of the Cahn-Hilliard model for phase separation and coarsening in binary mixtures. In particular, we examine solutions that start with initial data close to the preferred phases except at finitely many transition points where the data has sharp transition layers, and we show that such solutions may evolve exponentially slowly; i.e., if ε is the interaction length then there exists a constant C such that in exp(C/ε) units of time the change in such a solution is o(1). This corresponds to extremely slow coarsening of a multicomponent …

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Collective Expansion In Central Au+Au Collisions, W. C. Hsi, G. J. Kunde, J. Pochodzalla, W. G. Lynch, M. B. Tsang, M. L. Begemann-Blaich, D. R. Bowman, R. J. Charity, F. Cosmo, A. Ferrero, C. K. Gelbke, T. Glasmacher, T. Hofmann, G. Imme, I. Iori, J. Hubele, J. Kempter, P. Kreutz, W. D. Kunze, V. Lindenstruth, M. A. Lisa, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, G. Raciti, F. Rosenberger, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidei, V. Serfling, L. G. Sobotka Dec 1994

Collective Expansion In Central Au+Au Collisions, W. C. Hsi, G. J. Kunde, J. Pochodzalla, W. G. Lynch, M. B. Tsang, M. L. Begemann-Blaich, D. R. Bowman, R. J. Charity, F. Cosmo, A. Ferrero, C. K. Gelbke, T. Glasmacher, T. Hofmann, G. Imme, I. Iori, J. Hubele, J. Kempter, P. Kreutz, W. D. Kunze, V. Lindenstruth, M. A. Lisa, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, G. Raciti, F. Rosenberger, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidei, V. Serfling, L. G. Sobotka

Faculty Publications

Energy spectra for intermediate mass fragments produced in central Au + Au collisions at EA=100 MeV indicate a collective expansion at breakup. For the first time, values for this collective expansion energy per nucleon are extracted independently for each charge. Typically, these values are one-third to one-half of the incident kinetic energy per nucleon in the c.m. system, but they decrease with Zf, suggesting that all fragments do not participate equally in the collective expansion.

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Fragmentation Of Necklike Structures, C. P. Montoya, W. G. Lynch, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, L. Phair, M. B. Tsang, J. B. Webster, C. Williams, N. Colonna, K. Hanold, M. A. Mcmahan, G. J. Wozniak, L. G. Moretto Dec 1994

Fragmentation Of Necklike Structures, C. P. Montoya, W. G. Lynch, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, L. Phair, M. B. Tsang, J. B. Webster, C. Williams, N. Colonna, K. Hanold, M. A. Mcmahan, G. J. Wozniak, L. G. Moretto

Faculty Publications

Intermediate mass fragment (IMF: 3≤Z≤20 emission from necklike structures joining projectilelike and targetlike residues has been observed for peripheral Xe129 + Cunat collisions at EA=50 MeV. These fragments are emitted primarily at velocities between those of the projectilelike and targetlike residues. Relative to the charge distribution of fragments evaporated from projectilelike residues, the distribution for "neck" emission shows an enhanced emission for fragments with 4≤ZIMF≤12. This feature is consistent with expectations for the fragmentation of a noncompact cylindrical configuration.

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Comparison Of Continuous Records Of Near-Bottom Dissolved Oxygen From The Hypoxia Zone Along The Louisiana Coast, Nancy N. Rabalais, William J. Wiseman, R. Eugene Turner Dec 1994

Comparison Of Continuous Records Of Near-Bottom Dissolved Oxygen From The Hypoxia Zone Along The Louisiana Coast, Nancy N. Rabalais, William J. Wiseman, R. Eugene Turner

Faculty Publications

Oxygen depletion is a seasonally dominant feature of the lower water column on the highly-stratified, riverine-influenced continental shelf of Louisiana. The areal extent of hypoxia (bottom waters ≤2 mg l−1 dissolved oxygen) in mid-summer may encompass up to 9,500 km2, from the Mississippi River delta to the upper Texas coast, with the spatial configuration of the zone varying interannually. We placed two continuously recording oxygen meters (Endeco 1184) within 1 m of the seabed in 20-m water depth at two locations 77 km apart where we previously documented midsummer bottom water hypoxia. The oxygen meters recorded considerably different oxygen conditions …

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A Preliminary Mass Balance Model Of Primary Productivity And Dissolved Oxygen In The Mississippi River Plume/Inner Gulf Shelf Region, Victor J. Bierman Jr., Scott C. Hinz, William J. Wiseman Jr., Nancy N. Rabalais, R. Eugene Turner Dec 1994

A Preliminary Mass Balance Model Of Primary Productivity And Dissolved Oxygen In The Mississippi River Plume/Inner Gulf Shelf Region, Victor J. Bierman Jr., Scott C. Hinz, William J. Wiseman Jr., Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

A deterministic, mass balance model for phytoplankton, nutrients, and dissolved oxygen was applied to the Mississippi River Plume/Inner Gulf Shelf (MRP/IGS) region. The model was calibrated to a comprehensive set of field data collected during July 1990 at over 200 sampling stations in the northern Gulf of Mexico. The spatial domain of the model is represented by a three-dimensional, 21-segment water-column .grid extending from the Mississippi River Delta west to the Louisiana-Texas border, and from the shoreline seaward to the 30-60 m bathymetric contours. Diagnostic analyses and numerical experiments were conducted with the calibrated model to better understand the environmental …

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Time Scale For Multifragmentation In Intermediate Energy Heavy-Ion Reactions, D. Fox, R. T. De Souza, T. Glasmacher, L. Phair, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu Nov 1994

Time Scale For Multifragmentation In Intermediate Energy Heavy-Ion Reactions, D. Fox, R. T. De Souza, T. Glasmacher, L. Phair, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu

Faculty Publications

Fragment-fragment correlations are used to probe the spatial-temporal extent of the emitting source in central Ar36+197Au reactions at E/A=35, 50, 80, and 110 MeV. The experimental two particle correlations are compared both with the Koonin-Pratt two-body formalism as well as a three-body Coulomb trajectory calculation. The spatial-temporal extent of the emitting system decreases with increasing incident energy. Within the context of a three-body Coulomb trajectory model the mean fragment emission time rises sharply as a function of the assumed density of the system until ρ/ρ0≊0.3. If one assumes a fixed density, the extracted mean emission time decreases with increasing assumed …

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Semiclassical Quantization Of A Nonintegrable System: Pushing The Fourier Method Into The Chaotic Regime, Karl Sohlberg, Randall B. Shirts Nov 1994

Semiclassical Quantization Of A Nonintegrable System: Pushing The Fourier Method Into The Chaotic Regime, Karl Sohlberg, Randall B. Shirts

Faculty Publications

Semiclassical Einstein–Brillouin–Keller (EBK) quantization of the nonintegrable Hénon–Heiles Hamiltonian succeeds using the Fourier transform method of Martens and Ezra. Two innovations are required for this success: (1) the use of tunneling corrected quantizing actions obtained from an approximate, one-dimensional Hamiltonian and (2) exploitation of intermediate-time approximate quasiperiodicity or "vague tori'' wherein the Fourier transform of chaotic motion over 10–100 vibrational periods allows the determination of frequencies and amplitudes which approximate motion during the time interval. Approximate tori, actions, and EBK energy levels are then straightforward. We use an interpolation method to smooth over small resonance zones that are not expected …

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Driven Front And Interface Of A Fluid-Flow Model In 2+1-Dimensions, Michael J. Leaseburg, Ras B. Pandey Nov 1994

Driven Front And Interface Of A Fluid-Flow Model In 2+1-Dimensions, Michael J. Leaseburg, Ras B. Pandey

Faculty Publications

Computer simulations are performed to study the motion of the front and the growth of the interface width in a model of fluid flow driven by a biased field in 2+1 dimensions. The initial motion of the front is diffusive, which is followed by a nondiffusive power-law behavior in the long-time regime; the power-law exponent is nonuniversal, varying with the strength of the driven field. The growth of the interface width saturates in the asymptotic time regime. The saturated width W scales with both the driven field B as well as the transverse length L of the sample, leading to …

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A Vlsi Implementation Of A Parallel, Self-Organizing Learning Model, Tony R. Martinez, George L. Rudolph, Linton G. Salmon, Matthew G. Stout Oct 1994

A Vlsi Implementation Of A Parallel, Self-Organizing Learning Model, Tony R. Martinez, George L. Rudolph, Linton G. Salmon, Matthew G. Stout

Faculty Publications

This paper presents a VLSI implementation of the Priority Adaptive Self-organizing Concurrent System (PASOCS) learning model that is built using a multi-chip module (MCM) substrate. Many current hardware implementations of neural network learning models are direct implementations of classical neural network structures - a large number of sample computing nodes connected by a dense number of weighted links. PASOCS is one of a class of ASOCS (Adaptive Self-Organizing Concurrent System) connectionist models whose overall goal is the same as classical neural networks models, but whose functional mechanisms differ significantly. This model has potential application in areas such as pattern recognition, …

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