Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Faculty Publications

Discipline
Institution
Keyword
Publication Year
File Type

Articles 7861 - 7890 of 9001

Full-Text Articles in Entire DC Network

Comparison Of Tovs-Derived Land Surface Variables With Ground Observations, Venkataraman Lakshmi, Joel Susskind Jan 2000

Comparison Of Tovs-Derived Land Surface Variables With Ground Observations, Venkataraman Lakshmi, Joel Susskind

Faculty Publications

The Tiros Operational Vertical Sounder (TOVS) Pathfinder Path A retrieved surface skin temperature, surface air temperatures, and surface specific humidity are compared with data obtained from three large-scale field campaigns: the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE), the Hydrologic Atmospheric Pilot Experiment (HAPEX) in the Sahel, and the Boreal Ecosystem-Atmosphere Study (BOREAS). The long-term estimates of surface skin temperatures, surface air temperatures, and surface vapor pressure were unbiased, and the standard deviations of the errors were about 4°C, 3.5°C, and 3.5 mbar, respectively. The monthly mean variables obtained from the TOVS data at four times …

Go to article

Measurement Of Inclusive Prompt Photon Photoproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti Jan 2000

Measurement Of Inclusive Prompt Photon Photoproduction At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

© 2000 Published by Elsevier Science B.V. All rights reserved. First inclusive measurements of isolated prompt photons in photoproduction at the HERA ep collider have been made with the ZEUS detector, using an integrated luminosity of 38.4 pb-1. Cross sections are given as a function of the pseudorapidity and the transverse energy (ηγ, Eγ . of the photon, for E>5 GeV in the γ p centre-of-mass energy range T T 134-285 GeV. Comparisons are made with predictions from Monte Carlo models having leading-logarithm parton showers, and with next-To-leading-order QCD calculations, using currently available parameterisations of the photon structure. For …

Go to article

W Production And The Search For Events With An Isolated High-Energy Lepton And Missing Transverse Momentum At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti Jan 2000

W Production And The Search For Events With An Isolated High-Energy Lepton And Missing Transverse Momentum At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

© 2000 Published by Elsevier Science B.V. All rights reserved. A search for the leptonic decays of W bosons produced in the reaction e+ p → e+ W± X at a centre-of-mass energy of 300GeV has been performed with the ZEUS detector at HERA using an integrated luminosity of 47.7 pb-1. Three events consistent with W → eν decay are found, giving a cross section estimate of 0.9+10-07±0.2 pb, in good agreement with the Standard Model prediction. The corresponding 95% C.L. upper limit on the cross section is 3.3 pb. A search for the decay W → μν has a …

Go to article

The Use Of Aerial Photography For Development Of Fuel Loading Prediction Models Within Three Cover Types In The Jemez And Sangre De Cristo Mountains Of New Mexico, Kelly Scott, Brian P. Oswald, Kenneth W. Farrish, Daniel Unger Jan 2000

The Use Of Aerial Photography For Development Of Fuel Loading Prediction Models Within Three Cover Types In The Jemez And Sangre De Cristo Mountains Of New Mexico, Kelly Scott, Brian P. Oswald, Kenneth W. Farrish, Daniel Unger

Faculty Publications

Fuel load prediction equations that make use of aerial photographs were developed for Mixed Conifer, Ponderosa pine (Pinus ponderosa Dougl. Ex Laws.) and Pinyon-Juniper (Pinus edulis Engelm.) (Juniperus monosperma Engelm.) cover types from one time measurements made in the .Santa Fe watershed located in the Sangre de Cristo Mountains of northern New Mexico. Additional fuel sampling occurred at Los Alamos National Laboratory (LANL) located in the Jemez Mountains of Northern New Mexico. Use of these or similar prediction equations may be limited to certain regions and community types that exhibit similar regional characteristics such as terrain, soils, and weather conditions. …

Go to article

On The Error Performance Of 8-Vsb Tcm Decoder For Atsc Terrestrial Broadcasting Of Digital Television, Dojun Rhee, Robert H. Morelos-Zaragoza Jan 2000

On The Error Performance Of 8-Vsb Tcm Decoder For Atsc Terrestrial Broadcasting Of Digital Television, Dojun Rhee, Robert H. Morelos-Zaragoza

Faculty Publications

The error performance of various 8-VSB TCM decoders for reception of terrestrial digital television is analyzed. In previous work, 8-state TCM decoders were proposed and implemented for terrestrial broadcasting of digital television. In this paper, the performance of a 16-state TCM decoder is analyzed and simulated. It is shown that not only a 16-state TCM decoder outperforms one with 8-states, but it also has much smaller error coefficients.

Go to article

Aqueous Equilibria: Acids, Bases, And Solubility. A General Chemistry Laboratory Experiment, Michael A. Janusa Jan 2000

Aqueous Equilibria: Acids, Bases, And Solubility. A General Chemistry Laboratory Experiment, Michael A. Janusa

Faculty Publications

We refer to two major types of general chemistry freshman laboratory experiments: discovery and cookbook. The typical Freshman enrolled in general chemistry has the skills to perform an experiment that is somewhere between cookbook and discovery, and we have developed a laboratory experiment that is midway between these extremes. This experiment aids the student's understanding of the concept of aqueous equilibria. In this experiment, students are asked to prepare and measure the pH of a variety of acidic and basic solutions. Students are also asked to calculate pH values from literature dissociation constants and dissociation constants from their experimental pH …

Go to article

Solidification / Stabilization Of Lead With The Aid Of Bagasse As An Additive To Portland Cement, Michael A. Janusa Jan 2000

Solidification / Stabilization Of Lead With The Aid Of Bagasse As An Additive To Portland Cement, Michael A. Janusa

Faculty Publications

Solidification/stabilization (S/S) of hazardous waste is a widely used technology; therefore, it is crucial to evaluate its effectiveness and make attempts to improve the technique. A better matrix for S/S of hazardous waste was designed that is effective and economically feasible. This was accomplished by adding bagasse (byproduct of milling or diffusing sugar cane) to the waste/cement matrix. Lead nitrate was used as the model heavy metal waste with a 10or 15% lead by weight to cement loading. Samples were cured for 7, 14, and 28 days at 24°C. Samples containing bagasse typically resulted in TCLP (modified) extract lead concentrations …

Go to article

Palladium-Catalyzed Carboxylative Coupling Of Allylstannanes And Allyl Halides, Russell J. Franks Jan 2000

Palladium-Catalyzed Carboxylative Coupling Of Allylstannanes And Allyl Halides, Russell J. Franks

Faculty Publications

A three-component carboxylative coupling between allyl halides, allylstannanes, and CO2 to produce allyl esters is catalyzed by Pd and Pt phosphine complexes. Allyl chloride and allyltributylstannane are thus converted to propenyl butenoate in excellent yield. Cross coupling of two different allyl components produces a nearly statistical mixture of all four possible esters. Tentative mechanistic pathways for the catalytic reaction are proposed.

Go to article

Erratum: "Cell Size Dependence Of Transport Coefficients In Stochastic Particle Algorithms", Alejandro Garcia, F. Alexander, B. Alder Jan 2000

Erratum: "Cell Size Dependence Of Transport Coefficients In Stochastic Particle Algorithms", Alejandro Garcia, F. Alexander, B. Alder

Faculty Publications

No abstract provided.

Go to article

Effect Of Interfacial Tension On Propagating Polymerization Fronts, R. Texier-Picard, J. A. Pojman, Vit A. Volpert Jan 2000

Effect Of Interfacial Tension On Propagating Polymerization Fronts, R. Texier-Picard, J. A. Pojman, Vit A. Volpert

Faculty Publications

This paper is devoted to the investigation of polymerization fronts converting a liquid monomer into a liquid polymer. We assume that the monomer and the polymer are immiscible and study the influence of the interfacial tension on the front stability. The mathematical model consists of the reaction-diffusion equations coupled with the Navier-Stokes equations through the convection terms. The jump conditions at the interface take into account the interfacial tension. Simple physical arguments show that the same temperature distribution could not lead to Marangoni instability for a nonreacting system. We fulfill a linear stability analysis and show that interaction of the …

Go to article

Lie Semigroups With Triple Decompositions, Jimmie Lawson, Yongdo Lim Jan 2000

Lie Semigroups With Triple Decompositions, Jimmie Lawson, Yongdo Lim

Faculty Publications

In this paper we establish that the causal order determined by an Ol'shanski semigroup on the corresponding homogeneous space is globally hyperbolic. Using this fact, we present sufficient conditions for a special class of Lie semigroups to admit a canonical "triple decomposition," namely those for which the Lie algebra is of Cayley type. This theory applies in particular to semigroups which are naturally associated to euclidean Jordan algebras as the semigroup of compressions of the symmetric cone of the algebra.

Go to article

Generalized Δ-Y Exchange And K-Regular Matroids, James Oxley, Charles Semple, Dirk Vertigan Jan 2000

Generalized Δ-Y Exchange And K-Regular Matroids, James Oxley, Charles Semple, Dirk Vertigan

Faculty Publications

This paper introduces a generalization of the matroid operation of Δ-Y exchange. This new operation, segment-cosegment exchange, replaces a coindependent set of k collinear points in a matroid by an independent set of k points that are collinear in the dual of the resulting matroid. The main theorem of the first half of the paper is that, for every field, or indeed partial field, F, the class of matroids representable over F is closed under segment-cosegment exchanges. It follows that, for all prime powers q, the set of excluded minors for GF(q)-representability has at least 2q-4 members. In the second …

Go to article

Exact Relations For Effective Tensors Of Composites: Necessary Conditions And Sufficient Conditions, Yury Grabovsky, Graeme W. Milton, Daniel S. Sage Jan 2000

Exact Relations For Effective Tensors Of Composites: Necessary Conditions And Sufficient Conditions, Yury Grabovsky, Graeme W. Milton, Daniel S. Sage

Faculty Publications

Typically the elastic and electrical properties of composite materials are strongly microstructure dependent. So it comes as a nice surprise to come across exact formulae for effective moduli that are universally valid no matter what the microstructure. Such exact formulae provide useful benchmarks for testing numerical and actual experimental data and for evaluating the merit of various approximation schemes. They can also be regarded as fundamental invariances existing in a given physical context. Classic examples include Hill's formulae for the effective bulk modulus of a two-phase mixture when the phases have equal shear moduli, Levin's formulae linking the effective thermal …

Go to article

Lower Bounds For Two-Level Additive Schwarz Preconditioners With Small Overlap, Susanne C. Brenner Jan 2000

Lower Bounds For Two-Level Additive Schwarz Preconditioners With Small Overlap, Susanne C. Brenner

Faculty Publications

Lower bounds for the condition numbers of the preconditioned systems are obtained for two-level additive Schwarz preconditioners. They show that the known upper bounds for both second order and fourth order problems are sharp in the case of a small overlap.

Go to article

Trimethyl(Trifluorovinyl)Silane, Roxana M. Trifu, George L. Gould Jan 2000

Trimethyl(Trifluorovinyl)Silane, Roxana M. Trifu, George L. Gould

Faculty Publications

No abstract provided.

Go to article

Gravitational Radiation From Schwarzschild Black Holes: The Second-Order Perturbation Formalism, Reinaldo J. Gleiser, Carlos O. Nicasio, Richard H. Price, Jorge Pullin Jan 2000

Gravitational Radiation From Schwarzschild Black Holes: The Second-Order Perturbation Formalism, Reinaldo J. Gleiser, Carlos O. Nicasio, Richard H. Price, Jorge Pullin

Faculty Publications

The perturbation theory of black holes has been useful recently for providing estimates of gravitational radiation from the black-hole collisions. Second-order perturbation theory, relatively undeveloped until recently, has proved to be important both for providing refined estimates and for indicating the range of validity of perturbation theory. Here we review the second-order formalism for perturbations of Schwarzschild spacetimes. The emphasis is on practical methods for carrying out the second-order computations of the outgoing radiation. General issues are illustrated throughout with examples from "close-limit" results, perturbation calculations in which black holes start from the small separation. © 2000 Elsevier Science B.V.

Go to article

Grazing Collisions Of Black Holes Via The Excision Of Singularities, Steve Brandt, Randall Correll, Roberto Gómez, Mijan Huq, Pablo Laguna, Luis Lehner, Pedro Marronetti, Richard A. Matzner, David Pullin, Jorge Pullin, Erik Schnetter, Deirdre Shoemaker, Jeffrey Winicour Jan 2000

Grazing Collisions Of Black Holes Via The Excision Of Singularities, Steve Brandt, Randall Correll, Roberto Gómez, Mijan Huq, Pablo Laguna, Luis Lehner, Pedro Marronetti, Richard A. Matzner, David Pullin, Jorge Pullin, Erik Schnetter, Deirdre Shoemaker, Jeffrey Winicour

Faculty Publications

We present the first simulations of non-headon (grazing) collisions of binary black holes in which the black hole singularities have been excised from the computational domain. Initially two equal mass black holes m are separated a distance ≈10m and with impact parameter ≈2m. Initial data are based on superposed, boosted (velocity ≈0.5c) solutions of single black holes in Kerr-Schild coordinates. Both rotating and non-rotating black holes are considered. The excised regions containing the singularities are specified by following the dynamics of apparent horizons. Evolutions of up to t≈35m are obtained in which two initially separate apparent horizons are present for …

Go to article

Photodetachment In Combined Static And Dynamic Electric Fields, Chitra Rangan, A. P. Rau Jan 2000

Photodetachment In Combined Static And Dynamic Electric Fields, Chitra Rangan, A. P. Rau

Faculty Publications

Through an exact solution of the time-dependent Schrödinger equation for an electron in a static electric field plus the time-dependent electric field of the detaching radiation, the photodetachment cross section of [Formula Presented] is calculated. Careful attention is paid to ensuring proper limiting behavior as the frequency of the time-dependent field goes to zero. We do not find observable effects of a cross term between the two fields on the detachment cross section. Our results point to possible gauge dependence and other difficulties of S-matrix formulations of multiphoton detachment and ionization. © 2000 The American Physical Society.

Go to article

Similarity Analysis Of Nonlinear Equations And Bases Of Finite Wavelength Solitons, A. Ludu, G. Stoitcheva, J. P. Draayer Jan 2000

Similarity Analysis Of Nonlinear Equations And Bases Of Finite Wavelength Solitons, A. Ludu, G. Stoitcheva, J. P. Draayer

Faculty Publications

We introduce a generalized similarity analysis which grants a qualitative description of the localised solutions of any nonlinear differential equation. This procedure provides relations between amplitude, width, and velocity of the solutions, and it is shown to be useful in analysing nonlinear structures like solitons, dublets, triplets, compact supported solitons and other patterns. We also introduce kink-antikink compact solutions for a nonlinear-nonlinear dispersion equation, and we construct a basis of finite wavelength functions having self-similar properties.

Go to article

Arrangements And Local Systems, Daniel C. Cohen, Peter Orlik Jan 2000

Arrangements And Local Systems, Daniel C. Cohen, Peter Orlik

Faculty Publications

We use stratified Morse theory to construct a complex to compute the cohomology of the complement of a hyperplane arrangement with coefficients in a complex rank one local system. The linearization of this complex is shown to be the Aomoto complex of the arrangement. Using this result, we establish the relationship between the cohomology support loci of the complement and the resonance varieties of the Orlik-Solomon algebra for any arrangement, and show that the latter are unions of subspace arrangements in general, resolving a conjecture of Falk. We also obtain lower bounds for the local system Betti numbers in terms …

Go to article

A Mathematical Model For Spatially Varying Extracellular Matrix, J. C. Dallon, J. A. Sherratt Jan 2000

A Mathematical Model For Spatially Varying Extracellular Matrix, J. C. Dallon, J. A. Sherratt

Faculty Publications

Orientation of extracellular matrix fibers in the skin is a key ingredient of tissue appearance and function, and differences in fiber alignment are one of the main distinctions between scar tissue and normal skin. In this paper, the authors develop a mathematical model for alignment of collagen fibers and the fibroblast cells that remodel them; the model extends previous work in which spatial variation was excluded. Numerical simulations of the model are presented, which show spatial variations in alignment over long transients, but with spatially uniform behavior in the long term. This is investigated further via asymptotic analysis, using the …

Go to article

Modeling The Effect Of Plasticizer On The Viscoelastic Response Of Crosslinked Polymers Using The Tube-Junction Model, P. P. Simon, Harry J. Ploehn Jan 2000

Modeling The Effect Of Plasticizer On The Viscoelastic Response Of Crosslinked Polymers Using The Tube-Junction Model, P. P. Simon, Harry J. Ploehn

Faculty Publications

Plasticizers modify the mechanical properties of polymericmaterials. The effects of plasticizers on glass transition temperatures can be most clearly observed in isochronal temperature sweep profiles of viscoelastic dynamic moduli. However, no simple mathematical models of plasticization are available to those who wish to design and employ plasticized materials in specific applications. We extend a phenomenological, molecular-level model (known as the tube–junction model) for crosslinked polymers to describe the effect of plasticizers on dynamic moduli. We show that the increase in free volume fraction due to the presence of the plasticizer can account for the shift in the glass transition in …

Go to article

Diffusion Of Water In Nafion 115 Membranes, Sathya Motupally, Aaron J. Becker, John W. Weidner Jan 2000

Diffusion Of Water In Nafion 115 Membranes, Sathya Motupally, Aaron J. Becker, John W. Weidner

Faculty Publications

In this paper, experimental and simulated data for the diffusion of water across Nafion membranes as a function of the water activity gradient are presented. The gradient in the activity of water across the membrane was varied by changing the flow rate and pressure of nitrogen gas on one side of the membrane. The other side of the membrane was equilibrated with liquid water. It was found that the model predictions are very sensitive to the value of the diffusion coefficient of water in Nafion. Using the Fickian diffusion coefficient extracted from self-diffusion measurements reported in the literature, the model …

Go to article

Self‐Discharge Model Of A Nickel‐Hydrogen Cell, B. Wu, Ralph E. White Jan 2000

Self‐Discharge Model Of A Nickel‐Hydrogen Cell, B. Wu, Ralph E. White

Faculty Publications

No abstract provided.

Go to article

Expert Qualifications: Traps For The Unwary, Paul C. Giannelli Jan 2000

Expert Qualifications: Traps For The Unwary, Paul C. Giannelli

Faculty Publications

No abstract provided.

Go to article

The Pathology Of Property Norms: Living Within Nature's Boundaries, Lynda L. Butler Jan 2000

The Pathology Of Property Norms: Living Within Nature's Boundaries, Lynda L. Butler

Faculty Publications

No abstract provided.

Go to article

A Semianalytical Method For Predicting Primary And Secondary Current Density Distributions: Linear And Nonlinear Boundary Conditions, Dhanwa Thirumalai, Ralph E. White Jan 2000

A Semianalytical Method For Predicting Primary And Secondary Current Density Distributions: Linear And Nonlinear Boundary Conditions, Dhanwa Thirumalai, Ralph E. White

Faculty Publications

No abstract provided.

Go to article

Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov Jan 2000

Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov

Faculty Publications

It is shown that an electrodeposited Zn-Ni-Cd alloy coating produced from sulfate electrolyte inhibits the discharge of hydrogen on carbon steel. The newly developed ternary alloys have approximately ten times higher corrosion resistance when compared to a Zn-Ni alloy. Hydrogen permeation characteristics of Zn-Ni-Cd alloy coatings were studied and compared with those of a bare and a Zn-Ni alloy coated steel. The transfer coefficient, a, exchange current density, io, thickness dependent adsorption-absorption rate constant, k0, recombination rate constant, k3, surface hydrogen coverage, θH, were obtained by applying a mathematical model to experimental results. Alloys obtained from baths containing higher concentration …

Go to article

Modeling Lithium Intercalation Of A Single Spinel Particle Under Potentiodynamic Control, Dong Zhang, Branko N. Popov, Ralph E. White Jan 2000

Modeling Lithium Intercalation Of A Single Spinel Particle Under Potentiodynamic Control, Dong Zhang, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model is presented for the lithium intercalation of a single spinel particle as a microelectrode under the stimulus of a cyclic linear potential sweep. The model includes both lithium diffusion within the particle and kinetics at the particle/electrolyte interface. The model is used to predict that peak current densities depend linearly on the scan rate to a certain power with a constant term, which is different from the predicted peak current density for a conventional redox system.

Go to article

Shrinking Core Model For The Discharge Of A Metal Hydride Electrode, Venkat R. Subramanian, Harry J. Ploehn, Ralph E. White Jan 2000

Shrinking Core Model For The Discharge Of A Metal Hydride Electrode, Venkat R. Subramanian, Harry J. Ploehn, Ralph E. White

Faculty Publications

A shrinking core model is presented for the galvanostatic discharge of a metal hydride particle. A quantitative criterion for when the shrinking core can be completely neglected or approximated by a pseudosteady-state solution is presented. The effect of shrinking of the core on the discharge behavior of a metal hydride particle is also studied.

Go to article

First Prev Next Last