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Inclusive Gluon Production In Deep Inelastic Scattering At High Parton Density, Yuri V. Kovchegov, Kirill Tuchin Jan 2002

Inclusive Gluon Production In Deep Inelastic Scattering At High Parton Density, Yuri V. Kovchegov, Kirill Tuchin

Kirill Tuchin

We calculate the cross section of single inclusive gluon production in deep inelastic scattering at very high energies in the saturation regime, where the parton densities inside hadrons and nuclei are large and the evolution of structure functions with energy is nonlinear. The expression we obtain for the inclusive gluon production cross section is generated by this nonlinear evolution. We analyze the rapidity distribution of the produced gluons as well as their transverse momentum spectrum given by the derived expression for the inclusive cross section. We propose an ansatz for the multiplicity distribution of gluons produced in nuclear collisions which …


Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. Ii. Multivariant Phase Transformations And Stress Space Analysis, Valery I. Levitas, Dean L. Preston Jan 2002

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. Ii. Multivariant Phase Transformations And Stress Space Analysis, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

In this paper, the three-dimensional Landau model of austenite-martensite transformations constructed in Part I is generalized to include transformations between an arbitrary number of martensitic variants. The model can incorporate all temperature-dependent thermomechanical properties of both phases for arbitrary crystal symmetries, including higher-order elastic constants, and it correctly describes the characteristic features of stress-strain curves for shape-memory alloys and steels, namely, constant transformation strain tensors, constant or weakly temperature dependent stress hysteresis, and transformation at nonzero tangent moduli. Geometric representations of the conditions for phase equilibrium and phase transformations in six-dimensional stress space are developed. For the cubic-tetragonal phase transformation, …


Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. I. Austenite↔Martensite, Valery I. Levitas, Dean L. Preston Jan 2002

Three-Dimensional Landau Theory For Multivariant Stress-Induced Martensitic Phase Transformations. I. Austenite↔Martensite, Valery I. Levitas, Dean L. Preston

Valery I. Levitas

A three-dimensional Landau theory of stress-induced martensitic phase transformations is presented. It describes transformations between austenite and martensitic variants and transformations between martensitic variants. The Landau free energy incorporates all temperature-dependent thermomechanical properties of both phases. The theory accounts for the principal features of martensitic transformations in shape memory alloys and steels, namely, stress-strain curves with constant transformation strain and constant, or weakly temperature dependent, stress hysteresis, as well as nonzero tangent elastic moduli at the phase transformation point. In part I, the austenite↔martensite phase transformation is treated, while transformations between martensitic variants are considered in part II.


Low-Cost Manufacturing Process For Nanostructured Metals And Alloys, Travis L. Brown, Srinivasan Swaminathan, Srinivasan Chandrasekar, W. Dale Compton, Alexander H. King, Kevin P. Trumble Jan 2002

Low-Cost Manufacturing Process For Nanostructured Metals And Alloys, Travis L. Brown, Srinivasan Swaminathan, Srinivasan Chandrasekar, W. Dale Compton, Alexander H. King, Kevin P. Trumble

Alexander H. King

In spite of their interesting properties, nanostructured materials have found limited uses because of the cost of preparation and the limited range of materials that can be synthesized. It has been shown that most of these limitations can be overcome by subjecting a material to large-scale deformation, as occurs during common machining operations. The chips produced during lathe machining of a variety of pure metals, steels, and other alloys are shown to be nanostructured with grain (crystal) sizes between 100 and 800 nm. The hardness of the chips is found to be significantly greater than that of the bulk material.


Altitude Dependence Of Middleand Low-Latitude Thermospheric Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, G. G. Shepard, B. H. Solheim Jan 2002

Altitude Dependence Of Middleand Low-Latitude Thermospheric Disturbance Winds Measured By Windii, J. T. Emmert, Bela G. Fejer, G. G. Shepard, B. H. Solheim

Bela G. Fejer

[1] Thermospheric neutral winds exhibit strong altitudinal and latitudinal variation during geomagnetically quiet and active times. We use daytime middle and low-latitude neutral winds measured by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS) over the 90–275 km height range to study the altitude and season dependent climatology of disturbance winds (i.e., with quiet time patterns removed) in magnetic coordinates. The daytime perturbations winds are generally equatorward and westward and decrease toward the magnetic equator. Both the zonal and meridional components decrease sharply below 120 km and are essentially insignificant below 100 km. The …


Ultra-Dense Phosphorous Delta-Layer Grown Into Silicon From Ph3 Molecular Precursors, T. -C. Shen, J. -Y. Ji, M. A. Zudov, R. -R. Du, J. S. Kline, J. R. Tucker Jan 2002

Ultra-Dense Phosphorous Delta-Layer Grown Into Silicon From Ph3 Molecular Precursors, T. -C. Shen, J. -Y. Ji, M. A. Zudov, R. -R. Du, J. S. Kline, J. R. Tucker

T. -C. Shen

Phosphorous δ-doping layers were fabricated in silicon by PH3 deposition at room temperature, followed by low-temperature Si epitaxy.Scanning tunneling microscope images indicate large H coverage, and regions of c(2×2) structure. Hall data imply full carrier activation with mobility<40 cm2/V s when the surface coverage is ≲0.2 ML. Conductivity measurements show a ln(T) behavior at low temperatures, characteristic of a high-density two-dimensional conductor. Possible future applications to atom-scale electronics and quantum computation are briefly discussed.


Ripening Of Porous Media, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey Jan 2002

Ripening Of Porous Media, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey

Benny Davidovitch

We address the surface tension-driven dynamics of porous media in nearly saturated pore-space solutions. We linearize this dynamics in the reaction-limited regime near its fixed points – surfaces of constant mean curvature (CMC surfaces). We prove that the only stable interface for this dynamics is the plane, and estimate the time scale for a CMC surface to become unstable. We also discuss the differences between open and closed system dynamics, pointing out the unlikelihood that CMC surfaces are ever realized in these systems on any time scale.


Invaded Cluster Simulations Of The Xy Model In Two And Three, I. Dukovski, Jonathan Machta, L. V. Chayes Jan 2002

Invaded Cluster Simulations Of The Xy Model In Two And Three, I. Dukovski, Jonathan Machta, L. V. Chayes

Jonathan Machta

The invaded cluster algorithm is used to study the XY model in two and three dimensions up to sizes 20002 and 1203, respectively. A soft spin O(2) model, in the same universality class as the three-dimensional XY model, is also studied. The static critical properties of the model and the dynamical properties of the algorithm are reported. The results are Kc=0.45412(2) for the three-dimensional XY model and η=0.037(2) for the three-dimensional XY universality class. For the two-dimensional XY model the results are Kc=1.120(1) and η=0.251(5). The invaded cluster algorithm does not show any critical slowing for the magnetization or critical …


Iterated Conformal Dynamics And Laplacian Growth, Felipe Barra, Benny Davidovitch, Itamar Procaccia Jan 2002

Iterated Conformal Dynamics And Laplacian Growth, Felipe Barra, Benny Davidovitch, Itamar Procaccia

Benny Davidovitch

The method of iterated conformal maps for the study of diffusion limited aggregates (DLA) is generalized to the study of Laplacian growth patterns and related processes. We emphasize the fundamental difference between these processes: DLA is grown serially with constant size particles, while Laplacian patterns are grown by advancing each boundary point in parallel, proportional to the gradient of the Laplacian field. We introduce a two-parameter family of growth patterns that interpolates between DLA and a discrete version of Laplacian growth. The ultraviolet putative finite-time singularities are regularized here by a minimal tip size, equivalently for all the models in …


Quantum Corrections To The Reissner–Nordström And Kerr-Newman Metrics, John Donoghue, Barry R. Holstein, Björn Garbrecht, Thomas Konstandin Jan 2002

Quantum Corrections To The Reissner–Nordström And Kerr-Newman Metrics, John Donoghue, Barry R. Holstein, Björn Garbrecht, Thomas Konstandin

John Donoghue

We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of non-analytic pieces , q2log(−q2), etc. in the form factors of the energy–momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner–Nordström and Kerr–Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order ℏ/mr3


Coiling Instabilities Of Multilamellar Tubes, Christian Santangelo, P. Pincus Jan 2002

Coiling Instabilities Of Multilamellar Tubes, Christian Santangelo, P. Pincus

Christian Santangelo

Myelin figures are densely packed stacks of coaxial cylindrical bilayers that are unstable to the formation of coils or double helices. These myelin figures appear to have no intrinsic chirality. We show that such cylindrical membrane stacks can develop an instability when they acquire a spontaneous curvature or when the equilibrium distance between membranes is decreased. This instability breaks the chiral symmetry of the stack and may result in coiling. A unilamellar cylindrical vesicle, on the other hand, will develop an axisymmetric instability, possibly related to the pearling instability.


Classical Gluodynamics In Curved Space-Time And The Soft Pomeron, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin Jan 2002

Classical Gluodynamics In Curved Space-Time And The Soft Pomeron, Dmitri Kharzeev, Eugene Levin, Kirill Tuchin

Kirill Tuchin

QCD at the classical level possesses scale invariance which is broken by quantum effects. This "dimensional transmutation" phenomenon can be mathematically described by formulating classical gluodynamics in a curved, conformally flat, space-time with non-vanishing cosmological constant. We study QCD high-energy scattering in this theory. We find that the properties of the scattering amplitude at small momentum transfer are determined by the energy density of vacuum fluctuations. The approach gives rise to the power growth of the total hadron-hadron cross section with energy, i.e., the pomeron. The intercept of the pomeron and the multiplicity of produced particles are evaluated. We also …


A Simple Demonstration Of Mie Scattering Using An Overhead Projector, Charles L. Adler, James A. Lock Jan 2002

A Simple Demonstration Of Mie Scattering Using An Overhead Projector, Charles L. Adler, James A. Lock

James A. Lock

No abstract provided.


Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia Jan 2002

Comment On ‘‘Stress-Density Ratio Slip-Corrected Reynolds Equation For Ultra-Thin Film Gas Bearing Lubrication’’, Alejandro Garcia

Alejandro Garcia

No abstract provided.


High-Order Interaction Of Solitary Waves On Shallow Water, Prof. Tim Marchant Dec 2001

High-Order Interaction Of Solitary Waves On Shallow Water, Prof. Tim Marchant

Tim Marchant

The interaction of solitary waves on shallow water is examined to fourth order. At first order the interaction is governed by the Korteweg-de Vries (KdV) equation, and it is shown that the unidirectional assumption, of right-moving waves only, is incompatible with mass conservation at third order. To resolve this, a mass conserving system of KdV equations, involving both right- and left-moving waves, is derived to third order. A fourth-order interaction term, in which the right- and left-moving waves are coupled, is also derived as this term is crucial in determining the fourth-order change in solitary wave amplitude. The form of …


The Occurrence Of Limit-Cycles During Feedback Control Of Microwave Heating, Prof. Tim Marchant Dec 2001

The Occurrence Of Limit-Cycles During Feedback Control Of Microwave Heating, Prof. Tim Marchant

Tim Marchant

The microwave heating of one- and two-dimensional slabs, subject to linear feedback control, is examined. A semianalytical model of the microwave heating is developed using the Galerkin method. A local stability analysis of the model indicates that Hopf bifurcations occur; the regions of parameter space in which limit-cycles exist are identified. An efficient numerical scheme for the solution of the governing equations, which consist of the forced heat equation and a Helmholtz equation describing the electric-field amplitude, is also developed. An excellent comparison between numerical solutions of the semianalytical model and the governing equations is obtained for the temporal evolution …


Cubic Autocatalytic Reaction-Diffusion Equations: Semi-Analytical Solutions, Prof. Tim Marchant Dec 2001

Cubic Autocatalytic Reaction-Diffusion Equations: Semi-Analytical Solutions, Prof. Tim Marchant

Tim Marchant

The Gray-Scott model of cubic-autocatalysis with linear decay is coupled with diffusion and considered in a one-dimensional reactor (a reaction-diffusion cell). The boundaries of the reactor are permeable, so diffusion occurs from external reservoirs that contain fixed concentrations of the reactant and catalyst. The Galerkin method is used to approximate the spatial structure of the reactant and autocatalyst concentrations in the reactor. Ordinary differential equations are then obtained as an approximation to the governing partial differential equations. The ordinary differential equations are then analysed to obtain semi-analytical results for the reaction-diffusion cell. Steady-state concentration profiles and bifurcation diagrams are obtained …


Semi-Analytical Solutions For Continuous-Flow Microwave Reactors, Prof. Tim Marchant Dec 2001

Semi-Analytical Solutions For Continuous-Flow Microwave Reactors, Prof. Tim Marchant

Tim Marchant

A prototype chemical reaction is examined in both one and two-dimensional continuous-flow microwave reactors, which are unstirred so the effects of diffusion are important. The reaction rate obeys the Arrhenius law and the thermal absorptivity of the reactor contents is assumed to be both temperature- and concentration-dependent. The governing equations consist of coupled reaction-diffusion equations for the temperature and reactant concentration, plus a Helmholtz equation describing the electric-field amplitude in the reactor. The Galerkin method is used to develop a semi-analytical microwave reactor model, which consists of ordinary differential equations. A stability analysis is performed on the semi-analytical model. This …


The Initial Boundary Problem For The Korteweg-De Vries Equation On The Negative Quarter-Plane, Prof. Tim Marchant Dec 2001

The Initial Boundary Problem For The Korteweg-De Vries Equation On The Negative Quarter-Plane, Prof. Tim Marchant

Tim Marchant

The initial boundary-value problem for the Korteweg-de Vries (KdV) equation on the negative quarter-plane, x < 0 and t > 0, is considered. The formulation of this problem is different to the usual initial boundary-value problem on the positive quarter-plane, for which x > 0 and t > 0. Two boundary conditions are required at x = 0 for the negative quarter-plane problem, in contrast to the one boundary condition needed at x = 0 for the positive quarter-plane problem. Solutions of the KdV equation on the infinite line, such as the soliton, cnoidal wave, mean height variation and undular bore solution, are used to find approximate …


The Microwave Heating Of Three-Dimensional Blocks: Semi-Analytical Solutions, Prof. Tim Marchant Dec 2001

The Microwave Heating Of Three-Dimensional Blocks: Semi-Analytical Solutions, Prof. Tim Marchant

Tim Marchant

The microwave heating of three-dimensional blocks, by the transverse magnetic waveguide mode TM11, is considered in a long rectangular waveguide. The governing equations are the forced heat equation and a steady-state version of Maxwell's equations, while the boundary conditions take into account both convective and radiative heat loss. Semi-analytical solutions, valid for small thermal absorptivity, are found using the Galerkin method. The electrical conductivity and the thermal absorptivity are assumed to be temperature dependent, while both the electrical permittivity and magnetic permeability are taken to be constant. Both a quadratic relation and an Arrhenius-type law are used for the temperature …


Thermoelectric Properties Of K[Subscript 2]Bi[Subscript 8-X]Sb[Subscript X]Se[Subscript 13] Solid Solutions And Se Doping [Et Al.], Theodora Kyratski, Jeffrey Dyck, Wei Chen Dec 2001

Thermoelectric Properties Of K[Subscript 2]Bi[Subscript 8-X]Sb[Subscript X]Se[Subscript 13] Solid Solutions And Se Doping [Et Al.], Theodora Kyratski, Jeffrey Dyck, Wei Chen

Jeffrey Dyck

Our efforts to improve the thermoelectric properties of β-K2Bi8Se13, led to systematic studies of solid solutions of the type β-K2Bi8−xSbxSe13. The charge transport properties and thermal conductivities were studied for selected members of the series. Lattice thermal conductivity decreases due to the mass fluctuation generated in the lattice by the mixed occupation of Sb and Bi atoms. Se excess as a dopant was found to increase the figure-of merit of the solid solutions.


Numerical Solitary Wave Interaction: The Order Of The Inelastic Effect, Prof. Tim Marchant Dec 2001

Numerical Solitary Wave Interaction: The Order Of The Inelastic Effect, Prof. Tim Marchant

Tim Marchant

Solitary wave interaction is examined using an extended Benjamin-Bona-Mahony (eBBM) equation. This equation includes higher-order nonlinear and dispersive effects and is is asymptotically equivalent to the extended Korteweg-de Vries (eKdV) equation. The eBBM formulation is preferable to the eKdV equation for the numerical modelling of solitary wave collisions, due to the stability of its finite-difference scheme. In particular, it allows the interaction of steep waves to be modelled, which due to numerical instability, is not possible using the eKdV equation. Numerical simulations of a number of solitary wave collisions of varying nonlinearity are performed for two special cases corresponding to …


Analysis And Classification Of Nonlinear Dispersive Evolution Equations In The Potential Representation, Andrei Ludu Dec 2001

Analysis And Classification Of Nonlinear Dispersive Evolution Equations In The Potential Representation, Andrei Ludu

Andrei Ludu

No abstract provided.


What Do We Learn From The Local Geometry Of Glass-Forming Liquids?, Francis W. Starr, S. Sastry, J. F. Douglas, S. C. Glotzer Dec 2001

What Do We Learn From The Local Geometry Of Glass-Forming Liquids?, Francis W. Starr, S. Sastry, J. F. Douglas, S. C. Glotzer

Francis Starr

No abstract provided.


The Single Particle Potential In Mean-Field Theory, Peter Palffy-Muhoray Dec 2001

The Single Particle Potential In Mean-Field Theory, Peter Palffy-Muhoray

Peter Palffy-Muhoray

The problem of determining the single particle energy in a mean-field description of interacting particles is considered. It is shown that the single particle energy must satisfy two consistency conditions, and a general procedure for obtaining the single particle energy from the pair energy is proposed. Interacting dipolar systems are examined, current approaches in the literature are discussed, and the usefulness of the proposed method is demonstrated.


Translational And Rotational Diffusion In Stretched Water, P. A. Netz, Francis Starr, M. C. Barbosa, H. E. Stanley Dec 2001

Translational And Rotational Diffusion In Stretched Water, P. A. Netz, Francis Starr, M. C. Barbosa, H. E. Stanley

Francis Starr

No abstract provided.