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General features of Hugoniots-II

Description: The author has derived a differential version of the Principal Hugoniot jump relations for a shock wave. From this algebraic equation, relating equation of state and U{sub s} - U{sub p} Hugoniot variables, I explain the general features of the Hugoniot, including two regions of linearity, limiting forms, and insensitivity to shell structure.
Date: January 1, 1997
Creator: Johnson, J. D.
Partner: UNT Libraries Government Documents Department
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Inertia, stability and ductility in uniaxial tension at high strain rate

Description: The influence of inertia on the necking process in the dynamic tensile test has been studied. The equations of motion for a bar of finite length elongation dynamically have been written assuming a one-dimensional state of stress, and a model for rate independent or rate dependent flow has been presented. For rate dependent flow, a description of the stress-strain rate law that takes into account the increase of strain rate sensitivity in the dynamic range has been introduced. The growth of an a… more
Date: January 1, 1985
Creator: Regazzoni, G.; Follansbee, P.S. & Johnson, J.N.
Partner: UNT Libraries Government Documents Department
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On traveling wave solutions of a set of coupled Boussinesq-like equations

Description: A set of coupled partial differential equations of Boussinesq type are derived in the continuum limit from the equations of motion of Toda lattice with a transversal degree of freedom. Here the numerical stability of a hybrid traveling wave solution of such system (with longitudinal and transversal components) is investigated.
Date: June 1, 1990
Creator: Muto, V.; Lomdahl, P.S. (Los Alamos National Lab., NM (USA)) & Christiansen, P.L. (Technical Univ. of Denmark, Lyngby (Denmark). Lab. of Applied Mathematical Physics)
Partner: UNT Libraries Government Documents Department
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[Numerical and physical modelling of bubbly flow phenomena]

Description: The objective of the research was to develop a sound theoretical framework for analyzing various two-phase flows. The macroscopic behavior of these flows depends on the details of the microstructure of the dispersion, and these details, in turn, depend on the nature of the flow. Given the very diverse nature of the flows and their complex dependence on the microstructure of the dispersion, it is unlikely that a single set of equations, similar to the Navier-Stokes equations for homogeneous flui… more
Date: January 1, 1992
Partner: UNT Libraries Government Documents Department
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The trajectory analysis of bevel planetary gear trains

Description: In this paper, the trajectory of bevel planetary wear trains has been studied. The parametric equations of trajectory are derived. It is shown that the trajectory generated by a tracer point on the planet of a bevel planetary gear train is analogous to that of a spur planetary gear train. Two cases, gear ratio equal to one and two, are presented in detail including the geometric description, plane of symmetry, extent of trajectory, number of nodes (cusps) their locations. The criteria for the e… more
Date: January 1, 1991
Creator: Lin, Chen-Chou & Tsai, Lung-Wen.
Partner: UNT Libraries Government Documents Department
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Local full-wave energy in nonuniform plasmas

Description: The subject of local wave energy in plasmas is treated via quasilinear theory from the dual perspectives of the action-angle formalism and gyrokinetics analysis. This work presents an extension to all orders in the gyroradius of the self-consistent wave-propagation/quasilinear-absorption problem using gyrokinetics. Questions of when and under what conditions local energy should be of definite sign are best answered using the action-angle formalism. An important result is that the ''dielectric o… more
Date: October 1, 1988
Creator: Smithe, D.N.
Partner: UNT Libraries Government Documents Department
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Extended rate equations

Description: The equations of motion are discussed which describe time dependent population flows in an N-level system, reviewing the relationship between incoherent (rate) equations, coherent (Schrodinger) equations, and more general partially coherent (Bloch) equations. Approximations are discussed which replace the elaborate Bloch equations by simpler rate equations whose coefficients incorporate long-time consequences of coherence.
Date: January 30, 1981
Creator: Shore, B. W.
Partner: UNT Libraries Government Documents Department
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The dual description of long-distance QCD (Dual QCD)

Description: We construct and solve a local field theory which describes in terms of dual variables a system having an A{sub {mu}} propagator behaving like M{sup 2}/q{sup 4} in the infrared and discuss how this theory can be used as a starting point for describing long-distance QCD. 3 refs.
Date: January 1, 1990
Creator: Baker, M.
Partner: UNT Libraries Government Documents Department
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Transverse wake effects in an optical waveguide IFEL accelerator

Description: A recent proposal describes a project to build a short demonstration stage IFEL accelerator using as input beam the output of the Accelerator Test Facility high brightness linac (ATF) currently under construction at BNL. A second stage of the proposal involves the design and construction of a GeV IFEL accelerator. Both IFEL accelerators could be built using standard focussing as discussed in the proposal. While this is fairly natural in the short (60cm) demonstration accelerator, it requires mu… more
Date: August 13, 1987
Creator: Sandweiss, J.
Partner: UNT Libraries Government Documents Department
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Theory of the Dielectric Wakefield Accelerator

Description: The general theory for all angular modes m of the dielectric wakefield accelerator is reformulated. The expressions for the accelerating electric fields and transverse wake forces are written in terms of matrices, the zeros of one of which determine the excitation frequencies of the dielectric structure. In this scheme it is possible to obtain a maximum accelerating gradient of 2.0 megavolts per meter per nanoCoulomb of driver beam charge, for a driver beam of 0.7 millimeters rms bunch length. … more
Date: October 1, 1990
Creator: Mtingwa, S. K.
Partner: UNT Libraries Government Documents Department
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Stability of orbits in nonlinear mechanics for finite but very long times

Description: In various applications of nonlinear mechanics, especially in accelerator design, it would be useful to set bounds on the motion for finite but very long times. Such bounds can be sought with the help of a canonical transformation to new action-angle variables (J, {Psi}), such that action J is nearly constant while the angle {Psi} advances almost linearly with the time. By examining the change in J during a time T{sub 0} from many initial conditions in the open domain {Omega} of phase space, on… more
Date: July 1, 1990
Creator: Warnock, R.L. & Ruth, R.D.
Partner: UNT Libraries Government Documents Department
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A Test of the Age Theory (Part I)

Description: The Selengut-Goertzel and the P/sub 1/-approximations to the Boltzmann equation for the neutron slowing down process in a medium of finite extent are rewritten as integral equations over Placzek functions. In this form, the equations can be solved by iteration; also, in the asymptotic case, they permit the corresponding age equations to be read off directly. The first order nonasymptotic deviations of the flux from the age theoretical expressions are calculated. (auth)
Date: August 1, 1958
Creator: Sauer, A.
Partner: UNT Libraries Government Documents Department
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Steepest Descent for Partial Differential Equations of Mixed Type

Description: The method of steepest descent is used to solve partial differential equations of mixed type. In the main hypothesis for this paper, H, L, and S are Hilbert spaces, T: H -> L and B: H -> S are functions with locally Lipshitz Fréchet derivatives where T represents a differential equation and B represents a boundary condition. Define ∅(u) = 1/2 II T(u) II^2. Steepest descent is applied to the functional ∅. A new smoothing technique is developed and applied to Tricomi type equations (which are of … more
Date: August 1992
Creator: Kim, Keehwan
Partner: UNT Libraries

Hyperbolic Monge-Ampère Equation

Description: In this paper we use the Sobolev steepest descent method introduced by John W. Neuberger to solve the hyperbolic Monge-Ampère equation. First, we use the discrete Sobolev steepest descent method to find numerical solutions; we use several initial guesses, and explore the effect of some imposed boundary conditions on the solutions. Next, we prove convergence of the continuous Sobolev steepest descent to show local existence of solutions to the hyperbolic Monge-Ampère equation. Finally, we prov… more
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Date: August 2006
Creator: Howard, Tamani M.
Partner: UNT Libraries
open access

Response to Comment on "Geometric Phase of the Gyromotion for Charged Particles in a Time-dependent Magnetic Field

Description: The reformulation of our analysis on the geometric phase of the gyromotion [J. Liu and H. Qin, Phys. Plasmas 18, 072505 (2011)] in terms of spatial angles presented in the comment by Brizard and Guillebon is interesting and correct. The subtlety of whether the adiabatic term associated with the long term average of the variation of pitch angle completely disappears after the gyrophase average is related to where valid approximations are applied. But it has no impact on the main conclusions.
Date: August 22, 2012
Creator: Qin, Jian Liu and Hong
Partner: UNT Libraries Government Documents Department
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Wave equations for pulse propagation

Description: Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecu… more
Date: June 24, 1987
Creator: Shore, B. W.
Partner: UNT Libraries Government Documents Department
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Impact of the nuclear equation of state on models of rotating neutron stars

Description: The impact of the nuclear equation of state on the properties of rotating neutron stars from two different sources, stable rotation at the general relativistic Kepler period and rotation at the gravitational radiation-reaction driven instability mode, is analyzed. For this purpose models of rotating neutron stars are constructed in the framework of Einstein's theory of general relativity by applying a refined version of Hartle's perturbative stellar structure equations. The investigation is bas… more
Date: June 3, 1991
Creator: Weber, F. & Glendenning, N.K.
Partner: UNT Libraries Government Documents Department
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A new'' approach to the quantitative statistical dynamics of plasma turbulence: The optimum theory of rigorous bounds on steady-state transport

Description: The fundamental problem in the theory of turbulent transport is to find the flux {Gamma} of a quantity such as heat. Methods based on statistical closures are mired in conceptual controversies and practical difficulties. However, it is possible to bound {Gamma} by employing constraints derived rigorously from the equations of motion. Brief reviews of the general theory and its application to passive advection are given. Then, a detailed application is made to anomalous resistivity generated by … more
Date: June 1, 1990
Creator: Krommes, J.A. (Princeton Univ., NJ (USA). Plasma Physics Lab.) & Kim, Chang-Bae (Texas Univ., Austin, TX (USA). Inst. for Fusion Studies)
Partner: UNT Libraries Government Documents Department
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Harmonically excited orbital variations

Description: Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can … more
Date: August 6, 1985
Creator: Morgan, T.
Partner: UNT Libraries Government Documents Department
open access

Beam position monitor analysis

Description: A large proportion of devices used to interact with charged-particle beams in accelerator or storage rings can be classified as pick-ups or kickers. These devices extract information about the particle motion or affect a change in the motion. One device used frequently as pick-up or kicker is made with two little plates with one or more terminations per plate. In this paper the structure with one termination per plate is examined. The azimuthal dependence is taken into account in circular geome… more
Date: March 1, 1989
Creator: Di Massa, G. & Ruggiero, A. G.
Partner: UNT Libraries Government Documents Department
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