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Why we don`t need quantum planetary dynamics, or on decoherence and the correspondence principle for chaotic systems

Description: Violation of correspondence principle may occur for very macroscopic byt isolated quantum systems on rather short timescales as illustrated by the case of Hyperion, the chaotically tumbling moon of Saturn, for which quantum and classical predictions are expected to diverge on a timescale of approximately 20 years. Motivated by Hyperion, we review salient features of ``quantum chaos`` and show that decoherence is the essential ingredient of the classical limit, as it enables one to solve the apparent paradox caused by the breakdown of the correspondence principle for classically chaotic systems.
Date: August 1, 1995
Creator: Zurek, W.H. & Pas, J.P.
Partner: UNT Libraries Government Documents Department

Linearized Semiclassical Initial Value Time Correlation FunctionsUsing the Thermal Gaussian Approximation: Applications to Condensed PhaseSystems

Description: The linearized approximation to the semiclassical initial value representation (LSC-IVR) has been used together with the thermal Gaussian approximation (TGA) (TGA/LSC-IVR) to simulate quantum dynamical effects in realistic models of two condensed phase systems. This represents the first study of dynamical properties of the Ne13 Lennard-Jones (LJ) cluster in its liquid-solid phase transition region (temperature from 4 K to 14 K). Calculation of the force autocorrelation function shows considerable differences from that given by classical mechanics, namely that the cluster is much more mobile (liquid-like) than in the classical case. Liquid para-hydrogen at two thermodynamic state points (25 K and 14 K under nearly zero external pressure) has also been studied. The momentum autocorrelation function obtained from the TGA/LSC-IVR approach shows very good agreement with recent accurate path integral Monte Carlo (PIMC) results at 25 K. The self-diffusion constants calculated by the TGA/LSC-IVR are in reasonable agreement with those from experiment and from other theoretical calculations. These applications demonstrate the TGA/LSC-IVR to be a practical and versatile method for quantum dynamics simulations of condensed phase systems.
Date: July 10, 2007
Creator: Liu, Jian & Miller, William H.
Partner: UNT Libraries Government Documents Department

Are partons confined tachyons?

Description: The author notes that if hadrons are gravitationally stabilized ``black holes``, as discrete physics suggests, it is possible that partons, and in particular quarks, could be modeled as tachyons, i.e. particles having v{sup 2} > c{sup 2}, without conflict with the observational fact that neither quarks nor tachyons have appeared as ``free particles``. Some consequences of this model are explored.
Date: March 1, 1996
Creator: Noyes, H.P.
Partner: UNT Libraries Government Documents Department

The evolution of consciousness

Description: It is argued that the principles of classical physics are inimical to the development of an adequate science of consciousness. The problem is that insofar as the classical principles are valid consciousness can have no effect on the behavior, and hence on the survival prospects, of the organisms in which it inheres. Thus within the classical framework it is not possible to explain in natural terms the development of consciousness to the high-level form found in human beings. In quantum theory, on the other hand, consciousness can be dynamically efficacious: quantum theory does allow consciousness to influence behavior, and thence to evolve in accordance with the principles of natural selection. However, this evolutionary requirement places important constraints upon the details of the formulation of the quantum dynamical principles.
Date: August 16, 1996
Creator: Stapp, H.P.
Partner: UNT Libraries Government Documents Department

Conceptual foundation of the Fokker-Planck approach to space-charge effects

Description: An rms-mismatched beam can evolve rapidly to a configuration of quasiequilibrium under the influence of space-charge forces. As sit evolves, its emittance grows and a diffuse halo forms. The beam's distribution function accounts for all the complicated dynamics. Unfortunately, the distribution function is difficult to calculate in as much as the physics lies at the interface between classical mechanics and thermodynamics. This paper presents the foundation for a statistical theory of the dynamics of nonequilibrium space-charge-dominated beams. Within certain approximations, the theory takes on a Fokker-Planck form. Key questions arise concerning the nature of the dynamical friction and diffusion in the beam's phase space and of the quasiequilibrium configuration that ensues.
Date: July 1, 1996
Creator: Bohn, C.L.
Partner: UNT Libraries Government Documents Department

Can a {open_quotes}superconductor{close_quotes} always expel the generalized magnetic field?

Description: The conservation of generalized helicity in a perfectly conducting fluid may act as an electrodynamic barrier for the transition to the London (superconducting) state when the system is immersed in a topologically nontrival magnetic field (with a nonzero generalized helicity). An experiment is proposed to test whether the mechanism responsible (quantum correlations) for superconductivity respects the electrodynamic constraint.
Date: March 10, 1998
Creator: Mahajan, S.M.
Partner: UNT Libraries Government Documents Department

An application of mechanical leverage to microactuation

Description: Preliminary results on the use of mechanical advantage to convert a short-displacement, high-force actuation mechanism into a long-displacement, medium-force actuator are presented. This micromechanical, mechanically-advantaged actuator is capable of relatively large displacement and force values. The target design values are lever ration of 17.5:1 leading to a {plus_minus}17.5 {mu}N of force throughout providing no less than 2.25 {mu}N of force throughout actuator`s range of motion for an applied voltage of less tan 50 volts. The basis for the mechanical advantage is simple levers with fulcrums.
Date: December 31, 1994
Creator: Sniegowski, J.J. & Smith, C.
Partner: UNT Libraries Government Documents Department

Equilibrium fluid interface behavior under low- and zero-gravity conditions. II

Description: We describe here recent mathematical results that form the basis of our forthcoming space experiment, developed jointly with Mark Weislogel of NASA Lewis Research Center, which is scheduled for the Glovebox on the Mir 23 / NASA 4 Mission in December 1996. The mathematical basis for the Angular Liquid Bridge is described. The anticipated liquid behavior used in the apparatus is illustrated.
Date: May 1, 1996
Creator: Concus, P. & Finn, R.
Partner: UNT Libraries Government Documents Department

Impact of random numbers on parallel Monte Carlo application

Description: A number of graduate students are involved at various level of research in this project. We investigate the basic issues in materials using Monte Carlo simulations with specific interest in heterogeneous materials. Attempts have been made to seek collaborations with the DOE laboratories. Specific details are given.
Date: October 22, 2002
Creator: Pandey, Ras B.
Partner: UNT Libraries Government Documents Department

Errata Report on Herbert Goldstein's Classical Mechanics, Second Edition

Description: This report describes errors in Herbert Goldstein's textbook Classical Mechanics, Second Edition (Copyright 1980, ISBN 0-201-02918-9). Some of the errors in current printings of the text were corrected in the second printing; however, after communicating with Addison Wesley, the publisher for ''Classical Mechanics'', it was discovered that the corrected galley proofs had been lost by the printer and that no one had complained of any errors in the eleven years since the second printing. The errata sheet corrects errors from all printings of the second edition.
Date: January 1, 1993
Creator: Unseren, M.A.
Partner: UNT Libraries Government Documents Department

Classical Model for Laser-Induced Non-Adiabatic Collision Processes

Description: By synthesizing earlier work of Orel and Miller and of Meyer, McCurdy, and Miller, a model for describing laser-induced electronically non-adiabatic collision processes is constructed which treats all degrees of freedom -- heavy particle (i.e,, translation, rotation, and vibration), electronic, and photon by classical mechanics. This then makes it relatively easy to carry out calculations to simulate such processes within a dynatnically consistent framework. Application is made to the test case H + LiF {yields} Li + HF reaction considered by Light and Altenberger-Siczek. The most interesting feature revealed by these classical calculations is maxima in the reaction probability as a function of initial translational energy at energies below the laser-free threshold. It is seen that this structure can be understood as a Franck-Condon-like effect.
Date: January 1, 1980
Creator: Orel, Ann E. & Miller, William H.
Partner: UNT Libraries Government Documents Department

Disoriented chiral condensates in hadron-hadron collisions

Description: The authors review recent progress in the description and understanding of disoriented chiral condensates. Certain important unsolved issues are underlined, and the preliminary results of the program of investigation of these issues in the framework of the classical linear sigma model are reported. They also briefly review a formalism which could be useful at the full non-equilibrium quantum field theory level of analysis.
Date: September 1, 1996
Creator: Amelino-Camelia, G.; Bjorken, J.D. & Larsson, S.E.
Partner: UNT Libraries Government Documents Department

Relativistic charged particle in the dipole-sphere configuration. II. General tilted surface orbits.

Description: Relativistic charged particle orbits on a rotating sphere threaded by an intense magnetic dipole field are examined. Generalizing the results of the first paper (I), the dipole and rotational axes have arbitrary relative tilt. For ultra-intense magnetic fields characteristic of compact astrophysical bodies, the classical and semiclassical results are not greatly changed for moderate rotation rates. 4 refs., 4 figs.
Date: March 1, 1997
Creator: Gopinath, K.S. & Kennedy, D.C.
Partner: UNT Libraries Government Documents Department

The phase space of the focused cubic Schroedinger equation: A numerical study

Description: In a paper of 1988 [41] on statistical mechanics of the nonlinear Schroedinger equation, it was observed that a Gibbs canonical ensemble associated with the nonlinear Schroedinger equation exhibits behavior reminiscent of a phase transition in classical statistical mechanics. The existence of a phase transition in the canonical ensemble of the nonlinear Schroedinger equation would be very interesting and would have important implications for the role of this equation in modeling physical phenomena; it would also have an important bearing on the theory of weak solutions of nonlinear wave equations. The cubic Schroedinger equation, as will be shown later, is equivalent to the self-induction approximation for vortices, which is a widely used equation of motion for a thin vortex filament in classical and superfluid mechanics. The existence of a phase transition in such a system would be very interesting and actually very surprising for the following reasons: in classical fluid mechanics it is believed that the turbulent regime is dominated by strong vortex stretching, while the vortex system described by the cubic Schroedinger equation does not allow for stretching. In superfluid mechanics the self-induction approximation and its modifications have been used to describe the motion of thin superfluid vortices, which exhibit a phase transition; however, more recently some authors concluded that these equations do not adequately describe superfluid turbulence, and the absence of a phase transition in the cubic Schroedinger equation would strengthen their argument. The self-induction approximation for vortices takes into account only very localized interactions, and the existence of a phase transition in such a simplified system would be very unexpected. In this thesis the authors present a numerical study of the phase transition type phenomena observed in [41]; in particular, they find that these phenomena are strongly related to the splitting of the phase space into distinctly ...
Date: May 1, 1998
Creator: Burlakov, Y.O.
Partner: UNT Libraries Government Documents Department

Properties of a single asperity and the interface between molecular dynamics and continuum mechanics: A commentary

Description: The speakers in this session attempted to bridge the large spatial gap between the atomistic processes occurring at a sliding interface and the continuum description of such processes. This task is indeed formidable. One may ask why should we study such elementary processes at all if what we are really interested in is a global picture of friction. Real surfaces are uneven, impure, and may be covered by nasty things like lubricants specifically placed there to modify frictional behavior. Isn`t the real world of friction too ``dirty`` to be studied by surface science techniques? Indeed, even if we were to understand the interaction of every geometry of single asperity under every environment, how to average this information to produce a model of friction is unknown. Does this mean that we shouldn`t attempt to measure and calculate these simple processes? I think not. Understanding the response of a single asperity is an important essential element which will lead to a thorough predictive understanding of friction. But clearly our work cannot end with the study of single asperities. There are two critical phenomena which have to be added to a single asperity model: first the inclusion of a distribution in both size and location of single asperities and second the role of microstructure evolution. Clearly single asperities do not respond independently from each other. The proximity of two asperities changes both the local stress distribution as well as the contact area. I believe the greatest challenge that faces us is how to assemble the vast amount of single asperity data that we can generate and from it create useful engineering models.
Date: December 1, 1995
Creator: Baskes, M.I.
Partner: UNT Libraries Government Documents Department

Errata report on Herbert Goldstein's Classical Mechanics: Second edition

Description: This report describes errors in Herbert Goldstein's textbook Classical Mechanics, Second Edition (Copyright 1980, ISBN 0-201-02918-9). Some of the errors in current printings of the text were corrected in the second printing; however, after communicating with Addison Wesley, the publisher for Classical Mechanics, it was discovered that the corrected galley proofs had been lost by the printer and that no one had complained of any errors in the eleven years since the second printing. The errata sheet corrects errors from all printings of the second edition.
Date: January 1, 1993
Creator: Unseren, M.A. & Hoffman, F.M.
Partner: UNT Libraries Government Documents Department

Errata report on Herbert Goldstein`s Classical Mechanics: Second edition

Description: This report describes errors in Herbert Goldstein`s textbook Classical Mechanics, Second Edition (Copyright 1980, ISBN 0-201-02918-9). Some of the errors in current printings of the text were corrected in the second printing; however, after communicating with Addison Wesley, the publisher for Classical Mechanics, it was discovered that the corrected galley proofs had been lost by the printer and that no one had complained of any errors in the eleven years since the second printing. The errata sheet corrects errors from all printings of the second edition.
Date: January 1, 1993
Creator: Unseren, M. A. & Hoffman, F. M.
Partner: UNT Libraries Government Documents Department

Scattering theory for the quantum envelope of a classical system

Description: Classical dynamics, reformulated in terms of its quantum envelope is studied for the stationary states of the interacting system. The dynamical variable of ``elapsed time`` plays a crucial role in this study. It is shown that the perturbation series for the elapsed time can be summed in various simple cases even when standard perturbation series diverge. For the special class of systems where the interactions fall off sufficiently fast at infinity one could define ``in`` and ``out`` states; and consequently the wave matrices and scattering matrices. The scattering phase shifts bear a simple relation to the time delay in scattering.
Date: December 31, 1993
Creator: Sudarshan, E. C. G.
Partner: UNT Libraries Government Documents Department