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State space forecasting and noise reduction

Description: We discuss the effects of nonlinearity and noise on the problem of finding states and dynamics. We point out problems which arise in the construction of state space models for scalar time series. We describe solutions for the case when error due to noise dominates parameter estimation error and outline a framework for the general case.
Date: January 1, 1990
Creator: Eubank, S.; Casdagli, M.; Farmer, J.D. & Gibson, J.
Partner: UNT Libraries Government Documents Department

Geometric Hamiltonian structures and perturbation theory

Description: We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging.
Date: August 1, 1984
Creator: Omohundro, S.
Partner: UNT Libraries Government Documents Department

Center of buoyancy definition

Description: The center of buoyancy of an arbitrary shaped body is defined in analogy to the center of gravity. The definitions of the buoyant force and center of buoyancy in terms of integrals over the area of the body are converted to volume integrals and shown to have simple intuitive interpretations.
Date: December 1, 1988
Creator: Sandberg, V.
Partner: UNT Libraries Government Documents Department

On the computer simulation of the EPR-Bohm experiment

Description: We argue that supraluminal correlation without supraluminal signaling is a necessary consequence of any finite and discrete model for physics. Every day, the commercial and military practice of using encrypted communication based on correlated, pseudo-random signals illustrates this possibility. All that is needed are two levels of computational complexity which preclude using a smaller system to detect departures from ''randomness'' in the larger system. Hence the experimental realizations of the EPR-Bohm experiment leave open the question of whether the world of experience is ''random'' or pseudo-random. The latter possibility could be demonstrated experimentally if a complexity parameter related to the arm length and switching time in an Aspect-type realization of the EPR-Bohm experiment is sufficiently small compared to the number of reliable total counts which can be obtained in practice. 6 refs.
Date: December 1, 1988
Creator: McGoveran, D.O.; Noyes, H.P. & Manthey, M.J.
Partner: UNT Libraries Government Documents Department

Diffraction radiation produced by a charged particle passing near or through a dielectric sphere

Description: We have derived expressions for the spectral distribution of diffraction radiation produced when a charged particle of constant velocity passes near or through a dielectric sphere of radius a. Our expressions, which are valid in the long wavelength limit ka << 1, describe the production of radiation as a function of the particle's impact parameter and energy and as a function of the dielectric property of the sphere. Our results reduce to forms similar to Rayleigh scattering of light when ka ..-->.. O and the impact parameter is large. Certain limiting cases of our expressions are found to be significantly different from the corresponding results previously published by other workers. 4 refs., 7 figs.
Date: January 1, 1985
Creator: Rule, D.W. & Ritchie, R.H.
Partner: UNT Libraries Government Documents Department

Note on Zeno's paradox in quantum theory

Description: A decaying quantum system, if observed very frequently in order to ascertain whether or not it is still undecayed, will not decay at all. The derivation of this effect - known, e.g., as Zeno's paradox - has been criticized recently. It has been argued that measurements performed in a very short time interval, ..delta..t, produce states with a very large energy uncertanty, ..delta..E, and that Zeno's paradox disappears if this is taken into account. By construction of an explicit counterexample it is proved, however, that there is no energy-time uncertainty relation of the required kind; therefore, the criticism mentioned is unjustified.
Date: February 1, 1980
Creator: Kraus, K.
Partner: UNT Libraries Government Documents Department

Unification of quantum theory and classical physics

Description: A program is described for unifying quantum theory and classical physics on the basis of the Copenhagen-interpretation idea of external reality and a recently discovered classical part of the electromagnetic field. The program effects an integration of the intuitions of Heisenberg, Bohr, and Einstein.
Date: July 1, 1985
Creator: Stapp, H.P.
Partner: UNT Libraries Government Documents Department

Degenerate perturbation theory

Description: The algebraic structure of degenerate Rayleigh-Schroedinger perturbation theory is reviewed. There are a number of different but equivalent algorithms which generate this perturbation series; we argue that the frequent need to carry out infinite-order partial summations selects one of these algorithms as the most efficient. Recent developments include coupled-cluster formulations for open shells, a new diagrammatic representation, and the concept of incomplete model subspaces. These subjects are reviewed, as well as some applications.
Date: January 1, 1982
Creator: Brandow, B.
Partner: UNT Libraries Government Documents Department

Analysis of nonlinear systems using ARMA (autoregressive moving average) models

Description: While many vibration systems exhibit primarily linear behavior, a significant percentage of the systems encountered in vibration and model testing are mildly to severely nonlinear. Analysis methods for such nonlinear systems are not yet well developed and the response of such systems is not accurately predicted by linear models. Nonlinear ARMA (autoregressive moving average) models are one method for the analysis and response prediction of nonlinear vibratory systems. In this paper we review the background of linear and nonlinear ARMA models, and illustrate the application of these models to nonlinear vibration systems. We conclude by summarizing the advantages and disadvantages of ARMA models and emphasizing prospects for future development. 14 refs., 11 figs.
Date: January 1, 1990
Creator: Hunter, N.F. Jr.
Partner: UNT Libraries Government Documents Department

Algorithmic randomness, physical entropy, measurements, and the second law

Description: Algorithmic information content is equal to the size -- in the number of bits -- of the shortest program for a universal Turing machine which can reproduce a state of a physical system. In contrast to the statistical Boltzmann-Gibbs-Shannon entropy, which measures ignorance, the algorithmic information content is a measure of the available information. It is defined without a recourse to probabilities and can be regarded as a measure of randomness of a definite microstate. I suggest that the physical entropy S -- that is, the quantity which determines the amount of the work {Delta}W which can be extracted in the cyclic isothermal expansion process through the equation {Delta}W = k{sub B}T{Delta}S -- is a sum of two contributions: the mission information measured by the usual statistical entropy and the known randomness measured by the algorithmic information content. The sum of these two contributions is a constant of motion'' in the process of a dissipation less measurement on an equilibrium ensemble. This conservation under a measurement, which can be traced back to the noiseless coding theorem of Shannon, is necessary to rule out existence of a successful Maxwell's demon. 17 refs., 3 figs.
Date: January 1, 1989
Creator: Zurek, W.H.
Partner: UNT Libraries Government Documents Department

The statistical properties of electromagnetic fields with application to radiation and scattering

Description: Determining the relationships between different average values is an important step in any physics-based statistical theory. If these relationships exist and exhibit certain properties, then probability densities or distributions can be assigned to the field variables and the transition from an average-value theory'' to a statistical theory'' is complete. For electromagnetics, no such average-value relationships have been demonstrated to exist. The derivation of these relationships and their range of validity are the subject of consideration here. For purposes of this discussion, we limit our attention to the fields inside a complex cavity, but with the ultimate goal of deriving the statistics of the far radiated and scattered fields of complex envelopes.
Date: January 1, 1991
Creator: Lehman, T.H. (Lehman (T.H.), Albuquerque, NM (USA)) & Miller, E.K. (Los Alamos National Lab., NM (USA))
Partner: UNT Libraries Government Documents Department

Quantum measurement and the mind-brain connection

Description: It is argued that quantum measurements do pose a problem, within the context created by the fundamental aim of science, which is identified as the construction of a cohesive, comprehensive, and rationally coherent idea of the nature of the world in which we live. Models of nature are divided into two classes: (1), those in which there is a selection process that, for any possible measurement, would, if that measurement were to be performed, pick out one single outcome, and, (2), all others. It is proved that any model of class that reproduces the predictions of quantum theory must violate the condition that there be no faster-than-light influences of any kind. This result is used to motivate the study of models in which unitary evolution is maintained and there is no selection of unique outcomes. A consideration of ontic probabilities, historical records, and the form of the mind-brain connection leads to an elaboration of the Everett many-worlds interpretation that appears to provide the basis of satisfactory solution of the measurement problem. 18 refs.
Date: October 17, 1990
Creator: Stapp, H.P.
Partner: UNT Libraries Government Documents Department

Einstein locality, EPR locality, and the significance for science of the nonlocal character of quantum theory

Description: The immense difference between Einstein locality and EPR locality is discussed. The latter provides a basis for establishing the nonlocal character of quantum theory, whereas the former does not. A model representing Heisenberg's idea of physical reality is introduced. It is nondeterministic and holistic: the objects, measuring devices, and their environment are treated as an inseparable entity, with, however, macroscopically localizable attributes. The EPR principle that no disturbance can propagate faster than light is imposed without assuming any structure incompatible with orthodox quantum thinking. This locality requirement renders the model incompatible with rudimentary predictions of quantum theory. A more general proof not depending on any model is also given. A recent argument that purports to show that quantum theory is compatible with EPR locality is examined. It illustrates the importance of the crucial one-world assumption. The significance for science of the failure of EPR locality is discussed.
Date: October 1, 1985
Creator: Stapp, H.P.
Partner: UNT Libraries Government Documents Department

The behavior of matter under nonequilibrium conditions: Fundamental aspects and applications. Progress Report for period April 15, 1990 - April 14, 1991

Description: Our report contains a brief summary of what has been achieved over the period of the contract. We have studied the behavior of matter under equilibrium conditions on three levels: (1) on the microscopic level in the frame of classical mechanics or of quantum theory; (2) on the stochastic level, which includes fluctuations; and (3) on the phenomenological, macroscopic level described by nonlinear equations. We first report on the level (1), then report on the levels (2) and (3).
Date: December 1, 1990
Creator: Prigogine, I.
Partner: UNT Libraries Government Documents Department

Destruction of the fractional quantum Hall effect by disorder

Description: It is suggested that Hall steps in the fractional quantum Hall effect are physically similar to those in the ordinary quantum Hall effect. This proposition leads to a simple scaling diagram containing a new type of fixed point, which is identified with the destruction of the fractional states by disorder. 15 refs., 3 figs.
Date: July 1, 1985
Creator: Laughlin, R.B.
Partner: UNT Libraries Government Documents Department

Spins of cyons and dyons

Description: We examine the meaning of the angular momentum of cyons in some detail and compare the cyon case with the more familiar case of the dyon composed of a spinless electron bound by a scalar force to a spinless magnetic monopole. This treatment differs from others not primarily in its results, but in its central point that those results follow from very simple and general properties of the angular momentum in the electromagnetic field. 6 refs., 4 figs.
Date: January 1, 1985
Creator: Lipkin, H.J. & Peshkin, M.
Partner: UNT Libraries Government Documents Department

Algorithms and computer codes for atomic and molecular quantum scattering theory. Volume I

Description: The goals of this workshop are to identify which of the existing computer codes for solving the coupled equations of quantum molecular scattering theory perform most efficiently on a variety of test problems, and to make tested versions of those codes available to the chemistry community through the NRCC software library. To this end, many of the most active developers and users of these codes have been invited to discuss the methods and to solve a set of test problems using the LBL computers. The first volume of this workshop report is a collection of the manuscripts of the talks that were presented at the first meeting held at the Argonne National Laboratory, Argonne, Illinois June 25-27, 1979. It is hoped that this will serve as an up-to-date reference to the most popular methods with their latest refinements and implementations.
Date: January 1, 1979
Creator: Thomas, L. (ed.)
Partner: UNT Libraries Government Documents Department

Red-shift experiments and non-Newtonian gravitational forces

Description: The contribution of scalar non-Newtonian gravitational forces to the gravitational red-shifts is derived. The constraints imposed on scalar couplings by red-shift experiments are shown to be not competitive with those imposed by geophysical inverse-square-law experiments. 7 refs.
Date: January 1, 1989
Creator: Hughes, R.J.; Goldman, T. & Nieto, M.M.
Partner: UNT Libraries Government Documents Department

Supercoherent states and physical systems

Description: A method is developed for obtaining coherent states of a system admitting a supersymmetry. These states are called supercoherent states. The approach presented in this talk is based on an extension to supergroups of the usual group-theoretic approach. The example of the supersymmetric harmonic oscillator is discussed, thereby illustrating some of the attractive features of the method. Supercoherent states of an electron moving in a constant magnetic field are also described. 35 refs.
Date: January 1, 1991
Creator: Fatyga, B.W.; Kostelecky, V.A. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics); Nieto, M.M. (Los Alamos National Lab., NM (USA)) & Truax, D.R. (Calgary Univ., AB (Canada). Dept. of Chemistry)
Partner: UNT Libraries Government Documents Department

Kinetic and fluid theory of microwave breakdown in air

Description: We have developed time-dependent fluid and kinetic treatments of electron transport in air in the presence of a propagating microwave pulse. In both cases the HPM pulses are assumed to be of short enough duration so that electron spatial diffusion can be neglected. In addition, we limit our calculations to the non-relativistic regime where effects due to the ponderomotive force are negligible. 6 refs., 4 figs.
Date: January 1, 1987
Creator: Roussel-Dupre, R.A.; Murphy, T. & Johnson, A.
Partner: UNT Libraries Government Documents Department

Maxwell's demon, Szilard's engine and quantum measurements

Description: We propose and analyze a quantum version of Szilard's one-molecule engine. In particular, we recover, in the quantum context, Szilard's conclusion concerning the free energy cost of measurements: ..delta..F greater than or equal to k/sub B/T1n2 per bit of information.
Date: January 1, 1984
Creator: Zurek, W.H.
Partner: UNT Libraries Government Documents Department