Development of an underwater manipulator for use on a free-swimming unmanned submersible / Peter Bosse, Paul J. Heckman, Jr.

Bosse, P. C.; Heckman, P.

doi:10.5962/bhl.title.47796

Cited by 4 publications

(6 citation statements)

References 1 publication

(1 reference statement)

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“…The dynamic correlation functions resemble, in the mostly chaotic regime, that of a strongly coupled liquid. Moreover, we find the transition from classically regular to classically chaotic motion to be associated with a "liquid-glass"-type transition in the parametric energylevel dynamics characterized by the disappearance of diffusion [13]. A simple analytic approximation for the spectrum of the velocity autocorrelation function whose form is suggested by the PO quantization in the semiclassical limit reproduces our results of the moleculardynamics simulation quite well.…”

Section: Introductionsupporting

confidence: 69%

“…Therefore, the identification with the dynamic state of a liquid is incomplete. While the shorttime dynamics of P(A) closely resembles a liquid, the long-time limit D(A)~0 corresponds to that of a glass [13]. Figure 5, finally, presents the results for the meansquared displacement (x ) of the energy levels.…”

Section: Semiclassical Estimates For Correlation Functionsmentioning

confidence: 96%

“…The properties of the VAF can be most conveniently analyzed in terms of its frequency spectrum G(co)= f dAcos(coA)g(A) . (13) 0 The motion of the particle contains both diffusive and vibratory components. The diffusive component is characterized by a nonzero value of G(0) while a vibratory component appears in G(co) as a peak at nonzero frequency.…”

Section: Introductionmentioning

confidence: 99%

“…The VAF satisfies a generalized Langevin equation (22) Furthermore, combining (20) and (21) (This approach underlies the mode-coupling approximations [13,23].) In the following we restrict ourselves to phenomenological approximations to the memory kernel which allow a simple ana-The interrelation between K (A), P{s), and G (co) implies that an approximation for any of these functions uniquely determines the others, in particular the VAF, the generalized diffusion coefficient, and the mean-squared displacement of the tagged particle.…”

Section: Introductionmentioning

confidence: 99%

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Parametric correlations and diffusion in quantum spectra

Yang

Burgdörfer

1992

Phys. Rev. A

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The evolution of the quantum spectrum as the function of a control parameter can be mapped onto the molecular dynamics of a classical many-body system. This approach is used to study the parametric motion of energy levels in classically mostly regular and in mostly chaotic regimes. The parametric energy-level dynamics is described in terms of the velocity autocorrelation function and the friction kernel of a disordered many-body system. We show that the parametric dynamics is sensitively dependent on the underlying classical dynamics, and therefore provide new measures of quantum chaology. The transition from classically regular to chaotic motion manifests itself in the disappearance of parametric diffusion. Semiclassical arguments give analytic approximations for the spectrum of the velocity autocorrelation function, and these approximations are found to be consistent with numerical calculations for the vibronic motion of a triatomic molecule. We compare these autocorrelation functions with those found in gases, liquids, and glasses.

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Section: Introductionsupporting

confidence: 69%

Section: Semiclassical Estimates For Correlation Functionsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Parametric correlations and diffusion in quantum spectra

Yang

Burgdörfer

1992

Phys. Rev. A

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“…This feature of single-particle motion is well described by mode-coupling theory developed in the last years. [3][4][5][6] This hydrodynamically founded theory has been supposed to be valid only at very low momentum transfers h Q (Q < 0.1 A " l ). 4 But it will be shown here that hydrodynamic behavior of single-particle motion in liquid sodium at high temperatures extends up to Q values of the order of 1 A ~l.…”

mentioning

confidence: 99%

Experimental evidence for the long-time decay of the velocity-autocorrelation in liquid sodium

et al. 1987

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Incoherent inelastic neutron-scattering experiments on liquid sodium at high temperature revealed that atomic motions in simple liquids are governed by hydrodynamic shear modes leading to measurable deviations from Fick's law of diffusion. The experiments for the first time verify earlier predictions of a "long-time tail" behavior of the velocity-autocorrelation function of liquid particles as derived from computer-simulation data and theory. A proper analysis of the experimental data demonstrates the existence of a corresponding low-frequency cusp in the velocity-autocorrelation spectrum.There is a long-standing interest in single-particle behavior in simple liquids since a distinct coupling effect between a single moving particle and its liquid environment has been first observed in computer simulations, 1 ' 2 where it was found that the velocity-autocorrelation function (VAF) of the liquid particles varies as t ~3 /2 for /-* oo. This effect was explained within a simple hydrodynamic picture taking long-living diffusive shear excitations in the liquid into account. Shear modes generated by the moving particle in its surroundings act back on the particle itself at a later time, thus leading to a slower decay of the velocity-autocorrelation function (v/(0) • v/(/)>. This feature of single-particle motion is well described by mode-coupling theory developed in the last years. 3-6 This hydrodynamically founded theory has been supposed to be valid only at very low momentum transfers h Q (Q < 0.1 A " l ). 4 But it will be shown here that hydrodynamic behavior of single-particle motion in liquid sodium at high temperatures extends up to Q values of the order of 1 A ~l.As a consequence we restrict ourselves in this Letter to the hydrodynamic low-g region (Q < 1 A -1 ) which in addition requires high energy resolution (AE < 0.05 meV), whereas in earlier attempts much larger Q values and poorer energy resolutions have been used. 7 Further, this study of mode-coupling effects in a simple liquid was performed at high temperature (7" = 803 K) and not as in previous experiments 7 near the triple point, where these effects are very small, as will become clearer below.A convenient experimental technique for the study of atomic motions on the time and space range of interest is neutron scattering. A neutron-scattering experiment determines the scattering law S(Q,co), the Fourier transform of the space-and time-dependent density correlation function. Incoherent scattering projects out Ss (Q, (o), the self-part of this function, which is well characterized by reduced half-width y(Q) and peak height 8 Z(Q) defined as y(Q)=a) l/2 (Q)/DQ\( 1) where cox/iiQ) is the measured half-width of Ss(Q,co) at constant Q, D is the self-diffusion coefficient of the liquid, and L(Q)-xDQ 2 S s (Q,0).Both quantities are normalized to ordinary diffusion (Fick's law), for which Ss(q,co) is a simple Lorentzian of half-width (0\/ 2 (Q) = DQ 2 and peak height SS(Q,0) = (KDQ 2 )-\

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