Search results for "wise"
showing 10 items of 369 documents
Kac-potential treatment of nonintegrable interactions.
2000
We consider d-dimensional systems with nonintegrable, algebraically decaying pairwise interactions. It is shown that, upon introduction of periodic boundary conditions and a long-distance cutoff in the interaction range, the bulk thermodynamics can be obtained rigorously by means of a Kac-potential treatment, leading to an exact, mean-field-like theory. This explains various numerical results recently obtained for finite systems in the context of ``nonextensive thermodynamics,'' and in passing exposes a strong regulator dependence not discussed in these studies. Our findings imply that, contrary to some claims, Boltzmann-Gibbs statistics are sufficient for a standard description of this cla…
Fluctuation dissipation ratio in an aging Lennard-Jones glass
1998
By using extensive Molecular Dynamics simulations, we have determined the violation of the fluctuation-dissipation theorem in a Lennard-Jones liquid quenched to low temperatures. For this we have calculated $X(C)$, the ratio between a one particle time-correlation function $C$ and the associated response function. Our results are best fitted by assuming that $X(C)$ is a discontinuous, piecewise constant function. This is similar to what is found in spin systems with one step replica symmetry breaking. This strengthen the conjecture of a similarity between the phase space structure of structural glasses and such spin systems.
Number of metastable states of a chain with competing and anharmonicΦ4−like interactions
1993
We investigate the number of metastable configurations of a Φ 4 -like model with competing and anharmonic interactions as a function of an effective coupling constant η. The model has piecewise harmonic nearest-neighbor and harmonic next-nearerst-neighbor interactions. The number M of metastable states in the configuration space increases exponentially with the number N of particles: M∞exp(vN). It is shown numerically that, outside the previously considered range |η|<1/3, v is approximately linearly decreasing with η for |η|<1 and that v=0 for η≥1. These findings can be understood by describing the metastable configurations as an arrangement of kink solitons whose width creases with η
Numerical viscosity in simulations of the two-dimensional Kelvin-Helmholtz instability
2020
The Kelvin-Helmholtz instability serves as a simple, well-defined setup for assessing the accuracy of different numerical methods for solving the equations of hydrodynamics. We use it to extend our previous analysis of the convergence and the numerical dissipation in models of the propagation of waves and in the tearing-mode instability in magnetohydrodynamic models. To this end, we perform two-dimensional simulations with and without explicit physical viscosity at different resolutions. A comparison of the growth of the modes excited by our initial perturbations allows us to estimate the effective numerical viscosity of two spatial reconstruction schemes (fifth-order monotonicity preservin…
Rollvection versus linearvection: Comparison of brain activations in PET
2004
We conducted a PET study to directly compare the differential effects of visual motion stimulation that induced either rollvection about the line of sight or forward linearvection along this axis in the same subjects. The main question was, whether the areas that respond to vection are identical or separate and distinct for rollvection and linearvection. Eleven healthy volunteers were exposed to large-field (100 degrees x 60 degrees ) visual motion stimulation consisting of (1) dots accelerating from a focus of expansion to the edge of the screen (forward linearvection) and (2) dots rotating counterclockwise in the frontal plane (clockwise rollvection). These two stimuli, which induced appa…
Advanced models for nonlocal magneto-electro-elastic multilayered plates based on Reissner mixed variational theorem
2019
In the present work, nonlocal layer-wise models for the analysis of magneto-electro-elastic multilayered plates are formulated. An Eringen non-local continuum behaviour is assumed for the layers material; in particular, as usual in plate theories, partial in-plane nonlocality is assumed whereas local constitutive behaviour is considered in the thickness direction. The proposed plate theories are obtained via the Reissner Mixed Variational Theorem, assuming the generalized displacements and generalized out-of-plane stresses as primary variables, and expressing them as through-the-thickness expansions of suitably selected functions, considering the expansion order as a free parameter. In the …
Tunable liquid lens equipped virtual reality adapter for scientific, medical, and therapeutic goals
2018
We adapted virtual reality appliances to use them in scientific medical diagnostics and therapeutic aims by incorporated as part of appliance ocular system two electrically tunable Optotune liquid lenses, controllable by computer USB ports within 20D range. In present time we used the appliance to investigate the mono- and/or binocularly illusory perception dominances (Shapiro and al;2008), nonlinearities caused by controversial Gestalt recognition of motion. Back layer of stimuli elements contained internal motion sources - clockwise spinning disk on neutral background. Disk consisted of centrosymmetric radial rays which luminance was sinus mode modulated along the disc circumference. Spin…
Piecewise static Hamiltonian for an atom in strong laser field
2009
We show that it is possible to use a piecewise constant Hamiltonian to describe the main features of the dynamics of an atom interacting with a laser field. In particular we show that using this approximation we are able to give a good description of the ionization signal, of the HHG spectra and of the attosecond pulses generated by the radiating electron. Finally, we give an explicit formula to evaluate the ionization rate in the time dependent laser field. This formula, which is a generalization of the Landau formula for the ionization rate of an atom in a static electric field, fairly well reproduces the numerical ionization rates for a broad range of laser frequency and intensity. The m…
Two-Dimensional Boundary Layer Equations: High Resolution Capturing Methods
1993
In this paper we apply the piecewise hyperbolic and parabolic essentially non-oscillatory (ENO) capturing schemes (see [2] and [4]) to approximate the solution to the boundary layer equations for two-dimensional incompressible flow. We have tested several numerical examples analyzing their resolutive power and efficiency with respect to small values of the kinematic viscosity of the flow.
Models and solution methods for the uncapacitatedr-allocationp-hub equitable center problem
2017
Hub networks are commonly used in telecommunications and logistics to connect origins to destinations in situations where a direct connection between each origin–destination (o-d) pair is impractical or too costly. Hubs serve as switching points to consolidate and route traffic in order to realize economies of scale. The main decisions associated with hub-network problems include (1) determining the number of hubs (p), (2) selecting the p-nodes in the network that will serve as hubs, (3) allocating non-hub nodes (terminals) to up to r-hubs, and (4) routing the pairwise o-d traffic. Typically, hub location problems include all four decisions while hub allocation problems assume that the valu…