Search results for "SIP"

Rich dynamics and anticontrol of extinction in a prey-predator system

2019

This paper reveals some new and rich dynamics of a two-dimensional prey-predator system and to anticontrol the extinction of one of the species. For a particular value of the bifurcation parameter, one of the system variable dynamics is going to extinct, while another remains chaotic. To prevent the extinction, a simple anticontrol algorithm is applied so that the system orbits can escape from the vanishing trap. As the bifurcation parameter increases, the system presents quasiperiodic, stable, chaotic and also hyperchaotic orbits. Some of the chaotic attractors are Kaplan-Yorke type, in the sense that the sum of its Lyapunov exponents is positive. Also, atypically for undriven discrete sys…

Dissipation evidence for the quantum damped harmonic oscillator via pseudo-bosons

2011

It is known that a self-adjoint, time-independent hamiltonian can be defined for the quantum damped harmonic oscillator. We show here that the two vacua naturally associated to this operator, when expressed in terms of pseudo-bosonic lowering and raising operators, appear to be non square-integrable. This fact is interpreted as the evidence of the dissipation effect of the classical oscillator at a purely quantum level.

LOCAL STRONG AND COULOMB POTENTIALS IN THE THREE-NUCLEON SYSTEM

1976

Publisher Summary This chapter focuses on local strong and Coulomb potentials in the three-nucleon system. Attempts to use local potentials in three-nucleon calculations with the Faddeev equations are impeded by the fact that for increasing energies contributions from higher and higher subsystem, angular momentum states become important, which quickly make the system of coupled equations unwieldy. However, if long-range interactions such as the Coulomb potential were added, such a procedure would not be useful at all. Several approaches exist that deal with the problems arising from the infinite range of the latter. In the work of Noble and Bencze, the Faddeev equations are modified so that…

m-bonacci metamaterial multilayers: location of the zero-average index bandgap edges

2009

We examine quasiperiodic multilayers arranged in m-bonacci sequences, which combine ordinary positiveindex materials and dispersive metamaterials with negative index in a certain frequency range. When the volume-averaged refractive index of the nonperiodic multilayer equals zero, the structure does not propagate light radiation and exhibits a forbidden band. We identify some analytical expressions to determine the upper and lower limits of the above zero-average refractive-index bandgap. We recognize that these limits are not explicitly dependent on the geometrical parameters of the stack of layers. © 2009 Optical Society of America. Fil: Monsoriu, J.A.. Universidad Politécnica de Valencia;…

Joule heating and the thermal evolution of old neutron stars

1998

We consider Joule heating caused by dissipation of the magnetic field in the neutron star crust. This mechanism may be efficient in maintaining a relatively high surface temperature in very old neutron stars. Calculations of the thermal evolution show that, at the late evolutionary stage ($t \geq 10$ Myr), the luminosity of the neutron star is approximately equal to the energy released due to the field dissipation and is practically independent of the atmosphere models. At this stage, the surface temperature can be of the order of $3 \times 10^{4} - 10^{5}$K. Joule heating can maintain this high temperature during extremely long time ($\geq 100$ Myr), comparable with the decay time of the m…

Configuration-interaction calculations of jellium clusters by the nuclear shell model

1994

Configuration-interaction (CI) calculations are performed on Na clusters of up to 20 atoms within the spherical jellium model, with particular attention paid to the magic clusters with N=2, 8, and 20. The interacting valence electrons are assumed to move in the Coulomb field of the jellium core. The numerical work is carried out by the nuclear-structure code oxbash modified to handle LS coupling. The many-particle bases are constructed of harmonic-oscillator single-particle states extending over 11 major shells and, alternatively, of single-particle states generated by the local-spin-density approximation (LSDA). The calculated quantities include ground- and excited state energies, ionizati…

Nonlinear energy dissipation in a cellular automaton magnetotail field model

1999

A magnetic field model of the magnetotail current sheet based on cellular automaton (CA) is presented. The present isotropic model is a continuously driven, two-dimensional running CA. The model has a physical interpretation in terms of magnetohydrodynamic (MHD) equations, and features self-organized critical (SOC) behavior with power-law scalings both in durations and sizes of instabilities (avalanches). The model has nonlinear energy dissipation, and shows avalanches with and without an external trigger. Thus the model reproduces some of the statistical features recently observed in the magnetotail.

Nonresonant holeburning in the Terahertz range: Brownian oscillator model

2003

The response to the field sequence of nonresonant hole burning, a pump-wait-probe experiment originally designed to investigate slow relaxation in complex systems, is calculated for a model of Brownian oscillators, thus including inertial effects. In the overdamped regime the model predictions are very similar to those of the purely dissipative stochastic models investigated earlier, including the possibility to discriminate between dynamic homogeneous and heterogeneous relaxation. The case of underdamped oscillations is of particular interest when low-frequency excitations in glassy systems are considered. We show that also in this situation a frequency selective modification of the respon…

Linear response theory: many-body formulation

2013

Fluctuations, response and aging dynamics in a simple glass-forming liquid out of equilibrium

1999

By means of molecular dynamics computer simulations we investigate the out of equilibrium relaxation dynamics of a simple glass former, a binary Lennard-Jones system, after a quench to low temperatures. We study both one time quantities and two-times correlation functions. Two-times correlation functions show a strong time and waiting time $t_w$ dependence. For large $t_w$ and times corresponding to the early $\beta$-relaxation regime the correlators approach the Edwards-Anderson value by means of a power-law in time. at long times $\tau$ the correlation functions can be expressed as $C_{\rm AG}(h(t_w+\tau)/h(t_w))$ and compute the function $h(t)$. This function is found to show a $t$-depen…