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1.
The phase diagram of the coupled sine circle map system exhibits a variety of interesting phenomena including spreading regions
with spatiotemporal intermittency, non-spreading regions with spatial intermittency, and coherent structures termed solitons.
A spreading to non-spreading transition is seen in the system. A cellular automaton version of the coupled system maps the
spreading to non-spreading transition to a transition from a probabilistic to a deterministic cellular automaton. The solitonic
sector of the system shows spatiotemporal intermittency with soliton creation, propagation and absorption. A probabilistic
cellular automaton mapping is set up for this sector which can identify each one of these phenomena.
相似文献
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We introduce a dynamical model of coupled directed percolation systems with two particle species. The two species A and B are coupled asymmetrically in that A particles branch B particles, whereas B particles prey on A particles. This model may describe epidemic spreading controlled by reactive immunization agents. We study nonequilibrium phase transitions with attention focused on the multicritical point where both species undergo the absorbing phase transition simultaneously. In one dimension, we find that the inhibitory coupling from B to A is irrelevant and the model belongs to the unidirectionally coupled directed percolation class. On the contrary, a mean-field analysis predicts that the inhibitory coupling is relevant and a new universality appears with a variable dynamic exponent. Numerical simulations on small-world networks confirm our predictions. 相似文献
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Asymptotic Analysis for a Vlasov-Fokker-Planck/ Compressible Navier-Stokes System of Equations 总被引:1,自引:0,他引:1
This article is devoted to the asymptotic analysis of a system of coupled kinetic and fluid equations, namely the Vlasov-Fokker-Planck
equation and a compressible Navier-Stokes equation. Such a system is used, for example, to model fluid-particle interactions
arising in sprays, aerosols or sedimentation problems. The asymptotic regime corresponding to a strong drag force and a strong
Brownian motion is studied and the convergence toward a two phase macroscopic model is proved. The proof relies on a relative
entropy method.
A. Mellet was partially supported by NSF grant DMS-0456647. 相似文献
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When exposed to a corona discharge, a dielectric droplet spreads over a grounded substrate. In the present work, the spreading of dielectric liquids subjected to a short-term exposure is investigated. A simple theoretical model was developed to find the spreading law at the very beginning of exposure. The asymptotic approximation for the surface charge density and the interfacial pressure showed that the droplet spreading immediately after the exposure obeys t1/2 law. The high speed imaging of the spreading revealed the same trend as predicted by the theoretical model. 相似文献
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针对准中性Vlasov-Poisson系统中多尺度物理参数共存的问题开展研究,采用渐近保持格式推导出与Vlasov方程相耦合的Poisson方程。数值模拟了一维等离子体在真空中的膨胀,比较了渐近保持PIC算法与传统PIC算法模拟结果的异同。结果表明:两种算法在满足多尺度中小尺度量限制的前提下,其结果保持高度一致;且在克服小尺度量束缚时,渐近保持PIC算法依然可以正确地模拟等离子体的物理行为,大大节省了计算时间。 相似文献
8.
针对准中性Vlasov-Poisson系统中多尺度物理参数共存的问题开展研究,采用渐近保持格式推导出与Vlasov方程相耦合的Poisson方程。数值模拟了一维等离子体在真空中的膨胀,比较了渐近保持PIC算法与传统PIC算法模拟结果的异同。结果表明:两种算法在满足多尺度中小尺度量限制的前提下,其结果保持高度一致;且在克服小尺度量束缚时,渐近保持PIC算法依然可以正确地模拟等离子体的物理行为,大大节省了计算时间。 相似文献
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We discuss the spatiotemporal intermittency (STI) seen in the coupled sine circle map lattice. The phase diagram of this system, when updated with random initial conditions, shows very rich behaviour including synchronised solutions, and STI of various kinds. These behaviours are organised around the bifurcation boundary of the synchronised solutions, as well as an infection line which separates the lower part of the phase diagram into a spreading and a non-spreading regime. The STI seen at the bifurcation boundary in the spreading regime belongs convincingly to the directed percolation (DP) universality class. In the non-spreading regime, spatial intermittency (SI) with temporally regular bursts is seen at the bifurcation boundary. The laminar length distribution scales as a power-law with an exponent which is quite distinct from DP behaviour. Therefore, both DP and non-DP universality classes are seen in this system. When the coupled map lattice is mapped to a cellular automaton via coarse graining, a transition from a probabilistic cellular automaton to a deterministic cellular automaton at the infection line signals the transition from spreading to non-spreading behaviour. 相似文献
11.
Variational iteration method for solving the mechanism of the Equatorial Eastern Pacific El Nino-Southern Oscillation
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A class of coupled system for the E1 Nifio-Southern Oscillation (ENSO) mechanism is studied. Using the method of variational iteration for perturbation theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behaviour of solution for corresponding problem is considered. 相似文献
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We study the asymptotic dynamics of a driven spin-boson system
where the environment is formed by a broadened localized mode.
Upon exploiting an exact mapping, an equivalent formulation of the
problem in terms of a quantum two-state system (qubit) coupled to
a harmonic oscillator which is itself Ohmically damped, is found.
We calculate the asymptotic population difference of the two
states in two complementary parameter regimes. For weak damping
and low temperature, a perturbative Floquet-Born-Markovian master
equation for the qubit-oscillator system can be solved. We find
multi-photon resonances corresponding to transitions in the
coupled quantum system and calculate their line-shape
analytically. In the complementary parameter regime of strong
damping and/or high temperatures, non-perturbative real-time path
integral techniques yield analytic results for the resonance line
shape. In both regimes, we find very good agreement with exact
results obtained from a numerical real-time path-integral
approach. Finally, we show for the case of strong detuning between
qubit and oscillator that the width of the n-photon resonance
scales with the nth Bessel function of the driving strength in
the weak-damping regime. 相似文献
13.
We derive a system of coupled linear integral equations to determine the dynamical impurity spin susceptibility in the Kondo problem. It is shown that a high temperature solution of these equations is possible by an asymptotic expansion. This yields a Korringa width as one would expect from heuristic arguments. 相似文献
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Corrections to the hydrodynamic limit for an infinite chain of coupled harmonic oscillators are obtained. This makes more precise the asymptotic picture for this type of evolution of a system with infinitely many degrees of freedom. 相似文献
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In this paper, a class of coupled system for the El Ni no/La Ni na southern oscillation (ENSO) atmospheric physics oscillation model is considered. We propose an ENSO atmospheric physics model using a method from the asymptotic theory. It is indicated from the results that the asymptotic method can be used for analyzing the sea surface temperature anomaly and the thermocline depth anomaly of the atmosphere-ocean oscillation for the ENSO model in the equatorial Pacific. 相似文献
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We investigate the spreading processes of epidemic diseases among many residential sites for different disease characteristics and different population distributions by constructing and solving a set of integrodifferential equations for the evolutions of position-dependent infected and infective rates, taking into account the infection processes both within a single site and among different sites. In a spreading process the states of an individual include susceptible (S), incubative (I), active (A) and recovered (R) states. Although the transition from S to I mainly depends on the active rate, the susceptible rate and the connectivity among individuals, the transitions from I to A and from A to R are determined by intrinsic characteristics of disease development in individuals. We adopt incubation and infection periods to describe the intrinsic features of the disease. By numerically solving the equations we find that the asymptotic behavior of the spreading crucially depends on the infection period and the population under affection of an active individual. Other factors, such as the structure of network and the popular distribution, play less important roles. The study may provide useful information for analyzing the key parameters affecting the dynamics and the asymptotic behavior. 相似文献
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Wille E Spiegelhalder FM Kerner G Naik D Trenkwalder A Hendl G Schreck F Grimm R Tiecke TG Walraven JT Kokkelmans SJ Tiesinga E Julienne PS 《Physical review letters》2008,100(5):053201
We report on the observation of Feshbach resonances in an ultracold mixture of two fermionic species, (6)Li and (40)K. The experimental data are interpreted using a simple asymptotic bound state model and full coupled channels calculations. This unambiguously assigns the observed resonances in terms of various s- and p-wave molecular states and fully characterizes the ground-state scattering properties in any combination of spin states. 相似文献
19.
In the context of an idealized model describing an atom coupled to black-body radiation at a sufficiently high positive temperature,
we show that the atom will end up being ionized in the limit of large times. Mathematically, this is translated into the statement
that the coupled system does not have any time-translation invariant state of positive (asymptotic) temperature, and that
the expectation value of an arbitrary finite-dimensional projection in an arbitrary initial state of positive (asymptotic)
temperature tends to zero, as time tends to infinity. These results are formulated within the general framework of W
*-dynamical systems, and the proofs are based on Mourre's theory of positive commutators and a new virial theorem. Results
on the so-called standard form of a von Neumann algebra play an important role in our analysis. 相似文献
20.
We experimentally prove that light propagation in a discrete system, i.e., an array of coupled waveguides, exhibits striking anomalies. We show that refraction is restricted to a cone, irrespective of the initial tilt of the beam. Diffraction can be controlled in size and sign by the input conditions. Diffractive beam spreading can even be arrested and diverging light can be focused. The results can be thoroughly theoretically explained. 相似文献