排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
S. E. Mangioni H. S. Wio 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(1):67-73
We analyze the effect of a colored non Gaussian noise on a model of
a random walker moving along a ratchet potential. Such a model was
motivated by the transport properties of motor proteins, like
kinesin and myosin. Previous studies have been realized assuming
white noises. However, for real situations, in general we could
expect that those noises be correlated and non Gaussian. Among other
aspects, in addition to a maximum in the current as the noise
intensity is varied, we have also found another optimal value of the
current when departing from Gaussian behavior. We show the relevant
effects that arise when departing from Gaussian behavior,
particularly related to current's enhancement, and discuss its
relevance for both biological and technological situations. 相似文献
2.
Mangioni SE Deza RR Toral R Wio HS 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):223-232
A recently introduced lattice model, describing an extended system which exhibits a reentrant (symmetry-breaking, second-order) noise-induced nonequilibrium phase transition, is studied under the assumption that the multiplicative noise leading to the transition is colored. Within an effective Markovian approximation and a mean-field scheme it is found that when the self-correlation time tau of the noise is different from zero, the transition is also reentrant with respect to the spatial coupling D. In other words, at variance with what one expects for equilibrium phase transitions, a large enough value of D favors disorder. Moreover, except for a small region in the parameter subspace determined by the noise intensity sigma and D, an increase in tau usually prevents the formation of an ordered state. These effects are supported by numerical simulations. 相似文献
3.
H. S. Wio M. San Miguel R. F. Rodriguez 《Zeitschrift für Physik A Hadrons and Nuclei》1989,333(1):109-110
The new neutronrich isotope 228 Rn was produced by spallation reactions induced by 600 MeV protons in a 232 Th target and identified by massseparation and decay spectroscopy. The Zassignment was confirmed via KX-rays and the genetic relationship to the wellknown daughter product 228 Fr. The halflife of 228 Rn is 65±2 s. Energies and relative intensities of prominent γ-rays are presented for the first time from the decay of both the new isotope 228 Rn and 227 Rn. 相似文献
4.
In order to study the effect of partially reflective (albedo) boundary conditions on pattern formation and stability in reaction-diffusion systems, we have analyzed an exactly soluble model of an electrothermal instability: the Ballast resistor. The present results allow a continuous interpolation between the results corresponding to Neumann and Dirichlet boundary conditions, and they allow qualitative changes in the patterns to be followed. 相似文献
5.
We study the formation and global stability of stationary patterns in a finite one-dimensional reaction-diffusion model of the activator-inhibitor type. The analysis proceeds through the study of the nonequilibrium potential or Lyapunov functional for this system considering the fast inhibitor case and, in order to obtain analytical results, the adoption of a piecewise linear version of the model. We have studied the changes in relative stability among the different patterns as the ratio between the diffusion coefficients is varied and have discussed the meaning of the different contributions to the nonequilibrium potential. 相似文献
6.
Julián I. Peña Rosselló Horacio S. Wio Roberto R. Deza Peter Hänggi 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(2):34
The performance of a ring of linearly coupled, monostable nonlinear oscillators is optimized towards its goal of acting as energy harvester – through piezoelectric transduction – of mesoscopic fluctuations, which are modeled as Ornstein-Uhlenbeck noises. For a single oscillator, the maximum output voltage and overall efficiency are attained for a soft piecewise-linear potential (providing a weak attractive constant force) but they are still fairly large for a harmonic potential. When several harmonic springs are linearly and bidirectionally coupled to form a ring, it is found that counter-phase coupling can largely improve the performance while in-phase coupling worsens it. Moreover, it turns out that few (two or three) coupled units perform better than more. 相似文献
7.
Silvia A. Menchón Horacio S. Wio 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(8):1-8
To investigate the statistical behavior in the sizes of finite clusters for percolation, cluster size distribution n s (p) for site and bond percolations at different lattices and dimensions was simulated using a modified algorithm. An equation to approximate the finite cluster size distribution n s (p) was obtained and expressed as: log?(n s (p)) = as ? b log?s + c. Based on the analysis of simulation data, we found that the equation is valid for p from 0 to 1 on site and for the bond percolation of two-dimensional (2D) and three-dimensional (3D) lattices. Furthermore, the relationship between the coefficients of the equation and the occupied ratio p was studied using the finite-size scaling method. When \(x = D(p - p_c )L^{y_t }\) , p < p c , and D was a nonuniversal metric factor. a was found to be related only to p, and the a-x curves of different lattices were nearly overlapped; b was related to the dimensions and p, and the scaled data of the b of all lattices with the same dimension tended to fall on the same curves. Unlike a and b, c apparently had a quadratic relation with x in 2D lattices and linear relation with x in 3D lattices. The results of this paper could significantly reduce the amount of tasks required to obtain numerical data of on the cluster size distribution for p from 0 to p c . 相似文献
8.
The problem of pattern formation by adsorbates undergoing attractive lateral interactions, is described by a parabolic integrodifferential equation having the scaled inverse temperature ? and the scaled pressure α of the vapor phase as parameters. A coexistence region of high- and low-coverage stable homogeneous states has been reported in the (?, α) plane. In the small interaction-range limit an effective diffusion coefficient can be defined, which becomes however negative for a coverage range in between the stable homogeneous ones. A novel free-energy-like Lyapunov functional is found here for this problem. When evaluated on the homogeneous states, it leads to a Maxwell-like construction which selects essentially the same value α(?) as the originally posited zero front-velocity condition. Moreover, its value on static fronts at this particular α(?) coincides with those of the homogeneous states. This article is dedicated to Prof. Helmut Brand with occasion of his 60th birthday. 相似文献
9.
We have extended the CTRW theory of Montroll and Weiss including the effect of extra variables, like the energy. This MCTRW scheme can be written in a simple matrix notation, that simplifies its solution. As an example of their usefulness we have studied a two-energy-group neutron diffusion problem. This has shown the peculiarities of the transient behaviour for the variance of the probability distribution, due to the coupling between the groups.Comisión Nacional de Energiá AtómicaComisión Nacional de Energía Atómica and Universidad Nacional de Cuyo 相似文献
10.
A generalization of pseudo-diffusion processes in media with anisotropic scattering, described by a coupled RW, is done by means of the CTRW theory. The behaviour of the probability distribution has been studied. A kind of phase breaking in such a behaviour arises as a function of the anisotropic parameter. Some examples, with different models for the waiting time density, are presented. In the limit of strong forward or backward scattering, we have a new way to analyze quasi-unidirectional or quasi-collapsed processes respectively.Also at Universidad Nacional del Comahue, Centro Regional BarilocheComisión Nacional de Energia AtómicaComisión Nacional de Energía Atómica and Universidad Nacional de Cuyo 相似文献