Revealing the building blocks of spatiotemporal chaos: deviations from extensivity

We have performed high-precision computational studies of the fractal dimension as a function of system length for spatiotemporal chaotic states of the one-dimensional complex Ginzburg-Landau equation. Our data show deviations from extensivity on a length scale consistent with the chaotic length scale, indicating that this spatiotemporal chaotic system is composed of weakly interacting building blocks, each containing about 2 degrees of freedom. Our results also suggest an explanation of some of the "windows of periodicity" found in spatiotemporal systems of moderate size.     

Channeling problem for charged particles produced by confining environment

Channeling problem produced by confining environment that leads to resonance scattering of charged particles via quasistationary states imbedded in the continuum is examined. Nonmonotonic dependence of physical parameters on collision energy and/or confining environment due to resonance transmission and total reflection effects is confirmed that can increase the rate of recombination processes. The reduction of the model for two identical charged ions to a boundary problem is considered together with the asymptotic behavior of the solution in the vicinity of pair-collision point and the results of R-matrix calculations. Tentative estimations of the enhancement factor and the total reflection effect are discussed. The text was submitted by the authors in English.     

Ordering chaos by random shortcuts

In this Letter, the effects of random shortcuts in an array of coupled nonlinear chaotic pendulums and their ability to control the dynamical behavior of the system are investigated. We show that random shortcuts can induce periodic synchronized spatiotemporal motions, even though all oscillators are chaotic when uncoupled. This process exhibits a nonmonotonic dependence on the density of shortcuts. Specifically, there is an optimal amount of random shortcuts, which can induce the most ordered motion characterized by the largest order parameter that is introduced to measure the spatiotemporal order. Our results imply that topological randomness can tame spatiotemporal chaos.     

Tetragonal Distortion of InN Thin Films by RBS/Channeling

Rutherford backscattering and channeling spectrometry （RBS/C） are used to identify the crystalline quality （Xmin = 4.87%） Of an InN thin film as a function of depth, and make a non-destructive quantitative analysis of the structure, in order to analyze the tetragonal distortion of the InN thin film at the depth determined.     

Channeling radiation and coherent bremsstrahlung

We show that calculations based on the use of Bloch functions in at least two-dimensions predict both coherent brems-strahlung peaks (k_CB) and channeling radiation peaks (k_CR) in the spectrum of photons emitted by electrons traversing a crystal when moving nearly parallel to a crystal plane; and that furthermore, “sidebands” (e.g., k_CB ± k_CR) are predicted when the electrons move nearly parallel to two intersecting crystal planes.     

时空混沌系统的主动-间隙耦合同步

提出了离散系统中的主动-间隙耦合同步方法。该方法由同步相和自治相组成,在同步相,同步方案使得混沌系统趋于同步,而在自治相,两系统间的误差将迅速放大,导致同步失去。但只要同步相足够大,最终可实现系统的完全同步。从理论上讨论了同步条件,并在数值实验上讨论了同步相与耦合强度的关系。     

Controlling chaos by periodic proportional pulses

It is shown that proportional pulses, X_i → kX_i, applied once every p iterations to chaotic dynamics, X_n+1 = f(X_n), may stabilize the dynamics at a periodic orbit. We give here an explicit procedure to find all such periodic points X_i, and to calculate the corresponding constants p and k.     

Sound attenuation by multiple barriers

A method (tentatively called ‘the method of equivalent sound source’) of predicting the sound attenuation achieved by multiple barriers with knife edges and/or right-angled wedges is proposed. This paper shows that the sound pressure level in the shadow region behind the multiple barriers can be obtained by successively setting imaginary sound sources for respective edges and/or wedges. The locations of the imaginary sound sources are determined by means of the traditional solution for sound attenuation by a single edge. The calculated results for several kinds of small-scale model, obtained by ‘the method of equivalent sound source’, are compared with experimental results.     

Channeling and the periodic Lorentz gas

Properties of the periodic Lorentz gas, which describes particle motion in a lattice of hard spheres, are related to experiments on channeling in crystals. Extensive theoretical knowledge of the Lorentz gas can be applied to make predictions about diffusion and radiation in channeling experiments.     

Channeling of fast particles in fullerites

A theory of channeling of relativistic electrons and positrons as well as positively and negatively charged ions in molecular crystals of fullerenes (fullerites) is developed. The crystal potentials are calculated, and the spatial and angular distributions of beams of particles propagating along principal crystallographic directions are determined. A method is developed for taking into account the effect of incoherent scattering on the channeling process.     

利用速度反馈方法控制时空混沌

以空间一维的复Ginzburg-Landau方程为模型,研究了利用系统变量随时间的变化率作为反馈控制信号控制偏微分方程系统中时空混沌的可能性.通过理论分析和数值模拟方法讨论了控制参数与可控性所满足的关系,解释了不同目标态时临界控制参数的尺寸效应. 关键词： 混沌控制 时空混沌 速度反馈 复Ginzburg-Landau方程     

Continuous control of chaos by self-controlling feedback

Two methods of chaos control with a small time continuous perturbation are proposed. The stabilization of unstable periodic orbits of a chaotic system is achieved either by combined feedback with the use of a specially designed external oscillator, or by delayed self-controlling feedback without using of any external force. Both methods do not require an a priori analytical knowledge of the system dynamics and are applicable to experiment. The delayed feedback control does not require any computer analyses of the system and can be particularly convenient for an experimental application.     

Slow Ion Channeling in Monocrystalline Silicon

Physics of the Solid State - The profiles of the distribution of Si+ ions over the depth of single-crystal silicon were calculated by the molecular dynamics method. The inelastic energy losses...     

Channeling in single-wall nanotubes: Possible applications

The relevant potentials are calculated and used to investigate the trajectories and various characteristics of axial channeling of high-energy positively charged particles in the recently discovered single-wall nanotubes (SWNTs). The application of SWNTs in high-energy physics, specifically, in future colliders, is discussed, in view of the fact that the dechanneling length in SWNTs is much longer than in single crystals. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 304–307 (10 September 1997)