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1.
We analyze the properties of the excited solitary-wave model in the case of anharmonic-interaction of heavy ionic lattice in hydrogen bond systems.in this case,some new phenomena appear,We find different types of solutions for the proton displacement and influences on the kinks and pulse solitary waves by numerical calculation.For each of them we have presented a direct relation with the effective potential of the system.  相似文献   

2.
We discuss the twistor correspondence between path geometries in three dimensions with vanishing Wilczynski invariants and anti-self-dual conformal structures of signature (2, 2). We show how to reconstruct a system of ODEs with vanishing invariants for a given conformal structure, highlighting the Ricci-flat case in particular. Using this framework, we give a new derivation of the Wilczynski invariants for a system of ODEs whose solution space is endowed with a conformal structure. We explain how to reconstruct the conformal structure directly from the integral curves, and present new examples of systems of ODEs with point symmetry algebra of dimension four and greater which give rise to anti–self–dual structures with conformal symmetry algebra of the same dimension. Some of these examples are (2, 2) analogues of plane wave space–times in General Relativity. Finally we discuss a variational principle for twistor curves arising from the Finsler structures with scalar flag curvature.  相似文献   

3.
A number of experimental small-angle scattering (SAS) data are characterized by a succession of power-law decays with arbitrarily decreasing values of scattering exponents. To describe such data, here we develop a new theoretical model based on 3D fat fractals (sets with fractal structure, but nonzero volume) and show how one can extract structural information about the underlying fractal structure. We calculate analytically the monodisperse and polydisperse SAS intensity (fractal form factor and structure factor) of a newly introduced model of fat fractals and study its properties in momentum space. The system is a 3D deterministic mass fractal built on an extension of the well-known Cantor fractal. The model allows us to explain a succession of power-law decays and respectively, of generalized power-law decays (GPLD; superposition of maxima and minima on a power-law decay) with arbitrarily decreasing scattering exponents in the range from zero to three. We show that within the model, the present analysis allows us to obtain the edges of all the fractal regions in the momentum space, the number of fractal iteration and the fractal dimensions and scaling factors at each structural level in the fractal. We applied our model to calculate an analytical expression for the radius of gyration of the fractal. The obtained quantities characterizing the fat fractal are correlated to variation of scaling factor with the iteration number.  相似文献   

4.
Exact Periodic Solitary-Wave Solution for KdV Equation   总被引:1,自引:0,他引:1       下载免费PDF全文
A new technique, the extended homoclinic test technique, is proposed to seek periodic solitary wave solutions of integrable systems. Exact periodic solitary-wave solutions for classical KdV equation are obtained using this technique. This result shows that it is entirely possible for the (l + l)-dimensional integrable equation that there exists a periodic solitary-wave.  相似文献   

5.
The intensity profile of small-angle neutron sc attering from three-dimensional triadic Cantor and Vicsek fractals is calculated when the fractal sets are monodisperse and their positions are uncorrelated. It is shown that the scattering intensities present minima and maxima superimposed on a power-law decay with the exponent coinciding with the fractal dimension of the scatterer. This is in accordance with the scattering from similar systems like Menger sponge or fractal jacks, which all exhibit the same behavior. For a finite iteration, the Porod power decay of the intensity is displayed at large values of momenta beyond the fractal region.  相似文献   

6.
We present a novel method for the calculation of the fractal dimension of boundaries in dynamical systems, which is in many cases many orders of magnitude more efficient than the uncertainty method. We call it the output function evaluation (OFE) method. We show analytically that the OFE method is much more efficient than the uncertainty method for boundaries with D<0.5, where D is the dimension of the intersection of the boundary with a one-dimensional manifold. We apply the OFE method to a scattering system, and compare it to the uncertainty method. We use the OFE method to study the behavior of the fractal dimension as the system's dynamics undergoes a topological transition.  相似文献   

7.
P Singha Deo  A M Jayannavar 《Pramana》2001,56(2-3):439-452
Mesoscopic systems have provided an opportunity to study quantum effects beyond the atomic realm. In these systems quantum coherence prevails over the entire sample. We discuss several novel effects related to persistent currents in open systems which do not have analogues in closed systems. Some phenomena arising simultaneously due to two non-classical effects namely, Aharonov-Bohm effect and quantum tunneling are presented. Simple analysis of sharp phase jumps observed in double-slit Aharonov-Bohm experiments is given. Some consequences of parity violation are elaborated. Finally, we briefly describe the dephasing of Aharonov-Bohm oscillations in Aharonov-Bohm ring geometry due to spin-flip scattering in one of the arms. Several experimental manifestations of these phenomena and their applications are given.  相似文献   

8.
V. A. Sotskov 《Technical Physics》2013,58(10):1476-1480
The dependence of the permittivities of a number of model systems on the bulk resistivity is studied experimentally. The effect of fractal polarization is considered on the basis of analysis of experimental data. A qualitative model of relaxation phenomena is proposed for a new type of surface polarization that can be treated as a logical continuation of the Maxwell-Wagner polarization to conducting filters.  相似文献   

9.
We show that noise enhances the trapping of trajectories in scattering systems. In fully chaotic systems, the decay rate can decrease with increasing noise due to a generic mismatch between the noiseless escape rate and the value predicted by the Liouville measure of the exit set. In Hamiltonian systems with mixed phase space we show that noise leads to a slower algebraic decay due to trajectories performing a random walk inside Kolmogorov-Arnold-Moser islands. We argue that these noise-enhanced trapping mechanisms exist in most scattering systems and are likely to be dominant for small noise intensities, which is confirmed through a detailed investigation in the Hénon map. Our results can be tested in fluid experiments, affect the fractal Weyl's law of quantum systems, and modify the estimations of chemical reaction rates based on phase-space transition state theory.  相似文献   

10.
R NAZ  F M MAHOMED 《Pramana》2014,83(1):9-20
The Lie and Noether point symmetry analyses of a kth-order system of m complex ordinary differential equations (ODEs) with m dependent variables are performed. The decomposition of complex symmetries of the given system of complex ODEs yields Lie- and Noether-like operators. The system of complex ODEs can be split into 2m coupled real partial differential equations (PDEs) and 2m Cauchy–Riemann (CR) equations. The classical approach is invoked to compute the symmetries of the 4m real PDEs and these are compared with the decomposed Lie- and Noether-like operators of the system of complex ODEs. It is shown that, in general, the Lie- and Noether-like operators of the system of complex ODEs and the symmetries of the decomposed system of real PDEs are not the same. A similar analysis is carried out for restricted systems of complex ODEs that split into 2m coupled real ODEs. We summarize our findings on restricted complex ODEs in two propositions.  相似文献   

11.
The diffusive motion of Brownian particles near irregular interfaces plays a crucial role in various transport phenomena in nature and industry. Most diffusion-reaction processes in confining interfacial systems involve a sequence of Brownian flights in the bulk, connecting successive hits with the interface (Brownian bridges). The statistics of times and displacements separating two interface encounters are then determinant in the overall transport. We present a theoretical and numerical analysis of this complex first-passage problem. We show that the bridge statistics is directly related to the Minkowski content of the surface within the usual diffusion length. In the case of self-similar or self-affine interfaces, we show and check numerically that the bridge statistics follows power laws with exponents depending directly on the surface fractal dimension.  相似文献   

12.
Resonance processes are common phenomena in multiscale (slow-fast) systems. In the present paper we consider capture into resonance and scattering on resonance in 3D volume-preserving multiscale systems. We propose a general theory of those processes and apply it to a class of kinematic models inspired by viscous Taylor-Couette flows between two counter-rotating cylinders. We describe the phenomena during a single passage through resonance and show that multiple passages lead to the chaotic advection and mixing. We calculate the width of the mixing domain and estimate a characteristic time of mixing. We show that the resultant mixing can be described using a diffusion equation with a diffusion coefficient depending on the averaged effect of the passages through resonances.  相似文献   

13.
Considering that the motions of the particles take place on continuous but non-differentiable curves, i.e. on fractals with constant fractal dimension, an extended scale relativity model in its hydrodynamic version is built. In this approach, static (particle in a box and harmonic oscillator) and time-dependent (free particle etc.) systems are analyzed. The static systems can be associated with a coherent fractal fluid (of superconductor or of super-fluid types behavior), whose particles are moving on stationary trajectories. The complex speed field of the fractal fluid proves to be essential: the zero value of the real (differentiable) part specifies the coherence of the fractal fluid, while the non-zero value of the imaginary (non-differentiable or fractal) part selects, through some “quantization” relations, the “stationary” trajectories (that may correspond to the observables from quantum mechanics) of the fractal fluid particles. Moreover, the momentum transfer in the fractal fluid is achieved only through the fractal component of the complex speed field. The free time-dependent systems can be associated with an incoherent fractal fluid, and both the differentiable and fractal components of complex speed field are inhomogeneous in fractal coordinates due to the action of a fractal potential. It exist momentum transfer on both speed components and the “observable” in the form of an uniform motion is generated through a specific mechanism of “vacuum” polarization induced by the same fractal potential. The analysis on the fractal fluid specifies conductive properties in the case of movements synchronization both on differentiable and fractal scales, and convective properties in the absence of synchronization.  相似文献   

14.
张春平  于风崎  张光寅 《物理学报》1989,38(7):1339-1343
本文初步讨论了不同体系中的分形体的生长规律,通过对不同分形体体系透射光谱的分析,发现透射光谱中新吸收带的位置与时间对数关系曲线大致由两条直线组成,这说明分形体的主要生长过程按速度大致可分为两个阶段。 关键词:  相似文献   

15.
金属离子对银溶胶的聚集作用及形成的分数维结构   总被引:1,自引:0,他引:1       下载免费PDF全文
于风崎  张春平  张光寅 《物理学报》1987,36(10):1289-1304
本文研究了一些离子作用于银溶胶而引起聚集的情况。一价金属离子对银溶胶的聚集作用不明显,第Ⅱ主族的金属离子能够引起银溶胶的聚集而形成分形体(Fractal)态,且随着金属离子半径的增大,其聚集能力增强,对于三价金属离子Al3+,它也能引起银溶胶的聚集而形成分形体态。酸根阴离子一般不直接引起银溶胶的聚集,但能影响银溶胶的聚集。 关键词:  相似文献   

16.
张春平  于凤崎 《物理学报》1989,38(8):1334-1338
本文初步讨论了不同体系中的分形体的生长规律, 通过对不同分形体体系透射光谱的分析, 发现透射光谱中新吸收带的位置与时间对数关系曲线大致由两条直线组成, 这说明分形体的主要生长过程按速度大致可分为两个阶段。 关键词:  相似文献   

17.
Invariant linearization criteria for square systems of second-order quadratically nonlinear ordinary differential equations (ODEs) that can be represented as geodesic equations are extended to square systems of ODEs cubically nonlinear in the first derivatives. It is shown that there are two branches for the linearization problem via point transformations for an arbitrary system of second-order ODEs and its reduction to the simplest system. One is when the system is at most cubic in the first derivatives. One obtains the equivalent of the Lie conditions for such systems. We explicitly solve this branch of the linearization problem by point transformations in the case of a square system of two second-order ODEs. Necessary and sufficient conditions for linearization to the simplest system by means of point transformations are given in terms of coefficient functions of the system of two second-order ODEs cubically nonlinear in the first derivatives. A consequence of our geometric approach of projection is a rederivation of Lie's linearization conditions for a single second-order ODE and sheds light on more recent results for them. In particular we show here how one can construct point transformations for reduction to the simplest linear equation by going to the higher space and just utilizing the coefficients of the original ODE. We also obtain invariant criteria for the reduction of a linear square system to the simplest system. Moreover these results contain the quadratic case as a special case. Examples are given to illustrate our results.  相似文献   

18.
We describe a method for determining the approximate fractal dimension of an attractor. Our technique fits linear subspaces of appropriate dimension to sets of points on the attractor. The deviation between points on the attractor and this local linear subspace is analyzed through standard multilinear regression techniques. We show how the local dimension of attractors underlying physical phenomena can be measured even when only a single time-varying quantity is available for analysis. These methods are applied to several dissipative dynamical systems.  相似文献   

19.
刘伟  郭立新  吴振森 《中国物理 B》2010,19(7):74102-074102
This paper studies the influence of wind parameters and fractal dimension from an improved two-dimensional sea fractal surface on the polarimetric scattering by using facet integration.A two-dimensional improved sea surface simulated is discretized into three matrices of sea surface facets including a height matrix and two slope matrices on orthogonal directions.Based on the Kirchhoff approximation,the polarimetric scattered field is derived in the Cartesian coordinate system by integration of three matrices mentioned above.Finally,the fully polarised radar cross section is numerically simulated and the dependence of the polarimetric scattering on the sea fractal surface,such as the wind speed,the wind direction,as well as the fractal dimension,is discussed in detail.  相似文献   

20.
We have investigated fractal growth phenomena in three binary metal systems; the Sc-Co, Sc-Cr and Sc-Ni systems. For the Sc-Co and Sc-Cr systems, we describe the observed evolution process of the fractals based on the deposition–diffusion–aggregation model and find that the magnetic interaction can play an important role in influencing the fractal dimension, i.e. the stronger the magnetic moment of the aggregating particles, the smaller the dimension of the resultant fractal. Comparing the observations in the three systems studied, it was found that the chemical interaction between two dissimilar atoms might prevent the formation of the fractal pattern during deposition, for example in the Ni-Sc system . PACS 61.43. Hv; 68.55. -a; 66.30. Ny; 75.50. -y  相似文献   

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