摘要:

This paper is a theoretical study of nonlinear wave propagation in homogeneous and stratified shear flows. For a wave packet, it is known that levels where the flow velocity is equal to the phase or group velocity are regions where nonlinear effects are especially significant. In this study certain aspects of the flow configuration are examined in the neighborhood of each of these regions.

ISSN:0022-2526    

DOI:10.1002/sapm1983693177

年代:1983

数据来源: WILEY

摘要:

The time dependent expectation value of a magnetic perturbation of theXY‐Hamiltonian is computed exactly. Thermalization information is obtaine

ISSN:0022-2526    

DOI:10.1002/sapm1983693201

年代:1983

数据来源: WILEY

摘要:

The Kadomtsev‐Petviashvili equation, a two‐spatial‐dimensional analogue of the Korteweg‐deVries equation, arises in physical situations in two different forms depending on a certain sign appearing in the evolution equation. Here we investigate one of the two cases. The initial‐value problem, associated with initial data decaying sufficiently rapidly at infinity, is linearized by a suitable extension of the inverse scattering transform. Essential is the formulation of a nonlocal Riemann‐Hilbert problem in terms of scattering data expressible in closed form in terms of given initial data. The lump solutions, algebraically decaying solitons, are given a definite spectral characterization. Pure lump solutions are obtained by solving a linear algebraic system whose coefficients depend linearly onx, y, t. Many of the above results are also relevant to the problem of inverse scattering for the so‐called time‐dependent Schr

ISSN:0022-2526    

DOI:10.1002/sapm1983693211

年代:1983

数据来源: WILEY

摘要:

Collapse of solutions of then‐dimensional nonlinear Schrödinger equation are studied using the integrals of the motion and an equation corresponding to the Lagrange‐Jacobi virial equation of classical mechanics. There are strong parallels with collapse in the classicalN‐body problem and in particular with the results of K. F. Sundman. Collapse occurs when the amplitude of the solution becomes singular as the initial data collapse to the center of mass in finite time. In some cases the singularity is inevitable (for negative energy), but in others only a necessary condition for collapse can be derived, involving the angular mo

ISSN:0022-2526    

DOI:10.1002/sapm1983693229

年代:1983

数据来源: WILEY

ISSN:0022-2526    

DOI:10.1002/sapm1983693265

年代:1983

数据来源: WILEY

ISSN:0022-2526    

DOI:10.1002/sapm1983693267

年代:1983

数据来源: WILEY