In this article we investigate analytically and numerically a class of non-autonomous Schrödinger equations in one space dimension describing the dynamics of quantum anharmonic oscillators driven by timedependent quartic interactions. We do so within a suitably constructed Faedo-Galerkin scheme by analyzing several product approximations for their solutions, which involve various exponential op...

By posing and solving a global axisymmetric eigenvalue problem on an infinite domain with modes vanishing at zero and infinity for a differentially rotatingMHD plasma, the conditions for the occurrence of a purely growing lowfrequency mode known as the magnetorotational instability (MRI) are mapped. It is shown that the MRI criterion drawn from the ‘‘local dispersion relation’’ is at best inade...

A method is presented for decomposing wave motion into its principle components. The basic idea is a complex generalization of proper orthogonal decomposition. The method involves the representation of real oscillatory signals as complex analytic signals. The relationship between complex modes and wave motion is explored. From an ensemble of complex signals, a complex correlation matrix is form...

This paper presents eigensolution and non-modal analyses for immersed boundary methods (IBMs) based on volume penalization the linear advection equation. approach is used to analyze behavior of flux reconstruction (FR) discretization, including influence polynomial order parameter numerical errors stability. Through a semi-discrete analysis, we find that inclusion IBM adds additional dissipatio...

this paper consists of three sections. in the first section an efficient method is used for decomposition of the canonical matrices associated with repetitive structures. to this end, cylindrical coordinate system, as well as a special numbering scheme were employed. in the second section, divide and conquer method have been used for eigensolution of these structures, where the matrices are in ...

This article develops a simple linear model for the motion of a Stewart platform in a stationary position. That is, the situation where the platform is at rest and is then subject to an impulsive disturbance. The hydraulic actuators are modelled as simple spring-dashpot systems and the stiffness and damping matrices of the system are derived. It is found that the damping and stiffness matrices ...

Department of Physics, Southern Methodist University, Dallas, TX 75275 (Dated: September 4, 2002) Abstract We obtain analytic, nonperturbative, approximate solutions of Yukawa theory in the one-fermion sector using light-front quantization. The theory is regulated in the ultraviolet by the introduction of heavy Pauli–Villars scalar and fermion fields, each with negative norm. In order to obtain...

The Rational Krylov algorithm computes eigenvalues and eigenvectors of a regular not necessarily symmetric matrix pencil. It is a generalization of the shifted and inverted Arnoldi algorithm, where several factorizations with di erent shifts are used in one run. It computes an orthogonal basis and a small Hessenberg pencil. The eigensolution of the Hessenberg pencil approximates the solution of...

We consider the interaction of free-stream disturbances with the leading edge of a body and its effect on the transition point. We present a method which combines an asymptotic receptivity approach, and a numerical method which marches through the Orr-Sommerfeld region. The asymptotic receptivity analysis produces a three deck eigensolution which in its far downstream limiting form, produces an...

This paper consists of three sections. In the first section an efficient method is used for decomposition of the canonical matrices associated with repetitive structures. to this end, cylindrical coordinate system, as well as a special numbering scheme were employed. In the second section, divide and conquer method have been used for eigensolution of these structures, where the matrices are in ...