A Combined Regular-Logarithmic Perturbation Method for Signal-Noise Interaction in Amplified Optical Systems

Sound Attenuation in Elliptic Mufflers Using a Regular Perturbation Method

The study of sound attenuation in an elliptical chamber involves the solution of the Helmholtz equation in elliptic coordinate systems. The Eigen solutions for such problems involve the Mathieu and the modified Mathieu functions. The computation of such functions poses considerable challenge. An alternative method to solve such problems had been proposed in this paper. The elliptical cross-sect...

A Combined Cascading Subspace and Adaptive Signal Enhancement Method for Stereophonic Noise Reduction

A novel stereophonic noise reduction method is proposed based upon a combination of cascaded subspace filters, with delay and advancing elements alternatively inserted between the adjacent cascading stages, and two-channel adaptive signal enhancers. Simulation results based upon real stereophonic speech contaminated by two correlated noise components show that the proposed method gives improved...

A Robust Method for Sparse Signal Recovery under Multiplicative Perturbation

In this paper, we address the problem of sparse signal reconstruction using compressive sampling (CS) in the presence of unknown multiplicative perturbations. Such perturbations cause mismatch between the true signal basis and that in the measurements. We propose an algorithm which iteratively determines active bases, estimates the mismatch in the identified active bases, and adjusts the CS rec...

A Regular Indirect Boundary Element Method for Thermal Analysis

Logarithmic perturbation theory for quasinormal modes

Logarithmic perturbation theory (LPT) is developed and applied to quasinormal modes (QNMs) in open systems. QNMs often do not form a complete set, so LPT is especially convenient because summation over a complete set of unperturbed states is not required. Attention is paid to potentials with exponential tails, and the example of a Pöschl-Teller potential is briefly discussed. A numerical method...