background : myocardial infarction in young age is increasing. identifying risk factors could be important for health promotion. we studied classic atherosclerotic risk factors in premature myocardial infarction. methods : in this matched case-control study, which was conducted from 2005 to 2007 in birjand county, the east of iran, atherosclerotic risk factors ( hypertension , family history of...

After introducing the Discontinuous Galerkin (DG) method a detailed misfit analysis on its numerical approximation is performed. We investigate the accuracy of the scheme, the element type (tetrahedrons and hexahedrons), the spatial sampling of the computational domain and the number of propagated wavelengths. As the error norm we chose a time-frequency representation, which illustrates the tim...

An improved technique for matching the asymptotic solutions of non-linear differential equations is presented and successfully applied to the three-dimensional atmospheric skip trajectories. The classical method of matched asymptotic expansions (MAE) is generally applied to two-point-boundary value problems. When we apply the MAE method to initial value problems, due to error propagation, the r...

Article history: Received 26 January 2009 Available online 17 July 2009 Submitted by P. Broadbridge

Abstract. In this paper, we propose a uniaxial perfectly matched layer (PML) method for solving the time-harmonic scattering problems in layered media. The exterior region of the scatterer is divided into two half spaces by an infinite plane, on two sides of which the wave number takes different values. We surround the computational domain where the scattering field is interested by a PML layer...

This note is intended as a brief introduction to the theory and practice of per­ fectly matched layer (PML) absorbing boundaries for wave equations, intended for future use in the courses 18.369 and 18.336 at MIT. It focuses on the complex stretched-coordinate viewpoint, and also discusses the limitations of PML.