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Direct and inverse scattering in the time domain for a dissipative wave equation. Part 1: Scattering operators

This is the first part of a series of papers devoted to direct and inverse scattering of transient waves in lossy inhomogeneous media. The medium is assumed to be stratified, i.e., it varies only with depth. The wave propagation is modeled in an electromagnetic case with spatially varying permittivity and conductivity. The objective in this first paper is to analyze properties of the scattering op

Dynamical effects in X-ray spectra and the final-state rule

The dynamical theory of X-ray spectra due to Nozieres and De Dominicis (ND, 1969) is evaluated here numerically for numerous model systems including cases where the core-hole potential possesses a bound state. It is shown that the resulting emission spectra obey the final-state rule rather accurately. An approximate but analytical derivation of this rule is given which provides insight into the me

Light Propagation and Gas Absorption Studies in Turbid Media Using Tunable Diode Llaser Techniques

Optical absorption spectroscopy is a widely used analytical tool for constituent analysis in many applications. According to the Beer-Lambert law, the transmitted light intensity through a homogeneous medium is an exponential function of the product of the concentration, the total pathlength, and the absorption cross-section of the absorbing substance. By studying the intensity loss at the unique

Finite codimensional invariant subspaces in Hilbert spaces of analytic functions

Let $\scr H$ denote a Hilbert space consisting of functions analytic on a bounded, open, connected subset $\Omega$ of the complex plane. Given certain natural hypotheses on $\scr H$, the author characterizes the finite-codimensional subspaces of $\scr H$ that are invariant under multiplication by $z$, showing that all such subspaces have the form $(p\scr H)^-$, where $p$ is a polynomial whose zero

Development of an Automatic Reduction Tool for Chemical Mechanisms and an Optimized Sparse Matrix Solver for Systems of Differential and Algebraic Equations

Abstract An N-Heptane mechanism and a Methane/Propane mechanism have been reduced by an Automatic Reduction Tool (ART) and simulated with two different solver combinations, which solve the set of ordinary differential equations governing the time evolution of the species simultaneously with solving algebraic equations for species that can be considered to be in quasi steady state. The most succes

Development and Application of Non-linear Mid-infrared Laser Spectroscopy for Combustion Diagnostics

Popular Abstract in Swedish Denna avhandlings inriktar sig i huvudsak mot utveckling och tillämpning av två nyligen framtagna optiska tekniker för förbränningsstudier. Dessa tekniker kallas mid-infrared polarisationsspektroskopi (IRPS) samt degenererad fyrvågsmixning (IR-DFWM), vilka båda är baserade på infrarött ljus med en våglängd runt 3 mikrometer, samt att teknikernas signalrespons är ickelinThe work reported in this thesis involved the development and application of two novel infrared non-linear laser techniques, namely mid-infrared polarization spectroscopy (IRPS) and mid-infrared degenerate four-wave mixing (IR-DFWM) to combustion diagnostics. These two techniques meet the needs of species concentration detection in combustion environments, especially for those species lacking acce

Canopy storage capacity of xerophytic shrubs in northwestern China

Abstract in UndeterminedThe capacity of shrub canopy water storage is a key factor in controlling the rainfall interception. Thus, it affects a variety of hydrological processes in water-limited arid desert ecosystems. Vast areas of revegetated desert ecosystems in Northwestern China are occupied by shrub and dwarf shrub communities. Yet, data are still scarce regarding their rainwater storage cap

On-off Control of an Active Load for Power System Damping-Theory and Field Test

Controlled resistive loads can contribute to damping of electro-mechanical oscillations. This paper presents an on-off damping controller for a single machine system. It was used at a field test in southern Sweden to damp oscillations of a 0.9 MW hydro power generator. The controller used estimated machine frequency as input and controlled a 20 kW resistive load via thyristor switches. The field m