Search for dissertations about: "high frequency waves"

Showing result 1 - 5 of 182 swedish dissertations containing the words high frequency waves.

2. 1. Steady waves in local and nonlocal models for water waves

   Author : Tien Truong; Matematik (naturvetenskapliga fakulteten); []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics; The steady Euler equations; the Whitham equation; solitary waves; highest waves; periodic waves; transverse dynamics;

   Abstract : We study the steady Euler equations for inviscid, incompressible, and irrotational water waves of constant density. The thesis consists of three papers. The first paper approaches the Euler equations through a famous nonlocal model equation for gravity waves, namely the Whitham equation. READ MORE

4. 2. Uncertainty quantification for high frequency waves

   Author : Gabriela Malenova; Olof Runborg; Daniel Appelö; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : We consider high frequency waves satisfying the scalar wave equationwith highly oscillatory initial data. The speed of propagation of the mediumas well as the phase and amplitude of the initial data is assumed to beuncertain, described by a finite number of independent random variables withknown probability distributions. READ MORE

5. 3. Uncertainty quantification for high frequency waves

   Author : Gabriela Malenova; Olof Runborg; Fabio Nobile; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik;

   Abstract : We consider high frequency waves satisfying the scalar wave equation with highly oscillatory initial data represented by a short wavelength ε. The speed of propagation of the medium as well as the phase and amplitude of the initial data is assumed to be uncertain, described by a finite number of independent random variables with known probability distributions. READ MORE

6. 4. Fast Adaptive Numerical Methods for High Frequency Waves and Interface Tracking

   Author : Jelena Popovic; Olof Runborg; Hongkai Zhao; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; high frequency waves; Helmholtz equation; interface tracking; time-space adaptivity; multiresolution; Hamilton-Jacobi;

   Abstract : The main focus of this thesis is on fast numerical methods, where adaptivity is an important mechanism to lowering the methods' complexity. The application of the methods are in the areas of wireless communication, antenna design, radar signature computation, noise prediction, medical ultrasonography, crystal growth, flame propagation, wave propagation, seismology, geometrical optics and image processing. READ MORE

7. 5. Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves

   Author : Marcus Engholm; Tadeusz Stepinski; Paul D. Wilcox; Uppsala universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; imaging; array processing; guided waves; Lamb waves; dispersive waves; multi-modal waves; spatial filtering; mode suppression; resonant ultrasound; transducer design; direction of arrival estimation; adaptive beamforming; Signal processing; Signalbehandling; Electronic measurement and instrumentation; Elektronisk mät- och apparatteknik;

   Abstract : Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures. READ MORE