Sökning: "High frequency approximations"

Visar resultat 6 - 10 av 36 avhandlingar innehållade orden High frequency approximations.

1. 6. Approximations of Integral Equations for WaveScattering

   Författare :Andreas Atle; Björn Engquist; Richard Tsai; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Integral equations; Marching on in time; On surface radiation condition; Physical Optics; Numerical analysis; Numerisk analys;

   Sammanfattning : Wave scattering is the phenomenon in which a wave field interacts with physical objects. An incoming wave is scattered at the surface of the object and a scattered wave is produced. Common practical cases are acoustic, electromagnetic and elastic wave scattering. LÄS MER

3. 7. Perfectly Matched Layers and High Order Difference Methods for Wave Equations

   Författare :Kenneth Duru; Gunilla Kreiss; Jan Nordsröm; Ken Mattsson; Marcus Grote; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Elastic waves; Surface waves; Perfectly matched layers; High order difference methods; Stability; Summation-by-parts operators; Boundary treatments; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Sammanfattning : The perfectly matched layer (PML) is a novel technique to simulate the absorption of waves in unbounded domains. The underlying equations are often a system of second order hyperbolic partial differential equations. In the numerical treatment, second order systems are often rewritten and solved as first order systems. LÄS MER

4. 8. Liquidity and Portfolio Optimisation

   Författare :Björn Hagströmer; Jane M. Binner; Aston University Aston Business School; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; stock market; liquidity; systematic liquidity; portfolio optimisation; high-frequency data; Economics; Nationalekonomi;

   Sammanfattning : This thesis presents research within empirical financial economics with focus on liquidity and portfolio optimisation in the stock markets. The discussion on liquidity is focussed on measurement issues, including TAQ data processing and measurement of systematic liquidity factors. LÄS MER

5. 9. Spin Torque Oscillator Modeling, CMOS Design and STO-CMOS Integration

   Författare :Tingsu Chen; Ana Rusu; Atila Alvandpour; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; STO technology; microwave oscillator; analytical model; macrospin approximation; Verilog-A model; high frequency CMOS circuits; balun-LNA; STO-IC integration; Informations- och kommunikationsteknik; Information and Communication Technology;

   Sammanfattning : Spin torque oscillators (STOs) are microwave oscillators with an attractive blend of features, including a more-than-octave tunability, GHz operating frequencies, nanoscale size, nanosecond switching speed and full compatibility with CMOS technology. Over the past decade, STOs' physical phenomena have been explored to a greater extent, their performance has been further improved, and STOs have already shown great potential for a wide range of applications, from microwave sources and detectors to neuromorphic computing. LÄS MER

7. 10. Numerical approximations of time domain boundary integral equation for wave propagation

   Författare :Andreas Atle; KTH; []
   Nyckelord :MOT; Marching on in time; boundary integral equations;

   Sammanfattning : Boundary integral equation techniques are useful in thenumerical simulation of scattering problems for wave equations.Their advantage over methods based on partial di.erentialequations comes from the lack of phase errors in the wavepropagation and from the fact that only the boundary of thescattering object needs to be discretized. LÄS MER