Sökning: "On surface radiation condition"

Visar resultat 1 - 5 av 20 avhandlingar innehållade orden On surface radiation condition.

1. 1. 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. 2. Potential Flow Panel Methods for the Calculation of Free-surface Flows with Lift

   Författare :Carl-Erik Janson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; desingularized; shape optimization; Rankine source; waves; OCTOPUS; dipole; MMA; Dawson operator; boundary layer; vortex; Method of Moving Asymptotes; nonlinear; sailing yacht; four point operator; surface piercing wing; Navier-Stokes; numerical method; lift force; raised panel method; discrete Fourier transform; collocation point shift; potential flow; CFD; free surface; induced drag; SHIPFLOW; dispersion; damping; analytical method; hydrofoil;

   Sammanfattning : Two non-linear Rankine-source panel methods are developed and implemented in the same computer code. The first method uses a four-point upwind operator on the free-surface to compute the velocity derivatives and to enforce the radiation condition while the second method uses an analytical expression for the velocity derivatives and a collocation point shift one panel upstream to prevent upstream waves. LÄS MER

4. 3. Long-term performance of polymeric materials in nuclear power plants

   Författare :Payam Pourmand; Ulf W. Gedde; Sue Burnay; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; EPDM; thermal ageing; radiation ageing; portable NMR spectroscopy; modulus profiling; condition monitoring; plasticizer migration; Kemi; Chemistry;

   Sammanfattning : Access to energy is crucial for modern societies to function sustainably. In addition, nuclear power has for a long time been considered a reliable source of energy. However, the majority of nuclear power plants are reaching the end of their service lifetimes, and it is crucial to verify that every component can withstand the added service time. LÄS MER

5. 4. Boreal land surface water and heat balance : Modelling soil-snow-vegetation-atmosphere behaviour

   Författare :David Gustafsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; soil; snow; land surface heat exchange; forest; arable land; eddy-correlation; Civil engineering and architecture; Samhällsbyggnadsteknik och arkitektur;

   Sammanfattning : The water and heat exchange in thesoil-snow-vegetation-atmosphere system was studied in order toimprove the quantitative knowledge of land surface processes.In this study, numerical simulation models and availabledatasets representing arable land, sub-alpine snowpack, andboreal forest were evaluated at both diurnal and seasonaltimescales. LÄS MER

7. 5. Phenomena in laser based material deposition

   Författare :Himani Naesstroem; Frank Brückner; Alexander Kaplan; Prashanth Konda Gokuldoss; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Produktionsutveckling; Manufacturing Systems Engineering;

   Sammanfattning : This thesis is regarding the use of a laser beam to deposit material. Phenomena in two processes, laser beam welding with filler wire and blown powder directed energy deposition (DED) also known as laser metal deposition (LMD)1, are discussed. LÄS MER