Sökning: "Fast summation"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden Fast summation.

  1. 1. Inverse Problems in Tomography and Fast Methods for Singular Convolutions

    Författare :Fredrik Andersson; Matematik LTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematics; Matematik; Unequally spaced FFT; Integral transforms; Singular integrals; Lippmann?Schwinger equation; Helmholtz equation; Inverse problems; Fast Gauss transform; Fast summation; Convolution; Radon transform; Tomography;

    Sammanfattning : There are two, partially interlaced, themes treated in this thesis; inverse problems of tomographic type and fast and accurate methods for the application of convolution operators. Regarding the first theme, the inverse problem of Doppler tomography is considered and the Doppler moment transform is introduced for that purpose. LÄS MER

  3. 2. Boundary integral methods for Stokes flow : Quadrature techniques and fast Ewald methods

    Författare :Oana Marin; Anna-Karin Tornberg; Anita Layton; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; boundary integral; Stokes flow; quadrature rule; Ewald decomposition;

    Sammanfattning : Fluid phenomena dominated by viscous effects can, in many cases, be modeled by the Stokes equations. The boundary integral form of the Stokes equations reduces the number of degrees of freedom in a numerical discretization by reformulating the three-dimensional problem to two-dimensional integral equations to be discretized over the boundaries of the domain. LÄS MER

  4. 3. Accurate quadrature and fast summation in boundary integral methods for Stokes flow

    Författare :Joar Bagge; Anna-Karin Tornberg; Katarina Gustavsson; Adrianna Gillman; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

    Sammanfattning : This thesis concerns accurate and efficient numerical methods for the simulation of fluid flow on the microscale, known as Stokes flow or creeping flow. Such flows are important, for example, in understanding the swimming of microorganisms, spreading of dust particles, as well as in developing new nano-materials, and microfluidic devices that can be used for on-the-fly analysis of blood samples, among other things. LÄS MER

  5. 4. Algorithms for Molecular Dynamics Simulations

    Författare :Fredrik Hedman; Aatto Laaksonen; Tom Darden; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; molecular dynamics; MD; first principles molecular dynamics; quantum mechanics; liquid water; parallel algorithm; data parallel; MPI; Coulombic interaction; Ewald summation; nonuniform fast Fourier transform; FFT; FFTW; NFFT; ENUF; Physical chemistry; Fysikalisk kemi;

    Sammanfattning : Methods for performing large-scale parallel Molecular Dynamics(MD) simulations are investigated. A perspective on the field of parallel MD simulations is given. Hardware and software aspects are characterized and the interplay between the two is briefly discussed. LÄS MER

  7. 5. Fast and accurate integral equation methods with applications in microfluidics

    Författare :Ludvig af Klinteberg; Anna-Karin Tornberg; Mary-Catherine Kropinski; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Tillämpad matematik och beräkningsmatematik; Applied and Computational Mathematics;

    Sammanfattning : This thesis is concerned with computational methods for fluid flows on the microscale, also known as microfluidics. This is motivated by current research in biological physics and miniaturization technology, where there is a need to understand complex flows involving microscale structures. Numerical simulations are an important tool for doing this. LÄS MER