Search for dissertations about: "discrete fourier"

Showing result 1 - 5 of 36 swedish dissertations containing the words discrete fourier.

  2. 1. Leveraging Intermediate Representations for High-Performance Portable Discrete Fourier Transform Frameworks : with Application to Molecular Dynamics

    Author : Måns Andersson; Stefano Markidis; Artur Podobas; Niclas Jansson; Ivy Bo Peng; Hartwig Anzt; KTH; []
    Keywords : Intermediate Representation; Discrete Fourier Transform; Fast Fourier Transform; Molecular Dynamics; Mellankod; diskret Fouriertransform; snabb Fouriertransform; Molekyldynamik;

    Abstract : The Discrete Fourier Transform (DFT) and its improved formulations, the Fast Fourier Transforms (FFTs), are vital for scientists and engineers in a range of domains from signal processing to the solution of partial differential equations.  A growing trend in Scientific Computing is heterogeneous computing, where accelerators are used instead or together with CPUs. READ MORE

  4. 2. Vector-valued Eisenstein series of congruence types and their products

    Author : Jiacheng Xia; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Hecke operator; Fourier expansion of modular forms; congruence type; products of Eisenstein series; vector-valued modular forms;

    Abstract : Historically, Kohnen and Zagier connected modular forms with period polynomials, and as a consequence of this association concluded that the products of at most two Eisenstein series span all spaces of classical modular forms of level 1. Later Borisov and Gunnells among other authors extended the result to higher levels. READ MORE

  5. 3. Automorphic string amplitudes

    Author : Henrik Gustafsson; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Eisenstein series; string theory; automorphic forms; U-duality; non-perturbative effects; Whittaker vectors; instantons;

    Abstract : This thesis explores the non-perturbative properties of higher derivative interactions appearing in the low-energy expansion of four-graviton scattering amplitudes in toroidal compactifications of type IIB string theory. We summarise the arguments for finding such higher derivative corrections in terms of automorphic forms using U-duality, supersymmetry and string perturbation theory. READ MORE

  6. 4. A neutron noise solver based on a discrete ordinates method

    Author : Huaiqian Yi; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; diffusion synthetic acceleration; nuclear reactor modelling; deterministic neutron transport methods; neutron noise; convergence analysis; discrete ordinates;

    Abstract : A neutron noise transport modelling tool is presented in this thesis. The simulator allows to determine the static solution of a critical system and the neutron noise induced by a prescribed perturbation of the critical system. The simulator is based on the neutron balance equations in the frequency domain and for two-dimensional systems. READ MORE

  7. 5. Optimization of Rotations in FFTs

    Author : Fahad Qureshi; Oscar Gustafsson; Mario Garrido; Jarmo Takala; Linköpings universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Discrete Fourier transform; Fast Fourier transform; twiddle factor multiplication;

    Abstract : The aims of this thesis are to reduce the complexity and increasethe accuracy of rotations carried out inthe fast Fourier transform (FFT) at algorithmic and arithmetic level.In FFT algorithms, rotations appear after every hardware stage, which are alsoreferred to as twiddle factor multiplications. READ MORE