Sökning: "diffusion approximation"

Visar resultat 1 - 5 av 21 uppsatser innehållade orden diffusion approximation.

  1. 1. Estimating Diffusion Tensor Distributions With Neural Networks

    Master-uppsats, Linköpings universitet/Algebra, geometri och diskret matematik; Linköpings universitet/Tekniska fakulteten

    Författare :Rimaz Nismi; [2024]
    Nyckelord :Diffusion; Magnetic Resonance Imaging; MRI; Neural Networks; Optimal transport; Earth mover s distance; Sinkhorn distance;

    Sammanfattning : Magnetic Resonance Imaging (MRI) is an essential healthcare technology, with diffusion MRI being a specialized technique. Diffusion MRI exploits the inherent diffusion of water molecules within the human body to produce a high-resolution tissue image. An MRI image contains information about a 3D volume in space, composed of 3D units called voxels. LÄS MER

  3. 2. Solving the incompressible Navier-Stokes equations in 3-D to model gas flow in a room

    Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Avdelningen för beräkningsvetenskap

    Författare :Fredrik Malmström; [2024]
    Nyckelord :;

    Sammanfattning : The thesis proposes to model the flow of gases in a room by solving the incompressible Navier-Stokes equations in three dimensions. The transportationof scalars such as temperature and concentration of CO2 is modeled by solving the advection-diffusion equation, and the effects of temperature on thevelocity is accounted for by employing the Boussinesq approximation. LÄS MER

  4. 3. Filtering aspects

    Kandidat-uppsats, KTH/Skolan för teknikvetenskap (SCI)

    Författare :Johannes Pape; [2023]
    Nyckelord :;

    Sammanfattning : In this report, a Fourier spectral approximation of the solution to the linear convection--diffusion equation for initial conditions of different smoothness, and for Burger's equation for the initial condition f(x) = sin(x), was constructed, and implemented. Three different filters (Cesàro, Lanczos, and 4--th order exponential cutoff) were either applied to the initial condition or to the numerical approximation after the last integration step has been performed. LÄS MER

  5. 4. Approximating Quasistationary Distributions Using Deep Learning

    Master-uppsats, KTH/Matematisk statistik

    Författare :Björn Wehlin; [2022]
    Nyckelord :Applied Mathematics; Deep Learning; Probability Theory; Stochastic Processes; Ito Diffusions; Quasistationary Distributions; Tillämpad matematik; djupinlärning; sannolikhetsteori; stokastiska processer; Ito-diffusioner; kvasistationära fördelningar;

    Sammanfattning : We study a class of It\={o} diffusion processes on domains with smooth boundary, at which the process is killed. Such a process, when conditioned on non-extinction, gives rise to a stationary state known as a \emph{quasistationary distribution} (QSD). LÄS MER

  7. 5. Squaring VEGAS -- Multidimensional Integration Using 2D Correlations

    Kandidat-uppsats, Lunds universitet/Teoretisk partikelfysik - Geonomgår omorganisation

    Författare :Philip Siemund; [2021]
    Nyckelord :statistics; numerical integration; Monte Carlo integration; VEGAS; Physics and Astronomy;

    Sammanfattning : Multidimensional integrals are used in many areas of physics; electrodynamics, quantum mechanics and statistical physics, to name a few. Many integrals can not be solved analytically, but can instead be approximated numerically. VEGAS is a Monte Carlo integration algorithm, which specializes it in approximating multidimensional integrals. LÄS MER