Sökning: "filtered"

Visar resultat 1 - 5 av 197 avhandlingar innehållade ordet filtered.

  1. 1. Iterative Filtered Backprojection Methods for Helical Cone-Beam CT

    Författare :Johan Sunnegårdh; Michael Felsberg; Michel Defrise; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Iterative reconstruction; filtered backprojection; regularization; cone-beam CT; Medical engineering; Medicinsk teknik;

    Sammanfattning : State-of-the-art reconstruction algorithms for medical helical cone-beam Computed Tomography (CT) are of type non-exact Filtered Backprojection (FBP). They are attractive because of their simplicity and low computational cost, but they produce sub-optimal images with respect to artifacts, resolution, and noise. LÄS MER

  3. 2. Cone-Beam Reconstruction Using Filtered Backprojection

    Författare :Henrik Turbell; Per-Erik Danielsson; Michel Defrise; Linköpings universitet; []
    Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : The art of medical computed tomography is constantly evolving and the last years have seen new ground breaking systems with multi-row detectors. These tomographs are able to increase both scanning speed and image quality compared to the single-row systems more commonly found in hospitals today. LÄS MER

  4. 3. The Diamond Lemma for Power Series Algebras

    Författare :Lars Hellström; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mathematical analysis; diamond lemma; power series algebra; Gröbner basis; embedding into skew fields; archimedean element in semigroup; q-deformed Heisenberg--Weyl algebra; polynomial degree; ring norm; Birkhoff orthogonality; filtered structure; Matematisk analys; Mathematical analysis; Analys; Mathematics; matematik;

    Sammanfattning : The main result in this thesis is the generalisation of Bergman's diamond lemma for ring theory to power series rings. This generalisation makes it possible to treat problems in which there arise infinite descending chains. LÄS MER

  5. 4. Active Control of Propeller-Induced Noise in Aircraft : Algorithms & Methods

    Författare :Sven Johansson; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; active control of sound; active noise control; anc; actuator individual normalized filtered-x lms; filtered-x lms algorithm; newton algorithm; complex lms; multireference algorithm; leaky lms; control effort weighting; feedforward control; feedback contro;

    Sammanfattning : In the last decade acoustic noise has become more and more regarded as a problem. In cars, boats, trains and aircraft, low-frequency noise reduces comfort. Lightweight materials and more powerful engines are used in high-speed vehicles, resulting in a general increase in interior noise levels. LÄS MER

  7. 5. Gaussian Random Numbers and Filtered GaussianNoise Wireless Channel models:A Hardware Perspective

    Författare :Jamshaid Malik; Ahmed Hemani; Amir Alimohammad; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : This thesis comprises two distinctive but interrelated parts:1. Gaussian Random Number Generators (GRNGs)Gaussian Distributed Random Numbers (GRNs) are required for simu-lations in a wide variety of applications. LÄS MER