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Visar resultat 6 - 10 av 673 avhandlingar som matchar ovanstående sökkriterier.

  1. 6. Towards a Theory of Codes for Iterative Decoding

    Författare :Michael Lentmaier; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bit error probability; low-density parity-check convolutional code; low-density parity-check code; turbo code; convolutional code; channel coding; iterative decoding; Informatics; systems theory; Informatik; systemteori;

    Sammanfattning : Channel codes in combination with iterative decoding techniques are a both powerful and efficient method to protect data against disturbances in digital communication systems. This thesis deals with various code constructions for block-wise and continuous transmission that have the potential to achieve low bit error rates with iterative decoding, even when operating close to the Shannon limit. LÄS MER

  3. 7. 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

  4. 8. Iterative and Adaptive PDE Solvers for Shared Memory Architectures

    Författare :Henrik Löf; Jarmo Rantakokko; Sverker Holmgren; Erik Hagersten; Mark Bull; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; partial differential equations; iterative methods; finite elements; conjugate gradients; adaptive mesh refinement; multigrid; cc-NUMA; distributed shared memory; OpenMP; page migration; TLB shoot-down; bandwidth minimization; reverse Cuthill-McKee; migrate-on-next-touch; affinity; temporal locality; chip multiprocessors; CMP; Beräkningsvetenskap; Scientific Computing;

    Sammanfattning : Scientific computing is used frequently in an increasing number of disciplines to accelerate scientific discovery. Many such computing problems involve the numerical solution of partial differential equations (PDE). LÄS MER

  5. 9. Iterative decoding of product codes

    Författare :Omar Al-Askary; KTH; []
    Nyckelord :;

    Sammanfattning : Iterative decoding of block codes is a rather old subjectthat regained much interest recently. The main idea behinditerative decoding is to break up the decoding problem into asequence of stages, iterations, such that each stage utilizesthe output from the previous stages to formulate its ownresult. LÄS MER

  7. 10. Combining analytical and iterative reconstruction in helical cone-beam CT

    Författare :Johan Sunnegårdh; Gösta Granlund; Per-Erik Danielsson; Michel Defrise; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; cone-beam tomography; forward projection; image reconstruction; iterative reconstruction; ordered subsets; regularization; WFBP; Signal processing; Signalbehandling;

    Sammanfattning : Contemporary algorithms employed for reconstruction of 3D volumes from helical cone beam projections are so called non-exact algorithms. This means that the reconstructed volumes contain artifacts irrespective of the detector resolution and number of projection angles employed in the process. LÄS MER