Sökning: "Anders Forsgren"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden Anders Forsgren.

  1. 1. On low order controller synthesis using rational constraints

    Författare :Daniel Ankelhed; Anders Hansson; Anders Helmersson; Anders Forsgren; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; H-infinity synthesis; Linear Matrix Inequalities; rank constraints; polynomial constraints; interior point methods; Automatic control; Reglerteknik;

    Sammanfattning : In order to design robust controllers, H-infinity synthesis is a common tool to use. The controllers that result from these algorithms are typically of very high order, which complicates implementation. LÄS MER

  3. 2. Multicriteria optimization for managing tradeoffs in radiation therapy treatment planning

    Författare :Rasmus Bokrantz; Anders Forsgren; Karl-Heinz Küfer; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optimization; multicriteria optimization; robust optimization; Pareto optimality; Pareto surface approximation; Pareto surface navigation; intensity-modulated radiation therapy; volumetric-modulated arc therapy; intensity-modulated proton therapy; Optimering; flermålsoptimering; robust optimering; Paretooptimalitet; Paretofrontsapproximation; Paretofrontsnavigering; intensitetsmodulerad strålterapi; rotationsterapi; intensitetsmodulerad protonterapi;

    Sammanfattning : Treatment planning for radiation therapy inherently involves tradeoffs, such as between tumor control and normal tissue sparing, between time-efficiency and dose quality, and between nominal plan quality and robustness. The purpose of this thesis is to develop methods that can facilitate decision making related to such tradeoffs. LÄS MER

  4. 3. Toward Robust Optimization of Adaptive Radiation Therapy

    Författare :Michelle Böck; Anders Forsgren; Minsun Kim; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; optimization; adaptive radiation therapy; radiation therapy treatment planning; uncertainty; robust optimization; stochastic programming; Tillämpad matematik och beräkningsmatematik; Applied and Computational Mathematics;

    Sammanfattning : Adaptive radiation therapy is an evolving cancer treatment approach which relies on adapting the treatment plan in response to patient-specific interfractional geometric variations occurring during the fractionated treatment. If those variations are not addressed through adaptive replanning, the resulting treatment quality may be compromised. LÄS MER

  5. 4. Utilizing Problem Structure in Optimization of Radiation Therapy

    Författare :Fredrik Carlsson; Anders Forsgren; Edwin Romeijn; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optimization; intensity-modulated radiation therapy; conjugate-gradient method; step-and-shoot delivery; column generation; quasi-Newton method; regularization; sequential quadratic programming; Optimization; systems theory; Optimeringslära; systemteori;

    Sammanfattning : In this thesis, optimization approaches for intensity-modulated radiation therapy are developed and evaluated with focus on numerical efficiency and treatment delivery aspects. The first two papers deal with strategies for solving fluence map optimization problems efficiently while avoiding solutions with jagged fluence profiles. LÄS MER

  7. 5. Approaches to accelerate methods for solving systems of equations arising in nonlinear optimization

    Författare :David Ek; Anders Forsgren; Jacek Gondzio; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nonlinear optimization; mathematical programming; interior-point methods; approximate solutions to systems of linear equations; method of conjugate gradients; quasi-Newton methods; modified Newton methods; Ickelinjär optimering; matematisk programmering; inre-punktsmetoder; approximativa lösningar till linjära ekvationssystem; konjugerade gradientmetoden; kvasi-Newtonmetoder; modifierade Newtonmetoder.; Optimization and Systems Theory; Optimeringslära och systemteori;

    Sammanfattning : Methods for solving nonlinear optimization problems typically involve solving systems of equations. This thesis concerns approaches for accelerating some of those methods. In our setting, accelerating involves finding a trade-off between the computational cost of an iteration and the quality of the computed search direction. LÄS MER