Sökning: "Local approximation"

Visar resultat 1 - 5 av 157 avhandlingar innehållade orden Local approximation.

  1. 1. Model Vertices Beyond the GW Approximation

    Författare :Mikael Hindgren; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; GW approximation; Electron self energy; Green s function; consistency; local-field corrections; vertex function; conserving approximations; variational energies; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Hindgren;

    Sammanfattning : We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. LÄS MER

  3. 2. Approximation of topology optimization problems using sizing optimization problems

    Författare :Anton Evgrafov; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; structural optimization; bilevel programming; approximation; topology optimization; control in coefficients; optimal design; fictitious domain; control in coefficients;

    Sammanfattning : The present work is devoted to approximation techniques for singular extremal problems arising from optimal design problems in structural and fluid mechanics. The thesis consists of an introductory part and four independent papers, which however are united by the common idea of approximation and the related application areas. LÄS MER

  4. 3. Numerical analysis for random processes and fields and related design problems

    Författare :Konrad Abramowicz; Oleg Seleznjev; Krzysztof Podgórski; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stochastic processes; random fields; approximation; numerical integration; Hermite splines; piecewise linear interpolator; local stationarity; point singularity; stratified Monte Carlo quadrature; Asian option; Monte Carlo pricing method; Lévy market models; Mathematical statistics; Matematisk statistik; Mathematical Statistics; matematisk statistik;

    Sammanfattning : In this thesis, we study numerical analysis for random processes and fields. We investigate the behavior of the approximation accuracy for specific linear methods based on a finite number of observations. Furthermore, we propose techniques for optimizing performance of the methods for particular classes of random functions. LÄS MER

  5. 4. Privacy Mechanism Design Through the Lens of Information Theory : With Applications to Compression, Caching, and Semantic Communication

    Författare :Amirreza Zamani; Mikael Skoglund; Tobias J. Oechtering; Parastoo Sadeghi; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Privacy mechanism design; Leakage matrix; Strong privacy criterion; KL-divergence; Local approximation; Euclidean information geometry; Privacy-utility trade-off; χ2-privacy criterion; l1-privacy criterion; Common information; Functional representation lemma; Two-part construction coding; Design av sekretessmekanism; Läckagematris; Stark sekretesskriterium; KL-divergens; Lokal approximation; Euklidisk informationsgeometri; Sekretess-nyttoavvägning; χ2-sekretesskriterium; l1-sekretesskriterium; Gemensam information; Lemma för funktionell representation; Kodning med tvådelad konstruktion.; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Privacy mechanism design is an important research area and is receiving increased attention in recent years. This field focuses on addressing the challenge of revealing general data that might have correlations with sensitive information, all while protecting this sensitive information against unauthorized access. LÄS MER

  7. 5. Contributions to Numerical Solution of Stochastic Differential Equations

    Författare :Anders Muszta; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; adaptive method; change of time; CIR model; CKLS model; convergence order; Euler method; heavy-tailed SDE; hyperbolic SDE; geometric integration; global Lipschitz condition; Levy process; Lie group method; local Lipschitz condition; local martingales; mean reversion; Milstein method; numerical method; semimartingale; stochastic differential equation; stochastic Taylor expansion; strong approximation; symplectic integration; volatility induced stationarity; waveform relaxation; volatility induced stationarity;

    Sammanfattning : This thesis consists of four papers: Paper I is an overview of recent techniques in strong numerical solutions of stochastic differential equations, driven by Wiener processes, that have appeared the last then 10 years, or so. Paper II studies theoretical and numerical aspects of stochastic differential equations with so called volatility induced stationarity. LÄS MER