Search results for "virheanalyysi"
showing 10 items of 23 documents
Functional a posteriori error estimates for boundary element methods
2019
Functional error estimates are well-established tools for a posteriori error estimation and related adaptive mesh-refinement for the finite element method (FEM). The present work proposes a first functional error estimate for the boundary element method (BEM). One key feature is that the derived error estimates are independent of the BEM discretization and provide guaranteed lower and upper bounds for the unknown error. In particular, our analysis covers Galerkin BEM and the collocation method, what makes the approach of particular interest for scientific computations and engineering applications. Numerical experiments for the Laplace problem confirm the theoretical results.
A posteriori error control for Maxwell and elliptic type problems
2014
Guaranteed error bounds and local indicators for adaptive solvers using stabilised space-time IgA approximations to parabolic problems
2019
The paper is concerned with space–time IgA approximations to parabolic initial–boundary value problems. We deduce guaranteed and fully computable error bounds adapted to special features of such type of approximations and investigate their efficiency. The derivation of error estimates is based on the analysis of the corresponding integral identity and exploits purely functional arguments in the maximal parabolic regularity setting. The estimates are valid for any approximation from the admissible (energy) class and do not contain mesh-dependent constants. They provide computable and fully guaranteed error bounds for the norms arising in stabilised space–time approximations. Furthermore, a p…
Functional Type Error Control for Stabilised Space-Time IgA Approximations to Parabolic Problems
2018
The paper is concerned with reliable space-time IgA schemes for parabolic initial-boundary value problems. We deduce a posteriori error estimates and investigate their applicability to space-time IgA approximations. Since the derivation is based on purely functional arguments, the estimates do not contain mesh dependent constants and are valid for any approximation from the admissible (energy) class. In particular, they imply estimates for discrete norms associated with stabilised space-time IgA approximations. Finally, we illustrate the reliability and efficiency of presented error estimates for the approximate solutions recovered with IgA techniques on a model example. peerReviewed
A posteriori error estimates for variational problems in the theory of viscous fluids
2016
The papers included in the thesis are focused on functional type a posteriori error estimates for the Stokes problem, the Stokes problem with friction type boundary conditions, the Oseen problem, and the anti-plane Bingham problem. In the summary of the thesis we consider only the Oseen problem. The papers present and justify special forms of these estimates which are suitable for the approximations generated by the Uzawa algorithm. The estimates are of two main types. Estimates of the first type use exact solutions obtained on the steps of the Uzawa algorithm. They show how errors encompassed in Uzawa approximations behave and have mainly theoretical meaning. Estimates of the second type o…
Structural Parameters under Partial Least Squares and Covariance-Based Structural Equation Modeling : A Comment on Yuan and Deng (2021)
2023
In their article, Yuan and Deng argue that a structural parameter under partial least squares structural equation modeling (PLS-SEM) is zero if and only if the same structural parameter is zero under covariance-based structural equation modeling (CB-SEM). Yuan and Deng then conclude that statistical tests on individual structural parameters assessing the null hypothesis of no effect can achieve the same purpose in CB-SEM and PLS-SEM. Our response to their article highlights that the relationship they find between PLS-SEM and CB-SEM structural parameters is not universally valid, and that consequently, tests on individual parameters in CB-SEM and PLS-SEM generally do not fulfill the same pur…
Analyse des difficultés des finnophones dans la maîtrise des pronoms français dans les tests YKI
2008
Sanarakenteen hahmottaminen : venäjänkielisten 7.–9.-luokkalaisten epäsanojen sanarakenteen tunnistuksen taidot psykolingvistisissä testeissä
2016
Tutkimukseni tutkii suomea toisena kielenä (S2) puhuvien venäjänkielisten nuorten kielitaitoa. Tutkimusryhmä koostuu saman kielitaustan jakavista oppilaista, joilla on vähäisen kielen oppimisajan, maassaoloajan tai kaksikielisyyden vuoksi puutteita toisen kielen sanarakenteen tunnistuksen taidoissa. Tässä tutkielmassa tarkastellaan kuinka hyvin venäjänkieliset 7.-9.-luokkalaiset suomen kielen oppijat hallitsevat suomen kielen sanarakenteen? Tätä tarkastellaan psykolingvistisen testistön avulla etsimällä vastauksia kahteen alakysymykseen: a) Millaisia virheitä venäjänkieliset 7.–9.-luokkalaiset suomen kielen oppijat tekevät psykolingvistiseen testistöön kuuluvassa epäsanatestissä silloin, ku…
Kolmasluokkalaisten sanelutesti : siirtymäajat, kokonaisajat ja virheluokittelu tietokonepohjaisessa sanelutestissä
2004
Uncertainty analysis and symmetry restoration in nuclear self-consistent methods
2015
This thesis contains two articles, in the following denoted by I and II, and an introduction to them. In Chapter 1, I present the theoretical models of nuclear structure. In Chapter 2, I introduce the basic ideas about the density functional theory (DFT) and self-consistent mean-field (SCMF) calculations. In Chapter 3, I give the formulae for the uncertainty propagation, which is the error analysis method used in article I. As a proper tool to survey the predictive power of theoretical models, the error analysis now has become more and more widely used. By analyzing the propagation of uncertainties, one tries to find out the e ectiveness of the calculation with a given parameter set obtaine…