Sökning: "spurious solutions"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden spurious solutions.

  1. 1. Reliable hp finite element computations of scattering resonances in nano optics

    Författare :Juan Carlos Araujo-Cabarcas; Christian Engström; David Cohen; Mats G. Larson; Jeffrey Ovall; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scattering resonances; Helmholtz problems; pseudospectrum; Lippmann-Schwinger equation; finite element methods; nonlinear eigenvalue problems; spurious solutions;

    Sammanfattning : Eigenfrequencies are commonly studied in wave propagation problems, as they are important in the analysis of closed cavities such as a microwave oven. For open systems, energy leaks into infinity and therefore scattering resonances are used instead of eigenfrequencies. LÄS MER

  3. 2. Reconstruction Techniques and Finite Volume Schemes for Hyperbolic Conservation Laws

    Författare :Robert Artebrant; Matematik LTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; numerical analysis; Computer science; high order reconstruction; Conservation law; finite volume method; Datalogi; control; systems; kontroll; numerisk analys; system;

    Sammanfattning : This thesis concerns the numerical approximation of the solutions to hyperbolic conservation laws. In particular the research work focuses on reconstruction techniques; the reconstruction being the key ingredient in modern finite volume schemes aiming to increase spatial order of accuracy. LÄS MER

  4. 3. Numerical methods for waveguide modelling

    Författare :Christer Johansson; Björn Engquist; Per Lötstedt; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Waveguide; finite element; hp-adaptivity; helmholtz; maxwell; Numerical analysis; Numerisk analys;

    Sammanfattning : Waveguides are used to transmit electromagnetic signals. Their geometry is typically long and slender. This particular shape can be used in the design of efficient computational methods. Only special modes are transmitted and eigenvalue and eigenvector analysis becomes important. LÄS MER

  5. 4. Stable FEM-FDTD Hybrid Method for Maxwell's Equations

    Författare :Thomas Rylander; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Finite Element Method; scattering; antennas; stability analysis; edge elements; Maxwell s equations; NASA almond; microwave circuits; mass lumping; proof of stability; explicit-implicit time-stepping; Finite-Differences Time-Domain;

    Sammanfattning : In this thesis edge elements are applied to solve several problems in computational electromagnetics. In particular, a hybrid scheme joining the Finite Element Method (FEM) and the Finite-Difference Time-Domain (FDTD) algorithm is developed, tested and exploited. LÄS MER

  7. 5. Numerical algorithms for nonlinear eigenproblems with eigenvector nonlinearities

    Författare :Parikshit Upadhyaya; Elias Jarlebring; Robert Corless; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; numerical algorithms; nonlinear eigenproblems; multiparameter eigenvalue problem; nonlinear eigenvalue problem; eigenvector nonlinearities; nepv; scf; p-laplacian; quasi-newton; Numerical Analysis; Numerisk analys;

    Sammanfattning : Eigenproblems and their nonlinear generalizations appear as important problems in a wide variety of fields, ranging from quantum chemistry and vibration analysis to macroeconomics and data science. Hence, the development and analysis of numerical algorithms to solve such problems has a broad multiplicative effect on our ability to answer several crucial scientific questions. LÄS MER