Browsing NTNU Open by Author "Ilmavirta, Joonas"
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Higher-order Hamilton–Jacobi perturbation theory for anisotropic heterogeneous media: dynamic ray tracing in Cartesian coordinates
Iversen, Einar; Ursin, Bjørn; Saksala, Teemu; Ilmavirta, Joonas; de Hoop, Maarten (Journal article; Peer reviewed, 2019)With a Hamilton–Jacobi equation in Cartesian coordinates as a starting point, it is common to use a system of ordinary differential equations describing the continuation of first-order derivatives of phase-space perturbations ... -
Higher-order Hamilton–Jacobi perturbation theory for anisotropic heterogeneous media: transformation between Cartesian and ray-centred coordinates
Iversen, Einar; Ursin, Bjørn; Saksala, Teemu; Ilmavirta, Joonas; V. de Hoop, Maarten (Peer reviewed; Journal article, 2021)Dynamic ray tracing is a robust and efficient method for computation of amplitude and phase attributes of the high-frequency Green’s function. A formulation of dynamic ray tracing in Cartesian coordinates was recently ... -
Optimal recovery of a radiating source with multiple frequencies along one line
Brander, Tommi Olavi; Ilmavirta, Joonas; Piiroinen, Petteri; Tyni, Teemu (Peer reviewed; Journal article, 2020)We study an inverse problem where an unknown radiating source is observed with collimated detectors along a single line and the medium has a known attenuation. The research is motivated by applications in SPECT and beam ...