Sökning: "NATURAL SCIENCES Physics Other physics Geophysics"

Visar resultat 6 - 10 av 40 avhandlingar innehållade orden NATURAL SCIENCES Physics Other physics Geophysics.

1. 6. Plane wave electromagnetic measurements for imaging fracture zones

   Författare :Lena Persson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geophysics; Electromagnetic Measurements Fracture Zones; Geofysik; Geophysics; Geofysik; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

   Sammanfattning : Electromagnetic fields from distant radio transmitters interact with the resistivity structures in the earth. They can be regarded as plane-wave fields since their penetration depth is much smaller than their wavelength. LÄS MER

3. 7. Cluster in situ studies of the auroral acceleration region

   Författare :Bin Li; Göran Marklund; Stein Haaland; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cluster; Aurora acceleration region; Physics; Fysik;

   Sammanfattning : This thesis addresses a central topic in auroral physics, namely particle accelerationproducing intense aurora as well as energetic plasma outflow. Cluster satellitemeasurements of electric and magnetic fields, electrons and ions, collected across auroralfield lines, are used to study various aspects of the quasi-static auroral accelerationregion (AAR), its relation to the auroral density cavity, and the relative role of quasistaticand Alfvénic acceleration for producing aurora. LÄS MER

4. 8. Efficient Electromagnetic Induction Modelling : Adaptive mesh optimisation, advanced boundary methods and iterative solution techniques

   Författare :Laura M. Buntin; Thomas Kalscheuer; Gunilla Kreiss; Zhengyong Ren; Klaus Spitzer; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied geophysics; Electromagnetic theory; Numerical Modelling; Geo-Electromagnetics; Magnetotellurics; Controlled-source electromagnetics; Goal-oriented adaptive mesh refinement; Perfectly-matched layers; Iterative solution methods; Preconditioning; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

   Sammanfattning : Forward modelling of electromagnetic induction data simulates the electric and magnetic fields within a computational domain for a given distribution of electromagnetic material properties and a given source of the electromagnetic field. The quantities of interest are the fields at receiver locations at the Earth's surface. LÄS MER

5. 9. Seismics, 2D and 3D Inversion of Magnetotellurics : Jigsaw pieces in understanding the Skellefte Ore District

   Författare :María de los Ángeles García Juanatey; Ari Tryggavson; Ute Weckmann; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetotellurics; 2D inversion; 3D inversion; hard rock seismics; mineral exploration; integrated geophysics; 4D modeling; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

   Sammanfattning : The Skellefte District (SD) is one of the richest metallogenic mining areas in Sweden. The main deposits consist of volcanic-hosted massive sulphides (VHMS) rich in zinc, copper, lead, gold and silver, that have been explored and mined for more than a century. LÄS MER

7. 10. Three-dimensional forward modelling and inversion of controlled-source electromagnetic data using the edge-based finite-element method

   Författare :Paula Rulff; Thomas Kalscheuer; Michael Becken; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied geophysics; Controlled-source electromagnetics; Numerical modelling; Finite-element method; Geophysical inversion; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

   Sammanfattning : Electromagnetic geophysical methods are applied to investigate anomalous subsurface structures exhibiting contrasts in electrical resistivity, as for example in mineral exploration or geothermal areas. When evaluating electromagnetic data, one big challenge is to account for full three-dimensional measurement setups and subsurface scenarios. LÄS MER