Search for dissertations about: "radio tomography"

Showing result 1 - 5 of 17 swedish dissertations containing the words radio tomography.

  2. 1. Improvements of SPECT by a new collimator design and simultaneous transmission-emission tomography

    Author : Shahrokh Kimiaei; Marija Ivanovic; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Gamma camera; SPECT; Emission tomography; Transmission tomography; Planar-concave collimators; Spatial resolution; Other physics; Övrig fysik; medicinsk strålningsfysik; Medical Radiation Physics;

    Abstract : SPECT (Single Photon Emission Computed Tomography) and planar scintigraphy are the most established and world wide-spread nuclear medicine imaging techniques for clinical use today. SPECT is a tomographic technique that allows 3-D visualization of biochemical processes or physiological flow in the human body by external detection of photons from an administered radiopharmaceutical. READ MORE

  4. 2. Sensing Atmospheric Water Vapor Using Radio Waves: Studies of the 2, 3 and 4-D Structure of the Atmospheric Water Vapor Using Ground-based Radio Techniques Comprising the Global Positioning System, Microwave Radiometry and Very Long Baseline Interferometry

    Author : Lubomir Gradinarsky; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; microwave radiometry; global positioning system GPS ; water vapor; tomography; meteorology; propagation delay; delay gradients; climate;

    Abstract : The radio wave propagation time, the primary observable in the geodetic techniques Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) is affected by the presence of the atmospheric gases. By using appropriate modeling in the post-processing of the recorded phase measurements, together with local meteorological information, it is possible to estimate the total amount of atmospheric water vapor. READ MORE

  5. 3. The Auroral Large Imaging System : design, operation and scientific results

    Author : Urban Brändström; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; Aurora; Artificial airglow; HF-pump enhanced airglow; Multistation measurements; Polar Stratospheric clouds; Radio-Induced optical emissions; Spectroscopic imaging observations; Tomography; Rymd- och plasmafysik; Space physics; Rymdfysik; rymdfysik; Space Physics;

    Abstract : The Auroral Large Imaging System (ALIS) was proposed in 1989 by Åke Steen as a joint Scandinavian ground-based nework of automated auroral imaging stations. The primary scientic objective was in the field of auroral physics, but it was soon realised that ALIS could be used in other fields, for example, studies of Polar Stratospheric Clouds (PSC), meteors, as well as other atmospheric phenomena. READ MORE

  6. 4. Joint inversion and integration of multiple geophysical data for improved models of near-surface structures

    Author : Shunguo Wang; Alireza Malehmir; Mehrdad Bastani; Thomas Kalscheuer; Mark Everett; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; joint inversion; ERT; RMT; CSRMT; boat-towed; tomography; Geofysik med inriktning mot fasta jordens fysik; Geophysics with specialization in Solid Earth Physics;

    Abstract : Geophysical methods are non-invasive and allow an effective way of understanding subsurface structures and their physical properties. One of the main challenges is the often non-uniqueness of the geophysical models and that several different models can explain a dataset to an agreeable fit. READ MORE

  7. 5. Natural and Controlled Source Magnetotelluric Data Processing and Modeling

    Author : Chunling Shan; Thomas Kalscheuer; Laust Pedersen; Mehrdad Bastani; Thorkild Rasmussen; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Geophysics; Airborne Electromagnetic Method; Radio Magnetotellurics; Controlled Source Magnetotellurics; Electrical Resistivity Tomography; Moving Magnetotellurics; 2D inversion; 3D inversion;

    Abstract : In this thesis, four studies using different geophysical electromagnetic methods are presented. In the first study dealing with airborne measurements, the noise response due to the rotation of the aircraft and the aircraft itself as a metallic conductive body on the Earth's electromagnetic response in very low frequency and low frequency band was investigated. READ MORE