Search for dissertations about: "reflection coefficient"

Showing result 16 - 20 of 33 swedish dissertations containing the words reflection coefficient.

  2. 16. Radio Frequency Systems for NMR Imaging: Coil Development and Studies of Non-Thermal Biological Effects

    Author : Lars Malmgren; Lunds universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; anechoic chamber; TEM transmission cells; FDTD; circularly polarized electromagnetic fields; reduced coupling; noise matching; matching networks; low noise amplifiers; upper thoracic spine; surface coils; Nuclear magnetic resonance; magnetic resonance imaging; non-thermal biological effects; blood-brain barrier; Electronics; Elektronik;

    Abstract : This thesis concerns both design and optimization of NMR imaging systems and studies on non-thermal biological effects of electromagnetic fields. These two research fields are linked together by the fact that humans are subject to static and pulsed magnetic fields as well as to magnetic radio frequency fields (RF) during an NMR imaging investigation. READ MORE

  4. 17. Methods for Modelling and Characterization of In-Duct Sources

    Author : Hans Rämmal; Hans Bodén; Mats Åbom; Antonio Torregrosa; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Abstract : Methods to characterize acoustic sources in flow ducts have been investigated. In the first part of this thesis a measurement procedure to characterize an air terminal device using an acoustic one-port source model based on the two microphone technique has been tested and validated. READ MORE

  5. 18. Analytical Aspects of Atmospheric Pressure Ionisation in Mass Spectrometry

    Author : C. Fredrik Bökman; J. David Pinkston; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Analytical chemistry; Analytisk kemi; Analytical chemistry; Analytisk kemi; Analytical Chemistry; analytisk kemi;

    Abstract : The actual signal recorded with an analytical instrument is not always a true reflection of the analysed sample. In this thesis a further insight of the atmospheric pressure ionisation processes electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) has been endeavoured, to provide a deeper understanding of and ways to minimize this bias. READ MORE

  6. 19. Shape and material optimization for antenna applications

    Author : Per Jacobsson; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; explicit-implicit time stepping; sensitivity analysis; Nitsche s method; total scattering cross section; shape and material optimization; array antennas; finite element method;

    Abstract : In this thesis, a gradient-based method for shape and material optimization fortwo antenna applications is presented: minimization of the active reflectioncoefficient for conformal array antennas; and minimization of the totalscattering cross section for cylindrical scatterers. The sensitivity of theobjective function with respect to changes of the shape and material of the geometry isexpressed in terms of the original field problem and an adjoint field problem. READ MORE

  7. 20. Design and Fabrication of III-V Semiconductor Devices for Millimetre- and Submillimetre Wave Applications

    Author : Svein M. Nilsen; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : Devices (various types of diodes) have been fabricated in several different III-V semiconductors (AlxGa1-xAs, In1-xGaxAs, and InAs). The III- V compound semiconductors lend themselves well to high frequency applications due to the high electron mobility that can be obtained. READ MORE