Sökning: "Electric currents"

Visar resultat 1 - 5 av 74 avhandlingar innehållade orden Electric currents.

  1. 1. Investigations of auroral electric fields and currents

    Detta är en avhandling från Stockholm : KTH

    Författare :Tommy Johansson; KTH.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; auroral physics; auroral electric fields; auroral potential structures; auroral particle acceleration; NATURAL SCIENCES Physics Geocosmophysics and plasma physics Space physics; NATURVETENSKAP Fysik Geokosmofysik och plasmafysik Rymdfysik;

    Sammanfattning : The Cluster spacecraft have been used to investigate auroral electric fields and field-aligned currents (FACs) at geocentric distances between 4 and 7 Re. The electric fields have been measured by the EFW instrument, consisting of two pairs of spherical probes, and the FACs have been calculated from measurements of the magnetic field by the FGM fluxgate magnetometer. LÄS MER

  2. 2. Auroral Electric Fields From Satellite Observations and Numerical Modelling

    Detta är en avhandling från Stockholm : KTH

    Författare :Tomas Karlsson; KTH.; [2001]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Satellite measurements; electric fields; ionosphere; magnetosphere; diverging electric fields; downward current region; black aurora; westward travelling surge; auroral bulge; subauroral ion drifts SAID ; subauroral electric fields SAEF ; mid-latit; TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : This thesis is about electrodynamics of thehigh-latitude/auroral region of near-Earth space. The work ismainly based on electric field measurements made by the doubleprobe instrument on the Freja satellite at altitudes ofapproximately 800-1700 km, together with measurements fromother instruments on the same satellite, and ground-basedinstrumentation. LÄS MER

  3. 3. On the Formation and Structure of the Ionosphere of Titan

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Karin Ågren; Uppsala universitet.; [2012]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Titan; Cassini; space physics; ionisation; electron density; ionosphere; negative ions; electric currents; electric fields; solar zenith angle; Langmuir probe; Space and Plasma Physics; Rymd- och plasmafysik;

    Sammanfattning : We present results on the ionospheric structure around Titan observed during numerous deep (<1000 km) flybys by the Cassini spacecraft. Our results are based on measurements by the radio and plasma wave science instrument, in particular the Langmuir probe. In addition, data from the magnetometer and electron spectrometer have contributed. LÄS MER

  4. 4. Modelling the transient response of windings, laminated steel coresand electromagnetic power devices by means of lumped circuits With special reference to windings with a coaxial insulation system

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Pär Holmberg; Uppsala universitet.; [2000]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Transient response; frequency response; electromagnetic transient analysis; circuit modeling; eddy currents; skin effect; windings; coils; magnetic cores; cables; electric machines; rotating electric machines; transformers; Fysik; NATURAL SCIENCES Physics; NATURVETENSKAP Fysik; Electricity; Esp The Study Of Transients and Discharges; elektricitetslära; ssk studiet av transienter och urladdning;

    Sammanfattning : Electromagnetic transients impinging on electromagnetic power devices - such as electric machines, transformers and reactors - can stress the design severely. Thus the magnitudes of the transients are often decisive for the design of the devices. Further, the operation of a device can be transient in itself. LÄS MER

  5. 5. Magnetizing Currents in Power Transformers Measurements, Simulations, and Diagnostic Methods

    Detta är en avhandling från Stockholm : KTH Royal Institute of Technology

    Författare :Claes Carrander; KTH.; [2017]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transformer core; diagnostics; three-phase; no-load; hysteresis; modeling; resonance; remanence; delta; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : This thesis demonstrates a method for transformer core diagnostics. The method uses the no-load current of the transformer as an indicator, and gives different characteristic signatures for different types of faults or defects. Using the no-load current for the diagnostic gives high sensitivity. LÄS MER