Sökning: "likström"

Visar resultat 1 - 5 av 9 avhandlingar innehållade ordet likström.

  1. 1. On the design of hybrid DC-breakers consisting of a mechanical switch and semiconductor devices

    Författare :Jesper Magnusson; Göran Engdahl; Staffan Norrga; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DC; circuit breaker; hybrid breaker; DC systems; DC; brytare; hybridbrytare; likström;

    Sammanfattning : The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. LÄS MER

  3. 2. Electroosmosis Based Treatment Approach for Cerebral Edema

    Författare :Teng Wang; Xiaogai Li; Svein Kleiven; Tiit Illimar Mathiesen; KTH; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Cerebral edema; electroosmosis based treatment; finite element head model; electroosmotic flow; Technology and Health; Teknik och hälsa;

    Sammanfattning : Cerebral edema characterized as an abnormal accumulation of excess fluid in the intracellular or extracellular spaces has not been treated effectively despite aggressive treatments. As a result, cerebral edema often leads to intracranial pressure (ICP) elevation with potentially severe consequences unless treated effectively. LÄS MER

  4. 3. Performance Quantification of Interarea Oscillation Damping Using HVDC

    Författare :Joakim Björk; Karl H. Johansson; Lennart Harnefors; Robin Preece; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; HVDC transmission control; interarea oscillations; power oscillation damping; small-signal stability; frequency control; controllability; MIMO control; decoupling control; multivariable interaction; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : With the transition towards renewable energy, and the deregulation of the electricity market, generation patterns and grid topology are changing. These changes increase the need for transfer capacity. One limiting factor, which sometimes leads to underutilization of the transmission grid, is interarea oscillations. LÄS MER

  5. 4. Fundamentals of Polyethylene Composites for HVDC Cable Insulation – Interfaces and Charge Carriers

    Författare :Mattias E. Karlsson; Richard Olsson; Mikael Skrifvars; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; polyethylene; nanocomposites; HVDC; conductivity; metal oxide; nanoparticles; surface functionality; polyeten; nanokompositer; HVDC; konduktivitet; metalloxider; nanopartiklar; ytfunktionalitet; Fiber- och polymervetenskap; Fibre and Polymer Science;

    Sammanfattning : Power transmission over long distances by using high voltage direct current (HVDC) cables is important for the transition from fossil energy to using renewable energy sources, e.g. wind, solar and water. LÄS MER

  7. 5. Electronic, Transport, and Optical Properties of Broken-Gap Heterostructures

    Författare :Karin Nilsson; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; relaxation; magnetic resonance; supraconductors; magnetic and optical properties; k.p calculations; Condensed matter:electronic structure; electrical; interband transport; electron-hole hybridization; spin polarization; spectroscopy; spektroskopi; Kondenserade materiens egenskaper:elektronstruktur; egenskaper elektriska; magnetiska och optiska ; supraledare; magnetisk resonans;

    Sammanfattning : This thesis examines the physical properties of broken-gap heterostructures using a multiband k.p model and self-consistent calculations. Broken-gap heterostructures, made from InAs, GaSb, and AlSb, are characterized by a special band alignment with an overlap between the InAs conduction band and the GaSb valence band. LÄS MER