Sökning: "positive discharge"

Visar resultat 1 - 5 av 128 avhandlingar innehållade orden positive discharge.

  1. 1. Numerical Simulations of Long Spark and Lightning Attachment

    Författare :Liliana Arevalo; Vernon Cooray; Dan Windmar; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; breakdown; discharge; leader channel; lightning attachment; negative discharge; positive discharge; streamer; Electrical engineering; Elektroteknik; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : The research work presented here is concerned with numerical simulations of two different electrical phenomena: Long gap electrical discharges under switching impulses and the lightning attachment process associated with positive upward leaders. The development of positive upward leaders and the progression of discharges in long gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. LÄS MER

  3. 2. Computer Modelling of Electrophysical Phenomena in High Voltage Insulation

    Författare :Yuriy Serdyuk; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dielectric properties; discharge plasma; composite material; computer model; numerical simulations; electrical discharge;

    Sammanfattning : Different kinds of dielectrics are used for high voltage insulation. In most of the cases, they are combined into complex insulating systems forming macro- and micro-scale composite structures. LÄS MER

  4. 3. Charge Accumulation in Hybrid High Voltage Insulation

    Författare :Mats Sjöberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dielectric barrier; charge accumulation; high voltage; dielectric barrier discharge; dielectric coating; hybrid insulation; electric field distribution; discharge modelling; breakdown strength; charge conditioning;

    Sammanfattning : This thesis deals with the novel idea of controlling the electric stress or field distribution in a hybrid air - solid-dielectric high voltage insulation by promoting accumulation of surface charges on the internal interfacial layers in the combined (hybrid) dielectric structure. Primarily, applications are expected to be found in high voltage dc systems and as a method to improve the resistance against insulation failure by overvoltages, e. LÄS MER

  5. 4. Numerical modelling of positive electrical discharges in long air gaps

    Författare :Oscar Diaz; Vernon Cooray; Raul Montano; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high voltage techniques; numerical modeling; electrical discharge in gases; streamer mechanism; leader channel; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This dissertation deals with research on the numerical modelling of electrical discharges in laboratory long air gaps excited with positive switching impulses. It begins with the preliminary work of several scientists during the last decades, making a detailed analysis of different approaches for modelling all the stages in a full discharge. LÄS MER

  7. 5. Rehabilitation after stroke with focus on early supported discharge and post-stroke fatigue

    Författare :Anna Bråndal; Per Wester; Lillemor Lundin-Olsson; Eva-Lotta Glader; Lena von Koch; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Stroke; early supported discharge; post-stroke fatigue; patient reported outcome measurement; Fatigue assessment scale; cardiorespiratory training; sjukgymnastik; Physiotherapy;

    Sammanfattning : Background Stroke is a major cause of disability worldwide. After treatment in a specialized stroke unit, early supported discharge (ESD) followed by home rehabilitation has shown to be an effective way to improve patient outcome and quality of care for persons with mild to moderate stroke. LÄS MER