Sökning: "positive leader"

Visar resultat 1 - 5 av 38 avhandlingar innehållade orden positive leader.

  1. 1. Features of the Electric Fields Generated by Lightning with Special Attention to Positive Ground Flashes

    Författare :Dalina Johari; Vernon Cooray; Mahbubur Rahman; Fridolin Heidler; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; positive ground flashes; preliminary breakdown pulses; multiple-trains PBPs; positive leader; bidirectional leader; negative leader branch; subsequent return strokes; distant lightning; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This thesis focuses on the main processes in positive ground flashes and the distant lightning environment for both positive and negative ground flashes. It presents the characteristics of the preliminary breakdown pulses (PBPs), the characteristics of the electric field pulses observed during leader propagation, and the characteristics of the electric fields produced by the first and the subsequent return strokes. LÄS MER

  3. 2. Vi sjunger så bra tillsammans : Om medvetet eller omedvetet samarbete mellan körsångare samt om formella och informella ledare i körstämman

    Författare :Sverker Zadig; Øivind Varkøy; Anne Haugland Balsnes; Örebro universitet; []
    Nyckelord :HUMANIORA; HUMANITIES; choral singing; choral voices; choral singers; choral leader; choir leader; choral conductor; formal leader; informal leader; Music; Musikvetenskap; Musicology esp. Musical Education; Musikvetenskap med musikpedagogisk inriktning;

    Sammanfattning : Aim of the research: This essay describes what can happen between the singers in a choral voice and how the individuals differ in taking initiative and acting in leading roles. Method: I have done qualitative interview studies with conductors and singers, and also recording studies. LÄS MER

  4. 3. Unravelling the social and ecological implications of policy instruments for biodiversity governance

    Författare :Niak Sian Koh; Thomas Hahn; Claudia Ituarte-Lima; Wijnand Boonstra; Johanna Alkan Olsson; Henrik Josefsson; Grace Wong; Stockholms universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; biodiversity offsets; commensurability; commodification; Convention on Biological Diversity; human rights; No Net Loss; Sustainability Science; vetenskap om hållbar utveckling;

    Sammanfattning : Biodiversity losses are occurring at an unprecedented rate, with ongoing environmental degradation at the expense of expanding economic activities. A transformative change is needed away from business-as-usual development and towards prioritizing the conservation and sustainable use of biodiversity. 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. 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