Search for dissertations about: "upward lightning"

Showing result 1 - 5 of 9 swedish dissertations containing the words upward lightning.

  2. 1. On the Attachment of Lightning Flashes to Grounded Structures

    Author : Marley Becerra; Vernon Cooray; Rajeev Thottappillil; Mats Boman; Ivo Gallimberti; Uppsala universitet; []
    Keywords : Engineering physics; Lightning; Lightning attachment; Positive leader discharges; Lightning protection; Thunderstorms; Numerical modeling; Teknisk fysik;

    Abstract : This thesis deals with the physical modeling of the initiation and propagation of upward positive leader discharges from grounded structures during lightning strikes. It includes the analysis of upward leaders initiated under the influence of the electric field produced by a dominant negative cloud charge and due to the combined action of a negative thundercloud and a descending downward stepped negative leader. READ MORE

  4. 2. Experimental Observations and Theoretical Modeling of Lightning Interaction with Tall Objects

    Author : Helin Zhou; Rajeev Thottappillil; Gerhard Diendorfer; Daohong Wang; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tall objects; Upward lightning initiation; Charge density distribution; Upward positive lightning; Upward bipolar lightning;

    Abstract : This thesis investigates various discharge processes associated with upward lightning initiated from tall objects, both experimentally and theoretically, trying to bridge the knowledge-gap in understanding the mechanisms of the phenomena.Upward lightning initiation has attracted a great deal of interest during recent years due to the proliferation of tall communication towers and wind turbines. READ MORE

  5. 3. Some Properties of Lightning Flashes to a Tall Tower on a Mountain Top

    Author : Helin Zhou; Rajeev Thottappillil; Gerhard Diendorfer; Farhad Rachidi; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; tall tower; mountain top; effective height; field enhancements; upward lightning initiation; upward positive lightning; upward bipolar lightning;

    Abstract : .... READ MORE

  6. 4. On the Attachment of Lightning Flashes to Wind Turbines

    Author : Mengni Long; Marley Becerra; Rajeev Thottappillil; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind turbines; upward lightning; lightning attachment of dart and dart-stepped leaders;

    Abstract : The work presented in this thesis aims at investigating the attachment of lightning flashes to wind turbines. Modern wind turbines are highly exposed to lightning strikes, due to the increase of their height and the rotation of the blades. Upward lightning is the dominant mechanism of lightning strikes to them. READ MORE

  7. 5. Measurements of X-Ray Emission from Laboratory Sparks and Upward Initiated Lightning

    Author : Pasan Hettiarachchi; Vernon Cooray; Mats Leijon; Mahbubur Rahman; Marcos Rubinstein; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; X-ray; upward lighting; laboratory discharges; energy distribution;

    Abstract : In 1925 Nobel laureate R. C. Wilson predicted that high electric fields of thunderstorms could accelerate electrons to relativistic energies which are capable of generating high energetic radiation. The first detection of X-rays from lightning was made in 2001 and from long sparks in 2005. READ MORE