Visar resultat 1 - 5 av 65 avhandlingar innehållade ordet Lightning.
Sammanfattning : 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. LÄS MER
2. Electromagnetic Interference in Distributed Outdoor Electrical Systems, with an Emphasis on Lightning Interaction with Electrified Railway Network
Sammanfattning : This thesis deals with the electromagnetic compatibility (EMC) problems of distributed electrical networks, especially that caused by lightning to electrified railway. Lightning transients were found to damage important devices that control train movements, causing traffic stoppage and delays. LÄS MER
3. Interaction of Lightning Flashes with Wireless Communication Networks : Special Attention to Narrow Bipolar Pulses
Sammanfattning : In this thesis, the features of electric field signatures of narrow bipolar pulses (NBPs) generated by cloud flashes are investigated and their effects on wireless communication systems are studied. A handful amount of NBPs (14.5%) have been observed to occur as part of cloud-to-ground flashes in South Malaysia. LÄS MER
Sammanfattning : 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. LÄS MER
Sammanfattning : Propagation of transient waves in nonstationary, inhomogeneous, dispersive, stratified media is considered. Waves originating from sources exterior to the scatterer as well as from internal sources are treated. Algorithms are developed and illustrated by computations of wave phenomena in stationary, nonstationary and weakly nonlinear media. LÄS MER