Sökning: "Lightning"
Visar resultat 11 - 15 av 68 avhandlingar innehållade ordet Lightning.
11. Features and Origin of Electromagnetic Fields Generated by Lightning Flashes
Sammanfattning : Negative cloud-to-ground (CG) lightning flashes transport negative charge from cloud to ground. Negative ground flashes typically involve various processes identified as preliminary breakdown, stepped leader, return stroke, dart leader, dart-stepped leader, subsequent return stroke, and cloud activity between strokes, such as regular pulse trains and chaotic pulse trains. LÄS MER
12. Numerical Simulations of Long Spark and Lightning Attachment
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
13. Simulation of lightning electromagnetic fields and their interaction with low voltage power installations : By Arturo Galván Diego
Sammanfattning : An increasing number of damages of electric nature are being observed on modem electronic sensitiveequipment connected to low voltage power installation (LVPI) networks when they are exposed tolightning electromagnetic fields (LEMPs), or indeed, any other electromagnetic pulse (EMP). The wayin which these fields affect the electronic equipment depends on the properties of the interferencesource, the electromagnetic interaction and the hardness of the device. LÄS MER
14. NOx Production by Ionisation Processes in Air
Sammanfattning : The study presented in this thesis was motivated by the large uncertainty on the concentration of atmospheric electrical discharges to the global nitrogen budget. This uncertainty is partly due to the fact that information concerning the NOx production efficiency of electrical discharges having current signatures similar to those of lightning flashes is not available in the literature. LÄS MER
15. Broadband and HF Radiation from Cloud Flashes and Narrow Bipolar Pulses
Sammanfattning : Remote measurement of electric field generated by lightning has played a major role in understanding the lightning phenomenon. Even though other measurements such as photographic and channel base current have contributed to this research field, due to practical reasons remote measurements of electric field is considered as the most useful tool in lightning research. LÄS MER