Abstracts Category : Other

On the calculation of time-domain impulse-response of systems from band-limited scattering-parameters using wavelet transform

by Maryam Rahmani

In the aspect of electric-ship grounding, the time-domain behavior of the ship hull isneeded. The grounding scheme impacts the nature of voltage transients during switchingevents and faults, identifiability and locatability of ground faults, fault current levels,and power quality. Due to the large size of ships compared with the wavelengths ofthe desired signals, time-domain measurement or simulation is a time-consuming process.Therefore, it is preferred that the behavior be studied in the frequency-domain. In thefrequency-domain one can break down the whole ship hull into small blocks and find thefrequency behavior of each block (scattering parameters) in a short time and then connectthese blocks and find the whole ship hull scattering parameters. Then these scatteringpa- rameters should be transferred to the time-domain. The problem with this processis that the measured frequency-domain data (or the simulated data) is band-limited so,while calculating time-domain solutions, due to missing DC and low frequency contentthe time-domain response encounters causality, passivity and time-delay problems. Despiteavailability of several software and simulation packets that convert frequency-domaininformation to time-domain, all are known to suffer from the above mentioned problems. This dissertation provides a solution for computing the Time-Domain Impulse-Responsefor a system by using its measured or simulated scattering parameters. In this regard, anovel wavelet computational approach is introduced. Advisors/Committee Members: J. Patrick Donohoe (committee member), Masoud Karimi Ghartemani (committee member), Shantia Yarahmadian (committee member), Hendrik F Arnoldus (committee member).