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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Test of traditional vibrational wisdom by 2 proton stripping onto targets of 108;110Pd,114Cd,115In

Maqabuka, Bongani Goodman January 2018 (has links)
Philosophiae Doctor - PhD / The cadmium nuclei have traditionally been regarded as among the best examples of spherical vibrational nuclei. However, advances in nuclear spectroscopy have begun to detail the properties of these nuclei at the two and three vibrational phonon levels, casting doubts on the vibrational assumptions. In particular, the properties of the excited 0+n (for n 2) levels are key to any vibrational model. Excited 0+ states can arise in nuclei in association with the nucleon pairing degrees of freedom, and in model spaces with collective shape degrees of freedom. This thesis reports details of the excited 0+n levels in the even-even nuclei 110;112Cd and 116Sn, and the excited 9 2 + states in 117Sb, investigated using two-proton stripping reactions. The 108;110Pd(3He, n )110;112Cd, 114Cd(3He, n )116Sn and 115In(3He, n )117Sb reactions were investigated using AFRODITE spectrometer in conjunction with a wall of 12 plastic scintillator detectors placed 2 m away from the target chamber.
2

Electromechanics of an Ocean Current Turbine

Tzelepis, Vasileios 18 December 2015 (has links)
The development of a numeric simulation for predicting the performance of an Ocean Current Energy Conversion System is presented in this thesis along with a control system development using a PID controller for the achievement of specified rotational velocity set-points. In the beginning, this numeric model is implemented in MATLAB/Simulink® and it is used to predict the performance of a three phase squirrel single-cage type induction motor/generator in two different cases. The first case is a small 3 meter rotor diameter, 20 kW ocean current turbine with fixed pitch blades, and the second case a 20 meter, 720 kW ocean current turbine with variable pitch blades. Furthermore, the second case is also used for the development of a Voltage Source Variable Frequency Drive for the induction motor/generator. Comparison among the Variable Frequency Drive and a simplified model is applied. Finally, the simulation is also used to estimate the average electric power generation from the 720 kW Ocean Current Energy Conversion System which consists of an induction generator and an ocean current turbine connected with a shaft which modeled as a mechanical vibration system.

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