This thesis describes work carried out in an attempt to relate the physical properties, in particular, the restivity of certain electrical conductors to the secondary field generated by them in the presence of an alternating primary electromagnetic field. It also discusses, the feasability of determining these properties by the normal methods of electromagnetic prospecting, and relating them to the mineralogical properties of geological conductors. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In this thesis, computer methods for the transient analysis of networks are investigated. Numerical transform techniques are developed to solve the differential equations a rising in network simulation. Extensions to permit inclusion of some nonlinear elements are considered. Efficient methods for implementing the techniques are developed. For the transform techniques, error estimates are derived. Using these estimates, algorithms for the automatic determination of solution parameters are developed. Advantages over other numerical transform and numerical integration techniques are revealed. For nonlinear networks, it is shown that use of a Newton-Raphson scheme for solving nonlinear algebraic equations is difficult when coupled with transform methods for solving differential equations. Instead, an alternative technique is developed. Steps which are easily generated, but which only approximate Newton-Raphson steps, are used. The implementation of the transform techniques and the nonlinear solution is considered. A program using a sparse tableau form of network equations is discussed. The program is in two sections. The first reads in the network descriptions, and writes a series of Fortran subroutines for performing the analysis efficiently. The subroutines must be compiled, and are used by the second part of the program to perform the actual analysis. Examples which illustrate the performance of the various techniques are presented. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The thesis presents an analysis of the steady-state operation of a multiconductor power transmission line with distributed compensation. The analysis outlines two methods for deriving the voltage and current equations along the line starting from Maxwell's coefficients and the Telegraph equations. Correction factors due to an imperfect earth and conductor internal impedance are discussed. Also, by making the assumption that the system of conductors is completely transposed it is shown that considerable simplification of the equations is possible. Numerical results are given for a two and a four-conductor, single phase transmission line with earth return and for a three-phase system having four conductors per phase. The results show that successful operation of the system is prevented by electric field limitations at the surface of the conductors. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

A method based on phaselock techniques, for synchronizing the local oscillator signals in a proposed two-dish supersynthesis at 1420 MHz is presented. To demonstrate the feasibility of this method, the design and construction of a working system that provides phase-coherent, 1390 MHz signals at two sites, separated by a time-varying path length, is described. The phase accuracy of this system is ±5°. A provision for introducing a known phase difference between the two signals, in a manner that is suitable for interfacing with a digital computer, is included. Also, operation of the system over a frequency range greater than the expected range of doppler shift is possible, without the risk of locking to a wrong sideband. Transistor microwave oscillators at 1.4 GHz are used as voltage-controlled oscillators in this system. The performance of these devices is compared with that of the conventional voltage-controlled crystal oscillator/multiplier chain. Test results are given, which indicate that the system is suitable for use in an operational environment. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Procedures for the synthesis of a class of two-element-kind multiport networks are developed and illustrated by examples. In the RC case, the networks consist of the series connection of an R network and an RC network. The latter contains at least one capacitor tree so that its open-circuit impedance matrix vanishes at infinite frequency. It is shown that for a network within the class, the open-circuit impedance matrix and the normal form state model are equivalent in that, given one, the other can be written immediately. The synthesis problem then takes the form of the determination of a normal coordinate transformation such that the transformed state variables may be identified as capacitor voltage variables in a passive RC network. Two procedures are described for determining a transformation (modal) matrix which yields an irreducible realization of a given kxk, nͭʰ degree impedance matrix. There are ½(n-k) (n-k-l) degrees of freedom in the modal matrix. General analytical solutions are possible when n≤k+2, one greater than in existing methods. The main procedure yields a network with, in general, n + ½k(k+1) capacitors. A set of necessary conditions, easily applied to the given impedance matrix, is derived. Necessary and sufficient conditions are given for the special case k=2, n=3- An alternative procedure yields a network with n capacitors. Using either procedure, it is possible to simultaneously minimize both the number of elements and the total capacitance in the network. By introducing additional equations into the main procedure, numerical solutions for the modal matrix may be determined for any value of n. With k=2, the procedure yields a new class of minimal, grounded two-port networks consisting of one π-section and n-2 T-sections connected in parallel. The severity of the realizability conditions is approximately proportional to n. A given 2x2 impedance matrix may be realized exactly, or one driving-point impedance function may be realized, exactly and the transfer impedance function with a desired gain factor (within the limits of realizability). A computational procedure is given which minimizes the total capacitance and optimizes the voltage gain factor. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The increase in breakdown potential of a spark channel, formed by discharging a high current pulse between tungsten electrodes, has been studied at times after the current pulse ceases. The dependence of the breakdown potential on time is called the recovery characteristic of the spark channel. The characteristics have been measured for spark channels in air, hydrogen, nitrogen, argon and sulfur hexafluoride. Two new methods of measuring the spark channel temperature and diameter are described. In the first, the temperature is determined from the breakdown potential of an auxiliary spark gap in the second, the temperature is deduced by measuring the velocity of sound in the channel with piezo-electric pressure probes. The results indicate that the maximum diameter of the channel is determined by the interaction between the channel and gas in the surrounding vessel. Temperature measurements agree with the results of earlier workers. By using layered electrodes with tungsten surfaces, it is shown that the recovery characteristic of air sparks is controlled by the cooling effects of the electrodes. Measurements on hydrogen sparks, demonstrate that the breakdown potential increases significantly 10 ¯¹ sees after the spark channel is formed. Changes produced by doping the hydrogen with water vapour and oxygen indicate that this delayed increase in breakdown potential is produced by the adsorption of hydrogen onto the tungsten electrode surfaces. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In this thesis the use of the digital computer in determining the steady-state response of nonlinear networks is investigated. Two classes of such networks, forced oscillating networks and self-oscillating networks, are considered. For the first class, a method of obtaining the network equations is developed, and an algorithm for calculating the numerical solution is obtained. For the second class, the development is restricted to those networks which can be described by [ Formula omitted ] and the previous algorithm is extended to solve this problem. For both classes, a substitution is developed which can expedite the analysis when the nonlinearities are exponential in character. The effectiveness of the methods is demonstrated by examples. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This report describes attempts to discover a method for starting a water walled argon arc at high pressure. It is demonstrated that addition of small amounts of acetylene to the argon causes a very small reduction of breakdown voltage at pressures of about 3 atmospheres. Droplets of distilled water and of KC1 solution are shown to effectively increase the breakdown potential of a gas. A calculation of static fields before arc ignition is presented, and alternative starting circuit tests are done. Parallel starting pulse injection is found inferior to the normally used series injection. An auxiliary discharge is found to aid starting slightly, and a drastic decrease in the breakdown potential due to removal of the water wall is discovered. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The power balance equations for the column of a 500 A DC vortex stabilized arc in argon have been solved numerically to give predicted values for the temperature profile, radiative power and heat transport to the wall. These quantities have also been measured using spectroscopy and calorimetry, and compared with the theoretical results so as to refine our understanding of the heat transport processes in the arc. Further study is required to predict convective effects accurately, especially at low power levels, but the results show that the behaviour of the column is predictable at high power levels. Forced convection has been shown to play an important role in the arc column. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

M.Ing.