Engineering Commons^™

Analysis Of Oscillations In Nonlinear Systems Using Multiple Input Describing Functions, Frederic Lee Swern

Dissertations

Sufficient conditions for oscillation as well as absence of oscillations are presented for a class of systems containing one lumped linear element and a differentiable nonlinearity. The results are obtained by estimating the error inherent in using a describing function analysis. Contraction type arguments are used to show common topological properties of the describing function solution and the balance of first harmonic terms of the system.

After discussing the describing function method, two theorems are presented regarding existence or nonexistence of oscillations from homotopic considerations. A graphical method for examining systems with power law nonlinearities is given using a parameter …

Investigations Of Gate Turn-Off Structures, Hans Werner Becke

Dissertations

Research and Development was done on gate turn-off devices. The aim was i) to improve turn-off capability without compromise of turn-on, on-state, and useful temperature range, ii) to implement "safe" turn-off.

A) The dependence of the electrical device characteristics on cathode width for an optimized vertical structure was determined. Fall times of 100 to 200 nsec and risetimes of <400 nsec were simultaneously obtained for average current densities of 53 A/cm² @ T_j = 125°C. From spreading resistance analysis the fast t_r and t_f response is shown to be a consequence of proper Au-distribution in the active device volume.

From transient analysis it is concluded that for safe …

Statistical Averaging In Position Determination By Holography Under Turbulence Conditions, Paul Aloysius Mcgovern

Dissertations

An investigation of several, disparate phenomena is conducted with the aim of developing a novel surveying system capable of overcoming the limitations imposed by turbulence in modern surveying. This method incorporates standard holographic techniques and time domain statistical averaging of survey data.

Some pertinent characteristics of atmospheric turbulence are reviewed, and the restrictions imposed on standard surveying practices by such turbulence are identified. A model for the turbulent medium is proposed on the basis of previous work and several theoretical results are summarized and extended.

On this basis the technical characteristics of the proposed technique are developed and each step …

A Method Of Modeling Multirate Two-Dimensional Recursive Digital Filters Author, Albert P. Gerheim

Electrical & Computer Engineering Theses & Dissertations

This dissertation presents a method of modeling two dimensional sampled data systems with two sampling rates in each dimension. This methodology is applied to the problem of synthesizing two dimensional velocity filters using one dimensional prototypes and multirate concepts.

The modeling method includes the replacement of scalar z-transforms of signals by vectors of polynomials, and the replacement of scalar z-transforms of impulse responses by matrices of polynomials.

The synthesis of velocity filters is accomplished through the use of coordinate transformations in the z-transform domain which skew the ω₁ -ω₂ axes on the unit bidisc. The filters synthesized using …

Optimization Of An Investment Strategy For The Mcdonnell Douglas Salaried Savings Plan., Richard Charles Seifert

Masters Theses

"An automated technique is developed to maximize the return on investments in the McDonnell Douglas Salaried Savings Plan. Continual guidance is provided to the participant as to the currently preferred type of investment within the Plan, and to the strategic t iming of withdrawals from the Plan. The decision criteria within the modelled system address the tradeoff s which result from the participant's past investment decisions, his current tax situation, alternative market conditions, withdrawal penalties and o the r Plan characteristics. Decisions are made on the premise that historic performance patterns will continue, though adaptive procedures are included to react …

The Design And Development Of A Human Interface For An Intelligent Terminal For A Process Control Industry, V. Rangarajan

Masters Theses

"A complete description of an intelligent Terminal to be used in a Process Control Industry is presented. The system software is discussed. An account of the hardware and software interfaces for the input devices, along with the description of the input devices, is included. The data base used in the system is described with an example. Future enhancements have been proposed."--Abstract, page iii.