Thesis (MScIng)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

This research investigated whether the same attributes that cause managers to improve performance following upward feedback also encourage subordinates to give open and honest upward feedback. By proving that these attributes encourage integrity in upward feedback, this research allows organisations to freely implement programmes to increase the desired attributes among employees without fear of jeopardising the desired integrity of the feedback.Three hundred and twenty eight employees of a prominent South African company gave an indication of the levels of self-efficacy, learning goal orientation, organisational cynicism and integrity of upward feedback in the organisation. Statistical testing carried out on the resulting data then gave an indication of the relationships between the above-mentioned attributes or variables.It was found that there is a positive relationship between self-efficacy and upward feedback integrity, a positive relationship between learning goal orientation and upward feedback integrity and a strong negative relationship between organisational cynicism and upward feedback integrity. These results confirm that organisations can promote the attributes of self-efficacy and learning goal orientation in their employees without fear of jeopardising integrity in their upward feedback process. Conversely, the amount of organisational cynicism must be reduced wherever possible as it acts against the upward feedback mechanism. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

Methods of designing multivariable feedback control systems based on system eigenvalues and matrix diagonalization are discussed. It is shown that these methods allow single-variable graphical analysis and design techniques to be applied to multivariable systems. The experimental determination of system eigenvalues is shown to be feasible. The suitability of these methods in conjunction with simulation studies for investigation and design purposes is also shown. A simulated two-axis tracking system is used to compare the eigenvalue method and the diagonalized method. The eigenvalue method is applied to a system of four parallel-operated synchronous machines and graphical methods of stability investigation are discussed. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In many control, data-processing, and communication systems, sampling is an inherent part of the system. If the time-continuous input signal is nonbandlimited, and noise is introduced in the system, an unavoidable error exists between the actual reconstructed signal and the desired time-continuous output signal. This error can be reduced by the suitable choice of prefilter prior to sampling and by the suitable choice of post-filter for reconstructing the time-continuous signal from the samples. In this thesis, an algorithm for determining the jointly optimal pre and post-filters which minimize the frequency weighted mean-integral-squared error of the system is presented, and the validity of the algorithm is proved. In the analysis, no restrictions are placed on the input signal spectrum or the noise spectrum, and the cross-correlation between signal and noise is taken into account. Applications of the optimization algorithm to M-channel time-multiplexed PAM systems, PCM systems with digital channels errors, and DPCM systems are considered. Performance characteristics, showing mean-squared error and inband signal-to-noise ratio versus channel signal-to-noise ratio, are determined explicitly for optimal pre and postfiltered PAM and PCM systems with first-order Butterworth input spectrum. These characteristics are compared with those of PAM and PCM systems which use suboptimal filtering schemes and with the optimal performance theoretically attainable. Performance characteristics, showing mean-squared error versus channel capacity, are also determined for PAM, PCM, and DPCM systems when the systems parameters are optimized to yield the least mean-squared error for a given channel capacity. Because of the subjective nature of speech, the effect of pre and postfilters in PAM, PCM and DPCM communication systems for speech transmission is studied by simulation methods and evaluated with subjective tests. Weak noise pre and postfilters (WNF), which yield virtually the same performance as optimal pre and postfilters, are considered in the subjective evaluation, in addition to lowpass pre and postfilters (LPF). The digital simulation facilities and the subjective testing methods are described, and the subjective results interpreted. It was observed that no significant subjective improvement resulted when WNF were used in place of LPF in PAM and DPCM systems. In PCM systems, significant differences in WNF and LPF subjective performances could exist. Using the analytical results, an explanation for the subjective behaviour is presented. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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A thesis submitted to the Faculty of Engineering and the Built Environment in fulfilment of the requirement for the degree Doctor of Philosophy, University of the Witwatersrand, Johannesburg, 2019 / The design of feedback stabilizing controllers is an essential component of control engineering theory and practice. A large part of the modern literature in control theory is devoted to coming up with new methods of designing feedback stabilizing controllers. This sustained interest in answering the question \how to design a feedback stabilizing controller" has not been accompanied by equal interest in the more existential and fundamental problem of \when is a system stabilizable by feedback". As such the theory of control Lyapunov functions still remains the most general framework that characterizes stabilizability as a system property. This approach however simply replaces one elusive and di cult concept (i.e stabilizability) with an equally diffcult concept, the existence of control Lyapunov functions. In this thesis we analyse control system stabilizability from the perspective of control system quotients which are generalized control system reductions, the focus being on the propagation of the stabilizability property from the lower order quotient system to the original system. For the case where the quotient system is a linear controllable system we prove that propagation of the stabilizability property to the original system is possible if the zero dynamics of the original system are stable. A novel way of constructing the zero dynamics which does not involve the solution of a system of partial differential equations is devised. More generally for analytic non-linear systems given a stabilizable quotient system, we develop a new method of constructing a control Lyapunov function for the original system, this construction involves the solution of a system of partial di erential equations. By studying the integrability conditions of this associated system of partial differential equations we are able to characterize obstructions to our proposed method of constructing control Lyapunov functions in terms of the structure of the original control system. / PH2020

published_or_final_version / Electrical Engineering / Master / Master of Science in Engineering