It is time for a library that does not hold all the knowledge. A library that rather deals with very well thought out collections, where you cannot check on the internet before you arrive and find out exactly where the book you want is placed, where you will actually have to browse, to find it, work for your accomplishment and there by add value to it. Perhaps find something different, something you weren’t specifically looking for. A library with a carefully changing selection of knowledge, like curating books.

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In areas supplied by underground transmission systems load division among several parallel connected cables may not be satisfactory. Phase-angle-connected TCUL transformers may be used to provide the phase shift necessary to equalize the cable loading and to provide voltage regulation at the load. A means for automating the TCUL adjustments to provide satisfactory current balance and voltage regulation was sought. This problem was attacked by first expressing the system performance (the unbalance of cable currents and load voltage magnitude) in terms of a system performance function. An optimal policy of control is defined as the selection of the particular TCUL transformer which provides the greatest improvement in the system performance. A negative gradient optimization routine is used to determine the required adjustment. A derivation of the adjoint network relationships for a phase-angle-connected transformer is given. These relationships provide a means for readily determining the gradient of the performance function. This approach is developed to provide a means for continuously monitoring and automatically controlling the system performance. A discussion of two ways in which this approach might be implemented physically is given. The optimally adjusted TCUL controller was incorporated in a digital computer model of a small underground power system. Simulated operation of the system under widely varying load conditions demonstrated the ability of the controller to maintain very small cable current unbalance while simultaneously holding voltage variations to +2.9 percent of nominal. A significant advantage of this approach is that the optimal sequence of adjustments required to restore the system to a satisfactory level of performance may be obtained and verified without making any actual adjustments to the TCUL transformers. This is important from a maintenance point of view. A possible disadvantage of the method is that an accurate model of the system must be available. / Ph. D.

Stress can have a significant effect on the stability of pillars. To get an accurate picture of pillar stability, information is needed not only on the initial stress magnitude and distribution but also on all subsequent stress changes. Sonic methods have the potential to be among the fastest, most economical and least destructive means of stress measurement. Wave propagation velocity has long been applied to the investigation of the upper mantle and crust stress. Recently, it has also been applied to rock burst prediction and mine site investigations. Another parameter for investigating stress in rocks is the attenuation coefficient. Attenuation has been observed to be more sensitive to stress changes than wave velocity; however, the measurement of attenuation is more difficult than that of wave velocity. In this study, the mechanism of sonic attenuation in rock is reviewed. Both the velocity and the attenuation of sound waves in five different rock types under various stress levels were examined in the laboratory. It was found that the relationship between the velocity ratio and stress and that between the attenuation ratio and stress, for a specific rock type, can be expressed by simplified second order polynomial equations. / Master of Science

Submitted in fulfillment of the requirements of the Degree of Magister Technologiae: Civil Engineering, Durban University of Technology, 2013. / The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

The thesis highlights the literary-critical work of Jan Lopatka in the context of his personal library. It is a literary-historical and critical description of his work by characterizing and defining thematic blocks, which Lopatka systematically pursued in his personal library. It centers on a comparison of the significance of his work and pinpoints defined blocks in Lopatka's library fund and their significance in his literary criticism. Based on a complete inventory of his personal library (prepared by the author of this thesis) and its knowledge, research characterizes his work mainly from this perspective. Attention will also be paid to manuscripts, typescripts and notes in his books.