Bibliography: leaves 93-94. / The coplanar line has been used very successfully as an element in microwave circuits. Small size, high Q-factor, and accurate reproduction, are some of its many advantages. The coplanar transmission lines discussed in this report, are targeted at liquid level measurement, and are typically 30 cm. long. Their operating frequencies are consequently much lower than those of microwave coplanar waveguides, but they have common advantages. The factor which separates the coplanar line from similar liquid level sensors, is that it makes use of the electrical component of the electromagnetic fringe field, setup between its inner conductor, and the surrounding ground plane. The line is effectively a sharply tuned resonator, incorporated as the frequency controlling element of an electronic oscillator. The output frequency falls as a dielectric material penetrates the fringe field. An impressive sensitivity is accomplished by using very thin conductors, thereby ensuring that the fringe field energy is maximised. The most important feature of this sensor is its ability to operate non-intrusively when used with non-conducting vessels, or if employed in a metal tank, the unit can be encased in a dielectric material where the line is non-contacting (the liquid does not penetrate the unit). This combined with its excellent mechanical and electrical stability, and an accuracy better than 1 percent, makes the coplanar line a strong competitor in the field of liquid level measurement. The research began with a theoretical approach, and used lines machined from an Aluminium plate for characteristic impedance measurement. An empirical relation between the gap width, the line thickness, and the characteristic impedance of the line is presented. To assist with the design of the sensor, a lumped capacitance model of the line was developed. Various geometries were tested, and modified until a near linear response to water level was achieved. An advanced engineering model of the level sensor has been developed, which incorporates a stable digital output display, user calibration from the line's end points, and temperature compensation. A T-shaped line, which concentrates the field around its open end, was used for other applications such as, evaporation monitoring, measurement of slurry settlement, and to observe the effect of acids, bases, and salts in water. Various applications of the different coplanar line designs are proposed.

This thesis concerns itself with the development of a real-time automatic Network Analyzer measurement system based on Hewlett Packard's manual HP8410C. The major limitation in non real-time systems is the time required to perform a measurement. Real-time systems have greater measurement speed than their non real-time counterparts, but are also generally less accurate. The main objectives of the thesis are to survey literature on high frequency measurements, to develop hardware and software for a real-time Analyzer and to perform tests with the system.

Includes bibliography. / A instrument has been developed for measuring the velocity of solid particles adjacent to the pipe wall in a solids-liquid pipeline. It has been based on the Doppler shift principle and employs ultrasonic methods for detecting the bed-load particle velocity. Its application is in the mining industry for measuring the bed-load velocity of high concentration slurries such as in tailings and backfill hydraulic pipelines. Analyses have been conducted to investigate methods for increasing the accuracy of detecting the bed-load particle velocity. These methods have been implemented in the design of the transducer and the electronic circuitry. The system was tested using a simulation test-rig, hydraulic test-loops and at two industrial mining locations.

Includes bibliography. / An investigation into the analysis of Digital Microwave Radio Paths was conducted. The causes and effects of multipath fading on the propagation of microwave signals are of particular interest here. A study is made of the theory of link engineering, including an examination of fading and distortion, and the instrumentation used in the analysis of link performance. Multipath fading, the different categories, as well as the causes and effects thereof, are reviewed. The Tellurometer Method of distance measurement is described and its suitability to path analysis discussed.

Includes bibliographical references. / On-line measurement of the moisture content of process streams in a mineral processing plant is vital for their efficient operation. Although many industrial moisture meters are available, most of these were designed to determine the moisture content of low density, fine grained, uniformly surfaced and low resistance materials. Consequently these meters operate poorly on mineral treatment plants as the measured material, rock, is dense, uneven and consists of mixtures of various minerals. A literature survey revealed that of the many methods available, only three techniques could be used for on-line moisture determination in mineral processing operations.These were microwave attenuation, phase and frequency techniques.

Includes bibliography. / Microwave measurement techniques have found many industrial and commercial applications. This measurement potential of microwaves, together with observations that different minerals show different microwave heating characteristics, suggests the possibility of applying microwave techniques to various forms of mineral analysis. Simple, low cost, on-line mineral analysis techniques are of interest to the mining industry. The objectives of this research project were to cover the background theory of microwave interaction with minerals and to investigate different microwave measurement techniques that could possibly be applied to mineral measurement. Measurements were then to be performed on selected minerals in order to observe any differences between them. Finally, to comment on the feasibility of using microwave measurement techniques for the differentiation, identification and analysis of minerals.

Includes bibliographical references. / The AIDS virus has been identified in breast milk which is donated by expectant and recently delivered mothers in maternity hospitals). In maternity hospitals, where the facilities exist for the treatment of pre-term infants, breast milk is collected from mothers premature even those who have not delivered premature babies) and it is used in its raw state to feed the children. The possibility of some of these mothers being infected with the AIDS virus is high in Third World countries. The premature infants have to be fed with breast milk as they are at risk of being infected if fed with commercial milk formulas. Commercially available milk sterilizers are available in Europe but they are very costly.

Bibliography: leaves 185-187. / Massflows on conveyor belts need to be measured in various process streams in mineral extraction processes to ensure good plant management. Conventional weightometers are, however, too expensive to allow a widespread installation in these processes. This study investigates more economic means to measure the massflow on horizontal conveyor belts. A deterioration of accuracy resulting from an instrument using this technique is expected, but the advantages of being able to instrument entire plants is very attractive. The study uses a model a whereby the kinetic energy of the belt system is determined during a perturbation to the system. From this the massflow can be determined.

Bibliography: leaves 115-116. / Microwave ovens have been available for domestic cooking since 1956. This method of heating is very efficient compared to conventional cooking methods. As a result many applications have arisen particularly in the field of analytical chemistry. Most routine analysis of biological and chemical samples by atomic absorption spectroscopy (AAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) involves the time consuming operation of digesting the samples in acid on a hot plate. However, much time saving has been demonstrated by the use of microwave digestion, and successful digestions have been achieved in 10% of the time required for traditional methods. The first digestions using microwave heating were performed in open vessels. However many problems were identified.

Bibliography: leaves 155-160. / The ultimate purpose of this thesis is to compare and evaluate. South African poletop designs for 11kV and 22kV rural distribution lines. However, a frame of reference is first established from the literature and from construction practice before the analytical stage is tackled. In 1989, when the work for this thesis was started, it was quite apparent that there existed a proliferation of configuration designs for rural overhead lines at 11 kV and 22kV in South Africa. The electricity supply industry did not use a universal configuration. Eskom supplied over 97 of South Africa's electricity in 1990 (Eskom, 1990). It was also operating 160 280km of lines at 22kV and below in that year and was largely responsible for this situation. Local supply authorities or distributors S!JCh as municipalities either bought components from Eskom or used an Eskom design, or developed their own designs internally or via consultants. In any event, the designs they used are not considered to be a significant portion of the total. Historically, Eskom developed on a strongly regionalised basis, the separate Undertakings joining up (electrically) to form the national grid in 1973. Prior to 1985 there were six Regions distributing the electricity generated by the power stations. Each Region developed its own designs, independently or based on designs imported from Britain.