Numerical analysis of evapotranspiration and its influence on embankments

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The use of mixed thiol collectors in the flotation of Nkomati sulphide ore

Includes bibliographical references.Mixtures of collectors are widely used in sulfide and platinum group mineral (PGM) flotation, and a range of performance benefits have been reported for many different systems. An increase in paymetal recovery and grade as well as increased rates of recovery at lower collector dosages has been observed when single collectors are replaced with multi-collector suites. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics and increased recovery of middling or course particles. However, the mechanism of action of such collector suites is not clearly understood. Candidate selection of mixed collector suites is currently based on experience and contextual knowledge. The overall objective of this study was to experimentally identify a three component collector suite consisting of conventional collectors which could enhance the metallurgical performance of Nkomati nickel-copper sulfide ore. A three component collector suite consisting of sodium isobutyl xanthate (SIBX), sodium ethyl xanthate (SEX) and either sodium ethyl dithiophosphate (DTP) or sodium ethyl dithiocarbamate (DTC) was used. The scope of this work was confined to the use of xanthates, DTC’s and DTP’s since they are in common use in industry, are supplied over a relatively low price range and have shown potential performance enhancements when used as mixtures. The standard University of Cape Town (UCT) batch flotation procedure was used in this investigation and changes in electrochemical potential were monitored as collector was added to the flotation cell. It is hypothesised that the benefits of collector mixtures are only evident at low dosages, thus, dosages were carefully controlled. The study aimed to determine whether benefits of collector mixtures were dominant in the pulp or froth phase and suggest a possible mechanism of action

Adverse drug reactions reporting at a referral hospital in Zimbabwe

To establish factors influencing voluntary reporting of adverse drug reactions among health workers. A second objective was to establish the level of awareness on adverse drug reaction reporting and attitudes towards the voluntary adverse drug reaction reporting scheme. Design: Cross sectional descriptive study. Setting: Parirenyatwa Hospital, a major referral and teaching hospital in Harare, Zimbabwe. Subjects: 200 health professionals randomly selected from various departments. Main Outcome Measures: Number of health workers reporting adverse drug reactions; awareness of the adverse drug reaction reporting scheme

Effects of plant roots on soil-water retention and induced suction in vegetated soil

Plant evapotranspiration (ET) is considered to be a hydrological effect that would induce soil suction and hence influence the stability of geotechnical infrastructure. However, other hydrological effect, such as the change of soil water retention curve (SWRC) induced by roots, is generally ignored. This study aims to investigate and compare the effects of root-induced changes in SWRC with the effects of ET on suction responses in clayey sand. Two series of laboratory tests together with 21 numerical transient seepage analyses were conducted. A tree species, Schefflera heptaphylla, which is commonly used for ecological restoration in many subtropical regions, was selected for investigation. In order to consider any effects of tree variability on induced suction, six tree individuals with similar age were tested with and without the supply of light. It is revealed that under dark condition when ET was minimal, vegetated soil could induce higher suction than bare soil by 100% after subjecting to a wetting event with a return period of 100 years. This may be explained by the increases in the air-entry value and the size of hysteresis loop induced by roots. Water balance calculation from the numerical analyses shows that even under the supply of light, the amount of ET was only 1.7% of the total volume of water infiltrated. This means that during the wetting event, the contribution of root-water uptake to induced suction in vegetated soil was relatively little, as compared with the effects of root-induced change in SWRC. (C) 2015 Elsevier B.V. All rights reserved

Failures in transport infrastructure embankments

To ensure that road and rail transport networks remain operational, both highway and railway embankments require continual maintenance and renewal to mitigate against ongoing deterioration and repair any sections damaged by realised failures. This paper provides a review of recent developments in the understanding of highway and railway embankment degradation and failure. Failures due to pore water pressure increase, seasonal shrink-swell deformation and progressive failure are considered. The material composition and construction of highway and railway embankments differ, which influences the dominant type and timing of embankment failure. There is evidence for highway embankment failures induced by pore water pressure increase, but not seasonal deformation and progressive failure. Some railway embankments are susceptible to pore water pressure increase, seasonal shrink-swell deformation and progressive failure due to the age and nature of the dumped clay fill used in their construction. The approaches used to measure and explore embankment failure mechanisms are compared and discussed. Field observations have been used to understand pore water pressure increase and seasonal shrink-swell deformation in embankments, while the investigation of progressive embankment failure has mainly utilised physical and numerical modelling approaches. Further field and laboratory investigation is required before the rigorous analysis of embankment failure can be routinely undertaken. However, progress is being made to empirically identify and evaluate the various risk factors affecting transport infrastructure embankment failure

Expert system for the integrated approach to design and construction of ground bearing industrial floors

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN 011323 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Does Zimbabwe view social security as a right?

This research examines the attitude that Zimbabwe portrays towards the protection, promotion and enforcement of the right to social security. Zimbabwe did not have a Constitution that provided for the realisation of the right to social security before 2013. With the enactment of the 2013 Constitution, many people now have a chance to enjoy economic, social and cultural rights (including social security) which ordinarily was not possible in the past. Provision of the right to social security plays a pivotal role by assuring human dignity for people when they are faced with circumstances such as the deteriorating and unpredictable economic situation in Zimbabwe in recent years. This study uses academic textbooks, journals, legislation, international treaties, newspaper reports and other sources of literature to analyse Zimbabwe’s outlook on social security and examines the structures, policies and institutions put in place to enforce the right to social security. The Constitutional provisions for social security are also analysed in the light of international instruments’ provisions of social security to find out if they are adequate and effective in the protection and promotion of social security in Zimbabwe. The study also examines the national polices; the national commission for human rights and the courts to determine their efficacy in their administration of the right to social security. The Constitution of Zimbabwe states that when provisions of the declaration of rights and any legislation such as the provisions for the right to social security are being interpreted, international law and all treaties and conventions that Zimbabwe is a party to must be taken into consideration. Thus, in this study the application and influence on the enforcement of the right to social security by international law and all the treaties and conventions that Zimbabwe is a party to, are scrutinised. Budgets mirror the government’s values and can be reflective of the attitude that a State has towards a priority. That is why the study also examines the budget allocation and spending patterns of Zimbabwe towards the protection and promotion of the right to social security.Mini Dissertation (LLM)--University of Pretoria, 2019.Public LawLLM (Socio-Economic Rights)Unrestricte