The work deals with optimization of the technological properties of cement-sand mixtures. The main objective is to find the correct mixture of the individual components which contribute to the rapid solidification of the mixture, hence shorter dismantling. The content is also of a method of measuring and recording during the plasticity of the mixture. Also assessment of the velocity of hydration heat cement mixture in the initial stage of the solidification process in the course of the strength properties of the mixture. To assess these phenomena was used calorimetric method used for measuring hydration heat cement mixture. Further measurements plasticity mixtures and mechanical and physical methods for measuring the compressive strength with the help of a measuring instrument LRU-D.

MENVSC / Department of Geography and Geo-Information Sciences

Bibliography: pages 144-155. / Dunes are an integral part of the Walvis Bay environment. Their dynamics significantly influence the functioning of the coastal system and have major implications for both the ecological and socio-economic environments. In light of residential, commercial and industrial requirements for the Walvis Bay area, dune encroachment needs to be seriously considered in the future planning of land-use and resource utilisation. The overall objective of this report, therefore, is to provide a better understanding of the dominant role dunes and sand drift play in the study area and in so doing promote the more judicious future planning and management of the region. In order to achieve this aim, several specific objectives were addressed, these being: to identify and clarify all dune types occurring in the study area, and discuss the geomorphological and ecological characteristics of each; to provide an analysis of the long-term stability of dunes in the Walvis Bay area by means of aerial photograph interpretation; to highlight all factors that contribute to dune encroachment and to assess the ramifications of this movement upon the ecological and socio-economic environments; * to emphasise elements that need to be considered with any future planning of land-use and development; * to review dune management practices in the Walvis Bay area and provide recommendations for the more effective management of the system in the future.

The work deals with optimization of the technological properties of cement-sand mixtures. The main objective is to find the correct mixture of the individual components which contribute to the rapid solidification of the mixture, hence shorter dismantling. The content is also of a method of measuring and recording during the plasticity of the mixture. Also assessment of the velocity of hydration heat cement mixture in the initial stage of the solidification process in the course of the strength properties of the mixture. To assess these phenomena was used calorimetric method used for measuring hydration heat cement mixture. Further measurements plasticity mixtures and mechanical and physical methods for measuring the compressive strength with the help of a measuring instrument LRU-D.

Asian countries are urbanizing at an unprecedented rate, which has led to significant demand for sand. While sand mining fuels infrastructure development, creates livelihoods, and stimulates local economic activity, it also drives a series of environmental and socio-economic consequences which cannot be ignored. These include erosion, the destruction of habitats and loss of biodiversity, the deterioration of traditional livelihoods, forced displacement of communities, and damage to homes and infrastructure. On the one hand, this thesis uses mixed methods to study the multifaceted impacts of sand mining along the Red River in China, near the Vietnamese border. On the other hand, using qualitative methods, it explores how these impacts unfold along the Mekong River in Cambodia, near Phnom Penh. Using a political ecology approach, it identifies the actors involved in sand mining, their motives, and their impacts on the environment and local communities. The extractivism framework is used to describe sand mining activities and practices. In doing so, this thesis contributes to the literature on the understudied sand mining industry and its far-reaching impacts.

Doctor of Philosophy / Department of Entomology / Marcelo Ramalho-Ortigao / The emergence and reemergence of vector-borne diseases pose significant threats to humans and other animals worldwide. Although vector control relies mostly on insecticides, the emergence of insecticide resistance urges for the development of new strategies to control the spread of such diseases. For sand fly-transmitted leishmaniasis, Transmission Blocking Vaccines (TBV) may constitute a feasible strategy to impair Leishmania transmission from infected to uninfected vertebrate hosts. Moreover, sand fly saliva-based vaccines represent an alternative or complementary approach as these vaccines protect different mammalian hosts against Leishmania. Based on the potential use of sand fly molecules as vaccines against leishmaniasis, we assessed the potential of Phlebotomus papatasi midgut secreted proteins as TBV candidates and the expression variability of sand fly salivary gland genes. Regarding the TBV approach, we took advantage of the RNA interference (RNAi) technique to evaluate the effects of knocking down P. papatasi midgut-specific genes on Leishmania major development within the sand fly midgut. Whereas peritrophin 1 (PpPer1) knock down led to increased Le. major load by 39%, knocking down chitinase 1 (PpChit1) reduced Le. major load in P. papatasi midguts by 63%. Thus, our data strongly suggest that PpChit1 constitutes a potential target for TBV approaches against Leishmania transmission in endemic areas. Concerning protective vaccines based on salivary gland secreted proteins, we searched for expression polymorphism in selected salivary gland genes in natural and colonized populations of P. papatasi. Significant differences in salivary gland gene expression were not only exhibited in P. papatasi specimens collected in different geographic habitats but also seasonal difference in gene expression was displayed by specimens belonging to the same population. As antigen dose is an important component of immune responses, different doses of salivary protein inoculated into host skin may interfere with vaccine protection. Thus, the efficacy of sand fly saliva-based vaccine upon exposure to different salivary protein doses must be evaluated before deployment in endemic areas. Our data also ruled out some biotic factors as responsible for fine-tuning the expression of such genes. Overall, this dissertation makes significant contribution to the development of sand fly-based vaccines against leishmaniasis.

Master of Science / Department of Geology / Matthew Totten / Due to their high resolution and established success rates, 3D seismic surveys have become one of the most important tools in many hydrocarbon exploration programs. Basic interpretation of seismic reflectors alone, however, may result in inaccurate predictions of subsurface geology. Historically, seismic attributes have played a particularly important role in the characterization of the lithological and petrophysical properties of hydrocarbon reservoirs in Kansas channel fill lithofacies. Integration of an analysis based on post-stack seismic attributes may drastically reduce the chances of drilling in unsuitable locations. Previous theses have focused on establishing a suitable 3D seismic attribute analysis workflow for use in the determination of hydrocarbon production potential in areas of Ness County, Kansas, USA (Abbas, 2009; Phillip, 2011). By applying a similar workflow in the analysis of additional 3D seismic and well log data obtained from a nearby area in Ness County, and comparing those results to existing borehole and production data, this study seeks to test the hypothesis that seismic attribute analysis is a crucial component in the delineation of heterogeneous reservoir stratigraphy in Kansas lithologies. Time-structure maps, in addition to time slices of several 3D seismic attributes including amplitude attenuation, acoustic impedance, and event continuity all seem to indicate that five previously drilled dry wells within the study area were outside the boundary of a meandering, Cherokee sandstone body of potential reservoir quality. Additionally, comparisons of the results of this research to previous studies conducted in Ness County have provided an opportunity to assess, and potentially contribute to, paleodepositional interpretations made through the utilization of a similar workflow (Raef et al., in press). The results of this study seem to support a broadly NE-SW trending meandering channel system, which is in agreement with the interpretations of Raef et al., and the findings of Ramaker (2009).

Call number: LD2668 .T4 1965 A67 / Master of Science

Pipelines used for the transportation of oil and gas products offshore are often buried beneath the seabed for protection from mechanical damage and for thermal insulation. During high temperature and high pressure operations, these pipelines are susceptible to resurfacing behaviour known as upheaval buckling, a structural response that is strongly influenced by the resistance of the surrounding soil. Despite much previous research on pipe uplift, the influence of the initial soil state – particularly in loose and liquefiable soil conditions – on the uplift resistance and corresponding buckling behaviour of the pipe is not well understood. This thesis presents research that examines the implications of these backfill conditions in the context of the global behaviour of the pipeline. The work consists of plane-strain monotonic uplift experiments focusing on density, rate, and stress level effects on the initial pipe-soil response. This is followed by numerical modelling of the global buckling behaviour using the experimental data as inputs. Finally, plane-strain cyclic experiments examine the possibility of progressive upward displacements over a number of cycles causing eventual upheaval buckling. A key finding from the uplift tests is that very loose backfill conditions may result in a localised flow-around failure mechanism, associated with lower peak resistance and a softer force-displacement response than with the sliding block mechanism that is typically assumed. This leads to lower peak buckling loads/temperatures than those predicted by current design guidelines. High quality data from both the monotonic and cyclic experiments was used to assess and suggest improvements to design guidance for these conditions.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Geotextiles perform a number of functions in various applications in civil engineering practise. It is often cost effective and more environmentally friendly versus conventional construction methods. One of the main functions of a geotextile is filtration whereby the geotextile is expected to hold back the soil particles and simultaneously has to allow sufficient water to pass through it. Soils are all different and can be problematic when it comes to designing geotextile filters. One such problematic soil is encountered in KwaZulu- Natal, situated along the east coast of South Africa. The Berea sand is problematic as it can highly variable in its engineering properties over a small area. Geotextiles are becoming more and more common practice in South Africa and little is known about the filtration performance of commercially available geotextiles in conjunction with Berea sand. Local guidelines that are available are out of date and do not provide enough information to assist design engineers in decision making. Many international guidelines are available and it is difficult to choose which one is best suited to Berea sands. This primary objective of this study is to investigate the filtration performance of four variants of commercially available geotextiles and three variants of Berea sand. The applicability of some of the international filter design criteria will also be assessed. The soil to geotextile compatibility testing was carried out as per ASTM D5101 (2006) - Standard Test Method for Measuring the Soil-Geotextile System Clogging Potential by the Gradient Ratio. In total 12 permutations were executed. The results showed that only 5 test permutations met the gradient ratio and permeability criteria. The test results also conclude that the permeability is just as important as the gradient ratio. Thick geotextiles should be considered when used as filters in Berea sands. The available international geotextile filter design criteria were assessed and all showed poor correlation between laboratory results and suggested criteria. Designing geotextile filters in conjunction with Berea reds is challenging and it is recommended that design engineers perform laboratory performance testing in conjunction with their designs. / AFRIKAANSE OPSOMMING: Geotekstiele verrig vir 'n aantal funksies in verskeie programme in die siviele ingenieurswese praktyk. Dit is dikwels meer koste-effektief en omgewingsvriendelik, teenoor konvensionele konstruksie metodes. Een van die belangrikste funksies van 'n geotekstiel is filtrasie, waardeur van die geotekstiel verwag word om van die grond terug te hou, en gelyktydig genoeg water daardeur te laat vloei. Grond verskil en dit kan problematies wees wanneer dit kom by die ontwerp van geotekstiel filters. Een so ‘n problematiese grond kom voor in KwaZulu-Natal, geleë langs die ooskus van Suid-Afrika. (Die) Berea sand is problematies, want dit verander geweldig baie ten opsigte van ingenieurseienskappe oor 'n redelike klein area. Gebruik van geotekstiele word al hoe meer ‘n algemene praktyk in Suid- Afrika, terwyl min bekend is oor die filtrasie prestasie van kommersieel beskikbare geotekstiele in samewerking met Berea sand. Plaaslike riglyne wat beskikbaar is, is verouderd en onvoldoende inligting is beskikbaar aan ontwerpingenieurs vir besluitneming . Baie internasionale riglyne is beskikbaar en dit is moeilik om te besluit watter een die beste van toepassing is vir Berea sand. Die doel van hierdie studie is om die filtrasie prestasie van vier modelle van kommersieël beskikbare geotekstiele en voorbeelde van drie soorte Berea sand te ondersoek. Die toepaslikheid van 'n paar van die internasionale filter ontwerp kriteria sal ook beoordeel word. Die toetsing van grondverenigbaarheid met geotekstiel is uitgevoer soos aangedui in ASTM D5101 (2006 ) – Standaard Toets Metode vir die meet van die grond-Geotekstiel verstopping potensiëel deur die gradient verhouding. In totaal is 12 permutasies uitgevoer. Die resultate het getoon dat slegs 5 toetspermutasies beide gradiënt verhouding en permeabiliteit kriteria bevredig het. Dikker geotekstiele word ook aanbeveel vir gebruik as filters in Berea sand. Van die toets resultate kan ook afgelei word dat die permeabiliteit net so belangrik soos die gradiënt verhouding is. Beskikbare internasionalegeotekstiel filter ontwerp kriteria is nagegaan en al die metodes het swak korrelasie tussen laboratorium resultate en die voorgestelde kriteria getoon. Om geotekstiel filters in samewerking met Berea Reds te ontwerp is 'n uitdaging en dit word aanbeveel dat ontwerpingenieurs laboratorium prestasietoetsing in samewerking met hul ontwerpe uitvoer.