abstract: Drainage flow of a viscous compressible gas from a semi-sealed narrow conduit is a pore-scale model for studying the fundamental flow physics of fluid recovery from a porous reservoir without using fluid injection. Thermal effect has been routinely neglected for these flows in the traditional petroleum engineering literature. Since the motion is entirely driven by volumetric expansion, temperature change always accompanies the density change. This thesis examines such thermal effects on the drainage flow. Thermal drainage flow is first studied by simultaneously solving the linearized continuity, momentum and energy equations for adiabatic walls. It is shown that even in the absence of an imposed temperature drop, gas expansion induces a transient temperature decrease inside the channel, which slows down the drainage process compared to the isothermal model and Lighthill’s model. For a given density drop, gas drains out faster as the initial-to-final temperature ratio increases; and the transient density can undershoot the final equilibrium value. A parametric study is then carried out to explore the influence of various thermal boundary conditions on drainage flow. It is found that as the wall transitions from adiabatic to isothermal condition, the excess density changes from a plane wave solution to a non-plane wave solution and the drainage rate increases. It is shown that when the exit is also cooled and the wall is non-adiabatic, the total recovered fluid mass exceeds the amount based on the isothermal theory which is determined by the initial and final density difference alone. Finally, a full numerical simulation is conducted to mimic the channel-reservoir system using the finite volume method. The Ghost-Cell Navier-Stokes Characteristic Boundary Condition technique is applied at the far end of the truncated reservoir, which is an open boundary. The results confirm the conclusions of the linear theory. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020

This dissertation investigates the latent potential of the mining belt in Johannesburg through a regenerative theory, by placing a catalytic intervention which respects the heritage of the mining belt, with a focus on the ecology and the socio-economic value of the land has, thereby turning a liability into an asset. This intervention is seen as the first point of acupuncture in a long rehabilitation process and focuses on using this space to deal with context specific issues. The proposed intervention will investigate the potential of architecture to activate a harmed dormant space in the realm of a decentralized city node. It recognizes the potential of the currently fragmented mining belt to become a gateway to the South of Johannesburg, and embraces an opportunity to restitch the urban fabric. / Mini Dissertation MArch(Prof)--University of Pretoria, 2018. / Architecture / MArch(Prof) / Unrestricted

Environmental art: Art relating to the individual’s response, understanding and interest towards the land, including art forms such as Land/Earth art as well as more sensitive art forms such as Eco-art, focussed more on the earth’s natural processes. Exploitation: The exploitation of mineral resources is closely associated with progress and success, but also that of benefiting from something at the cost of something else, in this case exploiting gold at the cost of the ecology of the natural environment. Gold mining industry: The labour-intensive activity of removing gold from ore, mined from deep within the earth’s crust through a system of shafts and stopes. Installation art: Refers to what is contested as being a medium or process of art, whereby three-dimensional works are designed to influence the perception of a space, often site-specific, within an enclosed space or the outside environment, temporary or permanent. The found object or existing object is often used in installation art for its intellectual value. Inter-and-trans-disciplinary approach: The utilisation and collaboration of different disciplines as a means to find a solution to a (environmental) problem. Landscape: A cultural construct, referring not to physical topography, but to an aesthetically processed vision of the environment, mostly arranged and framed by an artist. Post-industrial environment: Referring to an environment, man-made or natural in a state preceded by industry. Often these environments are characterised as polluted and derelicts sites left behind by large mining industries. The gold-mining industry on the Witwatersrand, is characterised by massive tailings dumps and slimes dams. Resource curse: A term coined by artist Jeannette Unite, describing the phenomenon of extreme poverty co-existing with valuable minerals in the same region, especially prevalent in Africa. Technospasm: A term conceptualised by archeo-metallurgist Duncan Miller, as the unsustainable rate of non-renewable mineral resources extraction. South Africa is known to the world for its vast deposits of valuable minerals, of which gold has played a seminal role in the development of the country’s economy. What is left after more than 120 years of mining for this precious metal is a landscape, better described as a derelict post-industrial environment, characterised by pollution and impoverished communities. Environmental degradation caused by mining industries is not unique to the African continent, but is a worldwide phenomenon. Due to the rapid deterioration of environments caused by mining and industry, new environmentalist attitudes became prevalent by the 1970s in the West, seeking change in attitudes towards the land. Along with earth activists, artists also started to question humankind’s destructive relationship towards the land. Apart from the early developments of Land/Earth art during the 1960s, artists have taken on roles of activists, interventionists and collaborators of multi- and interdisciplinary projects since then, in order to remediate and re-cultivate post-industrial sites. Environmental artists find value in what art holistically contributes to society, as opposed to the commodity value of art. While artists in the West significantly progressed in environmentally orientated art, South African artists focused more on responding to the socio-economic conditions induced by the long-standing Apartheid era. Few South African artists have attempted to engage in environmentally-concerned art, especially related to the mining industry. However, Western attitudes towards the land can be derived from South Africa’s landscape depictions since its colonisation by Europeans up to contemporary versions of the South African landscape environment today. This study provides a historic overview of South Africa’s aesthetic relationship with the mining landscape, specifically of the post-industrial sites situated in the Witwatersrand. The aim is to determine the South African artists’ contribution towards developing an environmental awareness, and to call for more artists to take part in visual art forms concerning the disruption of the environment, caused by the mining industry. The study determines the relevance of art as a means to raise environmental issues and whether art may be utilised for post-industrial remediation projects. International examples of Reclamation art projects and its incorporation of science are investigated to find solutions towards contaminated post-industrial sites. These examples are compared to the work of a small number of South African artists who have attempted to engage in the post-industrial mining environment through Earthworks and science The researcher’s own work is discussed to raise awareness of the adverse effects of Acid Mine Drainage (AMD) caused by the gold-mining industry in the Witwatersrand. A body of installation art produced for this degree was displayed in a gallery space, which presented a platform for audience engagement. Through this body of work and through the examples discussed in this dissertation, the researcher urges South African artists to take up the task of moral responsibility towards the environment for the survival of future generations of life on earth. / Dissertation (MA)--University of Pretoria, 2012. / Visual Arts / unrestricted

It is evident that the sea ice cycle, from its formation to its melt, is governed by a complex interaction of the ocean, atmosphere and surrounding continents. Once sea water begins to freeze, physical, biological and chemical processes have implications on the evolution of the sea ice morphology [38]. The distinguishing factor between fresh and sea water ice is brine inclusions that get trapped within the ice pores during freezing. Salt inclusions within frozen ice influence the salinity as well as the physical properties of the sea ice [23]. These brine inclusions form part of a dynamic process within the ice characterized by the movement of brine and phase transition which are the foundation of many of its physical properties [23]. Brine removal subsequently begins to occur due to vertical gravity drainage into the underlying ocean water. This study introduces the application of a biphasic model based on the Theory of Porous Media (TPM) which considers a solid phase for the pore structure of the ice matrix as well as a liquid phase for the brine inclusions, respectively. This work explores the use of the TPM framework towards advancing the description and study of the various desalination mechanisms that are significant in aiding the salt flux into the Southern Ocean. This will foster understanding of brine rejection and how it is linked to the porous microstructure of Antarctic sea ice

Mediastinal pancreatic pseudocyst (MPP) is a rare, but known, complication of both acute and chronic pancreatitis. Most pseudocysts are associated with alcoholic pancreatitis. Recent advances in endoscopic techniques have shown promising results, with reduced chances of infection and recurrence than with percutaneous drainage, but limited availability restricts widespread use. Left gastric artery pseudoaneurysm with mediastinal pseudocyst has not been described in the literature to date. We report a successful resolution of hemorrhagic MPP with embolization of pseudoaneurysm and percutaneous trans-hepatic pseudocyst drainage.

With rising valuation of mineral commodities, mining has been envisioned as a profitable industry regardless of many challenges it entails. This comprehensive review provides the state of knowledge about several aspects of the metal mining industry, including (a) the basic mining processes with reasons for mine closure, (b) the potential environmental and human health impacts associated with mining, (c) the potential techniques for impact mitigation, (d) the latest production statistics for the base and precious metals with identification of currently operational major metal mines for different countries, and (e) how mining activities are regulated in different nations. Finally, the authors provide critical appraisal on the debatable issue of mining and sustainability to stimulate thoughts on how metal mining can be made sustainable, and suggest a path forward.

With rising valuation of mineral commodities, mining has been envisioned as a profitable industry regardless of many challenges it entails. This comprehensive review provides the state of knowledge about several aspects of the metal mining industry, including (a) the basic mining processes with reasons for mine closure, (b) the potential environmental and human health impacts associated with mining, (c) the potential techniques for impact mitigation, (d) the latest production statistics for the base and precious metals with identification of currently operational major metal mines for different countries, and (e) how mining activities are regulated in different nations. Finally, the authors provide critical appraisal on the debatable issue of mining and sustainability to stimulate thoughts on how metal mining can be made sustainable, and suggest a path forward.

In late 1992 coalbed methane became the most significant source of natural gas produced in Virginia. This gas is held within the coal formations adsorbed to the coal matrix. The current well stimulation technology applies a high pressure fluid to the coal formation surrounding the wellbore to induce a series of fractures. The research documented in this thesis investigates several new technologies that could replace or augment the current well stimulation approach of hydraulic fracturing. The application of liquid carbon dioxide, as the stimulation agent was investigated in a series of permeability tests. These measurements were made using a radial flow technique developed specifically for this research project. The results of the tests using liquid carbon dioxide to enhance the permeability of coal samples, to methane gas, indicated a significant increase in permeability of the samples. Comparison to a reference material showed, however, that the increase was of a general nature, not by specific interaction with the coal matrix. Rather, the permeability increase was due to reduced resistance of the borehole skin. Studies of the new, radial flow, permeability measurement approach showed good agreement to a conventional, axial flow, approach for similar sample bedding orientation to the gas flow. The documented experiments also include investigations into the potential for using custom designed nitrocellulose/nitroglycerin/RDX based propellant charges to produce extensive fracturing away from the wellbore. The first series of these experiments concerned the characterization of the burn properties for these propellants and their mixtures. Utilizing an interior ballistics approach, these laboratory small-scale shots were numerically modeled with a program written as a part of this project. Using the small-scale results and the modeled data, a series of large-scale test shots were developed and fired to gain understanding of the scale effects. The small-scale constant volume bomb, and the large-scale vented bomb were both custom designed and fabricated for this project. Comparisons of the laboratory data and modeled predictions show good agreement for both the small and large-scale test series. This work concludes by presenting considerations for utilizing the propellant based well stimulation approach in the water filled wells in southwest Virginia. / Ph. D.

B.A. Etcheverry (4) in his book, Land Drainage and Flood Protection, states that inadequate drainage causes: (1) a public health menace, (2) an animal health menace, (3) lower grade plant life, (4) inadequate soil saturation, (5) lower soil temperatures, (6) shallow root penetration and, therefore, plant suffering in late summer months from effects of drought, (7) poor soil texture and workability, (8) increased surface washing and erosion of land surface, and (9) alkali and saline conditions. Other factors such as poorer roads and highways, decreased tax revenues, etc., might be added to this list. The advantages of adequate drainage are absence of these disadvantages. Many public as well as private benefits are realized from land drainage. The present world situation has brought about a great need for increased food production. Jones, in the July 1952 issue of Agricultural Engineering (13), writes: There is greater need for food and fiber production on United States farms today than ever before. U.S. population has increased 20 million in ten years...an appreciable part of our food supplies must go to feed men in the military service...our present exports require the production ofrom approximately 50 million acres...as a result of these heavy demands, the agricultural surpluses we heard so much about a few years ago are now a myth. It appears that over the U.S. some 30-40 million acres of land are now under cultivation on which crop yields could be increased 50 per cent or more by farm drainage work, an increase which can be obtained without increased demands for machinery, labor, seed, or fertilizer. All that would be required would be a limited amount of construction equipment such as small draglines, bulldozers, and graders. In view of the urgent need for increasing our food supply, it would seem that every effort should be made to provide the necessary critical materials to furnish and maintain the small amount of equipment necessary to carry on an expanded program of farm drainage. Conditions are more favorable economically for drainage than ever before. Land values and food values have both increased considerably.

The presence of moisture in the soil reduces its shear strength. After the rain or snowmelt, the high percentage of moisture in the subgrade of highway, causes the instability resulting into failure of the highway due to high water table. Therefore, it is essential to install a drainage system to remove the excess moisture from the subgrade of highways to avoid its failure. In the present study, six different soil samples have been studied to observe its failure by triaxial shear strength and corresponding moisture content was noted. The tension applied to remove moisture was converted to equivalent drain depth. The relationships were studied between shear strength versus drain depth and moisture content versus drain depth. From these relationships the design drain depth for different types of soils studied was recommended. The present study also suggest that the design drain depth for the highways can be approximated directly using water retention curve.