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A widely discussed philosophical puzzle in contemporary epistemology is the so-called sceptical paradox. Ascriber contextualism has taken centre stage as the anti-sceptical theory that purportedly offers the best solution to the sceptical paradox. Ascriber contextualists Stewart Cohen (1988, 1999) and Keith DeRose (1995) advertise their anti-sceptical theory as the one that exclusively explains and solves it. This is false advertising, however. My thesis, which has been greatly influenced by the critical work of Michael Williams (1991) and Duncan Pritchard (2005), is that the generation of the sceptical paradox depends on whether the epistemologist is an internalist or externalist about knowledge, and that the ascriber contextualist attempt to solve the sceptical paradox rests on a long history of mistakes concerning internalist assumptions made by externalists Fred Dretske (1970) and Robert Nozick (1981). By applying the semantic thesis of ascriber contextualism to epistemology, ascriber contextualists seek to emend the rejection of the closure principle made by these externalists. This rejection came from these externalists mistakenly making internalist assumptions when facing sceptical hypotheses. Unfortunately, ascriber contextualists leave much unfixed, and end up inheriting and suffering from the serious mistake about internalist assumptions that had plagued the epistemologies of these externalists and now infects the ascriber contextualist solution to the sceptical paradox. With the help of hindsight to examine this history and an appreciation of how the adoption of one of these respective views about knowledge makes all the difference for whether the sceptical paradox arises, we come to see that the contextualist solution to the sceptical paradox is unnecessary.

A widely discussed philosophical puzzle in contemporary epistemology is the so-called sceptical paradox. Ascriber contextualism has taken centre stage as the anti-sceptical theory that purportedly offers the best solution to the sceptical paradox. Ascriber contextualists Stewart Cohen (1988, 1999) and Keith DeRose (1995) advertise their anti-sceptical theory as the one that exclusively explains and solves it. This is false advertising, however. My thesis, which has been greatly influenced by the critical work of Michael Williams (1991) and Duncan Pritchard (2005), is that the generation of the sceptical paradox depends on whether the epistemologist is an internalist or externalist about knowledge, and that the ascriber contextualist attempt to solve the sceptical paradox rests on a long history of mistakes concerning internalist assumptions made by externalists Fred Dretske (1970) and Robert Nozick (1981). By applying the semantic thesis of ascriber contextualism to epistemology, ascriber contextualists seek to emend the rejection of the closure principle made by these externalists. This rejection came from these externalists mistakenly making internalist assumptions when facing sceptical hypotheses. Unfortunately, ascriber contextualists leave much unfixed, and end up inheriting and suffering from the serious mistake about internalist assumptions that had plagued the epistemologies of these externalists and now infects the ascriber contextualist solution to the sceptical paradox. With the help of hindsight to examine this history and an appreciation of how the adoption of one of these respective views about knowledge makes all the difference for whether the sceptical paradox arises, we come to see that the contextualist solution to the sceptical paradox is unnecessary.

The aim of this bachelor’s thesis is to discuss, and attempt to confirm, that Ian McEwan’s Atonement (2001) lacks closure. Since the novel has an unreliable narrator who offers her readers several credible endings to her narrative, and who also acts as the fictitious author of the story, unreliability and metafiction are claimed to be the main underlying causes of this deprivation of closure. The discussion in the first section of the analysis is based on the plot development depicted in Gustav Freytag’s Pyramid, and the second part is focused on Victoria Orlowski’s four metafictional characteristics denoting ways in which writers of metafiction transgress narrative levels. The claim is concluded to be partly fulfilled, since Atonement is regarded as lacking closure in terms of narrative structure but not in a philosophical and moral sense.

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It was proposed that a study be done to investigate the problem of relating anxiety to the phenomenon of Gestalt closure. This study problem sought to demonstrate a systematic relationship between Gestalt closure, in terms of accuracy and speed, and possible interaction between levels of anxiety and induction of anxiety.

As a result of the mining that has taken place over the last century in South Africa, many towns and cities have developed around mining hubs, the most significant of these being the city of Johannesburg. Over the years, residential areas have grown around these mine sites, even well after decommissioning of the mining activities. The mining activities left a lasting legacy of derelict mining infrastructure with negative effects on the surrounding environment and community, such as dormant mine shafts, sterilised land and abandoned Tailings Storage Facilities (TSFs). Due to lack of funds, commitment from mine owners and regulators these facilities are often left unrehabilitated, posing negative environmental impacts, including potential health hazards to the surrounding community. This legacy of problems posed by abandoned mines encountered in South Africa is probably unique in scale compared to any country in the world. A significant problem South Africa currently faces is an electricity shortage, especially during the high demand season from the start of June to end of August, when it is winter in South Africa. This period is occasionally associated with so called controlled “load shedding”, i.e. managed power interruptions to prevent overload and subsequent collapse of the electricity supply and distribution network. South Africa is highly reliant on coal-fired power stations for the majority of electricity consumed, which has detrimental effects on the environment due to high carbon emissions. However, a global shift towards renewable energy, as well as South Africa’s energy shortage, has forced the National Energy Regulator of South Africa to encourage greener alternatives. This study is aimed at finding an opportunity to generate more electricity, which is sustainable and with reduced carbon emissions. This study was conducted to determine the financial and practical feasibility of generating energy from the ERGO TSF, near Brakpan Johannesburg, as a post closure land use option. The following options were investigated: • Solar Photovoltaic electricity generation • Pump storage scheme development • A combinations of the above In addition, rainwater harvesting and wind power generation were also considered, but were abandoned early on in the study. From the study it was concluded that a Solar PV plant on top of the ERGO TSF will achieve the highest possible IRR of 10.70% and a power generation capacity of 471.9 MWp. Developing a pump storage scheme at the ERGO TSF can achieve an IRR of 10.27% and generation capacity of 78.2 MW. Combining the two options independently on the same site will result in an IRR of 10.61% and a combined peak generation capacity of 550 MW. If the combined system is required to be independent of the surplus electricity available in the grid an IRR of 10.32% and a combined generation capacity of 550 MW is achievable. From a financial and technical perspective it is considered to be most beneficial to implement only the solar PV plant on top of the ERGO TSF. Construction of a pump storage scheme on TSF is considered to be a challenging undertaking and seeing that its generation capacity is only 17% of that of the solar PV facility on the same ERGO site, it is probably not the optimal solution for utilisation. Solar panels are light weight structures that can easily be installed in large numbers on TSFs with little engineering challenges. / Dissertation (MEng)--University of Pretoria, 2015. / tm2015 / Civil Engineering / MEng / Unrestricted

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Traditionally, pre-cracking has been performed under tension-tension loading, followed by a load reduction scheme to obtain fatigue crack growth rate data in the near threshold regime. These data have been shown to exhibit load history effects due to remote crack closure. An alternative test method has been developed to minimize these load history effects. This test procedure uses compression pre-cracking to initiate a crack, followed by constant amplitude loading to grow the crack to failure. Compression-compression (C-C) loading as a means of forming a starter crack for fatigue crack growth is a relatively new concept. Cracks grown under C-C loading emanate from the notch tip due to a tensile residual stress field formed during the unloading cycle. The subsequent constant amplitude steady-state crack growth is free of load history effects, after crack growth beyond several compressive plastic zone sizes, and therefore will give a better steady-state representation of the near-threshold regime. A more in-depth examination at this phenomenon is performed herein.

From its discovery, crack closure was recognized as a key aspect in understanding the fatigue crack growth process. Considering the condition of plane stress, a vast amount of research has been conducted experimentally, analytically, and numerically to understand the complex process of fatigue crack growth and crack closure. Nonzero crack opening stress values are routinely observed, and it seems that there is a general agreement regarding the incidence of the phenomenon under plane stress. However, investigations regarding crack closure under plane strain conditions are less abundant. Moreover, the existence of crack closure under the plane strain state of the stress has been questioned. The importance of accurate measurements of closure to predict adequately fatigue crack growth rates should not be underestimated. Models employed to predict fatigue crack growth rates rely on plasticity-induced crack closure concepts, and the validity of plasticity-induced crack closure depends on crack closure measurements. Crack closure measurements can be performed with Elber’s Method, the ASTM standard(Compliance offset method), or it may be done alternatively by the compliance ratio (CR) or the adjusted compliance ratio method (ACR). In this research, a small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity-induced fatigue crack closure under constant amplitude loading and plane strain conditions. A wide range of T-stresses and KI levels are considered in the finite element analysis with the purpose of exploring the behavior of the crack opening stress. Crack closure was observed for some values of T-stress. Other values of T-stress resulted in an absence of closure under steady state conditions. In addition, an elastic-plastic finite element model was used to simulate a growing fatigue crack with WARP3D software. The computed displacements were used to determine the effective stress intensity factor range ΔKeff with the ASTM standard compliance offset approach, the (CR) method, and the (ACR) method. Finally, measurement location effects on ACR and the ability of ACR method to remove residuals stresses were investigated.