Limit Analysis and Shakedown in Plane Frames and Plane Stress Problems

A method is developed for the determination of the shakedown load factor for elastic, perfectly plastic plane frames subjected to cyclic loading or random loads varying between fixed limits. The essential feature of the method is the employment of an automatic force method of elastic analysis which provides self-stress systems for the frame. This in turn permits the ready formulation of the compatibility requirements which are imposed on plastic hinge rotations. As a result, the analysis proceeds with data input which is comparable to straightforward kinematic analysis. A preliminary study of the generalisation of this approach to the limit analysis of plane stress problems is also given

The memoirs of C.S. Douglas

In this transcription of original memoirs, Cuthbert Sholto Douglas, 21.1.1887 - 6.8.1973, the son of a Methodist minister, describes his youth in Sea Point, and his studies in Land Surveying in Cape Town in the early years of the 20th century. His early career as a surveyor took place in Piet Retief, before he joined the Department of Irrigation. His responsiblities included work on the Hartebeespoort Dam, and the reconnaissance into the feasibilty of the Kalahari water scheme proposed by Prof. Schwartz. He worked on the Sundays River Valley irrigation canals, before proceeding to work in Bloemfontein, Pietermaritzburg and finally Pretoria as Surveyor General. His memoir contains numerous interesting details of life in the field in the early days of land surveying in South Africa, as well as the social history of the time. He was married to Honor Broadhead, daughter of a Methodist minister, and father of Sholto, Kenneth, Hugh and Malcolm Douglas.Donated by Geoff Douglas, 201

“Brightly Colored Magic and Weird Worlds”: Sylvia Plath’s Creation of Personae Through Her Visual Poetics

In this dissertation, I extend existing acknowledgments of the impact of Sylvia Plath’s visual arts training on her writing in order to argue that her painterly sensibilities are central to her character construction. Specifically, I contend that Plath draws upon a set of visual techniques, which I categorise as hallucinations, mental images, dreams, blurriness, and visual-to-verbal re-inscription. The ability to control subjective experience through the imagination, a philosophy Plath discusses in her journals, acts as a framework for her narratives, and visual techniques become, for Plath’s personae, a method of manipulating their experiences through a blurring of the divide between individual imagination and subjective reality. Plath’s visual techniques further function to represent her personae’s psychic interiority in ways that not only illustrate the limits to expression of the traditionally literary but also offer a means of overcoming these limits through an alternative system of meaning-making. Thus, her personae’s agency exists at the level of form, through self representation that is not stymied by the limitations of the written word, as well as at the level of narrative, through her personae’s control of experience. Moreover, because these visual techniques appear frequently in narratives that are preoccupied with a gendered power dynamic, I contend that we should understand Plath’s moments of resistance to textual tradition as enabling her personae’s escape from patriarchal limitations to freedom and selfexpression. While this recognition of the significance of Plath’s visual techniques should not necessarily constitute a panacea to the constraints of traditional language, it does offer a new way of reading Plath which acknowledges her painterly sensibilities as crucial to the way in which she gives her personae agency and writes back to her literary forefathers

The use of stable isotope ratios of carbon and nitrogen to elucidate pelagic marine foodwebs of the Benguela and Agulhas Bank regions of South Africa

Bibliography: pages 75-84.Isotope assessments of foodweb relationships amongst pelagic organisms may be influenced by their lipid content, since lipids are more depleted in ¹³C than other biochemical compounds. This is particularly important for plankton which show a greater decrease in δ¹³C caused by the failure to remove lipids during sample preparation, than the muscle tissue of pelagic fish species. Lipid removal is important for those fish species whose lipid content and magnitude of diet-consumer fractionation are simultaneously related to their size. The period required for pelagic fish to isotopically reflect a new diet is slow, of the order of months and years, and may depend on the diet and the magnitude of isotopic change displayed. It is likely that this rate decreases as the fish approach isotopic equilibrium with the new food source

Factors influencing survivorship of Portulacaria afra cuttings in restoration of degraded lands

Heavy over-browsing, over-grazing, and over-trampling has caused the degradation of vast areas of subtropical thicket, including parts of the Greater Addo Elephant National Park (GAENP). Severe degradation has resulted in the loss of vegetation cover and the deterioration of soils and soil functioning. The South African Department of Environmental Affairs (DEA), and specifically the Natural Resource Management Programme (NRM), have invested in restoration initiatives such as the Subtropical Thicket Restoration Programme (STRP), which has aimed to demonstrate the logistical and practical feasibility of restoring these degraded thickets by planting en masse Portulacaria afra (spekboom) cuttings. However, the planted P. afra cuttings often succumb to various abiotic and biotic stresses. This project aimed to identify various factors which may influence the survival of P. afra cuttings, including i) soil properties, ii) water (rainfall, infiltration, run-off, etc.), iii) browsing by mega-herbivores, iv) topographical features such as slope and aspect, or v) plant species or communities. Biodiversity and carbon baselines were carried out at 50 plots within the Main Camp, Darlington and Kabouga sections of the GAENP, providing pre-planting vegetation and soil data. The en masse planting of P. afra occurred following the completion of the baselines. Following a minimum rest period of three months after planting, survivorship counts were carried out at all plots. Infiltration rate had a significant positive relationship with planted P. afra survivorship across all of the sites. Positive trends between increases in litter and root biomass and planted P. afra cuttings survivorship in Kabouga were also evident. Magnesium, water-holding capacity and increasing soil clay percentage were found to have a significant negative relationship with planted P. afra survivorship in Kabouga. Aluminium, magnesium, and boron all had significant positive relationships with planted P. afra cuttings survivorship in Addo Main Camp. No soil variables had any significant relationship with survivorship of planted P. afra cuttings at Darlington. The presence of elephants (Loxidonta africana) had a significant negative relationship with planted P. afra survivorship. Plant communities in more ‘moderately’ degraded states, characterized by the retention of canopy dominant species, woody vegetation cover, limited bareground and higher cover of litter had higher survivorship of planted P. afra cuttings than those in more severely degraded states. The grass Panicum maximum, and forb Atriplex semibaccata were associated with positive relationships with planted P. afra survivorship across all sites. Future research should aim to develop matrices which plot likely survivorship percentages with parameters of measurable variables, such as infiltration, severity of soil capping, browsing densities, chemical indicators, and degradation severity, to identify suitable biophysical planting conditions for P. afra cuttings. Further research should assess whether the presence of elephants, in high densities, can reduce the economic feasibility of the en masse plantings of P. afra cuttings in attempts to restore degraded landscapes

Variables associated with run out opportunities in cricket: coaches’ perceptions versus video analyses of the Indian Premier League 2018/2019 seasons

The purpose of this investigation was to add a scientific element to the understanding of run out opportunities in T20 (twenty/twenty) formats, which would in turn, provide recommendations to players and coaches around the topic of run outs. Due to a lack of research in this field, the study was two-fold, as there is little research known on this topic. Firstly, surveying experienced coaches on what they would expect to take place during run out opportunities from different areas of the field in a T20 game. Secondly, the study looked at what happened during successful and unsuccessful run outs from different areas of the field in two Indian Premier League (IPL) seasons. The aim of the study was to determine what variables, within an area of fielding, led to a successful or non-successful run out from different zones in the field. Coaches were required to fill out a survey which asked them to give their expectations on run out opportunities during a T20 competition. The data from the questionnaire would be used to gain a greater understanding of the way coaches understand different characteristics of run outs and whether this matched the findings of the second part of this study. The second part of the study investigated run out opportunities in two consecutive IPL seasons, based on video footage, looking at how different variables impacted successful or marginally missed run out opportunities in different areas of the field and at different times of the game. The areas were put into four different zones. Zone 1 being close to the batter, zone 2 being in the inner ring, zone 3 being on the edge of the ring and zone 4 being boundary fielders. Most of the coaches believed that in zone 1 of the field, the bowler would have the most opportunities, where in fact, based on the video footage, these fell to the wicket-keeper. In zone 2 there were a larger range of fielding positions (10) that run outs fell to when analysing video footage. The coaches supported this by often naming the same fielding positions. There was a divide in zone 3. Most run out opportunities from the video footage came to extra cover, where most coaches didn’t believe that would be the case and rather mentioned mid-off and mid-on. When analysing video footage in zone 4, it had two fielding positions (long on and deep mid-wicket) make up the majority of run out chances in this area and these two positions were quoted by most of the coaches as having the most run out opportunities fall to them. Throughout the findings, as concluded from the video footage, there were some results that matched the coaches’ expectation and some results where findings from the video footage differed from the coaches’ expectations. These findings are all useful. Firstly, it validates coaching practices. Secondly, it provides coaches with greater insight as to where they aren’t getting it correct in their fielding training. In conclusion, this study found that although coaches perceptions, for the most part, matched what took place on the field, there were instances where we saw the opposite action take place. This has important practical implications for coaching and practice.Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 202

Variables associated with run out opportunities in cricket: coaches’ perceptions versus video analyses of the Indian Premier League 2018/2019 seasons

The purpose of this investigation was to add a scientific element to the understanding of run out opportunities in T20 (twenty/twenty) formats, which would in turn, provide recommendations to players and coaches around the topic of run outs. Due to a lack of research in this field, the study was two-fold, as there is little research known on this topic. Firstly, surveying experienced coaches on what they would expect to take place during run out opportunities from different areas of the field in a T20 game. Secondly, the study looked at what happened during successful and unsuccessful run outs from different areas of the field in two Indian Premier League (IPL) seasons. The aim of the study was to determine what variables, within an area of fielding, led to a successful or non-successful run out from different zones in the field. Coaches were required to fill out a survey which asked them to give their expectations on run out opportunities during a T20 competition. The data from the questionnaire would be used to gain a greater understanding of the way coaches understand different characteristics of run outs and whether this matched the findings of the second part of this study. The second part of the study investigated run out opportunities in two consecutive IPL seasons, based on video footage, looking at how different variables impacted successful or marginally missed run out opportunities in different areas of the field and at different times of the game. The areas were put into four different zones. Zone 1 being close to the batter, zone 2 being in the inner ring, zone 3 being on the edge of the ring and zone 4 being boundary fielders. Most of the coaches believed that in zone 1 of the field, the bowler would have the most opportunities, where in fact, based on the video footage, these fell to the wicket-keeper. In zone 2 there were a larger range of fielding positions (10) that run outs fell to when analysing video footage. The coaches supported this by often naming the same fielding positions. There was a divide in zone 3. Most run out opportunities from the video footage came to extra cover, where most coaches didn’t believe that would be the case and rather mentioned mid-off and mid-on. When analysing video footage in zone 4, it had two fielding positions (long on and deep mid-wicket) make up the majority of run out chances in this area and these two positions were quoted by most of the coaches as having the most run out opportunities fall to them. Throughout the findings, as concluded from the video footage, there were some results that matched the coaches’ expectation and some results where findings from the video footage differed from the coaches’ expectations. These findings are all useful. Firstly, it validates coaching practices. Secondly, it provides coaches with greater insight as to where they aren’t getting it correct in their fielding training. In conclusion, this study found that although coaches perceptions, for the most part, matched what took place on the field, there were instances where we saw the opposite action take place. This has important practical implications for coaching and practice.Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 202

Studies on the gastric proteases in three South African snake species

The pepsinogens and pepsins of cobra, mole snake and puff adder have been studied. The pepsinogens of all three species fall into two distinct groups, here designated PI and PII. At least the latter group, in all cases, shows substantial microheterogeneity. Physicochemical studies suggest that the cobra and puff adder PII groups are more similar to each other than either is to the mole snake PII group. Kinetic studies indicate that, in the cobra and mole snake, the PI and PII pepsins differ in their Arrhenius activation energies. Such difference is smaller, or absent, in the case of the puff adder PI and PII pepsins. These characteristics of the pepsins are assessed in the context of the differences between the oral secretions of the three species studied. The suggestion is advanced that the puff adder's strongly proteolytic venom has influenced certain properties of its gastric proteases

The development of cello technique in the string quartets of Joseph Haydn with special reference to (a) the various external influences causing this development and (b) the potential use of the cello parts within a teaching situation

From Introduction: In the middle of the eighteenth century, when Haydn began composing his first string quartets, violin writing was highly advanced and the violin an established solo instrument, its supremacy already firmly endorsed by the Italian Violin Schools of the seventeenth and early eighteenth centuries. The pace of development of the cello, however, was not comparable to that of the violin, despite the fact that the first cello known to us was made in 1572