1834 research outputs found
Sort by
Hadeda Ibis (Bostrychia hagedash) urban nesting and roosting sites
No full textHadeda Ibis (Bostrychia hagedash) have increased in population size and expanded in range in South Africa possibly as a result of increased use of exotic trees for nesting and roosting in urban areas. We investigated the urban nesting and roosting sites of the Hadeda Ibis by measuring tree height and species used by Hadeda Ibis for nesting and roosting in Pietermaritzburg, KwaZulu-Natal, South Africa. We expected Hadeda Ibis nests and roosts to have habitats, like wetlands, to be within 10 km of the roost or nest tree. Hadeda Ibis nest and roost locations were mapped using ArcGIS and available resources (grasslands, wetlands, plantations, other natural water sources) 10 km around each roost and nest tree were determined. Results showed that Hadeda Ibis use exotic trees for nesting and roosting in urban areas more than indigenous trees. This may be because exotic trees are more available in urban environments, particularly those trees that have ornamental value. Hadeda Ibis did not nest and roost closer to expected resources. Although previously associated with wetlands, Hadeda Ibis in urban environments were not close to natural water sources. This can be explained by swimming pools providing accessible drinking water and well watered lawns providing suitableNational Research Foundation (South Africa
Morphometrics, sex ratio, sexual size dimorphism, biomass, and population size of the Nile crocodile (Crocodylus niloticus) at its southern range limit in KwaZulu-Natal, South Africa
No full textAnimal body size and sex are requisite data for understanding population structure and demography. Little information exists regarding Nile crocodile, Crocodylus niloticus, morphometrics, sex ratios of wild populations, sexual size dimorphism and standing crop biomass. We captured 322 C. niloticus at Lake St Lucia and Ndumo Game Reserve, South Africa, the two largest crocodile populations at the southern extent of the species’ range in Africa, and measured a suite of physical characteristics to create predictive models of body length from other morphological attributes and body mass. Our sample included 118 hatchlings, 91 subadults and 113 adults. Strong positive allometric relationships were found between body length metrics (total length and snout-vent length) and other morphometrics. All morphometric regressions were linear, with the exception of the relationship of body length to body mass, which was logarithmic. Among relationships of cranial morphology and body length, we found considerable individual variation among all size classes. The mean head width-to-head length ratio was 1.9 ± 1.6, and mean head length-to-total length ratio was 0.14 ± 0.005. The sex ratios for non-hatchling individuals at both populations were essentially 1:1, but adult sex ratios were male biased. We calculated a total standing crop biomass of 96,867.18 kg (161.45 kg/km) and 52,640.40 kg (1504.01 kg/km) for C. niloticus at Lake St Lucia and Ndumo Game Reserve, respectively, and an estimated 3650 non-hatchling individuals for the province of KwaZulu-Natal. The data presented here will help inform crocodile management and population surveys in South Africa, where C. niloticus is an important apex predator that partitions aquatic resources and occasionally comes into conflict with human beingsNational Research Foundation (South Africa
Students encountering race and negotiating friendships, sexuality and language on campus
No full textBy drawing on a theoretical framing based on the geography of encounters, this article examines how students give meaning to racialised encounters on campus. These encounters are mediated by long established notions of difference based on power inequalities where race remains a powerful source of difference. However, race is not simply enacted but produced as it weaves through student friendships, heterosexual partnering and through language. By focusing on the construction of race in student encounters on campus, the article uncovers the points at which students produce relations of inequalities, their contestations and the continuities in racialised power structures. The article concludes by pointing to the value in understanding the race-friendship-heterosexual-language tension, which might help work towards understanding and addressing inequalities based on locally relevant interventions on campus.National Research Foundation (South Africa
Fuzzy particle swarm optimization algorithms for the open shortest path first weight setting problem
No full textThe open shortest path first (OSPF) routing protocol is a well-known approach for routing packets from a source node to a destination node. The protocol assigns weights (or costs) to the links of a network. These weights are used to determine the shortest paths between all sources to all destination nodes. Assignment of these weights to the links is classified as an NP-hard problem. The aim behind the solution to the OSPF weight setting problem is to obtain optimized routing paths to enhance the utilization of the network. This paper formulates the above problem as a multi-objective optimization problem. The optimization metrics are maximum utilization, number of congested links, and number of unused links. These metrics are conflicting in nature, which motivates the use of fuzzy logic to be employed as a tool to aggregate these metrics into a scalar cost function. This scalar cost function is then optimized using a fuzzy particle swarm optimization (FPSO) algorithm developed in this paper. A modified variant of the proposed PSO, namely, fuzzy evolutionary PSO (FEPSO), is also developed. FEPSO incorporates the characteristics of the simulated evolution heuristic into FPSO. Experimentation is done using 12 test cases reported in literature. These test cases consist of 50 and 100 nodes, with the number of arcs ranging from 148 to 503. Empirical results have been obtained and analyzed for different values of FPSO parameters. Results also suggest that FEPSO outperformed FPSO in terms of quality of solution by achieving improvements between 7 and 31 %. Furthermore, comparison of FEPSO with various other algorithms such as Pareto-dominance PSO, weighted aggregation PSO, NSGA-II, simulated evolution, and simulated annealing algorithms revealed that FEPSO performed better than all of them by achieving best results for two or all three objectivesNational Research Foundation (South Africa
The community work programme: potentials and problems
No full textThis article provides a detailed and critically reflective ‘insider’ account of the origins and development of a Community Work Programme as a public employment programme intervention. The article explores the significant potential of such a Community Work Programme to reduce unemployment and improve socio-economic livelihoods for programme participants, and its potential to model public/private alignment across sectors that complements what can be accomplished within the budgetary constraints of the central government alone. It also describes the challenges of programme implementation as a social policy intervention, arising in part from the difficulties of scaling up successful pilots to create a nationwide programme. The article demonstrates real achievements but also the difficulties of engagement with the state by non-profit organisations, and the difficulties of forging sustainable partnerships between communities and government around shared goals.National Research Foundation (South Africa
DCCMS’s Support of GMSA: the drivers behind NRF funding systems and processes
No full textTo introduce new employees, as well as re-acquaint existing staff with the work of GMSA, you will learn what happens behind the scenes of the NRF's funding activities through a series of 15 - minute presentations from representatives of the NRF's various business units
Ride comfort in commercial aircraft during formation flight using conventional flight control
No full textGlobal market forecasts and rapid air transport growth are making the aeronautical industry become aware of the necessity to develop high capacity long-range and fuel-efficient aircraft while maintaining high levels of passenger comfort. With the large interest in automated formation flight and improvements in automated flight control, it is the aim of this research to evaluate passenger ride comfort in commercial aircraft during formation flight.
The main objective of this thesis is to take into account the aircraft dynamics, atmospheric
turbulence and the effect of a flight control system when evaluating the ride comfort of passengers.
To achieve this objective, a detailed literature study into current and past projects
was performed, focusing on formation flight, passenger comfort evaluation and improvements in passenger comfort with efficient control systems design. Following the literature study, a theoretical Boeing B747 aircraft model was built and tested in MATLAB and Simulink. Subsequently, a conventional model of the fly-by-wire architecture used in modern transport aircraft was designed, implemented, and verified in simulation.
To model the formation flight effects, the induced forces and moments on the follower aircraft due to the trailing vortices of the leader were derived in a previous study by Bizinos at the University of Cape Town. These induced loads, expressed as aerodynamic coefficients, were used in conjunction with the conventional aerodynamic model to produce an extended aerodynamic model for formation flight. The conventional fly-by-wire control architecture used by modern transport aircraft has been extended for formation flight of two or more aircraft, with the focus on two aircraft in right echelon formation. A full non-linear simulation with realistic turbulence was produced to verify the working of the extended controllers and to ensure the follower maintains its path behind the leader aircraft.
In formation flight, the passenger comfort is influenced by disturbance loads due to the turbulence, as well as by compensatory control inputs produced by the autopilot controllers. The accelerations of passengers in a seated position were determined by considering the passenger’s seated position with respect to the mass centre, and the forces and moments at and around the mass centre respectively. These accelerations are weighted according to their frequency to determine the comfort levels in accordance with the International Organisation for Standardisation (ISO 2631-1).
Simulation results of the accelerations experienced at different locations in the trailing aircraft of a formation showed that very little difference in comfort can be expected between the different formation flight aircraft under the same flight conditions. It was concluded for both aircraft that a seating location at the front of the aircraft is more comfortable than one at the back of the aircraft. During light and moderate turbulence, the overall acceleration magnitudes remained within the not uncomfortable region suggested by the ISO 2631-1 standard. The percentage of ill passengers in isolated and formation flight is very low, making motion sickness incidence during formation flight almost no different to motion sickness during isolated flight.National Research Foundatio
Arabinoxylan as partial flour replacer: the effect on bread properties and economics of bread making
No full textWheat bran, used for animal feed, is a good candidate for production of higher value products such as arabinoxylan (AX). Extracted AX holds potential as a partial flour replacer in the bread making industry. The aim of this study was to maximise flour removal while using the minimum AX addition possible while maintaining physical bread properties.
The extraction of AX from wheat bran was accomplished using alkaline conditions. The purity of AX extracted at lab scale (275 ml) was 44.3% at the optimum extraction conditions (0.5 M NaOH, 240 min, 80°C). Large scale extraction (27 l) resulted in an extract with 49.3% purity, with addition of purification steps including ultrafiltration, anion exchange chromatography and ethanol precipitation. The two extracts obtained on small scale (E1) and large scale (E2) both had high average molecular weights (620 000 and 470 000 Da, respectively) and arabinose to xylose (A/X) ratios of 0.7 and 0.6. With inclusion of the additional purification steps at large scale, the whiteness index of the final extract was increased from 33 to 93. For the application purpose, the lighter extract colour will have a less prominent effect on bread colour and is therefore advantageous.
The high water binding capacity of AX allows for increased dough water absorption resulting in an altered final bread weight and volume. However, at optimal AX addition and flour removal levels, these product properties can be maintained. This was achieved with inclusion of 0.8% crude AX extract and 2.5% flour removal, while increasing water absorption by nearly 2%. The only physical difference between the AX containing loaves and the control was in colour, due to the darker colour of the extract. However, a discolouration step included in the extraction of E2 resulted in a significantly lighter final product compared to loaves containing E1. Comparison of E1 and E2 to highly pure AX resulted in similar final product properties indicating that the extracts’ performance was not affected by the purity. Furthermore, inclusion of an oxidative enzyme, laccase, resulted in a softer final product as determined using a texture analyser.
AX production cost was estimated at R110/ kg resulting in higher production costs for AX containing loaves compared to commercial white bread. In order to maintain profit margins the selling price of AX containing loaves have to be increased by 9.6%.
In conclusion, crude AX extracted from the animal feed co-product, wheat bran, is a feasible candidate for application in the bread making process as a partial flour replacer.National Research Foundatio
Institutional and national policy implications for adopting open access, open data and open science strategies - South Africa
No full textForum on Open Data, Open Science and Open Access to Information in Agriculture in the Context of Sustainable Development Goals (SDGs)
Avani Hotel, Windhoek Namibia, 18 April 201
An analysis of South Africa's role in regional integration in Southern Africa : prospects and challenges
No full textSince the success of Regional Integration (RI) in Europe epitomized by the European Union (EU), the mutual potential benefits that could be attained from RI initiatives and agreements have attracted much attention to the topic of RI. In the African context, RI has been hailed as the mechanism that nurtures the development of economic income, trade and bargaining power. This has resulted in the establishment of a number of Regional Economic Communities (RECs) in different parts of Africa. Despite the prevalence of Regional Economic Agreements (REAs) across Africa, RI has been largely unsuccessful due to a confluence of factors. Having been disregarded as a legitimate state by the Southern African Development Community (SADC) region due to its apartheid regime prior to 1994, South Africa has since emerged as one of the well-developed countries in SSA. Having transitioned from the apartheid regime to a post-apartheid era, South Africa rose to become one of the dominant economic powerhouses in SSA, and a leader in the SADC region. The role of South Africa as a hegemon in SADC has been contested by some, citing the State’s inability to resolve some of its domestic problems to a satisfactory level. This research is an investigation or inquiry into the prospects of South Africa as the most qualified State to carry out the responsibility of spear-heading the RI process in the Southern African region. In the process of compiling this research secondary data obtained from books, journal articles, newspaper articles and existing theses dealing with RI in Europe, Africa, and Southern Africa were analysed. The results of this study portray South Africa as the most suitable candidate for leading RI in Southern Africa. This is primarily due to its advanced infrastructural development, superior economic strength and peace enforcement capabilities in conflict-ridden Africa. South Africa is also the largest capital contributor and the biggest investor in individual states in the SADC region. Based on these results, one recommendation is that the African continent in general and the SADC region in particular has reasons to cooperate with South Africa in reviving the RI agenda that would benefit the entire African continent. South Africa can still play its role as the leading economic powerhouse while the presidency of SADC block of nations is rotated annually amongst the member countries as in the EU. South Africa will then not be viewed suspiciously as having usurped the hegemonic status within the region. Giant strides have already been made in the political and economic arena; South Africa can build on these successes.National Research Foundatio