1834 research outputs found
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Mixed-integer programming based techniques for resource allocation in underlay cognitive radio networks: a survey
No full textFor about the past decade and a half research efforts into cognitive radio networks (CRNs) have increased dramatically. This is because CRN is recognized as a technology that has the potential to squeeze the most out of the existing spectrum and hence virtually increase the effective capacity of a wireless communication system. The resulting increased capacity is still a limited resource and its optimal allocation is a critical requirement in order to realize its full benefits. Allocating these additional resources to the secondary users (SUs) in a CRN is an extremely challenging task and integer programming based optimization tools have to be employed to achieve the goals which include, among several aspects, increasing SUs throughput without interfering with the activities of primary users. The theory of the optimization tools that can be used for resource allocations (RA) in CRN have been well established in the literature; convex programming is one of them, in fact the major one. However when it comes to application and implementation, it is noticed that the practical problems do not fit exactly into the format of well-established tools and researchers have to apply approximations of different forms to assist in the process. In this survey paper, the optimization tools that have been applied to RA in CRNs are reviewed. In some instances the limitations of techniques used are pointed out and creative tools developed by researchers to solve the problems are identified. Some ideas of tools to be considered by researchers are suggested, and direction for future research in this area in order to improve on the existing tools are presentedNational Research Foundation (South Africa
Marikana Commission of Inquiry: from narratives towards history
No full textThe Marikana Commission of Inquiry was established following the killing of 34 Lonmin strikers by South African police on 16 August 2012. This article provides a substantive review of the Commission’s Report, released in June 2015. It highlights the Commission’s assessment that a decision made by top generals the evening before the massacre was ‘the decisive cause’ of the deaths. This and other findings against the police are contrasted with failure to make any recommendations for prosecution. Evidence presented to the Commission is used to draw different conclusions from those in the report. In particular, the article argues that the initial killings, broadcast live on television, were a consequence of planning by the operational commander, rather than a response to workers’ aggression. Culpability for the massacre is also considered. While the narrative presented by the police was discredited, that articulated by workers was largely vindicated. However, this did not restrain the Commission from making comments hostile to the workers, and this antipathy is viewed as a factor leading to errors of judgement. The article was written in honour of Colin Murray. Resonating with his work, it ends by urging historians to take workers’ voices seriously, something that Lonmin, the police, media reporters, and the Commission conspicuously failed to do.National Research Foundation (South Africa
Keeping it in the family: Co-evolution of latrunculid sponges and their dominant bacterial symbionts
No full textThe Latrunculiidae are a family of cold water sponges known for their production of bioactive pyrroloiminoquinone alkaloids. Previously it was shown that the bacterial community associated with a Tsitsikamma sponge species comprises unusual bacterial taxa and is dominated by a novel Betaproteobacterium. Here, we have characterized the bacterial communities associated with six latrunculid species representing three genera (Tsitsikamma, Cyclacanthia, and Latrunculia) as well as a Mycale species, collected from Algoa Bay on the South African southeast coast. The bacterial communities of all seven sponge species were dominated by a single Betaproteobacterium operational taxonomic unit (OTU 0.03), while a second OTU 0.03 was dominant in the Mycale sp. The Betaproteobacteria OTUs from the different latrunculid sponges are closely related and their phylogenetic relationship follows that of their hosts. We propose that the latrunculid Betaproteobacteria OTUs are members of a specialized group of sponge symbionts that may have coevolved with their hosts. A single dominant Spirochaetae OTU 0.03 was present in the Tsitsikamma and Cyclacanthia sponge species, but absent from the Latrunculia and Mycale sponges. This study sheds new light on the interactions between latrunculid sponges and their bacterial communities and may point to the potential involvement of dominant symbionts in the biosynthesis of the bioactive secondary metabolites.National Research Foundation (South Africa
Attending the SA PhD conference-then a student, now an academic
No full textPresentations SA PhD Project Conference: KwaZulu-Natal Province 17 August 2016
SET policy – the Journey
No full textPresentations SA PhD Project Conference: Gauteng Province 11 October 2016
Beyond the proposal: the art of generating funds for strategic research
No full textPresentation DST-NRF Postdoctoral Forum: Cape Town 13-15 March 2016
National postgraduate research forum - Abstracts
No full textDST-NRF Postdoctoral Forum: Cape Town 13-15 march 2016
Grant proposal writing
No full textPresentation DST-NRF Postdoctoral Forum: Cape Town 13-15 March 201
A pilot study of seasonal and interannual patterns in the distribution of chlorophyll α and temperature over three areas of the southwest Indian Ocean: northeast Madagascar, southeast Madagascar and the Mascarene Islands
No full textRemotely sensed weekly MODIS data of chlorophyll α (Chl-α) concentration, sea surface temperature (SST) and satellite altimetry data of Absolute Dynamic Topography (ADT) and geostrophic velocities are used to examine the seasonal and interannual patterns in the Chl-α concentration and SST over three pilot study areas of the southwest Indian Ocean, namely Northeast Madagascar, Southeast Madagascar and Mascarene Islands. The weekly and monthly climatology and the weekly means of each variables are assessed using image displays and time series from 2003 to 2014. It is found that there is a seasonal cycle of phytoplankton blooms occurring twice a year across northeast and southeast Madagascar. The two blooms occur during the summer monsoon and during the winter monsoon, respectively. Unlike these two areas, the Mascarene Islands area has only one bloom during the summer monsoon. There is a negative correlation between SST and Chl-α concentration across all three areas; when SST is high, Chl-α concentration is low and vice versa. Also, the current patterns showed that the two Madagascar study areas, are more physically dynamic than the Mascarene Islands region. Unlike the Masacarene region, the Madagascar regions are more affected by the forcing of the South Equatorial Current that splits into the Southeast Madagascar Current and Northeast Madagascar Current, thus causing displacement of surface water. New outcomes of this study are that the north Indian Ocean (north of 100S) is not the only area that is affected by the summer and winter monsoons but the areas south of 100S may also be indirectly affected by the monsoons. Across Northeast Madgascar region, the summer monsoon bloom is well spread over the area while the winter monsoon bloom is mostly coastal. Across the Southest Madagascar region, the summer monsoon bloom spreads from east to west while, the winter monsoon bloom spreads from west to east. The Mascarene region is less productive with higher sea surface height and weaker eddies compared to the other areas and the mixed layer depth is greater across the Mascarene region, thus less nutrients are injected to the euphotic zone and the weaker eddies result in less mixing and consequently in weak Chl-α production. This study should improve our understanding of the seasonal and interannual variability of the SST and Chl-α and the dynamics of the ADT and geostrophic velocities in these regions for improved management of fishery resources using an ecosystem approach to fisheries.National Research Foundatio