Assessing the productivity of selective container terminals in Africa using Data Envelopment Analysis (DEA)

Data envelopment analysis (DEA) is used to assess the efficiency of 15 container terminals in Africa. The models proposed by Charnes, Cooper and Rhodes (1978) and Banker, Charnes and Cooper (1984) are used to determine and rank the efficiencies of the container terminals for 2013 and 2014. The results show that selected South African container terminals can improve on their operations relative to some of their neighbours to the North. Bootstrapping methods are used to investigate and clarify the results. The Malmquist Productivity Index (MPI) model is used to track and explain changes in efficiency over the period of assessment

Assessing the productivity of selective container terminals in Africa using Data Envelopment Analysis (DEA)

Data envelopment analysis (DEA) is used to assess the efficiency of 15 container terminals in Africa. The models proposed by Charnes, Cooper and Rhodes (1978) and Banker, Charnes and Cooper (1984) are used to determine and rank the efficiencies of the container terminals for 2013 and 2014. The results show that selected South African container terminals can improve on their operations relative to some of their neighbours to the North. Bootstrapping methods are used to investigate and clarify the results. The Malmquist Productivity Index (MPI) model is used to track and explain changes in efficiency over the period of assessment

A framework to support the decision-making process for modelling of communicable diseases

Thesis (MEng)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Infectious disease outbreaks have the potential to disrupt and strain the global health care system, even more so when a localised disease outbreak propagates rapidly to a large area. Such a disease outbreak is referred to as a pandemic disease outbreak. Pandemic outbreaks often inspire global collaboration between researchers and modelling practitioners with a view to devise strategies, disease propagation models and actions on how to address the outbreak. Modelling of infectious disease is a complex endeavour. The literature on the available modelling approaches and general application to disease modelling is well documented in the literature. What is, however, less evident, especially to a modelling practitioner with less rigorous modelling experience, is the selection and consideration of modelling considerations based on the specific context of the disease outbreak. To address this challenge, a modelling support framework is designed in this research project, with a view to formalise the most salient universal modelling steps and assist novice modelling practitioners in the consideration and selection of appropriate approaches for modelling infectious diseases. The research consists of three phases, namely the design and execution of a structured literature review, analysis of the findings of the literature review, and the construction of a modelling support and guidance framework. During the first phase of the research, the chain of infection is used as an overarching metaphor to guide the process in identifying relevant considerations, disease characteristics and contextual factors which may potentially affect disease propagation, and this is used as the basis for determining the scope of the structured literature review. The review is designed to construct a sufficiently detailed dataset which is well representative of the various modelling approaches as applied in literature. The 283 identified literature pieces are methodically analysed and the relevant modelling considerations, disease characteristics and contextual factors from each of the pieces are captured to the dataset. During the second phase of the research the dataset is analysed. The modelling considerations are analysed in relation to the disease transmission mode, and the relationship between modelling considerations are also analysed. In general, the selection of modelling approaches and considerations were not reducible to a single factor. This suggests that numerous factors must be considered in the model decision making process, and additionally, it highlights the importance of contextualising the disease outbreak. The third phase of the research consists of the framework construction. Both the first and the second phases of the research are used to inform and guide the framework construction. The framework is constructed with two goals in mind, namely to inform modelling considerations from a holistic viewpoint and to aid in the selection of the relevant modelling considerations. The framework use is verified with an illustrative case study and validated with semi-structured interviews that are conducted with external subject matter experts with a background in engineering and health care modelling.AFRIKAANSE OPSOMMING: Die uitbreek van ’n aansteeklike siekte het die potensiaal om die globale gesondheidsorgsisteem te ontwrig en onder geweldige druk te plaas, des te meer wanneer so ’n gelokaliseerde uitbreking spoedig na ’n groter area versprei. Sulke siekte-uitbrekings staan bekend as pandemiese siektes. Die ontstaan van pandemiese uitbrekings van siektes lei tipies tot wêreldwye samewerking tussen navorsers en modelleerders. Die doel van samewerking hou verband met die skep van strategieë, modelle wat siekte-oordrag modelleer en aksieplanne om die uitbreking te bestuur. Die modellering van aansteeklike siektes is ’n komplekse onderneming. Beskikbare modellerings-benaderings en die generiese gebruik daarvan om siektes te modelleer is goed opgeteken in die literatuur. Wat minder ooglopend is van hierdie benaderings, veral vir die modelleerder met elementêre modelleringskennis, is die oorweging en selektering van modelleringelemente gebaseer op die spesifieke kontekstuele omstandighede van die siekte-uitbreking. Om hierdie uitdaging aan te pak word daar in hierdie navorsingsprojek ’n ondersteuningsraamwerk vir modellering geskep. Die doel hiervan is die formalisering van die belangrikste modellerings-stappe en om onervare modelleerders te ondersteun in die oorweging en selektering van toepaslike benaderings om aansteeklike siektes te modelleer. Die navorsing bestaan uit drie fases, naamlik die ontwerp en uitvoering van ’n gestruktureerde literatuuroorsig, ’n analise van die bevindinge van die literatuuroorsig, en die opstel van ’n raamwerk wat ondersteuning en raadgewing ten opsigte van modellering bied. As deel van die eerste fase van die navorsing, word die ketting van infeksie as ’n oorhoofse metafoor gebruik. Hierdie metafoor word gebruik om relevante oorwegings, siekte-eienskappe en kontekstuele faktore te identifiseer wat die potensiaal het om die verspreiding van siektes te beïnvloed. Dit word ook as die basis gebruik om die bestek van die gestruktureerde literatuuroorsig te bepaal. Die gestruktureerde literatuuroorsig is ontwerp om ’n gedetailleerde datastel op te stel wat ’n goeie verteenwoordiging is van die verskeie modelleringsbenaderings soos dit in die literatuur toegepas is. Die geïdentifiseerde 283 literatuurstukke is stapsgewys geanaliseer en die relevante modelleringsbenaderings, siekte-eienskappe en kontekstuele faktore van die literatuurstukke is in die datastel opgeneem. As deel van die tweede fase van die navorsing word die datastel geanaliseer. Die modelleringsoorwegings is geanaliseer met betrekking tot die siekte-oordragsmetode en die verhoudings tussen ander modelleringsoorwegings. Oor die algemeen is daar bevind dat die keuse van ’n modelleringsbenadering of -oorweging nie reduseerbaar is tot die oorweging van ’n enkele faktor nie. Die afleiding is dus dat verskeie faktore in ag geneem moet word in die seleksieproses van ’n modelleringsbenadering, en dat die belangrikheid van die kontekstualisering van ’n siekte-uitbreking benadruk moet word. As deel van die derde fase van die navorsing is die raamwerk opgestel. Beide die eerste en tweede fases van die navorsing is gebruik om die opstelproses van die raamwerk te lei en die opstelkeuses in te lig. Die raamwerk is opgestel met twee verwagte uitkomstes, naamlik om die modellerings-oorwegings vanuit ’n holistiese oogpunt in te lig, sowel as om die selektering van relevante modelleringsoorwegings te ondersteun. Die gebruik van die raamwerk is geverifieer met behulp van ’n verduidelikende gevallestudie. Die validasie is voltooi met behulp van semi-gestruktureerde onderhoude met eksterne vakgebied-kenners met ’n agtergrond in die ingenieurswese en gesondheidssorg-modelleringsvelde

Genetic variation, structure and dispersal among Cape buffalo populations from the Hluhluwe-Imfolozi and Kruger National Parks of South Africa

Genetic variation, structure and dispersal among Cape buffalo populations from the Hluhluwe-Imfolozi and Kruger National Parks of South Africa Barend Jacobus (Ben) Greyling Doctor of Philosophy (Zoology) Department of Zoology and Entomology Supervisor: Prof. Armanda Slager-Bastos Co-supervisor: Dr. Pim van Hooft 2007 The research reported on in this thesis is aimed at quantifying and qualifying, using a molecular genetics approach, some of the factors that influence the population dynamics of Cape buffalo (Syncerus caffer caffer) from the Kruger National Park (KNP) and Hluhluwe-imFolozi park (HiP) in South Africa. Prior to large-scale genotyping of animals sampled from these parks, a high-throughput, cost- and time-effective profiling system was developed. The system, based on a panel of 17 microsatellites (Msats), was found to be quite suitable for the intended application, since it uncovered substantial genetic variation, while exclusion probabilities were in excess of 0.999 and a random match probability of 6.5 x 10-17 was obtained. Inter-population level analyses revealed that the two populations were significantly differentiated (Msat data: FST = 0.159; mtDNA data: FST = 0.275), while little or no differentiation could be demonstrated among most herds and subpopulations. It seems that while drift has played a major role in divergence of the two populations, gene flow is the primary driving force behind the maintenance of genetic variation among herds and subpopulations. A striking feature was that HiP exhibited significant lower levels of genetic variation than KNP, which is reflected by the fact that a mere 4 haplotypes could be found in HiP compared to 34 identified in KNP. The absence of geographic partitioning and small genetic distances separating the haplotypes may be attributed to genetic contact between the respective populations in the distant past. The reduced levels of genetic variation in HiP may be the remnants of the rinderpest bottleneck. HiP also displayed signals of a population contraction, while KNP is in equilibrium and seems to have retained substantial levels of genetic variation. HiP also experienced a steady decline in genetic variation from 1986 to 2004, while sex-biased dispersal was less pronounced in HiP than in KNP, possibly due to the lack of mtDNA diversity and the small size of the park. The results presented here provide valuable baseline information for making conservation management decisions from a genetic point of view.Thesis (PhD (Zoology))--University of Pretoria, 2007.Zoology and Entomologyunrestricte

Designing an evaluation instrument for South African intermediate phase school textbooks

No coherent theory about the practice of South African intermediate phase school textbook evaluation has been forthcoming since the advent of a new South African school curriculum in 1998. This deficiency has had an adverse effect on the quality of intermediate phase school textbooks, as well as on the capacity to assess their value. This research project, therefore, had two aims. The first was to articulate a theory about the practice of textbook evaluation. The second was to develop a procedure for evaluating South African intermediate phase school textbooks in terms of the theory. The research method was underpinned by the interpretive research paradigm in terms of which relevant data were analysed and interpreted. The data emanated from a literature review, an analysis of the national Department of Education’s Revised National Curriculum Statement and its draft policy for the evaluation of learning support material, and two surveys. The first survey comprised a sample of intermediate phase teachers and the second a sample of intermediate phase textbook authors. Sufficient evidence was found to conclude that the capabilities of the authoring team, the authors’ rationale and their observance of the process of learning and instruction, the accessibility of the textbook, the availability of teacher support, meeting the requirements of the Revised National Curriculum Statement, and certain key notions about textbook evaluation play a role in articulating a theory about textbook evaluation in order to guide the process of determining the effectiveness of South African intermediate phase school textbooks. Based on the above-mentioned theory, this study proposes a procedure to assist teachers and textbook evaluators to assess the worth of South African intermediate phase school textbooks in a brief, systematic, thorough, rigorous, and practical manner

Critical analysis of angle modulated particle swarm optimisers

This dissertation presents an analysis of the angle modulated particle swarm optimisation (AMPSO) algorithm. AMPSO is a technique that enables one to solve binary optimisation problems with particle swarm optimisation (PSO), without any modifications to the PSO algorithm. While AMPSO has been successfully applied to a range of optimisation problems, there is little to no understanding of how and why the algorithm might fail. The work presented here includes in-depth theoretical and emprical analyses of the AMPSO algorithm in an attempt to understand it better. Where problems are identified, they are supported by theoretical and/or empirical evidence. Furthermore, suggestions are made as to how the identified issues could be overcome. In particular, the generating function is identified as the main cause for concern. The generating function in AMPSO is responsible for generating binary solutions. However, it is shown that the increasing frequency of the generating function hinders the algorithm’s ability to effectively exploit the search space. The problem is addressed by introducing methods to construct different generating functions, and to quantify the quality of arbitrary generating functions. In addition to this, a number of other problems are identified and addressed in various ways. The work concludes with an empirical analysis that aims to identify which of the various suggestions made throughout this dissertatioin hold substantial promise for further research.Dissertation (MSc)--University of Pretoria, 2017.Computer ScienceMScUnrestricte

Local and global search based PSO algorithm

Abstract: In this paper, a new algorithm for particle swarm optimisation (PSO) is proposed. In this algorithm, the particles are divided into two groups. The two groups have different focuses when all the particles are searching the problem space. The first group of particles will search the area around the best experience of their neighbours. The particles in the second group are influenced by the best experience of their neighbors and the individual best experience, which is the same as the standard PSO. Simulation results and comparisons with the standard PSO 2007 demonstrate that the proposed algorithm effectively enhances searching efficiency and improves the quality of searching.Originally presented at Fourth International Conference on Swarm Intelligence (ICSI 2013), Harbin, China, 12-15, June, 2013

Small world network based dynamic topology for particle swarm optimization

Abstract: A new particle optimization algorithm with dynamic topology is proposed based on ‘small world’ network. The technique imitates the dissemination of information in a ‘small world network’ by dynamically updating the neighborhood topology of particle swarm optimization. The proposed dynamic neighborhood strategy can effectively coordinate the exploration and exploitation ability of particle swarm optimization. Simulations demonstrated that convergence of the swarms is guaranteed. Experiments demonstrated that the proposed method maintained the population diversity and enhanced the global search ability