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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This project investigates the use of Rapid Prototyping (RP), with specific focus on Three Dimensional Printing (3DP), in the manufacture of complex shaped advanced composite parts, using variants of the Resin Transfer Moulding (RTM) method of composite manufacture. This study developed design guidelines, cost models and a process chain by studying data obtained by making example parts, from literature and consultation with industry. Advanced composite materials offer some of the best low weight and high specific strength properties for the solution of design problems. A major disadvantage of these processes, however, is the low production rates possible and the need of costly moulds. The 3DP technologies combined with the RTM composite process was found to enable a lowering of costs and increase in productivity if smaller batch sizes are considered. The most meaningful area of application for RP techniques seems to be for smaller and more complex components. The geometrical freedom allowed by RP technologies allowed the manufacture of parts which are challenging to manufacture by conventional technology such as CNC machining. Example part case studies were completed for a simple part utilising the one sided mould Resin Infusion RTM variant as well as for a complex part utilising the closed mould Vacuum Assisted Resin Transfer Moulding (VARTM) process variant. During these two case studies it was clear that proper part infusion with resin is critical for the manufacture of good quality composite parts free of voids and dry spots. It is possible to improve the resin infusion by correct placement of resin inlet and outlet ports as well as resin channels incorporated in the mould. Correct placement of these features for the case studies was obtained through simulations done with RTM-Worx software. Results also indicated that another useful application of RP technology to RTM is the manufacture of disposable cores for parts with thick cross sections. Resin channels were included on the surface of these cores to improve the mould filling with resin and consequently part quality. An early cost estimation model, based on the work of Veldsman (1995), was developed for the combined RP and RTM manufacturing process. This model may help designers to eliminate expensive design features and enables a quick cost comparison with competing processes. Drawbacks of applying RP techniques to RTM include the limited lifetime of moulds produced with 3DP and the size and accuracy limitations of the RP t echnology. / AFRIKAANSE OPSOMMING: Hierdie projek handel oor die toepassing van die drie-dimensionele druk metode van Snel-Prototipering (Rapid Prototyping) op die vervaardiging van komplekse gevorderde saamgestelde materiaal komponente met die Hars-Inspuit Giet (Resin Transfer Moulding) metode. Die projek behels die opstel van ontwerpsriglyne, koste-modelle en ’n proses-ketting deur data te bestudeer wat bekom is deur middel van die vervaardiging van eksperimentele parte, literatuurstudie asook raadpleging met individue in die industrie. Gevorderde saamgestelde materiale verskaf van die beste sterk, dog ligte oplossings vir sekere ontwerpsprobleme. ’n Ernstige nadeel van hierdie materiale is egter die stadige produksietempo moontlik en die vereiste van duur gietstukke. Die Snel- Prototipering metodes, gekombineerd met ’n saamgestelde materiaal vervaardigingsproses, maak laer kostes met beter produktiwiteit moontlik indien ontwerpers die part grootte- en akkuraatheidsbeperkings in ag neem. Die mees betekenisvolle area van toepassing blyk kleiner en meer komplekse komponente te wees. Die vryheid in geometrie wat moontlik gemaak word deur die Snel- Prototipering tegnologie laat die vervaardiging toe van parte wat uitdagend is om te vervaardig met konvensionele tegnologie soos CNC masjinering. ’n Gevallestudie is voltooi vir ’n eenvoudige part vervaardig met die enkelkant gietstuk vakuum-infusie weergawe van die Hars-Inspuit Giet metode asook vir ’n komplekse part wat vervaardig is met die geslote gietstuk Vakuum Hars-Inspuit Giet weergawe van die basiese metode. Dit het tydens die twee gevallestudies duidelik geword dat deeglike hars infusie van kritieke belang is vir die vervaardiging van goeie kwaliteit parte sonder enige droë kolle of lugruimtes. Dit is moontlik om die hars infusie te verbeter deur hars inlate en uitlate asook hars kanale in die korrekte posisies te plaas. Die korrekte posisies vir hierdie komponente is verkry deur middel van ’n reeks simulasies met die RTM-Worx sagteware. Resultate dui ook daarop dat Snel-Prototipering tegnologie handig te pas kom by die vervaardiging van verbruikbare kerne vir saamgestelde materiaal parte met groter diktes. Hars kanale kan maklik op die kerne se oppervlak geskep word om die hars verspreiding en gevolglik part kwaliteit te verbeter. ’n Vroeë kostevoorspellings model, gebaseer op werk voltooi deur Veldsman (1995), is saamgestel vir die gekombineerde Snel-Prototipering en Hars-Inspuit Giet proses. Hierdie model kan gebruik word om duur ontwerpsbesonderhede op parte te elimineer en om ’n vinnige koste vergelyking met ander vervaardigingsprosesse te toon. Nadele van die toepassing van Snel-Prototipering tegnieke op Hars-Inspuit Giet sluit die beperkte gietstuk-leeftyd en beperkte akkuraatheid in.

Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii

O Brasil tem como principal base econômica a exportação de commodities agrícolas e minerais. Esses produtos se caracterizam por possuírem grandes volumes de produção e baixo valor agregado. Diante desses fatos, as economias geradas ao longo da cadeia logística têm papel fundamental para o sucesso da comercialização destes produtos. Nesse contexto, este trabalho teve como objetivo encontrar as rotas de transportes mais econômicas para o escoamento da soja e minérios de ferro e manganês oriundos do estado do Mato Grosso do Sul com destino à exportação. Para tal foram identificados os pólos de geração destas cargas, assim como os modais de transportes existentes e futuros, terminais de transbordos e portos marítimos para exportação. Os métodos utilizados para esta análise foram a geração de cenários, modelos de custo de transporte para os modos rodoviário, ferroviário e fluvial; e sistema de informação geográfica. Os resultados obtidos neste trabalho indicam que opções de rotas com uso do modal hidroviário são as que possuem menores custos, com forte participação da hidrovia Paraguai-Paraná. Sugere-se para futuros trabalhos, a investigação da rede de transporte estudada com o uso de restrições de capacidade e também a inclusão dos custos portuários praticados nos portos marítimos de exportação. / Brazil has as the main economic base the exportation of agricultural and mineral commodities. These products are characterized by having a large quantity of production and low price. Given these facts, the saving generated along the supply chain are fundamental role in the marketing success of these products. In that context, this study aimed to find the most economic transport routes to the disposal of soybeans and iron ore and manganese from the state of Mato Grosso do Sul destined to exportation. For that were identified the places that generate as, and the transportation ways that exist up to now and the future ones, the terminals, transshipments and harbor for export. The methods used for this analysis were the generation of scenarios, models of cost of transport to the modes transport to road, rail and river, and geographic information system. The results obtained in this study indicate that options trades with the use of the waterway are those that have lower costs, with strong participation of the waterway Paraguay-Parana. It is suggested to future researches investigation of the transportation system studied the use of restrictions on capability and the inclusion of costs charged at seaports of exportation.

Les in silico expérimentations scientifiques à grande échelle contiennent généralement plusieurs activités de calcule pour traiter big data. Workflows scientifiques (SWfs) permettent aux scientifiques de modéliser les activités de traitement de données. Puisque les SWfs moulinent grandes quantités de données, les SWfs orientés données deviennent un problème important. Dans un SWf orienté donnée, les activités sont liées par des dépendances de données ou de contrôle et une activité correspond à plusieurs tâches pour traiter les différentes parties de données. Afin d’exécuter automatiquement les SWfs orientés données, Système de management pour workflows scientifiques (SWfMSs) peut être utilisé en exploitant High Perfmance Comuting (HPC) fournisse par un cluster, grille ou cloud. En outre, SWfMSs génèrent des données de provenance pour tracer l’exécution des SWfs.Puisque le cloud fournit des services stables, diverses ressources, la capacité de calcul et de stockage virtuellement infinie, il devient une infrastructure intéressante pour l’exécution de SWf. Le cloud données essentiellement trois types de services, i.e. Infrastructure en tant que Service (IaaS), Plateforme en tant que Service (PaaS) et Logiciel en tant que Service (SaaS). SWfMSs peuvent être déployés dans le cloud en utilisant des Machines Virtuelles (VMs) pour exécuter les SWfs orientés données. Avec la méthode de pay-as-you-go, les utilisateurs de cloud n’ont pas besoin d’acheter des machines physiques et la maintenance des machines sont assurée par les fournisseurs de cloud. Actuellement, le cloud généralement se compose de plusieurs sites (ou centres de données), chacun avec ses propres ressources et données. Du fait qu’un SWf orienté donnée peut-être traite les données distribuées dans différents sites, l’exécution de SWf orienté donnée doit être adaptée aux multisite cloud en utilisant des ressources de calcul et de stockage distribuées.Dans cette thèse, nous étudions les méthodes pour exécuter SWfs orientés données dans un environnement de multisite cloud. Certains SWfMSs existent déjà alors que la plupart d’entre eux sont conçus pour des grappes d’ordinateurs, grille ou cloud d’un site. En outre, les approches existantes sont limitées aux ressources de calcul statique ou à l’exécution d’un seul site. Nous vous proposons des algorithmes pour partitionner SWfs et d’un algorithme d’ordonnancement des tâches pour l’exécution des SWfs dans un multisite cloud. Nos algorithmes proposés peuvent réduire considérablement le temps global d’exécution d’un SWf dans un multisite cloud.En particulier, nous proposons une solution générale basée sur l’ordonnancement multi-objectif afin d’exécuter SWfs dans un multisite cloud. La solution se compose d’un modèle de coût, un algorithme de provisionnement de VMs et un algorithme d’ordonnancement des activités. L’algorithme de provisionnement de VMs est basé sur notre modèle de coût pour générer les plans à provisionner VMs pour exécuter SWfs dans un cloud d’un site. L’algorithme d’ordonnancement des activités permet l’exécution de SWf avec le coût minimum, composé de temps d’exécution et le coût monétaire, dans un multisite cloud. Nous avons effectué beaucoup d’expérimentations et les résultats montrent que nos algorithmes peuvent réduire considérablement le coût global pour l’exécution de SWf dans un multisite cloud. / Large-scale in silico scientific experiments generally contain multiple computational activities to process big data. Scientific Workflows (SWfs) enable scientists to model the data processing activities. Since SWfs deal with large amounts of data, data-intensive SWfs is an important issue. In a data-intensive SWf, the activities are related by data or control dependencies and one activity may consist of multiple tasks to process different parts of experimental data. In order to automatically execute data-intensive SWfs, Scientific Work- flow Management Systems (SWfMSs) can be used to exploit High Performance Computing (HPC) environments provided by a cluster, grid or cloud. In addition, SWfMSs generate provenance data for tracing the execution of SWfs.Since a cloud offers stable services, diverse resources, virtually infinite computing and storage capacity, it becomes an interesting infrastructure for SWf execution. Clouds basically provide three types of services, i.e. Infrastructure-as-a-Service (IaaS), Platform- as-a-Service (PaaS) and Software-as-a-Service (SaaS). SWfMSs can be deployed in the cloud using Virtual Machines (VMs) to execute data-intensive SWfs. With a pay-as-you- go method, the users of clouds do not need to buy physical machines and the maintenance of the machines are ensured by the cloud providers. Nowadays, a cloud is typically made of several sites (or data centers), each with its own resources and data. Since a data- intensive SWf may process distributed data at different sites, the SWf execution should be adapted to multisite clouds while using distributed computing or storage resources.In this thesis, we study the methods to execute data-intensive SWfs in a multisite cloud environment. Some SWfMSs already exist while most of them are designed for computer clusters, grid or single cloud site. In addition, the existing approaches are limited to static computing resources or single site execution. We propose SWf partitioning algorithms and a task scheduling algorithm for SWf execution in a multisite cloud. Our proposed algorithms can significantly reduce the overall SWf execution time in a multisite cloud.In particular, we propose a general solution based on multi-objective scheduling in order to execute SWfs in a multisite cloud. The general solution is composed of a cost model, a VM provisioning algorithm, and an activity scheduling algorithm. The VM provisioning algorithm is based on our proposed cost model to generate VM provisioning plans to execute SWfs at a single cloud site. The activity scheduling algorithm enables SWf execution with the minimum cost, composed of execution time and monetary cost, in a multisite cloud. We made extensive experiments and the results show that our algorithms can reduce considerably the overall cost of the SWf execution in a multisite cloud.

Os investimentos no setor ferroviário brasileiro desde o processo de privatização das ferrovias trouxeram um expressivo crescimento ao setor, evidenciado principalmente pelo aumento do volume de cargas transportadas. Entretanto, a capacidade de processamento dos trens tem sido comprometida pela imposição de limites operacionais de velocidades, decorrentes principalmente do aumento do desgaste da via permanente em função da intensificação do tráfego da malha ferroviária e das restrições das características geométricas da via construída no final do século XIX. Neste contexto e diante das perspectivas de crescimento do setor na próxima década, o objetivo desta dissertação é investigar a validade da hipótese de que a construção de uma nova via, com melhores padrões de projeto e maior capacidade no transporte de cargas, é uma alternativa mais atraente em relação à recuperação e modernização de uma ferrovia existente. O processo de investigação consiste em um método expedito de comparação de cenários através de um modelo de custos generalizado. Neste método, as características planimétricas da nova ferrovia são obtidas pela geração de um conjunto de vetores por inspeção visual no software Google Earth, posteriormente em uma plataforma de desenho assistido por computador (CAD). As características altimétricas da ferrovia são estabelecidas pela associação da geometria da via em planta com os dados altimétricos obtidos do modelo digital de terreno proposto pelo SRTM, através de um método computacional de cálculo dos gradientes da via. A partir dessas informações são estimados os volumes de movimentação de terra associados a cada cenário estabelecido. Como aplicação prática, apresenta-se a análise para um trecho de cerca de 200 km de um dos principais corredores de exportação do país entre as cidades de Santa Fé do Sul e São José do Rio Preto, no Estado de São Paulo, sob concessão da empresa América Latina Logística S.A. Os resultados da investigação permitem inferir que, apesar das limitações impostas pela técnica de modelagem utilizada, o custo total de implantação de uma nova ferrovia supera em apenas 4,3% o custo total de reforma e retificação do traçado antigo, mostrando-se como uma alternativa atraente do ponto de vista econômico, técnico e ambiental. / Investments in the Brazilian railway sector since the privatization of the railways brought a significant growth to the sector, notable primarily by the increase of cargo volume transported. However the processing capacity of the trains has been compromised by the restriction of operation speed limits, due mainly to the increased wear of the railway superstructure with the traffic increase and the geometric restriction of the track built in the late 90th century. In this context and given the sectors growth prospects over the next decade, the goal of this research is to investigate the validity of the hypothesis that the construction of a railroad with new improved design standards and greater capacity is a more attractive alternative than the repair and modernization of an existing railway. The research process consists of an expedite method of scenarios comparison through a generalized cost model. The planimetry features of the new railway are obtained by generating a set of vectors by visual inspection using the Google Earth software, which are fed into a computer aided design (CAD). The altimetry characteristics of track are set by the association of the horizontal track geometry platform with the elevation data obtained from the digital terrain model proposed by SRTM, using a computational method to calculate the gradient of the track. Earthwork volumes are calculated for each scenario based on this date. As a practical application, it presents an analysis of a segment of approximately 200 km between the cities of Santa Fé do Sul and São José do Rio Preto, São Paulo, operated by America Latina Logística S.A. The results of research may imply that, despite the limitations imposed by the modeling technique show that, the total cost of deployment of a new railway exceeds in only 4,3% the total cost of rectification and reform of the old track, and therefore constitutes an attractive alternative from the economical, technical and environmental point of view.

Os investimentos no setor ferroviário brasileiro desde o processo de privatização das ferrovias trouxeram um expressivo crescimento ao setor, evidenciado principalmente pelo aumento do volume de cargas transportadas. Entretanto, a capacidade de processamento dos trens tem sido comprometida pela imposição de limites operacionais de velocidades, decorrentes principalmente do aumento do desgaste da via permanente em função da intensificação do tráfego da malha ferroviária e das restrições das características geométricas da via construída no final do século XIX. Neste contexto e diante das perspectivas de crescimento do setor na próxima década, o objetivo desta dissertação é investigar a validade da hipótese de que a construção de uma nova via, com melhores padrões de projeto e maior capacidade no transporte de cargas, é uma alternativa mais atraente em relação à recuperação e modernização de uma ferrovia existente. O processo de investigação consiste em um método expedito de comparação de cenários através de um modelo de custos generalizado. Neste método, as características planimétricas da nova ferrovia são obtidas pela geração de um conjunto de vetores por inspeção visual no software Google Earth, posteriormente em uma plataforma de desenho assistido por computador (CAD). As características altimétricas da ferrovia são estabelecidas pela associação da geometria da via em planta com os dados altimétricos obtidos do modelo digital de terreno proposto pelo SRTM, através de um método computacional de cálculo dos gradientes da via. A partir dessas informações são estimados os volumes de movimentação de terra associados a cada cenário estabelecido. Como aplicação prática, apresenta-se a análise para um trecho de cerca de 200 km de um dos principais corredores de exportação do país entre as cidades de Santa Fé do Sul e São José do Rio Preto, no Estado de São Paulo, sob concessão da empresa América Latina Logística S.A. Os resultados da investigação permitem inferir que, apesar das limitações impostas pela técnica de modelagem utilizada, o custo total de implantação de uma nova ferrovia supera em apenas 4,3% o custo total de reforma e retificação do traçado antigo, mostrando-se como uma alternativa atraente do ponto de vista econômico, técnico e ambiental. / Investments in the Brazilian railway sector since the privatization of the railways brought a significant growth to the sector, notable primarily by the increase of cargo volume transported. However the processing capacity of the trains has been compromised by the restriction of operation speed limits, due mainly to the increased wear of the railway superstructure with the traffic increase and the geometric restriction of the track built in the late 90th century. In this context and given the sectors growth prospects over the next decade, the goal of this research is to investigate the validity of the hypothesis that the construction of a railroad with new improved design standards and greater capacity is a more attractive alternative than the repair and modernization of an existing railway. The research process consists of an expedite method of scenarios comparison through a generalized cost model. The planimetry features of the new railway are obtained by generating a set of vectors by visual inspection using the Google Earth software, which are fed into a computer aided design (CAD). The altimetry characteristics of track are set by the association of the horizontal track geometry platform with the elevation data obtained from the digital terrain model proposed by SRTM, using a computational method to calculate the gradient of the track. Earthwork volumes are calculated for each scenario based on this date. As a practical application, it presents an analysis of a segment of approximately 200 km between the cities of Santa Fé do Sul and São José do Rio Preto, São Paulo, operated by America Latina Logística S.A. The results of research may imply that, despite the limitations imposed by the modeling technique show that, the total cost of deployment of a new railway exceeds in only 4,3% the total cost of rectification and reform of the old track, and therefore constitutes an attractive alternative from the economical, technical and environmental point of view.

O Brasil tem como principal base econômica a exportação de commodities agrícolas e minerais. Esses produtos se caracterizam por possuírem grandes volumes de produção e baixo valor agregado. Diante desses fatos, as economias geradas ao longo da cadeia logística têm papel fundamental para o sucesso da comercialização destes produtos. Nesse contexto, este trabalho teve como objetivo encontrar as rotas de transportes mais econômicas para o escoamento da soja e minérios de ferro e manganês oriundos do estado do Mato Grosso do Sul com destino à exportação. Para tal foram identificados os pólos de geração destas cargas, assim como os modais de transportes existentes e futuros, terminais de transbordos e portos marítimos para exportação. Os métodos utilizados para esta análise foram a geração de cenários, modelos de custo de transporte para os modos rodoviário, ferroviário e fluvial; e sistema de informação geográfica. Os resultados obtidos neste trabalho indicam que opções de rotas com uso do modal hidroviário são as que possuem menores custos, com forte participação da hidrovia Paraguai-Paraná. Sugere-se para futuros trabalhos, a investigação da rede de transporte estudada com o uso de restrições de capacidade e também a inclusão dos custos portuários praticados nos portos marítimos de exportação. / Brazil has as the main economic base the exportation of agricultural and mineral commodities. These products are characterized by having a large quantity of production and low price. Given these facts, the saving generated along the supply chain are fundamental role in the marketing success of these products. In that context, this study aimed to find the most economic transport routes to the disposal of soybeans and iron ore and manganese from the state of Mato Grosso do Sul destined to exportation. For that were identified the places that generate as, and the transportation ways that exist up to now and the future ones, the terminals, transshipments and harbor for export. The methods used for this analysis were the generation of scenarios, models of cost of transport to the modes transport to road, rail and river, and geographic information system. The results obtained in this study indicate that options trades with the use of the waterway are those that have lower costs, with strong participation of the waterway Paraguay-Parana. It is suggested to future researches investigation of the transportation system studied the use of restrictions on capability and the inclusion of costs charged at seaports of exportation.

This dissertation considers three topics under the themes of wetland restoration, urban sprawl, and recreation demand employing spatial data and analysis. A key question addressed in the first essay is how we can identify priority areas for wetlands restoration along the Louisiana coast under the Coastal Wetlands Planning, Protection, and Restoration Act by estimating amenity values received by nearby residents from hypothetical wetlands restoration projects. The second essay evaluates the effectiveness of alternative land-use policy variables for controlling development in a sprawling metropolitan area during two extreme market conditions. The third essay estimates the effect on consumer welfare from improved satisfaction of recreation information availability.