Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016. / This dissertation presents how material properties (solids densities, particle size distributions, particle shapes and concentration) of gold tailings slurries are related to their rheological parameters, which are yield stress and viscosity. In this particular case Bingham yield stresses and Bingham plastic viscosities. Predictive models were developed from analysing data in a slurry database to predict the Bingham yield stresses and Bingham plastic viscosities from their material properties. The overall goal of this study was to develop a validated set of mathematical models to predict Bingham yield stresses and Bingham plastic viscosities from their material properties. The interaction of the non-Newtonian material properties is very complex at varying mass solids concentrations. The evaluation of these interactions in terms of constitutive equations is almost impossible and the relationship between material properties, mass solids concentration and rheology can only be modelled in a statistical manner. The validity of each model is checked to ensure that predictions and interpretations are unbiased and efficient. This is done by comparing the resulting models to experimental data generated from test work. An in-depth analysis was conducted to see the interrelationship between the material properties and how they affect the yield stress and viscosity values.

Orientador: Iscia Teresinha Lopes Cendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T18:59:17Z (GMT). No. of bitstreams: 1 Rocha_CristianedeSouza_D.pdf: 3551438 bytes, checksum: f6ebb3553396723b256a55fd2fae1034 (MD5) Previous issue date: 2011 / Resumo: A construção de perfis de expressão usando microarrays tornou-se um método amplamente utilizado para o estudo dos padrões de expressão gênica. Estes estudos produzem uma grande quantidade de dados que faz com que a análise seja complexa e demorada. À medida que a qualidade dos arrays se torna mais confiável com a introdução dos arrays industriais, a quantidade de dados gerados aumenta e o ponto crítico dos experimentos, passa a ser garantir uma boa análise de bioinformática. Para facilitar esta análise desenvolvemos um pipeline que executa todos os passos de processamento de dados, tais como a correção de background, controle de qualidade, normalização, detecção de genes diferencialmente expressos e análises de clusterização. Além disso, nossa ferramenta permite a escolha de diversos testes estatísticos paramétricos e não paramétricos e também faz mineração de dados, buscando as informações relevantes dos genes e gerando links para diversos bancos de dados públicos. A função principal desta ferramenta é auxiliar pesquisadores que trabalham com microarrays, pois ela facilita a análise da grande quantidade de dados que este tipo de experimento gera, podendo fornecer uma análise personalizada com a escolha dos testes estatísticos e valores de corte de acordo com os parâmetros que o usuário julgar mais apropriado para as condições de seu experimento. A facilidade de uso e aplicações múltiplas implementadas apresentadas nesta ferramenta são inéditas e esperamos contribuir de maneira significativa para estimular e facilitar o uso dos estudos de expressão em larga escala / Abstract: Expression profile using microarrays has become a widely used method for studying gene expression patterns. These studies produce a large amount of data which makes the analysis complex and time consuming. As the arrays' quality becomes more reliable the critical point remains the bioinformatics tools used to process and analyze the data generated in these large experiments. Therefore, we aimed to develop a pipeline that runs all the steps of data processing such as background correction, quality control, normalization, detection of differentially expressed genes and clustering analysis. In addition, our tool allows the choice of several parametric and non-parametric tests to be used for group comparisons. Furthermore, it can be used for data mining, searching for relevant information of genes as well as creating links to various public available databases. The main goal of this tool is to provide researchers working with microarray data a user friendly tool which includes customized statistical analysis. This type of research tool with this many function is not previously available and we hope to contribute to make large scale expression studies easier and faster, specially for researchers that are starting to use this type of technology / Doutorado / Neurociencias / Doutor em Fisiopatologia Medica

M.Ing. / This thesis considers in detail the applicability to hydro power systems of the theories of steady and unsteady flow in pipelines. In doing so.it highlights some of the shortcomings of these theories. An attempt is made by way of experimentation on a high pressure pipeline, to model some of the conditions which could occur in a full size future hydro power system. These experiments provide some quantitative data about the performance of some typical hydro power components such as pipes, orifices and valves, under steady and unsteady conditions. A computer program is included which was used to provide theoretical data to compare with the experimental results. The program was found to be limited in its capacity to provide accurate simulation of the experimental pipeline, but this was thought to be due to the pipeline not correctly modelling a hydro power system. Conclusions presented in this thesis will be of assistance to designers of future hydro power systems and to researchers continuing this work.

Laboratory tests were conducted to determine the head losses in wyes and manifolds of conventional type, both with and without an internal tie-rod at the theoretical centre of the wye. These wyes and manifolds, having 45°, 60° and 90° subtending angles of the wyes, were symmetrical about the longitudinal axis of the main pipe. The apparatus and method of testing used in the tests are described. The experiment spans a range of Reynold's numbers from 85,000 to 420,000 in the influent main pipe. The analysis of experimental data is based on the energy equation of Bernoulli for the one-dimensional condition. The results of the tests are given in both tabular and graphical form. It appears that the coefficient of the form loss (the ratio of the form loss of a wye or manifold to the velocity head in the main pipe) is a function of the proportional flow of water through the branches, the size of the tie-rod used and the subtending angle of the wye. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

At present the majority of wood-stave pipelines are supported on rigid cradles which bear on the lower 45% of the pipe circumference. The accepted method of analysis, developed by Regnell, completely ignores the stress concentrations induced in the staves just above the cradle tips. In this work, a full ring is proposed to distribute the support reaction to all staves and minimize deflections from a circular profile. From a consideration of equilibrium and stress-displacement relations for a stave element two fourth-order partial differential equations in terms of the radial and tangential displacements of the element are developed. Trigonometric series are applied to their solution. The support ring displacements are similarly described in series form. A study of the compatibility of ring and stave deflections removes the indeterminacy and all stress resultants, as functions of the ring or stave deflections, are then available from back-substitution. The formulas established are sufficiently complex that access to an electronic computer is a great practical advantage. In a numerical example, the effects of modifying the ring stiffness, hydraulic head, and the circumferential stiffness of the stave cylinder are investigated. The non-linear influence of ring and band tensions on the deformed shape of the structure is included. Design considerations are briefly discussed. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Bibliography: pages 81-85. / This thesis addresses some of the issues involved in using numerical methods to simulate the laying of an offshore pipeline, the objective being to contribute to the expertise of the South African offshore technology. Of particular interest is the prediction of the stresses in the pipe during such an event. The thesis concentrates on the use and suitability of the finite element method to simulate the important aspects of the pipelaying problem. ABAQUS, a nonlinear general purpose finite element code, was chosen as numerical tool, and nonlinear effects such as geometry and drag, as well as contact and lift-off at the boundaries, are included in the models. The analysis is performed in two parts: in the static analysis the displaced equilibrium position of the pipeline under self weight, buoyancy and barge tension is sought, whilst the response due to wave action and barge motion is of interest in the dynamic analysis. Numerical experiments show the suitability of ABAQUS to model the behaviour of slender structures under both static loads and dynamic excitations.

The collapse-behaviour of pipes was to be studied by use of Finite Element modelling.Existing analytical expressions for collapse were evaluated and especially the one used inDNV-OS-F101 was decided to be studied in comparison with FE-model results.Parameters that may influence the collapse capacity and are not included in the analyticalexpressions –flattening, peaking, eccentricity, local wall thickness variation, materialstress-strain curve, residual stresses - were defined and explained. A model was built inthe Finite Element software package Abaqus v6.9.1 and several articles on collapsetesting used to verify it. The aforementioned parameters were studied by use ofsensitivity studies and the results shown and discussed. Effective thickness definitions foruse in the DNV-formula and the DNV-yield stress criterion were discussed in the contextof the results. The results seemed to indicate that the transition between the elastic andplastic range of the material stress-strain curve was of great importance. The results werediscussed in the context of the different collapse-related parameters defined beforehandand some concluding remarks were made on possible further work related to thesefindings.

Underground pipelines are used in various process piping systems to transport gasses or fluids and are usually subjected to the effects of external corrosion. Corrosion can be defined as the deterioration of a material due to a reaction with its environment or the destruction of the material by means that are not mechanical (Fontana and Greene, 1967:2). External corrosion, due to the interaction between the pipe and the soil, is generally a slow process and the corrosion rate is influenced by a variety of external factors. Some of these factors include the ambient pH and salinity, the presence of moisture and bacteria, temperature, the electrical potential difference between the pipe and other structures and the implementation of preventative measures (such as cathodic protection and wrapping). Although the external corrosion of underground pipelines is generally a slow process in mild environments, pipe degradation as a result of external corrosion remains one of the prevalent reasons for the failure of underground pipelines. As with many mechanical systems that are prone to fail at one time or the other, the high costs involved with unforeseen failure necessitate some quantitative (or qualitative) indication of the condition of the pipe system. Some of the costs that can be expected as a result of unforeseen pipeline failure are, amongst others: • costs as a result of the failure of dependent systems; • costs as a result of the loss of production; • costs as a result of the loss of product (in distribution networks); • the cost of unscheduled maintenance (logistical costs); • costs as a result of damage to public property; • fines imposed by customers (in distribution networks); • costs related to pollution control, and • the loss of life The single most important parameter associated with the condition of a system is its profitable remaining life. This is the time during which a sub-system contributes to the well-being of a larger system and the organisation. Therefore, it is necessary to determine, with reasonable accuracy, the extent of the remaining life of a system so that managerial decisions (i.e. investments, cash-flow analyses, maintenance task scheduling and replacement programmes), based on this figure, can be made. Done correctly, this can directly lead to a decrease in maintenance costs and subsequently to an increase in profit. The extent of a corrosive attack on the pipeline might be highly localised or might be fairly uniform over the length of the installation. The fact of the matter is that, since the pipe is buried, it is very difficult to quantify the external damage caused by corrosion. A variety of techniques are in use to survey pipelines and detect anomalies. However, for large pipelines, most of these techniques are either inefficient or too expensive. There will always remain some uncertainty regarding the integrity of the pipeline. The work presented in this study is explained with valid generic examples and aims: 1. to provide the reader with sufficient background information so that the need for determining the integrity of a pipeline becomes apparent; 2. to indicate why a reliability-centred approach is necessary (Chapter 1); 3. to explain the basic principles of corrosion and the electrochemical nature of corrosion (Chapter 2); 4. to indicate areas, based on the basic principles of corrosion, where severe corrosion can be expected (Chapters 2 and 7); 5. to provide and elaborate on information regarding pipe surveillance techniques that are currently available (Chapter 3); 6. to establish the criteria for pipeline failure, in the form of a limit state Junction, for pipes that are subjected to near-constant internal pressures (static failure domain) as well as for pipes subjected to varying internal pressures (fatigue domain) (Chapters 5 and 6); 7. to indicate the sensitivity of the fatigue domain solution to changes in the system variables and to indicate that a significant reduction in the system variables does not necessarily reduce the solution accuracy (Chapter 6), and 8. to integrate the above-mentioned into a practical and workable guideline that can be used to determine the remaining life of an underground pipe network (Chapter 7). / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2002. / Mechanical and Aeronautical Engineering / unrestricted

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This thesis presents a computational study to examine lateral impact behavior of pressurized pipelines and to determine influence of internal pressure on the impact behaviors of pipelines. More than 300 numerical simulations were carried out on mild steel pipe models with different internal pressure levels and were struck at the mid-span and at the one quarter span positions. The computational results for the first time systematically revealed the effects of internal pressure, impact position, and outside diameter on the lateral impact behavior of the pipeline models. It inspects effects of important parameters such as the outside diameter and internal pressure. Quartic polynomial functions are applied to formulate the maximum crushing force (F), permanent displacement (W), and absorbed energy (E) of the pressurized pipelines during the impact problem. Response surfaces are plotted based on the generated quartic polynomial functions and the quality (accuracy) of those functions are verified through several techniques.