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Please read the abstract in the section 00front of this document / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

The research presented in this thesis studies the effects of foamed bitumen on the deformational behaviour and performance of pavement materials. The research was conducted in the laboratory and the field, using specific New Zealand materials. The aggregate used is a blend of a coarse aggregate imported from the Auckland region with a crushed dust from the Canterbury region. The bitumen selected for the study is an 80/100 bitumen grade, and the active filler was a Portland Cement, both commonly used for foamed bitumen stabilization in New Zealand. In the laboratory, samples of mixes with different foamed bitumen content were tested under various loading and stress conditions to investigate the effects of foamed bitumen on the deformational behaviour of the mix. The tests performed were: Indirect Tensile Strength (ITS), Indirect Tensile Resilient Modulus (ITM), Repeat Load Triaxial compression (RLT) and Monotonic Load Triaxial compression (MLT). Preliminary ITS and RLT tests conducted on mixes with 1% and 0% cement, at different foamed bitumen contents, indicated that mixes without cement performed poorly compared to the mixes with 1% cement. Therefore, the rest of the laboratory study was on mixes with 1% cement. ITS tests were conducted on 150 mm specimens prepared with 0% 1%, 2%, 3% and 4% bitumen content, with a common 1% cement. Results indicated that foamed bitumen increases the ITS values of the mix, up to an estimated optimum of 2.8% bitumen content. Similar trends were obtained with ITM tests, in which a diametrical load pulse was applied on 150 mm specimens, showing an estimated resilient modulus peak near to 2.8% bitumen content. RLT specimens were prepared at 0%, 2% and 4% bitumen content, at two compaction efforts, creating specimens at low and high bulk density. Permanent deformation RLT tests involved the application of seven stages of 50,000 load cycles each (4 Hz), with increasing deviator stress (from 75 kPa in the first stage, up to 525 kPa in the seventh stage) and at constant confining pressure of 50 kPa. Results of RLT permanent deformation tests indicated that the increase in the foamed bitumen content resulted in an increase in the permanent deformation of the material. MLT tests were conducted on specimens at 0%, 2% and 4% bitumen contents, at two compaction efforts, creating specimens of low and high bulk density, at confining pressures ranging from 50 kPa to 300 kPa, with a deformation rate of 2.1% per minute. Results indicated that the effect of foamed bitumen was a reduction of the peak vertical stress, or a reduction in the peak strength. The peak stresses obtained in MLT tests were plotted in stress diagrams, and the failure was approximated as linear function of the confining stress. The fundamental shear parameters (angle of internal friction and apparent cohesion) were estimated, and results indicated that foamed bitumen has no apparent effect in cohesion but does reduce the angle of internal friction. The reduction of the angle of internal friction explains the general trends observed in the laboratory, that on one hand the compressive strength decreases with increasing bitumen content, but on the other hand, the tensile strength increases up to an optimum. A full-scale experiment was carried out using an accelerated testing of foamed bitumen pavements at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF). In the full-scale experiments, the same materials that were tested in the laboratory (aggregates, bitumen, cement) were used to construct six different pavement sections, each with different contents of bitumen and cement. Three were constructed using foamed bitumen contents of 1.2%, 1.4% and 2.8% respectively, plus a common active filler content of 1.0% cement. Two more pavements were constructed adding cement only (1.0%), and foamed bitumen only (2.2%). In addition, one control section with the untreated unbound material was tested. Strains were collected using a 3D Emu soil strain system installed in each pavement section. The curing time between construction and pavement loading was approximately three months. The pavement response, such as surface deformation (rutting), surface deflections and strains were periodically recorded during the execution of the test. The strains were collected at different depths by using an array of Emu strain gauges. Deflections were recorded using both a Falling Weight Deflectometer (FWD) and CAPTIF Beam deflectometer, which is a modified Benkelmann beam. A total number of approximately 5.6 million equivalent standard axles were applied on the pavement sections. The rutting measured in the sections stabilised with foamed bitumen and cement was the lowest, showing that the addition of foamed bitumen significantly improved the performance of materials with 1% cement. The sections stabilised with cement only, foamed bitumen only, and the control untreated section showed large amounts of rutting and heaving by the end of the test. Deflection measurements showed that the effect of foamed bitumen content is a reduction of pavement deflections, with the lowest deflection measured in the section stabilised with 2.8% bitumen and 1% cement. The elastic pavement strains showed that foamed bitumen reduced the tensile strains in the basecourse but did not have a significant effect on vertical compressive strains. During the construction of pavements, material samples were taken for ITS and RLT testing. Results indicated that the highest ITS was measured in the section with 2.8% foamed bitumen content and 1% cement, and the ITS in the section without cement and foamed bitumen only was about 4-5 times lower than the ITS measured in specimens with cement. RLT specimens without cement performed poorly in comparison with the specimens with 1% cement. The specimens with 1% cement showed higher permanent deformation with increase in the foamed bitumen content, supporting the results from the previous laboratory study. To interpret and relate the results observed in the laboratory and the field, stress path analysis was used, in which the stress ratio of the foamed bitumen layers was calculated at different depths. The analysis showed that foamed bitumen content decreases the maximum stress ratio, hence reducing the proximity to failure and relative damage of the layer. Three-dimensional and two-dimensional finite element modelling of the CAPTIF pavements, were used to further investigate the stress and strain fields induced by the loading and to explain the pavement performance observed in the full-scale experiment.

Introduction: Innovations in modern medicine have led to the development of many effective laboratory tests for diagnosis and monitoring of disease. However, research suggests that 20-50% of tests may be inappropriately ordered. Test-ordering intervention development experts i.e. those staff at individual institutions who are tasked with designing different approaches to improving test-ordering practice, often have large datasets on the test-ordering practices within their jurisdiction as part of clinical care, but often have no clear guidance on how to choose which tests are worthy of intervention. These staff can include both clinicians and knowledge translation experts working in separately or in tandem to improve test-ordering behaviours at their institutions. The overall aim of this research is to build a prioritization framework to assist healthcare organizations in deciding which tests are worth targeting for intervention. Methods: The first stage of this project was a scoping review of the literature, the purpose of which was to determine the factors and processes used by intervention developers to choose which tests to target for intervention. Identification of these articles allowed for the descriptive analysis of the factors and processes reported in making the test-ordering decisions. The second stage involved semi-structured interviews with intervention development experts and contains information on their experiences with measuring and prioritizing among factors, as well as which processes they found to be most effective in making the decision on which tests to target for intervention. Results: By exploring all relevant guideline statements and related empirical studies, we gathered a wide range of factors to consider when deciding which test(s) to target for intervention. Overall, we identified 18 factors in our review and 30 in our interviews, highlighting the potential complexity of these decisions. While our studies were not the first to demonstrate that targeting tests is complex and that many factors must go into the decision of deciding which tests to target, our work has identified the most comprehensive range of factors available. We also explored processes reported by the studies that led to these decisions. Of the nine processes identified in our review, some were identified in a majority of cases (literature review, followed by clinical standard-implicit and consensus process), and other processes far more infrequently. Our interviews with relevant stakeholders demonstrated that the interviewees used 18 unique processes to decide which tests to target for intervention and helped to prioritize among the processes that are most effective in making these decisions. Conclusion: The current work prepares the way to develop a framework designed to help intervention developers choose which tests can most efficiently result in improved test-ordering processes. After additional interviews to ensure saturation of themes, we will be able to proceed with framework development, perhaps involving a consensus process of all relevant stakeholders. We hope to widely distribute our framework to assist intervention development experts working in a wide variety of milieus to help them decide which tests are worth targeting for intervention such that their respective institutions can provide the highest quality of care to patients.

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Predicting tire performance on soft, fine-grained soils is required for many off-road explorations in the military, mining, agricultural, and earth-moving sectors. However, the mobility in deformable material is extremely challenging, especially in the presence of water. Although there is a significant amount of research on terrains such as sands, there is a lack of research on fine-grained soils. This research is part of a bigger project that presents a novel approach to improve the mobility of off-road vehicles on wet deformable soils. The approach integrates experimental data from small-scale soil testing, large-scale soil-tire interaction testing, and advanced physics-based numerical simulation techniques. In particular, this thesis attempts to characterize the clay-tire interface by conducting large-scale direct shear tests. In addition to clay-tire contact friction, the properties and strength parameters of the soft clay are determined by conducting various index properties and advanced tests. The testing program accounts for different stresses, loading conditions, and boundary conditions, decided taking into account real field conditions. The results from all these experiments will be used to calibrate and validate the material constitutive models required for the development of a mobility predictive numerical model. Overall, this study contributes to the development of more advanced and accurate terramechanics models that involve deformable terrains like soft clays. / Master of Science / The prediction of Vehicle mobility on soft, fine-grained soils is challenging due to the impact of soil behavior on mobility, which is not taken into account by traditional vehicle simulation software. However, as off-road exploration and resource extraction become increasingly important, particularly in military, agricultural, and earth-moving sectors, the study of vehicle mobility on deformable soils is inevitable. The difficulty in predicting tire performance on soft, fine-grained soils is due to the lack of proper experimental data and numerical modeling techniques that accurately characterize the interaction between soil and vehicle tires, known as "terramechanics." The study forms a constituent part of a broader project, which aims to integrate the experimental research data from small-scale soil testing, large-scale soil-tire interaction testing, and advanced physics-based numerical simulation techniques. The main contribution of this study is to investigate soil-tire interaction to determine the contact friction between the soil and tire by conducting large-scale direct shear tests. It also involves conducting basic index properties tests and advanced shear strength and compression tests. The results from all these tests contribute to developing more accurate soil-tire interaction models in terramechanics. Given the scarcity of research on large deformable terrains like soft clays, this study can make a significant contribution towards developing more advanced and accurate terramechanics models that involve deformable terrain, which can be useful in various applications.

With increasing world population, demand for underground construction is expected to accelerate in the future. Design of tunnels in rock is still largely empirical, while rock failure in underground mines and tunnel construction continues to claim lives. A seismic method to aid in increasing safety during excavation is tomography. Seismic tomography is a non-invasive technique to map the stress changes induced by mining ahead of the active face. Seismic tomography maps the velocity distributions of elastic waves traveling through a rock mass. The velocity distributions mapped in the tomograms can relate to anomalies in the rock such as fracture zones and highly concentrated stresses. In order to develop a relationship between stress and elastic wave velocity, laboratory tests in a controlled environment are required. In the current study tomographic tests were conducted on Berea sandstone and Five Oaks limestone samples. The stress redistribution in the sandstone samples could be imaged by mapping velocity distributions. On an unconfined test the sandstone sample acted much like a coal mine pillar where the stress redistributes to the least confined area. On a sandstone test where the sample was indented by a steel platen the velocity contrast was seen directly under the load and the velocity remained almost unchanged over the rest of the sample. For the limestone tests, the stress redistribution could not be mapped in the tomograms. The ability to map the stress distribution in the tomograms were attributed to the elastic and non-elastic characteristics of the stress-strain curve. For sandstone, a porous rock, the stress redistribution could be mapped and for limestone, a stiff rock, the stress redistribution could not be mapped. A field data acquisition system to apply tomography to ground control problems in a mine was designed and calibrated. Data acquisition hardware were assembled and programmed in LabVIEW to collect seismic data in a mine. The design of a geophone array that will fit into a miniature 5.08 cm (2 in) diameter borehole is presented. / Master of Science

Doctor of Philosophy / Department of Civil Engineering / Stefan A. Romanoschi / Permanent deformation (rutting) is the most critical load-associated distress that develops on asphalt pavements significantly affecting their performance. Past research work focused on estimating permanent deformation of asphalt mixes using empirical prediction models or prediction models based on linear elastic material models. In recent years, mechanistic and mechanistic-empirical prediction models have been developed to take into account the behavior of asphalt material (viscoelastic, viscoplastic or elasto-visco-plastic). This research project aims to evaluate existing mechanistic models that predict permanent deformation (rutting) in asphalt mixes by comparing computed permanent deformation to that measured in a full-scale accelerated pavement test. Six pavement sections were constructed in the Civil Infrastructure Systems Laboratory (CISL) of Kansas State University with six different asphalt mixes. The sections were loaded with up to 700,000 load repetitions of a 22,000lb single axle. The transverse profiles at the pavement surface were measured periodically. For material characterization, asphalt mix samples fabricated in the laboratory, were subjected to dynamic modulus (|E*|), static creep - flow time (Ft), dynamic creep - flow number (Fn), triaxial and uniaxial strength tests, repetitive shear at constant height (RSCH) and frequency sweep at constant height (FSCH). The finite element software, Abaqus, was used to simulate and evaluate four permanent deformation prediction models, which are: creep model, elasto-visco-plastic model, viscoelastic model and Drucker-Prager model. The predicted permanent deformation was then compared to permanent deformation measured in CISL for the six of asphalt pavement sections. It was found that, with some improvements, creep and elasto-visco-plastic models could be used to predict permanent deformation in asphalt mixes. The viscoelastic model greatly under-predict permanent deformation, and the Drucker-Prager model with hardening criteria over predicts permanent deformation as compared to values measured in CISL.

A pluralização dos atendimentos e sua garantia de realização em todos os níveis de atenção conforme os princípios estabelecidos pelo Sistema Único de Saúde (SUS) fizeram com que o atual cenário da saúde pública ganhasse grande complexidade envolvendo o financiamento e suporte para a manutenção desses serviços. Nesse contexto, alguns trabalhos na literatura relatam um excesso no uso desses recursos diagnósticos, que ocorre muitas vezes desnecessariamente, aumentando a chance de riscos à saúde do paciente e sobrecarregando demasiadamente o orçamento financeiro dos serviços de saúde, em particular o hospital. O que ocorre muitas vezes é a falta de critério nas solicitações e problemas de interpretação dos exames, desconhecimento sobre custos dos procedimentos realizados, entre outros fatores que se mostram mais elevados dependendo da complexidade do ambiente do serviço de saúde, do quadro clínico do paciente e da experiência do profissional médico. Dessa forma, é escopo desse projeto avaliar os resultados qualitativos, quantitativos e os custos dos principais parâmetros laboratoriais de exames solicitados nas áreas clínicas de Cardiologia e Endocrinologia da divisão de Clínica Médica do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP-USP), e sua correlação com o que está descrito na literatura, objetivando identificar se o uso dos recursos diagnósticos estão sendo utilizados de forma racional e coerente. Para a realização desse estudo, foi realizada uma análise retrospectiva dos prontuários de pacientes pelo sistema HC-Athos em regime de primeira consulta e retorno, e também, de informações e metodologias relacionadas ao custeio de exames laboratoriais junto ao Centro de Custo do HCFMRP-USP, nas áreas clínicas de Endocrinologia, ambulatórios (ENA, END, ETP) e Cardiologia (CAA), no período de Julho de 2012 à Julho de 2013. Observando a análise dos elementos dos exames em ambos amulatórios, os resultados foram próximos: em Cardiologia a taxa média de elementos alterados foi de 20,79%, ao passo que em endocrinologia, o valor médio foi de 22,39%. Dessa forma, com base no que está descrito por alguns autores na literatura, esses achados podem sugerir a possibilidade de haver requisição sem necessidade dos exames laboratoriais. Em relação ao estudo de custos, observamos que existe uma diferença significativa para a relação: valor real gasto (HCFMRP-USP)/valor recebido(SUS). Na cardiologia onde o déficit foi mais elevado, 39,45%, contra os 12,80% observados em endocrinologia. Analisando cada exame separadamente nos dois ambulatórios, observa-se que há situações onde a relação do custo entre real gasto/valor recebido chega a ser bem discrepante, como a variação de 51 à 60% em exames como hemograma, uréia, creatinina, T3 e T4 total. Analisando esses achados, podemos concluir que há de certa forma um subfinanciamento do SUS em relação aos procedimentos laboratoriais realizados pelos hospitais. Com exceção de alguns exames, que isoladamente mostraram relação positiva, o saldo final considerando os exames mais comumente realizados foi negativo, ou seja, nos exames de maior demanda e faturamento, o resultado mostrou se preocupante. / The increasing demand of medical care and its realization warranty on all levels of care according to the principles established by the Unified Health System (SUS) made the current situation of public health gain great complexity involving funding and support to maintain these services. In this context, some studies in the literature report an excess in the use of these diagnostic tools, which is often unnecessarily, increasing the chance of risks to the health of the patient and overly burdening the financial budget of health services, particularly the hospital. What often happens is the lack of criteria in requests and problems of interpretation of the tests, ignorance about costs of the procedures performed, and other factors which show higher depending on the complexity of the health care environment, the patient\'s condition and the doctor\'s professional experience. Thus, is scope of this project, evaluate the qualitative and quantitative results, and the costs of major laboratory parameters tests requested in the clinical areas of Cardiology and Endocrinology of the University Hospital, Faculty of Medicine of RibeirãoPreto, University of São Paulo (HCFMRP-USP), and its correlation with what is described in the literature in order to identify whether the use of diagnostic resources are being used in a rational and coherent manner. To carry out this study, a retrospective analysis of medical records of patients at HC-Athos system in first consultation and return was carried out, and also, information and methodologies related to the cost of laboratory tests by the HCFMRP- USP Cost Center in the clinical areas of Endocrinology, outpatient clinics (ENA, END, ETP) and Cardiology (CAA) in the period July 2012 to July 2013. Noting the analysis of elements in both outpatient examinations, the results were similar: in Cardiology the average rate of change elements was 20.79%, while in endocrinology, the average value was 22.39%. Thus, based on what is described by some authors in the literature, these findings may suggest the possibility of request without laboratory tests. Regarding the study costs, we note that there is a significant difference to the relationship: real amount spent (HCFMRP- USP) / cash received (SUS). In cardiology where the deficit was higher, 39.45%, against 12.80% observed in endocrinology. Analyzing each exam separately in the two clinics, it is observed that there are situations where the ratio of the cost of real expenditure / amount received comes to be well outlier, as the range of 51 to 60% in exams such as blood count, urea, creatinine, T3 and T4 total. Analyzing these findings, we conclude that there is something of a SUS underfunded in relation to laboratory procedures performed by hospitals. Except for some tests, which alone showed a positive relationship, the final balance considering the most commonly performed tests was negative, that means, in higher demand and revenue tests, the results showed worrying.

Track stiffness is the one of the most critical parameters of the track structure. Its evaluation is important to assess track quality, component performance, localised faults and optimise maintenance periods and activities. Keeping the track stiffness within acceptable range of values is connected with keeping the railway network in a satisfactorily performing condition, allowing thereby upgrade of its capacity (speed, load, intensity). Current railway standards are changing to define loading and stiffness requirements for improved ballasted and ballastless performance under high speed train traffic. In recent years various techniques have been used to measure track deflection which have been also used to validate numerical models to assess various problems within the railway network. Based on recent introduction of the Video Gauge for its application in the civil engineering industry this project provides the proof of effective applicability of this DIC (Digital image correlation) tool for the accurate assessment of track deflection and the calculation of track stiffness through its effective applicability in various track conditions for assessing the stiffness of various track forms including track irregularities where abrupt change in track stiffness occur such as transition zones and rail joints. Attention is given in validation of numerical modelling of the response of insulated rail joints under the passage of wheel load within the goal to improve track performance adjacent to rail joints and contribute to the sponsoring company s product offering. This project shows a means of improving the rail joint behaviour by using external structural reinforcement, and this is presented through numerical modelling validated by laboratory and field measurements. The structural response of insulated rail joints (IRJs) under the wheel vertical load passage is presented to enhance industry understanding of the effect of critical factors of IRJ response for various IRJ types that was served as a parametric FE model template for commercial studies for product optimisation.