This dissertation develops a new concept for performance-based monitoring (PBM) of instrumented buildings subjected to earthquakes. This concept is achieved by simultaneously combining and advancing existing knowledge from structural mechanics, signal processing, and performance-based earthquake engineering paradigms. The PBM concept consists of 1) optimal sensor placement, 2) dynamic response reconstruction, 3) damage estimation, and 4) loss analysis. Within the proposed concept, the main theoretical contribution is the derivation of a nonlinear model-based observer (NMBO) for state estimation in nonlinear structural systems. The NMBO employs an efficient iterative algorithm to combine a nonlinear model and limited noise-contaminated response measurements to estimate the complete nonlinear dynamic response of the structural system of interest, in the particular case of this research, a building subject to an earthquake. The main advantage of the proposed observer over existing nonlinear recursive state estimators is that it is specifically designed to be physically realizable as a nonlinear structural model. This results in many desirable properties, such as improved stability and efficiency. Additionally, a practical methodology is presented to implement the proposed PBM concept in the case of instrumented steel, wood-frame, and reinforced concrete buildings as the three main types of structural systems used for construction in the United States. The proposed methodology is validated using three case studies of experimental and real-world large-scale instrumented buildings. The first case study is an extensively instrumented six-story wood frame building tested in a series of full-scale seismic tests in the final phase of the NEESWood project at the E-Defense facility in Japan. The second case study is a 6-story steel moment resisting frame building located in Burbank, CA, and uses the recorded acceleration data from the 1991 Sierra Madre and 1994 Northridge earthquakes. The third case is a seven-story reinforced concrete structure in Van Nuys, CA, which was severely damaged during the 1994 Northridge earthquake. The results presented in this dissertation constitute the most accurate and the highest resolution seismic response and damage measure estimates obtained for instrumented buildings. The proposed PBM concept will help structural engineers make more informed and swift decisions regarding post-earthquake assessment of critical instrumented building structures, thus improving earthquake resiliency of seismic-prone communities.

Self-compacting concrete (SCC) offers rational and fast casting process since it merely has to be poured, or pumped, into the formwork without any compaction work needed. But this can be at the cost of high form pressure. However, reported results show that SCC can act thixotropically, i.e., build up a structure at rest, and this can reduce the form pressure considerably. Thus, in order to utilise the favourable possibilities to increase effectiveness without risking form collapses, the need arises for deeper and broader understanding of the mechanisms behind this thixotropic behaviour. Methodologies have been developed for the characterisation and measurement of the structural build-up at rest, both for the fluid (micro mortar) phase and the concrete itself. Hypotheses state that thixotropic mechanisms originate within the colloidal domain and, thus, motivate studies on the fluid phase comprising this domain. The stress-strain methodology is based on the hypothesis stating that the magnitude of the structure is represented by the maximum elastic stress the fresh material can withstand before the structure breaks. An instrumented steel tube is used to simulate various casting heights and rates. Results show that both micro mortar and SCC are thixotropic and this behaviour is influenced by every measure taken influencing the interparticle colloidal forces. The time-dependent structural build-up of SCC is a function of an irreversible structure (slump-loss) and a reversible, thixotropic structure. There is apparently a threshold value of the structural build-up necessary to reach before obtaining any significant form pressure reduction. Housing SCC´s, with W/C = 0.58, show low degree of structural build-up and pressure decrease while civil engineering SCC´s can show the opposite, but this often at the cost of slump-loss. Recommendations are presented and for the nearest future, suggesting a conservatism regarding design of formwork systems when SCC is used. If the behaviour of a SCC is known it should be used to optimise the formwork. If not, calculating with hydrostatic pressure should be done or the knowledge missing should be gained by using this methodology. A third option is given and this is to monitor the form pressure in real time using sensors. / QC 20100812

Made available in DSpace on 2015-09-21T17:22:58Z (GMT). No. of bitstreams: 2 12.pdf: 27064206 bytes, checksum: 1c1c026fdfb1fb76bcd2dde6a22a8708 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2013 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Fármacos/Farmanguinhos. Rio de Janeiro, RJ, Brasil. / Os fármacos raras vezes são administrados isoladamente. Normalmente fazem parte de uma formulação combinada com um ou mais agentes não medicinais (excipientes farmacêuticos) de onde resultam formas farmacêuticas de vários tipos. Ocupando a posição como a mais utilizada entre elas estão os comprimidos, por suas várias vantagens frente às demais. Os lubrificantes, antiaderentes e deslizantes fazem parte de uma das classes de excipientes utilizados para a formação de um comprimido. São insumos capazes de proporcionar fluidez, melhor escoamento e anti-aderência às misturas de materiais durante as fases de fabricação, principalmente na compressão. Para o controle desta fase há máquinas compressoras que dispõem de softwares capazes de monitorar todo o processo e gerar dados para auxiliar na sua melhoria. O objetivo deste trabalho foi realizar uma avaliação dos lubrificantes farmacêuticos nas propriedades mecânicas de comprimidos utilizando-se compressora rotativa instrumentada (Fette 102i). Assim, foi feito um estudo para a avaliação dos lubrificantes utilizando duas formulações e diversos parâmetros previamente definidos. Em conjunto foi realizado um trabalho para o entendimento dos parâmetros utilizados pela Fette 102i e dos gráficos gerados através do Galenic Software. Com relação ao estudo dos lubrificantes, utilizando a metodologia proposta foi possível avaliá-los funcionalmente utilizando os dados gerados pela Fette 102i e pelos resultados obtidos por seus comprimidos e misturas. Notou-se uma grande diferença entre os lubrificantes. Entre os estearatos de magnésio analisados, o excipiente do fabricante 2 possui um poder de lubrificação maior do que os lotes do fabricante 1. Estes entre si possuem comportamentos muito próximos, diferenciando-se nos resultados de desintegração quando fabricados na base 07. O monoestearato de glicerila e o estearil fumarato de sódio apresentaram um poder de lubrificação inferior aos demais, com isso influenciaram minimamente na compressibilidade dos materiais. Entre os tipos de estearato, o de sódio foi o que se diferenciou dos estearatos de zinco e magnésio, sendo que esses dois últimos influenciaram mais negativamente na compressibilidade do que o primeiro. Notou-se também que ao utilizar o fosfato de cálcio diidratado a 30% na formulação a força de extração aumenta com o aumento da força de compressão pela formação de áreas não lubrificadas. Já a caracterização não foi conclusiva para os materiais analisados por conta da complexidade química dos mesmos. / The active pharmaceutical ingredients are rarely administered alone. Usually they are part of a formulation with one or more pharmacologically inactive substances (pharmaceutical excipients) which result in various dosage forms. The most commonly dosage forms are the tablets, because of their advantages over the others. Lubricants, antiadherents and glidants are one of the classes of excipients used for tablets. These materials are capable of providing flowability, improving flow and anti-adhesion of materials mixed during the manufacturing phases, mainly during compression. The tablet presses have adequate softwares to monitor and control the entire process and generate data to assist in their improvement. The aim of this study was an evaluation of lubricants on the mechanical properties of pharmaceutical tablets using an instrumented rotary tablet press (Fette 102i). Thus, a study was done to evaluate the pharmaceutical lubricants using the formulations and parameters previously defined. Together with this study it was conducted a work to understand the parameters used by Fette 102i and graphs generated by Galenic Software. Regarding the study of lubricants, the use of the proposed methodology can assess them functionally using the data generated by Fette 102i and the results obtained by their tablets and other products. A big difference between the lubricants was observed. Among the magnesium stearate samples analyzed, the excipient of manufacturer 2 has a higher lubricity than the first batch of the same manufacturer. The stearates of the manufacturer 1 have very similar profiles, but differing results in disintegration when manufactured in base 07. The glyceryl monostearate and sodium stearyl fumarate presented lubrication potential lower than the others, minimally affecting the compressibility of the material. Sodium stearate was different from zinc and magnesium ones, where the last two influenced more negatively the compressibility than the first one. It was also noted when using the calcium phosphate dihydrate 30% in the formulation, considering that the extraction force increased with increasing compression force for the formation of non-lubricated areas. The characterization performed was inconclusive for the materials analyzed because of the chemical complexity of these materials.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A produÃÃo de enzimas por fermentaÃÃo semi-sÃlida (FSS) à influenciada por diversos fatores de cultivo que afetam o crescimento microbiano e a produÃÃo de metabÃlitos. O estudo de fatores como aeraÃÃo e umidade do ar torna-se indispensÃvel para a otimizaÃÃo deste bioprocesso. Neste contexto, o presente trabalho teve como objetivo avaliar a produÃÃo de protease pelo fungo Aspergillus oryzae CCBP001 por FSS em biorreator de colunas. A FSS para a produÃÃo de protease utilizando o fungo filamentoso A. oryzae CCBP 001 ocorreu em condiÃÃes dinÃmica e estÃtica, visando observar o mÃtodo que apresentou a maior produÃÃo. Para tanto foram testados os resÃduos agroindustriais: torta de canola, torta de girassol, farelo de trigo, pelÃcula da amÃndoa de caju e farelo de algodÃo como substrato, observando o perfil de produÃÃo em funÃÃo de diferentes atividades de Ãgua (Aw) iniciais obtidas pela adiÃÃo de distintos volumes de Ãgua para umidificaÃÃo. A produÃÃo de protease em reator de colunas nas condiÃÃes otimizadas foi comparada com a produÃÃo em Erlenmeyer, durante dez dias. Foram avaliados procedimentos para recuperar, identificar, concentrar, e estocar o extrato enzimÃtico produzido. Para a concentraÃÃo do extrato enzimÃtico produzido realizou-se estudo de secagem em âspray dryerâ e acompanhou-se o tempo de estocagem do extrato seco durante 90 dias. Com os resultados foi possÃvel selecionar a torta de canola como o substrato onde apresentou uma produÃÃo 33% superior aos demais substratos testados. No estudo das condiÃÃes operacionais em reator de colunas foi possÃvel avaliar a influÃncia da vazÃo do ar, umidade relativa do ar e umidade do substrato na produÃÃo de protease. A utilizaÃÃo de glicose, maltodextrina e carboximetilcelulose como adjuvantes se mostraram eficientes com relaÃÃo à manutenÃÃo da atividade de protease durante o processo de secagem utilizando âspray dryerâ, onde foi possÃvel obter um produto seco com baixos valores de umidade e Aw, importante para o processo de estocagem do extrato enzimÃtico. A secagem por atomizaÃÃo do extrato enzimÃtico possibilitou concentrar e estocar a enzima. / Enzyme production by solid state fermentation (SSF) is influenced by several factors that affect crop growth and production of microbial metabolites. The study of factors such as aeration and moisture in the air becomes indispensable for this bioprocess optimization. In this context, the present study aimed to assess the protease production by Aspergillus oryzae CCBP001 by FSS bioreactor columns. The FSS for the production of protease using the filamentous fungus A. oryzae CCBP 001 occurred in dynamic and static conditions in order to observe the method with the highest production. Therefore, tested the agroindustrial waste: canola cake, sunflower cake, wheat bran, almond cashew film and cottonseed meal as substrate, observing the production profile for different water activity (Aw) obtained by initial adding different volumes of water for humidification. Protease production in reactor columns in the optimized conditions was compared to production in flasks for 10 days. Evaluated procedures to recover, identify, focus and store the enzyme extract produced. For the concentration of the enzyme extract produced a study was conducted in dry "spray dryer" and followed up the storage time of the dry extract for 90 days. From the results it was possible to select the canola cake as the substrate where it presented a production 33% higher than the other substrates tested. In the study of operating conditions in reactor columns was possible to evaluate the influence of air flow, air humidity and substrate moisture in protease production. The use of glucose, maltodextrin and carboxymethylcellulose as adjuvants proved to be efficient with regard to maintenance of protease activity during the drying process using a "spray dryer", where it was possible to obtain a dry product with low values of humidity and Aw important for the storage process of enzyme extract. Spray drying of the enzyme extract and concentrate stockpile allowed the enzyme.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work appears as an experimental attempt to verify the validity of the theoretical model used to interface ratio proposed by Chicot and Lesage. For this, we present a study on the mechanical properties of interface from the instrumented penetration tests. One of the important points of the study is related to the characteristics of materials with micro deformations and influence of defects on the mechanical properties. Discussions are developed concerning the intrinsic properties, especially the behavior of elastic modulus for different situations in which the materials are. Were used for development work, specimens taken from oil pump stem, which are used in oil production equipment. These stems were coated with two types of materials, the basis of a NiCr alloy and another with Al, both obtained by thermal spray process (arc spray). Using instrumented penetration test was carried out indentations in the coatings, substrate and interface of each sample. With these results, we applied the theoretical model interfacial and later tried to verify itsvalidity. / O presente trabalho configura-se como uma tentativa experimental de verificação da validade do modelo teórico utilizado para relação de interface proposto por Chicot e Lesage. Para isso, é apresentado um estudo sobre as propriedades mecânicas de interface a partir de ensaios de penetração instrumentada. Um dos pontos relevantes do estudo está relacionado com as características dos materiais com micro deformações e a influência dos defeitos sobre as propriedades mecânicas. São desenvolvidas discussões referentes às propriedades intrínsecas, sobretudo o comportamento do módulo de elasticidade para diferentes situações nas quais os materiais se encontram. Foram utilizados para o desenvolvimento do trabalho, corpos de prova retirados de hastes de bombeio, que são equipamentos utilizados na produção petrolífera. Essas hastes foram revestidas com dois tipos de materiais, um a base da liga NiCr e outro com Al, ambos obtidos pelo processo de aspersão térmica (arc spray). Com a utilização de testes de penetração instrumentada realizou-se indentações nos revestimentos, substrato e interface de cada amostra. Com os resultados obtidos, aplicou-se no modelo interfacial teórico e posteriormente tentou-se verificar a sua validade.

Atualmente, sabe-se que grande parte dos acidentes graves ocorridos envolvendo uma diversidade de sistemas como plataformas de petróleo, aeronaves ou plantas de processos industriais, poderiam ser evitados caso possuíssem dispositivos de controle projetados especificamente para manter a segurança durante a ocorrência de falhas no funcionamento dos mesmos. Por outro lado, observam-se complicações em realizar o controle de sistemas remotos em que é possível não haver garantia de monitoração em tempo real, como o caso de sondas espaciais ou robôs de exploração. Neste contexto, podem-se encontrar ambas as dificuldades no controle do funcionamento de um Dispositivo de Assistência Ventricular (DAV) que desempenha a função de auxiliar o bombeamento de sangue para o sistema circulatório de um paciente com insuficiência cardíaca. Este tipo de dispositivo, quando usado para terapia de destino, deve apresentar um elevado nível de segurança, pois, caso haja falha, o risco de morte é eminente. Por sua vez, o sistema deve apresentar um elevado índice de autonomia, já que as características comportamentais e fisiológicas de um paciente estão em constante mudança e afetam diretamente o modo como deve ocorrer a interação entre o DAV e o sistema cardiovascular do paciente. Sendo assim, há uma necessidade premente de aprimoramento do projeto de sistemas de controle de DAVs autônomos e seguros. A proposta do presente trabalho consiste em aplicar conceitos mecatrônicos para o projeto de um sistema de controle de DAVs e, considerando a natureza dos sinais que indicam a ocorrência de falhas, considerar a teoria de Sistemas a Eventos Discretos (SED), ferramentas de análise de risco e técnicas de diagnóstico e tratamento de falhas para a obtenção de modelos de controle considerando-se uma arquitetura modular e distribuída. Desta forma, foi desenvolvida uma arquitetura de controle supervisório para DAVs considerando características de variações de comportamento do sistema circulatório do paciente e do próprio DAV. Esta arquitetura de controle contempla o diagnóstico e tratamento de falhas desenvolvendo um método para a classificação de falhas e, de acordo com a severidade de cada uma delas é proposto um sistema de controle que atua na regeneração ou degeneração do DAV para um estado seguro, v observando, também, o cumprimento de normas médicas e técnicas de segurança. Para atingir este objetivo, propõe-se uma sistemática para o projeto do sistema de controle para DAVs considerando o aspecto multidisciplinar pertinente a este contexto. A base dessa sistemática consiste em realizar uma efetiva análise de risco do sistema utilizando a ferramenta de estudo HAZOP (Hazard and Operability Studies). A partir do conhecimento obtido sobre o comportamento do sistema em situações críticas desenvolvem-se modelos formais utilizando rede Bayesiana e rede de Petri para o diagnóstico e tratamento das possíveis falhas. O comportamento do DAV controlado pode ser analisado de duas formas: (i) a partir de ensaios in vitro utilizando técnicas de análise por simulação e ferramentas computacionais adequadas, além de testes em simuladores cardiovasculares físicos que emulam interação com o sistema circulatório humano; (ii) a partir de ensaios in vivo em animais que poderão ser utilizados para simular modelos físicos de insuficiência cardíaca e permitir uma avaliação fidedigna dos efeitos do implante do DAV. O procedimento proposto foi aplicado para um caso real de desenvolvimento de um DAV envolvendo uma equipe de pesquisadores da Escola Politécnica da USP e do Instituto Dante Pazanesse de Cardiologia. Assim, é possível obter-se um sistema de controle autônomo e seguro que atenda normas técnicas aderentes a esse assunto e os rigorosos requisitos de projeto impostos a essa classe de sistema. / Nowadays, it is kwon that the several of severe disasters compromising a great variety of systems such as oil platforms, aircrafts or industrial plants, could have been avoided if these systems had controllers designed specifically to maintain the safety levels in case of fault. On the other side, many complications are observed on performing the control of remote systems, where there is no guarantee of real time monitoring of the system, as in space probes or reconnaissance robots. In this context, both obstacles can be found on the control of ventricular assist devices (VAD), which have the role of assisting to pump the blood into the patients circulatory system, in case of irregular heartbeat or heart failure. Devices such as the VAD must possess very high safety levels, as in case of fault, the consequences are severe and might result on the dead of the patient. Nevertheless, these systems must have high degree of autonomy, as the patients physiology and behavior are constantly changing, and these changes impact directly the interactions between the VAD and the patient´s cardiovascular system. Thus, there is a pressing need to improve the design of safe and autonomous control systems for VADs. The present work proposes applying mechatronic concepts to the development of control systems for VADs, considering the nature of the fault indicating signals, as well as the Discrete Event Systems (DES) theory and through the application of tools for risk analysis, and fault diagnostic and treatment techniques aiming the development of control models based on modular and distributed architectures. Thereby, a VAD supervisory control architecture was developed, where the behavior variations of the patient´s circulatory system as well as of the VAD were taken into consideration. This control architecture features the diagnostic and treatment of faults, where methods for faults classification where developed, and according to the severity each fault is proposed a control system that performs the regeneration or degeneration of the VAD to a secure state and is according to medical standards and safety techniques. To achieve this goal is proposed a systematic for the design of the VAD control system considering the multidisciplinary context of the device. The foundation of this systematic is the performance of an effective risk analysis through the use of the toolset known vii as HAZOP (Hazard and Operability Studies). From the knowledge acquired about the system behavior during critical conditions, formal models are developed employing Bayesian Networks and Petri Nets for the diagnostic and treatment of faults. The behavior of the controlled VAD can be analyzed in two possible ways: (i) from in vitro experiments, through the use of simulation analysis tools and proper computational tools, as well as tests on real cardiovascular simulators, where the interactions between the VAD and the human circulatory system can be emulated; (ii) from in vivo experiments, animals can be used to simulate physical models of irregular heartbeat or heart failure and allow reliable valuations of the VAD implant. The proposed procedure was applied on the VAD development, which was performed by a team of researchers from the Escola Politécnica da USP and from the Instituto Dante Pazanesse de Cardiologia. Thus, is possible to achieve an autonomous and safe control system that complies with the applicable technical standards, as well as the strict project requirements for this class of system.

The aim of this thesis was to investigate how to construct a system to measure load in a mobile unicompartmental knee replacement (UKR) bearing. In vivo loads have been measured in a total knee replacement (TKR), but with TKR the kinematics are different from those of the normal knee, whereas they are close to normal in a mobile UKR, so the loads measured by an instrumented UKR would be more representative of the normal knee. On the principle of measuring compression of an object under load, the load may be estimated. Compression measurement using a capacitive sensor was the optimal solution to measure load, based on life expectancy of the sensor and bearing integrity. A capacitive sensor within a polyethylene (UHMWPE) bearing has not been used before. The visco-elastic and temperature dependent properties of UHMWPE were determined with experiments. UHMWPE had an approximately linear response after ten minutes of applying a constant load. A temperature sensor should be used in vivo to compensate for temperature effects acting on the elastic modulus of UHMWPE. Finite element modelling demonstrated that positioning the sensor under the centre of the bearing concavity resulted in the largest capacitive change. The influence of various dimensional parameters on sensor output was simulated, and the conclusion was that the sensor only needs to be calibrated once. An electronic module inserted into a bearing had less than 5 % influence on bearing compression. Capacitive sensors were made from polyimide, using standard production methods, and embedded within a UKR bearing using the standard compression moulding process. The embedded sensor had a second order low pass frequency response, with a corner frequency of 9 Hz, twice the frequency required for typical functional loading such as gait. Physiological load signals, gait and step up/down, were applied to the bearing. The capacitance to load response was approximately linear. Load was estimated using a linear method and a dynamic method. The linear method performed best, with an accuracy of force estimation better than 90 %. In vitro tests were performed using a commercially available transceiver, two stan- dard antennas and a custom antenna, designed to be incorporated in the bearing. Wireless communication between an implanted custom antenna and an external an- tenna was shown to be feasible. Experiments were also performed that demonstrate that inductive powering of the bearing was feasible. In addition to load measurement, a proposal for dynamic measurement of the orien- tation angles of both the tibia and the femur was made. Power and volume calculations showed that it is possible to place an electronic module within the bearing. This thesis has not only demonstrated that it is feasible to make an instrumented bearing for UKR but has also provided a basic design for manufacturing.

[pt] Este trabalho consiste na determinação dos valores e da distrbuição dos módulos de elasticidade com a profundidade de maciços de solo estratificados através de retroanálises de provas de carga em estaca instrumentada, com medição de recalques no topo e na base, publicadas na literatura para depósito de solos resuduais, argila rija e areia. Nas retroanálises utilizou-se um programa computacional baseado numa versão simplificada do método dos elementos de contorno, sugerida por Poulos (1968), com adaptações da formulação de Mindlin (1936) para permitir também a consideração de maciços estratificados. Seus resultados foram comparados com aqueles obtidos por vários tipos de ensaios de campo ou de laboratório, com o objetivo de indicar quais destes ensaios são os mais adequados para a determinação dos parâmetros de deformação do solo, visando o cálculo do recalque de estacas. Os valores de módulo de elasticidade computados nas retroanálises compararam-se satisfatoriamente com aqueles determinados com base nos ensaios que, durante a execução, induzem pequenas deformações no solo, ocorrendo, por outro lado, uma significativa subestimativa destes valores quando determinados em ensaios envolvendo grandes deformações. Este comportamento permitiu então concluir que uma escolha adequada do nível de deformações associada ao tipo de ensaio é essencial para a determinação das características de compressibilidade do solo na engenharia de fundações. / [en] This work consists of the determination of values and distribution of the modulus of elasticity with depth in layered soils through backanalysis of instrumented pile load tests, published in literature for residual soils, stiff clay and sand. In the backanalysis was used a simplified version of the boundary element method, originally introduced by Poulos and Davis (1968), with adaptations of Mindlin´s formulation to allow for the consideration of layered soils. The results of the backanalysis were compared with those obtained through many ´in situ´ and laboratory tests, with the aim of indicating which of those tests are more suitable for the determination of the deformation parameters of the soil, to be used in the evaluation of pile settlement. The values of elasticity modulus computed in the backanalysis agreed well with those determined from the tests which transmit small strains to the soil during its execution. On the other hand, these values were subestimated when obtained from tests that involve high strains. This behavior permitted the conclusion that an appropriate choice of the strain level, associated to the type of the test, is essential to the determination of the compressibility characteristics of the soil in foundation engineering problems. / [es] Este trabajo aborda la determinación de los valores de los módulos de elasticidad con profundidad de macizos de suelo estratificados así como su distribución. Dicha determinación se efectua a través de retroanálisis de pruebas de carga en estaca instrumentada, que aparecen publicadas en la literatura para depósito de suelos residuales, arcilla dura y arena. En el retroanálisis se utilizó un programa computacional basado en una versión simplificada del método de los elementos de contorno, sugerida por Polos (1968), con adaptaciones de la formulación de Mindlin (1936) que permiten considerar macizos estratificados. Con el objetivo de indicar cuál de estos ensayos resulta más adecuado para la determinación de los parámetros de deformación del suelo y para el cálculo del recalque de estacas, se compararon sus resultados con los obtenidos por varios tipos de ensayos de campo o de laboratorio. Los valores de módulo de elasticidad computados en el retroanálisis se compararan satisfactoriamente con los determinados con base en los ensayos que, durante la ejecución, inducen pequenas deformaciones en el suelo, teniendo, por otro lado, una significativa subestimación de estos valores cuando son determinados en ensayos con grandes deformaciones. Este comportamiento permitió entonces concluir que una selección adecuada del nível de deformación asociada al tipo de ensayo es esencial para la determinación de las características de compresibilidad del suelo en la ingeniería de fundaciones.

Cette thèse s’intéresse au travail enseignant en Sciences et Techniques des Agroéquipements (STA) dans le cadre de la transmission d’une « bonne pratique agricole » en situation d’enseignement professionnel. Elle vise à saisir l’organisation de l’activité d’enseignement, instrumentée dans un contexte particulièrement discrétionnaire et dans des environnements dynamiques multiples. Le cadre conceptuel mobilisé est au croisement de la didactique professionnelle et de l’approche instrumentale étendue. L’analyse porte à la fois sur des pratiques effectives et racontées et tient compte de la dimension symbolique de l’instrument dans la stratégie didactique mobilisée par l’enseignant. L’observation de l’activité didactique des enseignants, portant sur un même objet technique, permet de mettre en évidence les différents modes d’appropriations des instruments. L’analyse des résultats s’appuie sur la notion d’invariant (du sujet et de la situation) qui est envisagée au niveau du système d’instruments de l’enseignant et dans une articulation dialectique entre « pouvoir d’agir » et « accomplissement de soi ». La variabilité interindividuelle s’explique dans un processus dynamique de construction identitaire du sujet à l’origine « d’un sens pour soi » à chaque fois unique et sans cesse renouvelé : les connaissances en acte mobilisées par l’enseignant au travers de ses instruments apparaissent intimement liées à une forme de « re-connaissance en acte » donnant des styles d’enseignement variés. D’un point de vue plus général, les résultats valident le modèle « du sujet enseignant » proposé dans le cadre théorique en donnant à l’acte global d’enseignement une signification plus large et au-delà du langage. / This University thesis looks into the work done by teachers in Agri-Sciences and Techniques: how a "sound agricultural practice" is transmitted in a vocational teaching situation. Its aim is to grasp the organisation of the teaching activity in a particularly discretionary context and in various fluctuating situations. The conceptual framework used for this research is at the intersection of Professional Teaching Practice and an extended instrumental approach. The analytical work is based on tangible teaching practices as they were expressed, and takes into account the symbolic dimension of the device used by the teacher. As it bears on one technical element, the observation of the teachers’ activity makes it possible to highlight the various ways they make use of the chosen devices. The results analysis is based on the concept of invariance (both of the subject and the situation), as it was expected from the teacher’s range of devices and also dialectic relation between the concepts of "empowerment" and "self-accomplishment". The variations can be explained by the active process of the person’s identity construction, proceeding from the feeling of personal sense, a feeling each time unique and incessantly renewed: the teacher’s knowledge and cognition, as it is mustered through the devices used, appear to be closely linked to a form of "re-cognition", leading to varied teaching styles. From a more general point of view, the results verify the model of a "teaching person", as it was propositioned in the theoretical framework; it gives the global teaching act a broader meaning that reaches beyond language.

An existing analytical model, in use by Spoornet for the past two decades for calculating rail stresses on railway track, was revisited and improved. The model provided engineers with an easy-to-use program for evaluating track capacity and authorizing heavier loads on track. The model was modified to calculate rail and track component stresses more accurately. These modifications include the incorporation of current best practices and presentation of guidelines for the engineer on how to determine some input parameters which are normally difficult to obtain. Firstly it was determined which input parameters the model was the most sensitive to. Thereafter it was determined whether or not the correct information would generally be readily available for those sensitive parameters. The most sensitive parameters were further investigated and test results, as well as best practice analytical methods, were used to establish nominal input values and guidelines for determining such values. This research was necessary to establish whether or not the currently used analytical model still provided railway engineers with a useful tool and whether or not more modern and popular tools could validate or replace it. After some modifications to the analytical model, it was proved that it provides engineers with a suitably accurate tool for calculating rail and track component stresses, without the need to build time-consuming models of the track under investigation. It showed that the model, after some modifications, is current with calculational methods in recent publications and provides an immediate answer to "what-if" questions without the need to run lengthy analyses. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted