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Orientador: Marcos Roberto de Mattos Fontes / Resumo: As fosfolipases A2 (PLA2s) são um dos maiores constituintes protéicos do veneno botrópico e um dos responsáveis pela necrose muscular, consequência esta não eficazmente neutralizada pela administração do soro antiofídico. Estas proteínas são tóxicas através do rompimento ou perturbação da membrana celular em um mecanismo catalítico dependente de cálcio e outro independente, sendo este último não totalmente elucidado. Usualmente, estas toxinas são obtidas diretamente do veneno das serpentes, sendo sua purificação um desafio pela co-existência de diferentes isoformas. O objetivo desta tese foi compreender o mecanismo miotóxico independente de cálcio através de estudos estruturais e propor nova metodologia que trate de dados cristalográficos de toxinas provenientes de amostras impuras, chamada SEQUENCE SLIDER. Para tanto, cristalografia e outras técnicas biofísicas, como espalhamento de raios X a baixo ângulo, serão utilizados para estudar três miotoxinas ofídicas em estado nativo e complexado com produtos naturais e inibidores. Nós propusemos medidas locais e globais para caracterizar e relacionar a estrutura dessas toxinas a função. Com o SEQUENCE SLIDER, pudemos elucidar as estruturas de toxinas inéditas cuja sequência era parcialmente conhecida. Esta nova metodologia proposta consiste em avaliar diferentes cadeias laterais contra o coeficiente de correlação em espaço real calculado a partir dos dados cristalográficos. Em paralelo, desenvolvemos o SEQUENCE SLIDER no âmbito do... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

This works applies the idea of adjustment an engine-generator, so it is possible to connect an engine-generator, or other type of a generator, to the electricity. Consequently, the machine can transform the power supply without an outage. This work concerns the complex approach, provides the descriptions of particular parts, sensors and active components of a motor-generator and includes the explanation of their function. Further research is focused on designing and drawing a plan with a choice of a control unit for the whole system. Finally, the work deals with the complex implementation and testing the machine in real operation.

Due to their large torque-speed ratio and transmission efficiency, planetary gears are widely used in the automotive industry. However, high amplitude vibrations remain their critical weakness, which limits their usage especially when new strict noise legislations come into action. A new approach to handle the instability problems of planetary gears encountered in real industrial context is presented in this work. First, the dynamic response of a planetary gear failing to pass the noise regulations is theoretically investigated through an analytical model. The equations of motion were solved using the Spectral Iterative Method. The observed experimental results correlated well with those from the developed model. In order to limit the resonance phenomena, impacts of different macro and micro-geometry modifications were analytically investigated: quadratic teeth profile, different planets positioning, different number of teeth and number of planets. Optimum modifications were retrieved and are expected to be tested experimentally on a test bench and on the truck. Finally, the analytical model’s limits and sensitivity to different parameters were investigated in order to certify its reliability, and suggestions for improvements were presented.

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Pour franchir les prochaines étapes réglementaires, une des solutions adoptées par les constructeurs automobiles est la dépollution à la source par des nouveaux concepts de combustion. Une piste d’étude est le moteur à charge homogène allumé par compression, le moteur HCCI. Le défi majeur est de contrôler le phasage de la combustion lors des transitions. Or, l’ozone est un additif prometteur de la combustion. La première partie de ce travail est consacrée au développement d’un modèle 0D physique de la combustion dans le moteur HCCI à l’aide d’une approche statistique basée sur une fonction de densité de probabilité (PDF) de la température. Pour cela, un modèle de variance d’enthalpie est développé. Après la validation expérimentale du modèle, il est utilisé pour développer des cartographies du moteur HCCI avec et sans ajout de l’ozone afin d’évaluer le gain apporté par cet actuateur chimique en terme de charge et régime. La deuxième partie porte sur le contrôle du phasage de combustion par ajout d’ozone. Une étude de simulation est effectuée où des lois de commandes sont appliquées sur un modèle orienté contrôle. Les résultats montrent que l’ajout d’ozone permet de contrôler cycle-à-cycle le phasage de la combustion. En parallèle, une étude expérimentale sur un banc moteur est facilitée grâce à un système d’acquisition des paramètres de combustion (Pmax, CA50) en temps réel, développé au cours de cette étude. En intégrant les lois de commande par ajout d’ozone dans le calculateur du moteur (ECU), les résultats expérimentaux montrent la possibilité de contrôler non seulement cycle-à-cycle le phasage de la combustion par ajout d’ozone lors des transitions mais aussi de stabiliser le phasage de la combustion d’un point instable. / To pass the next legislator steps, one of the alternative solutions proposed for the depollution at the source by new concepts of combustion. One of proposed solution is the Homogeneous Charge Compression Ignition (HCCI) engine. The major challenge is to control combustion phasing during transitions. Ozone is promising additive to combustion. During this work, a 0D physical model is developed based on temperature fluctuations inside the combustion chamber by using Probability Density Function (PDF) approach. For this, an enthalpy variance model is developed to be used in Probability Density Function (PDF) of temperature. This model presents a good agreement with the experiments. It is used to develop HCCI engine map with and without ozone addition in order to evaluate the benefit of using ozone in extending the map in term of charge-speed. The second part deals with control the combustion phasing by ozone addition. A Control Oriented Model (COM) coupled with control laws demonstrates the possibility to control combustion phasing cycle-to-cycle. Thereafter, an experimental test bench is developed to prove this possibility. A real time data acquisition system is developed to capture combustion parameters (Pmax, CA50). By integrating control laws into Engine Control Unit (ECU), results demonstrate not only the controllability of combustion phasing cycle-to-cycle during transitions but also to stabilize it for an instable operating point.

On-orbit servicing (OOS) of space systems provides immense benefits by extending their lifetime, by reducing overall cost of space operations, and by adding flexibility to space missions. Refueling is an important aspect of OOS operations. The problem of determining the optimal strategy of refueling multiple satellites in a constellation, by expending minimum fuel during the orbital transfers, is challenging, and requires the solution of a large-scale optimization problem. The conventional notion about a refueling mission is to have a service vehicle visit all fuel-deficient satellites one by one and deliver fuel to them. A recently emerged concept, known as the peer-to-peer (P2P) strategy, is a distributed method of replenishing satellites with fuel. P2P strategy is an integral part of a mixed refueling strategy, in which a service vehicle delivers fuel to part (perhaps half) of the satellites in the constellation, and these satellites, in turn, engage in P2P maneuvers with the remaining satellites. During a P2P maneuver between a fuel-sufficient and a fuel-deficient satellite, one of them performs an orbital transfer to rendezvous with the other, exchanges fuel, and then returns back to its original orbital position. In terms of fuel expended during the refueling process, the mixed strategy outperforms the single service vehicle strategy, particularly with increasing number of satellites in the constellation. This dissertation looks at the problem of P2P refueling problem and proposes new extensions like the Cooperative P2P and Egalitarian P2P strategies. It presents an overview of the methodologies developed to determine the optimal set of orbital transfers required for cooperative and non-cooperative P2P refueling strategies. Results demonstrate that the proposed strategies help in reducing fuel expenditure during the refueling process.

Knocking is a type of abnormal combustion which depends on several physical factors and results in high frequency pressure oscillations inside the combustion chamber of a spark-ignited internal combustion engine (ICE). These oscillations can damage the engine and hamper its efficiency, which is why it is important for automakers to understand the knocking behavior so that it can be avoided during engine operation. Due to the catastrophic outcomes of knocking a lot of research has been done in the past on prediction of its occurrence. There can be several causes of knocking but when it occurs due to auto-ignition of fuel in the end-gas it’s called spark-knock. There are various mathematical models that predict the phenomenon of spark-knock. In this thesis, several of the previously published knock prediction models for heavy-duty natural-gas engine are studied and analyzed. The main objective of this project is to assess the accuracy of different types of knock prediction models.Amongst all the types of knock prediction models emphasize has been given to empirical correlation models, particularly to the ones which are based on chemical kinetics pertaining to the combustion process of methane. These are the models that claim to predict ignition delay time based on concentration of air and fuel in the unburned zone of the cylinder. The models are assessed based on the knocking behavior they represent across the engine operation range. Results pertaining to the knock prediction models are evaluated in a 1D engine simulation model using AVL BOOST. The BOOST performance prediction model is calibrated against experimentally measured engine test-cell data and the same data is used to assess the knock prediction models.The knock prediction model whose results correlate with experimental observations is analyzed further while other models are discarded. Using the validated model, variation in knock occurrence is evaluated with change in the combustion phasing. Two of the parameter that are used to define the combustion phasing are spark-advance and combustion duration. It was found that when the brake mean effective pressure is kept constant the knock prediction parameter increases linearly with increase in spark advance and decreases linearly with increase in combustion duration. The variation of knock prediction parameter with spark advance showed increasing gradient with increase in engine torque. / Knack i en förbränningsmotor är en typ av onormal förbränning. Det är ett komplicerat fenomen som beror på flera fysiska faktorer och resulterar i högfrekventa tryckoscillationer inuti förbränningskammaren. Dessa oscillationer kan skada motorn och fenomenet hämmar motorns effektivitet. Knack kan uppstå på två sätt i en Otto-motor och detta examensarbete kommer att handla om självantändning. Självantändning, i detta fall, är när ändgasen börjar brinna utan att ha blivit påverkad av flamfronten eller gnistan från tändstiftet. Det finns flera olika matematiska modeller som i olika grader kan prediktera knackfenomenet. I detta examensarbete studeras några av de tidigare publicerade prediktionsmodellerna för knack i Otto-förbränning och modelleras för analys. Huvudsyftet med detta projekt är således att bedöma noggrannheten hos olika typer av knackmodeller. Extra fokus har lagts på empiriska korrelationsmodeller, särskilt till de som är baserade på kemisk kinetik avseende förbränningsprocessen av metan. Dessa modeller förutsäger den tid det tar för ändgasen att självantända, baserat på dess koncentration av luft och bränsle. Knackmodellerna bedöms sedan utifrån det beteende som de förutsäger över motorns driftområde och dess överensstämmelse med kända motorkalibreringsstrategier. Resultatet av knackpredikteringen för de olika knackmodellerna utvärderas och valideras i en motorsimuleringsmodell i mjukvaran AVL BOOST. BOOST-modellen kalibreras mot experimentellt uppmätta motortestdata. Baserat på resultaten från de valda knockmodellerna så blev den modell som bäst korrelerar med kända motorkalibreringsstrategier analyserad djupare. Den utvalda modellen var en ECM modell och den utvärderas ytterligare med avseende på variation i predikterad knack-parameter. Detta görs genom att modifiera två förbränningsparametrar: tändvinkel och förbränningsduration. Det visade sig att modellerna predikterade en linjär ökning då tändningen tidigareläggs och ett linjärt minskande vid längre förbränningsduration, vilket är i enlighet med motortestdata. Vidare visade det sig att variationer i tändvinkel resulterade i en högre gradient i knackpredikteringen vid högre motorbelastningar och korresponderande minskning vid lägre belastning.

Knack i en förbränningsmotor är en typ av onormal förbränning. Det är ett komplicerat fenomen som beror på flera fysiska faktorer och resulterar i högfrekventa tryckoscillationer inuti förbränningskammaren. Dessa oscillationer kan skada motorn och fenomenet hämmar motorns effektivitet. Knack kan uppstå på två sätt i en Otto-motor och detta examensarbete kommer att handla om självantändning. Självantändning, i detta fall, är när ändgasen börjar brinna utan att ha blivit påverkad av flamfronten eller gnistan från tändstiftet. Det finns flera olika matematiska modeller som i olika grader kan prediktera knackfenomenet. I detta examensarbete studeras några av de tidigare publicerade prediktionsmodellerna för knack i Otto-förbränning och modelleras för analys. Huvudsyftet med detta projekt är således att bedöma noggrannheten hos olika typer av knackmodeller. Extra fokus har lagts på empiriska korrelationsmodeller, särskilt till de som är baserade på kemisk kinetik avseende förbränningsprocessen av metan. Dessa modeller förutsäger den tid det tar för ändgasen att självantända, baserat på dess koncentration av luft och bränsle. Knackmodellerna bedöms sedan utifrån det beteende som de förutsäger över motorns driftområde och dess överensstämmelse med kända motorkalibreringsstrategier. Resultatet av knackpredikteringen för de olika knackmodellerna utvärderas och valideras i en motorsimuleringsmodell i mjukvaran AVL BOOST. BOOST-modellen kalibreras mot experimentellt uppmätta motortestdata. Baserat på resultaten från de valda knockmodellerna så blev den modell som bäst korrelerar med kända motorkalibreringsstrategier analyserad djupare. Den utvalda modellen var en ECM modell och den utvärderas ytterligare med avseende på variation i predikterad knack-parameter. Detta görs genom att modifiera två förbränningsparametrar: tändvinkel och förbränningsduration. Det visade sig att modellerna predikterade en linjär ökning då tändningen tidigareläggs och ett linjärt minskande vid längre förbränningsduration, vilket är i enlighet med motortestdata. Vidare visade det sig att variationer i tändvinkel resulterade i en högre gradient i knackpredikteringen vid högre motorbelastningar och korresponderande minskning vid lägre belastning. / Knocking is a type of abnormal combustion which depends on several physical factors and results in high frequency pressure oscillations inside the combustion chamber of a spark-ignited internal combustion engine (ICE). These oscillations can damage the engine and hamper its efficiency, which is why it is important for automakers to understand the knocking behavior so that it can be avoided during engine operation. Due to the catastrophic outcomes of knocking a lot of research has been done in the past on prediction of its occurrence. There can be several causes of knocking but when it occurs due to auto-ignition of fuel in the end-gas it’s called spark-knock. There are various mathematical models that predict the phenomenon of spark-knock. In this thesis, several of the previously published knock prediction models for heavy-duty natural-gas engine are studied and analyzed. The main objective of this project is to assess the accuracy of different types of knock prediction models. Amongst all the types of knock prediction models emphasize has been given to empirical correlation models, particularly to the ones which are based on chemical kinetics pertaining to the combustion process of methane. These are the models that claim to predict ignition delay time based on concentration of air and fuel in the unburned zone of the cylinder. The models are assessed based on the knocking behavior they represent across the engine operation range. Results pertaining to the knock prediction models are evaluated in a 1D engine simulation model using AVL BOOST. The BOOST performance prediction model is calibrated against experimentally measured engine test-cell data and the same data is used to assess the knock prediction models. The knock prediction model whose results correlate with experimental observations is analyzed further while other models are discarded. Using the validated model, variation in knock occurrence is evaluated with change in the combustion phasing. Two of the parameter that are used to define the combustion phasing are spark-advance and combustion duration. It was found that when the brake mean effective pressure is kept constant the knock prediction parameter increases linearly with increase in spark advance and decreases linearly with increase in combustion duration. The variation of knock prediction parameter with spark advance showed increasing gradient with increase in engine torque.

No description available.