Castings made of aluminum 319 and A356.2 alloy were examined to determine the effectiveness of using pressure application during solidification to reduce porosity levels. Pyknometry was the method chosen to measure porosity. It was determined that the porosity of castings poured in both alloys was reduced in some instances. During the study, the surfaces of these castings were also examined and some were found to have defects present. After the porosity was evaluated, specimens of castings poured in both alloys were tested to determine whether or not the surface intrusions affected the castings. The defects were found to reduce the strength of the castings poured in aluminum 319. The castings poured in A356.2 did not have surface intrusions or any significant decreases in strength. Therefore it was concluded that of the two alloys tested, A356.2 alloy is most suited for using pressurization as a method of reducing porosity.

This research examines the role of actin cytoskeleton filaments in chondroinduction by cyclic hydrostatic pressurization. A chondroinductive hydrostatic pressurization system was developed and characterized. A pressure of 5 MPa at 1 Hz frequency, applied for 7200 cycles (4 hours intermittent) per day, induced chondrogenic differentiation in C3H10T1/2 cells while 1800 cycles (1 hour intermittent) did not induce chondrogenesis. Quantitative analysis of chondrogenesis was determined as sulfated glycosaminoglycan synthesis and rate of collagen synthesis while qualitative analysis was obtained as Alcian Blue staining and collagen type II immunostaining. Actin disruption using 2 uM Cytochalasin D inhibited the enhanced sGAG synthesis in the chondroinductive hydrostatic pressurization environment and significantly inhibited rate of collagen synthesis to the mean level lower than that of the non-pressurized group. These results suggest an involvement of actin cytoskeleton filaments in mechanotransduction of cyclic hydrostatic pressure.

Traditional diagnosis has been performed with hardware redundancy and limit checking. The development of more powerful computers have made a new kind of diagnosis possible. Todays computing power allows models of the system to be run in real time and thus making model-based diagnosis possible. The objective with this thesis is to investigate the potential of model-based diagnosis, especially when combined with active diagnosis. The diagnosis system has been applied on a model of the JAS39 Gripen fuel pressurization system. With the sensors available today no satisfying diagnosis system can be built, however, by adding a couple of sensors and using active model-based diagnosis all faults can be detected and isolated into a group of at most three components. Since the diagnosis system in this thesis only had a model of the real system to be tested at, this thesis is not directly applicable on the real system. What can be used is the diagnosis approach and the residuals and decision structure developed here.

Nowadays the aviation industry is playing an important role in our daily life, since is the main medium that satisfies the present human needs to reach long distances in the fastest way. But such benefit doesn’t come free of collateral consequences. It is estimated that each year, only the air transport industry produces 628 mega tonnes of CO2. Therefore, urgently actions need to be implemented considering that the current commercial fleet will be doubled by 2050. The research field for more efficient aircraft systems is a very constructive field; where novel ideas can be exploited towards the mitigation of the coming air transport development. In this research the configuration of the Environmental Control System (ECS) has been analysed aiming to reduce its energy consumption for both, fixed-wing and rotary-wing aircraft. This goal is expected to be achieved mainly through the replacement of the main source of power that supplies the ECS, from pneumatic to electric. Differently from the conventional ECS, a new electric-source technology is integrated in the system configuration to compare its effects on the energy consumption. This new technology doesn’t bleed air directly from the engines; instead of that, it takes the air directly from the atmosphere through the implementation of an electric compressor. This new technology has been implemented by Boeing in one of its most recent airplanes, the B787. Towards achieving the main goal, a framework integrated with five steps has been designed. An algorithmic analysis is integrated on the framework. The first step meets the required aircraft characteristics for the analysis. The second step is in charge of meeting the mission profile characteristics where the overall analysis will be carried out. The third step assesses the conventional ECS penalties. The fourth step carries out a complex analysis for the proposed electric ECS model, from its design up to its penalties assessment. The fifth step compares the analysis results for both, the conventional and the electric models. The fourth step of the framework, which analyses the electric ECS, is considered the most critic one; therefore is divided in three main tasks. Firstly, a small parametric study is done to select an optimum configuration. This task is carried out towards meeting the ECS air conditioning requirements of a selected aircraft. Secondly, the cabin temperature and pressurization are simulated to analyse the response of the configured electric ECS for a mission profile. And finally, the fuel penalties are assessed in terms of system weight, drag and fuel due power-off take. To achieve the framework results, a model which receives the name ELENA has been created using the tool Simulink®. This model contains 5 interconnected modules; each one reads a series of inputs to perform calculations and exchange information with other modules.

<p>Traditional diagnosis has been performed with hardware redundancy and limit checking. The development of more powerful computers have made a new kind of diagnosis possible. Todays computing power allows models of the system to be run in real time and thus making model-based diagnosis possible. </p><p>The objective with this thesis is to investigate the potential of model-based diagnosis, especially when combined with active diagnosis. The diagnosis system has been applied on a model of the JAS39 Gripen fuel pressurization system. </p><p>With the sensors available today no satisfying diagnosis system can be built, however, by adding a couple of sensors and using active model-based diagnosis all faults can be detected and isolated into a group of at most three components. </p><p>Since the diagnosis system in this thesis only had a model of the real system to be tested at, this thesis is not directly applicable on the real system. What can be used is the diagnosis approach and the residuals and decision structure developed here.</p>

Inflatable wings provide an innovative solution to unmanned aerial vehicles requiring small packed volumes, such as those used for military reconnaissance or extra-planetary exploration. There is desire to implement warping actuation forces to change the shape of the wing during flight to allow for greater control of the aircraft. In order to quickly and effectively analyze the effects of wing warping strategies on an inflatable wing, a finite element model is desired. Development of a finite element model which includes woven fabric material properties, internal pressure loading, and external wing loading is presented. Testing was performed to determine material properties of the woven fabric, and to determine wing response to static loadings. The modeling process was validated through comparison of simplified inflatable cylinder models to experimental test data. Wing model response was compared to experimental response, and modeling changes including varying material property models and mesh density studies are presented, along with qualitative wing warping simulations. Finally, experimental and finite element modal analyses were conducted, and comparisons of natural frequencies and mode shapes are presented.

Airflow into, out of, and within buildings is fundamental to their design and operation as it can affect occupant health and comfort, building durability, and energy consumption. This thesis works to develop the understanding of airflow patterns and pressure regimes in high-rise multi-unit residential buildings which are both unique and complex due to the combination of their height, typical inclusion of operable windows, and compartmentalized layout. Specific attention is directed towards the performance of corridor pressurization based ventilation systems which are used pervasively within industry to ventilate and control contaminant transfer in these buildings. Airflow is caused by pressure differences which for buildings are created by the driving forces of wind, stack effect, and mechanical ventilation systems. These airflows are resisted by the air permeance (i.e. airtightness) of building elements including the exterior enclosure and interior compartmentalizing elements. Using an experimental program at a case study building, this thesis assesses the interaction of these driving forces of airflow with the physical building to create the airflow patterns for a typical high-rise multi-unit residential building. Perflourocarbon tracer (PFT) testing was performed to measure in-service airflows into and out of the suites. This testing found that the air change rates of upper suites are significantly higher than that of lower suites and that most suites receive small fractions of modern ventilation rates or are over ventilated. Airflow measurements of the supply of ventilation air to each corridor indicate that these low flow rates are in part due to leakage of air from the supply duct. The PFT testing also found that significant airflow occurred from the parking garage below the building into the occupied building spaces indicating significant potential for transfer of harmful air contaminants. The air permeance of the exterior enclosure and interior compartmentalizing elements were measured using neutralized fan pressurization and depressurization techniques and found to be within typical ranges. In particular this testing found that only 20% of the flow paths out of the corridor were to the adjacent suites through the suite entrance doors and that flows to the elevator shaft and stairwells could create a significant inefficiency in the ventilation system. A long-term monitoring program was implemented at the case study building primarily to monitor exterior environmental conditions including wind and exterior temperature and to correlate these with measured pressure differences. A strong correlation was found between building pressure and exterior temperature. Nearly 70% of the theoretical stack effect pressure was measured to act across the corridor to suite pressure boundary which creates a significant pressure differences to be overcome by the ventilation system, likely contributing to the uneven distribution of ventilation rates. Both wind and stack effect pressures were found to often be of similar or greater magnitude than mechanically induced pressure differences and thus can overwhelm the ventilation system. Overall, the corridor pressurization based ventilation system at the case study building does not effectively or efficiently ventilate the building and also does not provide sufficient control of air contaminants. As the case study building was found to be relatively representative of a typical multi-unit residential building, the findings from this building can be extended to many other buildings. Effective ventilation and airflow control in multi-unit residential buildings likely requires suite compartmentalization and direct supply of ventilation via ducted or in-suite systems.

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Les failles dans la croûte supérieure sont des zones de déformation localisées capables de conduire des fluides sur de longues distances. L'estimation de la perméabilité des zones de failles et de leurs propriétés hydromécaniques est cruciale dans nombreux domaines de recherche et applications industrielles. Dans l'industrie pétrolière, et plus particulièrement dans les applications d'exploration et de production, l'intégrité de l'étanchéité des failles doit être évaluée pour la détection des pièges à hydrocarbures. Il existe déjà des approches permettant d'estimer la capacité de scellement latéral d'une faille à partir de la teneur en argile des couches (par exemple le Shale Gouge Ratio). Pourtant, les conditions dans lesquelles la faille se comporte comme un conduit le long de sa structure ne sont pas encore suffisamment contraintes. Dans ce contexte, la géomécanique peut apporter un éclairage complémentaire sur les paramétres qui contrôlent le comportement hydrodynamique de la faille. Ces paramètres comprennent le champ de contraintes, la pression du fluide, l'orientation des structures de la zone de faille et les propriétés des matériaux. Des expériences d'injection à une échelle décamétrique ont été réalisées dans une zone de faille située dans le site expérimental de Tournemire, dans le sud de la France, au cours desquelles la pression et le débit du fluide, la déformation du massif, la sismicité ont été suivis. Sur la base des observations issues de ces expériences, une étude numérique a été réalisée pour explorer l'évolution de la perméabilité etétablir le lien avec la réponse hydromécanique de la faille ainsi que la sismicité induite. Les comportements des failles secondaires, les fractures de la zone endommagée ainsi que la roche encaissante ont été modélisés numériquement en utilisant la méthode des éléments discrets. La modélisation des essais expérimentaux et l'analyse des modèles génériques utilisés pour les études paramétriques ont mis en évidence le rôle majeur des conditions de contrainte in situ. L'effet combiné de la contrainte et de l'orientation des structures de la faille détermine en premier lieu la nature de la réactivation selon le concept de l'état de contrainte critique de la faille décrit dans la littérature. Pour des conditions de contrainte et des éléments structuraux donnés, il a été démontré que selon le niveau de pression du fluide, la faille offre trois gammes différentes de perméabilité : i) perméabilité équivalente à la perméabilité de la formation, ii) 2 à 4 ordres de grandeur plus élevés et iii) plus de 4 ordres de grandeur plus élevés. Alors que pour les deux cas extrêmes, la faille est caractérisée comme étant hydromécaniquement active ou inactive, le second cas est principalement contrôlé par des mécanismes de chenalisation du fluide favorisés par des hétérogénéités aussi bien à l'échelle d'une seule fracture ou qu'à l'échelle du réseau de fractures. Les changements dans les propriétés hydrauliques sont dans certains cas détectés par la sismicité induite lors de l'injection en supposant que la sismicité est l'effet direct de la propagation du fluide, de l'augmentation de la pression du fluide et de la chute de la contrainte effective. Néanmoins, les mécanismes à l'origine de la sismicité induite par injection sont encore peu connus. A partir des résultats expérimentaux du site de Tournemire, le rôle de la diffusivité hydraulique des structures de la faille a été exploré sur la sismicité observée dans le cadre d'une analyse hydro-mécanique. Les résultats indiquent que la microsismicité induite était probablement liée à des perturbations de contrainte résultantes d'une déformation asismique importante plutôt que de la propagation de fluides à travers des structures hydrauliquement connectées. / Faults in the Earth crust are localized zones of deformation which can drive fluids over long distances. Estimating the permeability of fault zones and their hydro-mechanical properties is crucial in a wide range of fields of research and industrial applications. In the petroleum industry, and more specifically in exploration and production applications, the seal integrity of faults in low permeability formations (e.g. shale) needs to be evaluated for the detection of hydrocarbon traps. There already exist approaches able to sufficiently estimate the "side-sealing" capacity of a fault based on the clay or shale content of the layers (e.g. Shale Gouge Ratio). Nevertheless, the conditions under which the fault acts as a drain along its structure are still not properly constrained. In this context, the response of the fault is directly controlled by a number of factors that can be better approached from a geomechanics point of view. These factors include the stress field, the fluid pressure, the orientation of the fault-related structures and the material properties. Meso-scale field injection experiments were carried out inside a fault zone located in the Tournemire massif at the South of France during which the fluid pressure, the deformation, the seismicity and the flow rate were monitored. Based on the Tournemire experiments and field observations, a numerical study was performed exploring the evolution of the permeability and how it is related to the fault hydro-mechanical reactivation and potentially to the induced seismicity. Fault-related structures such as subsidiary faults or fractures that were targeted during the experiments together with the surrounding intact rock, were modeled using the Discrete Element method. Modeling of the experimental tests and the analysis of generic models used to perform parametric studies highlighted the primary role of the in-situ stress conditions. The combined effect of stress and orientation of the fault structures determine in the first place the nature of the reactivation according to the critically stressed fault concept reported in the literature. For given stress conditions and structural features, it was shown that depending on the fluid pressure level, the fault offers three different ranges of permeability: i) permeability that is equivalent to the formation's permeability, ii) 2 to 4 orders of magnitude higher and iii) more than 4 orders of magnitude higher. While for the two extreme cases the fault is characterized as hydro-mechanically inactive or active, the second case is mostly controlled by fluid channeling mechanisms promoted by heterogeneities at the scale of a single fracture or at the scale of the fracture network. Changes in the hydraulic properties are in some cases detected by the seismicity triggered during the injection under the assumption that the seismicity is the direct effect of fluid propagation, fluid pressure increase and effective stress drop.However, the mechanisms behind the injection induced seismicity are still poorly understood. Using experimental results from the Tournemire site, the role of the hydraulic diffusivity of the fault-related structures was explored on the recorded seismicity in the framework of a hydro-mechanical analysis. The results suggest that the induced microseismicity was possibly related to stress perturbations caused by a significant aseismic deformation rather than fluid propagation through hydraulically connected structures.

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