Particle ingestion is a prevalent issue for jet engines. During operation, sand and ash particles enter the engine and can cause serious problems, including erosion and buildup of Calcia-Magnesia-Alumina-Silicate (CMAS) deposits. Analyzing the particle mass concentration of the airflow can help better understand this issue. This can best be accomplished by sampling particles with a sampling probe at various locations within an engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to evaluate the aerodynamics of the modified probe through Particle Imaging Velocimetry (PIV), to gain insight on its ability to sample smaller particles, to characterize the movement of larger particles as they are sampled using Particle Tracking Velocimetry (PTV), and to develop a method to physically measure particle mass concentration. To accomplish this, a free jet rig was used to create a particle-laden flow, and the probe was placed at the jet exit to sample particles. A laser and camera system were used to capture images of the probe for PIV and PTV. A particle collection apparatus was designed to collect and weigh particles captured by the probe to measure mass concentration. The PIV results indicate that the probe exhibits sub-isokinetic sampling behavior. However, the PTV results show that large particles are not affected by non-isokinetic conditions. The mass concentration measured by the probe decreases when the flow Mach number increases due to the higher flow velocity causing particles to be spaced further apart. The mass concentration measured by the probe decreases when the probe yaw angle increases due to lower projected probe inlet area. / Master of Science / Sand and ash particles are harmful to jet engines. Particle ingestion can greatly affect the useful life of the engine. Particles erode the machinery within the engine, and they also melt to form mineral deposits, all of which degrades performance. One method that is being developed to better understand this problem is to sample particles at various locations in the engine using a sampling probe. The concept of a sampling probe is simple: particles are captured by the probe inside the engine, and the particles are collected outside the engine for analysis. This would give insight on particle behavior in the engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to use advanced imaging techniques to characterize the movement of air and particles entering the probe, and to safely collect and weigh particles captured by the probe. A compressed air jet was used to accelerate particles and create a particle-laden environment akin to the inside of an engine. The probe was placed at the exit of the jet to sample particles. A laser and camera system were used to capture images of the probe during the particle-sampling process. A particle collection apparatus was designed to safely collect and store particles captured by the probe for weighing. The image and weight data were then used to make conclusions about the probe's sampling capability.

[pt] O planejamento de recursos materiais é uma parte importante do gerenciamento da cadeia de suprimentos. As tarefas na cadeia de suprimentos precisam de materiais e recursos para serem executadas e, portanto, alocar os recursos corretamente é uma parte importante do planejamento de tarefas. Especificamente, as tarefas de construção de poços submarinos requerem a utilização de recursos, como sondas, e o planejamento do cronograma dessas operações envolve o dimensionamento de diversos materiais e serviços necessários para sua execução. Este estudo é motivado pelo planejamento de programação real de uma grande empresa de Óleo e Gás que estima estocasticamente a demanda por materiais e serviços devido às incertezas associadas às tarefas em suas datas de início e durações. O cálculo da demanda varia de acordo com o cronograma atual que a empresa possui e a um conjunto de regras que indicam condições de alocação, parâmetros logísticos, condições de desembarque e dependências para alocar as ferramentas e serviços necessários para cada tarefa e estimar sua quantidade e quantos dias em que serão usados. Este conjunto de ferramentas e regras pode mudar dependendo do usuário e de seu conhecimento operacional. Além disso, a empresa utiliza um grande número de cenários, o que resulta em tempos computacionais extremamente altos e impacta a tomada de decisões operacionais. Nesse contexto, a redução de cenários poderia auxiliar a empresa no seu processo de tomada de decisão. A metodologia proposta neste trabalho avalia e identifica cenários representativos de incerteza nos cronogramas de planejamento estratégico de sondas offshore, a fim de reduzir o número de cenários utilizados no cálculo da demanda por ferramentas e serviços. Com a utilização de técnicas não supervisionadas, como k-means e agrupamento hierárquico, foi identificado um subconjunto com os cenários mais representativos para a redução de cenários. A Distância de Wasserstein e a visualizações gráficas foram utilizadas para calcular a representatividade dos cenários selecionados e encontrar o melhor subconjunto. Além disso, o subconjunto de cenários proveniente da redução também foi utilizado para analisar o impacto da redução no cálculo da demanda. O Clustering Aglomerativo com Ward Linkage obteve os melhores resultados de clusterização e representatividade, resultando em um subconjunto de redução de 782 cenários. Para encontrar um conjunto mínimo representativo de cenários, foi utilizado o melhor método de agrupamento, junto com a Distância de Wasserstein, e por fim obtido um número de 343 cenários. Isto apresenta uma redução de 84 por cento no tempo de execução do cálculo da demanda, com o erro maior de 11 por cento no cálculo da demanda. / [en] Material resource planning is an integral part of supply chain management. The tasks in the supply chain need materials and resources to be executed, thus, allocating resources correctly is an important part of task scheduling. Specifically, construction tasks for subsea wells require the use of resources, such as rigs, and planning the schedule of these operations involves the sizing of various materials and services necessary for their execution. This study is motivated by real-life scheduling planning from a large Oil and Gas company that estimates the demand for materials and services stochastically due to the uncertainties associated with the tasks in their start dates and durations. The calculation of the demand is subject to the current schedule that the company has and a set of rules that indicate allocation conditions, logistics parameters, disembarking conditions, and dependencies to allocate the tools and services needed for each task and estimate their quantity and how many days they will be used. These sets of tools and rules can change depending on the user and their operation knowledge. Additionally, the company uses a large number of scenarios, which results in extremely high computational times and impacts operational decision-making. In this context, scenario reduction could assist the company in its decision-making process. The methodology proposed in this work evaluates and identifies representative scenarios of uncertainty in strategic planning schedules of offshore rigs in order to reduce the number of scenarios used in the calculation of the demand for tools and services. With the use of unsupervised techniques, such as k-means and hierarchical clustering, we identified a subset with the most representative scenarios for the scenario reduction. The Wasserstein Distance and graphical visualization were used to measure the representativeness of the selected scenarios and find the best subset. Moreover, the scenario reduction subset was also used to analyze the impact of the reduction in the demand calculation. The Agglomerative Clustering with Ward Linkage (hierarchical clustering) obtained the best clustering evaluation and representativeness metrics, resulting in a selected subset of 782 scenarios. To find a minimal representative set of scenarios, the best clustering method and the Wasserstein Distance were used, resulting in a number of 343 scenarios. This presents a reduction of 84 percent in the execution time of the demand calculation, with the highest error of 11 percent in the demand calculation.

Particle ingestion remains an important concern for turbine engines, specifically those in aircraft. Sand and related particles tend to become suspended in air, posing an omnipresent health threat to engine components. This issue is most prevalent during operation in sandy environments at low altitudes. Takeoffs and landings can blow a significant quantity of particulates into the air; these particulates may then be ingested by the engine. Helicopters and other Vertical Takeoff and Landing (VTOL) aircraft are at high risk of engine damage in these conditions. Compressor blades are especially vulnerable, as they may encounter the largest of particles. Robust and thorough experimental and computational studies have been conducted to understand the relationships between particle type, shape, and size and their effects on compressor and turbine blade wear. However, there is a lack of literature that focuses on sampling particles directly from the flow inside an engine. Instead, experimental studies that estimate the trajectories and behavior of particles are based upon the resulting erosion of blades and the expected aerodynamics and physics of the region. It is important to close this gap to fully understand the role of particulates in eroding engine components. This study investigated the performance of a particle-sampling probe designed to collect particles after the first compressor stage of a Rolls-Royce Allison Model 250 turboshaft engine. The engine was not used in this investigation; rather, a rig that creates a particle-laden jet was developed in order to determine probe sampling sensitivity with respect to varying angles of attack and flow Mach number. Particle image velocimetry (PIV) was utilized to understand the aerodynamic effects of the probe on smaller particles. / Master of Science / Aircraft jet engines are constantly exposed to particles suspended in the atmosphere. Most jet engines contain several stages of spinning blades. The first series of stages near the front of the engine comprise the compressor, while the series towards the end of the engine comprise the turbine. Engines depend on compressor blades to add energy to the flow via compression and turbine blades to extract energy from the flow after combustion. Thus, they are critical for the successful operation of the engine. The constant impact of airborne particulates against these blades causes erosion, which alters blade geometry and thereby engine performance. Depending on the turbine inlet temperature, particles may melt and clog the cooling passages in turbine blades, causing serious damage as the blades reach temperatures above their intended operating regime. These damages inhibit the ability of the engine to operate properly and pose a serious safety risk if left unchecked. In literature, experimental engine erosion correlations and numerical models of particle trajectories through the engine have been developed; however, none of these studies collected particles directly from the compressor region of the engine. In this study, a probe was developed and evaluated for the purpose of sampling particulates between the first and second compressor stages of a Rolls-Royce Allison Model 250 turboshaft engine. The probe's efficacy and aerodynamic properties were analyzed such that the probe will provide processable data when inserted into the engine. The methods to obtain this data include particle-sampling and particle image velocimetry (PIV).

The primary purpose of this study is to perform accurate dynamic measurements on a scaled roller rig designed and constructed by Virginia Tech and the Federal Railroad Administration (VT-FRA Roller Rig). The study also aims at determining the effect of naturally generated third-body layer deposits (because of the wear of the wheel and/or roller) on creep or traction forces. The wheel-rail contact forces, also referred to as traction forces, are critical for all aspects of rail dynamics. These forces are quite complex and they have been the subject of several decades of research, both in experiments and modeling. The primary intent of the VT-FRA Roller Rig is to provide an experimental environment for more accurate testing and evaluation of some of the models currently in existence, as well as evaluate new hypothesis and theories that cannot be verified on other roller rigs available worldwide. The Rig consists of a wheel and roller in a vertical configuration that allows for closely replicating the boundary conditions of railroad wheel-rail contact via actively controlling all the wheel-rail interface degrees of freedom: angle of attack, cant angle, normal load and lateral displacement, including flanging. The Rig has two sophisticated independent drivelines to precisely control the rotational speed of the wheels, and therefore their relative slip or creepage. The Rig benefits from a novel force measurement system, suitable for steel on steel contact, to precisely measure the contact forces and moments at the wheel-rail contact. Experimental studies are conducted on the VT ��" FRA Roller Rig that involved varying the angle of attack, wheel and rail surface lubricity condition (i.e., wet vs. dry rail), and wheel wear, to study their effect on wheel-rail contact mechanics and dynamics. The wheel-rail contact is in between a one-fourth scale AAR-1B locomotive wheel and a roller machined to US-136 rail profile. A quantitative assessment of the creep-creepage measurements, which is an important metric to evaluate the wheel-rail contact mechanics and dynamics, is presented. A MATLAB routine is developed to generate the creep-creepage curves from measurements conducted as part of a broad experimental study. The shape of the contact patch and its pressure distribution have been discussed. An attempt is made to apply the results to full-scale wheels and flat rails. The research results will help in the development of better simulation models for non-Hertzian contact and non-linear creep theories for wheel-rail contact problems that require further research to more accurately represent the wheel-rail interaction. / MS / Rail vehicles are supported, steered, accelerated, and decelerated by contact forces acting in extremely small wheel-rail contact areas. The behavior of these forces is quite complex and a broad interdisciplinary research is needed to understand and optimize the contact mechanics and dynamics problem. Key industry issues, such as control of Rolling Contact Fatigue (RCF), maximizing wheelset mileages, and minimizing the impact of rolling stock on the infrastructure, are directly related to the interaction at the wheel-rail contact. The Rig consists of a wheel and roller in a vertical configuration that allows for closely replicating the boundary conditions of railroad wheel-rail contact via actively controlling all the wheel-rail interface degrees of freedom: angle of attack, cant angle, normal load and lateral displacement, including flanging. The Rig has two sophisticated independent drivelines to precisely control the rotational speed of the wheels, and therefore their relative slip or creepage. The Rig benefits from a novel force measurement system, suitable for steel on steel contact, to precisely measure the contact forces and moments at the wheel-rail contact. The primary purpose of this study is to perform accurate dynamic measurements on a scaled roller rig designed and constructed by Virginia Tech and the Federal Railroad Administration (VT-FRA Roller Rig). Experimental studies are conducted on the VT – FRA Roller Rig that involved varying the angle of attack, the wheel and rail surface lubricity condition (i.e., wet vs. dry rail), and the wheel wear to study their effects on wheel-rail contact mechanics and dynamics. The wheel-rail contact is in between a one-fourth scale AAR-1B locomotive wheel and a roller machined to US-136 rail profile. A quantitative assessment of the creep-creepage measurements, which is an important metric to evaluate the wheel-rail contact mechanics and dynamics, is presented. A MATLAB routine is developed to generate the creep-creepage curves from measurements conducted as part of a broad experimental study. The shape of the contact patch and its pressure distribution have been discussed. An attempt is made to apply the results to full-scale wheels and flat rails. The research results will help in the development of better simulation models for non-Hertzian contact and non-linear creep theories for wheel-rail contact problems that require further research to more accurately represent the wheel-rail interaction.

In today’s society, there is a growing emphasis on renewable energy generation to reduce greenhouse gas emissions, particularly carbon dioxide (CO2) and methane(CH4). Among renewable sources, wind power has emerged as one of the most rapidly advancing technologies, with floating offshore wind turbines showing significant potential due to their ability to be installed in deeper waters. This study investigates the feasibility of implementing a LFA machine The abbreviation"LFA" used in this report for the machine comes from swedish "Luftgapslindadflerpolig asynkronmaskin" (meaning "Airgap armature winding Multipole Asynchnousmachine") in a Counter Rotating Axis Floating Turbine (CRAFT) system, developed by Hans Bernhoff and the Norwegian company WorldWideWind. The CRAFT system consists of two three-bladed turbines rotating in opposite directions, linked to a rotor and stator respectively, to maximize potential energy extraction by doubling the angular velocity. The LFA aims to optimize the potential between the turbines by regulating the speed of one of the axes. This report specifically examines the torque curve of the LFA when it operates as a motor at various speeds. Experimental setups included coupling the LFA motor with a known generator(TGET550-5KW-300R) and measuring the motor’s performance. The data collected allowed for an analysis of the torque and efficiency of the LFA. Despite initial challenges with power limitations from the drive unit, iterative tests and calculations provided insights into the LFA’s inertia and torque characteristics. The study concludes with an evaluation of the LFA’s suitability for enhancing the efficiency of the CRAFT system in floating offshore wind applications. The study concludes with an evaluation of the LFA’s suitability for enhancing the efficiency of the CRAFT system in floating offshore wind applications.

Sound generation and propagation in circular ducts for frequencies beyond the cut-on frequencies of several higher order acoustic modes is investigated. To achieve this, experimental and numerical set-ups are designed and used to research aeroacoustic interactions between in-duct components and to conceive noise mitigation strategies. Describing in-duct sound for frequencies with a moderate number of propagating modes is important, for example, for improving the noise emission from mid-size ventilation systems. Challenges that are largely unacknowledged in the literature involve efficient test rig design, quantification of limits in the methods, numerical modelling, and development of effective noise mitigation strategies for higher order modes. In this thesis, in-duct sound is mapped on a set of propagating pressure eigenmodes to describe aeroacoustic components as multi-ports with sound scattering (passive properties) and a source strength (active properties). The presented analysis includes genetic algorithms and Monte Carlo Methods for test rig enhancement and evaluation, multi-port network predictions to identify model limitations, and scale resolving (IDDES) and Linearized Navier Stokes computations for numerical multi-port eduction and the silencer design. It is first shown that test rig optimization improves the quality of multi-port data significantly. Subsequently, measurements on orifice plates are used to test the network prediction model. The model works with high accuracy for two components that are sufficiently separated. For small separations, strong coupling effects are observed for the source strength but not for the scattering of sound. The measurements are used for numerical validation, which gives reliable results for coupled and uncoupled systems. The total acoustic power of tandem orifices is predicted with less than 2 dB deviation and the passive properties for most frequencies with less than 5 % difference from the measurement. The numerical (FEM) models are also used to design a completely integrated silencer for spinning modes that is based on micro-perforated plates and gives broadband attenuation of 3-6 dB per duct diameter silencer length. The multi-port method is a powerful tool when describing aerodynamically decoupled in-duct components in the low- to mid-frequency range. Due to a robust passive network prediction, multi-port methods are particular interesting for the design of silencer stages. Furthermore, the demonstrated applicability to numerical data opens novel application areas. / <p>QC 20170522</p> / IdealVent

Diverses études ont souligné le rôle prépondérant du dialogue entre les cellules NK et les cellules dendritiques au cours des réponses immunes. Cependant, les récepteurs impliqués dans ce processus restent incertains. Au cours de ce travail, nous nous sommes attachés à identifier les récepteurs mis en jeu lors de la reconnaissance virale à l’aide de modèles humains et murins. Pour cela, nous avons mimé l’infection virale en utilisant deux ARN bicaténaires synthétiques – poly(AU) et poly(IC) – et montré qu’ils sont tous deux capables d’activer TLR3 mais que seul poly(IC) engage les hélicases RIG-I et MDA5. Les deux ARN induisent l’activation des cellules NK au sein des PBMC humaines, mais seul poly(IC) induit la production d’IFN-gamma. Les DC myéloïdes (mDC) sont requises pour cette activation sans nécessité d’un contact cellulaire entre les cellules NK et les mDC. En outre, les IFN de type I et l’IL-12 secrétés par les DC sont respectivement nécessaires à l’initiation du potentiel lytique et à la production d’IFN-gamma. Poly(IC), au contraire de poly(AU), a une action synergique avec l’IL-12 produite par les mDC pour induire la production d’IFN-gamma en agissant directement sur les cellules NK. Enfin, l’activation conjointe de TLR3 et des hélicases RLR sur les mDC et RIG-I sur les cellules NK, nécessaire à la production d’IFN-gama en réponse à l’ARN bicaténaire, a été confirmée à l’aide de souris déficientes pour TLR3 et Cardif et d’un ligand spécifique de RIG-I. En conclusion, nous rapportons pour la première fois la nécessité pour un composé microbien d’engager deux familles de récepteurs sur deux populations cellulaires distinctes pour induire une réponse innée éfficace. / Crosstalk between NK cells and DC is critical for the response to the microbial mimic poly(IC) but the dsRNA receptors involved in each cell types remained to be defined. We show herein that two dsRNA, poly(AU) and poly(IC), similarly engaged TLR3 while only poly(IC) triggered the RIG-I and MDA-5 helicases. Both dsRNA triggered NK cell activation within PBMC but only poly(IC) induced IFN-gamma. mDC were required for NK cell activation by the two dsRNA, suggesting that they triggered at least TLR3 on mDC. DsRNA induction of cytolytic potential and IFN-gamma production in NK cells did not require contact with mDC but was dependent on the secretion of type I IFN and IL-12, respectively. Poly(IC) but not poly(AU) synergized with mDC-derived IL-12 for high IFN-gamma production by acting directly on NK cells. Finally, the requirement of TLR3 and the RLR on mDC and the involvement of the RIG-I but not TLR3 on NK cells for the production of IFN-gamma induced by dsRNA was confirmed using TLR3 and Cardif deficient mice and RIG-I specific activator. This cooperation was further confirmed using inactivated FLU virus infected-target cells both in human and mouse system demonstrating that NK cells were able to sense viral material by a direct transfer from infected cells likely through lytic immunological synapse without prior infection of NK cells. Thus, we report for the first time the requirement of cotriggering

This diploma thesis is dedicated to mechnical desing, fabrication and assembly of experimental bearing testing rig. First part of the document contains research of current knowlege in the field of bearing testing and desings of currently used machines. In second part is conception of the testing rig described. Third part contains description of design variations that were designed. In Discussion is comented choices of final variants. Last part is dedicated to functional verification of the whole testing rig by first series of the tests.

<p>The Gravity Control for Maya will be extraordinary</p><p>beneficial to an animator trying to create realistic</p><p>animation, by calculating the center of gravity and area</p><p>of balance. This control will provide the animator with</p><p>the ability to rotate around the center of gravity and</p><p>keep the character in a balanced pose. With that ability,</p><p>the animator can easily create accurate poses and</p><p>animation, such as mid-air flips. The system also</p><p>supports a vast number of characters with different</p><p>shapes, sizes and number of limbs.</p>

Les métamatériaux à indice de réfraction négative ont attiré énormément l'attention ces dernières années surtout à cause de leurs propriétés électromagnétiques uniques. Ces matériaux sont des structures artificielles qui présentent des caractéristiques n'étant pas disponibles en matériaux naturels. Récemment, le développement technologique avec de nouvelles techniques de fabrication offrent un grand nombre de nouvelles application et développement de nouveaux matériaux. Il est possible d'obtenir un métamatériau en combinant des structures artificielles périodiquement. Les propriétés uniques du Split Ring Resonator (SRR), les Surfaces à Haute Impédance (HIS), les Surface Sélective en Fréquence (FSS) sont étudiées ainsi que les métamatériaux composés. Il a été démontré avec succès l'utilisation pratique de ces structures dans les circuits et les antennes. Il a été confirmé expérimentalement que les métamatériaux pourrait améliorer la performance des structures considérées dans cette thèse, pour des fréquences où la bande interdite électromagnétique se produit.