Drag polars for three Micro Air Vehicles (MAVs) were measured at Reynolds numbers of 70,000, 50,000, 30,000, and 10,000 and compared to predictions generated using the classical approach. The MAVs tested had different configurations and aspect ratios varying from 1.2 to 1.6 and ratios of wetted surface area to planform area from 2.6 to 3.9. A force balance was used to measure the lift and drag on the MAVs at angles of attack ranging from -5 degrees (or -10 degrees) to 10 degrees. The force balance allowed the MAVs to rotate in the pitching axis. The MAV angle of attack was set using an elevator installed on the MAV and controlled using a standard radio control used by RC plane enthusiasts. Uncertainty analysis performed on the data showed the uncertainty for high Reynolds numbers was dominated by velocity uncertainty, and uncertainty for the lower Reynolds numbers was dominated by uncertainty in the force measurements. Agreement between measured and predicted drag polars was good with the measured drag never being more than two times the predicted drag. For the majority of the tests, the drag coefficients followed the expected Reynolds number trend: increasing with decreasing Reynolds number.

A crescente preocupação ambiental e a necessidade de se criar produtos mais eficientes têm impulsionado os pesquisadores a realizarem estudos acerca da aerodinâmica veicular. Estes dois fatores constituem os principais motivos, pelos quais existe uma grande procura por conhecimento nesta área. Esta ciência pode ser considerada relativamente nova e ainda carece de uma base de dados. Entender como a aerodinâmica se relaciona com o consumo de combustível nos automóveis, à medida que o arrasto impõe resistência ao deslocamento dos mesmos, é algo que tem estimulado as indústrias automotivas a investirem grandes esforços na obtenção de ferramentas, que possam representar as condições de tráfego normais e, assim conseguir prever o desempenho do produto em desenvolvimento. Os túneis de vento e a simulação computacional surgem neste ambiente como as principais ferramentas de análise e predição do escoamento ao redor do veículo. Por isso seu entendimento faz-se de extrema necessidade. Ter conhecimento sobre a concepção do seu projeto, como funcionam, seus pontos fortes e suas fraquezas, são requisitos necessários para a pessoa que deseja estudar esta ciência. O presente trabalho traz uma contextualização histórica da aerodinâmica veicular nas indústrias automotiva e automobilística, além de apresentar aspectos técnicos relacionados aos túneis de vento e simulação computacional. Abordando as vantagens e desvantagens de cada ferramenta, expõe-se o fato de que estas ferramentas são complementares no estudo aerodinâmico. Para exemplificar a utilização dessas ferramentas, foi realizado um estudo aerodinâmico sobre uma geometria básica, que representa com similaridade os veículos tipo hatchback, denominada Modelo SAE em ambiente computacional. Os conceitos acerca do arrasto veicular e estabilidade veicular foram expostos para embasar este estudo. Este modelo foi submetido a diferentes geometrias traseiras e condições de escoamento simétricas e assimétricas. Este estudo demonstrou que o arrasto e a estabilidade veicular compreendem conceitos distintos e, dessa forma, é possível diminuir o arrasto de um veículo sem haver perda de estabilidade. / The growing environmental concern and the necessity to create more efficient products have motivated researchers to conduct studies about the aerodynamic vehicle. These two aspects are the main reasons which are promoting a great demand for knowledge in this theme. This science may be considered relatively new and still lacks more databases. Understand how aerodynamics is related to automobiles fuel consumption such as drag resistance imposed to their displacement, is something that has made the automotive industries invest considerable effort in obtaining tools which may represent the normal traffic conditions and thus, able to predict the performance of the product in development stage. The wind tunnels and computer simulations appear in this environment as the main tools for analysis and prediction of the flow around vehicle. The understanding about them is so of utmost necessity. Knowing how it was designed, how they work, their strengths and weaknesses are essential requirements for the person who wants to study this science. This material presents a historical development of vehicle aerodynamics in automotive and motor-racing industries, indeed technical aspects related to wind tunnels and computational fluid dynamics. Exposing the advantages and disadvantages of both tools, it is evidenced these tools complement each other during an aerodynamic study. To exemplify these tools utility an aerodynamic research was conducted using a basic form geometry known as SAE Model that represents with similarity the hatchback vehicles in the market. Drag and vehicle stability concepts were exposed to build a solid basis for this study. This model was submitted to different rear geometries, symmetric and asymmetric flow conditions. It could be demonstrated that drag and vehicle stability have distinct concepts and therefore it is possible diminish the first without damaging the later.

We investigate the propagation of light in different conditions that lead to exotic propagation of photons and use near-resonant light-matter interactions to enhance these effects. First, we study the propagation of light in a moving highly dispersive medium, namely rubidium atoms. Based on the special relativity the speed of light changes with the speed of the medium. However, this drag effect in a non-dispersive medium is very small and thus difficult to measure. We show that the drag effect is enhanced significantly when the moving medium is highly dispersive. Thus, with this enhancement even a slow motion can be detected. Next, we employ the large nonlinear response of rubidium atoms to accentuate the formation of optical caustics. Caustics are important as nature uses caustics to concentrate the energy of waves. Moreover, caustics can be formed in many physical systems such as water waves in oceans to amplify tsunamis or generate rogue waves. The connection of our study to these giant water waves is discussed. Finally, we explore light-matter interactions in plasmonic systems. We show that photons experience a significant phase jump as they couple into and out of a plasmonic structure. This coupling phase, also known as the scattering phase shift, is generic to all scattering events. We measure this coupling phase with a triple-slit plasmonic structure. Moreover, we use the near-field enhancement of the plasmonic structure to enhance the coupling between the slits. Consequently, the photons can take non-trivial trajectories that pass through all three slits. We measure such exotic trajectories for the first time that are seemingly in violation of the superposition principle. The application of the superposition principle and the validity of Born’s rule is discussed.

Losses associated with turbulent flows dissipate a significant amount of generated energy. Such losses originate from the drag force, which is often described as the sum of the pressure drag and the friction drag. This thesis sets out to explore the hypothesis that passive wall motions driven by fluid mechanical forces are able to reduce the friction drag in fully developed turbulent boundary layers. Firstly, the streamwise and spanwise opposition controls proposed by Choi et al. (1994, Journal of Fluid Mechanics) are revisited to identify beneficial wall motions. Near-wall streamwise or spanwise velocity fluctuations are measured along a detection plane parallel to the wall (sensing). For streamwise control, the wall velocities are set to be equivalent to the measured streamwise velocity fluctuations, whereas for spanwise control, the wall velocities are set to have the same magnitude but opposite direction as the measured spanwise velocity fluctuations (actuation). Direct numerical simulations of canonical turbulent channel flows are carried out at low (Reτ ≈ 180) and intermediate (Reτ ≈ 1000) Reynolds numbers to quantify the effect of the distance between the wall and the detection plane. The investigation reveals the primary differences between the mechanisms underlying the two active in-plane controls. The modified flow features and turbulence statistics show that the streamwise control amplifies the most energetic streamwise velocity fluctuations and damps the near-wall vorticity fluctuations. In comparison, the spanwise control induces near-wall vorticity in order to counteract the quasi-streamwise vortices of the near-wall cycle and suppress turbulence production. Although, the working principles of the active controls are fundamentally different, both achieve drag reduction by mitigating momentum transfer between the velocity components. Secondly, two theoretical passive compliant wall models are proposed, the aim being to sustain beneficial wall motions identified by active flow control simulations. In the proposed models, streamwise or spanwise in-plane wall motions are governed by an array of independent one-degree-of-freedom damped harmonic oscillators. Unidirectional wall motions are driven by local streamwise or spanwise wall shear stresses. A weak coupling scheme is implemented to investigate the interaction between the compliant surface models and the turbulent flow in the channel by means of direct numerical simulations. A linear analytical solution of the coupled differential equation system is derived for laminar pulsatile channel flows allowing verification and validation of the numerical model. The obtained analytical solution is utilised to map the parameter space of the passive controls and estimate the effect of the wall motions. It is shown that depending on the control parameters, the proposed compliant walls decrease or increase the vorticity fluctuations at the wall similarly to the active controls. This is confirmed by direct numerical simulations. On the one hand, when the control parameters are chosen appropriately, the passive streamwise control damps the near-wall vorticity fluctuations and sustains the same drag reduction mechanism as the active streamwise control. This leads to modest, 3.7% and 2.3% drag reductions at low and intermediate Reynolds numbers. On the other hand, the spanwise passive control is not capable of increasing the near-wall vorticity fluctuations as dictated by the active spanwise control. For this reason, passive spanwise wall motions can increase the friction drag by more than 50%. The results emphasise the necessity of anisotropy for a practical compliant wall design. The present work demonstrates for the first time that passive wall motions can decrease friction drag in fully turbulent wall-bounded flows. The thesis sheds light on the working principle of an active streamwise control, and proposes a passive streamwise control exploiting the same drag reduction mechanism. An analytical model is developed to give a ready prediction of the statistical behaviour of passive in-plane wall motions. Whereas streamwise passive wall motions are found beneficial when the control parameters are chosen appropriately, solely spanwise passive wall motions lead to a drag penalty.

Helicopter performance is greatly influenced by its drag. Pylons, fuselage, landing gear, and especially the rotor hub of a helicopter experience large separated flow regions, even under steady level flight conditions the vehicle has been designed for, contributing to the helicopter drag. Several passive and active flow control concepts have been studied for reducing helicopter drag. While passive flow control methods reduce drag, they do so at one optimized design condition. Therefore, passive drag reduction methods may not work for helicopters that operate under widely varying flight conditions. Active flow control (AFC) methods overcome this disadvantage and consequently are widely being pursued. The present investigator has studied some of these AFC methods using computational fluid dynamics (CFD) techniques and has found synthetic (or pulsed) jets as one of the more effective drag reduction devices. Two bluff bodies, representative of helicopter components, have been studied and the mechanism behind drag reduction has been analyzed. It was found that the increase in momentum due to the jet, and a resultant reduction in the separated flow region, is the main reason for drag reduction in these configurations. In comparison with steady jets, synthetic jets were found to use less power for a greater drag reduction. The flow inside these synthetic jet devices is incompressible. It is computationally inefficient to use compressible flow solvers in incompressible regions. In such regions, using Lattice Boltzmann equations (LBE) is more suitable compared to solving the incompressible Navier-Stokes equations. The length scales close to the synthetic jet devices are very small. LBE may be used to better resolve these small length scale regions. However, using LBE throughout the whole domain would be computationally expensive since the grid spacing in the LBE solver has to be of the order of the mean free path. To address this need, a coupled Lattice Boltzmann-Navier-Stokes (LB-NS) methodology has been developed. The LBE solver has been successfully validated in a standalone manner for several benchmark cases. The solver has also been shown to be of second order accuracy. This LBE solver has been subsequently coupled with an existing Navier-Stokes (NS) solver. Validation of the coupled methodology has been done for analytical problems with known closed form solution. This LB-NS methodology is further used to simulate the flow past a cylinder where synthetic jet devices have been used to reduce drag. The LBE solver is used in the cavity of the synthetic jet nozzle while the NS solver is employed in the rest of the domain. The cylinder configuration was chosen to demonstrate drag reduction on helicopter hub shape geometries. Significant drag reduction is observed when synthetic jets are used, compared to the baseline no flow control case.

The flow around a finite square prism has not been studied extensively when compared with an “infinite” (or two-dimensional) square prism. In the present study, the effect of a wake-mounted splitter plate on the flow around a surface-mounted square prism of finite height was investigated experimentally using a low-speed wind tunnel. Of specific interest were the combined effects of the splitter plate length and the prism’s aspect ratio on the vortex shedding, mean drag force coefficient, and the mean wake. Four square prisms of aspect ratios AR = 9, 7, 5 and 3 were tested at a Reynolds number of Re = 7.4×104 and a boundary layer thickness of /D = 1.5. Splitter plate lengths of L/D = 1, 1.5, 2, 3, 5, and 7, were tested, with all plates having the same height as the prism. Measurements of the mean drag force were obtained with a force balance, and measurements of the vortex shedding frequency were obtained with a single-component hot-wire probe. A seven-hole pressure probe was used to measure the time-averaged wake velocity at a Reynolds number of Re = 3.7×104 for AR = 9 and 5 with splitter plates of lengths L/D = 1, 3, 5, and 7. These measurements were carried out to allow for a better understanding of how the splitter plate affects the mean wake of the finite prism. The results show that the splitter plate is a less effective drag-reduction, but more effective vortex-shedding-suppression, device for finite square prisms than it is for infinite square prisms. Significant reduction in the mean drag coefficient was realized only for short prisms (of AR ≤ 5) when long splitter plates (of L/D ≥ 5) were used. A splitter plate of length L/D = 3 was able to suppress vortex shedding for all aspect ratios tested. However, for square prisms of aspect ratios AR ≤ 7, the splitter plate is a less effective vortex-shedding-suppression device when compared to its use with finite circular cylinders, i.e. longer splitter plates are needed for vortex shedding suppression with square prisms. Wake measurements showed distinct wake velocity fields for the two prisms tested. For the prism of AR = 9, a strong downwash flow in the upper part of the wake became weaker towards the ground plane. For the prism of AR = 5, the downwash remained strong close to the ground plane. With splitter plates installed, the downwash became weaker for both prisms. The splitter plate was found to narrow the wake width, especially close to the ground plane, and led to the stretching of the streamwise vortex structures in the vertical direction, and increased entrainment towards the wake centreline in the cross-stream direction.

Dans un contexte réglementaire incitant fortement les industriels à la réduction de la pollution à la source, l’application de stratégies telles que des bonnes pratiques environnementales et un meilleur contrôle des procédés constituent une réponse aux enjeux environnementaux. Le traitement de surface par voie aqueuse est une activité grande consommatrice d’eau et de produits chimiques et donc génératrice de rejets aqueux pollués. L’objectif de ce travail est de proposer à ce secteur d’activité une méthodologie simple de limitation des flux de pollution ainsi que de la consommation en eau. Cette méthodologie se base notamment sur le postulat que l’entraînement est le principal vecteur de pollution au sein d’une chaîne de traitement de surface.Des études expérimentales ont permis, d’une part de créer une méthode rapide de calcul de l’entraînement et, d’autre part, de montrer et de quantifier l’influence de la forme et de la rugosité des pièces traitées, du temps d’égouttage, de la tension superficielle des solutions de traitement ou encore du type et de la durée du rinçage des pièces sur l’entraînement.L’ensemble de ces éléments, intégrés à la méthodologie de minimisation de la pollution, permet d’une part de réaliser un diagnostic de la chaîne mais aussi d’estimer l’impact d’une modification de cette chaîne sur la consommation spécifique en eau, le bilan de pollution ainsi que sur la qualité des rinçages. Cette méthodologie aide ainsi à limiter les consommations d’eau et de réactifs non seulement sur la chaîne mais également en station de détoxication, diminuant ainsi les impacts environnementaux et les coûts de fonctionnement. / Currently, via the prevention principle, environmental regulations incite industries to implement strategies to reduce the pollution at the source (ICPE, IPPC, IED). Industries are sometimes lost in front of various proposed technical solutions. The application of cleaner production strategies such as good operational procedures and good practices of management allow to answer these constraints.The metal finishing activity uses a lot of water and chemicals and thus generates polluted effluents. The objective of this work is to propose a simple methodology of limitation of the pollution flows and of the water specific consumption of metal finishing workshops.Then, experimental studies have allowed, on one hand, to create an easy method of the drag-out calculation and, on the other hand, to show and to quantify the influence of different parameters on the drag-out, from a qualitative and quantitative point of view. They are, for example, the shape and the roughness of the treated pieces, the draining time, the superficial tension of the treatment solutions but also the stirring type and duration of rinsing.All these elements, integrated into the methodology of pollution minimization, allow to realize a diagnosis of the process line. Moreover, it permits to estimate the impact of a modification of this installation on the specific consumption of water, on the pollution balance assessment and on the rinsing quality. So, this methodology can help to optimize and to limit consumptions of water and chemicals not only on the process line but also in wastewater treatment plant, so decreasing the environmental impacts and the running costs.

GADELHA, José Juliano Barbosa. Masculinos em mutação: a performance drag queen em Fortaleza. 2009. 265f. Dissertação (Mestrado em Sociologia) – Universidade Federal do Ceará, Departamento de Ciências Sociais, Programa de Pós-Graduação em Sociologia, Fortaleza-CE, 2009. / Submitted by nazareno mesquita (nazagon36@yahoo.com.br) on 2011-12-04T12:26:24Z No. of bitstreams: 1 2009_Dis_JJBG.pdf: 1841154 bytes, checksum: a26999f3f7c6335f1314b720d00a868a (MD5) / Approved for entry into archive by Maria Josineide Góis(josineide@ufc.br) on 2012-01-05T10:25:27Z (GMT) No. of bitstreams: 1 2009_Dis_JJBG.pdf: 1841154 bytes, checksum: a26999f3f7c6335f1314b720d00a868a (MD5) / Made available in DSpace on 2012-01-05T10:25:27Z (GMT). No. of bitstreams: 1 2009_Dis_JJBG.pdf: 1841154 bytes, checksum: a26999f3f7c6335f1314b720d00a868a (MD5) Previous issue date: 2009 / This dissertation shows how the drag queen experience present in the city of Fortaleza, located in the Northeastern region of Brazil, consists of a ritualistic and performative experience which challenges the limits of the binary of gender and sex and also narrows what we understand as the world of arts and the everyday life. The field research is based on direct observations in the places where the drag queen performances happen in Fortaleza such as nightclubs, bars and other cabaret entertainment clubs, as well as on the collection of data in more than 50 interviews in life-story model recorded between the years 2004 and 2007 with drag queens, transformists, transsexuals and transvestites in this city. The ritualistic and performative aspects of the drag queen experience is evidenced through an analysis of what these characters name “montagem” (cross-dressing), the author can conclude that an becoming-artist can be found by the drag queens in the form of certain liminalities. The theoretical scope of this work is based on the anthropology of the ritual, the ethno-aesthetics, the Performance Studies, the Queer Theory and the sociology of agency. The methodology follows the steps of a meta-etnography in dialogue with the cartography experience, developed by Gilles Deleuze and Félix Guattari. / Esta dissertação demonstra como a experiência drag queen ocorrente na cidade de Fortaleza, situada no nordeste brasileiro, constitui uma experiência ritual e performática que desafia os limites dos binarismos de gênero e sexo além de aproximar o que temos como sendo o mundo das artes ao que entendemos como sendo o mundo cotidiano. O trabalho de campo se fundamenta em observações diretas nos locais que dão passagem a performance drag queen em Fortaleza tais como boates, bares e outras casas de show bem como na coleta de mais de 50 entrevistas, no estilo história de vida, gravadas entre os anos de 2004 e 2007 com drag queens, transformistas, transexuais e travestis residentes na aludida cidade. Ao revelar o caráter ritual/performático da experiência drag queen por meio de uma análise daquilo que essas personagens denominam montagem, o autor conclui que um devir-artista é encontrado pelas drag queens sob o trajeto de certas liminaridades. O escopo teórico do trabalho se fundamenta na antropologia dos rituais, na etnoestética, nos Performance Studies, na Queer Theory e na sociologia da agência. A metodologia segue os rumos de uma metaetnografia em diálogo com a experiência cartográfica, desenvolvida por Gilles Deleuze e Félix Guattari.

Utiliser une tablette ou un smartphone est désormais courant. Cependant, les effets de l'âge sur les capacités motrices nécessaires pour l'exécution des gestes d'interaction tactile n'ont pas été suffisamment pris en compte lors de la conception et de l'évaluation des systèmes interactifs, une des raisons qui a empêché l'inclusion numérique de ce groupe d'utilisateurs. L'objectif de cette thèse est d'étudier l'interaction des personnes âgées avec les écrans tactiles afin d'identifier des problèmes d'utilisabilité sur des supports variés (smartphone et tablette, doigt et stylet). Pour cette étude, nous avons conçu un système interactif constitué de jeux de type puzzle numérique tactiles, où le geste d'interaction drag-and-drop (glisser-déposer) est employé pour positionner les cibles. Dans ce contexte, une attention particulière a été portée à l'analyse des mouvements de l'utilisateur. L'analyse des postures du poignet durant l'interaction a permis d'élucider la relation entre les caractéristiques des mouvements des personnes âgées avec leurs performances, à savoir, des temps plus longs et une augmentation du nombre d'erreurs par rapport aux utilisateurs adultes plus jeunes. Prendre en compte la variabilité des capacités motrices des utilisateurs lors des phases de conception et évaluation des systèmes interactifs est nécessaire pour comprendre leurs difficultés et améliorer l'ergonomie et utilisabilité de l'interaction tactile. / Tablets and smartphones have become mainstream technologies. However, the aging effects on the motor skills implied on tactile interaction haven't been enough considered during the design and evaluation of tactile interactive systems, what prevent this group of older adult users to be digitally included successfully. This thesis aims to study the interaction of older adults with touchscreens in order to identify usability issues on different devices and input modalities (smartphone and tablet, finger and stylus). To this study, we designed an interactive system consisted of tactile puzzle games and using drag-and-drop interaction for positioning the puzzle pieces into their corresponding targets. In this framework, a special attention was given to the analysis of the movements of the user. The analysis of the postures of the users' wrists during interaction allowed to elucidate the relationship between the characteristics of the movements of older adults and their performances, particularly concerning the longer times needed for executing the gestures of interaction as well as the increased error rates of this group of users when compared to younger adults. Taking into account the variability of users' motor skills during the design and evaluation of interactive systems is necessary to better understand their difficulties as well as to improve the ergonomics and the usability levels of tactile interaction.

Made available in DSpace on 2014-12-17T13:54:50Z (GMT). No. of bitstreams: 1 JoseylsonFS_DISSERT_capa_pag209.pdf: 3245188 bytes, checksum: 4b076b4e873e6cc16ab7ec6ceb1c2c79 (MD5) Previous issue date: 2012-11-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The paper presents a discussion about gender and body in the drag queens experience at Natal city (RN). From the different concepts that characterizes the identity processes on subjects who perform gender transformation (transvestites, transsexuals and female impersonators), the justification for studying the drag character is observed as a means to understand matters that are important when you take such a position. Therefore, there is a need for a linkage between the various concepts responsible for this definition, in addition to considering the historical and cultural process responsible for the creation of such categories, identities and stereotypes among these individuals. In this sense it will be possible to carry out a critical analysis on the different social loads present in each representation, and understand what is at stake in the attribution of classifications and terminologies that are applied to different expressions of metamorphosis. This ethnography considers the debate from a field research conducted at LGBT social establishments and other performance spaces of these people, verifying their dynamics in these places and investigating relationships between performers, personas and characters and also backstage scene in which they participate / O texto apresenta uma discuss?o sobre corpo e g?nero na experi?ncia de drag queens na cidade de Natal (RN). A partir das diferentes concep??es que marcam os processos identit?rios sobre sujeitos que realizam transforma??o de g?nero (travestis, transexuais, transformistas), a justificativa por estudar o personagem drag se observa como um meio de entender que quest?es s?o importantes no momento de assumir tal posi??o. Nesse sentido, ? necess?ria uma articula??o entre os variados conceitos respons?veis por esta defini??o, al?m de considerar o processo hist?rico e cultural respons?vel pela cria??o de categorias, estere?tipos e identidades entre estes indiv?duos. Desse modo ser? poss?vel realizar uma an?lise cr?tica sobre as diferentes cargas sociais presentes em cada representa??o e compreender o que est? em jogo na atribui??o de nomenclaturas e terminologias que s?o aplicadas ?s diferentes express?es de metamorfose de g?nero. Esta etnografia contempla o debate a partir de um trabalho de campo realizado em estabelecimentos de sociabilidade LGBT e outros espa?os de atua??o destas pessoas, verificando suas din?micas nestes lugares e investigando rela??es entre int?rpretes, m?scaras e personagens tamb?m nos bastidores da cena da qual participam