Multi-component induction resistivity and sonic measurements acquired in high-angle wells can be strongly influenced by shoulder-bed effects, anisotropy resulting from sand-shale laminations, and presence of mud-filtrate invasion. Understanding the corresponding biasing effects aids in the interpretation of resistivity and sonic measurements and subsequently leads to more accurate and reliable formation evaluation. This dissertation describes numerical simulation studies examining the effects on multi-component induction and sonic measurements in a variety of complex formation models. Subsequently, a joint inversion scheme is presented that combines resistivity and sonic measurements to estimate in situ petrophysical and elastic properties in the presence of mud-filtrate invasion. To facilitate the simulation study of multi-component induction logs, I develop a new finite-difference algorithm for the numerical simulation of frequency-domain electromagnetic borehole measurements. The algorithm~uses a coupled scalar-vector potential formulation for arbitrary three-dimensional inhomogeneous and electrically anisotropic media. Simulations show that shoulder-bed anisotropy: enhances shoulder-bed effects across sand layers; and impacts invasion sensitivities to significantly alter the assessment of invasion in terms of invaded- and virgin-zone resistivities, radial length, and front shape. For the simulation study of sonic logs, I develop a three-dimensional, finite-difference time-domain algorithm that models elastic wave propagation in a fluid-filled borehole. Simulations show that presence of anisotropy not only alters the degree of dispersion observed in flexural and Stoneley waves, but also alters their responses to invasion. In addition, presence of a dipping shoulder bed can significantly distort flexural dispersion, making it difficult to identify the low frequency asymptote corresponding to formation shear wave velocity. Lastly, I consider a radial one-dimensional model in the development of a joint resistivity and sonic inversion algorithm. This scheme simultaneously inverts array-induction apparent conductivities and sonic flexural and Stoneley dispersions for the rock's elastic moduli and water saturation in the presence of mud-filtrate invasion. Inversions are performed on numerically simulated data for a variety of models reflecting soft and hard rock formations with presence of water- and oil-based mud-filtrate invasion. Results show the estimated invasion profiles display excellent agreement with the true models, and the elastic moduli are estimated to within a few percent of the true values. / text

This thesis deals with Computational Fluid Dynamics (CFD)simulations of the flow around delta wings at high angles ofattack. These triangular wings, mainly used in militaryaircraft designs, experience the formation of two vortices ontheir lee-side at large angles of attack. The simulation ofthis vortical flow by solving the Navier-Stokes equations isthe subject of this thesis. The purpose of the work is toimprove the understanding of this flow and contribute to thedesign of such a wing by developing methods that enable moreaccurate and efficient CFD simulations. Simulations of the formation, burst and disappearance of thevortices while the angle of attack is changing are presented.The structured flow solver NSMB has been used to get thetime-dependent solutions of the flow. Both viscous and inviscidresults of a 70°-swept delta wing pitching in anoscillatory motion are reported. The creation of the dynamiclift and the hysteresis observed in the history of theaerodynamic forces are well reproduced. The second part of the thesis is focusing on automatic meshrefinement and its influence on simulations of the delta wingleading-edge vortices. All the simulations to assess the gridquality are inviscid computations performed with theunstructured flow solver EDGE. A first study reports on theeffects of refining thewake of the delta wing. A70°-swept delta wing at a Mach number of 0.2 and an angleof attack of 27° where vortex breakdown is present abovethe wing, is used as testcase. The results show a strongdependence on the refinement, particularly the vortex breakdownposition, which leads to the conclusion that the wake should berefined at least partly. Using this information, a grid for thewing in the wind tunnel is created in order to assess theinfluence of the tunnel walls. Three sensors for automatic meshrefinement of vortical flows are presented. Two are based onflow variables (production of entropy and ratio of totalpressures) while the third one requires an eigenvalue analysisof the tensor of the velocity gradients in order to capture theposition of the vortices in the flow. These three vortexsensors are successfully used for the simulation of the same70° delta wing at an angle of attack of 20°. Acomparison of the sensors reveals the more local property ofthe third one based on the eigenvalue analysis. This lattertechnique is applied to the simulation of the wake of a deltawing at an angle of attack of 20°. The simulations on ahighly refined mesh show that the vortex sheet shed from thetrailing-edge rolls up into a vortex that interacts with theleading-edge vortex. Finally the vortex-detection technique isused to refine the grid around a Saab Aerosystems UnmannedCombat Air Vehicle (UCAV) configuration and its flight dynamicscharacteristics are investigated. Key words:delta wing, high angle of attack, vortex,pitching, mesh refinement, UCAV, vortex sensor, tensor ofvelocity gradients.

Desde o início da história da aviação, a cada novo projeto de aeronave, modificações são realizadas para se obter melhorias nas características aerodinâmicas como, por exemplo, diminuição do arrasto, aumento de sustentação, melhora na manobrabilidade em elevados ângulos de ataque, entre outras. Essas modificações podem ser feitas em diversas partes de uma aeronave como, por exemplo, no perfil aerodinâmico e enflechamento da asa, nas superfícies de controle e até em novas posições da entrada de ar do motor intake. Embora os conceitos de aeronaves com asas de enflechamento negativo, Canard e intake dorsal não sejam novos, ainda não existe uma aeronave que apresente essas três características juntas. Portanto, o presente trabalho teve como objetivo estudar uma aeronave não convencional com essas características. Para isso, testes foram realizados no túnel de vento do Laboratório de Aerodinâmica (LAE), do Departamento de Engenharia Aeronáutica da Escola de Engenharia de São Carlos, da Universidade de São Paulo. Três estudos foram realizados para diferentes ângulos de ataque da aeronave e diferentes ângulos de incidência de três pares de Canard projetados, que foram colocados em duas posições diferentes em relação à asa. No primeiro estudo, as forças aerodinâmicas atuantes na aeronave foram medidas por meio de uma balança aerodinâmica para se obter relações entre seus coeficientes e a eficiência conforme a troca dos pares de Canard. Posteriormente, o estudo do escoamento na entrada do intake dorsal englobou a relação entre a velocidade local no intake, a velocidade do escoamento livre e a recuperação de pressão total no mesmo. Por fim, um mapeamento da vorticidade no campo da asa foi realizado para se analisar a influência do Canard no escoamento raiz da asa. O modelo estudado obteve uma maior eficiência e menor arrasto em elevados ângulos de ataque para ângulos de incidência negativos de Canard. O Canard que se destacou nos dois primeiros estudos foi utilizado no estudo de mapeamento, porém, não apresentou uma influência no escoamento da raiz da asa como desejado. / Since the beginning of aviation history, in each new aircraft design, modifications are made to obtain improvements in aerodynamic characteristics such as drag reduction, increase of lift, improvement in maneuverability at high angles of attack. These modifications can be made in different parts of an aircraft, such as, aerodynamic profile, on the control surfaces and even in new intake positions. Although the concepts of aircraft with forward swept wing, Canard and dorsal intake are not new, there is still no aircraft that presents these three characteristics together. Therefore, the present work had as objective to study an unconventional aircraft with these characteristics. Wind tunnel tests were carried out in order to analyze the aerodynamic characteristics at the Aerodynamics Laboratory of the Department of Aeronautical Engineering of EESC-USP. Three studies were carried out for different angles of attack of the aircraft and different angles of incidence of three pairs of Canard, which were placed in two different positions in relation to the wing. In the first study, the aerodynamic forces acting on the aircraft were measured by an aerodynamic balance to obtain relations between their coefficients and the efficiency according to the change of the Canard pairs. Subsequently, the study of flow at the entrance of the dorsal intake included the relation between the local velocity at the intake and the velocity of the free flow and the total pressure recovery. Finally, a mapping of vorticity in the wing field was performed to analyze the influence of Canard on the boundary layer at the root of the wing. The model studied obtained higher efficiency and lower drag at high angles of attack at negative Canard angles of incidence. The Canard that stood out in the first two studies was used in the mapping study, however, it did not present an influence on the root of the wing as desired.

In recent years, optical near-field has received an ever-increasing attention owing to its ability to localise optical signals beyond the diffraction limit. Optical near-field is a non-propagating field existing in the close vicinity of a matter within a range less than the wavelength of the illumination light and it carries the high spatial frequency information showing the fine details of the matter. An optical near-field can be generated by a near-field optical microscope with a nano-aperture or a metal-coated fibre tip. However, common difficulties associated with this approach, such as a fragile probe, a low throughput and signal-to-noise ratio, and a slow response of gap controlling between the probe and the sample, make it less applicable. Alternatively, optical near-field can be produced by total internal reflection (TIR) occurring at the interface of a prism, which is capable of localising the electromagnetic (EM) field in the close vicinity of the interface. However, in this geometry, no confinement of the field can be achieved in the transverse direction, whereas, in most applications such as optical trapping, micro-fabrication and optical data storage, a transverse confinement of the light field is essential. In order to achieve a transverse confinement of the light field, maintaining the high spatial resolution of the optical near-field, and at the same time eliminating the drawbacks associated with the conventional near-field optical microscope, a novel near-field probe based on a high numerical aperture (NA) TIR objective combined with annular illumination has been developed recently. In this arrangement, an obstruction disk is inserted at the back aperture of the objective to block the light with a convergence angle lower than the critical angle determined by the refractive indices of the two media, resulting in a pure focused evanescent field in the second medium. The evanescent field produced by this method provides a useful tool for studying light-matter interaction at the single molecule level not only because of its high resolution but also due to its inherent merits such as no distance regulation, no heating effect and simple experimental setup. But, the most significant advantage that makes this method unique and superior to the other approaches in terms of producing the optical near-field is that it allows the dynamic control of the focal field by simply modulating the phase or amplitude or even the polarisation state of the incident beam before it enters the objective so that complex illumination beams can be generated, whereas in other fibre probe based approaches this goal is extremely difficult to achieve. To make use of such a novel near-field probe, a thorough theoretical and experimental investigation is required. A complete knowledge of the focused evanescent field is a prerequisite for a wide range of applications including single molecule detection, Raman spectroscopy, near-field non-linear imaging and near-field trapping. Therefore, it is not only necessary but also urgent to exploit the focusing properties of a focused evanescent field under complex field illumination both experimentally and theoretically and this is the major aim of this thesis. The complex fields, which are of particular interest in this thesis, are the radially polarised beam and the Laguerre-Gaussian (LG) beam, because the former owns a more compact circularly symmetric field distribution in the focal region when focused by a high NA objective, while the latter is capable of rotating a trapped particle by transferring the orbital angular momentum. Combining them with the focused evanescent field is potentially able to induce novel functions in the near-field region, which cannot be fulfilled by other near-field approaches. In this thesis, in order to generate these two types of beams, a single liquid crystal spatial light modulator (LCSLM) is employed to produce useful phase modulation to the incident beam. Experimental characterisation of an evanescent focal spot is performed with scanning near-field optical microscopy (SNOM), which is capable of providing the direct mapping of the focused evanescent field not only because of its high spatial resolution and its ability to detect the near-field and far-field signals simultaneously, but also due to the motion of the piezzo-stage enables a three-dimensional characterisation of the evanescent focal spot. In this thesis, a SNOM system with an aluminum coated aperture probe is implemented. The field distributions at both the interface and parallel planes with a small distance away from the interface are obtained. To verify the applicability of SNOM as a characterisation methodology, the field distribution in the focal region of a high NA objective illuminated by a linearly polarised plane wave is measured first. A focus splitting along the direction of incident polarisation is observed threedimensionally near the interface under such a circumstance. It has been demonstrated that the depolarisation effect plays an important role in determining the coupling behaviour of the light into the fibre probe of SNOM. The good match between the experimental results and theoretical predications confirms the validity of SNOM. Theoretical investigation of a tightly focused radially polarised beam is undertaken based on the vectorial-Debye diffraction theory because under the tight focusing of a high NA objective, the vectorial nature of the highly localised field has to be carefully considered in order to represent the field distribution accurately. The calculations on the focusing properties of a radially polarised beam suggest that the longitudinal field component in the focal region plays a dominant role in determining the overall field distribution. Direct measurement of the focused evanescent radially polarised beam in a three-dimensional manner near the interface is performed with SNOM. A highly localised focal spot is achieved in the close vicinity of the coverglass. The measured intensity distributions from SNOM show that correction of the focal spot deformation associated with a linearly polarised beam is achieved by taking advantage of the radially symmetric focal spot of a radially polarised beam. A smaller focal spot is acquired due to the dominant longitudinal polarisation component in the focal region, which possesses a more compact focal intensity distribution than that of the overall field. The experimental results demonstrate a good agreement with the theoretical expectations. The fact that a radially polarised beam is capable of eliminating the focus deformation often presented in the focal region of a high NA objective when a linearly polarised beam is employed can be very useful in many applications, including microfabrication using two-photon photopolymerisation technique. The theoretical study on the two-photon point spread function (PSF) of a radially polarised beam indicates that the focus elongation and splitting associated with a linearly polarised beam are eliminated and the achievable lateral size of the focal spot is approximately a quarter of the illumination wavelength, which is less than half of that under the illumination of a linearly polarised beam. A further reductiont of the lateral size can be expected by using annular radial beam illumination. The investigation on the focusing properties of LG beams has also been one of the major tasks of this thesis. Theoretical investigations of a focused evanescent LG beam suggest that the phase shift induced by the boundary effect when a light beam passes the interface satisfying TIR condition plays a vital role in determining the overall shape of the total field distribution. A severe focal intensity deformation is predicted theoretically in the case of focused evanescent LG beam illumination, which might involve new physical phenomena when applied in the near-field trapping. Such a focal intensity deformation is evidenced experimentally by the direct mapping result obtained from the SNOM probe. A quantitative cross-section comparison with the theoretical predication is conducted, which demonstrates a good agreement. To achieve a controllable optical trap and rotation in the near-field region, complex optical fields such as LG beams carrying orbital angular momentum, have been induced for the manipulation of a polystyrene particle. The influence of the focal intensity deformation on a near-field trapping has been thoroughly investigated. Rotation motion of the particle is examined by mapping the two-dimensional (2D) transverse trapping efficiency of the particle. Theoretical investigation reveals that a significant tangential force component is generated on the particle when it is illuminated by a focused evanescent LG beam. Such findings may prove useful in introducing a rotation mechanism in near-field trapping. The research investigations and methodologies described in this thesis provide a new approach to characterise the near-field focal spot under complex field illumination. It enhances the understanding of the novel near-field probe, thus opening the pathway for numerous near-field applications including optical trapping, two-photon excitation (photopolymerisation) and spectroscopy. The focal field rotation phenomena demonstrated in this thesis may prove particularly beneficial in introducing a rotation mechanism in near-field trapping using a focused evanescent field.

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<p>This thesis deals with Computational Fluid Dynamics (CFD)simulations of the flow around delta wings at high angles ofattack. These triangular wings, mainly used in militaryaircraft designs, experience the formation of two vortices ontheir lee-side at large angles of attack. The simulation ofthis vortical flow by solving the Navier-Stokes equations isthe subject of this thesis. The purpose of the work is toimprove the understanding of this flow and contribute to thedesign of such a wing by developing methods that enable moreaccurate and efficient CFD simulations.</p><p>Simulations of the formation, burst and disappearance of thevortices while the angle of attack is changing are presented.The structured flow solver NSMB has been used to get thetime-dependent solutions of the flow. Both viscous and inviscidresults of a 70°-swept delta wing pitching in anoscillatory motion are reported. The creation of the dynamiclift and the hysteresis observed in the history of theaerodynamic forces are well reproduced.</p><p>The second part of the thesis is focusing on automatic meshrefinement and its influence on simulations of the delta wingleading-edge vortices. All the simulations to assess the gridquality are inviscid computations performed with theunstructured flow solver EDGE. A first study reports on theeffects of refining thewake of the delta wing. A70°-swept delta wing at a Mach number of 0.2 and an angleof attack of 27° where vortex breakdown is present abovethe wing, is used as testcase. The results show a strongdependence on the refinement, particularly the vortex breakdownposition, which leads to the conclusion that the wake should berefined at least partly. Using this information, a grid for thewing in the wind tunnel is created in order to assess theinfluence of the tunnel walls. Three sensors for automatic meshrefinement of vortical flows are presented. Two are based onflow variables (production of entropy and ratio of totalpressures) while the third one requires an eigenvalue analysisof the tensor of the velocity gradients in order to capture theposition of the vortices in the flow. These three vortexsensors are successfully used for the simulation of the same70° delta wing at an angle of attack of 20°. Acomparison of the sensors reveals the more local property ofthe third one based on the eigenvalue analysis. This lattertechnique is applied to the simulation of the wake of a deltawing at an angle of attack of 20°. The simulations on ahighly refined mesh show that the vortex sheet shed from thetrailing-edge rolls up into a vortex that interacts with theleading-edge vortex. Finally the vortex-detection technique isused to refine the grid around a Saab Aerosystems UnmannedCombat Air Vehicle (UCAV) configuration and its flight dynamicscharacteristics are investigated.</p><p><b>Key words:</b>delta wing, high angle of attack, vortex,pitching, mesh refinement, UCAV, vortex sensor, tensor ofvelocity gradients.</p>

Nuclear logging-while-drilling (LWD) measurements acquired in high-angle and horizontal (HA/HZ) wells are influenced by tool, geometrical, and petrophysical effects. Reliable interpretation of petrophysical and geometrical properties from LWD measurements acquired in thinly-bedded formations requires that gamma ray, density, photoelectric (PEF), and neutron measurements be quantitatively integrated with explicit consideration of their effective volume of investigation (EVOI). One of the effects of different tool EVOIs is false gas density-neutron crossovers across thinly-bedded formations. Also, in the presence of tool eccentricity, azimuthally-varying standoff gives rise to an azimuthally-varying effective depth of investigation (EDOI), which introduces errors in the inference of formation dip. Conventional Monte Carlo simulations of nuclear measurements are computationally expensive in reproducing multi-sector LWD responses in HA/HZ wells. Using linear iterative refinement of pre-calculated flux sensitivity functions (FSFs), we introduce a fast method for numerical simulation of LWD nuclear images in the presence of tool eccentricity along any well trajectory. Our investigation of measurement responses from FSFs motivates techniques to explicitly consider the EVOI of LWD nuclear measurements. Simple radial DOI and standoff corrections suffice for interpretation of gamma-gamma images but are inadequate for neutron responses due to larger EVOI and azimuthal aperture. We introduce a new azimuthal deconvolution method of neutron images to improve bed-boundary detection. Neutron DOI varies significantly with porosity, whereby we correct neutron images for penetration length due to changes of porosity along the well trajectory. In addition, we implement a new method of separate linear iterative refinement on neutron thermal group responses to improve the resolution of neutron images across heterogeneous and thinly-bedded formations. The method reduces shoulder-bed effects and false neutron-density gas crossovers. We corroborate these techniques with rigorous Monte Carlo simulations in vertical and deviated wells. A field example of application conclusively indicates that numerical simulation of LWD nuclear measurements is necessary for reliable estimation of petrophysical properties. / text

The objective of the present research is to investigate unsteady aerodynamic models with state equation representations that are valid up to the high angle of attack regime with the purpose of evaluating them as computationally affordable models that can be used in conjunction with the equations of motion to simulate wing rock. The unsteady aerodynamic models with state equation representations investigated are functional approaches to modeling aerodynamic phenomena, not directly derived from the physical principles of the problem. They are thought to have advantages with respect to the physical modeling methods mainly because of the lower computational cost involved in the calculations. The unsteady aerodynamic multi-axis models with state equation representations investigated in this report assume the decomposition of the airplane into lifting surfaces or panels that have their particular aerodynamic force coefficients modeled as dynamic state-space models. These coefficients are summed up to find the total aircraft force coefficients. The products of the panel force coefficients and their moment arms with reference to a given axis are summed up to find the global aircraft moment coefficients. Two proposed variations of the state space representation of the basic unsteady aerodynamic model are identified using experimental aerodynamic data available in the open literature for slender delta wings, and tested in order to investigate their ability to represent the wing rock phenomenon. The identifications for the second proposed formulation are found to match the experimental data well. The simulations revealed that even though it was constructed with scarce data, the model presented the expected qualitative behavior and that the concept is able to simulate wing rock. / Ph. D.

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