This work is focused on the aerodynamics for a proprietary laminar flow airfoil for Unmanned Aerial Vehicle (UAV) applications. The two main focuses are (1) aerodynamic performance at Reynolds number on the order of 10,000, (2) the effect of a conventional hot-wire probe on laminar separation bubbles. For aerodynamic performance, pressure and wake velocity distributions were measured at Re = 40,000 and 60,000 for a range of angles of attack. The airfoil performed poorly for these Reynolds numbers due to laminar boundary layer separation. 2-D boundary layer trips significantly improved the lift-to-drag ratio. For probe effects, three Reynolds numbers were investigated (Re = 100,000, 150,000, and 200,000), with three angles of attack for each. Pressure and surface shear distributions were measured. Flow upstream of the probe tip was not affected. Transition was promoted downstream due to the additional disturbances in the separated shear layer.

The Skelton Glacier is one of the many smaller outlet glaciers located in the Transantarctic Mountains, where it drains ice into the Ross Ice Shelf. These outlet glaciers are important when determining the past, present, and future state of the mass balance of the East Antarctic Ice Sheet. This research uses satellite imagery acquired over a period of 15 years to obtain a high resolution velocity field for the Skelton Glacier which is then used to calculate the mass flux and mass balance at ten flux gates along the glacier using the input-output method. The high resolution velocity field is combined with ice thickness data and accumulation data from other sources to obtain the total mass balance. The high resolution velocity field of the Skelton Glacier was created using European Remote-Sensing Satellite 1 and 2 (ERS-1/2) Synthetic Aperture Radar (SAR) data acquired in 1996 with the processing technique of SAR interferometry (InSAR). Because of the lack of differential InSAR pairs, new auxiliary data from the ICESat and TanDEM-X mission were included into the analysis. A velocity field was created at a spatial resolution of 50m which was validated with in situ GPS measurements from 2011/12, and compared to lower resolution velocity fields of the Skelton Glacier. The ice velocity field is at improved accuracy for this area compared to previous studies and is thought to be representative for the mean ice velocity. The analysis of ice flux at several flux gates allowed an improved error estimation of the applied technique to estimate the overall mass balance. Mass flux estimates along the glacier were calculated using the new velocity field and additional thickness data, which was then compared to two accumulation datasets to give mass balance estimates along the glacier at selected flux gates. The mass flux through the grounding line was found to be 1.2165 Gt a⁻¹, which needs to be balanced in a state of mass balance equilibrium by a mean annual snow accumulation of about 185 mm a⁻¹ water equivalent over the total catchment area determined with 6569 km². The mass balance at the grounding line is slightly negative, but the second flux gate is thought to be more representative of the mass balance, which is estimated to be 0.0441 Gt a⁻¹. Error analysis of the mass balance estimates found uncertainties in this data to be approximately 0.110 Gt a⁻¹. It is concluded from the analysis that further improvements in the overall mass balance estimate can be primarily obtained by a better knowledge of ice thickness and snow accumulation.

No description available.

In this dissertation we use digital holographic quantitative phase microscopy to observe and measure phase-only structures due to induced photothermal interactions and nanoscopic structures produced by photomechanical interactions. Our use of the angular spectrum method combined with off-axis digital holography allows for the successful hologram acquisition and processing necessary to view these phenomena with nanometric and, in many cases, subnanometric precision. We show through applications that this has significance in metrology of bulk fluid and interfacial properties. Our accurate quantitative phase mapping of the optically induced thermal lens in media leads to improved measurement of the absorption coefficient over existing methods. By combining a mathematical model describing the thermal lens with that describing the surface deformation effect of optical radiation pressure, we simulate the ability to temporally decouple the two phenomena. We then demonstrate this ability experimentally as well as the ability of digital holography to clearly distinguish the phase signatures of the two effects. Finally, we devise a pulsed excitation method to completely isolate the optical pressure effect from the thermal lensing effect. We then develop a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase imaging technique to track a propagating nanometric capillary disturbance. We demonstrate the method's ability to accurately measure the surface energy of pure media and chemical monolayers formed by surfactants with good agreement to published values. We discuss the possible adaptation of this technique to applications for living biological cell membranes.

A novel delamination identification technique based on a low-population genetic algorithm for the quantitative characterisation of a single delamination in composite laminated panels is developed, and validated experimentally The damage identification method is formulated as an inverse problem through which system parameters are identified. The input of the inverse problem, the central geometric moments (CGM), is calculated from the surface out-of-plane displacements measurements of a delaminated panel obtained from Digital Speckle Pattern Interferometry (DSPI). The output parameters, the planar location, size and depth of the flaw, are the solution to the inverse problem to characterise an idealised elliptical flaw. The inverse problem is then reduced to an optimisation problem where the objective function is defined as the L2 norm of the difference between the CGM obtained from a finite element (FE) model with a trial delamination and the moments computed from the DSPI measurements. The optimum crack parameters are found by minimising the objective function through the use of a low-population real-coded genetic algorithm (LARGA). DSPI measurements of ten delaminated T700/LTM-45EL carbon/epoxy laminate panels with embedded delaminations are used to validate the methodology presented in this thesis.

No description available.

Optical Coherence Tomography (OCT) is a relatively new interferometric technology that allows for high-resolution and non-destructive tomographic imaging. One of its primary current uses is for in vivo and ex vivo examination of medical samples. It is used for non-destructive examination of ocular disease, dermatological examination, blood vessel imaging, and many other applications. Some primary advantages of OCT imaging include rapid imaging of biological tissue with minimal sample preparation, 3D high-resolution imaging with depth penetrations of several millimeters, and the capability to obtain results in real time, allowing for fast and minimally invasive identification of many diseases. Current commercial OCT systems rely heavily on optical fiber-based designs. They depend on the robustness of the fiber to maintain system performance in variable environmental conditions but sacrifice the performance and flexibility of free-space optical designs. We discuss the design and implementation of a free-space OCT interferometer that can automatically maintain its alignment, allowing for the use of a free-space optical design outside of tightly controlled laboratory environments. In addition, we describe how similar enhancements can be made to other optical interferometric systems. By extending these techniques, we can provide similar improvements to many related fields, such as interferometric metrology and Fourier Transform Spectroscopy. Improvements in these technologies can help bring powerful interferometric tools to a wider audience.

In this thesis a powerful and practical method for characterizing ultrashort pulses in space and time is described (called SEA TADPOLE). First we focus on measuring pulses that are spatially uniform but very complicated in time or frequency. We demonstrate and verify that SEA TADPOLE can measure temporal features as small as 30 femtoseconds over durations as long as 14 picoseconds. The spectral resolution of this device is carefully studied and we demonstrate that for certain pulses, we achieve spectral super resolution. We also develop and test an algorithm for measuring polarization shaped pulses with SEA TADPOLE. Our simple interferometer can even be used to measure the spatiotemporal electric field of ultrashort pulses at a focus. This is because SEA TADPOLE samples the field with an optical fiber which has a small core size. Therefore this fiber can be used to spatially sample the beam, so that the temporal electric field can be measured at every position to obtain E(x, y, z, t). The single mode fiber can be replaced with an NSOM (Near Field Scanning Optical Microscopy) fiber so that spatial resolution as low as 500nm (and possibly lower) can be achieved. Using this device we make the first direct measurements of the compete field of focusing ultrashort pulses. These measurement can be viewed as "snap shots" in flight of the focusing pulse. Also, for the first time, we have observed some of the interesting distortions that have been predicted for focusing ultrashort pulses such as the "forerunner" pulse, radially varying group delay dispersion, and the Bessel-like X-shaped pulse. We have also made the first direct measurements of the electric field of Bessel X-pulses and their propagation invariance is demonstrated. We also use SEA TADPOLE to study the "boundary wave pulses" which are due to diffraction.

Gas composition and analysis forms a large field of research whose requirements demand that measurement equipment be as affordable, uncomplicated and convenient as possible. The precise quantitative composition of an atmospheric, industrial or chemically synthesised sample of gas is of utmost importance when inferring the properties and nature of the environment from which the sample was taken, or for inferring how a prepared sample will react in its application. The most popular and widely used technique to achieve this is Gas Chromatography-Mass Spectrometry (GCMS) and, without a doubt, this technique has set the standard for gas analysis. Despite the accuracy of the GCMS technique, the equipment itself is bulky, expensive and cannot be applied readily to field work. Instead, most field work is conducted using a single gas detector, capable only of detecting one particular molecule or element at a time. Presented here is an interferometric technique that theoretically, has the ability to address all three issues of bulkiness, affordability and convenience, whilst not being limited to one particular element or molecule in its analysis. Identifying the unknown constituents of a gaseous mixture using the proposed method, employs the optical refractive properties of the mixture to determine its composition. A key aspect of this technique is that the refractive index of an arbitrary mixture of gases will vary depending on pressure and wavelength1. The Lorentz-Lorenz formula and the Sellmeier equations form the foundation of the theoretical background. The optical refractive properties of air and other atmospheric gases have been well established in the literature. The experimental investigations described here have been conducted based on this, insofar as no analysis has been conducted on gases that do not naturally occur in reasonable abundance in the atmosphere. However this does not in any way preclude the results and procedure developed from applying to a synthesised gas mixture. As mentioned, the platform of this technique relies on the pressure and wavelength dependence of the refractivity of the gas. The pressure dependence of the system is easily accounted for, in making this claim however it is still imperative the mixture be impervious to contamination from the wider atmosphere. Wavelength dependence however is perhaps slightly more difficult to accommodate. Multiple lasers, of differing wavelength form the radiative sources which underpin the method developed. Laser sources were chosen because of their coherence, making it easy to produce interference, when combined with the inherent stability of the Sagnac interferometer, provides for a very user friendly system that is able to quickly take results. The other key part of the experimental apparatus is the gas handling system, the gas(es) of interest need to be contained within an optical medium in the path of one of the beams of the interferometer. Precise manipulation of the pressure of the gas is critical in determining concentration, this has been achieved through the use of a gas syringe whose plunger is moved on a finely threaded screw, and measured on a digital manometer. The optical setup has also been explored, specifically in ruling out the use of such radiative sources as passing an incandescent source through a monochromator or the use of LED's to produce interference before settling on lasers to produce the required interference. Finally, a comprehensive theoretical background has been presented using classical electromagnetic theory as well as confirmation from a quantum perspective. The theoretical background for this study relies upon the Lorentz-Lorenz formula. It is commonly presented either from a classical or quantum perspective, in this work both classical and quantum mechanical treatments are given whilst also showing how each confirms the other. Furthermore, a thorough investigation into the dispersion functions of each of the major components of the atmosphere has been compiled from the study of refractivity on individual gases from other authors, in some cases, where no work has been done previously, this has been derived. The technique developed could be considered an ample addition to gas analysis techniques in certain circumstances in terms of expense, convenience and accuracy. The system can predict relative quantities of constituents of the atmosphere to at least 3%. The method described here would allow researchers more time to concentrate on actual results and more resources to allocate to broadening intellectual horizons. This would certainly justify further development.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.