Browsing by Subject "Phase"
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Item A Comparison of Three Equation of State Compositional Simulators(1984-05) Thele, Kent Joseph; Lake, Larry W.; Sepehrnoori, KamyDuring the past two decades, approximately one formulation per year has been published for compositional simulators. However, until now, no consistent comparison has been made on any of them. Three of these formulations were implemented on the Dual Cyber 170/750 machine and compared. Formulations by Nghiem, Fong, and Aziz (NFA) and Young and Stephenson (YS) were programmed for one and two dimensional problems, and the fully implicit formulation by Coats (C) was coded for one dimensional applications. These formulations were compared with respect to computer memory requirements, accuracy, and number of iterations and computation times required to satisfy carefully chosen convergence criteria. The phase behavior was modeled with the Peng-Robinson equation of state, and the flash calculations were performed using an accelerated successive substitution scheme by Mehra, Heidemann, and Aziz. From three to fifteen components were used in the test problems which consisted of multiple contact miscible and immiscible gas drives, a minimum miscibility pressure determination, and a carbon dioxide flood in a half of a five-spot pattern.Item Optical coherence tomography for retinal diagnostics(2013-08) Yin, Biwei; Milner, Thomas E.; Rylander, H. Grady (Henry Grady), 1948-Optical Coherence Tomography (OCT) is a non-invasive three-dimensional imaging technique. OCT synthesizes a cross-sectional image from a series of lateral adjacent depth scans, and with a two-dimensional scanning scheme, three-dimensional intensity image of sample can be constructed. Due to its non-invasive capability, OCT has been widely applied in ophthalmology, cardiology and dermatology; and in addition to three-dimensional intensity image construction, various functional OCT imaging techniques have been developed for clinical application. My research is focused on developing functional OCT systems for application in ophthalmology, including polarization-sensitive optical coherence tomography (PS-OCT) for retinal nerve fiber layer (RNFL) birefringence measurement and dual-wavelength photothermal optical coherence tomography (DWP-OCT) for microvasculature blood oxygen saturation (SO2) measurement. In the study, a single-mode-fiber based polarization-sensitive swept-source OCT (PS-SS-OCT) with polarization modulator, polarization-sensitive bulk-optics balanced detection module is constructed and polarization processing methods based on Stokes vectors are applied to determine birefringence. PS-OCT is able to provide human subject's RNFL thickness, phase retardation, and birefringence information. Degradation in the degree of polarization (DOP) along depth is investigated and its difference between four quadrants of RNFL (superior, temporal, inferior and nasal) indicates the structural property difference. DWP-OCT is a novel functional OCT system consisting of a phase-sensitive optical coherence tomography system (PhS-OCT) and two photothermal excitation lasers. PhS-OCT is based on a swept-source laser operating in the 1060 nm wavelength range; the two photothermal excitation lasers with wavelength 770 nm and 800 nm are intensity modulated at different frequencies. PhS-OCT probe beam and two photothermal excitation beams are combined and incident on the sample, optical pathlength (op) change on the sample introduced by two photothermal excitation beams are measured and used for blood SO2 estimation. A polarization microscope is proposed for future study. The polarization microscope is an imaging technique providing molecular structure and orientation based on probe light's polarization state information. The polarization microscope uses a wavelength tunable light source, and can achieve any incident polarization state by a retarder-rotator combination. Specimen's birefringence can be determined based on the changing of detected light amplitude.