Theses and Dissertations at Montana State University (MSU)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/732
Browse
12 results
Filters
Settings
Search Results
Item Experimental characterization of pore-scale capillary pressure and corner film flow in 2D porous micromodels(Montana State University - Bozeman, College of Engineering, 2023) Molla, Razin Sazzad; Chairperson, Graduate Committee: Yaofa LiMultiphase flow in porous media is ubiquitous in natural and engineering processes. A better understanding of the underlying pore-scale physics is crucial to effectively guiding, predicting and improving these applications. Traditional models describe multiphase flows in porous media based on empirical constitutive relations (e.g., capillary pressure vs. saturation), which, however, are known to be hysteretic. It has been theoretically shown that the hysteresis can be mitigated by adding new variables in the functional form. However, experiments are still needed to validate and further develop the theories. In particular, our understanding of capillary pressure characterization and numerous pore-scale mechanisms is still limited. For instance, during capillary pressure measurement, fluid phases become disconnected, making the bulk pressure an inaccurate measure for the actual capillary pressure. In a strongly wetting medium, wetting phase always remains connected by corner films, through which trapped water continues to drain until a capillary equilibrium is reached, but the effects of corner film flow are minimally characterized. In this thesis, two different experiments are presented. In the first experiment, we focused on the capillary pressure characterization and the effect of measurement resolution. Microscopic capillary pressure along with other geometric measures are characterized during drainage and imbibition. By strategically varying the pressure at the boundary, different equilibrium states were achieved and imaged at four different magnifications (i.e., 2, 1.25, 0.5, 0.25 micron/pixel). In the second experiment, we for the first time characterized the corner film flow again during drainage and imbibition condition employing particle image velocimetry. Overall, our results suggest that the calculated macroscale pressure P c and the bulk pressure drop agree reasonably well when only interfaces associated with the connected phases are considered. A spatial resolution of 2 micron/pixel seems to sufficiently resolve the interface, and further increasing the resolution does not have a significant impact on the results. Additionally, corner film flow was found to be an active transport mechanism. During drainage, trapped water is continuously drained over time via thin film, whereas during imbibition snap-off events are enhanced by wetting films. These observations call for future studies to carefully treat corner film flows when developing new predictive models.Item Stigmatic spectroscopy of the solar atmosphere in the vacuum-ultraviolet(Montana State University - Bozeman, College of Letters & Science, 2020) Courrier, Hans Thomas; Chairperson, Graduate Committee: Charles C. Kankelborg; Charles C. Kankelborg was a co-author of the article, 'Using local correlation tracking to recover solar spectral information from a slitless spectrograph' in the journal 'Journal of astronomical telescopes and imaging systems, SPIE' which is contained within this dissertation.; Charles C. Kankelborg, Bart De Pontieu and Jean-Pierre Wulser were co-authors of the article, 'An on orbit determination of point spread functions for the interface region imaging spectrograph' in the journal 'Solar physics' which is contained within this dissertation.; Charles C. Kankelborg, Amy R. Winebarger, Ken Kobayashi, Brent Beabout, Dyana Beabout, Ben Carroll, Jonathan W. Cirtain, James A. Duffy, Carlos Gomez, Eric M. Gullikson, Micah Johnson, Jacob D.Parker, Laurel A. Rachmeler, Roy T. Smart, Larry Springer and David L. Windt were co-authors of the article, 'The EUV snapshot imaging spectrograph (ESIS)' which is contained within this dissertation.The solar atmosphere presents a complicated observing target since tremendous variability exists in solar features over a wide range of spatial, spectral, and temporal scales. Stigmatic spectrographs are indispensable tools that provide simultaneous access to spatial context and spectroscopy, enabling the diagnosis of solar events that cannot be accomplished by imaging or spectroscopy alone. In this dissertation I develop and apply a novel technique for on orbit spectrograph calibration, recover co-temporal Doppler shifts of widely spaced solar features, and describe a new design for a slitless solar spectrograph. The Interface Region Imaging Spectrograph, (IRIS) is currently the highest spatial and spectral resolution, space based, solar spectrograph. Ongoing calibration is important to maintaining the quality of IRIS data. Using a Mercury transit against the backdrop of the dynamic solar atmosphere, I characterize the spatial point spread functions of the spectrograph with a unique, iterative, blind, deconvolution algorithm. An associated deconvolution routine improves the ability of IRIS to resolve spatially compact solar features. This technique is made freely available to the community for use with past and future IRIS observations. The Multi-Order Extreme Ultraviolet Spectrograph (MOSES) is a slitless spectrograph that collects co-temporal, but overlapping spatial and spectral images of solar spectral lines. Untangling these images presents an ill-posed inversion problem. I develop a fast, automated method that returns Doppler shifts of compact solar objects over the entire MOSES field of view with a minimum of effort and interpretation bias. The Extreme ultraviolet Snapshot Imaging Spectrograph (ESIS) is a slitless spectrograph that extends the MOSES concept. I describe this new instrument, which is far more complex and distinct as compared to MOSES, and the contributions I made in the form of optical design and optimization. ESIS will improve the quality of spatial and spectral information obtained from compact and extended solar features, and represents the next step in solar slitless spectroscopy. Taken together, these contributions advance the field by supporting existing instrumentation and by developing new instrumentation and techniques for future observations of the solar atmosphere.Item Iterative methods for total variation based image reconstruction(Montana State University - Bozeman, College of Letters & Science, 1995) Oman, Mary EllenItem GAP 2 : an image processing package for UNIX(Montana State University - Bozeman, College of Engineering, 1997) Kalmykov, YuriItem Support for the camera model(Montana State University - Bozeman, College of Engineering, 1992) Kincses, GaborItem Reconstructing free form 3D objects from 2D images with PEX(Montana State University - Bozeman, College of Engineering, 1994) You, XiaItem The design of an automatic vision switching system(Montana State University - Bozeman, College of Engineering, 1998) Feng, ChunshengThe importance of Robotics has been recognized by the manufacturing industry. The introduction of Computer Vision has greatly increased the versatility and application domain of robots such as the interaction between the robot and its changing environment. From previously developed vision position correction methods and currently used visual servo-feedback techniques, computer vision systems present many possibilities in improving the quality and productivity of an industrial product. But computer vision systems also have limits in dealing with some robotic tasks such as Storage Battery Cap Installation. Random geometric distortion exists, which results from the characteristics of battery material or from the positioning error of fixtures. Robotic teaching-playback method can not guarantee the assembly precision when deviation happens. A vision system introduced into the robotic system allows it to respond to an uncertain environment. Conventional vision correction methods only drive robots to the final position without considering robotic trajectory control. They reduce the robotic operation speed compared with stable conditions. Visual servo-feedback techniques can generate the optimal path and assembly precision, but the calculation of visual servo control algorithm is time consuming. It also reduces robotic execution time. In addition, random assembly tasks sometimes do not need vision correction. So the justification of this robotic vision system is improved robotic assembly accuracy that does not affect other robot performance. In this thesis a new robotic vision control system, Automatic Vision Switching System (AVSS), was designed. It was derived from the concept of Just-in-Time and dealt with the installation of storage battery caps. It demonstrated a vision system that functions to correct just when it is needed. Image processing techniques for solving the battery hole’s centroid values were included in AVSS design. The experiment was carried out based on an AdeptOne robot, a Vision-EZ system, a camera with eye-in-hand configuration, and a battery model. The experimental results showed that the AVSS can integrate a vision system with a robotic system efficiently. The AVSS identified the deviation of battery holes’ locations and generated the corrected values in real time. The control accuracy, operation speed and optimal path of robotic manipulator were obtained. The AVSS can also be used in other industrial tasks where random variation is present.Item Three dimensional visualization of medical images(Montana State University - Bozeman, College of Engineering, 1994) Pandurangam, Premkumar ManangamItem Image analysis of leafy spurge (Euphorbia esula L.) cover(Montana State University - Bozeman, College of Agriculture, 1995) Birdsall, Jennifer LeeItem Non-destructive soil testing using x-ray computed tomography(Montana State University - Bozeman, College of Engineering, 2004) Nielsen, Brent Daniel; Chairperson, Graduate Committee: Robert L. MokwaThe mechanical behavior of soils is highly dependent on the particle microstructure. Traditional geotechnical engineering soil tests generally do not measure soil properties on a micro-scale; instead, macro scale properties are commonly used as estimates of microstructure properties in determining soil engineering behavior. Additionally, traditional geotechnical engineering soil tests are destructive in nature, and many test methods destroy the same soil properties they intend to measure. The goal of this research was to develop non-destructive soil test methods using x-ray computer-aided tomography (CT) scanning techniques to determine soil index properties. The CT scanning process provides a promising method for examining soil microstructure in a non-destructive manner. This research had two main objectives. The first was to configure the Montana State University Civil Engineering Department's computer-aided tomography scanner to perform CT scans on soil samples. The second objective was to use the CT scanner to develop nondestructive test procedures to determine geotechnical index properties of soils. Test methods were developed in this study to determine porosity, grain size distribution, and pore size distribution. The results from the first objective showed that the MSU CT scanning equipment is capable of producing high quality CT scans of soil materials. Resolution limitations of the scanner define the smallest soil grain size that is detectable in a CT scan, but the scan resolution may be improved by using smaller sample sizes for small particle soils. The results of the second portion of the study show that the non-destructive CT scanning test methods compare favorably with traditional geotechnical laboratory mechanical test methods. CT-measured porosity values and grain size distributions compared well with mechanical testing results, which were used to validate the new test methods. In addition, the CT-measured pore size distributions were in good agreement with an accepted pore size mathematical model. Since traditional pore size distribution tests are time-consuming, labor intensive, and destructive in nature, the non-destructive x-ray CT scanning test methods developed in this study show strong promise as a means for measuring an elusive soil property that cannot be accurately measured using traditional geotechnical testing procedures.