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Dissertations / Theses on the topic 'Fluid imaging'

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Published: 4 June 2021

Last updated: 15 February 2022

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1

Gay, Etienne. "Coherent interferometric imaging in fluid dynamics." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7029.

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La présente recherche vise à développer des algorithmes d’imagerie par interférométrie cohérente (CINT) pour localiser des sources et des réflecteurs dans des applications impliquant des écoulements. L’imagerie CINT s’est avérée efficace et statistiquement stable dans des milieux inhomogènes au repos, où les techniques classiques d’imagerie, telles que la migration de Kirchhoff (KM), peuvent éventuellement échouer en raison de leur manque de robustesse statistique. Nous visons à étendre ces méthodes aux milieux en mouvement inhomogènes, car elles concernent l’aéroacoustique, l’acoustique atmosphérique et sous-marine, la propagation des infrasons, voire l’astrophysique. Dans ce rapport de thèse, nous abordons à la fois le problème direct de la modélisation de la propagation des ondes acoustiques dans un écoulement ambiant hétérogène et aléatoire, et le problème inverse de la recherche de la position de sources ou de réflecteurs par l'algorithme CINT mis en œuvre avec les traces des ondes acoustiques qui ont traversé l’écoulement<br>The present research is aimed at developing coherent interferometric (CINT) imaging algorithms to localize sources and reflectors in applications involving fluid flows. CINT imaging has been shown to be efficient and statistically stable in quiescent cluttered media where classical imaging techniques, such as Kirchhoff’s migration (KM), may possibly fail due to their lack of statistical robustness. We aim at extending these methods to inhomogeneous moving media, for it has relevance to aero-acoustics, atmospheric and underwater acoustics, infrasound propagation, or even astrophysics. In this thesis report we address both the direct problem of modeling the propagation of acoustic waves in a randomly heterogeneous ambient flow, and the inverse problem of finding the position of sources or reflectors by the CINT algorithm implemented with the traces of the acoustic waves that have travelled through the flow

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2

Newling, Benedict. "Magnetic resonance imaging studies of fluid flow." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627496.

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3

Moore, J. M. "Fluid Flow characterisation using time-lapse electrical imaging." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514275.

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4

Gallup, Benjamin H. (Benjamin Hodsdon) 1982. "High speed imaging of transient non-Newtonian fluid phenomena." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32815.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.<br>Includes bibliographical references (leaf 51).<br>In this thesis, I investigate the utility of high speed imaging for gaining scientific insight into the nature of short-duration transient fluid phenomena, specifically applied to the Kaye effect. The Kaye effect, noted by A. Kaye in the March 9, 1963 issue of Nature, is the deflection and rebound of a free-falling non-Newtonian fluid stream incident on a pool of the same fluid. The effect was successfully reproduced using Suave[TM] shampoo, and imaged using the Phantom[TM] High Speed Video system. This task involved developing a knowledge of the photographic process as applied to high speed imaging, and of non-Newtonian fluid mechanics. No precisely reproducible method for producing rebounding streams was found, and behavior contrary to the existing body of observation were noted. In conclusion, areas that merited further investigation and potential variables of interest to future Kaye effect research are discussed.<br>by Benjamin H. Gallup.<br>S.B.

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5

Belden, Jesse (Jesse Levi). "Synthetic aperture imaging for three dimensional resolution of fluid flows." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67577.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Fluid mechanics and instrumentation have a long history together, as experimental fluids studies play an important role in describing a more complete physical picture in a variety of problems. Presently. state-of-the-art instruments for fluid flows aim to resolve various quantities in three-dimensions. This thesis describes a novel three dimensional imaging system intended to extend laboratory measurement capabilities in complicated flows where knowledge is incomplete. In particular, the imaging system is designed to perform three-dimensional velocimetry in densely seeded flows where object geometry may partially occlude the field as well as to measure and locate bubbles, droplets and particles in three-dimensions in multiphase flows. An instrument of this kind has ramifications in a variety of engineering applications from air-sea interaction to Naval hydrodynamics to turbulence and beyond. The imaging system is based upon synthetic aperture (SA) imaging, which has received much attention in the computer vision community recently. In focus images from an array of synchronized cameras are recombined in software post-capture using a refocusing algorithm to generate a focal stack of synthetic images. Each synthetic image has a narrow depth of field, and objects residing at this depth appear sharp while off-plane objects appear blurred. The refocusing algorithm not only allows for 3D reconstruction of a scene, but also enables "see-through" effects, whereby an object occluded in some of the camera views will be seen in the synthetic images. In this thesis, considerations for development of a three-dimensional measurement system for fluid flows based on the SA imaging field are made. A high-performance three-dimensional particle image velocimetry technique is described and validated. Also, a method for auto-calibration of mutli-camera setups for fluids experiments is derived and developed. Finally, algorithms are generated for application to multiphase flows and the technique is applied to a circular plunging jet with results showing excellent agreement to prior literature and yielding new insight into the problem.<br>by Jesse Belden.<br>Ph.D.

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6

Edie, Margaret Saxby 1976. "Fluid flow in porous media : NMR imaging and numerical simulation." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/58362.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1999.<br>Includes bibliographical references (leaves 17-18).<br>We use nuclear magnetic resonance (NMR) imaging to obtain a three-dimensional image of the pore structure in a limestone core, 4.5 mm in diameter and 10 mm in length, with a resolution of 40 [mu]m. This image is converted into boundary conditions for simulation of fluid flow through the rock using the lattice gas method. The computed permeability is several orders of magnitude lower than the laboratory measured permeability, most likely a result of the image resolution being too coarse to resolve the smaller pore throats, which are believed to be significant for flow in this sample.<br>by Margaret Saxby Edie.<br>S.M.

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7

Hanlon, A. D. "Magnetic resonance imaging of fluid flow in a concentric cylinder rheometer." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603655.

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The shear field created by differential rotation of two concentric cylinders of different diameters has for many years been used as the basis of viscometers, the fluid viscosity being calculated from bulk measurements of the torque on one cylinder and the rate of rotation. Powerful as it is, this type of rheological characterisation is often limited by a lack of knowledge of the precise flow conditions at the fluid boundaries and by flow or thermally induced structural inhomogeneity within the sample. The ability to visualise flow fields within a shearing sample is highly desirable in such cases. This thesis reports the development of a protocol which combines Nuclear Magnetic Resonance (NMR) fluid velocity measurement and data analysis, which allows the velocity profile within the annular gap between two concentrically rotating cylinders to be measured. A temperature controlled, concentric cylinder, Couette flow rheometer, which is compatible with the demands of high spatial resolution (50<I>μ</I>m) Magnetic Resonance Imaging (MRI) is also described. A range of pulsed-field-gradient (PFG) based NMR imaging strategies for rapid velocity measurement have been evaluated and measurements made using each technique validated using a Newtonian fluid (water) undergoing Couette flow. This optimised measurement protocol has been used to study the temperature and shear-rate dependent flow properties of several fluids of relevance to the food industry. The velocity profiles across the fluid-filled gap were measured, the resulting data were then fitted using the power law model, and comparisons made with conventional stress-strain viscometry measurements. Newtonian flow, shear-thinning (pseudoplastic) behaviour, apparent wall slip and Taylor vortices have all been observed. The technique has also been applied in conjunction with NMR relaxometry to the study of time-varying phenomena which result from changes in sample temperature under shear and prolonged shearing at constant temperature. The combination of hardware and optimised NMR acquisition described complements conventional rheometry measurements and provides information which is not available from any other measurement technique.

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8

Yerworth, Rebecca Jane. "Real time imaging of fluid flow in porous and absorbent materials." Thesis, University College London (University of London), 2000. http://discovery.ucl.ac.uk/1421250/.

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9

Gunatilaka, Chamindu C. "Neonatal Airway Analysis Using Magnetic Resonance Imaging and Computational Fluid Dynamics." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623165127485093.

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10

Turk, Jodi. "Wake Induced By Real Seal Whiskers: Particle Imaging Velocimetry Analysis." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1529335121279739.

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11

Biancheri, Catherine L. "Magnetic resonance imaging of flow in simple arterial models." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19273.

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12

Sundareswaran, Kartik Sivaram. "Characterizing single ventricle hemodynamics using phase contrast magnetic resonance imaging." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31748.

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Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Yoganathan, Ajit; Committee Member: Fogel, Mark; Committee Member: Kanter, Kirk; Committee Member: Oshinski, John; Committee Member: Skrinjar, Oskar. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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13

Hornbach, Matthew J. "3D seismic imaging and fluid flow analysis of a gas hydrate province." Laramie, Wyo. : University of Wyoming, 2005. http://proquest.umi.com/pqdweb?did=888847891&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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14

Papaharilaou, Yannis. "Studies of fluid flow in arterial bypass grafts by magnetic resonance imaging." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271254.

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15

Tyszka, J. Michael. "Visualisation of slow and medium speed fluid motion using magnetic resonance imaging." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240122.

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16

Welch, Nathan James. "Imaging and fluid flow measurements of reservoir cap rock and ceramic analogues." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/41985.

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The study of reservoir seal formation characteristics is vital to the success of carbon sequestration projects. The unique properties of these formations allows for the safe long-term storage of carbon dioxide. These intrinsic properties also give rise to numerous experiment complexities outside of the realm of traditional core characterization techniques. Samples were obtained to represent the main classes of cap rocks; shales from both a quarry in the UK and a Spanish carbon storage pilot site, anhydrite from UK extraction mines, and a evaporite sample from a reservoir located in the Middle East. An apparatus has been constructed capable of measuring the permeability and capillary threshold pressure of reservoir cap rocks. The pressure decay technique was used to measure the permeability relationship of clay-rich and evaporite samples with varying applied stresses was measured. Unique trends are observed for each geologic sample exhibiting minimums in permeability. The initial reduction of permeability as effective pressure was increased was due compaction and the subsequent increase at high stresses was due to the opening of micro-fractures. The capillary threshold pressures of each sample were determined using three different techniques. A novel technique takes advantage of the pressure decay permeability measurements technique in quantifying extremely small fluid volumes during initial sample drainage. Capillary threshold pressures were shown to also be dependant on applied system stress. The capillary threshold pressure was observed to decrease dramatically following the increase in permeability with further increasing effective pressure. Imaging capabilities were also explored, ranging from core scale to nanometre scale techniques. Computerized micro-tomography was used in plug sample evaluation, and in the observation of fractured system behaviour under varying stress. Scanning electron microscopy paired with focused ion beam milling was used to extract the 3D pore space of the ceramic allowing for permeability estimates from numerical simulations.

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17

Stickland, Matthew Thomas. "The development of a three dimensional imaging system and its application in fluid mechanics." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249893.

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18

George, Stephanie Marie. "Hemodynamic investigation of the liver using magnetic resonance imaging and computational fluid dynamics." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24803.

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Thesis (Ph.D.)--Biomedical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Giddens, Don; Committee Member: Heffron, Thomas; Committee Member: Martin, Diego; Committee Member: Oshinski, John; Committee Member: Vito, Raymond.

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19

Kakigi, Takahide. "Subcutaneous fluid collection: An imaging marker for treatment response of infectious thoracolumbar spondylodiscitis." Kyoto University, 2016. http://hdl.handle.net/2433/215384.

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20

Poiseau, Eric. "Magnetic resonance imaging of flow using phase velocity encoding : an in vitro study." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/18365.

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21

Hardman, Robert R. "Infrared imaging : a proposed validation technique for computational fluid dynamics codes used in STOVL applications /." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-05022009-040418/.

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22

Pouya, Shahram. "Near-wall velocimetry and investigation of slip flow in microchannels using quantum dot imaging." Diss., Connect to online resource - MSU authorized users, 2008.

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23

Geiger, Robert Vincent. "Fluorescent imaging of intracellular free calcium in vascular endothelial cells subjected to fluid-imposed shear stress." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/33619.

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24

King, Peter Mackenzie. "Fluid movement and motility of the human gastroduodenal region : observations with real-time ultrasonic imaging." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/19015.

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25

Ebbers, Tino. "Cardiovascular fluid dynamics : methods for flow and pressure field analysis from magnetic resonance imaging /." Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/tek690s.pdf.

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26

Jones, Cameron Christopher. "VALIDATION OF COMPUTATIONAL FLUID DYNAMIC SIMULATIONS OF MEMBRANE ARTIFICIAL LUNGS WITH X-RAY IMAGING." UKnowledge, 2012. http://uknowledge.uky.edu/cbme_etds/2.

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The functional performance of membrane oxygenators is directly related to the perfusion dynamics of blood flow through the fiber bundle. Non-uniform flow and design characteristics can limit gas exchange efficiency and influence susceptibility of thrombus development in the fiber membrane. Computational fluid dynamics (CFD) is a powerful tool for predicting properties of the flow field based on prescribed geometrical domains and boundary conditions. Validation of numerical results in membrane oxygenators has been predominantly based on experimental pressure measurements with little emphasis placed on confirmation of the velocity fields due to opacity of the fiber membrane and limitations of optical velocimetric methods. A novel approach was developed using biplane X-ray digital subtraction angiography to visualize flow through a commercial membrane artificial lung at 1–4.5 L/min. Permeability based on the coefficients of the Ergun equation, α and β, were experimentally determined to be 180 and 2.4, respectively, and the equivalent spherical diameter was shown to be approximately equal to the outer fiber diameter. For all flow rates tested, biplane image projections revealed non-uniform radial perfusion through the annular fiber bundle, yet without flow bias due to the axisymmetric position of the outlet. At 1 L/min, approximately 78.2% of the outward velocity component was in the radial (horizontal) plane verses 92.0% at 4.5 L/min. The CFD studies were unable to predict the non-radial component of the outward perfusion. Two-dimensional velocity fields were generated from the radiographs using a cross-correlation tracking algorithm and compared with analogous image planes from the CFD simulations. Velocities in the non-porous regions differed by an average of 11% versus the experimental values, but simulated velocities in the fiber bundle were on average 44% lower than experimental. A corrective factor reduced the average error differences in the porous medium to 6%. Finally, biplane image pairs were reconstructed to show 3-D transient perfusion through the device. The methods developed from this research provide tools for more accurate assessments of fluid flow through membrane oxygenators. By identifying non-invasive techniques to allow direct analysis of numerical and experimental velocity fields, researchers can better evaluate device performance of new prototype designs.

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27

Scharfman, Barry Ethan. "Analysis of multiphase fluid flows via high speed and synthetic aperture three dimensional imaging." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78188.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Spray flows are a difficult problem within the realm of fluid mechanics because of the complicated interfacial physics involved. Complete models of sprays having even the simplest geometries continue to elude researchers and practitioners. From an experimental viewpoint, measurement of dynamic spray characteristics is made difficult by the optically dense nature of many sprays. Flow features like ligaments and droplets break off the bulk liquid volume during the atomization process and often occlude each other in images of sprays. In this thesis, two important types of sprays are analyzed. The first is a round liquid jet in a cross flow of air, which applies, for instance, to fuel injection in jet engines and the aerial spraying of crops. This flow is studied using traditional high-speed imaging in what is known as the bag breakup regime, in which partial bubbles that look like bags are formed along the downstream side of the liquid jet due to the aerodynamic drag exerted on it by the cross flow. Here, a new instability is discovered experimentally involving the presence of multiple bags at the same streamwise position along the jet. The dynamics of bag expansion and upstream column wavelengths are also investigated experimentally and theoretically, with experimental data having found to generally follow the scaling arguments predicted by the theory. The second flow that is studied is the atomization of an unsteady turbulent sheet of water in air, a situation encountered in the formation and breakup of ship bow waves. To better understand these complicated flows, the emerging light field imaging (LFI) and synthetic aperture (SA) refocusing techniques are combined to achieve three-dimensional (3D) reconstruction of the unsteady spray flow fields. A multi-camera array is used to capture the light field and raw images are reparameterized to digitally refocus the flow field post-capture into a volumetric image. These methods allow the camera array to effectively "see through" partial occlusions in the scene. It is demonstrated here that flow features, such as individual droplets and ligaments, can be located in 3D by refocusing throughout the volume and extracting features on each plane.<br>by Barry Ethan Scharfman.<br>S.M.

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28

Hwang, Bohyun. "Fluid Behavior in Nano to Micro Confinement Systems." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593454113844453.

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29

Adair, Kenneth Valloyd. "Diffusive, reactive and orientational dynamics of molecular systems using molecular Fourier imaging correlation spectroscopy /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251854551&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.

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Thesis (Ph. D.)--University of Oregon, 2006.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 103-108). Also available for download via the World Wide Web; free to University of Oregon users.

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30

Tulsiani, Deepti. "A fringe projection system for measurement of condensing fluid films in reduced gravity." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-010406-234259/.

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31

Johnson, Kevin Robert. "In Vivo Coronary Wall Shear Stress Determination Using CT, MRI, and Computational Fluid Dynamics." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14482.

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Wall shear stress (WSS) has long been identified as a factor in the development of atherosclerotic lesions. Autopsy studies have revealed a strong tendency for lesion development at arterial branch sites and along the inner walls of curvature areas that, in theory, should experience low WSS. Calculations of coronary artery WSS have typically been based upon average models of coronary artery geometry with average flow conditions and then compared to average lesion distributions. With all the averaging involved, a more detailed knowledge of the correlation between WSS and atherosclerotic lesion development might be obscured. Recent advancements in hemodynamic modeling now enable the calculation of WSS in individual subjects. An image-based approach for patient-specific calculation of in vivo WSS using computational fluid dynamics (CFD) would allow a more direct study of this correlation. New state-of-the-art technologies in multi-detector computed tomography (CT) and 3.0 Tesla magnetic resonance imaging (MRI) offer potential improvements for the measurement of coronary artery geometry and blood flow. The overall objective of this research was to evaluate the quantitative accuracy of multi-detector CT and 3.0 Tesla MRI and incorporate those imaging modalities into a patient-specific CFD model of coronary artery WSS. Using a series of vessel motion phantoms, it has been shown that 64-detector CT can provide accurate measurements of coronary artery geometry for heart rates below 70 beats per minute. A flow phantom was used to validate the use of navigator-echo gated, phase contrast MRI at 3.0 Tesla to measure velocity of coronary blood flow. Patient-specific, time-resolved CFD models of coronary WSS were created for two subjects. Furthermore, it was determined that population-average velocity curves or steady state velocities can predict locations of high or low WSS with high degrees of accuracy compared to the use of patient-specific blood flow velocity measurements as CFD boundary conditions. This work is significant because it constitutes the first technique to non-invasively calculate in vivo coronary artery WSS using image-based, patient-specific modeling.

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32

Fan, Tai-Hsi. "Fluid mechanics and bio-transport phenomena in imaging of biological membranes using AFM-integrated microelectrode." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04062004-164638/unrestricted/fan%5Ftai-shi%5F200312%5Fphd.pdf.

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33

Yoon, Il. "Two-phase flow dynamics by real-time neutron imaging in oscillating heat pipe." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5694.

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Thesis (M.S.)--University of Missouri-Columbia, 2008.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 19, 2009) Includes bibliographical references.

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34

Saber, Nikoo Rezazadeh. "CFD modelling of blood flow in the human left ventricle based on magnetic resonance imaging data." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390806.

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35

Gariba, Munir Antonio. "Visualisation methods for the analysis of blood flow using magnetic resonance imaging and computational fluid dynamics." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322530.

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36

Virhammar, Johan. "Idiopathic Normal Pressure Hydrocephalus : Cerebrospinal Fluid Tap Test and Magnetic Resonance Imaging as Preoperative Prognostic Investigations." Doctoral thesis, Uppsala universitet, Neurologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-222779.

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Idiopathic normal pressure hydrocephalus (iNPH) is a condition with dilated cerebral ventricles but intracranial pressure within normal limits. The symptoms of gait impairment, cognitive decline and urinary incontinence develop gradually. Treatment with shunt insertion results in improvement in eight out of ten patients. The cerebrospinal fluid tap test (CSF TT) and preoperative magnetic resonance imaging (MRI) are methods used to select patients who may benefit from shunt surgery, but they are performed and interpreted differently in different centers throughout the world. The aim of this thesis was to evaluate the performance of the CSF TT and the underlying mechanisms of improvement in gait function after CSF removal, and to investigate the prognostic value of preoperative MRI scans. Improvement in gait and changes in cerebral blood flow (CBF) after a CSF TT were investigated in two prospective studies that included 39 and 20 patients, respectively. Gait assessment and perfusion MRI were done before and several times during the first 24 hours after a CSF TT. Perfusion was investigated with pseudo-continuous arterial spin labeling. At the group level, gait function was significantly improved at all investigation times, but only one-third of individual CSF TT responders were improved at all investigation times. In patients with increased CBF in lateral and frontal white matter after the CSF TT, gait function improved more than it did in patients with decreased CBF in these regions. However, in the whole sample, there was no significant increase in CBF after CSF removal. Preoperative MRI scans were retrospectively evaluated in 109 patients with iNPH who had undergone shunt surgery. The callosal angle was smaller in shunt responders compared with non-responders. The following findings showed the highest association with a positive outcome after shunting: a small callosal angle, wide temporal horns, and occurrence of disproportionally enlarged subarachnoid space hydrocephalus. In conclusion, CBF in white matter close to the lateral ventricles may play a role in the reversibility of symptoms after CSF removal in patients with iNPH. The CSF TT should be reevaluated if the patient does not initially improve, and preoperative MRI investigations can add prognostic information regarding the selection of shunt candidates.

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Ohlin, Mathias. "Ultrasonic Fluid and Cell Manipulation." Doctoral thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166779.

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During the last decade, ultrasonic manipulation has matured into an important tool with a wide range of applications, from fundamental cell biological research to clinical and industrial implementations. The contactless nature of ultrasound makes it possible to manipulate living cells in a gentle way, e.g., for positioning, sorting, and aggregation. However, when manipulating cells using ultrasound, especially using high acoustic amplitudes, a great deal of heat can be generated. This constitutes a challenge, since the viability of cells is dependent on a stable physiological temperature around 37°C. In this Thesis we present applications of ultrasonic manipulation of fluids, particles, and cells in temperature-controlled micrometer-sized devices fabricated using well established etching techniques, directly compatible with high-resolution fluorescence microscopy. Furthermore, we present ultrasonic manipulation in larger up to centimeter-sized devices optimized for fluid mixing and cell lysis. In the present work, two new ultrasonic manipulation platforms have been developed implementing temperature control. These platforms are much improved with increased performance and usability compared to previous platforms. Also, two new ultrasonic platforms utilizing low-frequency ultrasound for solubilization and cell lysis of microliter-volumed and milliliter-volumed samples have been designed and implemented. We have applied ultrasound to synchronize the interaction between large numbers of immune, natural killer cells, and cancer cells to study the cytotoxic response, on a single cell level. A heterogeneity was found among the natural killer cell population, i.e., some cells displayed high cytotoxic response while others were dormant. Furthermore, we have used temperature-controlled ultrasound to form up to 100, in parallel, solid cancer HepG2 tumors in a glass-silicon multi-well microplate. Next, we investigated the immune cells cytotoxic response against the solid tumors. We found a correlation between the number of immune cells compared to the size of the tumor and the cytotoxic outcome, i.e., if the tumor could be defeated. Finally, the effect of high acoustic pressure amplitudes in the MPa-range on cell viability has been studied in a newly developed platform optimized for long-term stable temperature control, independent on the applied ultrasound power. Lastly, we present two applications of ultrasonic fluid mixing and lysis of cells. One platform is optimized for small microliter-sized volumes in plastic disposable chips and another is optimized for large milliliter-sized volumes in plastic test tubes. The latter platform has been implemented for clinical sputum sample solubilization and cell lysis for genomic DNA extraction for subsequent pathogen detection<br>Ultraljudsmanipulering har under de senaste tio åren mognat och utvecklats till ett verktyg med ett brett användningsområde. Idag kan man finna applikationer inom allt från cellbiologisk grundforskning till industri samt sjukvård. Ultraljudsmanipuleringens kontaktlösa natur gör det till en varsam metod för att manipulera celler, till exempel inom positionering, sortering och aggregering. När ultraljud med hög amplitud används kan värmeutvecklingen, som är oundviklig, bli ett problem. För att kunna säkerställa hög cellviabilitet krävs temperaturkontroll som kan hålla en fysiologisk, stabil temperatur på 37°C. I denna avhandling presenterar vi tillämpningar av temperaturkontrollerad ultraljudsmanipulering i mikrometerstora anordningar fabricerade med väletablerade etsningstekniker. Dessa anordningar är optimerade för att vara fullt kompatibla med högupplöst fluorescensmikroskopi. Vi demonstrerar även ultraljudsmanipulering i centimeterstora anordningar optimerade för omrörning och blandning av vätskor samt lysering av celler. Två nya plattformar för ultraljudsmanipulering med inbyggd temperaturkontroll har utvecklats. Dessa två plattformar erbjuder ökad prestanda, flexibilitet samt även användarvänlighet. Utöver dessa plattformar har ytterligare två anordningar för lågfrekvent ultraljudssolubilisering och cellysering av mikroliter- och milliliterstora prover konstruerats. I denna avhandling har vi tillämpat ultraljud för att synkronisera interaktionen mellan populationer utav immunceller (natural killer-celler) och cancerceller för att på cellnivå studera det cytotoxiska gensvaret. Vi fann en heterogenitet hos immuncellspopulationen. Det manifesterade sig i en fördelning av immuncellerna, från celler med stort cytotoxiskt gensvar till inaktiva immunceller. Vi har dessutom använt temperaturkontrollerad ultrasljudsmanipulering för att skapa solida cancertumörer utav HepG2-cancerceller, upp till 100 stycken parallellt, i en multihåls-mikrotiterplatta bestående av glas och kisel. Med hjälp av dessa tumörer har vi studerat det cytotoxiska gensvaret från immuncellerna. Vi fann att förhållandet mellan antalet immunceller och storleken på tumören bestämde utfallet, det vill säga om tumören kunde bekämpas. Vi presenterar dessutom effekten utav högamplitudsultraljudsexponering av cancerceller i en plattform speciellt designad för höga tryckamplituder med implementerad ultraljudseffektsoberoende temperaturkontroll. Slutligen presenterar vi två tillämpningar av ultraljud för vätskeblandning och cellysering. Den första tillämpningen är anpassad för små volymer i plastchip för engångsbruk och den andra är optimerad för större volymer i plastprovrör. Den senare tillämpningen är speciellt framtagen för ultraljudssolubilisering och cellysering utav kliniska sputumprover för att möjliggöra DNA-extrahering för detektion av smittämnen.<br><p>QC 20150522</p>

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Kitajima, Hiroumi D. "In Vitro Fluid Dynamics of Stereolithographic Single Ventricle Congenital Heart Defects From In Vivo Magnetic Resonance Imaging." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/25074.

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Background: Single ventricle congenital heart defects with cyanotic mixing between systemic and pulmonary circulations afflict 2 per 1000 live births. Following the atriopulmonary connection proposed by Fontan and Baudet in 1971, the present procedure is the total cavopulmonary connection (TCPC), where the superior vena cava (SVC) and inferior vena cava (IVC) are sutured to the left pulmonary artery (LPA) and right pulmonary artery (RPA). However, surgeon preference dictates the implementation of the extra-cardiac and intra-atrial varieties of the TCPC. Overall efficiency and hemodynamic advantage of the competing methodologies have not been determined. Hypothesis: It is hypothesized that an understanding of the experimental fluid dynamic differences between various Fontan surgical methodologies in the TCPC allows for power loss evaluation toward improved surgical planning and design. Methods: Toward such analysis, a previously developed data processing methodology is applied to create an anatomic database of single ventricle patients from in vivo magnetic resonance imaging (MRI) to examine the gamut of TCPC anatomies. From stereolithographic models of representative cases, pressure and flow data are used to quantify control volume power loss to measure overall efficiency. particle image velocimetry (PIV) is employed to detail flow structures in the vasculature. Results are validated with dye injection flow visualization and 3-D phase contrast magnetic resonance imaging (PC-MRI) velocimetry, highlighting flow phenomena that cannot be captured with in vivo MRI due to prohibitively long scanning times. Preliminary results illustrate the variation of control volume power loss over several TCPC anatomies with varying flow conditions, the application of PIV, and validation approaches with 3-D PC-MRI velocimetry. Data from control volume power loss evaluation demonstrate a correlation with TCPC anatomy, providing added clinical knowledge of optimal TCPC design. Findings from PIV and 3-D PC-MRI velocimetry reveal a means for quantitatively comparing flow structure. Dye injection flow visualization offers qualitative insight into limitations of the selected velocimetry techniques.

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Merrifield, Robert David. "Patient specific modelling of left ventricular morphology and flow using magnetic resonance imaging and computational fluid dynamics." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405430.

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Wang, Xiaohua. "Characterization of Mesoscopic Fluid Films for Applications in SPM Imaging and Fabrication of Nanostructures on Responsive Materials." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1068.

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This dissertation focuses on characterization of the mesoscopic fluid film, testing its behavior in different application scenarios, including its role in near-field scanning probe microscopy imaging, contribution to the phononic mechanism in nanotribology phenomena, utilizing it as a natural environment in the study of carbohydrate-protein interactions, and harnessing it as bridge to transport ions in the fabrication of nanostructures on responsive polymer materials. Due to their high resolution and versatile applications in a variety of fields, the family of scanning probe microscopy (SPM) has found widespread acceptance as an analytical and fabrication tool. However, the working mechanism of SPM that allows maintaining the probe-sample distance constant is still controversial. At the heart the problem is a lack of precise knowledge about the nature of the probe-sample interaction. One key factor is the presence of a mesoscopic fluid-like layer that naturally forms at any surface at ambient condition in which most SPMs are operated. Its mesoscopic nature (~20 nm in thickness) results in extraordinary behavior compared to the properties of bulk liquid. For example, the effective shear viscosity of confined mesoscopic fluids is enhanced, and viscoelastic relaxation times are prolonged. Despite the wide use of SPM techniques in ambient air, the basis of their working mechanisms is still not well understood. The probe-sample interaction is monitored using a combination of tuning-fork based shear force microscopy and our recently developed near-field acoustic technique. To characterize the mesoscopic fluid film a series of experiments are performed under different conditions in order to explore the benefits of having extra probing (acoustic) technique in addition to the shear-force approach. The presence of mesoscopic fluid layers as a natural environment enables the detection of protein-carbohydrate interactions. We demonstrated the capability of our shear-force/acoustic technique to monitor the rupture of chemical bonds between carbohydrate and protein pairs. Finally, we present fabrication of nanostructures via electric-field assisted dip-pen nanolithography by exploiting the responsive feature of a particular class of polymers, where the mesoscopic fluid layer also plays an important role in pattern creation.

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Buchenberg, Waltraud [Verfasser], and Jürgen [Akademischer Betreuer] Hennig. "Development of experimental methods to measure temperature fields and velocity fields in fluid flows using Magnetic Resonance Imaging." Freiburg : Universität, 2016. http://d-nb.info/1122831404/34.

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Silva, Pujitha. "Monitoring the fluid flow characteristics of the ovine lumbar disc using magnetic resonance imaging and finite element analysis /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19167.pdf.

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Schmidt, Simon [Verfasser], and Peter [Akademischer Betreuer] Bachert. "On the Quantification of Fluid Mechanical Properties by Means of Magnetic Resonance Imaging / Simon Schmidt ; Betreuer: Peter Bachert." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1211005550/34.

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Fohring, Jennifer. "Adaptive optimal experimental design and inversion of a coupled fluid flow and geophysical imaging model for reservoir monitoring." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58109.

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Imaging and prediction of fluid flow within the subsurface provides information crucial to decision making processes in fields such as groundwater management and enhanced oil recovery. The flow of a fluid through a reservoir depends primarily on the permeability of the subsurface rock; a quantity that is often unknown throughout the entire domain of the reservoir. One method for predicting flow is to estimate the permeability of the reservoir and simulate flow through a mathematical subsurface flow model. Given the model, flow data can be inverted to estimate the permeability. However, this inversion approach can lead to inaccurate results due to the sparse sampling of flow data, and thus inaccurate predictions. To acquire a higher sampling of data, geophysical survey techniques are applied in order to efficiently collect a higher density of data sampled at the surface. These data are sensitive to changes to the geophysical properties of the reservoir due to flow. Inversion of geophysical data then provides images of changes to the geophysical properties of the reservoir. In order to estimate the flow parameters using geophysical data, the two mathematical models require coupling. The thesis therefore proposes two approaches to improve the imaging and prediction of flow. First, a novel coupled inverse problem for estimating the fluid velocity field and the initial geophysical property model from geophysical data is developed. Second, a new method of optimally designing the geophysical survey for the coupled inverse problem is developed. The new adaptive design approach builds on traditional A-Optimal design methods such that historic data are included in the design algorithm. This produces designs that adapt with flow in the subsurface and reduce the collection of unnecessary data. Both the coupled inverse problem and adaptive survey design method are demonstrated using a seismic tomography geophysical survey and a tracer advection fluid flow model. Numerical examples show that the coupled approach yields an improved flow estimate as well as improved image quality, while the adaptive optimal designs provide sufficient geophysical data.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

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KAWAI, HISASHI, KIMINORI BOKURA, SHINJI NAGANAWA, and MASAHIRO YAMAZAKI. "VISUALIZATION OF BRAIN WHITE MATTER TRACTS USING HEAVILY T2-WEIGHTED THREE-DIMENSIONAL FLUID-ATTENUATED INVERSION-RECOVERY MAGNETIC RESONANCE IMAGING." Nagoya University School of Medicine, 2014. http://hdl.handle.net/2237/20547.

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Tulsiani, Deepti. "A Fringe Projection System for Measurement of Condensing Fluid Films in Reduced Gravity." Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/5.

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The thesis describes the design of a fringe projection system to study the dynamics of condensation with potential application in a reduced gravity environment. The concept is that an optical system for imaging the condensation layer enables extraction of valuable data from the image because of the ability of the optical system to image the perturbations in the condensation films. By acquiring a sequence of images of the deformed fringe pattern, the change in the surface topology can be observed over time, giving greater understanding of condensation dynamics in reduced gravity.

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Preusse, Franziska. "High fluid intelligence and analogical reasoning." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2011. http://dx.doi.org/10.18452/16424.

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Hitherto, previous studies on the cerebral correlates of fluid intelligence (fluIQ) used tasks that did not exclusively demand fluIQ, or were restricted to participants of average fluIQ (ave-fluIQ) solving intelligence test items of varying difficulty, thus not allowing assumptions on interindividual differences in fluIQ. Geometric analogical reasoning (GAR) demands fluIQ very purely and thus is an eligible approach for research on interindividual differences in fluIQ. In a first study, we examined the cerebral correlates of GAR, and showed the involvement of parietal and frontal brain regions. This is in line with the assumptions of the parieto-frontal integration theory (P-FIT) of intelligence and with literature reports for other visuo-spatial tasks. Building upon these findings, we report results from a second study with high fluIQ (hi-fluIQ) and ave-fluIQ school students solving a GAR task. Again in line with the P-FIT model, we demonstrated that the parieto-frontal network is involved in GAR in both groups. However, the extent of task-related brain activation in parietal and frontal brain regions was differentially modulated by fluIQ. Our results thus partly run counter to the postulates of the neural efficiency hypothesis, which assumes a negative brain activation-intelligence relationship. We conclude that this relationship is not generally unitary; rather, it can be conjectured that the adaptive and flexible modulation of brain activation is characteristic of hi-fluIQ. Knowledge on the stability of the cerebral correlates of hi-fluIQ during adolescence had been sparse. To elucidate this field, we examined the follow-up stability of the cerebral correlates of GAR in hi-fluIQ in a third study. We demonstrated that the relevant brain network is in place already at age 17 and that improvements in behavioral performance at age 18 due to task familiarity are indicative of more efficient use of the cerebral resources available.<br>Bisherige Studien zu zerebralen Korrelaten fluider Intelligenz (fluIQ) haben Aufgaben verwendet, die fluIQ nicht in Reinform erfordern oder haben Probanden mit durchschnittlicher fluIQ (ave-fluIQ) beim Lösen von Intelligenztestaufgaben mit variierenden Schwierigkeitsstufen untersucht und ermöglichen daher keine Aussagen zu interindividuellen Unterschieden in fluIQ. Geometrisches analoges Schließen (GA) beansprucht fluIQ in Reinform und eignet sich daher als differentielles Untersuchungsparadigma. In einer ersten Studie haben wir die zerebralen Korrelate des GA untersucht und nachgewiesen, dass parietale und frontale Hirnregionen involviert sind. Dies steht im Einklang mit der parieto-frontalen Integrationstheorie (P-FIT) der Intelligenz und mit Literaturberichten zu anderen visuell-räumlichen Aufgaben. Aufbauend auf diesen Befunden berichten wir Ergebnisse einer zweiten Studie, in der Schüler mit hoher fluIQ (hi-fluIQ) und ave-fluIQ GA-Aufgaben lösten. In Übereinstimmung mit den Annahmen des P-FIT-Modells konnten wir zeigen, dass GA in beiden Gruppen das parieto-frontale Netzwerk beansprucht. Das Ausmaß der Hirnaktivierung wurde jedoch differentiell durch fluIQ moduliert. Unsere Ergebnisse widersprechen damit teilweise den Postulaten der neuralen Effizienztheorie, die einen negativen Zusammenhang zwischen Hirnaktivierung und Intelligenz annimmt. Wir schlussfolgern, dass dieser Zusammenhang nicht generell einseitig gerichtet ist, sondern die flexible Modulation von Hirnaktivierung charakteristisch für hi-fluIQ ist. Befunde zur Stabilität zerebraler Korrelate von hi-fluIQ in der Jugend waren bisher rar. Um dieses Feld zu beleuchten, haben wir die follow-up-Stabilität zerebraler Korrelate des GA in der hi-fluIQ Gruppe in einer dritten Studie untersucht. Wir konnten zeigen, dass das relevante zerebrale Netzwerk schon mit 17 Jahren etabliert ist und Performanzverbesserungen über die Zeit für eine effizientere Nutzung der verfügbaren zerebralen Ressourcen sprechen.

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Miiller, Lopes Maria Fernanda 1985. "Simulação tridimensional de uma coluna de bolhas cilíndrica : análise em sistema bifásico por técnica de velocimetria por imagem de partícula (PIV), shadow imaging e simulação." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266720.

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Orientadores: Milton Mori, Marcos Akira D'Ávila<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química<br>Made available in DSpace on 2018-08-20T21:16:08Z (GMT). No. of bitstreams: 1 MiillerLopes_MariaFernanda_M.pdf: 2798310 bytes, checksum: d508c014dbb2db75fd6d052fdf5a76c7 (MD5) Previous issue date: 2012<br>Resumo: Esta pesquisa tem por objetivo avaliar os resultados numéricos por Fluidodinâmica Computacional (CFD) e experimentais pela técnica de Velocimetria por Imagem de Partícula (PIV) e a técnica de Shadow Imaging em uma coluna de bolhas de 1m de altura, 14,5 cm de diâmetro com um distribuidor de gás de 5 furos de 1 mm de diâmetro cada. O sistema estudado foi o sistema bifásico água-ar. O estudo foi realizado no regime homogêneo de operação para as velocidades superficiais de gás de 0,3 cm/s, 0,5 cm/s e 0,7 cm/s. Os experimentos de PIV e shadow imaging foram realizados nas mesmas condições operacionais. Para uma boa representação do escoamento pela técnica de PIV foi necessário o tratamento de 2500 fotos para as velocidades mais baixas e 3500 fotos para a velocidade mais alta. Para a técnica de shadow imaging foi necessário o tratamento de 2000 fotos para a determinação do diâmetro médio das bolhas. Nos testes numéricos foram avaliados dois modelos de arraste, o de Ishii-Zuber (1979) e o de Zhang-Vanderheyden (2002), para a turbulência foi utilizado o modelo k-?, e o diâmetro de bolha utilizado foi o obtido experimentalmente pela técnica de shadow imaging. Perfis de velocidade média axial de líquido obtidos experimentalmente foram comparados com os dados numéricos. Análises dos tensores de Reynolds, energia cinética turbulenta e intensidade turbulenta também foram avaliados. Para a velocidade de 0,3 cm/s e 0,5 cm/s ambos os modelos de arraste representaram bem o escoamento. Para a velocidade de 0,7 cm/s o modelo de arraste de Zhang-Vanderheyden representou melhor o escoamento<br>Abstract: This research aims to evaluate the numerical results from Computational Fluid Dynamics (CFD) simulations and experimental results obtained using Particle Image Velocimetry (PIV) and Shadow Imaging in a bubble column of 1m height, diameter of 14,5cm with a gas distributor with 5 holes of 1 mm diameter each one. The system studied was water-air. The study was performed in homogeneous operation regime for the superficial gas velocity of 0.3 cm/s, 0.5 cm/s and 0.7 cm/s. The PIV and shadow imaging experiments were performed under the same operation conditions. For a good flow representation of PIV data it was necessary to treat 2500 photos to the low superficial gas velocities and 3500 photos to the highest superficial gas velocity. For the shadow imaging technique it was necessary to treat 2000 photos for determining the bubble diameters. In the numerical tests two drag models were evaluated: Ishii-Zuber (1979) and Zhang-Vanderheyden (2002); for turbulence the k-? model was used and the bubble diameter used in the simulations was obtained experimentally by the shadow imaging technique. Average axial velocity profiles of fluid obtained experimentally were compared with numerical results. Analysis of Reynolds tensor, turbulent kinetic energy and turbulent intensity were also evaluated. For superficial gas velocities of 0,3 cm/s and 0,5 cm/s both drag models show good agreement with experimental data. For superficial gas velocities of 0,7 cm/s Zhang-Vanderheyden drag model showed better agreement with experimental data<br>Mestrado<br>Desenvolvimento de Processos Químicos<br>Mestra em Engenharia Química

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Nelson, Edward L. "Temperature, pressure, and infrared image survey of an axisymmetric heated exhaust plume." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-171052/.

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Heidari, Pahlavian Soroush. "Non-Invasive Assessment of Cerebrospinal Fluid and Brain Tissue Biomechanics using MRI and Computational Modeling." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522060187703491.

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