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Sample records for microparticle image velocimetry

  1. Functionalised alginate flow seeding microparticles for use in Particle Image Velocimetry (PIV).

    PubMed

    Varela, Sylvana; Balagué, Isaac; Sancho, Irene; Ertürk, Nihal; Ferrando, Montserrat; Vernet, Anton

    2016-01-01

    Alginate microparticles as flow seeding fulfil all the requirements that are recommended for the velocity measurements in Particle Image Velocimetry (PIV). These spherical microparticles offer the advantage of being environmentally friendly, having excellent seeding properties and they can be produced via a very simple process. In the present study, the performances of alginate microparticles functionalised with a fluorescent dye, Rhodamine B (RhB), for PIV have been studied. The efficacy of fluorescence is appreciated in a number of PIV applications since it can boost the signal-to-noise ratio. Alginate microparticles functionalised with RhB have high emission efficiency, desirable match with fluid density and controlled size. The study of the particles behaviour in strong acid and basic solutions and ammonia is also included. This type of particles can be used for measurements with PIV and Planar Laser Induced Fluorescence (PLIF) simultaneously, including acid-base reactions.

  2. Microparticle image velocimetry approach to flow measurements in isolated contracting lymphatic vessels.

    PubMed

    Margaris, Konstantinos N; Nepiyushchikh, Zhanna; Zawieja, David C; Moore, James; Black, Richard A

    2016-02-01

    We describe the development of an optical flow visualization method for resolving the flow velocity vector field in lymphatic vessels in vitro. The aim is to develop an experimental protocol for accurately estimating flow parameters, such as flow rate and shear stresses, with high spatial and temporal resolution. Previous studies in situ have relied on lymphocytes as tracers, but their low density resulted in a reduced spatial resolution whereas the assumption that the flow was fully developed in order to determine the flow parameters of interest may not be valid, especially in the vicinity of the valves, where the flow is undoubtedly more complex. To overcome these issues, we have applied the time-resolved microparticle image velocimetry (μ -PIV) technique, a well-established method that can provide increased spatial and temporal resolution that this transient flow demands. To that end, we have developed a custom light source, utilizing high-power light-emitting diodes, and associated control and image processing software. This paper reports the performance of the system and the results of a series of preliminary experiments performed on vessels isolated from rat mesenteries, demonstrating, for the first time, the successful application of the μ -PIV technique in these vessels.

  3. Microparticle image velocimetry approach to flow measurements in isolated contracting lymphatic vessels

    NASA Astrophysics Data System (ADS)

    Margaris, Konstantinos N.; Nepiyushchikh, Zhanna; Zawieja, David C.; Moore, James; Black, Richard A.

    2016-02-01

    We describe the development of an optical flow visualization method for resolving the flow velocity vector field in lymphatic vessels in vitro. The aim is to develop an experimental protocol for accurately estimating flow parameters, such as flow rate and shear stresses, with high spatial and temporal resolution. Previous studies in situ have relied on lymphocytes as tracers, but their low density resulted in a reduced spatial resolution whereas the assumption that the flow was fully developed in order to determine the flow parameters of interest may not be valid, especially in the vicinity of the valves, where the flow is undoubtedly more complex. To overcome these issues, we have applied the time-resolved microparticle image velocimetry (μ-PIV) technique, a well-established method that can provide increased spatial and temporal resolution that this transient flow demands. To that end, we have developed a custom light source, utilizing high-power light-emitting diodes, and associated control and image processing software. This paper reports the performance of the system and the results of a series of preliminary experiments performed on vessels isolated from rat mesenteries, demonstrating, for the first time, the successful application of the μ-PIV technique in these vessels.

  4. Flow bioreactor design for quantitative measurements over endothelial cells using micro-particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Leong, Chia Min; Voorhees, Abram; Nackman, Gary B.; Wei, Timothy

    2013-04-01

    Mechanotransduction in endothelial cells (ECs) is a highly complex process through which cells respond to changes in hemodynamic loading by generating biochemical signals involving gene and protein expression. To study the effects of mechanical loading on ECs in a controlled fashion, different in vitro devices have been designed to simulate or replicate various aspects of these physiological phenomena. This paper describes the design, use, and validation of a flow chamber which allows for spatially and temporally resolved micro-particle image velocimetry measurements of endothelial surface topography and stresses over living ECs immersed in pulsatile flow. This flow chamber also allows the study of co-cultures (i.e., ECs and smooth muscle cells) and the effect of different substrates (i.e., coverslip and/or polyethylene terepthalate (PET) membrane) on cellular response. In this report, the results of steady and pulsatile flow on fixed endothelial cells seeded on PET membrane and coverslip, respectively, are presented. Surface topography of ECs is computed from multiple two-dimensional flow measurements. The distributions of shear stress and wall pressure on each individual cell are also determined and the importance of both types of stress in cell remodeling is highlighted.

  5. Silica nanoparticles for micro-particle imaging velocimetry: fluorosurfactant improves nanoparticle stability and brightness of immobilized iridium(III) complexes.

    PubMed

    Lewis, David J; Dore, Valentina; Rogers, Nicola J; Mole, Thomas K; Nash, Gerard B; Angeli, Panagiota; Pikramenou, Zoe

    2013-11-26

    To establish highly luminescent nanoparticles for monitoring fluid flows, we examined the preparation of silica nanoparticles based on immobilization of a cyclometalated iridium(III) complex and an examination of the photophysical studies provided a good insight into the Ir(III) microenvironment in order to reveal the most suitable silica nanoparticles for micro particle imaging velocimetry (μ-PIV) studies. Iridium complexes covalently incorporated at the surface of preformed silica nanoparticles, [Ir-4]@Si500-Z, using a fluorinated polymer during their preparation, demonstrated better stability than those without the polymer, [Ir-4]@Si500, as well as an increase in steady state photoluminescence intensity (and therefore particle brightness) and lifetimes which are increased by 7-fold compared with nanoparticles with the same metal complex attached covalently throughout their core, [Ir-4]⊂Si500. Screening of the nanoparticles in fluid flows using epi-luminescence microscopy also confirm that the brightest, and therefore most suitable particles for microparticle imaging velocimetry (μ-PIV) measurements are those with the Ir(III) complex immobilized at the surface with fluorosurfactant, that is [Ir-4]@Si500-Z. μ-PIV studies demonstrate the suitability of these nanoparticles as nanotracers in microchannels.

  6. An analytic study on the effect of alginate on the velocity profiles of blood in rectangular microchannels using microparticle image velocimetry.

    PubMed

    Pitts, Katie L; Fenech, Marianne

    2013-01-01

    It is desired to understand the effect of alginic acid sodium salt from brown algae (alginate) as a viscosity modifier on the behavior of blood in vitro using a micro-particle image velocimetry (µPIV) system. The effect of alginate on the shape of the velocity profile, the flow rate and the maximum velocity achieved in rectangular microchannels channels are measured. The channels were constructed of polydimethylsiloxane (PDMS), a biocompatible silicone. Porcine blood cells suspended in saline was used as the working fluid at twenty percent hematocrit (H = 20). While alginate was only found to have minimal effect on the maximum velocity and the flow rate achieved, it was found to significantly affect the shear rate at the wall by between eight to a hundred percent.

  7. Three-dimensional two-component velocity measurement of the flow field induced by the Vorticella picta microorganism using a confocal microparticle image velocimetry technique.

    PubMed

    Nagai, Moeto; Oishi, Masamichi; Oshima, Marie; Asai, Hiroshi; Fujita, Hiroyuki

    2009-03-26

    Understanding the biological feeding strategy and characteristics of a microorganism as an actuator requires the detailed and quantitative measurement of flow velocity and flow rate induced by the microorganism. Although some velocimetry methods have been applied to examine the flow, the measured dimensions were limited to at most two-dimensional two-component measurements. Here we have developed a method to measure three-dimensional two-component flow velocity fields generated by the microorganism Vorticella picta using a piezoscanner and a confocal microscope. We obtained the two-component velocities of the flow field in a two-dimensional plane denoted as the XY plane, with an observation area of 455x341 mum(2) and the resolution of 9.09 mum per each velocity vector by a confocal microparticle image velocimetry technique. The measurement of the flow field at each height took 37.5 ms, and it was repeated in 16 planes with a 2.50 mum separation in the Z direction. We reconstructed the three-dimensional two-component flow velocity field. From the reconstructed data, the flow velocity field [u((x,y,z)),v((x,y,z))] in an arbitrary plane can be visualized. The flow rates through YZ and ZX planes were also calculated. During feeding, we examined a suction flow to the mouth of the Vorticella picta and measured it to be to 300 pls.

  8. Three-dimensional two-component velocity measurement of the flow field induced by the Vorticella picta microorganism using a confocal microparticle image velocimetry technique

    PubMed Central

    Nagai, Moeto; Oishi, Masamichi; Oshima, Marie; Asai, Hiroshi; Fujita, Hiroyuki

    2009-01-01

    Understanding the biological feeding strategy and characteristics of a microorganism as an actuator requires the detailed and quantitative measurement of flow velocity and flow rate induced by the microorganism. Although some velocimetry methods have been applied to examine the flow, the measured dimensions were limited to at most two-dimensional two-component measurements. Here we have developed a method to measure three-dimensional two-component flow velocity fields generated by the microorganism Vorticella picta using a piezoscanner and a confocal microscope. We obtained the two-component velocities of the flow field in a two-dimensional plane denoted as the XY plane, with an observation area of 455×341 μm2 and the resolution of 9.09 μm per each velocity vector by a confocal microparticle image velocimetry technique. The measurement of the flow field at each height took 37.5 ms, and it was repeated in 16 planes with a 2.50 μm separation in the Z direction. We reconstructed the three-dimensional two-component flow velocity field. From the reconstructed data, the flow velocity field [u(x,y,z),v(x,y,z)] in an arbitrary plane can be visualized. The flow rates through YZ and ZX planes were also calculated. During feeding, we examined a suction flow to the mouth of the Vorticella picta and measured it to be to 300 pl∕s. PMID:19693398

  9. Stereo Imaging Velocimetry

    NASA Technical Reports Server (NTRS)

    McDowell, Mark (Inventor); Glasgow, Thomas K. (Inventor)

    1999-01-01

    A system and a method for measuring three-dimensional velocities at a plurality of points in a fluid employing at least two cameras positioned approximately perpendicular to one another. The cameras are calibrated to accurately represent image coordinates in world coordinate system. The two-dimensional views of the cameras are recorded for image processing and centroid coordinate determination. Any overlapping particle clusters are decomposed into constituent centroids. The tracer particles are tracked on a two-dimensional basis and then stereo matched to obtain three-dimensional locations of the particles as a function of time so that velocities can be measured therefrom The stereo imaging velocimetry technique of the present invention provides a full-field. quantitative, three-dimensional map of any optically transparent fluid which is seeded with tracer particles.

  10. Echo particle image velocimetry.

    PubMed

    DeMarchi, Nicholas; White, Christopher

    2012-12-27

    The transport of mass, momentum, and energy in fluid flows is ultimately determined by spatiotemporal distributions of the fluid velocity field.(1) Consequently, a prerequisite for understanding, predicting, and controlling fluid flows is the capability to measure the velocity field with adequate spatial and temporal resolution.(2) For velocity measurements in optically opaque fluids or through optically opaque geometries, echo particle image velocimetry (EPIV) is an attractive diagnostic technique to generate "instantaneous" two-dimensional fields of velocity.(3,4,5,6) In this paper, the operating protocol for an EPIV system built by integrating a commercial medical ultrasound machine(7) with a PC running commercial particle image velocimetry (PIV) software(8) is described, and validation measurements in Hagen-Poiseuille (i.e., laminar pipe) flow are reported. For the EPIV measurements, a phased array probe connected to the medical ultrasound machine is used to generate a two-dimensional ultrasound image by pulsing the piezoelectric probe elements at different times. Each probe element transmits an ultrasound pulse into the fluid, and tracer particles in the fluid (either naturally occurring or seeded) reflect ultrasound echoes back to the probe where they are recorded. The amplitude of the reflected ultrasound waves and their time delay relative to transmission are used to create what is known as B-mode (brightness mode) two-dimensional ultrasound images. Specifically, the time delay is used to determine the position of the scatterer in the fluid and the amplitude is used to assign intensity to the scatterer. The time required to obtain a single B-mode image, t, is determined by the time it take to pulse all the elements of the phased array probe. For acquiring multiple B-mode images, the frame rate of the system in frames per second (fps) = 1/δt. (See 9 for a review of ultrasound imaging.) For a typical EPIV experiment, the frame rate is between 20-60 fps

  11. Particle Image Velocimetry Around Swimming Paramecia

    NASA Astrophysics Data System (ADS)

    Giarra, Matthew; Jana, Saikat; Jung, Sunghwan; Vlachos, Pavlos

    2011-11-01

    Microorganisms like paramecia propel themselves by synchronously beating thousands of cilia that cover their bodies. Using micro-particle image velocimetry (μPIV), we quantitatively measured velocity fields created by the movement of Paramecium multimicronucleatum through a thin (~100 μm) film of water. These velocity fields exhibited different features during different swimming maneuvers, which we qualitatively categorized as straight forward, turning, or backward motion. We present the velocity fields measured around organisms during each type of motion, as well as calculated path lines and fields of vorticity. For paramecia swimming along a straight path, we observed dipole-like flow structures that are characteristic of a prolate-spheroid translating axially in a quiescent fluid. Turning and backward-swimming organisms showed qualitatively different patterns of vortices around their bodies. Finally, we offer hypotheses about the roles of these different flow patterns in the organism's ability to maneuver.

  12. Detection of C-reactive protein in evanescent wave field using microparticle-tracking velocimetry.

    PubMed

    Fan, Yu-Jui; Sheen, Horn-Jiunn; Liu, Yi-Hsing; Tsai, Jing-Fa; Wu, Tzu-Heng; Wu, Kuang-Chong; Lin, Shiming

    2010-09-07

    A new technique is developed to measure the nanoparticles' brownian motions by employing microparticle-tracking velocimetry (micro-PTV) in evanescent wave field, which can provide high signal-to-noise ratio images for analyzing nanoparticles' movements. This method enables real-time detection of C-reactive proteins (CRPs) during the rapid interaction between CRPs and anti-CRP-coated nanobeads as CRP concentrations are related to the nanobeads' brownian velocity in the equilibrium state. The smallest observable nanobeads with 185 nm were utilized in this experiment to detect CRP concentrations as low as 0.1 microg/mL even in a high-viscosity solution. Further, the dissociation constant, K(D), can be evaluated based on the experimental results.

  13. Ultrasound Imaging Velocimetry: a review

    NASA Astrophysics Data System (ADS)

    Poelma, Christian

    2017-01-01

    Whole-field velocity measurement techniques based on ultrasound imaging (a.k.a. `ultrasound imaging velocimetry' or `echo-PIV') have received significant attention from the fluid mechanics community in the last decade, in particular because of their ability to obtain velocity fields in flows that elude characterisation by conventional optical methods. In this review, an overview is given of the history, typical components and challenges of these techniques. The basic principles of ultrasound image formation are summarised, as well as various techniques to estimate flow velocities; the emphasis is on correlation-based techniques. Examples are given for a wide range of applications, including in vivo cardiovascular flow measurements, the characterisation of sediment transport and the characterisation of complex non-Newtonian fluids. To conclude, future opportunities are identified. These encompass not just optimisation of the accuracy and dynamic range, but also extension to other application areas.

  14. Engineering imaging: using particle image velocimetry to see physiology in a new light.

    PubMed

    Fouras, Andreas; Dusting, Jonathan; Sheridan, John; Kawahashi, Masaaki; Hirahara, Hiroyuki; Hourigan, Kerry

    2009-02-01

    1. Despite the array of sophisticated imaging techniques available for biological applications, none of the standard biomedical techniques adequately provides the capability to measure motion and flow. Those techniques currently in use are particularly lacking in spatial and temporal resolution. 2. Herein, we introduce the technique of particle image velocimetry. This technique is a well-established tool in engineering research and industry. Particle image velocimetry is continuing to develop and has an increasing number of variants. 3. Three case studies are presented: (i) the use of microparticle image velocimetry to study flow generated by high-frequency oscillatory ventilation in a human airway model; (ii) the use of stereoparticle image velocimetry to study stirred cell and tissue culture devices; and (iii) a three-dimensional X-ray particle image velocimetry technique used to measure flow in an in vitro vascular flow model. 4. The case studies highlight the vast potential of applying the engineering technique of particle image velocimetry and its many variants to current research problems in physiology.

  15. Particle image velocimetry - Status and trends

    SciTech Connect

    Buchhave, P. )

    1992-09-01

    The use of particle image velocimetry (PIV) as a fluid mechanics tool is discussed in comparison with other flow image processing methods and standard laser anemometry. Attention is given to the PIV principle, technical problems associated with PIV, holographic recording, signal processing, and electronic detection. Some alternative signal processing methods, PIV applications, and future research needs are also reviewed. 101 refs.

  16. Differences in magnetically induced motion of diamagnetic, paramagnetic, and superparamagnetic microparticles detected by cell tracking velocimetry.

    PubMed

    Jin, Xiaoxia; Zhao, Yang; Richardson, Aaron; Moore, Lee; Williams, P Stephen; Zborowski, Maciej; Chalmers, Jeffrey J

    2008-12-01

    Magnetic separation in biomedical applications is based on differential magnetophoretic mobility (MM) of microparticulate matter in viscous media. Typically, the difference in MM is obtained by selectively labeling the target cells with superparamagnetic iron oxide nanoparticles (SPIONs). We have measured the MM of monodisperse, polystyrene microspheres (PSMs), with and without attached SPIONs as a model of cell motion induced by nanoparticle magnetization, using variable H field and cell tracking velocimetry (CTV). As a model of paramagnetic microparticle motion, the MM measurements were performed on the same PSMs in paramagnetic gadolinium solutions, and on spores of a prokaryotic organism, Bacillus globigii (shown to contain paramagnetic manganese). The CTV analysis was sensitive to the type of the microparticle magnetization, producing a value of MM independent of the applied H field for the paramagnetic species, and a decreasing MM value with an increasing field for superparamagnetic species, as predicted from theory. The SPION-labeled PSMs exhibited a saturation magnetization above H approximately = 64,000 A m(-1) (or 0.08 tesla). Based on those data, the average saturation magnetizations of the SPIONs was calculated and shown to vary between different commercial sources. The results demonstrate sensitivity of the CTV analysis to different magnetization mechanisms of the microparticles.

  17. Differences in magnetically induced motion of diamagnetic, paramagnetic, and superparamagnetic microparticles detected by Cell Tracking Velocimetry

    PubMed Central

    Jin, Xiaoxia; Zhao, Yang; Richardson, Aaron; Moore, Lee; Williams, P. Stephen; Zborowski, Maciej; Chalmers, Jeffrey J.

    2009-01-01

    Magnetic separation in biomedical applications is based on differential magnetophoretic mobility (MM) of microparticulate matter in viscous media. Typically, the difference in MM is obtained by selectively labeling the target cells with superparamagnetic iron oxide nanoparticles(SPIONs). We have measured the MM of monodisperse, polystyrene microspheres (PSMs), with and without attached SPIONs as a model of cell motion induced by nanoparticle magnetization, using variable H field and Cell Tracking Velocimetry (CTV). As a model of paramagnetic microparticle motion, the MM measurements were performed on the same PSMs in paramagnetic gadolinium solutions, and on spores of a prokaryotic organism, Bacillus globigii (shown to contain paramagnetic manganese). The CTV analysis was sensitive to the type of the microparticle magnetization, producing a value of MM independent of the applied H field for the paramagnetic species, and a decreasing MM value with an increasing field for superparamagnetic species, as predicted from theory. The SPION-labeled PSMs exhibited a saturation magnetization above H ≅ 64,000 A m−1 (or 0.08 tesla). Based on those data, the average saturation magnetizations of the SPIONs was calculated and shown to vary between different commercial sources. The results demonstrate sensitivity of the CTV analysis to different magnetization mechanisms of the microparticles. PMID:19082082

  18. Treatment of interfaces in particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Tsuei, L.; Savaş, Ö.

    2000-12-01

    A first-order accurate method of extending the capability of image velocimetry to interfaces is presented. In this method, the image fields are locally extended across interfaces using fields from the other image of an image pair. During this image parity exchange, the extension of the image fields amounts to locally reversing and reflecting the relative velocity field across the interface. Numerous experimental examples are given to demonstrate and validate the accuracy of the method. These are the plane Couette flow and the laminar pipe flow demonstrating straight rigid boundaries; uniform flow past a sphere and a sphere moving in a stagnant fluid demonstrating curved rigid surfaces; and a free-surface flow and a liquid-liquid interface flow demonstrating compliant interfaces.

  19. Turbulence velocimetry of density fluctuation imaging data

    NASA Astrophysics Data System (ADS)

    McKee, G. R.; Fonck, R. J.; Gupta, D. K.; Schlossberg, D. J.; Shafer, M. W.; Holland, C.; Tynan, G.

    2004-10-01

    Analysis techniques to measure the time-resolved flow field of turbulence are developed and applied to images of density fluctuations obtained with the beam emission spectroscopy diagnostic system on the DIII-D tokamak. Velocimetry applications include measurement of turbulent particle flux, zonal flows, and the Reynolds stress. The flow field of turbulent eddies exhibits quasisteady poloidal flows as well as high-frequency radial and poloidal motion associated with electrostatic potential fluctuations and strongly nonlinear multifield interactions. The orthogonal dynamic programming technique, developed for fluid-based particle and amorphous shape (smoke) flow analysis, is investigated to measure such turbulence flows. Sensitivity and accuracy are assessed and sample results discussed.

  20. Stereo imaging velocimetry for microgravity applications

    NASA Technical Reports Server (NTRS)

    Miller, Brian B.; Meyer, Maryjo B.; Bethea, Mark D.

    1994-01-01

    Stereo imaging velocimetry is the quantitative measurement of three-dimensional flow fields using two sensors recording data from different vantage points. The system described in this paper, under development at NASA Lewis Research Center in Cleveland, Ohio, uses two CCD cameras placed perpendicular to one another, laser disk recorders, an image processing substation, and a 586-based computer to record data at standard NTSC video rates (30 Hertz) and reduce it offline. The flow itself is marked with seed particles, hence the fluid must be transparent. The velocimeter tracks the motion of the particles, and from these we deduce a multipoint (500 or more), quantitative map of the flow. Conceptually, the software portion of the velocimeter can be divided into distinct modules. These modules are: camera calibration, particle finding (image segmentation) and centroid location, particle overlap decomposition, particle tracking, and stereo matching. We discuss our approach to each module, and give our currently achieved speed and accuracy for each where available.

  1. Single port access holographic particle image velocimetry

    SciTech Connect

    Woodruff, S.D.; Richards, G.A.; Cha, D.J.

    1995-07-01

    An optical system, which requires only a single optical window mounted on a test volume, is proposed for holographic particle image velocimetry (HPIV). The optical system is a derivative of the double-exposure, double-reference-beam, off-axis HPIV system, but the innovative idea behind the system is to use back scattered light from the particles as the object wave. A 45{degree} beam splitter inserted in front of the window serves to admit the illuminating beam and extract the back scattered light. This concept can be of great engineering interest because optical access is often limited to one window in practical devices. The preliminary results of the technique appear quite promising, with current studies aimed at defining the optical resolution capabilities.

  2. Uncertainty quantification in volumetric Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sayantan; Charonko, John; Vlachos, Pavlos

    2016-11-01

    Particle Image Velocimetry (PIV) uncertainty quantification is challenging due to coupled sources of elemental uncertainty and complex data reduction procedures in the measurement chain. Recent developments in this field have led to uncertainty estimation methods for planar PIV. However, no framework exists for three-dimensional volumetric PIV. In volumetric PIV the measurement uncertainty is a function of reconstructed three-dimensional particle location that in turn is very sensitive to the accuracy of the calibration mapping function. Furthermore, the iterative correction to the camera mapping function using triangulated particle locations in space (volumetric self-calibration) has its own associated uncertainty due to image noise and ghost particle reconstructions. Here we first quantify the uncertainty in the triangulated particle position which is a function of particle detection and mapping function uncertainty. The location uncertainty is then combined with the three-dimensional cross-correlation uncertainty that is estimated as an extension of the 2D PIV uncertainty framework. Finally the overall measurement uncertainty is quantified using an uncertainty propagation equation. The framework is tested with both simulated and experimental cases. For the simulated cases the variation of estimated uncertainty with the elemental volumetric PIV error sources are also evaluated. The results show reasonable prediction of standard uncertainty with good coverage.

  3. Selected Applications of Planar Imaging Velocimetry in Combustion Test Facilities

    NASA Astrophysics Data System (ADS)

    Willert, Christian; Stockhausen, Guido; Voges, Melanie; Klinner, Joachim; Schodl, Richard; Hassa, Christoph; Schürmans, Bruno; Güthe, Felix

    This chapter provides an overview on the application of particle image velocimetry (PIV) and Doppler global velocimetry (DGV) in combustion test facilities that are operated at pressures of up to 10 bar. Emphasis is placed on the experimental aspects of each application rather than the interpretation of the acquired flow-field data because many of the encountered problems and chosen solution strategies are unique to this area of velocimetry application. In particular, imaging configurations, seeding techniques, data-acquisition strategies as well as pre- and postprocessing methodologies are outlined.

  4. Ultrasound image velocimetry for rheological measurements

    NASA Astrophysics Data System (ADS)

    Gurung, A.; Haverkort, J. W.; Drost, S.; Norder, B.; Westerweel, J.; Poelma, C.

    2016-09-01

    Ultrasound image velocimetry (UIV) allows for the non-intrusive measurement of a wide range of flows without the need for optical transparency. In this study, we used UIV to measure the local velocity field of a model drilling fluid that exhibits yield stress flow behavior. The radial velocity profile was used to determine the yield stress and the Herschel-Bulkley model flow index n and the consistency index k. Reference data were obtained using the conventional offline Couette rheometry. A comparison showed reasonable agreement between the two methods. The discrepancy in model parameters could be attributed to inherent differences between the methods, which cannot be captured by the three-parameter model used. Overall, with a whole flow field measurement technique such as UIV, we were able to quantify the complex rheology of a model drilling fluid. These preliminary results show that UIV can be used as a non-intrusive diagnostic for in situ, real-time measurement of complex opaque flow rheology.

  5. Stereo-particle image velocimetry uncertainty quantification

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sayantan; Charonko, John J.; Vlachos, Pavlos P.

    2017-01-01

    Particle image velocimetry (PIV) measurements are subject to multiple elemental error sources and thus estimating overall measurement uncertainty is challenging. Recent advances have led to a posteriori uncertainty estimation methods for planar two-component PIV. However, no complete methodology exists for uncertainty quantification in stereo PIV. In the current work, a comprehensive framework is presented to quantify the uncertainty stemming from stereo registration error and combine it with the underlying planar velocity uncertainties. The disparity in particle locations of the dewarped images is used to estimate the positional uncertainty of the world coordinate system, which is then propagated to the uncertainty in the calibration mapping function coefficients. Next, the calibration uncertainty is combined with the planar uncertainty fields of the individual cameras through an uncertainty propagation equation and uncertainty estimates are obtained for all three velocity components. The methodology was tested with synthetic stereo PIV data for different light sheet thicknesses, with and without registration error, and also validated with an experimental vortex ring case from 2014 PIV challenge. Thorough sensitivity analysis was performed to assess the relative impact of the various parameters to the overall uncertainty. The results suggest that in absence of any disparity, the stereo PIV uncertainty prediction method is more sensitive to the planar uncertainty estimates than to the angle uncertainty, although the latter is not negligible for non-zero disparity. Overall the presented uncertainty quantification framework showed excellent agreement between the error and uncertainty RMS values for both the synthetic and the experimental data and demonstrated reliable uncertainty prediction coverage. This stereo PIV uncertainty quantification framework provides the first comprehensive treatment on the subject and potentially lays foundations applicable to volumetric

  6. Ultrasound imaging velocimetry of the human vitreous.

    PubMed

    Rossi, Tommaso; Querzoli, Giorgio; Pasqualitto, Giacomo; Iossa, Mario; Placentino, Luca; Repetto, Rodolfo; Stocchino, Alessandro; Ripandelli, Guido

    2012-06-01

    Knowledge of vitreous motion in response to saccades is a prerequisite for understanding vitreous rheology. Purpose of present paper is to introduce Ultrasound Image Velocimetry of the human eye, measure scleral and vitreous velocity fields and test the reproducibility of the proposed technique. Twelve patients with varying diagnosis underwent Ocular Dynamic Ultrasound; scleral angular velocity (V(S)) was measured by 2 different operators and reproducibility calculated. Squared velocity of the vitreous (E), which is representative of kinetic energy per unit mass, was computed from velocity. The time evolution of the energy of the vitreous was described by its spatial average (E(S)), whereas spatial distribution was described by its time average (E(T)). Peak and average E(S), the ratio K(p) of the peak of the spatially averaged kinetic energy per unit mass to the maximum squared scleral angular velocity, vitreous motion onset time (T(O)) and vitreous motion decay time (T(D)) were also defined. Inter-operator reproducibility coefficient was 0.043 and correlation between operators was significant. V(S), peak and average E(S), K(p) ratio and T(D) differed among patients but not among operators. V(S) correlated with E(S) and T(D). E(S) and T(D) but not V(S), were significantly different in patients with Posterior Vitreous Detachment. Patients with retinal detachment showed significantly higher V(S) and E(S). K(p) was inversely correlated to age and refraction. Measures proved accurate and reproducible. E is related to V(S), retinal traction and mechanical stimulation. Identified variables varied with age, refraction pathologic conditions.

  7. Improvement of ultrasound speckle image velocimetry using image enhancement techniques.

    PubMed

    Yeom, Eunseop; Nam, Kweon-Ho; Paeng, Dong-Guk; Lee, Sang Joon

    2014-01-01

    Ultrasound-based techniques have been developed and widely used in noninvasive measurement of blood velocity. Speckle image velocimetry (SIV), which applies a cross-correlation algorithm to consecutive B-mode images of blood flow has often been employed owing to its better spatial resolution compared with conventional Doppler-based measurement techniques. The SIV technique utilizes speckles backscattered from red blood cell (RBC) aggregates as flow tracers. Hence, the intensity and size of such speckles are highly dependent on hemodynamic conditions. The grayscale intensity of speckle images varies along the radial direction of blood vessels because of the shear rate dependence of RBC aggregation. This inhomogeneous distribution of echo speckles decreases the signal-to-noise ratio (SNR) of a cross-correlation analysis and produces spurious results. In the present study, image-enhancement techniques such as contrast-limited adaptive histogram equalization (CLAHE), min/max technique, and subtraction of background image (SB) method were applied to speckle images to achieve a more accurate SIV measurement. A mechanical sector ultrasound scanner was used to obtain ultrasound speckle images from rat blood under steady and pulsatile flows. The effects of the image-enhancement techniques on SIV analysis were evaluated by comparing image intensities, velocities, and cross-correlation maps. The velocity profiles and wall shear rate (WSR) obtained from RBC suspension images were compared with the analytical solution for validation. In addition, the image-enhancement techniques were applied to in vivo measurement of blood flow in human vein. The experimental results of both in vitro and in vivo SIV measurements show that the intensity gradient in heterogeneous speckles has substantial influence on the cross-correlation analysis. The image-enhancement techniques used in this study can minimize errors encountered in ultrasound SIV measurement in which RBCs are used as flow

  8. Stereo Imaging Velocimetry System and Method

    NASA Technical Reports Server (NTRS)

    McDowell, Mark (Inventor)

    2003-01-01

    A system and a method is provided for measuring three dimensional velocities at a plurality of points in a fluid employing at least two cameras positioned approximately perpendicular to one another. Image frames captured by the cameras may be filtered using background subtraction with outlier rejection with spike-removal filtering. The cameras may calibrated to accurately represent image coordinates in a world coordinate system using calibration grids modified using warp transformations. The two-dimensional views of the cameras may be recorded fur image processing and particle track determination. The tracer particles may be tracked on a two-dimensional basis and then stereo matched to obtain three-dimensional locations of the particles as a function of time so that velocities can be measured there from.

  9. Bi-modular flow characterization in tissue engineering scaffolds using computational fluid dynamics and particle imaging velocimetry.

    PubMed

    De Boodt, Sebastian; Truscello, Silvia; Ozcan, Sezin Eren; Leroy, Toon; Van Oosterwyck, Hans; Berckmans, Daniel; Schrooten, Jan

    2010-12-01

    As part of a tissue engineering (TE) therapy, cell-seeded scaffolds can be cultured in perfusion bioreactors in which the flow-mediated wall shear stress and the nutrient transport are factors that influence in vitro proliferation and osteogenic differentiation of the seeded progenitor cells. In this study both computational fluid dynamics simulations on idealized boundary conditions and circumstances and microparticle image velocimetry measurements on realistic conditions were carried out to quantify the fluid dynamic microenvironment inside a bone TE construct. The results showed that differences between actual and designed geometry and time-dependent character of the fluid flow caused a 19% difference in average fluid velocity and a 27% difference in wall shear stress between simulations and measurements. The computational fluid dynamics simulation enabled higher resolution and three-dimensional fluid flow quantification that could be quantitatively compared with a microparticle image velocimetry measurement. The coupling of numerical and experimental analysis provides a reliable and high-resolution bi-modular tool for quantifying the fluid dynamics that represent the basis to determine the relation between the hydrodynamic environment and cell growth and differentiation within TE scaffolds.

  10. Particle Image Velocimetry Applications Using Fluorescent Dye-Doped Particles

    NASA Technical Reports Server (NTRS)

    Petrosky, Brian J.; Maisto, Pietro; Lowe, K. Todd; Andre, Matthieu A.; Bardet, Philippe M.; Tiemsin, Patsy I.; Wohl, Christopher J.; Danehy, Paul M.

    2015-01-01

    Polystyrene latex sphere particles are widely used to seed flows for velocimetry techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). These particles may be doped with fluorescent dyes such that signals spectrally shifted from the incident laser wavelength may be detected via Laser Induced Fluorescence (LIF). An attractive application of the LIF signal is achieving velocimetry in the presence of strong interference from laser scatter, opening up new research possibilities very near solid surfaces or at liquid/gas interfaces. Additionally, LIF signals can be used to tag different fluid streams to study mixing. While fluorescence-based PIV has been performed by many researchers for particles dispersed in water flows, the current work is among the first in applying the technique to micron-scale particles dispersed in a gas. A key requirement for such an application is addressing potential health hazards from fluorescent dyes; successful doping of Kiton Red 620 (KR620) has enabled the use of this relatively safe dye for fluorescence PIV for the first time. In this paper, basic applications proving the concept of PIV using the LIF signal from KR620-doped particles are exhibited for a free jet and a twophase flow apparatus. Results indicate that while the fluorescence PIV techniques are roughly 2 orders of magnitude weaker than Mie scattering, they provide a viable method for obtaining data in flow regions previously inaccessible via standard PIV. These techniques have the potential to also complement Mie scattering signals, for example in multi-stream and/or multi-phase experiments.

  11. Multiplexed Sensing and Imaging with Colloidal Nano- and Microparticles

    NASA Astrophysics Data System (ADS)

    Carregal-Romero, Susana; Caballero-Díaz, Encarnación; Beqa, Lule; Abdelmonem, Abuelmagd M.; Ochs, Markus; Hühn, Dominik; Suau, Bartolome Simonet; Valcarcel, Miguel; Parak, Wolfgang J.

    2013-06-01

    Sensing and imaging with fluorescent, plasmonic, and magnetic colloidal nano- and microparticles have improved during the past decade. In this review, we describe the concepts and applications of how these techniques can be used in the multiplexed mode, that is, sensing of several analytes in parallel or imaging of several labels in parallel.

  12. Brief review of uncertainty quantification for particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Farias, M. H.; Teixeira, R. S.; Koiller, J.; Santos, A. M.

    2016-07-01

    Metrological studies for particle image velocimetry (PIV) are recent in literature. An attempt to evaluate the uncertainty quantifications (UQ) of the PIV velocity field are in evidence. Therefore, a short review on main sources of uncertainty in PIV and available methodologies for its quantification are presented. In addition, the potential of some mathematical techniques, coming from the area of geometric mechanics and control, that could interest the fluids UQ community are highlighted as good possibilities. “We must measure what is measurable and make measurable what cannot be measured” (Galileo)

  13. Three-dimensional illumination system for tomographic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Zhang, Fen; Song, Yang; Qu, Xiangju; Ji, Yunjing; Li, Zhenhua; He, Anzhi

    2016-10-01

    Tomographic particle image velocimetry (Tomo-PIV) is a new developed technique for three-component threedimensional (3C-3D) velocity measurement of the flow field based on the optical tomographic reconstruction method, and has been received extensive attention of the related industries. Three-dimensional light source illuminating the tracer particles of flow field is a critical application for tomographic particle image velocimetry. Three-dimensional light source not only determines the size of measurement volume and the range of the scope of application, but also has a great influence on the image quality. In this work, we propose a rectangular light amplification system using powell lens, prisms and two reflectors. The system can be optimized if given the system parameters based on the theoretical model. The rectangular light amplification system will be verified experimentally by measuring the cross section size of the illuminated light source. A 60mm×25mm cross section of rectangular three-dimensional light source can be obtained by using the rectangular light amplification system. The experiments demonstrate the the feasibility the proposed system.

  14. Analysis of particle kinematics in spheronization via particle image velocimetry.

    PubMed

    Koester, Martin; Thommes, Markus

    2013-02-01

    Spheronization is a wide spread technique in pellet production for many pharmaceutical applications. Pellets produced by spheronization are characterized by a particularly spherical shape and narrow size distribution. The particle kinematic during spheronization is currently not well-understood. Therefore, particle image velocimetry (PIV) was implemented in the spheronization process to visualize the particle movement and to identify flow patterns, in order to explain the influence of various process parameters. The spheronization process of a common formulation was recorded with a high-speed camera, and the images were processed using particle image velocimetry software. A crosscorrelation approach was chosen to determine the particle velocity at the surface of the pellet bulk. Formulation and process parameters were varied systematically, and their influence on the particle velocity was investigated. The particle stream shows a torus-like shape with a twisted rope-like motion. It is remarkable that the overall particle velocity is approximately 10-fold lower than the tip speed of the friction plate. The velocity of the particle stream can be correlated to the water content of the pellets and the load of the spheronizer, while the rotation speed was not relevant. In conclusion, PIV was successfully applied to the spheronization process, and new insights into the particle velocity were obtained.

  15. Photonic Doppler velocimetry lens array probe incorporating stereo imaging

    DOEpatents

    Malone, Robert M.; Kaufman, Morris I.

    2015-09-01

    A probe including a multiple lens array is disclosed to measure velocity distribution of a moving surface along many lines of sight. Laser light, directed to the moving surface is reflected back from the surface and is Doppler shifted, collected into the array, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to the multiple lens array. Numerous fibers in a fiber array project numerous rays to establish many measurement points at numerous different locations. One or more lens groups may be replaced with imaging lenses so a stereo image of the moving surface can be recorded. Imaging a portion of the surface during initial travel can determine whether the surface is breaking up.

  16. Application of optical correlation techniques to particle imaging velocimetry

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Edwards, Robert V.

    1988-01-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of velocity vectors across an extended 2-dimensional region of the flow field. The application of optical correlation techniques to the analysis of multiple exposure laser light sheet photographs can reduce and/or simplify the data reduction time and hardware. Here, Matched Spatial Filters (MSF) are used in a pattern recognition system. Usually MSFs are used to identify the assembly line parts. In this application, the MSFs are used to identify the iso-velocity vector contours in the flow. The patterns to be recognized are the recorded particle images in a pulsed laser light sheet photograph. Measurement of the direction of the partical image displacements between exposures yields the velocity vector. The particle image exposure sequence is designed such that the velocity vector direction is determined unambiguously. A global analysis technique is used in comparison to the more common particle tracking algorithms and Young's fringe analysis technique.

  17. Three-dimensional microscopic light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Truscott, Tadd T.; Belden, Jesse; Ni, Rui; Pendlebury, Jonathon; McEwen, Bryce

    2017-03-01

    A microscopic particle image velocimetry (μ {PIV}) technique is developed based on light field microscopy and is applied to flow through a microchannel containing a backward-facing step. The only hardware difference from a conventional μPIV setup is the placement of a microlens array at the intermediate image plane of the microscope. The method combines this optical hardware alteration with post-capture computation to enable 3D reconstruction of particle fields. From these particle fields, we measure three-component velocity fields, but find that accurate velocity measurements are limited to the two in-plane components at discrete depths through the volume (i.e., 2C-3D). Results are compared with a computational fluid dynamics simulation.

  18. The NASA Subsonic Jet Particle Image Velocimetry (PIV) Dataset

    NASA Technical Reports Server (NTRS)

    Bridges, James; Wernet, Mark P.

    2011-01-01

    Many tasks in fluids engineering require prediction of turbulence of jet flows. The present document documents the single-point statistics of velocity, mean and variance, of cold and hot jet flows. The jet velocities ranged from 0.5 to 1.4 times the ambient speed of sound, and temperatures ranged from unheated to static temperature ratio 2.7. Further, the report assesses the accuracies of the data, e.g., establish uncertainties for the data. This paper covers the following five tasks: (1) Document acquisition and processing procedures used to create the particle image velocimetry (PIV) datasets. (2) Compare PIV data with hotwire and laser Doppler velocimetry (LDV) data published in the open literature. (3) Compare different datasets acquired at the same flow conditions in multiple tests to establish uncertainties. (4) Create a consensus dataset for a range of hot jet flows, including uncertainty bands. (5) Analyze this consensus dataset for self-consistency and compare jet characteristics to those of the open literature. The final objective was fulfilled by using the potential core length and the spread rate of the half-velocity radius to collapse of the mean and turbulent velocity fields over the first 20 jet diameters.

  19. Echo Particle Image Velocimetry Measurements of Liquified Biomass

    NASA Astrophysics Data System (ADS)

    Demarchi, Nicholas; White, Christopher

    2013-11-01

    Echo particle image velocimetry (EPIV) is used to acquire planar fields of velocity in pipe flow of liquefied biomass. The biomass studied is pre-treated (i.e., acid washed) corn stover and it is liquefied by enzymatic hydrolysis. The liquefaction process is carried out for various biomass mass loadings (1.5%-15%). For each biomass loading, the fluid's microstructure and rheology are studied and EPIV measurements are acquired. The aim is to demonstrate the usefulness of EPIV to acquire planar fields of velocity in optically opaque flows and to evaluate the effect of particle size, distribution, and mass loading of the dispersed solid phase on the EPIV measurements. NSF-CBET0846359.

  20. Echo Particle Image Velocimetry in Pipeflow of Liquefied Lignocellulosic Biomass

    NASA Astrophysics Data System (ADS)

    Demarchi, Nicholas; White, Chris

    2014-11-01

    Echo particle image velocimetry (EPIV) is used to acquire planar fields of velocity in pipeflow of liquefied biomass. The biomass used is acid washed corn stover liquefied by enzymatic hydrolysis. The liquefaction process produces a complex multiphase fluid suspension with a microstructure consisting of insoluble solid particles dispersed within a continuous liquid phase. The solid particles are generally heavier than the liquid phase, non-spherical, and distributed over a wide size range. Batches of liquefied biomass are produced at various mass loadings from 1.5% to 20%, from which samples are withdrawn and used to evaluate the rheology, microstructure, and solid particle settling velocities. Next, EPIV measurements are used to evaluate how the suspension rheology, microstructure, and particle sedimentation affects the flow of liquefied biomass under laminar pipeflow conditions.

  1. Echo Particle Image Velocimetry in Pipeflow of Liquefied Lignocellulosic Biomass

    NASA Astrophysics Data System (ADS)

    Demarchi, Nicholas; White, Christopher

    2016-11-01

    Echo particle image velocimetry (EPIV) is used to acquire planar fields of velocity in pipeflow of liquefied biomass. The biomass used is acid washed corn stover, liquefied through enzymatic hydrolysis. The liquefaction process produces a complex multiphase fluid suspension with a microstructure consisting of insoluble solid particles dispersed within a continuous liquid phase. The solid particles are generally heavier than the liquid phase, non-spherical, and distributed over a wide range of aspect ratios and sizes. Batches of liquefied biomass are produced at incremental mass loadings doubling from 1.5% to 12%, samples are withdrawn to evaluate the rheology, microstructure, and solid particle settling velocities. EPIV is used to experimentally determine the mean particle behaviour under laminar and turbulent pressure driven pipeflow conditions. Work presented in this study can be used to design pipeline infrastructure with respect to suspension transport.

  2. Understanding brownout using dual-phase particle image velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Sydney, Anish Joshua

    To better understand the development of brownout dust clouds generated by rotor- craft, the dual-phase flow environment produced by one- and two-bladed laboratory-scale rotors operating over a mobile sediment bed were studied. Three size ranges of characterized glass microspheres were used to represent the sediment particles. Time-resolved flow visualization, particle image velocimetry, and particle tracking velocimetry were used to make the flow measurements. The high imaging rate of these systems allowed the time-history of the rotor wake interactions with the sediment bed to be documented, providing a better understanding of the transient processes and mechanisms that lead to the uplift of sediment and the formation of dust clouds near a rotor in ground effect operation. In particular, the fluid dynamics of the blade tip vortices near the bed were examined in detail, which were shown to have a primary influence on the mobilization of sediment. In general, the near-wall measurements documented at least five fundamental uplift and sediment transport mechanisms below the rotor: 1. Creep, 2. Modified saltation and saltation bombardment, 3. Vortex induced trapping, 4. Reingestion bombardment (local and global), and 5. Secondary suspension. In addition, a further mechanism related to the local unsteady pressure field induced by the convecting wake vortices was hypothesized to contribute to the uplift of sediment. The highest sediment entrainment levels occurred within the wake impingement zone, mainly from the erosion aspects of the tip vortices on the bed. Once entrained, significant quantities of sediment were intermittently trapped in the vortex-induced upwash field. Secondary sediment suspension was found to be more prevalent with the two-bladed rotor because of the propensity for merging of adjacent blade tip vortices and the resulting higher upwash velocities. The trapping of suspended sediment particles into the vortex flow was shown to cause recirculation of

  3. High-speed Particle Image Velocimetry Near Surfaces

    PubMed Central

    Lu, Louise; Sick, Volker

    2013-01-01

    Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (> 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows. A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included. PMID:23851899

  4. A high temperature seeding technique for particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Wernet, Mark P.; Hadley, Judith A.

    2016-12-01

    Non-intrusive measurements of gas velocities via particle image velocimetry (PIV) or laser Doppler velocimetry (LDV) requires entraining particles into the flow field. There are many techniques and materials available for seeding gas phase flows. However, when the flow temperatures exceed 200 °C, the available options for seed materials becomes limited. In high temperature applications refractory seed materials are required. The established technique for seeding flows with metal oxide powders is via fluidized beds by themselves or in combination with cyclone separators. These systems are fraught with problems which limit their ability to provide consistent, uniform flow seeding. In this work, we describe a technique for reliably introducing metal oxide particles into high temperature flows. The employment of pH stabilization techniques typically used to obtain stable dispersions in ceramic processing can provide a source of seed material for high temperature air flows. By pH stabilizing submicron alumina particles in ethanol, a stable dispersion is obtained which when atomized, produces a high quality aerosol. Commercial grade alumina is used with a moderate size distribution. The technique is not limited to alumina/ethanol and is also demonstrated with an alumina/H2O system. Other ceramic powders in other polar solvents can also be used once their point of zero charge (pHpzc) of the powder in the solvent has been determined. We present an example of the pH stabilized dispersions applied to a very challenging high temperature supersonic flow and a particle dynamics analysis across a shock.

  5. Peak-locking reduction for particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Michaelis, Dirk; Neal, Douglas R.; Wieneke, Bernhard

    2016-10-01

    A parametric study of the factors contributing to peak-locking, a known bias error source in particle image velocimetry (PIV), is conducted using synthetic data that are processed with a state-of-the-art PIV algorithm. The investigated parameters include: particle image diameter, image interpolation techniques, the effect of asymmetric versus symmetric window deformation, number of passes and the interrogation window size. Some of these parameters are found to have a profound effect on the magnitude of the peak-locking error. The effects for specific PIV cameras are also studied experimentally using a precision turntable to generate a known rotating velocity field. Image time series recorded using this experiment show a linear range of pixel and sub-pixel shifts ranging from 0 to  ±4 pixels. Deviations in the constant vorticity field (ω z ) reveal how peak-locking can be affected systematically both by varying parameters of the detection system such as the focal distance and f-number, and also by varying the settings of the PIV analysis. A new a priori technique for reducing the bias errors associated with peak-locking in PIV is introduced using an optical diffuser to avoid undersampled particle images during the recording of the raw images. This technique is evaluated against other a priori approaches using experimental data and is shown to perform favorably. Finally, a new a posteriori anti peak-locking filter (APLF) is developed and investigated, which shows promising results for both synthetic data and real measurements for very small particle image sizes.

  6. Instantaneous velocity field measurement of objects in coaxial rotation using digital image velocimetry

    NASA Technical Reports Server (NTRS)

    Cho, Y.-C.; Park, H.

    1990-01-01

    The instantaneous velocity fields of time-dependent flows, or of a collection of objects moving with spatially varying velocities, can be measured by means of digital image velocimetry (DIV). DIV overcomes several shortcomings of such existing techniques as laser-speckle or particle-image velocimetry. Attention is presently given to numerically generated images representing objects in uniform motion which are then used for the experimental validation of DIV.

  7. Particle image velocimetry of a flow at a vaulted wall.

    PubMed

    Kertzscher, U; Berthe, A; Goubergrits, L; Affeld, K

    2008-05-01

    The assessment of flow along a vaulted wall (with two main finite radii of curvature) is of general interest; in biofluid mechanics, it is of special interest. Unlike the geometry of flows in engineering, flow geometry in nature is often determined by vaulted walls. Specifically the flow adjacent to the wall of blood vessels is particularly interesting since this is where either thrombi are formed or atherosclerosis develops. Current measurement methods have problems assessing the flow along vaulted walls. In contrast with conventional particle image velocimetry (PIV), this new method, called wall PIV, allows the investigation of a flow adjacent to transparent flexible surfaces with two finite radii of curvature. Using an optical method which allows the observation of particles up to a predefined depth enables the visualization solely of the boundary layer flow. This is accomplished by adding a specific dye to the fluid which absorbs the monochromatic light used to illuminate the region of observation. The obtained images can be analysed with the methods of conventional PIV and result in a vector field of the velocities along the wall. With wall PIV, the steady flow adjacent to the vaulted wall of a blood pump was investigated and the resulting velocity field as well as the velocity fluctuations were assessed.

  8. Fluorescent image tracking velocimetry of the Nimbus AxiPump.

    PubMed

    Kerrigan, J P; Shaffer, F D; Maher, T R; Dennis, T J; Borovetz, H S; Antaki, J F

    1993-01-01

    High shear rates and extended residence times causing hemolysis and platelet activation can develop in an assist pump or cannula when inferior flow conditions exist. The high volume output of a miniature axial flow pump presents challenges in avoiding these adverse conditions. To assess the hemodynamics within the continuous flow Nimbus Axi-Pump, vector flow fields inside a translucent inflow cannula and a modified 12 mm AxiPump were mapped. Fluorescent image tracking velocimetry was used to track the motion of neutrally buoyant fluorescent particles (30 microns) using pulsed laser light, high resolution video cameras, and computer image analysis. An acrylic pump housing and cannula were integrated into a mock circulatory loop filled with a Newtonian, optically clear blood analog fluid. The flow parameters were controlled to yield known, physiologic loading conditions, including varying degrees of pulsatility. Cannula flow visualization results exhibited critical recirculation patterns at the bend. These results will be used to further optimize the design of the inflow. Particle impact was seen at the pump inlet in the inducer region of the rotor. Very good attachment of flow from the rotor to stator was observed when the pump operated at normal operating speeds. Intermittent regurgitant flow fields were evident in the presence of increased pulsatility and low pump speed. These results have lead to improvements in impeller design and speed control criteria to avoid potential deleterious flows.

  9. Implementation of a Particle Image Velocimetry System for Wind Tunnel Flowfield Measurements

    DTIC Science & Technology

    2014-12-01

    conducted to implement Particle Image Velocimetry (PIV) as a flow measurement technique in the 8’ x 10’ Subsonic Wind Tunnel at Naval Surface Warfare...discussed and summarized. PIV and SPIV were successfully demonstrated in the wind tunnel , and are now available as powerful flowfield measurement tools...for future test programs. 15. SUBJECT TERMS Particle Image Velocimetry, PIV, SPIV, wind tunnel , airwake, SFS2, flow seeding, flow survey 16

  10. Dynamics of liquid slug using particle image velocimetry technique

    NASA Astrophysics Data System (ADS)

    Siddiqui, M. I.; Aziz, A. Rashid A.; Heikal, M. R.

    2016-11-01

    Two phase liquid-gas slug flow is a source of vibration and fatigue on pipe walls and downstream equipment. This paper examines the effect of inlet conditions on the stream-wise velocity profiles and on the shear stresses induced by the liquid phase on the pipe wall during the slug flow. Instantaneous velocity vector fields of the liquid-gas (water-air) slug flow regime were obtained using particle image velocimetry (PIV) technique at various inlet conditions. A 6-m long Plexiglas pipe having an internal diameter 74-mm with a slight inclination of about 1.16° was considered for the visualization of the flow pattern. Test section was employed at a point 3.5m from the inlet, mounted with optical correction box filled with water to minimize the curvature effect of pipe on the PIV snapshots. Stream-wise velocity profiles are obtained at the wake of the liquid slug and the effect of inlet conditions were analyzed. A direct relationship was observed in between superficial gas velocity and the liquid stream-wise velocity at wake section of the slug flow. Further, the lower wall shear stresses were obtained using PIV velocity profiles at liquid film and the slug wake sections in a unit slug. The wall shear stress remained higher in the liquid slugy body as compared to the liquid film. Moreover, an increase in the wall shear stress was observed by increasing the gas superficial velocities.

  11. Particle Image Velocimetry studies of bicuspid aortic valve hemodynamics

    NASA Astrophysics Data System (ADS)

    Saikrishnan, Neelakantan; Yap, Choon-Hwai; Yoganathan, Ajit P.

    2010-11-01

    Bicuspid aortic valves (BAVs) are a congenital anomaly of the aortic valve with two fused leaflets, affecting about 1-2% of the population. BAV patients have much higher incidence of valve calcification & aortic dilatation, which may be related to altered mechanical forces from BAV hemodynamics. This study aims to characterize BAV hemodynamics using Particle Image Velocimetry(PIV). BAV models are constructed from normal explanted porcine aortic valves by suturing two leaflets together. The valves are mounted in an acrylic chamber with two sinuses & tested in a pulsatile flow loop at physiological conditions. 2D PIV is performed to obtain flow fields in three planes downstream of the valve. The stenosed BAV causes an eccentric jet, resulting in a very strong vortex in the normal sinus. The bicuspid sinus vortex appears much weaker, but more unstable. Unsteady oscillatory shear stresses are also observed, which have been associated with adverse biological response; characterization of the hemodynamics of BAVs will provide the first step to understanding these processes better. Results from multiple BAV models of varying levels of stenosis will be presented & higher stenosis corresponded to stronger jets & increased aortic wall shear stresses.

  12. Assessment of pressure field calculations from particle image velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Charonko, John J.; King, Cameron V.; Smith, Barton L.; Vlachos, Pavlos P.

    2010-10-01

    This paper explores the challenges associated with the determination of in-field pressure from DPIV (digital particle image velocimetry)-measured planar velocity fields for time-dependent incompressible flows. Several methods that have been previously explored in the literature are compared, including direct integration of the pressure gradients and solution of different forms of the pressure Poisson equations. Their dependence on grid resolution, sampling rate, velocity measurement error levels and off-axis recording was quantified using artificial data of two ideal sample flow fields—a decaying vortex flow and pulsatile flow between two parallel plates, and real DPIV and pressure data from oscillating flow through a diffuser. The need for special attention to mitigate the velocity error propagation in the pressure estimation is also addressed using a physics-preserving approach based on proper orthogonal decomposition (POD). The results demonstrate that there is no unique or optimum method for estimating the pressure field and the resulting error will depend highly on the type of the flow. However, the virtual boundary, omni-directional pressure integration scheme first proposed by Liu and Katz (2006 Exp. Fluids 41 227-40) performed consistently well in both synthetic and experimental flows. Estimated errors can vary from less than 1% to over 100% with respect to the expected value, though in contrast to more traditional smoothing algorithms, the newly proposed POD-based filtering approach can reduce errors for a given set of conditions by an order of magnitude or more. This analysis offers valuable insight that allows optimizing the choice of methods and parameters based on the flow under consideration.

  13. Digital particle image thermometry/velocimetry: a review

    NASA Astrophysics Data System (ADS)

    Dabiri, Dana

    2009-02-01

    Digital particle image thermometry/velocimetry (DPIT/V) is a relatively new methodology that allows for measurements of simultaneous temperature and velocity within a two-dimensional domain, using thermochromic liquid crystal tracer particles as the temperature and velocity sensors. Extensive research has been carried out over recent years that have allowed the methodology and its implementation to grow and evolve. While there have been several reviews on the topic of liquid crystal thermometry (Moffat in Exp Therm Fluid Sci 3:14-32, 1990; Baughn in Int J Heat Fluid Flow 16:365-375, 1995; Roberts and East in J Spacecr Rockets 33:761-768, 1996; Wozniak et al. in Appl Sci Res 56:145-156, 1996; Behle et al. in Appl Sci Res 56:113-143, 1996; Stasiek in Heat Mass Transf 33:27-39, 1997; Stasiek and Kowalewski in Opto Electron Rev 10:1-10, 2002; Stasiek et al. in Opt Laser Technol 38:243-256, 2006; Smith et al. in Exp Fluids 30:190-201, 2001; Kowalewski et al. in Springer handbook of experimental fluid mechanics, 1st edn. Springer, Berlin, pp 487-561, 2007), the focus of the present review is to provide a relevant discussion of liquid crystals pertinent to DPIT/V. This includes a background on liquid crystals and color theory, a discussion of experimental setup parameters, a description of the methodology’s most recent advances and processing methods affecting temperature measurements, and finally an explanation of its various implementations and applications.

  14. Symmetric Phase-Only Filtering in Particle-Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Wemet, Mark P.

    2008-01-01

    Symmetrical phase-only filtering (SPOF) can be exploited to obtain substantial improvements in the results of data processing in particle-image velocimetry (PIV). In comparison with traditional PIV data processing, SPOF PIV data processing yields narrower and larger amplitude correlation peaks, thereby providing more-accurate velocity estimates. The higher signal-to-noise ratios associated with the higher amplitude correlation peaks afford greater robustness and reliability of processing. SPOF also affords superior performance in the presence of surface flare light and/or background light. SPOF algorithms can readily be incorporated into pre-existing algorithms used to process digitized image data in PIV, without significantly increasing processing times. A summary of PIV and traditional PIV data processing is prerequisite to a meaningful description of SPOF PIV processing. In PIV, a pulsed laser is used to illuminate a substantially planar region of a flowing fluid in which particles are entrained. An electronic camera records digital images of the particles at two instants of time. The components of velocity of the fluid in the illuminated plane can be obtained by determining the displacements of particles between the two illumination pulses. The objective in PIV data processing is to compute the particle displacements from the digital image data. In traditional PIV data processing, to which the present innovation applies, the two images are divided into a grid of subregions and the displacements determined from cross-correlations between the corresponding sub-regions in the first and second images. The cross-correlation process begins with the calculation of the Fourier transforms (or fast Fourier transforms) of the subregion portions of the images. The Fourier transforms from the corresponding subregions are multiplied, and this product is inverse Fourier transformed, yielding the cross-correlation intensity distribution. The average displacement of the

  15. Stereo Imaging Velocimetry Technique Using Standard Off-the-Shelf CCD Cameras

    NASA Technical Reports Server (NTRS)

    McDowell, Mark; Gray, Elizabeth

    2004-01-01

    Stereo imaging velocimetry is a fluid physics technique for measuring three-dimensional (3D) velocities at a plurality of points. This technique provides full-field 3D analysis of any optically clear fluid or gas experiment seeded with tracer particles. Unlike current 3D particle imaging velocimetry systems that rely primarily on laser-based systems, stereo imaging velocimetry uses standard off-the-shelf charge-coupled device (CCD) cameras to provide accurate and reproducible 3D velocity profiles for experiments that require 3D analysis. Using two cameras aligned orthogonally, we present a closed mathematical solution resulting in an accurate 3D approximation of the observation volume. The stereo imaging velocimetry technique is divided into four phases: 3D camera calibration, particle overlap decomposition, particle tracking, and stereo matching. Each phase is explained in detail. In addition to being utilized for space shuttle experiments, stereo imaging velocimetry has been applied to the fields of fluid physics, bioscience, and colloidal microscopy.

  16. Endovascular Device Testing with Particle Image Velocimetry Enhances Undergraduate Biomedical Engineering Education

    ERIC Educational Resources Information Center

    Nair, Priya; Ankeny, Casey J.; Ryan, Justin; Okcay, Murat; Frakes, David H.

    2016-01-01

    We investigated the use of a new system, HemoFlow™, which utilizes state of the art technologies such as particle image velocimetry to test endovascular devices as part of an undergraduate biomedical engineering curriculum. Students deployed an endovascular stent into an anatomical model of a cerebral aneurysm and measured intra-aneurysmal flow…

  17. Study of fish response using particle image velocimetry and high-speed, high-resolution imaging

    SciTech Connect

    Deng, Z.; Richmond, M. C.; Mueller, R. P.; Gruensch, G. R.

    2004-10-01

    Fish swimming has fascinated both engineers and fish biologists for decades. Digital particle image velocimetry (DPIV) and high-speed, high-resolution digital imaging are recently developed analysis tools that can help engineers and biologists better understand how fish respond to turbulent environments. This report details studies to evaluate DPIV. The studies included a review of existing literature on DPIV, preliminary studies to test the feasibility of using DPIV conducted at our Flow Biology Laboratory in Richland, Washington September through December 2003, and applications of high-speed, high-resolution digital imaging with advanced motion analysis to investigations of fish injury mechanisms in turbulent shear flows and bead trajectories in laboratory physical models. Several conclusions were drawn based on these studies, which are summarized as recommendations for proposed research at the end of this report.

  18. Electrospray of multifunctional microparticles for image-guided drug delivery

    NASA Astrophysics Data System (ADS)

    Zhang, Leilei; Yan, Yan; Mena, Joshua; Sun, Jingjing; Letson, Alan; Roberts, Cynthia; Zhou, Chuanqing; Chai, Xinyu; Ren, Qiushi; Xu, Ronald

    2012-03-01

    Anti-VEGF therapies have been widely explored for the management of posterior ocular disease, like neovascular age-related macular degeneration (AMD). Loading anti-VEGF therapies in biodegradable microparticles may enable sustained drug release and improved therapeutic outcome. However, existing microfabrication processes such as double emulsification produce drug-loaded microparticles with low encapsulation rate and poor antibody bioactivity. To overcome these limitations, we fabricate multifunctional microparticles by both single needle and coaxial needle electrospray. The experimental setup for the process includes flat-end syringe needles (both single needle and coaxial needle), high voltage power supplies, and syringe pumps. Microparticles are formed by an electrical field between the needles and the ground electrode. Droplet size and morphology are controlled by multiple process parameters and material properties, such as flow rate and applied voltage. The droplets are collected and freezing dried to obtain multifunctional microparticles. Fluorescent beads encapsulated poly(DL-lactide-co-glycolide) acid (PLGA) microparticles are injected into rabbits eyes through intravitreal injection to test the biodegradable time of microparticles.

  19. Development of a 3D Digital Particle Image Thermometry and Velocimetry (3DDPITV) System

    NASA Astrophysics Data System (ADS)

    Schmitt, David; Rixon, Greg; Dabiri, Dana

    2006-11-01

    A novel 3D Digital Particle Image Thermometry and Velocimetry (3DDPITV) system has been designed and fabricated. By combining 3D Digital Particle Image Velocimetry (3DDPIV) and Digital Particle Image Thermometry (DPIT) into one system, this technique provides simultaneous temperature and velocity data in a volume of ˜1x1x0.5 in^3 using temperature sensitive liquid crystal particles as flow sensors. Two high-intensity xenon flashlamps were used as illumination sources. The imaging system consists of six CCD cameras, three allocated for measuring velocity, based on particle motion, and three for measuring temperature, based on particle color. The cameras were optically aligned using a precision grid and high-resolution translation stages. Temperature calibration was then performed using a precision thermometer and a temperature-controlled bath. Results from proof-of-concept experiments will be presented and discussed.

  20. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

    NASA Astrophysics Data System (ADS)

    Willert, C.; Stasicki, B.; Klinner, J.; Moessner, S.

    2010-07-01

    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage threshold, light pulses can be generated that are sufficient to illuminate and image micron-sized particles in flow velocimetry. Time-resolved PIV measurements in water at a framing rate of 2kHz are presented. The feasibility of LED-based PIV measurements in air is also demonstrated.

  1. Convective flow measurements in a heated cavity using digital imaging velocimetry

    SciTech Connect

    Chavez, H.L.; Hassan, Y. )

    1990-01-01

    During an accident, nuclear systems require devices that maintain long-term cooling of the nuclear fuel. This prevents the disruption of the fuel elements and other vital parts of the reactor that may result in the release of radioactivity. During this exponential decay, the nature of the cooling systems must be examined. This experimental study is primarily the examination of the natural convection flow between rectangular heating elements. Various flow patterns were studied. Convective flow in a liquid-filled heated cavity is investigated using a novel approach, digital imaging pulsed laser velocimetry. This method has several advantages over past methods such as hot wire anemometry and laser Doppler velocimetry. Digital imaging pulsed laser velocimetry is not only a method that supplied qualitative features but also quantitative information. The image is digitized and is manipulated to provide significant data such as centroids, gray levels, and other areas of interest in order to compute the velocity profiles. Each frame holds the equivalent of >1 Mbyte of information. The frame analysis is done with a PC/AT-compatible computer and an image processing unit in the laboratory, and the actual calculation of the flow trajectories is carried out on the VAX 8650 computing system.

  2. Weighted least-squares solver for determining pressure from particle image velocimetry data

    NASA Astrophysics Data System (ADS)

    de Kat, Roeland

    2016-11-01

    Currently, most approaches to determine pressure from particle image velocimetry data are Poisson approaches (e.g.) or multi-pass marching approaches (e.g.). However, these approaches deal with boundary conditions in their specific ways which cannot easily be changed-Poisson approaches enforce boundary conditions strongly, whereas multi-pass marching approaches enforce them weakly. Under certain conditions (depending on the certainty of the data or availability of reference data along the boundary) both types of boundary condition enforcement have to be used together to obtain the best result. In addition, neither of the approaches takes the certainty of the particle image velocimetry data (see e.g.) within the domain into account. Therefore, to address these shortcomings and improve upon current approaches, a new approach is proposed using weighted least-squares. The performance of this new approach is tested on synthetic and experimental particle image velocimetry data. Preliminary results show that a significant improvement can be made in determining pressure fields using the new approach. RdK is supported by a Leverhulme Trust Early Career Fellowship.

  3. Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

    NASA Astrophysics Data System (ADS)

    Falahatpisheh, Ahmad; Kheradvar, Arash

    2015-11-01

    Measurement of 3D flow field inside the cardiac chambers has proven to be a challenging task. Current laser-based 3D PIV methods estimate the third component of the velocity rather than directly measuring it and also cannot be used to image the opaque heart chambers. Modern echocardiography systems are equipped with 3D probes that enable imaging the entire 3D opaque field. However, this feature has not yet been employed for 3D vector characterization of blood flow. For the first time, we introduce a method that generates velocity vector field in 4D based on volumetric echocardiographic images. By assuming the conservation of brightness in 3D, blood speckles are tracked. A hierarchical 3D PIV method is used to account for large particle displacement. The discretized brightness transport equation is solved in a least square sense in interrogation windows of size 163 voxels. We successfully validate the method in analytical and experimental cases. Volumetric echo data of a left ventricle is then processed in the systolic phase. The expected velocity fields were successfully predicted by V-Echo-PIV. In this work, we showed a method to image blood flow in 3D based on volumetric images of human heart using no contrast agent.

  4. Genetic algorithm tracking technique for particle image velocimetry and comparison with other tracking models

    SciTech Connect

    Yoon, C.; Hassan, Y.A.; Ortiz-Villafuerte, J.; Schmidl, W.D.

    1996-12-31

    Particle Image Velocimetry (PIV) is a nonintrusive measurement technique, which can be used to study the structure of various fluid flows. PIV is a very efficient measurement technique since it can obtain both qualitative and quantitative spatial information about the flow field being studied. This information can be further processed into information such as vorticity and pathlines. Other flow measurement techniques (Laser Doppler Velocimetry, Hot Wire Anemometry, etc...) only provide quantitative information at a single point. A study on the performance of the Sub-Grid Genetic Tracking Algorithm for use in Particle Image Velocimetry was performed. A comparison with other tracking routines as the Cross Correlation, Spring Model and Neural Network tracking techniques was conducted. All four algorithms were used to track with synthetic data, and the results are compared with those obtained from a Large Eddy simulation computational fluid dynamics program. The simulated vectors were compared with the results from the four tracking techniques, to determine the yield and reliability of each tracking algorithm.

  5. Analysis of Particle Image Velocimetry (PIV) Data for Application to Subsonic Jet Noise Studies

    NASA Technical Reports Server (NTRS)

    Blackshire, James L.

    1997-01-01

    Global velocimetry measurements were taken using Particle Image Velocimetry (PIV) in the subsonic flow exiting a 1 inch circular nozzle in an attempt to better understand the turbulence characteristics of its shear layer region. This report presents the results of the PIV analysis and data reduction portions of the test and details the processing that was done. Custom data analysis and data validation algorithms were developed and applied to a data ensemble consisting of over 750 PIV 70 mm photographs taken in the 0.85 mach flow facility. Results are presented detailing spatial characteristics of the flow including ensemble mean and standard deviation, turbulence intensities and Reynold's stress levels, and 2-point spatial correlations.

  6. Optical diagnostics for turbulent and multiphase flows: Particle image velocimetry and photorefractive optics

    SciTech Connect

    O`Hern, T.J.; Torczynski, J.R.; Shagam, R.N.; Blanchat, T.K.; Chu, T.Y.; Tassin-Leger, A.L.; Henderson, J.A.

    1997-01-01

    This report summarizes the work performed under the Sandia Laboratory Directed Research and Development (LDRD) project ``Optical Diagnostics for Turbulent and Multiphase Flows.`` Advanced optical diagnostics have been investigated and developed for flow field measurements, including capabilities for measurement in turbulent, multiphase, and heated flows. Particle Image Velocimetry (PIV) includes several techniques for measurement of instantaneous flow field velocities and associated turbulence quantities. Nonlinear photorefractive optical materials have been investigated for the possibility of measuring turbulence quantities (turbulent spectrum) more directly. The two-dimensional PIV techniques developed under this LDRD were shown to work well, and were compared with more traditional laser Doppler velocimetry (LDV). Three-dimensional PIV techniques were developed and tested, but due to several experimental difficulties were not as successful. The photorefractive techniques were tested, and both potential capabilities and possible problem areas were elucidated.

  7. A maximum entropy reconstruction technique for tomographic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Bilsky, A. V.; Lozhkin, V. A.; Markovich, D. M.; Tokarev, M. P.

    2013-04-01

    This paper studies a novel approach for reducing tomographic PIV computational complexity. The proposed approach is an algebraic reconstruction technique, termed MENT (maximum entropy). This technique computes the three-dimensional light intensity distribution several times faster than SMART, using at least ten times less memory. Additionally, the reconstruction quality remains nearly the same as with SMART. This paper presents the theoretical computation performance comparison for MENT, SMART and MART, followed by validation using synthetic particle images. Both the theoretical assessment and validation of synthetic images demonstrate significant computational time reduction. The data processing accuracy of MENT was compared to that of SMART in a slot jet experiment. A comparison of the average velocity profiles shows a high level of agreement between the results obtained with MENT and those obtained with SMART.

  8. Optical correlator method and apparatus for particle image velocimetry processing

    NASA Technical Reports Server (NTRS)

    Farrell, Patrick V. (Inventor)

    1991-01-01

    Young's fringes are produced from a double exposure image of particles in a flowing fluid by passing laser light through the film and projecting the light onto a screen. A video camera receives the image from the screen and controls a spatial light modulator. The spatial modulator has a two dimensional array of cells the transmissiveness of which are controlled in relation to the brightness of the corresponding pixel of the video camera image of the screen. A collimated beam of laser light is passed through the spatial light modulator to produce a diffraction pattern which is focused onto another video camera, with the output of the camera being digitized and provided to a microcomputer. The diffraction pattern formed when the laser light is passed through the spatial light modulator and is focused to a point corresponds to the two dimensional Fourier transform of the Young's fringe pattern projected onto the screen. The data obtained fro This invention was made with U.S. Government support awarded by the Department of the Army (DOD) and NASA grand number(s): DOD #DAAL03-86-K0174 and NASA #NAG3-718. The U.S. Government has certain rights in this invention.

  9. Analysis of microparticle penetration into human and porcine skin: non-invasive imaging with multiphoton excitation microscopy

    NASA Astrophysics Data System (ADS)

    Mulholland, William J.; Kendall, Mark A.; Bellhouse, Brian J.; White, Nick

    2002-06-01

    At the University of Oxford and PowderJect Pharmaceuticals plc, a unique form of needle-free injection technology has been developed. Powdered vaccines and drugs in micro-particle form are accelerated in a high-speed gas flow to sufficient velocity to enter the skin, subsequently achieving a pharmaceutical effect. To optimize the delivery of vaccines and drugs with this method a detailed understanding of the interactive processes that occur between the microparticles and the skin is necessary. Investigations to date of micro-particle delivery into excised human and animal tissue have involved image analyses of histology sections. In the present study, a series of investigations were conducted on excised human and porcine skin using the technique of Multi-Photon fluorescence excitation Microscopy (MPM) to image particles and skin structures post-penetration. Micro-particles of various size and composition were imaged with infrared laser excitation. Three-dimensional images of stratum corneum and epidermal cell deformation due to micro-particle penetration were obtained. Measurements of micro-particle penetration depth taken from z-scan image stacks were used to successfully quantify micro-particle distribution within the skin, without invasively disrupting the skin target. This study has shown that MPM has great potential for the non-invasive imaging of particle skin interactive processes that occur with the transdermal delivery of powdered micro-particle vaccines and drugs.

  10. Neural network method applied to particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Grant, Ian; Pan, X.

    1993-12-01

    The last two decades have seen rapid developments in computing taking as their inspiration the human brain. The human brain functions in a highly parallel and distributed fashion. The adaptive structure of the brain means that learning or training can accompany decision making. This basic neural model has inspired computer hardware exhibiting a parallelism which has revolutionised processing speeds in complex task analysis. Similarly there has been substantial activity in the field of intelligent software and in particular in the area ofneural computing. The human brain may viewed as composed of approximately 1 dbasic units, the neurons. Each neuron exhibits a high degree of interconnectivity with connections to approximately 1 O other neurons. Each neuron accepts many inputs which are added or integrated in some fashion and this causes the neuron to become active or passive. The active neuron emits an output to interconnected neurons. The importance of any one input is controlled by the effectiveness of the corresponding interconnection or weight. One area that has attracted attention in the application of neural networks is pattern recognition. Here the functions of feature classification and extraction are handled by a network which receives some education or training prior to the task of recognition. A priori knowledge of expected outcomes is used as a starting point with the network being allowed to modify or enlarge its knowledge base as the task proceeds. Various models or approaches to adaptive problem solving have been developed. The pattern recognition problem considered in the present paper is the identification of image grouping in double exposure PIV images. The aim is to provide an adaptive net which, following initial training, is able to identify image partners and adapt to changing flow conditions. This latter feature is seen as essential in order that the full potential of the neural net in temporally or spatially changing flow regimes can be

  11. Particle Image Velocimetry Measurements Inside the Human Nasal Passage

    NASA Astrophysics Data System (ADS)

    Kelly, James; Hopkins, Lisa; Sreenivas, K. R.; Wexler, Anthony; Prasad, Ajay

    1998-11-01

    In some applications (such as biological flows) the flow passage exhibits a highly complex geometry. A method is described by which such a flow passage is rendered as a three-dimensional model. A computer model of an adult human nasal cavity was generated from digitized computed tomography (CT) scan images, using the I-DEAS modeling package, and was converted to a stereolithographic file for rapid prototyping. Rapid prototyping yielded a water soluble negative of the airway. Silicone elastomer was poured over the negative, which was washed out after the silicone hardened. This technique can be used to obtain an accurate, transparent, silicone, replicate model of any arbitrary geometry. If the working fluid is refractive-index matched to the silicone, it is possible to obtain PIV measurements in any cross-section. We demonstrate the technique by creating a double-scale model of the human nasal passage, and obtaining PIV measurements.

  12. Dynamical programming based turbulence velocimetry for fast visible imaging of tokamak plasma

    NASA Astrophysics Data System (ADS)

    Banerjee, Santanu; Zushi, H.; Nishino, N.; Mishra, K.; Onchi, T.; Kuzmin, A.; Nagashima, Y.; Hanada, K.; Nakamura, K.; Idei, H.; Hasegawa, M.; Fujisawa, A.

    2015-03-01

    An orthogonal dynamic programming (ODP) based particle image velocimetry (PIV) technique is developed to measure the time resolved flow field of the fluctuating structures at the plasma edge and scrape off layer (SOL) of tokamaks. This non-intrusive technique can provide two dimensional velocity fields at high spatial and temporal resolution from a fast framing image sequence and hence can provide better insights into plasma flow as compared to conventional probe measurements. Applicability of the technique is tested with simulated image pairs. Finally, it is applied to tangential fast visible images of QUEST plasma to estimate the SOL flow in inboard poloidal null-natural divertor configuration. This technique is also applied to investigate the intricate features of the core of the run-away dominated phase following the injection of a large amount of neutrals in the target Ohmic plasma. Development of the ODP-PIV code and its applicability on actual plasma images is reported.

  13. Optical coherence tomography based particle image velocimetry (OCT-PIV) of polymer flows

    NASA Astrophysics Data System (ADS)

    Buchsbaum, A.; Egger, M.; Burzic, I.; Koepplmayr, T.; Aigner, M.; Miethlinger, J.; Leitner, M.

    2015-06-01

    The measurement of spatially resolved velocity distributions is crucial for modelling flow and for understanding properties of materials produced in extrusion processes. Traditional methods for flow visualization such as particle image velocimetry (PIV) rely on optically transparent media and cannot be applied to turbid polymer melts. Here we present optical coherence tomography as an imaging technique for PIV data processing that allows for measuring a sequence of time resolved images even in turbid media. Time-resolved OCT images of a glass-fibre polymer compound were acquired during an extrusion process in a slit die. The images are post-processed by ensemble cross-correlation to calculate spatially resolved velocity vector fields. The results compared well with velocity data obtained by Doppler-OCT. Overall, this new technique (OCT-PIV) represents an important extension of PIV to turbid materials by the use of OCT.

  14. Biodegradable microparticles with surface dimples as a bi-modal imaging contrast agent.

    PubMed

    Kim, Mi Ri; Lim, Yong Taik; Cho, Kuk Young

    2013-03-12

    Fabrication of physically engineered colloids and their application to the biological fields is emerging importance because of their potential to provide an enhanced performance without altering the chemical properties of biomaterials used. A facile approach is reported to fabricate sub-10-μm-sized PLGA microparticle with small dimples covering the surface by droplet imprinting. Optical and magnetic resonance bioimaging agents are easily co-encapsulated inside the microparticles to obtain a bi-modal imaging agent. Cell internalization efficacy of dimpled particles in DC 2.4 cell is enhanced compared with conventional smooth round-shaped colloids. Our result indicates that morphology-controlled microparticles show promise as a cell labeling with improved cell interaction.

  15. Finding the location of the instantaneous center of rotation using a particle image velocimetry algorithm

    NASA Astrophysics Data System (ADS)

    Claessens, Tom

    2017-03-01

    This work is about planar rigid-body kinematics and, in particular, the principle of the instantaneous center of rotation (IC). Using a computer simulated approach, a workflow is presented that results in a visual representation of the locus of the IC, based on particle image velocimetry (PIV). Here, a small number of digital animations of textured objects are created with multibody dynamics software, and later imported in PIV software to extract the velocity field (magnitude and direction) of objects moving within a plane. We believe the workflow presented may help learners improve their understanding of the concept of the IC, thus enhancing their knowledge of rigid body kinematics.

  16. A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow

    PubMed Central

    Sou, In Mei; Layman, Christopher N.; Ray, Chittaranjan

    2013-01-01

    Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. PMID:24347810

  17. Digital holography particle image velocimetry for the measurement of 3D t-3c flows

    NASA Astrophysics Data System (ADS)

    Shen, Gongxin; Wei, Runjie

    2005-10-01

    In this paper a digital in-line holographic recording and reconstruction system was set up and used in the particle image velocimetry for the 3D t-3c (the three-component (3c), velocity vector field measurements in a three-dimensional (3D), space field with time history ( t)) flow measurements that made up of the new full-flow field experimental technique—digital holographic particle image velocimetry (DHPIV). The traditional holographic film was replaced by a CCD chip that records instantaneously the interference fringes directly without the darkroom processing, and the virtual image slices in different positions were reconstructed by computation using Fresnel-Kirchhoff integral method from the digital holographic image. Also a complex field signal filter (analyzing image calculated by its intensity and phase from real and image parts in fast fourier transform (FFT)) was applied in image reconstruction to achieve the thin focus depth of image field that has a strong effect with the vertical velocity component resolution. Using the frame-straddle CCD device techniques, the 3c velocity vector was computed by 3D cross-correlation through space interrogation block matching through the reconstructed image slices with the digital complex field signal filter. Then the 3D-3c-velocity field (about 20 000 vectors), 3D-streamline and 3D-vorticiry fields, and the time evolution movies (30 field/s) for the 3D t-3c flows were displayed by the experimental measurement using this DHPIV method and techniques.

  18. Reconstruction of an acoustic pressure field in a resonance tube by particle image velocimetry.

    PubMed

    Kuzuu, K; Hasegawa, S

    2015-11-01

    A technique for estimating an acoustic field in a resonance tube is suggested. The estimation of an acoustic field in a resonance tube is important for the development of the thermoacoustic engine, and can be conducted employing two sensors to measure pressure. While this measurement technique is known as the two-sensor method, care needs to be taken with the location of pressure sensors when conducting pressure measurements. In the present study, particle image velocimetry (PIV) is employed instead of a pressure measurement by a sensor, and two-dimensional velocity vector images are extracted as sequential data from only a one- time recording made by a video camera of PIV. The spatial velocity amplitude is obtained from those images, and a pressure distribution is calculated from velocity amplitudes at two points by extending the equations derived for the two-sensor method. By means of this method, problems relating to the locations and calibrations of multiple pressure sensors are avoided. Furthermore, to verify the accuracy of the present method, the experiments are conducted employing the conventional two-sensor method and laser Doppler velocimetry (LDV). Then, results by the proposed method are compared with those obtained with the two-sensor method and LDV.

  19. Development of thermal image velocimetry techniques to measure the water surface velocity

    NASA Astrophysics Data System (ADS)

    Saket, A.; Peirson, W. L.; Banner, M. L.; Barthelemy, X.

    2016-05-01

    Particle image velocimetry (PIV) is a state-of-the-art non-intrusive technique for velocity and fluid flow measurements. Due to ongoing improvements in image hardware and processing techniques, the diversity of applications of the PIV method continues to increase. This study presents an accurate thermal image velocimetry (TIV) technique using a CO2 laser source to measure the surface wave particle velocity using infrared imagery. Experiments were carried out in a 2-D wind wave flume with glass side walls for deep-water monochromatic and group waves. It was shown that the TIV technique is robust for both unforced and wind-forced group wave studies. Surface wave particles attain their highest velocity at the group crest maximum and slow down thereafter. As previously observed, each wave crest slows down as it approaches its crest maximum but this study demonstrates that the minimum crest speed coincides with maximum water velocity at the wave crest. Present results indicate that breaking is initiated once the water surface particle velocity at the wave crest exceeds a set proportion of the velocity of the slowing crest as it passes through the maximum of a wave group.

  20. Cell Image Velocimetry (CIV): boosting the automated quantification of cell migration in wound healing assays.

    PubMed

    Milde, Florian; Franco, Davide; Ferrari, Aldo; Kurtcuoglu, Vartan; Poulikakos, Dimos; Koumoutsakos, Petros

    2012-11-01

    Cell migration is commonly quantified by tracking the speed of the cell layer interface in wound healing assays. This quantification is often hampered by low signal to noise ratio, in particular when complex substrates are employed to emulate in vivo cell migration in geometrically complex environments. Moreover, information about the cell motion, readily available inside the migrating cell layers, is not usually harvested. We introduce Cell Image Velocimetry (CIV), a combination of cell layer segmentation and image velocimetry algorithms, to drastically enhance the quantification of cell migration by wound healing assays. The resulting software analyses the speed of the interface as well as the detailed velocity field inside the cell layers in an automated fashion. CIV is shown to be highly robust for images with low signal to noise ratio, low contrast and frame shifting and it is portable across various experimental settings. The modular design and parametrization of CIV is not restricted to wound healing assays and allows for the exploration and quantification of flow phenomena in any optical microscopy dataset. Here, we demonstrate the capabilities of CIV in wound healing assays over topographically engineered surfaces and quantify the relative merits of differently aligned gratings on cell migration.

  1. Study of Fish Response Using Particle Image Velocimetry and High-Speed, High-Resolution Imaging

    SciTech Connect

    Deng, Zhiqun; Richmond, Marshall C.; Guensch, Gregory R.; Mueller, Robert P.

    2004-10-23

    Existing literature of previous particle image velocimetry (PIV) studies of fish swimming has been reviewed. Historically, most of the studies focused on the performance evaluation of freely swimming fish. Technological advances over the last decade, especially the development of digital particle image velocimetry (DPIV) technique, make possible more accurate, quantitative descriptions of the flow patterns adjacent to the fish and in the wake behind the fins and tail, which are imperative to decode the mechanisms of drag reduction and propulsive efficiency. For flows generated by different organisms, the related scales and flow regimes vary significantly. For small Reynolds numbers, viscosity dominates; for very high Reynolds numbers, inertia dominates, and three-dimensional complexity occurs. The majority of previous investigations dealt with the lower end of Reynolds number range. The fish of our interest, such as rainbow trout and spring and fall chinook salmon, fall into the middle range, in which neither viscosity nor inertia is negligible, and three-dimensionality has yet to dominate. Feasibility tests have proven the applicability of PIV to flows around fish. These tests have shown unsteady vortex shedding in the wake, high vorticity region and high stress region, with the highest in the pectoral area. This evident supports the observations by Nietzel et al. (2000) and Deng et al. (2004) that the operculum are most vulnerable to damage from the turbulent shear flow, because they are easily pried open, and the large vorticity and shear stress can lift and tear off scales, rupture or dislodge eyes, and damage gills. In addition, the unsteady behavior of the vortex shedding in the wake implies that injury to fish by the instantaneous flow structures would likely be much higher than the injury level estimated using the average values of the dynamics parameters. Based on existing literature, our technological capability, and relevance and practicability to

  2. Phase contrast x-ray velocimetry of small animal lungs: optimising imaging rates

    PubMed Central

    Murrie, R. P.; Paganin, D. M.; Fouras, A.; Morgan, K. S.

    2015-01-01

    Chronic lung diseases affect a vast portion of the world’s population. One of the key difficulties in accurately diagnosing and treating chronic lung disease is our inability to measure dynamic motion of the lungs in vivo. Phase contrast x-ray imaging (PCXI) allows us to image the lungs in high resolution by exploiting the difference in refractive indices between tissue and air. Combining PCXI with x-ray velocimetry (XV) allows us to track the local motion of the lungs, improving our ability to locate small regions of disease under natural ventilation conditions. Via simulation, we investigate the optimal imaging speed and sequence to capture lung motion in vivo in small animals using XV on both synchrotron and laboratory x-ray sources, balancing the noise inherent in a short exposure with motion blur that results from a long exposure. PMID:26819819

  3. Effects of humic acid on physical and hydrodynamic properties of kaolin flocs by particle image velocimetry.

    PubMed

    Zhong, Runsheng; Zhang, Xihui; Xiao, Feng; Li, Xiaoyan; Cai, Zhonghua

    2011-07-01

    The physical and hydrodynamic properties of kaolin flocs including floc size, strength, regrowth, fractal structure and settling velocity were investigated by in situ particle image velocimetry technique at different humic acid concentration. Jar-test experimental results showed that the adsorbed humic acid had a significant influence on the coagulation process for alum and ferric chloride. Kaolin flocs formed with the ferric chloride were larger and stronger than those for alum at same humic acid concentration. Floc strength and regrowth were estimated by strength factor and recovery factor at different humic acid concentration. It was found that the increased humic acid concentration had a slight influence on the strength of kaolin flocs and resulted in much worse floc regrowth. In addition, the floc regrowth after breakage depended on the shear history and coagulants under investigation. The changes in fractal structure recorded continuously by in situ particle image velocimetry technique during the growth-breakage-regrowth processes provided a supporting information that the kaolin flocs exhibited a multilevel structure. It was proved that the increased humic acid concentration resulted in decrease in mass fractal dimension of kaolin flocs and consequently worse sedimentation performance through free-settling and microbalance techniques.

  4. Measurement and Image Processing Techniques for Particle Image Velocimetry Using Solid-Phase Carbon Dioxide

    DTIC Science & Technology

    2014-03-27

    doppler anemometry LED Light-emitting diode MgO Magnesium Oxide Nd:YAG Neodymium -doped yttrium aluminum garnet PSV Particle shadow velocimetry PTV Particle...density” ideal for PIV, and c) “high density” suitable for LSV [2] neodymium -doped yttrium aluminum garnet (Nd:YAG) laser that emits visible green light

  5. The application of digital particle image velocimetry (DPIV) to transonic flows

    NASA Astrophysics Data System (ADS)

    Bryanston-Cross, P. J.; Judge, T. R.; Quan, C.; Pugh, G.; Corby, N.

    The paper is an extension to earlier PIV work published in Progress in Aerospace Science Vol. 27, pp237-265. 1990. DPIV (Digital Particle Image Velocimetry) measurements have been made at transonic speeds using a new method of both digitally capturing and visualising high speed flow-fields. It has provided a quantitative whole field image of the transonic flow. The area of interest for this test was of the wing/pylon/nacelle/inboard gully region of a 5.7% scale model wing and engine combination. The measurements show velocity and flow angle changes in this region, to a measurement accuracy of 4%, made at an optical stand off distance of 0.5 m.

  6. Methodology for the Elimination of Reflection and System Vibration Effects in Particle Image Velocimetry Data Processing

    NASA Technical Reports Server (NTRS)

    Bremmer, David M.; Hutcheson, Florence V.; Stead, Daniel J.

    2005-01-01

    A methodology to eliminate model reflection and system vibration effects from post processed particle image velocimetry data is presented. Reflection and vibration lead to loss of data, and biased velocity calculations in PIV processing. A series of algorithms were developed to alleviate these problems. Reflections emanating from the model surface caused by the laser light sheet are removed from the PIV images by subtracting an image in which only the reflections are visible from all of the images within a data acquisition set. The result is a set of PIV images where only the seeded particles are apparent. Fiduciary marks painted on the surface of the test model were used as reference points in the images. By locating the centroids of these marks it was possible to shift all of the images to a common reference frame. This image alignment procedure as well as the subtraction of model reflection are performed in a first algorithm. Once the images have been shifted, they are compared with a background image that was recorded under no flow conditions. The second and third algorithms find the coordinates of fiduciary marks in the acquisition set images and the background image and calculate the displacement between these images. The final algorithm shifts all of the images so that fiduciary mark centroids lie in the same location as the background image centroids. This methodology effectively eliminated the effects of vibration so that unbiased data could be used for PIV processing. The PIV data used for this work was generated at the NASA Langley Research Center Quiet Flow Facility. The experiment entailed flow visualization near the flap side edge region of an airfoil model. Commercial PIV software was used for data acquisition and processing. In this paper, the experiment and the PIV acquisition of the data are described. The methodology used to develop the algorithms for reflection and system vibration removal is stated, and the implementation, testing and

  7. Advantages in using multi-frequency driving ultrasound for optimizing echo particle image velocimetry techniques.

    PubMed

    Zheng, Hairong; Mukdadi, Osama; Hertzberg, Jean; Shandas, Robin

    2004-01-01

    We have recently developed an ultrasound based velocimetry technique, termed echo particle image velocimetry (echo PIV). This method takes advantage of the non-linear backscatter characteristics of ultrasound contrast microbubbles when exposed to certain ultrasonic field. Preliminary in vitro, animal and clinical studies have shown significant promise of this method for measuring multiple velocity components with good temporal and spatial resolution. However, there is still difficulty in maximizing the non-linearity of bubble backscatter using conventional Gaussian-pulse excitation techniques because significant harmonic components may not be produced at modest pressure amplitudes and the higher incident pressure amplitudes required to induce non-linear behavior may cause bubble destruction. We present here a potential solution to this problem through the use of multi-frequency excitation. A rectangular pulse with multiple harmonics is used to drive the bubble. The backscatter process is studied through a modified Rayleigh-Plesset equation. Results show that the rectangular wave is effective in improving the visibility of microbubbles with ultrasound backscattered efficiency significantly higher than the widely used Gaussian waveform. Use of rectangular pulses with 4 and 2 harmonics showed no significant difference in bubble backscatter behavior, indicating that a two-frequency excitation may be sufficient to induce non-linear behavior of the microbubbles practically at modest incident pressures.

  8. A comprehensive statistical investigation of schlieren image velocimetry (SIV) using high-velocity helium jet

    NASA Astrophysics Data System (ADS)

    Biswas, Sayan; Qiao, Li

    2017-03-01

    A detailed statistical assessment of seedless velocity measurement using Schlieren Image Velocimetry (SIV) was explored using open source Robust Phase Correlation (RPC) algorithm. A well-known flow field, an axisymmetric turbulent helium jet, was analyzed near and intermediate region (0≤ x/d≤ 20) for two different Reynolds numbers, Re d = 11,000 and Re d = 22,000 using schlieren with horizontal knife-edge, schlieren with vertical knife-edge and shadowgraph technique, and the resulted velocity fields from SIV techniques were compared to traditional Particle Image Velocimetry (PIV) measurements. A novel, inexpensive, easy to setup two-camera SIV technique had been demonstrated to measure high-velocity turbulent jet, with jet exit velocities 304 m/s (Mach = 0.3) and 611 m/s (Mach = 0.6), respectively. Several image restoration and enhancement techniques were tested to improve signal to noise ratio (SNR) in schlieren and shadowgraph images. Processing and post-processing parameters for SIV techniques were examined in detail. A quantitative comparison between self-seeded SIV techniques and traditional PIV had been made using correlation statistics. While the resulted flow field from schlieren with horizontal knife-edge and shadowgraph showed excellent agreement with PIV measurements, schlieren with vertical knife-edge performed poorly. The performance of spatial cross-correlations at different jet locations using SIV techniques and PIV was evaluated. Turbulence quantities like turbulence intensity, mean velocity fields, Reynolds shear stress influenced spatial correlations and correlation plane SNR heavily. Several performance metrics such as primary peak ratio (PPR), peak to correlation energy (PCE), the probability distribution of signal and noise were used to compare capability and potential of different SIV techniques.

  9. Particle Image Velocimetry Measurements and Analysis of Bypass Data for a Scaled 6mm Gap

    SciTech Connect

    J.R. Wolf; T.E. Conder; R.R. Schultz

    2012-09-01

    The purpose of the fluid dynamics experiments in the MIR (Matched Index of-Refraction) flow system at Idaho National Laboratory (INL) is to develop benchmark databases for the assessment of Computational Fluid Dynamics (CFD) solutions of the momentum equations, scalar mixing, and turbulence models for the flow ratios between coolant channels and bypass gaps in the interstitial regions of typical prismatic standard fuel element (SFE) or upper reflector block geometries of typical Modular High-temperature Gas-cooled Reactors (MHTGR) in the limiting case of negligible buoyancy and constant fluid properties. The experiments will use optical techniques, primarily particle image velocimetry (PIV) in the INL Matched Index of Refraction (MIR) flow system.

  10. Instantaneous, phase-averaged, and time-averaged pressure from particle image velocimetry

    NASA Astrophysics Data System (ADS)

    de Kat, Roeland

    2015-11-01

    Recent work on pressure determination using velocity data from particle image velocimetry (PIV) resulted in approaches that allow for instantaneous and volumetric pressure determination. However, applying these approaches is not always feasible (e.g. due to resolution, access, or other constraints) or desired. In those cases pressure determination approaches using phase-averaged or time-averaged velocity provide an alternative. To assess the performance of these different pressure determination approaches against one another, they are applied to a single data set and their results are compared with each other and with surface pressure measurements. For this assessment, the data set of a flow around a square cylinder (de Kat & van Oudheusden, 2012, Exp. Fluids 52:1089-1106) is used. RdK is supported by a Leverhulme Trust Early Career Fellowship.

  11. General-Purpose Stereo Imaging Velocimetry Technique Developed for Space and Industrial Applications

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2004-01-01

    A new three-dimensional, full-field analysis technique has been developed for industrial and space applications. Stereo Imaging Velocimetry (SIV) will provide full-field analysis for three-dimensional flow data from any optically transparent fluid that can be seeded with tracer particles. The goal of SIV is to provide a means to measure three-dimensional fluid velocities quantitatively and qualitatively at many points. SIV is applicable to any optically transparent fluid experiment. Except for the tracer particles, this measurement technique is nonintrusive. Velocity accuracies are on the order of 95 to 99 percent of fullfield. The system components of SIV include camera calibration, centroid determination, overlap decomposition, particle tracking, stereo matching, and three-dimensional velocity analysis. SIV has been used successfully for space shuttle experiments as well as for fluid flow applications for business and industry.

  12. Two-phase velocity measurements around cylinders using particle image velocimetry

    SciTech Connect

    Hassan, Y.A.; Philip, O.G.; Schmidl, W.D.

    1995-09-01

    The particle Image Velocimetry flow measurement technique was used to study both single-phase flow and two-phase flow across a cylindrical rod inserted in a channel. First, a flow consisting of only a single-phase fluid was studied. The experiment consisted of running a laminar flow over four rods inserted in a channel. The water flow rate was 126 cm{sup 3}/s. Then a two-phase flow was studied. A mixture of water and small air bubbles was used. The water flow rate was 378 cm{sup 3}/s and the air flow rate was approximately 30 cm{sup 3}/s. The data are analyzed to obtain the velocity fields for both experiments. After interpretation of the velocity data, forces acting on a bubble entrained by the vortex were calculated successfully. The lift and drag coefficients were calculated using the velocity measurements and the force data.

  13. Velocity Field Measurements of Human Coughing Using Time Resolved Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Khan, T.; Marr, D. R.; Higuchi, H.; Glauser, M. N.

    2003-11-01

    Quantitative fluid mechanics analysis of human coughing has been carried out using new Time Resolved Particle Image Velocimetry (TRPIV). The study involves measurement of velocity vector time-histories and velocity profiles. It is focused on the average normal human coughing. Some work in the past on cough mechanics has involved measurement of flow rates, tidal volumes and sub-glottis pressure. However, data of unsteady velocity vector field of the exiting highly time-dependent jets is not available. In this study, human cough waveform data are first acquired in vivo using conventional respiratory instrumentation for various volunteers of different gender/age groups. The representative waveform is then reproduced with a coughing/breathing simulator (with or without a manikin) for TRPIV measurements and analysis. The results of this study would be useful not only for designing of indoor air quality and heating, ventilation and air conditioning systems, but also for devising means of protection against infectious diseases.

  14. Digital particle image velocimetry/thermometry and application to the wake of a heated circular cylinder

    NASA Astrophysics Data System (ADS)

    Park, H. G.; Dabiri, D.; Gharib, M.

    Digital particle image velocimetry/thermometry (DPIV/T) is a technique whereby the velocity and temperature fields are obtained using thermochromic liquid crystal (TLC) seeding particles in water. In this paper, the uncertainty levels associated with temperature and velocity measurements using DPIV/T are studied. The study shows that large uncertainties are encountered when the temperature is measured from individual TLC particles. Therefore, an averaging procedure is presented which can reduce the temperature uncertainties. The uncertainty is reduced by computing the average temperature of the particles within the common specified sampling window used for standard DPIV. Using this procedure, the velocity and temperature distributions of an unsteady wake behind a heated circular cylinder are measured experimentally at Re=610. The instantaneous DPIV/T measurements are shown to be useful for computing statistical flow quantities, such as mean and velocity-temperature correlations.

  15. Suspension Dynamics of Liquefied Lignocellulosic Biomass in Pipeflow using Echo Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Demarchi, Nicholas; White, Christopher

    2015-11-01

    Echo particle image velocimetry (EPIV) is used to acquire planar fields of velocity in pipeflow of liquefied biomass. The biomass used is acid washed corn stover liquefied by enzymatic hydrolysis. The liquefaction process produces a complex multiphase fluid suspension with a microstructure consisting of insoluble solid particles dispersed within a continuous liquid phase. The solid particles are generally heavier than the liquid phase, non-spherical, and distributed over a wide range of aspect ratios and sizes. Batches of liquefied biomass are produced at incremental mass loadings doubling from 1.5% to 12%. The rheology, microstructure, and solid particle settling velocities of the liquefied biomass as a function of mass loading is first quantified. Next, EPIV is used to measure and quantify the flow dynamics of liquefied biomass suspensions under laminar pressure driven pipeflow conditions. Finally, Information gathered from the experimental data is used to simulate particle settling rates and predict the particle physics under the same pipeflow conditions.?

  16. The complex aerodynamic footprint of desert locusts revealed by large-volume tomographic particle image velocimetry.

    PubMed

    Henningsson, Per; Michaelis, Dirk; Nakata, Toshiyuki; Schanz, Daniel; Geisler, Reinhard; Schröder, Andreas; Bomphrey, Richard J

    2015-07-06

    Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal's entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin-Helmholtz instability in the shear layer behind the flapping wings.

  17. Flowfield characterization of a piloted lean premixed injector by particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Berdanier, Catherine G. P.

    Limiting atmospheric pollution, especially nitrous oxides, is an important endeavor for aviation technology companies. Technology-driving regulations from the International Civil Aviation Organization's (ICAO) Committee of Aviation Environmental Protection (CAEP) standards spur the combustion research and development community to find innovative engine technologies to decrease emissions in the coming years. As engine technologies are developed, testing is necessary to verify combustion models and expected flow patterns. Optical diagnostics provide a unique opportunity to visualize flowfields in complex practical combustor systems. For this thesis, Particle Image Velocimetry (PIV) was employed to characterize the flowfield in a piloted lean premixed injector under non-combusting conditions. Planes of PIV data were acquired at five spanwise locations and two streamwise locations, at two different pressure conditions in order to characterize the flowfields and structures throughout the optically accessible flowpath. Average velocity maps and time-resolved vector fields at these planes were analyzed for this thesis.

  18. Microvascular Branching as a Determinant of Blood Flow by Intravital Particle Imaging Velocimetry

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; McKay, Terri L.; Vickerman, Mary B.; Wernet, Mark P.; Myers, Jerry G.; Radhakrishnan, Krishnan

    2007-01-01

    The effects of microvascular branching on blood flow were investigated in vivo by microscopic particle imaging velocimetry (micro-PIV). We use micro-PIV to measure blood flow by tracking red blood cells (RBC) as the moving particles. Velocity flow fields, including flow pulsatility, were analyzed for the first four branching orders of capillaries, postcapillary venules and small veins of the microvascular network within the developing avian yolksac at embryonic day 5 (E5). Increasing volumetric flowrates were obtained from parabolic laminar flow profiles as a function of increasing vessel diameter and branching order. Maximum flow velocities increased approximately twenty-fold as the function of increasing vessel diameter and branching order compared to flow velocities of 100 - 150 micron/sec in the capillaries. Results from our study will be useful for the increased understanding of blood flow within anastomotic, heterogeneous microvascular networks.

  19. Particle image velocimetry in a variable density flow: application to a dynamically evolving microburst

    NASA Astrophysics Data System (ADS)

    Alahyari, A.; Longmire, E. K.

    1994-10-01

    A fondamental difficulty in the experimental study of gravity-driven flows using particle image velocimetry (PIV) and other optical diagnostic techniques is the problem associated with variations in thé refractive index within the fluid. This paper discusses a method by which the refractive indices of two fluids are matched while maintaining density differences of up to 4%. Aqueous solutions of glycerol and potassium phosphate are used to achieve precise index matching in the presence of mixed and unmixed constituents. The effectiveness of the method is verified in a PIV study of a laboratory-scale model of an atmospheric microburst where planes of two-dimensional velocity vectors are obtained in thé evolving flow field.

  20. The complex aerodynamic footprint of desert locusts revealed by large-volume tomographic particle image velocimetry

    PubMed Central

    Henningsson, Per; Michaelis, Dirk; Nakata, Toshiyuki; Schanz, Daniel; Geisler, Reinhard; Schröder, Andreas; Bomphrey, Richard J.

    2015-01-01

    Particle image velocimetry has been the preferred experimental technique with which to study the aerodynamics of animal flight for over a decade. In that time, hardware has become more accessible and the software has progressed from the acquisition of planes through the flow field to the reconstruction of small volumetric measurements. Until now, it has not been possible to capture large volumes that incorporate the full wavelength of the aerodynamic track left behind during a complete wingbeat cycle. Here, we use a unique apparatus to acquire the first instantaneous wake volume of a flying animal's entire wingbeat. We confirm the presence of wake deformation behind desert locusts and quantify the effect of that deformation on estimates of aerodynamic force and the efficiency of lift generation. We present previously undescribed vortex wake phenomena, including entrainment around the wing-tip vortices of a set of secondary vortices borne of Kelvin–Helmholtz instability in the shear layer behind the flapping wings. PMID:26040598

  1. Investigation of cavitation bubble dynamics using particle image velocimetry: implications for photoacoustic drug delivery

    NASA Astrophysics Data System (ADS)

    Shangguan, HanQun; Casperson, Lee W.; Shearin, Alan; Prahl, Scott A.

    1996-05-01

    Photoacoustic drug delivery is a technique for delivering drugs to localized areas in the body. In cardiovascular applications, it uses a laser pulse to generate a cavitation bubble in a blood vessel due to the absorption of laser energy by targets (e.g., blood clots) or surrounding liquids (e.g., blood or injected saline). The hydrodynamic pressure arising from the expansion and collapse of the cavitation bubble can force the drug into the clots and tissue wall tissue. Time-resolved particle image velocimetry was used to investigate the flow of liquids during the expansion and collapse of cavitation bubbles near a soft boundary. A gelatin-based thrombus model was used to simulate the blood clot present during laser thrombolysis. An argon laser chopped by an acousto-optic modulator was used for illumination and photography was achieved using a CCD camera. The implications of this phenomenon on practical photoacoustic drug delivery implementation are discussed.

  2. Large Field of View Particle-Image Velocimetry (LF-PIV): Design and Performance

    NASA Astrophysics Data System (ADS)

    Pol, Suhas; Hoffman, John; Balasubramaniam, Balakumar; P-23, LANL Team

    2011-11-01

    We discuss the challenges and limitations associated with the development of a Large Field of View Particle Image Velocimetry (LF-PIV) diagnostic that is capable of resolving large scale motions (3m x 1m per camera) in gas phase laboratory experiments. While this diagnostic is developed for the measurement of wakes and local inflow conditions around research wind turbines, the design considerations provided here are also relevant for the application of LF-PIV to atmospheric boundary layer, rotorcraft dynamics and large-scale wind tunnel flows. Scaling laws associated with LF-PIV systems are presented along with the performance analysis of low-density, large diameter Expancel particles that appear to be promising candidates for LF-PIV seeding. Comparison of data obtained by LF-PIV measurements (2MP camera) and regular format sized PIV measurements show an agreement of within 1% for mean velocity and 8% for turbulent statistics respectively. Los Alamos National Laboratory, NM, USA.

  3. Volcano geodesy at Santiaguito using ground-based cameras and particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Johnson, J.; Andrews, B. J.; Anderson, J.; Lyons, J. J.; Lees, J. M.

    2012-12-01

    The active Santiaguito dome in Guatemala is an exceptional field site for ground-based optical observations owing to the bird's-eye viewing perspective from neighboring Santa Maria Volcano. From the summit of Santa Maria the frequent (1 per hour) explosions and continuous lava flow effusion may be observed from a vantage point, which is at a ~30 degree elevation angle, 1200 m above and 2700 m distant from the active vent. At these distances both video cameras and SLR cameras fitted with high-power lenses can effectively track blocky features translating and uplifting on the surface of Santiaguito's dome. We employ particle image velocimetry in the spatial frequency domain to map movements of ~10x10 m^2 surface patches with better than 10 cm displacement resolution. During three field campaigns to Santiaguito in 2007, 2009, and 2012 we have used cameras to measure dome surface movements for a range of time scales. In 2007 and 2009 we used video cameras recording at 30 fps to track repeated rapid dome uplift (more than 1 m within 2 s) of the 30,000 m^2 dome associated with the onset of eruptive activity. We inferred that the these uplift events were responsible for both a seismic long period response and an infrasound bimodal pulse. In 2012 we returned to Santiaguito to quantify dome surface movements over hour-to-day-long time scales by recording time lapse imagery at one minute intervals. These longer time scales reveal dynamic structure to the uplift and subsidence trends, effusion rate, and surface flow patterns that are related to internal conduit pressurization. In 2012 we performed particle image velocimetry with multiple cameras spatially separated in order to reconstruct 3-dimensional surface movements.

  4. Effects of red blood cell aggregates dissociation on the estimation of ultrasound speckle image velocimetry.

    PubMed

    Yeom, Eunseop; Nam, Kweon-Ho; Paeng, Dong-Guk; Lee, Sang-Joon

    2014-08-01

    Ultrasound speckle image of blood is mainly attributed by red blood cells (RBCs) which tend to form RBC aggregates. RBC aggregates are separated into individual cells when the shear force is over a certain value. The dissociation of RBC aggregates has an influence on the performance of ultrasound speckle image velocimetry (SIV) technique in which a cross-correlation algorithm is applied to the speckle images to get the velocity field information. The present study aims to investigate the effect of the dissociation of RBC aggregates on the estimation quality of SIV technique. Ultrasound B-mode images were captured from the porcine blood circulating in a mock-up flow loop with varying flow rate. To verify the measurement performance of SIV technique, the centerline velocity measured by the SIV technique was compared with that measured by Doppler spectrograms. The dissociation of RBC aggregates was estimated by using decorrelation of speckle patterns in which the subsequent window was shifted as much as the speckle displacement to compensate decorrelation caused by in-plane loss of speckle patterns. The decorrelation of speckles is considerably increased according to shear rate. Its variations are different along the radial direction. Because the dissociation of RBC aggregates changes ultrasound speckles, the estimation quality of SIV technique is significantly correlated with the decorrelation of speckles. This degradation of measurement quality may be improved by increasing the data acquisition rate. This study would be useful for simultaneous measurement of hemodynamic and hemorheological information of blood flows using only speckle images.

  5. Properties of iopamidol-incorporated poly(vinyl alcohol) microparticle as an X-ray imaging flow tracer.

    PubMed

    Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Lee, Sang Joon

    2011-02-10

    We have recently reported on poly(vinyl alcohol) microparticles containing X-ray contrast agent, iopamidol, designed as a flow tracer working in synchrotron X-ray imaging ( Biosens. Bioelectron. 2010 , 25 , 1571 ). Although iopamidol is physically encapsulated in the microparticles, it displays a great contrast enhancement and stable feasibility in in vitro human blood pool. Nonetheless, a direct relation between the absolute amount of incorporated iopamidol and the enhancement in imaging efficiency was not observed. In this study, physical properties of the designed microparticle are systematically investigated experimentally with theoretical interpretation to correlate an enhancement in X-ray imaging efficiency. The compositional ratio of X-ray contrast agent in polymeric microparticle is controlled as 1/1 and 10/1 [contrast agent/polymer microparticle (w/w)] with changed degree of cross-linkings. Flory-Huggins interaction parameter (χ), retractive force (τ) and degree of swelling of the designed polymeric microparticles are investigated. In addition, the hydrodynamic size (D(H)) and ζ-potential are evaluated in terms of environment responsiveness. The physical properties of the designed flow tracer microparticles under a given condition are observed to be strongly related with the X-ray absorption efficiency, which are also supported by the Beer-Lambert-Bouguer law. The designed microparticles are almost nontoxic with a reasonable concentration and time period, enough to be utilized as a flow tracer in various biomedical applications. This study would contribute to the basic understanding on the physical property connected with the imaging efficiency of contrast agents.

  6. Accuracy and Robustness Improvements of Echocardiographic Particle Image Velocimetry for Routine Clinical Cardiac Evaluation

    NASA Astrophysics Data System (ADS)

    Meyers, Brett; Vlachos, Pavlos; Charonko, John; Giarra, Matthew; Goergen, Craig

    2015-11-01

    Echo Particle Image Velocimetry (echoPIV) is a recent development in flow visualization that provides improved spatial resolution with high temporal resolution in cardiac flow measurement. Despite increased interest a limited number of published echoPIV studies are clinical, demonstrating that the method is not broadly accepted within the medical community. This is due to the fact that use of contrast agents are typically reserved for subjects whose initial evaluation produced very low quality recordings. Thus high background noise and low contrast levels characterize most scans, which hinders echoPIV from producing accurate measurements. To achieve clinical acceptance it is necessary to develop processing strategies that improve accuracy and robustness. We hypothesize that using a short-time moving window ensemble (MWE) correlation can improve echoPIV flow measurements on low image quality clinical scans. To explore the potential of the short-time MWE correlation, evaluation of artificial ultrasound images was performed. Subsequently, a clinical cohort of patients with diastolic dysfunction was evaluated. Qualitative and quantitative comparisons between echoPIV measurements and Color M-mode scans were carried out to assess the improvements delivered by the proposed methodology.

  7. Optimization and evaluation of fluorescent tracers for flare removal in gas-phase particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Chennaoui, M.; Angarita-Jaimes, D.; Ormsby, M. P.; Angarita-Jaimes, N.; McGhee, E.; Towers, C. E.; Jones, A. C.; Towers, D. P.

    2008-11-01

    We report the development of optimized fluorescent dye-doped tracer particles for gas-phase particle image velocimetry (PIV) and their use to eliminate 'flare' from the images obtained. In such applications, micron-sized tracer particles are normally required to accurately follow the flow. However, as the tracer size is reduced the amount of light incident on the particle diminishes and consequently the intensity of emitted light (fluorescence). Hence, there is a requirement to identify dyes with high quantum yield that can be dissolved in conventional tracer media at high concentrations. We describe the selection and characterization of a highly fluorescent blue-emitting dye, Bis-MSB, using a novel method, employing stabilized micro-emulsions, to emulate the fluorescence properties of tracer particles. We present the results of PIV experiments, using 1 µm tracer particles of o-xylene doped with Bis-MSB, in which elastically scattered 'flare' has been successfully removed from the images using an appropriate optical filter.

  8. A Globally Optimal Particle Tracking Technique for Stereo Imaging Velocimetry Experiments

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2008-01-01

    An important phase of any Stereo Imaging Velocimetry experiment is particle tracking. Particle tracking seeks to identify and characterize the motion of individual particles entrained in a fluid or air experiment. We analyze a cylindrical chamber filled with water and seeded with density-matched particles. In every four-frame sequence, we identify a particle track by assigning a unique track label for each camera image. The conventional approach to particle tracking is to use an exhaustive tree-search method utilizing greedy algorithms to reduce search times. However, these types of algorithms are not optimal due to a cascade effect of incorrect decisions upon adjacent tracks. We examine the use of a guided evolutionary neural net with simulated annealing to arrive at a globally optimal assignment of tracks. The net is guided both by the minimization of the search space through the use of prior limiting assumptions about valid tracks and by a strategy which seeks to avoid high-energy intermediate states which can trap the net in a local minimum. A stochastic search algorithm is used in place of back-propagation of error to further reduce the chance of being trapped in an energy well. Global optimization is achieved by minimizing an objective function, which includes both track smoothness and particle-image utilization parameters. In this paper we describe our model and present our experimental results. We compare our results with a nonoptimizing, predictive tracker and obtain an average increase in valid track yield of 27 percent

  9. Particle image velocimetry for the surface tension driven convection experiment using a particle displacement tracking technique

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Pline, Alexander D.

    1991-01-01

    The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

  10. Particle image velocimetry for the Surface Tension Driven Convection Experiment using a particle displacement tracking technique

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Pline, Alexander D.

    1991-01-01

    The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

  11. Powder dispersion mechanisms within a dry powder inhaler using microscale particle image velocimetry.

    PubMed

    Kou, Xiang; Wereley, Steven T; Heng, Paul W S; Chan, Lai Wah; Carvajal, M Teresa

    2016-12-05

    The goal of this work was to evaluate the ability of Particle Image Velocimetry (PIV) to visually assess dry powder dispersion within an inhaler. Herein, the study reports particle movement characterization of entrained low-micron particles within an inhaler to further scheme of potential mechanisms. Carrier based DPI formulations were prepared and placed in a transparent model Rotahaler(®) chamber for the aerosolization experiments. Then using the PIV, a high-speed camera, the dried powder dispersion was directly observed and analyzed for all, neat, binary and ternary systems. Powder dispersion mechanisms proposed include drag force, impact with obstacle and particle-particle collision; these different mechanisms depended on the powder flow properties. A revised ratio of aerodynamic response time (τA) to the mean time between collisions (τC) was found to be 6.8 indicating that particle collisions were of strong influence to particle dispersion. With image analysis techniques, visualization of particle flow pattern and collision regions was possible; suggesting that the various mechanisms proposed did govern the powder dispersion.

  12. Particle image velocimetry studies of bubble growth and detachment by high-speed photography

    NASA Astrophysics Data System (ADS)

    Stickland, Mathew; Dempster, William; Lothian, Lee; Oldroyd, Andrew

    1997-05-01

    An understanding of bubble flows is important in the design of process equipment, particularly in the chemical and power industries. In vapor-liquid processes the mass and heat transfer between the phases is dominated by the liquid-vapor interface and is determined by the number, size, and shape of the bubbles. For bubble flows these characteristics are often controlled by the generation mechanisms and, since bubble flows are often generated at an orifice, it is important to determine the controlling parameters which dictate how bubbles grow and detach. For bubbles growing at orifices the liquid displacement is an important feature and affects the pressure distribution acting on the bubble and the heat and mass transfer that may occur at the bubble interface. Therefore, in this study, the characteristics of the liquid velocity field are studied experimentally using Particle image Velocimetry (PIV) during growth, detachment and translation of a bubble being generated at an orifice supplied with a constant mass flow rate of air. The process is transient and occurs over a period of approximately 50 msecs. In order to map the transient flow field a combination of high speed cine and cross correlation PIV image processing has been used to determine the liquid velocity vector field during the bubble growth process. The paper contains details of the PIV technique and presents several of the velocity vector maps calculated.

  13. Flow Visualization and Particle Image Velocimetry Analysis of Rotor Vortex Wakes

    NASA Astrophysics Data System (ADS)

    Stack, James; Caradonna, Francis; Savas, Omer

    2004-11-01

    An experimental study is performed on a three-bladed rotor model in a stationary water tank, simulating a helicopter rotor operating in hover at Reynolds numbers of order 10^5. Flow visualization is done by injecting air bubbles and fluorescent dye tangentially from the blade tips to mark the vortices, showing the development of both short-wave (sinuous) and long-wave (leapfrogging) instabilities on the helical vortex filaments in the wake. The flow images show that as the instabilities develop, adjacent vortices merge and form thick vortex rings as quickly as half a rotor diameter downstream of the rotor disk. Particle image velocimetry data demonstrate the existence of the short-wave instability, evidenced by oscillations in the adjacent vortex core separation distance. At the same time, the long-wave instability is also apparent, as the vortices can be seen orbiting each other prior to merger. The circular axis and the moments of vorticity distribution are used to analyze the kinematics of vortex filament triads during formation, instability, and merger phases. Comparison of flow visualization and vorticity movies, however, shows interesting differences in the vortex merger process, possibly as a result of axial flow in the vortex cores.

  14. Particle Image Velocimetry Measurements in Anatomically-Accurate Models of the Mammalian Nasal Cavity

    NASA Astrophysics Data System (ADS)

    Rumple, C.; Richter, J.; Craven, B. A.; Krane, M.

    2012-11-01

    A summary of the research being carried out by our multidisciplinary team to better understand the form and function of the nose in different mammalian species that include humans, carnivores, ungulates, rodents, and marine animals will be presented. The mammalian nose houses a convoluted airway labyrinth, where two hallmark features of mammals occur, endothermy and olfaction. Because of the complexity of the nasal cavity, the anatomy and function of these upper airways remain poorly understood in most mammals. However, recent advances in high-resolution medical imaging, computational modeling, and experimental flow measurement techniques are now permitting the study of airflow and respiratory and olfactory transport phenomena in anatomically-accurate reconstructions of the nasal cavity. Here, we focus on efforts to manufacture transparent, anatomically-accurate models for stereo particle image velocimetry (SPIV) measurements of nasal airflow. Challenges in the design and manufacture of index-matched anatomical models are addressed and preliminary SPIV measurements are presented. Such measurements will constitute a validation database for concurrent computational fluid dynamics (CFD) simulations of mammalian respiration and olfaction. Supported by the National Science Foundation.

  15. Field Effects of Buoyancy on a Premixed Turbulent Flame Studied by Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Cheng, Robert K.

    2003-01-01

    Typical laboratory flames for the scientific investigation of flame/turbulence interactions are prone to buoyancy effects. Buoyancy acts on these open flame systems and provides upstream feedbacks that control the global flame properties as well as local turbulence/flame interactions. Consequently the flame structures, stabilization limits, and turbulent reaction rates are directly or indirectly coupled with buoyancy. The objective of this study is to characterize the differences between premixed turbulent flames pointing upwards (1g), pointing downwards (-1g), and in microgravity (mg). The configuration is an inverted conical flame stabilized by a small cone-shaped bluff body that we call CLEAN Flames (Cone-Stabilized Lean Flames). We use two laser diagnostics to capture the velocity and scalar fields. Particle image velocimetry (PIV) measures the mean and root mean square velocities and planar imaging by the flame fronts method outlines the flame wrinkle topology. The results were obtained under typical conditions of small domestic heating systems such as water heaters, ovens, and furnaces. Significant differences between the 1g and -1g flames point to the need for including buoyancy contributions in theoretical and numerical calculations. In Earth gravity, there is a complex coupling of buoyancy with the turbulent flow and heat release in the flame. An investigation of buoyancy-free flames in microgravity will provide the key to discern gravity contributions. Data obtained in microgravity flames will provide the benchmark for interpreting and analyzing 1g and -1g flame results.

  16. Flow characteristics in free impinging jet reactor by particle image velocimetry (PIV) investigation

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Liu, Youzhi; Qi, Guisheng; Jiao, Weizhou; Yuan, Zhiguo

    2016-08-01

    The flow characteristics in free impinging jet reactors (FIJRs) were investigated using particle image velocimetry (PIV). The effects of the Reynolds number (Re) and the ratio of jet distance to jet diameter (w/d) on flow behavior were discussed for equal volumetric flow rates of the two jets. The impingement plane, instantaneous velocity, mean velocity, and turbulent kinetic energy (TKE) distribution of FIJRs are measured from captured images using the PIV technique. As Re increases, the average diameter of the impingement plane linearly increases. The instability of the liquid is closely related to the jet velocity or the Re. However, the stagnation point is insensitive to the variation of the Re. The droplets break up from the turbulent liquid in the ‘wall-free’ environment of FIJRs, so that the liquid back-flow found in confined impinging jet reactors (CIJRs) is not observed. Increasing the Re from 1800-4100 or decreasing the w/d from 20-6 plays a similar role in increasing the TKE values and intensifying turbulence, which promotes the momentum transfer and mixing efficiency in FIJRs.

  17. Estimation of uncertainty bounds for individual particle image velocimetry measurements from cross-correlation peak ratio

    NASA Astrophysics Data System (ADS)

    Charonko, John J.; Vlachos, Pavlos P.

    2013-06-01

    Numerous studies have established firmly that particle image velocimetry (PIV) is a robust method for non-invasive, quantitative measurements of fluid velocity, and that when carefully conducted, typical measurements can accurately detect displacements in digital images with a resolution well below a single pixel (in some cases well below a hundredth of a pixel). However, to date, these estimates have only been able to provide guidance on the expected error for an average measurement under specific image quality and flow conditions. This paper demonstrates a new method for estimating the uncertainty bounds to within a given confidence interval for a specific, individual measurement. Here, cross-correlation peak ratio, the ratio of primary to secondary peak height, is shown to correlate strongly with the range of observed error values for a given measurement, regardless of flow condition or image quality. This relationship is significantly stronger for phase-only generalized cross-correlation PIV processing, while the standard correlation approach showed weaker performance. Using an analytical model of the relationship derived from synthetic data sets, the uncertainty bounds at a 95% confidence interval are then computed for several artificial and experimental flow fields, and the resulting errors are shown to match closely to the predicted uncertainties. While this method stops short of being able to predict the true error for a given measurement, knowledge of the uncertainty level for a PIV experiment should provide great benefits when applying the results of PIV analysis to engineering design studies and computational fluid dynamics validation efforts. Moreover, this approach is exceptionally simple to implement and requires negligible additional computational cost.

  18. Neutron Activated Samarium-153 Microparticles for Transarterial Radioembolization of Liver Tumour with Post-Procedure Imaging Capabilities

    PubMed Central

    Hashikin, Nurul Ab. Aziz; Yeong, Chai-Hong; Abdullah, Basri Johan Jeet; Ng, Kwan-Hoong; Chung, Lip-Yong; Dahalan, Rehir; Perkins, Alan Christopher

    2015-01-01

    Introduction Samarium-153 (153Sm) styrene divinylbenzene microparticles were developed as a surrogate for Yttrium-90 (90Y) microspheres in liver radioembolization therapy. Unlike the pure beta emitter 90Y, 153Sm possess both therapeutic beta and diagnostic gamma radiations, making it possible for post-procedure imaging following therapy. Methods The microparticles were prepared using commercially available cation exchange resin, Amberlite IR-120 H+ (620–830 μm), which were reduced to 20–40 μm via ball mill grinding and sieve separation. The microparticles were labelled with 152Sm via ion exchange process with 152SmCl3, prior to neutron activation to produce radioactive 153Sm through 152Sm(n,γ)153Sm reaction. Therapeutic activity of 3 GBq was referred based on the recommended activity used in 90Y-microspheres therapy. The samples were irradiated in 1.494 x 1012 n.cm-2.s-1 neutron flux for 6 h to achieve the nominal activity of 3.1 GBq.g-1. Physicochemical characterisation of the microparticles, gamma spectrometry, and in vitro radiolabelling studies were carried out to study the performance and stability of the microparticles. Results Fourier Transform Infrared (FTIR) spectroscopy of the Amberlite IR-120 resins showed unaffected functional groups, following size reduction of the beads. However, as shown by the electron microscope, the microparticles were irregular in shape. The radioactivity achieved after 6 h neutron activation was 3.104 ± 0.029 GBq. The specific activity per microparticle was 53.855 ± 0.503 Bq. Gamma spectrometry and elemental analysis showed no radioactive impurities in the samples. Radiolabelling efficiencies of 153Sm-Amberlite in distilled water and blood plasma over 48 h were excellent and higher than 95%. Conclusion The laboratory work revealed that the 153Sm-Amberlite microparticles demonstrated superior characteristics for potential use in hepatic radioembolization. PMID:26382059

  19. Particle image velocimetry measurements of massively separated turbulent flows with rotation

    NASA Astrophysics Data System (ADS)

    Visscher, Jan; Andersson, Helge I.

    2011-07-01

    Measurements of instantaneous velocity fields in the separated flow downstream of a backward-facing step in a rotating channel are presented for the first time. Particle image velocimetry (PIV) measurements were made for 13 different rotation numbers Ro at a bulk flow Reynolds number of about 5600. The expansion ratio 2:1 was the same as in the flow visualization study by Rothe and Johnston [ASME J. Fluids Eng. 101, 117 (1979)] which covered about the same range of Ro. The measured mean flow pattern exhibited substantial variations with the rate of system rotation. In particular, the length of the primary separation bubble decreased monotonically with increasing anti-cyclonic rotation and increased with increasing rate of cyclonic rotation, in keeping with the earlier observations. At the highest anti-cyclonic rotation rate, the flow field also separated from the planar wall where the shear layer flow was subjected to cyclonic rotation. The PIV data for the in-plane components of the Reynolds stress tensor were severely affected by the imposed system rotation. Almost all the striking affects of the Coriolis force observed herein could be explained by means of the exact production terms in the transport equation for the second-moments of the velocity fluctuations. These changes were in turn consistent with the observed alterations of the mean flow field.

  20. Measurement of Meteor Impact Experiments Using Three-Component Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Heineck, James T.; Schultz, Peter H.

    2002-01-01

    The study of hypervelocity impacts has been aggressively pursued for more than 30 years at Ames as a way to simulate meteoritic impacts. Development of experimental methods coupled with new perspectives over this time has greatly improved the understanding of the basic physics and phenomenology of the impact process. These fundamental discoveries have led to novel methods for identifying impact craters and features in craters on both Earth and other planetary bodies. Work done at the Ames Vertical Gun Range led to the description of the mechanics of the Chicxualub crater (a.k.a. K-T crater) on the Yucatan Peninsula, widely considered to be the smoking gun impact that brought an end to the dinosaur era. This is the first attempt in the world to apply three-component particle image velocimetry (3-D PIV) to measure the trajectory of the entire ejecta curtain simultaneously with the fluid structure resulting from impact dynamics. The science learned in these experiments will build understanding in the entire impact process by simultaneously measuring both ejecta and atmospheric mechanics.

  1. Measurements of the heat release rate integral in turbulent premixed stagnation flames with particle image velocimetry

    SciTech Connect

    Chen, Yung-Cheng; Kim, Munki; Han, Jeongjae; Yun, Sangwook; Yoon, Youngbin

    2008-08-15

    A new definition of turbulent consumption speed is proposed in this work that is based on the heat release rate integral, rather than the mass burning rate integral. Its detailed derivation and the assumptions involved are discussed in a general context that applies to all properly defined reaction progress variables. The major advantage of the proposed definition is that it does not require the thin-flame assumption, in contrast to previous definitions. Experimental determination of the local turbulent displacement speed, S{sub D}, and the local turbulent consumption speed, S{sub C}, is also demonstrated with the particle image velocimetry technique in three turbulent premixed stagnation flames. The turbulence intensity of these flames is of the same order of the laminar burning velocity. Based on the current data, a model equation for the local mean heat release rate is proposed. The relationship between S{sub D} and S{sub C} is discussed along with a possible modeling approach for the turbulent displacement speed. (author)

  2. Digital particle image velocimetry measurements of the downwash distribution of a desert locust Schistocerca gregaria

    PubMed Central

    Bomphrey, Richard J; Taylor, Graham K; Lawson, Nicholas J; Thomas, Adrian L.R

    2005-01-01

    Actuator disc models of insect flight are concerned solely with the rate of momentum transfer to the air that passes through the disc. These simple models assume that an even pressure is applied across the disc, resulting in a uniform downwash distribution. However, a correction factor, k, is often included to correct for the difference in efficiency between the assumed even downwash distribution, and the real downwash distribution. In the absence of any empirical measurements of the downwash distribution behind a real insect, the values of k used in the literature have been necessarily speculative. Direct measurement of this efficiency factor is now possible, and could be used to compare the relative efficiencies of insect flight across the Class. Here, we use Digital Particle Image Velocimetry to measure the instantaneous downwash distribution, mid-downstroke, of a tethered desert locust (Schistocerca gregaria). By integrating the downwash distribution, we are thereby able to provide the first direct empirical measurement of k for an insect. The measured value of k=1.12 corresponds reasonably well with that predicted by previous theoretical studies. PMID:16849240

  3. Wall Shear Stress in Oscillating Channel Flow Using Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Lance, Blake; Roberts, Jesse; Smith, Barton; Kearney, Sean

    2013-11-01

    Offshore wind and water power are renewable sources with the potential for significant power generation. But each generation mechanism has risks from ocean floor structures that can disrupt natural sediment transport by increasing local shear stress. The Sediment Erosion Actuated by Wave Oscillations and Linear Flow (SEAWOLF) flume was designed and built to replicate wave motion with both oscillatory and unidirectional components to study sediment transport. The rectangular test section provides optical access for Particle Image Velocimetry (PIV) measurements. Additionally series of pressure taps allow for differential pressure measurements. Sine-wave oscillations and unidirectional flow in more than a dozen combinations are measured and presented. Phase locked measurements of volume flow rates, velocity fields, and pressure are acquired over several hundred cycles and phase averaged. High spatial resolution PIV is used near the wall for direct shear stress measurements. Since the flow is unsteady, the pressure drop in the test section has both inertial and friction contributions. To isolate the friction term, the pressure resulting from the fluid acceleration is subtracted. The synced PIV and pressure measurements on smooth walls where the viscous sublayer is formed confirm the accuracy of this method. The pressure sensor then measures shear stress on rough walls where the viscous sublayer is disrupted or non-existent and where optical access is difficult.

  4. Visualization of air flow around soccer ball using a particle image velocimetry

    PubMed Central

    Hong, Sungchan; Asai, Takeshi; Seo, Kazuya

    2015-01-01

    A traditional soccer ball is constructed using 32 pentagonal and hexagonal panels. In recent years, however, the likes of the Teamgeist and Jabulani balls, constructed from 14 and 8 panels, respectively, have entered the field, marking a significant departure from conventionality in terms of shape and design. Moreover, the recently introduced Brazuca ball features a new 6-panel design and has already been adopted by many soccer leagues. However, the shapes of the constituent panels of these balls differ substantially from those of conventional balls. Therefore, this study set out to investigate the flight and aerodynamic characteristics of different orientations of the soccer ball, which is constructed from panels of different shapes. A wind tunnel test showed substantial differences in the aerodynamic forces acting on the ball, depending on its orientation. Substantial differences were also observed in the aerodynamic forces acting on the ball in different directions, corresponding to its orientation and rotation. Moreover, two-dimensional particle image velocimetry (2D-PIV) measurements showed that the boundary separation varies depending on the orientation of the ball. Based on these results, we can conclude that the shape of the panels of a soccer ball substantially affects its flight trajectory. PMID:26446616

  5. Visualization of nasal airflow patterns in a patient affected with atrophic rhinitis using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Garcia, G. J. M.; Mitchell, G.; Bailie, N.; Thornhill, D.; Watterson, J.; Kimbell, J. S.

    2007-10-01

    The relationship between airflow patterns in the nasal cavity and nasal function is poorly understood. This paper reports an experimental study of the interplay between symptoms and airflow patterns in a patient affected with atrophic rhinitis. This pathology is characterized by mucosal dryness, fetor, progressive atrophy of anatomical structures, a spacious nasal cavity, and a paradoxical sensation of nasal congestion. A physical replica of the patient's nasal geometry was made and particle image velocimetry (PIV) was used to visualize and measure the flow field. The nasal replica was based on computed tomography (CT) scans of the patient and was built in three steps: three-dimensional reconstruction of the CT scans; rapid prototyping of a cast; and sacrificial use of the cast to form a model of the nasal passage in clear silicone. Flow patterns were measured by running a water-glycerol mixture through the replica and evaluating the displacement of particles dispersed in the liquid using PIV. The water-glycerol flow rate used corresponded to an air flow rate representative of a human breathing at rest. The trajectory of the flow observed in the left passage of the nose (more affected by atrophic rhinitis) differed markedly from what is considered normal, and was consistent with patterns of epithelial damage observed in cases of the condition. The data are also useful for validation of computational fluid dynamics predictions.

  6. Ghost Cell Suspensions as Blood Analogue Fluid for Macroscopic Particle Image Velocimetry Measurements.

    PubMed

    Jansen, Sebastian V; Müller, Indra; Nachtsheim, Max; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2016-02-01

    Spatially resolved measurement of blood flow is of great interest in the development of artificial blood-carrying devices such as blood pumps, heart valve prostheses, and oxygenators. Particle image velocimetry (PIV) is able to measure instantaneous velocity fields in a plane with high accuracy and is being used more frequently for the development of such devices. However, as this measurement technique is based on optical access, blood flow at physiological hematocrit values is difficult to measure due to its low transparency and multiscattering properties. So far, only very small dimensions (in the range of 400 μm) can be measured using PIV. A suspension of ghost cells (GCs) offers a higher optical transparency than blood while having a similar rheological behavior. In this study, a procedure for the production of GC suspensions containing a very low intracellular hemoglobin concentration is presented. With the help of multiple rounds of controlled cell lysis, the intracellular hemoglobin concentration could be decreased to a point where a standard macroscopic PIV measurement was possible. A velocity profile of a 44% GC suspension in a circular channel with a diameter of 9.5 mm was measured with high spatial resolution. Meanwhile, the rheological behavior was found to be comparable with blood.

  7. Turbulent eddies in a compressible jet in crossflow measured using pulse-burst particle image velocimetry

    DOE PAGES

    Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; ...

    2016-01-01

    Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. Eddies were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. Correlated counter-rotating vortices are more strongly observed to pass by at a larger spacing,more » both leading and trailing the reference eddy. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer eddies.« less

  8. Turbulent eddies in a compressible jet in crossflow measured using pulse-burst particle image velocimetry

    SciTech Connect

    Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

    2016-01-01

    Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. Eddies were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. Correlated counter-rotating vortices are more strongly observed to pass by at a larger spacing, both leading and trailing the reference eddy. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer eddies.

  9. Investigation of Thunniform Swimming Using Material Testing, Biomimetic Robotics and Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Zhu, Ruijie; Saraiya, Vishaal; Zhu, Jianzhong; Lewis, Gregory; Bart-Smith, Hilary

    2015-11-01

    Thunniform swimming is well recognized as an efficient method for high-speed long-distance underwater travelers such as tuna. Previous research has shown that tuna relies on contraction and relaxation of red muscle to generate angular motion of its large, crescent-shaped caudal fin through its peduncle. However, few researchers conduct deep investigation of material properties of tuna caudal fin and peduncle. This research project is composed of two parts, first of which is determining mechanical properties of components such as spine joints, tendons, fin rays and cartilage, from which the biomechanics of tuna tail can be better understood. The second part is building a robotic system mimicking a real tuna tail based on previously retrieved information, and testing the system inside a flow tank. With the help of PIV (Particle Image Velocimetry), fluid-structure interaction of the biomimetic fin is visualized and data such as swimming speed and power consumption are retrieved through the robotic system. The final outcome should explain how the material properties of tuna tail affect fluid dynamics of thunniform swimming. This project is supported by Office of Naval Research (ONRBAA13-022).

  10. Turbulent Stress Measurements In The Coastal Ocean Using Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Nimmo Smith, W. A. M.; Osborn, T. R.; Luznik, L.; Zhu, W.; Katz, J.

    Particle Image Velocimetry (PIV) produces two-dimensional visualizations of the ve- locity field over the sample area. In our system we map the vertical velocity compo- nent and one component of the horizontal velocity over two collinear, parallel, 0.4 m square windows, which are separated horizontally by 0.4 m. From these measurements we can calculate structure functions for separations up to 1.2 m scales. Trowbridge (1998) introduces a technique for overcoming the wave contamination in Reynolds stress measurements. The flow field is decomposed into a mean flow, wave motion, and turbulent motions. The covariance of the velocity differences between two separate point sensors spaced further apart than the scale of the stress containing eddies but close compared to the wavelength of the surface waves provides a relatively uncontaminated estimate of the Reynolds stress. One can generalize this approach using the PIV data by calculating the second order structure function of the vertical and horizontal velocity components, for length scales extending from the vector spacing (5mm) up to 1.2m. The PIV data offer additional advantages, such as U the very good alignment of the velocity components measured at different locations, the large number of spatial samples, and the high spatial resolution of the velocity distributions. Measurements from the LEO-15 coastal observatory are used to show the applica- tion of the method and discuss the potential for wave turbulence correlations due to topographic effects.

  11. Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Sciacchitano, A.; Veldhuis, L. L. M.; Eitelberg, G.

    2016-10-01

    During the ground operation of aircraft, there is potentially a system of vortices generated from the ground toward the propulsor, commonly denoted as ground vortices. Although extensive research has been conducted on ground vortices induced by turbofans which were simplified by suction tubes, these studies cannot well capture the properties of ground vortices induced by propellers, e.g., the flow phenomena due to intermittent characteristics of blade passing and the presence of slipstream of the propeller. Therefore, the investigation of ground vortices induced by a propeller is performed to improve understanding of these phenomena. The distributions of velocities in two different planes containing the vortices were measured by high frequency Particle Image Velocimetry. These planes are a wall-parallel plane in close proximity to the ground and a wall-normal plane upstream of the propeller. The instantaneous flow fields feature highly unsteady flow in both of these two planes. The spectral analysis is conducted in these two flow fields and the energetic frequencies are quantified. The flow fields are further evaluated by applying the Proper Orthogonal Decomposition analysis to capture the coherent flow structures. Consistent flow structures with strong contributions to the turbulent kinetic energy are noticed in the two planes.

  12. Deriving a blood-mimicking fluid for particle image velocimetry in Sylgard-184 vascular models.

    PubMed

    Yousif, Majid Y; Holdsworth, David W; Poepping, Tamie L

    2009-01-01

    A new blood-mimicking fluid (BMF) has been developed for particle image velocimetry (PIV), which enables flow studies in vascular models (phantoms). A major difficulty in PIV that affects measurement accuracy is the refraction and distortion of light passing through the interface between the model and the fluid, due to the difference in refractive index (n) between the two materials. The problem can be eliminated by using a fluid with a refractive index matching that of the model. Such fluids are not commonly available, especially for vascular research where the fluid should also have a viscosity similar to human blood. In this work, a blood-mimicking fluid, composed of water (47.38% by weight), glycerol (36.94% by weight) and sodium iodide salt (15.68% by weight), was developed for compatibility with our silicone (Sylgard 184; n = 1.414) phantoms. The fluid exhibits a dynamic viscosity of 4.31+/-0.03 cP which lies within the range of human blood viscosity (4.4+/-0.6 cP). Both refractive index and viscosity were attained at 22.2+/-0.2 degrees C, which is a feasible room temperature, thus eliminating the need for a temperature-control system. The fluid will be used to study hemodynamics in vascular flow models fabricated from Sylgard 184.

  13. A blood-mimicking fluid for particle image velocimetry with silicone vascular models

    NASA Astrophysics Data System (ADS)

    Yousif, Majid Y.; Holdsworth, David W.; Poepping, Tamie L.

    2011-03-01

    For accurate particle image velocimetry measurements in hemodynamics studies, it is important to use a fluid with a refractive index ( n) matching that of the vascular models (phantoms) and ideally a dynamic viscosity matching human blood. In this work, a blood-mimicking fluid (BMF) composed of water, glycerol, and sodium iodide was formulated for a range of refractive indices to match most common silicone elastomers ( n = 1.40-1.43) and with corresponding dynamic viscosity within the average cited range of healthy human blood (4.4 ± 0.5 cP). Both refractive index and viscosity were attained at room temperature (22.2 ± 0.2°C), which eliminates the need for a temperature-control system. An optimally matched BMF, suitable for use in a vascular phantom ( n = 1.4140 ± 0.0008, Sylgard 184), was demonstrated with composition (by weight) of 47.38% water, 36.94% glycerol (44:56 glycerol-water ratio), and 15.68% sodium iodide salt, resulting in a dynamic viscosity of 4 .31 ± 0 .03 cP.

  14. A simple, inexpensive system for digital particle image velocimetry (DPIV) in biomechanics.

    PubMed

    Ryerson, William G; Schwenk, Kurt

    2012-02-01

    Functional morphology and biomechanics seek to reveal the mechanistic bases of organismal functions and the physical principles involved at the phenotype-environment interface. Characterization of fluid flow (air or water) within and around organismal structures is an example of this approach. Digital particle imaging velocimetry (DPIV) has been exploited in a variety of biological systems to visualize fluid flow associated with animal movement. DPIV employs particles suspended in air or water that are illuminated by a laser light sheet and recorded with a high-speed video camera. Software tracks particle movement across a specified number of video frames, generating vector diagrams showing patterns of fluid flow through time. As powerful as DPIV methods are, they are limited in application by the high cost and complexity of the equipment required. In this article, we describe a simple DPIV system that substitutes widely available, inexpensive consumer components for scientific-grade equipment to achieve low cost (<$1,000 total) and high accuracy (total error calculated to be approx. 6%, as compared with 5% in professional systems). We have employed this system successfully in our studies on the fluid dynamics of chemosensory tongue-flicking in snakes. This system can be used for research and teaching in labs that typically cannot afford the expense or commitment of a traditional DPIV apparatus and is particularly suited for obtaining preliminary data required to justify further grant and institutional support.

  15. A tomographic particle image velocimetry investigation of the flow development over dual step cylinders

    SciTech Connect

    Morton, C.; Yarusevych, S.; Scarano, F.

    2016-02-15

    This experimental study focuses on the near wake development of a dual step cylinder geometry consisting of a long base cylinder of diameter d to which a larger diameter (D) cylinder of length L is attached coaxially at mid-span. The experiments cover a range of Reynolds numbers, 2000 ≤ Re{sub D} ≤ 5000, diameter ratios, 1.33 ≤ D/d ≤ 2.0 and large cylinder aspect ratios, 0.5 ≤ L/D ≤ 5 using Tomographic particle image velocimetry. Distinct changes in wake topology are observed varying the above parameters. Supporting previous experimental studies on the same geometry involving flow visualization and planar measurements, four distinct flow regimes are identified to which a distinct three-dimensional wake topology can be associated. The vortex-dominated wake dynamical behaviour is investigated with Proper Orthogonal Decomposition (POD) and conditional averaging of three-dimensional velocity fields is used to exemplify the different shedding regimes. The conditionally averaged flow fields are shown to quantitatively resolve flow features equivalent to those obtained from a reduced order model consisting of the first ten to twenty POD modes, identifying the dominant vortex shedding cells and their interactions.

  16. Application of Stereoscopic Particle Image Velocimetry to Experimental Analysis of Flow through Multiblade Fan

    NASA Astrophysics Data System (ADS)

    Cho, Gyeong Rae; Kawahashi, Masaaki; Hirahara, Hiroyuki; Kitadume, Michio

    An experimental analysis of the 3D velocity field of flow is very effective for the understanding of the physical significance of complex flow and for the practical design of fluid machinery. Under the currently circumstance, stereoscopic particle image velocimetry (SPIV) is one of the promising techniques for the experimental analysis. Although the development of algorithms and the feasibility studies of SPIV have been realized, the accumulation of techniques for applications leading to the design of practical fluid machineries or devices is not yet sufficient. To establish practical techniques for the experimental analysis of 3D flow in fluid machinery by SPIV, the detailed 3D analysis of flow using a utility model of multiblade fans used in automobile air-conditioning systems has been carried out. The stereo view camera arrangement and laser-light-sheet illumination for the complex shape of the fan and for the 3D flow through it have been investigated, and the visualization of experimental results for the understanding of the flow structure has also been discussed. The results obtained using the practical techniques applied in this experiment provide knowledge useful in the understanding of flow through the fan and in improving it.

  17. Particle image velocimetry (PIV) study of rotating cylindrical filters for animal cell perfusion processes.

    PubMed

    Figueredo-Cardero, Alvio; Chico, Ernesto; Castilho, Leda; de Andrade Medronho, Ricardo

    2012-01-01

    In the present work, the main fluid flow features inside a rotating cylindrical filtration (RCF) system used as external cell retention device for animal cell perfusion processes were investigated using particle image velocimetry (PIV). The motivation behind this work was to provide experimental fluid dynamic data for such turbulent flow using a high-permeability filter, given the lack of information about this system in the literature. The results shown herein gave evidence that, at the boundary between the filter mesh and the fluid, a slip velocity condition in the tangential direction does exist, which had not been reported in the literature so far. In the RCF system tested, this accounted for a fluid velocity 10% lower than that of the filter tip, which could be important for the cake formation kinetics during filtration. Evidence confirming the existence of Taylor vortices under conditions of turbulent flow and high permeability, typical of animal cell perfusion RCF systems, was obtained. Second-order turbulence statistics were successfully calculated. The radial behavior of the second-order turbulent moments revealed that turbulence in this system is highly anisotropic, which is relevant for performing numerical simulations of this system.

  18. A Laboratory Study of Rain-Induced Underwater Turbulence Using Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Liu, R.; Liu, X.; Duncan, J. H.

    2014-11-01

    The characteristics of rain-induced turbulence under a free surface are studied experimentally with Paticle Image Velocimetry (PIV) techniques in a 1.22-m-by-1.22-m water pool with a water depth of 0.3 m. A rain generator consisting of an open-surface water tank with an array of 22-gauge hypodermic needles attached to the tank bottom is mounted above the water pool. The tank is connected to a 2D translation stage to provide a small-radius horizontal circular motion to the needles, thus avoiding repeated drop impacts at the same location under each needle. The drop diameter is 2.6 mm and the height of the rain generator above the water surface of the pool is varied from 1 m to 2.5 m to provide different impact velocities. Both the flow field of a single drop impact and the turbulent layer under the free surface during rain simulations were measured with PIV. It was found that the drop penetration, the thickness of the turbulent layer under the free surface and the RMS velocity fluctuation are strongly correlated to the impact velocities of raindrops. The influence of this turbulence on the height of rebounding jet stalks from drop impacts is discussed. The support of the National Science Foundation, Division of Ocean Sciences, is gratefully acknowledged.

  19. Using Particle Imaging Velocimetry and Radio Frequency Identification to gain insights into erosion processes

    NASA Astrophysics Data System (ADS)

    Parsons, A. J.; Wainwright, J.; Cooper, J. R.; Onda, Y.; Long, E. J.; Hargrave, G.; Kitchener, B.

    2012-12-01

    Erosion is a particle-based phenomenon, yet most of current understanding and modelling of this process is based on bulk measurements rather than the movement of individual particles. However, the application of two new technologies allows improved insight into the entrainment, transport and deposition of individual particles and facilitates particle-based modelling of the particle-based process. In this presentation we provide insights into particle movement based upon laboratory experiments using particle imaging velocimetry (PIV) and radio frequency identification (RFID). PIV has been used in experiments in which single raindrops have fallen onto dry sand in order to track the trajectories of detached particles. By measuring the movement of individual particles our aim is to compute the proportion of rainfall energy that is used in particle detachment and transport, and the controls on this proportion. RFID tags embedded into resin to mimic sand-sized particles have been tracked under simulated rainfall applied to bare-soil plots. By covering and uncovering particles at different times during the experiments we have been able to produce distributions of travel distances of particles under conditions of rainfall detachment and transport, overland-flow detachment and transport and combined raindrop detachment and flow transport.

  20. Visualization of air flow around soccer ball using a particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Hong, Sungchan; Asai, Takeshi; Seo, Kazuya

    2015-10-01

    A traditional soccer ball is constructed using 32 pentagonal and hexagonal panels. In recent years, however, the likes of the Teamgeist and Jabulani balls, constructed from 14 and 8 panels, respectively, have entered the field, marking a significant departure from conventionality in terms of shape and design. Moreover, the recently introduced Brazuca ball features a new 6-panel design and has already been adopted by many soccer leagues. However, the shapes of the constituent panels of these balls differ substantially from those of conventional balls. Therefore, this study set out to investigate the flight and aerodynamic characteristics of different orientations of the soccer ball, which is constructed from panels of different shapes. A wind tunnel test showed substantial differences in the aerodynamic forces acting on the ball, depending on its orientation. Substantial differences were also observed in the aerodynamic forces acting on the ball in different directions, corresponding to its orientation and rotation. Moreover, two-dimensional particle image velocimetry (2D-PIV) measurements showed that the boundary separation varies depending on the orientation of the ball. Based on these results, we can conclude that the shape of the panels of a soccer ball substantially affects its flight trajectory.

  1. Monitoring an eruption fissure in 3D: video recording, particle image velocimetry and dynamics

    NASA Astrophysics Data System (ADS)

    Witt, Tanja; Walter, Thomas R.

    2015-04-01

    The processes during an eruption are very complex. To get a better understanding several parameters are measured. One of the measured parameters is the velocity of particles and patterns, as ash and emitted magma, and of the volcano itself. The resulting velocity field provides insights into the dynamics of a vent. Here we test our algorithm for 3 dimensional velocity fields on videos of the second fissure eruption of Bárdarbunga 2014. There we acquired videos from lava fountains of the main fissure with 2 high speed cameras with small angles between the cameras. Additionally we test the algorithm on videos from the geyser Strokkur, where we had 3 cameras and larger angles between the cameras. The velocity is calculated by a correlation in the Fourier space of contiguous images. Considering that we only have the velocity field of the surface smaller angles result in a better resolution of the existing velocity field in the near field. For general movements also larger angles can be useful, e.g. to get the direction, height and velocity of eruption clouds. In summary, it can be stated that 3D velocimetry can be used for several application and with different setup due to the application.

  2. Particle image velocimetry measurements of three proximal anastomosis models under a pulsatile flow condition.

    PubMed

    Chua, L P; Ji, W-F; Yu, C M; Zhou, T-M; Tan, Y S

    2008-04-01

    This study was designed to examine the effects of the anastomotic angle on the flow and haemodynamic parameter distribution patterns of the proximal anastomoses, with emphasis on identifying site-specific haemodynamic features that could reasonably be expected to trigger the initiation and further development of anastomotic intimal hyperplasia. Particle image velocimetry measurements were carried out with three simplified glass proximal models under a physiological flow condition. The results revealed that the disturbed flow and the induced shear stress patterns including low recirculation flow, stagnation point, high wall shear stress, high temporal wall shear stress gradient, low time-averaged wall shear stress (TAWSS), and high oscillating shear index (OSI) occurred around the anastomotic joints and the flow field at proximal anastomosis was strongly affected by the anastomotic angle. Among the three models investigated, the 45 degrees backward anastomosis is found to have a smaller low-recirculation-flow region along the graft inner wall, non-stationary stagnation, and separation points, a higher TAWSS and smaller high-OSI low-TAWSS and low-OSI high-TAWSS regions.

  3. Velocity Measurement in a Dual-Mode Supersonic Combustor using Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Goyne, C. P.; McDaniel, J. C.; Krauss, R. H.; Day, S. W.; Reubush, D. E. (Technical Monitor); McClinton, C. R. (Technical Monitor); Reubush, D. E.

    2001-01-01

    Temporally and spatially-resolved, two-component measurements of velocity in a supersonic hydrogen-air combustor are reported. The combustor had a single unswept ramp fuel injector and operated with an inlet Mach number of 2 and a flow total temperature approaching 1200 K. The experiment simulated the mixing and combustion processes of a dual-mode scramjet operating at a flight Mach number near 5. The velocity measurements were obtained by seeding the fuel with alumina particles and performing Particle Image Velocimetry on the mixing and combustion wake of the ramp injector. To assess the effects of combustion on the fuel air-mixing process, the distribution of time-averaged velocity and relative turbulence intensity was determined for the cases of fuel-air mixing and fuel-air reacting. Relative to the mixing case, the near field core velocity of the reacting fuel jet had a slower streamwise decay. In the far field, downstream of 4 to 6 ramp heights from the ramp base, the heat release of combustion resulted in decreased flow velocity and increased turbulence levels. The reacting measurements were also compared with a computational fluid dynamics solution of the flow field. Numerically predicted velocity magnitudes were higher than that measured and the jet penetration was lower.

  4. Multiparticle imaging technique for two-phase fluid flows using pulsed laser speckle velocimetry

    SciTech Connect

    Hassan, T.A.

    1992-12-01

    The practical use of Pulsed Laser Velocimetry (PLV) requires the use of fast, reliable computer-based methods for tracking numerous particles suspended in a fluid flow. Two methods for performing tracking are presented. One method tracks a particle through multiple sequential images (minimum of four required) by prediction and verification of particle displacement and direction. The other method, requiring only two sequential images uses a dynamic, binary, spatial, cross-correlation technique. The algorithms are tested on computer-generated synthetic data and experimental data which was obtained with traditional PLV methods. This allowed error analysis and testing of the algorithms on real engineering flows. A novel method is proposed which eliminates tedious, undersirable, manual, operator assistance in removing erroneous vectors. This method uses an iterative process involving an interpolated field produced from the most reliable vectors. Methods are developed to allow fast analysis and presentation of sets of PLV image data. Experimental investigation of a two-phase, horizontal, stratified, flow regime was performed to determine the interface drag force, and correspondingly, the drag coefficient. A horizontal, stratified flow test facility using water and air was constructed to allow interface shear measurements with PLV techniques. The experimentally obtained local drag measurements were compared with theoretical results given by conventional interfacial drag theory. Close agreement was shown when local conditions near the interface were similar to space-averaged conditions. However, theory based on macroscopic, space-averaged flow behavior was shown to give incorrect results if the local gas velocity near the interface as unstable, transient, and dissimilar from the average gas velocity through the test facility.

  5. An innovative experimental setup for Large Scale Particle Image Velocimetry measurements in riverine environments

    NASA Astrophysics Data System (ADS)

    Tauro, Flavia; Olivieri, Giorgio; Porfiri, Maurizio; Grimaldi, Salvatore

    2014-05-01

    Large Scale Particle Image Velocimetry (LSPIV) is a powerful methodology to nonintrusively monitor surface flows. Its use has been beneficial to the development of rating curves in riverine environments and to map geomorphic features in natural waterways. Typical LSPIV experimental setups rely on the use of mast-mounted cameras for the acquisition of natural stream reaches. Such cameras are installed on stream banks and are angled with respect to the water surface to capture large scale fields of view. Despite its promise and the simplicity of the setup, the practical implementation of LSPIV is affected by several challenges, including the acquisition of ground reference points for image calibration and time-consuming and highly user-assisted procedures to orthorectify images. In this work, we perform LSPIV studies on stream sections in the Aniene and Tiber basins, Italy. To alleviate the limitations of traditional LSPIV implementations, we propose an improved video acquisition setup comprising a telescopic, an inexpensive GoPro Hero 3 video camera, and a system of two lasers. The setup allows for maintaining the camera axis perpendicular to the water surface, thus mitigating uncertainties related to image orthorectification. Further, the mast encases a laser system for remote image calibration, thus allowing for nonintrusively calibrating videos without acquiring ground reference points. We conduct measurements on two different water bodies to outline the performance of the methodology in case of varying flow regimes, illumination conditions, and distribution of surface tracers. Specifically, the Aniene river is characterized by high surface flow velocity, the presence of abundant, homogeneously distributed ripples and water reflections, and a meagre number of buoyant tracers. On the other hand, the Tiber river presents lower surface flows, isolated reflections, and several floating objects. Videos are processed through image-based analyses to correct for lens

  6. Outlier detection for particle image velocimetry data using a locally estimated noise variance

    NASA Astrophysics Data System (ADS)

    Lee, Yong; Yang, Hua; Yin, ZhouPing

    2017-03-01

    This work describes an adaptive spatial variable threshold outlier detection algorithm for raw gridded particle image velocimetry data using a locally estimated noise variance. This method is an iterative procedure, and each iteration is composed of a reference vector field reconstruction step and an outlier detection step. We construct the reference vector field using a weighted adaptive smoothing method (Garcia 2010 Comput. Stat. Data Anal. 54 1167-78), and the weights are determined in the outlier detection step using a modified outlier detector (Ma et al 2014 IEEE Trans. Image Process. 23 1706-21). A hard decision on the final weights of the iteration can produce outlier labels of the field. The technical contribution is that the spatial variable threshold motivation is embedded in the modified outlier detector with a locally estimated noise variance in an iterative framework for the first time. It turns out that a spatial variable threshold is preferable to a single spatial constant threshold in complicated flows such as vortex flows or turbulent flows. Synthetic cellular vortical flows with simulated scattered or clustered outliers are adopted to evaluate the performance of our proposed method in comparison with popular validation approaches. This method also turns out to be beneficial in a real PIV measurement of turbulent flow. The experimental results demonstrated that the proposed method yields the competitive performance in terms of outlier under-detection count and over-detection count. In addition, the outlier detection method is computational efficient and adaptive, requires no user-defined parameters, and corresponding implementations are also provided in supplementary materials.

  7. A Mobile System for Measuring Water Surface Velocities Using Unmanned Aerial Vehicle and Large-Scale Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Chen, Y. L.

    2015-12-01

    Measurement technologies for velocity of river flow are divided into intrusive and nonintrusive methods. Intrusive method requires infield operations. The measuring process of intrusive methods are time consuming, and likely to cause damages of operator and instrument. Nonintrusive methods require fewer operators and can reduce instrument damages from directly attaching to the flow. Nonintrusive measurements may use radar or image velocimetry to measure the velocities at the surface of water flow. The image velocimetry, such as large scale particle image velocimetry (LSPIV) accesses not only the point velocity but the flow velocities in an area simultaneously. Flow properties of an area hold the promise of providing spatially information of flow fields. This study attempts to construct a mobile system UAV-LSPIV by using an unmanned aerial vehicle (UAV) with LSPIV to measure flows in fields. The mobile system consists of a six-rotor UAV helicopter, a Sony nex5T camera, a gimbal, an image transfer device, a ground station and a remote control device. The activate gimbal helps maintain the camera lens orthogonal to the water surface and reduce the extent of images being distorted. The image transfer device can monitor the captured image instantly. The operator controls the UAV by remote control device through ground station and can achieve the flying data such as flying height and GPS coordinate of UAV. The mobile system was then applied to field experiments. The deviation of velocities measured by UAV-LSPIV of field experiments and handhold Acoustic Doppler Velocimeter (ADV) is under 8%. The results of the field experiments suggests that the application of UAV-LSPIV can be effectively applied to surface flow studies.

  8. EDITORIAL: 5th International Symposium on Particle Image Velocimetry, PIV'03

    NASA Astrophysics Data System (ADS)

    Sung, Hyung Jin; Kim, Kyung Chun; Lee, Sang Joon

    2004-06-01

    The advent of particle image velocimetry (PIV) in the late 20th century brought about a paradigm change in the technique of flow field measurement, from point measurement to field measurement. This revolution is a result of the recent advances in computers, video cameras, optics and lasers and a deeper understanding of the theory of image processing, and such advances continue by keeping pace with leading-edge technologies such as biotechnology, nanotechnology and so forth. Recently, the PIV technique has been extended in new directions such as stereoscopic PIV, holographic PIV, dynamic PIV, micro PIV and simultaneous PLIF/PIV techniques. This special issue contains research dealing with many of the most recent developments in PIV. The papers were selected from more than 120 papers presented at the 5th International Symposium on Particle Image Velocimetry (PIV'03) held in Busan, Korea, during 22-24 September 2003. Special thanks are due to the invited speakers who have contributed their original work to this special issue, which will enhance the academic reputation of Measurement Science and Technology (MST). Fourteen papers were selected by the Scientific Committee of PIV'03. After the standard refereeing process of MST, nine papers were finally accepted for publication. The selected papers can be categorized into three groups: new PIV algorithms and evaluation methods, three-dimensional velocity field measurement techniques and micro/bio PIV applications. As a new PIV technique, Lecuona et al introduced PIV evaluation algorithms for industrial applications having high shear flow structures. Billy et al used a single-pixel-based cross-correlation method for measuring flow inside a microchannel. Foucaut et al carried out PIV optimization using spectral analysis for the study of turbulent flows. Doh et al applied a 3D PTV method to the wake behind a sphere using three CCD cameras. Hori and Sakakibara developed a high-speed scanning stereoscopic PIV system and

  9. Stream Discharge Measurement Using A Large-Scale Particle Image Velocimetry Prototype

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Mostaghimi, S.

    2004-12-01

    Good water management is founded on accurate open-channel flow measurements. New technology for measuring discharge in streams and rivers has been pursued due to concerns about safety, accuracy, and costs of traditional methods. Large-Scale Particle Image Velocimetry (LSPIV) is an emerging technology for measuring discharge in streams and rivers. LSPIV is a system capable of measuring velocity fields by collecting and analyzing recorded images of the flow field. The LSPIV system tracks the movement of `tracers' through successive images using statistical correspondence. Cross-correlation algorithms divide the image into small interrogation areas; each producing one displacement vector. The surface velocity field can be used to estimate discharge based on the channel bathymetry. Use of LSPIV for flow measurements in low-order streams has several advantages. LSPIV is not as labor intensive and does not present the safety concerns of the conventional methods during high flow events. Another promise for LSPIV is remote monitoring applications, which could also reduce labor and data management costs. The scheme used in this study for the development of LSPIV follows a logical progression: assimilate current knowledge, develop methods and acquire equipment, conduct laboratory and field experiments for `proof-of-concept', and refine the methods to decrease costs and increase usability. A laboratory prototype was developed and tested in a flume, with good results. The experiment evaluated the LSPIV prototype and a Marsh-McBirney flow meter against the flume manometer. Several conclusions were made from the statistical analysis. The Froude number affects the accuracy of the Marsh-McBirney flow meter and the LSPIV prototype. Therefore, future applications may wish to use an adaptive method to determine input parameters based on flow conditions. The LSPIV prototype produced poor flow measurements at camera angles above a 30 degree oblique angle. Therefore, field applications

  10. Microparticle analysis system and method

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R. (Inventor)

    2007-01-01

    A device for analyzing microparticles is provided which includes a chamber with an inlet and an outlet for respectively introducing and dispensing a flowing fluid comprising microparticles, a light source for providing light through the chamber and a photometer for measuring the intensity of light transmitted through individual microparticles. The device further includes an imaging system for acquiring images of the fluid. In some cases, the device may be configured to identify and determine a quantity of the microparticles within the fluid. Consequently, a method for identifying and tracking microparticles in motion is contemplated herein. The method involves flowing a fluid comprising microparticles in laminar motion through a chamber, transmitting light through the fluid, measuring the intensities of the light transmitted through the microparticles, imaging the fluid a plurality of times and comparing at least some of the intensities of light between different images of the fluid.

  11. Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Squire, D. T.; Morrill-Winter, C.; Hutchins, N.; Marusic, I.; Schultz, M. P.; Klewicki, J. C.

    2016-10-01

    Two particle image velocimetry arrangements are used to make true spatial comparisons between smooth- and rough-wall boundary layers at high Reynolds numbers across a very wide range of streamwise scales. Together, the arrangements resolve scales ranging from motions on the order of the Kolmogorov microscale to those longer than twice the boundary layer thickness. The rough-wall experiments were obtained above a continuous sandpaper sheet, identical to that used by Squire et al. [J. Fluid Mech. 795, 210 (2016), 10.1017/jfm.2016.196], and cover a range of friction and equivalent sand-grain roughness Reynolds numbers (12 000 ≲δ+≲ 18000, 62 ≲ks+≲104 ). The smooth-wall experiments comprise new and previously published data spanning 6500 ≲δ+≲17 000 . Flow statistics from all experiments show similar Reynolds number trends and behaviors to recent, well-resolved hot-wire anemometry measurements above the same rough surface. Comparisons, at matched δ+, between smooth- and rough-wall two-point correlation maps and two-point magnitude-squared coherence maps demonstrate that spatially the outer region of the boundary layer is the same between the two flows. This is apparently true even at wall-normal locations where the total (inner-normalized) energy differs between the smooth and rough wall. Generally, the present results provide strong support for Townsend's [The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, 1956), Vol. 1] wall-similarity hypothesis in high Reynolds number fully rough boundary layer flows.

  12. Stereoscopic particle image velocimetry analysis of healthy and emphysemic alveolar sac models.

    PubMed

    Berg, Emily J; Robinson, Risa J

    2011-06-01

    Emphysema is a progressive lung disease that involves permanent destruction of the alveolar walls. Fluid mechanics in the pulmonary region and how they are altered with the presence of emphysema are not well understood. Much of our understanding of the flow fields occurring in the healthy pulmonary region is based on idealized geometries, and little attention has been paid to emphysemic geometries. The goal of this research was to utilize actual replica lung geometries to gain a better understanding of the mechanisms that govern fluid motion and particle transport in the most distal regions of the lung and to compare the differences that exist between healthy and emphysematous lungs. Excised human healthy and emphysemic lungs were cast, scanned, graphically reconstructed, and used to fabricate clear, hollow, compliant models. Three dimensional flow fields were obtained experimentally using stereoscopic particle image velocimetry techniques for healthy and emphysematic breathing conditions. Measured alveolar velocities ranged over two orders of magnitude from the duct entrance to the wall in both models. Recirculating flow was not found in either the healthy or the emphysematic model, while the average flow rate was three times larger in emphysema as compared to healthy. Diffusion dominated particle flow, which is characteristic in the pulmonary region of the healthy lung, was not seen for emphysema, except for very small particle sizes. Flow speeds dissipated quickly in the healthy lung (60% reduction in 0.25 mm) but not in the emphysematic lung (only 8% reduction 0.25 mm). Alveolar ventilation per unit volume was 30% smaller in emphysema compared to healthy. Destruction of the alveolar walls in emphysema leads to significant differences in flow fields between the healthy and emphysemic lung. Models based on replica geometry provide a useful means to quantify these differences and could ultimately improve our understanding of disease progression.

  13. Field implementation of Particle Image Velocimetry (PIV) for studying flow dynamics at river confluences

    NASA Astrophysics Data System (ADS)

    Lewis, Q. W.; Rhoads, B. L.

    2014-12-01

    The complex hydrodynamics of river confluences have been the focus of numerous investigations over the past several decades. Confluences are locations in river systems characterized by complex patterns of turbulent flow structure, especially within the mixing interface that develops between the two flows. To date, most field investigations of flow structure at stream confluences have been based on point measurements of velocity time series (e.g using ADVs) or on time-averaged data with high spatial resolution, but poor temporal resolution (e.g. using ADCPs). Past approaches have failed to capture the spatial and temporal density of velocity measurements needed to adequately characterize complex turbulent flow structures. In contrast, Particle Image Velocimetry (PIV) has been used successfully in laboratory studies to define in considerable detail the characteristics of turbulent structures. This study uses field-based PIV to characterize surficial flow structure within a small stream confluence. Landscape mulch served as seeding material for the PIV. Particle motion was recorded at a high frame rate using a small action camera mounted above the surface of the flow. Near-surface 3D velocities of flow were measured with an acoustic Doppler velocimeter (ADV) to evaluate velocity data generated by the PIV analysis. Results show that field-based PIV captures nicely complex patterns of fluid motion at the surface of the flow, revealing the two-dimensional characteristics of coherent flow structures. Velocities resulting from the PIV analysis match measured velocities most closely where the flow is least complex and where seeding material remains uniformly distributed throughout the flow. Overall the method appears promising for qualitatively assessing flow structure and for quantifying the size, duration, and vorticity of turbulent structures. Field-based PIV is a valuable technique that can be used along with traditional velocity measurements to more completely and

  14. Holographic particle image velocimetry measurements in a four-valve combustion engine

    NASA Astrophysics Data System (ADS)

    van Overbrüggen, Timo; Dannemann, Jan; Klaas, Michael; Schröder, Wolfgang

    2014-01-01

    This is a feasibility study to show that the nonreacting three-dimensional flow in the cylinder of a four-valve internal combustion engine at 160° after top dead center (atdc) at 1,500 rpm can be accurately measured by holographic particle image velocimetry. The results evidence the quality of holographic PIV measurements in engine flows and the capability of the holographic method to instantaneously capture the complete three-dimensional flow field in a large area of the highly intricate cylinder flow. The resolved measurement volume has a diameter of about 60 mm and a height of 80 mm with a vector spacing of 0.75 mm per vector. To validate the measurements, the flow structure as well as the turbulent kinetic energy of the flow field is compared with planar two-component/two-dimensional (2C/2D-PIV) measurements performed in the same engine (Dannemann et al., in Exp Fluids 2010). Furthermore, the spatial propagation of the flow field as well as the vortical structures is visualized by 3D streamlines and λ 2-contours. The current results confirm the existence of several large-scale flow structures, such as a counter-rotating ring-vortex pair below the inlet valve and the tumble vortex. The latter possesses a U-shaped propagation of the vortex core. The analysis of the two-point correlation shows the integral length scale to be in the range 2.5-6.1 mm, which is in agreement with literature data.

  15. Intensity Enhanced Cerenkov Luminescence Imaging Using Terbium-Doped Gd2O2S Microparticles.

    PubMed

    Cao, Xin; Chen, Xueli; Kang, Fei; Zhan, Yonghua; Cao, Xu; Wang, Jing; Liang, Jimin; Tian, Jie

    2015-06-10

    Weak intensity and poor penetration depth are two big obstacles toward clinical use of Cerenkov luminescence imaging (CLI). In this proof-of-concept study, we overcame these limitations by using lanthanides-based radioluminescent microparticles (RLMPs), called terbium doped Gd2O2S. The characterization experiment showed that the emission excited by Cerenkov luminescence can be neglected whereas the spectrum experiment demonstrated that the RLMPs can actually be excited by γ-rays. A series of in vitro experiments demonstrated that RLMPs significantly improve the intensity and the penetration capacity of CLI, which has been extended to as deep as 15 mm. In vivo pseudotumor study further prove the huge potential of this enhancement strategy for Cerenkov luminescence imaging in living animal studies.

  16. Velocity field measurements of valvular blood flow in a human superficial vein using high-frequency ultrasound speckle image velocimetry.

    PubMed

    Nam, Kweon-Ho; Yeom, Eunseop; Ha, Hojin; Lee, Sang-Joon

    2012-01-01

    This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.

  17. Particle Imaging Velocimetry Technique Development for Laboratory Measurement of Fracture Flow Inside a Pressure Vessel Using Neutron Imaging

    SciTech Connect

    Polsky, Yarom; Bingham, Philip R; Bilheux, Hassina Z; Carmichael, Justin R

    2015-01-01

    This paper will describe recent progress made in developing neutron imaging based particle imaging velocimetry techniques for visualizing and quantifying flow structure through a high pressure flow cell with high temperature capability (up to 350 degrees C). This experimental capability has great potential for improving the understanding of flow through fractured systems in applications such as enhanced geothermal systems (EGS). For example, flow structure measurement can be used to develop and validate single phase flow models used for simulation, experimentally identify critical transition regions and their dependence on fracture features such as surface roughness, and study multiphase fluid behavior within fractured systems. The developed method involves the controlled injection of a high contrast fluid into a water flow stream to produce droplets that can be tracked using neutron radiography. A description of the experimental setup will be provided along with an overview of the algorithms used to automatically track droplets and relate them to the velocity gradient in the flow stream. Experimental results will be reported along with volume of fluids based simulation techniques used to model observed flow.

  18. Kilohertz cinematographic particle image velocimetry measurements of turbulent flow past a shallow cavity

    NASA Astrophysics Data System (ADS)

    Bian, Shiyao

    High Reynolds number, low Mach number, turbulent shear flow past a rectangular, shallow cavity has been experimentally investigated using a digital dual-camera Cinematographic Particle Image Velocimetry (CPIV) system which has been developed to provide time-resolved, high resolution flow measurements. Two high-speed cameras were optically combined to acquire double-pulsed CPIV images at kilohertz frame rates. Bias and random errors due to camera misalignment, camera vibration, and lens aberration were corrected. An overall uncertainty of +/-6% has been estimated for the stream-wise velocity component and +/-10% for the cross-stream velocity component. The CPIV technique has made it possible to examine the dynamics of coherent structures and the vortex impingement process in this quasi-periodic flow. The time-averaged flow properties agree well with previous cavity flow studies. Mean velocity profiles and turbulent statistics of the separated shear layer are also similar to those of a free mixing layer. Time histories of the flow field reveal that coherent vortical structures were formed near the leading corner of the cavity and they travel with the shear layer at a convection speed close to half of the freestream velocity. The cross-correlation contours of vorticity also reveal the three-dimensional motion and breakup of the large-scale structures. Non-dimensional frequencies in the cavity shear layer correspond to the vortex roll-up frequency predicted using the linear, inviscid instability theory. No self-sustained oscillations were observed for the present cavity flow configurations. The power spectra of the vertical velocity fluctuations suggest that the downstream cross-stream fluctuations of the shear layer are amplified due to the periodic stagnation of the stream-wise flow at the cavity trailing edge. The mixing rate between the flow within cavity and the freestream computed from current CPIV data using one-dimensional mixing model is found to be three

  19. Combining UAV and high-resolution image-based particle image velocimetry to monitor flow in lakes and rivers

    NASA Astrophysics Data System (ADS)

    Blois, G.; Best, J.; Christensen, K. T.; Kennedy, A. B.; Donahue, A. S.; Hovakimyan, N.; Cichella, V.; Pakrasi, I.

    2015-12-01

    Unmanned aerial vehicles (UAV) are increasingly being applied by the geophysical community for large-scale surveys of environments that are challenging to reach (e.g. volcanoes, glaciers). Some of these natural systems include large bodies of water such as oceans, lakes and rivers. These environments are highly dynamic and, even in normal conditions, their characterization requires long surveys involving the deployment of expensive equipment and large crews. Technical challenges, and thus costs, become prohibitive especially during extreme natural events that may pose a threat not only to the monitoring facilities but, more importantly, to the surrounding residential areas (e.g. river flooding, extreme waves). Traditional measurement techniques have difficulty or are unable to monitor some flow quantities (i.e. flow discharge and wave energy content) associated with these natural systems, especially during emergencies. Extreme hydrodynamic loads due to high flow discharges and/or highly energetic waves may tamper with traditional monitoring systems that are typically submerged or fixed in the vicinity of the water body. Here, we propose to employ specially developed UAV systems to remotely and safely gain high-resolution images of the water surface. Such images are processed using robust large-scale particle image velocimetry (LSPIV) algorithms that are able to accurately resolve the complex two-dimensional flow field of the water surface over extensive areas. These systems can theoretically be deployed in a cost-effective way for long periods of time for continuous monitoring. Such monitoring is key to inform and calibrate predictive tools that can reconstruct potential emergency scenarios. In addition, during extreme natural events, data can be collected with no risk to human operators. Here, we discuss the concept and technology employed to render these measurement systems effective, and provide examples of applications that show the depth of the data that can

  20. Planar particle/droplet size measurement technique using digital particle image velocimetry image data

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P. (Inventor); Mielke, Amy F. (Inventor); Kadambi, Jaikrishnan R. (Inventor)

    2005-01-01

    A method for determining a mass flux of an entrained phase in a planar two-phase flow records images of particles in the two-phase flow. Respective sizes of the particles (the entrained phase) are determined as a function of a separation between spots identified on the particle images. Respective velocities of the particles are determined. The mass flux of the entrained phase is determined as a function of the size and velocity of the particles.

  1. A new experiment to measure shocked particle drag using multi-pulse particle image velocimetry and particle tracking

    NASA Astrophysics Data System (ADS)

    Martinez, Adam A.; Orlicz, Gregory C.; Prestridge, Katherine P.

    2015-01-01

    We demonstrate the measurement capabilities for a new horizontal shock tube facility designed to measure the displacements, velocities and accelerations of shock-accelerated particles just after shock passage. Eight-frame particle image accelerometry and particle tracking velocimetry accelerometry diagnostics are implemented, along with a shadowgraphy system for measuring the shock location during experiments. We demonstrate the driving conditions of the facility using a unique membraneless pneumatic driver and particle seeding system that can accommodate both solid and liquid particles in the carrier phase. Measurements of two types of solid particles show unsteady drag forces higher than those for steady drag.

  2. Computational fluid dynamics and digital particle image velocimetry study of the flow through an optimized micro-axial blood pump.

    PubMed

    Triep, Michael; Brücker, Christoph; Schröder, Wolfgang; Siess, Thorsten

    2006-05-01

    A detailed knowledge of the flow field in a blood pump is indispensable in order to increase the efficiency of the pump and to reduce the shear-induced hemolysis. Thus, three different impeller designs were developed and tested by means of computational fluid dynamics (CFD) and digital particle image velocimetry (DPIV). The results show a good agreement of CFD and DPIV data. An optimization of the impeller could be achieved by following the concept of turbulent drag reduction for the axisymmetric center body.

  3. Subscale Ship Airwake Studies Using Novel Vortex Flow Devices with Smoke, Laser-Vapor-Screen and Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Lamar, John E.; Landman, Drew; Swift, Russell S.; Parikh, Paresh C.

    2007-01-01

    Ships produce vortices and air-wakes while either underway or stationary in a wind. These flow fields can be detrimental to the conduction of air operations in that they can adversely impact the air vehicles and flight crews. There are potential solutions to these problems for both frigates/destroyers and carriers through the use of novel vortex flow or flow control devices. This appendix highlights several devices which may have application and points out that traditional wind-tunnel testing using smoke, laser-vapor screen, and Particle Image Velocimetry can be useful in sorting out the effectiveness of different devices.

  4. Time Resolved Particle Image Velocimetry Techniques with Continuous Wave Laser and their Application to Transient Flows

    NASA Astrophysics Data System (ADS)

    Esposito, Chiara

    The demand to increase the temporal resolution of Stereo-Particle Image Velocimetry systems used in the measurement of highly unsteady flow fields is limited by the low repetition rate of the pulse lasers and cameras. The availability of high-frame-rate digital cameras and CW lasers opens new possibilities in the development of continuous PIV systems with increased temporal resolution. Time-Resolved Particle Image Velocimetry (TR-PIV) with continuous wave (CW) laser sheet technique and a high frame-rate camera is introduced here to be used in gas flows at low to moderate Reynolds numbers. This experimental technique can measure velocity of the flow in a planar field with good spatial and temporal resolution. Additional modifications led to the development of a Split view TR-PIV system capable of resolving three-component velocity fields. The optical setup consists of a single high-frame-rate camera which can accommodate two simultaneous stereo view images of the deforming fluid on its CMOS chip obtained by using four different planar mirrors, appropriately positioned. This approach offers several advantages over traditional systems with two different cameras. First, it provides identical system parameters for the two views which minimize their differences and thus facilitating robust stereo matching. Second, it reduces calibration time since only one camera is used and third its cost is substantially lower than the cost of a system with two cameras. The TR-PIV with the CW laser technique has been evaluated in canonical turbulent boundary layer flows and the results were compared to data from the vast literature. Particular attention has been given to the performance of the system components, such as the high speed cameras, and the CW lasers. The techniques were also investigated in terms of the duration of exposure of PIV images. The effect of the duration of exposure was proven to be particularly important, and it has a negative effect for the case with higher

  5. Dynamics of supersonic microparticle impact on elastomers revealed by real-time multi-frame imaging.

    PubMed

    Veysset, David; Hsieh, Alex J; Kooi, Steven; Maznev, Alexei A; Masser, Kevin A; Nelson, Keith A

    2016-05-09

    Understanding high-velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post-mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real-time multi-frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700-900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high-velocity impact.

  6. Dynamics of supersonic microparticle impact on elastomers revealed by real–time multi–frame imaging

    PubMed Central

    Veysset, David; Hsieh, Alex J.; Kooi, Steven; Maznev, Alexei A.; Masser, Kevin A.; Nelson, Keith A.

    2016-01-01

    Understanding high–velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post–mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real–time multi–frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700–900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high–velocity impact. PMID:27156501

  7. Dynamics of supersonic microparticle impact on elastomers revealed by real–time multi–frame imaging

    NASA Astrophysics Data System (ADS)

    Veysset, David; Hsieh, Alex J.; Kooi, Steven; Maznev, Alexei A.; Masser, Kevin A.; Nelson, Keith A.

    2016-05-01

    Understanding high–velocity microparticle impact is essential for many fields, from space exploration to medicine and biology. Investigations of microscale impact have hitherto been limited to post–mortem analysis of impacted specimens, which does not provide direct information on the impact dynamics. Here we report real–time multi–frame imaging studies of the impact of 7 μm diameter glass spheres traveling at 700–900 m/s on elastomer polymers. With a poly(urethane urea) (PUU) sample, we observe a hyperelastic impact phenomenon not seen on the macroscale: a microsphere undergoes a full conformal penetration into the specimen followed by a rebound which leaves the specimen unscathed. The results challenge the established interpretation of the behaviour of elastomers under high–velocity impact.

  8. The aerodynamics of Manduca sexta: digital particle image velocimetry analysis of the leading-edge vortex.

    PubMed

    Bomphrey, Richard J; Lawson, Nicholas J; Harding, Nicholas J; Taylor, Graham K; Thomas, Adrian L R

    2005-03-01

    Here we present the first digital particle image velocimetry (DPIV) analysis of the flow field around the wings of an insect (the tobacco hawkmoth Manduca sexta, tethered to a 6-component force-moment balance in a wind tunnel). A leading-edge vortex (LEV) is present above the wings towards the end of the downstroke, as the net upward force peaks. Our DPIV analyses and smoke visualisations match the results of previous flow visualisation experiments at midwing, and we extend the experiments to provide the first analysis of the flow field above the thorax. Detailed DPIV measurements show that towards the end of the downstroke, the LEV structure is consistent with that recently reported in free-flying butterflies and dragonflies: the LEV is continuous across the thorax and runs along each wing to the wingtip, where it inflects to form the wingtip trailing vortices. The LEV core is 2-3 mm in diameter (approximately 10% of local wing chord) both at the midwing position and over the centreline at 1.2 m s(-1) and at 3.5 m s(-1) flight speeds. At 1.2 m s(-1) the measured LEV circulation is 0.012+/-0.001 m(2) s(-1) (mean +/-S.D.) at the centreline and 0.011+/-0.001 m(2) s(-1) halfway along the wing. At 3.5 m s(-1) LEV circulation is 0.011+/-0.001 m(2) s(-1) at the centreline and 0.020+/-0.004 m(2) s(-1) at midwing. The DPIV measurements suggest that if there is any spanwise flow in the LEV towards the end of the downstroke its velocity is less than 1 m s(-1). Estimates of force production show that the LEV contributes significantly to supporting body weight during bouts of flight at both speeds (more than 10% of body weight at 1.2 m s(-1) and 35-65% of body weight at 3.5 m s(-1)).

  9. Pulsatile flow in the aorta of the LVAD supported heart studied using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Moyedi, Zahra

    Currently many patients die because of the end-stage heart failure, mainly due to the reduced number of donor heart transplant organs. Studies show that a permanent left ventricular assist device (LVAD), a battery driven pump which is surgically implanted, increased the survival rate of patients with end-stage heart failure and improved considerably their quality of life. The inlet conduit of the LVAD is attached to the left ventricle and the outflow conduit anastomosed to the ascending aorta. The purpose of LVAD support is to help a weakened heart to pump blood to the rest of the body. However LVAD can cause some alterations of the natural blood flow. When your blood comes in contact with something that isn't a natural part of your body blood clots can occur and disrupt blood flow. Aortic valve integrity is vital for optimal support of left ventricular assist LVAD. Due to the existence of high continuous transvalvular pressure on the aortic valve, the opening frequency of the valve is reduced. To prevent the development of aortic insufficiency, aortic valve closure during LVAD implantation has been performed. However, the closed aortic valve reduces wash out of the aortic root, which causes blood stagnation and potential thrombus formation. So for this reason, there is a need to minimize the risks of occurring blood clot, by having more knowledge about the flow structure in the aorta during LVAD use. The current study focuses on measuring the flow field in the aorta of the LVAD assisted heart with two different types of aortic valve (Flat and Finned) using the SDSU cardiac simulator. The pulsatile pump that mimics the natural pulsing action of the heart also added to the system. The flow field is visualized using Particle Image Velocimetry (PIV). Furthermore, The fluid mechanics of aorta has been studied when LVAD conduit attached to two different locations (proximal and distal to the aortic valve) with pump speeds of 8,000 to 10,000 revolutions per minute (RPM

  10. Application of Particle Image Velocimetry to a Study of Flow About a Multi-Element Airfoil

    NASA Technical Reports Server (NTRS)

    Walker, Stephen M.; Baganoff, Donald

    1996-01-01

    An experiment was performed on the flap tip vortex shed from a half span Fowler flap. This flap was mounted on a 5 foot span NACA 63(2)-215 Mod B airfoil in the 7 by 10 foot wind tunnel at NASA Ames Research Center. Several noise reduction studies were performed with this model, and the addition of the Particle Image Velocimetry (PIV) research discussed here served as a proof case of large scale PIV. The measurement plane investigated here was a cross plane region. This is cross plane relative to the freestream flow direction. The measurement plane was located at a position 18 inches downstream of the flap trailing edge. This served to prove that measurements could also be made in the more difficult cross plane direction rather than in the downstream flow direction. Lastly the PIV data was used as a practical research tool that yielded important results that could not otherwise be obtained. The flow field area measured was 40 cm by 40 cm square, and served to characterize the downstream flow characteristics of the flap tip vortex under three configurations: the baseline configuration which was the flap and the wing only; the baseline with the addition of a 3/4 span slat; and the baseline with a Flap Edge Device which was designed to reduce the noise generated at the flap. All configurations were tested at a freestream velocity of 64.84 m/s. The test resulted in average velocity fields for the three configurations tested. The velocity fields aided in verifying other testing methods on this particular experiment, and also yielded further insight into the characteristics of the flap tip vortex under the three configurations considered. The velocity data was reduced, and we were able to calculate the vorticity of the flow field. From the position of minimum vorticity the location of the center of the vortex was determined. The circulation was also calculated and aided in comparing the effects of the three configurations on the lifting characteristics of the flap.

  11. Sensitivity study of large-scale particle image velocimetry measurement of river discharge using numerical simulation

    NASA Astrophysics Data System (ADS)

    Hauet, Alexandre; Creutin, Jean-Dominique; Belleudy, Philippe

    2008-01-01

    SummaryThis study deals with the uncertainty of large-scale particle image velocimetry (LSPIV) measurements in rivers. LSPIV belongs to the methods of local remote sensing of rivers, like Radar- and Lidar-based techniques. These methods have many potential advantages, in comparison with classical river gauging, but they have a fundamental drawback: they are indirect measurements. As such they need to be assessed in reference to direct measurements. A first validation method consists in the comparison of LSPIV measurements with classic gauging results, in field and laboratory experiments. Unfortunately, in both cases, it is impossible in practice to control all the parameters and to distinguish the impact of the various error sources. In the present study we propose a more theoretical assessment of LSPIV potential through numerical simulation. The idea is simply to mathematically formulate the present state of knowledge of the measurement including both the physics of the phenomenon (the illuminated river) and the physics of the sensor (the camera and the PIV tracking). The dilemma about when to start this type of simulation is the following: The simulation is satisfactory if we can validate it which means to be able to compare simulations and observations over a wide range of conditions. The simulation is useful to get preliminary insights about the most important measurement conditions to organize validation studies. Our simulator is composed of three blocks: The river block represents the unidirectional river flow by the association of the EDM model and a theoretical vertical velocity profile giving a 3D velocity distribution. This hydraulic model is complemented by features representing free surface tracers, the illumination of the free-surface (shadows and sun reflection) and the effect of the wind. The camera block transforms the river state parameters into raster images according to the intrinsic and extrinsic parameters of the camera. The LSPIV analysis

  12. Insights Into Sill Formation Processes From Particle Image Velocimetry (PIV) Analysis of Layered Elastic Media Experiments

    NASA Astrophysics Data System (ADS)

    Kavanagh, J. L.; Boutelier, D. A.; Cruden, A. R.

    2012-12-01

    A key issue in magma intrusion mechanics is constraining the conditions required to initiate sill formation from feeder dykes. To investigate these processes, we present a series of layered gelatine analogue experiments monitored with a Particle Image Velocimetry (PIV) system to document the fluid dynamics in the magma and small-scale deformation processes in the host material as a sill is formed along a weak contact beneath a more rigid layer. Gelatine is a good crustal analogue material to study the dynamics of dyke and sill propagation in the crust. Although gelatine is viscoelastic, tests carried out using a rheometer show that at experimental conditions the gelatine behaves as an almost ideal elastic material at 5-10 °C. Forty litres of hot liquid gelatine is poured into a clear-perspex tank and left to solidify in a fridge at ~5 °C. Experiments are prepared comprising multiple layers, with small strength contrasts (comparable to those between crustal strata) created by varying the gelatine concentration and allowing sufficient time for it to reach the plateau Young's modulus. Both strong and weak interface strengths are investigated by varying the extent of welding between the layers. Injection of dyed water (the magma analogue) into the solid gelatine from below causes a penny-shaped experimental dyke to form. With a constant driving pressure, the propagating experimental dyke becomes arrested beneath a more rigid layer if the Young's modulus contrast is greater than 12%. In the case of a weak interface, a sill is formed by intrusion along the contact between the layers; if the interface is strong a blade-like dyke forms. To monitor displacements within the gelatine using the PIV technique, neutrally buoyant polyamide reflective particles are added to the gelatine during experiment preparation. Two high-speed cameras are positioned outside the tank in a plane perpendicular to the strike of the experimental feeder dyke, and parallel to a high-power laser

  13. Imaging System for Extending Evanescent-Wave Particle Velocimetry to Wall Turbulence

    DTIC Science & Technology

    2014-11-17

    based particle?tracking velocimetry (PTV) technique to visualize a “slice” of the viscous sublayer in wall turbulence parallel to the wall in fully...developed turbulent channel flow. Understanding the characteristics of wall (?bounded) turbulence, especially in the viscous sublayer, i.e., the thin...flow region next to the wall where viscous effects dominate, is the key to understanding the drag and lift forces 1. REPORT DATE (DD-MM-YYYY) 4. TITLE

  14. Stereo Imaging Velocimetry of Mixing Driven by Buoyancy Induced Flow Fields

    NASA Technical Reports Server (NTRS)

    Duval, W. M. B.; Jacqmin, D.; Bomani, B. M.; Alexander, I. J.; Kassemi, M.; Batur, C.; Tryggvason, B. V.; Lyubimov, D. V.; Lyubimova, T. P.

    2000-01-01

    Mixing of two fluids generated by steady and particularly g-jitter acceleration is fundamental towards the understanding of transport phenomena in a microgravity environment. We propose to carry out flight and ground-based experiments to quantify flow fields due to g-jitter type of accelerations using Stereo Imaging Velocimetry (SIV), and measure the concentration field using laser fluorescence. The understanding of the effects of g-jitter on transport phenomena is of great practical interest to the microgravity community and impacts the design of experiments for the Space Shuttle as well as the International Space Station. The aim of our proposed research is to provide quantitative data to the community on the effects of g-jitter on flow fields due to mixing induced by buoyancy forces. The fundamental phenomenon of mixing occurs in a broad range of materials processing encompassing the growth of opto-electronic materials and semiconductors, (by directional freezing and physical vapor transport), to solution and protein crystal growth. In materials processing of these systems, crystal homogeneity, which is affected by the solutal field distribution, is one of the major issues. The understanding of fluid mixing driven by buoyancy forces, besides its importance as a topic in fundamental science, can contribute towards the understanding of how solutal fields behave under various body forces. The body forces of interest are steady acceleration and g-jitter acceleration as in a Space Shuttle environment or the International Space Station. Since control of the body force is important, the flight experiment will be carried out on a tunable microgravity vibration isolation mount, which will permit us to precisely input the desired forcing function to simulate a range of body forces. To that end, we propose to design a flight experiment that can only be carried out under microgravity conditions to fully exploit the effects of various body forces on fluid mixing. Recent

  15. Application of Digital Ultrasound Speckle Image Velocimetry(DUSIV) for Quantitative Flow Measurements in Aortic Vessel- an In Vitro Study

    NASA Astrophysics Data System (ADS)

    Zarandi, Mehrdad; Dabiri, Dana; Gharib, Morteza

    2001-11-01

    A new method is developed to use speckle signals for obtaining quantitative information about the flow field and its related properties such as wall shear stress. Speckle imaging allows for mapping flows at normal angles to the probe where Doppler technique render little information. Our custom developed method of Digital Ultrasound Speckle Image Velocimetry is used to measure the flow field and wall shear stress in a model of aortic vessel. The method has great potential for other applications such as flow in curved vessels, branching vessels, heart chambers and through valves for quantitative blood flow measurements. It also allows us to correct for the errors in ultrasound measurements caused by the angle of interrogation , or signal attenuation with distance from the ultrasound probe. Speckle velocimetry also allows calibration of the results obtained from the conventional Doppler shift based ultrasound methods and should therefore contribute to more accurate quantitative measurements of blood flow by ultrasound. Providing quantitative information with much higher resolution than Color Doppler measurements and applicability to optically inaccessible flows are the other advantages of this method.

  16. Tip-Clearance Vortex Characterized With Three-Dimensional Digital Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    John, W. Trevor

    2002-01-01

    An optical measurement technique known as Three-Dimensional Digital Particle Image Velocimetry (3-D DPIV) was used to characterize the tip clearance flow in NASA Glenn Research Center's low-speed axial compressor. 3-D DPIV is a technique in which a stereoscopic imaging system consisting of two cross-correlation cameras is used to record particles entrained in a flow as a laser light sheet is pulsed at two instances in time. Although 3-D DPIV has been used elsewhere, this is the first time it has been used to measure compressor tip clearance flows. In-house modifications of the DPIV system include the use of effective seeding technology and a novel system to perform a priori calibrations at all five measurement planes, greatly reducing facility run time. Computational fluid dynamics predictions, which are used to guide design changes toward improving the efficiency and operating range of turbomachinery, can be verified and improved by comparison with 3-D DPIV measurements of the actual tip clearance flow. This measurement campaign dealt with the characterization of the tip clearance vortex in the first stage of a four-stage axial compressor. The tip clearance vortex is formed in compressors operating with a clearance gap between the moving rotor blade tips and the stationary casing when a leakage flow, forced from the pressure side of the blade over the blade tip, forms a vortical structure on the suction side of the blade. 3-D DPIV is ideally suited to measure the clearance vortex for two reasons: (1) this technique captures the entire blade passage flow at one instant in time, so that wandering of the vortex during the measurement does not smear out velocity gradients in the flow field, and (2) the spanwise component of velocity changes sign across the vortex core, providing a more accurate measurement of the vortex location than was available with previous two-dimensional measurement approaches. These two attributes of the data will enable computational fluid

  17. A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

    SciTech Connect

    Zha, Kan; Busch, Stephen; Park, Cheolwoong; Miles, Paul C.

    2016-06-24

    In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. Here, to ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortion quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.

  18. A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

    DOE PAGES

    Zha, Kan; Busch, Stephen; Park, Cheolwoong; ...

    2016-06-24

    In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. Here, to ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortionmore » quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.« less

  19. The development of laser speckle or particle image displacement velocimetry. Part 1: The role of photographic parameters

    NASA Technical Reports Server (NTRS)

    Lourenco, L. M. M.; Krothapalli, A.

    1987-01-01

    One of the difficult problems in experimental fluid dynamics remains the determination of the vorticity field in fluid flows. Recently, a novel velocity measurement technique, commonly known as Laser Speckle or Particle Image Displacement Velocimetry became available. This technique permits the simultaneous visualization of the 2 dimensional streamline pattern in unsteady flows and the quantification of the velocity field. The main advantage of this new technique is that the whole 2 dimensional velocity field can be recorded with great accuracy and spatial resolution, from which the instantaneous vorticity field can be easily obtained. A apparatus used for taking particle displacement images is described. Local coherent illumination by the probe laser beam yielded Young's fringes of good quality at almost every location of the flow field. These fringes were analyzed and the velocity and vorticity fields were derived. Several conclusions drawn are discussed.

  20. Magnetic Resonance Imaging of Atherosclerosis Using CD81-Targeted Microparticles of Iron Oxide in Mice

    PubMed Central

    Yan, Fei; Yang, Wei; Li, Xiang; Liu, Hongmei; Nan, Xiang; Xie, Lisi; Zhou, Dongliang; Xie, Guoxi; Wu, Junru; Qiu, Bensheng; Liu, Xin; Zheng, Hairong

    2015-01-01

    The goal of this study is to investigate the feasibility of using CD81- (Cluster of Differentiation 81 protein-) targeted microparticles of iron oxide (CD81-MPIO) for magnetic resonance imaging (MRI) of the murine atherosclerosis. CD81-MPIO and IgG- (Immunoglobulin G-) MPIO were prepared by covalently conjugating, respectively, with anti-CD81 monoclonal and IgG antibodies to the surface of the tosyl activated MPIO. The relevant binding capability of the MPIO was examined by incubating them with murine bEnd.3 cells stimulated with phenazine methosulfate (PMS) and its effect in shortening T2 relaxation time was also examined. MRI in apolipoprotein E-deficient mice was studied in vivo. Our results show that CD81-MPIO, but not IgG-MPIO, can bind to the PMS-stimulated bEnd.3 cells. The T2 relaxation time was significantly shortened for stimulated bEnd.3 cells when compared with IgG-MPIO. In vivo MRI in apolipoprotein E-deficient mice showed highly conspicuous areas of low signal after CD81-MPIO injection. Quantitative analysis of the area of CD81-MPIO contrast effects showed 8.96- and 6.98-fold increase in comparison with IgG-MPIO or plain MPIO, respectively (P < 0.01). Histological assay confirmed the expression of CD81 and CD81-MPIO binding onto atherosclerotic lesions. In conclusion, CD81-MPIO allows molecular assessment of murine atherosclerotic lesions by magnetic resonance imaging. PMID:26266263

  1. Real-time imaging of microparticles and living cells with CMOS nanocapacitor arrays

    NASA Astrophysics Data System (ADS)

    Laborde, C.; Pittino, F.; Verhoeven, H. A.; Lemay, S. G.; Selmi, L.; Jongsma, M. A.; Widdershoven, F. P.

    2015-09-01

    Platforms that offer massively parallel, label-free biosensing can, in principle, be created by combining all-electrical detection with low-cost integrated circuits. Examples include field-effect transistor arrays, which are used for mapping neuronal signals and sequencing DNA. Despite these successes, however, bioelectronics has so far failed to deliver a broadly applicable biosensing platform. This is due, in part, to the fact that d.c. or low-frequency signals cannot be used to probe beyond the electrical double layer formed by screening salt ions, which means that under physiological conditions the sensing of a target analyte located even a short distance from the sensor (∼1 nm) is severely hampered. Here, we show that high-frequency impedance spectroscopy can be used to detect and image microparticles and living cells under physiological salt conditions. Our assay employs a large-scale, high-density array of nanoelectrodes integrated with CMOS electronics on a single chip and the sensor response depends on the electrical properties of the analyte, allowing impedance-based fingerprinting. With our platform, we image the dynamic attachment and micromotion of BEAS, THP1 and MCF7 cancer cell lines in real time at submicrometre resolution in growth medium, demonstrating the potential of the platform for label/tracer-free high-throughput screening of anti-tumour drug candidates.

  2. Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.

    PubMed

    Shi, Yubing; Yeo, Tony Joon Hock; Zhao, Yong; Hwang, Ned H C

    2006-12-01

    Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital PIV (DPIV) investigation was carried out with improved accuracy, to analyse the pulsatile flow field around the bi-leaflet mechanical heart valve (MHV) in a complete heart cycle. For this purpose a pulsatile flow test rig was constructed to provide the necessary in vitro test environment, and the flow field around a St. Jude size 29 bi-leaflet MHV and a similar MHV model were studied under a simulated physiological pressure waveform with flow rate of 5.2 l/min and pulse rate at 72 beats/min. A phase-locking method was applied to gate the dynamic process of valve leaflet motions. A special image-processing program was applied to eliminate optical distortion caused by the difference in refractive indexes between the blood analogue fluid and the test section. Results clearly showed that, due to the presence of the two leaflets, the valvular flow conduit was partitioned into three flow channels. In the opening process, flow in the two side channels was first to develop under the presence of the forward pressure gradient. The flow in the central channel was developed much later at about the mid-stage of the opening process. Forward flows in all three channels were observed at the late stage of the opening process. At the early closing process, a backward flow developed first in the central channel. Under the influence of the reverse pressure gradient, the flow in the central channel first appeared to be disturbed, which was then transformed into backward flow. The backward flow in the central channel was found to be the main driving factor for the leaflet rotation in the valve

  3. An application of particle image velocimetry to the direct measurement of laminar burning velocity in homogeneous propane-air mixtures

    SciTech Connect

    Zhou, M.; Garner, C.P.

    1995-12-31

    An experiment is described for the direct measurement of laminar burning velocity within an optically accessed cylindrical combustion chamber. The laminar burning velocity was determined directly as the difference between the flame propagation speed and the unburned gas velocity immediately ahead of the flame front. Particle Image Velocimetry (PIV) has been applied to measure the unburned gas velocity field. The local flame speed and flame front position were determined from a pair of ionization probes in conjunction with the simultaneous PIV measurement. The laminar burning velocity of propane-air mixtures initially at atmospheric condition for different equivalence ratios ranging from 0.7--1.4 are presented. Close agreement with other measurements and predicted results was found.

  4. Boundary layer development over a large array of porous-disk-modeled wind turbines via stereo particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Camp, Elizabeth; Vuppuluri, Vasant; Cal, Raúl

    2014-11-01

    The increasing size of wind turbine arrays in service highlights the importance of understanding the flow physics within such large turbine arrays. Thus, the development of a wind turbine array boundary layer (WTBL) was investigated experimentally for an 8 × 5 array of model wind turbines. Model wind turbines were on a 1:2000 scale and turbine rotors were represented by porous disks. Stereoscopic Particle Image Velocimetry (SPIV) measurements were done along the centerline of the wind turbine array at several streamwise positions both within and above the canopy. Measurements and analysis of the mean and streamwise-averaged statistics of the SPIV fields focus on the rotors in the furthest downstream positions. Statistics will be used to determine if a fully developed WTBL has been achieved.

  5. Experimental study of limit lean methane/air flame in a standard flammability tube using particle image velocimetry method

    SciTech Connect

    Shoshin, Yuriy; Gorecki, Grzegorz; Jarosinski, Jozef; Fodemski, Tadeusz

    2010-05-15

    Lean limit methane/air flame propagating upward in a standard 50 mm diameter and 1.8 m length tube was studied experimentally using particle image velocimetry method. Local stretch rate along the flame front was determined by measured gas velocity distributions. It was found that local stretch rate is maximum at the flame leading point, which is in agreement with earlier theoretical results. Similar to earlier observations, extinction of upward propagating limit flame was observed to start from the flame top. It is stated that the observed behavior of the extinction of the lean limit methane/air flame can not be explained in terms of the coupled effect of flame stretch and preferential diffusion. To qualitatively explain the observed extinction behavior, it is suggested that the positive strain-induced flame stretch increases local radiation heat losses from the flame front. An experimental methodology for PIV measurements in a round tube is described. (author)

  6. Experimental investigation of the dynamics of a hybrid morphing wing: time resolved particle image velocimetry and force measures

    NASA Astrophysics Data System (ADS)

    Jodin, Gurvan; Scheller, Johannes; Rouchon, Jean-François; Braza, Marianna; Mit Collaboration; Imft Collaboration; Laplace Collaboration

    2016-11-01

    A quantitative characterization of the effects obtained by high frequency-low amplitude trailing edge actuation is performed. Particle image velocimetry, as well as pressure and aerodynamic force measurements, are carried out on an airfoil model. This hybrid morphing wing model is equipped with both trailing edge piezoelectric-actuators and camber control shape memory alloy actuators. It will be shown that this actuation allows for an effective manipulation of the wake turbulent structures. Frequency domain analysis and proper orthogonal decomposition show that proper actuating reduces the energy dissipation by favoring more coherent vortical structures. This modification in the airflow dynamics eventually allows for a tapering of the wake thickness compared to the baseline configuration. Hence, drag reductions relative to the non-actuated trailing edge configuration are observed. Massachusetts Institute of Technology.

  7. A synchronized particle image velocimetry and infrared thermography technique applied to convective mass transfer in champagne glasses

    NASA Astrophysics Data System (ADS)

    Beaumont, Fabien; Liger-Belair, Gérard; Bailly, Yannick; Polidori, Guillaume

    2016-05-01

    In champagne glasses, it was recently suggested that ascending bubble-driven flow patterns should be involved in the release of gaseous carbon dioxide (CO2) and volatile organic compounds. A key assumption was that the higher the velocity of the upward bubble-driven flow patterns in the liquid phase, the higher the volume fluxes of gaseous CO2 desorbing from the supersaturated liquid phase. In the present work, simultaneous monitoring of bubble-driven flow patterns within champagne glasses and gaseous CO2 escaping above the champagne surface was performed, through particle image velocimetry and infrared thermography techniques. Two quite emblematic types of champagne drinking vessels were investigated, namely a long-stemmed flute and a wide coupe. The synchronized use of both techniques proved that the cloud of gaseous CO2 escaping above champagne glasses strongly depends on the mixing flow patterns found in the liquid phase below.

  8. The role of photographic parameters in laser speckle or particle image displacement velocimetry

    NASA Technical Reports Server (NTRS)

    Lourenco, L.; Krothapalli, A.

    1987-01-01

    The parameters involved in obtaining the multiple exposure photographs in the laser speckle velocimetry method (to record the light scattering by the seeding particles) were optimized. The effects of the type, concentration, and dimensions of the tracer, the exposure conditions (time between exposures, exposure time, and number of exposures), and the sensitivity and resolution of the film on the quality of the final results were investigated, photographing an experimental flow behind an impulsively started circular cylinder. The velocity data were acquired by digital processing of Young's fringes, produced by point-by-point scanning of a photographic negative. Using the optimal photographing conditions, the errors involved in the estimation of the fringe angle and spacing were of the order of 1 percent for the spacing and +/1 deg for the fringe orientation. The resulting accuracy in the velocity was of the order of 2-3 percent of the maximum velocity in the field.

  9. Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data

    NASA Astrophysics Data System (ADS)

    Simão Ferreira, C. J.; Bijl, H.; van Bussel, G.; van Kuik, G.

    2007-07-01

    The implementation of wind energy conversion systems in the built environment renewed the interest and the research on Vertical Axis Wind Turbines (VAWT), which in this application present several advantages over Horizontal Axis Wind Turbines (HAWT). The VAWT has an inherent unsteady aerodynamic behavior due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. The phenomenon of dynamic stall is then an intrinsic effect of the operation of a Vertical Axis Wind Turbine at low tip speed ratios, having a significant impact in both loads and power. The complexity of the unsteady aerodynamics of the VAWT makes it extremely attractive to be analyzed using Computational Fluid Dynamics (CFD) models, where an approximation of the continuity and momentum equations of the Navier-Stokes equations set is solved. The complexity of the problem and the need for new design approaches for VAWT for the built environment has driven the authors of this work to focus the research of CFD modeling of VAWT on: •comparing the results between commonly used turbulence models: URANS (Spalart-Allmaras and k-epsilon) and large eddy models (Large Eddy Simulation and Detached Eddy Simulation) •verifying the sensitivity of the model to its grid refinement (space and time), •evaluating the suitability of using Particle Image Velocimetry (PIV) experimental data for model validation. The 2D model created represents the middle section of a single bladed VAWT with infinite aspect ratio. The model simulates the experimental work of flow field measurement using Particle Image Velocimetry by Simão Ferreira et al for a single bladed VAWT. The results show the suitability of the PIV data for the validation of the model, the need for accurate simulation of the large eddies and the sensitivity of the model to grid refinement.

  10. Video monitoring in the Gadria debris flow catchment: preliminary results of large scale particle image velocimetry (LSPIV)

    NASA Astrophysics Data System (ADS)

    Theule, Joshua; Crema, Stefano; Comiti, Francesco; Cavalli, Marco; Marchi, Lorenzo

    2015-04-01

    Large scale particle image velocimetry (LSPIV) is a technique mostly used in rivers to measure two dimensional velocities from high resolution images at high frame rates. This technique still needs to be thoroughly explored in the field of debris flow studies. The Gadria debris flow monitoring catchment in Val Venosta (Italian Alps) has been equipped with four MOBOTIX M12 video cameras. Two cameras are located in a sediment trap located close to the alluvial fan apex, one looking upstream and the other looking down and more perpendicular to the flow. The third camera is in the next reach upstream from the sediment trap at a closer proximity to the flow. These three cameras are connected to a field shelter equipped with power supply and a server collecting all the monitoring data. The fourth camera is located in an active gully, the camera is activated by a rain gauge when there is one minute of rainfall. Before LSPIV can be used, the highly distorted images need to be corrected and accurate reference points need to be made. We decided to use IMGRAFT (an opensource image georectification toolbox) which can correct distorted images using reference points and camera location, and then finally rectifies the batch of images onto a DEM grid (or the DEM grid onto the image coordinates). With the orthorectified images, we used the freeware Fudaa-LSPIV (developed by EDF, IRSTEA, and DeltaCAD Company) to generate the LSPIV calculations of the flow events. Calculated velocities can easily be checked manually because of the already orthorectified images. During the monitoring program (since 2011) we recorded three debris flow events at the sediment trap area (each with very different surge dynamics). The camera in the gully was in operation in 2014 which managed to record granular flows and rockfalls, which particle tracking may be more appropriate for velocity measurements. The four cameras allows us to explore the limitations of camera distance, angle, frame rate, and image

  11. Tomographic particle image velocimetry of desert locust wakes: instantaneous volumes combine to reveal hidden vortex elements and rapid wake deformation.

    PubMed

    Bomphrey, Richard J; Henningsson, Per; Michaelis, Dirk; Hollis, David

    2012-12-07

    Aerodynamic structures generated by animals in flight are unstable and complex. Recent progress in quantitative flow visualization has advanced our understanding of animal aerodynamics, but measurements have hitherto been limited to flow velocities at a plane through the wake. We applied an emergent, high-speed, volumetric fluid imaging technique (tomographic particle image velocimetry) to examine segments of the wake of desert locusts, capturing fully three-dimensional instantaneous flow fields. We used those flow fields to characterize the aerodynamic footprint in unprecedented detail and revealed previously unseen wake elements that would have gone undetected by two-dimensional or stereo-imaging technology. Vortex iso-surface topographies show the spatio-temporal signature of aerodynamic force generation manifest in the wake of locusts, and expose the extent to which animal wakes can deform, potentially leading to unreliable calculations of lift and thrust when using conventional diagnostic methods. We discuss implications for experimental design and analysis as volumetric flow imaging becomes more widespread.

  12. Tomographic particle image velocimetry of desert locust wakes: instantaneous volumes combine to reveal hidden vortex elements and rapid wake deformation

    PubMed Central

    Bomphrey, Richard J.; Henningsson, Per; Michaelis, Dirk; Hollis, David

    2012-01-01

    Aerodynamic structures generated by animals in flight are unstable and complex. Recent progress in quantitative flow visualization has advanced our understanding of animal aerodynamics, but measurements have hitherto been limited to flow velocities at a plane through the wake. We applied an emergent, high-speed, volumetric fluid imaging technique (tomographic particle image velocimetry) to examine segments of the wake of desert locusts, capturing fully three-dimensional instantaneous flow fields. We used those flow fields to characterize the aerodynamic footprint in unprecedented detail and revealed previously unseen wake elements that would have gone undetected by two-dimensional or stereo-imaging technology. Vortex iso-surface topographies show the spatio-temporal signature of aerodynamic force generation manifest in the wake of locusts, and expose the extent to which animal wakes can deform, potentially leading to unreliable calculations of lift and thrust when using conventional diagnostic methods. We discuss implications for experimental design and analysis as volumetric flow imaging becomes more widespread. PMID:22977102

  13. Measurement of fluid rotation, dilation, and displacement in particle image velocimetry using a Fourier–Mellin cross-correlation

    DOE PAGES

    Giarra, Matthew N.; Charonko, John J.; Vlachos, Pavlos P.

    2015-02-05

    Traditional particle image velocimetry (PIV) uses discrete Cartesian cross correlations (CCs) to estimate the displacements of groups of tracer particles within small subregions of sequentially captured images. However, these CCs fail in regions with large velocity gradients or high rates of rotation. In this paper, we propose a new PIV correlation method based on the Fourier–Mellin transformation (FMT) that enables direct measurement of the rotation and dilation of particle image patterns. In previously unresolvable regions of large rotation, our algorithm significantly improves the velocity estimates compared to traditional correlations by aligning the rotated and stretched particle patterns prior to performingmore » Cartesian correlations to estimate their displacements. Furthermore, our algorithm, which we term Fourier–Mellin correlation (FMC), reliably measures particle pattern displacement between pairs of interrogation regions with up to ±180° of angular misalignment, compared to 6–8° for traditional correlations, and dilation/compression factors of 0.5–2.0, compared to 0.9–1.1 for a single iteration of traditional correlations.« less

  14. Development and application of a high speed digital data acquisition technique to study steam bubble collapse using particle image velocimetry

    SciTech Connect

    Schmidl, W.D.

    1992-08-01

    The use of a Particle Image Velocimetry (PIV) method, which uses digital cameras for data acquisition, for studying high speed fluid flows is usually limited by the digital camera's frame acquisition rate. The velocity of the fluid under study has to be limited to insure that the tracer seeds suspended in the fluid remain in the camera's focal plane for at least two consecutive images. However, the use of digital cameras for data acquisition is desirable to simplify and expedite the data analysis process. A technique was developed which will measure fluid velocities with PIV techniques using two successive digital images and two different framing rates simultaneously. The first part of the method will measure changes which occur to the flow field at the relatively slow framing rate of 53.8 ms. The second part will measure changes to the same flow field at the relatively fast framing rate of 100 to 320 [mu]s. The effectiveness of this technique was tested by studying the collapse of steam bubbles in a subcooled tank of water, a relatively high speed phenomena. The tracer particles were recorded and velocity vectors for the fluid were obtained far from the steam bubble collapse.

  15. Development and application of a high speed digital data acquisition technique to study steam bubble collapse using particle image velocimetry

    SciTech Connect

    Schmidl, W.D.

    1992-08-01

    The use of a Particle Image Velocimetry (PIV) method, which uses digital cameras for data acquisition, for studying high speed fluid flows is usually limited by the digital camera`s frame acquisition rate. The velocity of the fluid under study has to be limited to insure that the tracer seeds suspended in the fluid remain in the camera`s focal plane for at least two consecutive images. However, the use of digital cameras for data acquisition is desirable to simplify and expedite the data analysis process. A technique was developed which will measure fluid velocities with PIV techniques using two successive digital images and two different framing rates simultaneously. The first part of the method will measure changes which occur to the flow field at the relatively slow framing rate of 53.8 ms. The second part will measure changes to the same flow field at the relatively fast framing rate of 100 to 320 {mu}s. The effectiveness of this technique was tested by studying the collapse of steam bubbles in a subcooled tank of water, a relatively high speed phenomena. The tracer particles were recorded and velocity vectors for the fluid were obtained far from the steam bubble collapse.

  16. Measurement of fluid rotation, dilation, and displacement in particle image velocimetry using a Fourier–Mellin cross-correlation

    SciTech Connect

    Giarra, Matthew N.; Charonko, John J.; Vlachos, Pavlos P.

    2015-02-05

    Traditional particle image velocimetry (PIV) uses discrete Cartesian cross correlations (CCs) to estimate the displacements of groups of tracer particles within small subregions of sequentially captured images. However, these CCs fail in regions with large velocity gradients or high rates of rotation. In this paper, we propose a new PIV correlation method based on the Fourier–Mellin transformation (FMT) that enables direct measurement of the rotation and dilation of particle image patterns. In previously unresolvable regions of large rotation, our algorithm significantly improves the velocity estimates compared to traditional correlations by aligning the rotated and stretched particle patterns prior to performing Cartesian correlations to estimate their displacements. Furthermore, our algorithm, which we term Fourier–Mellin correlation (FMC), reliably measures particle pattern displacement between pairs of interrogation regions with up to ±180° of angular misalignment, compared to 6–8° for traditional correlations, and dilation/compression factors of 0.5–2.0, compared to 0.9–1.1 for a single iteration of traditional correlations.

  17. 3D SERS imaging based on chemically-synthesized highly-symmetric nanoporous silver microparticles

    NASA Astrophysics Data System (ADS)

    Ozaki, Yukihiro; Vantasin, Sanpon; Ji, Wei; Tanaka, Yoshito; Kitahama, Yasutaka; Wongrawee, Kanet; Ekgasit, Sanong

    2016-09-01

    This study presents the synthesis, SERS properties in three dimensions, and an application of 3D symmetric nanoporous silver microparticles. The particles are synthesized by purely chemical process: controlled precipitation of AgCl to acquire highly symmetric AgCl microparticle, followed by in-place to convert AgCl into nanoporous silver. The particles display highly predictable SERS enhancement pattern in three dimensions, which resembles particle shape and retains symmetry. The highly regular enhancement pattern allows an application in the study of inhomogeneity in two-layer polymer system, by improving spatial resolution in Z axis.

  18. Fiber-coupled, 10 kHz simultaneous OH planar laser-induced fluorescence/particle-image velocimetry.

    PubMed

    Hsu, Paul S; Jiang, Naibo; Gord, James R; Roy, Sukesh

    2013-01-15

    Planar laser-induced fluorescence (PLIF) and particle-image velocimetry (PIV) techniques that employ free-standing optics face severe challenges when implemented in harsh environments associated with practical combustion facilities because of limited optical access and restrictions on operation of sensitive laser systems. To circumvent this problem, we have developed and implemented a fiber-coupled, high-speed ultraviolet (UV) PLIF/PIV system for measuring hydroxyl radical (OH) concentration and velocity in a realistic 4 MW combustion rig. This system permits delivery of high-power, 10 kHz, nanosecond-duration OH-PLIF excitation pulses (283 nm) and PIV pulses (532 nm) through a common 6 m long, 600 μm core, deep-UV-enhanced multimode fiber. Simultaneous OH-PLIF and PIV imaging at a data-acquisition rate of 10 kHz is demonstrated in turbulent premixed flames behind a bluff body. The effects of delivering high-repetition-rate, intense UV and visible beams through a long optical fiber are investigated, and potential system improvements are discussed.

  19. Preliminary design of a SIMO fuzzy controller for steering microparticles inside blood vessels by using a magnetic resonance imaging system.

    PubMed

    Peng, Ke; Martel, Sylvain

    2011-01-01

    In this paper, a Single-Input-Multiple-Output (SIMO) fuzzy controller is designed to drive an upgraded clinical real-time Magnetic Resonance Imaging (MRI) system to provide steering forces for an aggregation of ferromagnetic microparticles in the human cardiovascular system according to a pre-set pathway. This kind of endovascular navigation is considered as an important procedure of the catheter-based method for medical treatments against diseases such as some particular types of cancers. The validity of the fuzzy controller has been tested by preliminary simulation results.

  20. Dual-plane stereoscopic particle image velocimetry: system set-up and its application on a lobed jet mixing flow

    NASA Astrophysics Data System (ADS)

    Hu, H.; Saga, T.; Kobayashi, T.; Taniguchi, N.; Yasuki, M.

    The technical basis and system set-up of a dual-plane stereoscopic particle image velocimetry (PIV) system, which can obtain the flow velocity (all three components) fields at two spatially separated planes simultaneously, is summarized. The simultaneous measurements were achieved by using two sets of double-pulsed Nd:Yag lasers with additional optics to illuminate the objective fluid flow with two orthogonally linearly polarized laser sheets at two spatially separated planes, as proposed by Kaehler and Kompenhans in 1999. The light scattered by the tracer particles illuminated by laser sheets with orthogonal linear polarization were separated by using polarizing beam-splitter cubes, then recorded by high-resolution CCD cameras. A three-dimensional in-situ calibration procedure was used to determine the relationships between the 2-D image planes and three-dimensional object fields for both position mapping and velocity three-component reconstruction. Unlike conventional two-component PIV systems or single-plane stereoscopic PIV systems, which can only get one-component of vorticity vectors, the present dual-plane stereoscopic PIV system can provide all the three components of the vorticity vectors and various auto-correlation and cross-correlation coefficients of flow variables instantaneously and simultaneously. The present dual-plane stereoscopic PIV system was applied to measure an air jet mixing flow exhausted from a lobed nozzle. Various vortex structures in the lobed jet mixing flow were revealed quantitatively and instantaneously. In order to evaluate the measurement accuracy of the present dual-plane stereoscopic PIV system, the measurement results were compared with the simultaneous measurement results of a laser Doppler velocimetry (LDV) system. It was found that both the instantaneous data and ensemble-averaged values of the stereoscopic PIV measurement results and the LDV measurement results agree well. For the ensemble-averaged values of the out

  1. Velocimetry with diode lasers

    NASA Astrophysics Data System (ADS)

    de Mul, F. F. M.; Jentink, H. W.; Koelink, M.; Greve, J.; Aarnoudse, J. G.

    The history of the application of diode lasers in velocimetry is reviewed. Some problems arising when using those lasers, e.g., mode hopping and wavelength shifts caused by temperature effects, are discussed, together with coherence effects encountered with diode lasers. The application in dual-beam velocimetry, in direct-contact velocimetry and in velocimetry using self-mixing will be discussed.

  2. Measurements of liquid-phase turbulence in gas-liquid two-phase flows using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Zhou, Xinquan; Doup, Benjamin; Sun, Xiaodong

    2013-12-01

    Liquid-phase turbulence measurements were performed in an air-water two-phase flow loop with a circular test section of 50 mm inner diameter using a particle image velocimetry (PIV) system. An optical phase separation method--planar laser-induced fluorescence (PLIF) technique—which uses fluorescent particles and an optical filtration technique, was employed to separate the signals of the fluorescent seeding particles from those due to bubbles and other noises. An image pre-processing scheme was applied to the raw PIV images to remove the noise residuals that are not removed by the PLIF technique. In addition, four-sensor conductivity probes were adopted to measure the radial distribution of the void fraction. Two benchmark tests were performed: the first was a comparison of the PIV measurement results with those of similar flow conditions using thermal anemometry from previous studies; the second quantitatively compared the superficial liquid velocities calculated from the local liquid velocity and void fraction measurements with the global liquid flow rate measurements. The differences of the superficial liquid velocity obtained from the two measurements were bounded within ±7% for single-phase flows and two-phase bubbly flows with the area-average void fraction up to 18%. Furthermore, a preliminary uncertainty analysis was conducted to investigate the accuracy of the two-phase PIV measurements. The systematic uncertainties due to the circular pipe curvature effects, bubble surface reflection effects and other potential uncertainty sources of the PIV measurements were discussed. The purpose of this work is to facilitate the development of a measurement technique (PIV-PLIF) combined with image pre-processing for the liquid-phase turbulence in gas-liquid two-phase flows of relatively high void fractions. The high-resolution data set can be used to more thoroughly understand two-phase flow behavior, develop liquid-phase turbulence models, and assess high

  3. 3D real-time visualization of blood flow in cerebral aneurysms by light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Carlsohn, Matthias F.; Kemmling, André; Petersen, Arne; Wietzke, Lennart

    2016-04-01

    Cerebral aneurysms require endovascular treatment to eliminate potentially lethal hemorrhagic rupture by hemostasis of blood flow within the aneurysm. Devices (e.g. coils and flow diverters) promote homeostasis, however, measurement of blood flow within an aneurysm or cerebral vessel before and after device placement on a microscopic level has not been possible so far. This would allow better individualized treatment planning and improve manufacture design of devices. For experimental analysis, direct measurement of real-time microscopic cerebrovascular flow in micro-structures may be an alternative to computed flow simulations. An application of microscopic aneurysm flow measurement on a regular basis to empirically assess a high number of different anatomic shapes and the corresponding effect of different devices would require a fast and reliable method at low cost with high throughout assessment. Transparent three dimensional 3D models of brain vessels and aneurysms may be used for microscopic flow measurements by particle image velocimetry (PIV), however, up to now the size of structures has set the limits for conventional 3D-imaging camera set-ups. On line flow assessment requires additional computational power to cope with the processing large amounts of data generated by sequences of multi-view stereo images, e.g. generated by a light field camera capturing the 3D information by plenoptic imaging of complex flow processes. Recently, a fast and low cost workflow for producing patient specific three dimensional models of cerebral arteries has been established by stereo-lithographic (SLA) 3D printing. These 3D arterial models are transparent an exhibit a replication precision within a submillimeter range required for accurate flow measurements under physiological conditions. We therefore test the feasibility of microscopic flow measurements by PIV analysis using a plenoptic camera system capturing light field image sequences. Averaging across a sequence of

  4. Particle Image Velocimetry Used to Qualitatively Validate Computational Fluid Dynamic Simulations in an Oxygenator: A Proof of Concept.

    PubMed

    Schlanstein, Peter C; Hesselmann, Felix; Jansen, Sebastian V; Gemsa, Jeannine; Kaufmann, Tim A; Klaas, Michael; Roggenkamp, Dorothee; Schröder, Wolfgang; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

    2015-09-01

    Computational fluid dynamics (CFD) is used to simulate blood flow inside the fiber bundles of oxygenators. The results are interpreted in terms of flow distribution, e.g., stagnation and shunt areas. However, experimental measurements that provide such information on the local flow between the fibers are missing. A transparent model of an oxygenator was built to perform particle image velocimetry (PIV), to perform the experimental validation. The similitude theory was used to adjust the size of the PIV model to the minimal resolution of the PIV system used (scale factor 3.3). A standard flow of 80 mL/min was simulated with CFD for the real oxygenator and the equivalent flow of 711 mL/min, according to the similitude theory, was investigated with PIV. CFD predicts the global size of stagnation and shunt areas well, but underestimates the streamline length and changes in velocities due to the meandering flow around the real fibers in the PIV model. Symmetrical CFD simulation cannot consider asymmetries in the flow, due to manufacturing-related asymmetries in the fiber bundle. PIV could be useful for validation of CFD simulations; measurement quality however must be improved for a quantitative validation of CFD results and the investigation of flow effects such as tortuosity and anisotropic flow behavior.

  5. A Stereo Imaging Velocimetry Technique for Analyzing Structure of Flame Balls at Low Lewis-Number (SOFBALL) Data

    NASA Technical Reports Server (NTRS)

    McDowell, Mark; Gray, Elizabeth

    2008-01-01

    Stereo Imaging Velocimetry (SIV) is a NASA Glenn Research Center (GRC) developed fluid physics technique for measuring threedimensional (3-D) velocities in any optically transparent fluid that can be seeded with tracer particles. SIV provides a means to measure 3-D fluid velocities quantitatively and qualitatively at many points. This technique provides full-field 3-D analysis of any optically clear fluid or gas experiment using standard off-the-shelf CCD cameras to provide accurate and reproducible 3-D velocity profiles for experiments that require 3-D analysis. A flame ball is a steady flame in a premixed combustible atmosphere which, due to the transport properties (low Lewis-number) of the mixture, does not propagate but is instead supplied by diffusive transport of the reactants, forming a premixed flame. This flame geometry presents a unique environment for testing combustion theory. We present our analysis of flame ball phenomena utilizing SIV technology in order to accurately calculate the 3-D position of a flame ball(s) during an experiment, which can be used as a direct comparison of numerical simulations.

  6. Measurement of turbulence statistics in single-phase and two-phase flows using ultrasound imaging velocimetry

    NASA Astrophysics Data System (ADS)

    Gurung, Arati; Poelma, Christian

    2016-11-01

    Ultrasound imaging velocimetry (UIV) has received considerable interest as a tool to measure in non-transparent flows. So far, studies have only reported statistics for steady flows or used a qualitative approach. In this study, we demonstrate that UIV has matured to a level where accurate turbulence statistics can be obtained. The technique is first validated in laminar and fully developed turbulent pipe flow (single-phase, with water as fluid) at a Reynolds number of 5300. The flow statistics agree with the literature data. Subsequently, we obtain similar statistics in turbulent two-phase flows at the same Reynolds number, by adding solid particles up to volume fraction of 3 %. In these cases, the medium is completely opaque, yet UIV provides useable data. The error in the measurements is estimated using an ad hoc approach at a volume load up to 10 %. For this case, the errors are approximately 1.9 and 0.3 % of the centerline velocity for the streamwise and radial velocity components, respectively. Additionally, it is demonstrated that it is possible to estimate the local concentration in stratified flows.

  7. Using Particle Imaging Velocimetry to Measure Anterior-Posterior Velocity Gradients in the Excised Canine Larynx Model

    PubMed Central

    Khosla, Sid; Murugappan, Shanmugam; Lakhamraju, Raghavaraju; Gutmark, Ephraim

    2008-01-01

    Objectives To quantify the anterior-posterior velocity gradient, we studied the velocity flow fields above the vocal folds in both the midcoronal and midsagittal planes. It was also our purpose to use these fields to deduce the mechanisms that cause the anterior-posterior gradient and to determine whether the vortical structures are highly 3-dimensional. Methods Using the particle imaging velocimetry method for 5 excised canine larynges. we obtained phase-averaged velocity fields in the midcoronal and midsagittal planes for 30 phases of phonation. The velocity fields were determined synchronously with the vocal fold motion recorded by high-speed videography. Results The results show that immediately above the folds, there is no significant anterior-posterior velocity gradient. However, as the flow travels downstream, the laryngeal jet tends to narrow in width and skew toward the anterior commissure. Vortices are seen at the anterior and posterior edges of the flow. Conclusions The downstream narrowing in the midsagittal plane is consistent with and is probably due to a phenomenon known as axis switching. Axis switching also involves vortices in the sagittal and coronal planes bending in the axial plane. This results in highly 3-dimensional, complex vortical structures. However, there is remarkable cyclic repeatability of these vortices during a phonation cycle. PMID:18357838

  8. Particle image velocimetry measurement of an instability wave over a porous wall in a duct with flow

    NASA Astrophysics Data System (ADS)

    Alomar, Antoni; Aurégan, Yves

    2017-01-01

    The flow in a rectangular channel lined with a porous material and acoustically excited with an upstream loudspeaker has been investigated using particle image velocimetry. The measurements are phase-locked to the loudspeaker signal so that the phase-averaged velocity in the lined section is obtained during an excitation period. Most features of the phase-averaged velocity field in the lined section are found to be well described from the sum of three single duct modes: the hydrodynamic instability wave, a standing wave and an acoustic wave. The hydrodynamic instability wave travels at half the mean flow velocity, and its structure shows differences to the case of a locally reacting liner. The relative phase lag between the hydrodynamic and acoustic waves at the liner end dictates the interference between both waves, giving rise to the oscillations of the acoustical transmission coefficient as a function of the frequency. A detachment of the instability wave from the porous wall is observed in the vicinity of the liner downstream edge, together with the separation of the mean vorticity core.

  9. Experimental investigations on the fluid-mechanics of an electrospun heart valve by means of particle image velocimetry.

    PubMed

    Del Gaudio, Costantino; Gasbarroni, Pier Luca; Romano, Giovanni Paolo

    2016-12-01

    End-stage failing heart valves are currently replaced by mechanical or biological prostheses. Both types positively contribute to restore the physiological function of native valves, but a number of drawbacks limits the expected performances. In order to improve the outcome, tissue engineering can offer an alternative approach to design and fabricate innovative heart valves capable to support the requested function and to promote the formation of a novel, viable and correctly operating physiological structure. This potential result is particularly critical if referred to the aortic valve, being the one mainly exposed to structural and functional degeneration. In this regard, the here proposed study presents the fabrication and in vitro characterization of a bioresorbable electrospun heart valve prosthesis using the particle image velocimetry technique either in physiological and pathological fluid dynamic conditions. The scaffold was designed to reproduce the aortic valve geometry, also mimicking the fibrous structure of the natural extracellular matrix. To evaluate its performances for possible implantation, the flow fields downstream the valve were accurately investigated and compared. The experimental results showed a correct functionality of the device, supported by the formation of vortex structures at the edge of the three cusps, with Reynolds stress values below the threshold for the risk of hemolysis (which can be comprised in the range 400-4000N/m(2) depending on the exposure period), and a good structural resistance to the mechanical loads generated by the driving pressure difference.

  10. Stereoscopic particle image velocimetry measurements of the three-dimensional flow field of a descending autorotating mahogany seed (Swietenia macrophylla).

    PubMed

    Salcedo, E; Treviño, C; Vargas, R O; Martínez-Suástegui, L

    2013-06-01

    An experimental investigation of near field aerodynamics of wind dispersed rotary seeds has been performed using stereoscopic digital particle image velocimetry (DPIV). The detailed three-dimensional flow structure of the leading-edge vortex (LEV) of autorotating mahogany seeds (Swietenia macrophylla) in a low-speed vertical wind tunnel is revealed for the first time. The results confirm that the presence of strong spanwise flow and strain produced by centrifugal forces through a spiral vortex are responsible for the attachment and stability of the LEV, with its core forming a cone pattern with a gradual increase in vortex size. The LEV appears at 25% of the wingspan, increases in size and strength outboard along the wing, and reaches its maximum stability and spanwise velocity at 75% of the wingspan. At a region between 90 and 100% of the wingspan, the strength and stability of the vortex core decreases and the LEV re-orientation/inflection with the tip vortex takes place. In this study, the instantaneous flow structure and the instantaneous velocity and vorticity fields measured in planes parallel to the free stream direction are presented as contour plots using an inertial and a non-inertial frame of reference. Results for the mean aerodynamic thrust coefficients as a function of the Reynolds number are presented to supplement the DPIV data.

  11. A particle image velocimetry study of the flow physics generated by a thin lamina oscillating in a viscous fluid

    NASA Astrophysics Data System (ADS)

    Jalalisendi, Mohammad; Panciroli, Riccardo; Cha, Youngsu; Porfiri, Maurizio

    2014-02-01

    In this paper, we study the flow physics produced by a thin rigid lamina oscillating in an otherwise quiescent viscous fluid. Particle image velocimetry (PIV) is used to extract the flow kinematics, which is, in turn, utilized to reconstruct the pressure distribution around the lamina through the integration of Navier-Stokes equations. The hydrodynamic loading experienced by the lamina is ultimately estimated from PIV data to investigate added mass and fluid damping phenomena. Experiments are conducted for varying Reynolds and Keulegan-Carpenter numbers to elucidate the relative weight of inertial, convective, and viscous phenomena on the resulting flow physics. In agreement with prior numerical studies, experimental results demonstrate that increasing the Reynolds and the Keulegan-Carpenter numbers results into the formation of coherent structures that are shed at the edges of the lamina and advected by the flow. This phenomenon is associated with nonlinearities in the hydrodynamic loading, whereby fluid damping is found to increase nonlinearly with the oscillation of the lamina.

  12. Turbulent Flow Field Measurements of Separate Flow Round and Chevron Nozzles with Pylon Interaction Using Particle Image Velocimetry

    NASA Technical Reports Server (NTRS)

    Doty, Michael J.; Henerson, Brenda S.; Kinzie, Kevin W.

    2004-01-01

    Particle Image Velocimetry (PIV) measurements for six separate flow bypass ratio five nozzle configurations have recently been obtained in the NASA Langley Jet Noise Laboratory. The six configurations include a baseline configuration with round core and fan nozzles, an eight-chevron core nozzle at two different clocking positions, and repeats of these configurations with a pylon included. One run condition representative of takeoff was investigated for all cases with the core nozzle pressure ratio set to 1.56 and the total temperature to 828 K. The fan nozzle pressure ratio was set to 1.75 with a total temperature of 350 K, and the freestream Mach number was M = 0.28. The unsteady flow field measurements provided by PIV complement recent computational, acoustic, and mean flow field studies performed at NASA Langley for the same nozzle configurations and run condition. The PIV baseline configuration measurements show good agreement with mean flow field data as well as existing PIV data acquired at NASA Glenn. Nonetheless, the baseline configuration turbulence profile indicates an asymmetric flow field, despite careful attention to concentricity. The presence of the pylon increases the upper shear layer turbulence levels while simultaneously decreasing the turbulence levels in the lower shear layer. In addition, a slightly shorter potential core length is observed with the addition of the pylon. Finally, comparisons of computational results with PIV measurements are favorable for mean flow, slightly over-predicted for Reynolds shear stress, and underpredicted for Reynolds normal stress components.

  13. Particle image velocimetry analysis of the flow around circular cylinder induced by arc discharge rotating in magnetic field

    NASA Astrophysics Data System (ADS)

    Munhoz, D. S.; Bityurin, V. A.; Klimov, A. I.; Moralev, I. A.

    2016-11-01

    An experimental study of the flow around a circular cylinder model with magnetohydrodynamic (MHD) actuator was carried out in subsonic wind tunnels (M < 0.2). Combined (high frequency and pulsed-periodic) electrical discharge was used in this MHD actuator. This intense pulsed-periodic discharge had the following characteristics: voltage amplitude up to 15 kV, current amplitude up to 16 A and frequency up to 1 kHz. Permanent magnets with an induction of B = 0.1 T on the model surface were placed inside the cylindrical model. Annular electrodes were situated on the surface of the cylindrical model. The Lorentz force causes the rotation of the electric arc on the model surface. In turn, the movement of the arc discharge induces the rotation of the gas near the surface of the model. In this experiment were carried out the measurement of the flow velocity profile near the surface of the model on the following operational modes: with plasma and without plasma. A parametric study of the aerodynamic performance of the model was fulfilled with respect to the discharge parameters and the flow velocity. To measure the velocity profile was used particle image velocimetry method.

  14. Hands-On Particle Image Velocimetry Experience for Bioengineering Students Using the Interactive Flowcoach System to Understand Aneurysm Hemodynamics

    NASA Astrophysics Data System (ADS)

    Roszelle, Breigh N.; Okcay, Murat; Oztekin, B. Uygar; Frakes, David H.

    2012-11-01

    The Flowcoach system is a flow visualization and analysis platform from Interactive Flow Studies that uses particle image velocimetry (PIV) and computational fluid dynamics to provide interactive fluid dynamics education. In the spring of 2012, Flowcoach was used at Arizona State University to help teach bioengineering students about biofluid mechanics. A custom insert was made for Flowcoach to model an anatomical aneurysm that could be treated with a high-porosity flow diverting stent. Students performed PIV on the treated aneurysm model in small lab groups using Flowcoach and then wrote reports comparing their results to those from an untreated aneurysm model. The students were surveyed before and after the project and asked to rate their understanding of general biofluid mechanics, as well as experimental fluid mechanics and aneurysmal hemodynamics. Of the 76 students surveyed, 86% indicated an increase in their understanding of biofluid mechanics, and 90% indicated an increase in their understanding of both PIV and cerebral aneurysm hemodynamics. Students' written feedback showed that they felt Flowcoach and the interactive learning experience it provided were both interesting and beneficial to their future careers as engineers.

  15. Particle image velocimetry measurements for opposing flow in a vertical channel with a differential and asymmetric heating condition

    SciTech Connect

    Martinez-Suastegui, L.; Trevino, C.

    2007-10-15

    Particle image velocimetry (PIV) measurements were carried out in an experimental investigation of laminar mixed convection in a vertical duct with a square cross-section. The main downward water-flow is driven by gravity while a portion of a lateral side is heated, and buoyancy forces produce non-stationary vortex structures close to the heated region. Various ranges of the Grashof number, Gr are studied in combination with the Reynolds number, Re varying from 300 to 700. The values of the generalized buoyancy parameter or Richardson number, Ri = Gr/Re{sup 2} parallel to the Grashof number are included in the results. The influence of these nondimensional parameters and how they affect the fluid flow structure and vortex sizes and locations are reported. The flow patterns are nonsymmetric, periodic, and exhibit increasing complexity and frequency for increasing buoyancy. For the averaged values of the resulting vortex dimensions, it was found that a better and more congruent representation occurs when employing the Grashof and Reynolds numbers as independent parameters. (author)

  16. Draft tube discharge fluctuation during self-sustained pressure surge: fluorescent particle image velocimetry in two-phase flow

    NASA Astrophysics Data System (ADS)

    Müller, A.; Dreyer, M.; Andreini, N.; Avellan, F.

    2013-04-01

    Hydraulic machines play an increasingly important role in providing a secondary energy reserve for the integration of renewable energy sources in the existing power grid. This requires a significant extension of their usual operating range, involving the presence of cavitating flow regimes in the draft tube. At overload conditions, the self-sustained oscillation of a large cavity at the runner outlet, called vortex rope, generates violent periodic pressure pulsations. In an effort to better understand the nature of this unstable behavior and its interaction with the surrounding hydraulic and mechanical system, the flow leaving the runner is investigated by means of particle image velocimetry. The measurements are performed in the draft tube cone of a reduced scale model of a Francis turbine. A cost-effective method for the in-house production of fluorescent seeding material is developed and described, based on off-the-shelf polyamide particles and Rhodamine B dye. Velocity profiles are obtained at three streamwise positions in the draft tube cone, and the corresponding discharge variation in presence of the vortex rope is calculated. The results suggest that 5-10 % of the discharge in the draft tube cone is passing inside the vortex rope.

  17. Assessment of transmitral flow after mitral valve edge-to-edge repair using High-speed particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Jeyhani, Morteza; Shahriari, Shahrokh; Labrosse, Michel; Kadem, Lyes

    2013-11-01

    Approximately 500,000 people in North America suffer from mitral valve regurgitation (MR). MR is a disorder of the heart in which the mitral valve (MV) leaflets do not close securely during systole. Edge-to-edge repair (EtER) technique can be used to surgically treat MR. This technique produces a double-orifice configuration for the MV. Under these un-physiological conditions, flow downstream of the MV forms a double jet structure that may disturb the intraventricular hemodynamics. Abnormal flow patterns following EtER are mainly characterized by high-shear stress and stagnation zones in the left ventricle (LV), which increase the potential of blood component damage. In this study, a custom-made prosthetic bicuspid MV was used to analyze the LV flow patterns after EtER by means of digital particle image velocimetry (PIV). Although the repair of a MV using EtER technique is an effective approach, this study confirms that EtER leads to changes in the LV flow field, including the generation of a double mitral jet flow and high shear stress regions.

  18. Multiparticle imaging technique for two-phase fluid flows using pulsed laser speckle velocimetry. Final report, September 1988--November 1992

    SciTech Connect

    Hassan, T.A.

    1992-12-01

    The practical use of Pulsed Laser Velocimetry (PLV) requires the use of fast, reliable computer-based methods for tracking numerous particles suspended in a fluid flow. Two methods for performing tracking are presented. One method tracks a particle through multiple sequential images (minimum of four required) by prediction and verification of particle displacement and direction. The other method, requiring only two sequential images uses a dynamic, binary, spatial, cross-correlation technique. The algorithms are tested on computer-generated synthetic data and experimental data which was obtained with traditional PLV methods. This allowed error analysis and testing of the algorithms on real engineering flows. A novel method is proposed which eliminates tedious, undersirable, manual, operator assistance in removing erroneous vectors. This method uses an iterative process involving an interpolated field produced from the most reliable vectors. Methods are developed to allow fast analysis and presentation of sets of PLV image data. Experimental investigation of a two-phase, horizontal, stratified, flow regime was performed to determine the interface drag force, and correspondingly, the drag coefficient. A horizontal, stratified flow test facility using water and air was constructed to allow interface shear measurements with PLV techniques. The experimentally obtained local drag measurements were compared with theoretical results given by conventional interfacial drag theory. Close agreement was shown when local conditions near the interface were similar to space-averaged conditions. However, theory based on macroscopic, space-averaged flow behavior was shown to give incorrect results if the local gas velocity near the interface as unstable, transient, and dissimilar from the average gas velocity through the test facility.

  19. Two-dimensional confocal laser scanning microscopy image correlation for nanoparticle flow velocimetry

    NASA Astrophysics Data System (ADS)

    Jun, Brian; Giarra, Matthew; Golz, Brian; Main, Russell; Vlachos, Pavlos

    2016-11-01

    We present a methodology to mitigate the major sources of error associated with two-dimensional confocal laser scanning microscopy (CLSM) images of nanoparticles flowing through a microfluidic channel. The correlation-based velocity measurements from CLSM images are subject to random error due to the Brownian motion of nanometer-sized tracer particles, and a bias error due to the formation of images by raster scanning. Here, we develop a novel ensemble phase correlation with dynamic optimal filter that maximizes the correlation strength, which diminishes the random error. In addition, we introduce an analytical model of CLSM measurement bias error correction due to two-dimensional image scanning of tracer particles. We tested our technique using both synthetic and experimental images of nanoparticles flowing through a microfluidic channel. We observed that our technique reduced the error by up to a factor of ten compared to ensemble standard cross correlation (SCC) for the images tested in the present work. Subsequently, we will assess our framework further, by interrogating nanoscale flow in the cell culture environment (transport within the lacunar-canalicular system) to demonstrate our ability to accurately resolve flow measurements in a biological system.

  20. A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Zha, Kan; Busch, Stephen; Park, Cheolwoong; Miles, Paul C.

    2016-08-01

    In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. To ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortion quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches. The proposed hybrid back-projection method for the first time provides a time-efficient and robust way to process planar PIV measurements conducted in an optical research engine with temporally- and spatially-varying optical distortion. This method is based upon geometric ray tracing and serves as a universal tool for the correction of optical distortion with an arbitrary but axisymmetric piston crown window geometry. Analytical analysis demonstrates that the ignorance of optical distortion change during the PIV laser temporal interval may induce a significant error in instantaneous velocity measurements. With the proposed digital dewarping method, this piston-motion-induced error can be eliminated. Uncertainty analysis with simulated particle images provides guidance on whether to back-project particle images or back-project velocity fields in order to minimize dewarping-induced uncertainties. The optimal implementation is piston-geometry-dependent. For regions with significant change in nominal magnification factor, it is recommended to apply the proposed back-projection approach to particle images prior to

  1. Artificial frame filling using adaptive neural fuzzy inference system for particle image velocimetry dataset

    NASA Astrophysics Data System (ADS)

    Akdemir, Bayram; Doǧan, Sercan; Aksoy, Muharrem H.; Canli, Eyüp; Özgören, Muammer

    2015-03-01

    Liquid behaviors are very important for many areas especially for Mechanical Engineering. Fast camera is a way to observe and search the liquid behaviors. Camera traces the dust or colored markers travelling in the liquid and takes many pictures in a second as possible as. Every image has large data structure due to resolution. For fast liquid velocity, there is not easy to evaluate or make a fluent frame after the taken images. Artificial intelligence has much popularity in science to solve the nonlinear problems. Adaptive neural fuzzy inference system is a common artificial intelligence in literature. Any particle velocity in a liquid has two dimension speed and its derivatives. Adaptive Neural Fuzzy Inference System has been used to create an artificial frame between previous and post frames as offline. Adaptive neural fuzzy inference system uses velocities and vorticities to create a crossing point vector between previous and post points. In this study, Adaptive Neural Fuzzy Inference System has been used to fill virtual frames among the real frames in order to improve image continuity. So this evaluation makes the images much understandable at chaotic or vorticity points. After executed adaptive neural fuzzy inference system, the image dataset increase two times and has a sequence as virtual and real, respectively. The obtained success is evaluated using R2 testing and mean squared error. R2 testing has a statistical importance about similarity and 0.82, 0.81, 0.85 and 0.8 were obtained for velocities and derivatives, respectively.

  2. Imaging lung tissue oscillations using high-speed X-ray velocimetry.

    PubMed

    Thurgood, Jordan; Dubsky, Stephen; Uesugi, Kentaro; Curtis, Michael; Samarage, Chaminda R; Thompson, Bruce; Zosky, Graeme; Fouras, Andreas

    2016-01-01

    This work utilized synchrotron imaging to achieve a regional assessment of the lung's response to imparted oscillations. The forced oscillation technique is increasingly being used in clinical and research settings for the measurement of lung function. During the forced oscillation technique, pressure oscillations are imparted to the lungs via the subjects' airway opening and the response is measured. This provides information about the mechanical properties of the airways and lung tissue. The quality of measurements is dependent upon the input signal penetrating uniformly throughout the lung. However, the penetration of these signals is not well understood. The development and use of a novel image-processing technique in conjunction with synchrotron-based imaging was able to regionally assess the lungs' response to input pressure oscillation signals in anaesthetized mice. The imaging-based technique was able to quantify both the power and distribution of lung tissue oscillations during forced oscillations of the lungs. It was observed that under forced oscillations the apices had limited lung tissue expansion relative to the base. This technique could be used to optimize input signals used for the forced oscillation technique or potentially as a diagnostic tool itself.

  3. Live small-animal X-ray lung velocimetry and lung micro-tomography at the Australian Synchrotron Imaging and Medical Beamline.

    PubMed

    Murrie, Rhiannon P; Morgan, Kaye S; Maksimenko, Anton; Fouras, Andreas; Paganin, David M; Hall, Chris; Siu, Karen K W; Parsons, David W; Donnelley, Martin

    2015-07-01

    The high flux and coherence produced at long synchrotron beamlines makes them well suited to performing phase-contrast X-ray imaging of the airways and lungs of live small animals. Here, findings of the first live-animal imaging on the Imaging and Medical Beamline (IMBL) at the Australian Synchrotron are reported, demonstrating the feasibility of performing dynamic lung motion measurement and high-resolution micro-tomography. Live anaesthetized mice were imaged using 30 keV monochromatic X-rays at a range of sample-to-detector propagation distances. A frame rate of 100 frames s(-1) allowed lung motion to be determined using X-ray velocimetry. A separate group of humanely killed mice and rats were imaged by computed tomography at high resolution. Images were reconstructed and rendered to demonstrate the capacity for detailed, user-directed display of relevant respiratory anatomy. The ability to perform X-ray velocimetry on live mice at the IMBL was successfully demonstrated. High-quality renderings of the head and lungs visualized both large structures and fine details of the nasal and respiratory anatomy. The effect of sample-to-detector propagation distance on contrast and resolution was also investigated, demonstrating that soft tissue contrast increases, and resolution decreases, with increasing propagation distance. This new capability to perform live-animal imaging and high-resolution micro-tomography at the IMBL enhances the capability for investigation of respiratory diseases and the acceleration of treatment development in Australia.

  4. Acoustic mapping velocimetry

    NASA Astrophysics Data System (ADS)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  5. An Integrated Centroid Finding and Particle Overlap Decomposition Algorithm for Stereo Imaging Velocimetry

    NASA Technical Reports Server (NTRS)

    McDowell, Mark

    2004-01-01

    An integrated algorithm for decomposing overlapping particle images (multi-particle objects) along with determining each object s constituent particle centroid(s) has been developed using image analysis techniques. The centroid finding algorithm uses a modified eight-direction search method for finding the perimeter of any enclosed object. The centroid is calculated using the intensity-weighted center of mass of the object. The overlap decomposition algorithm further analyzes the object data and breaks it down into its constituent particle centroid(s). This is accomplished with an artificial neural network, feature based technique and provides an efficient way of decomposing overlapping particles. Combining the centroid finding and overlap decomposition routines into a single algorithm allows us to accurately predict the error associated with finding the centroid(s) of particles in our experiments. This algorithm has been tested using real, simulated, and synthetic data and the results are presented and discussed.

  6. Particle Image Velocimetry Using a Novel, Non-Intrusive Particle Seeding

    DTIC Science & Technology

    2006-05-01

    information of this model is given in reference (14). 10 II. Literature Review Section 1 - Chapter Overview This chapter summarizes particle image...collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources...gathering and maintaining the data needed, and completing and reviewing the collection of information . Send comments regarding this burden estimate or any

  7. High-speed particle image velocimetry for the efficient measurement of turbulence statistics

    NASA Astrophysics Data System (ADS)

    Willert, Christian E.

    2015-01-01

    A high-frame-rate camera and a continuous-wave laser are used to capture long particle image sequences exceeding 100,000 consecutive frames at framing frequencies up to 20 kHz. The electronic shutter of the high-speed CMOS camera is reduced to s to prevent excessive particle image streaking. The combination of large image number and high frame rate is possible by limiting the field of view to a narrow strip, primarily to capture temporally resolved profiles of velocity and derived quantities, such as vorticity as well as higher order statistics. Multi-frame PIV processing algorithms are employed to improve the dynamic range of recovered PIV data. The recovered data are temporally well resolved and provide sufficient samples for statistical convergence of the fluctuating velocity components. The measurement technique is demonstrated on a spatially developing turbulent boundary layer inside a small wind tunnel with and . The chosen magnification permits a reliable estimation of the mean velocity profile down to a few wall units and yields statistical information such as the Reynolds stress components and probability density functions. By means of single-line correlation, it is further possible to extract the near-wall velocity profile in the viscous sublayer, both time-averaged as well as instantaneous, which permits the estimation the wall shear rate and along with it the shear stress and friction velocity . These data are then used for the calculation of space-time correlation maps of wall shear stress and velocity.

  8. Time-Resolved Particle Image Velocimetry Measurements with Wall Shear Stress and Uncertainty Quantification for the FDA Nozzle Model.

    PubMed

    Raben, Jaime S; Hariharan, Prasanna; Robinson, Ronald; Malinauskas, Richard; Vlachos, Pavlos P

    2016-03-01

    We present advanced particle image velocimetry (PIV) processing, post-processing, and uncertainty estimation techniques to support the validation of computational fluid dynamics analyses of medical devices. This work is an extension of a previous FDA-sponsored multi-laboratory study, which used a medical device mimicking geometry referred to as the FDA benchmark nozzle model. Experimental measurements were performed using time-resolved PIV at five overlapping regions of the model for Reynolds numbers in the nozzle throat of 500, 2000, 5000, and 8000. Images included a twofold increase in spatial resolution in comparison to the previous study. Data was processed using ensemble correlation, dynamic range enhancement, and phase correlations to increase signal-to-noise ratios and measurement accuracy, and to resolve flow regions with large velocity ranges and gradients, which is typical of many blood-contacting medical devices. Parameters relevant to device safety, including shear stress at the wall and in bulk flow, were computed using radial basis functions. In addition, in-field spatially resolved pressure distributions, Reynolds stresses, and energy dissipation rates were computed from PIV measurements. Velocity measurement uncertainty was estimated directly from the PIV correlation plane, and uncertainty analysis for wall shear stress at each measurement location was performed using a Monte Carlo model. Local velocity uncertainty varied greatly and depended largely on local conditions such as particle seeding, velocity gradients, and particle displacements. Uncertainty in low velocity regions in the sudden expansion section of the nozzle was greatly reduced by over an order of magnitude when dynamic range enhancement was applied. Wall shear stress uncertainty was dominated by uncertainty contributions from velocity estimations, which were shown to account for 90-99% of the total uncertainty. This study provides advancements in the PIV processing methodologies over

  9. N-pulse particle image velocimetry-accelerometry for unsteady flow-structure interaction

    NASA Astrophysics Data System (ADS)

    Ding, Liuyang; Adrian, Ronald J.

    2017-01-01

    Flow-structure interaction experiments are a major area of application of instruments capable of simultaneously measuring instantaneous fields of velocity and acceleration. An N-pulse particle image velocimeter-accelerometer (N-P PIVA) employing bursts of N pulses, where N  =  3 or 4, and operating in the high-image-density particle seeding mode is described and demonstrated in the context of a representative flow-structure interaction experiment. The instrument employs two double-pulsed lasers and a high-resolution, fast-framing camera to acquire successive particle images having time separations small enough to perform good interpolation or finite differencing. The interrogation procedure locates the same group of particles at each pulse time using multiple cross-correlations, and a predictor-corrector algorithm enhances the strength of the cross-correlations by centering the windows on the particle groups at each time. A flow-structure experiment was performed in liquid surrounding a horizontal cylinder suspended by two thin, flexible, vertical rods from a slider block driven horizontally and sinusoidally. The value of the Keulegan-Carpenter number is \\text{KC}=4.85 and the frequency parameter (or Stokes number) is β =7.2 . Data from 2-, 3- and 4-pulse systems are compared to assess their relative performance. Measurements from the 4-pulse method with interpolation have smaller mean bias errors than the 3-pulse method with interpolation or the 4-pulse method with least squares, but larger random error. To make measurements close to the surface of the cylinder, a method using near-wall transformation and correlation analysis on a transformed grid is developed. Image processing used to determine the position, velocity and acceleration of the center of the cylinder is described. These measurements, together with the N-P PIVA data allow complete evaluation of each term in the exact, stationary control surface formulation of the fluid force applied to the

  10. A genetic algorithm particle pairing technique for 3D velocity field extraction in holographic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Sheng, J.; Meng, H.

    This research explores a novel technique, using Genetic Algorithm Particle Pairing (GAPP) to extract three-dimensional (3D) velocity fields of complex flows. It is motivated by Holographic Particle Image Velocimetry (HPIV), in which intrinsic speckle noise hinders the achievement of high particle density required for conventional correlation methods in extracting 3D velocity fields, especially in regions with large velocity gradients. The GA particle pairing method maps particles recorded at the first exposure to those at the second exposure in a 3D space, providing one velocity vector for each particle pair instead of seeking statistical averaging. Hence, particle pairing can work with sparse seeding and complex 3D velocity fields. When dealing with a large number of particles from two instants, however, the accuracy of pairing results and processing speed become major concerns. Using GA's capability to search a large solution space parallelly, our algorithm can efficiently find the best mapping scenarios among a large number of possible particle pairing schemes. During GA iterations, different pairing schemes or solutions are evaluated based on fluid dynamics. Two types of evaluation functions are proposed, tested, and embedded into the GA procedures. Hence, our Genetic Algorithm Particle Pairing (GAPP) technique is characterized by robustness in velocity calculation, high spatial resolution, good parallelism in handling large data sets, and high processing speed on parallel architectures. It has been successfully tested on a simple HPIV measurement of a real trapped vortex flow as well as a series of numerical experiments. In this paper, we introduce the principle of GAPP, analyze its performance under different parameters, and evaluate its processing speed on different computer architectures.

  11. Particle-image velocimetry investigation of the fluid-structure interaction mechanisms of a natural owl wing.

    PubMed

    Winzen, A; Roidl, B; Schröder, W

    2015-09-15

    The increasing interest in the development of small flying air vehicles has given rise to a strong need to thoroughly understand low-speed aerodynamics. The barn owl is a well-known example of a biological system that possesses a high level of adaptation to its habitat and as such can inspire future small-scale air vehicle design. The combination of the owl-specific wing geometry and plumage adaptations with the flexibility of the wing structure yields a highly complex flow field, still enabling the owl to perform stable and at the same time silent low-speed gliding flight. To investigate the effects leading to such a characteristic flight, time-resolved stereoscopic particle-image velocimetry (TR-SPIV) measurements are performed on a prepared natural owl wing in a range of angles of attack 0° ≤ α ≤ 6° and Reynolds numbers 40,000 ≤ Re(c) ≤ 120,000 based on the chord length at a position located at 30% of the halfspan from the owl's body. The flow field does not show any flow separation on the suction side, whereas flow separation is found on the pressure side for all investigated cases. The flow field on the pressure side is characterized by large-scale vortices which interact with the flexible wing structure. The good agreement of the shedding frequency of the pressure side vortices with the frequency of the trailing-edge deflection indicates that the structural deformation is induced by the flow field on the pressure side. Additionally, the reduction of the time-averaged mean wing curvature at high Reynolds numbers indicates a passive lift-control mechanism that provides constant lift in the entire flight envelope of the owl.

  12. Influence of a gas bubble on the dynamical parameters of the slug flow using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Siddiqui, M. I.; Heikal, M. R.; Munir, S.; Dass, S. C.; Aziz, A. Rashid A.

    2014-10-01

    Inlet conditions strongly affect the dynamical parameters of a two-phase slug flow. A series of experiments were carried out, in a 6m long Plexiglas pipe having internal diameter 74 mm, to investigate the influence of gas bubble on the flow dynamics inside the slugy body of a unit slug. The pipe was kept inclined at an elevation of 1.160 to consider the terrain slugging mechanism. An optical diagnostic technique, Particle Image Velocimetry (PIV) was employed at a point 3.5m from the inlet to measure the instantaneous velocity fields of the flow for each case. Single-phase liquid pipe flow and the slugy body of the two-phase slug flow are the targeted sections for study and comparison. Velocity components, turbulence intensity and average volume flux are measured and compared. The effect of gas bubble on the liquid Reynolds number is also considered. It is noticed that by increasing the gas flow rate velocity, average flux and average kinetic energy increases dramatically in a slugy body of a slug flow regime. The results are also compared with the single phase liquid flow having same liquid flow rate. Moreover it is noticed that the increase in average volume flux in a slugy body for lower liquid flow rates are more significant as compared to the higher liquid flow rates by increasing gas rate. This shows that slug can be helpful in oil transportation in terrain oil fields for lower liquid flow rates as it creates more fluctuations and vibrational forces for higher liquid flow.

  13. Spatiotemporal analysis of turbulent jets enabled by 100-kHz, 100-ms burst-mode particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Miller, Joseph D.; Jiang, Naibo; Slipchenko, Mikhail N.; Mance, Jason G.; Meyer, Terrence R.; Roy, Sukesh; Gord, James R.

    2016-12-01

    100-kHz particle image velocimetry (PIV) is demonstrated using a double-pulsed, burst-mode laser with a burst duration up to 100 ms. This enables up to 10,000 time-sequential vector fields for capturing a temporal dynamic range spanning over three orders of magnitude in high-speed turbulent flows. Pulse doublets with inter-pulse spacing of 2 µs and repetition rate of 100 kHz are generated using a fiber-based oscillator and amplified through an all-diode-pumped, burst-mode amplifier. A physics-based model of pulse doublet amplification in the burst-mode amplifier is developed and used to accurately predict oscillator pulse width and pulse intensity inputs required to generate equal-energy pulse doublets at 532 nm for velocity measurements. The effect of PIV particle response and high-speed-detector limitations on the spatial and temporal resolution are estimated in subsonic turbulent jets. An effective spatial resolution of 266-275 µm and temporal resolution of 10 µs are estimated from the 8 × 8 pixel correlation window and inter-doublet time spacing, respectively. This spatiotemporal resolution is sufficient for quantitative assessment of integral time and length scales in highly turbulent jets with Reynolds numbers in the range 15,000-50,000. The temporal dynamic range of the burst-mode PIV measurement is 1200, limited by the 85-ms high-energy portion of the burst and 30-kHz high-frequency noise limit.

  14. Hydrodynamic study of freely swimming shark fish propulsion for marine vehicles using 2D particle image velocimetry.

    PubMed

    Babu, Mannam Naga Praveen; Mallikarjuna, J M; Krishnankutty, P

    Two-dimensional velocity fields around a freely swimming freshwater black shark fish in longitudinal (XZ) plane and transverse (YZ) plane are measured using digital particle image velocimetry (DPIV). By transferring momentum to the fluid, fishes generate thrust. Thrust is generated not only by its caudal fin, but also using pectoral and anal fins, the contribution of which depends on the fish's morphology and swimming movements. These fins also act as roll and pitch stabilizers for the swimming fish. In this paper, studies are performed on the flow induced by fins of freely swimming undulatory carangiform swimming fish (freshwater black shark, L = 26 cm) by an experimental hydrodynamic approach based on quantitative flow visualization technique. We used 2D PIV to visualize water flow pattern in the wake of the caudal, pectoral and anal fins of swimming fish at a speed of 0.5-1.5 times of body length per second. The kinematic analysis and pressure distribution of carangiform fish are presented here. The fish body and fin undulations create circular flow patterns (vortices) that travel along with the body waves and change the flow around its tail to increase the swimming efficiency. The wake of different fins of the swimming fish consists of two counter-rotating vortices about the mean path of fish motion. These wakes resemble like reverse von Karman vortex street which is nothing but a thrust-producing wake. The velocity vectors around a C-start (a straight swimming fish bends into C-shape) maneuvering fish are also discussed in this paper. Studying flows around flapping fins will contribute to design of bioinspired propulsors for marine vehicles.

  15. Experimental Approach to Visualize Flow in a Stacked Hollow Fiber Bundle of an Artificial Lung With Particle Image Velocimetry.

    PubMed

    Kaesler, Andreas; Schlanstein, Peter C; Hesselmann, Felix; Büsen, Martin; Klaas, Michael; Roggenkamp, Dorothee; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta

    2016-12-07

    Flow distribution is key in artificial lungs, as it directly influences gas exchange performance as well as clot forming and blood damaging potential. The current state of computational fluid dynamics (CFD) in artificial lungs can only give insight on a macroscopic level due to model simplification applied to the fiber bundle. Based on our recent work on wound fiber bundles, we applied particle image velocimetry (PIV) to the model of an artificial lung prototype intended for neonatal use to visualize flow distribution in a stacked fiber bundle configuration to (i) evaluate the feasibility of PIV for artificial lungs, (ii) validate CFD in the fiber bundle of artificial lungs, and (iii) give a suggestion how to incorporate microscopic aspects into mainly macroscopic CFD studies. To this end, we built a fully transparent model of an artificial lung prototype. To increase spatial resolution, we scaled up the model by a factor of 5.8 compared with the original size. Similitude theory was applied to ensure comparability of the flow distribution between the device of original size and the scaled-up model. We focused our flow investigation on an area (20 × 70 × 43 mm) in a corner of the model with a Stereo-PIV setup. PIV data was compared to CFD data of the original sized artificial lung. From experimental PIV data, we were able to show local flow acceleration and declaration in the fiber bundle and meandering flow around individual fibers, which is not possible using state-of-the-art macroscopic CFD simulations. Our findings are applicable to clinically used artificial lungs with a similar stacked fiber arrangement (e.g., Novalung iLa and Maquet QUADROX-I). With respect to some limitations, we found PIV to be a feasible experimental flow visualization technique to investigate blood-sided flow in the stacked fiber arrangement of artificial lungs.

  16. Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

    DOE PAGES

    Coriton, Bruno; Frank, Jonathan H.

    2016-02-16

    In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet withmore » Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal to s3¯.« less

  17. Study of the vortex-induced pressure excitation source in a Francis turbine draft tube by particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Favrel, A.; Müller, A.; Landry, C.; Yamamoto, K.; Avellan, F.

    2015-12-01

    Francis turbines operating at part-load experience the development of a precessing cavitation vortex rope at the runner outlet, which acts as an excitation source for the hydraulic system. In case of resonance, the resulting pressure pulsations seriously compromise the stability of the machine and of the electrical grid to which it is connected. As such off-design conditions are increasingly required for the integration of unsteady renewable energy sources into the existing power system, an accurate assessment of the hydropower plant stability is crucial. However, the physical mechanisms driving this excitation source remain largely unclear. It is for instance essential to establish the link between the draft tube flow characteristics and the intensity of the excitation source. In this study, a two-component particle image velocimetry system is used to investigate the flow field at the runner outlet of a reduced-scale physical model of a Francis turbine. The discharge value is varied from 55 to 81 % of the value at the best efficiency point. A particular set-up is designed to guarantee a proper optical access across the complex geometry of the draft tube elbow. Based on phase-averaged velocity fields, the evolution of the vortex parameters with the discharge, such as the trajectory and the circulation, is determined for the first time. It is shown that the rise in the excitation source intensity is induced by an enlargement of the vortex trajectory and a simultaneous increase in the precession frequency, as well as the vortex circulation. Below a certain value of discharge, the structure of the vortex abruptly changes and loses its coherence, leading to a drastic reduction in the intensity of the induced excitation source.

  18. High accuracy measurement of unsteady flows using digital particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Funes-Gallanzi, M.

    1998-09-01

    The analysis of digital PIV data, either derived from CCD technology or through film and then scanned, typically involves two quantization steps: spatial and intensity quantization. The all-optical systems do not introduce these sources of error. For systems which make use of digital technology however, it is of crucial importance to have reliable error bounds and a sufficiently accurate estimate of particle position, taking into consideration both types of quantization. The accuracy demanded by aerodynamicists from PIV has been a major barrier to its practical application in the past. The more recent approach of using the Gaussian profile of the particle images to yield sub-pixel accurate position estimates has resulted in robust measurements being taken to an accuracy of 1/10th pixel and 1% in velocity for the in-plane velocity, in hostile industrial environments. A major problem for 3D PIV estimation has historically been that the out-of-plane velocity error was of the order of 3-4 times larger than in-plane. The out-of-plane velocity estimate can be derived from the change in the ratio of amplitude to variance—known as the depth factor—of the Gaussian form, as a particle traverses the beam profile. However, such measurements are crucially dependent not only on an accurate position estimate but also on an equally accurate estimate of the amplitude and variance. The accuracy of the Gaussian profile fit using a Nelder-Meade optimisation method as developed until now however, is not capable of providing the required accuracies. Therefore, this paper presents a development of the "locales" approach to position estimation to achieve the desired objective of high accuracy PIV measurements. This approach makes use of the fact that by considering all the possible digital representations of the Gaussian particle profile, regions of indistinguishable position can be derived. These positions are referred to as "locales". By considering the density, distribution, and

  19. The application of PIV (particle image velocimetry) to long range transonic flow measurements

    SciTech Connect

    Bryanston-Cross, P.J.

    1995-12-31

    A number of PIV (particle image velocity) measurements have been made at transonic speeds. The initial objective of the work has been to explore if such measurements could be made remotely and processed in an accurate and automatic fashion. Subsequently PIV measurements have been made remotely at optical stand-off distance of up to 1m. PIV results are presented, made at ARA Bedford on a 1/12th scale model of an Airbus wing, where a separation induced shock has been measured in three dimensions. The paper also presents results achieved using PIV at DRA Pyestock in mapping the flow within a full size annular turbine cascade with a velocity measurement accuracy of 1%. Measurements are presented showing the wake measured downstream of an annular turbine stator row. The measurements clearly show the presence of a vortex street which has a width of approximately 3mm.

  20. Application of PIV (particle image velocimetry) to long-range transonic flow measurements

    NASA Astrophysics Data System (ADS)

    Bryanston-Cross, Peter J.

    1995-09-01

    A number of PIV (Particle Image Velocity) measurements have been made at transonic speeds. The initial objective of the work has been to explore if such measurements could be made remotely and processed in an accurate and automatic fashion. Subsequently PIV measurements have been made remotely at optical stand-off distance of up to 1 m. PIV results are presented, made at ARA Bedford on a 1/12 th scale model of an Airbus wing, where a separation induced shock has been measured in three dimensions. The paper also presents results achieve using PIV at DRA Pyestock in mapping the flow within a full size annular turbine cascade with a velocity measurement accuracy of 1%. Measurements are presented showing the wake measured downstream of a annular turbine stator row. The measurements clearly show the presence of a vortex street which has a width of approximately 3 mm.

  1. Physical stress testing of bovine jugular veins using magnetic resonance imaging, echocardiography and electrical velocimetry.

    PubMed

    Boethig, Dietmar; Ernst, Franziska; Sarikouch, Samir; Norozi, Kambiz; Lotz, Joachim; Opherk, Jan Patrick; Meister, Maren; Breymann, Thomas

    2010-06-01

    Bovine jugular veins (BJVs) (Contegra) are valve-bearing pulmonary artery substitutes. Their valves have higher profiles than human pulmonary valves; this might result in less optimal performance. Therefore, we investigated the impact of stress and undersizing on conduit performance with ergometry, echocardiography and magnetic resonance imaging (MRI). Between April 2007 and June 2008, 20 BJV recipients (age 7.9-19.6 years) underwent spiroergometry and subsequent echocardiography; after due rest, ergometry was repeated and followed by MRI during recovery. A year later, exams were repeated. Data was evaluated as follows: comparison of stress related maximal individual valve performance changes (magnetic resonance: exercise induced average stroke volume changes by 61+/-49%; mean insufficiency increased by 2% in patients with <1% rest insufficiency and by 8% after rest insufficiency of >10%; the average rest gradient of 24+/-11 mmHg rose to 40+/-20 mmHg), and stratification of pooled observations by regurgitation fraction, insufficiency grades and z-values (insufficiency rose with increasing heart rate and decreasing stroke volume; undersizing increased gradients during recovery by 7+/-0.7 mmHg/z-value). Contegras high-profile valves tolerate stress without performance drop. Stress induced changes of insufficiency and gradient were clinically not significant, but sufficient to distort examination results; therefore, constant examination conditions are indispensable for a correct follow-up.

  2. Particle image velocimetry measurement of steady, transitional, and turbulent flow in a randomly packed porous media

    NASA Astrophysics Data System (ADS)

    Ziazi, R. M.; Liburdy, J.; Apte, S.; Wood, B. D.

    2015-12-01

    The sequential transient regime of the flow through randomly packed porous media has been observed experimentally from steady inertial to turbulent flow. Considering the inherent constraints in visualization and measurements in porous media, the characterization has been performed using time resolved PIV in a randomly packed ordered array of spheres with uniform size. The size of the spheres are 15 mm and the pore Reynolds numbers are set to be 300, 500, and 900. The test bed has a cross-section of 70×70 mm and a height of 15mm. In addition to the difficult accessibility to the interrogation window, the challenges of visualizing the flow in this porous structure is matching of refractive indices of the fluid and solid phase as slight mismatches have been shown to cause significant tracking errors. The 2-D velocity field has been captured at discrete planar locations along the optical axis through the test bed to study the physics and statistics of the flow. Variations occur in the imaging magnification, and if not taken into consideration may lead to increased error. This study addresses three forms of error in PIV as they pertain to porous media flow: tracking error, bias error due to displacement gradients and perspective error. The bias error due to displacement gradients was evaluated from correlation peak width. Direct Numerical Simulation is also being performed to investigate the transitional and turbulent flow in porous media in detail.

  3. Multilaboratory particle image velocimetry analysis of the FDA benchmark nozzle model to support validation of computational fluid dynamics simulations.

    PubMed

    Hariharan, Prasanna; Giarra, Matthew; Reddy, Varun; Day, Steven W; Manning, Keefe B; Deutsch, Steven; Stewart, Sandy F C; Myers, Matthew R; Berman, Michael R; Burgreen, Greg W; Paterson, Eric G; Malinauskas, Richard A

    2011-04-01

    This study is part of a FDA-sponsored project to evaluate the use and limitations of computational fluid dynamics (CFD) in assessing blood flow parameters related to medical device safety. In an interlaboratory study, fluid velocities and pressures were measured in a nozzle model to provide experimental validation for a companion round-robin CFD study. The simple benchmark nozzle model, which mimicked the flow fields in several medical devices, consisted of a gradual flow constriction, a narrow throat region, and a sudden expansion region where a fluid jet exited the center of the nozzle with recirculation zones near the model walls. Measurements of mean velocity and turbulent flow quantities were made in the benchmark device at three independent laboratories using particle image velocimetry (PIV). Flow measurements were performed over a range of nozzle throat Reynolds numbers (Re(throat)) from 500 to 6500, covering the laminar, transitional, and turbulent flow regimes. A standard operating procedure was developed for performing experiments under controlled temperature and flow conditions and for minimizing systematic errors during PIV image acquisition and processing. For laminar (Re(throat)=500) and turbulent flow conditions (Re(throat)≥3500), the velocities measured by the three laboratories were similar with an interlaboratory uncertainty of ∼10% at most of the locations. However, for the transitional flow case (Re(throat)=2000), the uncertainty in the size and the velocity of the jet at the nozzle exit increased to ∼60% and was very sensitive to the flow conditions. An error analysis showed that by minimizing the variability in the experimental parameters such as flow rate and fluid viscosity to less than 5% and by matching the inlet turbulence level between the laboratories, the uncertainties in the velocities of the transitional flow case could be reduced to ∼15%. The experimental procedure and flow results from this interlaboratory study (available

  4. Flow tracing microparticle sensors designed for enhanced X-ray contrast.

    PubMed

    Lee, Sang Joon; Jung, Sung Yong; Ahn, Sungsook

    2010-03-15

    In applying the X-ray particle image velocimetry (PIV) technique to biofluid flows, the most pivotal prerequisite is suitable flow tracing sensors which should be detected effectively by the X-ray imaging system. In this study, to design those flow tracing sensors, X-ray contrast agent Iopamidol was encapsulated into the poly(vinyl alcohol) (PVA) microparticles crosslinked by glutaraldehyde (GA). The characteristics of the fabricated particle sensors were determined by optical microscopy, scanning electron microscopy, dynamic light scattering, laser Doppler electrophoresis and nuclear magnetic resonance spectroscopy ((1)H NMR). The amount of Iopamidol in the microparticles was measured using the energy dispersive X-ray spectroscopy (EDS) and (1)H NMR. The physical properties of the PVA microparticles are effectively controlled in terms of the average particle size, degree of crosslinking, degree of swelling and encapsulation efficiency of Iopamidol. By changing the amount of crosslinker, the degree of crosslinking and the efficiency of the Iopamidol encapsulation reached to the optimal. To some extent, the zeta-potential of the PVA microparticles is increased in less ionic media where the particles can effectively repel each other prohibiting aggregation. The X-ray absorption ability of the designed tracing sensors was examined by a synchrotron X-ray imaging technique. The X-ray absorption coefficients of the particle sensors were expressed by an exponential law assuming the spherical shape of the microparticles. The X-ray contrast agent, Iopamidol, was successfully encapsulated into the bio-compatible and bio-degradable PVA. With the controlled physical properties of the flow tracing sensors designed in this study, the particle sensors exhibit excellent X-ray absorption contrast fairly applicable in biological systems.

  5. Complex flow patterns in a real-size intracranial aneurysm phantom: phase contrast MRI compared with particle image velocimetry and computational fluid dynamics.

    PubMed

    van Ooij, P; Guédon, A; Poelma, C; Schneiders, J; Rutten, M C M; Marquering, H A; Majoie, C B; VanBavel, E; Nederveen, A J

    2012-01-01

    The aim of this study was to validate the flow patterns measured by high-resolution, time-resolved, three-dimensional phase contrast MRI in a real-size intracranial aneurysm phantom. Retrospectively gated three-dimensional phase contrast MRI was performed in an intracranial aneurysm phantom at a resolution of 0.2 × 0.2 × 0.3 mm(3) in a solenoid rat coil. Both steady and pulsatile flows were applied. The phase contrast MRI measurements were compared with particle image velocimetry measurements and computational fluid dynamics simulations. A quantitative comparison was performed by calculating the differences between the magnitude of the velocity vectors and angles between the velocity vectors in corresponding voxels. Qualitative analysis of the results was executed by visual inspection and comparison of the flow patterns. The root-mean-square errors of the velocity magnitude in the comparison between phase contrast MRI and computational fluid dynamics were 5% and 4% of the maximum phase contrast MRI velocity, and the medians of the angle distribution between corresponding velocity vectors were 16° and 14° for the steady and pulsatile measurements, respectively. In the phase contrast MRI and particle image velocimetry comparison, the root-mean-square errors were 12% and 10% of the maximum phase contrast MRI velocity, and the medians of the angle distribution between corresponding velocity vectors were 19° and 15° for the steady and pulsatile measurements, respectively. Good agreement was found in the qualitative comparison of flow patterns between the phase contrast MRI measurements and both particle image velocimetry measurements and computational fluid dynamics simulations. High-resolution, time-resolved, three-dimensional phase contrast MRI can accurately measure complex flow patterns in an intracranial aneurysm phantom.

  6. Morphotype-Dependent Flow Characteristics in Bicuspid Aortic Valve Ascending Aortas: A Benchtop Particle Image Velocimetry Study

    PubMed Central

    McNally, Andrew; Madan, Ashish; Sucosky, Philippe

    2017-01-01

    The bicuspid aortic valve (BAV) is a major risk factor for secondary aortopathy such as aortic dilation. The heterogeneous BAV morphotypes [left-right-coronary cusp fusion (LR), right-non-coronary cusp fusion (RN), and left-non-coronary cusp fusion (LN)] are associated with different dilation patterns, suggesting a role for hemodynamics in BAV aortopathogenesis. However, assessment of this theory is still hampered by the limited knowledge of the hemodynamic abnormalities generated by the distinct BAV morphotypes. The objective of this study was to compare experimentally the hemodynamics of a normal (i.e., non-dilated) ascending aorta (AA) subjected to tricuspid aortic valve (TAV), LR-BAV, RN-BAV, and NL-BAV flow. Tissue BAVs reconstructed from porcine TAVs were subjected to physiologic pulsatile flow conditions in a left-heart simulator featuring a realistic aortic root and compliant aorta. Phase-locked particle image velocimetry experiments were carried out to characterize the flow in the aortic root and in the tubular AA in terms of jet skewness and displacement, as well as mean velocity, viscous shear stress and Reynolds shear stress fields. While all three BAVs generated skewed and asymmetrical orifice jets (up to 1.7- and 4.0-fold increase in flow angle and displacement, respectively, relative to the TAV at the sinotubular junction), the RN-BAV jet was out of the plane of observation. The LR- and NL-BAV exhibited a 71% increase in peak-systolic orifice jet velocity relative to the TAV, suggesting an inherent degree of stenosis in BAVs. While these two BAV morphotypes subjected the convexity of the aortic wall to viscous shear stress overloads (1.7-fold increase in maximum peak-systolic viscous shear stress relative to the TAV-AA), the affected sites were morphotype-dependent (LR-BAV: proximal AA, NL-BAV: distal AA). Lastly, the LR- and NL-BAV generated high degrees of turbulence in the AA (up to 2.3-fold increase in peak-systolic Reynolds shear stress relative

  7. Morphotype-Dependent Flow Characteristics in Bicuspid Aortic Valve Ascending Aortas: A Benchtop Particle Image Velocimetry Study.

    PubMed

    McNally, Andrew; Madan, Ashish; Sucosky, Philippe

    2017-01-01

    The bicuspid aortic valve (BAV) is a major risk factor for secondary aortopathy such as aortic dilation. The heterogeneous BAV morphotypes [left-right-coronary cusp fusion (LR), right-non-coronary cusp fusion (RN), and left-non-coronary cusp fusion (LN)] are associated with different dilation patterns, suggesting a role for hemodynamics in BAV aortopathogenesis. However, assessment of this theory is still hampered by the limited knowledge of the hemodynamic abnormalities generated by the distinct BAV morphotypes. The objective of this study was to compare experimentally the hemodynamics of a normal (i.e., non-dilated) ascending aorta (AA) subjected to tricuspid aortic valve (TAV), LR-BAV, RN-BAV, and NL-BAV flow. Tissue BAVs reconstructed from porcine TAVs were subjected to physiologic pulsatile flow conditions in a left-heart simulator featuring a realistic aortic root and compliant aorta. Phase-locked particle image velocimetry experiments were carried out to characterize the flow in the aortic root and in the tubular AA in terms of jet skewness and displacement, as well as mean velocity, viscous shear stress and Reynolds shear stress fields. While all three BAVs generated skewed and asymmetrical orifice jets (up to 1.7- and 4.0-fold increase in flow angle and displacement, respectively, relative to the TAV at the sinotubular junction), the RN-BAV jet was out of the plane of observation. The LR- and NL-BAV exhibited a 71% increase in peak-systolic orifice jet velocity relative to the TAV, suggesting an inherent degree of stenosis in BAVs. While these two BAV morphotypes subjected the convexity of the aortic wall to viscous shear stress overloads (1.7-fold increase in maximum peak-systolic viscous shear stress relative to the TAV-AA), the affected sites were morphotype-dependent (LR-BAV: proximal AA, NL-BAV: distal AA). Lastly, the LR- and NL-BAV generated high degrees of turbulence in the AA (up to 2.3-fold increase in peak-systolic Reynolds shear stress relative

  8. Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

    SciTech Connect

    Coriton, Bruno; Frank, Jonathan H.

    2016-02-16

    In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet with Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal

  9. Locomotor forces on a swimming fish: three-dimensional vortex wake dynamics quantified using digital particle image velocimetry.

    PubMed

    Drucker; Lauder

    1999-01-01

    Quantifying the locomotor forces experienced by swimming fishes represents a significant challenge because direct measurements of force applied to the aquatic medium are not feasible. However, using the technique of digital particle image velocimetry (DPIV), it is possible to quantify the effect of fish fins on water movement and hence to estimate momentum transfer from the animal to the fluid. We used DPIV to visualize water flow in the wake of the pectoral fins of bluegill sunfish (Lepomis macrochirus) swimming at speeds of 0.5-1.5 L s(-)(1), where L is total body length. Velocity fields quantified in three perpendicular planes in the wake of the fins allowed three-dimensional reconstruction of downstream vortex structures. At low swimming speed (0.5 L s(-)(1)), vorticity is shed by each fin during the downstroke and stroke reversal to generate discrete, roughly symmetrical, vortex rings of near-uniform circulation with a central jet of high-velocity flow. At and above the maximum sustainable labriform swimming speed of 1.0 L s(-)(1), additional vorticity appears on the upstroke, indicating the production of linked pairs of rings by each fin. Fluid velocity measured in the vicinity of the fin indicates that substantial spanwise flow during the downstroke may occur as vortex rings are formed. The forces exerted by the fins on the water in three dimensions were calculated from vortex ring orientation and momentum. Mean wake-derived thrust (11.1 mN) and lift (3.2 mN) forces produced by both fins per stride at 0.5 L s(-)(1) were found to match closely empirically determined counter-forces of body drag and weight. Medially directed reaction forces were unexpectedly large, averaging 125 % of the thrust force for each fin. Such large inward forces and a deep body that isolates left- and right-side vortex rings are predicted to aid maneuverability. The observed force balance indicates that DPIV can be used to measure accurately large-scale vorticity in the wake of

  10. Fluid mechanic assessment of the total cavopulmonary connection using magnetic resonance phase velocity mapping and digital particle image velocimetry.

    PubMed

    Ensley, A E; Ramuzat, A; Healy, T M; Chatzimavroudis, G P; Lucas, C; Sharma, S; Pettigrew, R; Yoganathan, A P

    2000-01-01

    The total cavopulmonary connection (TCPC) is currently the most promising modification of the Fontan surgical repair for single ventricle congenital heart disease. The TCPC involves a surgical connection of the superior and inferior vena cavae directly to the left and right pulmonary arteries, bypassing the right heart. In the univentricular system, the ventricle experiences a workload which may be reduced by optimizing the cavae-to-pulmonary anastomosis. The hypothesis of this study was that the energetic efficiency of the connection is a consequence of the fluid dynamics which develop as a function of connection geometry. Magnetic resonance phase velocity mapping (MRPVM) and digital particle image velocimetry (DPIV) were used to evaluate the flow patterns in vitro in three prototype glass models of the TCPC: flared zero offset, flared 14 mm offset, and straight 21 mm offset. The flow field velocity along the symmetry plane of each model was chosen to elucidate the fluid mechanics of the connection as a function of the connection geometry and pulmonary artery flow split. The steady flow experiments were conducted at a physiologic cardiac output (4 L/min) over three left/right pulmonary flow splits (70/30, 50/50, and 30/70) while keeping the superior/inferior vena cavae flow ratio constant at 40/60. MRPVM, a noninvasive clinical technique for measuring flow field velocities, was compared to DPIV, an established in vitro fluid mechanic technique. A comparison between the results from both techniques showed agreement of large scale flow features, despite some discrepancies in the detailed flow fields. The absence of caval offset in the flared zero offset model resulted in significant caval flow collision at the connection site. In contrast, offsetting the cavae reduced the flow interaction and caused a vortex-like low velocity region between the caval inlets as well as flow disturbance in the pulmonary artery with the least total flow. A positive correlation was also

  11. Tomographic particle-image velocimetry and thermography in Rayleigh-Bénard convection using suspended thermochromic liquid crystals and digital image processing

    NASA Astrophysics Data System (ADS)

    Ciofalo, M.; Signorino, M.; Simiano, M.

    2003-02-01

    Steady-state flow and temperature fields in shallow rectangular enclosures heated from below were visualized and quantitatively characterized by using glycerol as the working fluid and suspended thermochromic liquid crystals as tracers. Couples of photographs taken on 120 transparency film for two orthogonal sets of vertical plane sections were digitized by a 1,200-dpi flatbed scanner and split into HSL (hue-saturation-lightness) components by using commercial general-purpose image processing software. Two-dimensional velocity fields were obtained from the lightness component by a two-frame cross-correlation technique using a commercial particle-image velocimetry (PIV) package. Temperature fields were obtained from the hue component on the basis of an in situ calibration procedure, conducted under conditions of stable thermal stratification. Finally, 2D flow and temperature distributions were interpolated by a purpose-written Fortran program to give 3D flow and thermal fields in the enclosure. Results are presented here for the case of a 1:2:4 aspect ratio cavity at a Rayleigh number of ˜ 14,500, for which a complex 3D flow and temperature distribution was observed.

  12. Development of a custom-designed echo particle image velocimetry system for multi-component hemodynamic measurements: system characterization and initial experimental results

    NASA Astrophysics Data System (ADS)

    Liu, Lingli; Zheng, Hairong; Williams, Logan; Zhang, Fuxing; Wang, Rui; Hertzberg, Jean; Shandas, Robin

    2008-03-01

    We have recently developed an ultrasound-based velocimetry technique, termed echo particle image velocimetry (Echo PIV), to measure multi-component velocity vectors and local shear rates in arteries and opaque fluid flows by identifying and tracking flow tracers (ultrasound contrast microbubbles) within these flow fields. The original system was implemented on images obtained from a commercial echocardiography scanner. Although promising, this system was limited in spatial resolution and measurable velocity range. In this work, we propose standard rules for characterizing Echo PIV performance and report on a custom-designed Echo PIV system with increased spatial resolution and measurable velocity range. Then we employed this system for initial measurements on tube flows, rotating flows and in vitro carotid artery and abdominal aortic aneurysm (AAA) models to acquire the local velocity and shear rate distributions in these flow fields. The experimental results verified the accuracy of this technique and indicated the promise of the custom Echo PIV system in capturing complex flow fields non-invasively.

  13. Dynamic mode decomposition of separated flow over a finite blunt plate: time-resolved particle image velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Liu, Yingzheng; Zhang, Qingshan

    2015-07-01

    Dynamic mode decomposition (DMD) analysis was performed on a large number of realizations of the separated flow around a finite blunt plate, which were determined by using planar time-resolved particle image velocimetry (TR-PIV). Three plates with different chord-to-thickness ratios corresponding to globally different flow patterns were particularly selected for comparison: L/D = 3.0, 6.0 and 9.0. The main attention was placed on dynamic variations in the dominant events and their interactive influences on the global fluid flow in terms of the DMD analysis. Toward this end, a real-time data transfer from the high-speed camera to the arrayed disks was built to enable continuous sampling of the spatiotemporally varying flows at the frequency of 250 Hz for a long run. The spectra of the wall-normal velocity fluctuation, the energy spectra of the DMD modes, and their spatial patterns convincingly determined the energetic unsteady events, i.e., St = 0.051 (Karman vortex street), 0.109 (harmonic event of Karman vortex street) and 0.197 (leading-edge vortex) in the shortest system L/D = 3.0, St = 0.159 (Karman vortex street) and 0.242 (leading-edge vortex) in the system L/D = 6.0, and St = 0.156 (Karman vortex street) and 0.241 (leading-edge vortex) in the longest system L/D = 9.0. In the shortest system L/D = 3.0, the first DMD mode pattern demonstrated intensified entrainment of the massive fluid above and below the whole plate by the Karman vortex street. The phase-dependent variation in the low-order flow field elucidated that this motion was sustained by the consecutive mechanisms of the convective leading-edge vortices near the upper and lower trailing edges, and the large-scale vortical structures occurring immediately behind the trailing edge, whereas the leading-edge vortices were entrained and decayed into the near wake. For the system L/D = 6.0, the closely approximated energy spectra at St = 0.159 and 0.242 indicated the balanced dominance of dual unsteady

  14. PARTICLE IMAGE VELOCIMETRY MEASUREMENTS IN A REPRESENTATIVE GAS-COOLED PRISMATIC REACTOR CORE MODEL: FLOW IN THE COOLANT CHANNELS AND INTERSTITIAL BYPASS GAPS

    SciTech Connect

    Thomas E. Conder; Richard Skifton; Ralph Budwig

    2012-11-01

    Core bypass flow is one of the key issues with the prismatic Gas Turbine-Modular Helium Reactor, and it refers to the coolant that navigates through the interstitial, non-cooling passages between the graphite fuel blocks instead of traveling through the designated coolant channels. To determine the bypass flow, a double scale representative model was manufactured and installed in the Matched Index-of-Refraction flow facility; after which, stereo Particle Image Velocimetry (PIV) was employed to measure the flow field within. PIV images were analyzed to produce vector maps, and flow rates were calculated by numerically integrating over the velocity field. It was found that the bypass flow varied between 6.9-15.8% for channel Reynolds numbers of 1,746 and 4,618. The results were compared to computational fluid dynamic (CFD) pre-test simulations. When compared to these pretest calculations, the CFD analysis appeared to under predict the flow through the gap.

  15. Massively parallel manipulation of single cells and microparticles using optical images.

    PubMed

    Chiou, Pei Yu; Ohta, Aaron T; Wu, Ming C

    2005-07-21

    The ability to manipulate biological cells and micrometre-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques--including optical tweezers, electrokinetic forces (electrophoresis, dielectrophoresis, travelling-wave dielectrophoresis), magnetic tweezers, acoustic traps and hydrodynamic flows--cannot achieve high resolution and high throughput at the same time. Optical tweezers offer high resolution for trapping single particles, but have a limited manipulation area owing to tight focusing requirements; on the other hand, electrokinetic forces and other mechanisms provide high throughput, but lack the flexibility or the spatial resolution necessary for controlling individual cells. Here we present an optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. It requires 100,000 times less optical intensity than optical tweezers. Using an incoherent light source (a light-emitting diode or a halogen lamp) and a digital micromirror spatial light modulator, we have demonstrated parallel manipulation of 15,000 particle traps on a 1.3 x 1.0 mm2 area. With direct optical imaging control, multiple manipulation functions are combined to achieve complex, multi-step manipulation protocols.

  16. Massively parallel manipulation of single cells and microparticles using optical images

    NASA Astrophysics Data System (ADS)

    Chiou, Pei Yu; Ohta, Aaron T.; Wu, Ming C.

    2005-07-01

    The ability to manipulate biological cells and micrometre-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques-including optical tweezers, electrokinetic forces (electrophoresis, dielectrophoresis, travelling-wave dielectrophoresis), magnetic tweezers, acoustic traps and hydrodynamic flows-cannot achieve high resolution and high throughput at the same time. Optical tweezers offer high resolution for trapping single particles, but have a limited manipulation area owing to tight focusing requirements; on the other hand, electrokinetic forces and other mechanisms provide high throughput, but lack the flexibility or the spatial resolution necessary for controlling individual cells. Here we present an optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. It requires 100,000 times less optical intensity than optical tweezers. Using an incoherent light source (a light-emitting diode or a halogen lamp) and a digital micromirror spatial light modulator, we have demonstrated parallel manipulation of 15,000 particle traps on a 1.3 × 1.0mm2 area. With direct optical imaging control, multiple manipulation functions are combined to achieve complex, multi-step manipulation protocols.

  17. Fundamental experiments in velocimetry

    SciTech Connect

    Briggs, Matthew Ellsworth; Hull, Larry; Shinas, Michael

    2009-01-01

    One can understand what velocimetry does and does not measure by understanding a few fundamental experiments. Photon Doppler Velocimetry (PDV) is an interferometer that will produce fringe shifts when the length of one of the legs changes, so we might expect the fringes to change whenever the distance from the probe to the target changes. However, by making PDV measurements of tilted moving surfaces, we have shown that fringe shifts from diffuse surfaces are actually measured only from the changes caused by the component of velocity along the beam. This is an important simplification in the interpretation of PDV results, arising because surface roughness randomizes the scattered phases.

  18. Fuzzy logic particle tracking velocimetry

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1993-01-01

    Fuzzy logic has proven to be a simple and robust method for process control. Instead of requiring a complex model of the system, a user defined rule base is used to control the process. In this paper the principles of fuzzy logic control are applied to Particle Tracking Velocimetry (PTV). Two frames of digitally recorded, single exposure particle imagery are used as input. The fuzzy processor uses the local particle displacement information to determine the correct particle tracks. Fuzzy PTV is an improvement over traditional PTV techniques which typically require a sequence (greater than 2) of image frames for accurately tracking particles. The fuzzy processor executes in software on a PC without the use of specialized array or fuzzy logic processors. A pair of sample input images with roughly 300 particle images each, results in more than 200 velocity vectors in under 8 seconds of processing time.

  19. Simultaneous particle image velocimetry and chemiluminescence visualization of millisecond-pulsed current-voltage-induced perturbations of a premixed propane/air flame

    NASA Astrophysics Data System (ADS)

    Schmidt, Jacob; Kostka, Stanislav; Lynch, Amy; Ganguly, Biswa

    2011-09-01

    The effects of millisecond-wide, pulsed current-voltage-induced behavior in premixed laminar flames have been investigated through the simultaneous collection of particle image velocimetry (PIV) and chemiluminescence data with particular attention paid to the onset mechanisms. Disturbances caused by applied voltages of 2 kV over a 30-mm gap to a downward propagating, atmospheric pressure, premixed propane/air flame with a flow speed near 2 m/s and an equivalence ratio of 1.06 are investigated. The combined PIV and chemiluminescence-based experimental data show the observed disturbance originates only in or near the cathode fall region very close to the burner base. The data also suggest that the coupling mechanism responsible for the flame disturbance behavior is fluidic in nature, developing from the radial positive chemi-ion distribution and an ion-drift current-induced net body force that acts along the annular space discharge distribution in the reaction zone in or near the cathode fall. This net body force causes a reduction in flow speed above these near cathodic regions causing the base of the flame to laterally spread. Also, this effect seems to produce a velocity gradient leading to the transition of a laminar flame to turbulent combustion for higher applied current-voltage conditions as shown in previous work (Marcum and Ganguly in Combust Flame 143:27-36, 2005; Schmidt and Ganguly in 48th AIAA aerospace sciences meeting. Orlando, 2010).

  20. Particle Image Velocimetry Measurements of a Two/Three-dimensional Separating/Reattaching Boundary Layer Downstream of an Axisymmetric Backward-facing Step

    NASA Technical Reports Server (NTRS)

    Hudy, Laura M.; Naguib, Ahmed M.; Humphreys, William M.; Bartram, Scott M.

    2005-01-01

    Planar Particle Image Velocimetry measurements were obtained in the separating/reattaching flow region downstream of an axisymmetric backward-facing step. Data were acquired for a two-dimensional (2D) separating boundary layer at five different Reynolds numbers based on step height (Re(sub h)), spanning 5900-33000, and for a three-dimensional (3D) separating boundary layer at Re(sub h) = 5980 and 8081. Reynolds number effects were investigated in the 2D cases using mean-velocity field, streamwise and wall-normal turbulent velocity, and Reynolds stress statistics. Results show that both the reattachment length (x(sub r)) and the secondary separation point are Reynolds number dependent. The reattachment length increased with rising Re(sub h) while the secondary recirculation region decreased in size. These and other Re(sub h) effects were interpreted in terms of changes in the separating boundary layer thickness and wall-shear stress. On the other hand, in the 3D case, it was found that the imposed cross-flow component was relatively weak in comparison to the streamwise component. As a result, the primary influences of three dimensionality only affected the near-separation region rather than the entire separation bubble.

  1. Stereo Particle Image Velocimetry Measurements of Transition Downstream of a Backward-Facing Step in a Swept-Wing Boundary Layer

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Yao, Chung-Sheng

    2017-01-01

    Stereo particle image velocimetry measurements were performed downstream of a backward-facing step in a stationary-cross flow dominated flow. The PIV measurements exhibit excellent quantitative and qualitative agreement with the previously acquired hotwire data. Instantaneous PIV snapshots reveal new information about the nature and cause of the \\spikes" that occurred prior to breakdown in both the hotwire and PIV data. The PIV snapshots show that the events occur simultaneously across multiple stationary cross flow wavelengths, indicating that this is not simply a local event, but is likely caused by the 2D Tollmien-Schlichting instability that is introduced by the step. While the TS instability is a 2D instability, it is also modulated in the spanwise direction due to interactions with the stationary cross flow, as are the other unsteady disturbances present. Because of this modulation, the "spike" events cause an instantaneous increase of the spanwise modulation of the streamwise and spanwise velocity initially caused by the stationary cross flow. Breakdown appears to be caused by this instantaneous modulation, possibly due to a high-frequency secondary instability similar to a traveling-cross flow breakdown scenario. These results further illuminate the respective roles of the stationary cross flow and unsteady disturbances in transition downstream of a backward-facing step.

  2. Large-scale time-resolved digital particle image velocimetry (TR-DPIV) for measurement of high subsonic hot coaxial jet exhaust of a gas turbine engine

    NASA Astrophysics Data System (ADS)

    Timmerman, B. H.; Skeen, A. J.; Bryanston-Cross, P. J.; Graves, M. J.

    2009-07-01

    The development of a highly configurable triple digital particle image velocimetry (DPIV) system is described, which is capable of acquiring both continuous, statistically independent measurements at up to 14 Hz and time-resolved PIV data at MHz rates. The system was used at QinetiQ's Noise Test Facility (NTF) as part of the EU-funded CoJeN programme to obtain measurements from high subsonic (Mach <= 0.9), hot (~500 °C), large (1/10th) scale coaxial jet flows at a standoff distance of ~1 m. High-resolution time-averaged velocity and turbulence data were obtained for complete coaxial engine exhaust plumes down to 4 m (20 jet diameters) from the nozzle exit in less than 1 h. In addition, the system allowed volumetric data to be obtained, enabling fast assessment of spatial alignment of nozzle configurations. Furthermore, novel six-frame time-series data-capture is demonstrated up to 330 kHz, used to calculate time-space correlations within the exhaust, allowing for study of spatio-temporal developments in the jet, associated with jet-noise production. The highly automated system provides synchronization triggers for simultaneous acquisition from different measurement systems (e.g. LDA) and is shown to be versatile, rugged, reliable and portable, operating remotely in a hostile environment. Data are presented for three operating conditions and two nozzle geometries, providing a database to be used to validate CFD models of coaxial jet flow.

  3. Characterization of the activity of ultrasound emitted in a perpendicular liquid flow using Particle Image Velocimetry (PIV) and electrochemical mass transfer measurements.

    PubMed

    Barthès, Magali; Mazue, Gerald; Bonnet, Dimitri; Viennet, Remy; Hihn, Jean-Yves; Bailly, Yannick

    2015-05-01

    The present work is dedicated to the study of the interactions between a liquid circulation and a perpendicular acoustic wave propagation. A specific experimental setup was designed to study one transducer operating at 20 kHz, with the help of electrochemical mass transfer measurements combined with Particle Image Velocimetry (PIV) determination. Electrodes were located on the wall opposite to the acoustic emission. Experiments were performed for various Reynolds numbers: from 0 to 21700 (different liquid flow rates and viscosities). Both PIV and electrochemical measurements methods were found to be relevant, and had delivered complementary information. Even if PIV showed that the plume due to streaming was highly deflected by the additional flow, electrochemical measurements showed that there was still an activity, higher than in silent conditions, on the wall facing the transducer. Thus the ultrasound contribution remained noticeable on the surface opposite to the transducer even for a disturbed hydrodynamic environment due to the presence of a liquid circulation perpendicular to the wave propagation.

  4. Microparticles of Aloe vera/vitamin E/chitosan: microscopic, a nuclear imaging and an in vivo test analysis for burn treatment.

    PubMed

    Pereira, Gabriela Garrastazu; Santos-Oliveira, Ralph; Albernaz, Martha S; Canema, Daniel; Weismüller, Gilberto; Barros, Eduardo Bede; Magalhães, Luciana; Lima-Ribeiro, Maria Helena Madruga; Pohlmann, Adriana Raffin; Guterres, Silvia S

    2014-02-01

    The use of drug-loaded nanoparticles and microparticles has been increasing, especially for cosmetic and drug delivery purposes. In this work, a new microparticle formulation was developed for use in the healing process of skin burns in a composition of Aloe vera/vitamin E/chitosan. In order to observe the morphological properties, Raman and atomic force microscopy evaluation were performed. The biodistribution studies were analyzed by using a nuclear methodology, labeling the microparticles with Technetium-99m and in vivo test was procedure to analyzed the cicatrization process. The results of AFM analysis show the formation and the adherence property of the microparticles. Raman analyses show the distribution of each component in the microparticle. The nuclear method used shows that the biodistribution of the microparticles remained in the skin. The in vivo cicatrization test showed that the poloxamer gel containing the microparticles make a better cicatrization in relation to the other formulations tested.

  5. Line-Scanning Particle Image Velocimetry: An Optical Approach for Quantifying a Wide Range of Blood Flow Speeds in Live Animals

    PubMed Central

    Kim, Tyson N.; Goodwill, Patrick W.; Chen, Yeni; Conolly, Steven M.; Schaffer, Chris B.; Liepmann, Dorian; Wang, Rong A.

    2012-01-01

    Background The ability to measure blood velocities is critical for studying vascular development, physiology, and pathology. A key challenge is to quantify a wide range of blood velocities in vessels deep within living specimens with concurrent diffraction-limited resolution imaging of vascular cells. Two-photon laser scanning microscopy (TPLSM) has shown tremendous promise in analyzing blood velocities hundreds of micrometers deep in animals with cellular resolution. However, current analysis of TPLSM-based data is limited to the lower range of blood velocities and is not adequate to study faster velocities in many normal or disease conditions. Methodology/Principal Findings We developed line-scanning particle image velocimetry (LS-PIV), which used TPLSM data to quantify peak blood velocities up to 84 mm/s in live mice harboring brain arteriovenous malformation, a disease characterized by high flow. With this method, we were able to accurately detect the elevated blood velocities and exaggerated pulsatility along the abnormal vascular network in these animals. LS-PIV robustly analyzed noisy data from vessels as deep as 850 µm below the brain surface. In addition to analyzing in vivo data, we validated the accuracy of LS-PIV up to 800 mm/s using simulations with known velocity and noise parameters. Conclusions/Significance To our knowledge, these blood velocity measurements are the fastest recorded with TPLSM. Partnered with transgenic mice carrying cell-specific fluorescent reporters, LS-PIV will also enable the direct in vivo correlation of cellular, biochemical, and hemodynamic parameters in high flow vascular development and diseases such as atherogenesis, arteriogenesis, and vascular anomalies. PMID:22761686

  6. Micro Particle Image Velocimetry Measurements of Steady Diastolic Leakage Flow in the Hinge of a St. Jude Medical® Regent™ Mechanical Heart Valve

    PubMed Central

    Jun, Brian H.; Saikrishnan, Neelakantan; Yoganathan, Ajit P.

    2013-01-01

    A number of clinical, in vitro and computational studies have shown the potential for thromboembolic complications in bileaflet mechanical heart valves (BMHV), primarily due to the complex and unsteady flows in the valve hinges. These studies have focused on quantitative and qualitative parameters such as velocity magnitude, turbulent shear stresses, vortex formation and platelet activation to identify potential for blood damage. However, experimental characterization of the whole flow fields within the valve hinges has not yet been conducted. This information can be utilized to investigate instantaneous damage to blood elements and also to validate numerical studies focusing on the hinge's complex fluid dynamics. The objective of this study was therefore to develop a high-resolution imaging system to characterize the flow fields and global velocity maps in a BMHV hinge. In this study, the steady leakage hinge flow fields representing the diastolic phase during the cardiac cycle in a 23 mm St. Jude Medical (SJM) Regent BMHV in the aortic position were characterized using a two-dimensional Micro Particle Image Velocimetry (μPIV) system. Diastolic flow was simulated by imposing a static pressure head on the aortic side. Under these conditions, a reverse flow jet from the aortic to the ventricular side was observed with velocities in the range of 1.47 to 3.24 m/s, whereas low flow regions were observed on the ventricular side of the hinge with viscous shear stress magnitude up to 60 N/m2. High velocities and viscous shearing may be associated with platelet activation & hemolysis, while low flow zones can cause thrombosis due to increased residence time in the hinge. Overall, this study provides a high spatial resolution experimental technique to map the fluid velocity in the BMHV hinge, which can be extended to investigate micron-scale flow domains in various prosthetic devices under different hemodynamic conditions. PMID:24085344

  7. Identifying and discriminating phase transitions along decaying shocks with line imaging Doppler interferometric velocimetry and streaked optical pyrometry

    SciTech Connect

    Millot, Marius

    2016-01-15

    Ultrafast line-imaging velocity interferometer system for any reflector and streaked optical pyrometry are now commonly used to obtain high precision equation of state and electronic transport data under dynamic compression at major high energy density science facilities. We describe a simple way to improve distinguishing phase transformation signatures from other signals when monitoring decaying shock waves. The line-imaging capability of these optical diagnostics offers additional supporting evidence to the assignment of particular anomalies—such as plateaus or reversals—to the occurrence of a phase transition along the Hugoniot. We illustrate the discussion with two example datasets collected during laser driven shock compression of quartz and stishovite.

  8. Heart wall velocimetry and exogenous contrast-based cardiac flow imaging in Drosophila melanogaster using Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Choma, Michael A.; Suter, Melissa J.; Vakoc, Benjamin J.; Bouma, Brett E.; Tearney, Guillermo J.

    2010-09-01

    Drosophila melanogaster (fruit fly) is a central organism in biology and is becoming increasingly important in the cardiovascular sciences. Prior work in optical imaging of the D. melanogaster heart has focused on static and dynamic structural anatomy. In the study, it is demonstrated that Doppler optical coherence tomography can quantify dynamic heart wall velocity and hemolymph flow in adult D. melanogaster. Since hemolymph is optically transparent, a novel exogenous contrast technique is demonstrated to increase the backscatter-based intracardiac Doppler flow signal. The results presented here open up new possibilities for functional cardiovascular phenotyping of normal and mutant D. melanogaster.

  9. Study of bubble-induced turbulence in upward laminar bubbly pipe flows measured with a two-phase particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Kim, Minki; Lee, Jun Ho; Park, Hyungmin

    2016-04-01

    In the present study, focusing on characterizing the bubble-induced agitation (turbulence), spatially varying flow statistics of gas and liquid phases in laminar upward bubbly flows (Reynolds number of 750) with varying mean void fraction are investigated using a two-phase high-speed particle image velocimetry. As the flow develops along the vertical direction, bubbles with small-to-moderate void fractions, which were intentionally distributed asymmetrically at the inlet, migrate fast and show symmetric distributions of wall or intermediate peaking. Meanwhile, the mean liquid velocity saturates relatively slowly to a flat distribution at the core region. Despite small void fractions considered, the bubbles generate a substantial turbulence, which increases with increasing mean void fraction. Interestingly, it is found that the mean vertical velocity, bubble-induced normal stress in radial direction, and Reynolds stress profiles match well with those of a single-phase turbulent flow at a moderate Reynolds number (e.g., 104), indicating the similarity between the bubble-induced turbulence and wall-shear-generated turbulence in a single-phase flow. Previously suggested scaling relations are confirmed such that the mean bubble rise velocity and bubble-induced normal stress (in both vertical and radial directions) scale with mean volume void fraction as a power of -0.1 and 0.4, respectively. Finally, based on the analysis of measured bubble dynamics (rise in an oscillating path), a theoretical model for two-phase turbulent (Reynolds) stress is proposed, which includes the contributions by the non-uniform distributions of local void fraction and relative bubble rise velocity, and is further validated with the present experimental data to show a good agreement with each other.

  10. Sucking while swimming: evaluating the effects of ram speed on suction generation in bluegill sunfish Lepomis macrochirus using digital particle image velocimetry.

    PubMed

    Higham, Timothy E; Day, Steven W; Wainwright, Peter C

    2005-07-01

    It is well established that suction feeding fish use a variable amount of swimming (ram) during prey capture. However, the fluid mechanical effects of ram on suction feeding are not well established. In this study we quantified the effects of ram on the maximum fluid speed of the water entering the mouth during feeding as well as the spatial patterns of flow entering the mouth of suction-feeding bluegill sunfish Lepomis macrochirus. Using Digital Particle Image Velocimetry (DPIV) and high-speed video, we observed the flow in front of the mouth of three fish using a vertical laser sheet positioned on the mid-sagittal plane of the fish. From this we quantified the maximum fluid speed (measured at a distance in front of the mouth equal to one half of the maximum mouth diameter), the degree of focusing of water flow entering the mouth, and the shape of the ingested volume of water. Ram speed in 41 feeding sequences, measured at the time of maximum gape, ranged between 0 and 25 cm s(-1), and the ratio of ram speed to fluid speed ranged from 0.1% to 19.1%. In a regression ram speed did not significantly affect peak fluid speed, but with an increase in ram speed the degree of focusing of water entering the mouth increased significantly, and the shape of the ingested volume of water became more elongate and narrow. The implications of these findings are that (1) suction feeders that employ ram of between 0% and 20% of fluid speed sacrifice little in terms of the fluid speeds they generate and (2) ram speed enhances the total body closing speed of the predator.

  11. Combined particle-image velocimetry and force analysis of the three-dimensional fluid-structure interaction of a natural owl wing.

    PubMed

    Winzen, A; Roidl, B; Schröder, W

    2016-04-01

    Low-speed aerodynamics has gained increasing interest due to its relevance for the design process of small flying air vehicles. These small aircraft operate at similar aerodynamic conditions as, e.g. birds which therefore can serve as role models of how to overcome the well-known problems of low Reynolds number flight. The flight of the barn owl is characterized by a very low flight velocity in conjunction with a low noise emission and a high level of maneuverability at stable flight conditions. To investigate the complex three-dimensional flow field and the corresponding local structural deformation in combination with their influence on the resulting aerodynamic forces, time-resolved stereoscopic particle-image velocimetry and force and moment measurements are performed on a prepared natural barn owl wing. Several spanwise positions are measured via PIV in a range of angles of attack [Formula: see text] 6° and Reynolds numbers 40 000 [Formula: see text] 120 000 based on the chord length. Additionally, the resulting forces and moments are recorded for -10° ≤ α ≤ 15° at the same Reynolds numbers. Depending on the spanwise position, the angle of attack, and the Reynolds number, the flow field on the wing's pressure side is characterized by either a region of flow separation, causing large-scale vortical structures which lead to a time-dependent deflection of the flexible wing structure or wing regions showing no instantaneous deflection but a reduction of the time-averaged mean wing curvature. Based on the force measurements the three-dimensional fluid-structure interaction is assumed to considerably impact the aerodynamic forces acting on the wing leading to a strong mechanical loading of the interface between the wing and body. These time-depending loads which result from the flexibility of the wing should be taken into consideration for the design of future small flying air vehicles using flexible wing structures.

  12. Stereo Particle Image Velocimetry Measurements of Transition Downstream of a Forward-Facing Step in a Swept-Wing Boundary Layer

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.

    2017-01-01

    Stereo particle image velocimetry measurements were performed downstream of a forward-facing step in a stationary-crossflow dominated flow. Three different step heights were studied with the same leading-edge roughness configuration to determine the effect of the step on the evolution of the stationary-crossflow. Above the critical step height, which is approximately 68% of the boundary-layer thickness at the step, the step caused a significant increase in the growth of the stationary crossflow. For the largest step height studied (68%), premature transition occurred shortly downstream of the step. The stationary crossflow amplitude only reached approximately 7% of U(sub e) in this case, which suggests that transition does not occur via the high-frequency secondary instabilities typically associated with stationary crossflow transition. The next largest step of 60% delta still caused a significant impact on the growth of the stationary crossflow downstream of the step, but the amplitude eventually returned to that of the baseline case, and the transition front remained the same. The smallest step height (56%) only caused a small increase in the stationary crossflow amplitude and no change in the transition front. A final case was studied in which the roughness on the leading edge of the model was enhanced for the lowest step height case to determine the impact of the stationary crossflow amplitude on transition. The stationary crossflow amplitude was increased by approximately four times, which resulted in premature transition for this step height. However, some notable differences were observed in the behavior of the stationary crossflow mode, which indicate that the interaction mechanism which results in the increased growth of the stationary crossflow downstream of the step may be different in this case compared to the larger step heights.

  13. Infiltration of CO2 into Water-Saturated Two-Dimensional Porous Micromodels: New Insight from Microscopic Particle Image Velocimetry (μPIV) Experiments

    NASA Astrophysics Data System (ADS)

    Kazemifar, F.; Blois, G.; Kyritsis, D. C.; Christensen, K. T.

    2013-12-01

    A novel experimental apparatus has been developed to study the interaction between liquid/supercritical CO2 and water in a two-dimensional porous micro-model. This flow process is very similar to what is encountered in many engineering applications such as sequestration of CO2 in geological formations (Carbon Capture and Sequestration, CCS) as well as enhanced oil recovery operations (EOR). Saline aquifers have very high potential for geological sequestration of CO2 based on several factors, including high capacity, economics and minimum environmental impact. Several CO2 injection and sequestration projects are currently in operation (e.g. Sleipner project in Norway), and numerous other projects are planned for the near future. While several studies exist on the large temporal- and spatial- scale effects of CO2 injection, the fluid-dynamic mechanisms at the pore-scale are largely unknown. In fact, recent studies suggest that such processes may be far more complex than previously addressed. CO2 and water/brine are immiscible, thus during the injection process of CO2 into a liquid-saturated porous structure, CO2 must displace the resident fluid. The lower viscosity and density of CO2 compared to water results in complex mechanisms of water displacement. While early studies focused on qualitative observations of fluid-fluid interactions, in this study, the microscopic particle image velocimetry (μPIV) technique is employed to quantify the flow fields within each fluid phase. The interface dynamics, migration and trapping mechanisms are of particular interest. In such flows, viscosity and interfacial tension are known as the main controlling parameters. In this regard, a challenging aspect of this work is that, in the vicinity of the critical point, these properties become very sensitive to changes in pressure and temperature. Additionally, despite the low Reynolds number of the flow, inertial effects are found to control the dynamics of flow patterns at the fluid

  14. Immiscible experiments on the Rayleigh-Taylor instability using simultaneous particle image velocimetry and planar laser induced fluorescence concentration measurements

    NASA Astrophysics Data System (ADS)

    Mokler, Matthew; Jacobs, Jeffrey

    2014-11-01

    Incompressible Rayleigh-Taylor instability experiments are presented in which two stratified liquids having Atwood number of 0.2 are accelerated in a vertical linear induction motor driven drop tower. A test sled having only vertical freedom of motion contains the experiment tank and visualization equipment. The sled is positioned at the top of the tower within the linear induction motors and accelerated downward causing the initially stable interface to be unstable and allowing the Rayleigh-Taylor instability to develop. Forced and unforced experiments are conducted using an immiscible liquid combination. Forced initial perturbations are produced by vertically oscillating the test sled prior to the start of acceleration. The interface is visualized using a 445 nm laser light source that illuminates a fluorescent dye mixed in one of the fluids and aluminum oxide particles dispersed in both fluids. The laser beam is synchronously swept across the fluorescent fluid, at the frame rate of the camera, exposing a single plane of the interface. The resulting images are recorded using a monochromatic high speed video camera. Time dependent velocity and density fields are obtained from the recorded images allowing for 2D full field measurements of turbulent kinetic energy and turbulent mass transport.

  15. The particle image velocimetry method in the study of the dynamics of phase transitions induced by high pressures in triolein and oleic acid

    NASA Astrophysics Data System (ADS)

    Tefelski, D. B.; Kulisiewicz, L.; Wierschem, A.; Delgado, A.; Rostocki, A. J.; Siegoczyński, R. M.

    2011-03-01

    Particle image velocimetry (PIV) is an optical measurement method capable of providing visualisation of velocity field of particle flow in fluids. After analysis of data acquired in the form of an image sequence, it is possible to retrieve information about flow parameters as mean values of velocity, vorticity, shear and normal strain. This paper presents the results of high pressure experiments using this method applied to triolein and oleic acid samples in their phase transition region. A high pressure optical chamber, He-Ne laser and light-sheet optics together with a digital camera and image acquisition computer allow us to study the motion of particles in high pressure conditions. The set-up was similar to that presented in Özmutlu et al. [Momentum and energy transfer during phase change of water under high hydrostatic pressure, Innov. Food Sci. Emerg. Technol. 7(3) (2006), pp. 161-168] and Kulisiewicz et al. [Visualization of pressure-shift freezing and thawing of concentrated aqueous sucrose solutions, High Press. Res. 27(2) (2007), pp. 291-297]. The analysis of phase transition dynamics in triolein and oleic acid is an extension to the work presented in Tefelski et al. [The investigation of the dynamics of the phase transformation in triolein and oleic acid under pressure, J. Phys.: Conf. Ser. 121(142004) (2008), pp. 1-6]. Oleic acid is a monounsaturated fatty acid and has a bent rod shape. Triolein is a triglyceride and has a "chair"-like shape. It is the base particle of many vegetable oils, especially olive oil. Triolein consists of three chains of oleic acid bound by a glycerol part. Information obtained by the study of phase transitions dynamics is important for food science and food technology processes which involve high pressure treatment. The PIV method shows differences in the solidification process of both substances in time, the existence of inhomogeneities (layers of different densities in the observed flow) and allows us to calculate the

  16. Time-resolved particle image velocimetry measurements of the 3D single-mode Richtmyer-Meshkov instability

    NASA Astrophysics Data System (ADS)

    Xu, Qian; Krivets, Vitaliy V.; Sewell, Everest G.; Jacobs, Jeffrey W.

    2016-11-01

    A vertical shock tube is used to perform experiments on the single-mode three-dimensional Richtmyer-Meshkov Instability (RMI). The light gas (Air) and the heavy gas (SF6) enter from the top and the bottom of the shock tube driven section to form the interface. The initial perturbation is then generated by oscillating the gases vertically. Both gases are seeded with particles generated through vaporizing propylene glycol. An incident shock wave (M 1.2) impacts the interface to create an impulsive acceleration. The seeded particles are illuminated by a dual cavity 75W, Nd: YLF laser. Three high-speed CMOS cameras record time sequences of image pairs at a rate of 2 kHz. The initial perturbation used is that of a single, square-mode perturbation with either a single spike or a single bubble positioned at the center of the shock tube. The full time dependent velocity field is obtained allowing the determination of the circulation versus time. In addition, the evolution of time dependent amplitude is also determined. The results are compared with PIV measurements from previous two-dimensional single mode experiments along with PLIF measurements from previous three-dimensional single mode experiments.

  17. Particle Image Velocimetry Measurements to Evaluate the Effectiveness of Deck-Edge Columnar Vortex Generators on Aircraft Carriers

    NASA Technical Reports Server (NTRS)

    Landman, Drew; Lamar, John E.; Swift, Russell

    2005-01-01

    Candidate passive flow control devices were chosen from a NASA flow visualization study to investigate their effectiveness at improving flow quality over a flat-top carrier model. Flow over the deck was analyzed using a particle image velocimeter and a 1/120th scaled carrier model in a low-speed wind tunnel. Baseline (no devices) flow quality was compared to flow quality from combinations of bow and deck-edge devices at both zero and 20 degrees yaw. Devices included plain flaps and spiral cross-section columnar vortex generators attached in various combinations to the front and sides of the deck. Centerline and cross plane measurements were made with velocity and average turbulence measurements reported. Results show that the bow/deck-edge flap and bow/deck-edge columnar vortex generator pairs reduce flight deck turbulence both at zero yaw and at 20 degrees yaw by a factor of approximately 20. Of the devices tested, the most effective bow-only device appears to be the plain flap.

  18. Microparticles with hierarchical porosity

    DOEpatents

    Petsev, Dimiter N; Atanassov, Plamen; Pylypenko, Svitlana; Carroll, Nick; Olson, Tim

    2012-12-18

    The present disclosure provides oxide microparticles with engineered hierarchical porosity and methods of manufacturing the same. Also described are structures that are formed by templating, impregnating, and/or precipitating the oxide microparticles and method for forming the same. Suitable applications include catalysts, electrocatalysts, electrocatalysts support materials, capacitors, drug delivery systems, sensors and chromatography.

  19. Fundamental Studies on the Enzymatic Liquefaction and Rheology of Cellulosic Biomass viaMagnetic Resonance Imaging Velocimetry

    NASA Astrophysics Data System (ADS)

    Cardona, Maria Jose

    Worldwide need for alternatives to fossil fuels has driven significant research effort toward the development and scale-up of sustainable forms of energy. Second-generation biofuels, obtained from the breakdown of lignocellulosic biomass (e.g., agricultural residues), present a promising alternative. In biofuel production, the enzymatic hydrolysis of cellulose to glucose is currently one of the most expensive steps in the biochemical breakdown of lignocellulosic biomass. Economic considerations for large-scale implementation of this process demand operation at high solids loadings of biomass (>15% (w/w)) due to potential for higher product concentrations and reduction of water usage throughout the biorefining process. In the high-solids regime, however, biomass slurries form a high viscosity, non-Newtonian slurry that introduces processing challenges, especially during the initial stages of hydrolysis (liquefaction), due to the low availability of water in the bulk phase. Furthermore, a concomitant reduction in glucose yields with increase in solids loadings has been observed, a phenomenon that is not well understood, but if overcome could hold the key to achieving desirable yields during hydrolysis. In order to better understand liquefaction, a magnetic resonance imaging (MRI) rheometer was used to perform in-line, in situ, real-time, and noninvasive studies on biomass slurries undergoing enzymatic hydrolysis. Batch and fed-batch experiments were done on lignocellulosic and cellulosic substrates with both purified and mixtures of enzymes, under various reaction conditions. The mechanism of liquefaction was found to be decoupled from the mechanism of saccharification. In addition, end product inhibition was found to have an impact on both saccharification and liquefaction during the initial stage of hydrolysis, which has an impact on scale-up of hydrolysis processes. Lastly, to address and overcome high-solids limitations, a fed-batch liquefaction process based on

  20. Blood circulating microparticle species in relapsing–remitting and secondary progressive multiple sclerosis. A case–control, cross sectional study with conventional MRI and advanced iron content imaging outcomes

    PubMed Central

    Alexander, J.S.; Chervenak, R.; Weinstock-Guttman, B.; Tsunoda, I.; Ramanathan, M.; Martinez, N.E.; Omura, S.; Sato, F.; Chaitanya, G.V.; Minagar, A.; McGee, J.; Jennings, M.H.; Monceaux, C.; Becker, F.; Cvek, U.; Trutschl, M.; Zivadinov, R.

    2015-01-01

    Background Although multiple sclerosis (MS) is thought to represent an excessive and inappropriate immune response to several central nervous system (CNS) autoantigens, increasing evidence also suggests that MS may also be a neurovascular inflammatory disease, characterized by endothelial activation and shedding of cell membrane microdomains known as ‘microparticles’ into the circulation. Objective To investigate the relationships between these endothelial biomarkers and MS. Methods We examined the relative abundance of CD31+/PECAM-1, CD51+CD61+ (αV–β3) and CD54+ (ICAM-1) bearing microparticles in sera of healthy individuals, patients with relapsing–remitting MS, and secondary-progressive MS. We also investigated the correlation among circulating levels of different microparticle species in MS with conventional MRI (T2- and T1-lesion volumes and brain atrophy), as well as novel MR modalities [assessment of iron content on susceptibility-weighted imaging (SWI)-filtered phase]. Results Differences in circulating microparticle levels were found among MS groups, and several microparticle species (CD31+/CD51+/CD61+/CD54+) were found to correlate with conventional MRI and SWI features of MS. Conclusion These results indicate that circulating microparticles’ profiles in MS may support mechanistic roles for microvascular stress and injury which is an underlying contributor not only to MS initiation and progression, but also to pro-inflammatory responses. PMID:26073484

  1. Streak speckle velocimetry

    NASA Astrophysics Data System (ADS)

    Re Calegari, Gabriele; Ferri, Fabio

    2014-01-01

    We present a method for fluid velocimetry based on a single-exposure analysis of the streak speckle pattern generated by sub-micron tracking particles illuminated with coherent light. It works in real-time and provides two dimensional velocity mappings in the direction orthogonal to the optical axis, independently of particle concentration and size. It is immune of any spurious light acting as undesired heterodyne signal and can probe velocities much higher (˜three orders of magnitude) than methods based on double-exposure analysis. The method has been tested by using rigid diffusers of different heterodyne strength and applied to map the flow of a confined fluid.

  2. Heterodyne speckle velocimetry

    SciTech Connect

    Alaimo, M. D.; Magatti, D.; Ferri, F.; Potenza, M.A.C.

    2006-05-08

    We present a simple method for fluid velocimetry based on the velocity of the heterodyne speckles generated by tracking particles illuminated with coherent light. It works in real time and provides instantaneous two-dimensional velocity mappings in the direction orthogonal to the optical axis, independently of the particle concentration and size, also for subwavelength particles. It also provides the velocity distribution of the fluid over the entire sample thickness. The method has been quantitatively tested by using the motions of rigid diffusers and applied for mapping the flow of a confined fluid.

  3. Using Concatenated Profiles from High-Speed Laser Profile Scanners to Estimate Debris-Flow Characteristics: A Novel Approach Based on Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Jacquemart, M. F.; Meier, L.; Graf, C.; Morsdorf, F.

    2015-12-01

    We use globally unique datasets from paired laser profile scanners to measure debris-flow height, velocity and discharge in two well-known debris-flow channels in Switzerland. Since 2011, these scanners have been scanning passing debris flows at rates of up to 75 Hz, acquiring millions of cross-bed profiles. The profiles can be concatenated through time, generating unique 2.5D representations of passing debris flows. Applying a large-scale Particle Image Velocimetry (PIV) approach to these datasets has proven successful to measure surface flow velocities. Flow height can also be estimated from the laser scanners, and thus a discharge estimate can be given. To account for changes to the channel bed due to erosion and deposition during the debris flow, we compute two flow height estimates using a pre-event as well as a post-event channel geometry in order to visualize discharge variability.Velocity outliers need to be excluded to provide reliable estimates of peak discharge, and changes to the channel bed are assumed to be the largest source of uncertainty. However, the latter problem is inherent to all debris-flow discharge measurements, and we have found the new system to offer distinct advantages over the conventional system relying on geophones and a radar gauge. The wide scan angle of up to 190° renders the scanners insensitive to changes of the flow path, and the point density of roughly 20 points per meter offer unprecedented spatial coverage.In addition, the geometries of the cross-bed profiles have been analyzed, revealing distinct changes of cross-flow convexity between the front and the tail of the flows in several cases. This is assumed to indicate changes of debris-flow mixtures, but further research is needed to better understand this signal.We hope that our preliminary analysis and toolbox will facilitate working with these kinds of datasets so as to further improve debris-flow understanding, monitoring and modeling efforts in the future.

  4. Spatial and temporal patterns of water flow generated by suction-feeding bluegill sunfish Lepomis macrochirus resolved by Particle Image Velocimetry.

    PubMed

    Day, Steven W; Higham, Timothy E; Cheer, Angela Y; Wainwright, Peter C

    2005-07-01

    The suction-feeding fish generates a flow field external to its head in order to draw prey into the mouth. To date there are very few empirical measurements that characterize the fluid mechanics of suction feeding, particularly the temporal and spatial patterns of water velocity in front of the fish. To characterize the flow in front of suction-feeding bluegill sunfish Lepomis macrochirus, measurements with high spatial (<1 mm) and temporal (500 Hz) resolution were taken using Particle Image Velocimetry (PIV). In an analysis separate from the PIV, high-speed video sequences were used for a novel method of visually tracking every seed particle for the duration of each feeding in order to determine directly the total parcel of water that the fish ingests. PIV measurements and particle tracking show that water is drawn from all around the mouth. Fluid velocity decreases rapidly with distance from the mouth and is only significant (>5% of speed at the mouth) within roughly 1 mouth diameter of the fish. Suction feeders gain little in terms of extending this flow field by even substantial increases in the fluid speed at the mouth opening. Instead, the chief advantage of increased flow speed at the mouth may be the increased magnitude of generated forces within the space very close to the mouth. After scaling of the velocity field based on size of the mouth opening and the measured fluid speed at a fixed position, the measured velocity profiles for all feedings are very similar to one another, so that a functional relationship for the magnitude of fluid speed as a function of distance from the predator mouth is presented and shown to be accurate over the range of kinematic variables tested. This relationship describes the velocity field both along the centerline of the fish and along transects lying at an angle to the centerline within both the mid-sagittal and frontal planes. Comparison of the time-resolved fluid velocity measurements to gape kinematics demonstrate that

  5. Time-resolved stereoscopic particle image velocimetry investigation of the entrainment in the near field of circular and daisy-shaped orifice jets

    NASA Astrophysics Data System (ADS)

    El Hassan, Mouhammad; Meslem, Amina

    2010-03-01

    The flow in the initial region of two jets, namely, a circular orifice jet and a lobed orifice jet, is considered in the present paper. The role played by the Kelvin-Helmholtz (K-H) azimuthal rings and the streamwise vortices in the entrainment process of both jets have been qualitatively and quantitatively analyzed, for a Reynolds number of 3600. This has been achieved using the high speed stereoscopic particle image velocimetry measurements and a proper orthogonal decomposition (POD) analysis. The mean entrainment rate observed in the daisy-shaped jet is higher than that of the circular jet. It is found that a strong correlation exists between the entrainment rate and the K-H vortex dynamics for the circular jet. The entrainment is mainly produced in the upstream part of the K-H ring as well as in the braid region where the streamwise vortices appear. In the downstream part of the K-H ring, the flow expands from the jet core to the surrounding. In the lobed jet, the amplitude of the entrainment variation is smaller than in the circular jet at the same axial position. The flow dynamics observed in the region of axis switching is highly complex. A snapshot POD analysis is performed to bring out the individual role played by the azimuthal and the streamwise vortices on the entrainment for both the jets. In the circular jet, the POD analysis confirms quantitatively the role of the K-H vortices as well as the streamwise vortices on jet entrainment. In the lobed jet, in addition to the main role of the streamwise vortex pairs in the entrainment, the K-H vortex also plays an undeniable role on the entrainment. In the experiments conducted, a steep rise in the momentum flux is observed for the axis-switching region of the lobed jet. The longitudinal distribution of the mean entrainment ratio of the daisy jet corroborates with that of the averaged streamwise vorticity and with the maximum streamwise vorticity. In the region of the axis switching, an important decrease in

  6. EDITORIAL: Holographic Particle Image Velocimetry

    NASA Astrophysics Data System (ADS)

    Hinsch, Klaus D.; Herrmann, Sven F.

    2004-04-01

    We are very pleased to be able to edit this special issue of Measurement Science and Technology, which provides readers with an overview of recent progress and the current status in the field of optical fibre sensors. The 16th International Conference on Optical Fibre Sensors (OFS-16) was held at the Nara-ken New Public Hall in Nara City, the ancient capital of Japan, from 14 to 17 October 2003. The first conference in this series was held in London in 1983, and a meeting has been held every one and a half years, covering the three geographic areas of America, Asia/Oceania and Europe/Africa. This conference was the third to be held in Japan. The conference provides a forum for the latest developments in optical fibre/guided-wave sensors, photonic sensing devices and related technologies. Also at OFS-16, many exciting papers were presented describing various kinds of fibre sensor technologies. The conference program consisted of a plenary talk, 23 invited presentations, 60 contributed oral presentations and 111 poster presentations. In addition, a special session was held on 'Sensing Technology for Smart Structures and Smart Materials'. This is one of the most promising fields in fibre sensing technology, and this session was planned to discuss the present status and identify issues to be resolved in the future. The 40 papers appearing in this issue contain detailed presentations of some of the articles presented at the conference, and reflect recent trends in optical fibre sensor technology and applications. About 40% of the papers are concerned with fibre Bragg grating technology itself or with its various applications, such as refractometry, thermometry, displacement, torsion, bending sensing and so forth. Of course, other original ideas have been proposed for applications that make clear how optical fibres are unique and powerful tools in sensing technology for various applications in many fields. We hope that this special issue helps to stimulate the field of optical fibre sensing, and would like to thank all the contributing authors and reviewers who have made this special issue possible. We would also like to thank Institute of Physics Publishing and their staff for all their hard work and support.

  7. Particle Streak Velocimetry of Supersonic Nozzle Flows

    NASA Technical Reports Server (NTRS)

    Willits, J. D.; Pourpoint, T. L.

    2016-01-01

    A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

  8. Microparticle Flow Sensor

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.

    2005-01-01

    The microparticle flow sensor (MFS) is a system for identifying and counting microscopic particles entrained in a flowing liquid. The MFS includes a transparent, optoelectronically instrumented laminar-flow chamber (see figure) and a computer for processing instrument-readout data. The MFS could be used to count microparticles (including micro-organisms) in diverse applications -- for example, production of microcapsules, treatment of wastewater, pumping of industrial chemicals, and identification of ownership of liquid products.

  9. OCT methods for capillary velocimetry

    PubMed Central

    Srinivasan, Vivek J.; Radhakrishnan, Harsha; Lo, Eng H.; Mandeville, Emiri T.; Jiang, James Y.; Barry, Scott; Cable, Alex E.

    2012-01-01

    To date, two main categories of OCT techniques have been described for imaging hemodynamics: Doppler OCT and OCT angiography. Doppler OCT can measure axial velocity profiles and flow in arteries and veins, while OCT angiography can determine vascular morphology, tone, and presence or absence of red blood cell (RBC) perfusion. However, neither method can quantify RBC velocity in capillaries, where RBC flow is typically transverse to the probe beam and single-file. Here, we describe new methods that potentially address these limitations. Firstly, we describe a complex-valued OCT signal in terms of a static scattering component, dynamic scattering component, and noise. Secondly, we propose that the time scale of random fluctuations in the dynamic scattering component are related to red blood cell velocity. Analysis was performed along the slow axis of repeated B-scans to parallelize measurements. We correlate our purported velocity measurements against two-photon microscopy measurements of RBC velocity, and investigate changes during hypercapnia. Finally, we image the ischemic stroke penumbra during distal middle cerebral artery occlusion (dMCAO), where OCT velocimetry methods provide additional insight that is not afforded by either Doppler OCT or OCT angiography. PMID:22435106

  10. Gelation chemistries for the encapsulation of nanoparticles in composite gel microparticles for lung imaging and drug delivery

    PubMed Central

    Pinkerton, Nathalie M.; Zhang, Stacey W.; Youngblood, Richard L.; Gao, Dayuan; Li, Shike; Benson, Bryan R.; Anthony, John; Stone, Howard A.; Sinko, Patrick J.; Prud’homme, Robert K.

    2014-01-01

    The formation of 10 to 40 μm Composite Gel MicroParticles (CGMPs) comprising ~100 nm drug containing nanoparticles (NPs) in a poly(ethylene glycol)(PEG) gel matrix is described. The CGMP particles enable targeting to the lung by filtration from the venous circulation. UV radical polymerization and Michael addition polymerization reactions are compared as approaches to form the PEG matrix. A fluorescent dye in the solid core of the NP was used to investigate the effect of reaction chemistry on the integrity of encapsulated species. When formed via UV radical polymerization, the fluorescence signal from the NPs indicated degradation of the encapsulated species by radical attack. The degradation decreased fluorescence by 90% over 15 minutes of UV exposure. When formed via Michael addition polymerization, the fluorescence was maintained. Emulsion processing using controlled shear stress enabled control of droplet size with narrow polydispersities. To allow for emulsion processing, the gelation rate was delayed by adjusting the solution pH. At a pH= 5.4 the gelation occurred at 3.5 hours. The modulus of the gels was tuned over the range of 5 to 50 kPa by changing the polymer concentration between 20 and 70 vol %. NPs aggregation during polymerization, driven by depletion forces, was controlled by the reaction kinetics. The ester bonds in the gel network enabled CGMP degradation. The gel modulus decreased by 50% over 27 days, followed by complete gel degradation after 55 days. This permits ultimate clearance of the CGMPs from the lungs. The demonstration of uniform delivery of 15.8 ± 2.6 μm CGMPs to the lungs of mice, with no deposition in other organs, is shown, and indicates the ability to target therapeutics to the lung while avoiding off-target toxic exposure. PMID:24410445

  11. Effect of coarctation of the aorta and bicuspid aortic valve on flow dynamics and turbulence in the aorta using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Keshavarz-Motamed, Zahra; Garcia, Julio; Gaillard, Emmanuel; Maftoon, Nima; Di Labbio, Giuseppe; Cloutier, Guy; Kadem, Lyes

    2014-03-01

    Blood flow in the aorta has been of particular interest from both fluid dynamics and physiology perspectives. Coarctation of the aorta (COA) is a congenital heart disease corresponding to a severe narrowing in the aortic arch. Up to 85 % of patients with COA have a pathological aortic valve, leading to a narrowing at the valve level. The aim of the present work was to advance the state of understanding of flow through a COA to investigate how narrowing in the aorta (COA) affects the characteristics of the velocity field and, in particular, turbulence development. For this purpose, particle image velocimetry measurements were conducted at physiological flow and pressure conditions, with three different aorta configurations: (1) normal case: normal aorta + normal aortic valve; (2) isolated COA: COA (with 75 % reduction in aortic cross-sectional area) + normal aortic valve and (3) complex COA: COA (with 75 % reduction in aortic cross-sectional area) + pathological aortic valve. Viscous shear stress (VSS), representing the physical shear stress, Reynolds shear stress (RSS), representing the turbulent shear stress, and turbulent kinetic energy (TKE), representing the intensity of fluctuations in the fluid flow environment, were calculated for all cases. Results show that, compared with a healthy aorta, the instantaneous velocity streamlines and vortices were deeply changed in the presence of the COA. The normal aorta did not display any regions of elevated VSS, RSS and TKE at any moment of the cardiac cycle. The magnitudes of these parameters were elevated for both isolated COA and complex COA, with their maximum values mainly being located inside the eccentric jet downstream of the COA. However, the presence of a pathologic aortic valve, in complex COA, amplifies VSS (e.g., average absolute peak value in the entire aorta for a total flow of 5 L/min: complex COA: = 36 N/m2; isolated COA = 19 N/m2), RSS (e.g., average peak value in the entire aorta for a total flow of 5

  12. Rubidium atomic line filtered (RALF) Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario E.; Molek, Christopher D.; Vesely, Annamaria L.

    2017-01-01

    We report recent improvements to our Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus [M.E. Fajardo, C.D. Molek, and A.L. Vesely, J. Appl. Phys. 118, 144901 (2015)]. RALF is a high-velocity and high-acceleration adaptation of the Doppler Global Velocimetry method for measuring multi-dimensional velocity vector flow fields, which was developed in the 1990s by aerodynamics researchers [H. Komine, U.S. Patent #4,919,536]. Laser velocimetry techniques in common use within the shock physics community (e.g. VISAR, Fabry-Pérot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to encode the Doppler shift of reflected λ0 ≈ 780.24 nm light directly onto the transmitted light intensity. Thus, RALF is insensitive to minor changes to the optical pathlengths and transit times of the Doppler shifted light, which promises a number of practical advantages in imaging velocimetry applications. The single-point RALF proof-of-concept apparatus described here is fiber optic based, and our most recent modifications include the incorporation of a larger bandwidth detection system, and a second 780 nm laser for simultaneous upshifted-PDV (UPDV) measurements. We report results for the laser driven launch of a 10-μm-thick aluminum flyer which show good agreement between the RALF and UPDV velocity profiles, within the limitations of the admittedly poor signal:noise ratio (SNR) RALF data.

  13. Plasma dragged microparticles as a method to measure plasma flows

    SciTech Connect

    Ticos, Catalin M.; Wang Zhehui; Delzanno, Gian Luca; Lapenta, Giovanni

    2006-10-15

    The physics of microparticle motion in flowing plasmas is studied in detail for plasmas with electron and ion densities n{sub e,i}{approx}10{sup 19} m{sup -3}, electron and ion temperatures of no more than 15 eV, and plasma flows on the order of the ion thermal speed, v{sub f}{approx}v{sub ti}. The equations of motion due to Coulomb interactions and direct impact with ions and electrons, of charge variation, as well as of heat exchange with the plasma, are solved numerically for isolated particles (or dust grains) of micron sizes. It is predicted that microparticles can survive in plasma long enough, and can be dragged in the direction of the local ion flow. Based on the theoretical analysis, we describe a new plasma flow measurement technique called microparticle tracer velocimetry (mPTV), which tracks microparticle motion in a plasma with a high-speed camera. The mPTV can reveal the directions of the plasma flow vectors at multiple locations simultaneously and at submillimeter scales, which is hard to achieve by most other techniques. Thus, mPTV can be used to study plasma flows produced in the laboratory.

  14. Validation and application of Acoustic Mapping Velocimetry

    NASA Astrophysics Data System (ADS)

    Baranya, Sandor; Muste, Marian

    2016-04-01

    The goal of this paper is to introduce a novel methodology to estimate bedload transport in rivers based on an improved bedform tracking procedure. The measurement technique combines components and processing protocols from two contemporary nonintrusive instruments: acoustic and image-based. The bedform mapping is conducted with acoustic surveys while the estimation of the velocity of the bedforms is obtained with processing techniques pertaining to image-based velocimetry. The technique is therefore called Acoustic Mapping Velocimetry (AMV). The implementation of this technique produces a whole-field velocity map associated with the multi-directional bedform movement. Based on the calculated two-dimensional bedform migration velocity field, the bedload transport estimation is done using the Exner equation. A proof-of-concept experiment was performed to validate the AMV based bedload estimation in a laboratory flume at IIHR-Hydroscience & Engineering (IIHR). The bedform migration was analysed at three different flow discharges. Repeated bed geometry mapping, using a multiple transducer array (MTA), provided acoustic maps, which were post-processed with a particle image velocimetry (PIV) method. Bedload transport rates were calculated along longitudinal sections using the streamwise components of the bedform velocity vectors and the measured bedform heights. The bulk transport rates were compared with the results from concurrent direct physical samplings and acceptable agreement was found. As a first field implementation of the AMV an attempt was made to estimate bedload transport for a section of the Ohio river in the United States, where bed geometry maps, resulted by repeated multibeam echo sounder (MBES) surveys, served as input data. Cross-sectional distributions of bedload transport rates from the AMV based method were compared with the ones obtained from another non-intrusive technique (due to the lack of direct samplings), ISSDOTv2, developed by the US Army

  15. Objective speckle velocimetry for autonomous vehicle odometry.

    PubMed

    Francis, D; Charrett, T O H; Waugh, L; Tatam, R P

    2012-06-01

    Speckle velocimetry is investigated as a means of determining odometry data with potential for application on autonomous robotic vehicles. The technique described here relies on the integration of translation measurements made by normalized cross-correlation of speckle patterns to determine the change in position over time. The use of objective (non-imaged) speckle offers a number of advantages over subjective (imaged) speckle, such as a reduction in the number of optical components, reduced modulation of speckles at the edges of the image, and improved light efficiency. The influence of the source/detector configuration on the speckle translation to vehicle translation scaling factor for objective speckle is investigated using a computer model and verified experimentally. Experimental measurements are presented at velocities up to 80  mm s(-1) which show accuracy better than 0.4%.

  16. Krypton tagging velocimetry of an underexpanded jet.

    PubMed

    Parziale, N J; Smith, M S; Marineau, E C

    2015-06-01

    In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow with krypton; (ii) photosynthesize metastable krypton atoms with a frequency-doubled dye laser to form the tagged tracer; (iii) record the translation of the tagged metastable krypton by imaging the laser-induced fluorescence (LIF) that is produced with an additional dye laser. The principle strength of KTV, relative to other tagging velocimetry techniques, is the use of a chemically inert tracer. KTV results are presented for an underexpanded jet of three mixtures of varying Kr/N2 concentration. It is demonstrated that KTV can be used in gas mixtures of relatively low krypton mole fraction (0.5% Kr/99.5% N2), and the KTV data from that experiment are found to be in good agreement with an empirical fit found in the literature. We find that KTV is useful to perform instantaneous velocity measurements with metastable krypton as a chemically inert, dilute, long-lifetime tracer in gas-phase flows.

  17. Magnetic barcoded hydrogel microparticles for multiplexed detection.

    PubMed

    Bong, Ki Wan; Chapin, Stephen C; Doyle, Patrick S

    2010-06-01

    Magnetic polymer particles have been used in a wide variety of applications ranging from targeting and separation to diagnostics and imaging. Current synthesis methods have limited these particles to spherical or deformations of spherical morphologies. In this paper, we report the use of stop flow lithography to produce magnetic hydrogel microparticles with a graphical code region, a probe region, and a magnetic tail region. These anisotropic multifunctional magnetic polymer particles are an enhanced version of previously synthesized "barcoded" particles (Science, 2007, 315, 1393-1396) developed for the sensitive and rapid multiplexed sensing of nucleic acids. The newly added magnetic region has acquired dipole moments in the presence of weak homogeneous magnetic fields, allowing the particles to align along the applied field direction. The novel magnetic properties have led to practical applications in the efficient orientation and separation of the barcoded microparticles during biological assays without disrupting detection capabilities.

  18. Advances in holographic particle velocimetry

    NASA Astrophysics Data System (ADS)

    Simmons, Scott; Meng, Hui; Hussain, Fazle; Liu, David

    1993-12-01

    Holographic particle velocimetry (HPV) is a promising technique for 3D flow velocity and hence vorticity measurements to study turbulence, coherent structures and vortex interactions. We discuss various aspects in the development of this technique ranging from hologram recording configurations such as in-line, off-axis and multibeam to data processing. Difficulties in implementation are analyzed and solutions are discussed. We also present preliminary measurement results in a 3D vortex flow using one of our prototype HPV systems.

  19. Velocimetry signal synthesis with fringen.

    SciTech Connect

    Dolan, Daniel H., III

    2011-02-01

    An important part of velocimetry analysis is the recovery of a known velocity history from simulated data signals. The fringen program synthesizes VISAR and PDV signals, given a specified velocity history, using exact formulations for the optical signal. Time-dependent light conditions, non-ideal measurement conditions, and various diagnostic limitations (noise, etc.) may be incorporated into the simulated signals. This report describes the fringen program, which performs forward VISAR (Velocity Interferometer System for Any Reflector) and PDV (Photonic Doppler Velocimetry, also known as heterodyne velocimetry) analysis. Nearly all effects that might occur in VISAR/PDV measurement of a single velocity can be modeled by fringen. The program operates in MATLAB, either within a graphical interface or as a user-callable function. The current stable version of fringen is 0.3, which was released in October 2010. The following sections describe the operation and use of fringen. Section 2 gives a brief overview of VISAR and PDV synthesis. Section 3 illustrates the graphical and console interface of fringen. Section 4 presents several example uses of the program. Section 5 summarizes program capabilities and discusses potential future work.

  20. Elastic filament velocimetry (EFV)

    NASA Astrophysics Data System (ADS)

    Fu, M. K.; Fan, Y.; Byers, C. P.; Chen, T.-H.; Arnold, C. B.; Hultmark, M.

    2017-02-01

    A novel method for velocity measurements in both gaseous and liquid flows is presented. The sensing element is comprised of a free-standing electrically conductive nanoscale ribbon suspended between silicon supports. Due to its minuscule size, the nanoribbon deflects in flow due to viscously dominated fluid forcing inducing an axial strain of the sensing element. The strain leads to a resistance change, which is measurable through a simple Wheatstone bridge circuit and can be related to the flow velocity through semi-analytic analysis. Two methods of characterization are employed to validate the sensor functionality. First, confocal microscopy was used to validate physical models and assumptions through imaging of the nanoribbon deformation under different fluid loads. Second, the resistance measurements of various nanoribbons under different flow conditions exhibited sensitivity to fluid flow consistent with lower order model predictions.

  1. Modification of the ultrasound induced activity by the presence of an electrode in a sono-reactor working at two low frequencies (20 and 40 kHz). Part II: Mapping flow velocities by particle image velocimetry (PIV).

    PubMed

    Mandroyan, A; Doche, M L; Hihn, J Y; Viennet, R; Bailly, Y; Simonin, L

    2009-01-01

    Sonoelectrochemical experiments differ from sonochemical ones by the introduction of electrodes in the sonicated reaction vessel. The aim of the study is to characterize the changes in the ultrasonic activity induced by the presence of an electrode located in front of the transducer. The scope of our investigations concerns two low frequency vibration modes: 20 and 40 kHz. For this purpose, two laser visualization techniques have been used. The first part of the study, described in a previous paper (Part I), deals with the laser tomography technique which provides an accurate picture of the reactor active zones, related to numerous cavitation events. The second part of the paper (Part II) will describe the particle image velocimetry (PIV) technique used to measure the velocity vector field in the fluid portion between the horn and the electrode. As for the previous study, two parameters were studied: the electrical power supplied to the transducer and the electrode/transducer distance. The velocity vector fields show a main flow in the reactor axis. This flow seems to correspond to the conical cavitation bubbles structure which is observed on the laser tomography pictures. When an electrode is introduced into the reactor, two additional symmetric transversal flows can be quantified on both sides of the electrode.

  2. Clean seeding for flow visualization and velocimetry measurements

    NASA Astrophysics Data System (ADS)

    Reeder, Mark F.; Crafton, Jim W.; Estevadeordal, Jordi; Delapp, Joseph; McNiel, Charles; Peltier, Don; Reynolds, Tina

    2010-05-01

    Flow visualization, particle image velocimetry (PIV), and laser Doppler velocimetry (LDV) are among the most useful tools available for experimental aerodynamics studies. Implementation of these techniques, however, requires that seed material be introduced into the flow. The undesirable qualities of the seeding material often prevent the use of flow visualization and velocimetry techniques in many test environments. This is particularly true for large-scale, closed-circuit tunnels where facility operators must weigh the risks of facility contamination, sensor damage, and safety concerns that might result from the introduction of seed particles. Identification of a practical clean seeding material that minimizes or eliminates these concerns would enable flow visualization and velocimetry techniques to be deployed in these facilities. Here, we demonstrate two seeding systems that have the potential to provide such a solution. The first system is a new concept which uses liquid carbon dioxide that can be made to form discrete particles as it expands from a high-pressure tank. PIV measurements are demonstrated in several flows, including supersonic and subsonic tunnels, using these residue-free seed particles. The second system utilizes a combination of steam and liquid nitrogen to produce an aerosol or fog that serves as flow seeding. Water- or steam-based seeding has been previously demonstrated for flow visualization in subsonic tunnels; here however, we utilize this seed material for PIV and LDV measurements as well as for flow visualization in a large supersonic tunnel.

  3. Porphyrin Microparticles for Biological and Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Huynh, Elizabeth

    Lipids are one of the critical building blocks of life, forming the plasma membrane of cells. In addition, porphyrins also play an equally important role in life, for example, through carrying oxygen in blood. The importance of both these components is evident through the biological and biomedical applications of supramolecular structures generated from lipids and porphyrins. This thesis investigates new porphyrin microparticles based on porphyrin-lipid architecture and their potential applications in biology and medicine. In Chapter 1, a background on lipid and porphyrin-based supramolecular structures is presented and design considerations for generating multifunctional agents. Chapter 2 describes the generation of a monolayer porphyrin microparticle as a dual-modal ultrasound and photoacoustic contrast agent and subsequently, a trimodal ultrasound, photoacoustic and fluorescence contrast agent. Chapter 3 examines the optical and morphological response of these multimodality ultrasound-based contrast agents to low frequency, high duty cycle ultrasound that causes the porphyrin microparticles to convertinto nanoparticles. Chapter 4 examines the generation of bilayer micrometer-sized porphyrin vesicles and their properties. Chapter 5 presents a brief summary and potential future directions. Although these microscale structures are similar in structure, the applications of these structures greatly differ with potential applications in biology and also imaging and therapy of disease. This thesis aims to explore and demonstrate the potential of new simplified, supramolecular structures based on one main building block, porphyrin-lipid.

  4. Velocimetry of cathode particles in a magnetoplasmadynamic thruster discharge plasma.

    PubMed

    Walker, J; Langendorf, S; Walker, M; Polzin, K; Kimberlin, A

    2015-07-01

    With high-speed imaging, it is possible to directly observe the time-evolution of the macroscopic behavior of the discharge plasma in a magnetoplasmadynamic thruster (MPDT). By utilizing direct high-speed imaging capable of capturing many images over the course of a single discharge, the velocity of the cathode erosion particles can be measured, opening the possibility of a novel, noninvasive technique for discharge plasma flow field velocimetry. In this work, an 8 kA argon MPDT discharge is imaged at 26 173 fps utilizing a 0.9 neutral density filter. The camera is aligned with thruster centerline 4 m downstream of the thruster exit plane. By tracking visible particles appearing in the multiple images, the particle motion in the radial and azimuthal directions is directly imaged. Through the use of traditional techniques in digital particle image velocimetry, the cathode particles emanating from the discharge are measured to have a mean radial velocity of 44.6 ± 6.0 m/s with a 95% confidence interval and a statistically insignificant azimuthal velocity. The setup and analysis employed permits measurement of the particle velocity in orthogonal direction to the image sensor plane using a single camera. By combining a background removal subtraction technique and knowledge of the optical focal plane, the estimated mean axial velocity of the particles is 1.59 km/s. This investigation ends with a discussion of important factors to consider for future MPDT high-speed imaging particle velocimetry, such as frame-rate, image size, spatial resolution, optics, and data handling selections.

  5. An automatic approach and grip method of micro-particle in 3D space

    NASA Astrophysics Data System (ADS)

    Zhang, Juan; Wu, Wenrong; Bi, Lie

    2017-03-01

    Micro-particle is hard to be observed as small scale and hard to be gripped as micro-force from substrate, an automatic approach and grip method of micro-particle in the guide of microscopic vision systems is proposed in the paper to grip micro-particle. First, the micro-gripper driven by electrostatic force is introduced and forces in gripping process are analyzed. Second, a micro-assembly robot composed of two microscopic vision systems is established to monitor micro-operation process and to operate micro-particle. Image features of micro-particle and micro-gripper end-effector are extracted by image feature extraction method to calculate relative position of micro-particle and micro-gripper in image space. Last, a movement control strategy in 3D space based on image Jacobian matrix is studied to control micro-gripper approach and align with micro-particle. Experimental results verified the effectiveness of proposed methods.

  6. Design, construction, alignment, and calibration of a compact velocimetry experiment

    SciTech Connect

    Kaufman, Morris I.; Malone, Robert M.; Frogget, Brent C.; Romero, Vincent T.; Esquibel, David L.; Iverson, Adam; Lare, Gregory A.; Briggs, Bart; DeVore, Douglas; Cata, Brian; McGillivray, Kevin; Palagi, Martin; et al.,

    2007-08-31

    A velocimetry experiment has been designed to measure shock properties for small, cylindrical, metal targets (8 mm diameter × 2 mm thick). A target is accelerated by high explosives, caught, then retrieved for later inspection. The target is expected to move at a velocity of 0.1 to 3 km/sec. The complete experiment canister is ~105 mm in diameter and 380 mm long. Optical velocimetry diagnostics include the Velocity Interferometer System for Any Reflector (VISAR) and photon Doppler velocimetry (PDV). The packaging of the velocity diagnostics is not allowed to interfere with the foam catchment or an X-ray imaging diagnostic. Using commercial lenses, a single optical relay collects Doppler-shifted light for both VISAR and PDV. The use of fiber optics allows measurement of point velocities on the target surface for accelerations lasting for 3 mm of travel. Operating at 532 nm, the VISAR has separate illumination fibers requiring alignment. The PDV diagnostic operates at 1550 nm but is aligned and calibrated at 670 nm. VISAR and PDV diagnostics are complimentary measurements that image spots in close proximity on the target surface. Because the optical relay uses commercial glass, optical fibers’ axial positions are offset to compensate for chromatic aberrations. The optomechanical design requires careful attention to fiber management, mechanical assembly and disassembly, foam catchment design, and X-ray diagnostic field of view.Calibration and alignment data are archived at each assembly sequence stage. The photon budgets for the VISAR and PDV diagnostics are separately estimated.

  7. Synthesis and Characterization of Silk Fibroin Microparticles for Intra-Articular Drug Delivery

    PubMed Central

    Mwangi, Timothy K.; Bowles, Robby D.; Tainter, David M.; Bell, Richard D.; Kaplan, David L.; Setton, Lori A.

    2015-01-01

    Objective To determine the utility of silk fibroin (SF) microparticles as sustained release vehicles for intra-articular delivery. Design SF formulations were varied to generate microparticle drug carriers that were characterized in vitro for their physical properties, release kinetics for a conjugated fluorophore (Cy7), and in vivo for intra-articular retention time using live-animal, fluorescence in vivo imaging. Results SF microparticle carriers were spherical in shape and ranged from 598 nm to 21.5 μm in diameter. SF microparticles provided for sustained release of Cy7 in vitro, with only 10% of the initial load released over 7 days. Upon intra-articular injection in rat knee joints, the SF microparticles were associated with an intra-articular fluorescence decay half-life of 43.3 hours, greatly increasing the joint residence over that for an equivalent concentration of SF-Cy7 in solution form. The SF microparticles also increase the localization of dye within the joint cavity as determined by image analysis of fluorescent gradients, significantly reducing distribution of the Cy7 to neighboring tissue as compared to SF-Cy7 in free solution. Conclusion Silk microparticles act to provide for localized and sustained delivery of loaded small molecules following intra-articular injection, and may be an attractive strategy for delivering small molecule drugs for the treatment of arthritis. PMID:25724134

  8. Critical rolling angle of microparticles

    NASA Astrophysics Data System (ADS)

    Farzi, Bahman; Vallabh, Chaitanya K. P.; Stephens, James D.; Cetinkaya, Cetin

    2016-03-01

    At the micrometer-scale and below, particle adhesion becomes particularly relevant as van der Waals force often dominates volume and surface proportional forces. The rolling resistance of microparticles and their critical rolling angles prior to the initiation of free-rolling and/or complete detachment are critical in numerous industrial processes and natural phenomenon involving particle adhesion and granular dynamics. The current work describes a non-contact measurement approach for determining the critical rolling angle of a single microparticle under the influence of a contact-point base-excitation generated by a transient displacement field of a prescribed surface acoustic wave pulse and reports the critical rolling angle data for a set of polystyrene latex microparticles.

  9. FAITH 3-D Particle Image Velocimetry

    NASA Video Gallery

    Instantaneous velocity (30 frames at 1 Hz) measurements of a three dimensional model of a small hill in fluid flow. This experiment was part of a series of measurements of the complex fluid flow ar...

  10. Microparticle Adhesive Dynamics and Rolling Mediated by Selectin-Specific Antibodies Under Flow

    PubMed Central

    Ham, Anthony Sang Won; Goetz, Douglas J.; Klibanov, Alexander L.

    2013-01-01

    In vitro studies were performed to characterize the relative performance of candidate receptors to target microparticles to inflammatory markers on vascular endothelium. To model the interactions of drug-bearing micro-particles or imaging contrast agents with the vasculature, 6 micron polystyrene particles bearing antibodies, peptides, or carbohydrates were perfused over immobilized E- or P-selectin in a flow chamber. Microparticles conjugated with HuEP5C7.g2 (HuEP), a monoclonal antibody (mAb) specific to E- and P-selectin, supported leukocyte-like rolling and transient adhesion at venular shear rates. In contrast, microparticles conjugated with a higher affinity mAb specific for P-selectin (G1) were unable to form bonds at venular flow rates. When both HuEP and G1 were conjugated to the microparticle, HuEP supported binding to P-selectin in flow which allowed G1 to form bonds leading to stable adhesion. While the microparticle attachment and rolling performance was not as stable as that mediated by the natural ligands P-selectin Glycoprotein Ligand-1 or sialyl Lewisx, HuEP performed significantly better than any previously characterized mAb in terms of mediating micro-particle binding under flow conditions. HuEP may be a viable alternative to natural ligands to selectins for targeting particles to inflamed endothelium. PMID:16917925

  11. Mechanically robust microfluidics and bulk wave acoustics to sort microparticles

    NASA Astrophysics Data System (ADS)

    Dauson, Erin R.; Gregory, Kelvin B.; Greve, David W.; Healy, Gregory P.; Oppenheim, Irving J.

    2016-04-01

    Sorting microparticles (or cells, or bacteria) is significant for scientific, medical and industrial purposes. Research groups have used lithium niobate SAW devices to produce standing waves, and then to align microparticles at the node lines in polydimethylsiloxane (PDMS, silicone) microfluidic channels. The "tilted angle" (skewed) configuration is a recent breakthrough producing particle trajectories that cross multiple node lines, making it practical to sort particles. However, lithium niobate wafers and PDMS microfluidic channels are not mechanically robust. We demonstrate "tilted angle" microparticle sorting in novel devices that are robust, rapidly prototyped, and manufacturable. We form our microfluidic system in a rigid polymethyl methacrylate (PMMA, acrylic) prism, sandwiched by lead-zirconium-titanate (PZT) wafers, operating in through-thickness mode with inertial backing, that produce standing bulk waves. The overall configuration is compact and mechanically robust, and actuating PZT wafers in through-thickness mode is highly efficient. Moving to this novel configuration introduced new acoustics questions involving internal reflections, but we show experimental images confirming the intended nodal geometry. Microparticles in "tilted angle" devices display undulating trajectories, where deviation from the straight path increases with particle diameter and with excitation voltage to create the mechanism by which particles are sorted. We show a simplified analytical model by which a "phase space" is constructed to characterize effective particle sorting, and we compare our experimental data to the predictions from that simplified model; precise correlation is not expected and is not observed, but the important physical trends from the model are paralleled in the measured particle trajectories.

  12. Mucoadhesive Microparticles for Gastroretentive Delivery: Preparation, Biodistribution and Targeting Evaluation

    PubMed Central

    Hou, Jing-Yi; Gao, Li-Na; Meng, Fan-Yun; Cui, Yuan-Lu

    2014-01-01

    The aim of this research was to prepare and characterize alginate-chitosan mucoadhesive microparticles containing puerarin. The microparticles were prepared by an emulsification-internal gelatin method using a combination of chitosan and Ca2+ as cationic components and alginate as anions. Surface morphology, particle size, drug loading, encapsulation efficiency and swelling ratio, in vitro drug released, in vitro evaluation of mucoadhesiveness and Fluorescence imaging of the gastrointestinal tract were determined. After optimization of the formulation, the encapsulation efficiency was dramatically increased from 70.3% to 99.2%, and a highly swelling ratio was achieved with a change in particle size from 50.3 ± 11.2 μm to 124.7 ± 25.6 μm. In ethanol induced gastric ulcers, administration of puerarin mucoadhesive microparticles at doses of 150 mg/kg, 300 mg/kg, 450 mg/kg and 600 mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently, significant changes were observed in inflammatory cytokines, such as prostaglandin E2 (PGE2), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and interleukin1β (IL-1β), in stomach tissues compared with the ethanol control group. In conclusion, core-shell type pH-sensitive mucoadhesive microparticles loaded with puerarin could enhance puerarin bioavailability and have the potential to alleviate ethanol-mediated gastric ulcers. PMID:25470180

  13. Phase retrieval for improved three-dimensional velocimetry of dynamic x-ray blood speckle

    SciTech Connect

    Irvine, S. C.; Paganin, D. M.; Dubsky, S.; Fouras, A.; Lewis, R. A.

    2008-10-13

    High-resolution synchrotron-based x-ray phase-contrast images of in vitro blood flow have been collected. We demonstrate that the application of a single-image phase retrieval algorithm to the images leads to improved detail in particle image velocimetry correlation peaks. Out-of-plane variation in flow has been extracted from the peaks leading to the three-dimensional reconstruction of velocity across an axially symmetric cylinder.

  14. Development of multi-spectral three-dimensional micro particle tracking velocimetry

    NASA Astrophysics Data System (ADS)

    Tien, Wei-Hsin

    2016-08-01

    The color-coded 3D micro particle tracking velocimetry system (CC3DμPTV) is a volumetric velocimetry technique that uses the defocusing digital particle image velocimetry (DDPIV) approach to reconstruct the 3D location of the particle. It is suited for microscopic flow visualization because of the single camera configuration. However, several factors limit the performance of the system. In this study, the limitation of the CC3DμPTV is discussed in detail and a new concept of a multi-camera 3D μ-PTV system is proposed to improve the performance of the original CC3DμPTV system. The system utilizes two dichroic beam splitters to separate the incoming light into 3 spectral ranges, and image with three monochrome image sensors. The use of a color-matched light source, off-center individual pinhole and monochrome image sensors allow the system to achieve better sensitivity and optical resolution. The use of coherent lasers light sources with high-speed cameras improves the velocity measurement dynamic range. The performance of the proposed multi-spectral system is first evaluated with a simulation model based on the finite element method (FEM). The performance is also compared numerically with the CC3DμPTV system. The test results show significant improvements on the signal to noise ratio and optical resolution. Originally presented in 11th International Symposium on Particle Image Velocimetry, Santa Barbara, California, September 14-16, 2015.

  15. Development of Hydroxyl Tagging Velocimetry for Low Velocity Flows

    NASA Technical Reports Server (NTRS)

    Andre, Matthieu A.; Bardet, Philippe M.; Burns, Ross A.; Danehy, Paul M.

    2016-01-01

    Hydroxyl tagging velocimetry (HTV) is a molecular tagging technique that relies on the photo-dissociation of water vapor into OH radicals and their subsequent tracking using laser induced fluorescence. Velocities are then obtained from time-of-flight calculations. At ambient temperature in air, the OH species lifetime is relatively short (<50 µs), making it suited for high speed flows. Lifetime and radicals formation increases with temperature, which allows HTV to also probe low-velocity, high-temperature flows or reacting flows such as flames. The present work aims at extending the domain of applicability of HTV, particularly towards low-speed (<10 m/s) and moderate (<500 K) temperature flows. Results are compared to particle image velocimetry (PIV) measurements recorded in identical conditions. Single shot and averaged velocity profiles are obtained in an air jet at room temperature. By modestly raising the temperature (100-200 degC) the OH production increases, resulting in an improvement of the signal-to-noise ratio (SNR). Use of nitrogen - a non-reactive gas with minimal collisional quenching - extends the OH species lifetime (to over 500 µs), which allows probing of slower flows or, alternately, increases the measurement precision at the expense of spatial resolution. Instantaneous velocity profiles are resolved in a 100degC nitrogen jet (maximum jet-center velocity of 6.5 m/s) with an uncertainty down to 0.10 m/s (1.5%) at 68% confidence level. MTV measurements are compared with particle image velocimetry and show agreement within 2%.

  16. Design, Construction, Alignment, and Calibration of a Compact Velocimetry Experiment

    SciTech Connect

    Kaufman, Morris I.; Malone, Robert M.; Frogget, Brent C.; Esquibel, David L.; Romero, Vincent T.; Lare, Gregory A.; Briggs, Bart; Iverson, Adam J.; Frayer, Daniel K.; DeVore, Douglas; Cata, Brian

    2007-09-21

    A velocimetry experiment has been designed to measure shock properties for small cylindrical metal targets (8-mm-diameter by 2-mm thick). A target is accelerated by high explosives, caught, and retrieved for later inspection. The target is expected to move at a velocity of 0.1 to 3 km/sec. The complete experiment canister is approximately 105 mm in diameter and 380 mm long. Optical velocimetry diagnostics include the Velocity Interferometer System for Any Reflector (VISAR) and Photon Doppler Velocimetry (PDV). The packaging of the velocity diagnostics is not allowed to interfere with the catchment or an X-ray imaging diagnostic. A single optical relay, using commercial lenses, collects Doppler-shifted light for both VISAR and PDV. The use of fiber optics allows measurement of point velocities on the target surface during accelerations occurring over 15 mm of travel. The VISAR operates at 532 nm and has separate illumination fibers requiring alignment. The PDV diagnostic operates at 1550 nm, but is aligned and focused at 670 nm. The VISAR and PDV diagnostics are complementary measurements and they image spots in close proximity on the target surface. Because the optical relay uses commercial glass, the axial positions of the optical fibers for PDV and VISAR are offset to compensate for chromatic aberrations. The optomechanical design requires careful attention to fiber management, mechanical assembly and disassembly, positioning of the foam catchment, and X-ray diagnostic field-of-view. Calibration and alignment data are archived at each stage of the assembly sequence.

  17. Microparticles as Potential Biomarkers of Cardiovascular Disease

    PubMed Central

    França, Carolina Nunes; Izar, Maria Cristina de Oliveira; do Amaral, Jônatas Bussador; Tegani, Daniela Melo; Fonseca, Francisco Antonio Helfenstein

    2015-01-01

    Primary prevention of cardiovascular disease is a choice of great relevance because of its impact on health. Some biomarkers, such as microparticles derived from different cell populations, have been considered useful in the assessment of cardiovascular disease. Microparticles are released by the membrane structures of different cell types upon activation or apoptosis, and are present in the plasma of healthy individuals (in levels considered physiological) and in patients with different pathologies. Many studies have suggested an association between microparticles and different pathological conditions, mainly the relationship with the development of cardiovascular diseases. Moreover, the effects of different lipid-lowering therapies have been described in regard to measurement of microparticles. The studies are still controversial regarding the levels of microparticles that can be considered pathological. In addition, the methodologies used still vary, suggesting the need for standardization of the different protocols applied, aiming at using microparticles as biomarkers in clinical practice. PMID:25626759

  18. Method for determining surface properties of microparticles

    DOEpatents

    Eisenthal, Kenneth B.

    2000-01-01

    Second harmonic generation (SHG), sum frequency generation (SFG) and difference frequency generation (DFG) can be used for surface analysis or characterization of microparticles having a non-metallic surface feature. The microparticles can be centrosymmetric or such that non-metallic molecules of interest are centrosymmetrically distributed inside and outside the microparticles but not at the surface of the microparticles where the asymmetry aligns the molecules. The signal is quadratic in incident laser intensity or proportional to the product of two incident laser intensities for SFG, it is sharply peaked at the second harmonic wavelength, quadratic in the density of molecules adsorbed onto the microparticle surface, and linear in microparticles density. In medical or pharmacological applications, molecules of interest may be of drugs or toxins, for example.

  19. Doppler Global Velocimetry Measurements for Supersonic Flow Fields

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    2005-01-01

    The application of Doppler Global Velocimetry (DGV) to high-speed flows has its origins in the original development of the technology by Komine et al (1991). Komine used a small shop-air driven nozzle to generate a 200 m/s flow. This flow velocity was chosen since it produced a fairly large Doppler shift in the scattered light, resulting in a significant transmission loss as the light passed through the Iodine vapor. This proof-of-concept investigation showed that the technology was capable of measuring flow velocity within a measurement plane defined by a single-frequency laser light sheet. The effort also proved that velocity measurements could be made without resolving individual seed particles as required by other techniques such as Fringe- Type Laser Velocimetry and Particle Image Velocimetry. The promise of making planar velocity measurements with the possibility of using 0.1-micron condensation particles for seeding, Dibble et al (1989), resulted in the investigation of supersonic jet flow fields, Elliott et al (1993) and Smith and Northam (1995) - Mach 2.0 and 1.9 respectively. Meyers (1993) conducted a wind tunnel investigation above an inclined flat plate at Mach 2.5 and above a delta wing at Mach 2.8 and 4.6. Although these measurements were crude from an accuracy viewpoint, they did prove that the technology could be used to study supersonic flows using condensation as the scattering medium. Since then several research groups have studied the technology and developed solutions and methodologies to overcome most of the measurement accuracy limitations:

  20. Laser Velocimetry: The Elusive Third Component

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1985-01-01

    The historical development of techniques for measuring three velocity components using laser velocimetry is presented. The techniques are described and their relative merits presented. Many of the approaches currently in use based on the fringe laser velocimeter have yielded inaccurate measurements of turbulence intensity in the on-axis component. A possible explanation for these inaccuracies is presented along with simulation results.

  1. Tandem mass spectrometry of individual airborne microparticles

    SciTech Connect

    Reilly, P.T.A.; Gieray, R.A.; Yang, M.; Whitten, W.B.; Ramsey, J.M.

    1997-01-01

    An apparatus for real-time MS/MS analysis of individual airborne microparticles by laser ablation in an ion trap is described. The performance has been demonstrated by the detection of tributyl phosphate and bis(2-ethylhexyl) phosphate on silicon carbide and kaolin microparticles. 28 refs., 5 figs.

  2. Application of confocal Raman microscopy to investigate casein micro-particles in blend casein/pectin films.

    PubMed

    Zhuang, Yu; Sterr, Julia; Kulozik, Ulrich; Gebhardt, Ronald

    2015-03-01

    Pectin triggers formation of casein micro-particles during solution casting. Confocal Raman microscopy revealed their composition and spatial dimension in resulting films. Peaks in the Raman spectra corresponded to those found in films prepared by either casein or pectin. This suggested that no conformational changes occurred after mixing. Raman images revealed incompatibility of both polymers because particles consisted of casein only and the surrounding matrix of pectin. Deformation of micro-particles into an oblate shape took place during film formation. In dried films, an empty space between casein and pectin was found in lateral dimension. In contrast, casein micro-particles overlapped with the pectin matrix in the vertical dimension.

  3. Thulium-170-labeled microparticles for local radiotherapy: preliminary studies.

    PubMed

    Polyak, Andras; Das, Tapas; Chakraborty, Sudipta; Kiraly, Reka; Dabasi, Gabriella; Joba, Robert Peter; Jakab, Csaba; Thuroczy, Julianna; Postenyi, Zita; Haasz, Veronika; Janoki, Gergely; Janoki, Gyozo A; Pillai, Maroor R A; Balogh, Lajos

    2014-10-01

    The present article describes the preparation, characterization, and biological evaluation of Thulium-170 ((170)Tm) [T1/2 = 128.4 days; Eβmax = 968 keV; Eγ = 84 keV (3.26%)] labeled tin oxide microparticles for its possible use in radiation synovectomy (RSV) of medium-sized joints. (170)Tm was produced by irradiation of natural thulium oxide target. 170Tm-labeled microparticles were synthesized with high yield and radionuclidic purity (> 99%) along with excellent in vitro stability by following a simple process. Particle sizes and morphology of the radiolabeled particles were examined by light microscope, dynamic light scattering, and transmission electron microscope and found to be of stable spherical morphology within the range of 1.4-3.2 μm. The preparation was injected into the knee joints of healthy Beagle dogs intraarticularly for biological studies. Serial whole-body and regional images were taken by single-photon-emission computed tomography (SPECT) and SPECT-CT cameras up to 9 months postadministration, which showed very low leakage (< 8% of I.D.) of the instilled particles. The majority of leaked radiocolloid particles were found in inguinal lymph nodes during the 9 months of follow-up. All the animals tolerated the treatment well; the compound did not show any possible radiotoxicological effect. These preliminary studies showed that 170Tm-labeled microparticles could be a promising nontoxic and effective radiopharmaceutical for RSV applications or later local antitumor therapy.

  4. Application of Doppler global velocimetry in cryogenic wind tunnels

    NASA Astrophysics Data System (ADS)

    Willert, C.; Stockhausen, G.; Beversdorff, M.; Klinner, J.; Lempereur, C.; Barricau, P.; Quest, J.; Jansen, U.

    2005-08-01

    A specially designed Doppler global velocimetry system (DGV, planar Doppler velocimetry) was developed and installed in a high-speed cryogenic wind tunnel facility for use at free stream Mach numbers between 0.2 and 0.88, and pressures between 1.2 bar and 3.3 bar. Particle seeding was achieved by injecting a mixture of gaseous nitrogen and water vapor into the dry and cold tunnel flow, which then immediately formed a large amount of small ice crystals. Given the limited physical and optical access for this facility, DGV is considered the best choice for non-intrusive flow field measurements. A multiple branch fiber imaging bundle attached to a common DGV image receiving system simultaneously viewed a common area in the flow field from three different directions through the wind tunnel side walls. The complete imaging system and fiber-fed light sheet generators were installed inside the normally inaccessible pressure plenum surrounding the wind tunnel’s test section. The system control and frequency-stabilized laser system were placed outside of the pressure shell. With a field of view of 300×300 mm2, the DGV system acquired flow maps at a spatial resolution of 3×3 mm2 in the wake of simple vortex generators as well as in the wake of different wing-tip devices on a half-span aircraft model. Although problems mainly relating to light reflections and icing on the observation windows significantly impaired part of the measurements, the remotely controlled hardware operated reliably over the course of three months.

  5. Laser Velocimetry of Chemical Vapor Deposition Flows

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Laser velocimetry (LV) is being used to measure the gas flows in chemical vapor deposition (CVD) reactors. These gas flow measurements can be used to improve industrial processes in semiconductor and optical layer deposition and to validate numerical models. Visible in the center of the picture is the graphite susceptor glowing orange-hot at 600 degrees C. It is inductively heated via the copper cool surrounding the glass reactor.

  6. Microparticles prepared from sulfenamide-based polymers

    PubMed Central

    D’Mello, Sheetal R.; Yoo, Jun; Bowden, Ned B.; Salem, Aliasger K.

    2015-01-01

    Polysulfenamides (PSN), with a SN linkage (RSNR2) along the polymer backbone, are a new class of biodegradable and biocompatible polymers. These polymers were unknown prior to 2012 when their synthesis and medicinally relevant properties were reported. The aim of this study was to develop microparticles as a controlled drug delivery system using polysulfenamide as the matrix material. The microparticles were prepared by a water-in-oil-in-water double emulsion solvent evaporation method. For producing drug-loaded particles, FITC-dextran was used as a model hydrophilic compound. At the optimal formulation conditions, the external morphology of the PSN microparticles was examined by scanning electron microscopy to show the formation of smooth-surfaced spherical particles with low polydispersity. The microparticles had a net negative surface charge (−23 mV) as analyzed by the zetasizer. The drug encapsulation efficiency of the particles and the drug loading were found to be dependent on the drug molecular weight, amount of FITC-dextran used in fabricating FITC-dextran loaded microparticles, concentration of PSN and surfactant, and volume of the internal and external water phases. FITC-dextran was found to be distributed throughout the PSN microparticles and was released in an initial burst followed by more continuous release over time. Confocal laser scanning microscopy was used to qualitatively observe the cellular uptake of PSN microparticles and indicated localization of the particles in both the cytoplasm and the nucleus. PMID:23862723

  7. Velocimetry Overview for visitors from the DOD

    SciTech Connect

    Briggs, Matthew E.; Holtkamp, David Bruce

    2016-08-19

    We are in the midst of a transformative period in which technological advances are making fundamental changes in the measurement techniques that form the backbone of nuclear weapon certification. Optical velocimetry has replaced electrical shorting pins in “Hydrotests,” which measure the dynamic implosion process. This advance has revolutionized nuclear weapons certification during the last 5 years. We can now measure the implosion process that drives a nuclear detonation with many orders of magnitude more resolution in both space and time than was possible just 10 years ago. It has been compared to going from Morse Code to HDTV, resulting in a dozen or more improvements in models of these weapons. These Hydrotests are carried out at LANL, LLNL and the NNSS, with the later holding the important role of allowing us to test with nuclear materials, in sub-critical configurations (i.e., no yield.) Each of these institutions has largely replaced pins with hundreds of channels of optical velocimetry. Velocimetry is non-contact and is used simultaneously with the X-ray capability of these facilities. The U1-a facility at NNSS pioneered this approach in the Gemini series in 2012, and continues to lead, both in channel count and technological advances. Close cooperation among LANL, LLNL and NSTec in these advances serves the complex by leveraging capabilities across sites and accelerating the pace of technical improvements.

  8. Rubidium Atomic Line Filtered (RALF) Doppler Velocimetry

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario; Molek, Christopher; Vesely, Annamaria

    2015-06-01

    We report the successful proof-of-concept demonstration of the Rubidium Atomic Line Filtered (RALF) Doppler velocimetry technique. RALF is a high-velocity and high-acceleration adaptation of the Global Doppler Velocimetry (GDV) method developed in the 1990s by aerodynamics researchers. Laser velocimetry techniques in common use within the shock physics community (e . g . VISAR, Fabry-Perot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to convert the Doppler shift of reflected λ0 ~ 780.24 nm light directly into transmitted light intensity. The single-point RALF apparatus used in these experiments is fiber optic based, and incorporates a simultaneous PDV measurement channel as an ``internal standard'' for validation of the RALF results. Future plans include ``line-RALF'' experiments with streak camera detection, and two-dimensional surface velocity mapping using pulsed laser illumination and gated intensified CCD camera detection. [RW PA#4931

  9. Nitric oxide scavenging by red cell microparticles.

    PubMed

    Liu, Chen; Zhao, Weixin; Christ, George J; Gladwin, Mark T; Kim-Shapiro, Daniel B

    2013-12-01

    Red cell microparticles form during the storage of red blood cells and in diseases associated with red cell breakdown and asplenia, including hemolytic anemias such as sickle cell disease. These small phospholipid vesicles that are derived from red blood cells have been implicated in the pathogenesis of transfusion of aged stored blood and hemolytic diseases, via activation of the hemostatic system and effects on nitric oxide (NO) bioavailability. Red cell microparticles react with the important signaling molecule NO almost as fast as cell-free hemoglobin, about 1000 times faster than red-cell-encapsulated hemoglobin. The degree to which this fast reaction with NO by red cell microparticles influences NO bioavailability depends on several factors that are explored here. In the context of stored blood preserved in ADSOL, we find that both cell-free hemoglobin and red cell microparticles increase as a function of duration of storage, and the proportion of extra erythrocytic hemoglobin in the red cell microparticle fraction is about 20% throughout storage. Normalized by hemoglobin concentration, the NO-scavenging ability of cell-free hemoglobin is slightly higher than that of red cell microparticles as determined by a chemiluminescence NO-scavenging assay. Computational simulations show that the degree to which red cell microparticles scavenge NO will depend substantially on whether they enter the cell-free zone next to the endothelial cells. Single-microvessel myography experiments performed under laminar flow conditions demonstrate that microparticles significantly enter the cell-free zone and inhibit acetylcholine, endothelial-dependent, and NO-dependent vasodilation. Taken together, these data suggest that as little as 5 μM hemoglobin in red cell microparticles, an amount formed after the infusion of one unit of aged stored packed red blood cells, has the potential to reduce NO bioavailability and impair endothelial-dependent vasodilation.

  10. Emulsification/internal gelation as a method for preparation of diclofenac sodium-sodium alginate microparticles.

    PubMed

    Ahmed, Mahmoud M; El-Rasoul, Saleh Abd; Auda, Sayed H; Ibrahim, Mohamed A

    2013-01-01

    Emulsification/internal gelation has been suggested as an alternative to extrusion/external gelation in the encapsulation of several compounds including non-steroidal anti-inflammatory drugs such as diclofenac sodium. The objective of the present study was a trial to formulate diclofenac sodium as controlled release microparticles that might be administered once or twice daily. This could be achieved via emulsification/internal gelation technique applying Box-Behnken design to choose these formulae. Box-Behnken design determined fifteen formulae containing specified amounts of the independent variables, which included stirring speed in rpm (X1), drug:polymer ratio (X2) and the surfactant span 80% (X3). The dependent variables studied were cumulative percent release after two hours (Y1), four hours (Y2) and eight hours (Y3). The prepared microparticles were characterized for their production yield, sizes, shapes and morphology, entrapment efficiency and Diclofenac sodium in vitro release as well. The results showed that the production yield of the prepared diclofenac sodium microparticles was found to be between 79.55% and 97.41%. The formulated microparticles exhibited acceptable drug content values that lie in the range 66.20-96.36%. Also, the data obtained revealed that increasing the mixing speed (X1) generally resulted in decreased microparticle size. In addition, scanning electron microscope images of the microparticles illustrated that the formula contains lower span concentration (1%) in combination with lower stirring speed (200 rpm) which showed wrinkled, but smooth surfaces. However, by increasing surfactant concentration, microspheres' surfaces become smoother and slightly porous. Kinetic treatment of the in vitro release from drug-loaded microparticles indicated that the zero order is the drug release mechanism for the most formulae.

  11. Flow Visualization and Laser Velocimetry for Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Hunter, W. W., Jr. (Editor); Foughner, J. T., Jr. (Editor)

    1982-01-01

    The need for flow visualization and laser velocimetry were discussed. The purpose was threefold: (1) provide a state-of-the-art overview; (2) provide a forum for industry, universities, and government agencies to address problems in developing useful and productive flow visualization and laser velocimetry measurement techniques; and (3) provide discussion of recent developments and applications of flow visualization and laser velocimetry measurement techniques and instrumentation systems for wind tunnels including the 0.3-Meter Transonic Cryogenic Tunnel.

  12. Tunneling holes in microparticles to facilitate the transport of lithium ions for high volumetric density batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Ng, K. Y. Simon; Deng, Da

    2015-08-01

    electrolyte than that of nanoparticles. Therefore, it will be interesting to tunnel-holes in the high volumetric density microparticles to facilitate the reversible storage of lithium ions. Here, tunnel-like holes were generated in microparticles to dramatically increase the accessibility of the active materials to facilitate the lithium ion transfer. A plausible formation mechanism to explain the generation of tunnel-like holes was proposed based on time-course experiments and intensive characterization. Impressively, the as-prepared microbeads with tunnels demonstrated dramatically improved performance compared to the solid microbeads without tunnels in lithium ion storage. The microparticles with tunnels could achieve comparable electrochemical performances to those nanoparticles reported in the literature, suggesting that microparticles, properly tuned, could be promising candidates as negative electrodes for lithium-ion batteries and worthy of further studies. We also directly measured the volumetric density of the microparticles. We would like to highlight that a superior volumetric capacity of 514 mA h cm-3 has been achieved. We hope to promote more frequent use of the unit mA h cm-3 in addition to the conventional unit mA h g-1 in the battery community. Electronic supplementary information (ESI) available: Optical and FESEM images, BET surface area and pore size distribution, electrochemical performance in terms of specific capacity and the dQ/dV vs. V plot of the 80th cycle. See DOI: 10.1039/c5nr03840e

  13. Trojan Microparticles for Drug Delivery

    PubMed Central

    Anton, Nicolas; Jakhmola, Anshuman; Vandamme, Thierry F.

    2012-01-01

    During the last decade, the US Food and Drug Administration (FDA) have regulated a wide range of products, (foods, cosmetics, drugs, devices, veterinary, and tobacco) which may utilize micro and nanotechnology or contain nanomaterials. Nanotechnology allows scientists to create, explore, and manipulate materials in nano-regime. Such materials have chemical, physical, and biological properties that are quite different from their bulk counterparts. For pharmaceutical applications and in order to improve their administration (oral, pulmonary and dermal), the nanocarriers can be spread into microparticles. These supramolecular associations can also modulate the kinetic releases of drugs entrapped in the nanoparticles. Different strategies to produce these hybrid particles and to optimize the release kinetics of encapsulated drugs are discussed in this review. PMID:24300177

  14. Microparticles and type 2 diabetes.

    PubMed

    Leroyer, A S; Tedgui, A; Boulanger, C M

    2008-02-01

    Cell activation or apoptosis leads to plasma membrane blebbing and microparticles (MPs) release in the extracellular space. MPs are submicron membrane vesicles, which harbour a panel of oxidized phospholipids and proteins specific to the cells they derived from. MPs are found in the circulating blood of healthy volunteers. MPs levels are increased in many diseases, including cardiovascular diseases with high thrombotic risk. Exposure of negatively charged phospholipids and tissue factor confers a procoagulant potential to MPs. Elevation of plasma MPs levels, particularly those of endothelial origin, reflects cellular injury and appears now as a surrogate marker of vascular dysfunction. Recent studies demonstrate an elevation of circulating levels of MPs in diabetes. MPs could also be involved in the development of vascular complications in diabetes for they stimulate pro-inflammatory responses in target cells and promote thrombosis, endothelial dysfunction and angiogenesis. Thus, these studies provide new insight in the pathogenesis and treatment of vascular complications of diabetes.

  15. Uniform biodegradable microparticle systems for controlled release

    PubMed Central

    Xia, Yujie; Pack, Daniel W.

    2014-01-01

    Drug delivery methods can impact efficacy as much as the nature of the drug itself. Microparticles made of biodegradable polymers such as poly(D,L-lactide-co-glycolide) and poly(lactic acid) (PLA) have been studied extensively for controlled release of diverse drugs. By using a modified solvent extraction/evaporation method called precision particle fabrication (PPF), uniform microparticles such as single-wall microspheres, double-wall microspheres and liquid-core microcapsules have been fabricated with precise control of their geometric structures. By producing particles of uniform size, which has crucial impact on drug release behaviors, PPF-fabricated microparticles provide unique insights about drug release mechanism. Using small-molecule and macromolecule model drugs, our group demonstrated that physicochemical properties of the polymers and drugs and structural properties of the matrix can greatly impact drug distribution within microparticles, particle erosion and drug release rates. By careful selection of particle size and shell thickness, uniform microparticles can achieve “zero-order”, pulsatile or tandem release of drugs. PMID:12106984

  16. Circulating microparticles: square the circle

    PubMed Central

    2013-01-01

    Background The present review summarizes current knowledge about microparticles (MPs) and provides a systematic overview of last 20 years of research on circulating MPs, with particular focus on their clinical relevance. Results MPs are a heterogeneous population of cell-derived vesicles, with sizes ranging between 50 and 1000 nm. MPs are capable of transferring peptides, proteins, lipid components, microRNA, mRNA, and DNA from one cell to another without direct cell-to-cell contact. Growing evidence suggests that MPs present in peripheral blood and body fluids contribute to the development and progression of cancer, and are of pathophysiological relevance for autoimmune, inflammatory, infectious, cardiovascular, hematological, and other diseases. MPs have large diagnostic potential as biomarkers; however, due to current technological limitations in purification of MPs and an absence of standardized methods of MP detection, challenges remain in validating the potential of MPs as a non-invasive and early diagnostic platform. Conclusions Improvements in the effective deciphering of MP molecular signatures will be critical not only for diagnostics, but also for the evaluation of treatment regimens and predicting disease outcomes. PMID:23607880

  17. Energetics of jellyfish locomotion determined from field measurements using a Self- Contained Underwater Velocimetry Apparatus (SCUVA)

    NASA Astrophysics Data System (ADS)

    Katija, K.; Dabiri, J. O.

    2007-12-01

    We conduct laboratory measurements of the flow fields induced by Aurelia labiata over a range of sizes using the method of digital particle image velocimetry (DPIV). The flow field measurements are used to directly quantify the kinetic energy induced by the swimming motions of individual medusae. This method provides details regarding the temporal evolution of the energetics during a swimming cycle and its scaling with bell diameter. These types of measurements also allow for the determination of propulsive efficiency, which can be used to compare various methods of propulsion, both biological and artificial. We then describe the development and application of a Self-Contained Underwater Velocimetry Apparatus (SCUVA), a device that enables a single SCUBA diver to make DPIV measurements of animal-fluid interactions in the field. Improvements and adjustments made to the original system will be presented, and a comparison between the animal-induced flow fields in the laboratory and in the field will be made.

  18. Real-time dynamics of high-velocity micro-particle impact

    NASA Astrophysics Data System (ADS)

    Veysset, David; Hsieh, Alex; Kooi, Steve; Maznev, Alex A.; Tang, Shengchang; Olsen, Bradley D.; Nelson, Keith A.

    High-velocity micro-particle impact is important for many areas of science and technology, from space exploration to the development of novel drug delivery platforms. We present real-time observations of supersonic micro-particle impacts using multi-frame imaging. In an all optical laser-induced projectile impact test, a monolayer of micro-particles is placed on a transparent substrate coated with a laser absorbing polymer layer. Ablation of a laser-irradiated polymer region accelerates the micro-particles into free space with speeds up to 1.0 km/s. The particles are monitored during the impact on the target with an ultrahigh-speed multi-frame camera that can record up to 16 images with time resolution as short as 3 ns. In particular, we investigated the high-velocity impact deformation response of poly(urethane urea) (PUU) elastomers to further the fundamental understanding of the molecular influence on dynamical behaviors of PUUs. We show the dynamic-stiffening response of the PUUs and demonstrate the significance of segmental dynamics in the response. We also present movies capturing individual particle impact and penetration in gels, and discuss the observed dynamics. The results will provide an impetus for modeling high-velocity microscale impact responses and high strain rate deformation in polymers, gels, and other materials.

  19. Agglomeration of microparticles in complex plasmas

    SciTech Connect

    Du, Cheng-Ran; Thomas, Hubertus M.; Ivlev, Alexei V.; Konopka, Uwe; Morfill, Gregor E.

    2010-11-15

    Agglomeration of highly charged microparticles was observed and studied in complex plasma experiments carried out in a capacitively coupled rf discharge. The agglomeration was caused by strong waves triggered in a particle cloud by decreasing neutral gas pressure. Using a high-speed camera during this unstable regime, it was possible to resolve the motion of individual microparticles and to show that the relative velocities of some particles were sufficiently high to overcome the mutual Coulomb repulsion and hence to result in agglomeration. After stabilizing the cloud again through the increase of the pressure, we were able to observe the aggregates directly with a long-distance microscope. We show that the agglomeration rate deduced from our experiments is in good agreement with theoretical estimates. In addition, we briefly discuss the mechanisms that can provide binding of highly charged microparticles in a plasma.

  20. Microparticle trapping in an ultrasonic Bessel beam.

    PubMed

    Choe, Youngki; Kim, Jonathan W; Shung, K Kirk; Kim, Eun Sok

    2011-12-05

    This paper describes an acoustic trap consisting of a multi-foci Fresnel lens on 127 μm thick lead zirconate titanate sheet. The multi-foci Fresnel lens was designed to have similar working mechanism to an Axicon lens and generates an acoustic Bessel beam, and has negative axial radiation force capable of trapping one or more microparticle(s). The fabricated acoustic tweezers trapped lipid particles ranging in diameter from 50 to 200 μm and microspheres ranging in diameter from 70 to 90 μm at a distance of 2 to 5 mm from the tweezers without any contact between the transducer and microparticles.

  1. Microparticle trapping in an ultrasonic Bessel beam

    PubMed Central

    Choe, Youngki; Kim, Jonathan W.; Shung, K. Kirk; Kim, Eun Sok

    2011-01-01

    This paper describes an acoustic trap consisting of a multi-foci Fresnel lens on 127 μm thick lead zirconate titanate sheet. The multi-foci Fresnel lens was designed to have similar working mechanism to an Axicon lens and generates an acoustic Bessel beam, and has negative axial radiation force capable of trapping one or more microparticle(s). The fabricated acoustic tweezers trapped lipid particles ranging in diameter from 50 to 200 μm and microspheres ranging in diameter from 70 to 90 μm at a distance of 2 to 5 mm from the tweezers without any contact between the transducer and microparticles. PMID:22247566

  2. Externally Dispersed Interferometry for Precision Radial Velocimetry

    SciTech Connect

    Erskine, D J; Muterspaugh, M W; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E

    2007-03-27

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  3. Optical Coherence Tomography Velocimetry with Complex Fluids

    NASA Astrophysics Data System (ADS)

    Malm, A.; Waigh, T. A.; Jaradat, S.; Tomlin, R.

    2015-04-01

    We present recent results obtained with an Optical Coherence Tomography Velocimetry technique. An optical interferometer measures the velocity of a sheared fluid at specific depths of the sample using the coherence length of the light source. The technique allows the dynamics of 3 pico liter volumes to be probed inside opaque complex fluids. In a study of opaque starch suspensions, classical bulk rheology experiments show non-linear shear thickening, whereas observations of the velocity profiles as a function of distance across the gap show Newtonian behavior. The ability of the technique to measure velocity fluctuations is also discussed for the case of polyacrylamide samples which were observed to display shear banding behavior. A relationship between the viscoelasticity of the sample and the size of the apparent fluctuations is observed.

  4. Design, Assembly, and Testing of a Photon Doppler Velocimetry Probe

    SciTech Connect

    Malone, Robert M; Cox, Brian C; Daykin, Edward P; DeVore, Douglas O; Esquibel, David L; Frayer, Daniel K; Frogget, Brent C; Gallegos, Cenobio H; Kaufman, Morris I; McGillivray, Kevin D; Romero, Vincent T; Briggs, Matthew E; Furlanetto, Michael R; Holtkamp, David B; Pazuchanics, Peter; Primas, Lori E; Shinas, Michael A; Sorenson, Danny S

    2011-08-21

    A novel fiber-optic probe measures the velocity distribution of an imploding surface along many lines of sight. Reflected light from each spot on the moving surface is Doppler shifted with a small portion of this light propagating backwards through the launching fiber. The reflected light is mixed with a reference laser in a technique called photon Doppler velocimetry, providing continuous time records. Within the probe, a matrix array of 56 single-mode fibers sends light through an optical relay consisting of three types of lenses. Seven sets of these relay lenses are grouped into a close-packed array allowing the interrogation of seven regions of interest. A six-faceted prism with a hole drilled into its center directs the light beams to the different regions. Several types of relay lens systems have been evaluated, including doublets and molded aspheric singlets. The optical design minimizes beam diameters and also provides excellent imaging capabilities. One of the fiber matrix arrays can be replaced by an imaging coherent bundle. This close-packed array of seven relay systems provides up to 476 beam trajectories. The pyramid prism has its six facets polished at two different angles that will vary the density of surface point coverage. Fibers in the matrix arrays are angle polished at 8{sup o} to minimize back reflections. This causes the minimum beam waist to vary along different trajectories. Precision metrology on the direction cosine trajectories is measured to satisfy environmental requirements for vibration and temperature.

  5. Interference microscopy: Super-resolution particle tracking and velocimetry

    NASA Astrophysics Data System (ADS)

    Snoeyink, Craig A.

    This dissertation describes the theory and applications of a new approach to imaging called Interference Microscopy (IM). Interfere Microscopy works by inserting a lens and axicon into the optical path of an imaging system. The lens and axicon serve to re-image the image produced by the original optical system. However, instead of imaging a point in the measurement plane to a point in an image plane, the IM system maps a point along a line produced by an interference pattern. This unique interference pattern, called a Bessel beam, allows for several unique applications of the IM system. The first chapter of this dissertation describes a rigorous derivation of the three dimensional point spread function of the IM system. Using the Frenel Diffraction Integral, light from a paraxial off axis point source is propagated through the axicon to an imaging plane. The resulting analytical expression for the diffraction pattern produced is then experimentally verified. Chapter 2 covers the use of IM for single view three dimensional particle locating. This application relies on the analytical expression for the three dimensional point spread function of the IM system. Once the properties of an interference pattern produced by a particle are determined, it is possible to directly calculate the three dimensional location of the particle that produced it. Image analysis algorithms to determine interference pattern properties are described and the method is experimentally verified and applied to pressure driven flow in a rectangular channel and to a particle carried by an electrothermal vortex. A measurement depth of 200 μm is demonstrated with an accuracy of ± 3 μm in calculating the height of the particle. In the third chapter the IM system is applied to another velocity measurement technique, Particle Image Velocimetry (PIV). Here, simulated images of a typical microscope and the same microscope with the IM attachment are used to investigate the resolution limits of PIV

  6. Circulating Microparticles Alter Formation, Structure, and Properties of Fibrin Clots

    PubMed Central

    Zubairova, Laily D.; Nabiullina, Roza M.; Nagaswami, Chandrasekaran; Zuev, Yuriy F.; Mustafin, Ilshat G.; Litvinov, Rustem I.; Weisel, John W.

    2015-01-01

    Despite the importance of circulating microparticles in haemostasis and thrombosis, there is limited evidence for potential causative effects of naturally produced cell-derived microparticles on fibrin clot formation and its properties. We studied the significance of blood microparticles for fibrin formation, structure, and susceptibility to fibrinolysis by removing them from platelet-free plasma using filtration. Clots made in platelet-free and microparticle-depleted plasma samples from the same healthy donors were analyzed in parallel. Microparticles accelerate fibrin polymerisation and support formation of more compact clots that resist internal and external fibrinolysis. These variations correlate with faster thrombin generation, suggesting thrombin-mediated kinetic effects of microparticles on fibrin formation, structure, and properties. In addition, clots formed in the presence of microparticles, unlike clots from the microparticle-depleted plasma, contain 0.1–0.5-μm size granular and CD61-positive material on fibres, suggesting that platelet-derived microparticles attach to fibrin. Therefore, the blood of healthy individuals contains functional microparticles at the levels that have a procoagulant potential. They affect the structure and stability of fibrin clots indirectly through acceleration of thrombin generation and through direct physical incorporation into the fibrin network. Both mechanisms underlie a potential role of microparticles in haemostasis and thrombosis as modulators of fibrin formation, structure, and resistance to fibrinolysis. PMID:26635081

  7. Microparticles: new light shed on the understanding of venous thromboembolism

    PubMed Central

    Zhou, Lin; Qi, Xiao-long; Xu, Ming-xin; Mao, Yu; Liu, Ming-lin; Song, Hao-ming

    2014-01-01

    Microparticles are small membrane fragments shed primarily from blood and endothelial cells during either activation or apoptosis. There is mounting evidence suggesting that microparticles perform a large array of biological functions and contribute to various diseases. Of these disease processes, a significant link has been established between microparticles and venous thromboembolism. Advances in research on the role of microparticles in thrombosis have yielded crucial insights into possible mechanisms, diagnoses and therapeutic targets of venous thromboembolism. In this review, we discuss the definition and properties of microparticles and venous thromboembolism, provide a synopsis of the evidence detailing the contributions of microparticles to venous thromboembolism, and propose potential mechanisms, by which venous thromboembolism occurs. Moreover, we illustrate a possible role of microparticles in cancer-related venous thromboembolism. PMID:25152025

  8. Strategy for the hemocompatibility testing of microparticles.

    PubMed

    Braune, S; Basu, S; Kratz, K; Johansson, J Bäckemo; Reinthaler, M; Lendlein, A; Jung, F

    2016-01-01

    Polymer-based microparticles are applied as non-thrombogenic or thrombogenic materials in a wide variety of intra- or extra-corporeal medical devices. As demanded by the regulatory agencies, the hemocompatibility of these blood contacting biomaterials has to be evaluated in vitro to ensure that the particle systems appropriately fulfill the envisioned function without causing undesired events such as thrombosis or inflammation. Currently described in vitro assays for hemocompatibility testing of particles comprise tests with different single cell types (e.g. erythrocytes or leukocytes), varying concentrations/dilutions of the used blood cells or whole blood, which are not standardized.Here, we report about an in vitro dynamic test system for studying the hemocompatibility of polymeric microparticles utilizing fresh human whole blood from apparently healthy subjects, collected and processed under standardized conditions. Spherical poly(ether imide) microparticles with an average diameter of 140±30 μm were utilized as model systems. Reported as candidate materials for the removal of uremic toxins, these microparticles are anticipated to facilitate optimal flow conditions in a dialyzer with minimal backflow and blood cell damage. Pristine (PEI) and potassium hydroxide (PEI-KOH) functionalized microparticles exhibited similarly nanoporous surfaces (PEI: ØExternal pore = 90±60 nm; PEI-KOH ØExternal pore = 150±130 nm) but varying water wettabilities (PEI: θadv = 112±10° PEI-KOH θadv = 60±2°). The nanoporosity of the microparticle surfaces allows the exchange of toxic solutes from blood towards the interconnective pores in the particle core, while an immigration of the substantially larger blood cells is inhibited.Sterilized PEI microparticles were incorporated -air-free -in a syringe-based test system and exposed to whole blood for 60 minutes under gentle agitation. Thereafter, thrombi formation on the particles surfaces were analyzed

  9. Synthesis, characterization and catalytic application of polyhedron zinc oxide microparticles

    NASA Astrophysics Data System (ADS)

    Jamil, Saba; Ramzan Saeed Ashraf Janjua, Muhammad; Khan, Shanza Rauf; Jahan, Nazish

    2017-01-01

    Zinc oxide (ZnO) microparticles of unique morphology were synthesized by the microwave heating method. The composition and morphology of the synthesized microparticles were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It is clear from the XRD pattern that the product is highly pure and crystalline. It is shown from the SEM images that the hexagonal unit cells are arranged in the form of a polyhedral lattice. The length of the sides is equal at the middle of the lattice, and unequal on the terminal sides of the lattice. This is due to the alignment of the hexagonal unit cells. The size distribution histogram of the product possesses a sharp band which shows that it is monodisperse. This means that a monodisperse product can be obtained by the microwave heating method. The synthesized particles were used as a catalyst for the thermal degradation of ammonium perchlorate (AP) and the catalytic reduction of 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP). The effect of temperature on the value of the apparent rate constant was also studied, and the values of the kinetic and thermodynamic parameters were calculated. This shows that the catalyst possesses high efficiency for thermally degrading of substances at low temperatures and rapidly reducing the nitroarenes in an aqueous medium.

  10. Encapsulation of Volatile Compounds in Silk Microparticles.

    PubMed

    Elia, Roberto; Guo, Jin; Budijono, Stephanie; Normand, Valery; Benczédi, Daniel; Omenetto, Fiorenzo; Kaplan, David L

    2015-07-01

    Various techniques have been employed to entrap fragrant oils within microcapsules or microparticles in the food, pharmaceutical, and chemical industries for improved stability and delivery. In the present work we describe the use of silk protein microparticles for encapsulating fragrant oils using ambient processing conditions to form an all-natural biocompatible matrix. These microparticles are stabilized via physical crosslinking, requiring no chemical agents, and are prepared with aqueous and ambient processing conditions using polyvinyl alcohol-silk emulsions. The particles were loaded with fragrant oils via direct immersion of the silk particles within an oil bath. The oil-containing microparticles were coated using alternating silk and polyethylene oxide layers to control the release of the oil from the microspheres. Particle morphology and size, oil loading capacity, release rates as well as silk-oil interactions and coating treatments were characterized. Thermal analysis demonstrated that the silk coatings can be tuned to alter both retention and release profiles of the encapsulated fragrance. These oil containing particles demonstrate the ability to adsorb and controllably release oils, suggesting a range of potential applications including cosmetic and fragrance utility.

  11. Hydrophobicity of silver surfaces with microparticle geometry

    NASA Astrophysics Data System (ADS)

    Macko, Ján; Oriňaková, Renáta; Oriňak, Andrej; Kovaľ, Karol; Kupková, Miriam; Erdélyi, Branislav; Kostecká, Zuzana; Smith, Roger M.

    2016-11-01

    The effect of the duration of the current deposition cycle and the number of current pulses on the geometry of silver microstructured surfaces and on the free surface energy, polarizability, hydrophobicity and thus adhesion force of the silver surfaces has been investigated. The changes in surface hydrophobicity were entirely dependent on the size and density of the microparticles on the surface. The results showed that formation of the silver microparticles was related to number of current pulses, while the duration of one current pulse played only a minor effect on the final surface microparticle geometry and thus on the surface tension and hydrophobicity. The conventional geometry of the silver particles has been transformed to the fractal dimension D. The surface hydrophobicity depended predominantly on the length of the dendrites not on their width. The highest silver surface hydrophobicity was observed on a surface prepared by 30 current pulses with a pulse duration of 1 s, the lowest one when deposition was performed by 10 current pulses with a duration of 0.1 s. The partial surface tension coefficients γDS and polarizability kS of the silver surfaces were calculated. Both parameters can be applied in future applications in living cells adhesion prediction and spectral method selection. Silver films with microparticle geometry showed a lower variability in final surface hydrophobicity when compared to nanostructured surfaces. The comparisons could be used to modify surfaces and to modulate human cells and bacterial adhesion on body implants, surgery instruments and clean surfaces.

  12. Study of high speed combustion flows by laser velocimetry

    NASA Technical Reports Server (NTRS)

    Schaefer, H. J.

    1984-01-01

    The feasibility of laser velocimetry in a high temperature jet was assessed in a model of an aircraft engine combustor. Experiments show that the problems encountered in measuring combustion flow can flow can be overcome by a carefully designed optical set-up and an appropriate signal processing and data acquisition system. Laser Doppler velocimetry provides useful information about coherent structures in hot free jets. The measurements agree with measurements in an isothermal jet.

  13. Volumetric microscale particle tracking velocimetry (PTV) in porous media

    NASA Astrophysics Data System (ADS)

    Guo, Tianqi; Aramideh, Soroush; Ardekani, Arezoo M.; Vlachos, Pavlos P.

    2016-11-01

    The steady-state flow through refractive-index-matched glass bead microchannels is measured using microscopic particle tracking velocimetry (μPTV). A novel technique is developed to volumetrically reconstruct particles from oversampled two-dimensional microscopic images of fluorescent particles. Fast oversampling of the quasi-steady-state flow field in the lateral direction is realized by a nano-positioning piezo stage synchronized with a fast CMOS camera. Experiments at different Reynolds numbers are carried out for flows through a series of both monodispersed and bidispersed glass bead microchannels with various porosities. The obtained velocity fields at pore-scale (on the order of 10 μm) are compared with direct numerical simulations (DNS) conducted in the exact same geometries reconstructed from micro-CT scans of the glass bead microchannels. The developed experimental method would serve as a new approach for exploring the flow physics at pore-scale in porous media, and also provide benchmark measurements for validation of numerical simulations.

  14. Clinical Relevance of Microparticles from Platelets and Megakaryocytes

    PubMed Central

    Italiano, Joseph E.; Mairuhu, Albert T.A.; Flaumenhaft, Robert

    2011-01-01

    Purpose of review Platelet microparticles were identified more than forty years ago and are the most abundant circulating microparticle subtype. Yet fundamental questions about their formation and role in human disease are just beginning to be understood at the cellular and molecular level. This review will address mechanisms of platelet microparticle generation and evaluate our current understanding of their clinical relevance. Recent findings New evidence indicates that the majority of CD41+ microparticles circulating in healthy individuals derive directly from megakaryocytes. CD41+ microparticles also form from activated platelets upon loss of cytoskeleton-membrane adhesion, which occurs in a multitude of disease states characterized by elevated platelet microparticle levels. More recent studies have demonstrated that platelet microparticles function as a transport and delivery system for bioactive molecules, participating in hemostasis and thrombosis, inflammation, malignancy infection transfer, angiogenesis, and immunity. The mechanism of platelet microparticle participation in specific disease entities such as rheumatoid arthritis has been elucidated. Summary Continued research into how platelet microparticles are generated and function as a transcellular delivery system will advance our basic understanding of microparticle physiology and may enable new strategies for treatment of select disease entities. PMID:20739880

  15. FLEET Velocimetry Measurements on a Transonic Airfoil

    NASA Technical Reports Server (NTRS)

    Burns, Ross A.; Danehy, Paul M.

    2017-01-01

    Femtosecond laser electronic excitation tagging (FLEET) velocimetry was used to study the flowfield around a symmetric, transonic airfoil in the NASA Langley 0.3-m TCT facility. A nominal Mach number of 0.85 was investigated with a total pressure of 125 kPa and total temperature of 280 K. Two-components of velocity were measured along vertical profiles at different locations above, below, and aft of the airfoil at angles of attack of 0 deg, 3.5 deg, and 7deg. Measurements were assessed for their accuracy, precision, dynamic range, spatial resolution, and overall measurement uncertainty in the context of the applied flowfield. Measurement precisions as low as 1 m/s were observed, while overall uncertainties ranged from 4 to 5 percent. Velocity profiles within the wake showed sufficient accuracy, precision, and sensitivity to resolve both the mean and fluctuating velocities and general flow physics such as shear layer growth. Evidence of flow separation is found at high angles of attack.

  16. Magnetophoresis of diamagnetic microparticles in a weak magnetic field.

    PubMed

    Zhu, Gui-Ping; Hejiazan, Majid; Huang, Xiaoyang; Nguyen, Nam-Trung

    2014-12-21

    Magnetic manipulation is a promising technique for lab-on-a-chip platforms. The magnetic approach can avoid problems associated with heat, surface charge, ionic concentration and pH level. The present paper investigates the migration of diamagnetic particles in a ferrofluid core stream that is sandwiched between two diamagnetic streams in a uniform magnetic field. The three-layer flow is expanded in a circular chamber for characterisation based on imaging of magnetic nanoparticles and fluorescent microparticles. A custom-made electromagnet generates a uniform magnetic field across the chamber. In a relatively weak uniform magnetic field, the diamagnetic particles in the ferrofluid move and spread across the chamber. Due to the magnetization gradient formed by the ferrofluid, diamagnetic particles undergo negative magnetophoresis and move towards the diamagnetic streams. The effects of magnetic field strength and the concentration of diamagnetic particles are studied in detail.

  17. Cellulose acetate butyrate microparticles for controlled release of carbamazepine.

    PubMed

    Arnaud, P; Boué, C; Chaumeil, J C

    1996-01-01

    Cellulose acetate butyrate microparticles loaded in carbamazepine were prepared by a solvent evaporation technique. A decrease of the amount of organic solvent (from 80 to 40 ml of methylene chloride) increased the microparticle average diameter (73-111 and 207 microns) and decreased the carbamazepine release rate (T50% increased from 3.3 to 16.8 and 166.4 min). The microparticle area under the curve at 120 min was similar to that obtained with Tegretol LP 200 tablets.

  18. Ion Velocimetry In Magnetized DC Sheaths

    NASA Astrophysics Data System (ADS)

    Young, Christopher; Lucca Fabris, Andrea; Cappelli, Mark

    2013-09-01

    Particle dynamics near the magnetic cusps in cusped field plasma thrusters are still not well understood; characterizing the ion velocity distribution functions in these regions can help thruster designs maximize electron trapping and minimize erosion of the channel wall. To that end, a robust argon ion velocity sensor is developed using a three-level laser-induced fluorescence (LIF) technique. The 3d4F7 / 2 --> 4p4D5/ 2 0 ArII transition at 668.61 nm is pumped with a 25 mW tunable external cavity diode laser, and fluorescence down to the 4s4P3 / 2 state at 442.72 nm is collected with phase-sensitive detection. The Doppler shift in the acquired signal peak, compared to a stationary reference, gives the ion velocity component parallel to the exciting laser. We demonstrate this LIF scheme by obtaining the argon ion velocity profile through a magnetized DC sheath. The LIF measurement is used to validate a new optogalvanic velocimetry technique in which two lasers (chopped at different frequencies) intersect one another at 90° in the measurement volume. Using a lock-in amplifier, changes observed in the DC discharge current at the sum and difference of the two chopping frequencies may be related back to the mean ion velocity at that point. The authors acknowledge support from the Air Force Office of Scientific Research (AFOSR). CY acknowledges support from the DOE NNSA Stewardship Science Graduate Fellowship under contract DE-FC52-08NA28752.

  19. One-step production of multilayered microparticles by tri-axial electro-flow focusing

    NASA Astrophysics Data System (ADS)

    Si, Ting; Feng, Hanxin; Li, Yang; Luo, Xisheng; Xu, Ronald

    2014-03-01

    Microencapsulation of drugs and imaging agents in the same carrier is of great significance for simultaneous detection and treatment of diseases. In this work, we have developed a tri-axial electro-flow focusing (TEFF) device using three needles with a novel concentric arrangement to one-step form multilayered microparticles. The TEFF process can be characterized as a multi-fluidic compound cone-jet configuration in the core of a high-speed coflowing gas stream under an axial electric field. The tri-axial liquid jet eventually breaks up into multilayered droplets. To validate the method, the effect of main process parameters on characteristics of the cone and the jet has been studied experimentally. The applied electric field can dramatically promote the stability of the compound cone and enhance the atomization of compound liquid jets. Microparticles with both three-layer, double-layer and single-layer structures have been obtained. The results show that the TEFF technique has great benefits in fabricating multilayered microparticles at smaller scales. This method will be able to one-step encapsulate multiple therapeutic and imaging agents for biomedical applications such as multi-modal imaging, drug delivery and biomedicine.

  20. Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; OByrne, S.; Houwing, A. F. P.

    2001-01-01

    We investigate a new type of flow-tagging velocimetry technique for hypersonic flows. The technique involves exciting a thin line of nitric oxide molecules with a laser beam and then, after some delay, acquiring an image of the displaced line. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National Universities T2 free-piston shock tunnel. The velocity is measured with an uncertainty of approximately 2%. Comparison with a CFD simulation of the flow shows reasonable agreement.

  1. Magnetic and fluorescence-encoded polystyrene microparticles for cell separation

    NASA Astrophysics Data System (ADS)

    Bradbury, Diana; Anglin, Emily J.; Bailey, Sheree; Macardle, Peter J.; Fenech, Michael; Thissen, Helmut; Voelcker, Nicolas H.

    2008-12-01

    Materials assisting with the efforts of cell isolation are attractive for numerous biomedical applications including tissue engineering and cell therapy. Here, we have developed surface modification methods on microparticles for the purposes of advanced cell separation. Iron oxide nanoparticles were incorporated into 200 ım polystyrene microparticles for separation of particle-bound cells from non-bound cells in suspension by means of a permanent magnet. The polystyrene microparticles were further encoded with fluorescent quantum dots (QD) as identification tags to distinguish between specific microparticles in a mixture. Cluster of differentiation (CD) antibodies were displayed on the surface of the microparticles through direct adsorption and various methods of covalent attachment. In addition, a protein A coating was used to orientate the antibodies on the microparticle surface and to maximise accessibility of the antigen-binding sites. Microparticles which carried CD antibodies via covalent attachment showed greater cell attachment over those modifications that were only adsorbed to the surface through weak electrostatic interactions. Greatest extent of cell attachment was observed on microparticles modified with protein A - CD antibody conjugates. B and T lymphocytes were successfully isolated from a mixed population using two types of microparticles displaying B and T cell specific CD antibodies, respectively. Our approach will find application in preparative cell separation from tissue isolates and for microcarrier-based cell expansion.

  2. Collagen-coated microparticles in drug delivery.

    PubMed

    Sehgal, Praveen Kumar; Srinivasan, Aishwarya

    2009-07-01

    Advantages of drug-incorporated collagen particles have been described for the controlled delivery system for therapeutic actions. The attractiveness of collagen lies in its low immunogenicity and high biocompatibility. It is also recognized by the body as a natural constituent rather than a foreign body. Our research and development efforts are focused towards addressing some of the limitations of collagen, like the high viscosity of an aqueous phase, nondissolution in neutral pH buffers, thermal instability (denaturation) and biodegradability, to make it an ideal material for drug delivery with particular reference to microparticles. These limitations could be overcome by making collagen conjugates with other biomaterials or chemically modifying collagen monomer without affecting its triple helical conformation and maintaining its native properties. This article highlights collagen microparticles' present status as a carrier in drug delivery.

  3. Adsorption of monoclonal antibodies to glass microparticles.

    PubMed

    Hoehne, Matthew; Samuel, Fauna; Dong, Aichun; Wurth, Christine; Mahler, Hanns-Christian; Carpenter, John F; Randolph, Theodore W

    2011-01-01

    Microparticulate glass represents a potential contamination to protein formulations that may occur as a result of processing conditions or glass types. The effect of added microparticulate glass to formulations of three humanized antibodies was tested. Under the three formulation conditions tested, all three antibodies adsorbed irreversibly at near monolayer surface coverages to the glass microparticles. Analysis of the secondary structure of the adsorbed antibodies by infrared spectroscopy reveal only minor perturbations as a result of adsorption. Likewise, front-face fluorescence quenching measurements reflected minimal tertiary structural changes upon adsorption. In contrast to the minimal effects on protein structure, adsorption of protein to suspensions of glass microparticles induced significant colloidal destabilization and flocculation of the suspension.

  4. Therapeutic Strategies Based on Polymeric Microparticles

    PubMed Central

    Vilos, C.; Velasquez, L. A.

    2012-01-01

    The development of the field of materials science, the ability to perform multidisciplinary scientific work, and the need for novel administration technologies that maximize therapeutic effects and minimize adverse reactions to readily available drugs have led to the development of delivery systems based on microencapsulation, which has taken one step closer to the target of personalized medicine. Drug delivery systems based on polymeric microparticles are generating a strong impact on preclinical and clinical drug development and have reached a broad development in different fields supporting a critical role in the near future of medical practice. This paper presents the foundations of polymeric microparticles based on their formulation, mechanisms of drug release and some of their innovative therapeutic strategies to board multiple diseases. PMID:22665988

  5. Inertial Focusing of Microparticles in Curvilinear Microchannels

    NASA Astrophysics Data System (ADS)

    Özbey, Arzu; Karimzadehkhouei, Mehrdad; Akgönül, Sarp; Gozuacik, Devrim; Koşar, Ali

    2016-12-01

    A passive, continuous and size-dependent focusing technique enabled by “inertial microfluidics”, which takes advantage of hydrodynamic forces, is implemented in this study to focus microparticles. The objective is to analyse the decoupling effects of inertial forces and Dean drag forces on microparticles of different sizes in curvilinear microchannels with inner radius of 800 μm and curvature angle of 280°, which have not been considered in the literature related to inertial microfluidics. This fundamental approach gives insight into the underlying physics of particle dynamics and offers continuous, high-throughput, label-free and parallelizable size-based particle separation. Our design allows the same footprint to be occupied as straight channels, which makes parallelization possible with optical detection integration. This feature is also useful for ultrahigh-throughput applications such as flow cytometers with the advantages of reduced cost and size. The focusing behaviour of 20, 15 and 10 μm fluorescent polystyrene microparticles was examined for different channel Reynolds numbers. Lateral and vertical particle migrations and the equilibrium positions of these particles were investigated in detail, which may lead to the design of novel microfluidic devices with high efficiency and high throughput for particle separation, rapid detection and diagnosis of circulating tumour cells with reduced cost.

  6. Inertial Focusing of Microparticles in Curvilinear Microchannels

    PubMed Central

    Özbey, Arzu; Karimzadehkhouei, Mehrdad; Akgönül, Sarp; Gozuacik, Devrim; Koşar, Ali

    2016-01-01

    A passive, continuous and size-dependent focusing technique enabled by “inertial microfluidics”, which takes advantage of hydrodynamic forces, is implemented in this study to focus microparticles. The objective is to analyse the decoupling effects of inertial forces and Dean drag forces on microparticles of different sizes in curvilinear microchannels with inner radius of 800 μm and curvature angle of 280°, which have not been considered in the literature related to inertial microfluidics. This fundamental approach gives insight into the underlying physics of particle dynamics and offers continuous, high-throughput, label-free and parallelizable size-based particle separation. Our design allows the same footprint to be occupied as straight channels, which makes parallelization possible with optical detection integration. This feature is also useful for ultrahigh-throughput applications such as flow cytometers with the advantages of reduced cost and size. The focusing behaviour of 20, 15 and 10 μm fluorescent polystyrene microparticles was examined for different channel Reynolds numbers. Lateral and vertical particle migrations and the equilibrium positions of these particles were investigated in detail, which may lead to the design of novel microfluidic devices with high efficiency and high throughput for particle separation, rapid detection and diagnosis of circulating tumour cells with reduced cost. PMID:27991494

  7. Measuring the coefficient of restitution of high speed microparticle impacts using a PTV and CFD hybrid technique

    NASA Astrophysics Data System (ADS)

    Reagle, C. J.; Delimont, J. M.; Ng, W. F.; Ekkad, S. V.; Rajendran, V. P.

    2013-10-01

    A novel particle tracking velocimetry (PTV)/computational fluid dynamics (CFD) hybrid method for measuring coefficient of restitution (COR) has been developed which is relatively simple, cost-effective, and robust. A laser and camera system is used in the Virginia Tech Aerothermal Rig to measure velocity trajectories of microparticles. The method solves for particle impact velocity at the impact surface using a CFD solution and Lagrangian particle tracking. The methodology presented here attempts to characterize a difficult problem by a combination of established techniques, PTV and CFD, which have not been used in this capacity before. Erosion and deposition are functions of particle/wall interactions and COR is a fundamental property of these interactions. COR depends on impact velocity, angle of impact, temperature, particle composition, and wall material. Two sizes of Arizona road dust and one size of glass beads are impacted on to a 304 stainless steel coupon. The particles are entrained into a free jet of 27 m s-1 at room temperature. Impact angle was varied from 85° to 25° depending on particle. Mean results collected using this new technique compare favorably with trends established in literature. The utilization of this technique to measure COR of microparticle sand will help develop a computational model and serve as a baseline for further measurements at elevated air and wall temperatures. This is a revised and expanded version of a paper originally presented at the ASME conference Turbo Expo held in Copenhagen in June 2012.

  8. Comparison of Simultaneous PIV and Hydroxyl Tagging Velocimetry in Low Velocity Flows

    NASA Technical Reports Server (NTRS)

    Andre, Matthieu A.; Bardet, Philippe M.; Burns, Ross A.; Danehy, Paul M.

    2016-01-01

    Hydroxyl tagging velocimetry (HTV) is a molecular tagging velocimetry (MTV) technique that relies on the photo- dissociation of water vapor into OH radicals and their subsequent tracking using laser-induced fluorescence. At ambient temperature in air, the OH species lifetime is about 50 micro-s. The feasibility of using HTV for probing low- speed flows (a few m/s) is investigated by using an inert, heated gas as a means to increase the OH species lifetime. Unlike particle-based techniques, MTV does not suffer from tracer settling, which is particularly problematic at low speeds. Furthermore, the flow needs to be seeded with only a small mole fraction of water vapor, making it safer for both the user and facilities than other MTV techniques based on corrosive or toxic chemical tracers. HTV is demonstrated on a steam-seeded nitrogen jet at approximately 75 C in the laminar (Umean=3.31 m/s, Re=1,540), transitional (Umean=4.48 m/s, Re=2,039), and turbulent (Umean=6.91 m/s, Re=3,016) regimes at atmospheric pressure. The measured velocity profiles are compared with particle image velocimetry (PIV) measurements performed simultaneously with a second imager. Seeding for the PIV is achieved by introducing micron-sized water droplets into the flow with the steam; the same laser sheet is used for PIV and HTV to guarantee spatial and temporal overlap of the data. Optimizing each of these methods, however, requires conflicting operating conditions: higher temperatures benefit the HTV signals but reduce the available seed density for the PIV through evaporation. Nevertheless, data are found to agree within 10% for the instantaneous velocity profiles and within 5% for the mean profiles and demonstrate the feasibility of HTV for low-speed flows at moderate to high temperatures.

  9. Chemical release from single-PMMA microparticles monitored by CARS microscopy

    NASA Astrophysics Data System (ADS)

    Enejder, Annika; Svedberg, Fredrik; Nordstierna, Lars; Nydén, Magnus

    2011-03-01

    Microparticles loaded with antigens, proteins, DNA, fungicides, and other functional agents emerge as ideal vehicles for vaccine, drug delivery, genetic therapy, surface- and crop protection. The microscopic size of the particles and their collective large specific surface area enables highly active and localized release of the functional substance. In order to develop designs with release profiles optimized for the specific application, it is desirable to map the distribution of the active substance within the particle and how parameters such as size, material and morphology affect release rates at single particle level. Current imaging techniques are limited in resolution, sensitivity, image acquisition time, or sample treatment, excluding dynamic studies of active agents in microparticles. Here, we demonstrate that the combination of CARS and THG microscopy can successfully be used, by mapping the spatial distribution and release rates of the fungicide and food preservative IPBC from different designs of PMMA microparticles at single-particle level. By fitting a radial diffusion model to the experimental data, single particle diffusion coefficients can be determined. We show that release rates are highly dependent on the size and morphology of the particles. Hence, CARS and THG microscopy provides adequate sensitivity and spatial resolution for quantitative studies on how singleparticle properties affect the diffusion of active agents at microscopic level. This will aid the design of innovative microencapsulating systems for controlled release.

  10. Tracking an imploding cylinder with photonic Doppler velocimetry.

    PubMed

    Dolan, D H; Lemke, R W; McBride, R D; Martin, M R; Harding, E; Dalton, D G; Blue, B E; Walker, S S

    2013-05-01

    Cylindrical implosion offers a path to extreme material states, reaching considerably higher pressures than planar geometry. However, diagnosing compressed material in cylindrical geometry is challenging. Time-resolved velocimetry, a standard technique in planar compression, is difficult to incorporate into cylindrical experiments. This paper describes the use of photonic Doppler velocimetry (PDV) in magnetically driven cylindrical compression experiments at the Sandia Z machine. With this diagnostic, it is possible to track the interior of an imploding cylinder beyond 20 km/s. A "leapfrog" implementation is described to support velocities well above the bandwidth limits of standard PDV measurements.

  11. Nitric oxide regulates neutrophil migration through microparticle formation.

    PubMed

    Nolan, Sarah; Dixon, Rachel; Norman, Keith; Hellewell, Paul; Ridger, Victoria

    2008-01-01

    The role of nitric oxide (NO) in regulating neutrophil migration has been investigated. Human neutrophil migration to interleukin (IL)-8 (1 nmol/L) was measured after a 1-hour incubation using a 96-well chemotaxis plate assay. The NO synthase inhibitor N(G)-nitro-l-arginine methyl ester (L-NAME) significantly (P < 0.001) enhanced IL-8-induced migration by up to 45%. Anti-CD18 significantly (P < 0.001) inhibited both IL-8-induced and L-NAME enhanced migration. Antibodies to L-selectin or PSGL-1 had no effect on IL-8-induced migration but prevented the increased migration to IL-8 induced by L-NAME. L-NAME induced generation of neutrophil-derived microparticles that was significantly (P < 0.01) greater than untreated neutrophils or D-NAME. This microparticle formation was dependent on calpain activity and superoxide production. Only microparticles from L-NAME and not untreated or D-NAME-treated neutrophils induced a significant (P < 0.01) increase in IL-8-induced migration and transendothelial migration. Pretreatment of microparticles with antibodies to L-selectin (DREG-200) or PSGL-1 (PL-1) significantly (P < 0.001) inhibited this effect. The ability of L-NAME-induced microparticles to enhance migration was found to be dependent on the number of microparticles produced and not an increase in microparticle surface L-selectin or PSGL-1 expression. These data show that NO can modulate neutrophil migration by regulating microparticle formation.

  12. Cavitational Iron Microparticles Generation By Plasma Procedures For Medical Applications

    NASA Astrophysics Data System (ADS)

    Bica, Ioan; Bunoiu, Madalin; Chirigiu, Liviu; Spunei, Marius; Juganaru, Iulius

    2012-12-01

    The paper presents the experimental installation for the production, in argon plasma, of cavitational iron microparticles (pore microspheres, microtubes and octopus-shaped microparticles). Experimental results are presented and discussed and it is shown that absorbant particles with a minimum iron content are obtained by the plasma procedures

  13. Validation of Multi-plane Particle Shadow Velocimetry to Quantify Turbulence Scales

    NASA Astrophysics Data System (ADS)

    Truong, Christine; Hinkle, Steven; Sinding, Kyle; Harris, Jeff; Krane, Michael; Jefferies, Rhett

    2016-11-01

    Estimates of radial integral length scales using multi-plane Particle Shadow Velocimetry (PSV) are presented using measurements from the 11.2-inch diameter glycerin tunnel in the Applied Research Lab Garfield Thomas Water Tunnel. Particle shadow velocimetry (PSV) enables illumination of a volume and is an efficient means of obtaining multi-plane illumination. The combination of two colors in the LED backlight and a dichroic mirror makes possible the imaging of two planes in space. Thus, velocity fields in two imaging planes separated radially along the optical axis can be simultaneously measured. These multi-plane velocity fields are correlated over a range of separations to obtain integral length scales. Integral time scales are also calculated and converted into a streamwise length scale using Taylor's hypothesis for further confirmation. The inter-plane radial length scales, the in-plane length scales, the converted time scale in the inter-plane radial direction, and multi-plane turbulent statistics are compared with published studies, which used proven measurement methods. An additional, independent check is provided from PSV measurements in a single radial-axial plane.

  14. SURVEY OF OPTICAL VELOCIMETRY EXPERIMENTS - APPLICATIONS OF PDV, A HETERODYNE VELOCIMETER

    SciTech Connect

    HOLTKAMP, DAVID B.

    2007-02-12

    Optical velocimetry has been an important experimental diagnostic for many experiments. Recent improvements to heterodyne techniques have resulted in compact, inexpensive and high performance velocimetry measurement systems. We report on developments and improvements in this area and illustrate the performance of Photon Doppler Velocimetry (PDV) by showing several experimental examples.

  15. Solid lipid microparticles containing loratadine prepared using a Micromixer.

    PubMed

    Milak, Spomenka; Medlicott, Natalie; Tucker, Ian G

    2006-12-01

    Solid lipid microparticles were investigated as a taste-masking approach for a lipophilic weak base in a suspension. The idea was that the drug concentration in the aqueous phase of a suspension might be reduced by its partitioning into the solid lipid particles. Loratadine, as a model drug, was used to prepare Precirol ATO 5 microparticles by a Micromixer. The effects of three process variables: drug loading, PVA concentration and water/lipid ratio on the microparticle size, encapsulation efficiency, surface appearance, in-vitro release and drug partitioning in a suspension were studied. Loratadine release was slow in simulated saliva and very fast at the pH of stomach. In suspension of loratadine lipid microparticles, drug was released into the aqueous phase to the same concentration as in a drug suspension. Therefore, the usefulness of these microparticles for taste-masking in liquids is limited. However, they might be useful for taste-masking in solid dosage forms.

  16. Planar Particle Imaging and Doppler Velocimetry System and Method

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P. (Inventor)

    2003-01-01

    A planar velocity measurement system (100) is operative to measure all three velocity components of a flowing fluid (106) across an illuminated plane (108) using only a single line of sight. The fluid flow is seeded with small particles which accurately follow the flow field fluctuations. The seeded flow field is illuminated with pulsed laser light source (102) and the positions of the particles in the flow are recorded on CCD cameras (122,124). The in-plane velocities are measured by determining the in-plane particle displacements. The out-of-plane velocity component is determined by measuring the Doppler shift of the light scattered by the particles. Both gas and liquid velocities can be measured, as well as two-phase flows.

  17. Particle Image Velocimetry Study of Density Current Fronts

    ERIC Educational Resources Information Center

    Martin, Juan Ezequiel

    2009-01-01

    Gravity currents are flows that occur when a horizontal density difference causes fluid to move under the action of gravity; density currents are a particular case, for which the scalar causing the density difference is conserved. Flows with a strong effect of the horizontal density difference, even if only partially driven by it--such as the…

  18. Multiplexed photonic Doppler velocimetry for large channel count experiments

    NASA Astrophysics Data System (ADS)

    Daykin, Edward; Burk, Martin; Holtkamp, David; Miller, Edward Kirk; Rutkowski, Araceli; Strand, Oliver Ted; Pena, Michael; Perez, Carlos; Gallegos, Cenobio

    2017-01-01

    Photonic Doppler Velocimetry (PDV) is routinely employed as a means of measuring surface velocities for shockwave experimentation. Scientists typically collect ˜4 to 12 channels of PDV data and use extrapolation, assumptions, and models to determine the velocities in regions of the experiment that were not observed directly. We have designed, built and applied a new optical velocimetry diagnostic—the Multiplexed Photonic Doppler Velocimeter (MPDV)—for use on shock physics experiments that require a large number (100s) of spatial points to be measured. MPDV expands upon PDV measurement capabilities via frequency and time multiplexing using commercially available products developed for the telecommunications industry. The MPDV uses the heterodyne method to multiplex four data channels in the frequency domain combined with fiber delays to multiplex an additional four-channel dataset in the time domain, all of which are recorded onto the same digitizer input. This means that each digitizer input records data from eight separate spatial points, so that a single 4-input digitizer may record a total of 32 channels of data. Motivation for development of a multiplexed PDV was driven by requirements for an economical, high-fidelity, high channel-count optical velocimetry system. We present a survey of the methods, components, and trade-offs incorporated into this recent development in optical velocimetry.

  19. Detection of microparticles in dynamic processes

    NASA Astrophysics Data System (ADS)

    Ten, K. A.; Pruuel, E. R.; Kashkarov, A. O.; Rubtsov, I. A.; Shechtman, L. I.; Zhulanov, V. V.; Tolochko, B. P.; Rykovanov, G. N.; Muzyrya, A. K.; Smirnov, E. B.; Stolbikov, M. Yu; Prosvirnin, K. M.

    2016-11-01

    When a metal plate is subjected to a strong shock impact, its free surface emits a flow of particles of different sizes (shock-wave “dusting”). Traditionally, the process of dusting is investigated by the methods of pulsed x-ray or piezoelectric sensor or via an optical technique. The particle size ranges from a few microns to hundreds of microns. The flow is assumed to include also finer particles, which cannot be detected with the existing methods yet. On the accelerator complex VEPP-3-VEPP-4 at the BINP there are two experiment stations for research on fast processes, including explosion ones. The stations enable measurement of both passed radiation (absorption) and small-angle x-ray scattering on synchrotron radiation (SR). Radiation is detected with a precision high-speed detector DIMEX. The detector has an internal memory of 32 frames, which enables recording of the dynamics of the process (shooting of movies) with intervals of 250 ns to 2 μs. Flows of nano- and microparticles from free surfaces of various materials (copper and tin) have been examined. Microparticle flows were emitted from grooves of 50-200 μs in size and joints (gaps) between metal parts. With the soft x-ray spectrum of SR one can explore the dynamics of a single microjet of micron size. The dynamics of density distribution along micro jets were determined. Under a shock wave (∼ 60 GPa) acting on tin disks, flows of microparticles from a smooth surface were recorded.

  20. Experimental measurement of unsteady drag on shock accelerated micro-particles

    NASA Astrophysics Data System (ADS)

    Bordoloi, Ankur; Martinez, Adam; Prestridge, Katherine

    2016-11-01

    The unsteady drag history of shock accelerated micro-particles in air is investigated in the Horizontal Shock Tube (HST) facility at Los Alamos National laboratory. Drag forces are estimated based on particle size, particle density, and instantaneous velocity and acceleration measured on hundreds of post-shock particle tracks. We use previously implemented 8-frame Particle Tracking Velocimetry/Anemometry (PTVA) diagnostics to analyze particles in high spatiotemporal resolution from individual particle trajectories. We use a simultaneous LED based shadowgraph to register shock location with respect to a moving particle in each frame. To measure particle size accurately, we implement a Phase Doppler Particle Analyzer (PDPA) in synchronization with the PTVA. In this presentation, we will corroborate with more accuracy our earlier observation that post-shock unsteady drag coefficients (CD(t)) are manifold times higher than those predicted by theoretical models. Our results will also show that all CD(t) measurements collapse on a master-curve for a range of particle size, density, Mach number and Reynolds number when time is normalized by a shear velocity based time scale, t* = d/(uf-up) , where d is particle diameter, and uf and up are post-shock fluid and particle velocities.

  1. Analysis of tissue factor positive microparticles.

    PubMed

    Key, Nigel S

    2010-04-01

    There has recently been intense interest in the clinical measurement of tissue factor (TF)-positive microparticles (MPs) in clinical disease states. This interest has been driven by the demonstration of an putative role for circulating TF-positive MPs in animal models of thrombus propagation. Both immunological and functional assays for MP-TF have been described. While each approach has its own advantages and drawbacks, neither has yet been truly established as the 'gold standard'. Heterogeneity of TF-bearing MPs, such as the variable co-expression of surface phosphatidylserine, may determine not only their procoagulant potential, but also additional properties including rate of clearance from the circulation.

  2. Microparticle-enhanced Aspergillus ficuum phytase production and evaluation of fungal morphology in submerged fermentation.

    PubMed

    Coban, Hasan B; Demirci, Ali; Turhan, Irfan

    2015-06-01

    Phytase can be used in animal's diets to increase the absorption of several divalent ions, amino acids and proteins and to decrease the excessive phosphorus release in manure to prevent negative effects on the environment. This study aimed to enhance the current submerged fungal phytase productions with a novel fermentation technique by evaluating the effect of the various microparticles on Aspergillus ficuum phytase production. It was observed that microparticles prevented bulk fungal pellet growth, decreased average fungal pellet size and significantly increased phytase activity in the submerged fermentation. Microbial structure imaging results showed that the average fungal pellet radius decreased from 800 to 500 and 200 µm by addition of 15 g/L aluminum oxide and talcum, respectively, in shake-flask fermentation. Also, addition of 15 g/L of talcum and aluminum oxide increased phytase activity to 2.01 and 2.93 U/ml, respectively, compared to control (1.02 U/ml) in shake-flask fermentation. Additionally, phytase activity reached 6.49 U/ml within 96 h of fermentation with the addition of 15 g/L of talcum, whereas the maximum phytase activity was only 3.45 U/ml at 120 h of fermentation for the control in the 1-L working volume bioreactors. In conclusion, microparticles significantly increased fungal phytase activity and production yield compared to control fermentation.

  3. Microfluidic-based fabrication, characterization and magnetic functionalization of microparticles with novel internal anisotropic structure

    NASA Astrophysics Data System (ADS)

    Qiu, Yang; Wang, Fei; Liu, Ying-Mei; Wang, Wei; Chu, Liang-Yin; Wang, Hua-Lin

    2015-08-01

    Easy fabrication and independent control of the internal and external morphologies of core-shell microparticles still remain challenging. Core-shell microparticle comprised of a previously unknown internal anisotropic structure and a spherical shell was fabricated by microfluidic-based emulsificaiton and photopolymerization. The interfacial and spatial 3D morphology of the anisotropic structure were observed by SEM and micro-CT respectively. Meanwhile, a series of layer-by-layer scans of the anisotropic structure were obtained via the micro-CT, which enhanced the detail characterization and analysis of micro materials. The formation mechanism of the internal anisotropic structure may be attributed to solution-directed diffusion caused by the semipermeable membrane structure and chemical potential difference between inside and outside of the semipermeable membrane-like polymerized shell. The morphology evolution of the anisotropic structure was influenced and controlled by adjusting reaction parameters including polymerization degree, polymerization speed, and solute concentration difference. The potential applications of these microparticles in microrheological characterization and image enhancement were also proposed by embedding magnetic nanoparticles in the inner core.

  4. Microfluidic-based fabrication, characterization and magnetic functionalization of microparticles with novel internal anisotropic structure

    PubMed Central

    Qiu, Yang; Wang, Fei; Liu, Ying-Mei; Wang, Wei; Chu, Liang-Yin; Wang, Hua-Lin

    2015-01-01

    Easy fabrication and independent control of the internal and external morphologies of core-shell microparticles still remain challenging. Core-shell microparticle comprised of a previously unknown internal anisotropic structure and a spherical shell was fabricated by microfluidic-based emulsificaiton and photopolymerization. The interfacial and spatial 3D morphology of the anisotropic structure were observed by SEM and micro-CT respectively. Meanwhile, a series of layer-by-layer scans of the anisotropic structure were obtained via the micro-CT, which enhanced the detail characterization and analysis of micro materials. The formation mechanism of the internal anisotropic structure may be attributed to solution-directed diffusion caused by the semipermeable membrane structure and chemical potential difference between inside and outside of the semipermeable membrane-like polymerized shell. The morphology evolution of the anisotropic structure was influenced and controlled by adjusting reaction parameters including polymerization degree, polymerization speed, and solute concentration difference. The potential applications of these microparticles in microrheological characterization and image enhancement were also proposed by embedding magnetic nanoparticles in the inner core. PMID:26268148

  5. Mucosal deformation from an impinging transonic gas jet and the ballistic impact of microparticles

    NASA Astrophysics Data System (ADS)

    Hardy, M. P.; Kendall, M. A. F.

    2005-10-01

    By means of a transonic gas jet, gene guns ballistically deliver microparticle formulations of drugs and vaccines to the outer layers of the skin or mucosal tissue to induce unique physiological responses for the treatment of a range of conditions. Reported high-speed imaging experiments show that the mucosa deforms significantly while subjected to an impinging gas jet from a biolistic device. In this paper, the effect of this tissue surface deformation on microparticle impact conditions is simulated with computational fluid dynamics (CFD) calculations. The microparticles are idealized as spheres of diameters 26.1, 39 and 99 µm and a density of 1050 kg m-3. Deforming surface calculations of particle impact conditions are compared directly with an immobile surface case. The relative velocity and obliquity of the deforming surface decrease the normal component of particle impact velocity by up to 30% at the outer edge of the impinging gas jet. This is qualitatively consistent with reported particle penetration profiles in the tissue. It is recommended that these effects be considered in biolistic studies requiring quantified particle impact conditions.

  6. Persistence, distribution, and impact of distinctly segmented microparticles on cochlear health following in vivo infusion.

    PubMed

    Ross, Astin M; Rahmani, Sahar; Prieskorn, Diane M; Dishman, Acacia F; Miller, Josef M; Lahann, Joerg; Altschuler, Richard A

    2016-06-01

    Delivery of pharmaceuticals to the cochleae of patients with auditory dysfunction could potentially have many benefits from enhancing auditory nerve survival to protecting remaining sensory cells and their neuronal connections. Treatment would require platforms to enable drug delivery directly to the cochlea and increase the potential efficacy of intervention. Cochlear implant recipients are a specific patient subset that could benefit from local drug delivery as more candidates have residual hearing; and since residual hearing directly contributes to post-implantation hearing outcomes, it requires protection from implant insertion-induced trauma. This study assessed the feasibility of utilizing microparticles for drug delivery into cochlear fluids, testing persistence, distribution, biocompatibility, and drug release characteristics. To allow for delivery of multiple therapeutics, particles were composed of two distinct compartments; one containing polylactide-co-glycolide (PLGA), and one composed of acetal-modified dextran and PLGA. Following in vivo infusion, image analysis revealed microparticle persistence in the cochlea for at least 7 days post-infusion, primarily in the first and second turns. The majority of subjects maintained or had only slight elevation in auditory brainstem response thresholds at 7 days post-infusion compared to pre-infusion baselines. There was only minor to limited loss of cochlear hair cells and negligible immune response based on CD45+ immunolabling. When Piribedil-loaded microparticles were infused, Piribedil was detectable within the cochlear fluids at 7 days post-infusion. These results indicate that segmented microparticles are relatively inert, can persist, release their contents, and be functionally and biologically compatible with cochlear function and therefore are promising vehicles for cochlear drug delivery. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1510-1522, 2016.

  7. Quantitative NO{sub 2} molecular tagging velocimetry at 500 kHz frame rate

    SciTech Connect

    Jiang, Naibo; Nishihara, Munetake; Lempert, Walter R.

    2010-11-29

    NO{sub 2} molecular tagging velocimetry (MTV) is demonstrated at repetition rates as high as 500 kHz in a laboratory scale Mach 5 wind tunnel. A pulse burst laser and a home built optical parametric oscillator system were used to simultaneously generate the required 355 and 226 nm wavelengths for NO{sub 2} photodissociation (tagging) and NO planar laser induced fluorescence imaging (interrogation), respectively. NO{sub 2} MTV images were obtained both in front and behind the characteristic bow shock from a 5 mm diameter cylinder. From Gaussian curve fitting, an average free stream flow velocity of 719 m/s was obtained. Absolute statistical precision in velocity of {approx}11.5 m/s was determined, corresponding to relative precision of 1.6%-5%, depending upon the region of the flow probed.

  8. In vivo biocompatibility of the PLGA microparticles in parotid gland

    PubMed Central

    Cantín, Mario; Miranda, Patricio; Suazo Galdames, Iván; Zavando, Daniela; Arenas, Patricia; Velásquez, Luis; Vilos, Cristian

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) microparticles are used in various disorders for the controlled or sustained release of drugs, with the management of salivary gland pathologies possible using this technology. There is no record of the response to such microparticles in the glandular parenchyma. The purpose of this study was to assess the morphological changes in the parotid gland when injected with a single dose of PLGA microparticles. We used 12 adult female Sprague Dawley rats (Rattus norvegicus) that were injected into their right parotid gland with sterile vehicle solution (G1, n=4), 0.5 mg PLGA microparticles (G2, n=4), and 0.75 mg PLGA microparticles (G3, n=4); the microparticles were dissolved in a sterile vehicle solution. The intercalar and striated ducts lumen, the thickness of the acini and the histology aspect in terms of the parenchyma organization, cell morphology of acini and duct system, the presence of polymeric residues, and inflammatory response were determined at 14 days post-injection. The administration of the compound in a single dose modified some of the morphometric parameters of parenchyma (intercalar duct lumen and thickness of the glandular acini) but did not induce tissue inflammatory response, despite the visible presence of polymer waste. This suggests that PLGA microparticles are biocompatible with the parotid tissue, making it possible to use intraglandular controlled drug administration. PMID:24228103

  9. Shock wave driven microparticles for pharmaceutical applications

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Gojani, A.; Hosseini, S. H. R.

    2008-10-01

    Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously generates a shock wave that propagates through the foil and deforms it at a high speed. This high-speed foil deformation can project dry micro- particles deposited on the anterior surface of the foil at high speeds such that the particles have sufficient momentum to penetrate soft targets. We used this method of particle acceleration to develop a drug delivery device to deliver DNA/drug coated microparticles into soft human-body targets for pharmaceutical applications. The device physics has been studied by observing the process of particle acceleration using a high-speed video camera in a shadowgraph system. Though the initial rate of foil deformation is over 5 km/s, the observed particle velocities are in the range of 900-400 m/s over a distance of 1.5-10 mm from the launch pad. The device has been tested by delivering microparticles into liver tissues of experimental rats and artificial soft human-body targets, modeled using gelatin. The penetration depths observed in the experimental targets are quite encouraging to develop a future clinical therapeutic device for treatments such as gene therapy, treatment of cancer and tumor cells, epidermal and mucosal immunizations etc.

  10. Particle tracking velocimetry using echocardiographic data resolves flow in the left ventricle

    NASA Astrophysics Data System (ADS)

    Sampath, Kaushik; Abd, Thura T.; George, Richard T.; Katz, Joseph

    2015-11-01

    Two dimensional contrast echocardiography was performed on patients with a history of left ventricular (LV) thrombus. The 636 x 434 pixels electrocardiograms were recorded using a GE Vivid 9E system with (M5S-D and 4V-D) probes in a 2-D mode at a magnification of 0.3 mm/pix. The concentration of 2-4.5 micron seed bubbles was adjusted to obtain individually discernable traces, and a data acquisition rate of 60-90 fps kept the inter-frame displacements suitable for matching traces, and calculating vectors, but yet low enough to allow a scanning depth and width of upto 13 cm and 60 degrees respectively. Particle tracking velocimetry (PTV) guided by initial particle image velocimetry (PIV) was used to obtain the velocity distributions inside the LV with vector spacing of 3-5 mm. The data quality was greatly enhanced by implementing an iterative particle specific enhancement and tracking algorithm. Data covering 20 heart beats facilitated phase averaging. The results elucidated blood flow in the intra-ventricular septal region, lateral wall region, the apex of the LV and the mitral valve region.

  11. Ghost particle velocimetry: accurate 3D flow visualization using standard lab equipment.

    PubMed

    Buzzaccaro, Stefano; Secchi, Eleonora; Piazza, Roberto

    2013-07-26

    We describe and test a new approach to particle velocimetry, based on imaging and cross correlating the scattering speckle pattern generated on a near-field plane by flowing tracers with a size far below the diffraction limit, which allows reconstructing the velocity pattern in microfluidic channels without perturbing the flow. As a matter of fact, adding tracers is not even strictly required, provided that the sample displays sufficiently refractive-index fluctuations. For instance, phase separation in liquid mixtures in the presence of shear is suitable to be directly investigated by this "ghost particle velocimetry" technique, which just requires a microscope with standard lamp illumination equipped with a low-cost digital camera. As a further bonus, the peculiar spatial coherence properties of the illuminating source, which displays a finite longitudinal coherence length, allows for a 3D reconstruction of the profile with a resolution of few tenths of microns and makes the technique suitable to investigate turbid samples with negligible multiple scattering effects.

  12. Doppler picture velocimetry applied to hypersonics: automated DPV fringe pattern analysis using the FFT method

    NASA Astrophysics Data System (ADS)

    Pichler, Alexander; George, Alfred; Seiler, Friedrich; Srulijes, Julio; Sauerwein, Berthold

    2009-10-01

    Doppler picture velocimetry (DPV) is a tool for visualizing and measuring the flow velocity distribution of tracer particles in a laser light sheet. A frequency sensitive Michelson interferometer, tuned for detecting the velocity distribution by the Doppler effect, visualizes the velocity information of tracer particles crossing an illuminating laser light sheet as interference fringe patterns. Many efforts have been done to evaluate best these DPV patterns, in order to obtain the frequency distribution and, by applying the Doppler formula, the velocity profile of the tracers. The first processing method, developed in 1982, relied on manual processing of the pictures by the user, due to the unavailability of suitable high performance picture processing algorithms. This drawback made DPV being considered as a rather time-consuming measurement technique with limited accuracy, compared to existing commercial velocity measurement systems (e.g. PIV). This is no more the state of the art: The new DPV analysis software, presented in this paper, allows automated processing of the interference fringe samples obtained by two images, a reference picture without frequency shift and a Doppler picture containing the frequency shift, using single beam velocimetry. Based on Fast Fourier transformation (FFT), the presented algorithm determines the corresponding velocity profile (in pseudo colours) within only a few seconds on a standard personal computer without user intervention.

  13. Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; OByrne, Sean; Houwing, A. Frank P.; Fox, Jodie S.; Smith, Daniel R.

    2003-01-01

    We demonstrate a new variation of molecular-tagging velocimetry for hypersonic flows based on laser-induced fluorescence. A thin line of nitric-oxide molecules is excited with a laser beam and then, after a time delay, a fluorescence image of the displaced line is acquired. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National University s T2 free-piston shock tunnel. The single-shot velocity measurement uncertainty in the freestream was found to be 3.5%, based on 90% confidence. The method is also demonstrated in the separated flow region forward of a blunt fin attached to a flat plate in a Mach 7.4 flow produced by the Australian National University s T3 free-piston shock tunnel. The measurement uncertainty in the blunt fin experiment is approximately 30%, owing mainly to low fluorescence intensities, which could be improved significantly in future experiments. This velocimetry method is applicable to very high-speed flows that have low collisional quenching of the fluorescing species. It is particularly convenient in facilities where planar laser-induced fluorescence is already being performed.

  14. A method to analyze molecular tagging velocimetry data using the Hough transform.

    PubMed

    Sanchez-Gonzalez, R; McManamen, B; Bowersox, R D W; North, S W

    2015-10-01

    The development of a method to analyze molecular tagging velocimetry data based on the Hough transform is presented. This method, based on line fitting, parameterizes the grid lines "written" into a flowfield. Initial proof-of-principle illustration of this method was performed to obtain two-component velocity measurements in the wake of a cylinder in a Mach 4.6 flow, using a data set derived from computational fluid dynamics simulations. The Hough transform is attractive for molecular tagging velocimetry applications since it is capable of discriminating spurious features that can have a biasing effect in the fitting process. Assessment of the precision and accuracy of the method were also performed to show the dependence on analysis window size and signal-to-noise levels. The accuracy of this Hough transform-based method to quantify intersection displacements was determined to be comparable to cross-correlation methods. The employed line parameterization avoids the assumption of linearity in the vicinity of each intersection, which is important in the limit of drastic grid deformations resulting from large velocity gradients common in high-speed flow applications. This Hough transform method has the potential to enable the direct and spatially accurate measurement of local vorticity, which is important in applications involving turbulent flowfields. Finally, two-component velocity determinations using the Hough transform from experimentally obtained images are presented, demonstrating the feasibility of the proposed analysis method.

  15. Swellable Microparticles as Carriers for Sustained Pulmonary Drug Delivery

    PubMed Central

    EL-SHERBINY, IBRAHIM M.; MCGILL, SHAYNA; SMYTH, HUGH D.C.

    2012-01-01

    In this investigation, novel biodegradable physically crosslinked hydrogel micro-particles were developed and evaluated in vitro as potential carriers for sustained pulmonary drug delivery. To facilitate sustained release in the lungs, aerosols must first navigate past efficient aerodynamic filtering to penetrate to the deep lung (requires small particle size) where they must then avoid rapid macrophage clearance (enhanced by large particle size). The strategy suggested in this study to solve this problem is to deliver drug-loaded hydrogel microparticles with aerodynamic characteristics allowing them to be respirable when dry but attain large swollen sizes once deposited on moist lung surfaces to reduce macrophage uptake rates. The microparticles are based on PEG graft copolymerized onto chitosan in combination with Pluronic® F-108 and were prepared via cryomilling. The synthesized polymers used in preparation of the microparticles were characterized using FTIR, EA, 2D-XRD, and differential scanning calorimetry (DSC). The microparticles size, morphology, moisture content, and biodegradation rates were investigated. Swelling studies and in vitro drug release profiles were determined. An aerosolization study was conducted and macrophage uptake rates were evaluated against controls. The microparticles showed a respirable fraction of approximately 15% when prepared as dry powders. Enzymatic degradation of microparticles started within the first hour and about 7–41% weights were remaining after 240 h. Microparticles showed sustained release up to 10 and 20 days in the presence and absence of lysozyme, respectively. Preliminary macrophage interaction studies indicate that the developed hydrogel microparticles significantly delayed phagocytosis and may have the potential for sustained drug delivery to the lung. PMID:19967777

  16. Microfluidics assisted generation of innovative polysaccharide hydrogel microparticles.

    PubMed

    Marquis, M; Davy, J; Cathala, B; Fang, A; Renard, D

    2015-02-13

    Capillary flow-based approach such as microfluidic devices offer a number of advantages over conventional flow control technology because they ensure highly versatile geometry and can be used to produce monodisperse spherical and non-spherical polymeric microparticles. Based on the principle of a flow-focusing device to emulsify the coflow of aqueous solutions in an organic phase, we were able to produce the following innovative polysaccharide hydrogel microparticles: - Janus hydrogel microparticles made of pectin–pectin (homo Janus) and pectin–alginate (hetero Janus) were produced. The efficiency of separation of the two hemispheres was investigated by confocal scanning laser microscopy (CSLM) of previously labelled biopolymers. The Janus structure was confirmed by subjecting each microparticle hemisphere to specific enzymatic degradation. As a proof of concept, free BSA or BSA grafted with dextran, were encapsulated in each hemisphere of the hetero Janus hydrogel microparticles. While BSA, free or grafted with dextran, was always confined in the alginate hemisphere, a fraction of BSA diffused from the pectin to the alginate hemisphere. Methoxy groups along the pectin chain will be responsible of the decrease of the number of attractive electrostatic interactions occurring between amino groups of BSA and carboxylic groups of pectin. - Pectin hydrogel microparticles of complex shapes were successfully produced by combining on-chip the phenomenon of gelation and water diffusion induced self-assembly, using dimethyl carbonate as continuous phase, or by deformation of the pre-gelled droplets off-chip at a fluid–fluid interface. Sphere, oblate ellipsoid, torus or mushroom-type morphologies were thus obtained. Moreover, it was established that after crossing the interface during their collect, mushroom-type microparticles did not migrate in the calcium or DMC phase but stayed at the liquid–liquid interface. These new and original hydrogel microparticles will

  17. Thermal and fractal analysis of diclofenac/Gelucire 50/13 microparticles obtained by ultrasound-assisted atomization.

    PubMed

    Cavallari, Cristina; Rodriguez, Lorenzo; Albertini, Beatrice; Passerini, Nadia; Rosetti, Francesca; Fini, Adamo

    2005-05-01

    The study describes the application of a spray-congealing technique, using a new ultrasound-assisted atomizer to prepare microparticles of diclofenac/Gelucire 50/13, with the aim to obtain a formulation of enhanced-release, at 10% w/w drug-to-excipient ratio, without any employ of solvent. Scanning electron microscopy showed that it was possible to obtain almost spherically shaped and non-aggregated microparticles; with good encapsulation efficiency (90% in most size fraction) and with a prevalent particle size in the range 150-350 mum. Image analysis results by SEM and the high fractal dimension value suggested that most particles have actually an ellipsoidal shape and a rather rough contour. Hot stage microscopy, differential scanning calorimetry, and X-ray powder diffractometry analysis were carried out to evaluate the nature of the solid state and the thermal behavior of the microparticles thus prepared. The in vitro tests displayed a significant increase of the diclofenac dissolution rate from ultrasound microparticles, compared with pure drug and with drug/Gelucire 50/13 physical mixtures.

  18. Chitosan microparticles as injectable scaffolds for tissue engineering.

    PubMed

    Cruz, Dunia Mercedes García; Ivirico, Jorge Luis Escobar; Gomes, Manuela M; Ribelles, Jose Luis Gómez; Sánchez, Manuel Salmerón; Reis, Rui L; Mano, João F

    2008-08-01

    The use of chitosan microparticles as injectable carriers for cell transplantation represents a promising alternative to avoid the drawbacks of the implantation of other forms of three-dimensional (3D) scaffolds seeded with cells. In this study, a 3D construct is obtained in vitro by combining chitosan microparticles crosslinked with genipin and goat bone marrow stromal cells (GBMCs). Cell viability and the morphology of GBMCs were evaluated after culture for 7 and 14 days. Our results show the feasibility of chitosan microparticles as potential injectable scaffolds for tissue engineering and regenerative medicine.

  19. Optical beam deflection signal from a single microparticle

    NASA Astrophysics Data System (ADS)

    Wu, Jiaqi; Kitamori, Takehiko; Sawada, Tsuguo

    1990-07-01

    The optical beam deflection (OBD) method was applied to the measurement of a single microparticle, and the signal from one resin microparticle of 200-600 μm in diameter could be detected. Based on the frequency characteristics and size dependence of the OBD signal, this method was found to be more sensitive for a smaller particle, and more effective than the photoacoustic method. Theoretical considerations showed that these characteristics were attributable to the enhancement of the temperature field gradient due to the curvature of the microparticle.

  20. Holocinematographic velocimetry - Resolution limitation for flow measurement

    NASA Astrophysics Data System (ADS)

    Liburdy, James A.

    1987-10-01

    The goal of developing a holocinematographic velocimeter (HCV) is to provide a technique to study the evolution of instantaneous three-dimensional velocity profiles in turbulent flow fields. The method tracks individual seed particles that have been introduced into the flow. An imaging system using far-field holography is used to provide a full field of view tracking. Velocity information is determined from measured particle displacements of sequential hologram reconstruction. This study examines the resolution limits of far-field holography as applied to the HCV. The results aid in the determination of required seeding concentrations, establish the ability to resolve particle centers, and illustrate the use of a dual TV camera system to aid resolution. A straightforward enhancement technique provides a means to eliminate noise and reduce out of image plane ambiguity.

  1. Expanding imaging capabilities for microfluidics: applicability of darkfield internal reflection illumination (DIRI) to observations in microfluidics.

    PubMed

    Kawano, Yoshihiro; Otsuka, Chino; Sanzo, James; Higgins, Christopher; Nirei, Tatsuo; Schilling, Tobias; Ishikawa, Takuji

    2015-01-01

    Microfluidics is used increasingly for engineering and biomedical applications due to recent advances in microfabrication technologies. Visualization of bubbles, tracer particles, and cells in a microfluidic device is important for designing a device and analyzing results. However, with conventional methods, it is difficult to observe the channel geometry and such particles simultaneously. To overcome this limitation, we developed a Darkfield Internal Reflection Illumination (DIRI) system that improved the drawbacks of a conventional darkfield illuminator. This study was performed to investigate its utility in the field of microfluidics. The results showed that the developed system could clearly visualize both microbubbles and the channel wall by utilizing brightfield and DIRI illumination simultaneously. The methodology is useful not only for static phenomena, such as clogging, but also for dynamic phenomena, such as the detection of bubbles flowing in a channel. The system was also applied to simultaneous fluorescence and DIRI imaging. Fluorescent tracer beads and channel walls were observed clearly, which may be an advantage for future microparticle image velocimetry (μPIV) analysis, especially near a wall. Two types of cell stained with different colors, and the channel wall, can be recognized using the combined confocal and DIRI system. Whole-slide imaging was also conducted successfully using this system. The tiling function significantly expands the observing area of microfluidics. The developed system will be useful for a wide variety of engineering and biomedical applications for the growing field of microfluidics.

  2. Detection and quantification of microparticles from different cellular lineages using flow cytometry. Evaluation of the impact of secreted phospholipase A2 on microparticle assessment.

    PubMed

    Rousseau, Matthieu; Belleannee, Clemence; Duchez, Anne-Claire; Cloutier, Nathalie; Levesque, Tania; Jacques, Frederic; Perron, Jean; Nigrovic, Peter A; Dieude, Melanie; Hebert, Marie-Josee; Gelb, Michael H; Boilard, Eric

    2015-01-01

    Microparticles, also called microvesicles, are submicron extracellular vesicles produced by plasma membrane budding and shedding recognized as key actors in numerous physio(patho)logical processes. Since they can be released by virtually any cell lineages and are retrieved in biological fluids, microparticles appear as potent biomarkers. However, the small dimensions of microparticles and soluble factors present in body fluids can considerably impede their quantification. Here, flow cytometry with improved methodology for microparticle resolution was used to detect microparticles of human and mouse species generated from platelets, red blood cells, endothelial cells, apoptotic thymocytes and cells from the male reproductive tract. A family of soluble proteins, the secreted phospholipases A2 (sPLA2), comprises enzymes concomitantly expressed with microparticles in biological fluids and that catalyze the hydrolysis of membrane phospholipids. As sPLA2 can hydrolyze phosphatidylserine, a phospholipid frequently used to assess microparticles, and might even clear microparticles, we further considered the impact of relevant sPLA2 enzymes, sPLA2 group IIA, V and X, on microparticle quantification. We observed that if enriched in fluids, certain sPLA2 enzymes impair the quantification of microparticles depending on the species studied, the source of microparticles and the means of detection employed (surface phosphatidylserine or protein antigen detection). This study provides analytical considerations for appropriate interpretation of microparticle cytofluorometric measurements in biological samples containing sPLA2 enzymes.

  3. Detection and Quantification of Microparticles from Different Cellular Lineages Using Flow Cytometry. Evaluation of the Impact of Secreted Phospholipase A2 on Microparticle Assessment

    PubMed Central

    Rousseau, Matthieu; Belleannee, Clemence; Duchez, Anne-Claire; Cloutier, Nathalie; Levesque, Tania; Jacques, Frederic; Perron, Jean; Nigrovic, Peter A.; Dieude, Melanie; Hebert, Marie-Josee; Gelb, Michael H.; Boilard, Eric

    2015-01-01

    Microparticles, also called microvesicles, are submicron extracellular vesicles produced by plasma membrane budding and shedding recognized as key actors in numerous physio(patho)logical processes. Since they can be released by virtually any cell lineages and are retrieved in biological fluids, microparticles appear as potent biomarkers. However, the small dimensions of microparticles and soluble factors present in body fluids can considerably impede their quantification. Here, flow cytometry with improved methodology for microparticle resolution was used to detect microparticles of human and mouse species generated from platelets, red blood cells, endothelial cells, apoptotic thymocytes and cells from the male reproductive tract. A family of soluble proteins, the secreted phospholipases A2 (sPLA2), comprises enzymes concomitantly expressed with microparticles in biological fluids and that catalyze the hydrolysis of membrane phospholipids. As sPLA2 can hydrolyze phosphatidylserine, a phospholipid frequently used to assess microparticles, and might even clear microparticles, we further considered the impact of relevant sPLA2 enzymes, sPLA2 group IIA, V and X, on microparticle quantification. We observed that if enriched in fluids, certain sPLA2 enzymes impair the quantification of microparticles depending on the species studied, the source of microparticles and the means of detection employed (surface phosphatidylserine or protein antigen detection). This study provides analytical considerations for appropriate interpretation of microparticle cytofluorometric measurements in biological samples containing sPLA2 enzymes. PMID:25587983

  4. Bottle beam based optical trapping system for three-dimensional trapping of high and low index microparticles

    NASA Astrophysics Data System (ADS)

    Ahluwalia, Balpreet Singh; Yuan, Xiaocong; Tao, Shaohua

    2005-08-01

    The quest for applying optical tweezers system for novel applications has aggrandized its trapping capabilities since its inception. Researchers have proposed and applied light based micro-manipulation technique in the field of colloidal sciences, bioscience, MEMS and the count is limitless. In this paper we report the self-imaged optical bottle beam based optical tweezers system. A self-imaged bottle beam possesses three-dimensional intensity-null points along the propagation axis. The transverse intensity profile of the self-imaged bottle beam oscillates along the propagation axis, hence providing three-dimensional trapping potential for high and low indices microparticles at constructive and destructive interference points, respectively. Bottle beam based optical tweezer system adds the beneficial property of Gaussian and Bessel beam based trapping systems by providing three-dimensional trapping potential and self-reconstruction ability, respectively. As self-imaged bottle beam belong to the family of propagation-invariant beams, it can be used to trap chain of high and low indices microparticles three-dimensionally along the propagation directions, which can be used to periodically stack microparticles (of different refractive index) longitudinally.

  5. Externally Dispersed Interferometry for Resolution Boosting and Doppler Velocimetry

    SciTech Connect

    Erskine, D J

    2003-12-01

    Externally dispersed interferometry (EDI) is a rapidly advancing technique for wide bandwidth spectroscopy and radial velocimetry. By placing a small angle-independent interferometer near the slit of an existing spectrograph system, periodic fiducials are embedded on the recorded spectrum. The multiplication of the stellar spectrum times the sinusoidal fiducial net creates a moire pattern, which manifests high detailed spectral information heterodyned down to low spatial frequencies. The latter can more accurately survive the blurring, distortions and CCD Nyquist limitations of the spectrograph. Hence lower resolution spectrographs can be used to perform high resolution spectroscopy and radial velocimetry (under a Doppler shift the entire moir{acute e} pattern shifts in phase). A demonstration of {approx}2x resolution boosting (100,000 from 50,000) on the Lick Obs. echelle spectrograph is shown. Preliminary data indicating {approx}8x resolution boost (170,000 from 20,000) using multiple delays has been taken on a linear grating spectrograph.

  6. Polymer-grafted starch microparticles for oral and nasal immunization.

    PubMed

    McDermott, M R; Heritage, P L; Bartzoka, V; Brook, M A

    1998-06-01

    Microparticle delivery systems for oral vaccine administration are receiving considerable attention. A novel silicone polymer-grafted starch microparticle system was developed that is efficacious both orally and intranasally. Unlike most other microparticle systems, this novel system does not appear to retard the release of antigen or to protect antigen from degradation. The results indicate that a unique physiochemical relationship occurs between protein antigen and silicone in a starch matrix that facilitates the mucosal immunogenicity of antigen. This leads to predominance of Th2 antibody response. Taken together, these findings indicate that this novel microparticle system may be advantageous for the delivery of small quantities of antigen, especially intranasally, and may be useful for the induction of oral tolerance.

  7. Microfabrication of encoded microparticle array for multiplexed DNA hybridization detection.

    PubMed

    Zhi, Zheng-Liang; Morita, Yasutaka; Yamamura, Shouhei; Tamiya, Eiichi

    2005-05-21

    A strategy for the high-sensitivity, high-selectivity, and multiplexed detection of oligonucleotide hybridizations has been developed with an encoded Ni microparticle random array that was manufactured by a "top-down" approach using micromachining and microfabrication techniques.

  8. Enhancement of laminar convective heat transfer using microparticle suspensions

    NASA Astrophysics Data System (ADS)

    Zhu, Jiu Yang; Tang, Shiyang; Yi, Pyshar; Baum, Thomas; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2017-01-01

    This paper investigates the enhancement of convective heat transfer within a sub-millimetre diameter copper tube using Al2O3, Co3O4 and CuO microparticle suspensions. Experiments are conducted at different particle concentrations of 1.0, 2.0 and 5.0 wt% and at various flow rates ranging from 250 to 1000 µl/min. Both experimental measurements and numerical analyses are employed to obtain the convective heat transfer coefficient. The results indicate a significant enhancement in convective heat transfer coefficient due to the implementation of microparticle suspensions. For the case of Al2O3 microparticle suspension with 5.0 wt% concentration, a 20.3 % enhancement in convective heat transfer coefficient is obtained over deionised water. This is comparable to the case of Al2O3 nanofluid at the same concentration. Hence, there is a potential for the microparticle suspensions to be used for cooling of compact integrated systems.

  9. Photonic nanojet shaping of dielectric non-spherical microparticles

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Yang

    2014-11-01

    The photonic nanojet shaping effect in the dielectric non-spherical microparticles is reported. The specific spatial electromagnetic field is studied by using finite-difference time-domain calculation which constitutes the so-called photonic nanojet. The dielectric non-spherical microparticle is truncated by the cutting thickness. The latitudinal and longitudinal dimensions of the photonic nanojet and its peak intensity depending on the variation of cutting thickness are numerically researched. The shape dependence of the photonic nanojet in the non-spherical microparticles has been investigated by quality criterion. The practical results are drawn concerning the possible procedures to gain the control over the properties of photonic nanojet in the non-spherical microparticles. The shaping mechanism has a significant impact on the use of photonic nanojet to distinguish nanoscale specimens.

  10. Effect of surface temperature on microparticle-surface adhesion

    NASA Astrophysics Data System (ADS)

    Vallabh, Chaitanya Krishna Prasad; Stephens, James D.; Cetinkaya, Cetin

    2015-07-01

    The effect of surface temperature on the adhesion properties of the bond between a substrate and a single micro-particle is investigated in a non-contact/non-invasive manner by monitoring the rolling/rocking motion dynamics of acoustically excited single microparticles. In the current work, a set of experiments were performed to observe the change in the rocking resonance frequency of the particles with the change of surface temperature. At various substrate surface temperature levels, the work-of-adhesion values of the surface-particle bond are evaluated from the resonance frequencies of the rocking motion of a set of microparticles driven by an orthogonal ultrasonic surface acoustic wave field. The dependence of adhesion bonds of a microparticle and the substrate on the surface temperature has been clearly demonstrated by the performed experiments. It was also observed and noted that the relative humidity plays a vital role in the rolling behavior of particles.

  11. Investigation of Surface Preparations to Enhance Photon Doppler Velocimetry Measurements

    DTIC Science & Technology

    2015-08-01

    SUPPLEMENTARY NOTES 14. ABSTRACT The work described in this report compiles empirical measurements of the intensity of 1.55-μm light reflected from...for conducting Photon Doppler Velocimetry measurements, which necessitates a prediction of the intensity of Doppler shifted light that will be...reflected from a surface to optimize the measurement. It was found that the intensity of reflected light could be sufficiently explained using the law of

  12. Flow Tagging Velocimetry Using Caged Dye Photo-Activated Fluorophores

    DTIC Science & Technology

    2000-01-01

    Meas. Sci. Technol. 11 (2000) 1251–1258. Printed in the UK PII: S0957-0233(00)10968-3 Flow tagging velocimetry using caged dye photo-activated...followed by laser induced electronic fluo- rescence, has been applied both to low speed turbulent air jets (Noullez et al 1997) and to supersonic flow...measurements in electrohydrodynamic flows with mean velocities of order 2–4 µm s−1. There are, however, some significant disadvantages associated with

  13. Laser Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field

    DTIC Science & Technology

    1991-06-01

    Velocimetry Measurements of Oscillating Airfoil Dynamic Stall Flow Field By M.S.Chandrasekharal Navy-NASA Joint Institute of Aeronautics and Fluid Mechanics ...tunnel of the Fluid Mechanics Laboratory(FML) angle information. The other could be used for the at NASA Ames Research Center (ARC). It is one of...were on throat is always kept choked so that no disturbances a different traverse mechanism , but this was driven as can propagate upstream into the

  14. Identification and Minimization of Errors in Doppler Global Velocimetry Measurements

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.

    2000-01-01

    A systematic laboratory investigation was conducted to identify potential measurement error sources in Doppler Global Velocimetry technology. Once identified, methods were developed to eliminate or at least minimize the effects of these errors. The areas considered included the Iodine vapor cell, optical alignment, scattered light characteristics, noise sources, and the laser. Upon completion the demonstrated measurement uncertainty was reduced to 0.5 m/sec.

  15. Design of a 3D Digital Liquid Crystal Particle Thermometry and Velocimetry (3DDLCPT/V) System

    NASA Astrophysics Data System (ADS)

    Grothe, Rob; Rixon, Greg; Dabiri, Dana

    2007-11-01

    A novel 3D Digital Liquid Crystal Particle Thermometry and Velocimetry (3DDLCPT/V) system has been designed and fabricated. By combining 3D Defocusing Particle Image Velocimetry (3DDPIV) and Digital Particle Image Thermometry (DPIT) into one system, this technique provides simultaneous temperature and velocity data using temperature-sensitive liquid crystal particles (LCP) as flow sensors. A custom water-filled prism corrects for astigmatism caused by off-axis imaging. New optics equations are derived to account for multi-surface refractions. This redesign also maximizes the use of the CCD area to more efficiently image the volume of interest. Six CCD cameras comprise the imaging system, with three allocated for velocity measurements and three for temperature measurements. The cameras are optically aligned to sub-pixel accuracy using a precision grid and high-resolution translation stages. Two high-intensity custom-designed xenon flashlamps provide illumination. Temperature calibration of the LCP is then performed. These results and proof-of-concept experiments will be discussed in detail.

  16. Multiplexed Photonic Doppler Velocimetry for Large Channel Count Experiments

    NASA Astrophysics Data System (ADS)

    Daykin, Edward; Burk, Martin; Gallegos, Cenobio; Pena, Michael; Perez, Carlos; Rutkowski, Araceli; Strand, Oliver; Holtkamp, David

    2015-06-01

    The Photonic Doppler Velocimeter (PDV) is routinely employed as a means of measuring surface velocities for shockwave experimentation. Scientists typically collect ~ 4 to 12 channels of PDV data and use extrapolation, assumptions and models to determine the velocities in regions of the experiment that were not observed directly. We have designed, built and applied a new optical velocimetry diagnostic - the Multiplexed Photonic Doppler Velocimeter (MPDV) - for use on shock physics experiments that requires a large number (~ 100) of spatial points to be measured. MPDV expands upon PDV measurement capabilities via frequency and time multiplexing. The MPDV is built using commercially available products. The MPDV uses the heterodyne method to multiplex four data channels in the frequency domain combined with fiber delays to multiplex an additional four channel data set in the time domain, all of which are recorded onto the same digitizer input. This means that each digitizer input records data from eight separate spatial points, so that a single 4-input digitizer may record a total of 32 channels of data. Motivation for development of a multiplexed PDV was driven by requirements for an economical, high channel count optical velocimetry system. We will present a survey of methods, components and trade-offs incorporated into this recent development in optical velocimetry.

  17. Iodine Tagging Velocimetry in a Mach 10 Wake

    NASA Technical Reports Server (NTRS)

    Balla, Robert Jeffrey

    2013-01-01

    A variation on molecular tagging velocimetry (MTV) [1] designated iodine tagging velocimetry (ITV) is demonstrated. Molecular iodine is tagged by two-photon absorption using an Argon Fluoride (ArF) excimer laser. A single camera measures fluid displacement using atomic iodine emission at 206 nm. Two examples ofMTVfor cold-flowmeasurements areN2OMTV [2] and Femtosecond Laser Electronic Excitation Tagging [3]. These, like most MTV methods, are designed for atmospheric pressure applications. Neither can be implemented at the low pressures (0.1- 1 Torr) in typical hypersonic wakes. Of all the single-laser/singlecamera MTV approaches, only Nitric-Oxide Planar Laser Induced Fluorescence-based MTV [4] has been successfully demonstrated in a Mach 10 wake. Oxygen quenching limits transit times to 500 ns and accuracy to typically 30%. The present note describes the photophysics of the ITV method. Off-body velocimetry along a line is demonstrated in the aerothermodynamically important and experimentally challenging region of a hypersonic low-pressure near-wake in a Mach 10 air wind tunnel. Transit times up to 10 µs are demonstrated with conservative errors of 10%.

  18. Laser velocimetry measurements in non-isothermal CVD systems

    NASA Technical Reports Server (NTRS)

    Johnson, E. J.; Hyer, P. V.; Culotta, P. W.; Clark, I. O.

    1991-01-01

    Researchers at the NASA Langley Research Center are applying laser velocimetry (LV) techniques to characterize the fluid dynamics of non-isothermal flows inside fused silica chambers designed for chemical vapor deposition (CVD). Experimental issues involved in the application of LV techniques to this task include thermophoretic effects on the LV seed particles, seeding the hazardous gases, index of refraction gradients in the flow field and surrounding media, optical access, relatively low flow velocities, and analysis and presentation of sparse data. An overview of the practical difficulties these issues represent to the use of laser velocimetry instrumentation for CVD applications is given. A fundamental limitation on the application of LV techniques in non-isothermal systems is addressed which involves a measurement bias due to the presence of thermal gradients. This bias results from thermophoretic effects which cause seed particle trajectories to deviate from gas streamlines. Data from a research CVD reactor are presented which indicate that current models for the interaction of forces such as Stokes drag, inertia, gravity, and thermophoresis are not adequate to predict thermophoretic effects on particle-based velocimetry measurements in arbitrary flow configurations.

  19. The picobalance for single microparticle measurements

    NASA Astrophysics Data System (ADS)

    Davis, E. James

    The picobalance or quadrupole levitator is an outgrowth of the classical Millikan oil drop experiment and has been used for a wide variety of studies of micron and submicron size particles and droplets. A new version of the picobalance, which uses automatic feedback control for particle suspension and a linear photodiode array for light-scattering measurements, is described. The instrument has been used to measure the aerodynamic drag on microparticles suspended in a flow field and to measure evaporation rates and optical properties of liquid droplets. The instrument can also be used to examine spectroscopically the optical and chemical properties of atmospheric and interplanetary particles and any number of phoretic forces on such particles.

  20. Numerical Simulations of the Digital Microfluidic Manipulation of Single Microparticles.

    PubMed

    Lan, Chuanjin; Pal, Souvik; Li, Zhen; Ma, Yanbao

    2015-09-08

    Single-cell analysis techniques have been developed as a valuable bioanalytical tool for elucidating cellular heterogeneity at genomic, proteomic, and cellular levels. Cell manipulation is an indispensable process for single-cell analysis. Digital microfluidics (DMF) is an important platform for conducting cell manipulation and single-cell analysis in a high-throughput fashion. However, the manipulation of single cells in DMF has not been quantitatively studied so far. In this article, we investigate the interaction of a single microparticle with a liquid droplet on a flat substrate using numerical simulations. The droplet is driven by capillary force generated from the wettability gradient of the substrate. Considering the Brownian motion of microparticles, we utilize many-body dissipative particle dynamics (MDPD), an off-lattice mesoscopic simulation technique, in this numerical study. The manipulation processes (including pickup, transport, and drop-off) of a single microparticle with a liquid droplet are simulated. Parametric studies are conducted to investigate the effects on the manipulation processes from the droplet size, wettability gradient, wetting properties of the microparticle, and particle-substrate friction coefficients. The numerical results show that the pickup, transport, and drop-off processes can be precisely controlled by these parameters. On the basis of the numerical results, a trap-free delivery of a hydrophobic microparticle to a destination on the substrate is demonstrated in the numerical simulations. The numerical results not only provide a fundamental understanding of interactions among the microparticle, the droplet, and the substrate but also demonstrate a new technique for the trap-free immobilization of single hydrophobic microparticles in the DMF design. Finally, our numerical method also provides a powerful design and optimization tool for the manipulation of microparticles in DMF systems.

  1. Electrodeposition of microparticles on polarized ion exchange membranes

    SciTech Connect

    Verbich, S.V.; Ponomarev, M.I.; Grebenyuk, V.D.; Dukhin, S.S.

    1986-11-01

    The use of ion exchange membranes to extract microparticles from an aqueous solution is considered. The efficiency of removing negatively charged aerosil particles depends substantially on the nature of the membrane located at the anode. It has been established that besides an increase in the electric field intensity the principal factor ensuring an increase in the efficiency of purifying a solution by electrodeposition of microparticles on a membrane surface is a reduction in the flowrate relative to the membrane surface.

  2. Detection and Monitoring of Microparticles Under Skin by Optical Coherence Tomography as an Approach to Continuous Glucose Sensing Using Implanted Retroreflectors

    PubMed Central

    Wang, Shang; Sherlock, Tim; Salazar, Betsy; Sudheendran, Narendran; Manapuram, Ravi Kiran; Kourentzi, Katerina; Ruchhoeft, Paul; Willson, Richard C.; Larin, Kirill V.

    2015-01-01

    We demonstrate the feasibility of using optical coherence tomography (OCT) to image and detect 2.8 μm diameter microparticles (stationary and moving) on a highly-reflective gold surface both in clear media and under skin in vitro. The OCT intensity signal can clearly report the microparticle count, and the OCT response to the number of microparticles shows a good linearity. The detect ability of the intensity change (2.9% ± 0.5%) caused by an individual microparticle shows the high sensitivity of monitoring multiple particles using OCT. An optical sensing method based on this feasibility study is described for continuously measuring blood sugar levels in the subcutaneous tissue, and a molecular recognition unit is designed using competitive binding to modulate the number of bound microparticles as a function of glucose concentration. With further development, an ultra-small, implantable sensor might provide high specificity and sensitivity for long-term continuous monitoring of blood glucose concentration. PMID:26413034

  3. Controlled Lateral Positioning of Microparticles Inside Droplets Using Acoustophoresis.

    PubMed

    Fornell, Anna; Nilsson, Johan; Jonsson, Linus; Periyannan Rajeswari, Prem Kumar; Joensson, Haakan N; Tenje, Maria

    2015-10-20

    In this paper, we utilize bulk acoustic waves to control the position of microparticles inside droplets in two-phase microfluidic systems and demonstrate a method to enrich the microparticles. In droplet microfluidics, different unit operations are combined and integrated on-chip to miniaturize complex biochemical assays. We present a droplet unit operation capable of controlling the position of microparticles during a trident shaped droplet split. An acoustic standing wave field is generated in the microchannel, and the acoustic forces direct the encapsulated microparticles to the center of the droplets. The method is generic, requires no labeling of the microparticles, and is operated in a noncontact fashion. It was possible to achieve 2+-fold enrichment of polystyrene beads (5 μm in diameter) in the center daughter droplet with an average recovery of 89% of the beads. Red blood cells were also successfully manipulated inside droplets. These results show the possibility to use acoustophoresis in two-phase systems to enrich microparticles and open up the possibility for new droplet-based assays that are not performed today.

  4. Combined AC electroosmosis and dielectrophoresis for controlled rotation of microparticles

    PubMed Central

    Walid Rezanoor, Md.; Dutta, Prashanta

    2016-01-01

    Electrorotation is widely used for characterization of biological cells and materials using a rotating electric field. Generally, multiphase AC electric fields and quadrupolar electrode configuration are needed to create a rotating electric field for electrorotation. In this study, we demonstrate a simple method to rotate dielectrophoretically trapped microparticles using a stationary AC electric field. Coplanar interdigitated electrodes are used to create a linearly polarized nonuniform AC electric field. This nonuniform electric field is employed for dielectrophoretic trapping of microparticles as well as for generating electroosmotic flow in the vicinity of the electrodes resulting in rotation of microparticles in a microfluidic device. The rotation of barium titanate microparticles is observed in 2-propanol and methanol solvent at a frequency below 1 kHz. A particle rotation rate as high as 240 revolutions per minute is observed. It is demonstrated that precise manipulation (both rotation rate and equilibrium position) of the particles is possible by controlling the frequency of the applied electric field. At low frequency range, the equilibrium positions of the microparticles are observed between the electrode edge and electrode center. This method of particle manipulation is different from electrorotation as it uses induced AC electroosmosis instead of electric torque as in the case of electrorotation. Moreover, it has been shown that a microparticle can be rotated along its own axis without any translational motion. PMID:27014394

  5. Theory of optical beam deflection for single microparticles

    NASA Astrophysics Data System (ADS)

    Wu, Jiaqi; Kitamori, Takehiko; Sawada, Tsuguo

    1991-05-01

    A theory was developed for the optical beam deflection (OBD) signal generated from a single microparticle. From the thermal-diffusion equations, the temperature fields inside and outside the microparticle, which has a two-layer structure, was deduced. A three-dimensional theoretical treatment was established for the deflection signal of the probe beam passing through the temperature field formed by photothermal conversion of the excitation beam energy absorbed by the sample. The proprieties of the theoretical model and its results were confirmed by comparing the theoretical values of the frequency characteristics, probe beam offset dependencies, and particle size dependencies of the OBD signal with the experimental ones for 25-300-μm-radius microparticles. From the theory, the unique particle size dependencies and frequency characteristics of the OBD method for the single microparticle, i.e., higher sensitivity for smaller particles and at high frequencies, were identified as due to the microparticle surface curvature. The optimal experimental conditions in the OBD measurement of the single microparticle were also obtained using theoretical analysis.

  6. Uniform Microparticles with Controllable Highly Interconnected Hierarchical Porous Structures.

    PubMed

    Zhang, Mao-Jie; Wang, Wei; Yang, Xiu-Lan; Ma, Bing; Liu, Ying-Mei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-07-01

    A simple and versatile strategy is developed for one-step fabrication of uniform polymeric microparticles with controllable highly interconnected hierarchical porous structures. Monodisperse water-in-oil-in-water (W/O/W) emulsions, with methyl methacrylate, ethylene glycol dimethacrylate, and glycidyl methacrylate as the monomer-containing oil phase, are generated from microfluidics and used for constructing the microparticles. Due to the partially miscible property of oil/aqueous phases, the monodisperse W/O/W emulsions can deform into desired shapes depending on the packing structure of inner aqueous microdrops, and form aqueous nanodrops in the oil phase. The deformed W/O/W emulsions allow template syntheses of highly interconnected hierarchical porous microparticles with precisely and individually controlled pore size, porosity, functionality, and particle shape. The microparticles elaborately combine the advantages of enhanced mass transfer, large functional surface area, and flexibly tunable functionalities, providing an efficient strategy to physically and chemically achieve enhanced synergetic performances for extensive applications. This is demonstrated by using the microparticles for oil removal for water purification and protein adsorption for bioseparation. The method proposed in this study provides full versatility for fabrication of functional polymeric microparticles with controllable hierarchical porous structures for enhancing and even broadening their applications.

  7. Performance and accuracy investigations of two Doppler global velocimetry systems applied in parallel

    NASA Astrophysics Data System (ADS)

    Willert, Christian; Stockhausen, Guido; Klinner, Joachim; Lempereur, Christine; Barricau, Philippe; Loiret, Philippe; Raynal, Jean Claude

    2007-08-01

    Two Doppler global velocimetry systems were applied in parallel to assess their performance in wind tunnel environments. Both DGV systems were mounted on a common traverse surrounding the glass-walled 1.4 × 1.8 m2 test section of the wind tunnel. The traverse normally supports a three-component forward-scatter laser Doppler velocimetry system. The reproducible tip-vortex flow field generated by the blunt tip of an airfoil was chosen for this investigation and was precisely surveyed by LDA just prior to the DGV measurements. Both DGV systems shared the same continuous wave laser light source, laser frequency monitoring and fibre optic light sheet delivery system. The principal differences between the DGV implementations are with regard to the imaging configuration. One configuration relied on a single camera view that observed three successively operated light sheets. In the second configuration, three camera views simultaneously observed a single light sheet using a four-branch fibre imaging bundle. The imaging bundle system had all three viewpoints in a forward scattering arrangement which increased the scattering efficiency but reduced the frequency shift sensitivity. Since all three light sheet observation components were acquired onto the same image frame, acquisition times could be reduced to a minimum. On the other hand, the triple light sheet-single camera system observed two light sheets in forward scatter and one light sheet in backscatter. Although three separate images had to be recorded in succession, the image quality, spatial resolution and signal-to-noise ratio were superior to the imaging bundle system. Comparison of the DGV data with LDV measurements shows very good agreement to within 1-2 m s-1. The remaining discrepancy has a variety of causes, some are related to the reduced resolving power of the fibre imaging bundle system (graininess, smoothing), exact localization of the receiver head with respect to the scene, laser frequency drift or

  8. Development of molecular based optical techniques for thermometry and velocimetry for fluorocarbon media

    NASA Astrophysics Data System (ADS)

    Pouya, Shahram; Blanchard, Gary; Koochesfahani, Manoochehr

    2016-11-01

    Fluorocarbon solvents are very stable inert fluids with unique physical properties that make them attractive compounds as refrigerant and several medical applications such as contrast enhanced ultrasound imaging. Since they do not mix with typical organic solvents or water, most luminescent (fluorescent or phosphorescent) probes cannot be used as tracers for optical diagnostic techniques. Perfluoropentane, a compound from this family, is used as a simulant fluid by NASA for two-phase heat transfer/mixing experiments under micro-gravity condition due to its low boiling temperature. Here we study the feasibility of employing non-intrusive optical methods for measurements of temperature and/or velocity within Perfluoropentane as the working fluid. Preliminary results of temperature and velocity measurement using Laser Induced Fluorescence and Molecular Tagging Velocimetry are presented. This work was supported by NASA Grant Number NNX16AD52A.

  9. In-cylinder engine flow measurement using stereoscopic molecular tagging velocimetry (SMTV)

    NASA Astrophysics Data System (ADS)

    Mittal, M.; Sadr, R.; Schock, H. J.; Fedewa, A.; Naqwi, A.

    2009-02-01

    The stereoscopic molecular tagging velocimetry (SMTV) technique is used to obtain the multiple point measurement of an instantaneous three-component velocity field inside the cylinder of an internal combustion (IC) engine assembly. A novel image processing technique is implemented to obtain the velocity data. The technique has the advantage that it eliminates the geometric details required to obtain the three components of the velocity field. The procedure involves two major steps: (i) calibration process and (ii) data acquisition and reduction. Cycle-to-cycle variations of the three-component velocity field and out-of-plane vorticity are presented inside an engine cylinder. Preliminary results show that cycle-to-cycle variations are more prominent in the velocity component perpendicular to the tumble plane, as opposed to the in-plane components. Such new insights will help better understand the details of these flows and further improve CFD models for IC engines.

  10. Development of a Diver-Operated Single Camera Volumetric Velocimetry System

    NASA Astrophysics Data System (ADS)

    Troutman, Valerie; Dabiri, John

    2016-11-01

    The capabilities of a single camera, volumetric velocimetry system for in situ measurement in marine environments are demonstrated by imaging a well-characterized flow in a laboratory environment. This work represents the first stages in the design of a SCUBA-diver operated system to study organisms and biological processes under the natural light in the water column. This system is primarily composed of a volumetric particle tracking diagnostic to investigate fluid-animal interactions. A target domain size of a 20 cm sided cube is sought as a key design feature for the capability of capturing the flow around a variety of benthic and freely swimming organisms. The integration of the particle tracking system with additional diagnostics will be discussed.

  11. Spectroscopic interpretation and velocimetry analysis of fluctuations in a cylindrical plasma recorded by a fast camera

    SciTech Connect

    Oldenbuerger, S.; Brandt, C.; Brochard, F.; Lemoine, N.; Bonhomme, G.

    2010-06-15

    Fast visible imaging is used on a cylindrical magnetized argon plasma produced by thermionic discharge in the Mirabelle device. To link the information collected with the camera to a physical quantity, fast camera movies of plasma structures are compared to Langmuir probe measurements. High correlation is found between light fluctuations and plasma density fluctuations. Contributions from neutral argon and ionized argon to the overall light intensity are separated by using interference filters and a light intensifier. Light emitting transitions are shown to involve a metastable neutral argon state that can be excited by thermal plasma electrons, thus explaining the good correlation between light and density fluctuations. The propagation velocity of plasma structures is calculated by adapting velocimetry methods to the fast camera movies. The resulting estimates of instantaneous propagation velocity are in agreement with former experiments. The computation of mean velocities is discussed.

  12. Microparticles: Facile and High-Throughput Synthesis of Functional Microparticles with Quick Response Codes (Small 24/2016).

    PubMed

    Ramirez, Lisa Marie S; He, Muhan; Mailloux, Shay; George, Justin; Wang, Jun

    2016-06-01

    Microparticles carrying quick response (QR) barcodes are fabricated by J. Wang and co-workers on page 3259, using a massive coding of dissociated elements (MiCODE) technology. Each microparticle can bear a special custom-designed QR code that enables encryption or tagging with unlimited multiplexity, and the QR code can be easily read by cellphone applications. The utility of MiCODE particles in multiplexed DNA detection and microtagging for anti-counterfeiting is explored.

  13. Precision of FLEET Velocimetry Using High-speed CMOS Camera Systems

    NASA Technical Reports Server (NTRS)

    Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

    2015-01-01

    Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 micro sec, precisions of 0.5 m/s in air and 0.2 m/s in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision High Speed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

  14. Precision of FLEET Velocimetry Using High-Speed CMOS Camera Systems

    NASA Technical Reports Server (NTRS)

    Peters, Christopher J.; Danehy, Paul M.; Bathel, Brett F.; Jiang, Naibo; Calvert, Nathan D.; Miles, Richard B.

    2015-01-01

    Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 microseconds, precisions of 0.5 meters per second in air and 0.2 meters per second in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision HighSpeed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

  15. Endothelial Dysfunction Caused by Circulating Microparticles from Patients with Metabolic Syndrome

    PubMed Central

    Agouni, Abdelali; Lagrue-Lak-Hal, Anne Hélène; Ducluzeau, Pierre Henri; Mostefai, Hadj Ahmed; Draunet-Busson, Catherine; Leftheriotis, Georges; Heymes, Christophe; Martinez, Maria Carmen; Andriantsitohaina, Ramaroson

    2008-01-01

    Microparticles are membrane vesicles that are released during cell activation and apoptosis. Elevated levels of microparticles occur in many cardiovascular diseases; therefore, we characterized circulating microparticles from both metabolic syndrome (MS) patients and healthy patients. We evaluated microparticle effects on endothelial function; however, links between circulating microparticles and endothelial dysfunction have not yet been demonstrated. Circulating microparticles and their cellular origins were examined by flow cytometry of blood samples from patients and healthy subjects. Microparticles were used either to treat human endothelial cells in vitro or to assess endothelium function in mice after intravenous injection. MS patients had increased circulating levels of microparticles compared with healthy patients, including microparticles from platelet, endothelial, erythrocyte, and procoagulant origins. In vitro treatment of endothelial cells with microparticles from MS patients reduced both nitric oxide (NO) and superoxide anion production, resulting in protein tyrosine nitration. These effects were associated with enhanced phosphorylation of endothelial NO synthase at the site of inhibition. The reduction of O2− was linked to both reduced expression of p47phox of NADPH oxidase and overexpression of extracellular superoxide dismutase. The decrease in NO production was triggered by nonplatelet-derived microparticles. In vivo injection of MS microparticles into mice impaired endothelium-dependent relaxation and decreased endothelial NO synthase expression. These data provide evidence that circulating microparticles from MS patients influence endothelial dysfunction. PMID:18772329

  16. 3-D Velocimetry of Strombolian Explosions

    NASA Astrophysics Data System (ADS)

    Taddeucci, J.; Gaudin, D.; Orr, T. R.; Scarlato, P.; Houghton, B. F.; Del Bello, E.

    2014-12-01

    Using two synchronized high-speed cameras we were able to reconstruct the three-dimensional displacement and velocity field of bomb-sized pyroclasts in Strombolian explosions at Stromboli Volcano. Relatively low-intensity Strombolian-style activity offers a rare opportunity to observe volcanic processes that remain hidden from view during more violent explosive activity. Such processes include the ejection and emplacement of bomb-sized clasts along pure or drag-modified ballistic trajectories, in-flight bomb collision, and gas liberation dynamics. High-speed imaging of Strombolian activity has already opened new windows for the study of the abovementioned processes, but to date has only utilized two-dimensional analysis with limited motion detection and ability to record motion towards or away from the observer. To overcome this limitation, we deployed two synchronized high-speed video cameras at Stromboli. The two cameras, located sixty meters apart, filmed Strombolian explosions at 500 and 1000 frames per second and with different resolutions. Frames from the two cameras were pre-processed and combined into a single video showing frames alternating from one to the other camera. Bomb-sized pyroclasts were then manually identified and tracked in the combined video, together with fixed reference points located as close as possible to the vent. The results from manual tracking were fed to a custom software routine that, knowing the relative position of the vent and cameras, and the field of view of the latter, provided the position of each bomb relative to the reference points. By tracking tens of bombs over five to ten frames at different intervals during one explosion, we were able to reconstruct the three-dimensional evolution of the displacement and velocity fields of bomb-sized pyroclasts during individual Strombolian explosions. Shifting jet directivity and dispersal angle clearly appear from the three-dimensional analysis.

  17. Multipurpose Pressure Vessel Scanner and Photon Doppler Velocimetry

    NASA Technical Reports Server (NTRS)

    Ellis, Tayera

    2015-01-01

    Critical flight hardware typically undergoes a series of nondestructive evaluation methods to screen for defects before it is integrated into the flight system. Conventionally, pressure vessels have been inspected for flaws using a technique known as fluorescent dye penetrant, which is biased to inspector interpretation. An alternate method known as eddy current is automated and can detect small cracks better than dye penetrant. A new multipurpose pressure vessel scanner has been developed to perform internal and external eddy current scanning, laser profilometry, and thickness mapping on pressure vessels. Before this system can be implemented throughout industry, a probability of detection (POD) study needs to be performed to validate the system's eddy current crack/flaw capabilities. The POD sample set will consist of 6 flight-like metal pressure vessel liners with defects of known size. Preparation for the POD includes sample set fabrication, system operation, procedure development, and eddy current settings optimization. For this, collaborating with subject matter experts was required. This technical paper details the preparation activities leading up to the POD study currently scheduled for winter 2015/2016. Once validated, this system will be a proven innovation for increasing the safety and reliability of necessary flight hardware. Additionally, testing of frangible joint requires Photon Doppler Velocimetry (PDV) and Digital Image Correlation instrumentation. There is often noise associated with PDV data, which necessitates a frequency modulation (FM) signal-to-noise pre-test. Generally, FM radio works by varying the carrier frequency and mixing it with a fixed frequency source, creating a beat frequency which is represented by audio frequency that can be heard between about 20 to 20,000 Hz. Similarly, PDV reflects a shifted frequency (a phenomenon known as the Doppler Effect) from a moving source and mixes it with a fixed source frequency, which results in

  18. Multipurpose Pressure Vessel Scanner and Photon Doppler Velocimetry

    NASA Technical Reports Server (NTRS)

    Ellis, Tayera

    2015-01-01

    Critical flight hardware typically undergoes a series of nondestructive evaluation methods to screen for defects before it is integrated into the flight system. Conventionally, pressure vessels have been inspected for flaws using a technique known as fluorescent dye penetrant, which is biased to inspector interpretation. An alternate method known as eddy current is automated and can detect small cracks better than dye penetrant. A new multipurpose pressure vessel scanner has been developed to perform internal and external eddy current scanning, laser profilometry, and thickness mapping on pressure vessels. Before this system can be implemented throughout industry, a probability of detection (POD) study needs to be performed to validate the system’s eddy current crack/flaw capabilities. The POD sample set will consist of 6 flight-like metal pressure vessel liners with defects of known size. Preparation for the POD includes sample set fabrication, system operation, procedure development, and eddy current settings optimization. For this, collaborating with subject matter experts was required. This technical paper details the preparation activities leading up to the POD study currently scheduled for winter 2015/2016. Once validated, this system will be a proven innovation for increasing the safety and reliability of necessary flight hardware.Additionally, testing of frangible joint requires Photon Doppler Velocimetry (PDV) and Digital Image Correlation instrumentation. There is often noise associated with PDV data, which necessitates a frequency modulation (FM) signal-to-noise pre-test. Generally, FM radio works by varying the carrier frequency and mixing it with a fixed frequency source, creating a beat frequency which is represented by audio frequency that can be heard between about 20 to 20,000 Hz. Similarly, PDV reflects a shifted frequency (a phenomenon known as the Doppler Effect) from a moving source and mixes it with a fixed source frequency, which results in

  19. Optical manipulation of microparticles and biological structures

    NASA Astrophysics Data System (ADS)

    Gahagan, Kevin Thomas

    1998-06-01

    We report experimental and theoretical investigations of the trapping of microparticles and biological objects using radiation pressure. Part I of this thesis presents a technique for trapping both low and high index microparticles using a single, stationary focused laser beam containing an optical vortex. Advantages of this vortex trap include the ease of implementation, a lower exposure level for high-index particles compared to a standard Gaussian beam trap, and the ability to isolate individual low-index particles in concentrated dispersions. The vortex trap is modeled using ray-tracing methods and a more precise electromagnetic model, which is accurate for particles less than 10 μm in diameter. We have measured the stable equilibrium position for two low-index particle systems (e.g., hollow glass spheres (HGS) in water, and water droplets in acetophenone (W/A)). The strength of the trap was measured for the HGS system along the longitudinal and transverse directions. We also demonstrate simultaneous trapping of a low and high index particle with a vortex beam. The stability of this dual-particle trap is found to depend on the relative particle size, the divergence angle of the beam, and the depth of the particles within the trapping chamber. Part II presents results from an interdisciplinary and collaborative investigation of an all-optical genetic engineering technique whereby Agrobacterium rhizogenes were inserted through a laser-ablated hole in the cell wall of the plant, Gingko biloba. We describe a protocol which includes the control of osmotic conditions, culturing procedures, viability assays and laser microsurgery. We succeeded in placing up to twelve viable bacteria into a single plant cell using this technique. The bacteria are believed to be slightly heated by the Gaussian beam trap. A numerical model is presented predicting a temperature rise of just a few degrees. Whereas G. biloba and A. rhitogenes were chosen for this study because of Ginkgo

  20. Optical Probes For Continuous Fabry-Perot Velocimetry Inside Materials

    SciTech Connect

    Goosman, D; Wade, J; Garza, R; Avara, G; Crabtree, T; Rivera, A; Hare, D; Tolar, D; Bratton, B

    2004-08-11

    We have used velocimetry for many years at LLNL to measure velocity-time histories of surfaces in dynamic experiments. We have developed and now use special instrumentation to make continuous shock-velocity measurements inside of materials. The goal is to extend the field of velocimetry into a new area of application in shock physics. At the last Congress we reported the successful use of our new filter system for selectively eliminating most of the non- Doppler-shifted light. We showed one record of a fiber embedded inside an explosive making a continuous detonation velocity-time history. At that time it was difficult to obtain complete records. We have now carried out over 65 inexpensive experiments usually using small cylinders or rectangular blocks of explosives or metals. Most were started by detonating a 25 mm diam by 25 mm long cylinder of Comp B explosive to drive a shock into an adjacent material of similar dimensions, using our embedded fiber probes. In contrast to surface velocimetry, embedded measurements involve detailed hydrodynamic considerations in order to result in a successful record. Calculations have guided us in understanding of various failed and successful experiments. The homogeneity of the explosive, poor contact, the materials used in the cladding and core of the fiber optic probes, and the shock speeds to be covered all greatly affect the success of an experiment. For example, a poor contact between the optical fiber and its environment causes severe loss of data. Non-symmetric air gaps on one side of the fiber cause 3 dimensional hydrodynamic effects which cause the shock wave in the fiber core to be too steeply angled to reflect light. We have recently developed and successfully used a special probe to usually overcome this limitation. We have custom designed several unique types of fiber-optic probes for specialty applications, using both solid and liquid core materials, to extend the usable shock-velocity range.

  1. Adapted MR velocimetry of slow liquid flow in porous media

    NASA Astrophysics Data System (ADS)

    Huang, Li; Mikolajczyk, Gerd; Küstermann, Ekkehard; Wilhelm, Michaela; Odenbach, Stefan; Dreher, Wolfgang

    2017-03-01

    MR velocimetry of liquid flow in opaque porous filters may play an important role in better understanding the mechanisms of deep bed filtration. With this knowledge, the efficiency of separating the suspended solid particles from the vertically flowing liquid can be improved, and thus a wide range of industrial applications such as wastewater treatment and desalination can be optimized. However, MR velocimetry is challenging for such studies due to the low velocities, the severe B0 inhomogeneity in porous structures, and the demand for high spatial resolution and an appropriate total measurement time during which the particle deposition will change velocities only marginally. In this work, a modified RARE-based MR velocimetry method is proposed to address these issues for velocity mapping on a deep bed filtration cell. A dedicated RF coil with a high filling factor is constructed considering the limited space available for the vertical cell in a horizontal MR magnet. Several means are applied to optimize the phase contrast RARE MRI pulse sequence for accurately measuring the phase contrast in a long echo train, even in the case of a low B1 homogeneity. Two means are of particular importance. One uses data acquired with zero flow to correct the phase contrast offsets from gradient imperfections, and the other combines the phase contrast from signals of both odd and even echoes. Results obtained on a 7T preclinical MR scanner indicate that the low velocities in the heterogeneous system can be correctly quantified with high spatial resolution and an adequate total measurement time, enabling future studies on flow during the filtration process.

  2. Upconversion microparticles as time-resolved luminescent probes for multiphoton microscopy: desired signal extraction from the streaking effect

    NASA Astrophysics Data System (ADS)

    Pominova, Daria V.; Ryabova, Anastasia V.; Grachev, Pavel V.; Romanishkin, Igor D.; Kuznetsov, Sergei V.; Rozhnova, Julia A.; Yasyrkina, Daria S.; Fedorov, Pavel P.; Loschenov, Victor B.

    2016-09-01

    The great interest in upconversion nanoparticles exists due to their high efficiency under multiphoton excitation. However, when these particles are used in scanning microscopy, the upconversion luminescence causes a streaking effect due to the long lifetime. This article describes a method of upconversion microparticle luminescence lifetime determination with help of modified Lucy-Richardson deconvolution of laser scanning microscope (LSM) image obtained under near-IR excitation using nondescanned detectors. Determination of the upconversion luminescence intensity and the decay time of separate microparticles was done by intensity profile along the image fast scan axis approximation. We studied upconversion submicroparticles based on fluoride hosts doped with Yb3+-Er3+ and Yb3+-Tm3+ rare earth ion pairs, and the characteristic decay times were 0.1 to 1.5 ms. We also compared the results of LSM measurements with the photon counting method results; the spread of values was about 13% and was associated with the approximation error. Data obtained from live cells showed the possibility of distinguishing the position of upconversion submicroparticles inside and outside the cells by the difference of their lifetime. The proposed technique allows using the upconversion microparticles without shells as probes for the presence of OH- ions and CO2 molecules.

  3. Magnetic microparticle steering within the constraints of an MRI system: proof of concept of a novel targeting approach.

    PubMed

    Mathieu, Jean-Baptiste; Martel, Sylvain

    2007-12-01

    This paper presents a magnetic microparticle steering approach that relies on improved gradient coils for Magnetic Resonance Imaging (MRI) systems. A literature review exposes the motivation and advantages of this approach and leads to a description of the requirements for a set of dedicated steering gradient coils in comparison to standard imaging coils. An experimental set-up was developed to validate the mathematical models and the hypotheses arising from this targeting modality. Magnetite Fe(3)O(4) microparticles (dia. 10.9 microm) were steered in a Y-shaped 100 microm diameter microchannel between a Maxwell pair (dB/dz = 443 mT/m) located in the center of an MRI bore with 0.525 m/s mean fluid velocity (ten times faster than in arterioles with same diameter). Experimental results based on the percentage of particles retrieved at the targeted outlet show that the mathematical models developed provide an order of magnitude estimate of the magnetic gradient strengths required. Furthermore, these results establish a proof of concept of microparticle steering using magnetic gradients within an MRI bore for applications in the human cardiovascular system.

  4. Instantaneous Doppler Global Velocimetry Measurements of a Rotor Wake: Lessons Learned

    NASA Technical Reports Server (NTRS)

    Meyers, James; Fleming, Gary A.; Gorton, Susan Althoff; Berry, John D.

    1998-01-01

    A combined Doppler Global Velocimetry (DGV) and Projection Moir Interferometry (PMI) investigation of a helicopter rotor wake flow field and rotor blade deformation is presented. The three-component DGV system uses a single-frequency, frequency-doubled Nd:YAG laser to obtain instantaneous velocity measurements in the flow. The PMI system uses a pulsed laser-diode bar to obtain blade bending and twist measurements at the same instant that DGV measured the flow. The application of pulse lasers to DGV and PMI in large-scale wind tunnel applications represents a major step forward in the development of these technologies. As such, a great deal was learned about the difficulties of using these instruments to obtain instantaneous measurements in large facilities. Laser speckle and other image noise in the DGV data images were found to be traceable to the Nd:YAG laser. Although image processing techniques were used to virtually eliminate laser speckle noise, the source of low-frequency image noise is still under investigation. The PMI results agreed well with theoretical predictions of blade bending and twist.

  5. Development of Doppler Global Velocimetry as a Flow Diagnostics Tool

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1995-01-01

    The development of Doppler global velocimetry is described from its inception to its use as a flow diagnostics tool. Its evolution is traced from an elementary one-component laboratory prototype, to a full three-component configuration operating in a wind tunnel at focal distances exceeding 15 m. As part of the developmental process, several wind tunnel flow field investigations were conducted. These included supersonic flow measurements about an oblique shock, subsonic and supersonic measurements of the vortex flow above a delta wing, and three-component measurements of a high-speed jet.

  6. Hardening Doppler Global Velocimetry Systems for Large Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.; Fletcher, Mark T.; South, Bruce W.

    2004-01-01

    The development of Doppler Global Velocimetry from a laboratory curiosity to a wind tunnel instrumentation system is discussed. This development includes system advancements from a single velocity component to simultaneous three components, and from a steady state to instantaneous measurement. Improvements to system control and stability are discussed along with solutions to real world problems encountered in the wind tunnel. This on-going development program follows the cyclic evolution of understanding the physics of the technology, development of solutions, laboratory and wind tunnel testing, and reevaluation of the physics based on the test results.

  7. SIRHEN : a data reduction program for photonic Doppler velocimetry measurements.

    SciTech Connect

    Dolan, Daniel H., III; Ao, Tommy

    2010-06-01

    SIRHEN (Sandia InfraRed HEtrodyne aNalysis) is a program for reducing data from photonic Doppler velocimetry (PDV) measurements. SIRHEN uses the short-time Fourier transform method to extract velocity information. The program can be run in MATLAB (2008b or later) or as a Windows executable. This report describes the new Sandia InfraRed HEtrodyne aNalysis program (SIRHEN; pronounced 'siren') that has been developed for efficient and robust analysis of PDV data. The program was designed for easy use within Sandia's dynamic compression community.

  8. Characterisation of inorganic microparticles in pigment cells of human gut associated lymphoid tissue.

    PubMed Central

    Powell, J J; Ainley, C C; Harvey, R S; Mason, I M; Kendall, M D; Sankey, E A; Dhillon, A P; Thompson, R P

    1996-01-01

    Macrophages at the base of human gut associated lymphoid tissue (GALT), become loaded early in life with dark granular pigment that is rich in aluminium, silicon, and titanium. The molecular characteristics, intracellular distribution, and source of this pigment is described. Laser scanning and electron microscopy showed that pigmented macrophages were often closely related to collagen fibres and plasma cells in GALT of both small and large intestine and contained numerous phagolysosomes, previously described as granules, that are rich in electron dense submicron sized particles. Morphological assessment, x ray microanalysis, and image electron energy loss spectroscopy showed three distinct types of microparticle: type I - spheres of titanium dioxide, 100-200 nm diameter, characterised as the synthetic food-additive polymorph anatase; type II - aluminosilicates, < 100-400 nm in length, generally of flaky appearance, often with adsorbed surface iron, and mostly characteristic of the natural clay mineral kaolinite; and type III - mixed environmental silicates without aluminium, 100-700 nm in length and of variable morphology. Thus, this cellular pigment that is partly derived from food additives and partly from the environment is composed of inert inorganic microparticles and loaded into phagolysosomes of macrophages within the GALT of all human subjects. These observations suggest that the pathogenicity of this pigment should be further investigated since, in susceptible individuals, the same intracellular distribution of these three types of submicron particle causes chronic latent granulomatous inflammation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 PMID:8675092

  9. Formation of monodisperse mesoporous silica microparticles via spray-drying.

    PubMed

    Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

    2014-03-15

    In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules.

  10. Enzyme-responsive hydrogel microparticles for pulmonary drug delivery.

    PubMed

    Secret, Emilie; Kelly, Stefan J; Crannell, Kelsey E; Andrew, Jennifer S

    2014-07-09

    Poly(ethylene glycol) based hydrogel microparticles were developed for pulmonary drug delivery. Hydrogels are particularly attractive for pulmonary delivery because they can be size engineered for delivery into the bronchi, yet also swell upon reaching their destination to avoid uptake and clearance by alveolar macrophages. To develop enzyme-responsive hydrogel microparticles for pulmonary delivery a new synthesis method based on a solution polymerization was developed. This method produces spherical poly(ethylene glycol) (PEG) microparticles from high molecular weight poly(ethylene glycol) diacrylate (PEGDA)-based precursors that incorporate peptides in the polymer chain. Specifically, we have synthesized hydrogel microparticles that degrade in response to matrix metalloproteinases that are overexpressed in pulmonary diseases. Small hydrogel microparticles with sizes suitable for lung delivery by inhalation were obtained from solid precursors when PEGDA was dissolved in water at a high concentration. The average diameter of the particles was between 2.8 and 4 μm, depending on the molecular weight of the precursor polymer used and its concentration in water. The relation between the physical properties of the particles and their enzymatic degradation is also reported, where an increased mesh size corresponds to increased degradation.

  11. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    PubMed

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution.

  12. Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles

    PubMed Central

    Sheikh, Faheem A.; Macossay, Javier; Kanjwal, Muzafar A.; Abdal-hay, Abdalla; Tantry, Mudasir A.; Kim, Hern

    2013-01-01

    The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems. PMID:24436780

  13. Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles

    NASA Astrophysics Data System (ADS)

    Yeredla, Nitish; Kojima, Taisuke; Yang, Yi; Takayama, Shuichi; Kanapathipillai, Mathumai

    2016-06-01

    Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations.

  14. Novel injectable, self-gelling hydrogel-microparticle composites for bone regeneration consisting of gellan gum and calcium and magnesium carbonate microparticles.

    PubMed

    Douglas, Timothy E L; Łapa, Agata; Reczyńska, Katarzyna; Krok-Borkowicz, Małgorzata; Pietryga, Krzysztof; Samal, Sangram Keshari; Declercq, Heidi A; Schaubroeck, David; Boone, Marijn; Van der Voort, Pascal; De Schamphelaere, Karel; Stevens, Christian V; Bliznuk, Vitaliy; Balcaen, Lieve; Parakhonskiy, Bogdan V; Vanhaecke, Frank; Cnudde, Veerle; Pamuła, Elżbieta; Skirtach, Andre G

    2016-11-21

    The suitability of hydrogel biomaterials for bone regeneration can be improved by incorporation of an inorganic phase in particle form, thus maintaining hydrogel injectability. In this study, carbonate microparticles containing different amounts of calcium (Ca) and magnesium (Mg) were added to solutions of the anionic polysaccharide gellan gum (GG) to crosslink GG by release of Ca(2+) and Mg(2+) from microparticles and thereby induce formation of hydrogel-microparticle composites. It was hypothesized that increasing Mg content of microparticles would promote GG hydrogel formation. The effect of Mg incorporation on cytocompatibility and cell growth was also studied. Microparticles were formed by mixing Ca(2+) and Mg(2+) and [Formula: see text] ions in varying concentrations. Microparticles were characterized physiochemically and subsequently mixed with GG solution to form hydrogel-microparticle composites. The elemental Ca:Mg ratio in the mineral formed was similar to the Ca:Mg ratio of the ions added. In the absence of Mg, vaterite was formed. At low Mg content, magnesian calcite was formed. Increasing the Mg content further caused formation of amorphous mineral. Microparticles of vaterite and magnesium calcite did not induce GG hydrogel formation, but addition of Mg-richer amorphous microparticles induced gelation within 20 min. Microparticles were dispersed homogeneously in hydrogels. MG-63 osteoblast-like cells were cultured in eluate from hydrogel-microparticle composites and on the composites themselves. All composites were cytocompatible. Cell growth was highest on composites containing particles with an equimolar Ca:Mg ratio. In summary, carbonate microparticles containing a sufficient amount of Mg induced GG hydrogel formation, resulting in injectable, cytocompatible hydrogel-microparticle composites.

  15. Controlling protein release using biodegradable microparticles

    NASA Astrophysics Data System (ADS)

    Kline, Benjamin Patrick

    Research in the field of protein therapeutics has exploded over the past decade and continues to grow in both academia and in industry. Protein drugs have advantages of being highly specific and highly active making them coveted targets for high profile disease states like cancer and multiple sclerosis. Unfortunately, their many advantages are complemented by their obstacles. Because proteins are highly active and highly specific, the window between efficacy and toxicity is very narrow and drug development can be long and arduous. In addition, protein activity is dependent on its specific folding conformation that is easily disrupted by a variety of development processes. This research aimed to identify microparticle formulations to control protein release and also to determine which formulation parameters affected burst release, encapsulation, and steady-state release the most. It was found that polymer type and composition were two of the most important factors. Long-term controlled release of bovine serum albumin (BSA) was achieved as well as a wide variety of release profiles. A method was identified for micronizing protein at low cost to retain activity and coacervation was evaluated as a method for preparing protein loaded microspheres. This research provides a basis from which researchers can create better controlled release formulations for future protein therapeutics.

  16. Bead mediated separation of microparticles in droplets

    PubMed Central

    Sung, Ki-Joo; Lin, Xiaoxia Nina; Burns, Mark A.

    2017-01-01

    Exchange of components such as particles and cells in droplets is important and highly desired in droplet microfluidic assays, and many current technologies use electrical or magnetic fields to accomplish this process. Bead-based microfluidic techniques offer an alternative approach that uses the bead’s solid surface to immobilize targets like particles or biological material. In this paper, we demonstrate a bead-based technique for exchanging droplet content by separating fluorescent microparticles in a microfluidic device. The device uses posts to filter surface-functionalized beads from a droplet and re-capture the filtered beads in a new droplet. With post spacing of 7 μm, beads above 10 μm had 100% capture efficiency. We demonstrate the efficacy of this system using targeted particles that bind onto the functionalized beads and are, therefore, transferred from one solution to another in the device. Binding capacity tests performed in the bulk phase showed an average binding capacity of 5 particles to each bead. The microfluidic device successfully separated the targeted particles from the non-targeted particles with up to 98% purity and 100% yield. PMID:28282412

  17. Optimization of MR phase-contrast-based flow velocimetry and shear stress measurements.

    PubMed

    Kim, Taeho; Seo, Ji-Hyea; Bang, Seong-Sik; Choi, Hyeon-Woo; Chang, Yongmin; Lee, Jongmin

    2010-02-01

    This study was designed to measure the pixel-by-pixel flow velocity and shear stress from phase-contrast MR images. An optimized method was suggested and the use of the method was confirmed. A self-developed, straight steady flow model system was scanned by MRI with a velocity-encoded phase-contrast sequence. In-house developed software was used for the pixel-by-pixel flow velocity and shear stress measurements and the measurements were compared with physically measured mean velocity and shear stress. A comparison between the use of the in-house velocimetry software and a commercial velocimetry system was also performed. Curved steady flow models were scanned by phase-contrast MRI. Subsequently, velocity and shear stress were measured to confirm the shifted peak flow velocity and shear stress toward the outer side of the lumen. Peak velocity and shear stress were calculated for both the inner and outer half of the lumen and were statistically compared. The mean velocity measured with the use of in-house software had a significant correlation with the physical measurements of mean velocity; in addition, the measurement was more precise compared to the commercial system (R(2) = 0.85 vs. 0.75, respectively). The calculated mean shear stress had a significant correlation with the physical measurements of mean shear stress (R(2) = 0.95). The curved flow model showed a significantly shifted peak velocity and shear stress zones toward the outside of the flow (P < 0.0001). The technique to measure pixel-by-pixel velocity and shear stress of steady flow from velocity-encoded phase-contrast MRI was optimized. This technique had a good correlation with physical measurements and was superior to a commercially available system.

  18. Volumetric intake flow measurements of an IC engine using magnetic resonance velocimetry

    NASA Astrophysics Data System (ADS)

    Freudenhammer, Daniel; Baum, Elias; Peterson, Brian; Böhm, Benjamin; Jung, Bernd; Grundmann, Sven

    2014-05-01

    Magnetic resonance velocimetry (MRV) measurements are performed in a 1:1 scale model of a single-cylinder optical engine to investigate the volumetric flow within the intake and cylinder geometry during flow induction. The model is a steady flow water analogue of the optical IC-engine with a fixed valve lift of mm to simulate the induction flow at crank-angle bTDC. This setup resembles a steady flow engine test bench configuration. MRV measurements are validated with phase-averaged particle image velocimetry (PIV) measurements performed within the symmetry plane of the optical engine. Differences in experimental operating parameters between MRV and PIV measurements are well addressed. Comparison of MRV and PIV measurements is demonstrated using normalized mean velocity component profiles and showed excellent agreement in the upper portion of the cylinder chamber (i.e., mm). MRV measurements are further used to analyze the ensemble average volumetric flow within the 3D engine domain. Measurements are used to describe the 3D overflow and underflow behavior as the annular flow enters the cylinder chamber. Flow features such as the annular jet-like flows extending into the cylinder, their influence on large-scale in-cylinder flow motion, as well as flow recirculation zones are identified in 3D space. Inlet flow velocities are analyzed around the entire valve curtain perimeter to quantify percent mass flow rate entering the cylinder. Recirculation zones associated with the underflow are shown to reduce local mass flow rates up to 50 %. Recirculation zones are further analyzed in 3D space within the intake manifold and cylinder chamber. It is suggested that such recirculation zones can have large implications on cylinder charge filling and variations of the in-cylinder flow pattern. MRV is revealed to be an important diagnostic tool used to understand the volumetric induction flow within engine geometries and is potentially suited to evaluate flow changes due to intake

  19. Analysis of Transitional and Turbulent Flow Through the FDA Benchmark Nozzle Model Using Laser Doppler Velocimetry.

    PubMed

    Taylor, Joshua O; Good, Bryan C; Paterno, Anthony V; Hariharan, Prasanna; Deutsch, Steven; Malinauskas, Richard A; Manning, Keefe B

    2016-09-01

    Transitional and turbulent flow through a simplified medical device model is analyzed as part of the FDA's Critical Path Initiative, designed to improve the process of bringing medical products to market. Computational predictions are often used in the development of devices and reliable in vitro data is needed to validate computational results, particularly estimations of the Reynolds stresses that could play a role in damaging blood elements. The high spatial resolution of laser Doppler velocimetry (LDV) is used to collect two component velocity data within the FDA benchmark nozzle model. Two flow conditions are used to produce flow encompassing laminar, transitional, and turbulent regimes, and viscous stresses, principal Reynolds stresses, and turbulence intensities are calculated from the measured LDV velocities. Axial velocities and viscous stresses are compared to data from a prior inter-laboratory study conducted with particle image velocimetry. Large velocity gradients are observed near the wall in the nozzle throat and in the jet shear layer located in the expansion downstream of the throat, with axial velocity changing as much as 4.5 m/s over 200 μm. Additionally, maximum Reynolds shear stresses of 1000-2000 Pa are calculated in the high shear regions, which are an order of magnitude higher than the peak viscous shear stresses (<100 Pa). It is important to consider the effects of both viscous and turbulent stresses when simulating flow through medical devices. Reynolds stresses above commonly accepted hemolysis thresholds are measured in the nozzle model, indicating that hemolysis may occur under certain flow conditions. As such, the presented turbulence quantities from LDV, which are also available for download at https://fdacfd.nci.nih.gov/ , provide an ideal validation test for computational simulations that seek to characterize the flow field and to predict hemolysis within the FDA nozzle geometry.

  20. A vector scanning processing technique for pulsed laser velocimetry

    NASA Astrophysics Data System (ADS)

    Wernet, Mark P.; Edwards, Robert V.

    1989-03-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of two-dimensional velocity vectors across an extended planar region of a flow. Current processing techniques offer high precision (1 pct) velocity estimates, but can require several hours of processing time on specialized array processors. Under some circumstances, a simple, fast, less accurate (approx. 5 pct), data reduction technique which also gives unambiguous velocity vector information is acceptable. A direct space domain processing technique was examined. The direct space domain processing technique was found to be far superior to any other techniques known, in achieving the objectives listed above. It employs a new data coding and reduction technique, where the particle time history information is used directly. Further, it has no 180 deg directional ambiguity. A complex convection vortex flow was recorded and completely processed in under 2 minutes on an 80386 based PC, producing a 2-D velocity vector map of the flow field. Hence, using this new space domain vector scanning (VS) technique, pulsed laser velocimetry data can be reduced quickly and reasonably accurately, without specialized array processing hardware.

  1. Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

    SciTech Connect

    Erskine, D J; Edelstein, J; Lloyd, J; Muirhead, P

    2006-05-04

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio.

  2. Electrosprayed inulin microparticles for microbiota triggered targeting of colon.

    PubMed

    Jain, Arvind K; Sood, Vishesh; Bora, Meghali; Vasita, Rajesh; Katti, Dhirendra S

    2014-11-04

    Inulin, a naturally occurring polysaccharide, was acetylated to make it processable by electrospraying, a facile and single step method for microparticle fabrication. Electrospraying process parameters were optimized for fabrication of spherical and monodisperse indomethacin (IDM) loaded inulin acetate (INA) microparticles. The apparent entrapment efficiency of IDM was determined to be 100%, whereas working encapsulation efficiency was estimated to be 35.39 ± 1.63%. Differential scanning calorimetry and X-ray diffraction analysis confirmed molecular dispersion of IDM in an amorphous state within the INA matrix. Finally, the results from in vitro release study performed in simulated gastro-intestinal fluids demonstrated that IDM was released only in simulated colonic fluid that contained inulinase. Therefore, this study demonstrates that acetylation of inulin does not alter its susceptibility to inulinase and that microparticles fabricated from INA can be developed as a colon targeting drug delivery system.

  3. Laser-ablation-assisted microparticle acceleration for drug delivery

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Ohki, T.; Gopalan, J.

    2005-10-01

    Localized drug delivery with minimal tissue damage is desired in some of the clinical procedures such as gene therapy, treatment of cancer cells, treatment of thrombosis, etc. We present an effective method for delivering drug-coated microparticles using laser ablation on a thin metal foil containing particles. A thin metal foil, with a deposition of a layer of microparticles is subjected to laser ablation on its backface such that a shock wave propagates through the foil. Due to shock wave loading, the surface of the foil containing microparticles is accelerated to very high speeds, ejecting the deposited particles at hypersonic speeds. The ejected particles have sufficient momentum to penetrate soft body tissues, and the penetration depth observed is sufficient for most of the pharmacological treatments. We have tried delivering 1μm tungsten particles into gelatin models that represent soft tissues, and liver tissues of an experimental rat. Sufficient penetration depths have been observed in these experiments with minimum target damage.

  4. Shape-based separation of microparticles with magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Zhou, Ran

    2016-11-01

    Precise manipulations, e.g., sorting and focusing, of nonspherical micro-particles in fluidic environment has important applications in the fields of biology sciences and biomedical engineering. However, non-spherical microparticles are hard to manipulate because they tumble in shear flows. Most of existing techniques, including traditional filtration and centrifugation, and recent microfluidic technology, have difficulty in separating microparticles by shape. We demonstrate a novel shape-based separation technique by combining external magnetic fields with pressure-driven flows in a microchannel. Due to the magnetic field, prolate ellipsoidal particles migrate laterally at different speeds than the spherical ones, leading to effective separation. Our experimental investigations reveal the underlying physical mechanism of the observed shape-dependent migration. We find that the magnetic field breaks the rotational symmetry of the nonspherical particles, and induces shape-dependent lift force and migration velocity.

  5. Molecular tagging velocimetry and thermometry and its application to the wake of a heated circular cylinder

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Koochesfahani, Manoochehr M.

    2006-06-01

    We report improvements to the molecular tagging velocimetry and thermometry (MTV&T) technique for the simultaneous measurement of velocity and temperature fields in fluid flows. A phosphorescent molecule, which can be turned into a long lifetime tracer upon excitation by photons of appropriate wavelength, is used as a tracer for both velocity and temperature measurements. A pulsed laser is used to 'tag' the regions of interest, and those tagged regions are imaged at two successive times within the lifetime of the tracer molecules. The measured Lagrangian displacement of the tagged molecules provides the estimate of the fluid velocity vector. The simultaneous temperature measurement is achieved by taking advantage of the temperature dependence of phosphorescence lifetime, which is estimated from the intensity ratio of the tagged molecules in the two images. In relation to the original molecular tagging thermometry work of Thompson and Maynes (2001 J. Fluid Eng. 123 293-302), the improvements reported here are the use of lifetime imaging as a ratiometric method to enhance the robustness and accuracy of temperature measurements and the extension of the technique to simultaneous whole-field planar mapping of velocity and temperature fields. Compared with other simultaneous velocity and temperature measurement techniques such as combined PIV-LIF (Sakakibara et al 1997 Int. J. Heat Mass Transfer 40 3163-76, Grissino et al 1999 Proc. 3rd Int. Workshop on Particale Image Velocimetry (Santa Barbara, CA, USA, 16-18 September 1999)) and the DPIV/T technique (Park et al 2001 Exp. Fluids 30 327-38), this method accomplishes the same objectives but with a completely molecular-based approach. Because of its molecular nature, issues such as tracking of the flow by the seed particles and the thermal response of the thermal tracer particles are eliminated. In addition, the use of a single molecular tracer and a dual-frame CCD camera provides for a much reduced burden on the

  6. Single camera volumetric velocimetry in aortic sinus with a percutaneous valve

    NASA Astrophysics Data System (ADS)

    Clifford, Chris; Thurow, Brian; Midha, Prem; Okafor, Ikechukwu; Raghav, Vrishank; Yoganathan, Ajit

    2016-11-01

    Cardiac flows have long been understood to be highly three dimensional, yet traditional in vitro techniques used to capture these complexities are costly and cumbersome. Thus, two dimensional techniques are primarily used for heart valve flow diagnostics. The recent introduction of plenoptic camera technology allows for traditional cameras to capture both spatial and angular information from a light field through the addition of a microlens array in front of the image sensor. When combined with traditional particle image velocimetry (PIV) techniques, volumetric velocity data may be acquired with a single camera using off-the-shelf optics. Particle volume pairs are reconstructed from raw plenoptic images using a filtered refocusing scheme, followed by three-dimensional cross-correlation. This technique was applied to the sinus region (known for having highly three-dimensional flow structures) of an in vitro aortic model with a percutaneous valve. Phase-locked plenoptic PIV data was acquired at two cardiac outputs (2 and 5 L/min) and 7 phases of the cardiac cycle. The volumetric PIV data was compared to standard 2D-2C PIV. Flow features such as recirculation and stagnation were observed in the sinus region in both cases.

  7. Multimodal delivery of irinotecan from microparticles with two distinct compartments.

    PubMed

    Rahmani, Sahar; Park, Tae-Hong; Dishman, Acacia Frances; Lahann, Joerg

    2013-11-28

    In the last several decades, research in the field of drug delivery has been challenged with the fabrication of carrier systems engineered to deliver therapeutics to the target site with sustained and controlled release kinetics. Herein, we report the fabrication of microparticles composed of two distinct compartments: i) one compartment containing a pH responsive polymer, acetal-modified dextran, and PLGA (polylactide-co-glycolide), and ii) one compartment composed entirely of PLGA. We demonstrate the complete release of dextran from the microparticles during a 10-hour period in an acidic pH environment and the complete degradation of one compartment in less than 24h. This is in congruence with the stability of the same microparticles in neutral pH over the 24-hour period. Such microparticles can be used as pH responsive carrier systems for drug delivery applications where their cargo will only be released when the optimum pH window is reached. The feasibility of the microparticle system for such an application was confirmed by encapsulating a cancer therapeutic, irinotecan, in the compartment containing the acetal-modified dextran polymer and the pH dependent release over a 5-day period was studied. It was found that upon pH change to an acidic environment, over 50% of the drug was first released at a rapid rate for 10h, similar to that observed for the dextran release, before continuing at a more controlled rate for 4 days. As such, these microparticles can play an important role in the fabrication of novel drug delivery systems due to the selective, controlled, and pH responsive release of their encapsulated therapeutics.

  8. SDOCT Doppler velocimetry for investigating the morphological influences on blood flow in the developing chick embryo heart

    NASA Astrophysics Data System (ADS)

    Davis, Anjul M.; Rothenberg, Florence G.; Law, Tzuo H.; Taber, Larry A.; Izatt, Joseph A.

    2007-02-01

    The onset of congenital heart disease (CHD) is believed to occur at very early stages of development. Investigations in the initiation and development of CHD has been hampered by the inability to image early stage heart structure and function, in vivo. Imaging small animals using optical coherence tomography (OCT) has filled a niche between the limited penetration depth of confocal microscopy and insufficient resolution from ultrasound. Previous demonstrations of chick heart imaging using OCT have entailed excision of, or arresting the heart to prevent motion artifacts. In this summary, we introduce SDOCT Doppler velocimetry as an enhancement of Doppler OCT for in vivo measurement of localized temporal blood flow dynamics. With this technique, dynamic velocity waveforms were measured in the outflow tract of the heart tube. These flow dynamics correlate to a finite element model of pulsatile flow and may lead to a further understanding of morphological influences on early heart development.

  9. Composition analyzer for microparticles using a spark ion source

    NASA Technical Reports Server (NTRS)

    Auer, S.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the elements of both detector and particle materials. The total extracted ion current was typically 10 A within a period of 100 nsec, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes or by nuclear bomb explosions.

  10. Dielectrophoretic Manipulation and Separation of Microparticles Using Microarray Dot Electrodes

    PubMed Central

    Yafouz, Bashar; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    This paper introduces a dielectrophoretic system for the manipulation and separation of microparticles. The system is composed of five layers and utilizes microarray dot electrodes. We validated our system by conducting size-dependent manipulation and separation experiments on 1, 5 and 15 μm polystyrene particles. Our findings confirm the capability of the proposed device to rapidly and efficiently manipulate and separate microparticles of various dimensions, utilizing positive and negative dielectrophoresis (DEP) effects. Larger size particles were repelled and concentrated in the center of the dot by negative DEP, while the smaller sizes were attracted and collected by the edge of the dot by positive DEP. PMID:24705632

  11. Chemistry of coal-related microparticles

    SciTech Connect

    Davis, E.J.; Krieger-Brockett, B.

    1993-01-11

    A new type of electrodynamic balance was designed, constructed and applied to the study of the chemistry of macerals and the chemical reaction between CaO sorbent particles and SO[sub 2]. The single-particle device was coupled to a Raman spectrometer. With this balance a single electrically charged microparticle is suspended in visible and infrared laser beams by means of superposed ac and dc electrical fields. The apparatus was designed to permit gas flow through the chamber so that gas-solid and gas-liquid chemical reactions can be carried out. A visible laser beam was used to illuminate the particle for Raman and fluorescence measurements, and an infrared laser beam was used to heat the particle. An overview of the experimental system is presented in Figure 1. The levitated particles were heated from two sides using a CO[sub 2] laser operating at the infrared wavelength of 10.6 [mu]m. The optical system used to direct the heating laser beam to the target is shown in Figure 2. Infrared detectors indicated in Figure 1 were used to measure the particle temperature by two-color pyrometery. A new technique was explored to independently determine the particle temperature; the method involves measuring the ratio of the intensities of Stokes and anti-Stokes Raman scattering signals. Although the method is not accurate near room temperature because of the weak and-Stokes signal at low temperatures, the method appears promising for high temperature measurement, and complements the pyrometry method. Optical pyrometry is quite suitable for black body emitters, but for the metal oxides of interest here, optical pyrometry was found to be less satisfactory than an alternate method.

  12. Involvement of microparticles in diabetic vascular complications.

    PubMed

    Tsimerman, Gala; Roguin, Ariel; Bachar, Anat; Melamed, Eyal; Brenner, Benjamin; Aharon, Anat

    2011-08-01

    Type 2 diabetes mellitus (T2DM) is associated with increased coagulability and vascular complications. Circulating microparticles (MPs) are involved in thrombosis, inflammation, and angiogenesis. However, the role of MPs in T2DM vascular complications is unclear. We characterised the cell origin and pro-coagulant profiles of MPs obtained from 41 healthy controls and 123 T2DM patients with coronary artery disease, retinopathy and foot ulcers. The effects of MPs on endothelial cell coagulability and tube formation were evaluated. Patients with severe diabetic foot ulcers expressed the highest levels of MPs originated from platelet and endothelial cells and negatively-charged phospholipid-bearing MPs. MP coagulability, calculated from MP tissue factor (TF) and TF pathway inhibitor (TFPI) ratio, was low in healthy controls and in diabetic retinopathy patients (<0.7) but high in patients with coronary artery disease and foot ulcers (>1.8, p≥0.002). MPs of all T2DM patients induced a more than two-fold increase in endothelial cell TF (antigen and gene expression) but did not affect TFPI levels. Tube networks were longest and most stable in endothelial cells that were incubated with MPs of healthy controls, whereas no tube formation occurred in MPs of diabetic patients with coronary artery disease. MPs of diabetic retinopathy and diabetic foot ulcer patients induced branched tube networks that were unstable and collapsed over time. This study demonstrates that MP characteristics are related to the specific type of vascular complications and may serve as a bio-marker for the pro- coagulant state and vascular pathology in patients with T2DM.

  13. Novel polymer-grafted starch microparticles for mucosal delivery of vaccines.

    PubMed

    Heritage, P L; Loomes, L M; Jianxiong, J; Brook, M A; Underdown, B J; McDermott, M R

    1996-05-01

    Recent studies have demonstrated that systemic and mucosal administration of soluble antigens in biodegradable microparticles can potentiate antigen-specific humoral and cellular immune responses. However, current microparticle formulations are not adequate for all vaccine antigens, necessitating the further development of microparticle carrier systems. In this study, we developed a novel microparticle fabrication technique in which human serum albumin (HSA) was entrapped in starch microparticles grafted with 3-(triethoxysilyl)-propyl-terminated polydimethylsiloxane (TS-PDMS), a biocompatible silicone polymer. The immunogenicity of HSA was preserved during the microparticle fabrication process. Following intraperitoneal immunization of mice, TS-PDMS-grafted microparticles (MP) dramatically enhanced serum IgG responses compared with ungrafted MP and soluble HSA alone (P < 0.001). When delivered orally, both TS-PDMS-grafted and ungrafted microparticles elicited HSA-specific IgA responses in gut secretions, in contrast to orally administered soluble antigen. Indeed, TS-PDMS-grafted microparticles stimulated significantly stronger serum IgG (P < 0.005) and IgA (P < 0.001) responses compared with those elicited by ungrafted microparticles. These findings indicate that TS-PDMS-grafted starch microparticles have potential as systemic and mucosal vaccine delivery vehicles.

  14. Multitarget sensing of glucose and cholesterol based on Janus hydrogel microparticles.

    PubMed

    Sun, Xiao-Ting; Zhang, Ying; Zheng, Dong-Hua; Yue, Shuai; Yang, Chun-Guang; Xu, Zhang-Run

    2017-06-15

    A visualized sensing method for glucose and cholesterol was developed based on the hemispheres of the same Janus hydrogel microparticles. Single-phase and Janus hydrogel microparticles were both generated using a centrifugal microfluidic chip. For glucose sensing, concanavalin A and fluorescein labeled dextran used for competitive binding assay were encapsulated in alginate microparticles, and the fluorescence of the microparticles was positively correlated with glucose concentration. For cholesterol sensing, the microparticles embedded with γ-Fe2O3 nanoparticles were used as catalyst for the oxidation of 3,3',5,5'-Tetramethylbenzidine by H2O2, an enzymatic hydrolysis product of cholesterol. And the color transition was more sensitive in the microparticles than in solutions, indicating the microparticles are more applicable for visualized determination. Furthermore, Janus microparticles were employed for multitarget sensing in the two hemespheres, and glucose and cholesterol were detected within the same microparticles without obvious interference. Besides, the particles could be manipulated by an external magnetic field. The glucose and cholesterol levels were measured in human serum utilizing the microparticles, which confirmed the potential application of the microparticles in real sample detection.

  15. Platelet and not erythrocyte microparticles are procoagulant in transfused thalassaemia major patients.

    PubMed

    Agouti, Imane; Cointe, Sylvie; Robert, Stéphane; Judicone, Coralie; Loundou, Anderson; Driss, Fathi; Brisson, Alain; Steschenko, Dominique; Rose, Christian; Pondarré, Corinne; Bernit, Emmanuelle; Badens, Catherine; Dignat-George, Françoise; Lacroix, Romaric; Thuret, Isabelle

    2015-11-01

    The level of circulating platelet-, erythrocyte-, leucocyte- and endothelial-derived microparticles detected by high-sensitivity flow cytometry was investigated in 37 β-thalassaemia major patients receiving a regular transfusion regimen. The phospholipid procoagulant potential of the circulating microparticles and the microparticle-dependent tissue factor activity were evaluated. A high level of circulating erythrocyte- and platelet-microparticles was found. In contrast, the number of endothelial microparticles was within the normal range. Platelet microparticles were significantly higher in splenectomized than in non-splenectomized patients, independent of platelet count (P < 0·001). Multivariate analysis indicated that phospholipid-dependent procoagulant activity was influenced by both splenectomy (P = 0·001) and platelet microparticle level (P < 0·001). Erythrocyte microparticles were not related to splenectomy, appear to be devoid of proper procoagulant activity and no relationship between their production and haemolysis, dyserythropoiesis or oxidative stress markers could be established. Intra-microparticle labelling with anti-HbF antibodies showed that they originate only partially (median of 28%) from thalassaemic erythropoiesis. In conclusion, when β-thalassaemia major patients are intensively transfused, the procoagulant activity associated with thalassaemic erythrocyte microparticles is probably diluted by transfusions. In contrast, platelet microparticles, being both more elevated and more procoagulant, especially after splenectomy, may contribute to the residual thrombotic risk reported in splenectomized multi-transfused β-thalassaemia major patients.

  16. Decellularized extracellular matrix microparticles as a vehicle for cellular delivery in a model of anastomosis healing.

    PubMed

    Hoganson, David M; Owens, Gwen E; Meppelink, Amanda M; Bassett, Erik K; Bowley, Chris M; Hinkel, Cameron J; Finkelstein, Eric B; Goldman, Scott M; Vacanti, Joseph P

    2016-07-01

    Extracellular matrix (ECM) materials from animal and human sources have become important materials for soft tissue repair. Microparticles of ECM materials have increased surface area and exposed binding sites compared to sheet materials. Decellularized porcine peritoneum was mechanically dissociated into 200 µm microparticles, seeded with fibroblasts and cultured in a low gravity rotating bioreactor. The cells avidly attached and maintained excellent viability on the microparticles. When the seeded microparticles were placed in a collagen gel, the cells quickly migrated off the microparticles and through the gel. Cells from seeded microparticles migrated to and across an in vitro anastomosis model, increasing the tensile strength of the model. Cell seeded microparticles of ECM material have potential for paracrine and cellular delivery therapies when delivered in a gel carrier. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1728-1735, 2016.

  17. Interfacial tension based on-chip extraction of microparticles confined in microfluidic Stokes flows

    NASA Astrophysics Data System (ADS)

    Huang, Haishui; He, Xiaoming

    2014-10-01

    Microfluidics involving two immiscible fluids (oil and water) has been increasingly used to produce hydrogel microparticles with wide applications. However, it is difficult to extract the microparticles out of the microfluidic Stokes flows of oil that have a Reynolds number (the ratio of inertia to viscous force) much less than one, where the dominant viscous force tends to drive the microparticles to move together with the surrounding oil. Here, we present a passive method for extracting hydrogel microparticles in microfluidic Stokes flow from oil into aqueous extracting solution on-chip by utilizing the intrinsic interfacial tension between oil and the microparticles. We further reveal that the thickness of an "extended confining layer" of oil next to the interface between oil and aqueous extracting solution must be smaller than the radius of microparticles for effective extraction. This method uses a simple planar merging microchannel design that can be readily fabricated and further integrated into a fluidic system to extract microparticles for wide applications.

  18. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    NASA Astrophysics Data System (ADS)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong

    2017-02-01

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350-400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  19. A microparticle approach to morphogen delivery within pluripotent stem cell aggregates

    PubMed Central

    Bratt-Leal, Andrés M.; Nguyen, Anh H.; Hammersmith, Katy A.; Singh, Ankur; McDevitt, Todd C.

    2013-01-01

    Stem cell fate and specification is largely controlled by extrinsic cues that comprise the 3D microenvironment. Biomaterials can serve to control the spatial and temporal presentation of morphogenic molecules in order to direct stem cell fate decisions. Here we describe a microparticle (MP)-based approach to deliver growth factors within multicellular aggregates to direct pluripotent stem cell differentiation. Compared to conventional soluble delivery methods, gelatin MPs laden with BMP4 or noggin induced efficient gene expression of mesoderm and ectoderm lineages, respectively, despite using nearly 12-fold less total growth factor. BMP4-laden MPs increased the percentage of cells expressing GFP under the control of the Brachyury-T promoter as visualized by whole-mount confocal imaging and quantified by flow cytometry. Furthermore, the ability to localize MPs laden with different morphogens within a particular hemisphere of stem cell aggregates allowed for spatial control of differentiation within 3D cultures. Overall, localized delivery of growth factors within multicellular aggregates from microparticle delivery vehicles is an important step towards scalable differentiation technologies and the study of morphogen gradients in pluripotent stem cell differentiation. PMID:23827184

  20. Characterization of cells and bacteria by photophoretic velocimetry

    NASA Astrophysics Data System (ADS)

    Helmbrecht, Clemens; Niessner, Reinhard; Haisch, Christoph

    2008-02-01

    The migration induced by intensive light is termed photophoresis. We could show that the evaluation of light-induced velocities of microparticles, bacteria and cells suspended in water is valuable for the prediction of their intrinsic properties. Two different laser setups were evaluated for photophoretic migration, a He-Ne laser (P = 45 mW, λ = 633 nm) and a diode-pumped cw-Nd:YAG (P = 1.1 W, λ = 532 nm). When analyzing the migration behavior of particles, we find significant differences depending on both, geometrical size and refractive index. We describe migration of PS particles of different size as well as with different refractive index but same diameter, SiO II and melamine resin. The potential for the separation of biological matter is shown as velocity distributions of heat killed bacteria of Escherichia coli, Salmonella enteritidis, and baker's yeast is reported.

  1. Magnetic Resonance Velocimetry analysis of an angled impinging jet

    NASA Astrophysics Data System (ADS)

    Irhoud, Alexandre; Benson, Michael; Verhulst, Claire; van Poppel, Bret; Elkins, Chris; Helmer, David

    2016-11-01

    Impinging jets are used to achieve high heat transfer rates in applications ranging from gas turbine engines to electronics. Despite the importance and relative simplicity of the geometry, simulations historically fail to accurately predict the flow behavior in the vicinity of the flow impingement. In this work, we present results from a novel experimental technique, Magnetic Resonance Velocimetry (MRV), which measures three-dimensional time-averaged velocity without the need for optical access. The geometry considered in this study is a circular jet angled at 45 degrees and impinging on a flat plate, with a separation of approximately seven jet diameters between the jet exit and the impingement location. Two flow conditions are considered, with Reynolds numbers of roughly 800 and 14,000. Measurements from the MRV experiment are compared to predictions from Reynolds Averaged Navier Stokes (RANS) simulations, thus demonstrating the utility of MRV for validation of numerical analyses of impinging jet flow.

  2. Application of Doppler Global Velocimetry to Supersonic Flows

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    1996-01-01

    The design and implementation of Doppler Global Velocimetry (DGV) for testing in the Langley Unitary Plan Wind Tunnel is presented. The discussion begins by outlining the characteristics of the tunnel and the test environment, with potential problem areas highlighted. Modifications to the optical system design to implement solutions for these problems are described. Since this tunnel entry was the first ever use of DGV in a supersonic wind tunnel, the test series was divided into three phases, each with its own goal. Phase I determined if condensation provided sufficient scattered light for DGV applications. Phase II studied particle lag by measuring the flow about an oblique shock above an inclined flat plate. Phase III investigated the supersonic vortical flow field above a 75-degree delta wing at 24-degrees angle of attack. Example results from these tests are presented.

  3. Multipoint photonic doppler velocimetry using optical lens elements

    DOEpatents

    Frogget, Brent Copely; Romero, Vincent Todd

    2014-04-29

    A probe including a fisheye lens is disclosed to measure the velocity distribution of a moving surface along many lines of sight. Laser light, directed to the surface and then reflected back from the surface, is Doppler shifted by the moving surface, collected into fisheye lens, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to an index-matching lens and eventually to a fisheye lens. The fiber array flat polished and coupled to the index-matching lens using index-matching gel. Numerous fibers in a fiber array project numerous rays through the fisheye lens which in turn project many measurement points at numerous different locations to establish surface coverage over a hemispherical shape with very little crosstalk.

  4. Investigation of Turbulent Boundary-Layer Separation Using Laser Velocimetry

    NASA Technical Reports Server (NTRS)

    Modarress, D.; Johnson, D. A.

    1979-01-01

    Boundary-layer measurements realized by laser velocimetry are presented for a Much 2.9, two-dimensional, shock-wave/turbulent boundary-layer interaction containing an extensive region of separated flow. Mean velocity and turbulent intensity profiles were obtained from upstream of the interaction zone to downstream of the mean reattachment point. The superiority of the laser velocimeter technique over pressure sensors in turbulent separated flows is demonstrated by a comparison of the laser velocimeter data with results obtained from local pilot and static pressure measurements for the same flow conditions. The locations of the mean separation and reattachment points as deduced from the mean velocity measurements are compared to oil-now visualization results. Representative velocity probability density functions obtained in the separated now region are also presented. Critical to the success of this investigation were: the use of Bragg cell frequency shifting and artificial seeding of the now with submicron light-scattering particles.

  5. Preparation of polystyrene microspheres for laser velocimetry in wind tunnels

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