WorldWideScience

Sample records for doppler velocity measurements

  1. MEMS based Doppler velocity measurement system

    Science.gov (United States)

    Shin, Minchul

    The design, fabrication, modeling and characterization of a capacitive micromachined ultrasonic transducer (cMUT) based in-air Doppler velocity measurement system using a 1 cm2 planar array are described. Continuous wave operation in a narrowband was chosen in order to maximize range, as it allows for better rejection of broadband noise. The sensor array has a 160-185 kHz resonant frequency to achieve a 10 degree beamwidth. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, characterization of the cMUT sensor with a variety of testing procedures is provided. Laser Doppler vibrometry (LDV), beampattern, reflection, and velocity testing characterize the performance of the sensors. The sensor is capable of measuring the velocity of a moving specular reflector with a resolution of 5 cm/s, an update rate of 0.016 second, and a range of 1.5 m.

  2. Measuring Velocity and Acceleration Using Doppler Shift of a ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Abstract. We describe here as to how the Doppler shift of a source needs to be used to measure its velocity and acceleration. We also apply this method, as an example here, to spectral lines of the blue-shifted jet in micro-quasar SS433 and discuss the intricacies of these measurements.

  3. Laser Doppler anemometer measurements using nonorthogonal velocity components: error estimates.

    Science.gov (United States)

    Orloff, K L; Snyder, P K

    1982-01-15

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  4. Laser Doppler detection systems for gas velocity measurement.

    Science.gov (United States)

    Huffaker, R M

    1970-05-01

    The velocity of gas flow has been remotely measured using a technique which involves the coherent detection of scattered laser radiation from small particles suspended in the fluid utilizing the doppler effect. Suitable instrumentation for the study of wind tunnel type and atmospheric flows are described. Mainly for reasons of spatial resolution, a function of the laser wavelength, the wind tunnel system utilizes an argon laser operating at 0.5 micro. The relaxed spatial resolution requirement of atmospheric applications allows the use of a carbon dioxide laser, which has superior performance at a wavelength of 10.6 micro, a deduction made from signal-to-noise ratio considerations. Theoretical design considerations are given which consider Mie scattering predictions, two-phase flow effects, photomixing fundamentals, laser selection, spatial resolution, and spectral broadening effects. Preliminary experimental investigations using the instrumentation are detailed. The velocity profile of the flow field generated by a 1.27-cm diam subsonic jet was investigated, and the result compared favorably with a hot wire investigation conducted in the same jet. Measurements of wind velocity at a range of 50 m have also shown the considerable promise of the atmospheric system.

  5. Ultrasonic distance and velocity measurement using a pair of LPM signals for cross-correlation method: improvement of Doppler-shift compensation and examination of Doppler velocity estimation.

    Science.gov (United States)

    Hirata, Shinnosuke; Kurosawa, Minoru Kuribayashi

    2012-09-01

    Real-time distance measurement of a moving object with high accuracy and high resolution using an ultrasonic wave is difficult due to the influence of the Doppler effect or the limit of the calculation cost of signal processing. An over-sampling signal processing method using a pair of LPM signals has been proposed for ultrasonic distance and velocity measurement of moving objects with high accuracy and high resolution. The proposed method consists of cross correlation by single-bit signal processing, high-resolution Doppler velocity estimation with wide measurement range and low-calculation-cost Doppler-shift compensation. The over-sampling cross-correlation function is obtained from cross correlation by single-bit signal processing with low calculation cost. The Doppler velocity and distance of the object are determined from the peak interval and peak form in the cross-correlation function by the proposed method of Doppler velocity estimation and Doppler-shift compensation. In this paper, the proposed method of Doppler-shift compensation is improved. Accuracy of the determined distance was improved from approximately within ±140μm in the previous method to approximately within ±10μm in computer simulations. Then, the proposed method of Doppler velocity estimation is evaluated. In computer simulations, accuracy of the determined Doppler velocity and distance were demonstrated within ±8.471mm/s and ±13.87μm. In experiments, Doppler velocities of the motorized stage could be determined within ±27.9mm/s. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Simultaneous measurements with 3D PIV and Acoustic Doppler Velocity Profiler

    NARCIS (Netherlands)

    Blanckaert, K.J.F.; McLelland, S.J.

    2009-01-01

    Simultaneous velocity measurements were taken using Particle Image Velocimetry (PIV) and an Acoustic Doppler Velocity Profiler (ADVP) in a sharp open-channel bend with an immobile gravel bed. The PIV measures 3D velocity vectors in a vertical plane (~40cm x 20cm) at a frequency of 7.5 Hz, whereas

  7. 3D velocity measurement by a single camera using Doppler phase-shifting holography

    International Nuclear Information System (INIS)

    Ninomiya, Nao; Kubo, Yamato; Barada, Daisuke; Kiire, Tomohiro

    2016-01-01

    In order to understand the details of the flow field in micro- and nano-fluidic devices, it is necessary to measure the 3D velocities under a microscopy. Thus, there is a strong need for the development of a new measuring technique for 3D velocity by a single camera. One solution is the use of holography, but it is well known that the accuracy in the depth direction is very poor for the commonly used in-line holography. At present, the Doppler phase-shifting holography is used for the 3D measurement of an object. This method extracts the signal of a fixed frequency caused by the Doppler beat between the object light and the reference light. It can measure the 3D shape precisely. Here, the frequency of the Doppler beat is determined by the velocity difference between the object light and the reference light. This implies that the velocity of an object can be calculated by the Doppler frequency. In this study, a Japanese 5 yen coin was traversed at a constant speed and its holography has been observed by a high-speed camera. By extracting only the first order diffraction signal at the Doppler frequency, a precise measurement of the shape and the position of a 5 yen coin has been achieved. At the same time, the longitudinal velocity of a 5 yen coin can be measured by the Doppler frequency. Furthermore, the lateral velocities are obtained by particle image velocimetry (PIV) method. A 5 yen coin has been traversed at different angles and its shapes and the 3D velocities have been measured accurately. This method can be applied to the particle flows in the micro- or nano-devices, and the 3D velocities will be measured under microscopes. (paper)

  8. Measuring Velocity and Acceleration Using Doppler Shift of a ...

    Indian Academy of Sciences (India)

    . 1. Introduction ... Doppler effect demands that time is universal, and not relative. We emphasize then that, we do not ..... the material ejected by the prime mover at a later time and is being obstructed by material the jet is ramming into. Then, let ...

  9. Current Measurements Using Doppler Range Velocities over the Estuary of Yangtze River

    Science.gov (United States)

    Li, Huimin; Wang, Yunhua; Zhang, Yanmin

    2014-11-01

    Measurements of oceanic surface current using range velocity over Estuary of Yangtze River are examined based on range Doppler velocity retrieved from Advanced Synthetic Aperture Radar(ASAR). Sign Doppler Estimator (SDE) is employed to calculate Doppler Centroid with ASAR Imaging mode datasets. Both non- and geophysical errors are corrected to acquire more realistic surface current. In the process of corrections for geophysical errors, contributions of wind are removed utilizing phase velocity of wind-generated waves (Bragg resonant waves). In general, magnitude of retrieved current is approximately 1m/s, which is in reasonable concordance with long-term hydrological observations. Maps of ASAR-derived oceanic surface current seem to capture the synoptic characteristics of this Estuary. Assessments using tide table are implemented, which depict a potential in obtaining high precision currents. The derived results are encouraging and manifest that SAR does offer a valuable means to retrieve high-resolution current especially over coastal areas.

  10. Coherent Doppler Lidar for Measuring Velocity and Altitude of Space and Arial Vehicles

    Science.gov (United States)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn D.; Petway, Larry; Barnes, Bruce W.

    2016-01-01

    A coherent Doppler lidar has been developed to support future NASA missions to planetary bodies. The lidar transmits three laser beams and measures line-of-sight range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. Accurate altitude and velocity vector data, derived from the line-of-sight measurements, enables the landing vehicle to precisely navigate from several kilometers above the ground to the designated location and execute a gentle touchdown. The same lidar sensor can also benefit terrestrial applications that cannot rely on GPS or require surface-relative altitude and velocity data.

  11. Note: Reflection-type micro multipoint laser Doppler velocimeter for measuring velocity distributions in blood vessels.

    Science.gov (United States)

    Ishida, H; Kobayashi, D; Shirakawa, H; Andoh, T; Akiguchi, S; Wakisaka, T; Ishizuka, M; Hachiga, T

    2011-07-01

    We have developed a laser Doppler velocimeter (LDV) for measuring velocity distributions in blood vessels. We converted a transmission-based LDV into a reflection-based LDV to make it suitable for clinical applications. The velocity distribution image of a serpentine flow channel obtained could be qualitatively explained by the numerical results. Finally, we evaluated the system by using it to measure injection of blood into a glass tube by a syringe pump. The results obtained demonstrate that erythrocytes can be used as seeding particles for the reflection-type micro multipoint LDV. The results obtained are useful as basic data for clinical applications.

  12. TU-A-9A-02: Analysis of Variations in Clinical Doppler Ultrasound Peak Velocity Measurements

    International Nuclear Information System (INIS)

    Zhang, Y; Stekel, S; Tradup, D; Hangiandreou, N

    2014-01-01

    Purpose: Doppler ultrasound (US) peak velocity (Vmax) measurements show considerable variations due to intrinsic spectral broadening with different scanning techniques, machines and manufacturers. We developed a semi-automated Vmax estimation method and used this method to investigate the performance of a US system for clinical Doppler Vmax measurement. Methods: Semi-automated Vmax is defined as the velocity at which the computed mean spectral profile falls to within 1 background standard deviation of the background mean. GE LOGIQ E9 system with 9L and ML6-15 probes were studied with steady flow (5.3 – 12.5 ml/s) in a Gammex OPTIMIZER 1425A phantom. All Doppler spectra were acquired by 1 operator at the distal end of 5 mm angular tube using a modified clinical carotid artery protocol. Repeatability and variation of Vmax to scanning parameters and probes were analyzed and reported as percentage, i.e. (max-min)/mean. Results: Vmax estimation had good repeatability (3.1% over 6 days for 9L, and 3.6% for ML6-15). For 9L probe, varying gain, compression, scale, SV depth and length, and frequency had minimal impact on Vmax (all variations less than 4.0%). Beam steering had slightly higher influence (largest variations across flow rates were 4.9% for 9L and 6.9% for ML6-15). For both probes, Doppler angle had the greatest effect on Vmax. Percentage increase of Vmax was largely independent of actual flow rates. For Doppler angle varied from 30 to 60°, Vmax increased 24% for 9L, and 20% for ML6-15. Vmax measured by ML6-15 were lower than that by 9L at each Doppler angle with differences less than 5%. Conclusion: The proposed Vmax estimation method is shown to be a useful tool to evaluate clinical Doppler US system performance. For the tested system and probes, Doppler angle had largest impact in measured Vmax

  13. Measurement of fast-changing low velocities by photonic Doppler velocimetry.

    Science.gov (United States)

    Song, Hongwei; Wu, Xianqian; Huang, Chenguang; Wei, Yangpeng; Wang, Xi

    2012-07-01

    Despite the increasing popularity of photonic Doppler velocimetry (PDV) in shock wave experiments, its capability of capturing low particle velocities while changing rapidly is still questionable. The paper discusses the performance of short time Fourier transform (STFT) and continuous wavelet transform (CWT) in processing fringe signals of fast-changing low velocities measured by PDV. Two typical experiments are carried out to evaluate the performance. In the laser shock peening test, the CWT gives a better interpretation to the free surface velocity history, where the elastic precursor, main plastic wave, and elastic release wave can be clearly identified. The velocities of stress waves, Hugoniot elastic limit, and the amplitude of shock pressure induced by laser can be obtained from the measurement. In the Kolsky-bar based tests, both methods show validity of processing the longitudinal velocity signal of incident bar, whereas CWT improperly interprets the radial velocity of the shocked sample at the beginning period, indicating the sensitiveness of the CWT to the background noise. STFT is relatively robust in extracting waveforms of low signal-to-noise ratio. Data processing method greatly affects the temporal resolution and velocity resolution of a given fringe signal, usually CWT demonstrates a better local temporal resolution and velocity resolution, due to its adaptability to the local frequency, also due to the finer time-frequency product according to the uncertainty principle.

  14. Simultaneous measurement of acoustic and streaming velocities in a standing wave using laser Doppler anemometry

    Science.gov (United States)

    Thompson, Michael W.; Atchley, Anthony A.

    2005-04-01

    Laser Doppler anemometry (LDA) with burst spectrum analysis (BSA) is used to study the acoustic streaming generated in a cylindrical standing-wave resonator filled with air. The air column is driven sinusoidally at a frequency of approximately 310 Hz and the resultant acoustic-velocity amplitudes are less than 1.3 m/s at the velocity antinodes. The axial component of fluid velocity is measured along the resonator axis, across the diameter, and as a function of acoustic amplitude. The velocity signals are postprocessed using the Fourier averaging method [Sonnenberger et al., Exp. Fluids 28, 217-224 (2000)]. Equations are derived for determining the uncertainties in the resultant Fourier coefficients. The time-averaged velocity-signal components are seen to be contaminated by significant errors due to the LDA/BSA system. In order to avoid these errors, the Lagrangian streaming velocities are determined using the time-harmonic signal components and the arrival times of the velocity samples. The observed Lagrangian streaming velocities are consistent with Rott's theory [N. Rott, Z. Angew. Math. Phys. 25, 417-421 (1974)], indicating that the dependence of viscosity on temperature is important. The onset of streaming is observed to occur within approximately 5 s after switching on the acoustic field. .

  15. Improvement of vertical velocity statistics measured by a Doppler lidar through comparison with sonic anemometer observations

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, Timothy A.; Newman, Jennifer F.; Klein, Petra M.; Chilson, Phillip B.; Wharton, Sonia

    2016-01-01

    Since turbulence measurements from Doppler lidars are being increasingly used within wind energy and boundary-layer meteorology, it is important to assess and improve the accuracy of these observations. While turbulent quantities are measured by Doppler lidars in several different ways, the simplest and most frequently used statistic is vertical velocity variance (w'2) from zenith stares. However, the competing effects of signal noise and resolution volume limitations, which respectively increase and decrease w'2, reduce the accuracy of these measurements. Herein, an established method that utilises the autocovariance of the signal to remove noise is evaluated and its skill in correcting for volume-averaging effects in the calculation of w'2 is also assessed. Additionally, this autocovariance technique is further refined by defining the amount of lag time to use for the most accurate estimates of w'2. Through comparison of observations from two Doppler lidars and sonic anemometers on a 300 m tower, the autocovariance technique is shown to generally improve estimates of w'2. After the autocovariance technique is applied, values of w'2 from the Doppler lidars are generally in close agreement (R2≈0.95-0.98) with those calculated from sonic anemometer measurements.

  16. Navigation Doppler Lidar Sensor for Precision Altitude and Vector Velocity Measurements Flight Test Results

    Science.gov (United States)

    Pierrottet, Diego F.; Lockhard, George; Amzajerdian, Farzin; Petway, Larry B.; Barnes, Bruce; Hines, Glenn D.

    2011-01-01

    An all fiber Navigation Doppler Lidar (NDL) system is under development at NASA Langley Research Center (LaRC) for precision descent and landing applications on planetary bodies. The sensor produces high resolution line of sight range, altitude above ground, ground relative attitude, and high precision velocity vector measurements. Previous helicopter flight test results demonstrated the NDL measurement concepts, including measurement precision, accuracies, and operational range. This paper discusses the results obtained from a recent campaign to test the improved sensor hardware, and various signal processing algorithms applicable to real-time processing. The NDL was mounted in an instrumentation pod aboard an Erickson Air-Crane helicopter and flown over vegetation free terrain. The sensor was one of several sensors tested in this field test by NASA?s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project.

  17. Capillary blood cell velocity in periulcerous regions of the lower leg measured by laser Doppler anemometry.

    Science.gov (United States)

    Stücker, Markus; Huntermann, Christina; Bechara, Falk Georges; Hoffmann, Klaus; Altmeyer, Peter

    2004-08-01

    The capillary blood flow of the nailfold can be measured by means of modern non-invasive techniques like the videocapillary microscope in vivo. To quantify the capillary blood cell velocity, apart from the nailfold capillaries, we used a new technique, the so-called laser Doppler anemometry (LDA). The present study investigated how far laser Doppler fluxmetry (LDF), transcutaneous partial pressure of oxygen (tcpO2), and LDA are capable of quantifying differences of cutaneous microcirculation between patients with leg ulcera and a healthy control group. The effects of intravenous prostaglandin E1 and pentoxifylline were also investigated. Ten patients with venous leg ulcers and 10 patients with mixed venous/arterial ulcers were investigated with LDF, tcpO2, and LDA before and after injection of prostaglandin E1 and pentoxifylline. We measured the resting capillary blood cell velocity (rCBV), the maximum hyperemia, and the time to peak capillary blood cell velocity (tpCBV) during hyperemia after 4 min of suprasystolic occlusion and compared them with the results of a contol group of 20 patients. Laser Doppler flow was increased in all patients during resting period, whereas the tcpO2 was significantly decreased. LDF did not show an extension of tpCBV during reactive hyperemia after suprasystolic occlusion compared to the control group (73.6+/-31.1 vs. 164.1+/-52.5 s, P=0.003). TcpO2 revealed significantly decreased tpCBV in patients with venous and mixed venous/arterial ulcers (90.1+/-61.7 vs. 162.7+/-65.5 s, P0.8). After application of prostaglandin E1, LDA revealed a significant increase of erythrocyte velocity (0.5+/-0.18 to 0.74+/-0.28 mm/s [P=0,01]), whereas pentoxifylline had no significant effect. Capillary density increased significantly after application of prostaglandin E1 (5,1+/-2.7/mm2 to 8.9+/-3/mm2 [P=0.001]) and pentoxifylline (5.3+/- 1.8/mm2 to 8+/-2.1/mm2 [P=0.006]). The LDA is an important additional investigation tool for cutaneous microcirculation.

  18. Comparison of index velocity measurements made with a horizontal acoustic Doppler current profiler

    Science.gov (United States)

    Jackson, P. Ryan; Johnson, Kevin K.; Duncker, James J.

    2012-01-01

    The State of Illinois' annual withdrawal from Lake Michigan is limited by a U.S. Supreme Court decree, and the U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Every 5 years, a technical review committee consisting of practicing engineers and academics is convened to review the U.S. Geological Survey's streamgage practices in the CSSC near Lemont, Illinois. The sixth technical review committee raised a number of questions concerning the flows and streamgage practices in the CSSC near Lemont and this report provides answers to many of those questions. In addition, it is the purpose of this report to examine the index velocity meters in use at Lemont and determine whether the acoustic velocity meter (AVM), which is now the primary index velocity meter, can be replaced by the horizontal acoustic Doppler current profiler (H-ADCP), which is currently the backup meter. Application of the AVM and H-ADCP to index velocity measurements in the CSSC near Lemont, Illinois, has produced good ratings to date. The site is well suited to index velocity measurements in spite of the large range of velocities and highly unsteady flows at the site. Flow variability arises from a range of sources: operation of the waterway through control structures, lockage-generated disturbances, commercial and recreational traffic, industrial withdrawals and discharges, natural inflows, seiches, and storm events. The influences of these factors on the index velocity measurements at Lemont is examined in detail in this report. Results of detailed data comparisons and flow analyses show that use of bank-mounted instrumentation such as the AVM and H-ADCP appears to be the best option for index velocity measurement in the CSSC near Lemont. Comparison of the rating curves for the AVM and H-ADCP demonstrates

  19. Particle Filter Based Fault-tolerant ROV Navigation using Hydro-acoustic Position and Doppler Velocity Measurements

    DEFF Research Database (Denmark)

    Zhao, Bo; Blanke, Mogens; Skjetne, Roger

    2012-01-01

    This paper presents a fault tolerant navigation system for a remotely operated vehicle (ROV). The navigation system uses hydro-acoustic position reference (HPR) and Doppler velocity log (DVL) measurements to achieve an integrated navigation. The fault tolerant functionality is based on a modied...... the ROV kinematic states, even when sensor failures appear frequently....

  20. Fiber-optic laser-Doppler anemometer microscope developed for the measurement of microvascular red cell velocity.

    Science.gov (United States)

    Seki, J

    1990-11-01

    A fiber-optic laser-Doppler anemometer microscope (FLDAM) was developed and its applicability to the study of microvascular blood flow was examined by measuring red cell velocities in vivo and in vitro. The FLDAM consists of an intravital microscope equipped with a fringe-mode back-scatter LDA. A data processing method of the Doppler signal which used frequency averaging over the entire frequency range of the power spectrum was developed. Spatial resolution of the FLDAM varied from 17 to 200 microns with 50X to 5X objectives. In vitro experiments showed that the red cell velocity obtained by the FLDAM was equal to the mean flow velocity, within the accuracy of the measurements, for tube diameters from 35 to 100 microns, mean velocity from 0.7 to 17 mm/sec, and feed hematocrit of 20%, when 10X or 20X objectives were used. In vivo red cell velocity measurements conducted with the FLDAM in microvessels of rat mesentery with diameters from 6.5 to 49 microns showed that red cell velocities were about 1/1.6 times smaller than those obtained by the two-slit technique, which also suggests that the velocity obtained by the FLDAM corresponds to the mean flow velocity. This relationship was also established from theoretical considerations for the case where the FLDAM sampling volume covers the entire vessel cross section. Furthermore the frequency response of the FLDAM was established to be about 20 Hz, which was sufficient for measurement of pulsatile velocities in rat mesenteric microvessels.

  1. Modeling solar oscillation power spectra. II. Parametric model of spectral lines observed in Doppler-velocity measurements

    International Nuclear Information System (INIS)

    Vorontsov, Sergei V.; Jefferies, Stuart M.

    2013-01-01

    We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and damping as these mechanisms remain poorly understood. The model is targeted at the accurate fitting of power spectra coming from Doppler-velocity measurements and uses an adaptive response function that accounts for both the vertical and horizontal components of the velocity field on the solar surface and for possible instrumental and observational distortions. The model is continuous in frequency, can easily be adapted to intensity measurements, and extends naturally to the analysis of high-frequency pseudomodes (interference peaks at frequencies above the atmospheric acoustic cutoff).

  2. Modeling solar oscillation power spectra. II. Parametric model of spectral lines observed in Doppler-velocity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vorontsov, Sergei V. [Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Jefferies, Stuart M., E-mail: S.V.Vorontsov@qmul.ac.uk, E-mail: stuartj@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii, 34 Ohia Ku Street, Pukalani, HI 96768 (United States)

    2013-11-20

    We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and damping as these mechanisms remain poorly understood. The model is targeted at the accurate fitting of power spectra coming from Doppler-velocity measurements and uses an adaptive response function that accounts for both the vertical and horizontal components of the velocity field on the solar surface and for possible instrumental and observational distortions. The model is continuous in frequency, can easily be adapted to intensity measurements, and extends naturally to the analysis of high-frequency pseudomodes (interference peaks at frequencies above the atmospheric acoustic cutoff).

  3. Two-component laser Doppler anemometer for measurement of velocity and turbulent shear stress near prosthetic heart valves.

    Science.gov (United States)

    Woo, Y R; Yoganathan, A P

    1985-01-01

    The velocity and turbulent shear stress measured in the immediate vicinity of prosthetic heart valves play a vital role in the design and evaluation of these devices. In the past hot wire/film and one-component laser Doppler anemometer (LDA) systems were used extensively to obtain these measurements. Hot wire/film anemometers, however, have some serious disadvantages, including the inability to measure the direction of the flow, the disturbance of the flow field caused by the probe, and the need for frequent calibration. One-component LDA systems do not have these problems, but they cannot measure turbulent shear stresses directly. Since these measurements are essential and are not available in the open literature, a two-component LDA system for measuring velocity and turbulent shear stress fields under pulsatile flow conditions was assembled under an FDA contract. The experimental methods used to create an in vitro data base of velocity and turbulent shear stress fields in the immediate vicinity of prosthetic heart valves of various designs in current clinical use are also discussed.

  4. Comparison of velocity measurements by high temperature anemometer and laser-doppler anemometer with results of CFD-simulation

    Directory of Open Access Journals (Sweden)

    Zimmel M.

    2002-01-01

    Full Text Available In the present work, results of gas velocity measurements with a newly developed vane anemometer (HTA - High Tem per a ture Anemometer are compared with re sults of measurements obtained from Laser-Doppler Anemometer (LDA. The measurements were carried out at the combustion test rig of ALSTOM Combustion Services Ltd. in Derby/UK, and demonstrate the usability and accuracy of the HTA under severe conditions. The test rig was provided with a triple register low NOx coal burner firing pulverised Colombian blended coal at a constant thermal load of 30 MW. Although the environment was both very hot (up to 1350 °C and dust laden, the vane anemometer worked with an accuracy comparable to the reference LDA measurement. Since the anemometer represents a relatively simple to use and low cost option compared with LDA, it is seen as aviable alternative for gas velocity measurements in difficult environments. The measurement results are also demonstrated to compare favourably with the results from CFD calculations of the flow in the combustion chamber of the test rig.

  5. Doppler spectroscopic measurements of sheath ion velocities in radio-frequency plasmas

    International Nuclear Information System (INIS)

    Woodcock, B.K.; Busby, J.R.; Freegarde, T.G.; Hancock, G.

    1997-01-01

    We have measured the distributions of N 2 + ion velocity components parallel and perpendicular to the electrode in the sheath of a radio-frequency nitrogen reactive ion etching discharge, using pulsed laser-induced fluorescence. Parallel to the electrode, the ions have throughout a thermal distribution that is found to be consistent with the rotational temperature of 355 K. In the perpendicular direction, we see clearly the acceleration of the ions towards the electrode, and our results agree well with theoretical predictions although an unexpected peak of unaccelerated ions persists. We have also determined the absolute ion concentrations in the sheath, which we have calibrated by analyzing the decay in laser-induced fluorescence in the plasma bulk after discharge extinction. At 20 mTorr, the bulk concentration of 1.0x10 10 cm -3 falls to around 2x10 8 cm -3 at 2 mm from the electrode. copyright 1997 American Institute of Physics

  6. Measurement of Instantaneous Velocities from a Fluidically Controlled Nozzle Using a Laser Doppler Velocimeter

    Science.gov (United States)

    1976-09-01

    unscattered and therefore undergoes no frequency shift. As a result, the photo- detector will have an output current composed of a DC term from the...alternatingly light and dark bands, they scatter light only while in the light bands, generating a current at the photodetector. The current fluctuation...34 interferential Doppler" [2] is shown in Figure 6. a. A single laser beam is directed into the flow, scattering with different intensities in all directions. 15

  7. Doppler Velocity Signatures of Idealized Elliptical Vortices

    Directory of Open Access Journals (Sweden)

    Wen-Chau Lee

    2006-01-01

    Full Text Available Doppler radar observations have revealed a class of atmospheric vortices (tropical cyclones, tornadoes, dust devils that possess elliptical radar reflectivity signatures. One famous example is Typhoon Herb (1996 that maintained its elliptical reflectivity structure over a 40-hour period. Theoretical work and dual-Doppler analyses of observed tropical cyclones have suggested two physical mechanisms that can explain the formation of two types of elliptical vortices observed in nature, namely, the combination of a circular vortex with either a wavenumber two vortex Rossby wave or a deformation field. The characteristics of these two types of elliptical vortices and their corresponding Doppler velocity signatures have not been previously examined.

  8. Doppler Lidar Vertical Velocity Statistics Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosis from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.

  9. Coronary Flow Velocity Reserve Assessed by Transthoracic Doppler

    DEFF Research Database (Denmark)

    Michelsen, Marie M; Peña, Adam; Mygind, Naja D

    2016-01-01

    BACKGROUND: Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography is a noninvasive measure of microvascular function, but it has not achieved widespread use, mainly because of concerns of validity and feasibility. The aim of this study was to describe the feasib...

  10. Absolute calibration of Doppler coherence imaging velocity images

    Science.gov (United States)

    Samuell, C. M.; Allen, S. L.; Meyer, W. H.; Howard, J.

    2017-08-01

    A new technique has been developed for absolutely calibrating a Doppler Coherence Imaging Spectroscopy interferometer for measuring plasma ion and neutral velocities. An optical model of the interferometer is used to generate zero-velocity reference images for the plasma spectral line of interest from a calibration source some spectral distance away. Validation of this technique using a tunable diode laser demonstrated an accuracy better than 0.2 km/s over an extrapolation range of 3.5 nm; a two order of magnitude improvement over linear approaches. While a well-characterized and very stable interferometer is required, this technique opens up the possibility of calibrated velocity measurements in difficult viewing geometries and for complex spectral line-shapes.

  11. Application of acoustic-Doppler current profiler and expendable bathythermograph measurements to the study of the velocity structure and transport of the Gulf Stream

    Science.gov (United States)

    Joyce, T. M.; Dunworth, J. A.; Schubert, D. M.; Stalcup, M. C.; Barbour, R. L.

    1988-01-01

    The degree to which Acoustic-Doppler Current Profiler (ADCP) and expendable bathythermograph (XBT) data can provide quantitative measurements of the velocity structure and transport of the Gulf Stream is addressed. An algorithm is used to generate salinity from temperature and depth using an historical Temperature/Salinity relation for the NW Atlantic. Results have been simulated using CTD data and comparing real and pseudo salinity files. Errors are typically less than 2 dynamic cm for the upper 800 m out of a total signal of 80 cm (across the Gulf Stream). When combined with ADCP data for a near-surface reference velocity, transport errors in isopycnal layers are less than about 1 Sv (10 to the 6th power cu m/s), as is the difference in total transport for the upper 800 m between real and pseudo data. The method is capable of measuring the real variability of the Gulf Stream, and when combined with altimeter data, can provide estimates of the geoid slope with oceanic errors of a few parts in 10 to the 8th power over horizontal scales of 500 km.

  12. Blood flow velocity in migraine attacks - a transcranial Doppler study

    International Nuclear Information System (INIS)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D.

    1991-01-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs

  13. Laser Doppler measurements in two-phase flows

    International Nuclear Information System (INIS)

    Durst, F.; Zare, M.

    1976-01-01

    Basic theory for laser-Doppler velocity measurements of large reflecting or refracting surfaces is provided. It is shown that the Doppler-signals contain information of the velocity and size of the large bodies, and relationships for transforming velocity and radius of curvature of moving spheres are presented. Preliminary experiments verified the analytical findings and demonstrated the applicability of the method to some two-phase flows

  14. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    1996-08-01

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  15. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  16. Frequency Diversity Technique for Space-borne Radar Doppler Measurements

    Data.gov (United States)

    National Aeronautics and Space Administration — Doppler velocity measurement has been challenging for radars onboard fast moving platforms (such as spacecrafts) or radars with rapid scanning antennas due to the...

  17. Influence of immune-mediated hemolytic anemia on flow velocities in the portal vein and caudal vena cava measured by use of pulsed-wave Doppler ultrasonography in dogs.

    Science.gov (United States)

    Smith, Rachel Policelli; Koenigshof, Amy M; Smith, Daniel J; Strom, Phillip R; Nelson, Nathan C

    2018-05-01

    OBJECTIVE To compare blood flow velocities of the portal vein (PV) and caudal vena cava (CVC) measured by use of pulsed-wave Doppler ultrasonography in clinically normal dogs and dogs with primary immune-mediated hemolytic anemia (IMHA). ANIMALS 11 client-owned dogs admitted to a veterinary teaching hospital for management of primary IMHA and 21 staff- or student-owned clinically normal dogs. PROCEDURES Flow velocities in the PV and CVC at the porta hepatis were evaluated in conscious unsedated dogs with concurrent ECG monitoring; evaluations were performed before dogs with IMHA received heparin or blood transfusions. Three measurements of peak velocity at end expiration were obtained for each vessel, and the mean was calculated. Results were compared between IMHA and control groups. RESULTS Mean ± SD blood flow velocity in the CVC differed between control (63.0 ± 18.6 cm/s) and IMHA (104 ± 36.9 cm/s) groups. Variance in dogs with IMHA was significantly greater than that for the clinically normal dogs. No significant difference in blood flow velocity in the PV was detected between IMHA and control dogs. CONCLUSIONS AND CLINICAL RELEVANCE Higher blood flow velocities were detected by use of pulsed-wave Doppler ultrasonography in the CVC of dogs with naturally occurring IMHA and may be used to predict anemia in patients suspected of having IMHA.

  18. Determination of relationship between Rayleigh wave velocity and stress with laser Doppler velocimeter

    Science.gov (United States)

    He, Lingfeng; Kobayashi, Shoichi

    2002-05-01

    A non-contact measurement technique of Rayleigh wave velocity is proposed. In the non-contact measurement system, a laser Doppler velocimeter is used to determine wave motions. With above technique, the relationship between Rayleigh wave velocity and stress for an aluminum alloy 5052 and steel SS400 is determined, and the results are in good agreement with that obtained by contact measurement method.

  19. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

    Singh, Upendra N.; Emmitt, George D.; Yu, Jirong; Kavaya, Michael J.

    2010-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. The transmitter portion of the transceiver employs the high-pulse-energy, Ho:Tm:LuLiF, partially conductively cooled laser technology developed at NASA Langley. The transceiver is capable of 250 mJ pulses at 10 Hz. It is very similar to the technology envisioned for coherent Doppler lidar wind measurements from Earth and Mars orbit. The transceiver is coupled to the large optics and data acquisition system in the NASA Langley VALIDAR mobile trailer. The large optics consists of a 15-cm off-axis beam expanding telescope, and a full-hemispheric scanner. Vertical and horizontal vector winds are measured, as well as relative backscatter. The data acquisition system employs frequency domain velocity estimation and pulse accumulation. It permits real-time display of the processed winds and archival of all data. This lidar system was recently deployed at Howard University facility in Beltsville, Mary-land, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other sensors will be presented. A simulation and data product for wind measurement at Venus will be presented.

  20. Error analysis of ultrasonic tissue doppler velocity estimation techniques for quantification of velocity and strain.

    Science.gov (United States)

    Bennett, Michael J; McLaughlin, Steve; Anderson, Tom; McDicken, W Norman

    2007-01-01

    Recent work in the field of Doppler tissue imaging has focused mainly on the quantification of results involving the use of techniques of strain and strain-rate imaging. These results are based on measuring a velocity gradient between two points, a known distance apart, in the region-of-interest. Although many recent publications have demonstrated the potential of this technique in clinical terms, the method still suffers from low repeatability. The work presented here demonstrates, through the use of a rotating phantom arrangement and a custom developed single element ultrasound system, that this is a consequence of the fundamental accuracy of the technique used to estimate the original velocities. Results are presented comparing the performance of the conventional Kasai autocorrelation velocity estimator with those obtained using time domain cross-correlation and the complex cross-correlation model based estimator. The results demonstrate that the complex cross-correlation model based technique is able to offer lower standard deviations of the velocity gradient estimations compared with the Kasai algorithm.

  1. Transcranial Doppler velocities in a large, healthy population.

    Science.gov (United States)

    Tegeler, Charles H; Crutchfield, Kevin; Katsnelson, Michael; Kim, Jongyeol; Tang, Rong; Passmore Griffin, Leah; Rundek, Tanja; Evans, Greg

    2013-07-01

    Transcranial Doppler (TCD) ultrasonography has been extensively used in the evaluation and management of patients with cerebrovascular disease since the clinical application was first described in 1982 by Aaslid and colleagues TCD is a painless, safe, and noninvasive diagnostic technique that measures blood flow velocity in various cerebral arteries. Numerous commercially available TCD devices are currently approved for use worldwide, and TCD is recognized to have an established clinical value for a variety of clinical indications and settings. Although many studies have reported normal values, there have been few recently, and none to include a large cohort of healthy subjects across age, race, and gender. As more objective, automated processes are being developed to assist with the performance and interpretation of TCD studies, and with the potential to easily compare results against a reference population, it is important to define stable normal values and variances across age, race, and gender, with clear understanding of variability of the measurements, as well as the yield from various anatomic segments. To define normal TCD values in a healthy population, we enrolled 364 healthy subjects, ages 18-80 years, to have a complete, nonimaging TCD examination. Subjects with known or suspected cerebrovascular disorders, systemic disorders with cerebrovascular effects, as well as those with known hypertension, diabetes, stroke, coronary artery disease, or myocardial infarction, were excluded. Self-reported ethnicity, handedness, BP, and BMI were recorded. A complete TCD examination was performed by a single experienced sonographer, using a single gate nonimaging TCD device, and a standardized protocol to interrogate up to 23 arterial segments. Individual Doppler spectra were saved for each segment, with velocity and pulsatility index (PI) values calculated using the instrument's automated waveform tracking function. Descriptive analysis was done to determine the mean

  2. Doppler term in the galaxy two-point correlation function: Wide-angle, velocity, Doppler lensing and cosmic acceleration effects

    Science.gov (United States)

    Raccanelli, Alvise; Bertacca, Daniele; Jeong, Donghui; Neyrinck, Mark C.; Szalay, Alexander S.

    2018-03-01

    We study the parity-odd part (that we shall call Doppler term) of the linear galaxy two-point correlation function that arises from wide-angle, velocity, Doppler lensing and cosmic acceleration effects. As it is important at low redshift and at large angular separations, the Doppler term is usually neglected in the current generation of galaxy surveys. For future wide-angle galaxy surveys, however, we show that the Doppler term must be included. The effect of these terms is dominated by the magnification due to relativistic aberration effects and the slope of the galaxy redshift distribution and it generally mimics the effect of the local type primordial non-Gaussianity with the effective nonlinearity parameter fNLeff of a few; we show that this would affect forecasts on measurements of fNL at low-redshift. Our results show that a survey at low redshift with large number density over a wide area of the sky could detect the Doppler term with a signal-to-noise ratio of ∼ 1 - 20, depending on survey specifications.

  3. Blood flow velocity imaging of malignant melanoma by micro multipoint laser Doppler velocimetry

    Science.gov (United States)

    Ishida, H.; Andoh, T.; Akiguchi, S.; Shirakawa, H.; Kobayashi, D.; Kuraishi, Y.; Hachiga, T.

    2010-09-01

    We have developed a laser Doppler velocimeter to measure blood flow, the micromultipoint laser Doppler velocimeter (μ-MLDV). This equipment can measure absolute velocity and, based on this, can display the course of blood vessels. In this study, we attempted to perform blood flow velocity imaging of malignant melanoma transplanted to the mouse ear. We found that blood flow velocity of the formed blood vessels originating in the melanoma was much greater than that of the capillary vessels in normal skin. Furthermore, the form of the tumor was clearly visible from the blood flow velocity image. These experimental results suggest that μ-MLDV has potential as a diagnostic method for distinguishing benign nevi from malignant melanomas.

  4. Differences between Doppler velocities of ions and neutral atoms in a solar prominence

    Science.gov (United States)

    Anan, T.; Ichimoto, K.; Hillier, A.

    2017-05-01

    Context. In astrophysical systems with partially ionized plasma, the motion of ions is governed by the magnetic field while the neutral particles can only feel the magnetic field's Lorentz force indirectly through collisions with ions. The drift in the velocity between ionized and neutral species plays a key role in modifying important physical processes such as magnetic reconnection, damping of magnetohydrodynamic waves, transport of angular momentum in plasma through the magnetic field, and heating. Aims: This paper aims to investigate the differences between Doppler velocities of calcium ions and neutral hydrogen in a solar prominence to look for velocity differences between the neutral and ionized species. Methods: We simultaneously observed spectra of a prominence over an active region in H I 397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion spectrograph of the Domeless Solar Telescope at Hida observatory. We compared the Doppler velocities, derived from the shift of the peak of the spectral lines presumably emitted from optically-thin plasma. Results: There are instances when the difference in velocities between neutral atoms and ions is significant, for example 1433 events ( 3% of sets of compared profiles) with a difference in velocity between neutral hydrogen atoms and calcium ions greater than 3σ of the measurement error. However, we also found significant differences between the Doppler velocities of two spectral lines emitted from the same species, and the probability density functions of velocity difference between the same species is not significantly different from those between neutral atoms and ions. Conclusions: We interpreted the difference of Doppler velocities as being a result of the motions of different components in the prominence along the line of sight, rather than the decoupling of neutral atoms from plasma. The movie attached to Fig. 1 is available at http://www.aanda.org

  5. Modelling nonstationary Doppler noise in exoplanetary radial velocity data

    Science.gov (United States)

    Baluev, Roman V.

    2015-08-01

    We construct a new class of analytic nonstationary noise models for exoplanetary Doppler data. The observable correlated noise is represented as a convolution of a parent activity process with a given memory function. The model honours the casuality principle, meaning that only past values of the activity may affect the observable value. This model does not approximate detailedly any real stellar activity phenomena, but it becomes mathematically simple, simultaneously satisfying the basic natural principles of physical sensibility and self-consistency.Additionally, we develop a new type of periodograms that can be used to detect periodic modulations in the Doppler noise characteristics, rather than in the observed radial velocity curve itself. We present first results of applying this technique to public Doppler time series available for a set of planet-hosting stars.This work was supported by the Russian Foundation for Basic Research (project No. 14-02-92615 KO_a), the UK Royal Society International Exchange grant IE140055, by the President of Russia grant for young scientists (No. MK-733.2014.2), by the programme of the Presidium of Russian Academy of Sciences P21, and by the Saint Petersburg State University research grant 6.37.341.2015.

  6. Ratio of left ventricular peak E-wave velocity to flow propagation velocity assessed by color M-mode Doppler echocardiography in first myocardial infarction

    DEFF Research Database (Denmark)

    Møller, J E; Søndergaard, E; Seward, J B

    2000-01-01

    OBJECTIVES: To determine the ability of the ratio of peak E-wave velocity to flow propagation velocity (E/Vp) measured with color M-mode Doppler echocardiography to predict in-hospital heart failure and cardiac mortality in an unselected consecutive population with first myocardial infarction (MI...

  7. Visualizing flow fields using acoustic Doppler current profilers and the Velocity Mapping Toolbox

    Science.gov (United States)

    Jackson, P. Ryan

    2013-01-01

    The purpose of this fact sheet is to provide examples of how the U.S. Geological Survey is using acoustic Doppler current profilers for much more than routine discharge measurements. These instruments are capable of mapping complex three-dimensional flow fields within rivers, lakes, and estuaries. Using the Velocity Mapping Toolbox to process the ADCP data allows detailed visualization of the data, providing valuable information for a range of studies and applications.

  8. Doppler coefficient measurements in Zebra Core 5

    International Nuclear Information System (INIS)

    Baker, A.R.; Wheeler, R.C.

    1965-11-01

    Measurements using a central hot loop in Zebra Core 5 are described. Results are given for the Doppler coefficients found in a number of assemblies with PuO 2 and 16% PuO 2 /84% depleted UO 2 pins, loaded with different combinations of steel, sodium or void pins. The mixed oxide results are in general about 20% more negative than was calculated using the FD2 data set, but agreement is good if the plutonium contributions in the calculations are omitted. The small positive Doppler coefficient calculated for Pu239 was not observed, and two measurements indicated instead a small negative effect. The Doppler effect in the mixed oxide systems was found to vary approximately as 1/T. The results from the empty loop and non-fissile assemblies indicate either a small negative Doppler effect in steel or alternatively the presence of an unexplained expansion effect. (author)

  9. Power spectral density of velocity fluctuations estimated from phase Doppler data

    Directory of Open Access Journals (Sweden)

    Jicha Miroslav

    2012-04-01

    Full Text Available Laser Doppler Anemometry (LDA and its modifications such as PhaseDoppler Particle Anemometry (P/DPA is point-wise method for optical nonintrusive measurement of particle velocity with high data rate. Conversion of the LDA velocity data from temporal to frequency domain – calculation of power spectral density (PSD of velocity fluctuations, is a non trivial task due to nonequidistant data sampling in time. We briefly discuss possibilities for the PSD estimation and specify limitations caused by seeding density and other factors of the flow and LDA setup. Arbitrary results of LDA measurements are compared with corresponding Hot Wire Anemometry (HWA data in the frequency domain. Slot correlation (SC method implemented in software program Kern by Nobach (2006 is used for the PSD estimation. Influence of several input parameters on resulting PSDs is described. Optimum setup of the software for our data of particle-laden air flow in realistic human airway model is documented. Typical character of the flow is described using PSD plots of velocity fluctuations with comments on specific properties of the flow. Some recommendations for improvements of future experiments to acquire better PSD results are given.

  10. Comparison of blood flow velocity through the internal carotid artery based on Doppler ultrasound and numerical simulation

    International Nuclear Information System (INIS)

    Hassani-Ardekani, Hajar; Ghalichi, Farzan; Niroomand-Oscuii, Hanieh; Farhoudi, Mehdi; Tarzmani, Mohammad K.

    2012-01-01

    Doppler ultrasound is a usual non-invasive method to estimate the stenosis percentage in large arteries such as carotid by measuring maximum velocity of blood flow. Based on clinical investigations, because of vessel wall motions, Doppler positioning and angle correction, some errors can arise in Doppler results which lead to incorrect diagnosis. The aim of this study was to compare the results of Doppler test and the numerical simulation of blood flow in the same case. For this evaluation, two patients including an 87-year-old man and a 72-year-old woman suffering from stenosis in the internal carotid artery were selected. First, clinical information of each patient such as CT-Angio scan images and Doppler ultrasound results on different locations of the stenosed artery were obtained. Then, the geometries were reconstructed and numerical simulations were carried out using ANSYS software. Results showed that the velocity profile of Doppler test and numerical simulation were in good agreement at the regions of pre-and post-stenosis. However, the value of maximum velocity at the stenotic region had significant differences.

  11. Evaluation of turbulence measurement techniques from a single Doppler lidar

    Science.gov (United States)

    Bonin, Timothy A.; Choukulkar, Aditya; Brewer, W. Alan; Sandberg, Scott P.; Weickmann, Ann M.; Pichugina, Yelena L.; Banta, Robert M.; Oncley, Steven P.; Wolfe, Daniel E.

    2017-08-01

    Measurements of turbulence are essential to understand and quantify the transport and dispersal of heat, moisture, momentum, and trace gases within the planetary boundary layer (PBL). Through the years, various techniques to measure turbulence using Doppler lidar observations have been proposed. However, the accuracy of these measurements has rarely been validated against trusted in situ instrumentation. Herein, data from the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) are used to verify Doppler lidar turbulence profiles through comparison with sonic anemometer measurements. For 17 days at the end of the experiment, a single scanning Doppler lidar continuously cycled through different turbulence measurement strategies: velocity-azimuth display (VAD), six-beam scans, and range-height indicators (RHIs) with a vertical stare.Measurements of turbulence kinetic energy (TKE), turbulence intensity, and stress velocity from these techniques are compared with sonic anemometer measurements at six heights on a 300 m tower. The six-beam technique is found to generally measure turbulence kinetic energy and turbulence intensity the most accurately at all heights (r2 ≈ 0.78), showing little bias in its observations (slope of ≈ 0. 95). Turbulence measurements from the velocity-azimuth display method tended to be biased low near the surface, as large eddies were not captured by the scan. None of the methods evaluated were able to consistently accurately measure the shear velocity (r2 = 0.15-0.17). Each of the scanning strategies assessed had its own strengths and limitations that need to be considered when selecting the method used in future experiments.

  12. A GIS-based Computational Tool for Multidimensional Flow Velocity by Acoustic Doppler Current Profilers

    International Nuclear Information System (INIS)

    Kim, D; Winkler, M; Muste, M

    2015-01-01

    Acoustic Doppler Current Profilers (ADCPs) provide efficient and reliable flow measurements compared to other tools for characteristics of the riverine environments. In addition to originally targeted discharge measurements, ADCPs are increasingly utilized to assess river flow characteristics. The newly developed VMS (Velocity Mapping Software) aims at providing an efficient process for quality assurance, mapping velocity vectors for visualization and facilitating comparison with physical and numerical model results. VMS was designed to provide efficient and smooth work flows for processing groups of transects. The software allows the user to select group of files and subsequently to conduct statistical and graphical quality assurance on the files as a group or individually as appropriate. VMS also enables spatial averaging in horizontal and vertical plane for ADCP data in a single or multiple transects over the same or consecutive cross sections. The analysis results are displayed in numerical and graphical formats. (paper)

  13. Technique for measuring very high surface velocities

    International Nuclear Information System (INIS)

    Maron, Y.

    1977-01-01

    An interferometric technique for measuring displacements of surfaces moving at velocities in the range of a few millimeters per microsecond is presented. The Doppler shift of frequency of light scattered from such surfaces is too high to be detectable by known devices. The present technique is based upon monitoring the signal resulting from the interference between two beams reflected from the surface at different incidence angles. Measurement systems for specularly as well as diffusely reflecting surfaces are described. Light source with very modest temporal coherence delivering about 100 mw power is required. The accuracy of the technique is discussed. (author)

  14. Assessment of the effect of vessel curvature on Doppler measurements in steady flow.

    Science.gov (United States)

    Balbis, S; Guiot, C; Roatta, S; Arina, R; Todros, T

    2004-05-01

    Blood vessel curvature is responsible for the appearance of nonaxial velocity components and for minor changes in the pattern of the axial flow. All the velocity components are expected to contribute to the Doppler signal produced by the ultrasound (US) backscattered by the insonated blood cells, the axial velocity, contributing to the actual volumetric blood flow, and the transverse velocity, causing the recirculating vortices. A detailed, separate analysis of the velocity components is, therefore, mandatory to quantify how vessel curvature can affect results and clinical diagnosis. Both experimental in vitro measures and numerical simulations were performed on a curved tube and the Doppler power spectra so obtained were compared. The satisfactorily agreement of the above spectra shows that the nonaxial velocity components are easily detectable with clinical equipment and that their amplitude, as expected, is not negligible and can bias Doppler measurements and resulting clinical diagnosis.

  15. A Method of Initial Velocity Measurement for Rocket Projectile

    Directory of Open Access Journals (Sweden)

    Zhang Jiancheng

    2017-01-01

    Full Text Available In this paper, a novel method is proposed to measure the initial velocity of the rocket based on STFT (the short-time Fourier transform and the WT (wavelet transform. The radar echo signal processing procedure involves the following steps: sampling process, overlapping windows, wavelet decomposition and reconstruction, computing FFT (Fast Fourier Transform and spectrum analysis, power spectrum peak detection. Then, according to the peak of the detection power spectrum, the corresponding Doppler frequency is obtained. Finally, on the basis of the relationship between Doppler frequency and instantaneous velocity, the V-T curve is drawn in MATLAB to obtain the initial velocity of the rocket muzzle.

  16. Doppler Monte Carlo simulations of light scattering in tissue to support laser-Doppler perfusion measurements

    NARCIS (Netherlands)

    de Mul, F.F.M.; Steenbergen, Wiendelt; Greve, Jan

    1999-01-01

    Doppler Monte Carlo (DMC) simulations of the transport of light through turbid media, e.g., tissue, can be used to predict or to interpret measurements of the blood perfusion of tissue by laser‐Doppler perfusion flowmetry. We describe the physical and mathematical background of Doppler Monte Carlo

  17. De-Dopplerization of Acoustic Measurements

    Science.gov (United States)

    2017-08-10

    spectrum at a chosen resolution through application of digital filter bank . This spectrum is defined at a measurement time, or time of arrival for...calculated with a one-third-octave band filter bank employing Butterworth digital filters. To examine the results of the FOBS correction, Fig. 4...band energy obtained from fractional octave band digital filters generates a de-Dopplerized spectrum without complex resampling algorithms. An

  18. Measuring Turbulence from Moored Acoustic Doppler Velocimeters. A Manual to Quantifying Inflow at Tidal Energy Sites

    Energy Technology Data Exchange (ETDEWEB)

    Kilcher, Levi [National Renewable Energy Lab. (NREL), Golden, CO (United States); Thomson, Jim [Univ. of Washington, Seattle, WA (United States); Talbert, Joe [Univ. of Washington, Seattle, WA (United States); DeKlerk, Alex [Univ. of Washington, Seattle, WA (United States)

    2016-03-01

    This work details a methodology for measuring hub height inflow turbulence using moored acoustic Doppler velocimiters (ADVs). This approach is motivated by the shortcomings of alternatives. For example, remote velocity measurements (i.e., from acoustic Doppler profilers) lack sufficient precision for device simulation, and rigid tower-mounted measurements are very expensive and technically challenging in the tidal environment. Moorings offer a low-cost, site-adaptable and robust deployment platform, and ADVs provide the necessary precision to accurately quantify turbulence.

  19. Using embedded fibers to measure explosive detonation velocities

    Energy Technology Data Exchange (ETDEWEB)

    Podsednik, Jason W.; Parks, Shawn Michael; Navarro, Rudolfo J.

    2012-07-01

    Single-mode fibers were cleverly embedded into fixtures holding nitromethane, and used in conjunction with a photonic Doppler velocimeter (PDV) to measure the associated detonation velocity. These measurements have aided us in our understanding of energetic materials and enhanced our diagnostic capabilities.

  20. Estimating Radar Velocity using Direction of Arrival Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Horndt, Volker [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States); Bickel, Douglas Lloyd [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naething, Richard M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    Direction of Arrival (DOA) measurements, as with a monopulse antenna, can be compared against Doppler measurements in a Synthetic Aperture Radar ( SAR ) image to determine an aircraft's forward velocity as well as its crab angle, to assist the aircraft's navigation as well as improving high - performance SAR image formation and spatial calibration.

  1. Radar velocity determination using direction of arrival measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.; Horndt, Volker

    2017-12-19

    The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis. This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.

  2. SIRHEN : a data reduction program for photonic Doppler velocimetry measurements.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Doppler velocity fields in magnetic structures and their surroundings

    Czech Academy of Sciences Publication Activity Database

    Klvaňa, Miroslav; Bumba, Václav; Švanda, Michal

    2006-01-01

    Roč. 30, č. 1 (2006), s. 21-30 ISSN 1845-8319. [Central European Solar Physics Meeting /2./. Bairisch Kölldorf, 19.05.2005-21.05.2005] R&D Projects: GA AV ČR IAA3003404; GA ČR GA205/04/2129 Institutional research plan: CEZ:AV0Z10030501 Keywords : solar photosphere * velocity field * magnetic and non-magnetic regions Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  4. Intraoperative changes of transcranial Doppler velocity: relation to arterial oxygen content and whole-blood viscosity

    NARCIS (Netherlands)

    Schuurman, P. R.; Albrecht, K. W.

    1999-01-01

    The association of arterial oxygen content (CaO2) and viscosity with transcranial Doppler (TCD) blood flow velocity in the middle cerebral artery was studied in 20 adults without cerebrovascular disease undergoing abdominal surgery associated with significant fluctuations in hematology. TCD

  5. Systematic retrieval of ejecta velocities and gas fluxes at Etna volcano using L-Band Doppler radar

    Science.gov (United States)

    Gouhier, Mathieu; Donnadieu, Franck

    2011-11-01

    Strombolian-type volcanic activity is characterized by a series of gas bubbles bursting at the top of a magma column and leading to the ejection of lava clots and gas emission at the surface. The quantitative analysis of physical parameters (e.g., velocity, size, and mass fluxes) controlling the emission dynamics of these volcanic products is very important for the understanding of eruption source mechanisms but remains difficult to obtain in a systematic fashion. Ground-based Doppler radar is found to be a very effective tool for measuring ejecta velocities at a high acquisition rate and close to the emission source. We present here a series of measurements carried out at Mt. Etna's Southeast crater, using an L-band volcanological Doppler radar, during the 4 July 2001 Strombolian eruptions. Doppler radar data are supplemented by the analysis of video snapshots recorded simultaneously. We provide here a set of physical parameters systematically retrieved from 247 Strombolian explosions spanning 15 min and occurring during the paroxysm of the eruption from 21:30 to 21:45 UT. The time-average values give a maximum particle velocity of V_{{}}^p = {94}.{7}± {24} {{m/s}} , a bulk lava jet velocity of {V_{{{{PW - rad}}}}} = {37}.{6}± {1}.{9} {{m/s}} , and an initial gas velocity at the source vent of V_0^g = {118}.{4}± {36} {{m/s}} . The time-averaged particle diameter is found to be about {D_{{{{PW - rad}}}}} = {4}.{2}± {2}.{1} {{cm}} . The volume and mass gas fluxes are estimated from time-averaged source gas velocities over the sequence duration at Q_v^g = {3} - {11} × {1}{0^{{3}}}{{{m}}^{{3}}}{{/s}} and Q_m^g = 0.{5} - {2} × {1}{0^{{3}}}{{kg/s}} , respectively.

  6. Numerical performance analysis of acoustic Doppler velocity profilers in the wake of an axial-flow marine hydrokinetic turbine

    Energy Technology Data Exchange (ETDEWEB)

    Richmond, Marshall C.; Harding, Samuel F.; Romero Gomez, Pedro DJ

    2015-09-01

    The use of acoustic Doppler current profilers (ADCPs) for the characterization of flow conditions in the vicinity of both experimental and full scale marine hydrokinetic (MHK) turbines is becoming increasingly prevalent. The computation of a three dimensional velocity measurement from divergent acoustic beams requires the assumption that the flow conditions are homogeneous between all beams at a particular axial distance from the instrument. In the near wake of MHK devices, the mean fluid motion is observed to be highly spatially dependent as a result of torque generation and energy extraction. This paper examines the performance of ADCP measurements in such scenarios through the modelling of a virtual ADCP (VADCP) instrument in the velocity field in the wake of an MHK turbine resolved using unsteady computational fluid dynamics (CFD). This is achieved by sampling the CFD velocity field at equivalent locations to the sample bins of an ADCP and performing the coordinate transformation from beam coordinates to instrument coordinates and finally to global coordinates. The error in the mean velocity calculated by the VADCP relative to the reference velocity along the instrument axis is calculated for a range of instrument locations and orientations. The stream-wise velocity deficit and tangential swirl velocity caused by the rotor rotation lead to significant misrepresentation of the true flow velocity profiles by the VADCP, with the most significant errors in the transverse (cross-flow) velocity direction.

  7. The determination by coherent lidar of Doppler-velocity profiles in turbulent atmosphere

    Science.gov (United States)

    Gurdev, Luan L.; Dreischuh, Tanja N.

    2003-11-01

    The influence is investigated quantitatively of the velocity fluctuations in turbulent atmosphere on the formation of the autocovariance of coherent heterodyne aerosol lidar signals. A multishot, high pulse repetition rate lidar operation is supposed. The limit cases of long-term and short-term averaging are especially considered, when the observation (data accumulation) time is respectively much larger or much less than the correlation time of the fluctuation process. As a result, the intuitive conception is proved and illustrated quatitatively that a long-term averaging, under stationary conditions, allows one to obtain (on the basis of the autocovariance) a range-resolved estimate of the parent population mean Doppler-velocity profile; a short-term averaging allows one to determine a (near) instantaneous range-resolved Doppler-velocity profile.

  8. Prediction of delayed neurological deficit after subarachnoid haemorrhage: a CT blood load and Doppler velocity approach

    International Nuclear Information System (INIS)

    Grosset, D.G.; McDonald, I.; Cockburn, M.; Straiton, J.; Bullock, R.R.

    1994-01-01

    The predictive value of cranial computed tomography (CT) blood load and serial transcranial Doppler sonography for the development of delayed ischaemic neurological deficit was assessed in 121 patients following subarachnoid haemorrhage. Of the 121 patients, 81 (67 %) had thick layers of blood or haematoma, including intraventricular bleeding. The proportion of patients who developed delayed deficit was higher with increasing amounts of subarachnoid blood on the admission CT (51 % of 53 cases in Fisher grade 3; 35 % of 33 cases in grade 2; 28 % of 7 cases in grade 1, P < 0.01). Doppler velocities obtained from readings at least every 2 days following admission were higher in patients with delayed neurological deficit (peak velocity for grade 3 patients 176 ± 6 cm/s (mean ± SE), versus grade 2: 164 ± 7 cm/s; grade 4 149 ± 9, both P = 0.04, Mann-Whitney). Peak velocity and maximal 24-h rise tended to be higher within different CT grades in patients with a deficit than in those without; this difference was significant for grade 3 patients (P < 0.01). We conclude that a combined approach with CT and Doppler sonography provides greater predictive value for the development of delayed ischaemic neurological deficit than either test considered independently. The value of Doppler sonography may be greatest for patients with Fisher grade 3 blood, in whom the risk of delayed ischaemia is greatest. (orig.)

  9. Baroreflex regulation measurement using a noninvasive laser Doppler method

    Science.gov (United States)

    Hast, Jukka T.; Myllylae, Risto A.; Sorvoja, Hannu; Nissilae, Seppo M.

    2001-05-01

    In this study, a noninvasive laser Doppler measurement method based on the self-mixing effect of a diode laser was used to measure baroreflex regulation, which is manifest in the blood pressure signal as a 0.1 Hz sinusoidal variation. The laser Doppler measurement system was used to measure the movement of the right radial artery of ten volunteers. Variation in blood pressure caused by the baroreflex affects the elastic properties of the arterial wall. When diastolic blood pressure increases, the elasticity of the arterial wall decreases, causing the wall to lose some of its movability. This decreased elasticity reveals itself in the Doppler signal such that when the blood pressure increases, the Doppler frequency decreases and vice versa. The results show, that the laser Doppler method can be used to measure baroreflex regulation. Finally, baroreflex regulation in the Doppler signal is approximately in the inverse phase with respect to variation in diastolic blood pressure.

  10. Dead time effects in laser Doppler anemometry measurements

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Buchhave, Preben; George, William K.

    2014-01-01

    We present velocity power spectra computed by the so-called direct method from burst-type laser Doppler anemometer (LDA) data, both measured in a turbulent round jet and generated in a computer. Using today’s powerful computers, we have been able to study more properties of the computed spectra......, however, are assumed to be measured for each data point. In addition, the detector and processor used in the current study introduce a certain amount of fixed processing and data transfer times, which further contribute to the distortion of the computed spectrum. However, we show an excellent agreement...... between a measured spectrum and our modeled LDA data, thereby confirming the validity of our model for the LDA burst processor....

  11. Ultrasound propagation in steel piping at electric power plant using clamp-on ultrasonic pulse doppler velocity-profile flowmeter

    International Nuclear Information System (INIS)

    Tezuka, Kenichi; Mori, Michitsugu; Wada, Sanehiro; Aritomi, Masanori; Kikura, Hiroshige

    2008-01-01

    Venturi nozzles are widely used to measure the flow rates of reactor feedwater. This flow rate of nuclear reactor feedwater is an important factor in the operation of nuclear power reactors. Some other types of flowmeters have been proposed to improve measurement accuracy. The ultrasonic pulse Doppler velocity-profile flowmeter is expected to be a candidate method because it can measure the flow profiles across the pipe cross sections. For the accurate estimation of the flow velocity, the incidence angle of ultrasonic entering the fluid should be carefully estimated by the theoretical approach. However, the evaluation of the ultrasound propagation is not straightforward for the several reasons such as temperature gradient in the wedge or mode conversion at the interface between the wedge and pipe. In recent years, the simulation code for ultrasound propagation has come into use in the nuclear field for nondestructive testing. This article analyzes and discusses ultrasound propagation in steel piping and water, using the 3D-FEM simulation code and the Kirchhoff method, as it relates to the flow profile measurements in power plants with the ultrasonic pulse Doppler velocity-profile flowmeter. (author)

  12. Application of acoustic doppler velocimeters for streamflow measurements

    Science.gov (United States)

    Rehmel, M.

    2007-01-01

    The U.S. Geological Survey (USGS) principally has used Price AA and Price pygmy mechanical current meters for measurement of discharge. New technologies have resulted in the introduction of alternatives to the Price meters. One alternative, the FlowTracker acoustic Doppler velocimeter, was designed by SonTek/YSI to make streamflow measurements in wadeable conditions. The device measures a point velocity and can be used with standard midsection method algorithms to compute streamflow. The USGS collected 55 quality-assurance measurements with the FlowTracker at 43 different USGS streamflow-gaging stations across the United States, with mean depths from 0.05to0.67m, mean velocities from 13 to 60 cm/s, and discharges from 0.02 to 12.4m3/s. These measurements were compared with Price mechanical current meter measurements. Analysis of the comparisons shows that the FlowTracker discharges were not statistically different from the Price meter discharges at a 95% confidence level. ?? 2007 ASCE.

  13. Turbulence as observed by concurrent measurements made at NSSL using weather radar, Doppler radar, Doppler lidar and aircraft

    Science.gov (United States)

    Lee, Jean T.

    1987-01-01

    As air traffic increases and aircraft capability increases in range and operating altitude, the exposure to weather hazards increases. Turbulence and wind shears are two of the most important of these hazards that must be taken into account if safe flight operations are to be accomplished. Beginning in the early 1960's, Project Rough Rider began thunderstorm investigations. Past and present efforts at the National Severe Storm Laboratory (NSSL) to measure these flight safety hazards and to describe the use of Doppler radar to detect and qualify these hazards are summarized. In particular, the evolution of the Doppler-measured radial velocity spectrum width and its applicability to the problem of safe flight is presented.

  14. Use of high sensitivity GNSS receiver Doppler measurements for indoor pedestrian dead reckoning.

    Science.gov (United States)

    He, Zhe; Renaudin, Valérie; Petovello, Mark G; Lachapelle, Gérard

    2013-03-28

    Dead-reckoning (DR) algorithms, which use self-contained inertial sensors combined with gait analysis, have proven to be effective for pedestrian navigation purposes. In such DR systems, the primary error is often due to accumulated heading drifts. By tightly integrating global navigation satellite system (GNSS) Doppler measurements with DR, such accumulated heading errors can usually be accurately compensated. Under weak signal conditions, high sensitivity GNSS (HSGNSS) receivers with block processing techniques are often used, however, the Doppler quality of such receivers is relatively poor due to multipath, fading and signal attenuation. This often limits the benefits of integrating HSGNSS Doppler with DR. This paper investigates the benefits of using Doppler measurements from a novel direct vector HSGNSS receiver with pedestrian dead-reckoning (PDR) for indoor navigation. An indoor signal and multipath model is introduced which explains how conventional HSGNSS Doppler measurements are affected by indoor multipath. Velocity and Doppler estimated by using direct vector receivers are introduced and discussed. Real experimental data is processed and analyzed to assess the veracity of proposed method. It is shown when integrating HSGNSS Doppler with PDR algorithm, the proposed direct vector method are more helpful than conventional block processing method for the indoor environments considered herein.

  15. Use of High Sensitivity GNSS Receiver Doppler Measurements for Indoor Pedestrian Dead Reckoning

    Directory of Open Access Journals (Sweden)

    Gérard Lachapelle

    2013-03-01

    Full Text Available Dead-reckoning (DR algorithms, which use self-contained inertial sensors combined with gait analysis, have proven to be effective for pedestrian navigation purposes. In such DR systems, the primary error is often due to accumulated heading drifts. By tightly integrating global navigation satellite system (GNSS Doppler measurements with DR, such accumulated heading errors can usually be accurately compensated. Under weak signal conditions, high sensitivity GNSS (HSGNSS receivers with block processing techniques are often used, however, the Doppler quality of such receivers is relatively poor due to multipath, fading and signal attenuation. This often limits the benefits of integrating HSGNSS Doppler with DR. This paper investigates the benefits of using Doppler measurements from a novel direct vector HSGNSS receiver with pedestrian dead-reckoning (PDR for indoor navigation. An indoor signal and multipath model is introduced which explains how conventional HSGNSS Doppler measurements are affected by indoor multipath. Velocity and Doppler estimated by using direct vector receivers are introduced and discussed. Real experimental data is processed and analyzed to assess the veracity of proposed method. It is shown when integrating HSGNSS Doppler with PDR algorithm, the proposed direct vector method are more helpful than conventional block processing method for the indoor environments considered herein.

  16. Refractive index effects on the scatter volume location and Doppler velocity estimates of ionospheric HF backscatter echoes

    Directory of Open Access Journals (Sweden)

    P. V. Ponomarenko

    2009-11-01

    Full Text Available Ionospheric E×B plasma drift velocities derived from the Super Dual Auroral Radar Network (SuperDARN Doppler data exhibit systematically smaller (by 20–30% magnitudes than those measured by the Defence Meteorological Satellites Program (DMSP satellites. A part of the disagreement was previously attributed to the change in the E/B ratio due to the altitude difference between the satellite orbit and the location of the effective scatter volume for the radar signals. Another important factor arises from the free-space propagation assumption used in converting the measured Doppler frequency shift into the line-of-sight velocity. In this work, we have applied numerical ray-tracing to identify the location of the effective scattering volume of the ionosphere and to estimate the ionospheric refractive index. The simulations show that the major contribution to the radar echoes should be provided by the Pedersen and/or escaping rays that are scattered in the vicinity of the F-layer maximum. This conclusion is supported by a statistical analysis of the experimental elevation angle data, which have a signature consistent with scattering from the F-region peak. A detailed analysis of the simulations has allowed us to propose a simple velocity correction procedure, which we have successfully tested against the SuperDARN/DMSP comparison data set.

  17. Continuous measurements of discharge from a horizontal acoustic Doppler current profiler in a tidal river

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Buschman, F.A.; Vermeulen, B.

    2009-01-01

    Acoustic Doppler current profilers (ADCPs) can be mounted horizontally at a river bank, yielding single-depth horizontal array observations of velocity across the river. This paper presents a semideterministic, semistochastic method to obtain continuous measurements of discharge from horizontal ADCP

  18. Flow velocity measurement with the nonlinear acoustic wave scattering

    Energy Technology Data Exchange (ETDEWEB)

    Didenkulov, Igor, E-mail: din@appl.sci-nnov.ru [Institute of Applied Physics, 46 Ulyanov str., Nizhny Novgorod, 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation); Pronchatov-Rubtsov, Nikolay, E-mail: nikvas@rf.unn.ru [Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation)

    2015-10-28

    A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.

  19. Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler

    International Nuclear Information System (INIS)

    Thomas, T.D.; Harpold, G.J.

    1990-01-01

    Transcranial Doppler ultrasound is a relatively new diagnostic modality which allows the non-invasive assessment of intracranial circulation. A total of 10 migraine patients were studied and compared to healthy controls without headaches. Migraineurs during the headache-free interval demonstrated excessive cerebrovascular reactivity to CO 2 , evidenced by an increase in middle cerebral artery blood flow velocity of 47% ± 15% compared to 28% ± 14% in controls. Differences between the two study groups revealed no significant decrease in middle cerebral artery blood flow velocity with hypocapnia. However, the differences between middle cerebral artery blood flow velocity during hyperventilation and CO 2 inhalation were significantly different comparing migraineurs and controls. Instability of the baseline blood flow velocities was also noted in migraineurs during the interictal period. Characteristics which may allow differentiation of migraineurs from other headache populations could possibly be obtained from transcranial Doppler ultrasound flow studies. 24 refs., 2 tabs

  20. Variability of Vertical Velocity Statistics in the Cloud-Free Convective Boundary Layer as Revealed by Doppler Lidar

    Science.gov (United States)

    Berg, L. K.; Newsom, R. K.; Turner, D. D.

    2016-12-01

    The majority of our understanding of the behavior of vertical velocity in the convective boundary layer is based on a small number of short-term observations made using either in situ or with remote sensing techniques over a limited number of sites. Analysis of long-term statistics have been lacking due to the scarcity of appropriate measurements. The US Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility is addressing this shortcoming through the deployment of a suite of scanning Doppler Lidars at a number of locations, associated with reconfiguration of the ARM Southern Great Plains site and the recent Holistic Interaction of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign. In this study, we utilize data collected by a Doppler Lidar system that has operated continuously from 2011 to the present at a location in north-central Oklahoma to examine the long-term behavior of the vertical velocity variance, skewness, and kurtosis. The application of standard normalization techniques, such as the mixed-layer depth and Deardorff convective velocity scale, do a good job in collapsing the data onto a single curve during periods in which the boundary layer is well developed, albeit with considerable amounts of scatter. During non-steady conditions, such as those found in the morning, scaling using the Deardorff convective velocity scale is found to work poorly. This behavior is likely due to the eddy turnover time and the growth rate of the boundary-layer depth. Systematic differences in the turbulence statistics are found by season, for non-stationary conditions, or periods with relatively small and large values of the surface friction velocity measured at the surface, amount of static instability, and wind shear across the boundary-layer top.

  1. Secondary benefit of maintaining normal transcranial Doppler velocities when using hydroxyurea for prevention of severe sickle cell anemia.

    Science.gov (United States)

    Ghafuri, Djamila Labib; Chaturvedi, Shruti; Rodeghier, Mark; Stimpson, Sarah-Jo; McClain, Brandi; Byrd, Jeannie; DeBaun, Michael R

    2017-07-01

    In a retrospective cohort study, we tested the hypothesis that when prescribing hydroxyurea (HU) to children with sickle cell anemia (SCA) to prevent vaso-occlusive events, there will be a secondary benefit of maintaining low transcranial Doppler (TCD) velocity, measured by imaging technique (TCDi). HU was prescribed for 90.9% (110 of 120) of children with SCA ≥5 years of age and followed for a median of 4.4 years, with 70% (n = 77) receiving at least one TCDi evaluation after starting HU. No child prescribed HU had a conditional or abnormal TCDi measurement. HU initiation for disease severity prevention decreases the prevalence of abnormal TCDi velocities. © 2016 Wiley Periodicals, Inc.

  2. Color Doppler myocardial imaging demonstrates reduced diastolic tissue velocity in growth retarded fetuses with flow redistribution.

    Science.gov (United States)

    Larsen, Lene U; Petersen, Olav B; Sloth, Erik; Uldbjerg, Niels

    2011-04-01

    In fetuses suffering from intrauterine growth retardation with cerebroplacental redistribution (IUGR CPR), the diastolic heart function may be particularly susceptible to hypoxemia as described in postnatal pathological conditions. Using the newly introduced ultrasound technique, color Doppler myocardial imaging (CDMI), we investigated the correlation between diastolic tissue velocities and diastolic blood flow velocities and compared diastolic myocardial tissue velocities in fetuses with IUGR CPR and normal fetuses. Peak early and active atrial tissue velocities (E' and A') were acquired from both ventricular free walls in 18 fetuses with IUGR CPR and 42 normal fetuses. In 35 normal fetuses, blood flow across the atrio-ventricular valves was also recorded. Umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) flows were obtained in all fetuses. Nonparametric tests were used for statistical analysis. There was a tendency towards increased E' and A' with fetal age in normal pregnancies. No correlation between tissue velocity and blood flow velocity was established. IUGR CPR fetuses had significantly lower E' and A', but when indexing to heart length, only A' remained significantly lower. E'/A' ratio was increased in the left ventricle but unchanged in the right. CDMI is easily applicable during standard fetal echocardiography and provides new information on the diastolic properties of the fetal myocardium. In fetuses with IUGR CPR, diastolic tissue velocities are abnormal and especially A' may be a marker of diastolic dysfunction. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  3. Minimally destructive Doppler measurement of a quantized, superfluid flow

    Science.gov (United States)

    Anderson, Neil; Kumar, Avinash; Eckel, Stephen; Stringari, Sandro; Campbell, Gretchen

    2016-05-01

    Ring shaped Bose-Einstein condensates are of interest because they support the existence of quantized, persistent currents. These currents arise because in a ring trap, the wavefunction of the condensate must be single valued, and thus the azimuthal velocity is quantized. Previously, these persistent current states have only been measured in a destructive fashion via either interference with a phase reference or using the size of a central vortex-like structure that appears in time of flight. Here, we demonstrate a minimally destructive, in-situ measurement of the winding number of a ring shaped BEC. We excite a standing wave of phonon modes in the ring BEC using a perturbation. If the condensate is in a nonzero circulation state, then the frequency of these phonon modes are Doppler shifted, causing the standing wave to precess about the ring. From the direction and velocity of this precession, we can infer the winding number of the flow. For certain parameters, this technique can detect individual winding numbers with approximately 90% fidelity.

  4. Doppler Wind Lidar Measurements and Scalability to Space

    Data.gov (United States)

    National Aeronautics and Space Administration — Global measurements of wind speed and direction from Doppler wind lidars, if available, would significantly improve forecasting of severe weather events such as...

  5. Using transthoracic Doppler echocardiography to diagnose reduced coronary flow velocity reserve in the posterior descending coronary artery in children with elevated right ventricular pressure.

    Science.gov (United States)

    Shimada, Shunsuke; Harada, Kenji; Toyono, Manatomo; Tamura, Masamichi; Takada, Goro

    2007-12-01

    Advances in transthoracic Doppler echocardiography enable noninvasive measurements of coronary flow velocity and coronary flow velocity reserve (CFVR) in the posterior descending coronary artery (PD). To evaluate CFVR in the PD of children with elevated right ventricular (RV) pressure, 19 children with RV pressure overload and 13 age-matched controls with normal RV pressure were studied using transthoracic Doppler echocardiography. Average peak flow velocity (APV) was measured at rest and in hyperemic conditions (intravenous administration of adenosine of 0.16 mg.kg(-1).min(-1)). Compared with controls, the PD CFVR was significantly reduced in the patients with elevated RV pressure (1.87+/-0.42 vs 2.49+/-0.55, pvelocity.

  6. Coronary Flow Velocity Reserve Assessed by Transthoracic Doppler: The iPOWER Study: Factors Influencing Feasibility and Quality.

    Science.gov (United States)

    Michelsen, Marie M; Pena, Adam; Mygind, Naja D; Frestad, Daria; Gustafsson, Ida; Hansen, Henrik S; Kastrup, Jens; Bech, Jan; Høst, Nis; Prescott, Eva

    2016-07-01

    Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography is a noninvasive measure of microvascular function, but it has not achieved widespread use, mainly because of concerns of validity and feasibility. The aim of this study was to describe the feasibility and factors associated with the quality of CFVR obtained in a large prospective study of women suspected of having microvascular disease. Women with angina-like chest pain and no obstructive coronary artery disease on coronary angiography (<50% stenosis) were consecutively examined by transthoracic Doppler echocardiography of the left anterior descending coronary artery to measure CFVR (n = 947). Quality was evaluated on the basis of (1) identification of the left anterior descending coronary artery, (2) maintained probe position throughout the examination, (3) visibility and configuration of the left anterior descending coronary artery in two-dimensional color Doppler mode, and (4) gradual, consistent increases of characteristic, well-defined flow velocity curves in pulsed-wave mode. The mean age (SD) was 62.1 ± 9.7 years. On the basis of the evaluations, patients were divided into four groups according to quality score: nonfeasible (n = 28 [3%]), low quality (n = 80 [8%]), medium quality (n = 451 [48%]), and high quality (n = 388 [41%]). Quality score was associated with diabetes (P < .01), body mass index (P = .02), waist circumference (P = .05), nonsignificant atherosclerosis on coronary angiography (P = .03), and operator experience (P < .01). Low examination quality was associated with lower CFVR (P = .03), also after multivariate adjustment. Transthoracic Doppler echocardiographic measurement of CFVR is highly feasible and of good quality in experienced hands. However, CFVR is possibly underestimated when examination quality is low. Awareness of pitfalls and potential bias may improve the validity and interpretation of the measures obtained

  7. Quality characterization of reflectivity and radial velocity observed by Indian Doppler weather radars

    Science.gov (United States)

    Amarjyothi, Kasimahanthi; Dutta, Devajyoti; Devarajan, Preveen Kumar; George, John P.; Rajagopal, Ekkattil N.

    2017-07-01

    Static and dynamic quality index (QI) maps are generated as the base products of Doppler weather radar (DWR). The quality characterization of radar reflectivity and radial velocity in terms of their QI is presented for the operational DWRs in India. A static composite QI has been generated using the maximum method. These static maps enable the detection of a low QI region in advance for the Indian radars. The QI of reflectivity is above 0.5 in all regions except in the regions of blockage, high attenuation due to rain, and beam broadening, whereas the QI of radial velocity is good for values >0.8 except for the ambiguous region and the region affected by nonmeteorological echoes. This shall help in the quick preprocessing of radar observations, since the regions of low QI can be masked. A sample case of gridded radar rainfall is presented by employing the QI scheme.

  8. Estimating discharge using multi-level velocity data from acoustic doppler instruments

    DEFF Research Database (Denmark)

    Poulsen, Jane Bang; Rasmussen, Keld Rømer; Ovesen, Niels Bering

    it records the stage. The monthly control measurements made by the water authority office are made with an ADCP-instrument (Streampro, acoustic Doppler current profiler) which is pulled across the stream next to the in situ Doppler instruments. As part of the present project supplementary ADCP-data have been......In the majority of Danish streams, weed growth affects the effective stream width and bed roughness thus imposes temporal variations on the stage-discharge relationship. Small stream-gradients and firm ecology based restrictions prevent that hydraulic structures are made at the discharge stations...... and thus remove or limit such influences. Hence, estimation of the hydrograph is based on continuous stream gauging combined with monthly control measurements of discharge and assuming linear variation of bed roughness between the monthly measurements. As a result, any non-linear drift in weed density...

  9. Evaluation of postoperative pulmonary regurgitation after surgical repair of tetralogy of Fallot: comparison between Doppler echocardiography and MR velocity mapping

    Energy Technology Data Exchange (ETDEWEB)

    Grothoff, Matthias; Spors, Birgit; Gutberlet, Matthias [Charite Campus Virchow Klinikum, Department of Radiology and Nuclear Medicine, Berlin (Germany); Abdul-Khaliq, Hasim [Deutsches Herzzentrum, Department of Congenital Heart Disease/Pediatric Cardiology, Berlin (Germany)

    2008-02-15

    Pulmonary regurgitation is a common finding in patients after correction of tetralogy of Fallot (TOF). Right ventricular impairment and even ventricular arrhythmia have been ascribed to pulmonary valve insufficiency (PI), which is therefore an important issue in follow-up examinations. To compare PI measured by echocardiography (ECHO) with data provided by cardiac MRI (CMR). We studied 54 selected patients (18 female; median age 14.0 years, range 3.8-53.4 years) after surgical correction of TOF. To quantify pulmonary regurgitant fraction (PRF) by CMR, flow velocity mapping was performed. On Doppler ECHO, length, width and localization of regurgitant flow was measured. The severity of PI was categorized as mild, moderate or severe and compared to the data obtained by CMR. On CMR the mean PRF was 29.2 {+-} 13.4%. Patients with a transannular patch had a significantly higher PRF (39.9 {+-} 11.6%) than patients with an intact annular ring (23.6 {+-} 11.4%). Differentiation by Doppler ECHO between the categories mild, moderate and severe PI was confirmed by significant differences in PRF measured by CMR (mild vs. moderate P < 0.04; moderate vs. severe P < 0.014; mild vs. severe P < 0.001). Furthermore, PRF correlated with right ventricular end diastolic volume index (r = 0.45, P < 0.01) and right ventricular end systolic volume index (r = 0.39, P < 0.01). Doppler ECHO can estimate the severity of PI after repair of TOF with acceptable results compared to CMR flow measurement. In univariate analysis there is only a weak influence of PRF on right ventricular volume. (orig.)

  10. Evaluation of postoperative pulmonary regurgitation after surgical repair of tetralogy of Fallot: comparison between Doppler echocardiography and MR velocity mapping

    International Nuclear Information System (INIS)

    Grothoff, Matthias; Spors, Birgit; Gutberlet, Matthias; Abdul-Khaliq, Hasim

    2008-01-01

    Pulmonary regurgitation is a common finding in patients after correction of tetralogy of Fallot (TOF). Right ventricular impairment and even ventricular arrhythmia have been ascribed to pulmonary valve insufficiency (PI), which is therefore an important issue in follow-up examinations. To compare PI measured by echocardiography (ECHO) with data provided by cardiac MRI (CMR). We studied 54 selected patients (18 female; median age 14.0 years, range 3.8-53.4 years) after surgical correction of TOF. To quantify pulmonary regurgitant fraction (PRF) by CMR, flow velocity mapping was performed. On Doppler ECHO, length, width and localization of regurgitant flow was measured. The severity of PI was categorized as mild, moderate or severe and compared to the data obtained by CMR. On CMR the mean PRF was 29.2 ± 13.4%. Patients with a transannular patch had a significantly higher PRF (39.9 ± 11.6%) than patients with an intact annular ring (23.6 ± 11.4%). Differentiation by Doppler ECHO between the categories mild, moderate and severe PI was confirmed by significant differences in PRF measured by CMR (mild vs. moderate P < 0.04; moderate vs. severe P < 0.014; mild vs. severe P < 0.001). Furthermore, PRF correlated with right ventricular end diastolic volume index (r = 0.45, P < 0.01) and right ventricular end systolic volume index (r = 0.39, P < 0.01). Doppler ECHO can estimate the severity of PI after repair of TOF with acceptable results compared to CMR flow measurement. In univariate analysis there is only a weak influence of PRF on right ventricular volume. (orig.)

  11. Concordance and reproducibility between M-mode, tissue Doppler imaging, and two-dimensional strain imaging in the assessment of mitral annular displacement and velocity in patients with various heart conditions

    DEFF Research Database (Denmark)

    de Knegt, Martina Chantal; Biering-Sorensen, Tor; Sogaard, Peter

    2014-01-01

    between motion mode (M-mode), colour tissue Doppler imaging (TDI), and two-dimensional strain imaging (2DSI) when measuring MA displacement and systolic velocity. METHODS AND RESULTS: Using GE Healthcare Vivid 7 and E9 and Echopac BT11 software, MA displacement and velocity measurements by 2DSI, TDI...

  12. Lateral resonant Doppler flow measurement by spectral domain optical coherence tomography

    Science.gov (United States)

    Walther, Julia; Koch, Edmund

    2017-07-01

    In spectral domain optical coherence tomography (SD-OCT), any transverse motion component of a detected obliquely moving sample results in a nonlinear relationship between the Doppler phase shift and the axial sample velocity restricting phase-resolved Doppler OCT. To circumvent the limitation, we propose the lateral resonant Doppler flow quantification in spectral domain OCT, where the scanner movement velocity is matched to the transverse velocity component of the sample motion.

  13. Fast Doppler as a novel bedside measure of cerebral perfusion in preterm infants.

    Science.gov (United States)

    Peeples, Eric S; Mehic, Edin; Mourad, Pierre D; Juul, Sandra E

    2016-02-01

    Altered cerebral perfusion from impaired autoregulation may contribute to the morbidity and mortality associated with premature birth. We hypothesized that fast Doppler imaging could provide a reproducible bedside estimation of cerebral perfusion and autoregulation in preterm infants. This is a prospective pilot study using fast Doppler ultrasound to assess blood flow velocity in the basal ganglia of 19 subjects born at 26-32 wk gestation. Intraclass correlation provided a measure of test-retest reliability, and linear regression of cerebral blood flow velocity and heart rate or blood pressure allowed for estimations of autoregulatory ability. The intraclass correlation when imaging in the first 48 h of life was 0.634. We found significant and independent correlations between the systolic blood flow velocity and both systolic blood pressure and heart rate (P = 0.015 and 0.012 respectively) only in the 26-28 wk gestational age infants in the first 48 h of life. Our results suggest that fast Doppler provides reliable bedside measurements of cerebral blood flow velocity at the tissue level in premature infants, acting as a proxy for cerebral tissue perfusion. Additionally, autoregulation appears to be impaired in the extremely preterm infants, even within a normal range of blood pressures.

  14. Laser Doppler anemometry measurements in a circulating fluidized bed of metal particles

    DEFF Research Database (Denmark)

    Ibsen, Claus Hübbe; Solberg, Tron; Hjertager, Bjørn Helge

    2002-01-01

    of the solid phase from which the particle kinetic stresses were determined. The measured velocity profiles are in agreement with previous data from the full-scale boiler, i.e. showing a flat profile over the core region of the riser with a pronounced wall layer. The particle kinetic stresses are found......Laser Doppler Anemometry (LDA) measurements were performed in a 1/9 scale model of a 12 MW circulating fluidized bed (CFB) boiler. The model was operated according to scaling laws. The 2D-LDA system used was positioned in two different ways to obtain the three velocity components u, v and w...

  15. Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenzhong; Yi, Ji; Chen, Siyu [Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Jiao, Shuliang [Department of Biomedical Engineering, Florida International University, Miami, Florida 33174 (United States); Zhang, Hao F., E-mail: hfzhang@northwestern.edu [Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60208 and Department of Ophthalmology, Northwestern University, Chicago, Illinois 60611 (United States)

    2015-09-15

    Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.

  16. Using WSR-88D Polarimetric Data to Identify Bird-Contaminated Doppler Velocities

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2013-01-01

    Full Text Available As an important part of Doppler velocity data quality control for radar data assimilation and other quantitative applications, an automated technique is developed to identify and remove contaminated velocities by birds, especially migrating birds. This technique builds upon the existing hydrometeor classification algorithm (HCA for dual-polarimetric WSR-88D radars developed at the National Severe Storms Laboratory, and it performs two steps. In the first step, the fuzzy-logic method in the HCA is simplified and used to identify biological echoes (mainly from birds and insects. In the second step, another simple fuzzy logic method is developed to detect bird echoes among the biological echoes identified in the first step and thus remove bird-contaminated velocities. The membership functions used by the fuzzy logic method in the second step are extracted from normalized histograms of differential reflectivity and differential phase for birds and insects, respectively, while the normalized histograms are constructed by polarimetric data collected during the 2012 fall migrating season and sorted for bird and insects, respectively. The performance and effectiveness of the technique are demonstrated by real-data examples.

  17. Wavelet entropy of Doppler ultrasound blood velocity flow waveforms distinguishes nitric oxide-modulated states.

    Science.gov (United States)

    Agnew, Christina E; Hamilton, Paul K; McCann, Aaron J; McGivern, R Canice; McVeigh, Gary E

    2015-05-01

    Wavelet entropy assesses the degree of order or disorder in signals and presents this complex information in a simple metric. Relative wavelet entropy assesses the similarity between the spectral distributions of two signals, again in a simple metric. Wavelet entropy is therefore potentially a very attractive tool for waveform analysis. The ability of this method to track the effects of pharmacologic modulation of vascular function on Doppler blood velocity waveforms was assessed. Waveforms were captured from ophthalmic arteries of 10 healthy subjects at baseline, after the administration of glyceryl trinitrate (GTN) and after two doses of N(G)-nitro-L-arginine-methyl ester (L-NAME) to produce vasodilation and vasoconstriction, respectively. Wavelet entropy had a tendency to decrease from baseline in response to GTN, but significantly increased after the administration of L-NAME (mean: 1.60 ± 0.07 after 0.25 mg/kg and 1.72 ± 0.13 after 0.5 mg/kg vs. 1.50 ± 0.10 at baseline, p wavelet entropy had a spectral distribution from increasing doses of L-NAME comparable to baseline, 0.07 ± 0.04 and 0.08 ± 0.03, respectively, whereas GTN had the most dissimilar spectral distribution compared with baseline (0.17 ± 0.08, p = 0.002). Wavelet entropy can detect subtle changes in Doppler blood velocity waveform structure in response to nitric-oxide-mediated changes in arteriolar smooth muscle tone. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  18. Passive emitter location with Doppler frequency and interferometric measurements

    NARCIS (Netherlands)

    Groot, J.S.; Dam, F.A.M.; Theil, A.

    2008-01-01

    Ground based emitters can be located with a receiver installed on an airborne platform. This paper discusses techniques based on Doppler frequency and differential phase measurements (interferometry). Measurements of the first technique are provided, while we discuss and compare the theoretical

  19. Measurement of LBE flow velocity profile by UDVP

    International Nuclear Information System (INIS)

    Kikuchi, Kenji; Takeda, Yasushi; Obayashi, Hiroo; Tezuka, Masao; Sato, Hiroshi

    2006-01-01

    Measurements of liquid metal lead-bismuth eutectic (LBE), flow velocity profile were realized in the spallation neutron source target model by the ultrasonic Doppler velocity profiler (UVDP) technique. So far, it has not been done well, because both of poor wetting property of LBE with stainless steels and poor performance of supersonic probes at high temperatures. The measurement was made for a return flow in the target model, which has coaxially arranged annular and tube channels, in the JAEA Lead Bismuth Loop-2 (JLBL-2). The surface treatment of LBE container was examined. It was found that the solder coating was effective to enhance an intensity of reflected ultrasonic wave. This treatment has been applied to the LBE loop, which was operated up to 150 deg. C. The electro magnetic pump generates LBE flow and the flow rate was measured by the electro magnetic flow meter. By changing the flow rate of LBE, velocity profiles in the target were measured. It was confirmed that the maximum velocity in the time-averaged velocity distribution on the target axis was proportional to the flow rate measured by the electro magnetic flow meter

  20. Photonic systems for high precision radial velocity measurements

    Science.gov (United States)

    Halverson, Samuel P.

    The discovery of Earth-like exoplanets has profound implications for our understanding of the origins and diversity of life in our universe. As such, developing new and improved Doppler radial velocity (RV) spectrometers capable of discovering and characterizing these planets is a high priority in the astronomical community. However, detection of true Earth-analogs remains beyond the technical reach of current Doppler RV instruments. This thesis discusses a number of technological developments designed specifically to overcome classical instrumental limitations of high precision Doppler RV measurements. These technologies are essential components of next generation instruments that aim to achieve the RV precision necessary to detect low-mass planets. This instrumentation research is driven by the development of the Habitable-zone Planet Finder (HPF), a near-infrared (NIR) Doppler spectrograph currently under development at Penn State that will detect terrestrial-mass planets orbiting nearby M-dwarfs. Furthermore, many technologies discussed will also be applied to the NASA-NSF Extreme Precision Doppler Spectrometer concept NEID, a Doppler RV instrument for the 3.5 meter WIYN telescope, slated for delivery in 2019. NEID is an ultra-stable, high resolution optical spectrometer also under development at Penn State. This thesis describes new specialized optical fiber delivery systems, designed to significantly improve instrument illumination stability, modal noise suppression systems, which suppress mode interference in optical fibers and allow spectrometers to fully realize the exquisite precision of modern wavelength calibration sources, and new photonic calibration sources, which show significant promise as potential Doppler wavelength references. These technologies represent important steps in enabling next generation instruments to reach precisions sufficient to detect terrestrial-mass planets orbiting in the Habitable-zones of nearby stars. Improving measurement

  1. Lower Transcranial Doppler Flow Velocities in Sickle Cell Anemia Patients on Hydroxyurea: Myth or Fact.

    Science.gov (United States)

    Moeen, Sawsan M; Thabet, Ahmad F; Hasan, Hosam A; Saleh, Medhat A

    2018-01-01

    Transcranial Doppler (TCD) detects stroke risk in patients with sickle cell anemia (SCA). Hydroxyurea therapy has the ability to induce increased levels of fetal hemoglobin in sickle cells thus decreasing tendency for red cell sickling. This study aimed to evaluate TCD findings in SCA patients on hydroxyurea and correlate the time-averaged mean velocity (TAMV) with their hematological parameters. Forty SCA patients of both sexes, aged 16-22 years with no history of stroke were screened with TCD for an elevated TAMV, divided into: Group T (20 patients on blood transfusion); and Group H (20 patients on daily hydroxyurea). For all, full medical history, clinical examination, hemoglobin, hematocrit, leukocytes, platelets, fetal hemoglobin and sickling test, in addition TCD to describe the pattern of cerebral blood flow abnormalities were done. TAMV in all cerebral arteries were significantly higher in Group T than Group H, the highest TAMV (147.5 ± 57.09 cm/s) was found in the right middle cerebral artery and correlated negatively with hematocrit in Groups H ( P  Hydroxyurea therapy may lower TCD velocities and prevent the risk of primary stroke in SCA patients.

  2. Preload dependence of color M-mode Doppler flow propagation velocity in controls and in patients with left ventricular dysfunction

    DEFF Research Database (Denmark)

    Møller, J E; Poulsen, S H; Søndergaard, E

    2000-01-01

    The purpose of this study was to assess the effects of preload alterations on color M-mode flow propagation velocity (Vp) in volunteers with normal left ventricular (LV) function and in patients with depressed LV function. Color M-mode Doppler echocardiography was performed during Valsalva maneuv...

  3. Velocity measurement of conductor using electromagnetic induction

    International Nuclear Information System (INIS)

    Kim, Gu Hwa; Kim, Ho Young; Park, Joon Po; Jeong, Hee Tae; Lee, Eui Wan

    2002-01-01

    A basic technology was investigated to measure the speed of conductor by non-contact electromagnetic method. The principle of the velocity sensor was electromagnetic induction. To design electromagnet for velocity sensor, 2D electromagnetic analysis was performed using FEM software. The sensor output was analyzed according to the parameters of velocity sensor, such as the type of magnetizing currents and the lift-off. Output of magnetic sensor was linearly depended on the conductor speed and magnetizing current. To compensate the lift-off changes during measurement of velocity, the other magnetic sensor was put at the pole of electromagnet.

  4. Non-contact measurement of facial surface vibration patterns during singing by scanning laser Doppler vibrometer.

    Science.gov (United States)

    Kitamura, Tatsuya; Ohtani, Keisuke

    2015-01-01

    This paper presents a method of measuring the vibration patterns on facial surfaces by using a scanning laser Doppler vibrometer (LDV). The surfaces of the face, neck, and body vibrate during phonation and, according to Titze (2001), these vibrations occur when aerodynamic energy is efficiently converted into acoustic energy at the glottis. A vocalist's vibration velocity patterns may therefore indicate his or her phonatory status or singing skills. LDVs enable laser-based non-contact measurement of the vibration velocity and displacement of a certain point on a vibrating object, and scanning LDVs permit multipoint measurements. The benefits of scanning LDVs originate from the facts that they do not affect the vibrations of measured objects and that they can rapidly measure the vibration patterns across planes. A case study is presented herein to demonstrate the method of measuring vibration velocity patterns with a scanning LDV. The objective of the experiment was to measure the vibration velocity differences between the modal and falsetto registers while three professional soprano singers sang sustained vowels at four pitch frequencies. The results suggest that there is a possibility that pitch frequency are correlated with vibration velocity. However, further investigations are necessary to clarify the relationships between vibration velocity patterns and phonation status and singing skills.

  5. Color Doppler measurement of blood flow in the inferior thyroid artery in patients with autoimmune thyroid diseases

    International Nuclear Information System (INIS)

    Caruso, Giuseppe; Attard, Marco; Caronia, Aurelio; Lagalla, Roberto

    2000-01-01

    Purpose: The aim of the study is to find out whether the measurement of peak systolic velocity in the inferior thyroid artery (ITA) is a valuable parameter to differentiate autoimmune thyroid diseases (hyper-, normo- or hypofunctional) and to evaluate the efficacy of medical treatment. Material and methods: The ITA of 31 patients (eight with Graves' disease, 23 with subclinical hypothyroidism) was examined with color Doppler and pulsed Doppler. The final diagnosis was obtained by citology and by hormonal and antibodies assays. The patients were monitorized by ultrasound for a period of 8 months. Results: In all the patients with Graves' disease the peak systolic velocity was always over 150 cm/s, while in other autoimmune thyroiditis the peak systolic velocity was within the normal range, and never exceeding 65 cm/s. In the first group, the measurement taken in the ITA showed also the efficacy of the pharmacological treatment earlier and more reliably than the color Doppler pattern obtained in the parenchyma. Conclusions: The color Doppler measurement of the ITA seems to be a promising technique with low-cost and easy approach. In our experience, the color Doppler of the ITA could have a clinical role in the differential diagnosis of diffuse thyroid diseases and in the follow-up of the Graves' disease during medical treatment

  6. Year-Long Vertical Velocity Statistics Derived from Doppler Lidar Data for the Continental Convective Boundary Layer

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Larry K. [Pacific Northwest National Laboratory, Richland, Washington; Newsom, Rob K. [Pacific Northwest National Laboratory, Richland, Washington; Turner, David D. [Global Systems Division, NOAA/Earth System Research Laboratory, Boulder, Colorado

    2017-09-01

    One year of Coherent Doppler Lidar (CDL) data collected at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) site in Oklahoma is analyzed to provide profiles of vertical velocity variance, skewness, and kurtosis for cases of cloud-free convective boundary layers. The variance was scaled by the Deardorff convective velocity scale, which was successful when the boundary layer depth was stationary but failed in situations when the layer was changing rapidly. In this study the data are sorted according to time of day, season, wind direction, surface shear stress, degree of instability, and wind shear across the boundary-layer top. The normalized variance was found to have its peak value near a normalized height of 0.25. The magnitude of the variance changes with season, shear stress, and degree of instability, but was not impacted by wind shear across the boundary-layer top. The skewness was largest in the top half of the boundary layer (with the exception of wintertime conditions). The skewness was found to be a function of the season, shear stress, wind shear across the boundary-layer top, with larger amounts of shear leading to smaller values. Like skewness, the vertical profile of kurtosis followed a consistent pattern, with peak values near the boundary-layer top (also with the exception of wintertime data). The altitude of the peak values of kurtosis was found to be lower when there was a large amount of wind shear at the boundary-layer top.

  7. VizieR Online Data Catalog: GJ667C Doppler and activity measurements (Anglada-Escude+, 2013)

    Science.gov (United States)

    Anglada-Escude, G.; Tuomi, M.; Gerlach, E.; Barnes, R.; Heller, R.; Jenkins, J. S.; Wende, S.; Vogt, S. S.; Butler, R. P.; Reiners, A.; Jones, H. R. A.

    2013-06-01

    HARPS-TERRA Doppler and activity measurements of GJ 667C. Doppler Measurements are in the Barycenter of the Solar System and corrected for perspective acceleration. The median has been velocity has been subtracted for cosmetic purposes. Nominal uncertainties in FWHM and BIS are 2.0 and 2.35 times the corresponding UNCCCF. No consistent CCF measurement could be obtained for the last two spectra because of conflicting HARPS-DRS software versions (different binary masks) used to produce them. Except for those two spectra and according to the ESO archive documentation, all CCF measurements were generated using the default M2 binary mask. (1 data file).

  8. Transthoracic Doppler assessment of coronary flow velocity reserve in children with Kawasaki disease: comparison with coronary angiography and thallium-201 imaging.

    Science.gov (United States)

    Hiraishi, Satoshi; Hirota, Hamao; Horiguchi, Yasunori; Takeda, Nobuhiro; Fujino, Nobuyuki; Ogawa, Natsuko; Nakahata, Yayoi

    2002-11-20

    The purpose of this study was to determine the feasibility of coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) in children with Kawasaki disease (KD). Doppler-derived CFVR is a reliable marker predicting the presence of myocardial ischemia. We studied 49 patients (median age 11 years) with KD. The CFVR was calculated as the ratio of hyperemic to basal peak (peak CFVR) and mean (mean CFVR) diastolic flow velocities in the posterior descending coronary artery (PD) and left anterior descending coronary artery (LAD). The CFVR measurements by TTDE were compared with the results of coronary angiography, thallium-201 (Tl-201) single-photon emission computed tomography (SPECT), and intracoronary Doppler study. The CFVR measurements by TTDE were obtained in 92 (94%) of 98 vessels of the PD and LAD in 49 study patients. Both peak and mean CFVRs for 21 stenotic vessels were significantly smaller than those for 35 normal vessels and for 20 vessels with aneurysmal lesions (p children with KD.

  9. Acoustic resolution photoacoustic Doppler flowmetry using a transducer array: optimising processing for velocity contrast

    Science.gov (United States)

    Bücking, T. M.; van den Berg, P. J.; Balabani, S.; Steenbergen, W.; Beard, P. C.; Brunker, J.

    2017-03-01

    This work demonstrates the first measurements of blood flow velocity using photoacoustic flowmetry (PAF) employing a transducer array. The measurements were made in a flow phantom consisting of a tube (580 μm inner diameter) containing blood flowing steadily at physiological speeds ranging from 3 mm/s to 25 mm/s. Velocity measurements were based on the generation of two successive photoacoustic (PA) signals using two laser pulses with a wavelength of 1064 nm; the PA signals were detected using a 64-element transducer array with a -6 dB detection bandwidth of 11-17 MHz. We developed a processing pipeline to optimise a cross-correlation based velocity measurement method comprising the following processing steps: image reconstruction, filtering, displacement detection, and masking. We found no difference in flow detection accuracy when choosing different image reconstruction algorithms (time reversal, Fourier transformation, and delay-and-sum). High-pass filtering and wallfiltering were however found to be essential pre-processing steps in order to recover the correct displacement information. We masked the calculated velocity map based on the amplitude of the cross-correlation function in order to define the region of interest corresponding to highest signal amplitude. These developments enabled blood flow measurements using a transducer array, bringing PAF one step closer to clinical applicability.

  10. Doppler ultrasound velocities and resistive indexes immediately after pediatric liver transplantation: normal ranges and predictors of failure.

    Science.gov (United States)

    Jamieson, Lucy H; Arys, Bo; Low, Gavin; Bhargava, Ravi; Kumbla, Surekha; Jaremko, Jacob L

    2014-07-01

    We sought to determine the ranges of Doppler ultrasound findings immediately after pediatric liver transplantation that are associated with successful outcomes or postoperative complications. This study included consecutive children who underwent Doppler ultrasound less than 48 hours after liver transplantation from 2001 to 2011. Operative reports and clinical outcome data were recorded. We had 110 patients (54% girls) with mean age at transplantation of 2.9 years (median, 1.3 years; range, 0-14 years) and a median follow-up interval of 3.5 years. Two pediatric radiologists reviewed ultrasound images in consensus. We computed descriptive statistics, interindex correlations, and analysis of variance. Twenty-four of 110 patients had a vascular complication, most commonly hepatic arterial thrombosis (seven patients). Compared with published adult normal values, normal pediatric Doppler parameters at postoperative day 1 trended toward higher normal velocities and resistive indexes (up to 0.95). Absent or low-velocity common hepatic artery flow less than 50 cm/s or a common hepatic artery resistive index less than 0.50 were significantly associated with hepatic artery thrombosis, whereas absent or low-velocity portal venous flow less than 30 cm/s or low-velocity hepatic venous flow less than 25 cm/s were significantly associated with vascular complications and a monotonic hepatic venous waveform was significantly associated with venous complications. Flow in a pediatric liver on the first day after transplantation is normally hyperdynamic, especially in the youngest transplant recipients, and, as a result, low velocities or resistive indexes are particularly concerning for complications. The pediatric-specific ranges of expected posttransplantation Doppler ultrasound findings presented in this article should assist in identifying normal variation and potentially life-threatening complications.

  11. Measurement uncertainty budget of an interferometric flow velocity sensor

    Science.gov (United States)

    Bermuske, Mike; Büttner, Lars; Czarske, Jürgen

    2017-06-01

    Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their influences to the

  12. The geometry of Strombolian explosions: insights from Doppler radar measurements

    Science.gov (United States)

    Gouhier, Mathieu; Donnadieu, Franck

    2010-12-01

    Observations of Strombolian volcanic explosions were carried out at Etna's southeast crater on 2001 July 4 using a ground-based pulsed Doppler radar (VOLDORAD). To obtain quantitative constraints on the geometry of the explosions, we modelled synthetic Doppler spectra by combining the outputs of a ballistic model to compute the theoretical velocities of gas and particles, and an electromagnetic scattering model to calculate the synthetic echo power. This allowed us to reproduce the shapes of recorded Doppler spectra for each volcanic explosion. We examined the geometrical distribution of ejected pyroclasts for about 200 explosions and found two main types of explosion, each showing a distinctive spectral signature. The first type, characterized by the triangular shape of their Doppler spectra, represents 34 per cent of the explosions. This spectrum shape is related to a Gaussian distribution of the pyroclast ejection angles, where most of the volcanic material is ejected vertically within a narrow cone, with the particle concentration decreasing radially. The second type represents about 12 per cent of the explosions, and is characterized by a top-hat-shaped spectrum. It is produced by a uniform distribution of pyroclast ejection angles. In this case, the bubbles tend to burst above the crater rim and eject the ballistic clasts hemispherically without preferential orientation. The majority of the Strombolian explosions analysed (54 per cent) are intermediate between these end-member shapes, and show a triangular spectra truncated by a plateau. They result from a uniform distribution of ejection angles around the jet axis. The continuous radar recordings allowed us to carry out a statistical analysis on the geometrical features of the same 200 Strombolian explosions. Thus we find that 40° is a statistically representative aperture of the dispersion cone characterized by uniform ejecta distribution for explosions having a plateau component (i.e. 2/3 of all

  13. Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Wu Songhua

    2016-01-01

    Full Text Available Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA. In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

  14. Superhilac real-time velocity measurements

    International Nuclear Information System (INIS)

    Feinberg, B.; Meaney, D.; Thatcher, R.; Timossi, C.

    1987-03-01

    Phase probes have been placed in several external beam lines at the LBL heavy ion linear accelerator (SuperHILAC) to provide non-destructive velocity measurements independent of the ion being accelerated. The existing system has been improved to provide the following features: a display refresh rate better than twice per second, a sensitive pseudo-correlation technique to pick out the signal from the noise, simultaneous measurements of up to four ion velocities when more than one beam is being accelerated, and a touch-screen operator interface. These improvements allow the system to be used as a routine tuning aid and beam velocity monitor

  15. Spectral Doppler Waveforms for Diagnosis of Appendicitis: Potential Utility of Point Peak Systolic Velocity and Resistive Index Values.

    Science.gov (United States)

    Shin, Lewis K; Jeffrey, R Brooke; Berry, Gerald J; Olcott, Eric W

    2017-12-01

    Purpose To test the hypothesis that appendiceal spectral Doppler waveforms can distinguish patients with and patients without appendicitis. Materials and Methods In this retrospective study, Doppler waveforms were obtained from intramural appendiceal arteries identified with color Doppler imaging in 60% (93 of 155) of consecutive patients whose appendices were visualized at graded compression ultrasonography (US) performed for suspected appendicitis (53 male and 40 female; age, 1-56 years; mean, 14.5 years) over the 5-month period from November 2015 through March 2016. Point, non-angle-corrected peak systolic velocity (PSV) and resistive index (RI) values were compared between patients with and patients without appendicitis by utilizing histopathologically proven appendicitis and 6-week clinical follow-up as diagnostic reference standards. Data were assessed by using the Student t test, exact binomial distribution, two-sample test of proportions, and receiver operating characteristic analysis. Results Among the 93 patients, 36 (38.7%) had proven appendicitis (mean PSV, 19.7 cm/sec; mean RI, 0.69) and 57 patients (61.2%) did not (mean PSV, 7.1 cm/sec, P appendicitis was 0.97 (95% confidence interval [CI]: 0.95, 1.00) for PSV and 0.86 (95% CI: 0.78, 0.95; P = .011) for RI. Chosen discriminatory criteria of PSV greater than 10 cm/sec and RI greater than 0.65 yielded specificity for appendicitis of 94.7% and 96.5% with sensitivity of 88.9% and 63.9% (P = .013) and negative predictive value of 93.1% and 80.9% (P = .045), respectively. Original clinical graded compression US interpretations based on established US findings demonstrated specificity of 96.2% and sensitivity of 100.0%. Considering the subset of 20 patients whose maximum outer diameter measured 6-8 mm, the discriminatory criteria of PSV greater than 10 cm/sec and RI greater than 0.65 yielded specificity for appendicitis of 88.9% each, with sensitivity of 100.0% and 63.6% and negative predictive value of 100

  16. Non-contact measurement of facial surface vibration patterns during singing by scanning laser Doppler vibrometer

    Directory of Open Access Journals (Sweden)

    Tatsuya eKitamura

    2015-11-01

    Full Text Available This paper presents a method of measuring the vibration patterns onfacial surfaces by using a scanning laser Doppler vibrometer(LDV. The surfaces of the face, neck, and body vibrate duringphonation and, according to Titze (2001, these vibrations occur whenaerodynamic energy is efficiently converted into acoustic energy atthe glottis. A vocalist's vibration velocity patterns may thereforeindicate his or her phonatory status or singing skills. LDVs enablelaser-based non-contact measurement of the vibration velocity anddisplacement of a certain point on a vibrating object, and scanningLDVs permit multipoint measurements. The benefits of scanning LDVsoriginate from the facts that they do not affect the vibrations ofmeasured objects and that they can rapidly measure the vibrationpatterns across planes. A case study is presented herein todemonstrate the method of measuring vibration velocity patterns with ascanning LDV. The objective of the experiment was to measure thevibration velocity differences between the modal and falsettoregisters while three professional soprano singers sang sustainedvowels at four pitch frequencies. The results suggest that there is apossibility that pitch frequency are correlated with vibrationvelocity. However, further investigations are necessary to clarify therelationships between vibration velocity patterns and phonation statusand singing skills.

  17. Shock Initiation of Wedge-shaped Explosive Measured with Smear Camera and Photon Doppler Velocimetry

    Science.gov (United States)

    Gu, Yan

    2017-06-01

    Triaminotrinitrobenzene (TATB) is an important insensitive high explosive in conventional weapons due to its safety and high energy. In order to have an insight into the shock initiation performance of a TATB-based insensitive high explosive (IHE), experimental measurements of the particle velocity histories of the TATB-based Explosive using Photon Doppler Velocimetry and shock wave profile of the TATB-based explosive using High Speed Rotating Mirror Smear Camera had been performed. In this paper, we would describe the shock initiation performance of the TATB-based explosive by run-to-detonation distance and the particle velocity history at an initialization shock of about 7.9 GPa. The parameters of hugoniot of unreacted the TATB-based explosive and Pop relationship could be derived with the particle velocity history obtained in this paper.

  18. A study of the river velocity measurement techniques and analysis methods

    Science.gov (United States)

    Chung Yang, Han; Lun Chiang, Jie

    2013-04-01

    Velocity measurement technology can be traced back to the pitot tube velocity measurement method in the 18th century and today's velocity measurement technology use the acoustic and radar technology, with the Doppler principle developed technology advances, in order to develop the measurement method is more suitable for the measurement of velocity, the purpose is to get a more accurate measurement data and with the surface velocity theory, the maximum velocity theory and the indicator theory to obtain the mean velocity. As the main research direction of this article is to review the literature of the velocity measurement techniques and analysis methods, and to explore the applicability of the measurement method of the velocity measurement instruments, and then to describe the advantages and disadvantages of the different mean velocity profiles analysis method. Adequate review of the references of this study will be able to provide a reference for follow-up study of the velocity measurement. Review velocity measurement literature that different velocity measurement is required to follow the different flow conditions measured be upgraded its accuracy, because each flow rate measurement method has its advantages and disadvantages. Traditional velocity instrument can be used at low flow and RiverRAD microwave radar or imaging technology measurement method may be applied in high flow. In the tidal river can use the ADCP to quickly measure river vertical velocity distribution. In addition, urban rivers may be used the CW radar to set up on the bridge, and wide rivers can be used RiverRAD microwave radar to measure the velocities. Review the relevant literature also found that using Ultrasonic Doppler Current Profiler with the Chiu's theory to the velocity of observing automation work can save manpower and resources to improve measurement accuracy, reduce the risk of measurement, but the great variability of river characteristics in Taiwan and a lot of drifting floating

  19. Evaluation of Normal Erectile Function with Duplex Color Doppler Sonography after lntracavernosaI Injection of Prostaglandin E1 : Optimal Site and Time of Doppler Measurement

    International Nuclear Information System (INIS)

    Kim, Jong Min; Oh, Kyung Seoung; Jung, Gyoo Sik; Huh, Jin Do; Joh, Yong Kuk; Choi, Seong

    1995-01-01

    We performed color Doppler sonography(CDS) to examine the erectile process in normal volunteer for evaluating the proper time and adequate site for sampling volume of penile cavernous artery after intracorporeal injection of prostaglandin E1 (PGE1). 23 normal volunteers(mean age 22 years) were examined. CDS of both cavernous arteries was performed consecutively during 30∼40 minutes after injection of PGE1 to evaluate peak systolic and end diastolic velocities. We measured the peak systolic velocities at three differentiates along the right cavernous artery to evaluate the velocities and to determine the most proper site at which the Doppler angle could be optimally made. The mean value of maximal peak systolic of right and left cavernous arteries were 61.0 and 58.8 cm/sec with mean time-to-peak of 10.8 and 13.4 minutes respectively, and confidence interval between 9.6∼12 minutes (P<0.05) on the right. The mean value of minimal diastoic velocities were -4.8 and -3.5 cm/sec with reaching times of 8.7 and 8.2 minutes respectively, and confidence interval between∼10.3 minutes (P<0.05) on the right. The peak systolic velocities at three sites (A, B, C) along the right cavernous artery were 773.6, 53.1, 36.3 cm/sec from proximal site A to distal site C. The site A was suitable for maintenance of proper Doppler angle. CDS of the penis should be examined between 7.1∼12 minites after intracorporeal injection of PGE1 at site A (at penile base)

  20. Evaluation of Normal Erectile Function with Duplex Color Doppler Sonography after lntracavernosaI Injection of Prostaglandin E1 : Optimal Site and Time of Doppler Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Min; Oh, Kyung Seoung; Jung, Gyoo Sik; Huh, Jin Do; Joh, Yong Kuk; Choi, Seong [Kosin Medical College, Busan (Korea, Republic of)

    1995-12-15

    We performed color Doppler sonography(CDS) to examine the erectile process in normal volunteer for evaluating the proper time and adequate site for sampling volume of penile cavernous artery after intracorporeal injection of prostaglandin E1 (PGE1). 23 normal volunteers(mean age 22 years) were examined. CDS of both cavernous arteries was performed consecutively during 30{approx}40 minutes after injection of PGE1 to evaluate peak systolic and end diastolic velocities. We measured the peak systolic velocities at three differentiates along the right cavernous artery to evaluate the velocities and to determine the most proper site at which the Doppler angle could be optimally made. The mean value of maximal peak systolic of right and left cavernous arteries were 61.0 and 58.8 cm/sec with mean time-to-peak of 10.8 and 13.4 minutes respectively, and confidence interval between 9.6{approx}12 minutes (P<0.05) on the right. The mean value of minimal diastoic velocities were -4.8 and -3.5 cm/sec with reaching times of 8.7 and 8.2 minutes respectively, and confidence interval between{approx}10.3 minutes (P<0.05) on the right. The peak systolic velocities at three sites (A, B, C) along the right cavernous artery were 773.6, 53.1, 36.3 cm/sec from proximal site A to distal site C. The site A was suitable for maintenance of proper Doppler angle. CDS of the penis should be examined between 7.1{approx}12 minites after intracorporeal injection of PGE1 at site A (at penile base)

  1. Measurement of Plasma Ion Temperature and Flow Velocity from ...

    Indian Academy of Sciences (India)

    304. Xu Wei where ν0 is the flow velocity vector. The uniform flow in the absence of any other mechanism is delta function (Xu 2003): f (λ) = δ. [ λ − λc. (. 1 − ν0 c cos θ. )] = δ. [ x + λc ν0 c cos θ. ] , where x = λ − λc. The line profile due to Doppler broadening and Doppler shift is the convolution of the two profile functions: f (y) =.

  2. Acoustic doppler methods for remote measurements of ocean flows - a review

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.

    The evolution of acoustic doppler methods for remote measurements of ocean flows has been briefly reviewed in historical perspective. Both Eulerian and profiling methods have been discussed. Although the first acoustic Doppler current meter has been...

  3. Heart rate and flow velocity variability as determined from umbilical Doppler velocimetry at 10-20 weeks of gestation.

    Science.gov (United States)

    Ursem, N T; Struijk, P C; Hop, W C; Clark, E B; Keller, B B; Wladimiroff, J W

    1998-11-01

    1. The aim of this study was to define from umbilical artery flow velocity waveforms absolute peak systolic and time-averaged velocity, fetal heart rate, fetal heart rate variability and flow velocity variability, and the relation between fetal heart rate and velocity variables in early pregnancy.2.A total of 108 women presenting with a normal pregnancy from 10 to 20 weeks of gestation consented to participate in a cross-sectional study design. Doppler ultrasound recordings were made from the free-floating loop of the umbilical cord.3. Umbilical artery peak systolic and time-averaged velocity increased at 10-20 weeks, whereas fetal heart rate decreased at 10-15 weeks of gestation and plateaued thereafter. Umbilical artery peak systolic velocity variability and fetal heart rate variability increased at 10-20 and 15-20 weeks respectively.4. The inverse relationship between umbilical artery flow velocity and fetal heart rate at 10-15 weeks of gestation suggests that the Frank-Starling mechanism regulates cardiovascular control as early as the late first and early second trimesters of pregnancy. A different underlying mechanism is suggested for the observed variability profiles in heart rate and umbilical artery peak systolic velocity. It is speculated that heart rate variability is mediated by maturation of the parasympathetic nervous system, whereas peak systolic velocity variability reflects the activation of a haemodynamic feedback mechanism.

  4. Ultrasonic velocity measurements in expanded liquid mercury

    International Nuclear Information System (INIS)

    Suzuki, K.; Inutake, M.; Fujiwaka, S.

    1977-10-01

    In this paper we present the first results of the sound velocity measurements in expanded liquid mercury. The measurements were made at temperatures up to 1600 0 C and pressures up to 1700 kg/cm 2 by means of an ultrasonic pulse transmission/echo technique which was newly developed for such high temperature/pressure condition. When the density is larger than 9 g/cm 3 , the observed sound velocity decreases linearly with decreasing density. At densities smaller than 9 g/cm 3 , the linear dependence on the density is no longer observed. The observed sound velocity approaches a minimum near the liquid-gas critical point (rho sub(cr) asymptotically equals 5.5 g/cm 3 ). The existing theories for sound velocity in liquid metals fail to explain the observed results. (auth.)

  5. Measuring Velocity and Acceleration Using Doppler Shift of a ...

    Indian Academy of Sciences (India)

    effects, which is a form of the general principle of relativity, demands T = ¯T and. T = ¯T . Then, time runs at the ... assuming, additionally to the constancy of speed of light, certain special (inertial) kind of observers. We also ..... However, it is easy to see that this 'correct' special relativistic formula contradicts the results of the ...

  6. Thermal tests for laser Doppler perfusion measurements in Raynaud's syndrome

    Science.gov (United States)

    Kacprzak, Michal; Skora, A.; Obidzinska, J.; Zbiec, A.; Maniewski, Roman; Staszkiewicz, W.

    2004-07-01

    The laser Doppler method offers a non-invasive, real time technique for monitoring of blood perfusion in microcirculation. In practical measurements the perfusion index is given only in relative values. Thus, accurate and reproducible results can be only obtained when using a well controlled stimulation test. The aim of this study was evaluation of the thermal stimulation test, which is frequently used to investigate microcirculation in patients with Raynaud's syndrome. Three types of thermal tests, in which air or water with temperature in range 5°C - 40°C were used. Ten normal volunteers and fifteen patients with clinical symptoms of the primary Raynaud's syndrome were enrolled in this study. To estimate skin microcirculation changes during the thermal test, the multichannel laser Doppler system and laser Doppler scanner were used. The obtained results were analyzed from the point of view of the efficiency of these methods and the thermal provocative tests in differentiation of normal subjects and patient with Raynaud's syndrome.

  7. Magnetostriction measurement in thin films using laser Doppler vibrometry

    International Nuclear Information System (INIS)

    Varghese, Ronnie; Viswan, Ravindranath; Joshi, Keyur; Seifikar, Safoura; Zhou, Yuan; Schwartz, Justin; Priya, Shashank

    2014-01-01

    This paper reports the laser Doppler vibrometry based measurement of the magnetostriction in magnetic thin films. Using this method, the strain induced by an AC magnetic field in the polycrystalline cobalt ferrite and nickel ferrite thin films grown on silicon and platinized silicon substrates was measured under a DC magnetic bias. The experimental setup and the derivation of the magnetostriction constant from the experimentally measured deflection values are discussed. The magnetostriction values derived using force and bending moment balances were compared with that derived from an industry standard relationship. In addition, we corroborate our approach by comparing the values derived from bending theory calculations of magnetically induced torque to those from measurements using Vibrating Sample Magnetometer (VSM). At high DC magnetic field bias, the magnitude of magnetization calculated from the measured magnetostriction was found to match the measured magnetization by VSM. - Highlights: • Laser Doppler vibrometry based technique to measure magnetostriction in thin films. • Strain induced by an AC magnetic field under a DC magnetic bias. • Picometer level deflections in polycrystalline cobalt and nickel ferrite thin films

  8. Radar Measurement of Human Polarimetric Micro-Doppler

    Directory of Open Access Journals (Sweden)

    David Tahmoush

    2013-01-01

    Full Text Available We use polarimetric micro-Doppler for the detection of arm motion, especially for the classification of whether someone has their arms swinging and is thus unloaded. The arm is often bent at the elbow, providing a surface somewhat similar to a dihedral. This is distinct from the more planar surfaces of the body which allows us to isolate the signals of the arm (and knee. The dihedral produces a double bounce that can be seen in polarimetric radar data by measuring the phase difference between HH and VV. This measurement can then be used to determine whether the subject is unloaded.

  9. Doppler lidar measurement of profiles of turbulence and momentum flux

    Science.gov (United States)

    Eberhard, Wynn L.; Cupp, Richard E.; Healy, Kathleen R.

    1989-01-01

    A short-pulse CO2 Doppler lidar with 150-m range resolution measured vertical profiles of turbulence and momentum flux. Example measurements are reported of a daytime mixed layer with strong mechanical mixing caused by a wind speed of 15 m/sec, which exceeded the speed above the capping inversion. The lidar adapted an azimuth scanning technique previously demonstrated by radar. Scans alternating between two elevation angles allow determination of mean U-squared, V-squared, and W-squared. Expressions were derived to estimate the uncertainty in the turbulence parameters. A new processing method, partial Fourier decomposition, has less uncertainty than the filtering used earlier.

  10. Corrected tetralogy of Fallot: comparison of tissue doppler imaging and velocity-encoded MR for assessment of performance and temporal activation of right ventricle

    NARCIS (Netherlands)

    van der Hulst, Annelies E.; Roest, Arno A. W.; Delgado, Victoria; Kroft, Lucia J. M.; Holman, Eduard R.; Blom, Nico A.; Bax, Jeroen J.; de Roos, Albert; Westenberg, Jos J. M.

    2011-01-01

    To compare velocity-encoded (VE) magnetic resonance (MR) imaging with tissue Doppler imaging to assess right ventricular (RV) peak systolic velocities and timing of velocities in patients with corrected tetralogy of Fallot and healthy subjects. Local institutional review board approval was obtained;

  11. Influence of myocardial infarction size on radionuclide and Doppler echocardiographic measurements of diastolic function

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, K.A.; Cerqueira, M.D.; Stratton, J.R. (Seattle Veterans Administration Medical Center, WA (USA))

    1990-03-15

    To assess the relation between myocardial infarction size and diastolic function as measured by radionuclide ventriculography and Doppler echocardiography, 83 patients (aged 58 +/- 9 years) without significant valvular disease were studied 8 to 12 weeks after an acute myocardial infarction. Myocardial infarction size was measured by resting thallium-201 tomography. Peak early filling rate (in end-diastolic volumes/s) was measured by gated blood pool scintigraphy. Doppler measures of mitral inflow were peak early (E) and atrial (A) filling velocities, slopes of E and A, percent E and A filling, E/A ratio and diastolic filling period. In univariate analyses, there was a significant inverse correlation between infarction size and the peak early filling rate (r = -0.59, p less than 0.001), and this remained significant (r = -0.63, p less than 0.0001) in an analysis that included 2 other determinants of the filling rate, age and diastolic filling period. Infarction size was directly correlated to the peak E velocity (r = 0.37, p less than 0.01), deceleration of E (r = 0.41, p less than 0.01) and percent E filling (r = 0.31, p less than 0.01), and was inversely correlated to peak A (r = -0.27, p less than 0.05) and percent A filling (r = -0.26, p less than 0.05).

  12. Analysis of airborne Doppler lidar, Doppler radar and tall tower measurements of atmospheric flows in quiescent and stormy weather

    Science.gov (United States)

    Bluestein, H. B.; Doviak, R. J.; Eilts, M. D.; Mccaul, E. W.; Rabin, R.; Sundara-Rajan, A.; Zrnic, D. S.

    1986-01-01

    The first experiment to combine airborne Doppler Lidar and ground-based dual Doppler Radar measurements of wind to detail the lower tropospheric flows in quiescent and stormy weather was conducted in central Oklahoma during four days in June-July 1981. Data from these unique remote sensing instruments, coupled with data from conventional in-situ facilities, i.e., 500-m meteorological tower, rawinsonde, and surface based sensors, were analyzed to enhance understanding of wind, waves and turbulence. The purposes of the study were to: (1) compare winds mapped by ground-based dual Doppler radars, airborne Doppler lidar, and anemometers on a tower; (2) compare measured atmospheric boundary layer flow with flows predicted by theoretical models; (3) investigate the kinematic structure of air mass boundaries that precede the development of severe storms; and (4) study the kinematic structure of thunderstorm phenomena (downdrafts, gust fronts, etc.) that produce wind shear and turbulence hazardous to aircraft operations. The report consists of three parts: Part 1, Intercomparison of Wind Data from Airborne Lidar, Ground-Based Radars and Instrumented 444 m Tower; Part 2, The Structure of the Convective Atmospheric Boundary Layer as Revealed by Lidar and Doppler Radars; and Part 3, Doppler Lidar Observations in Thunderstorm Environments.

  13. A technique to measure the size of particles in laser Doppler velocimetry applications

    Science.gov (United States)

    Hess, C. F.

    1985-01-01

    A method to measure the size of particles in Laser Doppler Velocimeter (LDV) applications is discussed. Since in LDV the velocity of the flow is assocated with the velocity of particles to establish how well they follow the flow, in the present method the interferometric probe volume is surrounded by a larger beam of different polarization or wavelength. The particle size is then measured from the absolute intensity scattered from the large beam by particles crossing the fringes. Experiments using polystrene particles between 1.1 and 3.3 microns and larger glass beads are reported. It is shown that the method has an excellent size resolution and its accuracy is better than 10% for the particle size studied.

  14. MEASUREMENTS IN A LIQUID ATOMISER SPRAY USING THE PHASE-DOPPLER PARTICLE ANALYSER

    Directory of Open Access Journals (Sweden)

    R HADEF

    2000-12-01

    Full Text Available Experiments have been carried out at atmospheric conditions using a water atomiser spray. A phase Doppler anemometry was used to perform the measurements of the droplets size, their velocity and concentration, and photographs were taken.  The results showed that the small particles with low turbulence occupied the central core of the jet displaying a Gaussian profile for the axial velocity component.  The large particles were defected towards the outer edges of the jet, due to their higher initial momentum, and displayed relatively high levels of turbulence. The variables measured show that their spatial distributions were nearly symmetrical about the x-axis and although the number density of the droplets is very high in the centred region, most of the pulverised liquid was present in the edges of the spray.

  15. Laser-Doppler Velocimetry Measurements Inside a Backward Curved Centrifugal Fan

    Directory of Open Access Journals (Sweden)

    Tong-Miin Liou

    2001-01-01

    Full Text Available Laser-Doppler velocimetry (LDV measurements are presented of relative mean velocity and turbulence intensity components inside the impeller passage of a centrifugal fan with twelve backward curved blades at design, under-design, and over-design flow rates. Additional LDV measurements were also performed at the volute outlet to examine the uniformity of the outlet flow for the three selected flow rates. Complementary flow visualization results in the tongue region are further presented. It is found that the number of characteristic flow regions and the average turbulence level increase with decreasing air flow rate. For the case of under-design flow rate, there are a through-flow region on the suction side, a reverse flow region on the pressure side, and a shear layer region in between. The corresponding average turbulence intensity is as high as 9.1% of blade tip velocity.

  16. A New Ka-Band Scanning Radar Facility: Polarimetric and Doppler Spectra Measurements of Snow Events

    Science.gov (United States)

    Oue, M.; Kollias, P.; Luke, E. P.; Mead, J.

    2017-12-01

    Polarimetric radar analyses offer the capability of identification of ice hydrometeor species as well as their spatial distributions. In addition to polarimetric parameter observations, Doppler spectra measurements offer unique insights into ice particle properties according to particle fall velocities. In particular, millimeter-wavelength radar Doppler spectra can reveal supercooled liquid cloud droplets embedded in ice precipitation clouds. A Ka-band scanning polarimetric radar, named KASPR, was installed in an observation facility at Stony Brook University, located 22 km west of the KOKX NEXRAD radar at Upton, NY. The KASPR can measure Doppler spectra and full polarimetric variables, including radar reflectivity, differential reflectivity (ZDR), differential phase (φDP), specific differential phase (KDP), correlation coefficient (ρhv), and linear depolarization ratio (LDR). The facility also includes a micro-rain radar and a microwave radiometer capable of measuring reflectivity profiles and integrated liquid water path, respectively. The instruments collected initial datasets during two snowstorm events and two snow shower events in March 2017. The radar scan strategy was a combination of PPI scans at 4 elevation angles (10, 20, 45, and 60°) and RHI scans in polarimetry mode, and zenith pointing with Doppler spectra collection. During the snowstorm events the radar observed relatively larger ZDR (1-1.5 dB) and enhanced KDP (1-2 ° km-1) at heights corresponding to a plate/dendrite crystal growth regime. The Doppler spectra showed that slower-falling particles ( 1 m s-1). The weakly increased ZDR could be produced by large, faster falling particles such as quasi-spherical aggregates, while the enhanced KDP could be produced by highly-oriented oblate, slowly-falling particles. Below 2 km altitude, measurements of dual wavelength ratio (DWR) based on Ka and S-band reflectivities from the KASPR and NEXRAD radars were available. Larger DWR (>10 dB) suggested

  17. ACHIEVING CONSISTENT DOPPLER MEASUREMENTS FROM SDO /HMI VECTOR FIELD INVERSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Schuck, Peter W. [Space Weather Laboratory, Code 674, Heliophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt, MD 20771 (United States); Antiochos, S. K. [Heliophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd., Greenbelt, MD 20771 (United States); Leka, K. D.; Barnes, Graham, E-mail: peter.schuck@nasa.gov, E-mail: spiro.antiochos@nasa.gov, E-mail: leka@nwra.com, E-mail: graham@nwra.com [NorthWest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

    2016-06-01

    NASA’s Solar Dynamics Observatory is delivering vector magnetic field observations of the full solar disk with unprecedented temporal and spatial resolution; however, the satellite is in a highly inclined geosynchronous orbit. The relative spacecraft–Sun velocity varies by ±3 km s{sup −1} over a day, which introduces major orbital artifacts in the Helioseismic Magnetic Imager (HMI) data. We demonstrate that the orbital artifacts contaminate all spatial and temporal scales in the data. We describe a newly developed three-stage procedure for mitigating these artifacts in the Doppler data obtained from the Milne–Eddington inversions in the HMI pipeline. The procedure ultimately uses 32 velocity-dependent coefficients to adjust 10 million pixels—a remarkably sparse correction model given the complexity of the orbital artifacts. This procedure was applied to full-disk images of AR 11084 to produce consistent Dopplergrams. The data adjustments reduce the power in the orbital artifacts by 31 dB. Furthermore, we analyze in detail the corrected images and show that our procedure greatly improves the temporal and spectral properties of the data without adding any new artifacts. We conclude that this new procedure makes a dramatic improvement in the consistency of the HMI data and in its usefulness for precision scientific studies.

  18. Minimally destructive, Doppler measurement of a quantized flow in a ring-shaped Bose-Einstein condensate

    Science.gov (United States)

    Kumar, A.; Anderson, N.; Phillips, W. D.; Eckel, S.; Campbell, G. K.; Stringari, S.

    2016-02-01

    The Doppler effect, the shift in the frequency of sound due to motion, is present in both classical gases and quantum superfluids. Here, we perform an in situ, minimally destructive measurement, of the persistent current in a ring-shaped, superfluid Bose-Einstein condensate using the Doppler effect. Phonon modes generated in this condensate have their frequencies Doppler shifted by a persistent current. This frequency shift will cause a standing-wave phonon mode to be ‘dragged’ along with the persistent current. By measuring this precession, one can extract the background flow velocity. This technique will find utility in experiments where the winding number is important, such as in emerging ‘atomtronic’ devices.

  19. Wave Measurements Using GPS Velocity Signals

    Directory of Open Access Journals (Sweden)

    Chia Chuen Kao

    2011-01-01

    Full Text Available This study presents the idea of using GPS-output velocity signals to obtain wave measurement data. The application of the transformation from a velocity spectrum to a displacement spectrum in conjunction with the directional wave spectral theory are the core concepts in this study. Laboratory experiments were conducted to verify the accuracy of the inversed displacement of the surface of the sea. A GPS device was installed on a moored accelerometer buoy to verify the GPS-derived wave parameters. It was determined that loss or drifting of the GPS signal, as well as energy spikes occurring in the low frequency band led to erroneous measurements. Through the application of moving average skill and a process of frequency cut-off to the GPS output velocity, correlations between GPS-derived, and accelerometer buoy-measured significant wave heights and periods were both improved to 0.95. The GPS-derived one-dimensional and directional wave spectra were in agreement with the measurements. Despite the direction verification showing a 10° bias, this exercise still provided useful information with sufficient accuracy for a number of specific purposes. The results presented in this study indicate that using GPS output velocity is a reasonable alternative for the measurement of ocean waves.

  20. Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

    Directory of Open Access Journals (Sweden)

    Ovandir Bazan

    2013-12-01

    Full Text Available INTRODUCTION: In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. OBJECTIVE: To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. METHODS: To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. RESULTS: It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. CONCLUSIONS: Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM is superior to the 21 AJ - 501 model (Master Series. Based on the results, future studies can choose to focus on specific regions of the these valves.

  1. Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

    Science.gov (United States)

    Bazan, Ovandir; Ortiz, Jayme Pinto; Vieira Junior, Francisco Ubaldo; Vieira, Reinaldo Wilson; Antunes, Nilson; Tabacow, Fabio Bittencourt Dutra; Costa, Eduardo Tavares; Petrucci Junior, Orlando

    2013-01-01

    Introduction In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. Objective To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. Methods To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. ) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. Results It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. Conclusions Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves. PMID:24598950

  2. Novel laser Doppler flowmeter for pulpal blood flow measurements

    Science.gov (United States)

    Zang, De Yu; Millerd, James E.; Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.

    1996-04-01

    We have proposed and experimentally demonstrated a new configuration of laser Doppler flowmetry for dental pulpal blood flow measurements. To date, the vitality of a tooth can be determined only by subjective thermal or electric tests, which are of questionable reliability and may induced pain in patient. Non-invasive techniques for determining pulpal vascular reactions to injury, treatment, and medication are in great demand. The laser Doppler flowmetry technique is non-invasive; however, clinical studies have shown that when used to measure pulpal blood flow the conventional back-scattering Doppler method suffers from low signal-to-noise ratio (SNR) and unreliable flux readings rendering it impossible to calibrate. A simplified theoretical model indicates that by using a forward scattered geometry the detected signal has a much higher SNR and can be calibrated. The forward scattered signal is readily detectable due to the fact that teeth are relatively thin organs with moderate optical loss. A preliminary experiment comparing forward scattered detection with conventional back- scattered detection was carried out using an extracted human molar. The results validated the findings of the simple theoretical model and clearly showed the utility of the forward scattering geometry. The back-scattering method had readings that fluctuated by as much as 187% in response to small changes in sensor position relative to the tooth. The forward scattered method had consistent readings (within 10%) that were independent of the sensor position, a signal-to-noise ratio that was at least 5.6 times higher than the back-scattering method, and a linear response to flow rate.

  3. Stochastic method for turbulence estimation from Doppler lidar measurements

    Science.gov (United States)

    Rottner, Lucie; Baehr, Christophe; Dabas, Alain; Hammoud, Linda

    2017-10-01

    The Doppler lidar technology is known for its ability to measure accurate winds with fine time and space resolutions. The derivation of turbulence parameters from lidar wind measurement has been attempted by several authors. All of them relate the turbulence parameters to long-time series (several tens of minutes) of wind measurements. The method presented here retrieves estimations of the atmospheric turbulence at much finer time scales. The technique is based on a wind reconstruction method applied to a five-beam wind Doppler lidar (namely the WindCube model by Leosphere). The method relies on a particle filter. The suggested reconstruction algorithm links the lidar observations to numerical particles to obtain turbulence estimations every time new observations are available. The high frequency of the estimations is an innovation and is detailed and discussed here. Moreover, the presented algorithm enables reconstruction of the wind in three dimensions in the observed volume. Thus, we locally have access to the spatial variability of the turbulent atmosphere. The suggested algorithm is applied to a set of real observations. The results show that the estimation of the turbulent parameters is significantly improved. They open the way to the use of lidars for scientific and industrial purposes such as site studies for wind farms.

  4. Cerebral hemispheric blood flow velocity differences in left- and right- handers: functional trans-cranial Doppler ultrasonography

    Directory of Open Access Journals (Sweden)

    Sikaroodi H

    2009-12-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: It is a well known fact that language functions are primarily related to the left hemisphere in right handed individuals, there is still no agreement about hemispheric language dominance in left handers. The aim of this study is to evaluate the possibility of using functional Transcranial Doppler ultra sonography (TCD, as a non-invasive method for investigation of hemispheric language dominance and also to explore possible gender influence on hemispheric language representation."n"nMethods: We performed functional TCD during a word generation task, in 62 healthy volunteers (30 right handers and 32 left handers, 50% male and 50% female. All subjects were medical students in the age range of 22-29 years. Right or left handedness was determined using Edinburgh questionnaire. Two subjects were excluded from the study because of poor temporal windows. Mean blood flow velocity was measured in both right and left middle cerebral arteries (MCA at rest and during a word generation task, and changes in flow velocities were compared."n"nResults: Increase of MCA blood flow velocity was observed in 55% (33 subjects of the students in the left side, and in 45% (27 subjects of them in the right side. Right hemispheric

  5. Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

    Science.gov (United States)

    Tylka, Jonathan

    2016-01-01

    Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

  6. Transcranial Doppler ultrasonography in children with sickle cell anemia: Clinical and laboratory correlates for elevated blood flow velocities.

    Science.gov (United States)

    Lagunju, IkeOluwa; Sodeinde, Olugbemiro; Brown, Biobele; Akinbami, Felix; Adedokun, Babatunde

    2014-02-01

    Transcranial Doppler (TCD) sonography of major cerebral arteries is now recommended for routine screening for stroke risk in children with sickle cell disease (SCD). We performed TCD studies on children with sickle cell anemia (SCA) seen at the pediatric hematology clinic over a period of 2 years. TCD scans were repeated yearly in children with normal flow velocities and every 3 months in children with elevated velocities. Findings were correlated with clinical variables, hematologic indices, and arterial oxygen saturation. Predictors of elevated velocities were identified by multiple linear regressions. We enrolled 237 children and performed a total of 526 TCD examinations. Highest time-averaged maximum flow velocities were ≥170 cm/s in 72 (30.3%) cases and ≥200 cm/s in 20 (8.4%). Young age, low hematocrit, low hemoglobin, and arterial oxygen desaturation <95% showed significant correlations with presence of increased cerebral flow velocities. Low hematocrit, low hemoglobin concentration, young age, and low arterial oxygen desaturation predicted elevated cerebral blood flow velocities and, invariably, increased stroke risk, in children with SCA. Children who exhibit these features should be given high priority for TCD examination in the setting of limited resources. Copyright © 2013 Wiley Periodicals, Inc.

  7. Measurement of velocity deficit at the downstream of a 1:10 axial hydrokinetic turbine model

    Energy Technology Data Exchange (ETDEWEB)

    Gunawan, Budi [ORNL; Neary, Vincent S [ORNL; Hill, Craig [St. Anthony Falls Laboratory, 2 Third Avenue SE, Minneapolis, MN 55414; Chamorro, Leonardo [St. Anthony Falls Laboratory, 2 Third Avenue SE, Minneapolis, MN 55414

    2012-01-01

    Wake recovery constrains the downstream spacing and density of turbines that can be deployed in turbine farms and limits the amount of energy that can be produced at a hydrokinetic energy site. This study investigates the wake recovery at the downstream of a 1:10 axial flow turbine model using a pulse-to-pulse coherent Acoustic Doppler Profiler (ADP). In addition, turbine inflow and outflow velocities were measured for calculating the thrust on the turbine. The result shows that the depth-averaged longitudinal velocity recovers to 97% of the inflow velocity at 35 turbine diameter (D) downstream of the turbine.

  8. A method for estimating the turbulent kinetic energy dissipation rate from a vertically pointing Doppler lidar, and independent evaluation from balloon-borne in situ measurements

    OpenAIRE

    O'Connor, Ewan J.; Illingworth, Anthony J.; Brooks, Ian M.; Westbrook, Christopher D.; Hogan, Robin J.; Davies, Fay; Brooks, Barbara J.

    2010-01-01

    A method of estimating dissipation rates from a vertically pointing Doppler lidar with high temporal and spatial resolution has been evaluated by comparison with independent measurements derived from a balloon-borne sonic anemometer. This method utilizes the variance of the mean Doppler velocity from a number of sequential samples and requires an estimate of the horizontal wind speed. The noise contribution to the variance can be estimated from the observed signal-to-noise ratio and removed w...

  9. In vivo lateral blood flow velocity measurement using speckle size estimation.

    Science.gov (United States)

    Xu, Tiantian; Hozan, Mohsen; Bashford, Gregory R

    2014-05-01

    In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method

  10. Application of low-coherence optical fiber Doppler anemometry to fluid-flow measurement: optical system considerations

    Science.gov (United States)

    Boyle, William J. O.; Grattan, Kenneth T. V.; Palmer, Andrew W.; Meggitt, B. T.

    1991-08-01

    A fiber optic Doppler anemometric (FODA) sensor using an optical delay cavity technique and having the advantage of detecting velocity rather than simple speed is outlined. In this sensor the delay in a sensor cavity formed from light back-reflected from a fiber tip (Fresnel reflection) and light back-reflected from particles flowing in a fluid is balanced by the optical delay when light from this sensor cavity passes through a reference cavity formed by a combination of the zero and first diffraction orders produced by a Bragg cell inserted into the optical arrangement. The performance of an experimental sensor based on this scheme is investigated, and velocity measurements using the Doppler shift data from moving objects are presented. The sensitivity of the scheme is discussed, with reference to the other techniques of fluid flow measurement.

  11. Measurement of acoustic streaming in a standing wave using laser Doppler anemometry

    Science.gov (United States)

    Thompson, Michael W.

    Laser Doppler anemometry (LDA) with burst spectrum analysis (BSA) is used to study the acoustic streaming generated in a cylindrical standing-wave resonator filled with air. The air column is driven sinusoidally at a frequency of approximately 310 Hz, and the resultant acoustic-velocity amplitudes are less than 1.3 m/s at the velocity antinodes. The axial component of fluid velocity is measured along the resonator axis, across the diameter, and as a function of acoustic amplitude. The velocity signals are post-processed using the Fourier averaging method [Sonnenberger et al., Exp. Fluids 28, 217--224 (2000)]. Equations are derived for determining the uncertainties in the resultant Fourier coefficients. The time-averaged velocity-signal components are seen to be contaminated by significant errors due to the LDA/BSA system. In order to avoid these errors, the Lagrangian streaming velocities are determined using the time-harmonic signal components and the arrival times of the velocity samples. The observed Lagrangian streaming velocities are consistent with Rott's theory [N. Rott, J. Appl. Math. Phys. (ZAMP) 25, 417--421 (1974)], indicating that the dependence of viscosity on temperature is important. The onset of streaming is observed to occur within approximately 5 s after switching on the acoustic field. The influences of a thermoacoustically induced axial temperature gradient and fluid inertia on the streaming are investigated using this same method. The axial component of Lagrangian streaming velocity is measured along the resonator axis and across the diameter at acoustic-velocity amplitudes of 2.7 m/s, 4.3 m/s, 6.1 m/s, and 8.6 m/s at the velocity antinodes. Measurements are repeated with the resonator either wrapped in foam insulation, surrounded by a water jacket, or suspended within an air-filled tank, in order to vary the magnitude of the axial temperature gradient. A significant correlation is observed between the temperature gradient and the behavior of

  12. Carotid stenosis measurement on colour Doppler ultrasound: Agreement of ECST, NASCET and CCA methods applied to ultrasound with intra-arterial angiographic stenosis measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wardlaw, Joanna M. [Division of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU (United Kingdom)]. E-mail: jmw@skull.dcn.ed.ac.uk; Lewis, Steff [Division of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh EH4 2XU (United Kingdom)

    2005-11-01

    Purpose: Carotid stenosis is usually determined on Doppler ultrasound from velocity readings. We wondered if angiography-style stenosis measurements applied to ultrasound images improved accuracy over velocity readings alone, and if so, which measure correlated best with angiography. Materials and methods: We studied prospectively patients undergoing colour Doppler ultrasound (CDU) for TIA or minor stroke. Those with 50%+ symptomatic internal carotid artery (ICA) stenosis had intra-arterial angiography (IAA). We measured peak systolic ICA velocity, and from the ultrasound image, the minimal residual lumen, the original lumen (ECST), ICA diameter distal (NASCET) and CCA diameter proximal (CCA method) to the stenosis. The IAAs were measured by ECST, NASCET and CCA methods also, blind to CDU. Results: Amongst 164 patients (328 arteries), on CDU the ECST, NASCET and CCA stenosis measures were similarly related to each other (ECST = 0.54 NASCET + 46) as on IAA (ECST = 0.6 NASCET + 40). Agreement between CDU- and IAA-measured stenosis was similar for ECST (r = 0.51), and CCA (r = 0.48) methods, and slightly worse for NASCET (r = 0.41). Adding IAA-style stenosis to the peak systolic ICA velocity did not improve agreement with IAA over peak systolic velocity alone. Conclusion: Angiography-style stenosis measures have similar inter-relationships when applied to CDU, but do not improve accuracy of ultrasound over peak systolic ICA velocity alone.

  13. Carotid stenosis measurement on colour Doppler ultrasound: Agreement of ECST, NASCET and CCA methods applied to ultrasound with intra-arterial angiographic stenosis measurement

    International Nuclear Information System (INIS)

    Wardlaw, Joanna M.; Lewis, Steff

    2005-01-01

    Purpose: Carotid stenosis is usually determined on Doppler ultrasound from velocity readings. We wondered if angiography-style stenosis measurements applied to ultrasound images improved accuracy over velocity readings alone, and if so, which measure correlated best with angiography. Materials and methods: We studied prospectively patients undergoing colour Doppler ultrasound (CDU) for TIA or minor stroke. Those with 50%+ symptomatic internal carotid artery (ICA) stenosis had intra-arterial angiography (IAA). We measured peak systolic ICA velocity, and from the ultrasound image, the minimal residual lumen, the original lumen (ECST), ICA diameter distal (NASCET) and CCA diameter proximal (CCA method) to the stenosis. The IAAs were measured by ECST, NASCET and CCA methods also, blind to CDU. Results: Amongst 164 patients (328 arteries), on CDU the ECST, NASCET and CCA stenosis measures were similarly related to each other (ECST = 0.54 NASCET + 46) as on IAA (ECST = 0.6 NASCET + 40). Agreement between CDU- and IAA-measured stenosis was similar for ECST (r = 0.51), and CCA (r = 0.48) methods, and slightly worse for NASCET (r = 0.41). Adding IAA-style stenosis to the peak systolic ICA velocity did not improve agreement with IAA over peak systolic velocity alone. Conclusion: Angiography-style stenosis measures have similar inter-relationships when applied to CDU, but do not improve accuracy of ultrasound over peak systolic ICA velocity alone

  14. Vector Flow Imaging Compared with Pulse Wave Doppler for Estimation of Peak Velocity in the Portal Vein

    DEFF Research Database (Denmark)

    Brandt, Andreas Hjelm; Moshavegh, Ramin; Hansen, Kristoffer Lindskov

    2018-01-01

    The study described here investigated whether angle-independent vector flow imaging (VFI) technique estimates peak velocities in the portal vein comparably to pulsed wave Doppler (PWD). Furthermore, intra- and inter-observer agreement was assessed in a substudy. VFI and PWD peak velocities were...... estimated with from intercostal and subcostal views for 32 healthy volunteers, and precision analyses were conducted. Blinded to estimates, three physicians rescanned 10 volunteers for intra- and inter-observer agreement analyses. The precision of VFI and PWD was 18% and 28% from an intercostal view and 23......% and 77% from a subcostal view, respectively. Bias between VFI and PWD was 0.57 cm/s (p = 0.38) with an intercostal view and 9.89 cm/s (p ...

  15. Preload dependence of color M-mode Doppler flow propagation velocity in controls and in patients with left ventricular dysfunction

    DEFF Research Database (Denmark)

    Møller, J E; Poulsen, S H; Søndergaard, E

    2000-01-01

    The purpose of this study was to assess the effects of preload alterations on color M-mode flow propagation velocity (Vp) in volunteers with normal left ventricular (LV) function and in patients with depressed LV function. Color M-mode Doppler echocardiography was performed during Valsalva maneuver......, passive leg lifting, and after administration of nitroglycerin in 30 healthy volunteers and in 30 age- and sex-matched patients with previous myocardial infarction (MI). Mean Vp in controls was 74 +/- 15 cm/s at baseline and 46 +/- 15 cm/s in MI patients (P .... In conclusion, we found that in controls and patients with previous MI, the color M-mode flow propagation velocity is not affected significantly by preload....

  16. Quantitative Doppler measures in coiled vessels: investigation on excised umbilical veins.

    Science.gov (United States)

    Guiot, C; Roatta, S; Piccoli, E; Saccomandi, F; Todros, T

    1999-11-01

    Quantitative assessment of umbilical venous blood velocity with Doppler ultrasound (US) must cope with the coiled structure of the vein inside the cord. Both an experimental and a theoretical approach showed remarkable variations in the insonation angle when the probe was moved along the vein, provided the inclination between the Doppler probe and the cord was kept constant. Inaccurate signal processing, stochastic variability and flow disturbances could, however, mask the influence of the geometry. The above hypotheses were assessed by investigating five cords in vitro a few hours after delivery from normal pregnancies at term. The Doppler signal was sampled at different sites along each cord and the mean Doppler shift estimated by FFT spectral analysis, both directly and through the noise rejection D'Alessio's algorithm, which proved effective in improving the Doppler shift estimate in condition of low signal-to-noise ratio (SNR).

  17. Wide angle Michelson Doppler imaging interferometer. [measuring atmospheric emissions

    Science.gov (United States)

    Shepherd, G. G.

    1980-01-01

    The optical system, stepping control, phase and modulation depth, array detector, and directions sensor are described for a specialized type of Michelson interferometer which works at sufficiently high resolution to measure the line widths and Doppler shifts of naturally occurring atmospheric emissions. With its imaging capability, the instrument can potentially supply this data independently for each element of the 100 x 100 detector array. The experiment seeks: (1) to obtain vertical profiles of atmospheric winds and temperatures as functions of latitude by observing near the limb; (2) to acquire exploratory wind and temperature data on smaller scale structures in airglow irregularities and in auroral forms; and (3) to collaborate with other Spacelab experiments, such as barium cloud releases, in providing wind and temperature data.

  18. [Doppler velocimetry measurement in pregnancy complicated with diabetes mellitus].

    Science.gov (United States)

    Gao, M Y

    1992-11-01

    To evaluate the effects of diabetes mellitus (DM) on fetoplacental circulation, Doppler velocimetry was carried out in diabetic pregnant women (n = 21) and normal pregnant controls (n = 20) every 2 weeks from the 20th week of gestation till term. Blood flow wave form of umbilical artery (Um) and uterine artery (Ut) were measured and the systolic/diastolic ratio (S/D) of Um and Ut calculated. The results showed that the Um and Ut S/D ratio of diabetic mothers with AGA babies (n = 15) and normal controls were not different. The S/D ratio of diabetic women with LGA newborns (n = 6) elevated after the 30th week of gestation, and the time of elevation was in accordance with the accelerating growth stage of LGA fetus. It is suggested that the elevation of S/D ratio may be related to the increasing requirement of blood supply for LGA babies in DM mother.

  19. Measurements of enlarged blood pump models using Laser Doppler Anemometer.

    Science.gov (United States)

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  20. Double-Edge Molecular Technique for Doppler Lidar Wind Measurement

    Science.gov (United States)

    Flesia, Cristina; Korb, C. Laurence

    1998-01-01

    The double-edge lidar technique for measuring the wind using molecular backscatter is described. Two high spectral resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and gives nearly a factor of two improvement in measurement accuracy. The use of a crossover region is described where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering over a frequency range of +/- 100 m/s. We give methods for correcting for short-term frequency jitter and drift using a laser reference frequency measurement and methods for long-term frequency correction using a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2 to 15 km for a 1 km vertical resolution, a satellite altitude of 400 km and a 200 km x 200 km spatial resolution. Results of ground based wind measurements are presented.

  1. Double-edge molecular technique for Doppler lidar wind measurement

    Science.gov (United States)

    Flesia, Cristina; Korb, C. L.

    1998-08-01

    The double-edge lidar technique for measuring the wind based upon using molecular backscatter is described. The technique uses two high spectral resolution edge filters which are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and gives nearly a factor of two improvement in measurement accuracy relative to the single edge technique. The use of a crossover region is described where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering over a frequency range of plus or minus 100 m/s. We give methods for correcting for short- term, shot to shot, frequency jitter and drift using a laser reference frequency measurement and methods for long-term frequency correction using a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2 - 3 m/s for altitudes of 2 to 15 km for a 1 km vertical resolution, a satellite altitude of 400 km and a 200 km X 200 km spatial resolution. Results for recent wind measurements, which show an accuracy of 1 m/s up to an altitude of 10 km, are given.

  2. Blood flow measurements during hemodialysis vascular access interventions - Catheter-based thermodilution or Doppler ultrasound?

    DEFF Research Database (Denmark)

    Heerwagen, Søren T; Hansen, Marc A; Schroeder, Torben V

    2012-01-01

    Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had...... access blood flow measured before and after every procedure. Two methods, catheter-based thermodilution and Doppler ultrasound, were compared to the reference method of ultrasound dilution. Catheter-based thermodilution and Doppler ultrasound were performed during the endovascular procedures while flow...

  3. The Effect of Amplitude Modulation on the Axial Resolution of Doppler-Based Ultrasonic Topography Measurement

    DEFF Research Database (Denmark)

    RezaNejad Gatabi, Javad; Das, Sayantan; Forouzbakhsh, Farshid

    2016-01-01

    Ultrasonic Doppler-based systems for surface topography measurements are attractive alternatives to the transit-time-based methods. Sensors used in Doppler systems are less dependent on the speed of the sound in air, although contemporary Doppler measurement systems are sensitive to the amplitude...... variation of the received signal. Amplitude variation significantly affects the measurement accuracy when the surface axial displacement range is comparable with the ultrasonic wavelength. This paper presents a theoretical and experimental study of the effect of amplitude modulation on the performance...... of the Doppler measurement techniques. A modified Doppler measurement system that significantly improves the measurement accuracy is also presented. The fabricated sensor has 72-μm measurement accuracy using 40-kHz transducers. This technique can also be employed in cost-effective displacement measurement...

  4. Experimental validation of uterine artery volume blood flow measurement by Doppler ultrasonography in pregnant sheep.

    Science.gov (United States)

    Acharya, G; Sitras, V; Erkinaro, T; Mäkikallio, K; Kavasmaa, T; Päkkilä, M; Huhta, J C; Räsänen, J

    2007-04-01

    To test the hypothesis that Doppler-derived (calculated) uterine artery volume blood flow (cQ(UtA)) reflects accurately volume blood flow measured directly (mQ(UtA)) in an experimental setting. Five pregnant sheep were instrumented at 122-130 days of gestation under general anesthesia. After a 4-day recovery period, maternal hemodynamics were varied by administering to the sheep under general anesthesia noradrenaline, beta-blocker, low oxygen gas mixture, epidural bupivacaine and ephedrine, consecutively. The central venous pressure was obtained with the help of a thermodilution catheter. The mean arterial pressure and acid-base status were monitored using a 16-gauge polyurethane catheter inserted into the descending aorta via a femoral artery. A 6-mm transit-time ultrasonic perivascular flow probe was used to measure the mQ(UtA). Doppler ultrasonography of the uterine artery was performed and volume blood flow was obtained simultaneously by the transit-time ultrasonic perivascular flow probe during each phase of the experiment. A total of 31 observations were made. The mQ(UtA) varied between 90 and 800 (mean +/- SD, 419 +/- 206) mL/min during the experiments. The corresponding values for the cQ(UtA) were 110 and 900 (mean +/- SD, 459 +/- 211) mL/min. There was a significant correlation (R = 0.76; P blood flow measured directly. Doppler-derived uterine artery absolute blood flow velocities reflect uteroplacental volume blood flow in pregnant sheep. Published by John Wiley & Sons, Ltd. Copyright (c) 2007 ISUOG.

  5. Comparison of balloon-carried atmospheric motion sensors with Doppler lidar turbulence measurements.

    Science.gov (United States)

    Harrison, R G; Heath, A M; Hogan, R J; Rogers, G W

    2009-02-01

    Magnetic sensors have been added to a standard weather balloon radiosonde package to detect motion in turbulent air. These measure the terrestrial magnetic field and return data over the standard uhf radio telemetry. Variability in the magnetic sensor data is caused by motion of the instrument package. A series of radiosonde ascents carrying these sensors has been made near a Doppler lidar measuring atmospheric properties. Lidar-retrieved quantities include vertical velocity (w) profile and its standard deviation (sigma(w)). sigma(w) determined over 1 h is compared with the radiosonde motion variability at the same heights. Vertical motion in the radiosonde is found to be robustly increased when sigma(w)>0.75 m s(-1) and is linearly proportional to sigma(w).

  6. Role of turbulence fluctuations on uncertainties of acoutic Doppler current profiler discharge measurements

    Science.gov (United States)

    Tarrab, Leticia; Garcia, Carlos M.; Cantero, Mariano I.; Oberg, Kevin

    2012-01-01

    This work presents a systematic analysis quantifying the role of the presence of turbulence fluctuations on uncertainties (random errors) of acoustic Doppler current profiler (ADCP) discharge measurements from moving platforms. Data sets of three-dimensional flow velocities with high temporal and spatial resolution were generated from direct numerical simulation (DNS) of turbulent open channel flow. Dimensionless functions relating parameters quantifying the uncertainty in discharge measurements due to flow turbulence (relative variance and relative maximum random error) to sampling configuration were developed from the DNS simulations and then validated with field-scale discharge measurements. The validated functions were used to evaluate the role of the presence of flow turbulence fluctuations on uncertainties in ADCP discharge measurements. The results of this work indicate that random errors due to the flow turbulence are significant when: (a) a low number of transects is used for a discharge measurement, and (b) measurements are made in shallow rivers using high boat velocity (short time for the boat to cross a flow turbulence structure).

  7. Validation of doppler lidar wind measurements with the local model of the german weather service

    Science.gov (United States)

    Werner, Christian; Leike, Ines; Streicher, Juergen; Reitebuch, Oliver; Cress, Alexander; Wergen, Werner

    2017-11-01

    Doppler lidars measure the range resolved Line-of-Sight (LOS) wind component by extracting the Doppler shift of radiation backscattered from atmospheric aerosols and molecules.The virtual instrument was tested with an existing airborne Doppler lidar to get confidence on the simulation.The local model (LM) of the German Weather Service produced data for all the levels in the atmosphere with the same information as for the global model within a finer grid (7km).

  8. Ultrasonic Measurement of Velocity Profile on Bubbly Flow Using Fast Fourier Transform (FFT) Technique

    Science.gov (United States)

    Wongsaroj, W.; Hamdani, A.; Thong-un, N.; Takahashi, H.; Kikura, H.

    2017-10-01

    In two-phase bubbly flow, measurement of liquid and bubble velocity is a necessity to understand fluid characteristic. The conventional ultrasonic velocity profiler (UVP), which has been known as a nonintrusive measurement technique, can measure velocity profile of liquid and bubble simultaneously by applying a separation technique for both phases (liquid and bubble) and transparent test section is unnecessary. The aim of this study was to develop a new technique for separating liquid and bubble velocity data in UVP method to measure liquid and bubble velocity profiles separately. The technique employs only single resonant frequency transducer and a simple UVP system. An extra equipment is not required. Fast Fourier Transform (FFT) based frequency estimator paralleled with other signal processing techniques, which is called as proposed technique, was proposed to measure liquid and bubble velocity separately. The experimental facility of two-phase bubbly flow in the vertical pipe was constructed. Firstly, the Doppler frequency estimation by using the FFT technique was evaluated in single-phase liquid flow. Results showed that FFT technique showed a good agreement with autocorrelation and maximum likelihood estimator. Then, separation of liquid and bubble velocity was demonstrated experimentally in the two-phase bubbly flow. The proposed technique confirmed that liquid and bubble velocity could be measured efficiently.

  9. Evaluation of the Wind Flow Variability Using Scanning Doppler Lidar Measurements

    Science.gov (United States)

    Sand, S. C.; Pichugina, Y. L.; Brewer, A.

    2016-12-01

    Better understanding of the wind flow variability at the heights of the modern turbines is essential to accurately assess of generated wind power and efficient turbine operations. Nowadays the wind energy industry often utilizes scanning Doppler lidar to measure wind-speed profiles at high spatial and temporal resolution.The study presents wind flow features captured by scanning Doppler lidars during the second Wind Forecast and Improvement Project (WFIP 2) sponsored by the Department of Energy (DOE) and National Oceanic and Atmospheric Administration (NOAA). This 18-month long experiment in the Columbia River Basin aims to improve model wind forecasts complicated by mountain terrain, coastal effects, and numerous wind farms.To provide a comprehensive dataset to use for characterizing and predicting meteorological phenomena important to Wind Energy, NOAA deployed scanning, pulsed Doppler lidars to two sites in Oregon, one at Wasco, located upstream of all wind farms relative to the predominant westerly flow in the region, and one at Arlington, located in the middle of several wind farms.In this presentation we will describe lidar scanning patterns capable of providing data in conical, or vertical-slice modes. These individual scans were processed to obtain 15-min averaged profiles of wind speed and direction in real time. Visualization of these profiles as time-height cross sections allows us to analyze variability of these parameters with height, time and location, and reveal periods of rapid changes (ramp events). Examples of wind flow variability between two sites of lidar measurements along with examples of reduced wind velocity downwind of operating turbines (wakes) will be presented.

  10. Sound Power Estimation by Laser Doppler Vibration Measurement Techniques

    Directory of Open Access Journals (Sweden)

    G.M. Revel

    1998-01-01

    Full Text Available The aim of this paper is to propose simple and quick methods for the determination of the sound power emitted by a vibrating surface, by using non-contact vibration measurement techniques. In order to calculate the acoustic power by vibration data processing, two different approaches are presented. The first is based on the method proposed in the Standard ISO/TR 7849, while the second is based on the superposition theorem. A laser-Doppler scanning vibrometer has been employed for vibration measurements. Laser techniques open up new possibilities in this field because of their high spatial resolution and their non-intrusivity. The technique has been applied here to estimate the acoustic power emitted by a loudspeaker diaphragm. Results have been compared with those from a commercial Boundary Element Method (BEM software and experimentally validated by acoustic intensity measurements. Predicted and experimental results seem to be in agreement (differences lower than 1 dB thus showing that the proposed techniques can be employed as rapid solutions for many practical and industrial applications. Uncertainty sources are addressed and their effect is discussed.

  11. An assimilation test of Doppler radar reflectivity and radial velocity from different height layers in improving the WRF rainfall forecasts

    Science.gov (United States)

    Tian, Jiyang; Liu, Jia; Yan, Denghua; Li, Chuanzhe; Chu, Zhigang; Yu, Fuliang

    2017-12-01

    Hydrological forecasts require high-resolution and accurate rainfall information, which is one of the most difficult variables to be captured by the mesoscale Numerical Weather Prediction (NWP) systems. Radar data assimilation is an effective method for improving rainfall forecasts by correcting the initial and lateral boundary conditions of the NWP system. The aim of this study is to explore an efficient way of utilizing the Doppler radar observations for data assimilation, which is implemented by exploring the effect of assimilating radar data from different height layers on the improvement of the NWP rainfall accuracy. The Weather Research and Forecasting (WRF) model is used for numerical rainfall forecast in the Zijingguan catchment located in the ;Jing-Jin-Ji; (Beijing-Tianjin-Hebei) Region of Northern China, and the three-dimensional variational data assimilation (3-DVar) technique is adopted to assimilate the radar data. Radar reflectivity and radial velocity are assimilated separately and jointly. Each type of radar data is divided into seven data sets according to the height layers: (1) 2000 m, and (7) all layers. The results show that radar reflectivity assimilation leads to better results than radial velocity assimilation. The accuracy of the forecasted rainfall deteriorates with the rise of the height of the assimilated radar reflectivity. The same results can be found when assimilating radar reflectivity and radial velocity at the same time. The conclusions of this study provide a reference for efficient assimilation of the radar data in improving the NWP rainfall products.

  12. Laser Doppler anemometer measurements of pulsatile flow in a model carotid bifurcation.

    Science.gov (United States)

    Ku, D N; Giddens, D P

    1987-01-01

    Hemodynamics at the human carotid bifurcation is important to the understanding of atherosclerotic plaque initiation and progression as well as to the diagnosis of clinically important disease. Laser Doppler anemometry was performed in a large scale model of an average human carotid. Pulsatile waveforms and physiologic flow divisions were incorporated. Disturbance levels and shear stresses were computed from ensemble averages of the velocity waveform measurements. Flow in the common carotid was laminar and symmetric. Flow patterns in the sinus, however, were complex and varied considerably during the cycle. Strong helical patterns and outer wall flow separation waxed and waned during each systole. The changing flow patterns resulted in an oscillatory shear stress at the outer wall ranging from -13 to 9 dyn cm-2 during systole with a time-averaged mean of only -0.5 dyn cm-2. This contrasts markedly with an inner wall shear stress range of 17-50, (mean 26) dyn cm-2. The region of transient separation was confined to the carotid sinus outer wall with no reverse velocities detected in the distal internal carotid. Notable disturbance velocities were also time-dependent, occurring only during the deceleration phase of systole and the beginning of diastole. The present pulsatile flow studies have aided in identifying hemodynamic conditions which correlate with early intimal thickening and predict the physiologic level of flow disturbances in the bulb of undiseased internal carotid arteries.

  13. Status update of the effort to correct the SDO/HMI systemmatic errors in Doppler velocity and derived data products

    Science.gov (United States)

    Scherrer, Philip H.

    2017-08-01

    This poster provides an update of the status of the efforts to understand and correct the leakage of the SDO orbit velocity into most HMI data products. The following is extracted from the abstract for the similar topic presented at the 2016 SPD meeting: “The Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) measures sets of filtergrams which are converted into velocity and magnetic field maps. In addition to solar photospheric motions the velocity measurements include a direct component from the line-of-sight component of the SDO orbit. Since the magnetic field is computed as the difference between the velocity measured in left and right circular polarization, the orbit velocity is canceled only if the velocity is properly calibrated. When the orbit velocity is subtracted the remaining "solar" velocity shows a residual signal which is equal to about 2% of the c. +- 3000 m/s orbit velocity in a nearly linear relationship. This implies an error in our knowledge of some of the details of as-built filter components. This systematic error is the source of 12- and 24-hour variations in most HMI data products. While the instrument as presently calibrated (Couvidat et al. 2012 and 2016) meets all of the “Level-1” mission requirements it fails to meet the stated goal of 10 m/s accuracy for velocity data products. For the velocity measurements this has not been a significant problem since the prime HMI goals of obtaining data for helioseismology are not affected by this systematic error. However the orbit signal leaking into the magnetograms and vector magnetograms degrades the ability to accomplish some of the mission science goals at the expected levels of accuracy. This poster presents the current state of understanding of the source of this systematic error and prospects for near term improvement in the accuracy of the filter profile model.”

  14. Velocity Gradient Maps Directly Measured by PLF

    Science.gov (United States)

    Quintella, Cristina M.; Gonçalves, Cristiane C.; Lima, Angelo Mv; Pepe, Iuri M.

    2000-11-01

    Flows are macroscopically classified as laminar or turbulent due to their velocity distributions, nevertheless most chemical and biological phenomena are yield or enhanced by intermolecular orientation and microscopic turbulence. Here was studied a 100micra liquid sheet produced by a slit nozzle, both flowing freely into air and over a borosilicate surface (roughness bellow 5nm), ranging from 17 to 36Re (143 to 297cm/s, similar to muscles and brain blood flow). Mono ethylene glycol was used either pure, or with sodium alkyl benzene sulfated (ABS) surfactant (24.5mol/L, submicellar), or with poly(ethylene oxide) (PEO) (1409ppm, 4millions aw). Velocity gradients were directly measured by 514nm polarized laser induced fluorescence (PLF) with R6G as probe. Intermolecular alignment (IA) maps were obtained all over the flow (about 1,950 points, 0.02mm2 precision). The free jet average IA has increased 57% when flowing over borosilicate. With ABS, the IA increased, suggesting wall drag reduction. With PEO the IA decreases due to solvent intermolecular forces attenuation, generating wider turbulent areas. PLF proved to be an excellent method to evaluate IA within liquid thin flows. Chosen solute additions permits IA control over wide regions.

  15. Novel approach to laser Doppler measurement of pulpal blood flow

    Science.gov (United States)

    Zang, De Yu; Wilder-Smith, Petra B.; Millerd, James E.; Arrastia-Jitosho, Anna-Marie A.

    1997-07-01

    A modified laser Doppler flowmetry technique that significantly improves the performance of the current technique in measuring pulpal blood flow is described. A preliminary model demonstrates that, by using a forward- scattering geometry, the detected signal will have a much higher signal-to-noise ratio and calibration capacity. The forward-scattered signal is readily detectable because teeth are relatively thin organs with moderate optical loss. Preliminary experiments comparing forward-scattered detection with conventional back-scattered detection were carried out using an extracted, perfused human molar. The results showed that: (1) the existing back-scattering method produced readings that fluctuated by as much as 187% in response to small changes in sensor position relative to the tooth and (2) the forward-scattered method produced consistent readings (within 10%) that were independent of the sensor position, a signal-to-noise ratio that was at least 5.6 times higher than that obtained by the back- scattering method, and a linear response to flow rate. The results validated the findings of the preliminary model and clearly showed the superiority of the forward-scattering geometry.

  16. Intracavity Rayleigh/Mie Scattering for Multipoint, Two-Component Velocity Measurement

    Science.gov (United States)

    Bivolaru, Daniel; Danehy, Paul M.; Lee, Joseph W.

    2006-01-01

    A simultaneous multi-point two-component Doppler velocimeter is described. The system uses two optical cavities: a Fabry-Perot etalon and an optical cavity for collecting and re-circulating the Rayleigh/Mie scattered light that is collected from the measurement volume in two parallel, but opposite directions. Single-pulse measurements of two orthogonal components of the velocity vector in a supersonic free jet were performed to demonstrate the technique. The re-circulation of the light rejected by the interferometer input mirror also increased the signal intensity by a factor of 3.5. 2005 Optical Society of America Interferometric Rayleigh scattering has previously been used for single-point velocity measurements in unseeded gas flow. However, this past work has generally been limited to probing with continuous-wave lasers resulting in time-averaged measurements of velocity. Multiple velocity components have been measured simultaneously by separate instruments.1,2 It has also been demonstrated that two orthogonal velocity components can be measured simultaneously at one point using one interferometer by reflecting back the probing laser beam, although this approach results in directional ambiguity of the flow velocity vector.3 This measurement ambiguity was removed by prior knowledge of the approximate magnitude and sign of the velocity components. Furthermore, it was shown that multiple points could be measured simultaneously with a Rayleigh scattering interferometric approach, but only one component of velocity was measured.4 Another method of performing multiple component velocity measurements with Rayleigh scattering uses a pair of cameras to image the flow, one of which views the flow through an iodine gas filter. This iodine-filter technique has the advantage of allowing high-resolution velocity imaging, but it generally has a lower dynamic range.

  17. Steady flow in a model of the human carotid bifurcation. Part II--laser-Doppler anemometer measurements.

    Science.gov (United States)

    Bharadvaj, B K; Mabon, R F; Giddens, D P

    1982-01-01

    The evidence for hypothesizing a relationship between hemodynamics and atherogenesis as well as the motivation for selecting the carotid bifurcation for extensive fluid dynamic studies has been discussed in Part I of this two-paper sequence. Part II deals with velocity measurements within the bifurcation model described by Fig. 1 and Table 1 of the previous paper. A plexiglass model conforming to the dimensions of the average carotid bifurcation was machined and employed for velocity measurements with a laser-Doppler anemometer (LDA). The objective of this phase of the study was to obtain quantitative information on the velocity field and to estimate levels and directions of wall shear stress in the region of the bifurcation.

  18. Acoustic Doppler current profiler velocity data collected in the approach channel of Brandon Road Lock and Dam in 2015

    Data.gov (United States)

    Department of the Interior — Water velocities were measured in the Des Plaines River from approximately river mile 286 to river mile 284 on October 19–21, 2015 using Teledyne Rio Grande 1200 kHz...

  19. Doppler ultrasound compared with strain gauge for measurement of systolic ankle blood pressure.

    Science.gov (United States)

    Joensen, J B; Juul, S; Abrahamsen, J; Henneberg, E W; Lindholt, Jes S

    2008-01-01

    This study assesses measurement variation in the measurement of ankle systolic blood pressure (ABP) when measured with Doppler ultrasound and with the strain gauge method. Ninety-seven patients were included. ABP was measured with Doppler ultrasound and with the strain gauge method. The methods were compared graphically by scatterplots and analyzed by paired t test, analysis of variance, and Pitman's paired variance ratio test. ABP was measured by strain gauge in all extremities, whereas no Doppler signal was obtainable in 7 limbs (4%). There was no systematic difference in measurements between the means of the two measurements. However, a substantial difference of more than 25 mm Hg was found in 15% of limbs and more than 20 mm Hg in 20%. In the majority of patients, measurements of ABP by Doppler ultrasound and the strain gauge method give similar results, but for a minority the discrepancy is substantial.

  20. Accuracy of spatial and temporal averaging of acoustic Doppler current profiler (ADCP) moving boat measurements

    Science.gov (United States)

    Gunawan, B.; Neary, V. S.; Hill, C.; Chamorro, L. P.

    2011-12-01

    Characterization of mean velocity, turbulence levels and secondary currents in rivers and tidal flow is crucial for the annual energy production estimation and structural design of MHK devices. A moving vessel deployment of an acoustic Doppler current profiler (ADCP) can obtain 3D velocity data in a large spatial region in an open channel cross-section within a significantly shorter time than other methods currently available. When using such a deployment method, the ADCP measures only a single velocity value at each bin, and therefore the data contain a significant amount of fluctuations due to turbulence velocity fluctuation and instrument's noise. Several researchers have proposed spatial and temporal averaging methodologies for ADCP moving boat (transects) data to deal with this issue. However, little is known about the accuracy of this technique. The effects of spatial and temporal averaging (STA) of ADCP transects data are investigated in the St. Anthony Falls laboratory flume. ADCP transects were obtained upstream and downstream of a 1:10 scale MHK horizontal axis turbine at various bin sizes. The MHK turbine generates a helical vortex flow with its axis parallel to the flume longitudinal direction, similar to the Prandtl's secondary flow of the first and second kind observed in open channels. The ADCP is attached to a computerized cart capable of traversing the ADCP at various speeds and recording the ADCP positions up to 1 mm accuracy. Accuracy of the STA of ADCP transects data with various bin size is assessed against ADCP fixed vessel and ADV point measurements. The accuracy of the STA of ADCP transects in representing the magnitude and direction of the helical vortex flow is also assessed.

  1. Implementing a wind measurement Doppler Lidar based on a molecular iodine filter to monitor the atmospheric wind field over Beijing

    Science.gov (United States)

    Du, Li-fang; Yang, Guo-tao; Wang, Ji-hong; Yue, Chuan; Chen, Lin-xiang

    2017-02-01

    A wind measurement Doppler Lidar system was developed, in which injection seeded laser was used to generate narrow linewidth laser pulse. Frequency stabilization was achieved through absorption of iodine molecules. Commands that control the instrumental system were based on the PID algorithm and coded using VB language. The frequency of the seed laser was locked to iodine molecular absorption line 1109 which is close to the upper edge of the absorption range,with long-time (>4 h) frequency-locking accuracy being ≤0.5 MHz and long-time frequency stability being 3.55×10-9. Design the continuous light velocity measuring system, which concluded the cure about doppler frequency shift and actual speed of chopped wave plate, the velocity error is less than 0.4 m/s. The experiment showed that the stabilized frequency of the seed laser was different from the transmission frequency of the Lidar. And such frequency deviation is known as Chirp of the laser pulse. The real-time measured frequency difference of the continuous and pulsed lights was about 10 MHz, long-time stability deviation was around 5 MHz. When the temporal and spatial resolutions were respectively set to 100 s and 96 m, the wind velocity measurement error of the horizontal wind field at the attitude of 15-35 km was within ±5 m/s, the results showed that the wind measurement Doppler Lidar implemented in Yanqing, Beijing was capable of continuously detecting in the middle and low atmospheric wind field at nighttime. With further development of this technique, system measurement error could be lowered, and long-run routine observations are promising.

  2. Recalculation of an artificially released avalanche with SAMOS and validation with measurements from a pulsed Doppler radar

    Directory of Open Access Journals (Sweden)

    R. Sailer

    2002-01-01

    Full Text Available A joint experiment was carried out on 10 February 1999 by the Swiss Federal Institute for Snow and Avalanche Research (SFISAR and the Austrian Institute for Avalanche and Torrent Research (AIATR, of the Federal Office and Re-search Centre for Forests, BFW to measure forces and velocities at the full scale experimental site CRÊTA BESSE in VALLÉE DE LA SIONNE, Canton du Valais, Switzerland. A huge avalanche could be released artificially, which permitted extensive investigations (dynamic measurements, im-provement of measurement systems, simulation model verification, design of protective measures, etc.. The results of the velocity measurements from the dual frequency pulsed Doppler avalanche radar of the AIATR and the recalculation with the numerical simulation model SAMOS are explained in this paper.

  3. Analysis of mean velocity and turbulence measurements with ADCPs

    Science.gov (United States)

    De Serio, Francesca; Mossa, Michele

    2015-07-01

    The present study examines the vertical structure of the coastal current in the inner part of the Gulf of Taranto, located in the Ionian Sea (Southern Italy), including both the Mar Grande and Mar Piccolo basins. To this aim, different measuring stations investigated by both a Vessel Mounted Acoustic Doppler Current Profiler (VM-ADCP) and a bottom fixed ADCP were taken into consideration. Two surveys were carried out in the target area on 29.12.2006 and on 11.06.2007 by the research unit of the Technical University of Bari (DICATECh Department), using a VM-ADCP to acquire the three velocity components along the water column in selected stationing points. The measurements were taken in shallow waters, under non-breaking wave conditions, offshore the surf zone. Due to the recording frequency of the instrument time-averaged vertical velocity profiles could be evaluated in these measuring stations. Water temperature and salinity were also measured at the same time and locations by means of a CTD recorder. A rigidly mounted ADCP, located on the seabed in the North-Eastern area of the Mar Grande basin, provided current data relative to the period 10-20 February 2014. Set to acquire the three velocity components with higher frequency with respect to the VM-ADCP, it allowed us to estimate the turbulent quantities such as Reynolds stresses and turbulent kinetic energy by means of the variance method. Therefore, the present research is made up of two parts. The first part examines the current pattern measured by the VM-ADCP and verifies that, for each station, the classical log law reproduces well the vertical profile of the experimental streamwise velocities extending beyond its typical limit of validity up to the surface i.e. reaching great heights above the sea bed. This behavior is quite new and not always to be expected, being generally limited to boundary layers. It has been convincingly observed in only few limited experimental works. In the present study this

  4. Systolic and early diastolic left ventricular velocities assessed by tissue Doppler imaging in 100 top-level handball players.

    Science.gov (United States)

    Butz, Thomas; van Buuren, Frank; Mellwig, Klaus Peter; Langer, Christoph; Oldenburg, Olaf; Treusch, Kuno Alexander; Meissner, Axel; Plehn, Gunnar; Trappe, Hans-Joachim; Horstkotte, Dieter; Faber, Lothar

    2010-06-01

    Echocardiographic tissue Doppler imaging (TDI) has been proposed for the differentiation of physiologic left ventricular hypertrophy and pathologic left ventricular hypertrophy in athletes. In addition, cutoff values for systolic (S'athletes (100 Caucasian men; professional handball players of the first German handball league and the German national team; mean age 25.8+/-4.8 years). Global and regional left ventricular systolic function was normal in all athletes. They showed an eccentric hypertrophy of the left ventricle (LV), which was characterized by an increased mass of the LV (287.3+/-58.4 g), and an increased end diastolic diameter of the LV (LVEDD: 58+/-5.9 mm), but no echomorphologic signs of pathologic hypertrophy or hypertrophic cardiomyopathy. TDI showed a systolic velocity S' of the MA of 9.3+/-1.5 cm/s at the septal and 10.5+/-2.1 at the lateral MA. Ten of the 100 athletes showed a S'athletes showed reduced systolic or early diastolic velocities below the proposed cutoff values (S' and E'<9 cm/s) at any sides of the MA. Our study provides further insights into systolic and diastolic function as assessed by TDI in top-level handball players. Owing to the large cohort of individuals, our findings might be helpful as reference values for the echocardiographic assessment of handball players, who are performing a moderate static and high dynamic sport.

  5. Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning speed and high velocity sensitivity

    NARCIS (Netherlands)

    Zhao, YH; Chen, ZP; Saxer, CE; Xiang, SH; de Boer, JF; Nelson, JS

    2000-01-01

    We have developed a novel phase-resolved optical coherence tomography (OCT) and optical Doppler tomography (ODT) system that uses phase information derived from a Hilbert transformation to image blood flow in human skin with fast scanning speed and high velocity sensitivity. Using the phase change

  6. Cryogenic flow rate measurement with a laser Doppler velocimetry standard

    Science.gov (United States)

    Maury, R.; Strzelecki, A.; Auclercq, C.; Lehot, Y.; Loubat, S.; Chevalier, J.; Ben Rayana, F.

    2018-03-01

    A very promising alternative to the state-of-the-art static volume measurements for liquefied natural gas (LNG) custody transfer processes is the dynamic principle of flow metering. As the Designated Institute (DI) of the LNE (‘Laboratoire National de métrologie et d’Essais’, being the French National Metrology Institute) for high-pressure gas flow metering, Cesame-Exadebit is involved in various research and development programs. Within the framework of the first (2010-2013) and second (2014-2017) EURAMET Joint Research Project (JRP), named ‘Metrological support for LNG custody transfer and transport fuel applications’, Cesame-Exadebit explored a novel cryogenic flow metering technology using laser Doppler velocimetry (LDV) as an alternative to ultrasonic and Coriolis flow metering. Cesame-Exadebit is trying to develop this technique as a primary standard for cryogenic flow meters. Currently, cryogenic flow meters are calibrated at ambient temperatures with water. Results are then extrapolated to be in the Reynolds number range of real applications. The LDV standard offers a unique capability to perform online calibration of cryogenic flow meters in real conditions (temperature, pressure, piping and real flow disturbances). The primary reference has been tested on an industrial process in a LNG terminal during truck refuelling. The reference can calibrate Coriolis flow meters being used daily with all the real environmental constraints, and its utilisation is transparent for LNG terminal operators. The standard is traceable to Standard International units and the combined extended uncertainties have been determined and estimated to be lower than 0.6% (an ongoing improvement to reducing the correlation function uncertainty, which has a major impact in the uncertainty estimation).

  7. Stellar magnetometry and Zeeman-Doppler imaging in exo-planets research using the radial velocity method

    International Nuclear Information System (INIS)

    Hebrard, Elodie

    2015-01-01

    Forthcoming instruments dedicated to exo-planets detection through the radial velocity method are numerous, and increasingly more accurate. However this method is indirect: orbiting planets are detected and characterised from variations on the spectrum of the host star. We are therefore sensitive to all activity phenomena impacting the spectrum and producing a radial velocity signal (pulsation, granulation, spots, magnetic cycle...). The detection of rocky Earth-like planets around main-sequence stars, and of hot Jupiters into young systems, are currently limited by the intrinsic magnetic activity of the host stars. The radial velocity fluctuations caused by activity (activity jitter) can easily mimic and hide signals from such planets, whose amplitude is of a few m/s and hundreds of m/s, respectively. As a result, the detection threshold of exo-planets is largely set by the stellar activity level. Currently, efforts are invested to overcome this intrinsic limitation. During my PhD, I studied how to take advantage of imaging tomographic techniques (Zeeman-Doppler imaging, ZDI) to characterize stellar activity and magnetic field topologies, ultimately allowing us to filter out the activity jitter. My work is based on spectro-polarimetric observations of a sample of weakly-active M-dwarfs, and young active T Tauri stars. Using a modified version of ZDI, we are able to reconstruct the distribution of active regions, and then model the induced stellar signal allowing us to clean RV curves from the activity jitter. First tests demonstrate that this technique can be efficient enough to recover the planet signal, especially for the more active ones. (author)

  8. Measurements of ion temperature and flow of pulsed plasmas produced by a magnetized coaxial plasma gun device using an ion Doppler spectrometer

    Science.gov (United States)

    Kitagawa, Y.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    It is important to know surface damage characteristics of plasma-facing component materials during transient heat and particle loads such as type I ELMs. A magnetized coaxial plasma gun (MCPG) device has been used as transient heat and particle source in ELM simulation experiments. Characteristics of pulsed plasmas produced by the MCPG device play an important role for the plasma material interaction. In this study, ion temperature and flow velocity of pulsed He plasmas were measured by an ion Doppler spectrometer (IDS). The IDS system consists of a light collection system including optical fibers, 1m-spectrometer and a 16 channel photomultiplier tube (PMT) detector. The IDS system measures the width and Doppler shift of HeII (468.58 nm) emission line with the time resolution of 1 μs. The Doppler broadened and shifted spectra were measured with 45 and 135 degree angles with respect to the plasmoid traveling direction. The observed emission line profile was represented by sum of two Gaussian components to determine the temperature and flow velocity. The minor component at around the wavelength of zero-velocity was produced by the stationary plasma. As the results, the ion velocity and temperature were 68 km/s and 19 eV, respectively. Thus, the He ion flow energy is 97 eV. The observed flow velocity agrees with that measured by a time of flight technique.

  9. Theory of the double-edge molecular technique for Doppler lidar wind measurement.

    Science.gov (United States)

    Flesia, C; Korb, C L

    1999-01-20

    The theory of the double-edge lidar technique for measuring the wind with molecular backscatter is described. Two high-spectral-resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and improves measurement accuracy relative to the single-edge technique by nearly a factor of 2. The use of a crossover region where the sensitivity of a molecular- and an aerosol-based measurement is equal is described. Use of this region desensitizes the molecular measurement to the effects of aerosol scattering over a velocity range of +/-100 m/s. We give methods for correcting short-term, shot-to-shot, frequency jitter and drift with a laser reference frequency measurement and methods for long-term frequency correction with a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2-15 km for a 1-km vertical resolution, a satellite altitude of 400 km, and a 200 km x 200 km spatial resolution.

  10. Theory of the Double-Edge Molecular Technique for Doppler Lidar Wind Measurement

    Science.gov (United States)

    Flesia, Cristina; Korb, C. Laurence

    1999-01-01

    The theory of the double-edge lidar technique for measuring the wind with molecular backscatter is described. Two high-spectral-resolution edge filters are located in the wings of the Rayleigh Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and improves measurement accuracy relative to the single-edge technique by nearly a factor of 2. The use of a crossover region where the sensitivity of a molecular- and an aerosol-based measurement is equal is described. Use of this region desensitizes the molecular measurement to the effects of aerosol scattering over a velocity range of 100 m s. We give methods for correcting short-term, shot-to-shot, frequency jitter and drift with a laser reference frequency measurement and methods for long-term frequency correction with a servo control system. The effects of Rayleigh Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2 3 m s for altitudes of 2 15 km for a 1-km vertical resolution, a satellite altitude of 400 km, and a 200 km 200 km spatial resolution.

  11. Measurement of bubbly flows in vertical channels using ultrasonic velocity profile monitor

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Zhou Shirong; Takeda, Yasushi; Nakamura, Hideo; Kukita, Yutaka

    1998-01-01

    The authors have been developing measurement technique, using the Ultrasonic Doppler effect and applicable for a bubbly flow in vertical channels in order to understand their multi-dimensional flow characteristics and to offer a data base to validate numerical codes for multi-dimensional two-phase flow. Our developed measurement system is composed of an ultrasonic velocity profile monitor with a video data processing unit, which can measure simultaneously velocity profiles in both gas and liquid phases, a void fraction profile for bubbly flow in a channel, and an average bubble diameter and void fraction. In this paper, our proposed measurement system was applied to bubbly countercurrent flows in a vertical rectangular channel the followings are discussed: (1) the measurement principle, (2) the data processing process, (3) measurement accuracy and (4) further problems. (author)

  12. Ecografia transfontanelar com fluxo a cores em recém-nascidos prematuros Intracranial blood flow velocities evaluated by color doppler (duplex in preterm infants

    Directory of Open Access Journals (Sweden)

    Marcelo Cardoso de Assis

    2004-03-01

    intracranial hemorrhage. They were subjected to sequencial measurements of blood flow velocities in the intracranial arteries. The gestational age of the whole group varied from 28 to 36 weeks and birth weights between 720 and 2530 g. The diagnosis of the intracerebral hemorrhages in these preterm neonates were done using high resolution gray and color scale transfontanellar ultrasonography brain scans . The ultrasound evaluations were performed in the initial 3rd, 7th and 14th day of life. The 73 preterm infants were evaluated with sequencial measurements of blood flow velocity in the intracranial arteries using the Doppler technique through the anterior fontanelle. Doppler evaluation of the cerebral vessels were performed on days 3, 7, 30 and 90 of life. These evaluations were performed in the six intracranial arteries, meaning: right and left anterior and middle cerebral arteries and right and left internal carotid arteries. Doppler recordings were made using Duplex Color-Doppler system, pulse echo probe of 3,5; 5,0 and 7,5 MHz. Measuring the blood flow velocity in the cerebral arteries we obtained a maximum systolic velocity and end diastolic velocity with a rate in meters per second (m/s for each cardiac cycle. After obtaining these numerical values for these velocities we obtained the resistance index (RI or Pourcelot index. In a progressive way as the resistance index (RI values were being obtained in each stage of this study they were also being checked in the cerebral arteries of healthy preterm infants and infants with intracranial hemorrhages. We also analyzed in a comparative method the values of the resistive index between the two groups of preterm infants observing their behaviour.The results obtained when comparing the RI values in the various arteries during the different stages of the study permitted us to conclude that the RI values of healthy pre-term infants were always larger than the RI values of pre-term infants with intracranial hemorrhage. We also

  13. Plasma flow velocity measurements using a modulated Michelson interferometer

    International Nuclear Information System (INIS)

    Howard, J.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (orig.)

  14. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    Directory of Open Access Journals (Sweden)

    Royer Philippe

    2016-01-01

    LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL. These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR in order to detect (aerosol/cloud base and top, PBL height and to characterize atmospheric structures (attenuated backscatter, depolarization ratio. For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  15. Improved flow velocity estimates from moving-boat ADCP measurements

    NARCIS (Netherlands)

    Vermeulen, B.; Hoitink, A.J.F.; Sassi, M.G.

    2014-01-01

    Acoustic Doppler current profilers (ADCPs) are the current standard for flow measurements in large-scale open water systems. Existing techniques to process vessel-mounted ADCP data assume homogeneous or linearly changing flow between the acoustic beams. This assumption is likely to fail but is

  16. Dynamic Data Filtering of Long-Range Doppler LiDAR Wind Speed Measurements

    Directory of Open Access Journals (Sweden)

    Hauke Beck

    2017-06-01

    Full Text Available Doppler LiDARs have become flexible and versatile remote sensing devices for wind energy applications. The possibility to measure radial wind speed components contemporaneously at multiple distances is an advantage with respect to meteorological masts. However, these measurements must be filtered due to the measurement geometry, hard targets and atmospheric conditions. To ensure a maximum data availability while producing low measurement errors, we introduce a dynamic data filter approach that conditionally decouples the dependency of data availability with increasing range. The new filter approach is based on the assumption of self-similarity, that has not been used so far for LiDAR data filtering. We tested the accuracy of the dynamic data filter approach together with other commonly used filter approaches, from research and industry applications. This has been done with data from a long-range pulsed LiDAR installed at the offshore wind farm ‘alpha ventus’. There, an ultrasonic anemometer located approximately 2.8 km from the LiDAR was used as reference. The analysis of around 1.5 weeks of data shows, that the error of mean radial velocity can be minimised for wake and free stream conditions.

  17. Shock-induced phase transition of Tin: Experimental study with velocity and temperature measurements

    Science.gov (United States)

    Chauvin, Camille; Bouchkour, Zakaria; Sinatti, Frédéric; Petit, Jacques

    2017-01-01

    To investigate polymorphic transition and melting on release of Tin, experiments under shock wave compression have been carried out from 10 GPa to 44 GPa with both velocity and temperature measurements. Interface Sn/LiF velocity has been recorded using Photon Doppler Velocimeter (PDV) measurement technique and interface Sn/LiF temperature has been performed thanks to an optical pyrometer appropriate to detect low and high temperatures (respectively 1000 K). While PDV measurements are common and accurate, temperature remains often imprecise due to the lack of knowledge on the emissivity of the sample. The use of an emissive layer at the interface Sn/LiF helps to estimate an accurate temperature measurement which can be compared to our numerical simulations. The profiles of both velocity and radiance records are in good agreement and display the polymorphic transition and the melting on release of Tin. Besides, temperature profiles can show complementary singularities particularly during phase transition, not visible on velocity profiles. This paper will discuss the evidence of phase transitions on temperature measurements, the complementarity with velocity measurements and the advantages of an emissive layer.

  18. Doppler study of middle cerebral artery blood flow velocity and cerebral autoregulation during a simulated ascent of Mount Everest.

    Science.gov (United States)

    Ter Minassian, A; Beydon, L; Ursino, M; Gardette, B; Gortan, C; Richalet, J P

    2001-01-01

    To explore cerebral hemodynamics in 8 healthy volunteers in a hypobaric chamber up to the altitude of Mount Everest after a progressive stepwise decompression to 8,848 m. Physiological, clinical, and transcranial Doppler data were collected after at least 3 days at 5,000, 6,000, and 7,000 m and within 4 hours of reaching 8,000 m and returning to sea level. Three subjects were excluded at 8,000 and 8,848 m because of acute neurological deficits. Heart rate increased; mean arterial pressure remained stable; PaO2 and PaCO2 decreased with altitude; hemoglobin (Hb) and hematocrit (Ht) increased; arterial O2 content decreased over 6,000 m; middle cerebral artery blood flow velocity (MCAv) increased only during acute exposure to 8,000 m; and the corresponding pulsatility (PI) and resistivity indices (RI) decreased over 5,000 m. PI and RI correlated with heart rate. The transient hyperemic response (THR) of MCAv to common carotid compression was depressed at 8,000 m. At 8,000 m, the increase in MCAv seemed to reflect the normal hemodynamic response to acute hypoxia. The decrease of THR at this altitude could be an indication of impaired cerebral autoregulation. The role of impaired cerebral autoregulation in the genesis of acute neurologic deficits, observed at 8,000 m and above in 3 subjects, remains speculative.

  19. Magnetic resonance imaging/angiography and transcranial Doppler velocities in sickle cell anemia: results from the SWiTCH trial.

    Science.gov (United States)

    Helton, Kathleen J; Adams, Robert J; Kesler, Karen L; Lockhart, Alex; Aygun, Banu; Driscoll, Catherine; Heeney, Matthew M; Jackson, Sherron M; Krishnamurti, Lakshmanan; Miller, Scott T; Sarnaik, Sharada A; Schultz, William H; Ware, Russell E

    2014-08-07

    The Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial compared standard (transfusions/chelation) to alternative (hydroxyurea/phlebotomy) treatment to prevent recurrent stroke and manage iron overload in children chronically transfused over 7 years before enrollment. Standardized brain magnetic resonance imaging/magnetic resonance angiography (MRA) and transcranial Doppler (TCD) exams were performed at entry and exit, with a central blinded review. A novel MRA vasculopathy grading scale demonstrated frequent severe baseline left/right vessel stenosis (53%/41% ≥Grade 4); 31% had no vessel stenosis on either side. Baseline parenchymal injury was prevalent (85%/79% subcortical, 53%/37% cortical, 50%/35% subcortical and cortical). Most children had low or uninterpretable baseline middle cerebral artery TCD velocities, which were associated with worse stenoses (incidence risk ratio [IRR] = 5.1, P ≤ .0001 and IRR = 4.1, P severe parenchymal and vascular abnormalities in children with SCA and stroke and support concerns about chronic transfusions lacking effectiveness for preventing progressive cerebrovascular injury. The novel SWiTCH vasculopathy grading scale warrants validation testing and consideration for use in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00122980. © 2014 by The American Society of Hematology.

  20. Distance and velocity estimation of projectiles based on Doppler radar signals using a nonlinear discrete-time observer

    Science.gov (United States)

    Podjawerschek, Sonja; Spahn, Emil; Horn, Joachim; Brodmann, Michael; Himmelsbach, Ralf

    2010-04-01

    We propose a new "quasi-global" observer design to determine the distance and velocity of projectiles in real-time. The detection of the projectile is realized by a low power Doppler radar at short distances (5m-10m). The advantage of a global observer design is the possibility to deal with large initial errors, which is important because of the usually unknown initial state of the observed system. The transformation to the nonlinear observability canonical form (NOCF) leads to linear error dynamics and this allows a traceable influence on the dynamic behaviour of the observer, which is essential for the time critical implementation on a real-time system. To benefit from these two advantages, the nonlinear system has to be transformed to the NOCF and an explicit expression of the inverse transformation has to be found. Since with this severe restriction the given problem can not be solved, we propose a numerically approximated inverse transformation in a bounded region of physical interest to allow the design of a quasi-global observer with linear error dynamics in the presented case. Based on this design the class of systems where this kind of observer can be applied has been enlarged considerably.

  1. Acceleration and Velocity Sensing from Measured Strain

    Science.gov (United States)

    Pak, Chan-Gi; Truax, Roger

    2016-01-01

    A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic strain sensor, system equivalent reduction and expansion process.

  2. Linear FMCW Laser Radar for Precision Range and Vector Velocity Measurements

    Science.gov (United States)

    Pierrottet, Diego; Amzajerdian, Farzin; Petway, Larry; Barnes, Bruce; Lockhard, George; Rubio, Manuel

    2008-01-01

    An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA s new Space Exploration initiative for manned and robotic missions to the Moon and Mars. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing state-of-the-art fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed. Linear FMCW lidar has the capability of high-resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision horizontal and vertical velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the preselected site and achieving autonomous, safe soft-landing. The all-fiber coherent laser radar has several important advantages over more conventional pulsed laser altimeters or range finders. One of the advantages of the coherent laser radar is its ability to measure directly the platform velocity by extracting the Doppler shift generated from the motion, as opposed to time of flight range finders where terrain features such as hills, cliffs, or slopes add error to the velocity measurement. Doppler measurements are about two orders of magnitude more accurate than the velocity estimates obtained by pulsed laser altimeters. In addition, most of the components of the device are efficient and reliable commercial off-the-shelf fiber optic telecommunication components. This paper discusses the design and performance of a second-generation brassboard system under development at NASA Langley Research Center as part of the Autonomous Landing and Hazard Avoidance (ALHAT) project.

  3. Can Emergency Physicians Perform Common Carotid Doppler Flow Measurements to Assess Volume Responsiveness?

    Directory of Open Access Journals (Sweden)

    Stolz, Lori A.

    2015-02-01

    Full Text Available Introduction: Common carotid flow measurements may be clinically useful to determine volume responsiveness. The objective of this study was to assess the ability of emergency physicians (EP to obtain sonographic images and measurements of the common carotid artery velocity time integral (VTi for potential use in assessing volume responsiveness in the clinical setting. Methods: In this prospective observational study, we showed a five-minute instructional video demonstrating a technique to obtain common carotid ultrasound images and measure the common carotid VTi to emergency medicine (EM residents. Participants were then asked to image the common carotid artery and obtain VTi measurements. Expert sonographers observed participants imaging in real time and recorded their performance on nine performance measures. An expert sonographer graded image quality. Participants were timed and answered questions regarding ease of examination and their confidence in obtaining the images. Results: A total of 30 EM residents participated in this study and each performed the examination twice. Average time required to complete one examination was 2.9 minutes (95% CI [2.4-3.4 min]. Participants successfully completed all performance measures greater than 75% of the time, with the exception of obtaining measurements during systole, which was completed in 65% of examinations. Median resident overall confidence in accurately performing carotid VTi measurements was 3 (on a scale of 1 [not confident] to 5 [confident]. Conclusion: EM residents at our institution learned the technique for obtaining common carotid artery Doppler flow measurements after viewing a brief instructional video. When assessed at performing this examination, they completed several performance measures with greater than 75% success. No differences were found between novice and experienced groups. [West J Emerg Med. 2015;16(2:255–259.

  4. Evaluation of performance of Son Tek Argonaut acoustic doppler velocity log in tow tank and sea

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Madhan, R.; Mascarenhas, A.A.M.Q.; Desai, R.G.P.; VijayKumar, K.; Dias, M.; Tengali, S.; Methar, A.

    within the towing speed bounds of ≈ ±50cm/s is likely to be severely affected if it is operated in a constricted environment where the signal-to-noise ratio might be poor at low speeds. Acknowledgements We are thankful for the assistance and help... offered by the research officers Mr. Marcande, Mrs. Deogade, Mr. Oke, and other technical staff of CWPRS, Pune, during tow- tank experiments. Thanks are also due to the Captain and crewmembers of ORV. Sagar Sukthi for their assistance during measurements...

  5. Measuring velocity profile in scaled CANDU6 moderator tank using particle image velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Han; Bang, In Cheol [UNIST, Ulsan, (Korea, Republic of); Kim, Hyoung Tae; Cha, Jae Eun [KAISt, Daejeon (Korea, Republic of)

    2012-10-15

    The Calandria vessel, which is called as CANDU6 moderator tank, is the actual reactor core including fuel channels and moderator in PHWR. The understanding of circulation patterns in Calandria vessel is important because the cooling capability is related to the moderator tank. Therefore, measuring velocity and temperature patterns in the Calandria vessel is the key factor for the safety of CANDU reactor. Various experimental and numerical efforts to predict and analyze the thermal hydraulic characteristic of Calandria vessel have been made. Yoon et al. developed a CFD model for the CANDU6 moderator analyzing the velocity profile and the temperature distribution. Khartabil et al. did an experiment to measure 3 dimensional velocity and temperature distribution in moderator circulation tests at a 1/4 scaled down facility. Laser Doppler Anememetry (LDA) was used to detect the velocity profile and thermocouples detect the temperature distribution. Previous study presented the velocity profile in a 1/40 scaled-down Calandria vessel and compared with CFD analysis. In the present work, Particle Image Velocimetry (PIV) technique is used to obtain velocity profiles in a 1/8 scaled down Calandria vessel.

  6. On the measurement of the neutrino velocity applying the standard time of the Global Positioning System

    Science.gov (United States)

    Skeivalas, J.; Parseliunas, E.

    2013-01-01

    The measurement of the neutrino velocity applying the standard time of the Global Positioning System (GPS) is presented in the paper. The practical data were taken from the OPERA experiment, in which neutrino emission from the CERN LHC accelerator to Gran Sasso detector was investigated. The distance between accelerator and detector is about 730 km. The time interval was measured by benchmark clocks, which were calibrated by the standard GPS time signals received from GPS satellites. The calculation of the accuracy of the GPS time signals with respect to changes of the signals' frequencies due to the Doppler effect is presented. It is shown that a maximum error of about 200 ns could occur when GPS time signals are applied for the calibration of the clocks for the neutrino velocity measurements.

  7. Shipborne Wind Measurement and Motion-induced Error Correction of a Coherent Doppler Lidar over the Yellow Sea in 2014

    Science.gov (United States)

    Zhai, Xiaochun; Wu, Songhua; Liu, Bingyi; Song, Xiaoquan; Yin, Jiaping

    2018-03-01

    Shipborne wind observations by a coherent Doppler lidar (CDL) have been conducted to study the structure of the marine atmospheric boundary layer (MABL) during the 2014 Yellow Sea campaign. This paper evaluates uncertainties associated with the ship motion and presents the correction methodology regarding lidar velocity measurement based on modified 4-Doppler beam swing (DBS) solution. The errors of calibrated measurement, both for the anchored and the cruising shipborne observations, are comparable to those of ground-based measurements. The comparison between the lidar and radiosonde results in a bias of -0.23 ms-1 and a standard deviation of 0.87 ms-1 for the wind speed measurement, and 2.48, 8.84° for the wind direction. The biases of horizontal wind speed and random errors of vertical velocity are also estimated using the error propagation theory and frequency spectrum analysis, respectively. The results show that the biases are mainly related to the measuring error of the ship velocity and lidar pointing error, and the random errors are mainly determined by the signal-to-noise ratio (SNR) of the lidar backscattering spectrum signal. It allows for the retrieval of vertical wind, based on one measurement, with random error below 0.15 ms-1 for an appropriate SNR threshold and bias below 0.02 ms-1. The combination of the CDL attitude correction system and the accurate motion correction process has the potential of continuous long-term high temporal and spatial resolution measurement for the MABL thermodynamic and turbulence process.

  8. EnKF assimilation of simulated spaceborne Doppler observations of vertical velocity: impact on the simulation of a supercell thunderstorm and implications for model-based retrievals

    Directory of Open Access Journals (Sweden)

    W. E. Lewis

    2006-01-01

    Full Text Available Recently, a number of investigations have been made that point to the robust effectiveness of the Ensemble Kalman Filter (EnKF in convective-scale data assimilation. These studies have focused on the assimilation of ground-based Doppler radar observations (i.e. radial velocity and reflectivity. The present study differs from these investigations in two important ways. First, in anticipation of future satellite technology, the impact of assimilating spaceborne Doppler-retrieved vertical velocity is examined; second, the potential for the EnKF to provide an alternative to instrument-based microphysical retrievals is investigated. It is shown that the RMS errors of the analyzed fields produced by assimilation of vertical velocity alone are in general better than those obtained in previous studies: in most cases assimilation of vertical velocity alone leads to analyses with small errors (e.g. <1 ms-1 for velocity components after only 3 or 4 assimilation cycles. The microphysical fields are notable exceptions, exhibiting lower errors when observations of reflectivity are assimilated together with observations of vertical velocity, likely a result of the closer relationship between reflectivity and the microphysical fields themselves. It is also shown that the spatial distribution of the error estimates improves (i.e. approaches the true errors as more assimilation cycles are carried out, which could be a significant advantage of EnKF model-based retrievals.

  9. Surface Charge Measurement of SonoVue, Definity and Optison: A Comparison of Laser Doppler Electrophoresis and Micro-Electrophoresis.

    Science.gov (United States)

    Ja'afar, Fairuzeta; Leow, Chee Hau; Garbin, Valeria; Sennoga, Charles A; Tang, Meng-Xing; Seddon, John M

    2015-11-01

    Microbubble (MB) contrast-enhanced ultrasonography is a promising tool for targeted molecular imaging. It is important to determine the MB surface charge accurately as it affects the MB interactions with cell membranes. In this article, we report the surface charge measurement of SonoVue, Definity and Optison. We compare the performance of the widely used laser Doppler electrophoresis with an in-house micro-electrophoresis system. By optically tracking MB electrophoretic velocity in a microchannel, we determined the zeta potentials of MB samples. Using micro-electrophoresis, we obtained zeta potential values for SonoVue, Definity and Optison of -28.3, -4.2 and -9.5 mV, with relative standard deviations of 5%, 48% and 8%, respectively. In comparison, laser Doppler electrophoresis gave -8.7, +0.7 and +15.8 mV with relative standard deviations of 330%, 29,000% and 130%, respectively. We found that the reliability of laser Doppler electrophoresis is compromised by MB buoyancy. Micro-electrophoresis determined zeta potential values with a 10-fold improvement in relative standard deviation. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  10. Influence of the measuring condition on vibrocardiographic signals acquired on the thorax with a laser Doppler vibrometer

    Science.gov (United States)

    Mignanelli, L.; Bauer, G.; Klarmann, M.; Wang, H.; Rembe, C.

    2017-07-01

    Velocity signals acquired with a Laser Doppler Vibrometer on the thorax (Optical Vibrocardiography) contain important information, which have a relation to cardiovascular parameters and cardiovascular diseases. The acquired signal results in a superimposition of vibrations originated from different sources of the human body. Since we study the vibration generated by the heart to reliably detect a characteristic time interval corresponding to the PR interval in the ECG, these disturbance have to be removed by filtering. Moreover, the Laser Doppler Vibrometer measures only in the direction of the laser beam and, thus, the velocity signal is only a projection of the tridimensional movement of the thorax. This work presents an analysis of the influences of the filters and of the measurement direction on the characteristic time interval in Vibrocardiographic signals. Our analysis results in recommended settings for filters and we demonstrate that reliable detection of vibrocardiographic parameters is possible within an angle deviation of 30° in respect to the perpendicular irradiation on the front side of the subject.

  11. Study of the Myocardial Contraction and Relaxation Velocities through Doppler Tissue Imaging Echocardiography: A New Alternative in the Assessment of the Segmental Ventricular Function

    Directory of Open Access Journals (Sweden)

    Silva Carlos Eduardo Suaide

    2002-01-01

    Full Text Available OBJECTIVE: Doppler tissue imaging (DTI enables the study of the velocity of contraction and relaxation of myocardial segments. We established standards for the peak velocity of the different myocardial segments of the left ventricle in systole and diastole, and correlated them with the electrocardiogram. METHODS: We studied 35 healthy individuals (27 were male with ages ranging from 12 to 59 years (32.9 ± 10.6. Systolic and diastolic peak velocities were assessed by Doppler tissue imaging in 12 segments of the left ventricle, establishing their mean values and the temporal correlation with the cardiac cycle. RESULTS: The means (and standard deviation of the peak velocities in the basal, medial, and apical regions (of the septal, anterior, lateral, and posterior left ventricle walls were respectively, in cm/s, 7.35(1.64, 5.26(1.88, and 3.33(1.58 in systole and 10.56(2.34, 7.92(2.37, and 3.98(1.64 in diastole. The mean time in which systolic peak velocity was recorded was 131.59ms (±19.12ms, and diastolic was 459.18ms (±18.13ms based on the peak of the R wave of the electrocardiogram. CONCLUSION: In healthy individuals, maximum left ventricle segment velocities decreased from the bases to the ventricular apex, with certain proportionality between contraction and relaxation (P<0.05. The use of Doppler tissue imaging may be very helpful in detecting early alterations in ventricular contraction and relaxation.

  12. Time series analysis of continuous-wave coherent Doppler Lidar wind measurements

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Mikkelsen, Torben; Mann, Jakob

    2008-01-01

    The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra simultaneou......The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra...

  13. Magneto-optic Doppler analyzer: a new instrument to measure mesopause winds

    Science.gov (United States)

    Williams, Bifford P.; Tomczyk, Steven

    1996-11-01

    The magneto-optic Doppler analyzer (MODA) is a new type of passive optical instrument that one can use to measure the Doppler shift of the sodium nightglow emitted at approximately 91 km near the mesopause. From this measurement, horizontal wind signatures are inferred. The MODA is based on a sodium vapor magneto-optic filter that provides inherent wavelength stability at a low cost. The instrument has been used to take nightly zonal and meridional wind measurements since October 1994 at Niwot Ridge, Colorado (40 N, 105 W). We obtained an internally consistent wind signal and measured the semidiurnal tide for several seasons.

  14. Measuring our peculiar velocity on the CMB with high-multipole off-diagonal correlations

    Energy Technology Data Exchange (ETDEWEB)

    Amendola, Luca; Catena, Riccardo; Notari, Alessio [Institute of Theoretical Physics, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Masina, Isabella [Dip. di Fisica, Università di Ferrara and INFN Sez. di Ferrara, Via Saragat 1, I-44100 Ferrara (Italy); Quartin, Miguel [Instituto de Física, Universidade Federal do Rio de Janeiro, CEP 21941-972, Rio de Janeiro, RJ (Brazil); Quercellini, Claudia, E-mail: l.amendola@thphys.uni-heidelberg.de, E-mail: r.catena@thphys.uni-heidelberg.de, E-mail: masina@fe.infn.it, E-mail: a.notari@thphys.uni-heidelberg.de, E-mail: mquartin@if.ufrj.br, E-mail: Claudia.Quercellini@uniroma2.it [Dip. di Fisica, Università di Roma ' ' Tor Vergata' ' , Rome (Italy)

    2011-07-01

    Our peculiar velocity with respect to the CMB rest frame is known to induce a large dipole in the CMB. However, the motion of an observer has also the effect of distorting the anisotropies at all scales, as shown by Challinor and Van Leeuwen (2002), due to aberration and Doppler effects. We propose to measure independently our local motion by using off-diagonal two-point correlation functions for high multipoles. We study the observability of the signal for temperature and polarization anisotropies. We point out that Planck can measure the velocity β with an error of about 30% and the direction with an error of about 20°. This method constitutes a cross-check, which can be useful to verify that our CMB dipole is due mainly to our velocity or to disentangle the velocity from other possible intrinsic sources. Although in this paper we focus on our peculiar velocity, a similar effect would result also from other intrinsic vectorial distortion of the CMB which would induce a dipolar lensing. Measuring the off-diagonal correlation terms is therefore a test for a preferred direction on the CMB sky.

  15. In-cylinder velocity field measurements in a motored diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Cipolla, G.; Puglisi, A.; Vafidis, C.

    1987-01-01

    Measurements of three velocity components and of the corresponding turbulent fluctuations are reported obtained by laser Doppler anemometry in the cylinder of a FIAT-IVECO 8140 DI Diesel engine motored at 1000 rpm with a 16:1 compression ratio. The results show that the air swirl velocities at inlet valve closure are axially stratified while the intake-generated axial flow structures persist, although decaying, up to 70/sup 0/ BTDC when the squish effect transforms the in-cylinder flow structure. The presence of a flow towards the piston crevice is detected at 20/sup 0/ BTDC while at TDC of compression the formation of, at least, one toroidal vortex in the axial plane inside the piston bowl is detected. The findings of this investigation are compared with similar measurements in simplified engine configurations and reveal a satisfactory qualitative as well as quantitative agreement.

  16. MEaSUREs Greenland Ice Velocity: Selected Glacier Site Velocity Maps from Optical Images, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, consists of mean monthly velocity maps for...

  17. Measuring Average Angular Velocity with a Smartphone Magnetic Field Sensor

    Science.gov (United States)

    Pili, Unofre; Violanda, Renante

    2018-01-01

    The angular velocity of a spinning object is, by standard, measured using a device called a tachometer. However, by directly using it in a classroom setting, the activity is likely to appear as less instructive and less engaging. Indeed, some alternative classroom-suitable methods for measuring angular velocity have been presented. In this paper,…

  18. Fat mass measured by DXA varies with scan velocity

    DEFF Research Database (Denmark)

    Black, Eva; Petersen, Liselotte; Kreutzer, Martin

    2002-01-01

    To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight.......To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight....

  19. GPM GROUND VALIDATION DUAL-FREQUENCY DUAL-POLARIZED DOPPLER RADAR (D3R) IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Dual-frequency Dual-polarized Doppler Radar (D3R) IFloodS data set contain radar reflectivity and doppler velocity measurements. The D3R...

  20. GPM Ground Validation Dual-frequency Dual-polarized Doppler Radar (D3R) OLYMPEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation OLYMPEX Dual-frequency Dual-polarized Doppler Radar (D3R) dataset contains radar reflectivity and doppler velocity measurements. The D3R...

  1. GPM GROUND VALIDATION DUAL-FREQUENCY DUAL-POLARIZED DOPPLER RADAR (D3R) GCPEX V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Dual-frequency Dual-polarized Doppler Radar (D3R) GCPEx and IFloodS data sets contain radar reflectivity and doppler velocity measurements....

  2. A comparative study of calculated and measured particle velocities

    International Nuclear Information System (INIS)

    Tariq, S.M.

    2005-01-01

    After an explosive is detonated in a blast hole, seismic waves are generated in the ground surrounding the blast hole. These waves cause the particles of rock to oscillate about its position. As the wave attenuate, the particles come back to their original position. The rapidity with which the particles move is called the particle velocity. The peak or maximum velocity is the value which is of prime concern. This value of peak particle velocity can be estimated by the equations determined by the United States Bureau of Mines and by the DUPONT. A research program was conducted by the author at the 'Beck Materials Quarry' situated near Rolla, Missouri, USA. The purpose was to draw a comparison between the predicted and measured particle velocities. It was generally found that the predicted peak particle velocities were quite high as compared to the velocities measured by the Seismographs. (author)

  3. The effect of chamber mixing velocity on bias in measurement of sediment oxygen demand rates in the Tualatin River basin, Oregon

    Science.gov (United States)

    Doyle, Micelis C.; Rounds, Stewart

    2003-01-01

    Three sediment oxygen demand (SOD) measurement chambers were deployed in the Tualatin River near Tigard, Oregon, at river mile 10 in August 2000. SOD rates were calculated for three different circulation velocities during each chamber deployment. The SOD rate at each velocity was calculated from a graph of dissolved oxygen concentration versus elapsed time. An acoustic doppler current profiler (ADCP) was used to measure stream discharge and near-bottom water velocities in the Tualatin at river mile 10 and at two upstream locations. Measured river and chamber velocities were similar, indicating that results from the chambers were representative of instream effects.

  4. Maritime target and sea clutter measurements with a coherent Doppler polarimetric surveillance radar

    NARCIS (Netherlands)

    Smith, A.J.E.; Gelsema, S.J.; Kester, L.J.H.M.; Melief, H.W.; Premel Cabic, G.; Theil, A.; Woudenberg, E.

    2002-01-01

    Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary

  5. Insensitivity of single particle time domain measurements to laser velocimeter 'Doppler ambiguity.'

    Science.gov (United States)

    Johnson, D. A.

    1973-01-01

    It is shown that single particle time domain measurements in high speed gas flows obtained by a laser velocimeter technique developed for use in wind tunnels are not affected by the so-called 'Doppler ambiguity.' A comparison of hot-wire anemometer and laser velocimeter measurements taken under similar flow conditions is used for the demonstration.

  6. Measurement of velocity and velocity derivatives based on pattern tracking in 3D LIF images

    Energy Technology Data Exchange (ETDEWEB)

    Deusch, S.; Merava, H.; Rys, P. [Swiss Federal Inst. of Technol., Zurich (Switzerland). Dept. of Chem. Eng.; Dracos, T. [Swiss Federal Institute of Technology, Untergasse 14, 8126 Zumikon (Switzerland)

    2000-10-01

    Pattern tracking in consecutive 3D LIF images based on least squares matching (LSM) of grey levels has been developed recently for velocity and velocity gradient measurements. The shortcomings of this method are clearly shown. The present article presents an improvement on this method by introducing a local multi-patch (LMP) technique through the LSM approach. The method is validated using the flow field of a turbulent channel flow obtained by direct numerical simulation (DNS) and a synthetic image with grey-level patterns. The results show that LMP matching allows the determination of the velocity and the velocity gradient fields with high accuracy including the second derivatives. Measurements of a round non-buoyant jet are presented which demonstrate the good performance of the method when applied under laboratory conditions. This method can also be applied on two-dimensional images provided that the flow is strictly two-dimensional. (orig.)

  7. Measurement of velocity and velocity derivatives based on pattern tracking in 3D LIF images

    Science.gov (United States)

    Deusch, S.; Merava, H.; Dracos, T.; Rys, P.

    Pattern tracking in consecutive 3D LIF images based on least squares matching (LSM) of grey levels has been developed recently for velocity and velocity gradient measurements. The shortcomings of this method are clearly shown. The present article presents an improvement on this method by introducing a local multi-patch (LMP) technique through the LSM approach. The method is validated using the flow field of a turbulent channel flow obtained by direct numerical simulation (DNS) and a synthetic image with grey-level patterns. The results show that LMP matching allows the determination of the velocity and the velocity gradient fields with high accuracy including the second derivatives. Measurements of a round non-buoyant jet are presented which demonstrate the good performance of the method when applied under laboratory conditions. This method can also be applied on two-dimensional images provided that the flow is strictly two-dimensional.

  8. Measurement of two-dimensional Doppler wind fields using a field widened Michelson interferometer.

    Science.gov (United States)

    Langille, Jeffery A; Ward, William E; Scott, Alan; Arsenault, Dennis L

    2013-03-10

    An implementation of the field widened Michelson concept has been applied to obtain high resolution two-dimensional (2D) images of low velocity (interferometer scanning mirror position is controlled to subangstrom precision with subnanometer repeatability using the multi-application low-voltage piezoelectric instrument control electronics developed by COM DEV Ltd.; it is the first implementation of this system as a phase stepping Michelson. In this paper the calibration and characterization of the Doppler imaging system is described and the planned implementation of this new technique for imaging 2D wind and irradiance fields using the earth's airglow is introduced. Observations of Doppler winds produced by a rotating wheel are reported and shown to be of sufficient precision for buoyancy wave observations in airglow in the mesopause region of the terrestrial atmosphere.

  9. Three-dimensional instantaneous velocity field measurement using ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... set equal to 20 μl/min. The instantaneous 3D velocity field is obtained by correlating the particles obtained from the 3D numerical reconstruction of holograms using particle tracking velocimetry. (PTV). Keywords. Holography; velocity measurements; laminar flow in microchannel. PACS Nos 42.40.–i; 06.30.

  10. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A.D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  11. Plasma flow velocity measurements using a modulated Michelson interferometer

    NARCIS (Netherlands)

    Howard, J.; Meijer, F. G.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (C) 1997 Elsevier Science S.A.

  12. Electron drift velocity measurements in liquid krypton-methane mixtures

    CERN Document Server

    Folegani, M; Magri, M; Piemontese, L

    1999-01-01

    Electron drift velocities have been measured in liquid krypton, pure and mixed with methane at different concentrations (1-10% in volume) versus electric field strength, and a possible effect of methane on electron lifetime has been investigated. While no effect on lifetime could be detected, since lifetimes were in all cases longer than what measurable, a very large increase in drift velocity (up to a factor 6) has been measured.

  13. Measurement of sound velocity profiles in fluids for process monitoring

    International Nuclear Information System (INIS)

    Wolf, M; Kühnicke, E; Lenz, M; Bock, M

    2012-01-01

    In ultrasonic measurements, the time of flight to the object interface is often the only information that is analysed. Conventionally it is only possible to determine distances or sound velocities if the other value is known. The current paper deals with a novel method to measure the sound propagation path length and the sound velocity in media with moving scattering particles simultaneously. Since the focal position also depends on sound velocity, it can be used as a second parameter. Via calibration curves it is possible to determine the focal position and sound velocity from the measured time of flight to the focus, which is correlated to the maximum of averaged echo signal amplitude. To move focal position along the acoustic axis, an annular array is used. This allows measuring sound velocity locally resolved without any previous knowledge of the acoustic media and without a reference reflector. In previous publications the functional efficiency of this method was shown for media with constant velocities. In this work the accuracy of these measurements is improved. Furthermore first measurements and simulations are introduced for non-homogeneous media. Therefore an experimental set-up was created to generate a linear temperature gradient, which also causes a gradient of sound velocity.

  14. Doppler lidar results from the San Gorgonio Pass experiments

    Science.gov (United States)

    Cliff, W. C.; Skarda, J. R.; Renne, D. S.

    1984-01-01

    During FY-84, the Doppler Lidar data from the San Gorgonio Pass experiments were analyzed, evaluated, and interpreted with regard to signal strength, signal width, magnitude and direction of velocity component and a goodness parameter associated with the expected noise level of the signal. From these parameters, a screening criteria was developed to eliminate questionable data. For the most part analysis supports the validity of Doppler Lidar data obtained at San Gorgonio Pass with respect to the mean velocity magnitude and direction. The question as to whether the Doppler width could be interpreted as a measure of the variance of the turbulence within the Doppler Lidar System (DLS) focal volume was not resolved. The stochastic nature of the Doppler broadening from finite residence time of the particles in the beam as well as other Doppler broadening phenomenon tend to mask the Doppler spread associated with small scale turbulence. Future tests with longer pulses may assist in better understanding.

  15. A prospective comparative study to assess the effect of maternal smoking at 37 weeks on Doppler flow velocity waveforms as well as foetal birth weight and placental weight.

    Science.gov (United States)

    Alptekin, Hüsnü; Işık, Hatice; Alptekin, Nazife; Kayhan, Fatih; Efe, Duran; Cengiz, Türkan; Gök, Emine

    2017-02-01

    Maternal smoking is known to have adverse effects on the foetus. This study aimed to evaluate the effects of maternal smoking during pregnancy on arterial blood flow velocities in the foetal-placental-maternal circulation, and the pathophysiological relationship with placental and foetal birth weight. A total of 148 singleton pregnancies in 59 smokers and 89 non-smoking controls were examined during the 37th week of gestation. Blood flow in the maternal uterine, foetal umbilical and middle cerebral arteries was analysed with Doppler ultrasonography. Statistically significant differences in Doppler waveforms were detected in the foetal umbilical artery (UmbA) (p  0.05). Both infant birthweight and placental weight were significantly decreased by maternal smoking (psmoking during pregnancy did not affect either maternal uterine or foetal middle cerebral arterial blood flow, but caused abnormal blood flow in the foetal UmbA.

  16. Three Component Velocity and Acceleration Measurement Using FLEET

    Science.gov (United States)

    Danehy, Paul M.; Bathel, Brett F.; Calvert, Nathan; Dogariu, Arthur; Miles, Richard P.

    2014-01-01

    The femtosecond laser electronic excitation and tagging (FLEET) method has been used to measure three components of velocity and acceleration for the first time. A jet of pure N2 issuing into atmospheric pressure air was probed by the FLEET system. The femtosecond laser was focused down to a point to create a small measurement volume in the flow. The long-lived lifetime of this fluorescence was used to measure the location of the tagged particles at different times. Simultaneous images of the flow were taken from two orthogonal views using a mirror assembly and a single intensified CCD camera, allowing two components of velocity to be measured in each view. These different velocity components were combined to determine three orthogonal velocity components. The differences between subsequent velocity components could be used to measure the acceleration. Velocity accuracy and precision were roughly estimated to be +/-4 m/s and +/-10 m/s respectively. These errors were small compared to the approx. 100 m/s velocity of the subsonic jet studied.

  17. A Plasma Edge Electron Density Diagnostic Based on a Doppler-free Measurement of Stark Broadening

    Science.gov (United States)

    Zafar, Abdullah; Martin, Elijah; Shannon, Steve

    2017-10-01

    Passive spectroscopic measurements of Stark broadening have been reliably used to determine electron density for decades. A low-density limit of 1e19 m-3 exists using these passive techniques due to Doppler and instrument broadening. At Oak Ridge National Laboratory, a novel diagnostic approach for measuring electron density using Stark broadening is currently under development and is capable of extending the low-density limit to 1e16 m-3 . The diagnostic is based on measuring the spectral line profile of a Balmer series transition using Doppler-free saturation spectroscopy, a laser-based absorption technique. The spectrum is then fit to a quantum mechanical model using the Explicit Zeeman Stark Spectral Simulator (EZSSS) code to extract the electron density. The increased sensitivity to the electron density is realized because Doppler-free saturation spectroscopy (DFSS) can greatly reduce the Doppler broadening and essentially eliminate the instrument broadening. DFSS has been successfully employed to measure spectral data in a magnetized (500-800 G), low temperature (5 eV), low density (1e17-1e18 m-3), He/H2 and He/CH4 plasma in the mTorr pressure range. Experimentally measured pi and sigma H-alpha spectra, fit using the EZSSS code, will be presented. A quantitative model to accurately predict crossover peaks and dips will also be given. This work was supported by the US. D.O.E. contract DE-AC05-00OR22725.

  18. Tissue Doppler echocardiography reveals distinct patterns of impaired myocardial velocities in different degrees of coronary artery disease

    DEFF Research Database (Denmark)

    Hoffmann, Soren; Mogelvang, Rasmus; Olsen, Niels Thue

    2010-01-01

    ) were divided into three groups according to significant one-, two-, or three-vessel disease (n = 18, n = 14, and n = 15, respectively). Regional longitudinal peak systolic (s'), early (e'), and late diastolic (a') myocardial velocities were measured at six mitral annular sites and averaged to provide.......86 +/- 0.24 vs. 1.00 +/- 0.28, P reduced in patients with three-vessels disease. CONCLUSION: Colour TDI performed at rest in patients with stable angina and preserved ejection fraction reveals both diastolic and systolic dysfunction and the nature...

  19. Measurements of the toroidal plasma rotation velocity in TFTR major-radius compression experiments with auxiliary neutral beam heating

    International Nuclear Information System (INIS)

    Bitter, M.; Wong, K.L.; Scott, S.; Hsuan, H.; Grek, B.; Johnson, D.; Tait, G.

    1990-01-01

    The time history of the central toroidal plasma rotation velocity in Tokamak Fusion Test Reactor (TFTR) experiments [Phys. Rev. Lett. 55, 2587 (1985)] with auxiliary heating by neutral deuterium beam injection and major-radius compression has been measured from the Doppler shift of the emitted Ti XXI Kα line radiation. The experiments were conducted for neutral beam powers in the range 2.1--3.8 MW and line-averaged densities in the range 1.8--3.0x10 19 m -2 . The observed rotation velocity increase during compression is consistent with theoretical estimates

  20. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  1. Near-wall velocity profile measurement for nanofluids

    Directory of Open Access Journals (Sweden)

    Anoop Kanjirakat

    2016-01-01

    Full Text Available We perform near-wall velocity measurements of a SiO2–water nanofluid inside a microchannel. Nanoparticle image velocimetry measurements at three visible depths within 500 nm of the wall are conducted. We evaluate the optical properties of the nanofluid and their effect on the measurement technique. The results indicate that the small effect of the nanoparticles on the optical properties of the suspension have a negligible effect on the measurement technique. Our measurements show an increase in nanofluid velocity gradients near the walls, with no measurable slip, relative to the equivalent basefluid flow. We conjecture that particle migration induced by shear may have caused this increase. The effect of this increase in the measured near wall velocity gradient has implications on the viscosity measurement for these fluids.

  2. Dynamical critical scaling of electric field fluctuations in the greater cusp and magnetotail implied by HF radar observations of F-region Doppler velocity

    Directory of Open Access Journals (Sweden)

    M. L. Parkinson

    2006-03-01

    Full Text Available Akasofu's solar wind ε parameter describes the coupling of solar wind energy to the magnetosphere and ionosphere. Analysis of fluctuations in ε using model independent scaling techniques including the peaks of probability density functions (PDFs and generalised structure function (GSF analysis show the fluctuations were self-affine (mono-fractal, single exponent scaling over 9 octaves of time scale from ~46 s to ~9.1 h. However, the peak scaling exponent α0 was a function of the fluctuation bin size, so caution is required when comparing the exponents for different data sets sampled in different ways. The same generic scaling techniques revealed the organisation and functional form of concurrent fluctuations in azimuthal magnetospheric electric fields implied by SuperDARN HF radar measurements of line-of-sight Doppler velocity, vLOS, made in the high-latitude austral ionosphere. The PDFs of vLOS fluctuation were calculated for time scales between 1 min and 256 min, and were sorted into noon sector results obtained with the Halley radar, and midnight sector results obtained with the TIGER radar. The PDFs were further sorted according to the orientation of the interplanetary magnetic field, as well as ionospheric regions of high and low Doppler spectral width. High spectral widths tend to occur at higher latitude, mostly on open field lines but also on closed field lines just equatorward of the open-closed boundary, whereas low spectral widths are concentrated on closed field lines deeper inside the magnetosphere. The vLOS fluctuations were most self-affine (i.e. like the solar wind ε parameter on the high spectral width field lines in the noon sector ionosphere (i.e. the greater cusp, but suggested multi-fractal behaviour on closed field lines in the midnight sector (i.e. the central plasma sheet. Long tails in the PDFs imply that "microbursts" in ionospheric convection occur far more frequently, especially on open field lines, than can be

  3. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

    Salewski, Mirko; Geiger, B.; Heidbrink, W. W.

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion Dα (FIDA) spectroscopy measurements in magnetically confined plasma......, the Dα-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright...... and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography and what can be learned by comparison of these applications....

  4. CALF BLOOD-FLOW AND POSTURE - DOPPLER ULTRASOUND MEASUREMENTS DURING AND AFTER EXERCISE

    NARCIS (Netherlands)

    VANLEEUWEN, BE; BARENDSEN, GJ; LUBBERS, J; DEPATER, L

    To investigate the joint effects of body posture and calf muscle pump, the calf blood flow of eight healthy volunteers was measured with pulsed Doppler equipment during and after 3 min of rhythmic exercise on a calf ergometer in the supine, sitting, and standing postures. Muscle contractions

  5. The diagnosis of deep venous thrombosis using laser Doppler skin perfusion measurements

    NARCIS (Netherlands)

    de Graaff, J. C.; Ubbink, D. T.; Büller, H. R.; Jacobs, M. J.

    2001-01-01

    Compression ultrasonography (CUS) falls short in the diagnosis of deep venous thrombosis in asymptomatic patients and thrombi limited to the calf veins. Alternatively, laser Doppler fluxmetry (LDF) may be useful for this purpose, as it can measure the peripheral vasoconstriction response upon an

  6. Detonation Velocity Measurement with Chirped Fiber Bragg Grating

    OpenAIRE

    Wei, Peng; Lang, Hao; Liu, Taolin; Xia, Dong

    2017-01-01

    Detonation velocity is an important parameter for explosive, and it is crucial for many fields such as dynamic chemistry burn models, detonation propagation prediction, explosive performance estimation, and so on. Dual-channel detonation velocity measurement method and system are described. The CFBG sensors are pasted both on the surface and in the center of the explosive cylinder. The length of CFBG sensors is measured via the hot-tip probe method. The light intensity reflected from the CFBG...

  7. Measurement of Poloidal Velocity on the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ronald E. Bell and Russell Feder

    2010-06-04

    A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.

  8. Projectile Impact Point Prediction Based on Self-Propelled Artillery Dynamics and Doppler Radar Measurements

    Directory of Open Access Journals (Sweden)

    Mostafa Khalil

    2013-01-01

    Full Text Available Any trajectory calculation method has three primary sources of errors, which are model error, parameter error, and initial state error. In this paper, based on initial projectile flight trajectory data measured using Doppler radar system; a new iterative method is developed to estimate the projectile attitude and the corresponding impact point to improve the second shot hit probability. In order to estimate the projectile initial state, the launch dynamics model of practical 155 mm self-propelled artillery is defined, and hence, the vibration characteristics of the self-propelled artillery is obtained using the transfer matrix method of linear multibody system MSTMM. A discrete time transfer matrix DTTM-4DOF is developed using the modified point mass equations of motion to compute the projectile trajectory and set a direct algebraic relation between any two successive radar data. During iterations, adjustments to the repose angle are made until an agreement with acceptable tolerance occurs between the Doppler radar measurements and the estimated values. Simulated Doppler radar measurements are generated using the nonlinear six-degree-of-freedom trajectory model using the resulted initial disturbance. Results demonstrate that the data estimated using the proposed algorithm agrees well with the simulated Doppler radar data obtained numerically using the nonlinear six-degree-of-freedom model.

  9. Air speed and velocity measurements in a room with a sidewall jet

    Directory of Open Access Journals (Sweden)

    M. Hurnik

    2015-12-01

    Full Text Available In mixing ventilation systems, diffusers are often located on side walls and supply quasi-free air jets above the occupied zone. The data presented in this paper shows a new CFD 3D benchmark with two well-defined characteristic zones in the room, i.e., the quasi-free jet zone and the occupied zone. Measurement methods adequate for air velocity and speed measurement were applied: laser Doppler anemometry for the axial velocity component in the jet and low velocity thermal anemometry for the air speed in the occupied zone. Measurements were performed in a physical scale model (1:5 of the room. The kinematic similarity criterion was fulfilled by the equality of the Reynolds numbers in the model and in the prototype. To identify boundary conditions, additional measurements were carried out in the inlet region (as close as possible to the supply opening. The CFD results validation and reporting methods applicable for the benchmark data are proposed in Hurnik et al. (2015 [1].

  10. Color doppler and power doppler ultrasonography in renal transplant recipients with cytomegalovirus infection

    International Nuclear Information System (INIS)

    Wan Guangsheng; Chen Xionghui; Li Meidi; Shao Zheying; Peng Shubai

    2003-01-01

    Objective: To investigate the features of color Doppler and Doppler ultrasonography of transplanted kidneys in patients with cytomegalovirus infections. Methods: Color Doppler and Power Doppler ultrasonography was used to examine transplanted kidneys in 36 recipients with cytomegalovirus infection. The blood flow area ratios (BFAR), the volumes, the resistive indexes (RI), the peak flow velocities in parenchymal arteries (Vmax) were measured and compared with no complication (normal) cases. Results: BFAR was lower in patients with cytomegalovirus infection than that in no complication (normal) cases (P 0.05). Conclusions: The blood flows of transplanted kidneys were reduced in patients with cytomegalovirus infection. To monitor BFAR of transplanted kidneys was contributed to evaluate management effect

  11. Measuring the Bed Load velocity in Laboratory flumes using ADCP and Digital Cameras

    Science.gov (United States)

    Conevski, Slaven; Guerrero, Massimo; Rennie, Colin; Bombardier, Josselin

    2017-04-01

    Measuring the transport rate and apparent velocity of the bedload is notoriously hard and there is not a certain technique that would obtain continues data. There are many empirical models, based on the estimation of the shear stress, but only few involve direct measurement of the bed load velocity. The bottom tracking (BT) mode of an acoustic Doppler current profiler (ADCP) has been used many times to estimate the apparent velocity of the bed load. Herein is the basic idea, to exploit the bias of the BT signal towards the bed load movement and to calibrate this signal with traditional measuring techniques. These measurements are quite scarce and seldom reliable since there are not taken in controlled conditions. So far, no clear confirmation has been conducted in laboratory-controlled conditions that would attest the assumptions made in the estimation of the apparent bed load velocity, nor in the calibration of the empirical equations. Therefore, this study explores several experiments under stationary conditions, where the signal of the ADCP BT mode is recorded and compared to the bed load motion recorded by digital camera videography. The experiments have been performed in the hydraulic laboratories of Ottawa and Bologna, using two different ADCPs and two different high resolution cameras. In total, more then 30 experiments were performed for different sediment mixtures and different hydraulic conditions. In general, a good match is documented between the apparent bed load velocity measured by the ADCP and the videography. The slight deviation in single experiments can be explained by gravel particles inhomogeneity, difficult in reproducing the same hydro-sedimentological conditions and the randomness of the backscattering strength.

  12. Transverse and Longitudinal Doppler Effects of the Sunbeam Spectra and Earth-Self Rotation and Orbital Velocities, the Mass of the Sun and Others

    OpenAIRE

    Nam, Sang Boo

    2009-01-01

    The transverse and longitudinal Doppler effects of the sunbeam spectra are shown to result in the earth parameters such as the earth-self rotation and revolution velocities, the earth orbit semi-major axis, the earth orbital angular momentum, the earth axial tilt, the earth orbit eccentricity, the local latitude and the mass of the sun. The sunbeam global positioning scheme is realized, including the earth orbital position. PACS numbers: 91.10.Fc, 95.10.Km, 91.10.Da, 91.10.Jf.

  13. Analysis of the Uncertainty in Wind Measurements from the Atmospheric Radiation Measurement Doppler Lidar during XPIA: Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, Rob [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-01

    In March and April of 2015, the ARM Doppler lidar that was formerly operated at the Tropical Western Pacific site in Darwin, Australia (S/N 0710-08) was deployed to the Boulder Atmospheric Observatory (BAO) for the eXperimental Planetary boundary-layer Instrument Assessment (XPIA) field campaign. The goal of the XPIA field campaign was to investigate methods of using multiple Doppler lidars to obtain high-resolution three-dimensional measurements of winds and turbulence in the atmospheric boundary layer, and to characterize the uncertainties in these measurements. The ARM Doppler lidar was one of many Doppler lidar systems that participated in this study. During XPIA the 300-m tower at the BAO site was instrumented with well-calibrated sonic anemometers at six levels. These sonic anemometers provided highly accurate reference measurements against which the lidars could be compared. Thus, the deployment of the ARM Doppler lidar during XPIA offered a rare opportunity for the ARM program to characterize the uncertainties in their lidar wind measurements. Results of the lidar-tower comparison indicate that the lidar wind speed measurements are essentially unbiased (~1cm s-1), with a random error of approximately 50 cm s-1. Two methods of uncertainty estimation were tested. The first method was found to produce uncertainties that were too low. The second method produced estimates that were more accurate and better indicators of data quality. As of December 2015, the first method is being used by the ARM Doppler lidar wind value-added product (VAP). One outcome of this work will be to update this VAP to use the second method for uncertainty estimation.

  14. Outlier Detection in GNSS Pseudo-Range/Doppler Measurements for Robust Localization

    Directory of Open Access Journals (Sweden)

    Salim Zair

    2016-04-01

    Full Text Available In urban areas or space-constrained environments with obstacles, vehicle localization using Global Navigation Satellite System (GNSS data is hindered by Non-Line Of Sight (NLOS and multipath receptions. These phenomena induce faulty data that disrupt the precise localization of the GNSS receiver. In this study, we detect the outliers among the observations, Pseudo-Range (PR and/or Doppler measurements, and we evaluate how discarding them improves the localization. We specify a contrario modeling for GNSS raw data to derive an algorithm that partitions the dataset between inliers and outliers. Then, only the inlier data are considered in the localization process performed either through a classical Particle Filter (PF or a Rao-Blackwellization (RB approach. Both localization algorithms exclusively use GNSS data, but they differ by the way Doppler measurements are processed. An experiment has been performed with a GPS receiver aboard a vehicle. Results show that the proposed algorithms are able to detect the ‘outliers’ in the raw data while being robust to non-Gaussian noise and to intermittent satellite blockage. We compare the performance results achieved either estimating only PR outliers or estimating both PR and Doppler outliers. The best localization is achieved using the RB approach coupled with PR-Doppler outlier estimation.

  15. Outlier Detection in GNSS Pseudo-Range/Doppler Measurements for Robust Localization.

    Science.gov (United States)

    Zair, Salim; Le Hégarat-Mascle, Sylvie; Seignez, Emmanuel

    2016-04-22

    In urban areas or space-constrained environments with obstacles, vehicle localization using Global Navigation Satellite System (GNSS) data is hindered by Non-Line Of Sight (NLOS) and multipath receptions. These phenomena induce faulty data that disrupt the precise localization of the GNSS receiver. In this study, we detect the outliers among the observations, Pseudo-Range (PR) and/or Doppler measurements, and we evaluate how discarding them improves the localization. We specify a contrario modeling for GNSS raw data to derive an algorithm that partitions the dataset between inliers and outliers. Then, only the inlier data are considered in the localization process performed either through a classical Particle Filter (PF) or a Rao-Blackwellization (RB) approach. Both localization algorithms exclusively use GNSS data, but they differ by the way Doppler measurements are processed. An experiment has been performed with a GPS receiver aboard a vehicle. Results show that the proposed algorithms are able to detect the 'outliers' in the raw data while being robust to non-Gaussian noise and to intermittent satellite blockage. We compare the performance results achieved either estimating only PR outliers or estimating both PR and Doppler outliers. The best localization is achieved using the RB approach coupled with PR-Doppler outlier estimation.

  16. A mixing method for traceable air velocity measurements

    International Nuclear Information System (INIS)

    Sillanpää, S; Heinonen, M

    2008-01-01

    A novel and quite simple method to establish a traceability link between air velocity and the national standards of mass and time is presented in this paper. The method is based on the humidification of flowing air before the blower of a wind tunnel with a known mass flow of water. Then air velocity can be calculated as a function of humidification water flow. The method is compared against a Pitot-tube-based velocity measurement in a wind tunnel at the MIKES. The results of these two different methods agreed well, with a maximum difference of 0.7%

  17. Measurement bias of fluid velocity in molecular simulations

    International Nuclear Information System (INIS)

    Tysanner, Martin W.; Garcia, Alejandro L.

    2004-01-01

    In molecular simulations of fluid flow, the measurement of mean fluid velocity is considered to be a straightforward computation, yet there is some ambiguity in its definition. We show that in systems far from equilibrium, such as those with large temperature or velocity gradients, two commonly used definitions give slightly different results. Specifically, a bias can arise when computing the mean fluid velocity by measuring the mean particle velocity in a cell and averaging this mean over samples. We show that this bias comes from the correlation of momentum and density fluctuations in non-equilibrium fluids, obtain an analytical expression for predicting it, and discuss what system characteristics (e.g., number of particles per cell, temperature gradients) reduce or magnify the error. The bias has a physical origin so although we demonstrate it by direct simulation Monte Carlo (DSMC) computations, the same effect will be observed with other particle-based simulation methods, such as molecular dynamics and lattice gases

  18. Evaluation and accuracy of the local velocity data measurements in an agitated vessel

    Directory of Open Access Journals (Sweden)

    Kysela Bohuš

    2014-03-01

    Full Text Available Velocity measurements of the flow field in an agitated vessel are necessary for the improvement and better understanding of the mixing processes. The obtained results are used for the calculations of the impeller pumping capacity, comparison of the power consumption etc. We performed various measurements of the local velocities in an agitated vessel final results of which should be processed for several purposes so it was necessary to make an analysis of the obtained data suitability and their quality. Analysed velocity data were obtained from the LDA (Laser Doppler Anemometry and PIV (Particle Image Velocimetry measurements performed on a standard equipment where the flat bottomed vessel with four baffles was agitated by the six-blade Rushton turbine. The results from both used methods were compared. The frequency analyses were examined as well as the dependency of the data rates, time series lengths etc. The demands for the data processed in the form of the ensemble-averaged results were also established.

  19. Interferometric method for measuring high velocities of diffuse surfaces

    International Nuclear Information System (INIS)

    Maron, Y.

    1978-01-01

    An interferometric method for measuring the displacement of diffuse surfaces moving with velocities of a few microsecond is presented. The method utilizes the interference between two light beams reflected from a constant area of the moving surface at two different angles. It enables the detection of high rate velocity variations. Light source of a fairly low temporal coherence and power around 100mW is needed. (author)

  20. Measurements of electron drift velocity in pure isobutane

    International Nuclear Information System (INIS)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio

    2009-01-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  1. Measurements of electron drift velocity in pure isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B., E-mail: ccbueno@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept de Fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  2. Remote measurement of surface-water velocity using infrared videography and PIV: a proof-of-concept for Alaskan rivers

    Science.gov (United States)

    Kinzel, Paul J.; Legleiter, Carl; Nelson, Jonathan M.; Conaway, Jeffrey S.

    2017-01-01

    Thermal cameras with high sensitivity to medium and long wavelengths can resolve features at the surface of flowing water arising from turbulent mixing. Images acquired by these cameras can be processed with particle image velocimetry (PIV) to compute surface velocities based on the displacement of thermal features as they advect with the flow. We conducted a series of field measurements to test this methodology for remote sensing of surface velocities in rivers. We positioned an infrared video camera at multiple stations across bridges that spanned five rivers in Alaska. Simultaneous non-contact measurements of surface velocity were collected with a radar gun. In situ velocity profiles were collected with Acoustic Doppler Current Profilers (ADCP). Infrared image time series were collected at a frequency of 10Hz for a one-minute duration at a number of stations spaced across each bridge. Commercial PIV software used a cross-correlation algorithm to calculate pixel displacements between successive frames, which were then scaled to produce surface velocities. A blanking distance below the ADCP prevents a direct measurement of the surface velocity. However, we estimated surface velocity from the ADCP measurements using a program that normalizes each ADCP transect and combines those normalized transects to compute a mean measurement profile. The program can fit a power law to the profile and in so doing provides a velocity index, the ratio between the depth-averaged and surface velocity. For the rivers in this study, the velocity index ranged from 0.82 – 0.92. Average radar and extrapolated ADCP surface velocities were in good agreement with average infrared PIV calculations.

  3. Improved Micro Rain Radar snow measurements using Doppler spectra post-processing

    Directory of Open Access Journals (Sweden)

    M. Maahn

    2012-11-01

    Full Text Available The Micro Rain Radar 2 (MRR is a compact Frequency Modulated Continuous Wave (FMCW system that operates at 24 GHz. The MRR is a low-cost, portable radar system that requires minimum supervision in the field. As such, the MRR is a frequently used radar system for conducting precipitation research. Current MRR drawbacks are the lack of a sophisticated post-processing algorithm to improve its sensitivity (currently at +3 dBz, spurious artefacts concerning radar receiver noise and the lack of high quality Doppler radar moments. Here we propose an improved processing method which is especially suited for snow observations and provides reliable values of effective reflectivity, Doppler velocity and spectral width. The proposed method is freely available on the web and features a noise removal based on recognition of the most significant peak. A dynamic dealiasing routine allows observations even if the Nyquist velocity range is exceeded. Collocated observations over 115 days of a MRR and a pulsed 35.2 GHz MIRA35 cloud radar show a very high agreement for the proposed method for snow, if reflectivities are larger than −5 dBz. The overall sensitivity is increased to −14 and −8 dBz, depending on range. The proposed method exploits the full potential of MRR's hardware and substantially enhances the use of Micro Rain Radar for studies of solid precipitation.

  4. Reduced arteriovenous shunting capacity after local heating and redistribution of baseline skin blood flow in type 2 diabetes assessed with velocity-resolved quantitative laser Doppler flowmetry.

    Science.gov (United States)

    Fredriksson, Ingemar; Larsson, Marcus; Nyström, Fredrik H; Länne, Toste; Ostgren, Carl J; Strömberg, Tomas

    2010-07-01

    To compare the microcirculatory velocity distribution in type 2 diabetic patients and nondiabetic control subjects at baseline and after local heating. The skin blood flow response to local heating (44 degrees C for 20 min) was assessed in 28 diabetic patients and 29 control subjects using a new velocity-resolved quantitative laser Doppler flowmetry technique (qLDF). The qLDF estimates erythrocyte (RBC) perfusion (velocity x concentration), in a physiologically relevant unit (grams RBC per 100 g tissue x millimeters per second) in a fixed output volume, separated into three velocity regions: v 10 mm/s. The increased blood flow occurs in vessels with a velocity >1 mm/s. A significantly lower response in qLDF total perfusion was found in diabetic patients than in control subjects after heat provocation because of less high-velocity blood flow (v >10 mm/s). The RBC concentration in diabetic patients increased sevenfold for v between 1 and 10 mm/s, and 15-fold for v >10 mm/s, whereas no significant increase was found for v velocity increased from 0.94 to 7.3 mm/s in diabetic patients and from 0.83 to 9.7 mm/s in control subjects. The perfusion increase occurs in larger shunting vessels and not as an increase in capillary flow. Baseline diabetic patient data indicated a redistribution of flow to higher velocity regions, associated with longer duration of diabetes. A lower perfusion was associated with a higher BMI and a lower toe-to-brachial systolic blood pressure ratio.

  5. Numerical Simulation Modelling for Velocity Measurement of Electromagnetic Flow Meter

    International Nuclear Information System (INIS)

    Wang, J Z; Gong, C L; Tian, G Y; Lucas, G P

    2006-01-01

    An induced voltage EMF in the area of measuring single-phase flow rate in pipes has been used in many industrial areas. To measure the continuous phase velocity profile in multiphase flows where the continuous phase is an electrical conductor, Electrical capacitance and resistance tomography has been comprehensively investigated, except for continuous phase velocity profile measurement. This paper tries to design the numerical simulation model according to the basic electromagnetic induction law and to investigate the relationship between induced electric potential or potential drop and the velocity distribution of the conductive continuous phase in the flow. First, the 3-Dimenssion simulating module for EMF is built. Given the most simple velocity profile of the fluid in the pipe, the value of the induced potential difference between electrodes is obtained by simulation and theoretical computation according to J A Shercliff's weight function. The relative error is 6.066 . This proves that the simulation model is accurate enough to investigate the characteristic of the induced potential difference of EMF. Finally, the relationship between induced potential difference and the velocity profile is analysed in detail where the complicated velocity profile is expressed as vz = 1m/s when 0.022< x2+y2< = 0.02652 and vz = 5m/s when x2+y2< = 0.022

  6. Upscaling Point Velocity Measurements to Characterize a Glacial Outwash Aquifer.

    Science.gov (United States)

    Schillig, P C; Devlin, J F; Rudolph, D

    2016-05-01

    Small-scale point velocity probe (PVP)-derived velocities were compared to conventional large-scale velocity estimates from Darcy calculations and tracer tests, and the possibility of upscaling PVP data to match the other velocity estimates was evaluated. Hydraulic conductivity was estimated from grain-size data derived from cores, and single-well response testing or slug tests of onsite wells. Horizontal hydraulic gradients were calculated using 3-point estimators from all of the wells within an extensive monitoring network, as well as by representing the water table as a single best fit plane through the entire network. Velocities determined from PVP testing were generally consistent in magnitude with those from depth specific data collected from multilevel monitoring locations in the tracer test, and similar in horizontal flow direction to the average hydraulic gradient. However, scaling up velocity estimates based on PVP measurements for comparison with site-wide Darcy-based velocities revealed issues that challenge the use of Darcy calculations as a generally applicable standard for comparison. The Darcy calculations were shown to underestimate the groundwater velocities determined both by the PVPs and large-scale tracer testing, in a depth-specific sense and as a site-wide average. Some of this discrepancy is attributable to the selective placement of the PVPs in the aquifer. Nevertheless, this result has important implications for the design of in situ treatment systems. It is concluded that Darcy estimations of velocity should be supplemented with independent assessments for these kinds of applications. © 2015, National Ground Water Association.

  7. Patch near field acoustic holography based on particle velocity measurements

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Jacobsen, Finn; Bi, Chuan-Xing

    2009-01-01

    Patch near field acoustic holography (PNAH) based on sound pressure measurements makes it possible to reconstruct the source field near a source by measuring the sound pressure at positions on a surface. that is comparable in size to the source region of concern. Particle velocity is an alternative...

  8. Velocity and size distribution measurement of suspension droplets using PDPA technique

    Science.gov (United States)

    Amiri, Shahin; Akbarnozari, Ali; Moreau, Christian; Dolatabadi, Ali

    2015-11-01

    The creation of fine and uniform droplets from a bulk of liquid is a vital process in a variety of engineering applications, such as atomization in suspension plasma spray (SPS) in which the submicron coating materials are injected to the plasma gas through the suspension droplets. The size and velocity of these droplets has a great impact on the interaction of the suspension with the gas flow emanating from a plasma torch and can consequently affect the mechanical and chemical properties of the resultant coatings. In the current study, an aqueous suspension of small glass particles (2-8 μm) was atomized by utilizing an effervescent atomizer of 1 mm orifice diameter which involves bubbling gas (air) directly into the liquid stream. The gas to liquid ratio (GLR) was kept constant at 6% throughout this study. The mass concentration of glass particles varied in the range between 0.5 to 5% in order to investigate the effect of suspension viscosity and surface tension on the droplet characteristics, such as velocity and size distributions. These characteristics were simultaneously measured by using a non-intrusive optical technique, Phase Doppler Particle Anemometry (PDPA), which is based on the light signal scattered from the droplets moving in a measurement volume. The velocity and size distribution of suspension droplets were finally compared to those of distilled water under identical conditions. The results showed a different atomization behaviors due to the reduction in surface tension of the suspension spray.

  9. Ultrasonic Doppler measurement technique for the diagnosis of non-steady state multi-phase flow processes; Ultraschall-Doppler-Messtechnik zur Diagnose instationaerer Mehrphasen-Stroemungsvorgaenge

    Energy Technology Data Exchange (ETDEWEB)

    Specht, O.; Fiedler, O. [Rostock Univ. (Germany). Fachbereich Elektrotechnik; Skerl, O.

    1997-12-01

    In many areas of technology and in industry, there is an increasing requirement for a flexible, non-invasive measurement technique for flow speeds and through flows. The ultrasonic clamp-on measurement technique can fulfil these requirements and is being used to an increasing extent. The application of this technique only presupposes the acoustic transparency of the pipe wall, which is the case for most materials, such as metals, plastics and glass. The ultrasonic running time process is preferred to the Doppler process for mainly one-phase fluids. Due to its working principle, the ultrasonic Doppler process depends on multi-phase fluids, because it uses the frequency displacement of the sound waves backscattered at the phase boundaries as the measurement parameter for the speed of flow. [Deutsch] In vielen Bereichen der Technik und in der Industrie besteht zunehmend die Forderung nach einer flexiblen, nichtinvasiven Messtechnik fuer Stroemungsgeschwindigkeiten und Durchfluesse. Die Ultraschall-Clamp-On-Messtechnik kann diese Anforderungen erfuellen und wird in wachsendem Umfang eingesetzt. Die Anwendung dieser Technik setzt nur die akustische Transparenz der Rohrwand voraus, was fuer die meisten Materialien wie Metalle, Kunststoffe und Glas der Fall ist. Bei ueberwiegend einphasigen Fluiden wird das Ultraschall-Laufzeit-Verfahren gegenueber dem Doppler-Verfahren bevorzugt. Das Ultraschall-Doppler-Verfahren ist nach seinem Wirkprinzip auf mehrphasige Fluide angewiesen, denn es nutzt die Frequenzverschiebung der an den Phasengrenzen rueckgestreuten Schallwellen als Messgroesse fuer die Stroemungsgeschwindigkeit. (orig.)

  10. Detonation Velocity Measurement with Chirped Fiber Bragg Grating.

    Science.gov (United States)

    Wei, Peng; Lang, Hao; Liu, Taolin; Xia, Dong

    2017-11-06

    Detonation velocity is an important parameter for explosive, and it is crucial for many fields such as dynamic chemistry burn models, detonation propagation prediction, explosive performance estimation, and so on. Dual-channel detonation velocity measurement method and system are described. The CFBG sensors are pasted both on the surface and in the center of the explosive cylinder. The length of CFBG sensors is measured via the hot-tip probe method. The light intensity reflected from the CFBG sensors attached to the explosive is transformed to voltage, and the voltage-time is then measured with the oscilloscope. According to the five experiments results, the relative standard uncertainty of detonation velocity is below 1%.

  11. Detonation Velocity Measurement with Chirped Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Peng Wei

    2017-11-01

    Full Text Available Detonation velocity is an important parameter for explosive, and it is crucial for many fields such as dynamic chemistry burn models, detonation propagation prediction, explosive performance estimation, and so on. Dual-channel detonation velocity measurement method and system are described. The CFBG sensors are pasted both on the surface and in the center of the explosive cylinder. The length of CFBG sensors is measured via the hot-tip probe method. The light intensity reflected from the CFBG sensors attached to the explosive is transformed to voltage, and the voltage–time is then measured with the oscilloscope. According to the five experiments results, the relative standard uncertainty of detonation velocity is below 1%.

  12. Measurement of the neutrino velocity in OPERA experiment

    International Nuclear Information System (INIS)

    Dracos, M.

    2013-01-01

    The OPERA neutrino experiment has measured the neutrino velocity using the CERN CNGS beam over a baseline of 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010, 2011. An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (6.5±7.4(stat.) −8.0 +8.3 (sys.))ns was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light (v−c)/c=(2.7±3.1(stat.) −3.3 +3.4 (sys.))×10 −6 . During spring 2012 the CNGS provided during two weeks a short proton bunched beam dedicated to the neutrino velocity measurement. The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos with slightly modified setup compared to 2011 measurements. These modifications increased the timing accuracy and also fixed previous problems. The arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum has been found to be in agreement with the previous measurement. This result confirms the revised OPERA result and that indeed the neutrino anticipation announced in September 2011 was due to technical problems

  13. Innovative Coal Solids-Flow Monitoring and Measurement Using Phase-Doppler and Mie Scattering Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Seong Lee

    2010-01-19

    Fuel flow to individual burners is complicated and difficult to determine on coal fired boilers, since coal solids were transported in a gas suspension that is governed by the complex physics of two-phase flow. The objectives of the project were the measurements of suspended coal solids-flows in the simulated test conditions. Various extractive methods were performed manually and can give only a snapshot result of fuel distribution. In order to measure particle diameter & velocity, laser based phase-Doppler particle analyzer (PDPA) and particle image velocimetry (PIV) were carefully applied. Statistical methods were used to analyze particle characteristics to see which factors have significant effect. The transparent duct model was carefully designed and fabricated for the laser-based-instrumentation of solids-flow monitoring (LISM). The experiments were conducted with two different kinds of particles with four different particle diameters. The particle types were organic particles and saw dust particles with the diameter range of 75-150 micron, 150-250 micron, 250-355 micron and 355-425 micron. The densities of the particles were measured to see how the densities affected the test results. Also the experiment was conducted with humid particles and fog particles. To generate humid particles, the humidifier was used. A pipe was connected to the humidifier to lead the particle flow to the intersection of the laser beam. The test results of the particle diameter indicated that, the mean diameter of humid particles was between 6.1703 microns and 6.6947 microns when the humid particle flow was low. When the humid particle flow was high, the mean diameter was between 6.6728 microns and 7.1872 microns. The test results of the particle mean velocity indicated that the mean velocity was between 1.3394 m/sec and 1.4556 m/sec at low humid particle flow. When the humid particle flow was high, the mean velocity was between 1.5694 m/sec and 1.7856 m/sec. The Air Flow Module, TQ

  14. Velocity-space sensitivity of neutron spectrometry measurements

    DEFF Research Database (Denmark)

    Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.

    2015-01-01

    Neutron emission spectrometry (NES) measures the energies of neutrons produced in fusion reactions. Here we present velocity-space weight functions for NES and neutron yield measurements. Weight functions show the sensitivity as well as the accessible regions in velocity space for a given range...... of the neutron energy spectrum. Combined with a calculated fast-ion distribution function, they determine the part of the distribution function producing detectable neutrons in a given neutron energy range. Furthermore, we construct a forward model based on weight functions capable of rapidly calculating neutron...

  15. Comparing Pulsed Doppler LIDAR with SODAR and Direct Measurements for Wind Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N. D.; Jonkman, B. J.; Scott, G. N.; Pichugina, Y. L.

    2007-07-01

    There is a pressing need for good wind-speed measurements at greater and greater heights to assess the availability of the resource in terms of power production and to identify any frequently occurring atmospheric structural characteristics that may create turbulence that impacts the operational reliability and lifetime of wind turbines and their components. In this paper, we summarize the results of a short study that compares the relative accuracies of wind speeds derived from a high-resolution pulsed Doppler LIDAR operated by the National Oceanic and Atmospheric Administration (NOAA) and a midrange Doppler SODAR with wind speeds measured by four levels of tower-based sonic anemometry up to a height of 116 m.

  16. Method and system to measure temperature of gases using coherent anti-stokes doppler spectroscopy

    Science.gov (United States)

    Rhodes, Mark

    2013-12-17

    A method of measuring a temperature of a noble gas in a chamber includes providing the noble gas in the chamber. The noble gas is characterized by a pressure and a temperature. The method also includes directing a first laser beam into the chamber and directing a second laser beam into the chamber. The first laser beam is characterized by a first frequency and the second laser beam is characterized by a second frequency. The method further includes converting at least a portion of the first laser beam and the second laser beam into a coherent anti-Stokes beam, measuring a Doppler broadening of the coherent anti-Stokes beam, and computing the temperature using the Doppler broadening.

  17. Hemodynamic study of ischemic limb by velocity measurement in foot

    International Nuclear Information System (INIS)

    Shionoya, S.; Hirai, M.; Kawai, S.; Ohta, T.; Seko, T.

    1981-01-01

    By means of a tracer technique with 99mTc-pertechnetate, provided with seven zonal regions of interest, 6 mm in width, placed at equal spaces of 18 mm, from the toe tip to the midfoot at a right angle to the long axis of the foot, arterial flow velocity in the foot during reactive hyperemia was measured. The mean velocity in the foot was 5.66 +/- 1.78 cm/sec in 14 normal limbs, 1.58 +/- 1.07 cm/sec in 29 limbs with distal thromboangiitis obliterans (TAO), 0.89 +/- 0.61 cm/sec in 13 limbs with proximal TAO, and 0.97 +/- 0.85 cm/sec in 15 limbs with arteriosclerosis obliterans (ASO). The velocity returned to normal in all 12 limbs after successful arterial reconstruction, whereas the foot or toe blood pressure remained pathologic in 9 of the 12 limbs postoperatively; the velocity reverted to normal in 4 of 13 limbs after lumbar sympathectomy. When the velocity was normalized after operation, the ulceration healed favorably, and the ischemic limb was salvaged. The most characteristic feature of peripheral arterial occlusive disease of the lower extremity was a stagnation of arterial circulation in the foot, and the flow velocity in the foot was a sensitive predictive index of limb salvage

  18. Use of High Sensitivity GNSS Receiver Doppler Measurements for Indoor Pedestrian Dead Reckoning

    OpenAIRE

    Renaudin, Valérie; ZHE, He; PETOVELLO, Mark G.; Lachapelle, Gérard

    2013-01-01

    Dead-reckoning (DR) algorithms, which use self-contained inertial sensors combined with gait analysis, have proven to be effective for pedestrian navigation purposes. In such DR systems, the primary error is often due to accumulated heading drifts. By tightly integrating global navigation satellite system (GNSS) Doppler measurements with DR, such accumulated heading errors can usually be accurately compensated. Under weak signal conditions, high sensitivity GNSS (HSGNSS) receivers with block ...

  19. Coherence measures in automatic time-migration velocity analysis

    International Nuclear Information System (INIS)

    Maciel, Jonathas S; Costa, Jessé C; Schleicher, Jörg

    2012-01-01

    Time-migration velocity analysis can be carried out automatically by evaluating the coherence of migrated seismic events in common-image gathers (CIGs). The performance of gradient methods for automatic time-migration velocity analysis depends on the coherence measures used as the objective function. We compare the results of four different coherence measures, being conventional semblance, differential semblance, an extended differential semblance using differences of more distant image traces and the product of the latter with conventional semblance. In our numerical experiments, the objective functions based on conventional semblance and on the product of conventional semblance with extended differential semblance provided the best velocity models, as evaluated by the flatness of the resulting CIGs. The method can be easily extended to anisotropic media. (paper)

  20. Study on time-varying velocity measurement with self-mixing laser diode based on Discrete Chirp-Fourier Transform

    International Nuclear Information System (INIS)

    Zhang Zhaoyun; Gao Yang; Zhao Xinghai; Zhao Xiang

    2011-01-01

    Laser's optical output power and frequency are modulated when the optical beam is back-scattered into the active cavity of the laser. By signal processing, the Doppler frequency can be acquired, and the target's velocity can be calculated. Based on these properties, an interferometry velocity sensor can be designed. When target move in time-varying velocity mode, it is difficult to extract the target's velocity. Time-varying velocity measurement by self-mixing laser diode is explored. A mathematics model was proposed for the time-varying velocity (invariable acceleration) measurement by self-mixing laser diode. Based on this model, a Discrete Chirp-Fourier Transform (DCFT) method was applied, DCFT is analogous to DFT. We show that when the signal length N is prime, the magnitudes of all the side lobes are 1, whereas the magnitudes of the main lobe is √N, And the coordinates of the main lobe shows the target's velocity and acceleration information. The simulation results prove the validity of the algorithm even in the situation of low SNR when N is prime.

  1. Comparison of bottom-track to global positioning system referenced discharges measured using an acoustic Doppler current profiler

    Science.gov (United States)

    Wagner, Chad R.; Mueller, David S.

    2011-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) can be caused by the movement of sediment on or near the streambed. The integration of a global positioning system (GPS) to track the movement of the ADCP can be used to avoid the systematic negative bias associated with a moving streambed. More than 500 discharge transects from 63 discharge measurements with GPS data were collected at sites throughout the US, Canada, and New Zealand with no moving bed to compare GPS and bottom-track-referenced discharges. Although the data indicated some statistical bias depending on site conditions and type of GPS data used, these biases were typically about 0.5% or less. An assessment of differential correction sources was limited by a lack of data collected in a range of different correction sources and different GPS receivers at the same sites. Despite this limitation, the data indicate that the use of Wide Area Augmentation System (WAAS) corrected positional data is acceptable for discharge measurements using GGA as the boat-velocity reference. The discharge data based on GPS-referenced boat velocities from the VTG data string, which does not require differential correction, were comparable to the discharges based on GPS-referenced boat velocities from the differentially-corrected GGA data string. Spatial variability of measure discharges referenced to GGA, VTG and bottom-tracking is higher near the channel banks. The spatial variability of VTG-referenced discharges is correlated with the spatial distribution of maximum Horizontal Dilution of Precision (HDOP) values and the spatial variability of GGA-referenced discharges is correlated with proximity to channel banks.

  2. The 3 December 2015 paroxysm of Voragine crater at Etna: insights from Doppler radar measurements

    Science.gov (United States)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Gouhier, Mathieu; Coltelli, Mauro; Scollo, Simona; Fréville, Patrick; Hervier, Claude; Prestifilippo, Michele

    2016-04-01

    After a progressive intensification of Strombolian activity inside the Voragine crater in the evening of December 2 2015, Mount Etna produced a short but violent paroxysm in the night of 3 December 2015, the most intense of the last two decades at Voragine. Lava fountains, observed with the network of thermal and visible cameras of INGV-OE, reached well over 1 km in height with some jets of incandescent material reaching 3 km. A tephra column several kilometers high was produced and pyroclastic material was dispersed by winds in altitude to the NE, causing ash fallouts to affect many towns in Sicily and Reggio Calabria. A 23 cm-wavelength Doppler radar (VOLDORAD 2B), located about 3 km from NSEC at the Montagnola station and integrated into the INGV-OE instrumental network, has been continuously monitoring the explosive activity of Mt. Etna's summit craters since 2009. The radar beam probes 13 successive volumes 150 m deep aligned northward above the summit craters, providing two sets of parameters (echo power and velocity) at a rate of 0.2 s. We analyze the paroxysmal event of Voragine using the radar echoes and Doppler signals coming from volumes inside the lava fountain feeding the tephra column in combination with thermal and visible imagery and satellite data. The radar range gating allowed us to immediately discriminate the central craters as the source of the tephra emission and to estimate the lava fountain width between 300 and 450 m. The backscattered power, which is related to the erupted tephra mass load in the beam, and Doppler velocities help to mark the transition from Strombolian activity to lava fountaining, providing onset and end times of the fountain. The tephra flux into the radar beam started to increase after 02:00 UTC with a strong increase at 02:20 UTC marking the transition to continuous lava fountaining. The climax was reached between ca. 02:35 and 03:15 UTC with maintained high echo power and ejection velocities of 190 m/s in average

  3. Tissue Doppler echocardiography reveals distinct patterns of impaired myocardial velocities in different degrees of coronary artery disease

    DEFF Research Database (Denmark)

    Hoffmann, Soren; Mogelvang, Rasmus; Olsen, Niels Thue

    2010-01-01

    Aim To determine how the left ventricular wall motion assessed by echocardiographic Tissue Doppler Imaging (TDI) is affected by increasing severity of coronary artery disease (CAD) among patients with stable angina pectoris and preserved ejection fraction. METHODS AND RESULTS: This study comprises...... global estimates. Each patient with significant coronary disease was matched with a control of the same age, sex, body mass index, and status regarding diabetes and hypertension. Global systolic and diastolic performance by TDI (in terms of global s' and E/e') were negatively correlated to the number...

  4. Three-dimensional instantaneous velocity field measurement using ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... In the present study, a digital holography microscope has been developed to study instantaneous 3D ... Rv. 1. Introduction. Digital holography is a nonintrusive optical technique having immense potential for 3D .... microscope (DHM) for 3D instantaneous velocity field measurements in microchannels.

  5. Utilisation of the Rapsodie reactor for the measurement of the doppler effect

    International Nuclear Information System (INIS)

    Zaleski, C.P.; Abdon, R.; Ladet, J.; Ping, I.; Steven, L.

    1964-01-01

    This report shows how a special loading of a 400 liters core in the reactor 'Rapsodie' could simulate the same neutronic conditions as those encountered in power fast reactors. Various methods designed to measure the Doppler effect in this core are described and compared. In particular, a computation of the errors involved is set. This computation would bring us to think that such an experiment could give a valid estimation of the Doppler coefficient of large fast reactors. The neutronic computations set for this study are described in an annex. - This report(the annex excepted) has already been presented by Freddy STORRER at the conference on breeding: Economics and safety in large fast breeder reactors at Argonne National Laboratory, october 1963 and published in the Proceedings (ANL 6792). (authors) [fr

  6. Measurement of acoustic velocity components in a turbulent flow using LDV and high-repetition rate PIV

    Science.gov (United States)

    Léon, Olivier; Piot, Estelle; Sebbane, Delphine; Simon, Frank

    2017-06-01

    The present study provides theoretical details and experimental validation results to the approach proposed by Minotti et al. (Aerosp Sci Technol 12(5):398-407, 2008) for measuring amplitudes and phases of acoustic velocity components (AVC) that are waveform parameters of each component of velocity induced by an acoustic wave, in fully turbulent duct flows carrying multi-tone acoustic waves. Theoretical results support that the turbulence rejection method proposed, based on the estimation of cross power spectra between velocity measurements and a reference signal such as a wall pressure measurement, provides asymptotically efficient estimators with respect to the number of samples. Furthermore, it is shown that the estimator uncertainties can be simply estimated, accounting for the characteristics of the measured flow turbulence spectra. Two laser-based measurement campaigns were conducted in order to validate the acoustic velocity estimation approach and the uncertainty estimates derived. While in previous studies estimates were obtained using laser Doppler velocimetry (LDV), it is demonstrated that high-repetition rate particle image velocimetry (PIV) can also be successfully employed. The two measurement techniques provide very similar acoustic velocity amplitude and phase estimates for the cases investigated, that are of practical interest for acoustic liner studies. In a broader sense, this approach may be beneficial for non-intrusive sound emission studies in wind tunnel testings.

  7. Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 1: Computer simulation of ionospheric-induced Doppler shifts

    Science.gov (United States)

    Grossi, M. D.; Gay, R. H.

    1975-01-01

    A computer simulation of the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) was performed. ASTP is the first example of USA/USSR cooperation in space and is scheduled for summer 1975. The experiment consists of performing dual-frequency Doppler measurements (at 162 and 324 MHz) between the Apollo Command Service Module (CSM) and the ASTP Docking Module (DM), both orbiting at 221-km height and at a relative distance of 300 km. The computer simulation showed that, with the Doppler measurement resolution of approximately 3 mHz provided by the instrumentation (in 10-sec integration time), ionospheric-induced Doppler shifts will be measurable accurately at all times, with some rare exceptions occurring when the radio path crosses regions of minimum ionospheric density. The computer simulation evaluated the ability of the experiment to measure changes of columnar electron content between CSM and DM (from which horizontal gradients of electron density at 221-km height can be obtained) and to measure variations in DM-to-ground columnar content (from which an averaged columnar content and the electron density at the DM can be deduced, under some simplifying assumptions).

  8. Measuring discharge with acoustic Doppler current profilers from a moving boat

    Science.gov (United States)

    Mueller, David S.; Wagner, Chad R.; Rehmel, Michael S.; Oberg, Kevin A.; Rainville, Francois

    2013-01-01

    The use of acoustic Doppler current profilers (ADCPs) from a moving boat is now a commonly used method for measuring streamflow. The technology and methods for making ADCP-based discharge measurements are different from the technology and methods used to make traditional discharge measurements with mechanical meters. Although the ADCP is a valuable tool for measuring streamflow, it is only accurate when used with appropriate techniques. This report presents guidance on the use of ADCPs for measuring streamflow; this guidance is based on the experience of U.S. Geological Survey employees and published reports, papers, and memorandums of the U.S. Geological Survey. The guidance is presented in a logical progression, from predeployment planning, to field data collection, and finally to post processing of the collected data. Acoustic Doppler technology and the instruments currently (2013) available also are discussed to highlight the advantages and limitations of the technology. More in-depth, technical explanations of how an ADCP measures streamflow and what to do when measuring in moving-bed conditions are presented in the appendixes. ADCP users need to know the proper procedures for measuring discharge from a moving boat and why those procedures are required, so that when the user encounters unusual field conditions, the procedures can be adapted without sacrificing the accuracy of the streamflow-measurement data.

  9. Radar speed gun true velocity measurements of sports-balls in flight: application to tennis

    Science.gov (United States)

    Robinson, Garry; Robinson, Ian

    2016-02-01

    Spectators of ball-games often seem to be fascinated by the speed of delivery of the ball. They appear to be less interested in or even oblivious to the mechanism and accuracy of the measurement or where in the flight path of the ball the measurement is actually made. Radar speed guns using the Doppler effect are often employed for such speed measurements. It is well known that such guns virtually always measure the line-of-sight or radial velocity of the ball and as such will return a reading less than or equal to the true speed of the ball. In this paper, using only basic physics principles we investigate such measurements, in particular those associated with the service stroke in tennis. For the service trajectories employed here, a single radar gun located in line with the centre-line of the court in fact under-estimates the speed of a wide serve by about 3.4% at the point of delivery, and by about 14.3% on impact with the court. However, we demonstrate that both the magnitude and direction of the true velocity of the ball throughout its entire flight path may be obtained, at least in principle, by the use of four suitably placed radar speed guns. These four guns must be able to measure the ‘range’ to the ball, enabling its position in flight to be determined, and three of them must be able to measure the radial velocity of the ball. Restrictions on the locations of the speed guns are discussed. Such restrictions are quite liberal, although there are certain configurations of the radar gun positions which cannot be used. Importantly, with the one proviso that no speed gun can be directly in the path of the ball (not only for the obvious reasons), we find that if the speed of the ball can be determined for one point in the trajectory, it can also be determined for all points. The accuracy of the range and radial velocity measurements required to give meaningful results for the true velocity are also briefly discussed. It is found that the accuracy required

  10. Radar speed gun true velocity measurements of sports-balls in flight: application to tennis

    International Nuclear Information System (INIS)

    Robinson, Garry; Robinson, Ian

    2016-01-01

    Spectators of ball-games often seem to be fascinated by the speed of delivery of the ball. They appear to be less interested in or even oblivious to the mechanism and accuracy of the measurement or where in the flight path of the ball the measurement is actually made. Radar speed guns using the Doppler effect are often employed for such speed measurements. It is well known that such guns virtually always measure the line-of-sight or radial velocity of the ball and as such will return a reading less than or equal to the true speed of the ball. In this paper, using only basic physics principles we investigate such measurements, in particular those associated with the service stroke in tennis. For the service trajectories employed here, a single radar gun located in line with the centre-line of the court in fact under-estimates the speed of a wide serve by about 3.4% at the point of delivery, and by about 14.3% on impact with the court. However, we demonstrate that both the magnitude and direction of the true velocity of the ball throughout its entire flight path may be obtained, at least in principle, by the use of four suitably placed radar speed guns. These four guns must be able to measure the ‘range’ to the ball, enabling its position in flight to be determined, and three of them must be able to measure the radial velocity of the ball. Restrictions on the locations of the speed guns are discussed. Such restrictions are quite liberal, although there are certain configurations of the radar gun positions which cannot be used. Importantly, with the one proviso that no speed gun can be directly in the path of the ball (not only for the obvious reasons), we find that if the speed of the ball can be determined for one point in the trajectory, it can also be determined for all points. The accuracy of the range and radial velocity measurements required to give meaningful results for the true velocity are also briefly discussed. It is found that the accuracy required

  11. Relationship Between Uterine and Ovarian Arterial Blood Flow Measured by Doppler Sonography at Different Stages of Puberty

    Directory of Open Access Journals (Sweden)

    Reza Golestani

    2008-03-01

    Conclusion: Uterine and ovarian arterial blood flow, measured by Doppler sonography, was not useful for the evaluation of pubertal stages. However, it should be investigated with a greater sample size.

  12. Sub-Doppler spectroscopy

    International Nuclear Information System (INIS)

    Hansch, T.W.

    1983-01-01

    This chapter examines Doppler-free saturation spectroscopy, tunable cw sources, and Doppler-free two-photon spectroscopy. Discusses saturation spectroscopy; continuous wave saturation spectroscopy in the ultraviolet; and two-photon spectroscopy of atomic hydrogen 1S-2S. Focuses on Doppler-free laser spectroscopy of gaseous samples. Explains that in saturation spectroscopy, a monochromatic laser beam ''labels'' a group of atoms within a narrow range of axial velocities through excitation or optical pumping, and a Doppler-free spectrum of these selected atoms is observed with a second, counterpropagating beam. Notes that in two-photon spectroscopy it is possible to record Doppler-free spectra without any need for velocity selection by excitation with two counterpropagating laser beams whose first order Doppler shifts cancel

  13. Synchronized Measurements of Maximum Blood Flow Velocities in Carotid, Brachial and Femoral Arteries, and ECG in Human Posture Changes

    National Research Council Canada - National Science Library

    Hirao, Y

    2001-01-01

    ...., sitting to standing and standing to sitting) using an ultrasonic Doppler technique. The ultrasonic Doppler technique can measure the dynamics of blood flow in arteries that exist deep within the human body...

  14. Sources of measurement error in laser Doppler vibrometers and proposal for unified specifications

    Science.gov (United States)

    Siegmund, Georg

    2008-06-01

    The focus of this paper is to disclose sources of measurement error in laser Doppler vibrometers (LDV) and to suggest specifications, suitable to describe their impact on measurement uncertainty. Measurement errors may be caused by both the optics and electronics sections of an LDV, caused by non-ideal measurement conditions or imperfect technical realisation. While the contribution of the optics part can be neglected in most cases, the subsequent signal processing chain may cause significant errors. Measurement error due to non-ideal behaviour of the interferometer has been observed mainly at very low vibration amplitudes and depending on the optical arrangement. The paper is organized as follows: Electronic signal processing blocks, beginning with the photo detector, are analyzed with respect to their contribution to measurement uncertainty. A set of specifications is suggested, adopting vocabulary and definitions known from traditional vibration measurement equipment. Finally a measurement setup is introduced, suitable for determination of most specifications utilizing standard electronic measurement equipment.

  15. Velocity measurement accuracy in optical microhemodynamics: experiment and simulation

    International Nuclear Information System (INIS)

    Chayer, Boris; Cloutier, Guy; L Pitts, Katie; Fenech, Marianne

    2012-01-01

    Micro particle image velocimetry (µPIV) is a common method to assess flow behavior in blood microvessels in vitro as well as in vivo. The use of red blood cells (RBCs) as tracer particles, as generally considered in vivo, creates a large depth of correlation (DOC), even as large as the vessel itself, which decreases the accuracy of the method. The limitations of µPIV for blood flow measurements based on RBC tracking still have to be evaluated. In this study, in vitro and in silico models were used to understand the effect of the DOC on blood flow measurements using µPIV RBC tracer particles. We therefore employed a µPIV technique to assess blood flow in a 15 µm radius glass tube with a high-speed CMOS camera. The tube was perfused with a sample of 40% hematocrit blood. The flow measured by a cross-correlating speckle tracking technique was compared to the flow rate of the pump. In addition, a three-dimensional mechanical RBC-flow model was used to simulate optical moving speckle at 20% and 40% hematocrits, in 15 and 20 µm radius circular tubes, at different focus planes, flow rates and for various velocity profile shapes. The velocity profiles extracted from the simulated pictures were compared with good agreement with the corresponding velocity profiles implemented in the mechanical model. The flow rates from both the in vitro flow phantom and the mathematical model were accurately measured with less than 10% errors. Simulation results demonstrated that the hematocrit (paired t tests, p = 0.5) and the tube radius (p = 0.1) do not influence the precision of the measured flow rate, whereas the shape of the velocity profile (p < 0.001) and the location of the focus plane (p < 0.001) do, as indicated by measured errors ranging from 3% to 97%. In conclusion, the use of RBCs as tracer particles makes a large DOC and affects the image processing required to estimate the flow velocities. We found that the current µPIV method is acceptable to estimate the flow rate

  16. A prototype of radar-drone system for measuring the surface flow velocity at river sites and discharge estimation

    Science.gov (United States)

    Moramarco, Tommaso; Alimenti, Federico; Zucco, Graziano; Barbetta, Silvia; Tarpanelli, Angelica; Brocca, Luca; Mezzanotte, Paolo; Rosselli, Luca; Orecchini, Giulia; Virili, Marco; Valigi, Paolo; Ciarfuglia, Thomas; Pagnottelli, Stefano

    2015-04-01

    Discharge estimation at a river site depends on local hydraulic conditions identified by recording water levels. In fact, stage monitoring is straightforward and relatively inexpensive compared with the cost necessary to carry out flow velocity measurements which are, however, limited to low flows and constrained by the accessibility of the site. In this context the mean flow velocity is hard to estimate for high flow, affecting de-facto the reliability of discharge assessment for extreme events. On the other hand, the surface flow velocity can be easily monitored by using radar sensors allowing to achieve a good estimate of discharge by exploiting the entropy theory applied to rivers hydraulic (Chiu,1987). Recently, a growing interest towards the use of Unmanned Aerial Vehicle (UVA), henceforth drone, for topographic applications is observed and considering their capability drones may be of a considerable interest for the hydrological monitoring and in particular for streamflow measurements. With this aim, for the first time, a miniaturized Doppler radar sensor, operating at 24 GHz, will be mounted on a drone to measure the surface flow velocity in rivers. The sensor is constituted by a single-board circuit (i.e. is a fully planar circuits - no waveguides) with the antenna on one side and the front-end electronic on the other side (Alimenti et al., 2007). The antenna has a half-power beam width of less than 10 degrees in the elevation plane and a gain of 13 dBi. The radar is equipped with a monolithic oscillator and transmits a power of about 4 mW at 24 GHz. The sensor is mounted with an inclination of 45 degrees with respect to the drone flying plane and such an angle is considered in recovering the surface speed of the water. The drone is a quadricopter that has more than 30 min, flying time before recharging the battery. Furthermore its flying plan can be scheduled with a suitable software and is executed thanks to the on-board sensors (GPS, accelerometers

  17. Quantification of displacement and velocity noise in vibrometer measurements on transversely moving or rotating surfaces

    Science.gov (United States)

    Dräbenstedt, Alexander

    2007-06-01

    The heterodyne interferometer (vibrometer) is a well established technique for measuring all kinds of mechanical vibrations in a broad range of applications. The non-contact measurement principle relies upon the Doppler (or phase-) shift that laser light experiences when it is reflected by the vibrating surface. The speckle nature of the reflected light imposes problems and creates additional measurement noise if the object is moving transversely through the laser spot or is rotating around an axis perpendicular to the laser direction. Another implication that can arise is cross coupling from in-plane vibrations into the out-of-plane measurement direction when small in-plane vibrations are present. A model is presented in this paper that describes the origin of these disturbances. Using this model it is possible to quantify the amplitude spectrum of the noise in displacement and velocity measurements. This enables the user to calculate the limits of resolvable vibration amplitudes when transverse motion is present. The results of the model have been confirmed well by measurements. In addition, the influence of the surface roughness and beam inclination on the out-of-plane vibration measurements at a tilted surface is investigated. The conditions for the measurability of the profile of a transversely moving surface are derived in this work. It is discussed that the R q-roughness parameter has to be less than λ/4 to obtain the slope information in the speckle-perturbed interferometer signal.

  18. Investigation of gravity waves using horizontally resolved radial velocity measurements

    Science.gov (United States)

    Stober, G.; Sommer, S.; Rapp, M.; Latteck, R.

    2013-10-01

    The Middle Atmosphere Alomar Radar System (MAARSY) on the island of Andøya in Northern Norway (69.3° N, 16.0° E) observes polar mesospheric summer echoes (PMSE). These echoes are used as tracers of atmospheric dynamics to investigate the horizontal wind variability at high temporal and spatial resolution. MAARSY has the capability of pulse-to-pulse beam steering allowing for systematic scanning experiments to study the horizontal structure of the backscatterers as well as to measure the radial velocities for each beam direction. Here we present a method to retrieve gravity wave parameters from these horizontally resolved radial wind variations by applying velocity azimuth display and volume velocity processing. Based on the observations a detailed comparison of the two wind analysis techniques is carried out in order to determine the zonal and meridional wind as well as to measure first-order inhomogeneities. Further, we demonstrate the possibility to resolve the horizontal wave properties, e.g., horizontal wavelength, phase velocity and propagation direction. The robustness of the estimated gravity wave parameters is tested by a simple atmospheric model.

  19. Investigation of gravity waves using horizontally resolved radial velocity measurements

    Directory of Open Access Journals (Sweden)

    G. Stober

    2013-10-01

    Full Text Available The Middle Atmosphere Alomar Radar System (MAARSY on the island of Andøya in Northern Norway (69.3° N, 16.0° E observes polar mesospheric summer echoes (PMSE. These echoes are used as tracers of atmospheric dynamics to investigate the horizontal wind variability at high temporal and spatial resolution. MAARSY has the capability of pulse-to-pulse beam steering allowing for systematic scanning experiments to study the horizontal structure of the backscatterers as well as to measure the radial velocities for each beam direction. Here we present a method to retrieve gravity wave parameters from these horizontally resolved radial wind variations by applying velocity azimuth display and volume velocity processing. Based on the observations a detailed comparison of the two wind analysis techniques is carried out in order to determine the zonal and meridional wind as well as to measure first-order inhomogeneities. Further, we demonstrate the possibility to resolve the horizontal wave properties, e.g., horizontal wavelength, phase velocity and propagation direction. The robustness of the estimated gravity wave parameters is tested by a simple atmospheric model.

  20. Measurement of the parallel velocity distribution function of the electron beam in a quasi-optical gyrotron by electron cyclotron emission

    International Nuclear Information System (INIS)

    Soumagne, G.; Alberti, S.; Hogge, J.P.; Pedrozzi, M.; Siegrist, M.R.; Tran, M.Q.; Tran, T.M.

    1996-03-01

    The parallel velocity distribution function of the weakly relativistic electron beam of a quasi-optical gyrotron (QOG) has been determined by measuring the Doppler-shifted Electron Cyclotron Emission (ECE) at an angle θ=15 o with respect to the external magnetic DC-field. Due to the Doppler shift, the frequency of the spontaneous cyclotron emission at the fundamental (ν 0 =100 GHz) is upshifted to 140 GHz. A broadening of the spectrum up to 10 GHz (Full Width at Half Maximum FWHM) was measured. The measured mean frequency agrees well with the theoretical predictions, but the observed line-width, and hence the parallel velocity distribution function, is 2-3 times larger than expected. Considerations on ECE-measurements of the electron beam energy spread, performed at larger angles θ, are also discussed. (author) 12 figs., 18 refs

  1. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H.; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been...... vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new...

  2. Correlation between ocular pulse amplitude measured by dynamic contour tonometer and colour doppler flow imaging of the arteric retrobulbar vessels

    Directory of Open Access Journals (Sweden)

    Marjanović Ivan

    2011-01-01

    Full Text Available Introduction. An altered perfusion of the optic nerve head has been proposed as a pathogenic factor in glaucoma. Objective. The aim of this study was to evaluate the correlation between ocular pulse amplitude (OPA, measured by Dynamic contour tonometer (DCT and colour Doppler imaging (CDI of the arteric retro- bulbar vessels. Methods. Twenty patients older than 50 years were examined, and divided into two equal groups. The first group comprised of patients with normal tension glaucoma treated with topical antiglaucomatous therapy, and the second group included patients with ocular hypertension and glaucoma suspicious without any antiglaucomatous therapy. Ocular pulse amplitude (OPA was measured with DCT. CDI was also performed. We measured haemodynamic parameters of the internal carotid artery (ICA, ophthalmic artery (OA, central retinal artery (CRA, and posterior ciliary arteries (PCA. Peak systolic (PSV, end- diastolic (EDV velocities were measured, and resistance index (RI and pulsatility index (PI were calculated. Results Correlation with OPA showed indirect servitude in the RI of the ICA, RI and PI of the CRA, in the first group; and in the PSV and EDV of the ICA, in the RI and PI of the OA, EDV and RI of the CRA, and RI of the PCA, in the second group Conclusion. Increase of OPA was mostly followed by the increase of the parameters (PSV, EDV, RI, and PI of the arteric retrobulbar vessels in the first group; in the second group, increase of OPA was in almost 50% of parameters followed by their decrease.

  3. Discharge estimation combining flow routing and occasional measurements of velocity

    Directory of Open Access Journals (Sweden)

    G. Corato

    2011-09-01

    Full Text Available A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data at a single gauged site, as well as 1-D shallow water modelling and occasional maximum surface flow velocity measurements. One-dimensional diffusive hydraulic model is used for routing the recorded stage hydrograph in the channel reach considering zero-diffusion downstream boundary condition. Based on synthetic tests concerning a broad prismatic channel, the "suitable" reach length is chosen in order to minimize the effect of the approximated downstream boundary condition on the estimation of the upstream discharge hydrograph. The Manning's roughness coefficient is calibrated by using occasional instantaneous surface velocity measurements during the rising limb of flood that are used to estimate instantaneous discharges by adopting, in the flow area, a two-dimensional velocity distribution model. Several historical events recorded in three gauged sites along the upper Tiber River, wherein reliable rating curves are available, have been used for the validation. The outcomes of the analysis can be summarized as follows: (1 the criterion adopted for selecting the "suitable" channel length based on synthetic test studies has proved to be reliable for field applications to three gauged sites. Indeed, for each event a downstream reach length not more than 500 m is found to be sufficient, for a good performances of the hydraulic model, thereby enabling the drastic reduction of river cross-sections data; (2 the procedure for Manning's roughness coefficient calibration allowed for high performance in discharge estimation just considering the observed water levels and occasional measurements of maximum surface flow velocity during the rising limb of flood. Indeed, errors in the peak discharge magnitude, for the optimal calibration, were found not exceeding 5% for all events observed in the three investigated gauged sections, while the

  4. Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

    Science.gov (United States)

    Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

    2009-01-01

    In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global

  5. Model basin, measurement of particle velocities in wave crests

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-15

    A model set-up, which makes it possible to measure water particle velocities in wave crests, has been developed and tested. The technique includes a tri-axial ultrasonic current probe mounted on a movable frame which is moved vertically by a hydraulic piston thus following the oscillating water surface. Recording is hereby done at a constant depth beneath the water surface and the velocity profiles are found by interpolation/extrapolation between the recordings taken in different levels at a given time during the wave time series. The set-up has been successfully used for measurements indeep-water regular and irregular seastates. Detailed analysis and comparison with various theoretical descriptions of wave kinematics has been performed. Furthermore, the set-up has been used for measurements in freak waves reproduced at a limited waterdepth. The analysis and comparisons with theoretical predictions have shed new light on the freak wave phenomenon. Some disturbance into the area of measurements is introduced by the ultrasonic proble. For the maximum values of particle velocities (under a crest or a trough), this disturbance is minimal as the particles move in practically horizontal directons. (BN).

  6. Entanglement-enhanced lidars for simultaneous range and velocity measurements

    Science.gov (United States)

    Zhuang, Quntao; Zhang, Zheshen; Shapiro, Jeffrey H.

    2017-10-01

    Lidar is a well-known optical technology for measuring a target's range and radial velocity. We describe two lidar systems that use entanglement between transmitted signals and retained idlers to obtain significant quantum enhancements in simultaneous measurements of these parameters. The first entanglement-enhanced lidar circumvents the Arthurs-Kelly uncertainty relation for simultaneous measurements of range and radial velocity from the detection of a single photon returned from the target. This performance presumes there is no extraneous (background) light, but is robust to the round-trip loss incurred by the signal photons. The second entanglement-enhanced lidar—which requires a lossless, noiseless environment—realizes Heisenberg-limited accuracies for both its range and radial-velocity measurements, i.e., their root-mean-square estimation errors are both proportional to 1 /M when M signal photons are transmitted. These two lidars derive their entanglement-based enhancements from the use of a unitary transformation that takes a signal-idler photon pair with frequencies ωS and ωI and converts it to a signal-idler photon pair whose frequencies are (ωS+ωI)/2 and (ωS-ωI)/2 . Insight into how this transformation provides its benefits is provided through an analogy to continuous-variable superdense coding.

  7. Editorial special issue on "Laser Doppler vibrometry"

    Science.gov (United States)

    Vanlanduit, Steve; Dirckx, Joris

    2017-12-01

    The invention of the laser in 1960 has opened up many opportunities in the field of measurement science and technology. Just a few years after the invention of the laser, a novel fluid flow measurement technique based on the Doppler effect was introduced: at that moment the laser Doppler anemometer or shortly LDA [1] was born. The technique enabled fluid velocity measurement by using the light of a He-Ne beam which was scattered by very small polystyrene spheres entrained in the fluid. Later on, in the late nineteen seventees it was recognized that the detection of the Doppler frequency shift that occurs when light is scattered by a moving surface can also be used to measure the vibration velocity of an object. The instrument to perform these vibration measurements was called the laser Doppler vibrometer or LDV [2]. In the last decades several technological advances were made in the field of laser Doppler vibrometry. The result is that nowadays, velocity measurements of fluids (using LDA) and vibrating objects (using LDV) are performed in many challenging applications in different fields (microelectronics, civil structures, biomedical engineering, material science, etc.).

  8. High-speed velocity measurements on an EFI-system

    Science.gov (United States)

    Prinse, W. C.; van't Hof, P. G.; Cheng, L. K.; Scholtes, J. H. G.

    2007-01-01

    For the development of an Exploding Foil Initiator for Insensitive Munitions applications the following topics are of interest: the electrical circuit, the exploding foil, the velocity of the flyer, the driver explosive, the secondary flyer and the acceptor explosive. Several parameters of the EFI have influences on the velocity of the flyer. To investigate these parameters a Fabry-Perot Velocity Interferometer System (F-PVIS) has been used. The light to and from the flyer is transported by a multimode fibre terminated with a GRIN-lens. By this method the velocity of very tiny objects (0.1 mm), can be measured. The velocity of flyer can be recorded with nanosecond resolution, depending on the Fabry-Perot etalon and the streak camera. With this equipment the influence of the dimensions of the exploding foil and the flyer on the velocity and the acceleration of the flyer are investigated. Also the integrity of the flyer during flight can be analyzed. To characterize the explosive material, to be used as driver explosive in EFI's, the initiation behaviour of the explosive has been investigated by taking pictures of the explosion with a high speed framing and streak camera. From these pictures the initiation distance and the detonation behaviour of the explosive has been analyzed. Normally, the driver explosive initiates the acceptor explosive (booster) by direct contact. This booster explosive is embedded in the main charge of the munitions. The combination of initiator, booster explosive and main charge explosive is called the detonation train. In this research the possibility of initiation of the booster by an intermediate flyer is investigated. This secondary flyer can be made of different materials, like aluminium, steel and polyester with different sizes. With the aid of the F-PVIS the acceleration of the secondary flyer is investigated. This reveals the influence of the thickness and density of the flyer on the acceleration and final velocity. Under certain

  9. Spacecraft Angular Velocity Estimation Algorithm Based on Orientation Quaternion Measurements

    Directory of Open Access Journals (Sweden)

    M. V. Li

    2016-01-01

    Full Text Available The spacecraft (SC mission involves providing the appropriate orientation and stabilization of the associated axes in space. One of the main sources of information for the attitude control system is the angular rate sensor blocks. One way to improve a reliability of the system is to provide a back up of the control algorithms in case of failure of these blocks. To solve the problem of estimation of SP angular velocity vector in the inertial system of coordinates with a lack of information from the angular rate sensors is supposed the use of orientation data from the star sensors; in this case at each clock of the onboard digital computer. The equations in quaternions are used to describe the kinematics of rotary motion. Their approximate solution is used to estimate the angular velocity vector. Methods of modal control and multi-dimensional decomposition of a control object are used to solve the problem of observation and identification of the angular rates. These methods enabled us to synthesize the SP angular velocity vector estimation algorithm and obtain the equations, which relate the error quaternion with the calculated estimate of the angular velocity. Mathematical modeling was carried out to test the algorithm. Cases of different initial conditions were simulated. Time between orientation quaternion measurements and angular velocity of the model was varied. The algorithm was compared with a more accurate algorithm, built on more complete equations. Graphs of difference in angular velocity estimation depending on the number of iterations are presented. The difference in angular velocity estimation is calculated from results of the synthesized algorithm and the algorithm for more accurate equations. Graphs of error distribution for angular velocity estimation with initial conditions being changed are also presented, and standard deviations of estimation errors are calculated. The synthesized algorithm is inferior in accuracy assessment to

  10. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...

  11. Dual purpose pyrometer for temperature and solidification velocity measurement

    Science.gov (United States)

    Hofmeister, W. H.; Bayuzick, R. J.; Robinson, M. B.

    1990-01-01

    A dual purpose pyrometer is described that allows both accurate radiance temperature measurement and fast temporal response. The system uses two silicon photodiodes with separate optical paths derived from a common spot on the sample. The optical bandwidths and response times of each detection circuit are tailored to the function of each radiometer. The radiance temperature of electromagnetically levitated metallic samples is measured over a narrow optical bandwidth with a high-gain silicon detector. The velocity of solidification of undercooled melts can be deduced from the rise time of the second silicon detector which samples a broad optical bandwidth and has a fast response time. Results from experiments on the undercooling and solidification behavior of electromagnetically levitated pure nickel show that the solidification velocity approaches 17 m/s at high undercooling.

  12. Analytical and experimental comparisons between the frequency-modulated–frequency-shift measurement and the pulsed-wave–time-shift measurement Doppler systems

    DEFF Research Database (Denmark)

    Wilhjelm, Jens Erik; Pedersen, P. C.

    1996-01-01

    In previous publications, a new echo-ranging Doppler system based on transmission of repetitive coherent frequency modulated (FM) sinusoids in two different implementations was presented. One of these implementations, the Frequency Modulated - frequency shift measurement (FM-fsm) Doppler system i...

  13. Water Surface and Velocity Measurement-River and Flume

    Directory of Open Access Journals (Sweden)

    J. H. Chandler

    2014-06-01

    Full Text Available Understanding the flow of water in natural watercourses has become increasingly important as climate change increases the incidence of extreme rainfall events which cause flooding. Vegetation in rivers and streams reduce water conveyance and natural vegetation plays a critical role in flood events which needs to be understood more fully. A funded project at Loughborough University is therefore examining the influence of vegetation upon water flow, requiring measurement of both the 3-D water surface and flow velocities. Experimental work therefore requires the measurement of water surface morphology and velocity (i.e. speed and direction in a controlled laboratory environment using a flume but also needs to be adaptable to work in a real river. Measuring the 3D topographic characteristics and velocity field of a flowing water surface is difficult and the purpose of this paper is to describe recent experimental work to achieve this. After reviewing past work in this area, the use of close range digital photogrammetry for capturing both the 3D water surface and surface velocity is described. The selected approach uses either two or three synchronised digital SLR cameras in combination with PhotoModeler for data processing, a commercial close range photogrammetric package. One critical aspect is the selection and distribution of appropriate floating marker points, which are critical if automated and appropriate measurement methods are to be used. Two distinct targeting approaches are available: either large and distinct specific floating markers or some fine material capable of providing appropriate texture. Initial work described in this paper uses specific marker points, which also provide the potential measuring surface velocity. The paper demonstrates that a high degree of measurement and marking automation is possible in a flume environment, where lighting influences can be highly controlled. When applied to a real river it is apparent that

  14. Velocity Measurement Systems for a Low-speed Wind Tunnel

    Science.gov (United States)

    2015-04-29

    SECURITY CLASSIFICATION OF: Funds were provided by the ARO for the purchase of TSI hot-wire anemometer equipment and a Dantec particle- image...Velocity Measurement Systems for a Low-speed Wind Tunnel Report Title Funds were provided by the ARO for the purchase of TSI hot-wire anemometer equipment...Funds were provided by the Army Research Office for the purchase of TSI hot-wire anemometer equipment and a Dantec particle-image velocimetry system

  15. 3D model assisted fully automated scanning laser Doppler vibrometer measurements

    Science.gov (United States)

    Sels, Seppe; Ribbens, Bart; Bogaerts, Boris; Peeters, Jeroen; Vanlanduit, Steve

    2017-12-01

    In this paper, a new fully automated scanning laser Doppler vibrometer (LDV) measurement technique is presented. In contrast to existing scanning LDV techniques which use a 2D camera for the manual selection of sample points, we use a 3D Time-of-Flight camera in combination with a CAD file of the test object to automatically obtain measurements at pre-defined locations. The proposed procedure allows users to test prototypes in a shorter time because physical measurement locations are determined without user interaction. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. The proposed method is illustrated with vibration measurements of an unmanned aerial vehicle

  16. Model-assisted measurements of suspension-feeding flow velocities.

    Science.gov (United States)

    Du Clos, Kevin T; Jones, Ian T; Carrier, Tyler J; Brady, Damian C; Jumars, Peter A

    2017-06-01

    Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis , measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers ( Re ). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re , pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8 to 520, and exhalant Re ranged from 15 to 1073. Volumetric pumping rates ranged from 1.7 to 7.4 l h -1 for M . arenaria , 0.3 to 3.6 l h -1 for M . m ercenaria and 0.07 to 0.97 l h -1 for C . intestinalis We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies. © 2017. Published by The Company of Biologists Ltd.

  17. Early Reticulocytosis and Anemia Are Associated with Abnormal and Conditional Transcranial Doppler Velocities in Children with Sickle Cell Anemia.

    Science.gov (United States)

    Meier, Emily Riehm; Fasano, Ross M; Estrada, Monica; He, Jianping; Luban, Naomi L C; McCarter, Robert

    2016-02-01

    To improve prediction of sickle cell anemia severity at an early age, we evaluated whether absolute reticulocyte count (ARC) or hemoglobin (Hb) levels during early infancy (2-6 months of age) in patients with sickle cell anemia predict the risk of later developing an abnormal (abTCD) or conditional (cdTCD) Transcranial Doppler (TCD). We used chart review to identify 121 consecutive patients who underwent TCD screening and had steady state ARC and Hb levels recorded between 2 and 6 months of age. Cox regression analysis was used to determine the relationship between ARC, Hb levels, and risk of developing cdTCD/abTCD over time. Mean ARC in early infancy was highest and mean Hb lowest in those children with abTCDs and cdTCDs. Cox regression analysis revealed that those subjects with an ARC ≥200 K/μL in early infancy had nearly 3 times the risk of having an abTCD/cdTCD than the group with an ARC <200 K/μL, and patients with a Hb <8.5 g/dL had 2.7 times the risk of having an abTCD/cdTCD. These data suggest that both elevated ARC and low baseline Hb during early infancy are associated with an increased risk of developing a cdTCD or abTCD later in childhood. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Measuring surface current velocities in the Agulhas region with ASAR

    CSIR Research Space (South Africa)

    Rouault, MJ

    2010-01-01

    Full Text Available Surface current information collected over the Agulhas Current region and derived from the Doppler centroid anomalies of the Advanced Synthetic Aperture Radar (ASAR) are examined. The sources of errors and potential use of the radar surface...

  19. Measurement of blood flow in the carotid arteries using color doppler in healthy Korean adults

    International Nuclear Information System (INIS)

    Moon, Ki Ho; Jeon, Do Ig; Choi, Chang Ho; Ro, Young Jin; Kim, Hak Jin; Lee, Suck Hong; Kim, Byung Soo

    1994-01-01

    To evaluate the blood flow patterns and velocities of the carotid arteries in healthy Korean adults. We evaluated the blood flow patterns and measured the peak systolic and end-diastolic velocities of the common, internal and external carotid arteries in 48 healthy adults who did not have cardiovascular disorders and neck lesions. The velocity difference was analyzed according to different age groups. In addition, peak systolic and end-diastolic velocity ratio of the internal to common carotid artery was estimated, and our data were compared with values reported by other authors. Generally, the velocity in the younger age group tends be to higher than in older group. The peak systolic and end diastolic velocities of the internal carotid artery were 84.5 cm/sec and 30.5 cm/sec. The peak systolic and end diastolic velocity ratio of the internal to common carotid artery were 0.715 and 0.966. The internal carotid artery was less resistant in blood flow than the external carotid artery. Our data were lower than the values which were reported by Bluth et al. The blood flow velocities of the internal carotid artery in healthy adults were lower than those of previous reported foreign values, but the patterns were similar

  20. A new version of the differential decay curve method for Doppler-shift attenuation lifetime measurements

    International Nuclear Information System (INIS)

    Petkov, P.; Yavahchova, M.; Tonev, D.; Goutev, N.; Dewald, A.

    2013-01-01

    A new version of the differential decay curve method is proposed for the analysis of Doppler-shift attenuation lifetime measurements. The lifetime is derived directly from the line shapes of the depopulating and feeding transitions on the basis of the Blaugrund approximation without including any assumptions or fitting of the time dependence of the population of the corresponding levels. For specific simulated cases, the method shows promise for its applicability. In the future, we intend to generalize the method for the case of an arbitrary multi-detector setup

  1. Tunable diode laser absorption sensor for temperature and velocity measurements of O2 in air flows

    Science.gov (United States)

    Philippe, L. C.; Hanson, R. K.

    1991-01-01

    A fast and nonintrusive velocity and temperature diagnostic based on oxygen absorption is presented. The system uses a GaAlAs tunable diode laser, ramped and modulated in wavelength at high frequency. Detection is performed at twice the modulating frequency, leading to second harmonic absorption lineshapes. Velocity is inferred from the wavelength shift of the absorption line center due to the Doppler effect. Temperature is determined by comparing experimental and calculated lineshapes. Capabilities of the technique for studies of transient high-speed flows are demonstrated in shock tube experiments. Good agreement is obtained with predicted temperatures and velocities when pressure-induced shifts are accounted for.

  2. Velocity field measurement in micro-bubble emission boiling

    International Nuclear Information System (INIS)

    Ito, Daisuke; Saito, Yasushi; Natazuka, Jun

    2017-01-01

    Liquid inlet behavior to a heat surface in micro-bubble emission boiling (MEB) was investigated by flow measurement using particle image velocimetry (PIV). Subcooled pool boiling experiments under atmospheric pressure were carried out using a heat surface with a diameter of 10 mm. An upper end of a heater block made of copper was used as the heat surface. Working fluid was the deionized water and the subcooling was varied from 40 K to 70 K. Three K-type thermocouples were installed in the copper block to measure the temperature gradient, and the heat flux and wall superheat were estimated from these temperature data to make a boiling curve. The flow visualization around the heat surface was carried out using a high-speed video camera and a light sheet. The microbubbles generated in the MEB were used as tracer particles and the velocity field was obtained by PIV analysis of the acquired image sequence. As a result, the higher heat fluxes than the critical heat flux could be obtained in the MEB region. In addition, the distribution characteristics of the velocity in MEB region were studied using the PIV results and the location of the stagnation point in the velocity fields was discussed. (author)

  3. On the measurement of lateral velocity derivatives in turbulent flows

    Science.gov (United States)

    Antonia, R. A.; Zhu, Y.; Kim, J.

    1993-01-01

    Direct numerical simulation data for the lateral velocity derivative delta(u)/delta(y) at the centerline of a fully developed turbulent channel flow provide reasonable support for Wyngaard's analysis of the error involved in measuring this quantity using parallel hot wires. Numerical data in the wall region of the channel flow also provide a useful indication of how to select the separation between the wires. Justification for this choice is obtained by comparing several measured statistics of delta(u)/delta(y) with the corresponding numerical data.

  4. Predicted and measured velocity distribution in a model heat exchanger

    International Nuclear Information System (INIS)

    Rhodes, D.B.; Carlucci, L.N.

    1984-01-01

    This paper presents a comparison between numerical predictions, using the porous media concept, and measurements of the two-dimensional isothermal shell-side velocity distributions in a model heat exchanger. Computations and measurements were done with and without tubes present in the model. The effect of tube-to-baffle leakage was also investigated. The comparison was made to validate certain porous media concepts used in a computer code being developed to predict the detailed shell-side flow in a wide range of shell-and-tube heat exchanger geometries

  5. Measurement of Damage Velocities in Bullet Impacts of Transparent Armor

    Science.gov (United States)

    Anderson, Charles; Bigger, Rory; Weiss, Carl

    2013-06-01

    A series of impact experiments have been conducted to examine the response of transparent material to ballistic impact. The experiments consisted of impacting 15 mm of borosilicate glass back by 9.5 mm of Lexan. The projectile was a 0.30-cal hard steel bullet designed specifically for the experiments. Residual velocities and the residual length of the bullets (which were soft-recovered in a catch box) were measured as a function of impact velocity. High-speed imaging of the impact event and post-test analysis has permitted quantification of damage propagation and the rate of propagation. The results of several experiments are presented and compared to edge-on impact experiments that have been conducted by Strassburger et al..

  6. Particle Image Velocimetry (PIV) Measurements of Suspension-Feeding Velocities

    Science.gov (United States)

    Du Clos, K.; Jones, I. T.; Carrier, T. J.; Jumars, P. A.

    2016-02-01

    Active suspension feeders, such as bivalves and tunicates, connect benthic and pelagic ecosystems by packaging suspended matter into larger fecal and pseudofecal particles, greatly enhancing the flux of carbon and nutrients from the water column to the benthos. The volume of water processed by a population of suspension feeders is commonly estimated by scaling up results from experiments that measure the clearance rate (the volume of water cleared of particles per time) of one or a few individual suspension feeders. Clearance rates vary, however, between species, within a species, and over time for a single individual; and the velocity fields produced by suspension feeders are likely to interact in complex ways. We measured the water velocity fields produced by two species of bivalve, Mya arenaria and Mercenaria mercenaria, and the tunicate Ciona intestinalis, using particle image velocimetry (PIV). We used these measurements to calculate flow rates and Reynolds numbers of inhalant and exhalant siphons. We also observed strong entrainment of water by M. arenaria's exhalant siphon jet that may help to explain how the clam avoids depleting the water around it of particles and oxygen as it feeds. We are using these measurements to inform computational fluid mechanics (CFD) models of suspension feeding, allowing us to examine the interactions of flow fields produced by multiple suspension feeders and other effects not quantified by clearance-rate measurements.

  7. Dynamic Characterization of Cohesive Material Based on Wave Velocity Measurements

    Directory of Open Access Journals (Sweden)

    Wojciech Sas

    2016-02-01

    Full Text Available The paper presents a description of the dynamic properties of cohesive material, namely silty clays, obtained by using one of the applied seismology methods, the bender elements technique. The authors’ aim was to present the dynamics of a porous medium, in particular an extremely important passage of seismic waves that travel through the bulk of a medium. Nowadays, the application of the bender element (BE technique to measure, e.g., small strain shear stiffness of soils in the laboratory is well recognized, since it allows for reliable and relatively economical shear wave velocity measurements during various laboratory experiments. However, the accurate estimation of arrival time during BE tests is in many cases unclear. Two different interpretation procedures (from the time domain of BE tests in order to measure travel times of waves were examined. Those values were then used to calculate shear and compression wave velocities and elastic moduli. Results showed that the dynamic parameters obtained by the start-to-start method were always slightly larger (up to about 20% than those obtained using the peak-to-peak one. It was found that the peak-to-peak method led to more scattered results in comparison to the start-to-start method. Moreover, the influence of the excitation frequency, the mean effective stress and the unloading process on the dynamic properties of the tested material was studied. In addition, the obtained results highlighted the importance of initial signal frequency and the necessity to choose an appropriate range of frequencies to measure the shear wave velocity in clayey soils.

  8. Study of Estimation Method for Unsteady Inflow Velocity in Two-Dimensional Ultrasonic-Measurement-Integrated Blood Flow Simulation.

    Science.gov (United States)

    Kadowaki, Hiroko; Hayase, Toshiyuki; Funamoto, Kenichi; Taniguchi, Nobuyuki

    2016-02-01

    Information on hemodynamics is essential for elucidation of mechanisms and development of novel diagnostic methods for circulatory diseases. Two-dimensional ultrasonic-measurement-integrated (2D-UMI) simulation can correctly reproduce an intravascular blood flow field and hemodynamics by feeding back an ultrasonic measurement to the numerical blood flow simulation. In this method, it is critically important to give the correct cross-sectional average inflow velocity (inflow velocity) as the boundary condition. However, systematic study has not been done on the relative validity and effectiveness of existing inflow velocity estimation methods for various target flow fields. The aim of this study was to examine the existing methods systematically and to establish a method to accurately estimate inflow velocities for various vessel geometries and flow conditions in 2D-UMI simulations. A numerical experiment was performed for 2D-UMI simulation of blood flow models in a straight vessel with inflow velocity profiles symmetric and asymmetric to the vessel axis using existing evaluation functions based on Doppler velocity error for the inflow velocity estimation. As a result, it was clarified that a significantly large estimation error occurs in the asymmetric flow due to a nonfeedback domain near the downstream end of the calculation domain. Hence, a new inflow velocity estimation method of 2D-UMI simulation is proposed in which the feedback and evaluation domains are extended to the downstream end. Further numerical experiments of 2D-UMI simulation for two realistic vessel geometries of a healthy blood vessel and a stenosed one confirmed the effectiveness of the proposed method.

  9. A Space-Frequency Data Compression Method for Spatially Dense Laser Doppler Vibrometer Measurements

    Directory of Open Access Journals (Sweden)

    José Roberto de França Arruda

    1996-01-01

    Full Text Available When spatially dense mobility shapes are measured with scanning laser Doppler vibrometers, it is often impractical to use phase-separation modal parameter estimation methods due to the excessive number of highly coupled modes and to the prohibitive computational cost of processing huge amounts of data. To deal with this problem, a data compression method using Chebychev polynomial approximation in the frequency domain and two-dimensional discrete Fourier series approximation in the spatial domain, is proposed in this article. The proposed space-frequency regressive approach was implemented and verified using a numerical simulation of a free-free-free-free suspended rectangular aluminum plate. To make the simulation more realistic, the mobility shapes were synthesized by modal superposition using mode shapes obtained experimentally with a scanning laser Doppler vibrometer. A reduced and smoothed model, which takes advantage of the sinusoidal spatial pattern of structural mobility shapes and the polynomial frequency-domain pattern of the mobility shapes, is obtained. From the reduced model, smoothed curves with any desired frequency and spatial resolution can he produced whenever necessary. The procedure can he used either to generate nonmodal models or to compress the measured data prior to modal parameter extraction.

  10. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been...

  11. In situ calibration of an interferometric velocity sensor for measuring small scale flow structures using a Talbot-pattern

    Science.gov (United States)

    König, Jörg; Czarske, Jürgen

    2017-10-01

    Small scale flow phenomena play an important role across engineering, biological and chemical sciences. To gain deeper understanding of the influence of those flow phenomena involved, measurement techniques with high spatial resolution are often required, presuming a calibration of very low uncertainty. To enable such measurements, a method for the in situ calibration of an interferometric flow velocity profile sensor is presented. This sensor, with demonstrated spatial resolution better than 1 μm, allows for spatially-resolving measurements with low velocity uncertainty in flows with high velocity gradients, on condition that the spatial behavior of the interference fringe systems is well-known by calibration with low uncertainty, especially challenging to obtain at applications with geometries difficult to access. The calibration method described herein uses three interfering beams to form the interference fringe systems of the sensor, yielding Doppler burst signals exhibiting two peaks in the frequency domain whose amplitude ratio varies periodically along the measurement volume major z-axis, giving a further independent value of the axial tracer particle position that can be used to determine the calibration functions of the sensor during the flow measurement. A flow measurement in a microchannel experimentally validates that the presented approach allows for simultaneously estimating the calibration functions and the velocity profile, providing flow measurements with very low systematic measurement errors of the particle position of less than 400 nm (confidence interval 95%). In that way, the interferometric flow velocity profile sensor utilizing the in situ self-calibration method promises valuable insights on small scale flow phenomena, such as those given in shear and boundary layer flows, by featuring reliable flow measurements due to minimum systematic and statistical measurement errors.

  12. Use of an Acoustic Doppler Current Profiler (ADCP) to Measure Hypersaline Bidirectional Discharge

    Science.gov (United States)

    Johnson, K.K.; Loving, B.L.; ,

    2002-01-01

    The U.S. Geological Survey measures the exchange of flow between the north and south parts of Great Salt Lake, Utah, as part of a monitoring program. Turbidity and bidirectional flow through the breach in the causeway that divides the lake into two parts makes it difficult to measure discharge with conventional streamflow techniques. An acoustic Doppler current profiler (ADCP) can be used to more accurately define the angles of flow and the location of the interface between the layers of flow. Because of the high salinity levels measured in Great Salt Lake (60-280 parts per thousand), special methods had to be developed to adjust ADCP-computed discharges for the increased speed of sound in hypersaline waters and for water entrained at the interface between flow layers.

  13. Improved measurements of mean sea surface velocity in the Nordic Seas from synthetic aperture radar

    Science.gov (United States)

    Wergeland Hansen, Morten; Johnsen, Harald; Engen, Geir; Øie Nilsen, Jan Even

    2017-04-01

    The warm and saline surface Atlantic Water (AW) flowing into the Nordic Seas across the Greenland-Scotland ridge transports heat into the Arctic, maintaining the ice-free oceans and regulating sea-ice extent. The AW influences the region's relatively mild climate and is the northern branch of the global thermohaline overturning circulation. Heat loss in the Norwegian Sea is key for both heat transport and deep water formation. In general, the ocean currents in the Nordic Seas and the North Atlantic Ocean is a complex system of topographically steered barotropic and baroclinic currents of which the wind stress and its variability is a driver of major importance. The synthetic aperture radar (SAR) Doppler centroid shift has been demonstrated to contain geophysical information about sea surface wind, waves and current at an accuracy of 5 Hz and pixel spacing of 3.5 - 9 × 8 km2. This corresponds to a horizontal surface velocity of about 20 cm/s at 35° incidence angle. The ESA Prodex ISAR project aims to implement new and improved SAR Doppler shift processing routines to enable reprocessing of the wide swath acquisitions available from the Envisat ASAR archive (2002-2012) at higher resolution and better accuracy than previously obtained, allowing combined use with Sentinel-1 and Radarsat-2 retrievals to build timeseries of the sea surface velocity in the Nordic Seas. Estimation of the geophysical Doppler shift from new SAR Doppler centroid shift retrievals will be demonstrated, addressing key issues relating to geometric (satellite orbit and attitude) and electronic (antenna mis-pointing) contributions and corrections. Geophysical Doppler shift retrievals from one month of data in January 2010 and the inverted surface velocity in the Nordic Seas are then addressed and compared to other direct and indirect estimates of the upper ocean current, in particular those obtained in the ESA GlobCurrent project.

  14. Ultrasonic Doppler color in glaucoma: Concordance study

    International Nuclear Information System (INIS)

    Uriza, Felipe; Useche, Nicolas

    2005-01-01

    Our study demonstrates that US color Doppler is a non invasive, reliable and reproducible method for the evaluation of the orbitary flow in normal and glaucomatous patients. However is suggested that every group evaluates the inter and intraobserver variability because of the lack of universal reference velocity measurements

  15. Laser-Doppler velocimetry measurements in a motored IC engine simulator

    Science.gov (United States)

    Gany, A.; Sirignano, W. A.; Larrea, J.-J.

    1980-01-01

    A measurement technique and experimental results are presented for mean velocity and velocity fluctuations in a motored, axisymmetric engine chamber simulation. Three valve configurations are considered: open orifice, open valve, and operating valve. Measurements of axial and tangential velocity components have been taken at various axial and radial positions for one compression ratio (7:1) and one rpm level (31). The measurements show that the intake stroke (in both two and four stroke operations) result in a recirculating flow with substantial turbulence generation even at the low rpm value. The four-stroke results in an axisymmetric design are novel and especially significant since the ability exists to make comparisons with theoretical, axisymmetric, turbulent results.

  16. Pre-precipitation studies in an Al-Zn alloy by positron Doppler broadening measurements

    International Nuclear Information System (INIS)

    Panchanadeeswaran, S.; Plichta, M.R.; Byrne, J.G.

    1984-01-01

    Positron annihilation studies using measurements of Doppler broadening of annihilation γ-rays have been carried out in an Al-8.5 wt% Zn alloy. More than 90% of positron trapping is believed to occur at GP zones formed on quenching the supersaturated solid solution. The dissolution of GP zones above 373 K was revealed by drastic narrowing of the Doppler energy spectrum for samples aged above 373 K. The kinetics of formation of GP zones at ambient temperatures is drastically reduced when the alloy containing GP zones formed during quenching from supersaturated solid solution was reverted at 403 K and reaged at ambient temperature. It was also observed that, even after long reageing, the total number of GP zones formed is much lower than in a directly quenched alloy. The kinetics of formation of GP zones are also reduced by quenching from a single phase to an intermediate temperature where GP zones are not stable, followed by ageing at ambient temperature. Transmission electron micrographs revealed the presence of dislocation loops in alloys quenched from temperature above 773 K. The sensitivity of positrons to the presence of dislocation loops was analysed using the R parameter analysis. (author)

  17. Measuring Tsunami Current Velocities on California’s North Coast

    Science.gov (United States)

    Crawford, G. B.; Dengler, L. A.; Montoya, J.

    2009-12-01

    The Northern California coast is particularly susceptible to tsunami damage. Thirty-one tsunamis have been recorded since 1933 when the first tide gauge was installed at Citizen’s Dock in Crescent City, California and four have caused damage. In November 2006, a magnitude 8.3 earthquake in the Kuril Islands generated a tsunami that caused over $20 million in damages and replacement costs to the Crescent City small boat basin. The 2006 tsunami did not flood any areas above the normal high tide; very strong currents produced as the tsunami surged in and out of the small boat basin caused all of the damage. The Harbor Master and commercial fishermen in the area estimated the peak currents near the mouth of the small boat basin at 12 to 15 knots or 6 to 8 m/sec. MOST numerical modeling of the 2006 currents in Crescent City gives peak velocities in the 2-3 m/sec range. We have initiated a pilot project to directly measure current velocities produced by moderate tsunamis such as the 2006 event. In spring of 2009 we acquired a Nortek Aquadopp 600 kHz acoustic 2-D current profiler through a donation from the Pacific Gas and Electric Company to measure currents in Humboldt Bay, located 100 km south of Crescent City. The manufacturer specifies the current meter can measure currents up to 10 m/sec. In a preliminary deployment at the Fairhaven dock inside Humboldt Bay in May 2009, we measured current velocities of 1.5 m/sec caused by the daily tidal fluctuation with a 1 minute sampling rate. Our primary goal is to model control and data telemetry of this current meter after NOAA’s tsunami-ready tide gages, in collaboration with NOAA personnel at PMEL and CO-OPS. We also intend to make available real-time current measurements online for the local maritime community. In this poster, we present preliminary results from the current meter and discuss deployment and telecommunication considerations. While some interference is present in the closest range bins, the system

  18. Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

    Science.gov (United States)

    Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul; hide

    2010-01-01

    This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 aircraft in autonomous operation. Recently, LaRC 2-micron coherent Doppler wind lidar system was selected to contribute to the NASA Science Mission Directorate (SMD) Earth Science Division (ESD) hurricane field experiment in 2010 titled Genesis and Rapid Intensification Processes (GRIP). The Doppler lidar system will measure vertical profiles of horizontal vector winds from the DC-8 aircraft using NASA Langley s existing 2-micron, pulsed, coherent detection, Doppler wind lidar system that is ready for DC-8 integration. The measurements will typically extend from the DC-8 to the earth s surface. They will be highly accurate in both wind magnitude and direction. Displays of the data will be provided in real time on the DC-8. The pulsed Doppler wind lidar of NASA Langley Research Center is much more powerful than past Doppler lidars. The operating range, accuracy, range resolution, and time resolution will be unprecedented. We expect the data to play a key role, combined with the other sensors, in improving understanding and predictive algorithms for hurricane strength and track. 1

  19. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    Science.gov (United States)

    Mach, J. J.; Varghese, P. L.; Jagodzinski, J. J.

    1999-01-01

    The ability of solid-state lasers to be tuned in operating frequency at MHz rates by input current modulation, while maintaining a relatively narrow line-width, has made them useful for spectroscopic measurements. Their other advantages include low cost, reliability, durability, compact size, and modest power requirements, making them a good choice for a laser source in micro-gravity experiments in drop-towers and in flight. For their size, they are also very bright. In a filtered Rayleigh scattering (FRS) experiment, a diode laser can be used to scan across an atomic or molecular absorption line, generating large changes in transmission at the resonances for very small changes in frequency. The hyperfine structure components of atomic lines of alkali metal vapors are closely spaced and very strong, which makes such atomic filters excellent candidates for sensitive Doppler shift detection and therefore for high-resolution velocimetry. In the work we describe here we use a Rubidium vapor filter, and work with the strong D(sub 2) transitions at 780 nm that are conveniently accessed by near infrared diode lasers. The low power output of infrared laser diodes is their primary drawback relative to other laser systems commonly used for velocimetry. However, the capability to modulate the laser frequency rapidly and continuously helps mitigate this. Using modulation spectroscopy and a heterodyne detection scheme with a lock-in amplifier, one can extract sub-microvolt signals occurring at a specific frequency from a background that is orders of magnitude stronger. The diode laser modulation is simply achieved by adding a small current modulation to the laser bias current. It may also be swept repetitively in wavelength using an additional lower frequency current ramp.

  20. Volumetric velocity measurements on flows through heart valves

    Science.gov (United States)

    Troolin, Daniel; Amatya, Devesh; Longmire, Ellen

    2009-11-01

    Volumetric velocity fields inside two types of artificial heart valves were obtained experimentally through the use of volumetric 3-component velocimetry (V3V). Index matching was used to mitigate the effects of optical distortions due to interfaces between the fluid and curved walls. The steady flow downstream of a mechanical valve was measured and the results matched well with previously obtained 2D PIV results, such as those of Shipkowitz et al. (2002). Measurements upstream and downstream of a deformable silicone valve in a pulsatile flow were obtained and reveal significant three-dimensional features of the flow. Plots and movies will be shown, and a detailed discussion of the flow and various experimental considerations will be included. Reference: Shipkowitz, T, Ambrus J, Kurk J, Wickramasinghe K (2002) Evaluation technique for bileaflet mechanical valves. J. Heart Valve Disease. 11(2) pp. 275-282.

  1. Development of tunable high pressure CO2 laser for lidar measurements of pollutants and wind velocities

    Science.gov (United States)

    Levine, J. S.; Guerra, M.; Javan, A.

    1980-01-01

    The problem of laser energy extraction at a tunable monochromatic frequency from an energetic high pressure CO2 pulsed laser plasma, for application to remote sensing of atmospheric pollutants by Differential Absorption Lidar (DIAL) and of wind velocities by Doppler Lidar, was investigated. The energy extraction principle analyzed is based on transient injection locking (TIL) at a tunable frequency. Several critical experiments for high gain power amplification by TIL are presented.

  2. Reliability of laser Doppler, near-infrared spectroscopy and Doppler ultrasound for peripheral blood flow measurements during and after exercise in the heat.

    Science.gov (United States)

    Choo, Hui C; Nosaka, Kazunori; Peiffer, Jeremiah J; Ihsan, Mohammed; Yeo, Chow C; Abbiss, Chris R

    2017-09-01

    This study examined the test-retest reliability of near-infrared spectroscopy (NIRS), laser Doppler flowmetry (LDF) and Doppler ultrasound to assess exercise-induced haemodynamics. Nine men completed two identical trials consisting of 25-min submaximal cycling at first ventilatory threshold followed by repeated 30-s bouts of high-intensity (90% of peak power) cycling in 32.8 ± 0.4°C and 32 ± 5% relative humidity (RH). NIRS (tissue oxygenation index [TOI] and total haemoglobin [tHb]) and LDF (perfusion units [PU]) signals were monitored continuously during exercise, and leg blood flow was assessed by Doppler ultrasound at baseline and after exercise. Cutaneous vascular conductance (CVC; PU/mean arterial pressure (MAP)) was expressed as the percentage change from baseline (%CVC BL ). Coefficients of variation (CVs) as indicators of absolute reliability were 18.7-28.4%, 20.2-33.1%, 42.5-59.8%, 7.8-12.4% and 22.2-30.3% for PU, CVC, %CVC BL , TOI and tHb, respectively. CVs for these variables improved as exercise continued beyond 10 min. CVs for baseline and post-exercise leg blood flow were 17.8% and 10.5%, respectively. CVs for PU, tHb (r 2  = 0.062) and TOI (r 2  = 0.002) were not correlated (P > 0.05). Most variables demonstrated CVs lower than the expected changes (35%) induced by training or heat stress; however, minimum of 10 min exercise is recommended for more reliable measurements.

  3. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurments of diffuse light

    NARCIS (Netherlands)

    Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton; Steenbergen, Wiendelt

    2007-01-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a

  4. Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light

    NARCIS (Netherlands)

    Varghese, Babu; Rajan, Vinayakrishnan; van Leeuwen, Ton G.; Steenbergen, Wiendelt

    2007-01-01

    The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a

  5. INCREASING MEASUREMENT ACCURACY IN ELECTRO-OPTICAL METHOD FOR MEASURING VELOCITY OF DETONATION

    Directory of Open Access Journals (Sweden)

    Mario Dobrilović

    2014-12-01

    Full Text Available In addition to other detonation parameters detonation velocity is a value that provides indirect information on the strength i.e. brisance of an explosive and explosive performance. In addition to that, detonation velocity is a value which can be measured in a relatively simpler and more precise manner, by developed and accessible methods when compared to other detonation parameters Due to its simple use, compact instruments and satisfactory accuracy, electro-optical method of detonation velocity measurement is widely used. The paper describes the electro-optical measurement method and points out the factors that affect its accuracy. The accuracy of measurement is increased and measurement uncertainty is reduced by the measurement result analysis with the application of different measurement setups.

  6. Wind Profiling from a New Compact, Pulsed, 2-Micron, Coherent-Detection Doppler Lidar Transceiver during Wind Measurement Intercomparison

    Science.gov (United States)

    Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Yu, Jirong; Beyon, Jeffrey Y.; Demoz, B.; Veneable, D.

    2009-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. This lidar system was recently deployed at Howard University facility in Beltsville, Maryland, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other lidars and other sensors will be presented.

  7. Ion Velocity Measurements for the Ionospheric Connections Explorer

    Science.gov (United States)

    Heelis, R. A.; Stoneback, R. A.; Perdue, M. D.; Depew, M. D.; Morgan, W. A.; Mankey, M. W.; Lippincott, C. R.; Harmon, L. L.; Holt, B. J.

    2017-10-01

    The Ionospheric Connections Explorer (ICON) payload includes an Ion Velocity Meter (IVM) to provide measurements of the ion drift motions, density, temperature and major ion composition at the satellite altitude near 575 km. The primary measurement goal for the IVM is to provide the meridional ion drift perpendicular to the magnetic field with an accuracy of 7.5 m s-1 for all daytime conditions encountered by the spacecraft within 15° of the magnetic equator. The IVM will derive this parameter utilizing two sensors, a retarding potential analyzer (RPA) and an ion drift meter (IDM) that have a robust and successful flight heritage. The IVM described here incorporates improvements in the design and operation to produce the most sensitive device that has been fielded to date. It will specify the ion drift vector, from which the component perpendicular to the magnetic field will be derived. In addition it will specify the total ion density, the ion temperature and the fractional ion composition. These data will be used in conjunction with measurements from the other ICON instruments to uncover the important connections between the dynamics of the neutral atmosphere and the ionosphere through the generation of dynamo currents perpendicular to the magnetic field and collisional forces parallel to the magnetic field. Here the configuration and operation of the IVM instrument are described, as well as the procedures by which the ion drift velocity is determined. A description of the subsystem characteristics, which allow a determination of the expected uncertainties in the derived parameters, is also given.

  8. Visible Spectrometer at the Compact Toroid Injection Experiment, the Sustained Spheromak Plasma Experiment and the Alcator C-Mod Tokamak for Doppler Width and Shift Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Graf, A; Howard, S; Horton, R; Hwang, D; May, M; Beiersdorfer, P; McLean, H; Terry, J

    2006-05-15

    A novel Doppler spectrometer is currently being used for ion or neutral velocity and temperature measurements on the Alcator C-Mod Tokamak. The spectrometer has an f/No. of {approx}3.1 and is appropriate for visible light (3500-6700 {angstrom}). The full width at half maximum from a line emitting calibration source has been measured to be as small as 0.4 {angstrom}. The ultimate time resolution is line brightness light limited and on the order of ms. A new photon efficient detector is being used for the setup at C-Mod. Time resolution is achieved by moving the camera during a plasma discharge in a perpendicular direction through the dispersion plane of the spectrometer causing a vertical streaking across the camera face. Initial results from C-Mod as well as previous measurements from the Compact Toroid Injection Experiment (CTIX) and the Sustained Spheromak Plasma Experiment (SSPX) are presented.

  9. Drop weight impact strength measurement method for porous concrete using laser doppler velocimetry

    NARCIS (Netherlands)

    Agar-Ozbek, A.S.; Weerheijm, J.; Schlangen, E.; Breugel, K. van

    2012-01-01

    In this study, an experimental configuration that reveals the dynamic response of porous concretes in a drop weight impact test was introduced. Through the measurement of particle velocity at the interface, between the impactor and the concrete target, the dynamic response was obtained in an easily

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

    Science.gov (United States)

    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.

  11. [Effect of decreased ocular perfusion pressure on iris blood flow measured by laser Doppler flowmetry].

    Science.gov (United States)

    Chamot, S R; Movaffaghy, A; Petrig, B L; Riva, C E

    1999-05-01

    To determine whether iris blood flow (IBF) is regulated in response to an acute decrease in mean ocular perfusion pressure (PPm = MOAP-IOP, MOAP = mean ophthalmic arterial pressure) induced by increasing the intraocular pressure (IOP). Iris blood flow was measured using a slit lamp incorporating a laser Doppler flowmetry (LDF) module. The study was conducted on 12 normal volunteers (14 to 59 years old). IOP was raised using a scleral suction cup. In Exp. #1, the suction pressure was successively raised in steps of 50 to 100 mm Hg, each lasting about 10 sec, until IOP reached the MOAP level. In Exp. #2, the suction was raised to 200 mm Hg in 4 successive steps of 2 min duration. In Exp. #1, no significant change of IBF was observed for small decreases of PPm ( 23%).

  12. Measurements of ultrasonic waves by means of laser Doppler velocimeter and an experimental study of elastic wave propagation in inhomogeneous media; Laser doppler sokudokei ni yoru choonpa keisoku to ganseki wo mochiita fukinshitsu baishitsu no hado denpa model jikken

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, O.; Sato, T. [Geological Survey of Japan, Tsukuba (Japan); Lei, X. [Dia Consultants Company, Tokyo (Japan)

    1996-05-01

    In the study of seismic wave propagation, a model experimenting technique has been developed using a laser Doppler velocimeter (LDV) as the sensor. This technique, not dependent on conventional piezoelectric devices, only irradiates the specimen with laser to measure the velocity amplitude on the target surface, eliminating the need for close contact between the specimen and sensor. In the experiment, elastic penetration waves with their noise levels approximately 0.05mm/s were observed upon application of vibration of 10{sup 6}-10{sup 5}Hz. The specimen was stainless steel or rock, and waveforms caught by the LDV and piezoelectric device were compared. As the result, it was found that the LDV is a powerful tool for effectively explaining elastic wave propagation in inhomogeneous media. The piezoelectric device fails to reproduce accurately the waves to follow the initial one while the LDV detect the velocity amplitude on the specimen surface in a wide frequency range encouraging the discussion over the quantification of observed waveforms. 10 refs., 7 figs.

  13. Research on the improvement of nuclear safety - Development of a technique for simultaneous measurement of particle size and velocity for direct containment heating accident analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Yong; Song, Si Hong; Koh, Kwang Woong; Kim, Joo Yeon; Kim, Jong Moon; Choi, Chul Jin [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1995-08-01

    The main objective is to develop a high performance software routine to process the output signals from the phase/Doppler device for simultaneous measurement of drop sizes and two-dimensional velocities of spray drops/particles. The present work has been carried out as an extension work of the first year`s research, where the principles and the limitation of this measuring technique have been thoroughly reviewed. In order to verify the performance and reliability of this software for simultaneous measurement of sizes and velocities of spray drops with two-dimensional motions, the results were compared with those from commercial signal processor DSA by Aerometrics, and concluded to be satisfactory. The routine developed throughout this project is applicable not only to the DCH model experiments but also to the measurements of sizes and velocities of drops/particles in combustors, dryers, humidifiers, and in various two-phase equipments. 20 refs., 5 tabs., 21 figs. (author)

  14. Determination of groundwater flow velocity by radon measurements

    International Nuclear Information System (INIS)

    Hohn, E.; von Gunten, H.R.

    1990-01-01

    The groundwater resources of glacio-fluvial perialpine valleys are recharged significantly by the infiltration from rivers. The groundwater residence times between rivers and wells should be known in groundwater management problems. Short residence times can be estimated using radon. Radon concentrations in rivers are usually very low. Upon filtration and movement of the water in the ground, radon is picked up and its concentration increases by 2-3 orders of magnitude according to radioactive growth laws. Residence times and flow velocities can be estimated from the increasing radon concentrations measured in groundwater sampling tubes at different distances from the river. Results obtained with this method agree with the results from experiments with artificial tracers

  15. Measuring the Edge Recombination Velocity of Monolayer Semiconductors.

    Science.gov (United States)

    Zhao, Peida; Amani, Matin; Lien, Der-Hsien; Ahn, Geun Ho; Kiriya, Daisuke; Mastandrea, James P; Ager, Joel W; Yablonovitch, Eli; Chrzan, Daryl C; Javey, Ali

    2017-09-13

    Understanding edge effects and quantifying their impact on the carrier properties of two-dimensional (2D) semiconductors is an essential step toward utilizing this material for high performance electronic and optoelectronic devices. WS 2 monolayers patterned into disks of varying diameters are used to experimentally explore the influence of edges on the material's optical properties. Carrier lifetime measurements show a decrease in the effective lifetime, τ effective , as a function of decreasing diameter, suggesting that the edges are active sites for carrier recombination. Accordingly, we introduce a metric called edge recombination velocity (ERV) to characterize the impact of 2D material edges on nonradiative carrier recombination. The unpassivated WS 2 monolayer disks yield an ERV ∼ 4 × 10 4 cm/s. This work quantifies the nonradiative recombination edge effects in monolayer semiconductors, while simultaneously establishing a practical characterization approach that can be used to experimentally explore edge passivation methods for 2D materials.

  16. In Vivo Validation of a Blood Vector Velocity Estimator with MR Angiography

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

    2009-01-01

    Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound beam direction. This implies that a Doppler angle under examination close to 90° results in unreliable information about the true blood direction and blood velocity. The novel method...... transverse oscillation (TO), which combines estimates of the axial and the transverse velocity components in the scan plane, makes it possible to estimate the vector velocity of the blood regardless of the Doppler angle. The present study evaluates the TO method with magnetic resonance phase contrast......° for TO measurements. The correlation between the stroke volume estimated by TO and MRA was 0.91 (p

  17. Application of a Novel Laser-Doppler Velocimeter for Turbulence: Structural Measurements in Turbulent Boundary Layers

    Science.gov (United States)

    2006-10-18

    multiple-wire configurations to achieve velocity gradient measurements ( Balint et al. 1991, Wallace and Foss 1995, Honkan and Andreopoulos 1997, Wang and...repeated with elaborate hot-wire arrangements by Balint et al. (1991) and Honkan and Andreopoulos (1997) among others. These studies measured all-nine...documented a number of times (Sandbom and Braun 1956; Balint et al. 1991). Surprisingly, the lower-Reynolds number case follows the spectral value for the

  18. Velocity flow field and water level measurements in shoaling and breaking water waves

    CSIR Research Space (South Africa)

    Mukaro, R

    2010-01-01

    Full Text Available levels were measured using capacitive waves gauges, while the instantaneous velocity flow fields were measured using video techniques together with digital correlation techniques. The instantaneous velocity flow fields were further analyzed to yield...

  19. High temperature doppler effect experiment for 238U at FCA. 1. Reactivity worth measurement with a small heated sample up to 1,500degC

    International Nuclear Information System (INIS)

    Okajima, Shigeaki; Oigawa, Hiroyuki; Mukaiyama, Takehiko; Andoh, Masaki

    1996-01-01

    The experimental device for Doppler effect measurement was developed for the Fast Critical Assembly of Japan Atomic Energy Research Institute. The Doppler effect up to 1,500degC can be measured with this device. The experimental data is to be used for evaluating and improving the calculation method of the Doppler effect in higher temperature range. The measurement technique is based on a reactivity worth measurement with a heated sample. The device is made of tungsten for the high temperature parts and stainless steel for the other structural parts. The measurements were carried out in a mock-up core of an oxide-fueled fast reactor. In the analysis of the experimental data, the Doppler reactivity worth was calculated by a first order perturbation theory and JENDL-3.2 library. A collision probability cell code with ultra-fine group structure, PEACO-X, was used to obtain the precise effective cross sections in a pin cell model of the Doppler sample. The calculation underestimates Doppler effect by about 5% in high temperature range. The Doppler effect above 1,500degC was estimated by the extrapolation of the measured data below this temperature. When the calculated and extrapolated Doppler reactivity worths at 2,000degC were compared, a good agreement between them was obtained. The significant improvement of calculation reliability of the Doppler effect in the higher temperature range was achieved by this experiment. (author)

  20. Velocity Mapping Toolbox (VMT): a processing and visualization suite for moving-vessel ADCP measurements

    Science.gov (United States)

    Parsons, D.R.; Jackson, P.R.; Czuba, J.A.; Engel, F.L.; Rhoads, B.L.; Oberg, K.A.; Best, J.L.; Mueller, D.S.; Johnson, K.K.; Riley, J.D.

    2013-01-01

    The use of acoustic Doppler current profilers (ADCP) for discharge measurements and three-dimensional flow mapping has increased rapidly in recent years and has been primarily driven by advances in acoustic technology and signal processing. Recent research has developed a variety of methods for processing data obtained from a range of ADCP deployments and this paper builds on this progress by describing new software for processing and visualizing ADCP data collected along transects in rivers or other bodies of water. The new utility, the Velocity Mapping Toolbox (VMT), allows rapid processing (vector rotation, projection, averaging and smoothing), visualization (planform and cross-section vector and contouring), and analysis of a range of ADCP-derived datasets. The paper documents the data processing routines in the toolbox and presents a set of diverse examples that demonstrate its capabilities. The toolbox is applicable to the analysis of ADCP data collected in a wide range of aquatic environments and is made available as open-source code along with this publication.

  1. Phonon characteristics of high Tc superconductors from neutron Doppler broadening measurements

    International Nuclear Information System (INIS)

    Trela, W.J.; Kwei, G.H.; Lynn, J.E.; Meggers, K.

    1994-01-01

    Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La 2-x Ba x CuO 4 . Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra

  2. Repeatability and reproducibility of characteristic features measured by laser Doppler vibrometry for on-line diagnostics

    Science.gov (United States)

    Agostinelli, G.; Paone, N.

    2008-06-01

    It is analyzed the statistical dispersion of characteristic features measured by Laser Doppler Vibrometry (LDV) in on-line diagnostic applications, with reference to on-line detection of mechanical defects of washing machines. The paper presents two complementary approaches: a) experimental evaluation of repeatability of measured features according to the Guide to the Expression of Uncertainty in Measurement-GUM; b) Montecarlo simulation of uncertainty propagation across the on-line test station. Experiments consist in a test bench which simulates the vibration of a washing machine, by playing back on a shaker a real signal acquired on-line and taking repeated measurements, so that a statistical analysis is performed about dispersion of diagnostic features. The analysis is repeated by varying the scattering characteristics of the vibrating surface, so to evaluate the effect of signal quality. The Montecarlo approach consists in modeling the propagation of uncertainty across the various elements of the measurement chain, up to the computation of features. The influence of LDV, Data Acquisition device (DAQ) and processing software have been taken into account. Results allow to estimate Repeatability and Reproducibility (R&R) of a typical set of characteristic features used in industrial diagnostics and to discuss uncertainty of similar diagnostic procedures.

  3. Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)

    1994-12-01

    Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

  4. Relationship between hemodynamic changes of portal vein and hepatic artery measured by color Doppler ultrasound and FibroScan value in patients with liver cirrhosis

    Directory of Open Access Journals (Sweden)

    CHENG Xiaofei

    2014-11-01

    Full Text Available ObjectiveTo explore the relationship between hemodynamic changes of the portal vein and hepatic artery measured by color Doppler ultrasound and FibroScan value in patients with liver cirrhosis. MethodsA total of 192 patients with hepatitis B cirrhosis who were admitted to our hospital from March 2010 to December 2013, as well as 100 healthy persons, were recruited. The mean portal vein blood flow velocity (PVVmean, hepatic artery pulsatility index (HAPI, and hepatic artery resistance index (HARI were measured by color Doppler ultrasound. FibroScan was also carried out. All data were statistically analyzed using SPSS 13.0. Continuous data were expressed as mean±SD and compared between groups by t-test. ResultsThe HAPI, HARI, and FibroScan value of the patient group were 1.56±024, 0.73±0.05, and 25.38±7.73, respectively, significantly higher than those of the control group (1.36±0.14, 0.65±0.07, and 7.8±3.6 (P<0.05; the PVVmean of the patient group was 14.43±1.86, significantly lower than that of the control group (17.35±0.56 (P<0.05. FibroScan value was positively correlated with HAPI and HARI (r1=0.59, r2=0.66, P<0.001, but negatively correlated with PVVmean (r=-0.64, P<0.001. ConclusionThe liver stiffness assessed by FibroScan and the hemodynamic changes of the portal vein and hepatic artery measured by color Doppler ultrasound are vitally important for evaluating the severity of liver cirrhosis.

  5. Validation of streamflow measurements made with M9 and RiverRay acoustic Doppler current profilers

    Science.gov (United States)

    Boldt, Justin A.; Oberg, Kevin A.

    2015-01-01

    The U.S. Geological Survey (USGS) Office of Surface Water (OSW) previously validated the use of Teledyne RD Instruments (TRDI) Rio Grande (in 2007), StreamPro (in 2006), and Broadband (in 1996) acoustic Doppler current profilers (ADCPs) for streamflow (discharge) measurements made by the USGS. Two new ADCPs, the SonTek M9 and the TRDI RiverRay, were first used in the USGS Water Mission Area programs in 2009. Since 2009, the OSW and USGS Water Science Centers (WSCs) have been conducting field measurements as part of their stream-gaging program using these ADCPs. The purpose of this paper is to document the results of USGS OSW analyses for validation of M9 and RiverRay ADCP streamflow measurements. The OSW required each participating WSC to make comparison measurements over the range of operating conditions in which the instruments were used until sufficient measurements were available. The performance of these ADCPs was evaluated for validation and to identify any present and potential problems. Statistical analyses of streamflow measurements indicate that measurements made with the SonTek M9 ADCP using firmware 2.00–3.00 or the TRDI RiverRay ADCP using firmware 44.12–44.15 are unbiased, and therefore, can continue to be used to make streamflow measurements in the USGS stream-gaging program. However, for the M9 ADCP, there are some important issues to be considered in making future measurements. Possible future work may include additional validation of streamflow measurements made with these instruments from other locations in the United States and measurement validation using updated firmware and software.

  6. All semiconductor laser Doppler anemometer at 1.55 μm

    DEFF Research Database (Denmark)

    Hansen, Rene Skov; Pedersen, Christian

    2008-01-01

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300...

  7. Comparison of Global Sizing Velocimetry and Phase Doppler Anemometry measurements of alternative jet fuel sprays

    Science.gov (United States)

    Sadr, Reza; Kannaiyan, Kumaran

    2013-11-01

    Atomization plays a crucial precursor role in liquid fuel combustion that directly affects the evaporation, mixing, and emission levels. Laser diagnostic techniques are often used to study the spray characteristics of liquid fuels. The objective of this work is to compare the spray measurements of Gas-to Liquid (GTL) jet fuels obtained using Global Sizing Velocimetry (GSV) and Phase Doppler Anemometry (PDA) techniques at global and local levels, respectively. The chemical and physical properties of GTL fuels are different from conventional jet fuels, owing to the difference in their production methodology. In this work, the experimental facility, the measurement techniques, and spray characteristics of two different GTL fuels are discussed and compared with those of Jet A-1 fuel. Results clearly demonstrate that although the global measurement gives an overall picture of the spray, fine details are obtained only through local measurements and complement in gaining more inferences into the spray characteristics. The results also show a close similarity in spray characteristics between GTL and Jet A-1 fuels. Funded by Qatar Science and Technology Park.

  8. Evaluation of a new high power, wide separation laser Doppler probe : Potential measurement of deeper tissue blood flow

    NARCIS (Netherlands)

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    Objective: To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper

  9. Rapid tuning CW laser technique for measurements of gas velocity, temperature, pressure, density, and mass flux using NO

    Science.gov (United States)

    Chang, Albert Y.; Dirosa, Michael D.; Davidson, David F.; Hanson, Ronald K.

    1991-01-01

    An intracavity-doubled rapid-tuning CW ring dye laser was used to acquire fully resolved absorption profiles of NO line pairs in the A-X band at 225 nm at a rate of 4 kHz. These profiles were utilized for simultaneous measurements of flow parameters in the high-speed 1D flows generated in a shock tube. Velocity was determined from the Doppler shift, measured using a pair of profiles simultaneously acquired at different angles with respect to the flow direction. Temperature was determined from the intensity ratio of the adjacent lines. Pressure and density were found both from the collisional broadening and the fractional absorption. From this information the mass flux was determined. The results compare well to 1D shock calculations.

  10. Ivabradine and Bisoprolol on Doppler-derived Coronary Flow Velocity Reserve in Patients with Stable Coronary Artery Disease: Beyond the Heart Rate.

    Science.gov (United States)

    Tagliamonte, Ercole; Cirillo, Teresa; Rigo, Fausto; Astarita, Costantino; Coppola, Antonino; Romano, Carlo; Capuano, Nicola

    2015-08-01

    Coronary flow velocity reserve (CFVR) is an important prognostic marker in patients with stable coronary artery disease (CAD). Beta-blockers and ivabradine have been shown to improve CFVR in patients with stable CAD, but their effects were never compared. The aim of the current study was to compare the effects of bisoprolol and ivabradine on CFVR in patients with stable CAD. Patients in sinus rhythm with stable CAD were enrolled in this prospective, randomized, double-blind trial. Patients had to be in a stable condition for at least 15 days before enrollment, on their usual therapy. Patients who were receiving beta-blockers or ivabradine entered a 2-week washout period from these drugs before randomization. Transthoracic Doppler-derived CFVR was assessed in left anterior descending coronary artery, and was calculated as the ratio of hyperemic to baseline diastolic coronary flow velocity (CFV). Hyperemic CFV was obtained using dipyridamole administration using standard protocols. After CFVR assessment, patients were randomized to ivabradine or bisoprolol and entered an up-titration phase, and CFVR was assessed again 1 month after the end of the up-titration phase. Fifty-nine patients (38 male, 21 female; mean age 69 ± 9 years) were enrolled. Transthoracic Doppler-derived assessment of CFV and CFVR was successfully performed in all patients. Baseline characteristics were similar between the bisoprolol and ivabradine groups. No patient dropped out during the study. At baseline, rest and hyperemic peak CFV as well as CFVR was not significantly different in the ivabradine and bisoprolol groups. After the therapy, resting peak CFV significantly decreased in both the ivabradine and bisoprolol groups, but there was no significant difference between the groups (ivabradine group 20.7 ± 4.6 vs. 22.8 ± 5.2, P < 0.001; bisoprolol group 20.1 ± 4.1 vs. 22.1 ± 4.3, P < 0.001). However, hyperemic peak CFV significantly increased in both groups, but to a

  11. Doppler limited rotational transitions of OH and SH radicals measured by continuous-wave terahertz photomixing

    Science.gov (United States)

    Eliet, Sophie; Martin-Drumel, Marie-Aline; Guinet, Mickaël; Hindle, Francis; Mouret, Gaël; Bocquet, Robin; Cuisset, Arnaud

    2011-12-01

    A continuous-wave terahertz (CW-THz) source generated by photomixing has been employed to detect and quantify radicals produced in a cold plasma probing their spin-rotation transitions. Due to their dual interest for both atmospherists and astrophysicists, the hydroxyl OH and the mercapto SH radicals have been chosen. The photomixing technique which can access the largest range of THz frequencies of any known coherent source, allowed to resolve the Doppler-limited hyperfine transitions of OH in the 2.5 THz frequency region. Line profile analysis of the hyperfine components demonstrated that OH radicals have been detected in this region at a ppm level at a temperature close to 490 K. The hyperfine structure of SH has been resolved for the first time above 1 THz. Ten new frequency transitions have been measured in the 1.3-2.6 THz frequency range using the CW-THz synthesizer based on a frequency comb. With relative uncertainties better than 10 -7, the CW-THz frequencies measured in this study are now competitive with those measured by other instruments such as frequency multiplication chains or FT-FIR spectrometers and are now capable to improve the predictions of the complete high-resolution spectra of these radicals collected in the atmospheric and astrophysical spectroscopic databases. versioncorrigeeAC 2011-07-18 17:32 2011 Arnaud Cuisset.

  12. Wind gust measurements using pulsed Doppler wind-lidar: comparison of direct and indirect techniques

    DEFF Research Database (Denmark)

    wind vector, we need information from at least three different lines of sight pointing towards different directions. The instrument sensitivity depends on the amount of aerosol present and the velocity measurement uncertainty is directly related to the amount of signal. With the commercial lidars...... traditionally used today it takes several seconds to measure each line of sight with sufficient sensitivity and therefore the temporal resolution of the wind measurement is of the order of tens of seconds, which is not sufficient for gusts. Here we deploy a fast scanning lidar (temporal resolution for a scan...

  13. Imaging doppler lidar for wind turbine wake profiling

    Science.gov (United States)

    Bossert, David J.

    2015-11-19

    An imaging Doppler lidar (IDL) enables the measurement of the velocity distribution of a large volume, in parallel, and at high spatial resolution in the wake of a wind turbine. Because the IDL is non-scanning, it can be orders of magnitude faster than conventional coherent lidar approaches. Scattering can be obtained from naturally occurring aerosol particles. Furthermore, the wind velocity can be measured directly from Doppler shifts of the laser light, so the measurement can be accomplished at large standoff and at wide fields-of-view.

  14. Measurements of turbulent velocity profiles in combined system of polymer additives and riblets; Kobunshi tenkazai to riblet tono fukugokei ni okeru ranryu sokudo bunpu no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Mizunuma, H. [Tokyo Metropolitan Univ., Tokyo (Japan); Ban, T. [Hino Motors, Ltd., Tokyo (Japan)

    2000-03-25

    In the combined system of polymer additives and riblets, the polymer additives expand the range of non-dimensionalized riblet width s{sup +} where the riblets reduce the frictional drag. Although in the higher region of s{sup +} the riblets increase the frictional drag as the rough surface, the polymer additives thicken the wall layer, which dumps the drag increase due to riblets and then gives the benefical combined effect in this higher region of s{sup +}. Based on this scinario, the velocity profile and the pipe frictional coefficient for the combined system were derived from the velocity profile of each system. The turbulent velocity profiles were measured for the combined system using a laser Doppler velocimetry. The measured results agreed well with the derived prediction for the combined system. (author)

  15. Engine classification using vibrations measured by Laser Doppler Vibrometer on different surfaces

    Science.gov (United States)

    Wei, J.; Liu, Chi-Him; Zhu, Zhigang; Vongsy, Karmon; Mendoza-Schrock, Olga

    2015-05-01

    In our previous studies, vehicle surfaces' vibrations caused by operating engines measured by Laser Doppler Vibrometer (LDV) have been effectively exploited in order to classify vehicles of different types, e.g., vans, 2-door sedans, 4-door sedans, trucks, and buses, as well as different types of engines, such as Inline-four engines, V-6 engines, 1-axle diesel engines, and 2-axle diesel engines. The results are achieved by employing methods based on an array of machine learning classifiers such as AdaBoost, random forests, neural network, and support vector machines. To achieve effective classification performance, we seek to find a more reliable approach to pick authentic vibrations of vehicle engines from a trustworthy surface. Compared with vibrations directly taken from the uncooperative vehicle surfaces that are rigidly connected to the engines, these vibrations are much weaker in magnitudes. In this work we conducted a systematic study on different types of objects. We tested different types of engines ranging from electric shavers, electric fans, and coffee machines among different surfaces such as a white board, cement wall, and steel case to investigate the characteristics of the LDV signals of these surfaces, in both the time and spectral domains. Preliminary results in engine classification using several machine learning algorithms point to the right direction on the choice of type of object surfaces to be planted for LDV measurements.

  16. Motion of tympanic membrane in guinea pig otitis media model measured by scanning laser Doppler vibrometry.

    Science.gov (United States)

    Wang, Xuelin; Guan, Xiying; Pineda, Mario; Gan, Rong Z

    2016-09-01

    Otitis media (OM) is an inflammatory or infectious disease of the middle ear. Acute otitis media (AOM) and otitis media with effusion (OME) are the two major types of OM. However, the tympanic membrane (TM) motion differences induced by AOM and OME have not been quantified in animal models in the literature. In this study, the guinea pig AOM and OME models were created by transbullar injection of Streptococcus pneumoniae type 3 and lipopolysaccharide, respectively. To explore the effects of OM on the entire TM vibration, the measurements of full-field TM motions were performed in the AOM, OME and untreated control ears by using scanning laser Doppler vibrometry (SLDV). The results showed that both AOM and OME generally reduced the displacement peak and produced the traveling-wave-like motions at relatively low frequencies. Compared with the normal ear, OME resulted in a significant change of the TM displacement mainly in the inferior portion of the TM, and AOM significantly affected the surface motion across four quadrants. The SLDV measurements provide more insight into sound-induced TM vibration in diseased ears. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. 2-Micron Coherent Doppler Lidar Instrument Advancements for Tropospheric Wind Measurement

    Science.gov (United States)

    Petros, Mulugeta; Singh, U. N.; Yu, J.; Kavaya, M. J.; Koch, G.

    2014-01-01

    Knowledge derived from global tropospheric wind measurement is an important constituent of our overall understanding of climate behavior [1]. Accurate weather prediction saves lives and protects properties from destructions. High-energy 2-micron laser is the transmitter of choice for coherent Doppler wind detection. In addition to the eye-safety, the wavelength of the transmitter suitably matches the aerosol size in the lower troposphere. Although the technology of the 2-micron laser has been maturing steadily, lidar derived wind data is still a void in the global weather database. In the last decade, researchers at NASA Langley Research Center (LaRC) have been engaged in this endeavor, contributing to the scientific database of 2-micron lidar transmitters. As part of this effort, an in depth analysis of the physics involved in the workings of the Ho: Tm laser systems have been published. In the last few years, we have demonstrated lidar transmitter with over1Joule output energy. In addition, a large body of work has been done in characterizing new laser materials and unique crystal configurations to enhance the efficiency and output energy of the 2-micron laser systems. At present 2-micron lidar systems are measuring wind from both ground and airborne platforms. This paper will provide an overview of the advancements made in recent years and the technology maturity levels attained.

  18. Classification of micro-Doppler signatures of human aquatic activity through simulation and measurement using transferred learning

    Science.gov (United States)

    Kim, Youngwook; Park, Jinhee; Moon, Taesup

    2017-05-01

    Remote detection of human aquatic activity can be applied not only to ocean surveillance but also to rescue operations. When a human is illuminated by electromagnetic waves, a Doppler signal is generated from his or her moving parts. Indeed, bodily movements are what make humans' micro-Doppler signatures unique, offering a chance to classify human motions. Certain studies have analyzed and attempted to recognize human aquatic activity, but the topic has yet to be extensively studied. In the present research, we simulate the micro-Doppler signatures of a swimming person in an attempt to investigate those signatures' characteristics. We model human arms as point scatterers while assuming a simple arm motion. By means of such a simulation, we can obtain spectrograms from a swimming person, then extend our measurement to multiple participants. Measurements are taken from five aquatic activities featuring five participants, comprising freestyle, backstroke, and breaststroke, pulling a boat, and rowing. As suggested by the simulation study, the spectrograms for the five activities show different micro-Doppler signatures; hence, we propose to classify them using a deep convolutional neural network (DCNN). In particular, we suggest the use of a transfer-learned DCNN, which is based on a DCNN pretrained by a large-scale RGB image dataset that is, ImageNet. The classification accuracy is calculated using fivefold cross-validation on our dataset. We find that a DCNN trained through transfer learning achieves the highest accuracy while also providing a significant performance boost over the conventional classification method.

  19. Cross-correlation Doppler global velocimetry (CC-DGV)

    Science.gov (United States)

    Cadel, Daniel R.; Lowe, K. Todd

    2015-08-01

    A flow velocimetry method, cross-correlation Doppler global velocimetry (CC-DGV), is presented as a robust, simplified, and high dynamic range implementation of the Doppler global/planar Doppler velocimetry technique. A sweep of several gigahertz of the vapor absorption spectrum is used for each velocity sample, with signals acquired from both Doppler-shifted scattered light within the flow and a non-Doppler shifted reference beam. Cross-correlation of these signals yields the Doppler shift between them, averaged over the duration of the scan. With presently available equipment, velocities from 0 ms-1 to over 3000 ms-1 can notionally be measured simultaneously, making the technique ideal for high speed flows. The processing routine is shown to be robust against large changes in the vapor pressure of the iodine cell, benefiting performance of the system in facilities where ambient conditions cannot be easily regulated. Validation of the system was performed with measurements of a model wind turbine blade boundary layer made in a 1.83 m by 1.83 m subsonic wind tunnel for which laser Doppler velocimetry (LDV) measurements were acquired alongside the CC-DGV results. CC-DGV uncertainties of ±1.30 ms-1, ±0.64 ms-1, and ±1.11 ms-1 were determined for the orthogonal stream-wise, transverse-horizontal, and transverse-vertical velocity components, and root-mean-square deviations of 2.77 ms-1 and 1.34 ms-1 from the LDV validation results were observed for Reynolds numbers of 1.5 million and 2 million, respectively. Volumetric mean velocity measurements are also presented for a supersonic jet, with velocity uncertainties of ±4.48 ms-1, ±16.93 ms-1, and ±0.50 ms-1 for the orthogonal components, and self-validation done by collapsing the data with a physical scaling.

  20. Sub-Doppler magneto-optical trap temperatures measured using Rydberg tagging

    International Nuclear Information System (INIS)

    Tallant, J.; Overstreet, K. R.; Schwettmann, A.; Shaffer, J. P.

    2006-01-01

    We present measurements of polarization-gradient cooling in a Cs magneto-optic trap (MOT). The temperature in the MOT is found to vary linearly with the light shift. The slope gives a value of C σ =0.25±0.05 while the minimum temperature T 0 =3.8±3.3 μK, in agreement with measurements done in the absence of a magnetic field. The temperature is determined by using a nondestructive method which uses Rydberg time-of-flight velocity distributions of trapped atoms

  1. Adaptive Clutter Filtering for Improved Measurement of Cardiac Blood Velocities

    OpenAIRE

    Vågsholm, Beate Haram

    2017-01-01

    In ultrasound color flow images of the heart, irregular blood flow patterns might be an early indication of heart disease. The blood flow is possible to image using multi-dimensional blood velocity estimation like speckle tracking. In order to image the blood flow, the signal from the surrounding tissue must be attenuated, and this is often termed clutter filtering. Insufficient clutter filtering might cause bias in the velocity estimation. It is difficult to design filters with a fixed cut-o...

  2. Performance Analysis and Design Strategy for a Second-Order, Fixed-Gain, Position-Velocity-Measured (α-β-η-θ Tracking Filter

    Directory of Open Access Journals (Sweden)

    Kenshi Saho

    2017-07-01

    Full Text Available We present a strategy for designing an α - β - η - θ filter, a fixed-gain moving-object tracking filter using position and velocity measurements. First, performance indices and stability conditions for the filter are analytically derived. Then, an optimal gain design strategy using these results is proposed and its relationship to the position-velocity-measured (PVM Kalman filter is shown. Numerical analyses demonstrate the effectiveness of the proposed strategy, as well as a performance improvement over the traditional position-only-measured α - β filter. Moreover, we apply an α - β - η - θ filter designed using this strategy to ultra-wideband Doppler radar tracking in numerical simulations. We verify that the proposed strategy can easily design the gains for an α - β - η - θ filter based on the performance of the ultra-wideband Doppler radar and a rough approximation of the target’s acceleration. Moreover, its effectiveness in predicting the steady state performance in designing the position-velocity-measured Kalman filter is also demonstrated.

  3. Measurement of pulmonary arterial elastance in patients with systolic heart failure using Doppler echocardiography

    Science.gov (United States)

    Taghavi, Sepideh; Esmaeilzadeh, Maryam; Amin, Ahmad; Naderi, Nasim; Abkenar, Hooman Bakhshandeh; Maleki, Majid; Mitra, Chitsazan

    2016-01-01

    Objective: A reliable and easy-to-perform method for measuring right ventricular (RV) afterload is desirable when scheduling patients with systolic heart failure to undergo heart transplantation. The present study aimed to investigate the accuracy of echocardiographically-derived pulmonary arterial elastance as a measurement of pulmonary vascular resistance by comparing it with invasive measures. Methods: Thirty-one patients with moderate to severe systolic heart failure, including 22 (71%) male patients, with a mean age of 41.16±15.9 years were enrolled in the study. Right heart catheterization and comprehensive echocardiography during the first hour after completion of cardiac catheterization were performed in all the patients. The pulmonary artery elastance was estimated using the ratio of end-systolic pressure (Pes) over the stroke volume (SV) by both cardiac catheterization [Ea (PV)-C] and echocardiography [Ea (PV)-E]. Results: The mean Ea (PV)-C and Ea (PV)-E were estimated to be 0.73±0.49 mm Hg/mL and 0.67±0.44 mm Hg/mL, respectively. There was a significant relation between Ea (PV)-E and Ea (PV)-C (r=0.897, pechocardiography and catheterization methods for estimating Ea (PV), investigated by the Bland-Altman method, showed a mean bias of -0.06, with 95% limits of agreement from -0.36 mm Hg/mL to 0.48 mm Hg/mL. Conclusion: Doppler echocardiography is an easy, non-invasive, and inexpensive method for measuring pulmonary arterial elastance, which provides accurate and reliable estimation of RV afterload in patients with systolic heart failure. PMID:26467379

  4. Line-RALF Doppler Velocimetry

    Science.gov (United States)

    Fajardo, Mario

    2017-06-01

    We report the successful proof-of-concept demonstration of a 1D spatially-dependent variant of our Rubidium Atomic Line Filtered (RALF) Doppler velocimetry technique, using streak camera detection of laser light reflected from 1-mm-diameter laser-driven flyers traveling at 1 km/s. RALF employs the frequency-dependent near-resonant optical absorption of a heated Rb/N2 gas cell to convert the Doppler shift of reflected 780.24 nm light directly into transmitted light intensity. This approach results in each individual pixel in a RALF image constituting an independent velocity measurement. RALF advantages over conventional interferometric Doppler velocimetry methods include: a time response limited only by the optoelectronic detection system, and facile adaptation for 1D, and even 2D, imaging velocimetry applications. RALF disadvantages include: the direct conversion of image intensity noise into calculated velocity noise, extreme sensitivity to loss of signal upon shock breakout, and poor tolerance of parasitic reflections of unshifted illumination laser light.

  5. Helium temperature measurements in a hot filament magnetic mirror plasma using high resolution Doppler spectroscopy

    Science.gov (United States)

    Knott, S.; McCarthy, P. J.; Ruth, A. A.

    2016-09-01

    Langmuir probe and spectroscopic diagnostics are used to routinely measure electron temperature and density over a wide operating range in a reconfigured Double Plasma device at University College Cork, Ireland. The helium plasma, generated through thermionic emission from a negatively biased tungsten filament, is confined by an axisymmetric magnetic mirror configuration using two stacks of NdFeB permanent magnets, each of length 20 cm and diameter 3 cm placed just outside the 15 mm water cooling jacket enclosing a cylindrical vacuum vessel of internal diameter 25 cm. Plasma light is analysed using a Fourier Transform-type Bruker spectrometer with a highest achievable resolution of 0.08 cm-1 . In the present work, the conventional assumption of room temperature ions in the analysis of Langmuir probe data from low temperature plasmas is examined critically using Doppler spectroscopy of the 468.6 nm He II line. Results for ion temperatures obtained from spectroscopic data for a variety of engineering parameters (discharge voltage, gas pressure and plasma current) will be presented.

  6. Population pharmacokinetic/pharmacodynamic modeling of histamine response measured by histamine iontophoresis laser Doppler.

    Science.gov (United States)

    Liu, Xiaoxi; Jones, Bridgette L; Roberts, Jessica K; Sherwin, Catherine M

    2016-08-01

    The epicutaneous histamine (EH) test is the current gold standard method for the clinical evaluation of allergic conditions. However, the EH method is limited in providing an objective and qualitative assessment of histamine pharmacodynamic response. The histamine iontophoresis with laser Doppler (HILD) monitoring method, an alternative method, allows a fixed dose of histamine to be delivered and provides an objective, continuous, and dynamic measurement of histamine epicutaneous response in children and adults. However, due to the high sampling frequency (up to 40 Hz), the output files are usually too cumbersome to be directly used for further analysis. In this study, we developed an averaging algorithm that efficiently reduces the HILD data in size. The reduced data was further analyzed and a population linked effect pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the local histamine response. The model consisted of a one-compartment PK model and a direct-response fractional maximum effect (Emax) model. The parameter estimates were obtained as follows: absorption rate constant (ka), 0.094/min; absorption lag time (Tlag), 2.72 min; partitioning clearance from local depot to systemic circulation (CLpar), 0.0006 L/min; baseline effect (E0), 13.1 flux unit; Emax, 13.4; concentration at half maximum effect (EC50) 31.1 mg/L. Covariate analysis indicated that age and race had significant influence on Tlag and EC50, respectively.

  7. Doppler ultrasound measurement of resistance index in the diagnosis of prostate cancer.

    Science.gov (United States)

    Huang, Wei; Cen, Son; Kang, Xin-Li; Wang, Wei Fu; Wang, Yang; Chen, Xiang

    2015-01-01

    Prostate cancer (PCa) remains the second leading cause of cancer diagnosis worldwide. Early diagnosis and treatment of PCa is critical since the long-term prognosis is excellent in patients with tumors confined to the prostate gland. The current meta-analysis investigates the diagnostic value of resistive index (RI) measurement using color Doppler ultrasound in patients with PCa. Electronic literature databases were exhaustively searched for relevant studies published prior to May 31, 2014. Nine studies met our predetermined inclusion criteria for the present meta-analysis. The methodologic quality of the selected studies was independently assessed by 2 reviewers based on Quality Assessment of Diagnostic Accuracy Studies tool. Our meta-analysis results showed that RI values were significantly higher in malignant prostate tissues compared to normal prostate tissues (standardized mean difference [SMD] 0.42, 95% confidence interval [CI] 0.12~0.73, p = 0.007) and benign prostate tissues (SMD 0.41, 95% CI 0.26~0.56, pbased on the diagnostic instruments used revealed that RI values were accurate in diagnosis of PCa when compared between malignant tissue vs normal tissue and malignant tissue vs benign tissue (all pvalues in diagnosis of PCa.

  8. A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s(-1).

    Science.gov (United States)

    Li, Chih-Hao; Benedick, Andrew J; Fendel, Peter; Glenday, Alexander G; Kärtner, Franz X; Phillips, David F; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L

    2008-04-03

    Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.

  9. A comparative cepstral based analysis of simulated and measured S-band and X-band radar Doppler spectra of human motion

    CSIR Research Space (South Africa)

    Van Eeden, WD

    2015-10-01

    Full Text Available A simulation for human Doppler response is developed based on the Carnegie Mellon University motion capture database. This data is used to simulate human Doppler response as it would be seen by a radar system and this data is compared to measured...

  10. A method for measuring mean wind velocities in a canyon with tracer balloons

    Science.gov (United States)

    Sheih, C. M.; Billman, B. J.; Depaul, F. T.

    1985-08-01

    A method using balloons as tracers for measuring mean wind velocity in street canyons or mountain valleys has been developed. Tests of the method with numerical experiments showed that the method reproduced an assumed wind field quite well provided that the buoyancy component of the balloon velocity was larger than the downward velocity component of the wind. Tests of the method with measurements of wind velocity in a street canyon of downtown Chicago showed that the method yielded flow patterns quite similar to photographic results of flow visualization of phisical simulations by other investigators. However, no direct measurements of wind velocity were available for quantitative comparison.

  11. Topographic imaging and velocity measurements of surface expansion during laser ablation of a metal layer on glass

    Science.gov (United States)

    Rodriguez, G.; Valenzuela, A. R.; Clarke, S. A.; Thomas, K. A.

    2006-05-01

    We report on the development of novel high-speed techniques to measure the surface topography and instantaneous velocity of ablatively launched thin metal layers with sub-nanosecond temporal resolution. Applications for laser detonator technology require the understanding of laser fiber optical energy deposition and ablative launch of a thin metal layer into an explosive. Characterization of the ablation process requires a time-resolved diagnosis of the ejected material state (topography, velocity, density, pressure, etc.). A pulsed Nd:YAG fibercoupled laser is used to ablate a 250 nm layer of titanium deposited on a 500 μm thick fused silica substrate at fluences below 10 J/cm2. Time-resolved imaging of the free expansion of the metal surface is accomplished with Fourier plane imaging using a Shack-Hartmann lenticular array coupled to a fast framing camera. The imager performs topographical surface measurements by detecting changes in the optical wavefront of a reflected picosecond probe laser beam off the expanding surface. Consequently, single-event sub-nanosecond time-resolved "movies" of surface motion dynamics are captured. Crosscheck of the Shack-Hartmann imager is done using advanced velocimetry. A 1550 nm heterodyne laser-based Photonic Doppler Velocimeter is used to measure surface velocity. Using a 1550 nm single mode fiber laser, 10 GHz InGaAs detectors and telecom hardware, we directly record the resulting beat signal produced by the accelerated surface onto a fast digitizer. Free surface velocities as high as 6.5 μm/ns are recorded. Comparisons between the dynamic topography, surface velocimetry and laser hydrocode simulations are presented.

  12. "Cognitive activity" monitored by non-invasive measurement of cerebral blood flow velocity and its application to the investigation of cerebral dominance.

    Science.gov (United States)

    Markus, H S; Boland, M

    1992-12-01

    We have developed a method of non-invasively detecting language lateralisation by measuring the increase in middle cerebral artery blood flow velocity occurring during a word association task, using transcranial Doppler ultrasonography. All exclusively right handed subjects (N = 12) showed a relative increase in left sided flow velocity during the task; mean rise was 4.04% on the left, and -0.03% on the right (p 5%) in left, compared with right, hemisphere flow velocity, and three showing only small differences between left and right sides, possibly reflecting bilateral language representation. This technique offers potential not only in studying patterns of cerebral dominance, but also in studying cognitive responses to other stimuli.

  13. A comparison between 133Xenon washout technique and Laser Doppler flowmetry in the measurement of local vasoconstrictor effects on the microcirculation in subcutaneous tissue and skin

    DEFF Research Database (Denmark)

    Kastrup, J; Bülow, J; Lassen, N A

    1987-01-01

    level. The measurements were performed in tissue with and without sympathetic innervation. In five subjects, who all had been cervically sympathectomized for manual hyperhidrosis, the Laser Doppler and 133Xenon blood flow measurements were performed simultaneously on the sympathetically denervated...

  14. Results from transcranial Doppler examination on children and adolescents with sickle cell disease and correlation between the time-averaged maximum mean velocity and hematological characteristics: a cross-sectional analytical study

    Directory of Open Access Journals (Sweden)

    Mary Hokazono

    Full Text Available CONTEXT AND OBJECTIVE: Transcranial Doppler (TCD detects stroke risk among children with sickle cell anemia (SCA. Our aim was to evaluate TCD findings in patients with different sickle cell disease (SCD genotypes and correlate the time-averaged maximum mean (TAMM velocity with hematological characteristics. DESIGN AND SETTING: Cross-sectional analytical study in the Pediatric Hematology sector, Universidade Federal de São Paulo. METHODS: 85 SCD patients of both sexes, aged 2-18 years, were evaluated, divided into: group I (62 patients with SCA/Sß0 thalassemia; and group II (23 patients with SC hemoglobinopathy/Sß+ thalassemia. TCD was performed and reviewed by a single investigator using Doppler ultrasonography with a 2 MHz transducer, in accordance with the Stroke Prevention Trial in Sickle Cell Anemia (STOP protocol. The hematological parameters evaluated were: hematocrit, hemoglobin, reticulocytes, leukocytes, platelets and fetal hemoglobin. Univariate analysis was performed and Pearson's coefficient was calculated for hematological parameters and TAMM velocities (P < 0.05. RESULTS: TAMM velocities were 137 ± 28 and 103 ± 19 cm/s in groups I and II, respectively, and correlated negatively with hematocrit and hemoglobin in group I. There was one abnormal result (1.6% and five conditional results (8.1% in group I. All results were normal in group II. Middle cerebral arteries were the only vessels affected. CONCLUSION: There was a low prevalence of abnormal Doppler results in patients with sickle-cell disease. Time-average maximum mean velocity was significantly different between the genotypes and correlated with hematological characteristics.

  15. Design of channel experiment equipment for measuring coolant velocity of innovative research reactor

    International Nuclear Information System (INIS)

    Muhammad Subekti; Endiah Puji Hastuti; Dedi Heriyanto

    2014-01-01

    The design of innovative high flux research reactor (RRI) requires high power so that the capability core cooling requires to be improved by designing the faster core coolant velocity near to the critical velocity limit. Hence, the critical coolant velocity as the one of the important parameter of the reactor safety shall be measured by special equipment to the velocity limit that may induce fuel element degradation. The research aims is to calculate theoretically the critical coolant velocity and to design the special experiment equipment namely EXNal for measuring the critical coolant velocity in fuel element subchannel of the RRI. EXNal design considers the critical velocity calculation result of 20.52 m/s to determine the variation of flow rate of 4.5-29.2 m 3 /h, in which the experiment could simulate the 1-4X standard coolant velocity of RSG-GAS as well as destructive test of RRI's fuel plate. (author)

  16. High speed velocity measurements on an EFI-system

    NARCIS (Netherlands)

    Prinse, W.C.; Hof, P.G. van 't; Cheng, L.K.; Scholtes, J.H.G.

    2007-01-01

    For the development of an Exploding Foil Initiator for Insensitive Munitions applications the following topics are of interest: the electrical circuit, the exploding foil, the velocity of the flyer, the driver explosive, the secondary flyer and the acceptor explosive. Several parameters of the EFI

  17. Photographic method measures particle size and velocity in fluid stream

    Science.gov (United States)

    Dickerson, R. A.

    1966-01-01

    Method employing a nonframing motion picture camera, a continuous front light source, and a strobe light determines the size and velocity of small particles in nonturbulent fluid streams. This method is used in the study of the motion of solid and liquid particles in research and industrial fluid flow systems.

  18. Three-dimensional instantaneous velocity field measurement using ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... ... Singh P K Panigrahi. Contributed Papers Volume 82 Issue 2 February 2014 pp 439-444 ... Abstract. In the present study, a digital holography microscope has been developed to study instantaneous 3D velocity field in a square channel of 1000 × 1000 2 cross-section. The flow field is seeded with ...

  19. Measurements of Sound Velocity of Laser-Irradiated Iron Foils Relevant to Earth Core Condition

    International Nuclear Information System (INIS)

    Shigemori, K.; Ichinose, D.; Otani, K.; Shiota, T.; Sakaiya, T.; Azechi, H.; Irifune, T.

    2006-01-01

    We have developed a novel method to measure sound velocity of laser-irradiated iron foils by side-on x-ray radiograph technique. Iron foils were irradiated with two-stepped laser pulse to reach the earth's core condition. We obtained not only the sound velocity but also temperature, pressure, shock velocity, compressibility, and particle velocity of the laser-irradiated iron. The experimental results are in good agreements with previous experimental results and with one-dimensional simulation results

  20. Aortic pulse wave velocity measurement in systemic sclerosis patients

    Directory of Open Access Journals (Sweden)

    M. Sebastiani

    2012-12-01

    Full Text Available Background. Systemic sclerosis (SSc is characterized by endothelial dysfunction and widespread microangiopathy. However, a macrovascular damage could be also associated. Aortic pulse wave velocity (aPWV is known to be a reliable indicator of arterial stiffness and a useful prognostic predictor of cardiovascular events. Moreover, aPWV may be easily measured by non-invasive, user-friendly tool. Aim of our study was to evaluate aPWV alterations in a series of SSc patients. Methods. The aPWV was evaluated in 35 consecutive female SSc patients and 26 sex- and age-matched healthy controls. aPWV alterations were correlated with cardiopulmonary involvement. Results. A significant increase of aPWV was observed in SSc patients compared to controls (9.4±3.2 m/s vs 7.3±1 m/s; P=0.002. In particular, 14/35 (40% SSc patients and only 1/26 (4% controls (P=0.0009 showed increased aPWV (>9 m/s cut-off value. Moreover, echocardiography evaluation showed an increased prevalence of right atrial and ventricular dilatation (atrial volume: 23.6±6.2 mL vs 20.3±4.3 mL, P=0.026; ventricular diameter 19.5±4.9 mm vs 15.9±1.6 mm; P=0.001 associated to higher values of pulmonary arterial systolic pressure (PAPs in SSc patients (31.5±10.4 mmHg vs 21.6±2.9 mmHg; P50 years old. Furthermore, altered aPWV was more frequently associated with limited cutaneous pattern, longer disease duration (≥5 years, and/or presence of anticentromere antibody (ACA. Conclusions. A significantly higher prevalence of abnormally increased aPWV was evidenced in SSc patients compared to healthy controls. The possibility of more pronounced and diffuse vascular damage in a particular SSc subset (ACA-positive subjects with limited cutaneous scleroderma and longer disease duration might be raised.

  1. Intracranial Blood-Flow Velocity and Pressure Measurements Using an Intra-Arterial Dual-Sensor Guidewire

    NARCIS (Netherlands)

    Ferns, S. P.; Schneiders, J. J.; Siebes, M.; van den Berg, R.; van Bavel, E. T.; Majoie, C. B.

    2010-01-01

    Hemodynamics is thought to play a role in the growth and rupture of intracranial aneurysms. In 4 patients, we obtained local pressure and BFV by using a dual-sensor pressure and Doppler velocity wire within and in vessels surrounding unruptured aneurysms. Local BFVs can serve as boundary conditions

  2. Coherent compounding in doppler imaging.

    Science.gov (United States)

    Ekroll, Ingvild K; Voormolen, Marco M; Standal, Oyvind K-V; Rau, Jochen M; Lovstakken, Lasse

    2015-09-01

    Coherent compounding can provide high frame rates and wide regions of interest for imaging of blood flow. However, motion will cause out-of-phase summation, potentially causing image degradation. In this work the impact of blood motion on SNR and the accuracy of Doppler velocity estimates are investigated. A simplified model for the compounded Doppler signal is proposed. The model is used to show that coherent compounding acts as a low-pass filter on the coherent compounding Doppler signal, resulting in negatively biased velocity estimates. Simulations and flow phantom experiments are used to quantify the bias and Doppler SNR for different velocities and beam-to-flow (BTF) angles. It is shown that the bias in the mean velocity increases with increasing beam-to-flow angle and/or blood velocity, whereas the SNR decreases; losses up to 4 dB were observed in the investigated scenarios. Further, a 2-D motion correction scheme is proposed based on multi-angle vector Doppler velocity estimates. For a velocity of 1.1 v(Nyq) and a BTF angle of 75°, the bias was reduced from 30% to less than 4% in simulations. The motion correction scheme was also applied to flow phantom and in vivo recordings, in both cases resulting in a substantially reduced mean velocity bias and an SNR less dependent on blood velocity and direction.

  3. The SDSS-III DR12 MARVELS radial velocity data release: the first data release from the multiple object Doppler exoplanet survey

    Science.gov (United States)

    Ge, Jian; Thomas, Neil B.; Li, Rui; Senan Seieroe Grieves, Nolan; Ma, Bo; de Lee, Nathan M.; Lee, Brian C.; Liu, Jian; Bolton, Adam S.; Thakar, Aniruddha R.; Weaver, Benjamin; SDSS-Iii Marvels Team

    2015-01-01

    We present the first data release from the SDSS-III Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) through the SDSS-III DR12. The data include 181,198 radial velocity (RV) measurements for a total of 5520 different FGK stars with V~7.6-12, of which more than 80% are dwarfs and subdwarfs while remainders are GK giants, among a total of 92 fields nearly randomly spread out over the entire northern sky taken with a 60-object MARVELS dispersed fixed-delay interferometer instrument over four years (2008-2012). There were 55 fields with a total of 3300 FGK stars which had 14 or more observations over about 2-year survey window. The median number of observations for these plates is 27 RV measurements. This represents the largest homogeneous sample of precision RV measurements of relatively bright stars. In this first released data, a total of 18 giant planet candidates, 16 brown dwarfs, and over 500 binaries with additional 96 targets having RV variability indicative of a giant planet companion are reported. The released data were produced by the MARVELS finalized 1D pipeline. We will also report preliminary statistical results from the MARVELS 2D data pipeline which has produced a median RV precision of ~30 m/s for stable stars.

  4. Multi Point Velocity, Density and Temperature Measurements using LITA, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser induced thermal acoustics (LITA) is a nonintrusive, transient-grating optical technique that provides simultaneous high-accuracy measurements of velocity,...

  5. Measuring In-Situ Mdf Velocity Of Detonation

    Science.gov (United States)

    Horine, Frank M.; James, Jr., Forrest B.

    2005-10-25

    A system for determining the velocity of detonation of a mild detonation fuse mounted on the surface of a device includes placing the device in a predetermined position with respect to an apparatus that carries a couple of sensors that sense the passage of a detonation wave at first and second spaced locations along the fuse. The sensors operate a timer and the time and distance between the locations is used to determine the velocity of detonation. The sensors are preferably electrical contacts that are held spaced from but close to the fuse such that expansion of the fuse caused by detonation causes the fuse to touch the contact, causing an electrical signal to actuate the timer.

  6. Cardiac Time Intervals Measured by Tissue Doppler Imaging M-mode

    DEFF Research Database (Denmark)

    Biering-Sørensen, Tor; Møgelvang, Rasmus; Schnohr, Peter

    2016-01-01

    function was evaluated in 1915 participants by using both conventional echocardiography and tissue Doppler imaging (TDI). The cardiac time intervals, including the isovolumic relaxation time (IVRT), isovolumic contraction time (IVCT), and ejection time (ET), were obtained by TDI M-mode through the mitral...

  7. Methods and Systems for Use of an Acoustic Doppler Current Profiler for Measurement of Compact Jets

    National Research Council Canada - National Science Library

    Hendricks, Peter J

    2007-01-01

    ... an Acoustic Doppler Current Profiler (ADCP). The ADCP is a four-beam, Janus-type ADCP having beams aligned so that each of the beams is at an angle of about 200 to 300 to vertical and at 450 to the fore and aft axis of the vessel, such that two...

  8. Methods to quantify the velocity dependence of common gait measurements from automated rodent gait analysis devices.

    Science.gov (United States)

    Neckel, Nathan D

    2015-09-30

    Walking slowly is a different biomechanical task than walking quickly, thus measures of gait will be different at different velocities, such as pre/post injury. It is necessary to determine if the difference in gait measures are from the experimental changes, or simply from traveling at different speeds. Instead of limiting this effect, we have developed techniques to embrace the velocity dependence of gait measures. By translating the pawprints into a body coordinate frame we are able to measure location of paw placement in addition to the standard gait measures. At higher velocities rats have greater consistency of steps, place their forelimb initial contact more medially and anteriorly, and place their hindlimb toe off more medially and posteriorly. Interlimb phasing also becomes more consistent at higher velocities. Following a cervical spinal cord injury consistency is reduced and the velocity dependent behaviors are significantly different. Translating the coordinate frame improves the ability to measure changes in base of support following spinal cord injury. Employing a treadmill, or limiting analysis to a narrow velocity window does address the effects of velocity. We feel that measuring across all velocities is more appropriate than dictating that the animals match speeds. Quantifying locomotion with automated gait analysis devices is a great way to evaluate the changes that experimental treatments provide. These new methods allow for a more appropriate way to address the confound of many gait measures being velocity dependent. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. MEaSUREs Greenland Ice Velocity: Selected Glacier Site Velocity Maps from InSAR

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program. This data set provides maps of glacier outlet...

  10. Velocity measurement by vortex shedding. Contribution to the mass-flow measurement

    International Nuclear Information System (INIS)

    Martinez Piquer, T.

    1988-01-01

    The phenomenon of vortex shedding has been known for centuries and has been the subject of scientific studies for about one hundred years. It is only in the ten last years that is has been applied to the measurement of fluids velocity. In 1878 F. Strouhal observed the vortex shedding phenomenon and shown that the shedding frequency of a wire vibrating in the wind was related to the wire diameter and the wind velocity. Rayleigh, who introduced the non-dimensional Strouhal number, von Karman and Rohsko, carried out extensive work or the subject which indicated that vortex shedding could form the basis for a new type of flowmeter. The thesis describes two parallel lines of investigation which study in depth the practical applications of vortex shedding. The first one deals with the measure of velocity and it presents the novelty of a bluff body with a cross-section which has not been used until this day. This body is a circular cylinder with a two-dimensional slit along the diameter and situated in crossdirection to the fluid's stream. It possesses excellent characteristics and it is the most stable as a vortex shedder, which gives it great advantage to the rest of the shapes used until now. The detection of the vortex has been performed by measuring the pressure changes generated by the vortex on two posts situated just beside the slit. To calculate the frequency of the vortex shedding, we obtain the difference of the mentioned signals, which are the same and 180 out of phase. Finding out the period of the autocorrelation function of this signal we can estimate the velocity of the fluid. A logical equipment based on a microprocessor has been designed for the calculation using a zero-crossing time algorithm implemented in assembler language. The second line of research refers to a new method of measure mass flow. The pressure signal generated by the vortex has an intensity which is proportional to the density and to the square of the velocity. Since we have already

  11. Left Ventricular Assist Device Thrombosis Is Associated With an Increase in the Systolic-to-Diastolic Velocity Ratio Measured at the Inflow and Outflow Cannulae.

    Science.gov (United States)

    Jain, Ankit; Rohrer, Ben; Gebhardt, Brian; Breeze, Janis L; Quick, Joshua D; Couper, Gregory; Kiernan, Michael S; Lawrence, Matthew; Cobey, Frederick C

    2017-04-01

    To determine whether the ratio of peak systolic-to-nadir diastolic velocity (S/D ratio) measured using Doppler at the left ventricular assist device (LVAD) inflow and outflow cannulae is associated with pump thrombosis and to determine whether there is an absolute decrease in the diastolic cannula velocities in LVAD thrombosis. Retrospective chart review. University hospital. Patients who underwent LVAD exchange. None. Transesophageal echocardiograms were reviewed from all patients with the HeartMate II device (Thoratec Corporation, Pleasanton, CA) over a 6-year period and who underwent LVAD exchange for pump thrombosis. The following 3 time points were evaluated: (1) initial LVAD placement (prethrombosis), (2) thrombosis, and (3) exchanged LVAD placement (postthrombosis). Systolic and diastolic flow velocities were examined using pulse-wave spectral Doppler at the inflow and outflow cannulae, and the S/D ratio for each was determined. Statistical analysis was performed with SAS, version 9.4 (SAS Institute, Cary, NC), using 2-tailed tests and alpha = 0.05. Thirteen patients were included in the study. Significant differences were observed in S/D ratios among the 3 phases at both the inflow (p = 0.0234) and outflow (p = 0.0047) cannulae. Pairwise tests of the inflow cannulae showed that the mean S/D ratio at the time of thrombosis (mean ± standard deviation [SD], 4.29 ± 1.74) was significantly greater than the prethrombosis ratio (2.49 ± 0.65; p = 0.0069). Among outflow measurements, the mean S/D ratio at thrombosis (3.94 ± 1.34) was significantly higher than both the prethrombosis (2.63 ± 0.56; p = 0.0025) and postthrombosis (2.74 ± 0.83) (p = 0.0093) ratios. Decreases in diastolic velocities were not statistically significant at the inflow cannula. At the outflow cannula, there was a significant difference in diastolic velocity among the phases (p = 0.0233). Specifically, the postthrombosis diastolic measurements (41.50 ± 9.94) were significantly higher

  12. Proving diamonds under ultra-high pressure with sound velocity measurements

    Science.gov (United States)

    Shigemori, Keisuke; Shimizu, Katsuya; Asakura, Yasuhiro; Sakaiya, Tatsuhiro; Kondo, Tadashi; Hironaka, Yoichiro; Irifune, Tetsuo; Sumiya, Hitoshi; Kadono, Toshihiko; Azechi, Hiroshi

    2014-10-01

    Diamond under terapascal (TPa) regime is of great interest on its phase transition to a post diamond phase. Many experimental works have been done on the diamond at the TPa regime by measuring the shock parameters (shock velocity, particle velocity). We measured sound velocities of shock-compressed diamond under several pressures by means of x-ray backlighting technique. Experiments were done on GEKKO-HIPER laser irradiation facility at Institute of Laser Engineering, Osaka University. We obtained sound velocities at a pressure of 0.4 - 2.0 TPa by changing the laser intensity. The experimental sound velocity suggests that a clear discontinuity at around 0.7 TPa where the melting of the diamond starts. The sound velocity drops then slightly increases with increasing pressure. The slope of the sound velocity over 1 TPa is lower than that under 0.7 TPa, indicating the melting of the diamond.

  13. Measuring the Variations of the Apparent Settling Velocity for Fine Particles

    DEFF Research Database (Denmark)

    Larsen, Torben

    2000-01-01

    This note establishes the fact that the settling velocity for fine flocculent particles in flowing aquatic systems vary considerably and the settling velocity should therefore be understood as a variable which varies temporally and spatially in the flow field. In the mathematical formulation...... the settling velocity of a suspension appears in the actual and local mass conservation equation as an apparent settling velocity. A new approach to measuring this variable settling velocity is mentioned and its relation to well-known principles, e.g. settling columns, is discussed....

  14. Mass sensitivity of acoustic wave devices from group and phase velocity measurements

    Science.gov (United States)

    McHale, G.; Martin, F.; Newton, M. I.

    2002-09-01

    The effect of dispersion on acoustic wave sensors is considered. The discussion is focused upon layer guided surface acoustic waves (Love waves), which obtain their high mass sensitivity for the first Love wave mode by optimizing the guiding layer thickness, d, such that dapprox][lambdal/4; the wavelength in the layer is given by lambdal=f/vl where f is the operating frequency and vl is the shear acoustic speed of the guiding layer. We show that this optimization of guiding layer thickness corresponds to strong dispersion so that the phase and group velocities can be quite different. From the definition of the phase velocity mass sensitivity, we show that it can be determined from either the slope of the curve of phase velocity with normalized guiding layer thickness, z=d/lambdal, or from the phase and group velocities measured for a given guiding layer thickness. Experimental data for a poly(methylmethacrylate) polymer guiding layer on 36deg XY Lithium Tantalate is presented. Measurements of phase velocity and group velocity determined by a network analyzer were obtained for systematically increasing guiding layer thicknesses; a pulse transit experiment was also used to provide independent confirmation of the group velocity data. Two independent estimates of the mass sensitivity are obtained for z=d/lambdal<0.22 from (i) the slope of the phase velocity curve and (ii) the measurements of the group and phase velocity. These two estimates are shown to be consistent and we, therefore, conclude that it is possible to determine the mass sensitivity for a Love wave device with a given guiding layer thickness from measurements of the phase and group velocities. Moreover, we argue that the formula using group velocity to determine phase velocity mass sensitivity can be extended to a wide range of other acoustic wave sensors. In addition, we suggest that variations in the group velocity due to deposited mass may be a more sensitive parameter than variations in the phase

  15. 3C velocity field measurement in microscale using time resolved micro-PIV

    OpenAIRE

    N., Erkan; K., Okamoto; Dept. of Quantum Eng. and Sys. Science, The University of Tokyo; Inst. of Env. Studies, The University of Tokyo

    2007-01-01

    Measurement of the 3C velocity field in the microfluidic devices with the conventional techniques and conventional micro-PIV is still difficult due to the limited optical access to the microscale flow fields. Mainly micro PIV vector field realizations have been remained limited to 2C velocities. In this study, 3C velocity measurement in microscale using 2-dimentional time-resolved micro PIV images is proposed. The method is based on the PIV performs cross-correlation (CC) peak height tracking...

  16. Diagnostic accuracy of laser Doppler flowmetry versus strain gauge plethysmography for segmental pressure measurement.

    Science.gov (United States)

    Høyer, Christian; Sandermann, Jes; Paludan, Jens Peder D; Pavar, Susanne; Petersen, Lars J

    2013-12-01

    To assess the diagnostic accuracy of laser Doppler flowmetry (LDF) with mercury-in-silastic strain gauge plethysmography (SGP) as a reference test for measuring the toe and ankle pressures in patients with known or suspected peripheral arterial disease (PAD). This was a prospective, randomized, blinded diagnostic accuracy study. Toe and ankle pressures were measured using both methods in 200 consecutive patients, who were recruited at our vascular laboratory over a period of 30 working days. Classification of PAD and critical limb ischemia (CLI) was made in accordance with TASC-II criteria. The LDF method demonstrated 5.8 mm Hg higher mean toe pressures than the SGP method for the right limb and 7.0 mm Hg for the left limb (both P pressures (both P > .129). The limits of agreement for the differences (SGP - LDF) were -31.7 to 20.2 mm Hg for right toe pressures, -28.0 to 14.0 mm Hg for left toe pressures, -25.5 to 22.8 mm Hg for right ankle pressures, and -26.9 to 24.6 mm Hg for left ankle pressures. A correlation analysis of the absolute pressures using the two methods showed an intraclass correlation coefficient of 0.902 (95% confidence interval [CI], 0.835-0.938) for right toe pressures, 0.919 (95% CI, 0.782-0.960) for the left toe pressures, 0.953 (95% CI, 0.937-0.965) for right ankle pressures, and 0.952 (95% CI, 0.936-0.964) for left ankle pressures. Cohen's Kappa showed an agreement in the diagnostic classification of κ = 0.775 (95% CI, 0.631-0.919) for PAD and κ = 0.780 (95% CI, 0.624-0.936) for CLI. LDF showed a good correlation with SGP over a wide range of toe and ankle pressures, as well as substantial agreement for the diagnostic classification of PAD including CLI. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  17. Does the application of gadolinium-DTPA have an impact on magnetic resonance phase contrast velocity measurements? Results from an in vitro study

    International Nuclear Information System (INIS)

    Heverhagen, J.T.; Hoppe, M.; Klose, K.-J.; Wagner, H.-J.

    2002-01-01

    Introduction/objective: To evaluate the potential influence of various concentrations of gadolinium (Gd)-DTPA on magnetic resonance phase contrast (MR PC) velocimetry. Material and methods: Imaging was done with a 1.0 T scanner using a standard Flash 2D sequence and a circular polarized extremity coil. In a validated flow phantom with a defined 75% area stenosis different concentrations of Gd-DTPA, diluted in a 10:1 water-yogurt mixture, MR PC measurements were correlated with a Doppler guide wire as gold standard. Results: MR PC measurements correlated well with the Doppler derived data (r=0.99; P 0.05; Student's t-test) flow measurement changes were noted (maximum pre-stenotic velocity: 21.3±1.3 cm/s; maximum intra-stenotic velocity: 84.0±3.6 cm/s). However, delineation of the perfused lumen was enhanced after the application of Gd-DTPA. Discussions and conclusion: The application of Gd-DTPA does not affect MR PC velocimetry. However, the application of contrast media allowed a more accurate vessel segmentation. MR PC measurements can be reliably carried out after application of Gd-DTPA

  18. Stratospheric temperature measurement with scanning Fabry-Perot interferometer for wind retrieval from mobile Rayleigh Doppler lidar.

    Science.gov (United States)

    Xia, Haiyun; Dou, Xiankang; Shangguan, Mingjia; Zhao, Ruocan; Sun, Dongsong; Wang, Chong; Qiu, Jiawei; Shu, Zhifeng; Xue, Xianghui; Han, Yuli; Han, Yan

    2014-09-08

    Temperature detection remains challenging in the low stratosphere, where the Rayleigh integration lidar is perturbed by aerosol contamination and ozone absorption while the rotational Raman lidar is suffered from its low scattering cross section. To correct the impacts of temperature on the Rayleigh Doppler lidar, a high spectral resolution lidar (HSRL) based on cavity scanning Fabry-Perot Interferometer (FPI) is developed. By considering the effect of the laser spectral width, Doppler broadening of the molecular backscatter, divergence of the light beam and mirror defects of the FPI, a well-behaved transmission function is proved to show the principle of HSRL in detail. Analysis of the statistical error of the HSRL is carried out in the data processing. A temperature lidar using both HSRL and Rayleigh integration techniques is incorporated into the Rayleigh Doppler wind lidar. Simultaneous wind and temperature detection is carried out based on the combined system at Delhi (37.371°N, 97.374°E; 2850 m above the sea level) in Qinghai province, China. Lower Stratosphere temperature has been measured using HSRL between 18 and 50 km with temporal resolution of 2000 seconds. The statistical error of the derived temperatures is between 0.2 and 9.2 K. The temperature profile retrieved from the HSRL and wind profile from the Rayleigh Doppler lidar show good agreement with the radiosonde data. Specifically, the max temperature deviation between the HSRL and radiosonde is 4.7 K from 18 km to 36 km, and it is 2.7 K between the HSRL and Rayleigh integration lidar from 27 km to 34 km.

  19. VizieR Online Data Catalog: K2-106 radial velocities measurements (Guenther+, 2017)

    Science.gov (United States)

    Guenther, E. W.; Barragan, O.; Dai, F.; Gandolfi, D.; Hirano, T.; Fridlund, M.; Fossati, L.; Chau, A.; Helled, R.; Korth, J.; Prieto-Arranz, J.; Nespral, D.; Antoniciello, G.; Deeg, H.; Hjorth, M.; Grziwa, S.; Albrecht, S.; Hatzes, A. P.; Rauer, H.; Csizmadia, Sz.; Smith, A. M. S.; Cabrera, J.; Narita, N.; Arriagada, P.; Burt, J.; Butler, R. P.; Cochran, W. D.; Crane, J. D.; Eigmueller, P.; Erikson, A.; Johnson, J. A.; Kiilerich, A.; Kubyshkina, D.; Palle, E.; Persson, C. M.; Paetzold, M.; Sabotta, S.; Sato, B.; Shectman, St. A.; Teske, J. K.; Thompson, I. B.; van Eylen, V.; Nowak, G.; Vanderburg, A.; Winn, J. N.; Wittenmyer, R. A.

    2017-11-01

    k2-106re.dat contains the relative radial velocity measurements of K2-106 obtained with HDS, PFS, and FIES. k2-106ab.dat contains the absolute radial velocity measurements of K2-106 obtained with HARPS and HARPS-N. (2 data files).

  20. Total uncertainty of low velocity thermal anemometers for measurement of indoor air movements

    DEFF Research Database (Denmark)

    Jørgensen, F.; Popiolek, Z.; Melikov, Arsen Krikor

    2004-01-01

    For a specific thermal anemometer with omnidirectional velocity sensor the expanded total uncertainty in measured mean velocity Û(Vmean) and the expanded total uncertainty in measured turbulence intensity Û(Tu) due to different error sources are estimated. The values are based on a previously dev...

  1. A Raman anemometer for component-selective velocity measurements of particles in a flow

    NARCIS (Netherlands)

    Florisson, O.; de Mul, F.F.M.; de Winter, H.G.

    1981-01-01

    An anemometer for the measurement of the velocity of particles of different components in a flow, separate and apart from that of the flow itself, is described. As a component-selective mechanism Raman scattering is used. The velocity is measured by relating the autocorrelated scattering signal to

  2. Functional analysis of third ventriculostomy patency with phase-contrast MRI velocity measurements

    International Nuclear Information System (INIS)

    Lev, S.; Bhadelia, R.A.; Estin, D.; Heilman, C.B.; Wolpert, S.M.

    1997-01-01

    Our purpose was to explore the utility of cine phase-contrast MRI velocity measurements in determining the functional status of third ventriculostomies, and to correlate the quantitative velocity data with clinical follow-up. We examined six patients with third ventriculostomies and 12 normal subjects by phase-contrast MRI. The maximum craniocaudal to maximum caudocranial velocity range was measured at regions of interest near the third ventricular floor, and in cerebrospinal fluid anterior to the upper pons and spinal cord on midline sagittal images. Ratios of the velocities of both the third ventricle and prepontine space to the space anterior to the spinal cord were obtained. The velocities near the third ventricular floor and in the pontine cistern were significantly higher in patients than in normal subjects, but the velocity anterior to the spinal cord was similar between the groups. The velocity ratios, used to normalize individual differences, were also higher in patients than in controls. Two patients had lower velocity ratios than their fellows at the third ventricular floor and in the pontine cistern; one required a shunt 11 months later, while in the other, who had a third ventricular/thalamic tumor, the lower values probably reflect distortion of the third ventricular floor. We conclude that phase-contrast MR velocity measurements, specifically the velocity ratio between the high pontine cistern and the space anterior to the spinal cord, can help determine the functional status of third ventriculostomies. (orig.)

  3. Winds and temperatures of the Arctic middle atmosphere during January measured by Doppler lidar

    Science.gov (United States)

    Hildebrand, Jens; Baumgarten, Gerd; Fiedler, Jens; Lübken, Franz-Josef

    2017-11-01

    We present an extensive data set of simultaneous temperature and wind measurements in the Arctic middle atmosphere. It consists of more than 300 h of Doppler Rayleigh lidar observations obtained during three January seasons (2012, 2014, and 2015) and covers the altitude range from 30 km up to about 85 km. The data set reveals large year-to-year variations in monthly mean temperatures and winds, which in 2012 are affected by a sudden stratospheric warming. The temporal evolution of winds and temperatures after that warming are studied over a period of 2 weeks, showing an elevated stratopause and the reformation of the polar vortex. The monthly mean temperatures and winds are compared to data extracted from the Integrated Forecast System of the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Horizontal Wind Model (HWM07). Lidar and ECMWF data show good agreement of mean zonal and meridional winds below ≈ 55 km altitude, but we also find mean temperature, zonal wind, and meridional wind differences of up to 20 K, 20 m s-1, and 5 m s-1, respectively. Differences between lidar observations and HWM07 data are up to 30 m s-1. From the fluctuations of temperatures and winds within single nights we extract the potential and kinetic gravity wave energy density (GWED) per unit mass. It shows that the kinetic GWED is typically 5 to 10 times larger than the potential GWED, the total GWED increases with altitude with a scale height of ≈ 16 km. Since temporal fluctuations of winds and temperatures are underestimated in ECMWF, the total GWED is underestimated as well by a factor of 3-10 above 50 km altitude. Similarly, we estimate the energy density per unit mass for large-scale waves (LWED) from the fluctuations of nightly mean temperatures and winds. The total LWED is roughly constant with altitude. The ratio of kinetic to potential LWED varies with altitude over 2 orders of magnitude. LWEDs from ECMWF data show results similar to the lidar data. From the

  4. Line ORVIS particle velocity measurements on the laser-driven miniflyer apparatus

    International Nuclear Information System (INIS)

    Gehr, R.J.; Bucholtz, S.M.; Rupp, T.D.; Robbins, D.L.; Stahl, D.B.; Sheffield, S.A.

    2004-01-01

    A line optically-recording velocity interferometer system (ORVIS) was used to measure laser-driven flyer plates impacting windows of various materials. Since the particle velocity can be measured along a line, half the line measured the acceleration of the flyer plate as well as the effect of the impact on the window. The other half of the line measured the jump in particle velocity upon impact with the window because the window was mirrored on that half. This provided information about the flyer velocity and two independent measurements of the interface particle velocity resulting from the flyer impact. Hugoniot data for copper flyers were obtained. In addition, the flatness of the flyer plate during its acceleration and the effect of this flatness on the Hugoniot data obtained are discussed

  5. Doppler-shift proton fraction measurement on a CW proton injector

    International Nuclear Information System (INIS)

    Kamperschroer, J.H.; Sherman, J.D.; Zaugg, T.J.; Arvin, A.H.; Bolt, A.S.; Richards, M.C.

    1998-01-01

    A spectrometer/Optical Multi-channel Analyzer has been used to measure the proton fraction of the cw proton injector developed for the Accelerator Production of Tritium (APT) and the Low Energy Demonstration Accelerator (LEDA) at Los Alamos. This technique, pioneered by the Lawrence Berkeley National Laboratory (LBNL), was subsequently adopted by the international fusion community as the standard for determining the extracted ion fractions of neutral beam injectors. Proton fractions up to 95 ± 3% have been measured on the LEDA injector. These values are in good agreement with results obtained by magnetically sweeping the ion beam, collimated by a slit, across a Faraday cup. Since the velocity distribution of each beam species is measured, it also can be used to determine beam divergence. While divergence has not yet been ascertained due to the wide slit widths in use, non-Gaussian distributions have been observed during operation above the design-matched perveance. An additional feature is that the presence of extracted water ions can be observed. During ion source conditioning at 75 kV, an extracted water fraction > 30% was briefly observed

  6. A Measuring Method About the Bullet Velocity in Electromagnetic Rail Gun

    Directory of Open Access Journals (Sweden)

    Jianming LIU

    2014-02-01

    Full Text Available The operating principle of electromagnetic rail gun by store capacitor was analyzed. A simulation model about the bullet velocity in the electromagnetic rail gun was built. The results of computer simulation experiment showed the relationships between the bullet velocity and the capacitor charging voltage and the pellet mass. By ten coil targets, a new kind of measuring method for the bullet velocity in electromagnetic rail gun was presented. The results of the actual experiment were analyzed. The improving method for measuring bullet velocity was put forward.

  7. Measurement of flow velocity fields in small vessel-mimic phantoms and vessels of small animals using micro ultrasonic particle image velocimetry (micro-EPIV).

    Science.gov (United States)

    Qian, Ming; Niu, Lili; Wang, Yanping; Jiang, Bo; Jin, Qiaofeng; Jiang, Chunxiang; Zheng, Hairong

    2010-10-21

    Determining a multidimensional velocity field within microscale opaque fluid flows is needed in areas such as microfluidic devices, biofluid mechanics and hemodynamics research in animal studies. The ultrasonic particle image velocimetry (EchoPIV) technique is appropriate for measuring opaque flows by taking advantage of PIV and B-mode ultrasound contrast imaging. However, the use of clinical ultrasound systems for imaging flows in small structures or animals has limitations associated with spatial resolution. This paper reports on the development of a high-resolution EchoPIV technique (termed as micro-EPIV) and its application in measuring flows in small vessel-mimic phantoms and vessels of small animals. Phantom experiments demonstrate the validity of the technique, providing velocity estimates within 4.1% of the analytically derived values with regard to the flows in a small straight vessel-mimic phantom, and velocity estimates within 5.9% of the computationally simulated values with regard to the flows in a small stenotic vessel-mimic phantom. Animal studies concerning arterial and venous flows of living rats and rabbits show that the micro-EPIV-measured peak velocities within several cardiac cycles are about 25% below the values measured by the ultrasonic spectral Doppler technique. The micro-EPIV technique is able to effectively measure the flow fields within microscale opaque fluid flows.

  8. Novel Doppler laser radar for diagnostics in fusion reactors

    Science.gov (United States)

    Menon, Madhavan; Slotwinski, Anthony

    2004-10-01

    We describe the development of a novel Doppler laser radar (DOLAR) for remote measurement of flow velocity (0-10 m/s) and film thickness of liquid metal walls, currently being studied for their superior heat handling and self-healing characteristics. Small fluctuations in flow velocity(˜mm/s) and flow thickness (˜50 μm) that may arise during plasma discharges can also be measured. The DOLAR is also designed for non intrusive mapping of features of plasma-facing solid surfaces with very high precision (˜50 μm). It can also measure the motion of structural components of a fusion reactor during plasma discharges and during plasma disruptions. The device utilizes frequency modulation laser radar principles for precision range measurements. Compensation of Doppler frequency shift is used to measure flow velocity. The DOLAR probe head is designed with acousto-optic and piezoelectric devices for operation in the harsh fusion environment.

  9. Comparison between a newly developed PC-based Doppler ...

    African Journals Online (AJOL)

    Objectives. To determine the accuracy of the resistance index (RI) of flow velocity waveforms of the umbilical artery measured using a newly developed PC-based continuous wave Doppler device (Umbiflow) with regard to systematic and random variations when compared with a commercial standard (Vasoflow). Design.

  10. Doppler time-of-flight imaging

    KAUST Repository

    Heidrich, Wolfgang

    2017-02-16

    Systems and methods for imaging object velocity are provided. In an embodiment, at least one Time-of-Flight camera is used to capture a signal representative of an object in motion over an exposure time. Illumination and modulation frequency of the captured motion are coded within the exposure time. A change of illumination frequency is mapped to measured pixel intensities of the captured motion within the exposure time, and information about a Doppler shift in the illumination frequency is extracted to obtain a measurement of instantaneous per pixel velocity of the object in motion. The radial velocity information of the object in motion can be simultaneously captured for each pixel captured within the exposure time. In one or more aspects, the illumination frequency can be coded orthogonal to the modulation frequency of the captured motion. The change of illumination frequency can correspond to radial object velocity.

  11. Effect of Doppler Radial Velocity Data Assimilation on the Simulation of a Typhoon Approaching Taiwan: A Case Study of Typhoon Aere (2004

    Directory of Open Access Journals (Sweden)

    Hsin-Hung Lin

    2011-01-01

    Full Text Available Compared to conventional data, radar observations have an advantage of high spatial and temporal resolutions, and Doppler radars are capable of capturing detailed characteristics of flow fields, including typhoon circulation. In this study, the possible improvement of short-term typhoon predictions near Taiwan, particularly with regard to related rainfall forecasts over the mountainous island, using Doppler radial wind observations is explored. The case of Typhoon Aere (2004 was chosen for study, and a series of experiments were carried out using the Penn State University/National Center for Atmospheric Research (PSU/NCAR Mesoscale Model Version 5 (MM5 with its three-dimensional variational (3D-VAR data assimilation system.

  12. Laser transit anemometer measurements of a JANNAF nozzle base velocity flow field

    Science.gov (United States)

    Hunter, William W., Jr.; Russ, C. E., Jr.; Clemmons, J. I., Jr.

    1990-01-01

    Velocity flow fields of a nozzle jet exhausting into a supersonic flow were surveyed. The measurements were obtained with a laser transit anemometer (LTA) system in the time domain with a correlation instrument. The LTA data is transformed into the velocity domain to remove the error that occurs when the data is analyzed in the time domain. The final data is shown in velocity vector plots for positions upstream, downstream, and in the exhaust plane of the jet nozzle.

  13. Effects of various factors on Doppler ultrasonographic measurements of radial and coccygeal arterial blood pressure in privately owned, conscious cats.

    Science.gov (United States)

    Whittemore, Jacqueline C; Nystrom, Michael R; Mawby, Dianne I

    2017-04-01

    OBJECTIVE To assess the effects of age, body condition score (BCS), and muscle condition score (MCS) on radial and coccygeal systolic arterial blood pressure (SAP) in cats. DESIGN Prospective randomized trial. ANIMALS 66 privately owned cats enrolled between May and December 2010. PROCEDURES BCS and MCS of cats were assessed by 2 investigators; SAP was measured via Doppler ultrasonic flow detector, with cats positioned in right lateral or sternal recumbency for measurements at the radial or coccygeal artery, respectively, with order of site randomized. Associations among variables were assessed through correlation coefficients, partial correlation coefficients, and ANCOVA. RESULTS Interrater reliability for BCS and MCS assessment was high (correlation coefficients, 0.95 and 0.83, respectively). No significant effect was identified for order of SAP measurement sites. Coccygeal and radial SAP were positively correlated (ρ = 0.45). The median difference in coccygeal versus radial SAP was 19 mm Hg, but differences were not consistently positive or negative. Radial SAP was positively correlated with age (ρ = 0.48) and negatively correlated with MCS (ρ = -0.30). On the basis of the correlation analysis, the association between radial SAP and MCS reflected the confounding influence of age. Coccygeal SAP was not significantly correlated with age, BCS, or MCS. CONCLUSIONS AND CLINICAL RELEVANCE Use of the coccygeal artery is recommended to reduce the confounding effects of age and sarcopenia on Doppler ultrasonographic SAP measurements in cats. Additionally, monitoring for changes in MCS is recommended for cats undergoing serial SAP measurement.

  14. Velocity Deficits in the Wake of Model Lemon Shark Dorsal Fins Measured with Particle Image Velocimetry

    Science.gov (United States)

    Terry, K. N.; Turner, V.; Hackett, E.

    2017-12-01

    Aquatic animals' morphology provides inspiration for human technological developments, as their bodies have evolved and become adapted for efficient swimming. Lemon sharks exhibit a uniquely large second dorsal fin that is nearly the same size as the first fin, the hydrodynamic role of which is unknown. This experimental study looks at the drag forces on a scale model of the Lemon shark's unique two-fin configuration in comparison to drag forces on a more typical one-fin configuration. The experiments were performed in a recirculating water flume, where the wakes behind the scale models are measured using particle image velocimetry. The experiments are performed at three different flow speeds for both fin configurations. The measured instantaneous 2D distributions of the streamwise and wall-normal velocity components are ensemble averaged to generate streamwise velocity vertical profiles. In addition, velocity deficit profiles are computed from the difference between these mean streamwise velocity profiles and the free stream velocity, which is computed based on measured flow rates during the experiments. Results show that the mean velocities behind the fin and near the fin tip are smallest and increase as the streamwise distance from the fin tip increases. The magnitude of velocity deficits increases with increasing flow speed for both fin configurations, but at all flow speeds, the two-fin configurations generate larger velocity deficits than the one-fin configurations. Because the velocity deficit is directly proportional to the drag force, these results suggest that the two-fin configuration produces more drag.

  15. High Precision UTDR Measurements by Sonic Velocity Compensation with Reference Transducer

    Directory of Open Access Journals (Sweden)

    Sam Stade

    2014-07-01

    Full Text Available An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol’skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 µm, while using the calculated sonic velocity the standard deviations were 21–39 µm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol’skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements.

  16. Estimation of clamping force in high-tension bolts through ultrasonic velocity measurement.

    Science.gov (United States)

    Jhang, Kyung-Young; Quan, Hai-Hua; Ha, Job; Kim, Noh-Yu

    2006-12-22

    The estimation of clamping force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating clamping force in high-tension bolts.

  17. Absolute measurement of the Hugoniot and sound velocity of liquid copper at multimegabar pressures

    Science.gov (United States)

    McCoy, Chad A.; Knudson, Marcus D.; Root, Seth

    2017-11-01

    Measurement of the Hugoniot and sound velocity provides information on the bulk modulus and Grüneisen parameter of a material at extreme conditions. The capability to launch multilayered (copper/aluminum) flyer plates at velocities in excess of 20 km/s with the Sandia Z accelerator has enabled high-precision sound-velocity measurements at previously inaccessible pressures. For these experiments, the sound velocity of the copper flyer must be accurately known in the multi-Mbar regime. Here we describe the development of copper as an absolutely calibrated sound-velocity standard for high-precision measurements at pressures in excess of 400 GPa. Using multilayered flyer plates, we performed absolute measurements of the Hugoniot and sound velocity of copper for pressures from 500 to 1200 GPa. These measurements enabled the determination of the Grüneisen parameter for dense liquid copper, clearly showing a density dependence above the melt transition. Combined with earlier data at lower pressures, these results constrain the sound velocity as a function of pressure, enabling the use of copper as a Hugoniot and sound-velocity standard for pressures up to 1200 GPa.

  18. Apparatus and method for noninvasive particle detection using doppler spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N.

    2016-05-31

    An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

  19. A simple measuring technique of surface flow velocity to analyze the behavior of velocity fields in hydraulic engineering applications.

    Science.gov (United States)

    Tellez, Jackson; Gomez, Manuel; Russo, Beniamino; Redondo, Jose M.

    2015-04-01

    An important achievement in hydraulic engineering is the proposal and development of new techniques for the measurement of field velocities in hydraulic problems. The technological advances in digital cameras with high resolution and high speed found in the market, and the advances in digital image processing techniques now provides a tremendous potential to measure and study the behavior of the water surface flows. This technique was applied at the Laboratory of Hydraulics at the Technical University of Catalonia - Barcelona Tech to study the 2D velocity fields in the vicinity of a grate inlet. We used a platform to test grate inlets capacity with dimensions of 5.5 m long and 4 m wide allowing a zone of useful study of 5.5m x 3m, where the width is similar of the urban road lane. The platform allows you to modify the longitudinal slopes from 0% to 10% and transversal slope from 0% to 4%. Flow rates can arrive to 200 l/s. In addition a high resolution camera with 1280 x 1024 pixels resolution with maximum speed of 488 frames per second was used. A novel technique using particle image velocimetry to measure surface flow velocities has been developed and validated with the experimental data from the grate inlets capacity. In this case, the proposed methodology can become a useful tools to understand the velocity fields of the flow approaching the inlet where the traditional measuring equipment have serious problems and limitations. References DigiFlow User Guide. (2012), (June). Russo, B., Gómez, M., & Tellez, J. (2013). Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates. Journal of Irrigation and Drainage Engineering, 139(10), 864-871. doi:10.1061/(ASCE)IR.1943-4774.0000625 Teresa Vila (1), Jackson Tellez (1), Jesus Maria Sanchez (2), Laura Sotillos (1), Margarita Diez (3, 1), and J., & (1), M. R. (2014). Diffusion in fractal wakes and convective thermoelectric flows. Geophysical Research Abstracts - EGU General Assembly 2014

  20. Comparison of ankle-brachial index measured by an automated oscillometric apparatus with that by standard Doppler technique in vascular patients

    DEFF Research Database (Denmark)

    Korno, M.; Eldrup, N.; Sillesen, H.

    2009-01-01

    was calculated twice using both the methods on both legs. MATERIALS AND METHODS: We tested the automated oscillometric blood pressure device, CASMED 740, for measuring ankle and arm blood pressure and compared it with the current gold standard, the hand-held Doppler technique, by the Bland-Altman analysis....... RESULTS: Using the Doppler-derived ABI as the gold standard, the sensitivity and specificity of the oscillometric method for determining an ABI Udgivelsesdato: 2009/11...

  1. Continuous amorphization of Cu-Zr studied by positron lifetime and two-dimensional Doppler broadening measurements

    International Nuclear Information System (INIS)

    Puff, W.; Rabitsch, H.; Wuerschum, R.; Wilde, G.

    2007-01-01

    Positron lifetime and 2-dimensional Doppler broadening measurements were used to study the amorphization of Cu 60 Zr 40 induced by consecutive folding and rolling. In an intermediate state of folding and rolling cycles a complex microstructure evolves with structural free volumes exhibiting a local environment with enhanced Zr content. In the fully amorphous state after 80 cycles, free volumes of the size of a few missing atoms occur which is contrast to amorphous alloys prepared by melt-spinning. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Low-temperature positron lifetime and Doppler-broadening measurements for single-crystal nickel oxide containing cation vacancies

    International Nuclear Information System (INIS)

    Waber, J.T.; Snead, C.L. Jr.; Lynn, K.G.

    1985-01-01

    Lifetime and Doppler-broadening measurements for positron annihilation in substoichiometric nickelous oxide have been made concomitantly from liquid-helium to room temperature. The concentration of cation vacancies is readily controlled by altering the ambient oxygen pressure while annealing the crystals at 1673 0 K. It was found that neither of the three lifetimes observed or their relative intensities varied significantly with the oxygen pressure, and the bulk rate only increased slightly when the specimen was cooled from room to liquid-helium temperatures. These results are interpreted as indicating that some of the positrons are trapped by the existing cation vacancies and a smaller fraction by vacancy clusters

  3. Influence of recent exercise and skin temperature on ultrasound Doppler measurements in patients with rheumatoid arthritis - an intervention study

    DEFF Research Database (Denmark)

    Ellegaard, Karen; Torp-Pedersen, Søren; Henriksen, Marius

    2009-01-01

    separate days. The interventions were (i) isometric exercise of the muscles of the hand and forearm, (ii) heating and (iii) cooling of the hand. The amount of Doppler in the wrist joint was quantified by measuring the percentage of colour in the synovium-the colour fraction (CF). The CF values estimated.......78-1.33 percentage points. The other interventions did not affect the CF significantly, with P-values of 0.65 and 0.59 in the heating intervention and 0.49 in the exercise intervention. CONCLUSIONS: Cooling of the hand should, if possible, be avoided before a USD examination of the wrist in patients with RA, because...

  4. Temperature and velocity measurement fields of fluids using a schlieren system.

    Science.gov (United States)

    Martínez-González, Adrian; Guerrero-Viramontes, J A; Moreno-Hernández, David

    2012-06-01

    This paper proposes a combined method for two-dimensional temperature and velocity measurements in liquid and gas flow using a schlieren system. Temperature measurements are made by relating the intensity level of each pixel in a schlieren image to the corresponding knife-edge position measured at the exit focal plane of the schlieren system. The same schlieren images were also used to measure the velocity of the fluid flow. The measurement is made by using particle image velocimetry (PIV). The PIV software used in this work analyzes motion between consecutive schlieren frames to obtain velocity fields. The proposed technique was applied to measure the temperature and velocity fields in the natural convection of water provoked by a heated rectangular plate.

  5. Non-collinear wave mixing for a bulk wave phase velocity measurement in an isotropic solid

    NARCIS (Netherlands)

    Demcenko, A.

    2013-01-01

    A measurement method is presented to estimate the bulk wave phase velocity in an isotropic solid when longitudinal or shear wave velocity is known. This method is based on the non-collinear plane wave interaction theory and it does not need to estimate the phase time-of-flight and wave propagation

  6. Measuring of Settling Velocity of Fine Sediment Using a Recirculated Settling Column

    DEFF Research Database (Denmark)

    Johansen, Claus; Larsen, Torben

    1998-01-01

    The paper describes a new experimental method for the measurement of the settling velocity of fine sediments. The method includes determination of the influence of turbulence and concentration. The paper also illustrates the method by giving results of the settling velocity of kaolinite for varying...

  7. Measurement of Settling Velocity of Fine Sediment using a Recirculated Settling Column

    DEFF Research Database (Denmark)

    Johansen, C.; Larsen, Torben

    1997-01-01

    The paper describes a new experimental method for the measurement of the settling velocity of fine sediments. The method includes determination of the influence of turbulence and concentration. The paper also illustrates the method by giving results of the settling velocity of kaolinite for varying...

  8. Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are…

  9. Relationship between tissue Doppler measurements of left ventricular diastolic function and silent brain infarction in patients with non-valvular atrial fibrillation.

    Science.gov (United States)

    Ishikawa, Sera; Sugioka, Kenichi; Sakamoto, Shinichi; Fujita, Suwako; Ito, Asahiro; Norioka, Naoki; Iwata, Shinichi; Nakagawa, Masashi; Takagi, Masahiko; Miki, Yukio; Ueda, Makiko; Yoshiyama, Minoru

    2017-11-01

    Left ventricular (LV) diastolic function assessed by tissue Doppler imaging (TDI) is reported to be associated with left atrial (LA) blood stasis in patients with non-valvular atrial fibrillation (AF). This study aimed to evaluate the relationship of diastolic TDI parameters with silent brain infarction (SBI) on brain magnetic resonance imaging (MRI), and in turn the risks of subsequent stroke or dementia, in non-valvular AF patients. The study population consisted of 171 neurologically asymptomatic patients with non-valvular AF who underwent transoesophageal echocardiography (TOE) (128 men; mean age, 63 ± 11 years). We measured diastolic TDI parameters by transthoracic echocardiography, and also screened for SBI employing brain MRI. Early transmitral flow velocity (E) and mitral annular velocity by TDI (e') were measured, and E/e' ratios were calculated. An increased tertile of the E/e' ratio was significantly related to high prevalences of LA abnormalities detected by TOE (32% vs. 12% vs. 9%; P =0.002) and SBI on brain MRI (46% vs. 23% vs. 14%; P chronic kidney disease, and CHA2DS2-VASc score ≥2, the E/e' ratio ≥12.4 was found to be an independent predictor of the presence of SBI (OR 3.98, 95% CI 1.74-9.07; P = 0.001). Impaired LV diastolic function evaluated by increased E/e' ratio was closely associated with the presence of SBI independent of CHA2DS2-VASc score. TDI measurements are non-invasive and useful for risk stratification of the early stage of cerebral damages in patients with non-valvular AF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions, please email: journals.permissions@oup.com.

  10. Measurements of aerosol particle dry deposition velocity using the relaxed eddy accumulation technique

    OpenAIRE

    Grönholm, Tiia; Aalto, Pasi P.; Hiltunen, Veijo; Rannik, Üllar; Rinne, Janne; Laakso, Lauri; Hyvönen, Saara; Vesala, Timo; Kulmala, Markku

    2011-01-01

    The continuous measurements of aerosol particle deposition velocity have been performed from January 2004 to January 2005 using a REA technique with dynamic deadband. We measured aerosol particle deposition velocity in the size range of 10–150 nanometer with 5–10 nanometer steps using differential mobility analyser for sizing. We were able to measure two size classes simultaneously. One size class was changed at one month intervals, another we kept constant at 30 nm to investigate the effect ...

  11. Evaluation of StereoPIV Measurement of Droplet Velocity in an Effervescent Spray

    Directory of Open Access Journals (Sweden)

    Sina Ghaemi

    2010-06-01

    Full Text Available Particle image velocimetry (PIV is a well known technique for measuring the instantaneous velocity field of flows. However, error may be introduced when measuring the velocity field of sprays using this technique when the spray droplets are used as the seed particles. In this study, the effect of droplet number density, droplet velocity profile, and droplet size distribution of a spray produced by an effervescent atomizer on velocity measurement using a StereoPIV has been investigated. A shadowgraph-particle tracking velocimetry (S-PTV system provided measurement of droplet size and velocity for comparison. This investigation demonstrated that the StereoPIV under-estimates velocity at near-field dense spray region where measurement accuracy is limited by multi-scattering of the laser sheet. In the dilute far-field region of the spray, StereoPIV measurement is mostly in agreement with velocity of the droplet size-class which is close to the mean diameter based on droplet number frequency times droplet cross sectional area.

  12. Near-field acoustic holography with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of the particle velocity has notable potential in NAH, and furthermore, combined measurement of sound pressure and particle velocity opens a new range of possibilities that are examined in this study. On this basis, sound field separation methods have been studied, and a new measurement principle based on double...... layer measurements of the particle velocity has been proposed. Also, the relation between near-field and far-field radiation from sound sources has been examined using the concept of the supersonic intensity. The calculation of this quantity has been extended to other holographic methods, and studied...

  13. Influence of timing algorithm on brachialankle pulse wave velocity measurement.

    Science.gov (United States)

    Sun, Xin; Li, Ke; Ren, Hongwei; Li, Peng; Wang, Xinpei; Liu, Changchun

    2014-01-01

    The baPWV measurement is a non-invasive and convenient technique in an assessment of arterial stiffness. Despite its widespread application, the influence of different timing algorithms is still unclear. The present study was conducted to investigate the influence of six timing algorithms (MIN, MAX, D1, D2, MDP and INS) on the baPWV measurement and to evaluate the performance of them. Forty-five CAD patients and fifty-five healthy subjects were recruited in this study. A PVR acquisition apparatus was built up for baPWV measurement. The baPWV and other related parameters were calculated separately by the six timing algorithms. The influence and performance of the six algorithms was analyzed. The six timing algorithms generate significantly different baPWV values (left: F=29.036, Pvalue (≥ 18.6%) than the other methods, while the INS has the lowest CV value (≤ 2.7%). On the performance of classification, the INS produces the highest AUC values (left: 0.854; right: 0.872). The MIN and D2 also have a passable performance (AUC > 0.8). The choice of timing algorithm affects baPWV values and the quality of measurement. The INS method is recommended for baPWV measurement.

  14. Photon trajectories, anomalous velocities and weak measurements: a classical interpretation

    International Nuclear Information System (INIS)

    Bliokh, Konstantin Y; Kofman, Abraham G; Nori, Franco; Bekshaev, Aleksandr Y

    2013-01-01

    Recently, Kocsis et al (2011 Science 332 1170) reported the observation of ‘average trajectories of single photons’ in a two-slit interference experiment. This was possible by using the quantum weak-measurement method, which implies averaging over many events, i.e. in fact, a multi-photon limit of classical linear optics. We give a classical-optics interpretation of this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum and show that their measurements have been realized in classical optics using small-probe particles. We also examine the appearance of ‘anomalous’ values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and find examples of photon trajectories and anomalous-momentum measurements in various optical experiments. (paper)

  15. Evaluation of a new high power, wide separation laser Doppler probe: potential measurement of deeper tissue blood flow.

    Science.gov (United States)

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    2009-09-01

    To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissues in humans. Monte Carlo modeling was used to predict depths of light scattering in skin with each probe, geometry. Experimentally, forearm blood flow was measured at rest and during local warming of the skin surface and post occlusion reactive hyperaemia (PORH). Laser Doppler blood flux (LDF) and the power spectral density of its component frequency intervals, were compared. Monte Carlo modeling indicated that while the majority of wide probe LD signal derives from deeper tissue, a significant portion is from superficial (dermal) tissue (and vice versa for standard probe). Perturbation of local blood flow differentially increased LDF and spectral power as measured by the two probes, with the standard skin probe showing a significantly greater response to local skin warming (p<0.01). These differences support our hypothesis that the wide probe is recording predominantly blood flux within the vasculature of sub-dermal tissue. This is in agreement with Monte Carlo simulation.

  16. Assessment of right ventricular systolic function by tissue Doppler echocardiography

    DEFF Research Database (Denmark)

    Kjærgaard, Jesper

    2012-01-01

    This thesis summarizes a series of studies performed in order to assess the clinical usefulness of a novel echocardiographic technology that allows non-invasive assessment of regional right ventricular myocardial velocities and deformation: tissue Doppler echocardiography. While the technology...... and pharmacological pulmonary vasodilatation is established in normal subjects. The diagnostic and prognostic importance of adding tissue Doppler echocardiography to conventional echocardiographic and clinical parameters was evaluated in studies on patients with diseases associated with different modes of impact...... on right ventricular hemodynamics: pulmonary embolism, Arrhythmogenic right ventricular cardiomyopathy and pulmonary regurgitation, the latter in an animal model. The conclusions of the thesis are: Color tissue Doppler echocardiography accurately measures velocities, SR and strain in vitro. No systematic...

  17. Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment

    Science.gov (United States)

    Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E.

    2014-01-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the other at torso level is necessary. An excellent absolute agreement with intraclass correlation coefficients of 0.97 was found for step time estimation with the foot level radar. For walking speed, although both radars show excellent consistency they all have a system offset compared to the ground truth due to walking direction with respect to the radar beam. The torso level radar has a better performance (9% offset on average) in the speed estimation compared to the foot level radar (13%–18% offset). Quantitative analysis has been performed to compute the angles causing the systematic error. These lab results demonstrate the capability of the system to be used as a daily gait assessment tool in home environments, useful for fall risk assessment and other health care applications. The system is currently being tested in an unstructured home environment. PMID:24771566

  18. Measurement of longitudinal and rayleigh wave velocities by advanced one-sided technique in concrete

    International Nuclear Information System (INIS)

    Lee, Joon Hyun; Song, Won Joon; Popovics, J. S.; Achenbach, J. D.

    1997-01-01

    A new procedure for the advanced one-sided measurement of longitudinal wave and surface wave velocities in concrete is presented in this paper. Stress waves are generated in a consistent fashion with a DC solenoid. Two piezoelectric accelerometers are mounted on the surface of a specimen as receivers. Stress waves propagate along the surface of the specimen and are detected by the receivers. In order to reduce the large incoherent noise levels of the signals, signals are collected and manipulated by a computer program for each velocity measurement. For a known distance between the two receivers and using the measured flight times, the velocities of the longitudinal wave and the surface wave are measured. The velocities of the longitudinal wave determined by this method are compared with those measured by conventional methods on concrete, PMMA and steel.

  19. ASSESSMENT OF LEFT VENTRICULAR FUNCTION USING TISSUE DOPPLER IMAGING

    Directory of Open Access Journals (Sweden)

    Martin Tretjak

    2004-09-01

    Full Text Available Background. Objective evidence of cardiac dysfunction is one of the diagnostic criteria for heart failure. It is often hard to assess systolic function and assessing diastolic dysfunction is even harder because there are no generally accepted echocardiographic criteria. Tissue Doppler imaging (TDI enables analysis of the mitral annular descent velocity for detection of left ventricular diastolic dysfunction along the longitudinal axis.Methods. 30 patients with heart failure and 30 healthy participants were enrolled in the study. Pulsed wave tissue Doppler imaging velocities of septal and lateral mitral annulus borders were recorded in systole (Sm and early diastole (Em. Velocities in both groups were compared. The correlations between Sm velocity and LVEF and Em velocity and age were studied.Results. Patients with heart failure had significantly decreased Sm and Em velocities compared with healthy participants (5.3 ± 1.6 cm/s vs. 8.4 ± 1 cm/s, P < 0.001, for Sm velocity and 5 ± 1.4 cm/s vs. 8.7 ± 1.6 cm/s, P < 0.001, for Em velocity. The correlation between Sm velocity and LVEF in all participants was very good and highly significant (r = 0.91, P < 0.001. The Sm velocity ≥ 6.4 cm/s was 91% sensitive and 95% specific for LVEF ≥ 0.45. There was a good correlation between age and Em velocity (r = -0.84, P < 0.001. The Em velocity < 7 cm/s had a sensitivity of 90% and specificity of 97% for diagnosing heart failure.Conclusions. Pulsed wave tissue Doppler imaging of mitral annulus enables simple, fast and precise assessment of systolic and diastolic left ventricular function. It can replace some other more time consuming echocardiographic measurements.

  20. Temperature Sensitive Particle for Velocity and Temperature Measurement.

    Science.gov (United States)

    Someya, Satoshi; Okamoto, Koji; Iida, Masao

    2007-11-01

    Phosphorescence and fluorescence are often applied to measure the temperature and the concentration of oxygen. The intensity and the lifetime of phosphor depend on the temperature and the oxygen concentration, due to the quenching effect of the phosphor. The present study clarified the effects of temperature on the lifetime of phosphorescence of Porphyrins, Ru(bpy)3^2+ and the europium complex. The phosphorescence lifetime of oil solution / water solution / painted wall were measured with changing temperature and oxygen concentration. In addition, the optical property of the small particles incorporated with the europium complex was investigated in the oil/water. The lifetime was strongly affected by temperature. Then, the temperature sensitive particle (TSParticle) with metal complex was applied to measure temperature in Silicone oil (10cSt) two-dimensionally. Present study is the result of ?High speed three-dimensional direct measurement technology development for the evaluation of heat flux and flow of liquid metal? entrusted to the University of Tokyo by the Ministry of Education, Culture, Sports, Science and Technology of Japan(MEXT).

  1. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... (ICC) and limits of agreement. RESULTS: Fifteen minutes of hyperoxia was accompanied by mean reductions in arterial and venous perfusion velocities of 14% and 16%, respectively (p = 0.0080; p = 0.0019), constriction of major arteries and veins by 5.5% and 8.2%, respectively (p ...). For perfusion velocities, short-term ICCs were 0.79-0.82 and long-term ICCs were 0.06-0.11. Intersession increases in blood glucose were associated with reductions in perfusion velocities (arterial p = 0.0067; venous p = 0.018). CONCLUSION: Oxygen reactivity testing supported that motion-contrast velocimetry...

  2. Hull-Mounted Acoustic Doppler Current Profiler Data (SADCP) collected aboard the NOAA Ship NANCY FOSTER during cruise NF-10-01 and NF-10-02

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Upper ocean current velocity measurements collected with NOAA Ship NANCY FOSTER's Teledyne RD Instruments 150 kHz hull-mounted acoustic Doppler current profiler...

  3. Magnetic particle imaging for in vivo blood flow velocity measurements in mice

    Science.gov (United States)

    Kaul, Michael G.; Salamon, Johannes; Knopp, Tobias; Ittrich, Harald; Adam, Gerhard; Weller, Horst; Jung, Caroline

    2018-03-01

    Magnetic particle imaging (MPI) is a new imaging technology. It is a potential candidate to be used for angiographic purposes, to study perfusion and cell migration. The aim of this work was to measure velocities of the flowing blood in the inferior vena cava of mice, using MPI, and to evaluate it in comparison with magnetic resonance imaging (MRI). A phantom mimicking the flow within the inferior vena cava with velocities of up to 21 cm s‑1 was used for the evaluation of the applied analysis techniques. Time–density and distance–density analyses for bolus tracking were performed to calculate flow velocities. These findings were compared with the calibrated velocities set by a flow pump, and it can be concluded that velocities of up to 21 cm s‑1 can be measured by MPI. A time–density analysis using an arrival time estimation algorithm showed the best agreement with the preset velocities. In vivo measurements were performed in healthy FVB mice (n  =  10). MRI experiments were performed using phase contrast (PC) for velocity mapping. For MPI measurements, a standardized injection of a superparamagnetic iron oxide tracer was applied. In vivo MPI data were evaluated by a time–density analysis and compared to PC MRI. A Bland–Altman analysis revealed good agreement between the in vivo velocities acquired by MRI of 4.0  ±  1.5 cm s‑1 and those measured by MPI of 4.8  ±  1.1 cm s‑1. Magnetic particle imaging is a new tool with which to measure and quantify flow velocities. It is fast, radiation-free, and produces 3D images. It therefore offers the potential for vascular imaging.

  4. Speckle-based three-dimensional velocity measurement using spatial filtering velocimetry

    DEFF Research Database (Denmark)

    Iversen, Theis Faber Quist; Jakobsen, Michael Linde; Hanson, Steen Grüner

    2011-01-01

    We present an optical method for measuring the real-time three-dimensional (3D) translational velocity of a diffusely scattering rigid object observed through an imaging system. The method is based on a combination of the motion of random speckle patterns and regular fringe patterns. The speckle ...... spatial filters designed to measure the three components of the object’s translational velocity. Furthermore, experimental data are presented that demonstrate full 3D velocity measurement.......We present an optical method for measuring the real-time three-dimensional (3D) translational velocity of a diffusely scattering rigid object observed through an imaging system. The method is based on a combination of the motion of random speckle patterns and regular fringe patterns. The speckle...

  5. MEaSUREs Greenland Ice Sheet Velocity Map from InSAR Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides annual ice-sheet-wide velocity maps...

  6. MEaSUREs Greenland Ice Sheet Velocity Map from InSAR Data V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides annual ice-sheet-wide velocity maps...

  7. MEaSUREs Multi-year Greenland Ice Sheet Velocity Mosaic V001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, contains a multi-year ice-sheet-wide velocity...

  8. Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion.

    Science.gov (United States)

    Varley, Matthew C; Fairweather, Ian H; Aughey, Robert J

    2012-01-01

    In this study, we assessed the validity and reliability of 5 and 10 Hz global positioning systems (GPS) for measuring instantaneous velocity during acceleration, deceleration, and constant velocity while straight-line running. Three participants performed 80 running trials while wearing two GPS units each (5 Hz, V2.0 and 10 Hz, V4.0; MinimaxX, Catapult Innovations, Scoresby, VIC, Australia). The criterion measure used to assess GPS validity was instantaneous velocity recorded using a tripod-mounted laser. Validity was established using the standard error of the estimate (± 90% confidence limits). Reliability was determined using typical error (± 90% confidence limits, expressed as coefficient of variation) and Pearson's correlation. The 10 Hz GPS devices were two to three times more accurate than the 5 Hz devices when compared with a criterion value for instantaneous velocity during tasks completed at a range of velocities (coefficient of variation 3.1-11.3%). Similarly, the 10 Hz GPS units were up to six-fold more reliable for measuring instantaneous velocity than the 5 Hz units (coefficient of variation 1.9-6.0%). Newer GPS may provide an acceptable tool for the measurement of constant velocity, acceleration, and deceleration during straight-line running and have sufficient sensitivity for detecting changes in performance in team sport. However, researchers must account for the inherent match-to-match variation reported when using these devices.

  9. Group velocity measurement using spectral interference in near-field scanning optical microscopy

    International Nuclear Information System (INIS)

    Mills, John D.; Chaipiboonwong, Tipsuda; Brocklesby, William S.; Charlton, Martin D. B.; Netti, Caterina; Zoorob, Majd E.; Baumberg, Jeremy J.

    2006-01-01

    Near-field scanning optical microscopy provides a tool for studying the behavior of optical fields inside waveguides. In this experiment the authors measure directly the variation of group velocity between different modes of a planar slab waveguide as the modes propagate along the guide. The measurement is made using the spectral interference between pulses propagating inside the waveguide with different group velocities, collected using a near-field scanning optical microscope at different points down the guide and spectrally resolved. The results are compared to models of group velocities in simple guides

  10. Measurements of the propagation velocity and shape of the luminous front in a coaxial accelerator

    International Nuclear Information System (INIS)

    Ionescu Bujor, T.; Tsois, N.; Muscalu, G.

    1977-01-01

    The results of the measurements on the propagation velocity of the luminous front and the shape of the plasma sheath produced in a coaxial accelerator working in hydrogen (2.0 Torr) at condenser voltages between 15 and 17 kV are reported. The arrival times of the luminous and shock fronts, determined from hydrogen continuum emission and laser beam deflection measurements, respectively, have been used to estimate the propagation velocities and plasma sheath spatial distribution (geometrical shape). Velocities ranging from 10 to 20 cm/μsec and a non-planar geometrical shape resulted. (author)

  11. Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Greve, Sara V; Blicher, Marie K; Kruger, Ruan

    2016-01-01

    BACKGROUND: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood...... pressure, and previously published equations. The aim of this study was to investigate whether ePWV could predict cardiovascular events independently of traditional cardiovascular risk factors and/or cfPWV. METHOD: cfPWV was measured and ePWV was calculated in 2366 patients from four age groups...... healthy patients, ePWV and cfPWV (per SD) added independently to SCORE in prediction of combined endpoint [hazard ratio (95%CI) = 1.38(1.09-1.76) and hazard ratio (95%CI) = 1.18(1.01-1.38)] and to FRS [hazard ratio (95%CI) = 1.33(1.06-1.66) and hazard ratio (95%CI) = 1.16(0.99-1.37)]. If healthy patients...

  12. Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Olsen, Michael; Greve, Sara; Blicher, Marie

    2016-01-01

    OBJECTIVE: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular (CV) risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood...... pressure and previously published equations. The aim of this study was to investigate whether ePWV could predict CV events independently of traditional cardiovascular risk factors and/or cfPWV. DESIGN AND METHOD: cfPWV was measured and ePWV calculated in 2366 apparently healthy subjects from four age......, ePVW and cfPWV (per standard deviation) added independently to SCORE in prediction of CEP (HR [95% CI] = 1.38[1.09-1.76] and HR [95% CI] = 1.18[1.01-1.38]) and to FRS (HR [95% CI] = 1.33[1.06-1.66] and HR [95% CI] = 1.16[0.99-1.37]). If healthy subjects with ePWV and/or cfPWV ≥ 10 m/s were...

  13. Measurement of Flow Velocity and Inference of Liquid Viscosity in a Microfluidic Channel by Fluorescence Photobleaching

    DEFF Research Database (Denmark)

    Carroll, Nick J.; Jensen, Kaare Hartvig; Parsa, Shima

    2014-01-01

    We present a simple, noninvasive method for simultaneous measurement of flow velocity and inference of liquid viscosity in a microfluidic channel. We track the dynamics of a sharp front of photobleached fluorescent dye using a confocal microscope and measure the intensity at a single point...... theological properties of the liquid. This technique provides a simple method for simultaneous elucidation of flow velocity and liquid viscosity in microchannels....

  14. Experimental study on thermal-hydraulic for thermal striping phenomena. Results of temperature and velocity measurement among parallel triple jets

    International Nuclear Information System (INIS)

    Miyakoshi, Hiroyuki; Kimura, Nobuyuki; Kamide, Hideki; Miyake, Yasuhiro

    2003-03-01

    A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing among jets causes thermal fatigue in structural components, is of importance for structural integrity and also reactor safety. The treasonable and safety design could be approved by taking account of decay of temperature fluctuation in fluid, during heat transfer from fluid to structure surface and thermal conduction in the structure. In this study, water experiment was performed for vertical and parallel triple jets along wall, those are cold jet in the center and hot jets on both sides. The local temperature and velocity were measured by movable thermocouples and particle image velocimetry (PIV). The both hot jets flowed leaning to the cold jet. The lean of the jets increased as the jets approached the wall. So the convective mixing region among the jets was shifted upstream near the wall. Temperature fluctuation intensity was dependent of the distance from the wall. Under isovelocity condition, prominent frequency component was observed in the power spectrum density of the temperature fluctuation at the furthest position from the wall. The power at the prominent component decreased as the jets approached the wall. Under non-isovelocity condition, on the other hand, the power spectrum density of temperature fluctuation was independent of the distance from the wall. Comparison of the second moment between of velocity PIV and laser Doppler velocimetry showed that the PIV system had high measurement accuracy. Under non-isovelocity condition, the normal components in the second-order moments of fluctuation were smaller than those under isovelocity condition. Normal components in the second-order moments in turbulence was dependent of the distance from the wall. (author)

  15. Physical model experiment for wave field measurements by means of laser Doppler vibrometer. Measurement of three components; Laser Doppler shindokei ni yoru butsuri model jikken. Hado sanseibun no kenshutsu

    Energy Technology Data Exchange (ETDEWEB)

    Nishizawa, O.; Sato, T. [Geological Survey of Japan, Tsukuba (Japan); Lei, X. [DIA Consultant Co. Ltd., Tokyo (Japan)

    1997-05-27

    In this experiment, a beam incident from an oblique direction is reflected by a spherical lens toward the direction of incidence. When the surface of a matter is vibrated by elastic waves, the spherical lens comes into a translation motion that accompanies the vibration. It follows accordingly that the vibration on the surface of the matter may be detected by sensing the spherical lens travelling speed. Three components of the vibration may be determined if beams are focused at one spot from three directions. Detection of the S-wave component by LDV (laser Doppler vibrometer) discloses the complicated wave field in a heterogeneous material, and this physical model experiment may be utilized in various fields of study. For instance, information about problems that may surface in the field work may be collected beforehand in a physical model experiment for developing an S-wave-aided probing method. For the study of seismic wave propagation in a complicated three-dimensional ground structure, a numerical model is not enough, and a physical model experiment will be an effective method to fulfill the purpose. In the monitoring of cracks in a rock, again, not only elastic wave velocity but also waveform information collected from a physical model experiment should be fully utilized. 6 refs., 6 figs.

  16. Modelling and experimental analysis of the performance of a laser Doppler vibrometer used to measure vibrations through combustive flows

    Science.gov (United States)

    Paone, Nicola; Revel, Gian Marco

    1998-08-01

    The problem of measuring surface vibrations by a laser Doppler vibrometer operating with the measuring beam across a combustive flow is discussed, in order to assess the possibility of experimentally determining the dynamic behaviour of a burner under operating conditions. The instrument performance is analysed in terms of interfering and modifying inputs through the development of a model of the interferometer and by experimental validation of its predictions. Experiments are carried out on an unconfined CH 4 flame of a Bunsen burner and a metal surface under a known forced vibration. The laser vibrometer output is influenced by the presence of the flame: major effects are optical path length variations of the measuring arm of the interferometer and beam movements. All effects occur at the typical flame flickering frequency and cause a distorted vibration spectra and a reduced signal-to-noise ratio. Beam wandering and defocusing are documented by image acquisition.

  17. Comparison between /sup 133/Xenon washout technique and Laser Doppler flowmetry in the measurement of local vasoconstrictor effects on the microcirculation in subcutaneous tissue and skin

    Energy Technology Data Exchange (ETDEWEB)

    Kastrup, J.; Buelow, J.; Lassen, N.A.

    1987-10-01

    Changes in skin blood flow measured by Laser Doppler flowmetry and changes in subcutaneous blood flow measured by /sup 133/Xenon washout technique were compared during activation of the local sympathetic mediated veno-arteriolar vaso-constrictor reflex by lowering the area of investigation below heart level. The measurements were performed in tissue with and without sympathetic innervation. In five subjects, who all had been cervically sympathectomized for manual hyperhidrosis, the Laser Doppler and /sup 133/Xenon blood flow measurements were performed simultaneously on the sympathetically denervated forearm, and on the calf with preserved sympathetic nerve supply. The Laser Doppler method registered a 23% reduction in skin blood flow during lowering of the extremities independently of the sympathetic nerve supply to the skin. The /sup 133/Xenon method recorded a 44% decrease in blood flow in innervated and unchanged blood flow in denervated subcutaneous tissue during lowering of the extremities. Our results indicate that the Laser Doppler method and /sup 133/Xenon method are not comparable, and that the Laser Doppler method is not useful in measuring local sympathetic mediated blood flow changes.

  18. Intracranial artery velocity measurement using 4D PC MRI at 3 T: comparison with transcranial ultrasound techniques and 2D PC MRI

    International Nuclear Information System (INIS)

    Meckel, Stephan; Leitner, Lorenz; Schubert, Tilman; Bonati, Leo H.; Lyrer, Philippe; Santini, Francesco; Stalder, Aurelien F.; Markl, Michael; Wetzel, Stephan G.

    2013-01-01

    4D phase contrast MR imaging (4D PC MRI) has been introduced for spatiotemporal evaluation of intracranial hemodynamics in various cerebrovascular diseases. However, it still lacks validation with standards of reference. Our goal was to compare blood flow quantification derived from 4D PC MRI with transcranial ultrasound and 2D PC MRI. Velocity measurements within large intracranial arteries [internal carotid artery (ICA), basilar artery (BA), and middle cerebral artery (MCA)] were obtained in 20 young healthy volunteers with 4D and 2D PC MRI, transcranial Doppler sonography (TCD), and transcranial color-coded duplex sonography (TCCD). Maximum velocities at peak systole (PSV) and end diastole (EDV) were compared using regression analysis and Bland-Altman plots. Correlation of 4D PC MRI measured velocities was higher in comparison with TCD (r = 0.49-0.66) than with TCCD (0.35-0.44) and 2D PC MRI (0.52-0.60). In mid-BA and ICA C7 segment, a significant correlation was found with TCD (0.68-0.81 and 0.65-0.71, respectively). No significant correlation was found in carotid siphon. On average over all volunteers, PSVs and EDVs in MCA were minimally underestimated compared with TCD/TCCD. Minimal overestimation of velocities was found compared to TCD in mid-BA and ICA C7 segment. 4D PC MRI appears as valid alternative for intracranial velocity measurement consistent with previous reference standards, foremost with TCD. Spatiotemporal averaging effects might contribute to vessel size-dependent mild underestimation of velocities in smaller (MCA), and overestimation in larger-sized (BA and ICA) arteries, respectively. Complete spatiotemporal flow analysis may be advantageous in anatomically complex regions (e.g. carotid siphon) relative to restrictions of ultrasound techniques. (orig.)

  19. Intracranial artery velocity measurement using 4D PC MRI at 3 T: comparison with transcranial ultrasound techniques and 2D PC MRI

    Energy Technology Data Exchange (ETDEWEB)

    Meckel, Stephan [University Hospital Freiburg, Department of Neuroradiology, Freiburg (Germany); Leitner, Lorenz; Schubert, Tilman [University Hospital Basel, Institute of Radiology, Basel (Switzerland); Bonati, Leo H.; Lyrer, Philippe [University Hospital Basel, Department of Neurology, Basel (Switzerland); Santini, Francesco [University Hospital Basel, Department of Radiological Physics, Institute of Radiology, Basel (Switzerland); Stalder, Aurelien F. [Xuanwu Hospital - Capital Medical University, Department of Radiology, Beijing (China); Markl, Michael [Northwestern University Feinberg School of Medicine, Departments of Radiology and Biomedical Engineering, Chicago (United States); Wetzel, Stephan G. [Neuroradiology, Swiss Neuro Institute, Klinik Hirslanden, Zurich (Switzerland)

    2013-04-15

    4D phase contrast MR imaging (4D PC MRI) has been introduced for spatiotemporal evaluation of intracranial hemodynamics in various cerebrovascular diseases. However, it still lacks validation with standards of reference. Our goal was to compare blood flow quantification derived from 4D PC MRI with transcranial ultrasound and 2D PC MRI. Velocity measurements within large intracranial arteries [internal carotid artery (ICA), basilar artery (BA), and middle cerebral artery (MCA)] were obtained in 20 young healthy volunteers with 4D and 2D PC MRI, transcranial Doppler sonography (TCD), and transcranial color-coded duplex sonography (TCCD). Maximum velocities at peak systole (PSV) and end diastole (EDV) were compared using regression analysis and Bland-Altman plots. Correlation of 4D PC MRI measured velocities was higher in comparison with TCD (r = 0.49-0.66) than with TCCD (0.35-0.44) and 2D PC MRI (0.52-0.60). In mid-BA and ICA C7 segment, a significant correlation was found with TCD (0.68-0.81 and 0.65-0.71, respectively). No significant correlation was found in carotid siphon. On average over all volunteers, PSVs and EDVs in MCA were minimally underestimated compared with TCD/TCCD. Minimal overestimation of velocities was found compared to TCD in mid-BA and ICA C7 segment. 4D PC MRI appears as valid alternative for intracranial velocity measurement consistent with previous reference standards, foremost with TCD. Spatiotemporal averaging effects might contribute to vessel size-dependent mild underestimation of velocities in smaller (MCA), and overestimation in larger-sized (BA and ICA) arteries, respectively. Complete spatiotemporal flow analysis may be advantageous in anatomically complex regions (e.g. carotid siphon) relative to restrictions of ultrasound techniques. (orig.)

  20. Front-Crawl Instantaneous Velocity Estimation Using a Wearable Inertial Measurement Unit

    Directory of Open Access Journals (Sweden)

    Kamiar Aminian

    2012-09-01

    Full Text Available Monitoring the performance is a crucial task for elite sports during both training and competition. Velocity is the key parameter of performance in swimming, but swimming performance evaluation remains immature due to the complexities of measurements in water. The purpose of this study is to use a single inertial measurement unit (IMU to estimate front crawl velocity. Thirty swimmers, equipped with an IMU on the sacrum, each performed four different velocity trials of 25 m in ascending order. A tethered speedometer was used as the velocity measurement reference. Deployment of biomechanical constraints of front crawl locomotion and change detection framework on acceleration signal paved the way for a drift-free integration of forward acceleration using IMU to estimate the swimmers velocity. A difference of 0.6 ± 5.4 cm·s−1 on mean cycle velocity and an RMS difference of 11.3 cm·s−1 in instantaneous velocity estimation were observed between IMU and the reference. The most important contribution of the study is a new practical tool for objective evaluation of swimming performance. A single body-worn IMU provides timely feedback for coaches and sport scientists without any complicated setup or restraining the swimmer’s natural technique.

  1. S-wave velocity structures of the Taipei Basin, Taiwan, using microtremor array measurements

    Science.gov (United States)

    Huang, Huey-Chu; Wu, Cheng-Feng; Lee, Feng-Mei; Hwang, Ruey-Der

    2015-04-01

    The S-wave velocity structures of the Taipei Basin in Taiwan are investigated using the array records of microtremors at 15 sites. Dispersion curves at these sites are calculated using the frequency-wavenumber (F-K) spectrum method. The S-wave velocity structures in the Taipei Basin are then estimated by employing surface wave inversion technique. Harder strata sites have higher phase velocities than softer sites. If the S-wave velocity of the Tertiary Basement is assumed to be 1000 m/s, then the Quaternary alluvial thicknesses in the Taipei Basin are between about 100 m and 650 m. The thickness of the alluvium gradually increases from the southeast to the northwest. The inversion results are also in good agreement with well-logging data and seismic reflection studies of the Taipei Basin. The study concludes that microtremor array measurement is a useful tool for estimating S-wave velocity structure.

  2. Measurements of Sound Velocity of Diamond at the Pressure Around the Melt

    Science.gov (United States)

    Shigemori, K.; Shimizu, K.; Asakura, Y.; Hayashi, D.; Nakamoto, Y.; Kagayama, T.; Sakaiya, T.; Kondo, T.; Sumiya, H.; Irifune, T.; Kurosawa, K.; Sugita, S.; Kadono, T.; Hironaka, Y.

    2011-10-01

    We have measured the sound velocity of the diamond foils at around the melting pressures (500 - 1500 GPa). Experiments were done on GEKKO-XII glass laser system with HIPER irradiation facility. Single crystal diamond foils (Ia) of 30 ~40 μm thickness were irradiated at intensities of 0.2 - 1.5 × 1014 W/cm2. We measured the sound velocity by side-on x-ray backlighting technique. Trajectories of foil surfaces were observed by x-ray streak camera. We also measured the shock velocity by two VISARs (velocity interferometer system for any reflector), and shocked temperature by an SOP (streaked optical pyrometer) in order to determine the pressure and the temperature at around the melting. Experimental data were compared with the previous theoretical studies and the percolation theory.

  3. Prevalence and inter-relationship of different Doppler measures of dyssynchrony in patients with heart failure and prolonged QRS: a report from CARE-HF

    Directory of Open Access Journals (Sweden)

    Maru Fikru

    2009-01-01

    Full Text Available Abstract Background Cardiac resynchronisation therapy (CRT improves mortality and morbidity in heart failure patients with wide QRS. Observational studies suggest that patients having more left ventricular dyssynchrony pre-implantation obtain greater benefit on ventricular function and symptoms with CRT. Aim To provide an analysis of the prevalence and type of dyssynchrony in patients included in the CARE-HF trial. Methods 100 patients 67 (58 to 71 years were examined with echocardiography including tissue doppler imaging before receiving a CRT-pacemaker. Atrio-ventricular dyssynchrony (LVFT/RR was defined as left ventricular filling time 40 ms. Intra-ventricular (regional dyssynchrony in a 16-segment model was expressed either as a delayed longitudinal contraction (DLC during the postsystolic phase or by tissue synchronisation imaging (TSI with a predefined time-difference in systolic maximal velocities >85 ms. Results LVFT/RR was present in 34% and IVMD in 60% of patients while intra-ventricular dyssynchrony was present in 85% (DLC and 86% (TSI with a high agreement between the measures (Kappascore 0.86–1.00, indicating the methods being interchangeable. Patients with cardiomyopathy (53% were more likely to have LVFT/RR Conclusion The prevalence of intra-ventricular dyssynchrony is high in patients with heart failure, wide QRS and depressed systolic function. Most important, TSI appears to be a fast and reliable method to identify patients with intra-ventricular dyssynchrony likely to benefit from CRT.

  4. Development of a Spatially Resolving X-Ray Crystal Spectrometer (XCS) for Measurement of Ion-Temperature (Ti) and Rotation-Velocity (v) Profiles in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Hill, K W; Delgado-Aprico, L; Johnson, D; Feder, R; Beiersdorfer,; Dunn, J; Morris, K; Wang, E; Reinke, M; Podpaly, Y; Rice, J E; Barnsley, R; O' Mullane, M; Lee, S G

    2010-05-21

    Imaging XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, Fe) with ~7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a PPPL-MIT instrument on Alcator C-Mod, uses a spherically bent crystal and 2d x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. Measurement of many spatial chords permits tomographic inversion for inference of local parameters. The instrument design, predictions of performance, and results from C-Mod will be presented.

  5. Development of a laser Doppler system for the detection and monitoring of atmospheric disturbances

    Science.gov (United States)

    Jeffreys, H. B.; Bilbro, J. W.

    1975-01-01

    A Scanning Laser Doppler Velocimeter System (SLDVS) capable of detecting and monitoring atmospheric disturbances, including wake vortices of landing aircraft and vertical wind profiles in the atmosphere was developed. The SLDVS is a focused, continuous wave, CO2 system that determines the line-of-sight velocities of particles in the focal volume by measuring the Doppler shift created by these particles. At present, the SLDVS is designed to have a range coverage of approximately 2000 ft with a vertical angle coverage of approximately 60 deg. It is also designed to detect Doppler velocities of up to 200 ft/sec with a velocity resolution of approximately 1.8 ft/sec. A complete velocity spectrum is provided by the SLDVS at each point in space at which it is focused. The overall operation and performance of the system and the description of its individual components and data handling capabilities were given.

  6. TCSP ER-2 DOPPLER RADAR (EDOP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The EDOP provides vertically profiled reflectivity and Doppler velocity at aircraft nadir along the flight track. The ER-2 Doppler radar (EDOP) is an X-band (9.6...

  7. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  8. Doppler Tomography

    Science.gov (United States)

    Marsh, T. R.

    I review the method of Doppler tomography which translates binary-star line profiles taken at a series of orbital phases into a distribution of emission over the binary. I begin with a discussion of the basic principles behind Doppler tomography, including a comparison of the relative merits of maximum entropy regularisation versus filtered back-projection for implementing the inversion. Following this I discuss the issue of noise in Doppler images and possible methods for coping with it. Then I move on to look at the results of Doppler Tomography applied to cataclysmic variable stars. Outstanding successes to date are the discovery of two-arm spiral shocks in cataclysmic variable accretion discs and the probing of the stream/magnetospheric interaction in magnetic cataclysmic variable stars. Doppler tomography has also told us much about the stream/disc interaction in non-magnetic systems and the irradiation of the secondary star in all systems. The latter indirectly reveals such effects as shadowing by the accretion disc or stream. I discuss all of these and finish with some musings on possible future directions for the method. At the end I include a tabulation of Doppler maps published in refereed journals.

  9. Can intracranial pressure be measured non-invasively bedside using a two-depth Doppler-technique?

    Science.gov (United States)

    Koskinen, Lars-Owe D; Malm, Jan; Zakelis, Rolandas; Bartusis, Laimonas; Ragauskas, Arminas; Eklund, Anders

    2017-04-01

    Measurement of intracranial pressure (ICP) is necessary in many neurological and neurosurgical diseases. To avoid lumbar puncture or intracranial ICP probes, non-invasive ICP techniques are becoming popular. A recently developed technology uses two-depth Doppler to compare arterial pulsations in the intra- and extra-cranial segments of the ophthalmic artery for non-invasive estimation of ICP. The aim of this study was to investigate how well non-invasively-measured ICP and invasively-measured cerebrospinal fluid (CSF) pressure correlate. We performed multiple measurements over a wide ICP span in eighteen elderly patients with communicating hydrocephalus. As a reference, an automatic CSF infusion apparatus was connected to the lumbar space. Ringer's solution was used to create elevation to pre-defined ICP levels. Bench tests of the infusion apparatus showed a random error (95 % CI) of less than ±0.9 mmHg and a systematic error of less than ±0.5 mmHg. Reliable Doppler signals were obtained in 13 (72 %) patients. An infusion test could not be performed in one patient. Thus, twelve patients and a total of 61 paired data points were studied. The correlation between invasive and non-invasive ICP measurements was good (R = 0.74), and the 95 % limits of agreements were -1.4 ± 8.8 mmHg. The within-patient correlation varied between 0.47 and 1.00. This non-invasive technique is promising, and these results encourage further development and evaluation before the method can be recommended for use in clinical practice.

  10. Non-invasive tissue Doppler imaging pulmonary capillary wedge pressure measurement improves NT-proBNP prognostic value in heart failure.

    Science.gov (United States)

    Berni, Andrea; Cappelli, Francesco; Bitossi, Luca; Cecioni, Ilaria; Cappelli, Brunello; Toncelli, Loira; Galanti, Giorgio; Poggesi, Loredana

    2009-04-01

    The aim of the present study was to investigate whether the improvement of pulmonary capillary wedge pressure (PCWP) non-invasively assessed with tissue Doppler imaging is able to predict prognosis and cardiac-related mortality in patients with heart failure (HF), as previously demonstrated for NT-proBNP. We prospectively studied 23 patients (74 +/- 10 y; 17 M, 6 F) with acute HF. NT-proBNP and PCWP were measured at admission and discharge. NT-proBNP concentrations were determined by a chemiluminescent immunoassay kit. PCWP was assessed using the ratio of transmitral E velocity to the early diastolic mitral annulus velocity (E'), with the formula PCWP = 1.9 + 1.24 (E/E'). Patients were divided in two groups according to the clinical end-point based on cardiac death and hospital readmission for HF. After a mean follow-up of 230 days, 10 patients reached the end-point (group A), while 13 patients resulted event-free (group B). In group B, NT-proBNP values significantly decreased (3816 +/- 7424 vs. 6799 +/- 10537 pg/mL, P values was able to identify the majority of patients (77%) with an event-free survival at follow-up, whereas 70% of patients who reached the end-point had discordant changes in NT-proBNP and PCWP (chi2 = 5.06, P < 0.05). The combination of a biochemical marker such as NT-proBNP and a new indicator of LV filling pressure (E/E') allows to estimate the prognostic impact of standard medical therapy even in a small group of HF patients.

  11. Experimental and biological variation of three-dimensional transcranial Doppler measurements

    DEFF Research Database (Denmark)

    Thomsen, L L; Iversen, Helle Klingenberg

    1993-01-01

    , 24 females and 11 males (P = 0.002). When middle cerebral artery velocity was monitored, high- and low-frequency oscillations were found, with a mean frequency of 5 and 1.6/min, respectively. These variations underline the necessity of standardized conditions and very carefully matched control groups...

  12. Resolution potential of surface wave phase velocity measurements at small arrays

    Science.gov (United States)

    Bodin, Thomas; Maupin, Valérie

    2008-02-01

    The deployment of temporary arrays of broadband seismological stations over dedicated targets is common practice. Measurement of surface wave phase velocity across a small array and its depth-inversion gives us information about the structure below the array which is complementary to the information obtained from body-wave analysis. The question is however: what do we actually measure when the array is much smaller than the wave length, and how does the measured phase velocity relates to the real structure below the array? We quantify this relationship by performing a series of numerical simulations of surface wave propagation in 3-D structures and by measuring the apparent phase velocity across the array on the synthetics. A principal conclusion is that heterogeneities located outside the array can map in a complex way onto the phase velocities measured by the array. In order to minimize this effect, it is necessary to have a large number of events and to average measurements from events well-distributed in backazimuth. A second observation is that the period of the wave has a remarkably small influence on the lateral resolution of the measurement, which is dominantly controlled by the size of the array. We analyse if the artefacts created by heterogeneities can be mistaken for azimuthal variations caused by anisotropy. We also show that if the amplitude of the surface waves can be measured precisely enough, phase velocities can be corrected and the artefacts which occur due to reflections and diffractions in 3-D structures greatly reduced.

  13. A time-space synchronization of coherent Doppler scanning lidars for 3D measurements of wind fields

    DEFF Research Database (Denmark)

    Vasiljevic, Nikola

    This thesis consists of the results of a Ph.D. study that was focused on the development of the system of three time-space synchronized pulsed coherent Doppler scanning lidars, which are coordinated by a remote ’master computer’. This system has the unique capability to measure a complete three...... synchronization and time control of the emission, steering and acquisition were achieved, resulting that the complete lidar measurement process is controlled from the single hardware component. The system was formed using a novel approach, in which the master computer simultaneously coordinates the remote lidars...... through a UDP/IP and TCP/IP network by exchange of network packets. Since the size of the packets is roughly 1 kB, this approach allows an uninterrupted and fast coordination of the lidars, even in the case of mobile networks such as GSM. With this approach a maximum lag of 10 ms was observed in terms...

  14. Laser Doppler phase shifting using a high-speed digital micromirror device

    Science.gov (United States)

    Kuo, D.; Sharpe, J. P.

    2015-03-01

    Here we demonstrate the use of a binary spatial light modulator (Texas Instruments Digital Micromirror Device) to impart a phase shift to the beams of a laser Doppler velocimeter. Advantages of this approach to laser Doppler phase shifting include low cost, low power consumption, a precisely known phase-stepping frequency and the capability of working with a broad range of optical wavelengths. In the implementation shown here velocities of order 1 cm/s are measured.

  15. TEACHING PHYSICS: An experiment to demonstrate the principles and processes involved in medical Doppler ultrasound

    Science.gov (United States)

    Andrews, D. G. H.

    2000-09-01

    Doppler ultrasound is widely used in medicine for measuring blood velocity. This paper describes an experiment illustrating the principles of medical Doppler ultrasound. It is designed with A-level/undergraduate physics students in mind. Ultrasound is transmitted in air and reflected from a moving target. The return signal is processed using a series of modules, so that students can discover for themselves how each stage in the instrument works. They can also obtain a quantitative value of the speed of the target.

  16. Visual search tasks: measurement of dynamic visual lobe and relationship with display movement velocity.

    Science.gov (United States)

    Yang, Lin-Dong; Yu, Rui-Feng; Lin, Xue-Lian; Xie, Ya-Qing; Ma, Liang

    2018-02-01

    Visual lobe is a useful tool for predicting visual search performance. Up till now, no study has focused on dynamic visual lobe. This study developed a dynamic visual lobe measurement system (DVLMS) that could effectively map dynamic visual lobe and calculate visual lobe shape indices. The effects of display movement velocity on lobe shape indices were examined under four velocity conditions: 0, 4, 8 and 16 deg/s. In general, with the increase of display movement velocity, visual lobe area and perimeter became smaller, whereas lobe shape roundness, boundary smoothness, symmetry and regularity deteriorated. The elongation index was not affected by velocity. Regression analyses indicated that display movement velocity was important in determining dynamic visual lobe shape indices. Dynamic visual lobe provides another option for better understanding dynamic vision, in addition to dynamic visual acuity. Findings of this study can provide guidelines for analysing and designing dynamic visual tasks. Practitioner Summary: Dynamic visual lobe is important in reflecting the visual ability of searching for a moving target. We developed a dynamic visual lobe measurement system (DVLMS) and examined display movement velocity's effects on lobe shape. Findings revealed that velocity was a key factor affecting dynamic visual lobe shape indices.

  17. Comparison between different speckle tracking and color tissue Doppler techniques to measure global and regional myocardial deformation in children.

    Science.gov (United States)

    Koopman, Laurens P; Slorach, Cameron; Hui, Wei; Manlhiot, Cedric; McCrindle, Brian W; Friedberg, Mark K; Jaeggi, Edgar T; Mertens, Luc

    2010-09-01

    Myocardial deformation parameters obtained by speckle-tracking echocardiography (STE) and color Doppler tissue imaging (CDTI) using two different ultrasound systems and three different software packages were compared. Apical four-chamber, short-axis grayscale, and color Doppler tissue images were prospectively acquired using Vivid 7 and iE33 ultrasound systems in 34 children and then analyzed using EchoPAC and QLAB (STE) and SPEQLE (CDTI). Measurement of myocardial deformation was feasible for all three modalities. Longitudinal strain (epsilon) measurements showed the lowest intraobserver and interobserver variability (intraobserver and interobserver coefficients of variation, 9% and 8% for EchoPAC, 5% and 6% for QLAB, and 14% and 16% for SPEQLE). In addition, longitudinal epsilon had a small bias and narrow limits of agreement when comparing different techniques. The coefficients of variation of circumferential epsilon by EchoPAC and QLAB were 12% and 11% (intraobserver) and 9% and 13% (interobserver), respectively. Circumferential epsilon by STE had a small systematic bias but relatively narrow limits of agreement. The reproducibility of radial epsilon measurements using STE was low, while CDTI epsilon provided better performance (intraobserver and interobserver coefficients of variation for radial posterior epsilon, 12% and 24% for EchoPAC, 39% and 56% for QLAB, and 12% and 14% for SPEQLE). Radial epsilon was on average 50% lower using QLAB compared with EchoPAC and SPEQLE. Systolic strain rate values obtained by STE were lower compared with CDTI-derived values. The limits of agreement for strain rate values among the three modalities were wide, and intraobserver and interobserver variability was poor for all three modalities. Some deformation measurements (e.g., longitudinal and circumferential epsilon) are comparable among different ultrasound machines and software packages, whereas others are significantly different (e.g., radial epsilon and strain rate

  18. Extending the unambiguous velocity range using multiple carrier frequencies

    DEFF Research Database (Denmark)

    Zhang, Z.; Jakobsson, A.; Nikolov, Svetoslav

    2005-01-01

    Typically, velocity estimators based on the estimation of the Doppler shift will suffer from a limited unambiguous velocity range. Proposed are two novel multiple carrier based velocity estimators extending the velocity range above the Nyquist velocity limit. Numerical simulations indicate...

  19. Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

    Science.gov (United States)

    St. Clair, James; Holbrook, W. Steven

    2017-12-01

    Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR) has been shown to be an effective tool for measuring snow water equivalent (SWE) because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD) filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3-21 % of the manual measurements when the antenna is mounted on the front of a snowmobile ˜ 0.5 m above the snow surface.

  20. Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

    Directory of Open Access Journals (Sweden)

    J. St. Clair

    2017-12-01

    Full Text Available Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR has been shown to be an effective tool for measuring snow water equivalent (SWE because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3–21 % of the manual measurements when the antenna is mounted on the front of a snowmobile  ∼  0.5 m above the snow surface.