A Comprehensive Radial Velocity Error Budget for Next Generation Doppler Spectrometers

Science.gov (United States)

Halverson, Samuel; Ryan, Terrien; Mahadevan, Suvrath; Roy, Arpita; Bender, Chad; Stefansson, Guomundur Kari; Monson, Andrew; Levi, Eric; Hearty, Fred; Blake, Cullen;

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

Blood flow velocity in migraine attacks - a transcranial Doppler study

Energy Technology Data Exchange (ETDEWEB)

Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

1991-05-01

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.

The Coincident Coherence of Extreme Doppler Velocity Events with p-mode Patches in the Solar Photosphere.

Science.gov (United States)

McClure, Rachel Lee

2018-06-01

Observations of the solar photosphere show many spatially compact Doppler velocity events with short life spans and extreme values. In the IMaX spectropolarimetric inversion data of the first flight of the SUNRISE balloon in 2009 these striking flashes in the intergranule lanes and complementary outstanding values in the centers of granules have line of sight Doppler velocity values in excess of 4 sigma from the mean. We conclude that values outside 4 sigma are a result from the superposition of the granulation flows and the p-modes.To determine how granulation and p-modes contribute to these outstanding Doppler events, I separate the two components using the Fast Fourier Transform. I produce the power spectrum of the spatial wave frequencies and their corresponding frequency in time for each image, and create a k-omega filter to separate the two components. Using the filtered data, test the hypothesis that extreme events occur because of strict superposition between the p-mode Doppler velocities and the granular velocities. I compare event counts from the observational data to those produced by random superposition of the two flow components and find that the observational event counts are consistent with the model event counts in the limit of small number statistics. Poisson count probabilities of event numbers observed are consistent with expected model count probability distributions.

Parameters determining maximum wind velocity in a tropical cyclone

International Nuclear Information System (INIS)

Choudhury, A.M.

1984-09-01

The spiral structure of a tropical cyclone was earlier explained by a tangential velocity distribution which varies inversely as the distance from the cyclone centre outside the circle of maximum wind speed. The case has been extended in the present paper by adding a radial velocity. It has been found that a suitable combination of radial and tangential velocities can account for the spiral structure of a cyclone. This enables parametrization of the cyclone. Finally a formula has been derived relating maximum velocity in a tropical cyclone with angular momentum, radius of maximum wind speed and the spiral angle. The shapes of the spirals have been computed for various spiral angles. (author)

Preliminary simulation study of doppler reflectometry

International Nuclear Information System (INIS)

Ishii, Yuta; Hojo, Hitoshi; Yoshikawa, Masashi; Ichimura, Makoto; Haraguchi, Yusuke; Imai, Tsuyoshi; Mase, Atsushi

2010-01-01

A preliminary simulation study of Doppler reflectometry is performed. The simulations solve Maxwell's equations by a finite difference time domain (FDTD) code method in two dimensions. A moving corrugated metal target is used as a plasma cutoff layer to study the basic features of Doppler reflectometry. We examined the effects of the full width at half maximum (FWHM) of the electromagnetic waves and the corrugation depth of the metal target. Furthermore, the effect of a nonuniform plasma is studied using this FDTD analysis. The Doppler shift and velocity are compared with those obtained from FDTD analysis of a uniform plasma. (author)

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.

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...

Complex regression Doppler optical coherence tomography

Science.gov (United States)

Elahi, Sahar; Gu, Shi; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2018-04-01

We introduce a new method to measure Doppler shifts more accurately and extend the dynamic range of Doppler optical coherence tomography (OCT). The two-point estimate of the conventional Doppler method is replaced with a regression that is applied to high-density B-scans in polar coordinates. We built a high-speed OCT system using a 1.68-MHz Fourier domain mode locked laser to acquire high-density B-scans (16,000 A-lines) at high enough frame rates (˜100 fps) to accurately capture the dynamics of the beating embryonic heart. Flow phantom experiments confirm that the complex regression lowers the minimum detectable velocity from 12.25 mm / s to 374 μm / s, whereas the maximum velocity of 400 mm / s is measured without phase wrapping. Complex regression Doppler OCT also demonstrates higher accuracy and precision compared with the conventional method, particularly when signal-to-noise ratio is low. The extended dynamic range allows monitoring of blood flow over several stages of development in embryos without adjusting the imaging parameters. In addition, applying complex averaging recovers hidden features in structural images.

Evaluation of Portal Venous Velocity with Doppler Ultrasound in Patients with Nonalcoholic Fatty Liver Disease

Energy Technology Data Exchange (ETDEWEB)

Ulusan, Serife; Yakar, Tolga; Koc, Zafer [Baskent University Faculty of Medicine, Adana (Turkmenistan)

2011-08-15

We examined the relationship between portal venous velocity and hepatic-abdominal fat in patients with nonalcoholic fatty liver disease (NAFLD), using spectral Doppler ultrasonography (US) and magnetic resonance imaging (MRI). In this prospective study, 35 patients with NAFLD and 29 normal healthy adults (control group) underwent portal Doppler US. The severity of hepatic steatosis in patients with NAFLD was assessed by MRI through chemical shift imaging, using a modification of the Dixon method. Abdominal (intra-abdominal and subcutaneous) fat was measured by MRI. The difference in portal venous velocity between the patients with NAFLD and the control group was significant (p < 0.0001). There was no correlation between the degree of abdominal or hepatic fat and portal venous velocity (p > 0.05). There were strong correlations between the hepatic fat fraction and subcutaneous adiposity (p < 0.0001), intraperitoneal fat accumulation (p 0.017), and retroperitoneal fat accumulation (p < 0.0001). Our findings suggest that patients with NAFLD have lower portal venous velocities than normal healthy subjects.

Spectroscopic Doppler analysis for visible-light optical coherence tomography

Science.gov (United States)

Shu, Xiao; Liu, Wenzhong; Duan, Lian; Zhang, Hao F.

2017-12-01

Retinal oxygen metabolic rate can be effectively measured by visible-light optical coherence tomography (vis-OCT), which simultaneously quantifies oxygen saturation and blood flow rate in retinal vessels through spectroscopic analysis and Doppler measurement, respectively. Doppler OCT relates phase variation between sequential A-lines to the axial flow velocity of the scattering medium. The detectable phase shift is between -π and π due to its periodicity, which limits the maximum measurable unambiguous velocity without phase unwrapping. Using shorter wavelengths, vis-OCT is more vulnerable to phase ambiguity since flow induced phase variation is linearly related to the center wavenumber of the probing light. We eliminated the need for phase unwrapping using spectroscopic Doppler analysis. We split the whole vis-OCT spectrum into a series of narrow subbands and reconstructed vis-OCT images to extract corresponding Doppler phase shifts in all the subbands. Then, we quantified flow velocity by analyzing subband-dependent phase shift using linear regression. In the phantom experiment, we showed that spectroscopic Doppler analysis extended the measurable absolute phase shift range without conducting phase unwrapping. We also tested this method to quantify retinal blood flow in rodents in vivo.

Observation of E×B Flow Velocity Profile Change Using Doppler Reflectometry in HL-2A

Institute of Scientific and Technical Information of China (English)

XIAO Wei-Wen; ZOU Xiao-Lan; DING Xuan-Tong; DONG Jia-Qi; LIU Ze-Tian; SONG Shao-Dong; GAO Ya-Dong; YAO Liang-Hua; FENG Bei-Bin; SONG Xian-Ming; CHEN Cheng-Yuan; SUN Hong-Juan; LI Yong-Gao; YANG Qing-Wei; YAN Long-Wen; LIU Yi; DUAN Xu-Ru; PAN Chuan-Hong; LIU Yong

2009-01-01

A broadband,O-mode sweeping Doppler reflectometry designed for measuring plasma E×B flow velocity profiles is operated in HL-2A.The main feature of the Doppler reflectometry is its capability to be tuned to any selected frequency in total waveband from 26-40 GHz.This property enables us to probe several plasma layers within a short time interval during a discharge,permitting the characterization of the radial distribution of plasma fluctuations.The system allows us to extract important information about the velocity change layer,namely its spatial localization.In purely Ohmic discharge a change of the E×B flow velocity profiles has been observed in the region for 28 ＜ r ＜ 30cm if only the line average density exceeds 2.2×1019 m-3.The density gradient change is measured in the same region,too.

Local velocity measurements in lead-bismuth and sodium flows using the ultrasound doppler velocimetry

International Nuclear Information System (INIS)

Eckert, S.; Gerbeth, G.

2003-01-01

We will present measurements of the velocity profiles in liquid sodium and eutectic lead-bismuth by means of the Ultrasonic Doppler Velocimetry (UDV). A sodium flow in a rectangular duct exposed to an external, transverse magnetic field has been examined. To demonstrate the capability of UDV the transformation of the well-known turbulent, piston-like profile to an M-shaped velocity profile for growing magnetic field strength was observed. The significance of artifacts such as caused by the existence of reflecting interfaces in the measuring domain will be discussed. In the sodium case, the measurements were performed through the channel wall. An integrated ultrasonic sensor with acoustic wave-guide has been developed to overcome the limitation of ultrasonic transducers to temperatures lower than 200 .deg. C. This sensor can presently be applied at maximum temperatures up to 800 .deg. C. Stable and robust measurements have been performed in various PbBi flows in our laboratory at FZR as well as at the THESYS loop of the KALLA laboratory of the ForschungsZentrum Karlsruhe (FZK). We will also present experimental results obtained in a PbBi bubbly flow at 250...300 .deg. C. Argon bubbles were injected through a single orifice in a cylindrical container filled with stagnant PbBi. Velocity profiles were measured in the bubble plume. Mean values of the liquid as well as the bubble velocity were extracted from the data and will be presented as function of the gas flow rate

ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space

Science.gov (United States)

Krawczyk, R.; Ghibaudo, JB.; Labandibar, JY.; Willetts, D.; Vaughan, M.; Pearson, G.; Harris, M.; Flamant, P. H.; Salamitou, P.; Dabas, A.; Charasse, R.; Midavaine, T.; Royer, M.; Heimel, H.

2018-04-01

This paper, "ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Measurement of fast-changing low velocities by photonic Doppler velocimetry

Energy Technology Data Exchange (ETDEWEB)

Song Hongwei; Wu Xianqian; Huang Chenguang; Wei Yangpeng; Wang Xi [Key Laboratory for Hydrodynamics and Ocean Engineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

2012-07-15

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.

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.)

Transesophageal Doppler measurement of renal arterial blood flow velocities and indices in children.

Science.gov (United States)

Zabala, Luis; Ullah, Sana; Pierce, Carol D'Ann; Gautam, Nischal K; Schmitz, Michael L; Sachdeva, Ritu; Craychee, Judith A; Harrison, Dale; Killebrew, Pamela; Bornemeier, Renee A; Prodhan, Parthak

2012-06-01

Doppler-derived renal blood flow indices have been used to assess renal pathologies. However, transesophageal ultrasonography (TEE) has not been previously used to assess these renal variables in pediatric patients. In this study, we (a) assessed whether TEE allows adequate visualization of the renal parenchyma and renal artery, and (b) evaluated the concordance of TEE Doppler-derived renal blood flow measurements/indices compared with a standard transabdominal renal ultrasound (TAU) in children. This prospective cohort study enrolled 28 healthy children between the ages of 1 and 17 years without known renal dysfunction who were undergoing atrial septal defect device closure in the cardiac catheterization laboratory. TEE was used to obtain Doppler renal artery blood velocities (peak systolic velocity, end-diastolic velocity, mean diastolic velocity, resistive index, and pulsatility index), and these values were compared with measurements obtained by TAU. Concordance correlation coefficient (CCC) was used to determine clinically significant agreement between the 2 methods. The Bland-Altman plots were used to determine whether these 2 methods agree sufficiently to be used interchangeably. Statistical significance was accepted at P ≤ 0.05. Obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children is feasible. There was statistically significant agreement between the 2 methods for all measurements. The CCC between the 2 imaging techniques was 0.91 for the pulsatility index and 0.66 for the resistive index. These coefficients were sensitive to outliers. When the highest and lowest data points were removed from the analysis, the CCC between the 2 imaging techniques was 0.62 for the pulsatility index and 0.50 for the resistive index. The 95% confidence interval (CI) for pulsatility index was 0.35 to 0.98 and for resistive index was 0.21 to 0.89. The Bland-Altman plots indicate good agreement between the 2 methods; for the

Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows

Science.gov (United States)

Allen, M. G.; Davis, S. J.; Kessler, W. J.; Sonnenfroh, D. M.

1992-01-01

The application of Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows is analyzed. Focussing on fluorescence of the OH molecule in typical H2-air Scramjet flows, the effects of uncharacterized variations in temperature, pressure, and collisional partner composition across the measurement plane are examined. Detailed measurements of the (1,0) band OH lineshape variations in H2-air combustions are used, along with single-pulse and time-averaged measurements of an excimer-pumped dye laser, to predict the performance of a model velocimeter with typical Scramjet flow properties. The analysis demonstrates the need for modification and control of the laser bandshape in order to permit accurate velocity measurements in the presence of multivariant flow properties.

Assessment of the Influence Factors on Nasal Spray Droplet Velocity Using Phase-Doppler Anemometry (PDA)

OpenAIRE

Liu, Xiaofei; Doub, William H.; Guo, Changning

2011-01-01

Droplet velocity is an important parameter that can be used to characterize nasal spray products. In this study, a phase-Doppler anemometry (PDA) system was used to measure the droplet velocities of nasal sprays. A survey of seven commercial nasal spray products showed a range of droplet velocities from 6.7 to 19.2 m/s, all significantly different from each other. A three-level, four-factor Box–Behnken design of experiments (DOE) methodology were applied to investigate the influences of actua...

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

Real-time three-dimensional color Doppler echocardiography for characterizing the spatial velocity distribution and quantifying the peak flow rate in the left ventricular outflow tract

Science.gov (United States)

Tsujino, H.; Jones, M.; Shiota, T.; Qin, J. X.; Greenberg, N. L.; Cardon, L. A.; Morehead, A. J.; Zetts, A. D.; Travaglini, A.; Bauer, F.;

Techniques for obtaining velocity distributions of atoms or ions from Doppler-broadened spectral line profiles

International Nuclear Information System (INIS)

Moran, T.G.

1986-12-01

Analysis of the doppler-broadened profiles of spectral lines radiated by atoms or ions in plasmas yields information about their velocity distributions. Researchers have analysed profiles of lines radiated by atoms in isotropic velocity distributions in several ways, one being the inversion of the integral equation which relates the velocity distribution to the line profile. This inversion formula was derived for a separate application and was given to within an arbitrary multiplicative constant. This paper presents a new derivation which obtains the inversion exactly, using a method which is easily generalized for determination of anisotropic velocity distribution functions. The technique to obtain an anisotropic velocity distribution function from line profiles measured at different angles is outlined

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

Field estimates of floc dynamics and settling velocities in a tidal creek with significant along-channel gradients in velocity and SPM

Science.gov (United States)

Schwarz, C.; Cox, T.; van Engeland, T.; van Oevelen, D.; van Belzen, J.; van de Koppel, J.; Soetaert, K.; Bouma, T. J.; Meire, P.; Temmerman, S.

2017-10-01

A short-term intensive measurement campaign focused on flow, turbulence, suspended particle concentration, floc dynamics and settling velocities were carried out in a brackish intertidal creek draining into the main channel of the Scheldt estuary. We compare in situ estimates of settling velocities between a laser diffraction (LISST) and an acoustic Doppler technique (ADV) at 20 and 40 cm above bottom (cmab). The temporal variation in settling velocity estimated were compared over one tidal cycle, with a maximum flood velocity of 0.46 m s-1, a maximum horizontal ebb velocity of 0.35 m s-1 and a maximum water depth at high water slack of 2.41 m. Results suggest that flocculation processes play an important role in controlling sediment transport processes in the measured intertidal creek. During high-water slack, particles flocculated to sizes up to 190 μm, whereas at maximum flood and maximum ebb tidal stage floc sizes only reached up to 55 μm and 71 μm respectively. These large differences indicate that flocculation processes are mainly governed by turbulence-induced shear rate. In this study, we specifically recognize the importance of along-channel gradients that places constraints on the application of the acoustic Doppler technique due to conflicts with the underlying assumptions. Along-channel gradients were assessed by additional measurements at a second location and scaling arguments which could be used as an indication whether the Reynolds-flux method is applicable. We further show the potential impact of along-channel advection of flocs out of equilibrium with local hydrodynamics influencing overall floc sizes.

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...

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; Desai, R.G.P.; VijayKumar, K.; Dias, M.; Tengali, S.; Methar, A

Performance of a 500-kHz, 3-beam downward-looking Sontex Argonaut acoustic Doppler velocity log (DVL) based on measurements at tow-tank and sea is addressed. Its accuracy and linearity under tow-tank measurements were largely scattered...

Evaluation of arterial digital blood flow using Doppler ultrasonography in healthy dairy cows.

Science.gov (United States)

Müller, H; Heinrich, M; Mielenz, N; Reese, S; Steiner, A; Starke, A

2017-06-06

Local circulatory disturbances have been implicated in the development of foot disorders in cattle. The goals of this study were to evaluate the suitability of the interdigital artery in the pastern region in both hind limbs using pulsed-wave (PW) Doppler ultrasonography and to investigate quantitative arterial blood flow variables at that site in dairy cows. An Esaote MyLabOne ultrasound machine with a 10-MHz linear transducer was used to assess blood flow in the interdigital artery in the pastern region in both hind limbs of 22 healthy German Holstein cows. The cows originated from three commercial farms and were restrained in a standing hoof trimming chute without sedation. A PW Doppler signal suitable for analysis was obtained in 17 of 22 cows. The blood flow profiles were categorised into four curve types, and the following quantitative variables were measured in three uniform cardiac cycles: vessel diameter, pulse rate, maximum systolic velocity, maximum diastolic velocity, end-diastolic velocity, reverse velocity, maximum time-averaged mean velocity, blood flow rate, resistance index and persistence index. The measurements did not differ among cows from the three farms. Maximum systolic velocity, vessel diameter and pulse rate did not differ but other variables differed significantly among blood flow profiles. Differences in weight-bearing are thought to be responsible for the normal variability of blood flow profiles in healthy cows. The scanning technique used in this report for evaluation of blood flow in the interdigital artery appears suitable for further investigations in healthy and in lame cows.

Operator auditory perception and spectral quantification of umbilical artery Doppler ultrasound signals.

Directory of Open Access Journals (Sweden)

Ann Thuring

Full Text Available OBJECTIVE: An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI. Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model. METHODS: Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by microsphere embolization of the placental bed (embolization model, 7 lamb fetuses, 370 Doppler recordings or by fetal hemodilution (anemia model, 4 lamb fetuses, 184 recordings. A subjective 11-step operator auditory scale (OAS was related to conventional Doppler parameters, PI and time average mean velocity (TAM, and to sound frequency analysis of Doppler signals (sound frequency with the maximum energy content [MAXpeak] and frequency band at maximum level minus 15 dB [MAXpeak-15 dB] over several heart cycles. RESULTS: WE FOUND A NEGATIVE CORRELATION BETWEEN THE OAS AND PI: median Rho -0.73 (range -0.35- -0.94 and -0.68 (range -0.57- -0.78 in the two lamb models, respectively. There was a positive correlation between OAS and TAM in both models: median Rho 0.80 (range 0.58-0.95 and 0.90 (range 0.78-0.95, respectively. A strong correlation was found between TAM and the results of sound spectrum analysis; in the embolization model the median r was 0.91 (range 0.88-0.97 for MAXpeak and 0.91 (range 0.82-0.98 for MAXpeak-15 dB. In the anemia model, the corresponding values were 0.92 (range 0.78-0.96 and 0.96 (range 0.89-0.98, respectively. CONCLUSION: Audio-spectrum analysis reflects the subjective perception of Doppler sound signals in the umbilical artery and has a strong correlation to TAM-velocity. This information might be of importance for clinical management of complicated pregnancies as an addition to conventional Doppler parameters.

Determination of the Ion Velocity Distribution in a Rotating Plasma from Measurements of Doppler Broadening

DEFF Research Database (Denmark)

Jørgensen, L. W.; Sillesen, Alfred Hegaard

1979-01-01

The Doppler-broadened profile of the He II 4685.75 AA line was measured along a chord in a rotating plasma, transverse to the magnetic field. Using a single-particle orbit picture, the corresponding velocity spectrum of ions confirm the measurements, so it can be concluded that the single-particl...

Enormous periodic doppler shifts in SS 433

International Nuclear Information System (INIS)

Margon, B.; Ford, H.C.; Grandi, S.A.; Stone, R.P.S.

1979-01-01

We have previously reported prominent ''moving' emission lines in the visible spectrum of Stephenson-Sanduleak 433, the optical counterpart of a variable radio and X-ray source. Further observations show that despite the implausible velocities and changes in velocities implied if the moving features are interpreted as Doppler-shifted Balmer lines, this explanation is indeed correct. Spectroscopy of SS 433 on 51 mights in 1978--1979 reveals that the unidentified features are two sets of Balmer and He I lines, one with large and changing redshift, and the other with large and changing blueshift. Combining our data with published earlier observations, we obtain Doppler shifts on 80 nights in the period 1978 June to 1979 June. These data indicate that the velocity variations are cyclical, repeating in both the blueshift and redshift systems with a period of 164 +- 3 days. The two systems have thus far been observed to reach maximum positive and negative radial velocities of +50,000 and -35,000 km s -1 , respectively, are always symmetric about redshift z=0.04, and follow roughly sinusoidal velocity curves. We discuss in addition a variety of interesting short-term spectroscopic details, including minor but highly significant deviations of the radial velocity from the sinusoid, and nightly line profile changes, sometimes appearing as mirror-image events in the redshift and blueshift systems. The behavior of SS 433 is unprecedented

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.

The Relationship Between Maximum Isometric Strength and Ball Velocity in the Tennis Serve

Directory of Open Access Journals (Sweden)

Baiget Ernest

2016-12-01

Full Text Available The aims of this study were to analyze the relationship between maximum isometric strength levels in different upper and lower limb joints and serve velocity in competitive tennis players as well as to develop a prediction model based on this information. Twelve male competitive tennis players (mean ± SD; age: 17.2 ± 1.0 years; body height: 180.1 ± 6.2 cm; body mass: 71.9 ± 5.6 kg were tested using maximum isometric strength levels (i.e., wrist, elbow and shoulder flexion and extension; leg and back extension; shoulder external and internal rotation. Serve velocity was measured using a radar gun. Results showed a strong positive relationship between serve velocity and shoulder internal rotation (r = 0.67; p < 0.05. Low to moderate correlations were also found between serve velocity and wrist, elbow and shoulder flexion – extension, leg and back extension and shoulder external rotation (r = 0.36 – 0.53; p = 0.377 – 0.054. Bivariate and multivariate models for predicting serve velocity were developed, with shoulder flexion and internal rotation explaining 55% of the variance in serve velocity (r = 0.74; p < 0.001. The maximum isometric strength level in shoulder internal rotation was strongly related to serve velocity, and a large part of the variability in serve velocity was explained by the maximum isometric strength levels in shoulder internal rotation and shoulder flexion.

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...

Evaluation of metered dose inhaler spray velocities using phase Doppler anemometry (PDA).

Science.gov (United States)

Liu, Xiaofei; Doub, William H; Guo, Changning

2012-02-28

Droplet velocity is an important parameter which can significantly influence inhalation drug delivery performance. Together with the droplet size, this parameter determines the efficiency of the deposition of MDI products at different sites within the lungs. In this study, phase Doppler anemometry (PDA) was used to investigate the instantaneous droplet velocity emitted from MDIs as well as the corresponding droplet size distribution. The nine commercial MDI products surveyed showed significantly different droplet velocities, indicating that droplet velocity could be used as a discriminating parameter for in vitro testing of MDI products. The droplet velocity for all tested MDI products decreased when the testing distance was increased from 3 cm to 6 cm from the front of mouthpiece, with CFC formulations showing a larger decrease than HFA formulations. The mean droplet diameters of the nine MDIs were also significantly different from one-another. Droplet size measurements made using PDA (a number-based technique) could not be directly compared to results obtained using laser light scattering measurements (a volume-based technique). This work demonstrates that PDA can provide unique information useful for characterizing MDI aerosol plumes and evaluating MDI drug delivery efficiency. PDA could also aid the evaluation of in vitro equivalence in support of formulation or manufacturing changes and in evaluation of abbreviated new drug applications (ANDAs) for MDIs. Published by Elsevier B.V.

The Relationship Between Maximum Isometric Strength and Ball Velocity in the Tennis Serve.

Science.gov (United States)

Baiget, Ernest; Corbi, Francisco; Fuentes, Juan Pedro; Fernández-Fernández, Jaime

2016-12-01

The aims of this study were to analyze the relationship between maximum isometric strength levels in different upper and lower limb joints and serve velocity in competitive tennis players as well as to develop a prediction model based on this information. Twelve male competitive tennis players (mean ± SD; age: 17.2 ± 1.0 years; body height: 180.1 ± 6.2 cm; body mass: 71.9 ± 5.6 kg) were tested using maximum isometric strength levels (i.e., wrist, elbow and shoulder flexion and extension; leg and back extension; shoulder external and internal rotation). Serve velocity was measured using a radar gun. Results showed a strong positive relationship between serve velocity and shoulder internal rotation (r = 0.67; p isometric strength level in shoulder internal rotation was strongly related to serve velocity, and a large part of the variability in serve velocity was explained by the maximum isometric strength levels in shoulder internal rotation and shoulder flexion.

New Insights from Inside-Out Doppler Tomography

Directory of Open Access Journals (Sweden)

E. J. Kotze

2015-02-01

Full Text Available We present preliminary results from our investigation into using an “inside-out” velocity space for creating a Doppler tomogram. The aim is to transpose the inverted appearance of the Cartesian velocity space used in normal Doppler tomography. In a comparison between normal and inside-out Doppler tomograms of cataclysmic variables, we show that the inside-out velocity space has the potential to produce new insights into the accretion dynamics in these systems.

Assessment of the influence factors on nasal spray droplet velocity using phase-Doppler anemometry (PDA).

Science.gov (United States)

Liu, Xiaofei; Doub, William H; Guo, Changning

2011-03-01

Droplet velocity is an important parameter that can be used to characterize nasal spray products. In this study, a phase-Doppler anemometry (PDA) system was used to measure the droplet velocities of nasal sprays. A survey of seven commercial nasal spray products showed a range of droplet velocities from 6.7 to 19.2 m/s, all significantly different from each other. A three-level, four-factor Box-Behnken design of experiments (DOE) methodology were applied to investigate the influences of actuation parameters and formulation properties on nasal spray droplet velocity using a set of placebo formulations. The DOE study shows that all four input factors (stroke length, actuation velocity, concentration of the gelling agent, and concentration of the surfactant) have significant influence on droplet velocity. An optimized quadratic model generated from the DOE results describes the inherent relationships between the input factors and droplet velocity thus providing a better understanding of the input factor influences. Overall, PDA provides a new in vitro characterization method for the evaluation of inhalation drugs through assessment of spray velocity and may assist in product development to meet drug delivery equivalency requirements. © 2011 American Association of Pharmaceutical Scientists

Adaptive OFDM Radar Waveform Design for Improved Micro-Doppler Estimation

Energy Technology Data Exchange (ETDEWEB)

Sen, Satyabrata [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Engineering Science Advanced Research, Computer Science and Mathematics Division

2014-07-01

Here we analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a rotating target having multiple scattering centers. The use of a frequency-diverse OFDM signal enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. We characterize the accuracy of micro-Doppler frequency estimation by computing the Cramer-Rao bound (CRB) on the angular-velocity estimate of the target. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations with respect to the signal-to-noise ratios, number of temporal samples, and number of OFDM subcarriers. We also analysed numerically the improvement in estimation accuracy due to the adaptive waveform design. A grid-based maximum likelihood estimation technique is applied to evaluate the corresponding mean-squared error performance.

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

Inertial Navigation System/Doppler Velocity Log (INS/DVL Fusion with Partial DVL Measurements

Directory of Open Access Journals (Sweden)

Asaf Tal

2017-02-01

Full Text Available The Technion autonomous underwater vehicle (TAUV is an ongoing project aiming to develop and produce a small AUV to carry on research missions, including payload dropping, and to demonstrate acoustic communication. Its navigation system is based on an inertial navigation system (INS aided by a Doppler velocity log (DVL, magnetometer, and pressure sensor (PS. In many INSs, such as the one used in TAUV, only the velocity vector (provided by the DVL can be used for aiding the INS, i.e., enabling only a loosely coupled integration approach. In cases of partial DVL measurements, such as failure to maintain bottom lock, the DVL cannot estimate the vehicle velocity. Thus, in partial DVL situations no velocity data can be integrated into the TAUV INS, and as a result its navigation solution will drift in time. To circumvent that problem, we propose a DVL-based vehicle velocity solution using the measured partial raw data of the DVL and additional information, thereby deriving an extended loosely coupled (ELC approach. The implementation of the ELC approach requires only software modification. In addition, we present the TAUV six degrees of freedom (6DOF simulation that includes all functional subsystems. Using this simulation, the proposed approach is evaluated and the benefit of using it is shown.

Screening for stroke in sickle cell anemia: comparison of transcranial Doppler imaging and nonimaging US techniques.

Science.gov (United States)

Neish, Ariane S; Blews, David E; Simms, Catherine A; Merritt, Robert K; Spinks, Alice J

2002-03-01

To determine whether criteria for screening patients with sickle cell anemia for stroke established with a nonimaging transcranial Doppler ultrasonographic (US) technique are applicable to studies performed with a transcranial Doppler US imaging technique. One hundred sixty-eight examinations in 66 children were performed for sickle cell stroke screening. Children were examined with nonimaging and imaging transcranial Doppler US techniques on the same day, for a total of 84 paired examinations. The time-averaged maximum mean velocity (V(mean)) and resistive index (RI) were calculated in the middle cerebral arteries, bifurcations of the distal internal carotid arteries, distal internal carotid arteries, anterior cerebral arteries, posterior cerebral arteries, and basilar arteries. The maximum systolic velocity (V(max)) was evaluated in the distal internal carotid arteries and middle cerebral arteries. V(mean), V(max), and RI measurements were subjected to repeated-measures multivariate analysis of covariance, and the Pearson product moment correlation was used for middle cerebral artery velocity, age, and hemoglobin. V(mean) measurements obtained with nonimaging and imaging techniques varied substantially for the bifurcation of the distal internal carotid artery, the posterior cerebral artery, and the basilar artery. Substantial differences were found in RIs for every vessel. Examination time was shorter with the nonimaging technique. V(mean) measurements in the middle cerebral artery, distal internal carotid artery, and anterior cerebral artery did not vary substantially between nonimaging and imaging transcranial Doppler US. RI data did not yield comparable measurements.

Maximum Likelihood Blood Velocity Estimator Incorporating Properties of Flow Physics

DEFF Research Database (Denmark)

Schlaikjer, Malene; Jensen, Jørgen Arendt

2004-01-01

)-data under investigation. The flow physic properties are exploited in the second term, as the range of velocity values investigated in the cross-correlation analysis are compared to the velocity estimates in the temporal and spatial neighborhood of the signal segment under investigation. The new estimator...... has been compared to the cross-correlation (CC) estimator and the previously developed maximum likelihood estimator (MLE). The results show that the CMLE can handle a larger velocity search range and is capable of estimating even low velocity levels from tissue motion. The CC and the MLE produce...... for the CC and the MLE. When the velocity search range is set to twice the limit of the CC and the MLE, the number of incorrect velocity estimates are 0, 19.1, and 7.2% for the CMLE, CC, and MLE, respectively. The ability to handle a larger search range and estimating low velocity levels was confirmed...

Evaluation of droplet velocity and size from nasal spray devices using phase Doppler anemometry (PDA).

Science.gov (United States)

Liu, Xiaofei; Doub, William H; Guo, Changning

2010-03-30

To determine aerosol deposition during the inhalation drug delivery, it is important to understand the combination of velocity and droplet size together. In this study, phase Doppler anemometry (PDA) was used to simultaneously characterize the aerosol velocity and droplet size distribution (DSD) of three nasal spray pumps filled with water. Thirteen sampling positions were located in the horizontal cross-sectional area of the nasal spray plumes at a distance of 3cm from the pump orifice. The results showed droplet velocities near the center of the spray plume were higher and more consistent than those near the edge. The pumps examined showed significant differences in their aerosol velocity at the center of the spray plume, which suggest that this metric might be used as a discriminating parameter for in vitro testing of nasal sprays. Droplet size measurements performed using PDA were compared with results from laser light scattering measurements. The ability of PDA to provide simultaneous measurements of aerosol velocity and size makes it a powerful tool for the detailed investigation of nasal spray plume characteristics. Published by Elsevier B.V.

Velocity profile measurement of lead-lithium flows by high-temperature ultrasonic doppler velocimetry

International Nuclear Information System (INIS)

Ueki, Y.; Kunugi, T.; Hirabayashi, Masaru; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Morley, N.B.

2014-01-01

This paper describes a high-temperature ultrasonic Doppler Velocimetry (HT-UDV) technique that has been successfully applied to measure velocity profiles of the lead-lithium eutectic alloy (PbLi) flows. The impact of tracer particles is investigated to determine requirements for HT-UDV measurement of PbLi flows. The HT-UDV system is tested on a PbLi flow driven by a rotating-disk in an inert atmosphere. We find that a sufficient amount of particles contained in the molten PbLi are required to successfully measure PbLi velocity profiles by HT-UDV. An X-ray diffraction analysis is performed to identify those particles in PbLi, and indicates that those particles were made of the lead mono-oxide (PbO). Since the specific densities of PbLi and PbO are close to each other, the PbO particles are expected to be well-dispersed in the bulk of molten PbLi. We conclude that the excellent dispersion of PbO particles enables in HT-UDV to obtain reliable velocity profiles for operation times of around 12 hours. (author)

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)

Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation.

Science.gov (United States)

Garcia, M J; Smedira, N G; Greenberg, N L; Main, M; Firstenberg, M S; Odabashian, J; Thomas, J D

2000-01-01

To determine the effect of preload in color M-mode Doppler flow propagation velocity (v(p)). The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.

Maximum run-up behavior of tsunamis under non-zero initial velocity condition

Directory of Open Access Journals (Sweden)

Baran AYDIN

2018-03-01

Full Text Available The tsunami run-up problem is solved non-linearly under the most general initial conditions, that is, for realistic initial waveforms such as N-waves, as well as standard initial waveforms such as solitary waves, in the presence of initial velocity. An initial-boundary value problem governed by the non-linear shallow-water wave equations is solved analytically utilizing the classical separation of variables technique, which proved to be not only fast but also accurate analytical approach for this type of problems. The results provide important information on maximum tsunami run-up qualitatively. We observed that, although the calculated maximum run-ups increase significantly, going as high as double that of the zero-velocity case, initial waves having non-zero fluid velocity exhibit the same run-up behavior as waves without initial velocity, for all wave types considered in this study.

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

Science.gov (United States)

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

2016-12-01

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.

Evaluation of hepatic venous pulsatility and portal venous velocity with doppler ultrasonography during the puerperium

Energy Technology Data Exchange (ETDEWEB)

Pekindil, Goekhan [Department of Radiology, Trakya University School of Medicine, 22030 Edirne (Turkey); Varol, Fuesun G. [Department of Obstetrics and Gynecology, Trakya University School of Medicine, 22030 Edirne (Turkey); Ali Yuece, M. [Department of Obstetrics and Gynecology, Trakya University School of Medicine, 22030 Edirne (Turkey); Yardim, Turgut [Department of Obstetrics and Gynecology, Trakya University School of Medicine, 22030 Edirne (Turkey)

1999-03-01

Objective: The aim of this study is to evaluate pregnancy-induced changes of hepatic venous pulsatility and portal venous velocity in the puerperium and to determine if these changes disappeared by the end of the puerperium. Methods and material: Healthy normal volunteers (90) were examined on the 2nd and 7th days of puerperium and between the 6th and 8th weeks postpartum. Doppler waveform patterns were obtained in the middle hepatic vein and main portal vein. The hepatic venous pulsatility was named as normal, damped or flat. Results: On the 2nd day postpartum, the hepatic vein pulsatility was shown as normal in 8 (26%), damped in 11 (37%) and flat in 11 (37%) cases. On the 7th day postpartum, 15 (50%) cases had normal, 9 (30%) cases had dampened, and 6 (20%) cases had still flat pattern. The majority of the cases (60%) displayed normal hepatic venous pulsatility in the 6th and 8th weeks of puerperium, whereas 23% had still dampened and 17% had flat patterns. There was a trend toward normal pulsatility with increasing puerperal age. The mean portal venous velocity was still higher than the non-pregnant levels and did not showed significant alterations during puerperium. Conclusion: This study emphasised that, since pregnancy-induced alterations in hepatic venous pulsatility and portal venous velocity had not completely returned to normal in most cases until the end of the puerperium, these physiological changes should be considered whenever hepatic and portal systems are interpreted with Doppler sonography during the puerperal period.

Evaluation of hepatic venous pulsatility and portal venous velocity with doppler ultrasonography during the puerperium

International Nuclear Information System (INIS)

Pekindil, Goekhan; Varol, Fuesun G.; Ali Yuece, M.; Yardim, Turgut

1999-01-01

Objective: The aim of this study is to evaluate pregnancy-induced changes of hepatic venous pulsatility and portal venous velocity in the puerperium and to determine if these changes disappeared by the end of the puerperium. Methods and material: Healthy normal volunteers (90) were examined on the 2nd and 7th days of puerperium and between the 6th and 8th weeks postpartum. Doppler waveform patterns were obtained in the middle hepatic vein and main portal vein. The hepatic venous pulsatility was named as normal, damped or flat. Results: On the 2nd day postpartum, the hepatic vein pulsatility was shown as normal in 8 (26%), damped in 11 (37%) and flat in 11 (37%) cases. On the 7th day postpartum, 15 (50%) cases had normal, 9 (30%) cases had dampened, and 6 (20%) cases had still flat pattern. The majority of the cases (60%) displayed normal hepatic venous pulsatility in the 6th and 8th weeks of puerperium, whereas 23% had still dampened and 17% had flat patterns. There was a trend toward normal pulsatility with increasing puerperal age. The mean portal venous velocity was still higher than the non-pregnant levels and did not showed significant alterations during puerperium. Conclusion: This study emphasised that, since pregnancy-induced alterations in hepatic venous pulsatility and portal venous velocity had not completely returned to normal in most cases until the end of the puerperium, these physiological changes should be considered whenever hepatic and portal systems are interpreted with Doppler sonography during the puerperal period

Maximum mass-particle velocities in Kantor's information mechanics

International Nuclear Information System (INIS)

Sverdlik, D.I.

1989-01-01

Kantor's information mechanics links phenomena previously regarded as not treatable by a single theory. It is used here to calculate the maximum velocities υ m of single particles. For the electron, υ m /c ∼ 1 - 1.253814 x 10 -77 . The maximum υ m corresponds to υ m /c ∼ 1 -1.097864 x 10 -122 for a single mass particle with a rest mass of 3.078496 x 10 -5 g. This is the fastest that matter can move. Either information mechanics or classical mechanics can be used to show that υ m is less for heavier particles. That υ m is less for lighter particles can be deduced from an information mechanics argument alone

Differential doppler heterodyning technique

DEFF Research Database (Denmark)

Lading, Lars

1971-01-01

Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating...

Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound.

Science.gov (United States)

Hotfiel, Thilo; Swoboda, Bernd; Krinner, Sebastian; Grim, Casper; Engelhardt, Martin; Uder, Michael; Heiss, Rafael U

2017-04-01

Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

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

Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers

OpenAIRE

Richard Billich; Jakub Štvrtňa; Karel Jelen

2015-01-01

Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers In today’s world of strength training there are many myths surrounding effective exercising with the least possible negative effect on one’s health. In this experiment we focus on the finding of a relationship between maximum output, used load and the velocity with which the exercise is performed. The main objective is to find the optimal speed of the exercise motion which would allow us to reach the ma...

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...

Doppler evaluation of valvular stenosis

International Nuclear Information System (INIS)

Kisslo, J.; Krafchek, J.; Adams, D.; Mark, D.B.

1986-01-01

One of the reasons why use of Doppler echocardiography is growing rapidly is because of its utility in detecting the presence of valvular stenosis and in estimating its severity. Detection of the presence of stenotic valvular heart disease using Doppler echocardiography was originally described over 10 years ago. It has been demonstrated that Doppler blood velocity data could be used to estimate the severity of a stenotic lesion. This chapter discusses the evaluation of valvular stenois using Doppler

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.

Comparisons between PW Doppler system and enhanced FM Doppler system

DEFF Research Database (Denmark)

Wilhjelm, Jens E.; Pedersen, P. C.

1995-01-01

This paper presents a new implementation of an echo-ranging FM Doppler system with improved performance, relative to the FM Doppler system reported previously. The use of long sweeps provides a significant reduction in peak to average power ratio compared to pulsed wave (PW) emission. A PW Doppler...... system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of the demodulated received signals, so that range is represented by frequency. Thus, a shift in location...... of moving scatterers between consecutive emissions corresponds to a frequency shift in the spectral signature. The improvement relative to the earlier version of the FM Doppler system is attained by utilizing cross-correlation of real spectra rather than of magnitude spectra for assessing flow velocity...

MP3 compression of Doppler ultrasound signals.

Science.gov (United States)

Poepping, Tamie L; Gill, Jeremy; Fenster, Aaron; Holdsworth, David W

2003-01-01

The effect of lossy, MP3 compression on spectral parameters derived from Doppler ultrasound (US) signals was investigated. Compression was tested on signals acquired from two sources: 1. phase quadrature and 2. stereo audio directional output. A total of 11, 10-s acquisitions of Doppler US signal were collected from each source at three sites in a flow phantom. Doppler signals were digitized at 44.1 kHz and compressed using four grades of MP3 compression (in kilobits per second, kbps; compression ratios in brackets): 1400 kbps (uncompressed), 128 kbps (11:1), 64 kbps (22:1) and 32 kbps (44:1). Doppler spectra were characterized by peak velocity, mean velocity, spectral width, integrated power and ratio of spectral power between negative and positive velocities. The results suggest that MP3 compression on digital Doppler US signals is feasible at 128 kbps, with a resulting 11:1 compression ratio, without compromising clinically relevant information. Higher compression ratios led to significant differences for both signal sources when compared with the uncompressed signals. Copyright 2003 World Federation for Ultrasound in Medicine & Biology

Application of two-component phase doppler interferometry to the measurement of particle size, mass flux, and velocities in two-phase flows

OpenAIRE

McDonell, VG; Samuelsen, GS

1989-01-01

The application of two-component interferometry is described for the spatially-resolved measurement of particle size, velocity and mass flux as well as continuous phase velocity. Such a capability is important to develop an understanding of the physical processes attendant to two-phase flow systems, especially those involving liquid atomization typical of a wide class of combustion systems. Adapted from laser anemometry, the technique (phase Doppler interferometry) measures single particle ev...

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)

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...... particle lter. This particle lter is able to run in an asynchronous manner to accommodate the measurement drop out problem, and it overcomes the measurement outliers by switching observation models. Simulations with experimental data show that this fault tolerant navigation system can accurately estimate...

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.).

Monitoring cerebral hemodynamics with transcranial Doppler ultrasound during cognitive and exercise testing in adults following unilateral stroke.

Science.gov (United States)

Watt, Brian P; Burnfield, Judith M; Truemper, Edward J; Buster, Thad W; Bashford, Gregory R

2012-01-01

An observational study was performed as a preliminary investigation into the use of transcranial Doppler ultrasound (TCD) for recording cerebral hemodynamic changes during multiple tasks. TCD is a method of measuring cerebral blood flow (CBF) using ultrasound transducers in contact with the surface of the head. Using the maximum flow envelope of the Doppler spectrum returning from the middle cerebral artery (MCA), standard clinical flow indices can be calculated and displayed in real time providing information concerning perturbations in CBF and their potential cause. These indices as well as flow velocity measurements have been recognized as useful in measuring changes in responses to various stimulus that can be used to indicate cardiovascular health. For this study, the pulsatility index (PI) and resistivity index (RI) were chosen since they indicate composite changes indicative of vasoconstriction and vasodilatation which are normal hemodynamic responses under appropriate conditions. A total of eleven participants were recruited to take part in this study. Nine of these individuals had no known disability (Controls); two had experienced unilateral cerebrovascular accidents (Strokes) in the ipsilateral MCA distribution. Maximum velocity envelopes of the spectral Doppler data were recorded using a fixation device designed to stabilize two ultrasound probes (2 MHz) to sample the bilateral MCAs CBF. These measures were performed separately while the subject performed four activities: 1) rest, 2) cognitive challenge, 3) cardiovascular exercise, and 4) simultaneous exercise and cognitive challenge. Cardiovascular parameters were calculated from the data by extracting maximum (Vs) and minimum flow velocities (Vd), PI, RI, and time signatures for each cardiac cycle. The data for all participants shows significant changes in cardiovascular parameters between states of rest and exercise, as well as slight trends across time. Although the data are preliminary, they show

Liquid velocity in upward and downward air-water flows

International Nuclear Information System (INIS)

Sun Xiaodong; Paranjape, Sidharth; Kim, Seungjin; Ozar, Basar; Ishii, Mamoru

2004-01-01

Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral laser Doppler anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void-weighted area-averaged drift velocity were obtained based on the definitions

Color Doppler flow mapping of stenotic and regurgitant natural heart valves

International Nuclear Information System (INIS)

Nanda, N.C.

1986-01-01

Color Doppler echocardiography has found widest application in reliable detection and assessment of severity of both atrio-ventricular and semi-lunar valve incompetence. The authors believe both the sensitivity and specificity of color Doppler for the detection of mitral and aortic regurgitation is very high in patients with adequate acoustic windows. In 82 patients with proven mitral regurgitation studied, the best correlations with angiography were noted when the maximum or average regurgitant jet are obtained by color Doppler from three standard 2-D echo planes (parasternal long and short axis and apical four chamber view) and expressed as a percentage of the left atrial area were considered. The criteria the authors used for assessment of tricuspid and pulmonary valve incompetence are similar to those used for mitral and aortic valve incompetence, but the lack of a good ''gold'' standard has hampered validation. The color Doppler technique also supplements conventional Doppler in the assessment of severity of stenotic lesions by facilitating parallel alignment of the continuous wave Doppler cursor line with the stenotic jet for accurate recording of maximal velocities and pressure gradients. The authors have found this method especially useful in the assessment of aortic stenosis. In conclusion, color Doppler flow mapping combined with conventional echocardiography provides, for the first time, a comprehensive noninvasive assessement of the severity of regurgitant and stenotic lesions

A new maximum likelihood blood velocity estimator incorporating spatial and temporal correlation

DEFF Research Database (Denmark)

Schlaikjer, Malene; Jensen, Jørgen Arendt

2001-01-01

and space. This paper presents a new estimator (STC-MLE), which incorporates the correlation property. It is an expansion of the maximum likelihood estimator (MLE) developed by Ferrara et al. With the MLE a cross-correlation analysis between consecutive RF-lines on complex form is carried out for a range...... of possible velocities. In the new estimator an additional similarity investigation for each evaluated velocity and the available velocity estimates in a temporal (between frames) and spatial (within frames) neighborhood is performed. An a priori probability density term in the distribution...... of the observations gives a probability measure of the correlation between the velocities. Both the MLE and the STC-MLE have been evaluated on simulated and in-vivo RF-data obtained from the carotid artery. Using the MLE 4.1% of the estimates deviate significantly from the true velocities, when the performance...

An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication.

Science.gov (United States)

MinhHai, Tran; Rie, Saotome; Suzuki, Taisaku; Wada, Tomohisa

2016-01-01

We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1) estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2) symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically.

Does the application of gadolinium-DTPA have an impact on magnetic resonance phase contrast velocity measurements? Results from an in vitro study

Energy Technology Data Exchange (ETDEWEB)

Heverhagen, J.T. E-mail: heverhag@post.med.uni-marburg.de; Hoppe, M.; Klose, K.-J.; Wagner, H.-J

2002-10-01

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<0.01; maximum pre-stenotic velocity: 21.6{+-}0.5 cm/s; maximum intra-stenotic velocity: 81.7{+-}0.6 cm/s). Following Gd-DTPA administration no significant (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.

Vega-1 and Vega-2: vertical profiles of wind velocity according to Doppler measurements data at landing spacecrafts

International Nuclear Information System (INIS)

Kerzhanovich, V.V.; Antsibor, N.M.; Bakit'ko, R.V.

1987-01-01

Results of the measurements of the Venus atmosphere vertical motion using the ''Vega'' landing spacecrafts are presented. Signal emitted by the landing spacecraft transmitter was received by flying apparatus and retranslated to the Earth. The difference between the measured frequency of the retranslated signal and reference one (Doppler's shift) permitted to determine the velocity of the landing spacecraft with the accuracy of 2 cm/s with the pitch of 1 s

Dual-Doppler Feasibility Study

Science.gov (United States)

Huddleston, Lisa L.

2012-01-01

When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

Validation of Transverse Oscillation Vector Velocity Estimation In-Vivo

DEFF Research Database (Denmark)

Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

2007-01-01

Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound (US) beam direction. This implies that a Doppler angle under examination close to 90deg results in unreliable information about the true blood direction and blood velocity. The novel...... the presented angle independent 2-D vector velocity method. The results give reason to believe that the TO method can be a useful alternative to conventional Doppler systems bringing forth new information to the US examination of blood flow....

Doppler sonographic evaluation of ophthalmic arterial flow pattern in hypertensive patients

International Nuclear Information System (INIS)

Ryu, Dae Sik; Kim, Young Goo

1994-01-01

To compare the Doppler velocity waveform pattern of ophthalmic artery of hypertensive patients with that of normotensive subjects. Doppler velocity waveform was obtained from ophthalmic artery in 45 hypertensive patients and 60 normotensive subjects. Both hypertensives and normotensive subjects were classified according to age into those younger than and those older than 45 years. Doppler indices(pulsatility index(PI), resistance index(RI), the first systolic peak/the second systolic peak(S1/S2), the first systolic peak/diastolic peak(S1/D)) measured in hypertensive patients were compared with normotensive subjects. Among the various doppler indices, only S1/S2 showed significant difference(P < 0.05) between the hypertensive patients and normotensive subjects younger than 45 years. Doppler velocity waveform of hypertensive patients older than 45 years showed no significant difference from that of normotensive subjects with corresponding age. Doppler velocity waveform of ophthalmic artery in hypertensive patients younger than 45 years shows pattern with S2 higher than that of normotensive subjects. High S2 component(reflective-wave) may represent increased vascular impedance due to vasococonstriction of retinal arterioles in hypertensive patients

Hydroxyurea lowers transcranial Doppler flow velocities in children with sickle cell anaemia in a Nigerian cohort.

Science.gov (United States)

Lagunju, IkeOluwa; Brown, Biobele J; Sodeinde, Olugbemiro

2015-09-01

Sickle cell anaemia (SCA) is the leading genetic disorder in Nigeria. Elevated velocities ≥170 cm/sec occur in about a third of Nigerian children with SCA. Chronic blood transfusion for stroke prevention is faced with a myriad of challenges in our practice. To evaluate the effectiveness of hydroxyurea (HU) in reducing flow velocities in a cohort of Nigerian children with SCA and elevated velocities treated with HU. An observational study was carried out on a cohort of Nigerian children with SCA and elevated velocities identified on routine transcranial Doppler (TCD) screening. HU was recommended in those with TCD velocities ≥ 170cm/sec as stipulated in our hospital protocol. Outcomes were compared after ≥12 months of observation. Fifty children with elevated TCD velocities were studied; 31 consented to HU therapy and 19 declined. Children on HU showed a statistically significant decline in mean velocities from 199.7 [17.1] cm/sec to 165.8 [20.7] cm/sec (P < 0.001) with a significant increase in mean packed cell volume from 21.1 [3.4] to 25.0 [2.8]%. Children without treatment had a significant rise in mean velocities from 190.2 [10.8] cm/sec to 199.7 [14.9] cm/sec (P = 0.003). Children with conditional risk velocities on HU were less likely to convert to abnormal risk (P < 0.001). Two stroke events occurred, one in each group. No adverse effects of HU were recorded in the cohort. HU appears to significantly reduce TCD velocities in Nigerian children with SCA and elevated velocities ≥170 cm/sec with beneficial effect on the haematological profile. HU may provide an effective approach to primary stroke prevention, particularly in Africa. © 2015 Wiley Periodicals, Inc.

Monodimensional estimation of maximum Reynolds shear stress in the downstream flow field of bileaflet valves.

Science.gov (United States)

Grigioni, Mauro; Daniele, Carla; D'Avenio, Giuseppe; Barbaro, Vincenzo

2002-05-01

Turbulent flow generated by prosthetic devices at the bloodstream level may cause mechanical stress on blood particles. Measurement of the Reynolds stress tensor and/or some of its components is a mandatory step to evaluate the mechanical load on blood components exerted by fluid stresses, as well as possible consequent blood damage (hemolysis or platelet activation). Because of the three-dimensional nature of turbulence, in general, a three-component anemometer should be used to measure all components of the Reynolds stress tensor, but this is difficult, especially in vivo. The present study aimed to derive the maximum Reynolds shear stress (RSS) in three commercially available prosthetic heart valves (PHVs) of wide diffusion, starting with monodimensional data provided in vivo by echo Doppler. Accurate measurement of PHV flow field was made using laser Doppler anemometry; this provided the principal turbulence quantities (mean velocity, root-mean-square value of velocity fluctuations, average value of cross-product of velocity fluctuations in orthogonal directions) needed to quantify the maximum turbulence-related shear stress. The recorded data enabled determination of the relationship, the Reynolds stresses ratio (RSR) between maximum RSS and Reynolds normal stress in the main flow direction. The RSR was found to be dependent upon the local structure of the flow field. The reported RSR profiles, which permit a simple calculation of maximum RSS, may prove valuable during the post-implantation phase, when an assessment of valve function is made echocardiographically. Hence, the risk of damage to blood constituents associated with bileaflet valve implantation may be accurately quantified in vivo.

Is the measurement of inferior thyroid artery blood flow velocity by color-flow Doppler ultrasonography useful for differential diagnosis between gestational transient thyrotoxicosis and Graves' disease? A prospective study.

Science.gov (United States)

Zuhur, Sayid Shafi; Ozel, Alper; Velet, Selvinaz; Buğdacı, Mehmet Sait; Cil, Esra; Altuntas, Yüksel

2012-01-01

To determine the role of peak systolic velocity, end-diastolic velocity and resistance indices of both the right and left inferior thyroid arteries measured by color-flow Doppler ultrasonography for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy. The right and left inferior thyroid artery-peak systolic velocity, end-diastolic velocity and resistance indices of 96 patients with thyrotoxicosis (41 with gestational transient thyrotoxicosis, 31 age-matched pregnant patients with Graves' disease and 24 age- and sex-matched non-pregnant patients with Graves' disease) and 25 age and sex-matched healthy euthyroid subjects were assessed with color-flow Doppler ultrasonography. The right and left inferior thyroid artery-peak systolic and end-diastolic velocities in patients with gestational transient thyrotoxicosis were found to be significantly lower than those of pregnant patients with Graves' disease and higher than those of healthy euthyroid subjects. However, the right and left inferior thyroid artery peak systolic and end-diastolic velocities in pregnant patients with Graves' disease were significantly lower than those of non-pregnant patients with Graves' disease. The right and left inferior thyroid artery peak systolic and end-diastolic velocities were positively correlated with TSH-receptor antibody levels. We found an overlap between the inferior thyroid artery-blood flow velocities in a considerable number of patients with gestational transient thyrotoxicosis and pregnant patients with Graves' disease. This study suggests that the measurement of inferior thyroid artery-blood flow velocities with color-flow Doppler ultrasonography does not have sufficient sensitivity and specificity to be recommended as an initial diagnostic test for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy.

Three-dimensional imaging of absolute blood flow velocity and blood vessel position under low blood flow velocity based on Doppler signal information included in scattered light from red blood cells

Science.gov (United States)

Kyoden, Tomoaki; Akiguchi, Shunsuke; Tajiri, Tomoki; Andoh, Tsugunobu; Hachiga, Tadashi

2017-11-01

The development of a system for in vivo visualization of occluded distal blood vessels for diabetic patients is the main target of our research. We herein describe two-beam multipoint laser Doppler velocimetry (MLDV), which measures the instantaneous multipoint flow velocity and can be used to observe the blood flow velocity in peripheral blood vessels. By including a motorized stage to shift the measurement points horizontally and in the depth direction while measuring the velocity, the path of the blood vessel in the skin could be observed using blood flow velocity in three-dimensional space. The relationship of the signal power density between the blood vessel and the surrounding tissues was shown and helped us identify the position of the blood vessel. Two-beam MLDV can be used to simultaneously determine the absolute blood flow velocity distribution and identify the blood vessel position in skin.

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.

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.

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.

An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication

Directory of Open Access Journals (Sweden)

Tran MinhHai

2016-01-01

Full Text Available We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1 estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2 symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically.

An Acoustic OFDM System with Symbol-by-Symbol Doppler Compensation for Underwater Communication

Science.gov (United States)

MinhHai, Tran; Rie, Saotome; Suzuki, Taisaku; Wada, Tomohisa

2016-01-01

We propose an acoustic OFDM system for underwater communication, specifically for vertical link communications such as between a robot in the sea bottom and a mother ship in the surface. The main contributions are (1) estimation of time varying Doppler shift using continual pilots in conjunction with monitoring the drift of Power Delay Profile and (2) symbol-by-symbol Doppler compensation in frequency domain by an ICI matrix representing nonuniform Doppler. In addition, we compare our proposal against a resampling method. Simulation and experimental results confirm that our system outperforms the resampling method when the velocity changes roughly over OFDM symbols. Overall, experimental results taken in Shizuoka, Japan, show our system using 16QAM, and 64QAM achieved a data throughput of 7.5 Kbit/sec with a transmitter moving at maximum 2 m/s, in a complicated trajectory, over 30 m vertically. PMID:27057558

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.

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...

Marked Increase in Flow Velocities During Deep Expiration: A Duplex Doppler Sign of Celiac Artery Compression Syndrome

International Nuclear Information System (INIS)

Erden, Ayse; Yurdakul, Mehmet; Cumhur, Turhan

1999-01-01

Symptoms of chronic mesenteric ischemia develop when the celiac artery is constricted by the median arcuate ligament of the diaphragm. Lateral aortography is the primary modality for diagnosing ligamentous compression of the celiac artery. However, duplex Doppler sonography performed during deep expiration can cause a marked increase in flow velocities at the compressed region of the celiac artery and suggest the diagnosis of celiac arterial constriction due to the diaphragmatic ligament. RID='''' ID='''' Correspondence to: A. Erden, M.D., Hafta sokak. 23/6, Gaziosmanpasa, 06700 Ankara, Turkey

Reconstruction of Typhoon Structure Using 3-Dimensional Doppler Radar Radial Velocity Data with the Multigrid Analysis: A Case Study in an Idealized Simulation Context

Directory of Open Access Journals (Sweden)

Hongli Fu

2016-01-01

Full Text Available Extracting multiple-scale observational information is critical for accurately reconstructing the structure of mesoscale circulation systems such as typhoon. The Space and Time Mesoscale Analysis System (STMAS with multigrid data assimilation developed in Earth System Research Laboratory (ESRL in National Oceanic and Atmospheric Administration (NOAA has addressed this issue. Previous studies have shown the capability of STMAS to retrieve multiscale information in 2-dimensional Doppler radar radial velocity observations. This study explores the application of 3-dimensional (3D Doppler radar radial velocities with STMAS for reconstructing a 3D typhoon structure. As for the first step, here, we use an idealized simulation framework. A two-scale simulated “typhoon” field is constructed and referred to as “truth,” from which randomly distributed conventional wind data and 3D Doppler radar radial wind data are generated. These data are used to reconstruct the synthetic 3D “typhoon” structure by the STMAS and the traditional 3D variational (3D-Var analysis. The degree by which the “truth” 3D typhoon structure is recovered is an assessment of the impact of the data type or analysis scheme being evaluated. We also examine the effects of weak constraint and strong constraint on STMAS analyses. Results show that while the STMAS is superior to the traditional 3D-Var for reconstructing the 3D typhoon structure, the strong constraint STMAS can produce better analyses on both horizontal and vertical velocities.

Demonstration of a Vector Velocity Technique

DEFF Research Database (Denmark)

Hansen, Peter Møller; Pedersen, Mads M.; Hansen, Kristoffer L.

2011-01-01

With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa......With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60–70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner...

Maximum Likelihood-Based Methods for Target Velocity Estimation with Distributed MIMO Radar

Directory of Open Access Journals (Sweden)

Zhenxin Cao

2018-02-01

Full Text Available The estimation problem for target velocity is addressed in this in the scenario with a distributed multi-input multi-out (MIMO radar system. A maximum likelihood (ML-based estimation method is derived with the knowledge of target position. Then, in the scenario without the knowledge of target position, an iterative method is proposed to estimate the target velocity by updating the position information iteratively. Moreover, the Carmér-Rao Lower Bounds (CRLBs for both scenarios are derived, and the performance degradation of velocity estimation without the position information is also expressed. Simulation results show that the proposed estimation methods can approach the CRLBs, and the velocity estimation performance can be further improved by increasing either the number of radar antennas or the information accuracy of the target position. Furthermore, compared with the existing methods, a better estimation performance can be achieved.

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....

Use of Doppler ultrasound for non-invasive urodynamic diagnosis

Directory of Open Access Journals (Sweden)

Hideo Ozawa

2009-01-01

Full Text Available Objectives: A totally non-invasive transperineal urodynamic technique using Doppler ultrasonography has been developed. Methods: Since normal urine does not have blood cells, urine was thought not to produce the Doppler effects. However, basic studies confirmed that the decrease of pressure at high velocity (Bernouilli effect caused dissolved gas to form microbubbles, which are detected by Doppler ultrasonography. Subjects sat and the probe was advanced via remote control to achieve gentle contact with the perineal skin. The digital uroflow data signals and the color Doppler ultrasound video images were processed on a personal computer. The flow-velocity curves from two sites; the distal prostatic urethra just above the external sphincter (V1 and the sphincteric urethra (V2 were plotted against time. The parameters of both the pressure-flow studies and the Doppler ultrasound urodynamic studies were compared in men who had various degrees of obstruction. Results: Functional cross-sectional area at prostatic urethra (A1, calculated by Q max /V1, was lower in the group of bladder outlet obstruction (BOO vs. control group. Velocity ratio (VR, which was calculated by V1/V2, was the parameter having the best correlation with BOO index, though A1 had a similar correlation. This method is viable to diagnose the degree of BOO. Conclusions: The development of non-invasive Doppler ultrasound videourodynamics (Doppler UDS will dramatically expand the information on voiding function.

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...... indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative velocity information....

Study on Droplet Size and Velocity Distributions of a Pressure Swirl Atomizer Based on the Maximum Entropy Formalism

Directory of Open Access Journals (Sweden)

Kai Yan

2015-01-01

Full Text Available A predictive model for droplet size and velocity distributions of a pressure swirl atomizer has been proposed based on the maximum entropy formalism (MEF. The constraint conditions of the MEF model include the conservation laws of mass, momentum, and energy. The effects of liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio on the droplet size and velocity distributions of a pressure swirl atomizer are investigated. Results show that model based on maximum entropy formalism works well to predict droplet size and velocity distributions under different spray conditions. Liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio have different effects on droplet size and velocity distributions of a pressure swirl atomizer.

Validation of Patient-Specific Cerebral Blood Flow Simulation Using Transcranial Doppler Measurements

Directory of Open Access Journals (Sweden)

Derek Groen

2018-06-01

Full Text Available We present a validation study comparing results from a patient-specific lattice-Boltzmann simulation to transcranial Doppler (TCD velocity measurements in four different planes of the middle cerebral artery (MCA. As part of the study, we compared simulations using a Newtonian and a Carreau-Yasuda rheology model. We also investigated the viability of using downscaled velocities to reduce the required resolution. Simulations with unscaled velocities predict the maximum flow velocity with an error of less than 9%, independent of the rheology model chosen. The accuracy of the simulation predictions worsens considerably when simulations are run at reduced velocity, as is for example the case when inflow velocities from healthy individuals are used on a vascular model of a stroke patient. Our results demonstrate the importance of using directly measured and patient-specific inflow velocities when simulating blood flow in MCAs. We conclude that localized TCD measurements together with predictive simulations can be used to obtain flow estimates with high fidelity over a larger region, and reduce the need for more invasive flow measurement procedures.

Analysis of multiple scattering effects in optical Doppler tomography

DEFF Research Database (Denmark)

Yura, H.T.; Thrane, L.; Andersen, Peter E.

2005-01-01

Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where...... multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed...

Experimental study on liquid velocity in upward and downward two-phase flows

International Nuclear Information System (INIS)

Sun, X.; Paranjape, S.; Kim, S.; Ozar, B.; Ishii, M.

2003-01-01

Local characteristics of the liquid phase in upward and downward air-water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral Laser Doppler Anemometry (LDA) system was used to measure the axial liquid velocity and its fluctuations. No effect of the flow direction on the liquid velocity radial profile was observed in single-phase liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the liquid velocity radial profile, and the maximum liquid velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum liquid velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void weighted area-averaged drift velocity were obtained based on the definitions

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...

High-frequency Doppler ultrasound transducer for the peripheral circulatory system

Energy Technology Data Exchange (ETDEWEB)

Bae, Youngmin; Yang, Jeongwon; Kang, Uk; Kim, Guanghoon [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of)

2011-12-15

A Doppler ultrasound transducer was designed and implemented to measure the blood flow velocity in tiny vessels near the skin of hands or feet. The geometric parameters of the transducer for defining the observation volume were derived and implemented with an acoustic window made of polystyrene. The observation volume designed in this study was located 6.5 mm from the transducer, which was comparable to the value predicted geometrically. The two-way insertion loss of the transducer was -11.3 dB on ultrasound frequency of 20 MHz, and the 3-dB bandwidth was approximately 2 MHz. In addition, the Doppler shift in the frequency measured by using a Doppler device composed of the transducer and a Doppler signal processing unit was proportional to the flow velocity generated by a homemade flowing system. Finally, we concluded that the transducer could be applied to measure the blood flow velocity in hands or feet.

High-frequency Doppler ultrasound transducer for the peripheral circulatory system

International Nuclear Information System (INIS)

Bae, Youngmin; Yang, Jeongwon; Kang, Uk; Kim, Guanghoon

2011-01-01

A Doppler ultrasound transducer was designed and implemented to measure the blood flow velocity in tiny vessels near the skin of hands or feet. The geometric parameters of the transducer for defining the observation volume were derived and implemented with an acoustic window made of polystyrene. The observation volume designed in this study was located 6.5 mm from the transducer, which was comparable to the value predicted geometrically. The two-way insertion loss of the transducer was -11.3 dB on ultrasound frequency of 20 MHz, and the 3-dB bandwidth was approximately 2 MHz. In addition, the Doppler shift in the frequency measured by using a Doppler device composed of the transducer and a Doppler signal processing unit was proportional to the flow velocity generated by a homemade flowing system. Finally, we concluded that the transducer could be applied to measure the blood flow velocity in hands or feet.

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

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

Doppler ultrasound study of penis in men with systemic sclerosis: a correlation with Doppler indices of renal and digital arteries.

Science.gov (United States)

Rosato, E; Barbano, B; Gigante, A; Cianci, R; Molinaro, I; Quarta, S; Digiulio, M A; Messineo, D; Pisarri, S; Salsano, F

2013-01-01

Erectile dysfunction (ED) prevalence in male systemic sclerosis (SSc) is high and its pathogenesis is unclear. The aim of the study is to assess correlation between Doppler ultrasound indices of penis and kidneys or digital arteries in male systemic sclerosis. Fourteen men with systemic sclerosis were enrolled in this study. Erectile function was investigated by the International Index of Erectile Function-5. Peak systolic velocity, end diastolic velocity, resistive index, pulsative index, and systolic/diastolic ratio were measured on the cavernous arteries at the peno-scrotal junction in the flaccid state, on the interlobar artery of both kidneys and all ten proper palmar digital arteries. Ten (71 percent) patients have an International Index of Erectile Function-5 less than 21. Reduction of penis peak systolic velocity was observed in all SSc subjects. Doppler indices of cavernous arteries correlate with the International Index of Erectile Function-5. The renal and digital arteries resistive index demonstrated a good correlation (p less than 0.0001) with International Index of Erectile Function-5. A positive correlation exists between penis and kidney arteries Doppler indices: end diastolic velocity (p less than 0.05, r=0.54), resistive index (p less than 0.0001, r=0.90), systolic/diastolic ratio (p less than 0.01, r=0.69). A positive correlation was observed between penis and digital arteries Doppler indices: peak systolic velocity (p less than 0.01, r=0.68), end diastolic velocity (p less than 0.01, r=0.75), resistive index (p less than 0.001, r=0.79), systolic/diastolic ratio (p less than 0.05, r=0.59). A correlation exists between arterial impairment of penis and renal or digital arteries.

EFFECTS OF A SAND RUNNING SURFACE ON THE KINEMATICS OF SPRINTING AT MAXIMUM VELOCITY

Directory of Open Access Journals (Sweden)

P E Alcaraz

2011-05-01

Full Text Available Performing sprints on a sand surface is a common training method for improving sprint-specific strength. For maximum specificity of training the athlete’s movement patterns during the training exercise should closely resemble those used when performing the sport. The aim of this study was to compare the kinematics of sprinting at maximum velocity on a dry sand surface to the kinematics of sprinting on an athletics track. Five men and five women participated in the study, and flying sprints over 30 m were recorded by video and digitized using biomechanical analysis software. We found that sprinting on a sand surface was substantially different to sprinting on an athletics track. When sprinting on sand the athletes tended to ‘sit’ during the ground contact phase of the stride. This action was characterized by a lower centre of mass, a greater forward lean in the trunk, and an incomplete extension of the hip joint at take-off. We conclude that sprinting on a dry sand surface may not be an appropriate method for training the maximum velocity phase in sprinting. Although this training method exerts a substantial overload on the athlete, as indicated by reductions in running velocity and stride length, it also induces detrimental changes to the athlete’s running technique which may transfer to competition sprinting.

Pulsed-wave tissue Doppler and color tissue Doppler echocardiography: calibration with M-mode, agreement, and reproducibility in a clinical setting

DEFF Research Database (Denmark)

Olsen, Niels Thue; Jons, Christian; Fritz-Hansen, Thomas

2009-01-01

BACKGROUND: Myocardial velocities can be measured with both pulsed-wave tissue Doppler (PWTD) and color tissue Doppler (CTD) echocardiography. We aimed to (A) to explore which of the two methods better approximates true tissue motion and (B) to examine the agreement and the reproducibility...... of the two methods in a routine clinical setting. METHODS: For Study A, the displacements of 63 basal myocardial segments from 13 patients were examined with M-mode and compared with the velocity-time integral of PWTD and CTD velocities. For Study B, the basal lateral segments from 58 patients were examined...... with PWTD and CTD, and the peak myocardial velocities during systole (Sm), early diastole (Em), and late diastole (Am) were measured. RESULTS: Study A: CTD-based measurements of displacement were 12% lower than M-mode measurements (95% CI: -18%; -6%). PWTD velocity-time integrals measured at the outer edge...

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.

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.

Doppler-guided retrograde catheterization system

Science.gov (United States)

Frazin, Leon J.; Vonesh, Michael J.; Chandran, Krishnan B.; Khasho, Fouad; Lanza, George M.; Talano, James V.; McPherson, David D.

1991-05-01

The purpose of this study was to investigate a Doppler guided catheterization system as an adjunctive or alternative methodology to overcome the disadvantages of left heart catheterization and angiography. These disadvantages include the biological effects of radiation and the toxic and volume effects of iodine contrast. Doppler retrograde guidance uses a 20 MHz circular pulsed Doppler crystal incorporated into the tip of a triple lumen multipurpose catheter and is advanced retrogradely using the directional flow information provided by the Doppler waveform. The velocity detection limits are either 1 m/second or 4 m/second depending upon the instrumentation. In a physiologic flow model of the human aortic arch, multiple data points revealed a positive wave form when flow was traveling toward the catheter tip indicating proper alignment for retrograde advancement. There was a negative wave form when flow was traveling away from the catheter tip if the catheter was in a branch or bent upon itself indicating improper catheter tip position for retrograde advancement. In a series of six dogs, the catheter was able to be accurately advanced from the femoral artery to the left ventricular chamber under Doppler signal guidance without the use of x-ray. The potential applications of a Doppler guided retrograde catheterization system include decreasing time requirements and allowing safer catheter guidance in patients with atherosclerotic vascular disease and suspected aortic dissection. The Doppler system may allow left ventricular pressure monitoring in the intensive care unit without the need for x-ray and it may allow left sided contrast echocardiography. With pulse velocity detection limits of 4 m/second, this system may allow catheter direction and passage into the aortic root and left ventricle in patients with aortic stenosis. A modification of the Doppler catheter may include transponder technology which would allow precise catheter tip localization once the

Glare Spot Phase Doppler Anemometry

OpenAIRE

Hespel, Camille; Ren, Kuan Fang; Gréhan, Gérard; Onofri, Fabrice

2006-01-01

International audience; The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index is also necessary since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemo...

Multimodal quantitation of the effects of endovascular therapy for vasospasm on cerebral blood flow, transcranial doppler ultrasonographic velocities, and cerebral artery diameters.

Science.gov (United States)

Oskouian, Rod J; Martin, Neil A; Lee, Jae Hong; Glenn, Thomas C; Guthrie, Donald; Gonzalez, Nestor R; Afari, Arash; Viñuela, Fernando

2002-07-01

The goal of this study was to quantify the effects of endovascular therapy on vasospastic cerebral vessels. We reviewed the medical records for 387 patients with ruptured intracranial aneurysms who were treated at a single institution (University of California, Los Angeles) between May 1, 1993, and March 31, 2001. Patients who developed cerebral vasospasm and underwent cerebral arteriographic, transcranial Doppler ultrasonographic, and cerebral blood flow (CBF) studies before and after endovascular therapy for cerebral arterial spasm (vasospasm) were included in this study. Forty-five patients fulfilled the aforementioned criteria and were treated with either papaverine infusion, papaverine infusion with angioplasty, or angioplasty alone. After balloon angioplasty (12 patients), CBF increased from 27.8 +/- 2.8 ml/100 g/min to 28.4 +/- 3.0 ml/100 g/min (P = 0.87); the middle cerebral artery blood flow velocity was 1 57.6 +/- 9.4 cm/s and decreased to 76.3 +/- 9.3 cm/s (P < 0.05), with a mean increase in cerebral artery diameters of 24.4%. Papaverine infusion (20 patients) transiently increased the CBF from 27.5 +/- 2.1 ml/100 g/min to 38.7 +/- 2.8 ml/100 g/min (P < 0.05) and decreased the middle cerebral artery blood flow velocity from 109.9 +/- 9.1 cm/s to 82.8 +/- 8.6 cm/s (P < 0.05). There was a mean increase in vessel diameters of 30.1% after papaverine infusion. Combined treatment (13 patients) significantly increased the CBF from 33.3 +/- 3.2 ml/100 g/min to 41.7 +/- 2.8 ml/100 g/min (P< 0.05) and decreased the transcranial Doppler velocities from 148.9 +/- 12.7 cm/s to 111.4 +/- 10.6 cm/s (P < 0.05), with a mean increase in vessel diameters of 42.2%. Balloon angioplasty increased proximal vessel diameters, whereas papaverine treatment effectively dilated distal cerebral vessels. In our small series, we observed no correlation between early clinical improvement or clinical outcomes and any of our quantitative or physiological data (CBF, transcranial Doppler

Predicting the Maximum Dynamic Strength in Bench Press: The High Precision of the Bar Velocity Approach.

Science.gov (United States)

Loturco, Irineu; Kobal, Ronaldo; Moraes, José E; Kitamura, Katia; Cal Abad, César C; Pereira, Lucas A; Nakamura, Fábio Y

2017-04-01

Loturco, I, Kobal, R, Moraes, JE, Kitamura, K, Cal Abad, CC, Pereira, LA, and Nakamura, FY. Predicting the maximum dynamic strength in bench press: the high precision of the bar velocity approach. J Strength Cond Res 31(4): 1127-1131, 2017-The aim of this study was to determine the force-velocity relationship and test the possibility of determining the 1 repetition maximum (1RM) in "free weight" and Smith machine bench presses. Thirty-six male top-level athletes from 3 different sports were submitted to a standardized 1RM bench press assessment (free weight or Smith machine, in randomized order), following standard procedures encompassing lifts performed at 40-100% of 1RM. The mean propulsive velocity (MPV) was measured in all attempts. A linear regression was performed to establish the relationships between bar velocities and 1RM percentages. The actual and predicted 1RM for each exercise were compared using a paired t-test. Although the Smith machine 1RM was higher (10% difference) than the free weight 1RM, in both cases the actual and predicted values did not differ. In addition, the linear relationship between MPV and percentage of 1RM (coefficient of determination ≥95%) allow determination of training intensity based on the bar velocity. The linear relationships between the MPVs and the relative percentages of 1RM throughout the entire range of loads enable coaches to use the MPV to accurately monitor their athletes on a daily basis and accurately determine their actual 1RM without the need to perform standard maximum dynamic strength assessments.

Korea-China Joint R and D on Doppler Lidar Technology

International Nuclear Information System (INIS)

Cha, Hyung Ki; Kim, D. H.; Kwon, S. O.; Yang, K. H.; Song, I. K.

2009-03-01

Doppler lidar technology is to monitor atmospheric wind velocity by measuring the light scattering signals between a laser and aerosol particles or molecules existing in the atmosphere. When the particles (or molecules) in the atmosphere are moving by wind force, the frequency of backscattering light is shifted by doppler effect, so that the wind velocity profile can be obtained by measurement of the shifted frequencies. When the laser radiation is scanned in four different direction, three dimensional wind profiles are obtained. The Anhui Institute of Optics and Fine Mechanics under the China Academy of Sciences has developed and operated the doppler lidar system for long time. In this project we want to developed a new technologies adopted to the chinese doppler system and to test the updated In the process of collaboration between China and Korea research teams, we want to learn the state-of-art technology involved in the doppler lidar system

Technical Note: A new phantom design for routine testing of Doppler ultrasound.

Science.gov (United States)

Grice, J V; Pickens, D R; Price, R R

2016-07-01

The objective of this project is to demonstrate the principle and operation for a simple, inexpensive, and highly portable Doppler ultrasound quality assurance (QA) phantom intended for routine QA testing. A prototype phantom has been designed, fabricated, and evaluated. The phantom described here is powered by gravity alone, requires no external equipment for operation, and produces a stable fluid velocity useful for quality assurance. Many commercially available Doppler ultrasound testing systems can suffer from issues such as a lengthy setup, prohibitive cost, nonportable size, or difficulty in use. This new phantom design aims to address some of these problems and create a phantom appropriate for assessing Doppler ultrasound stability. The phantom was fabricated using a 3D printer. The basic design of the phantom is to provide gravity-powered flow of a Doppler fluid between two reservoirs. The printed components were connected with latex tubing and then seated in a tissue mimicking gel. Spectral Doppler waveforms were sampled to evaluate variations in the data, and the phantom was evaluated using high frame rate video to find an alternate measure of mean fluid velocity flowing in the phantom. The current system design maintains stable flow from one reservoir to the other for approximately 7 s. Color Doppler imaging of the phantom was found to be qualitatively consistent with laminar flow. Using pulsed spectral Doppler, the average fluid velocity from a sample volume approximately centered in the synthetic vessel was measured to be 56 cm/s with a standard deviation of 3.2 cm/s across 118 measurements. An independent measure of the average fluid velocity was measured to be 51.9 cm/s with a standard deviation of 0.7 cm/s over 4 measurements. The developed phantom provides stable fluid flow useful for frequent clinical Doppler ultrasound testing and attempts to address several obstacles facing Doppler phantom testing. Such an ultrasound phantom can make routine

Characterization of Medication Velocity and Size Distribution from Pressurized Metered-Dose Inhalers by Phase Doppler Anemometry.

Science.gov (United States)

Alatrash, Abubaker; Matida, Edgar

2016-12-01

Particle size and velocity are two of the most significant factors that impact the deposition of pressurized metered-dose inhaler (pMDI) sprays in the mouth cavity. pMDIs are prominently used around the world in the treatment of patients suffering from a variety of lung diseases such as asthma and chronic obstructive pulmonary disease. Since their introduction in the field, and as a result of their effectiveness and simplicity of usage, pMDIs are considered to be the most widely prescribed medical aerosol delivery system. In the current study, particle velocity and size distribution were measured at three different locations along the centerline of a pMDI spray using Phase Doppler Anemometry. pMDIs from four different pharmaceutical companies were tested, each using salbutamol sulfate as the medication. Measurements along at the pMDI centerline (at 0, 75, and 100 mm downstream of the inhaler mouthpiece) showed that the spray velocities were bimodal in time for all four pMDI brands. The first peak occurred as the spray was leaving the mouthpiece, while the second peak (at the same location, 0 mm) occurred at around 60, 95, 95, and 115 milliseconds later, respectively, for the four tested inhalers, with a drop in the velocity between the two peaks. Three probability density functions (PDFs) were tested, and the Rosin-Rammler PDF best fit the empirical data, as determined using a chi-squared test. These results suggest that there is a difference in the mean particle velocities at the centerline for the tested pMDIs and the diameter of released particles varied statistically for each brand.

In vivo visualization method by absolute blood flow velocity based on speckle and fringe pattern using two-beam multipoint laser Doppler velocimetry

Energy Technology Data Exchange (ETDEWEB)

Kyoden, Tomoaki, E-mail: kyouden@nc-toyama.ac.jp; Naruki, Shoji; Akiguchi, Shunsuke; Momose, Noboru; Homae, Tomotaka; Hachiga, Tadashi [National Institute of Technology, Toyama College, 1-2 Ebie-Neriya, Imizu, Toyama 933-0293 (Japan); Ishida, Hiroki [Department of Applied Physics, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005 (Japan); Andoh, Tsugunobu [Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194 (Japan); Takada, Yogo [Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi, Osaka 558-8585 (Japan)

2016-08-28

Two-beam multipoint laser Doppler velocimetry (two-beam MLDV) is a non-invasive imaging technique able to provide an image of two-dimensional blood flow and has potential for observing cancer as previously demonstrated in a mouse model. In two-beam MLDV, the blood flow velocity can be estimated from red blood cells passing through a fringe pattern generated in the skin. The fringe pattern is created at the intersection of two beams in conventional LDV and two-beam MLDV. Being able to choose the depth position is an advantage of two-beam MLDV, and the position of a blood vessel can be identified in a three-dimensional space using this technique. Initially, we observed the fringe pattern in the skin, and the undeveloped or developed speckle pattern generated in a deeper position of the skin. The validity of the absolute velocity value detected by two-beam MLDV was verified while changing the number of layers of skin around a transparent flow channel. The absolute velocity value independent of direction was detected using the developed speckle pattern, which is created by the skin construct and two beams in the flow channel. Finally, we showed the relationship between the signal intensity and the fringe pattern, undeveloped speckle, or developed speckle pattern based on the skin depth. The Doppler signals were not detected at deeper positions in the skin, which qualitatively indicates the depth limit for two-beam MLDV.

Poststenotic flow disturbance in the dog aorta as measured with pulsed Doppler ultrasound.

Science.gov (United States)

Talukder, N; Fulenwider, J T; Mabon, R F; Giddens, D P

1986-08-01

Blood flow velocity was measured in the dog aorta distal to mechanically induced constrictions of various degrees of severity employing an 8-MHz pulsed Doppler ultrasound velocimeter and a phase-lock loop frequency tracking method for extracting velocity from the Doppler quadrature signals. The data were analyzed to construct ensemble average velocity waveforms and random velocity disturbances. In any individual animal the effect of increasing the degree of stenosis beyond approximately 25 percent area reduction was to produce increasing levels of random velocity disturbance. However, variability among animals was such that the sensitivity of random behavior to the degree of stenosis was degraded to the point that it appears difficult to employ Doppler ultrasound measurements of random disturbances to discriminate among stenoses with area reductions less than approximately 75 percent. On the other hand, coherent vortex structures in velocity waveforms consistently occurred distal to mild constrictions (25-50 percent area reduction). Comparison of the phase-lock loop Doppler ultrasound data with simultaneous measurements using invasive hot-film anemometry, which possesses excellent frequency response, demonstrates that the ultrasound method can reliably detect those flow phenomena in such cases. Thus, the identification of coherent, rather than random, flow disturbances may offer improved diagnostic capability for noninvasively detecting arteriosclerotic plaques at relatively early stages of development.

Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

International Nuclear Information System (INIS)

Erskine, D J; Edelstein, J; Lloyd, J; Muirhead, P

2006-01-01

Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio

A Fabry-Perot interferometer system for high-speed velocity measurement

NARCIS (Netherlands)

Cheng, L.K.; Bruinsma, A.J.A.; Prinse, W.C.; Smorenburg, C.

1997-01-01

The Fabry-Perot Velocity Interferometer System (F-PVIS) is designed and built for measuring the Doppler shift of light by recording positional changes in the interferometric pattern behind the Fabry-Perot interferometer. The velocity of a surface can be deduced from the Doppler shift which is caused

Assessment of ureterovesical jet dynamics in obstructed ureter by urinary stone with color Doppler and duplex Doppler examinations.

Science.gov (United States)

Jandaghi, Ali Babaei; Falahatkar, Siavash; Alizadeh, Ahmad; Kanafi, Alireza Rajabzadeh; Pourghorban, Ramin; Shekarchi, Babak; Zirak, Amin Keshavarz; Esmaeili, Samaneh

2013-04-01

This study was designed to evaluate ureterovesical jet dynamics in obstructed ureter and to compare it with those of contralateral unobstructed side. Forty-six patients with diagnosis of ureteral stone, based on imaging findings in computed tomography were enrolled in this study. The gray-scale ultrasound exam from both kidneys and urinary bladder was performed. Then, ureterovesical jet characteristics including ureteral jet frequency, duration and peak velocity were assessed by color Doppler and duplex Doppler studies in both obstructed and unobstructed ureters by a radiologist, 15-30 min after oral hydration with 750-1,000 mL of water. When compared with contralateral normal side, the ureterovesical jet in obstructed ureter showed less frequency (0.59 vs. 3.04 jets/min; P < 0.05), shorter duration (1.24 vs. 5.26 s; P < 0.05) and lower peak velocity (5.41 vs. 32.09 cm/s; P < 0.05). The cut-off points of 1.5 jets/min, 2.5 s and 19.5 cm/s for difference of ureteral jet frequency, duration and peak velocity between obstructed and contralateral normal ureters yielded sensitivities of 97.8, 95.6 and 100 % and specificities of 87, 87.9 and 97.8 %, respectively for diagnosis of ureteral obstruction. Given the safety of Doppler study and significant differences in flow dynamics of obstructed versus unobstructed ureters, our findings demonstrated the utility of Doppler ultrasound examination as a useful adjunct to gray-scale ultrasound by improving the accuracy of ultrasound exam in diagnosis of ureteral obstruction.

Macroscopic effects in electromagnetically-induced transparency in a Doppler-broadened system

International Nuclear Information System (INIS)

Pei Li-Ya; Qu Yi-Zhi; Niu Jin-Yan; Wang Ru-Quan; Wu Ling-An; Fu Pan-Ming; Zuo Zhan-Chun

2015-01-01

We study the electromagnetically-induced transparency (EIT) in a Doppler-broadened cascaded three-level system. We decompose the susceptibility responsible for the EIT resonance into a linear and a nonlinear part, and the EIT resonance reflects mainly the characteristics of the nonlinear susceptibility. It is found that the macroscopic polarization interference effect plays a crucial role in determining the EIT resonance spectrum. To obtain a Doppler-free spectrum there must be polarization interference between atoms of different velocities. A dressed-state model, which analyzes the velocities at which the atoms are in resonance with the dressed states through Doppler frequency shifting, is employed to explain the results. (paper)

A study of doppler waveform using pulsatile flow model

International Nuclear Information System (INIS)

Chung, Hye Won; Chung, Myung Jin; Park, Jae Hyung; Chung, Jin Wook; Lee, Dong Hyuk; Min, Byoung Goo

1997-01-01

Through the construction of a pulsatile flow model using an artificial heart pump and stenosis to demonstrate triphasic Doppler waveform, which simulates in vivo conditions, and to evaluate the relationship between Doppler waveform and vascular compliance. The flow model was constructed using a flowmeter, rubber tube, glass tube with stenosis, and artificial heart pump. Doppler study was carried out at the prestenotic, poststenotic, and distal segments;compliance was changed by changing the length of the rubber tube. With increasing proximal compliance, Doppler waveforms show decreasing peak velocity of the first phase and slightly delayed acceleration time, but the waveform itself did not change significantly. Distal compliance influenced the second phase, and was important for the formation of pulsus tardus and parvus, which without poststenotic vascular compliance, did not develop. The peak velocity of the first phase was inversely proportional to proximal compliance, and those of the second and third phases were directly proportional to distal compliance. After constructing this pulsatile flow model, we were able to explain the relationship between vascular compliance and Doppler waveform, and also better understand the formation of pulsus tardus and parvus

On the choice of the number of samples in laser Doppler anemometry signal processing

Science.gov (United States)

Dios, Federico; Comeron, Adolfo; Garcia-Vizcaino, David

2001-05-01

The minimum number of samples that must be taken from a sinusoidal signal affected by white Gaussian noise, in order to find its frequency with a predetermined maximum error, is derived. This analysis is of interest in evaluating the performance of velocity-measurement systems based on the Doppler effect. Specifically, in laser Doppler anemometry (LDA) it is usual to receive bursts with a poor signal-to- noise ratio, yet high accuracy is required for the measurement. In recent years special attention has been paid to the problem of monitoring the temporal evolution of turbulent flows. In this kind of situation averaging or filtering the data sequences cannot be allowed: in a rapidly changing environment each one of the measurements should rather by performed within a maximum permissible error and the bursts strongly affected by noise removed. The method for velocity extraction that will be considered here is the spectral analysis through the squared discrete Fourier transform, or periodogram, of the received bursts. This paper has two parts. In the first an approximate expression for the error committed in LDA is derived and discussed. In the second a mathematical formalism for the exact calculation of the error as a function of the signal-to- noise ratio is obtained, and some universal curves for the expected error are provided. The results presented here appear to represent a fundamental limitation on the accuracy of LDA measurements, yet, to our knowledge, they have not been reported in the literature so far.

Color doppler imaging of subclavian steal phenomenon

International Nuclear Information System (INIS)

Cho, Nari Ya; Chung, Tae Sub; Kim, Jai Keun

1997-01-01

To evaluate the characteristic color doppler imaging of vertebral artery flow in the subclavian steal phenomenon. The study group consisted of eight patients with reversed vertebral artery flow proved by color Doppler imaging. We classified this flow into two groups:(1) complete reversal;(2) partial reversal, as shown by Doppler velocity waveform. Vertebral angiography was performed in six of eight patients;color Doppler imaging and angiographic findings were compared. On color Doppler imaging, all eight cases with reversed vertebral artery flow showed no signal at the proximal subclavian or brachiocephalic artery. We confirmed shunting of six cases by performing angiography from the contralateral vertebral and basilar artery to the ipsilateral vertebral artery. On the Doppler spectrum, six cases showed complete reversal and two partial reversal. On angiography, one partial reversal case showed complete occlusion of the subclavian artery with abundant collateral circulation of muscular branches of the vertebral artery. On color Doppler imaging, a reversed vertebral artery suggests the subclavian steal phenomenon. In particular, partial reversal waveform may reflect collateral circulation

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)

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

Prognostic value of systolic mitral annular velocity measured with Doppler tissue imaging in patients with chronic heart failure caused by left ventricular systolic dysfunction

Science.gov (United States)

Nikitin, N P; Loh, P H; de Silva, R; Ghosh, J; Khaleva, O Y; Goode, K; Rigby, A S; Alamgir, F; Clark, A L; Cleland, J G F

2006-01-01

Objective To assess the prognostic value of various conventional and novel echocardiographic indices in patients with chronic heart failure (CHF) caused by left ventricular (LV) systolic dysfunction. Methods 185 patients with a mean (SD) age of 67 (11) years with CHF and LV ejection fraction < 45% despite optimal pharmacological treatment were prospectively enrolled. The patients underwent two dimensional echocardiography with tissue harmonic imaging to assess global LV systolic function and obtain volumetric data. Transmitral flow was assessed with conventional pulse wave Doppler. Systolic (Sm), early, and late diastolic mitral annular velocities were measured with the use of colour coded Doppler tissue imaging. Results During a median follow up of 32 months (range 24–38 months in survivors), 34 patients died and one underwent heart transplantation. Sm velocity (hazard ratio (HR) 0.648, 95% confidence interval (CI) 0.463 to 0.907, p  =  0.011), diastolic arterial pressure (HR 0.965, 95% CI 0.938 to 0.993, p  =  0.015), serum creatinine (HR 1.006, 95% CI 1.001 to 1.011, p  =  0.023), LV ejection fraction (HR 0.945, 95% CI 0.899 to 0.992, p  =  0.024), age (HR 1.035, 95% CI 1.000 to 1.071, p  =  0.052), LV end systolic volume index (HR 1.009, 95% CI 0.999 to 1.019, p  =  0.067), and restrictive pattern of transmitral flow (HR 0.543, 95% CI 0.278 to 1.061, p  =  0.074) predicted the outcome of death or transplantation on univariate analysis. On multivariate analysis, only Sm velocity (HR 0.648, 95% CI 0.460 to 0.912, p  =  0.013) and diastolic arterial pressure (HR 0.966, 95% CI 0.938 to 0.994, p  =  0.016) emerged as independent predictors of outcome. Conclusions In patients with CHF and LV systolic dysfunction despite optimal pharmacological treatment, the strongest independent echocardiographic predictor of prognosis was Sm velocity measured with quantitative colour coded Doppler tissue

Spectral color Doppler in the diagnosis and follow-up of Graves' disease

International Nuclear Information System (INIS)

Sponza, Massimo; Bertolotto, Michele; Ricci, Claudio; Fabris, Bruno; Armini, Lorenzo

1997-01-01

Hyperthyroidism in Graves' disease is caused by the presence of circulating autoantibodies to the THS receptors on the thyroid cells. Thyroid-suppression therapy prevents hormone production directly, without affecting the pathogenetic process. They performed color Doppler US of the thyroid gland and pulsed Doppler analysis of thyroid artery flow in 21 patients with Graves' disease before and during medical treatment. US results were compared with those of a control group of 40 healthy subjects and correlated with the values of thyroid hormones, TSH and thyroid microsomal and thyroglobulin antibodies. The thyroid gland was hypo vascularized in the control group. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity of PSV 20 ± 4 cm/s, diastolic velocity of 8 ± 1 cm/s, and resistive index of 0.60 ± 0.04. The thyroid gland of Graves' disease patients was hyper vascularized. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity (PSV = 51 ± 12 cm/s), end diastolic velocity (VD = 15 ± 4 cm/s) and resistive index (RI = 0.71 ± 0.04) significantly higher than in normal subjects (p < 0.001). Circulating thyroid hormones and flow parameters normalized after 6-8 months of medical therapy (PSV = 20 ± 6 cm/s, VD = 9 ± 3 cm(s, RI = 0.58 ± 0.07). The color Doppler patterns normalized only in a patient with normal TSH and antibodies. Sampling of the thyroid arteries proved more repeatable than sampling of parenchymal vessels

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

Relationship between lower limbs kinematic variables and effectiveness of sprint during maximum velocity phase.

Science.gov (United States)

Struzik, Artur; Konieczny, Grzegorz; Grzesik, Kamila; Stawarz, Mateusz; Winiarski, Sławomir; Rokita, Andrzej

2015-01-01

The aim of the study was to determine the relationships between time of running over a 15-25 m section of a 30-meter run along a straight line and changes in the angle and angular velocity observed in ankle, knee and hip joints. Therefore, the authors attempted to answer the question of whether a technique of lower limbs movement during the phase of sprint maximum velocity significantly correlates with the time of running over this section. A group of 14 young people from the Lower Silesia Voivodeship Team participated in the experiment. A Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using Noraxon MyoMotion system. There were observed statistically significant relationships between sprint time over a section from 15 to 25 m and left hip rotation (positive) and between this time and left and right ankle joint dorsi-plantar flexion (negative). During the maximum velocity phase of a 30 m sprint, the effect of dorsi-plantar flexion performed in the whole range of motion was found to be beneficial. This can be attributed to the use of elastic energy released in the stride cycle. Further, hip rotation should be minimized, which makes the stride aligned more along a line of running (a straight line) instead of from side to side.

Transcranial Doppler Ultrasound in Peninsular Arab Patients With Sickle Cell Disease.

Science.gov (United States)

Adekile, Adekunle; Hassan, Meaad; Asbeutah, Akram; Al-Hinai, Mohamed; Trad, Omar; Farhan, Nayef

2018-05-06

Transcranial Doppler ultrasound is used to identify patients with sickle cell disease (SCD) at risk for stroke. We performed transcranial Doppler studies in patients from 4 countries in the Arabian Peninsula (Kuwait, Oman, Iraq, and United Arab Emirates) to document the prevalence of abnormal transcranial Doppler findings. The patients were recruited from outpatient clinics and studied in a steady state. Transcranial Doppler examinations were performed with standard equipment by experienced operators. The time-averaged maximum mean velocity (TAMMV) was documented in the arteries of the circle of Willis. The hemoglobin (Hb) genotype was confirmed, and the fetal Hb level and complete blood counts were determined. There were 415 patients in the study, aged 2 to 18 years (mean ± SD, 8.6 ± 3.5 years). None of the patients had an abnormal TAMMV (ie, > 200 cm/s), whereas only 13 (3.1%), all from Iraq, had conditional values (170-200 cm/s) in the right middle cerebral artery and 7 (1.7%) in the left middle cerebral artery. There were no consistent TAMMV differences among male and female patients or in patients with different Hb genotypes (sickle cell anemia, sickle cell β 0- thalassemia, and sickle D). The use of hydroxyurea was associated with a lower TAMMV, whereas a blood transfusion history had no influence. Total hemoglobin, reticulocyte count, serum bilirubin, and fetal Hb values showed varying degrees of association with the TAMMV in the different vessels. This study has demonstrated the rarity of abnormal transcranial Doppler findings among Peninsular Arab patients with SCD. The guidelines for transcranial Doppler screening in this population need further studies and recommendations. © 2018 by the American Institute of Ultrasound in Medicine.

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

AIMS: Mitral annular (MA) displacement reflects longitudinal left ventricular (LV) deformation and systolic velocity measurements reflect the rate of contraction; both are valuable in the diagnosis and prognosis of cardiac disease. The aim of this study was to test the agreement and reproducibility...... 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...

Theoretical study of electromagnetically induced transparency in a five-level atom and application to Doppler-broadened and Doppler-free Rb atoms

International Nuclear Information System (INIS)

Bhattacharyya, Dipankar; Ray, Biswajit; Ghosh, Pradip N

2007-01-01

We report theoretical studies of a Λ-type five-level atomic system. The density matrix equations are set up and solved numerically to obtain the probe absorption line shape of Rb D 2 transitions for cold (Doppler-free) and room temperature (Doppler-broadened) atoms. Simulated spectra for Doppler-broadened systems lead to four velocity-selective dips along with an electromagnetic induced transparency (EIT) peak as observed earlier from the co-propagating pump-probe spectroscopy of Rb D 2 transitions. Effects of pump power and spontaneous decay rate from the upper levels on the simulated spectra are also studied. For cold atoms a very pronounced EIT peak is observed when the pump frequency is on resonance with one allowed transition. We find that lower pump power leads to a much sharper EIT signal in this case. A simulated dispersion curve shows a rapid variation of the refractive index that may lead to a sharp reduction of the group velocity of photons

Two-dimensional intraventricular flow mapping by digital processing conventional color-Doppler echocardiography images.

Science.gov (United States)

Garcia, Damien; Del Alamo, Juan C; Tanne, David; Yotti, Raquel; Cortina, Cristina; Bertrand, Eric; Antoranz, José Carlos; Perez-David, Esther; Rieu, Régis; Fernandez-Aviles, Francisco; Bermejo, Javier

2010-10-01

Doppler echocardiography remains the most extended clinical modality for the evaluation of left ventricular (LV) function. Current Doppler ultrasound methods, however, are limited to the representation of a single flow velocity component. We thus developed a novel technique to construct 2D time-resolved (2D+t) LV velocity fields from conventional transthoracic clinical acquisitions. Combining color-Doppler velocities with LV wall positions, the cross-beam blood velocities were calculated using the continuity equation under a planar flow assumption. To validate the algorithm, 2D Doppler flow mapping and laser particle image velocimetry (PIV) measurements were carried out in an atrio-ventricular duplicator. Phase-contrast magnetic resonance (MR) acquisitions were used to measure in vivo the error due to the 2D flow assumption and to potential scan-plane misalignment. Finally, the applicability of the Doppler technique was tested in the clinical setting. In vitro experiments demonstrated that the new method yields an accurate quantitative description of the main vortex that forms during the cardiac cycle (mean error for vortex radius, position and circulation). MR image analysis evidenced that the error due to the planar flow assumption is close to 15% and does not preclude the characterization of major vortex properties neither in the normal nor in the dilated LV. These results are yet to be confirmed by a head-to-head clinical validation study. Clinical Doppler studies showed that the method is readily applicable and that a single large anterograde vortex develops in the healthy ventricle while supplementary retrograde swirling structures may appear in the diseased heart. The proposed echocardiographic method based on the continuity equation is fast, clinically-compliant and does not require complex training. This technique will potentially enable investigators to study of additional quantitative aspects of intraventricular flow dynamics in the clinical setting by

Tumor vascularity evaluated by transrectal color Doppler US in predicting therapy outcome for low-lying rectal cancer

International Nuclear Information System (INIS)

Barbaro, Brunella; Valentini, Vincenzo; Coco, Claudio; Mancini, Anna Paola; Gambacorta, Maria Antonietta; Vecchio, Fabio Maria; Bonomo, Lorenzo

2005-01-01

Purpose: To evaluate the impact on T downstaging of the vasculature supplying blood flow to rectal cancer evaluated by color Doppler ultrasound. Methods and Materials: Color Doppler images were graded in 29 T3-staged rectal carcinoma patients sonographically just before chemoradiation. Any arterial vessels detected in rectal masses were assigned one of two grades: vascularity was considered as grade 1 for vessels feeding the periphery and as grade 2 for vessels coursing in all rectal masses within its peripheral and central portions. The pulsatility indices (PI = peak systolic velocity - end-diastolic velocity/time-averaged maximum velocity) were calculated in the central and peripheral portions. Results: The pathologic observations showed a change in stage in 15 of the 23 patients graded 2, positive predictive value 65.2% (p = 0.047), and in one of the six rectal cancers graded 1 (negative predictive value, 83.3%). The minimal peripheral PI values in rectal cancer graded 2 were higher in nonresponding (2.2 ± 1.3) than in responding lesions (1.6 ± 0.7) p = 0.01. Conclusion: Vascularity graded 2 associated with low peripheral PI values are indicators of therapy outcome. Vascularity graded 1 and high peripheral PI values in graded 2 have negative predictive value

Experimental study of wind tunnel performance by a two-component laserDopplerAnemometer

Directory of Open Access Journals (Sweden)

M Pourmahabadian

2005-10-01

Full Text Available Background and Aims: This survey studies the wind tunnel performance by a two- componentlaser Doppler Anemometer, so some experiments were carried out to assess the performance of awind tunnel.Method: The tunnel was capable to produce air velocity of up to 40 m/s.. Measurements ofvelocity profiles have been made actors the test section of wind tunnel through the using a twocomponentfiber optic Laser Doppler anemometer. Measurements of velocity profiles andturbulence intensities have been made across the test section of the wind tunnel using a twocomponentfiber optic Laser Doppler anemometer (I.D.A for wind speeds ranging from 1 to3m/s.Results: Performance rests of velocity profiles at a given flow rate and various position of aerosolgenerator showed that although uniformity of flow dependent to the place of an atomizer (asaerosol generator but the variation of wind speed across the test section meets the wind speedrequirements, as specified by US EPAfor 3m/s only.Conclusion:At time which particles velocity reach to less than one micron, the air velocity relateson the similarity of particles and

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

Color M-mode and pulsed wave tissue Doppler echocardiography

DEFF Research Database (Denmark)

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

2001-01-01

To assess the association between color M-mode flow propagation velocity and the early diastolic mitral annular velocity (E(m)) obtained with tissue Doppler echocardiography and to assess the prognostic implications of the indexes, echocardiography was performed on days 1 and 5, and 1 and 3 month...

The Assessment of Left Ventricular Time-Varying Radius Using Tissue Doppler Imaging

Directory of Open Access Journals (Sweden)

Fardin Mirbolouk

2012-03-01

Full Text Available Background: Left ventricular twist/torsion is believed to be a sensitive indicator of systolic and diastolic performance. To obtain circumferential rotation using tissue Doppler imaging, we need to estimate the time-varying radius of the left ventricle throughout the cardiac cycle to convert the tangential velocity into angular velocity. Objectives: The aim of this study was to investigate accuracy of measured LV radius using tissue Doppler imaging throughout the cardiac cycle compared to two-dimensional (2D imaging. Methods: A total of 35 subjects (47±12 years old underwent transthoracic echocardiographic standard examinations. Left ventricular radius during complete cardiac cycle measured using tissue Doppler and 2D-imaging at basal and apical short axis levels. For this reason, the 2D-images and velocity-time data derived and transferred to a personal computer for off-line analysis. 2D image frames analyzed via a program written in the MATLAB software. Velocity-time data from anteroseptal at basal level (or anterior wall at apical level and posterior walls transferred to a spreadsheet Excel program for the radius calculations. Linear correlation and Bland-Altman analysis were calculated to assess the relationships and agreements between the tissue Doppler and 2D-measured radii throughout the cardiac cycle. Results: There was significant correlation between tissue Doppler and 2D-measured radii and the Pearson correlation coefficients were 0.84 to 0.97 (P<0.05. Bland-Altman analysis by constructing the 95% limits of agreement showed that the good agreements existed between the two methods. Conclusion: It can be concluded from our experience that the tissue Doppler imaging can reasonably estimate radius of the left ventricle throughout the cardiac cycle.

Cerebrovascular reactivity in migraineurs as measured by transcranial Doppler

Energy Technology Data Exchange (ETDEWEB)

Thomas, T.D.; Harpold, G.J. (Alabama Univ., Birmingham, AL (USA). School of Medicine); Troost, B.T. (Bowman Gray School of Medicine, Winston-Salem, NC (USA))

1990-04-01

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{sub 2}, evidenced by an increase in middle cerebral artery blood flow velocity of 47% {plus minus} 15% compared to 28% {plus minus} 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{sub 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.

Spectral color Doppler in the diagnosis and follow-up of Graves` disease; Ruolo dell`eco color Doppler e dell`analisi flussimetrica nella diagnosi e nel follow-up della malattia dei Graves

Energy Technology Data Exchange (ETDEWEB)

Sponza, Massimo; Bertolotto, Michele; Ricci, Claudio [Ospedale di Cattinara, Trieste (Italy). Istituto di Medicina Clinica; Fabris, Bruno; Armini, Lorenzo [Ospedale di Cattinara, Trieste (Italy). Istituto di Radiologia

1997-04-01

Hyperthyroidism in Graves` disease is caused by the presence of circulating autoantibodies to the THS receptors on the thyroid cells. Thyroid-suppression therapy prevents hormone production directly, without affecting the pathogenetic process. They performed color Doppler US of the thyroid gland and pulsed Doppler analysis of thyroid artery flow in 21 patients with Graves` disease before and during medical treatment. US results were compared with those of a control group of 40 healthy subjects and correlated with the values of thyroid hormones, TSH and thyroid microsomal and thyroglobulin antibodies. The thyroid gland was hypo vascularized in the control group. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity of PSV 20 {+-} 4 cm/s, diastolic velocity of 8 {+-} 1 cm/s, and resistive index of 0.60 {+-} 0.04. The thyroid gland of Graves` disease patients was hyper vascularized. Pulsed Doppler examination of the thyroid arteries exhibited peak systolic velocity (PSV = 51 {+-} 12 cm/s), end diastolic velocity (VD = 15 {+-} 4 cm/s) and resistive index (RI = 0.71 {+-} 0.04) significantly higher than in normal subjects (p < 0.001). Circulating thyroid hormones and flow parameters normalized after 6-8 months of medical therapy (PSV = 20 {+-} 6 cm/s, VD = 9 {+-} 3 cm/s, RI = 0.58 {+-} 0.07). The color Doppler patterns normalized only in a patient with normal TSH and antibodies. Sampling of the thyroid arteries proved more repeatable than sampling of parenchymal vessels.

[Doppler ultrasound evaluation of aortic insufficiency using half-pressure time. Absence of arterial rigidity influence].

Science.gov (United States)

Kalotka-Bratek, H; Drobinski, G; Klimczak, K; Busquet, P; Fraysse, J B; Bejean-Lebuisson, A; Grosgogeat, Y

1989-02-01

In 20 patients with pure aortic regurgitation we studied the relationship between the severity of regurgitation, as assessed haemodynamically by the percentage of leakage (%L), and the half-pressure (T 1/2 P) and half-velocity (T 1/2 V) times, as obtained from doppler aortic blood velocity curves, taking into account the rigidity of the systemic vascular circuit characterized by the pressure wave propagation velocity (PWPV). The systemic arterial circuit was supple in 14 patients (PWPV less than 7.5 m/sec) and rigid in 6 patients (PWPV greater than 7.5 m/sec). The regression slopes between %L and T 1/2 P and between %L and T 1/2 V were calculated with their confidence limits in the 14 patients with supple arteries. The 6 patients with rigid arteries fitted into this nomogram, thus demonstrating that systemic arterial rigidity makes no difference in the relationship between %L and doppler indices. The half-velocity and half-pressure times measured by doppler ultrasound were acquired from a velocity signal directly determined by the aortic regurgitation, without any detectable effect of vascular circuit rigidity. Being equivalent by nature to the signal decrease time constant, they are independent of the absolute protodiastolic value of diastolic pressure gradient or blood flow velocity. For this reason these two doppler parameters are reliable to evaluate the severity of aortic regurgitation.

Transcranial Doppler ultrasound and cerebral angiography - alternative or complementary

International Nuclear Information System (INIS)

Bockenheimer, S.; Lorey, N.

1985-01-01

Transcranial Doppler ultrasound is a noninvasive method of recording the flow velocity of larger intracranial vessels. The impact on diagnosis of cerebravascular occlusive disease is not yet evaluated. We present 15 patients, age range 39-73 years, who suffered from completed stroke. The findings of transcranial Doppler ultrasound and of cerebral angiography are presented. The value of both methods in treatment strategy is discussed. (orig.) [de

Doppler ultrasound for detection of renal transplant artery stenosis - Threshold peak systolic velocity needs to be higher in a low-risk or surveillance population

International Nuclear Information System (INIS)

Patel, U.; Khaw, K.K.; Hughes, N.C.

2003-01-01

AIMS: To establish the ideal threshold arterial velocity for the diagnosis of renal transplant artery stenosis in a surveillance population with a low pre-test probability of stenosis. METHODS: Retrospective review of Doppler ultrasound, angiographic and clinical outcome data of patients transplanted over a 3-year period. Data used to calculate sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for various threshold peak systolic velocity values. RESULTS: Of 144 patients transplanted, full data were available in 117 cases. Five cases had renal transplant artery stenosis--incidence 4.2% [stenosis identified at a mean of 6.5 months (range 2-10 months)]. All five cases had a significant arterial pressure gradient across the narrowing and underwent angioplasty. Threshold peak systolic velocity of ≥2.5 m/s is not ideal [specificity=79% (CI 65-82%), PPV=18% (CI 6-32%), NPV=100% (CI 94-100%)], subjecting many patients to unnecessary angiography--8/117 (6%) in our population. Comparable values if the threshold is set at ≥3.0 m/s are 93% (CI 77-96%), 33% (CI 7-44%) and 99% (CI 93-100%), respectively. The clinical outcome of all patients was satisfactory, with no unexplained graft failures or loss. CONCLUSIONS: In a surveillance population with a low pre-test probability of stenosis, absolute renal artery velocity ≥2.5 m/s is a limited surrogate marker for significant renal artery stenosis. The false-positive rate is high, and ≥3.0 m/s is a better choice which will halve the number of patients enduring unnecessary angiography. Close clinical follow-up of patients in the 2.5-3.0 m/s range, with repeat Doppler ultrasound if necessary, will identify the test false-negatives

Laser doppler velocimetry and confined flows

Directory of Open Access Journals (Sweden)

Ilić Jelena T.

2017-01-01

Full Text Available Finding the mode, in which two component laser Doppler velocimetry can be applied to flows confined in cylindrical tubes or vessels, was the aim of this study. We have identified principle issues that influence the propagation of laser beams in laser Doppler velocimetry system, applied to flow confined in cylindrical tube. Among them, the most important are influences of fluid and wall refractive indices, wall thickness and internal radius ratio and beam intersection angle. In analysis of the degrees of these influences, we have applied mathematical model, based on geometrical optics. The separation of measurement volumes, that measure different velocity components, has been recognized as the main drawback. To overcome this, we propose a lens with dual focal length – primary focal length for the measurement of one velocity component and secondary focal length for the measurement of the other velocity component. We present here the procedure for calculating the optimal value of secondary focal length, depending on experimental set-up parameters. The mathematical simulation of the application of the dual focal length lens, for chosen cases presented here, confirmed the accuracy of the proposed procedure.

Study on Water Distribution Imaging in the Sand Using Propagation Velocity of Sound with Scanning Laser Doppler Vibrometer

Science.gov (United States)

Sugimoto, Tsuneyoshi; Nakagawa, Yutaka; Shirakawa, Takashi; Sano, Motoaki; Ohaba, Motoyoshi; Shibusawa, Sakae

2013-07-01

We propose a method for the monitoring and imaging of the water distribution in the rooting zone of plants using sound vibration. In this study, the water distribution measurement in the horizontal and vertical directions in the soil layer was examined to confirm whether a temporal change in the volume water content of the soil could be estimated from a temporal changes in propagation velocity. A scanning laser Doppler vibrometer (SLDV) is used for measurement of the vibration velocity of the soil surface, because the highly precise vibration velocity measurement of several many points can be carried out automatically. Sand with a uniform particle size distribution is used for the soil, as it has high plasticity; that is, the sand can return to a dry state easily even if it is soaked with water. A giant magnetostriction vibrator or a flat speaker is used as a sound source. Also, a soil moisture sensor, which measures the water content of the soil using the electric permittivity, is installed in the sand. From the experimental results of the vibration measurement and soil moisture sensors, we can confirm that the temporal changes of the water distribution in sand using the negative pressure irrigation system in both the horizontal and vertical directions can be estimated using the propagation velocity of sound. Therefore, in the future, we plan to develop an insertion-type sound source and receiver using the acceleration sensors, and we intend to examine whether our method can be applied even in commercial soil with growing plants.

Principles of doppler tomography

International Nuclear Information System (INIS)

Juhlin, P.

1992-08-01

This paper shows how the radon transform can be used to determine vector fields. A scheme to determine the velocity field of a moving fluid by measurements with a continuous doppler signal is suggested. When the flow is confined to a bounded domain, as is the case in most applications, it can be uniquely decomposed into one gradiental and one rotational part. The former vanishes if the fluid is incompressible and source-free, and the latter can be completely reconstructed by the methods proposed in this paper if the domain is simply connected. Special attention is paid to laminar flow in a long cylindrical vessel with circular cross-section. Under such conditions the flow profile becomes parabolic, which makes the vessel recognizable as a typical 'N-shaped' pattern in an image describing the rotation of the velocity field. The vessel yields the same doppler tomographic pattern, no matter how it is sectioned. The ideas presented should be applicable also when studying the flow in blood vessels, even if the flow profile in these is not quite parabolic. The discrepancies only make the 'N-shape' somewhat distorted

Thermal Design for a Diffraction-Limited Doppler Spectrometer

Data.gov (United States)

National Aeronautics and Space Administration — The Univ. of Notre Dame is building a new high-resolution spectrometer named “iLocater” to achieve unprecedented radial velocity (RV) precision for stellar Doppler...

Laser Doppler thermometry in flat flames

NARCIS (Netherlands)

Maaren, van A.; Goey, de L.P.H.

1994-01-01

Laser Doppler Velocimetry measurements are performed in flat flames, stabilized on a newly developed flat-flame burner. It is shown that the velocity component perpendicular to the main flow direction, induced by expansion in the reaction zone and buoyancy in the burnt gas, is significant. A method

Estimation of blood velocities using ultrasound

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt

imaging, and, finally, some of the more recent experimental techniques. The authors shows that the Doppler shift, usually considered the way velocity is detected, actually, plays a minor role in pulsed systems. Rather, it is the shift of position of signals between pulses that is used in velocity...

High Dynamic Velocity Range Particle Image Velocimetry Using Multiple Pulse Separation Imaging

Directory of Open Access Journals (Sweden)

Tadhg S. O’Donovan

2010-12-01

Full Text Available The dynamic velocity range of particle image velocimetry (PIV is determined by the maximum and minimum resolvable particle displacement. Various techniques have extended the dynamic range, however flows with a wide velocity range (e.g., impinging jets still challenge PIV algorithms. A new technique is presented to increase the dynamic velocity range by over an order of magnitude. The multiple pulse separation (MPS technique (i records series of double-frame exposures with different pulse separations, (ii processes the fields using conventional multi-grid algorithms, and (iii yields a composite velocity field with a locally optimized pulse separation. A robust criterion determines the local optimum pulse separation, accounting for correlation strength and measurement uncertainty. Validation experiments are performed in an impinging jet flow, using laser-Doppler velocimetry as reference measurement. The precision of mean flow and turbulence quantities is significantly improved compared to conventional PIV, due to the increase in dynamic range. In a wide range of applications, MPS PIV is a robust approach to increase the dynamic velocity range without restricting the vector evaluation methods.

High dynamic velocity range particle image velocimetry using multiple pulse separation imaging.

Science.gov (United States)

Persoons, Tim; O'Donovan, Tadhg S

2011-01-01

The dynamic velocity range of particle image velocimetry (PIV) is determined by the maximum and minimum resolvable particle displacement. Various techniques have extended the dynamic range, however flows with a wide velocity range (e.g., impinging jets) still challenge PIV algorithms. A new technique is presented to increase the dynamic velocity range by over an order of magnitude. The multiple pulse separation (MPS) technique (i) records series of double-frame exposures with different pulse separations, (ii) processes the fields using conventional multi-grid algorithms, and (iii) yields a composite velocity field with a locally optimized pulse separation. A robust criterion determines the local optimum pulse separation, accounting for correlation strength and measurement uncertainty. Validation experiments are performed in an impinging jet flow, using laser-Doppler velocimetry as reference measurement. The precision of mean flow and turbulence quantities is significantly improved compared to conventional PIV, due to the increase in dynamic range. In a wide range of applications, MPS PIV is a robust approach to increase the dynamic velocity range without restricting the vector evaluation methods.

Referencing geostrophic velocities using ADCP data Referencing geostrophic velocities using ADCP data

Directory of Open Access Journals (Sweden)

Isis Comas-Rodríguez

2010-06-01

Full Text Available Acoustic Doppler Current Profilers (ADCPs have proven to be a useful oceanographic tool in the study of ocean dynamics. Data from D279, a transatlantic hydrographic cruise carried out in spring 2004 along 24.5°N, were processed, and lowered ADCP (LADCP bottom track data were used to assess the choice of reference velocity for geostrophic calculations. The reference velocities from different combinations of ADCP data were compared to one another and a reference velocity was chosen based on the LADCP data. The barotropic tidal component was subtracted to provide a final reference velocity estimated by LADCP data. The results of the velocity fields are also shown. Further studies involving inverse solutions will include the reference velocity calculated here.

An improvement of wind velocity estimation from radar Doppler spectra in the upper mesosphere

Directory of Open Access Journals (Sweden)

S. Takeda

2001-08-01

Full Text Available We have developed a new parameter estimation method for Doppler wind spectra in the mesosphere observed with an MST radar such as the MU radar in the DBS (Doppler Beam Swinging mode. Off-line incoherent integration of the Doppler spectra is carried out with a new algorithm excluding contamination by strong meteor echoes. At the same time, initial values on a least square fitting of the Gaussian function are derived using a larger number of integration of the spectra for a longer time and for multiple heights. As a result, a significant improvement has been achieved with the probability of a successful fitting and parameter estimation above 80 km. The top height for the wind estimation has been improved to around 95 km. A comparison between the MU radar and the High Resolution Doppler Imager (HRDI on the UARS satellite is shown and the capability of the new method for a validation of a future satellite mission is suggested.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics – Radio science (remote sensing; signal processing

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.

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.)

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.

Numerical stud of glare spot phase Doppler anemometry

OpenAIRE

Hespel , Camille; Ren , Kuan Fang; Gréhan , Gérard; Onofri , Fabrice

2008-01-01

International audience; The phase Doppler anemometry has (PDA) been developed to measure simultaneously the velocity and the size of droplets. When the concentration of particles is high, tightly focused beams must be used, as in the dual burst PDA. The latter permits an access to the refractive index of the particle, but the effect of wave front curvature of the incident beams becomes evident. In this paper, we introduce a glare spot phase Doppler anemometry which uses two large beams. The i...

Wind profiling for a coherent wind Doppler lidar by an auto-adaptive background subtraction approach.

Science.gov (United States)

Wu, Yanwei; Guo, Pan; Chen, Siying; Chen, He; Zhang, Yinchao

2017-04-01

Auto-adaptive background subtraction (AABS) is proposed as a denoising method for data processing of the coherent Doppler lidar (CDL). The method is proposed specifically for a low-signal-to-noise-ratio regime, in which the drifting power spectral density of CDL data occurs. Unlike the periodogram maximum (PM) and adaptive iteratively reweighted penalized least squares (airPLS), the proposed method presents reliable peaks and is thus advantageous in identifying peak locations. According to the analysis results of simulated and actually measured data, the proposed method outperforms the airPLS method and the PM algorithm in the furthest detectable range. The proposed method improves the detection range approximately up to 16.7% and 40% when compared to the airPLS method and the PM method, respectively. It also has smaller mean wind velocity and standard error values than the airPLS and PM methods. The AABS approach improves the quality of Doppler shift estimates and can be applied to obtain the whole wind profiling by the CDL.

New clutter-rejection algorithm for Doppler ultrasound

Science.gov (United States)

Cloutier, Guy; Chen, Danmin; Durand, Louis-Gilles

2002-04-01

Several strategies, known as clutter or wall Doppler filtering, were proposed to remove the strong echoes produced by stationary or slow moving tissue structures from the Doppler blood flow signal. In this study, the matching pursuit (MP) method is proposed to remove clutter components. The MP method decomposes the Doppler signal into wavelet atoms that are selected in a decreasing energy order. Thus, the high-energy clutter components are extracted first. In the present study, the pulsatile Doppler signal s(n) was simulated by a sum of random-phase sinusoids. Two types of high-amplitude clutter signals were then superimposed on s(n): a time-varying low frequency component (type 1), covering systole and early diastole, and short transient clutter signals (type 2), distributed within the whole cardiac cycle. The Doppler signals were modeled with the MP method and the most dominant atoms were subtracted until the signal-to-clutter (S/C) ratio reached a maximum. For the type 1 clutter signal, the improvement in the S/C ratio was 19.0 +/- 0.6 dB, and 72.0 +/- 4.5 atoms were required to reach this performance. For the transient type 2 clutter signal, exactly 10 atoms were required and the maximum improvement in S/C ratio was 5.5 +/- 0.5 dB. These results suggest the possibility of using this signal processing approach to implement clutter rejection filters on ultrasound commercial instruments.

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...

Three dimensional winds: A maximum cross-correlation application to elastic lidar data

Energy Technology Data Exchange (ETDEWEB)

Buttler, William Tillman [Univ. of Texas, Austin, TX (United States)

1996-05-01

Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar (light detection and ranging) data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three-dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain-following winds in the Rio Grande valley.

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

Optic-microwave mixing velocimeter for superhigh velocity measurement

International Nuclear Information System (INIS)

Weng Jidong; Wang Xiang; Tao Tianjiong; Liu Cangli; Tan Hua

2011-01-01

The phenomenon that a light beam reflected off a moving object experiences a Doppler shift in its frequency underlies practical interferometric techniques for remote velocity measurements, such as velocity interferometer system for any reflector (VISAR), displacement interferometer system for any reflector (DISAR), and photonic Doppler velocimetry (PDV). While VISAR velocimeters are often bewildered by the fringe loss upon high-acceleration dynamic process diagnosis, the optic-fiber velocimeters such as DISAR and PDV, on the other hand, are puzzled by high velocity measurement over 10 km/s, due to the demand for the high bandwidth digitizer. Here, we describe a new optic-microwave mixing velocimeter (OMV) for super-high velocity measurements. By using currently available commercial microwave products, we have constructed a simple, compact, and reliable OMV device, and have successfully obtained, with a digitizer of bandwidth 6 GH only, the precise velocity history of an aluminum flyer plate being accelerated up to 11.2 km/s in a three stage gas-gun experiment.

Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers

Directory of Open Access Journals (Sweden)

Richard Billich

2015-03-01

Full Text Available Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers In today’s world of strength training there are many myths surrounding effective exercising with the least possible negative effect on one’s health. In this experiment we focus on the finding of a relationship between maximum output, used load and the velocity with which the exercise is performed. The main objective is to find the optimal speed of the exercise motion which would allow us to reach the maximum mechanic muscle output during a bench press exercise. This information could be beneficial to sporting coaches and recreational sportsmen alike in helping them improve the effectiveness of fast strength training. Fifteen football players of the FK Třinec football club participated in the experiment. The measurements were made with the use of 3D cinematic and dynamic analysis, both experimental methods. The research subjects participated in a strength test, in which the mechanic muscle output of 0, 10, 30, 50, 70, 90% and one repetition maximum (1RM was measured. The acquired result values and other required data were modified using Qualisys Track Manager and Visual 3D software (C-motion, Rockville, MD, USA. During the bench press exercise the maximum mechanic muscle output of the set of research subjects was reached at 75% of maximum exercise motion velocity. Optimální rychlost pohybu pro dosažení maxima výstupního výkonu – bench press u trénovaných fotbalistů Dnešní svět silového tréninku přináší řadu mýtů o tom, jak cvičit efektivně a zároveň s co nejmenším negativním vlivem na zdraví člověka. V tomto experimentu se zabýváme nalezením vztahu mezi maximálním výkonem, použitou zátěží a rychlostí. Hlavním úkolem je nalezení optimální rychlosti pohybu pro dosažení maximálního mechanického svalového výkonu při cvičení bench press, což pomůže nejenom trenérům, ale i rekreačním sportovc

Inline Ultrasonic Rheometry by Pulsed Doppler

Energy Technology Data Exchange (ETDEWEB)

Pfund, David M.; Greenwood, Margaret S.; Bamberger, Judith A.; Pappas, Richard A.

2006-12-22

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for making non-invasive, real-time measurements for monitoring and control. Rheograms of a shear thinning, thixotropic gel will be presented. The operating parameters and limitations of the Doppler-based instrument will be discussed. The most significant limitation is velocity gradient broadening of the Doppler spectra near the walls of the pipe. This limitation can be significant for strongly shear thinning fluids (depending also on the ratio of beam to pipe diameter and the transducer's insertion angle).

Feasibility of UltraFast Doppler in Post-operative Evaluation of Hepatic Artery in Recipients following Liver Transplantation.

Science.gov (United States)

Kim, Se-Young; Kim, Kyoung Won; Choi, Sang Hyun; Kwon, Jae Hyun; Song, Gi-Won; Kwon, Heon-Ju; Yun, Young Ju; Lee, Jeongjin; Lee, Sung-Gyu

2017-11-01

To determine the feasibility of using UltraFast Doppler in post-operative evaluation of the hepatic artery (HA) after liver transplantation (LT), we evaluated 283 simultaneous conventional and UltraFast Doppler sessions in 126 recipients over a 2-mo period after LT, using an Aixplorer scanner The Doppler indexes of the HA (peak systolic velocity [PSV], end-diastolic velocity [EDV], resistive index [RI] and systolic acceleration time [SAT]) by retrospective analysis of retrieved waves from UltraFast Doppler clips were compared with those obtained by conventional spectral Doppler. Correlation, performance in diagnosing the pathologic wave, examination time and reproducibility were evaluated. The PSV, EDV, RI and SAT of spectral and UltraFast Doppler measurements exhibited excellent correlation with favorable diagnostic performance. During the bedside examination, the mean time spent for UltraFast clip storing was significantly shorter than that for conventional Doppler US measurements. Both conventional and UltraFast Doppler exhibited good to excellent inter-analysis consistency. In conclusion, compared with conventional spectral Doppler, UltraFast Doppler values correlated excellently and yielded acceptable pathologic wave diagnostic performance with reduced examination time at the bedside and excellent reproducibility. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Pulsed and Tissue Doppler Echocardiographic Changes in Patients with Thalassemia Major

Directory of Open Access Journals (Sweden)

Taysir S. Garadah

2010-01-01

Full Text Available Background Doppler echocardiographic studies of left ventricle (LV systolic and diastolic function in patients with β-Thalassemia Major (β-TM had shown different patterns of systolic and diastolic dysfunction. Aim This cross-sectional study was designed to study the LV systolic and diastolic function in patients with β-TM using Pulsed Doppler (PD and Tissue Doppler (TD echocardiography. Methods All patients were evaluated clinically and by echocardiography, The study included patients with β-TM (n = 38, age 15.7 ± 8.9 years compared with an age-matched control group (n = 38, age 15.9 ± 8.9 years. The pulse Doppler indices were normalized for age and heart rate. Results Compared with control patients, M-Mode showed that patients with β-TM have thicker LV septal wall index (0.659 ± 0.23 vs. 0.446 ± 0.219 cm, P ≤ 0.001, posterior wall index (0.659 ± 0.235 vs. 0.437 ± 0.214 cm, P ≤ 0.01, and larger LVEDD index is (3.99 ± 0.48 vs. 2.170 ± 0.57 mm. P = 0.035. Pulsed Doppler showed high LV trans-mitral E wave velocity (70.818 ± 10.139 vs. 57.532 ± 10.139, p = 0.027 and E/A ratio (1.54 vs. 1.23, P ≤ 0.01. The duration of Deceleration time (DT and isovolumic relaxation time (IVRT were significantly shorter in patients with β-TM (150.234 ± 20.0.23 vs. 167.123 ± 19.143 msec, P ≤ 0.01 and (60.647 ± 6.77 vs. 75.474 ± 5.83 msec, P ≤ 0.001, respectively. The ratio of transmitral E wave velocity to the tissue Doppler E wave at the basal septal mitral annulus E/Em – was significantly higher in β-TM group (14.024 ± 2.29 vs. 12.132 ± 1.82, P ≤ 0.01. The Tissue Doppler systolic velocity (Sm and the early diastolic velocity (Em were significantly lower in β-TM group compared to control (4.31 ± 1.2 cm/s vs. 6.95 ± 2.1, P ≤ 0.01 and 4.31 ± 2.7 cm/s vs. 5.82 ± 2.5, P ≤ 0.01 respectively. The tricuspid valve velocity was significantly higher than controls (2.993 ± 0.569 vs. 1.93 ± 0.471 m/sec, respectively, P ≤ 0

Development Characteristics of Velocity Transports in An Isothermal Heated Drag-Reducing Surfactant Solution Flow

Science.gov (United States)

Zhang, Hongxia; Wang, Dezhong; Chen, Hanping; Wang, Yanping

2007-06-01

The development characteristics, turbulence transports for stresses and kinetic energy of a cetyltrimethyl ammonium chloride (CTAC) surfactant solution for a two-dimensional channel flow have been experimentally investigated. Time mean velocity and fluctuating velocity are measured using a Phase Doppler Anemometry (PDA) at the Reynolds number 1.78×104 and isothermal heated temperature 31°C. Although mean velocity profiles at three cross sections show that the fluid is almost fully developed, the peak location of fluctuating intensity for the CTAC solution is slightly away from the wall downstream from the fluid and the peak location of fluctuating intensity is observed at far away from the wall than that of water. The location where the velocity gradient has its maximum, the fluctuating intensity does not get the high value. The elastic shear stress contribution to the total shear stress is 15 percents to 36 percents and it gets to the maximum near to the wall. The surfactant elastic shear stress is almost a liner function of the height of the channel, which means that the elastic stress contribution of the different cross locations is approximately the same. The fluctuating surfactant stress work is negative and the fluctuating elastic shear stresses produce rather than dissipate kinetic energy.

Flow structure in a downward branch pipe with a closed end. Characteristics of flow velocity in the branch pipe

International Nuclear Information System (INIS)

Miyoshi, Koji; Nakamura, Akira; Takenaka, Nobuyuki

2016-01-01

Many pipes branch off from a main pipe in industrial plants. The penetration of hot water into the branch pipe causes thermal stratification. The thermal stratification layer fluctuates and causes thermal fatigue. The characteristics of velocity distributions in the branch pipe for inner diameters from D_b=21 mm to 43 mm were investigated by laser Doppler velocimetry in this paper. As for the flow in the branch pipe at L=4D_b, the mean velocity of the spiral flow was a simple forced vortex which indicated a straight velocity distribution. The maximum circumferential velocity U_θ _m_a_x and minimum axial velocity U_z _m_i_n at L=4D_b were expressed with D_b and main flow velocity. Empirical formulas were proposed for estimating the distributions of U_θ _m_a_x and U_z _m_i_n in the axial direction. (author)

A method to validate quantitative high-frequency power doppler ultrasound with fluorescence in vivo video microscopy.

Science.gov (United States)

Pinter, Stephen Z; Kim, Dae-Ro; Hague, M Nicole; Chambers, Ann F; MacDonald, Ian C; Lacefield, James C

2014-08-01

Flow quantification with high-frequency (>20 MHz) power Doppler ultrasound can be performed objectively using the wall-filter selection curve (WFSC) method to select the cutoff velocity that yields a best-estimate color pixel density (CPD). An in vivo video microscopy system (IVVM) is combined with high-frequency power Doppler ultrasound to provide a method for validation of CPD measurements based on WFSCs in mouse testicular vessels. The ultrasound and IVVM systems are instrumented so that the mouse remains on the same imaging platform when switching between the two modalities. In vivo video microscopy provides gold-standard measurements of vascular diameter to validate power Doppler CPD estimates. Measurements in four image planes from three mice exhibit wide variation in the optimal cutoff velocity and indicate that a predetermined cutoff velocity setting can introduce significant errors in studies intended to quantify vascularity. Consistent with previously published flow-phantom data, in vivo WFSCs exhibited three characteristic regions and detectable plateaus. Selection of a cutoff velocity at the right end of the plateau yielded a CPD close to the gold-standard vascular volume fraction estimated using IVVM. An investigator can implement the WFSC method to help adapt cutoff velocity to current blood flow conditions and thereby improve the accuracy of power Doppler for quantitative microvascular imaging. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

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.)

Methodology for obtaining wind gusts using Doppler lidar

DEFF Research Database (Denmark)

Suomi, Irene; Gryning, Sven-Erik; O'Connor, Ewan J.

2017-01-01

reduced the bias in the Doppler lidar gust factors from 0.07 to 0.03 and can be improved further to reduce the bias by using a realistic estimate of turbulence. Wind gust measurements are often prone to outliers in the time series, because they represent the maximum of a (moving-averaged) horizontal wind...... detection also outperformed the traditional Doppler lidar quality assurance method based on carrier-to-noise ratio, by removing additional unrealistic outliers present in the time series.......A new methodology is proposed for scaling Doppler lidar observations of wind gusts to make them comparable with those observed at a meteorological mast. Doppler lidars can then be used to measure wind gusts in regions and heights where traditional meteorological mast measurements are not available...

Glare Spot Phase Doppler Anemometry

Science.gov (United States)

Hespel, Camille; Ren, Kuanfang; Gréhan, Gérard; Onofri, Fabrice

2007-06-01

The Phase Doppler anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index would be also interesting since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemometry which uses two large beams. In this case, the images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes in the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences between two signals, the distance and the intensity ratio of reflected and refracted parts can be obtained and they provide rich information about the particle diameter and its refractive index, as well as its velocity. This paper is devoted to the numerical study of such a configuration with two theoretical models: geometrical optics and rigorous electromagnetism solution.

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.

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).

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.

Laser sub-Doppler cooling of atoms in an arbitrarily directed magnetic field

International Nuclear Information System (INIS)

Chang, Soo; Kwon, Taeg Yong; Lee, Ho Seong; Minogin, V.G.

2002-01-01

We analyze the influence of an arbitrarily directed uniform magnetic field on the laser sub-Doppler cooling of atoms. The analysis is done for a (3+5)-level atom excited by a σ + -σ - laser field configuration. Our analysis shows that the effects of the magnetic field depend strongly on the direction of the magnetic field. In an arbitrarily directed magnetic field the laser cooling configuration produces both the main resonance existing already at zero magnetic field and additional sub-Doppler resonances caused by two-photon and higher-order multiphoton processes. These sub-Doppler resonances are, however, well separated on the velocity scale if the Zeeman shift exceeds the widths of the resonances. This allows one to use the main sub-Doppler resonance for an effective laser cooling of atoms even in the presence of the magnetic field. The effective temperature of the atomic ensemble at the velocity of the main resonance is found to be almost the same as in the absence of the magnetic field. The defined structure of the multiphoton resonances may be of importance for the sub-Doppler laser cooling of atoms, atomic extraction from magneto-optical traps, and applications related to the control of atomic motion

Tissue Doppler echocardiography – A case of right tool, wrong use

Directory of Open Access Journals (Sweden)

Thomas George

2004-08-01

Full Text Available Abstract Background The developments in echocardiography or ultrasound cardiography (UCG have improved our clinical capabilities. However, advanced hardware and software capabilities have resulted in UCG facilities of dubious clinical benefits. Is tissue Doppler echocardiography (TDE is one such example? Presentation of the hypothesis TDE has been touted as advancement in the field of echocardiography. The striking play of colors, impressive waveforms and the seemingly accurate velocity values could be deceptive. TDE is a clear case of inappropriate use of technology. Testing the hypothesis To understand this, a comparison between flow Doppler and tissue Doppler is made. To make clinically meaningful velocity measurements with Doppler, we need prior knowledge of the line of motion. This is possible in blood flow but impossible in the complex myocardial motion. The qualitative comparison makes it evident that Doppler is best suited for flow studies. Implications of the hypothesis As of now TDE is going backwards using an indirect method when direct methods are better. The work on TDE at present is only debatable 'research and publication' material and do not translate into tangible clinical benefits. There are several advances like curved M-mode, strain rate imaging and tissue tracking in TDE. However these have been disappointing. This is due to the basic flaw in the application of the principles of Doppler. Doppler is best suited for flow studies and applying it to tissue motion is illogical. All data obtained by TDE is scientifically incorrect. This makes all the published papers on the subject flawed. Making diagnostic decisions based on this faulty application of technology would be unacceptable to the scientific cardiologist.

Transcranial Doppler, MRA, and MRI as a screening examination for cerebrovascular disease in patients with sickle cell anemia: an 8-year study

Energy Technology Data Exchange (ETDEWEB)

Seibert, J.J.; Glasier, C.M.; Allison, J.W.; James, C.A.; Kinder, D.L.; Cox, K.S.; Lairry, F.; Graves, R.A. [Arkansas Children`s Hospital, Little Rock, AR (United States). Dept. of Radiology; Kirby, R.S.; Flick, E.L. [Center for Ambulatory Research, Univ. of Arkansas for Medical Sciences, Little Rock, AR (United States); Becton, D.L.; Jackson, F.J. [Dept. of Hematology, Univ. of Arkansas for Medical Sciences, Little Rock, AR (United States)

1998-03-01

Objective. The authors previously reported five transcranial Doppler ultrasonography (TCD) findings as significant in detecting clinical cerebrovascular disease in a 4-year study in patients with sickle cell disease. This is a follow-up to evaluate the validity of the original findings over another 4-year period during which the study population doubled. A clinical follow-up of the original asymptomatic sickle cell patients with positive TCD, MRA, and MRI was also made. Results. Of the 4 out of original 46 control patients in 1992 who had positive MRA and TCD, 3 have subsequently had clinical stroke. None of the 9 original patients with positive TCD and positive MRI but negative MRA have developed stroke. All five original TCD indicators of disease were still significant (P<0.05) for detecting clinical disease: maximum velocity in ophthalmic artery (OA)>35 cm/s, mean velocity in middle cerebral artery (MCA) >170 cm/s, resistive index (RI) in OA<50, velocity in OA greater than in MCA, and velocity in posterior cerebral (PCA), vertebral, or basilar arteries greater than in MCA. Four additional factors were also significant: turbulence, PCA or ACA without MCA, RI<30, and maximum velocity in MCA>200 cm/s. (orig.)

The influence of emotional stress on Doppler-derived aortic peak velocity in boxer dogs.

Science.gov (United States)

Pradelli, D; Quintavalla, C; Crosta, M C; Mazzoni, L; Oliveira, P; Scotti, L; Brambilla, P; Bussadori, C

2014-01-01

Subaortic stenosis (SAS) is a common congenital heart disease in Boxers. Doppler-derived aortic peak velocity (AoPV) is a diagnostic criterion for the disease. To investigate the influence of emotional stress during echocardiographic examination on AoPV in normal and SAS-affected Boxers. To evaluate the effects of aortic root diameters on AoPV in normal Boxers. DOGS: Two hundred and fifteen normal and 19 SAS-affected Boxers. The AoPV was recorded at the beginning of echocardiographic examination (T0), and when the emotional stress of the dog was assumed to decrease based on behavioral parameters and heart rate (T1). AoPV0-AoPV1 was calculated. In normal dogs, stroke volume index was calculated at T0 and T1. Aortic root diameters were measured and their relationship with AoPV and AoPV0-AoPV1 was evaluated. In normal dogs, AoPV was higher at T0 (median, 1.95 m/s; range, 1.60-2.50 m/s) than at T1 (median, 1.76 m/s; range, 1.40-2.20 m/s; P dogs, AoPV0 was higher than AoPV1 (P < .0001; reduction 7.3%). Aortic peak velocity was affected by emotional stress during echocardiographic examination both in SAS-affected and normal Boxers. In normal Boxers, aortic root size weakly affected AoPVs, but did not affect AoPV0-AoPV1. Stroke volume seems to play a major role in stress-related AoPV increases in normal Boxers. Emotional stress should be taken into account when screening for SAS in the Boxer breed. Copyright © 2014 by the American College of Veterinary Internal Medicine.

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

Assessment of resting-state blood flow through anterior cerebral arteries using trans-cranial doppler recordings.

Science.gov (United States)

Huang, Hanrui; Sejdić, Ervin

2013-12-01

Trans-cranial Doppler (TCD) recordings are used to monitor cerebral blood flow in the main cerebral arteries. The resting state is usually characterized by the mean velocity or the maximum Doppler shift frequency (an envelope signal) by insonating the middle cerebral arteries. In this study, we characterized cerebral blood flow in the anterior cerebral arteries. We analyzed both envelope signals and raw signals obtained from bilateral insonation. We recruited 20 healthy patients and conducted the data acquisition for 15 min. Features were extracted from the time domain, the frequency domain and the time-frequency domain. The results indicate that a gender-based statistical difference exists in the frequency and time-frequency domains. However, no handedness effect was found. In the time domain, information-theoretic features indicated that mutual dependence is higher in raw signals than in envelope signals. Finally, we concluded that insonation of the anterior cerebral arteries serves as a complement to middle cerebral artery studies. Additionally, investigation of the raw signals provided us with additional information that is not otherwise available from envelope signals. Use of direct trans-cranial Doppler raw data is therefore validated as a valuable method for characterizing the resting state. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

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...... is a promising tool for improving our understanding of right ventricular hemodynamics, several aspects of the technology must be evaluated. The accuracy and reproducibility of the technology is evaluated in vitro, and normal values, impact of changes in loading of the right ventricle, response to exercise...... 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...

Acoustic and streaming velocity components in a resonant waveguide at high acoustic levels.

Science.gov (United States)

Daru, Virginie; Reyt, Ida; Bailliet, Hélène; Weisman, Catherine; Baltean-Carlès, Diana

2017-01-01

Rayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming velocities is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency on acoustics going from quadratic to linear. The evolution of streaming flow is different for outer cells and for inner cells. Also, the hypothesis of radial streaming velocity being of second order in a Mach number expansion, is not valid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.

Velocity slip of gas mixtures in free jet expansions

International Nuclear Information System (INIS)

Cattolica, R.J.; Talbot, L.; Coe, D.

1976-11-01

Velocity slip in gas mixtures of argon and helium in axisymmetric free jet expansions has been measured using a grating monochromator together with a computer-controlled Fabry-Perot interferometer to observe the fluorescence excited by an electron beam. The Doppler shift between the fluorescence observed parallel and perpendicular to the centerline of the free jet was used to measure the mean velocity of a particular species along the jet centerline, employing the 4880 A line for argon and the 5016 A line for helium. By alternately tracking the parallel and perpendicular fluorescence, the Doppler shift due to the mean velocity was measured directly with an accuracy of 1 percent. Flow field surveys have been made in the initial acceleration region where the flow becomes hypersonic and in the far field region. The differences between argon and helium mean velocities (velocity slip) are in good agreement with molecular beam data and show a correlation with an inverse Knudsen number

Analysis of Radar Doppler Signature from Human Data

Directory of Open Access Journals (Sweden)

M. ANDRIĆ

2014-04-01

Full Text Available This paper presents the results of time (autocorrelation and time-frequency (spectrogram analyses of radar signals returned from the moving human targets. When a radar signal falls on the human target which is moving toward or away from the radar, the signals reflected from different parts of his body produce a Doppler shift that is proportional to the velocity of those parts. Moving parts of the body causes the characteristic Doppler signature. The main contribution comes from the torso which causes the central Doppler frequency of target. The motion of arms and legs induces modulation on the returned radar signal and generates sidebands around the central Doppler frequency, referred to as micro-Doppler signatures. Through analyses on experimental data it was demonstrated that the human motion signature extraction is better using spectrogram. While the central Doppler frequency can be determined using the autocorrelation and the spectrogram, the extraction of the fundamental cadence frequency using the autocorrelation is unreliable when the target is in the clutter presence. It was shown that the fundamental cadence frequency increases with increasing dynamic movement of people and simultaneously the possibility of its extraction is proportional to the degree of synchronization movements of persons in the group.

Echobiometrics kidney and renal artery triplex doppler of canine fetuses

Directory of Open Access Journals (Sweden)

M.A.R. Feliciano

2014-04-01

Full Text Available The aim of this study was to assess the sogographic parameters and biometry of canine fetal kidneys using the B mode, and to determinate the vascular index of the fetal renal arteries using the Doppler Triplex. Twenty four Shi-tzu and Pug, weighting between 4 and 10kg, aging between 4 and 6 years old were evaluated. The B mode, the fetal renal echobiometry and regularity of the renal surface, echotexture and cortex:medular ratio were evaluated during the 5th, 6th, 7th and 8th weeks of pregnancy. At the same time point of the B mode evaluation, the Doppler Triplex was carried out to assess the sistolic peak velocity (SPV, end diastolic velocity (EDV, vascular resistive (RI and pulsatility index (PI. B mode revealed no fetal renal abnormalities and echobiometry showed important measurements during fetal development (P0.05. B mode and Doppler Triplex were important tools for the assessment of fetal renal development, using echobiometry and renal arterial index in canie fetuses.

New technology - demonstration of a vector velocity technique

DEFF Research Database (Denmark)

Møller Hansen, Peter; Pedersen, Mads M; Hansen, Kristoffer L

2011-01-01

With conventional Doppler ultrasound it is not possible to estimate direction and velocity of blood flow, when the angle of insonation exceeds 60-70°. Transverse oscillation is an angle independent vector velocity technique which is now implemented on a conventional ultrasound scanner. In this pa...

Analysis of 3D Doppler Tomography of the X-ray Binary System Cygnus X-1 from Spectral Observations in 2007 in the HeII λ 4686 Å Line

Science.gov (United States)

Agafonov, M. I.; Karitskaya, E. A.; Sharova, O. I.; Bochkarev, N. G.; Zharikov, S. V.; Butenko, G. Z.; Bondar', A. V.; Bubukin, I. T.

2018-03-01

This is the second paper in a series dedicated to studies of the X-ray binary Cyg X-1 in the HeII λ 4686 Å line using 3D Doppler tomography. A detailed analysis of the tomogram constructed has made it possible for the first time to obtain information about the motions of gaseous flows including all three velocity components. The observations were obtained in June 2007 at the Terskol Branch of the Institute of Astronomy (Russia) and the National Astronomical Observatory of Mexico. The correctness of the tomographic results and their discussion is analyzed. The results are compared with a 2D Doppler tomogram reconstruction. Model-atmosphere computations of HeII λ 4686 Å line profiles are used to estimate the influence of absorption features of the Osupergiant on the emission structure in the tomogram. The correctness of the 3D solutions is confirmed by the good agreement between the original sequence of spectral data and a control data set computed using the constructed 3D Doppler tomogram. Tomograms constructed using the data of each of the two observatories are compared. The results of the reconstruction for inclinations of the system of 40° and 45° essentially coincide. The maximum absorption (corresponding to the O supergiant) and emission structural features in the 3D tomogram are located in its central ( V x , V y ) section, where the velocity component perpendicular to the orbital plane V z is zero. The emission is generated mainly in the outer part of the accretion structure, close to the supergiant. A gaseous stream from the Lagrangian point L1 with its motion close to the orbital plane can be distinguished. Its maximum velocity reaches 800 km/s. The identification of an emission structure with V z 300 km/s and with V x , V y in the velocity interval corresponding to the donor star was unexpected. Its presence may indicate, for example, an outflow of matter from a magnetic pole of the supergiant.

Prediction of the Maximum Number of Repetitions and Repetitions in Reserve From Barbell Velocity.

Science.gov (United States)

García-Ramos, Amador; Torrejón, Alejandro; Feriche, Belén; Morales-Artacho, Antonio J; Pérez-Castilla, Alejandro; Padial, Paulino; Haff, Guy Gregory

2018-03-01

To provide 2 general equations to estimate the maximum possible number of repetitions (XRM) from the mean velocity (MV) of the barbell and the MV associated with a given number of repetitions in reserve, as well as to determine the between-sessions reliability of the MV associated with each XRM. After determination of the bench-press 1-repetition maximum (1RM; 1.15 ± 0.21 kg/kg body mass), 21 men (age 23.0 ± 2.7 y, body mass 72.7 ± 8.3 kg, body height 1.77 ± 0.07 m) completed 4 sets of as many repetitions as possible against relative loads of 60%1RM, 70%1RM, 80%1RM, and 90%1RM over 2 separate sessions. The different loads were tested in a randomized order with 10 min of rest between them. All repetitions were performed at the maximum intended velocity. Both the general equation to predict the XRM from the fastest MV of the set (CV = 15.8-18.5%) and the general equation to predict MV associated with a given number of repetitions in reserve (CV = 14.6-28.8%) failed to provide data with acceptable between-subjects variability. However, a strong relationship (median r 2  = .984) and acceptable reliability (CV  .85) were observed between the fastest MV of the set and the XRM when considering individual data. These results indicate that generalized group equations are not acceptable methods for estimating the XRM-MV relationship or the number of repetitions in reserve. When attempting to estimate the XRM-MV relationship, one must use individualized relationships to objectively estimate the exact number of repetitions that can be performed in a training set.

Performance bounds on micro-Doppler estimation and adaptive waveform design using OFDM signals

Science.gov (United States)

Sen, Satyabrata; Barhen, Jacob; Glover, Charles W.

2014-05-01

We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Craḿer-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

Performance Bounds on Micro-Doppler Estimation and Adaptive Waveform Design Using OFDM Signals

Energy Technology Data Exchange (ETDEWEB)

Sen, Satyabrata [ORNL; Barhen, Jacob [ORNL; Glover, Charles Wayne [ORNL

2014-01-01

We analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a target having multiple rotating scatterers (e.g., rotor blades of a helicopter, propellers of a submarine). The presence of rotating scatterers introduces Doppler frequency modulation in the received signal by generating sidebands about the transmitted frequencies. This is called the micro-Doppler effects. The use of a frequency-diverse OFDM signal in this context enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. Therefore, to characterize the accuracy of micro-Doppler frequency estimation, we compute the Cram er-Rao Bound (CRB) on the angular-velocity estimate of the target while considering the scatterer responses as deterministic but unknown nuisance parameters. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the transmitting OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations at different values of the signal-to-noise ratio (SNR) and the number of OFDM subcarriers. The CRB values not only decrease with the increase in the SNR values, but also reduce as we increase the number of subcarriers implying the significance of frequency-diverse OFDM waveforms. The improvement in estimation accuracy due to the adaptive waveform design is also numerically analyzed. Interestingly, we find that the relative decrease in the CRBs on the angular-velocity estimate is more pronounced for larger number of OFDM subcarriers.

Testing the relativistic Doppler boost hypothesis for supermassive black hole binary candidates

Science.gov (United States)

Charisi, Maria; Haiman, Zoltán; Schiminovich, David; D'Orazio, Daniel J.

2018-06-01

Supermassive black hole binaries (SMBHBs) should be common in galactic nuclei as a result of frequent galaxy mergers. Recently, a large sample of sub-parsec SMBHB candidates was identified as bright periodically variable quasars in optical surveys. If the observed periodicity corresponds to the redshifted binary orbital period, the inferred orbital velocities are relativistic (v/c ≈ 0.1). The optical and ultraviolet (UV) luminosities are expected to arise from gas bound to the individual BHs, and would be modulated by the relativistic Doppler effect. The optical and UV light curves should vary in tandem with relative amplitudes which depend on the respective spectral slopes. We constructed a control sample of 42 quasars with aperiodic variability, to test whether this Doppler colour signature can be distinguished from intrinsic chromatic variability. We found that the Doppler signature can arise by chance in ˜20 per cent (˜37 per cent) of quasars in the nUV (fUV) band. These probabilities reflect the limited quality of the control sample and represent upper limits on how frequently quasars mimic the Doppler brightness+colour variations. We performed separate tests on the periodic quasar candidates, and found that for the majority, the Doppler boost hypothesis requires an unusually steep UV spectrum or an unexpectedly large BH mass and orbital velocity. We conclude that at most approximately one-third of these periodic candidates can harbor Doppler-modulated SMBHBs.

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.

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.

Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Lee, Teaghee; Choi, Jong Woon [Department of Information and Communication, Honam University, Seobong-dong 59-1, Gwansan-gu, Gwangju 506-714 (Korea, Republic of); Kim, Yong Pyung [College of Electronics and Information, Kyunghee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2012-09-15

We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO{sub 2} laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

Color doppler energy (CDE) : initial ten-months experience

International Nuclear Information System (INIS)

Ro, Young Jin; Son, Hyun Ju; Lee, Suck Hong; Kim, Byung Soo; Han, Kook Sang; Nam, SAng Hwa; Lee, Keum Seob; Shin Se Kwon

1996-01-01

Color Doppler imaging(CDI) has shortcomings, including random noise, aliasing, and angle dependence. To overcome these, a method using CD US, termed power doppler or Color Doppler Energy(CDE), has recently been introduced. The purpose of this study was to show the clinical usefulness of CDE. We retrospectively analyzed the CDI and CDE of 61 cases(20 renal pseudotumors, 8 musculoskeletal inflammations, 17 epididymitis or epididymo-orchitis, 3 varicoceles, 1 normal testis, 1 hepatocellualr carcinoma, 7 renal cell carcinoma, 1 renal angiomyolipoma, and 3 splenic varices). CDI and CDE scans were obtained at the same region with constant scan plane. The color gain was increased until noise first became perceptible, and scans were always obtained in such a way that the maximum amount of vascularity was shown. Thereafter, the vascularity, vascular displacement, and the vascular relationship between CDI and CDE were compared. In 17 of 20 cases of pseudotumor in the kidney, normal vascularity was identified in CDI and CDE, but was more cleary visible in CDE. In three cases, there was no visible vascularity in CDI, but normal vascularity in CDE. In eight cases of musculoskeletal inflammation and 17 cases of epididymitis with or without orchitis, the vascularity was increased due to hyperemia, which was more prominently seen in CDE than in CDI. In three varicoceles, CDE appeared to be better in demonstrating low velocity flow. In one patient who was suspected of having acute testicular torsion, CDE was helpful in excluding this suspicion. In one case of hepatocellualr carcinoma, seven cases of renal cell carcinoma, one case of renal angiomyolipoma, and three cases of splenic varices, CDE was better than CDI in showing the vascularity, vascular relationship, and vascular displacement

Axial flow velocity patterns in a normal human pulmonary artery model: pulsatile in vitro studies.

Science.gov (United States)

Sung, H W; Yoganathan, A P

1990-01-01

It has been clinically observed that the flow velocity patterns in the pulmonary artery are directly modified by disease. The present study addresses the hypothesis that altered velocity patterns relate to the severity of various diseases in the pulmonary artery. This paper lays a foundation for that analysis by providing a detailed description of flow velocity patterns in the normal pulmonary artery, using flow visualization and laser Doppler anemometry techniques. The studies were conducted in an in vitro rigid model in a right heart pulse duplicator system. In the main pulmonary artery, a broad central flow field was observed throughout systole. The maximum axial velocity (150 cm s-1) was measured at peak systole. In the left pulmonary artery, the axial velocities were approximately evenly distributed in the perpendicular plane. However, in the bifurcation plane, they were slightly skewed toward the inner wall at peak systole and during the deceleration phase. In the right pulmonary artery, the axial velocity in the perpendicular plane had a very marked M-shaped profile at peak systole and during the deceleration phase, due to a pair of strong secondary flows. In the bifurcation plane, higher axial velocities were observed along the inner wall, while lower axial velocities were observed along the outer wall and in the center. Overall, relatively low levels of turbulence were observed in all the branches during systole. The maximum turbulence intensity measured was at the boundary of the broad central flow field in the main pulmonary artery at peak systole.

Doppler speedometer for micro-organisms

International Nuclear Information System (INIS)

Penkov, F.; Tuleushev, A.; Lisitsyn, V.; Kim, S.; Tuleushev, Yu.

1996-01-01

Objective of Investigations: Development and creation of the Doppler speedometer for micro-organisms which allows to evaluate, in a real temporal scale, variations in the state of water suspension of micro-organisms under the effect of chemical, physical and other external actions. Statement of the Problem The main problem is absence of reliable, accessible for users and simple, in view of application, Doppler speedometers for micro-organisms. Nevertheless, correlation Doppler spectrometry in the regime of heterodyning the supporting and cell-scattered laser radiation is welt known. The main idea is that the correlation function of photo-current pulses bears an information on the averages over the assembly of cell velocities. For solving the biological problems, construction of auto-correlation function in the real-time regime with the delay time values comprising, function in the real-time regime with the delay time values comprising, nearly, 100 me (10 khz) or higher is needed. Computers of high class manage this problem using but the program software. Due to this, one can simplify applications of the proposed techniques provided he creates the Doppler speedometer for micro-organism on a base of the P entium . Expected Result Manufactured operable mock-up of the Doppler speedometer for micro-organisms in a form of the auxiliary computer block which allows to receive an information, in the real time scale, on the results of external effects of various nature on the cell assembly in transparent medium with a small volume of the studied cell suspension

Digital storage and analysis of color Doppler echocardiograms

Science.gov (United States)

Chandra, S.; Thomas, J. D.

1997-01-01

Color Doppler flow mapping has played an important role in clinical echocardiography. Most of the clinical work, however, has been primarily qualitative. Although qualitative information is very valuable, there is considerable quantitative information stored within the velocity map that has not been extensively exploited so far. Recently, many researchers have shown interest in using the encoded velocities to address the clinical problems such as quantification of valvular regurgitation, calculation of cardiac output, and characterization of ventricular filling. In this article, we review some basic physics and engineering aspects of color Doppler echocardiography, as well as drawbacks of trying to retrieve velocities from video tape data. Digital storage, which plays a critical role in performing quantitative analysis, is discussed in some detail with special attention to velocity encoding in DICOM 3.0 (medical image storage standard) and the use of digital compression. Lossy compression can considerably reduce file size with minimal loss of information (mostly redundant); this is critical for digital storage because of the enormous amount of data generated (a 10 minute study could require 18 Gigabytes of storage capacity). Lossy JPEG compression and its impact on quantitative analysis has been studied, showing that images compressed at 27:1 using the JPEG algorithm compares favorably with directly digitized video images, the current goldstandard. Some potential applications of these velocities in analyzing the proximal convergence zones, mitral inflow, and some areas of future development are also discussed in the article.

Effect of Doppler flow meter position on discharge measurement in surcharged manholes.

Science.gov (United States)

Yang, Haoming; Zhu, David Z; Liu, Yanchen

2018-02-01

Determining the proper installation location of flow meters is important for accurate measurement of discharge in sewer systems. In this study, flow field and flow regimes in two types of manholes under surcharged flow were investigated using a commercial computational fluid dynamics (CFD) code. The error in measuring the flow discharge using a Doppler flow meter (based on the velocity in a Doppler beam) was then estimated. The values of the corrective coefficient were obtained for the Doppler flow meter at different locations under various conditions. Suggestions for selecting installation positions are provided.

Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

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T. D. Borisova

2002-09-01

Full Text Available Comparisons between bistatic scatter measurements and simulation results during the Tromsø HF pumping experiment on 16 February 1996 are made. Doppler measurements of an HF diagnostic signal scattered from the field-aligned irregularities (FAIs in the auroral E-region were carried out on the London – Tromsø – St. Petersburg path at 9410 kHz from 21:00 to 22:00 UT. The scattered signals were observed both from natural and artificial ionospheric irregularities located in the vicinity of Tromsø. To simulate the Doppler frequency shifts, fd , of scattered signals, a radio channel model, named CONE, was developed. The model allows for ray tracing, group and phase paths, and Doppler frequency shift calculations. The calculated Doppler shifts were analyzed for dependence on the magnitude and direction of plasma velocities in the scattering volume. It was found that the velocity components in the north-south direction are crucial for explaining the Doppler frequency shifts of the scattered diagnostic signals. To simulate fd , real velocities obtained from the EISCAT UHF radar at an altitude of 278 km and from the digital all-sky imager during the experiment were employed. The simulation results of Doppler frequency shift variations with time are in reasonable agreement with the experimental Doppler shifts of scattered signals on the London – Tromsø – St. Petersburg path.Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

The effect of blood acceleration on the ultrasound power Doppler spectrum

Science.gov (United States)

Matchenko, O. S.; Barannik, E. A.

2017-09-01

The purpose of the present work was to study the influence of blood acceleration and time window length on the power Doppler spectrum for Gaussian ultrasound beams. The work has been carried out on the basis of continuum model of the ultrasound scattering from inhomogeneities in fluid flow. Correlation function of fluctuations has been considered for uniformly accelerated scatterers, and the resulting power Doppler spectra have been calculated. It is shown that within the initial phase of systole uniformly accelerated slow blood flow in pulmonary artery and aorta tends to make the correlation function about 4.89 and 7.83 times wider, respectively, than the sensitivity function of typical probing system. Given peak flow velocities, the sensitivity function becomes, vice versa, about 4.34 and 3.84 times wider, respectively, then the correlation function. In these limiting cases, the resulting spectra can be considered as Gaussian. The optimal time window duration decreases with increasing acceleration of blood flow and equals to 11.62 and 7.54 ms for pulmonary artery and aorta, respectively. The width of the resulting power Doppler spectrum is shown to be defined mostly by the wave vector of the incident field, the duration of signal and the acceleration of scatterers in the case of low flow velocities. In the opposite case geometrical properties of probing field and the average velocity itself are more essential. In the sense of signal-noise ratio, the optimal duration of time window can be found. Abovementioned results may contribute to the improved techniques of Doppler ultrasound diagnostics of cardiovascular system.

Precession feature extraction of ballistic missile warhead with high velocity

Science.gov (United States)

Sun, Huixia

2018-04-01

This paper establishes the precession model of ballistic missile warhead, and derives the formulas of micro-Doppler frequency induced by the target with precession. In order to obtain micro-Doppler feature of ballistic missile warhead with precession, micro-Doppler bandwidth estimation algorithm, which avoids velocity compensation, is presented based on high-resolution time-frequency transform. The results of computer simulations confirm the effectiveness of the proposed method even with low signal-to-noise ratio.

Dynamic exercise enhances regional cerebral artery mean flow velocity

DEFF Research Database (Denmark)

Linkis, P; Jørgensen, L G; Olesen, H L

1995-01-01

Dynamic exercise enhances regional cerebral artery mean flow velocity. J. Appl. Physiol. 78(1): 12-16, 1995.--Anterior (ACA) and middle (MCA) cerebral artery mean flow velocities (Vmean) and pulsatility indexes were determined using transcranial Doppler in 14 subjects during dynamic exercise afte...

Changes in Doppler flow velocity waveforms and fetal size at 20 weeks gestation among cigarette smokers.

Science.gov (United States)

Kho, E M; North, R A; Chan, E; Stone, P R; Dekker, G A; McCowan, L M E

2009-09-01

To compare umbilical and uterine artery Doppler waveforms and fetal size at 20 weeks between smokers and nonsmokers. Prospective cohort study. Auckland, New Zealand and Adelaide, Australia. Nulliparous participants in the Screening for Pregnancy Endpoints (SCOPE) study. Self-reported smoking status was determined at 15 +/- 1 weeks' gestation. At the 20 +/- 1 week anatomy scan, uterine and umbilical Doppler resistance indices (RI) and fetal measurements were compared between smokers and nonsmokers. Umbilical and mean uterine artery Doppler RI values, abnormal umbilical and uterine Doppler (RI > 90th centile) and fetal biometry. Among the 2459 women, 248 (10%) were smokers. Smokers had higher umbilical RI [0.75 (SD 0.06) versus 0.73 (0.06), P gestation, women who smoke have higher umbilical artery RI, a surrogate measure for an abnormal placental villous vascular tree. This may contribute to later fetal growth restriction among smokers. Further research is needed to explore the clinical significance of these findings.

Diagnosis of brain death by transcranial Doppler sonography.

Science.gov (United States)

Bode, H; Sauer, M; Pringsheim, W

1988-12-01

The blood flow velocities in the basal cerebral arteries can be recorded at any age by transcranial Doppler sonography. We examined nine children with either initial or developing clinical signs of brain death. Soon after successful resuscitation increased diastolic flow velocities indicated a probable decrease in cerebrovascular resistance; this was of no particular prognostic importance. As soon as there was a clinical deterioration, there was a reduction in flow velocities with retrograde flow during early diastole, probably due to an increase in cerebrovascular resistance; this indicated a doubtful prognosis. In eight of the nine children with clinical signs of brain death a typical reverberating flow pattern was found, which was characterised by a counterbalancing short forward flow in systole and a short retrograde flow in early diastole. This indicated arrest of cerebral blood flow. One newborn showed normal systolic and end diastolic flow velocities in the basal cerebral arteries for two days despite clinical and electroencephalographic signs of brain death. Shunting of blood through the circle of Willis without effective cerebral perfusion may explain this phenomenon. No patient had the typical reverberating flow pattern without being clinically brain dead. Transcranial Doppler sonography is a reliable technique, which can be used at the bedside for the confirmation or the exclusion of brain death in children in addition to the clinical examination.

Doppler reflectometry for the investigation of poloidally propagating density perturbations

International Nuclear Information System (INIS)

Hirsch, M.; Baldzuhn, J.; Kurzan, B.; Holzhauer, E.

1999-01-01

A modification of microwave reflectometry is discussed where the direction of observation is tilted with respect to the normal onto the reflecting surface. The experiment is similar to scattering where a finite resolution in k-space exists but keeps the radial localization of reflectometry. The observed poloidal wavenumber is chosen by Bragg's condition via the tilt angle and the resolution in k-space is determined by the antenna pattern. From the Doppler shift of the reflected wave the poloidal propagation velocity of density perturbations is obtained. The diagnostic capabilities of Doppler reflectometry are investigated using full wave code calculations. The method offers the possibility to observe changes in the poloidal propagation velocity of density perturbations and their radial shear with a temporal resolution of about 10μs. (authors)

Three-dimensional power Doppler sonography: imaging and quantifying blood flow and vascularization.

Science.gov (United States)

Pairleitner, H; Steiner, H; Hasenoehrl, G; Staudach, A

1999-08-01

To assess the feasibility of imaging low-velocity blood flow in adnexal masses by transvaginal three-dimensional power Doppler sonography, to analyze three-dimensional power Doppler sonography data sets with a new computer-assisted method and to test the reproducibility of the technique. A commercially available 5-MHz Combison 530 ultrasound system was used to perform three-dimensional power Doppler sonography transvaginally. A cube (= volume of interest) was defined enclosing the vessels of the cyst and the Cartesian characteristics were stored on a hard disk. This cube was analyzed using specially designed software. Five indices representing vascularization (the vascularization index (VI) or blood flow (the flow index (FI)) or both (the vascularization-flow index (VFI)) were calculated. The intraobserver repeatability of cube definition and scan repetition was assessed using Hartley's test for homogeneous variances. Interobserver agreement was assessed by the Pearson correlation coefficient. Imaging of vessels with low-velocity blood flow by three-dimensional power Doppler sonography and cube definition was possible in all adnexal massed studied. In some cases even induced non-vascular flow related to endometriosis was detected. The calculated F value with intraobserver repeated Cartesian file-saving ranged from 0 to 18.8, with intraobserver scan repetition from 4.74 to 24.8 for VI, FI 1, FI 2 and VFI 1; for VFI 2 the calculated F value was 64. The interobserver correlation coefficient ranged between 0.83 and 0.92 for VI, FI 1, FI 2 and VFI 1; for VFI 2 the correlation coefficient was less than 0.75. Vessels with low-velocity blood flow can be imaged using three-dimensional power Doppler sonography. Induced non-vascular flow was detected in endometriotic cyst fluid. Three-dimensional power Doppler sonography combined with the cube method gave reproducible information for all indices except VFI 2. These indices might prove to be a new predictor in all fields of

Simulation study on detection performance of eye-safe coherent Doppler wind lidar operating near 1.6 μm

Science.gov (United States)

Ma, Han; Wang, Qing; Na, Quanxin; Gao, Mingwei

2018-01-01

Coherent Doppler wind lidars (CDWL) are widely used in aerospace, atmospheric monitoring and other fields. The parameters of laser source such as the wavelength, pulse energy, pulse duration and pulse repetition rate (PRR) have significant influences on the detection performance of wind lidar. We established a simulation model which takes into account the effects of atmospheric transmission, backscatter, atmospheric turbulence and parameters of laser source. The maximum detection range is also calculated under the condition that the velocity estimation accuracy is 0.1 m/s by using this model. We analyzed the differences of the detection performance between two operation systems, which show the high pulse energy-low pulse repetition rate (HPE-LPRR) and low pulse energy-high repetition rate (LPE-HPRR), respectively. We proved our simulation model reliable by using the parameters of two commercial lidar products. This research has important theoretical and practical values for the design of eye-safe coherent Doppler wind lidar.

Size and velocity measurements in combustion systems

International Nuclear Information System (INIS)

Levy, Y.; Timnat, Y.M.

1986-01-01

Two-phase flow measurements for size and velocity determination in combustion systems are discussed: the pedestal technique and phase Doppler anemometry (PDA) are described in detail. The experimental apparatus for the pedestal method includes the optical laser-Doppler anemometry (LDA) package and the electronic data acquisition system. The latter comprises three channels for recording the Doppler frequency, and the pedestal amplitude as well as the validation pulse. Results of measurements performed in a dump combustor, into which kerosene droplets were injected, are presented. The principle of the PDA technique is explained and validation experiments, using latex particles, are reported. Finally the two methods are compared

[The value of spectral frequency analysis by Doppler examination (author's transl)].

Science.gov (United States)

Boccalon, H; Reggi, M; Lozes, A; Canal, C; Jausseran, J M; Courbier, R; Puel, P; Enjalbert, A

1981-01-01

Arterial stenoses of moderate extent may involve modifications of the blood flow. Arterial shading is not always examined at the best incident angle to assess the extent of the stenosis. Spectral frequency analysis by Doppler examination is a good means of evaluating the effect of moderate arterial lesions. The present study was carried out with a Doppler effect having an acoustic spectrum, which is shown in a histogram having 16 frequency bands. The values were recorded on the two femoral arteries. A study was also made of 49 normal subjects so as to establish a normal envelope histogram, taking into account the following parameters: maximum peak (800 Hz), low cut-off frequency (420 Hz), high cut-off frequency (2,600 Hz); the first peak was found to be present in 81 % of the subjects (at 375 Hz) and the second peak in 75 % of the subjects (2,020 Hz). Thirteen patients with iliac lesions of different extent were included in the study; details of these lesions were established in all cases by aortography. None of the recorded frequency histograms were located within the normal envelope. Two cases of moderate iliac stenoses were noted ( Less Than 50 % of the diameter) which interfered with the histogram, even though the femoral velocity signal was normal.

Local Doppler Effect, Index of Refraction through the Earth Crust, PDF and the CNGS Neutrino Anomaly?

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Assis A. V. D. B.

2012-04-01

Full Text Available In this brief paper, we show the neutrino velocity discrepancy obtained in the OPERA experiment may be due to the local Doppler effect between a local clock attached to a given detector at Gran Sasso, say C G , and the respective instantaneous clock crossing C G , say C C , being this latter at rest in the instantaneous inertial frame having got the velocity of rotation of CERN about Earth’s axis in relation to the fixed stars. With this effect, the index of refraction of the Earth crust may accomplish a refractive effect by which the neutrino velocity through the Earth crust turns out to be small in relation to the speed of light in the empty space, leading to an encrusted discrepancy that may have contamined the data obtained from the block of detectors at Gran Sasso, leading to a time interval excess that did not provide an exact match between the shift of the protons PDF (probability distribution function by TOF c and the detection data at Gran Sasso via the maximum likelihood matching.

Moving Target Detection With Compact Laser Doppler Radar

Science.gov (United States)

Sepp, G.; Breining, A.; Eisfeld, W.; Knopp, R.; Lill, E.; Wagner, D.

1989-12-01

This paper describes an experimental integrated optronic system for detection and tracking of moving objects. The system is based on a CO2 waveguide laser Doppler ra-dar with homodyne receiver and galvanometer mirror beam scanner. A "hot spot" seeker consisting of a thermal imager with image processor transmits the coordinates of IR-emitting, i.e. potentially powered, objects to the laser radar scanner. The scanner addresses these "hot" locations operating in a large field-of-view (FOV) random ac-cess mode. Hot spots exhibiting a Doppler shifted laser signal are indicated in the thermal image by velocity-to-colour encoded markers. After switching to a small FOV scanning mode, the laser Doppler radar is used to track fast moving objects. Labora-tory and field experiments with moving objects including rotating discs, automobiles and missiles are described.

Flow measurement by Laser Doppler Anemometry in a nuclear fuel assembly

International Nuclear Information System (INIS)

Kehoe, A.

1984-12-01

Development of a Laser Doppler Anemometer measurement system and its operation are examined in this research. The system is designed for flow measurement in laboratory models of nuclear fuel assemblies. Use of the system is demonstrated by measuring turbulent velocity profiles in the laboratory model at full scale reactor flow rates. The reactors at the Savanah River Plant (SRP) are heavy water moderated and operate at low temperatures and pressures. Reactor power is currently limited by the temperature of the water in the nuclear fuel assembly. These temperature limits are conservatively calculated without allowing for any turbulent mixing. This research incorporates the design, fabriction and operation of a plexiglas model fuel assembly for the purpose of making turbulent velocity measurement via a Laser Doppler Anemometer System

Variações de parâmetros da função diastólica do ventrículo esquerdo de acordo com a idade através da ecocardiografia com Doppler tissular Changes in the parameters of left ventricular diastolic function according to age on tissue Doppler imaging

Directory of Open Access Journals (Sweden)

Márcia Duarte Pedone

2004-12-01

Full Text Available OBJETIVO: Determinar a correlação entre as velocidades diastólicas do Doppler tissular com a idade em amostra de adultos saudáveis, e correlacionar a idade com as velocidades do fluxo transmitral e de veias pulmonares. MÉTODOS: Estudados, através da ecocardiografia, 51 indivíduos saudáveis, com idades entre 21 e 69 anos e registradas as velocidades miocárdicas diastólicas ao Doppler tissular e determinadas as velocidades dos fluxos transmitral e venoso pulmonar. RESULTADOS: As velocidades miocárdicas diastólicas iniciais septal basal e lateral basal apresentaram correlação inversa com a idade, com r = - 0,40 (p = 0,004 e r = - 0,60 (p = 0,0001 respectivamente. As velocidades atriogênicas do Doppler tissular foram diretamente correlacionadas com a idade, sendo no segmento septal basal r = 0,56 (p = 0,0001 e no segmento lateral basal r = 0,50 (p = 0,0001. As velocidades do fluxo transmitral e do fluxo venoso pulmonar também mostraram correlação com a idade. CONCLUSÃO: Existe correlação entre a idade e as velocidades miocárdicas diastólicas do Doppler tissular e com as velocidades do fluxo transmitral e fluxo venoso pulmonar, demonstrando em indivíduos saudáveis uma variação de parâmetros da função diastólica do ventrículo esquerdo com a evolução natural da idade.OBJECTIVE: To determine the correlation between diastolic velocities on tissue Doppler imaging and age in a sample of healthy adults and to correlate age with the velocities of transmitral and pulmonary vein flows. METHODS: Echocardiographic assessment of 51 healthy individuals, whose ages ranged from 21 to 69 years. The diastolic myocardial velocities were recorded on tissue Doppler imaging. The velocities of the transmitral and pulmonary vein flows were also determined. RESULTS: The initial basal septal and basal lateral diastolic myocardial velocities showed an inverse correlation with age [r = - 0.40 (P = 0.004, and r = - 0.60 (P = 0.0001, respectively

Laser Doppler vibrometry experiment on a piezo-driven slot synthetic jet in water

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Broučková Zuzana

2015-01-01

Full Text Available The present study deals with a slot synthetic jet (SJ issuing from an actuator into quiescent surroundings and driven by a piezoceramic transducer. The actuator slot width was 0.36 mm, with a drive frequency proposed near the theoretical natural frequency of the actuator. The working fluid was water at room temperature. The present experiments used flow visualization (a laser-induced fluorescence technique and laser Doppler vibrometry methods. Flow visualization was used to identify SJ formation, to demonstrate its function, and to estimate SJ velocity. Laser Doppler vibrometry was used to quantify diaphragm displacement and refine operating parameters. Phase averaging yielded a spatial and temporal diaphragm deflection during the actuation period. Taking incompressibility and continuity into consideration, the velocity in the actuator slot and the Reynolds number of the SJ were evaluated as 0.21 m/s and 157, respectively. The present results confirmed a SJ actuator function at the resonance frequency of approximately 46 Hz, which corresponds closely with the theoretical evaluation. The laser Doppler vibrometry results corresponded closely with an estimation of SJ velocity by the present flow visualization.

Evaluation of factors influencing arterial Doppler waveforms in an in vitro flow phantom

Energy Technology Data Exchange (ETDEWEB)

Sung, Chang Kyu [Dept. of Radiology, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul (Korea, Republic of); Lee, Kyoung Ho [Dept. of Radiology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam (Korea, Republic of); Kim, Seung Hyup [Dept. of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul (Korea, Republic of)

2017-01-15

The aim of this study was to investigate factors that influence arterial Doppler waveforms in an in vitro phantom to provide a more accurate and comprehensive explanation of the Doppler signal. A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinations of compliance, resistance, and pulse rate. Peak systolic velocity, minimum diastolic velocity, resistive index (RI), pulsatility index, early systolic acceleration time, and acceleration index were measured. On the basis of these measurements, the influences of the variables on the Doppler waveforms were analyzed. With increasing distal resistance, the RI increased in a relatively linear relationship. With increasing proximal resistance, the RI decreased. The pulsus tardus and parvus phenomenon was observed with a small acceleration index in the model with a higher grade of stenosis. An increase in the distal resistance masked the pulsus tardus and parvus phenomenon by increasing the acceleration index. Although this phenomenon occurred independently of compliance, changes in the compliance of proximal or distal tubes caused significant changes in the Doppler waveform. There was a reverse relationship between the RI and the pulse rate. Resistance and compliance can alter the Doppler waveforms independently. The pulse rate is an extrinsic factor that also influences the RI. The compliance and distal resistance, as well as proximal resistance, influence the pulsus tardus and parvus phenomenon.

Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996

Directory of Open Access Journals (Sweden)

T. D. Borisova

Full Text Available Comparisons between bistatic scatter measurements and simulation results during the Tromsø HF pumping experiment on 16 February 1996 are made. Doppler measurements of an HF diagnostic signal scattered from the field-aligned irregularities (FAIs in the auroral E-region were carried out on the London – Tromsø – St. Petersburg path at 9410 kHz from 21:00 to 22:00 UT. The scattered signals were observed both from natural and artificial ionospheric irregularities located in the vicinity of Tromsø. To simulate the Doppler frequency shifts, f_d , of scattered signals, a radio channel model, named CONE, was developed. The model allows for ray tracing, group and phase paths, and Doppler frequency shift calculations. The calculated Doppler shifts were analyzed for dependence on the magnitude and direction of plasma velocities in the scattering volume. It was found that the velocity components in the north-south direction are crucial for explaining the Doppler frequency shifts of the scattered diagnostic signals. To simulate f_d , real velocities obtained from the EISCAT UHF radar at an altitude of 278 km and from the digital all-sky imager during the experiment were employed. The simulation results of Doppler frequency shift variations with time are in reasonable agreement with the experimental Doppler shifts of scattered signals on the London – Tromsø – St. Petersburg path.

Key words. Ionosphere (active experiments; ionospheric irregularities Radio science (ionospheric propagation

Doppler ultrasound scan during normal gestation: umbilical circulation; Ecografia Doppler en la gestacion normal: circulacion umbilical

Energy Technology Data Exchange (ETDEWEB)

Ruiz, T.; Sabate, J.; Martinez-Benavides, M. M.; Sanchez-Ramos, J. [Hospital Virgen Macarena. Sevilla (Spain)

2002-07-01

To determine normal umbilical circulation patterns by means of Doppler ultrasound scan in a healthy gestating population without risk factors and with normal perinatal results, and to evaluate any occurring modifications relative to gestational age by obtaining records kept during pregnancy. One hundred and sixteen pregnant women carrying a single fetus have been studied. These women had no risk factors, with both clinical and analytical controls, as well as ultrasound scans, all being normal. There were performed a total of 193 Doppler ultrasound scans between weeks 15 and 41 of gestation, with blood-flow analysis in the arteries and vein of the umbilical cord. The obtained information was correlated with parameters that evaluate fetal well-being (fetal monitoring and/or oxytocin test) and perinatal result (delivery type, birth weight, Apgar score). Statistical analysis was performed with the programs SPSS 6.0.1 for Windows and EPIINFO 6.0.4. With pulsed Doppler, the umbilical artery in all cases demonstrated a biphasic morphology with systolic and diastolic components and without retrograde blood flow. As the gestation period increased, there was observed a progressive decrease in resistance along with an increase in blood-flow velocity during the diastolic phase. The Doppler ultrasound scan is a non-invasive method that permits the hemodynamic study of umbilical blood circulation. A knowledge of normal blood-flow signal morphology, as well as of the normal values for Doppler indices in relation to gestational age would permit us to utilize this method in high-risk pregnancies. (Author) 30 refs.

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.

Velocity Statistics and Spectra in Three-Stream Jets

Science.gov (United States)

Ecker, Tobias; Lowe, K. Todd; Ng, Wing F.; Henderson, Brenda; Leib, Stewart

2016-01-01

Velocimetry measurements were obtained in three-stream jets at the NASA Glenn Research Center Nozzle Acoustics Test Rig using the time-resolved Doppler global velocimetry technique. These measurements afford exceptional frequency response, to 125 kHz bandwidth, in order to study the detailed dynamics of turbulence in developing shear flows. Mean stream-wise velocity is compared to measurements acquired using particle image velocimetry for validation. Detailed results for convective velocity distributions throughout an axisymmetric plume and the thick side of a plume with an offset third-stream duct are provided. The convective velocity results exhibit that, as expected, the eddy speeds are reduced on the thick side of the plume compared to the axisymmetric case. The results indicate that the time-resolved Doppler global velocimetry method holds promise for obtaining results valuable to the implementation and refinement of jet noise prediction methods being developed for three-stream jets.

Design And Analysis Of Doppler Radar-Based Vehicle Speed Detection

Directory of Open Access Journals (Sweden)

Su Myat Paing

2015-08-01

Full Text Available The most unwanted thing to happen to a road user is road accident. Most of the fatal accidents occur due to over speeding. Faster vehicles are more prone to accident than the slower one. Among the various methods for detecting speed of the vehicle object detection systems based on Radar have been replaced for about a century for various purposes like detection of aircrafts spacecraft ships navigation reading weather formations and terrain mapping. The essential feature in adaptive vehicle activated sign systems is the accurate measurement of a vehicles velocity. The velocities of the vehicles are acquired from a continuous wave Doppler radar. A very low amount of power is consumed in this system and only batteries can use to operate. The system works on the principle of Doppler Effect by detecting the Doppler shift in microwaves reflected from a moving object. Since the output of the sensor is sinusoidal wave with very small amplitude and needs to be amplified with the help of the amplifier before further processing. The purpose to calculate and display the speed on LCD is performed by the microcontroller.

Superimposed noninterfering probes to extend the capabilities of phase Doppler anemometry.

Science.gov (United States)

Onofri, Fabrice; Lenoble, Anne; Radev, Stefan

2002-06-20

We propose using multiple superimposed noninterfering probes (SNIPs) of the same wavelength but different beam angles to extend the capabilities of phase Doppler anemometry. When a particle is moving in a SNIP the Doppler signals that are produced exhibit multiple Doppler frequencies and phase shifts. The resolution of the measurements of particle size (i.e., by fringe spacing and Doppler frequency) increases with beam angle. Then, with the solution proposed, even with only two detectors several measurements of size can be obtained for the same particle with increasing resolution if we consider higher frequencies in the signal. Several optical solutions to produce SNIPs as well as a signal-processing algorithm to treat the multiple-frequency Doppler signals are proposed. Experimental validations of the sizing of spherical and cylindrical particles demonstrate the applicability of this technique for particle measurement. We believe that this new technique can be of great interest when high resolution of size, velocity, and even refractive index is required.

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

Energy Technology Data Exchange (ETDEWEB)

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

2000-10-01

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.

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

Doppler color flow mapping of peripheral vessels: Comparison of angiodynography with conventional duplex US

International Nuclear Information System (INIS)

Merritt, C.R.B.; Bluth, E.I.; Sullivan, M.A.

1986-01-01

A new Doppler color flow imager was compared to duplex US in the evaluation of carotid and peripheral vessels in 50 patients. A 7.5-MHz transducer permitted simultaneous high-resolution real-time imaging of Doppler flow and tissue. The system was found to have excellent image quality and Doppler sensitivity. Flow characteristics and velocity measurements obtained with this system correlated well with those obtained using the duplex scanner and were obtained more quickly than with the conventional system, allowing more complete assessment of flow characteristics. Color Doppler flow imaging appears to be an extremely promising method for the rapid and effective evaluation of peripheral vascular flow

Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

Energy Technology Data Exchange (ETDEWEB)

Kaganovich, Igor D.; Massidda, Scottt; Startsev, Edward A.; Davidson, Ronald C.; Vay, Jean-Luc; Friedman, Alex

2012-06-21

Neutralized drift compression offers an effective means for particle beam pulse compression and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt (head-to-tail gradient) is applied to the non-relativistic beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam current can increase by more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limit the maximum longitudinal compression. It is found that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, a part of the beam pulse where the errors are small may compress to much higher values, which are determined by the initial thermal spread of the beam pulse. It is also shown that sharp jumps in the compressed current density profile can be produced due to overlaying of different parts of the pulse near the focal plane. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied. For beam velocity errors given by a cubic function, the compression ratio can be described analytically. In this limit, a significant portion of the beam pulse is located in the broad wings of the pulse and is poorly compressed. The central part of the compressed pulse is determined by the thermal spread. The scaling law for maximum compression ratio is derived. In addition to a smooth variation in the velocity tilt, fast-changing errors during the pulse may appear in the induction bunching module if the voltage pulse is formed by several pulsed elements. Different parts of the pulse compress nearly simultaneously at the target and the compressed profile may have many peaks. The maximum compression is a function of both thermal spread and the velocity errors. The effects of the

Biometric, B-mode and color Doppler ultrasound assessment of eyes in healthy dogs

Directory of Open Access Journals (Sweden)

Elzivânia G. Silva

Full Text Available ABSTRACT: B-scan ultrasonography is an important diagnostic tool that allows characterization of internal organ anatomy and, when complemented by Doppler ultrasound, allows vascular hemodynamic assessment, increasing the diagnostic accuracy. Thus, the aim of the present study was the B-scan ultrasound characterization and measurement of the eyeball segments and assessment of the external ophthalmic artery by color and pulsed Doppler. Sixty eyeballs were assessed from 30 dogs of different breeds using an 8.5MHz microconvex transductor. First, biometry was performed by B-scan of the following segments: axial length (M1, anterior chamber depth (M2, lens thickness (M3, lens length (M4, vitreous chamber depth (M5, optical disc length (M6 and optic nerve diameter (M7. Colored Doppler identified the external ophthalmic article and pulsed Doppler assessed its flow, and the following were measured: systolic peak velocity (VPS, final diastolic velocity (VDF, resistivity index (IR and pulse index (IP. No statistical difference was observed for the biometric values of the eye segments between the right and left eyes (p>0.05. The vitreous chamber depth (M5 was shown to be the biometric variable with greatest bilateral symmetry, varying from 0.79 to 0.87cm and 0.78 to 0.86cm for the right and left eye, respectively. The ophthalmic artery was visualized over the optic nerve towards the eyeball, with flow stained red. There was no significant statistical difference between the Doppler velocimetric values for the ophthalmic artery between the right and left eye of the animals assessed (p>0.05. The mean resistivity index (RI showed average values equal to 0.63±0.03, bilaterally. The mean base velocity was 17.50cm/s and 18.18cm/s at the systolic peak and 6.21cm/s and 6.68cm/s at the end of the diastole, for the right and left eyes respectively. The anatomic, biometric and hemodynamic characterization using the ultrasound B-scan and the Doppler modalities

Measurement of thermal plasma jet temperature and velocity by laser light lineshape analysis

International Nuclear Information System (INIS)

Snyder, S.C.; Reynolds, L.D.

1991-01-01

Two important parameters of thermal plasma jets are kinetic or gas temperatures and flow velocity. Gas temperatures have been traditionally measured using emission spectroscopy, but this method depends on either the generally unrealistic assumption of the existence of local thermodynamic equilibrium (LTE) within the plasma, or the use of various non-LTE or partial LTE models to relate the intensity of the emission lines to the gas temperature. Plasma jet velocities have been measured using laser Doppler velocimetry on particles injected into the plasma. However, this method is intrusive and it is not known how well the particle velocities represent the gas velocity. Recently, plasma jet velocities have been measured from the Doppler shift of laser light scattered by the plasma. In this case, the Doppler shift was determined from the difference in the transmission profile of a high resolution monochromator between red shifted and blue shifted scattered light. A direct approach to measuring localized temperatures and velocities is afforded by high resolution scattered light lineshape measurements. The linewidth of laser light scattered by atoms and ions can be related to the kinetic temperature without LTE assumptions, while a shift in the peak position relative to the incident laser lineshape yields the gas velocity. We report in this paper work underway to measure gas temperatures and velocities in an argon thermal plasma jet using high resolution lineshape analysis of scattered laser light

Sub-Doppler cooling in reduced-period optical lattice geometries

International Nuclear Information System (INIS)

Berman, P.R.; Raithel, G.; Zhang, R.; Malinovsky, V.S.

2005-01-01

It is shown that sub-Doppler cooling occurs in an atom-field geometry that can lead to reduced-period optical lattices. Four optical fields are combined to produce a 'standing wave' Raman field that drives transitions between two ground state sublevels. In contrast to conventional Sisyphus cooling, sub-Doppler cooling to zero velocity occurs when all fields are polarized in the same direction. Solutions are obtained using both semiclassical and quantum Monte Carlo methods in the case of exact two-photon resonance. The connection of the results with conventional Sisyphus cooling is established using a dressed state basis

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

International Nuclear Information System (INIS)

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. (paper)

Comparison of magnetic resonance imaging and Laser Doppler Anemometry velocity measurements downstream of replacement heart valves: implications for in vivo assessment of prosthetic valve function.

Science.gov (United States)

Fontaine, A A; Heinrich, R S; Walker, P G; Pedersen, E M; Scheidegger, M B; Boesiger, P; Walton, S P; Yoganathan, A P

1996-01-01

The non-invasive, in-vivo assessment of prosthetic valve function is compromised by the lack of accurate measurements of the transvalvular flow fields or hemodynamics by current techniques. Short echo time magnetic resonance imaging (MRI) may provide a method for the non-invasive, in vivo assessment of prosthetic valve function by accurately measuring changes in the transvalvular flow fields associated with normal and dysfunctional prosthetic valves. The objectives of these in vitro experiments were to investigate the potential for using MRI as a tool to measure the complex flow fields distal to replacement heart valves, and to assess the accuracy of MRI velocity measurements by comparison with Laser Doppler Anemometry (LDA), a gold standard. The velocity fields downstream of tilting disc, bileaflet, ball and cage, and pericardial tissue valves were measured using both three-component LDA and MRI phase velocity encoding under a steady flow rate of 22.8 l/min, simulating peak systolic flow. The valves were tested under normal and stenotic conditions to assess the MRI capabilities under a wide range of local flow conditions, velocities and turbulence levels. A new short echo time MRI technique (FAcE), which allowed velocity measurements in stenotic jets with high turbulence, was tested. Good overall agreement was obtained between the MRI velocity measurements and the LDA data. The MRI velocity measurements adequately reproduced the spatial structure of the flow fields. In most cases peak velocities were accurately measured to within 15%. The results indicate that the FAcE MRI method has the potential to be used as a diagnostic tool to assess prosthetic valve function.

Middle cerebral artery flow velocity waveforms in fetal hypoxaemia.

Science.gov (United States)

Vyas, S; Nicolaides, K H; Bower, S; Campbell, S

1990-09-01

In 81 small-for-gestational age fetuses (SGA) colour flow imaging was used to identify the fetal middle cerebral artery for subsequent pulsed Doppler studies. Impedence to flow (pulsatility index; PI) was significantly lower, and mean blood velocity was significantly higher, than the respective reference ranges with gestation. Fetal blood sampling by cordocentesis was performed in all SGA fetuses and a significant quadratic relation was found between fetal hypoxaemia and the degree of reduction in the PI of FVWs from the fetal middle cerebral artery. Thus, maximum reduction in PI is reached when the fetal PO2 is 2-4 SD below the normal mean for gestation. When the oxygen deficit is greater there is a tendency for the PI to rise, and this presumably reflects the development of brain oedema.

Investigation of two-phase bubbly flows using laser doppler anemometry

OpenAIRE

Marié , Jean-Louis

1983-01-01

International audience; The present work is devoted to the development of an accurate and reliable laser Doppler anemometer technique (L.D.A.) meant for the measurement of the characteristics of twoephase bubbly flows. Most of these characteristics are the various statistical moments of the velocity fluctuations and the Reynolds stress tensor components within the continuous phase but also, under well defined conditions, the mean slip velocity of the dispersed phase. Although this technique w...

Investigation of Doppler spectra of laser radiation scattered inside hand skin during occlusion test

Science.gov (United States)

Kozlov, I. O.; Zherebtsov, E. A.; Zherebtsova, A. I.; Dremin, V. V.; Dunaev, A. V.

2017-11-01

Laser Doppler flowmetry (LDF) is a method widely used in diagnosis of microcirculation diseases. It is well known that information about frequency distribution of Doppler spectrum of the laser radiation scattered by moving red blood cells (RBC) usually disappears after signal processing procedure. Photocurrent’s spectrum distribution contains valuable diagnostic information about velocity distribution of the RBC. In this research it is proposed to compute the indexes of microcirculation in the sub-ranges of the Doppler spectrum as well as investigate the frequency distribution of the computed indexes.

Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking

Directory of Open Access Journals (Sweden)

Armstrong J. W.

2006-01-01

Full Text Available This paper discusses spacecraft Doppler tracking, the current-generation detector technology used in the low-frequency (~millihertz gravitational wave band. In the Doppler method the earth and a distant spacecraft act as free test masses with a ground-based precision Doppler tracking system continuously monitoring the earth-spacecraft relative dimensionless velocity $2 Delta v/c = Delta u/ u_0$, where $Delta u$ is the Doppler shift and $ u_0$ is the radio link carrier frequency. A gravitational wave having strain amplitude $h$ incident on the earth-spacecraft system causes perturbations of order $h$ in the time series of $Delta u/ u_0$. Unlike other detectors, the ~1-10 AU earth-spacecraft separation makes the detector large compared with millihertz-band gravitational wavelengths, and thus times-of-flight of signals and radio waves through the apparatus are important. A burst signal, for example, is time-resolved into a characteristic signature: three discrete events in the Doppler time series. I discuss here the principles of operation of this detector (emphasizing transfer functions of gravitational wave signals and the principal noises to the Doppler time series, some data analysis techniques, experiments to date, and illustrations of sensitivity and current detector performance. I conclude with a discussion of how gravitational wave sensitivity can be improved in the low-frequency band.

Parametric Investigation of Laser Doppler Microphones

Science.gov (United States)

Daoud, M.; Naguib, A.

2002-11-01

The concept of a Laser Doppler Microphone (LDM) is based on utilizing the Doppler frequency shift of a focused laser beam to measure the unsteady velocity of the center point of a flexible polymer diaphragm that is mounted on top of a hole and subjected to the unsteady pressure. Time integration of the velocity signal yields a time series of the diaphragm displacement, which can be converted to pressure from knowledge of the sensor's deflection sensitivity. In our APS/DFD presentation last year, the stringent frequency resolution requirement of these new sensors and methods to meet this requirement were discussed. Here, the dependence of the sensor characteristics (sensitivity, bandwidth, and noise floor) on various significant parameters is investigated in detail by calibrating the sensor in a plane wave tube in the frequency range of 50 - 5000 Hz. Parameters investigated include sensor diaphragm material and thickness, sensor size, damping of the diaphragm motion and laser beam spot size. The results shed light on the operating limits of the new sensor and demonstrate its ability to conduct high-spatial-resolution measurements in typical high-Reynolds-number test facilities. Moreover, calibrated LDM sensors were used to conduct measurements in a separating/reattaching flow and the results are compared to classical electret-type microphones with a similar sensing diameter.

Comparative analysis of pulsed doppler ultrasonography of portal vein vs indirect photography

International Nuclear Information System (INIS)

Chang, Jae Chun; Kwon, Huck Po; Hwang, Mi Soo; Kim, Sun Youn; Park, Bok Hwan; Lee, Hyun Ju; Kim, Hong Jin

1990-01-01

There are some limitation of interpretation in indirect photography via superior mesenteric artery. In order to supplement and predict indirect photography, we compared indirect photographic findings with pulsed doppler flowmetry in 38 hepatobiliary patients, and the results were as follow: 1. In case of normal main portal vein(MPV) filling, Pulsed Doppler always showed antegrade, continuous parabolic wave form and cases of abnormal MPV filling, showed unusual wave form and flow direction. 2. In normal filling case of proximal right portal vein, Pulsed Doppler almost showed normal continuous parabolic wave form but in normal filling cases of proximal left portal vein, occasionally showed undulating wave form. 3. In each side proximal portal vein abnormal filling case, we could observe abnormal doppler wave form and could obtain additional information using doppler wave form. 4. Mean portal flow velocity was significantly increased in higher photography grade(p=0.01) and congestion index was significantly decreased in higher photography grade(p=0.01). 5. We concluded that doppler ultrasonography could supplement incomplete indirect photography

Doppler Ultrasonographic Parameters for Predicting Cerebral Vascular Reserve in Patients with Acute Ischemic Stroke

International Nuclear Information System (INIS)

Jung, Han Young; Lee, Hui Joong; Kim, Hye Jung; Kim, Yong Sun; Kang, Duk Sik

2006-01-01

We investigated Doppler ultrasonographic (US) parameters of patients with acute stroke to predict the cerebral vascular reserve (CVR) measured by SPECT. We reviewed the flow velocity and cross-sectional area of the circular vessel at the common, external, and internal carotid arteries (ICA) and the vertebral arteries (VA) in 109 acute stroke patients who underwent SPECT. Flow volume (FV) of each artery was calculated as the product of the angle-corrected time averaged flow velocity and cross-sectional area of the circular vessel. Total cerebral FV (TCBFV) was determined as the sum of the FVs of the right and left ICA and VA. We compared the Doppler US parameters between 44 cases of preserved and 65 cases of impaired CVR. In the preserved CVR group, ICA FV, anterior circulating FV (ACFV) and TCBFV were higher than in the impaired CVR group (p < 0.05, independent t-test). In the impaired CVR group, the ROC curves showed ACFV and TCBFV were suitable parameters to predict CVR (p < 0.05). Doppler US was helpful for understanding the hemodynamic state of acute stroke. FV measurement by Doppler US was useful for predicting CVR

Contrast-enhanced power Doppler US of hepatocellular carcinomas: Quantitative analysis

International Nuclear Information System (INIS)

Kim, Ah Young; Choi, Byung Ihn; Kim, Tae Kyoung; Lee, Kyoung Ho; Han, Joon Koo

1999-01-01

To determine peak time and duration of contrast enhancement of nodular hepatocellular carcinoma (HCC) on contrast-enhancement power Doppler ultrasound (US) with Levovist by quantitative analysis. Twenty eight patients with nodular HCC were prospectively evaluated with power Doppler US by one examiner. Serial images were obtained before and after injection of 300 mg/mL US contrast agent (SH U 508 A, Levovist, Schering) with the injection rate of 0.2 mL/sec. Power Doppler signals on obtained digital images were quantified using 'Ultrasound Imaging Tool Version 1.0' (Seoul, Korea). The grade, peak time and duration of contrast enhancement of the tumors were analyzed. For nodular HCCs, mean peak enhancement time was 60 seconds after injection of Levovist (mean enhanced area 41.6 ± 28.6 %). These tumoral enhancement decreased from 90 seconds and returned to near baseline state at 5 minutes after injection of Levovist. Maximum enhanced areas (%) were variable at a range of 8-98.5% and mean maximum enhanced area was 46.4 ± 28.6%. On contrast-enhanced power Doppler US with Levovist, nodular HCCs showed peak contrast enhancement (41.6± 28.6) at 60 seconds after injection of contrast agent. This tumoral enhancement nearly disappeared at 5 minutes after injection of contrast agent.

Tissue doppler echocardiography for evaluating left ventricular functions in obese

Directory of Open Access Journals (Sweden)

Mecnun Çetin

2013-03-01

Full Text Available Objective: The aim of this study was to investigate theimpact of childhood obesity on ventricular functions usingtissue Doppler echocardiography.Materials and methods: The mitral tissue Doppler signalswere recorded in the apical four-chamber view, with thesample volume placed at the lateral walls of mitral annulus.The mitral flow was examined with the sample Pulse Dopplerpositioned parallely to flow just at the orifice of the mitralleaflets. Twenty obese (mean age, 161.5±25.8 monthsand 20 healthy children (mean age, 151.2±33.5 monthswere included to this study.Results: Body mass index (BMI was significantly higherin obese group (30.92±6.87. Isovolumic relaxation time(IVRT which is one of the left ventricular (LV diastolicfunction parameters was 66.10±7.30 ms in obese group,and 58.70±9.06 ms in the control group. IVRT was significantlyhigher in the obese group (p=0.007. In obesegroup, the mitral annulus tissue Doppler E velocity wasdecreased, flow velocity was increased and decrement inEm/Am ratio was significant. We found significant negativecorrelation between BMI and LV Em/Am ratio. Myocardialperformance index (MPI in obese group and control groupwas 0.50±0.07 and 0.41±0.04, respectively (p<0.001.Between MPI and LV Em/Am ratio there was a significantnegative correlation while MPI showed positive correlationwith BMI. In obese group septal and LV posterior wall thicknesswas shown to be significantly increased compared tothe control group (p<0.001.Conclusion: Our findings, may be important for determinationof the relationship between obesity and cardiovascularrisk factors in children. Tissue Doppler echocardiographicimaging may be useful in revealing this relationship.Key words: obesity, doppler echocardiography, ventricular dysfunction

Magnetic and Velocity Field Variations in the Active Regions NOAA ...

Indian Academy of Sciences (India)

Abstract. We study the magnetic and velocity field evolution in the two magnetically complex active regions NOAA 10486 and NOAA 10488 observed during October–November 2003. We have used the available data to examine net flux and Doppler velocity time profiles to identify changes associated with evolutionary and ...

Interpreting the CMB aberration and Doppler measurements: boost or intrinsic dipole?

International Nuclear Information System (INIS)

Roldan, Omar; Quartin, Miguel; Notari, Alessio

2016-01-01

The aberration and Doppler coupling effects of the Cosmic Microwave Background (CMB) were recently measured by the Planck satellite. The most straightforward interpretation leads to a direct detection of our peculiar velocity β, consistent with the measurement of the well-known dipole. In this paper we discuss the assumptions behind such interpretation. We show that Doppler-like couplings appear from two effects: our peculiar velocity and a second order large-scale effect due to the dipolar part of the gravitational potential. We find that the two effects are exactly degenerate but only if we assume second-order initial conditions from single-field Inflation. Thus, detecting a discrepancy in the value of β from the dipole and the Doppler couplings implies the presence of a primordial non-Gaussianity. We also show that aberration-like signals likewise arise from two independent effects: our peculiar velocity and lensing due to a first order large-scale dipolar gravitational potential, independently on Gaussianity of the initial conditions. In general such effects are not degenerate and so a discrepancy between the measured β from the dipole and aberration could be accounted for by a dipolar gravitational potential. Only through a fine-tuning of the radial profile of the potential it is possible to have a complete degeneracy with a boost effect. Finally we discuss that we also expect other signatures due to integrated second order terms, which may be further used to disentangle this scenario from a simple boost.

Interpreting the CMB aberration and Doppler measurements: boost or intrinsic dipole?

Energy Technology Data Exchange (ETDEWEB)

Roldan, Omar; Quartin, Miguel [Instituto de Física, Universidade Federal do Rio de Janeiro, 21941-972, Rio de Janeiro, RJ (Brazil); Notari, Alessio, E-mail: oaroldan@if.ufrj.br, E-mail: notari@ffn.ub.es, E-mail: mquartin@if.ufrj.br [Departament de Física Fondamental i Institut de Ciéncies del Cosmos, Universitat de Barcelona, Martí i Franqués 1, E-08028 Barcelona (Spain)

2016-06-01

The aberration and Doppler coupling effects of the Cosmic Microwave Background (CMB) were recently measured by the Planck satellite. The most straightforward interpretation leads to a direct detection of our peculiar velocity β, consistent with the measurement of the well-known dipole. In this paper we discuss the assumptions behind such interpretation. We show that Doppler-like couplings appear from two effects: our peculiar velocity and a second order large-scale effect due to the dipolar part of the gravitational potential. We find that the two effects are exactly degenerate but only if we assume second-order initial conditions from single-field Inflation. Thus, detecting a discrepancy in the value of β from the dipole and the Doppler couplings implies the presence of a primordial non-Gaussianity. We also show that aberration-like signals likewise arise from two independent effects: our peculiar velocity and lensing due to a first order large-scale dipolar gravitational potential, independently on Gaussianity of the initial conditions. In general such effects are not degenerate and so a discrepancy between the measured β from the dipole and aberration could be accounted for by a dipolar gravitational potential. Only through a fine-tuning of the radial profile of the potential it is possible to have a complete degeneracy with a boost effect. Finally we discuss that we also expect other signatures due to integrated second order terms, which may be further used to disentangle this scenario from a simple boost.

Computed estimates of maximum temperature elevations in fetal tissues during transabdominal pulsed Doppler examinations.

Science.gov (United States)

Bly, S H; Vlahovich, S; Mabee, P R; Hussey, R G

1992-01-01

Measured characteristics of ultrasonic fields were obtained in submissions from manufacturers of diagnostic ultrasound equipment for devices operating in pulsed Doppler mode. Simple formulae were used with these data to generate upper limits to fetal temperature elevations, delta Tlim, during a transabdominal pulsed Doppler examination. A total of 236 items were analyzed, each item being a console/transducer/operating-mode/intended-use combination, for which the spatial-peak temporal-average intensity, ISPTA, was greater than 500 mW cm-2. The largest calculated delta Tlim values were approximately 1.5, 7.1 and 8.7 degrees C for first-, second- and third-trimester examinations, respectively. The vast majority of items yielded delta Tlim values which were less than 1 degree C in the first trimester. For second- and third-trimester examinations, where heating of fetal bone determines delta Tlim, most delta Tlim values were less than 4 degrees C. The clinical significance of the results is discussed.

A Wearable Transcranial Doppler Ultrasound Phased Array System.

Science.gov (United States)

Pietrangelo, Sabino J; Lee, Hae-Seung; Sodini, Charles G

2018-01-01

 Practical deficiencies related to conventional transcranial Doppler (TCD) sonography have restricted its use and applicability. This work seeks to mitigate several such constraints through the development of a wearable, electronically steered TCD velocimetry system, which enables noninvasive measurement of cerebral blood flow velocity (CBFV) for monitoring applications with limited operator interaction. A highly-compact, discrete prototype system was designed and experimentally validated through flow phantom and preliminary human subject testing. The prototype system incorporates a custom two-dimensional transducer array and multi-channel transceiver electronics, thereby facilitating acoustic beamformation via phased array operation. Electronic steering of acoustic energy enables algorithmic system controls to map Doppler power throughout the tissue volume of interest and localize regions of maximal flow. Multi-focal reception permits dynamic vessel position tracking and simultaneous flow velocimetry over the time-course of monitoring. Experimental flow phantom testing yielded high correlation with concurrent flowmeter recordings across the expected range of physiological flow velocities. Doppler power mapping has been validated in both flow phantom and preliminary human subject testing, resulting in average vessel location mapping times testing. A wearable prototype CBFV measurement system capable of autonomous vessel search and tracking has been presented. Although flow phantom and preliminary human validation show promise, further human subject testing is necessary to compare velocimetry data against existing commercial TCD systems. Additional human subject testing must also verify acceptable vessel search and tracking performance under a variety of subject populations and motion dynamics-such as head movement and ambulation.

Doppler ultrasonography combined with transient elastography improves the non-invasive assessment of fibrosis in patients with chronic liver diseases.

Science.gov (United States)

Alempijevic, Tamara; Zec, Simon; Nikolic, Vladimir; Veljkovic, Aleksandar; Stojanovic, Zoran; Matovic, Vera; Milosavljevic, Tomica

2017-01-31

Accurate clinical assessment of liver fibrosis is essential and the aim of our study was to compare and combine hemodynamic Doppler ultrasonography, liver stiffness by transient elastography, and non-invasive serum biomarkers with the degree of fibrosis confirmed by liver biopsy, and thereby to determine the value of combining non-invasive method in the prediction significant liver fibrosis. We included 102 patients with chronic liver disease of various etiology. Each patient was evaluated using Doppler ultrasonography measurements of the velocity and flow pattern at portal trunk, hepatic and splenic artery, serum fibrosis biomarkers, and transient elastography. These parameters were then input into a multilayer perceptron artificial neural network with two hidden layers, and used to create models for predicting significant fibrosis. According to METAVIR score, clinically significant fibrosis (≥F2) was detected in 57.8% of patients. A model based only on Doppler parameters (hepatic artery diameter, hepatic artery systolic and diastolic velocity, splenic artery systolic velocity and splenic artery Resistance Index), predicted significant liver fibrosis with a sensitivity and specificity of75.0% and 60.0%. The addition of unrelated non-invasive tests improved the diagnostic accuracy of Doppler examination. The best model for prediction of significant fibrosis was obtained by combining Doppler parameters, non-invasive markers (APRI, ASPRI, and FIB-4) and transient elastography, with a sensitivity and specificity of 88.9% and 100%. Doppler parameters alone predict the presence of ≥F2 fibrosis with fair accuracy. Better prediction rates are achieved by combining Doppler variables with non-invasive markers and liver stiffness by transient elastography.

A New Filtering Algorithm Utilizing Radial Velocity Measurement

Institute of Scientific and Technical Information of China (English)

LIU Yan-feng; DU Zi-cheng; PAN Quan

2005-01-01

Pulse Doppler radar measurements consist of range, azimuth, elevation and radial velocity. Most of the radar tracking algorithms in engineering only utilize position measurement. The extended Kalman filter with radial velocity measureneut is presented, then a new filtering algorithm utilizing radial velocity measurement is proposed to improve tracking results and the theoretical analysis is also given. Simulation results of the new algorithm, converted measurement Kalman filter, extended Kalman filter are compared. The effectiveness of the new algorithm is verified by simulation results.

Doppler time-of-flight imaging

KAUST Repository

Heide, Felix

2015-07-30

Over the last few years, depth cameras have become increasingly popular for a range of applications, including human-computer interaction and gaming, augmented reality, machine vision, and medical imaging. Many of the commercially-available devices use the time-of-flight principle, where active illumination is temporally coded and analyzed on the camera to estimate a per-pixel depth map of the scene. In this paper, we propose a fundamentally new imaging modality for all time-of-flight (ToF) cameras: per-pixel velocity measurement. The proposed technique exploits the Doppler effect of objects in motion, which shifts the temporal frequency of the illumination before it reaches the camera. Using carefully coded illumination and modulation frequencies of the ToF camera, object velocities directly map to measured pixel intensities. We show that a slight modification of our imaging system allows for color, depth, and velocity information to be captured simultaneously. Combining the optical flow computed on the RGB frames with the measured metric axial velocity allows us to further estimate the full 3D metric velocity field of the scene. We believe that the proposed technique has applications in many computer graphics and vision problems, for example motion tracking, segmentation, recognition, and motion deblurring.

Coherent optical transients observed in rubidium atomic line filtered Doppler velocimetry experiments

Energy Technology Data Exchange (ETDEWEB)

Fajardo, Mario E., E-mail: mario.fajardo@eglin.af.mil; Molek, Christopher D.; Vesely, Annamaria L. [Air Force Research Laboratory, Munitions Directorate, Ordnance Division, Energetic Materials Branch, AFRL/RWME, 2306 Perimeter Road, Eglin AFB, Florida 32542-5910 (United States)

2015-10-14

We report the first successful results from our novel Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus, along with unanticipated oscillatory signals due to coherent optical transients generated within pure Rb vapor cells. RALF is a high-velocity and high-acceleration extension of the well-known Doppler Global Velocimetry (DGV) technique for constructing multi-dimensional flow velocity vector maps in aerodynamics experiments [H. Komine, U.S. Patent No. 4,919,536 (24 April 1990)]. RALF exploits the frequency dependence of pressure-broadened Rb atom optical absorptions in a heated Rb/N{sub 2} gas cell to encode the Doppler shift of reflected near-resonant (λ{sub 0} ≈ 780.24 nm) laser light onto the intensity transmitted by the cell. The present RALF apparatus combines fiber optic and free-space components and was built to determine suitable operating conditions and performance parameters for the Rb/N{sub 2} gas cells. It yields single-spot velocities of thin laser-driven-flyer test surfaces and incorporates a simultaneous Photonic Doppler Velocimetry (PDV) channel [Strand et al., Rev. Sci. Instrum. 77, 083108 (2006)] for validation of the RALF results, which we demonstrate here over the v = 0 to 1 km/s range. Both RALF and DGV presume the vapor cells to be simple Beer's Law optical absorbers, so we were quite surprised to observe oscillatory signals in experiments employing low pressure pure Rb vapor cells. We interpret these oscillations as interference between the Doppler shifted reflected light and the Free Induction Decay (FID) coherent optical transient produced within the pure Rb cells at the original laser frequency; this is confirmed by direct comparison of the PDV and FID signals. We attribute the different behaviors of the Rb/N{sub 2} vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N{sub 2} collisions. The minimum necessary N{sub 2} buffer gas density ≈0.3 amagat translates into a

High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

Science.gov (United States)

Sellar, Brian; Harding, Samuel; Richmond, Marshall

2015-08-01

An array of single-beam acoustic Doppler profilers has been developed for the high resolution measurement of three-dimensional tidal flow velocities and subsequently tested in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use divergent acoustic beams emanating from a single instrument. This is achieved using geometrically convergent acoustic beams creating a sample volume at the focal point of 0.03 m3. Away from the focal point, the array is also able to simultaneously reconstruct three-dimensional velocity components in a profile throughout the water column, and is referred to herein as a convergent-beam acoustic Doppler profiler (C-ADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational commercial-scale Alstom 1 MW DeepGen-IV Tidal Turbine deployed at the European Marine Energy Center, Orkney Isles, UK. This proof-of-concept paper outlines the C-ADP system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of C-ADP to standard divergent ADP (D-ADP) velocity measurements reveals a mean difference of 8 mm s-1, standard deviation of 18 mm s-1, and an order of magnitude reduction in realisable length scale. C-ADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the C-ADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved quantification of flow turbulence. Since waves are simultaneously measured via profiled velocities, pressure measurements and surface detection, it is expected that derivatives of this system will be a powerful tool in

Discovery of the double Doppler-shifted emission-line systems in the X-ray spectrum of SS 433

Science.gov (United States)

Kotani, Taro; Kawai, Nobuyuki; Aoki, Takashi; Doty, John; Matsuoka, Masaru; Mitsuda, Kazuhisa; Nagase, Fumiaki; Ricker, George; White, Nick E.

1994-01-01

We have used the CCD X-ray spectrometers on ASCA and resolved the X-ray emission line from the jet of SS 433 both into Doppler-shifted components with two distinct velocities, and into emission from different ionization states of iron, i.e., Fe XXV and Fe XXVI. This is the first direct detection of the two Doppler shifted beams in the X-ray spectra of SS 433 and allows the radial velocity of the jet along the line of sight to be determined with an accuracy comparable to the optical spectroscopy. We also found pairs of emission lines from other atomic species, such as ionized silicon and sulfur, with the Doppler shifts consistent with each other. This confirms the origin of the X-ray emission in the high temperature plasma in the jets.

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; Östgren, Carl J.; Strömberg, Tomas

2010-01-01

OBJECTIVE To compare the microcirculatory velocity distribution in type 2 diabetic patients and nondiabetic control subjects at baseline and after local heating. RESEARCH DESIGN AND METHODS The skin blood flow response to local heating (44°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 × concentration), in a physiologically relevant unit (grams RBC per 100 g tissue × millimeters per second) in a fixed output volume, separated into three velocity regions: v 10 mm/s. RESULTS 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 <1 mm/s. The mean 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. CONCLUSIONS 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. PMID:20393143

Structure of a swirl-stabilized spray flame by imaging, laser Doppler velocimetry, and phase Doppler anemometry

Science.gov (United States)

Edwards, C. F.; Rudoff, R. C.

1991-01-01

Data are presented which describe the mean structure of a steady, swirl-stabilized, kerosene spray flame in the near-injector region of a research furnace. The data presented include ensemble-averaged results of schlieren, luminosity, and extinction imaging, measurement of the gas phase velocity field by laser Doppler velocimetry, and characterization of the condensed phase velocity by phase Doppler anemometry. The results of these studies define six key regions in the flame: the dense spray region; the rich, two-phase, fuel jet; the main air jet; the internal product recirculation zone; the external product recirculation zone; and the gaseous diffusion flame zone. The first five of these regions form a conical mixing layer which prepares the air and fuel for combustion. The air and fuel jets comprise the central portion of this mixing layer and are bounded on either side by the hot product gases of the internal and external recirculation zones. Entrainment of these product gases into the air/fuel streams provides the energy required to evaporate the fuel spray and initiate combustion. Intermittency of the internal recirculation and spray jet flows accounts for unexpected behavior observed in the aerodynamics of the two phases. The data reported herein are part of the database being accumulated on this spray flame for the purpose of detailed comparison with numerical modeling.

A new method for measurement of granular velocities

International Nuclear Information System (INIS)

Nyborg Andersen, B.

1984-01-01

A new, supplementary method to measure granular velocities is presented. The method utilizes the Doppler shift caused by the line of sight component of the solar rotation to cause a wavelength shift through spectral lines as function of heliocentric angle. By measuring the center-to-limb variation of the granular intensity fluctations at different wavelength positions in the lines, the velocities are found. To do this, assumptions regarding the geometrical structure of the velocity and intensity fields have to be made. Preliminary application of the method results in a steep velocity gradient suggesting zero velocity at a hight of 200 km above tau 500 = 1. Possible causes are discussed

Experimental and biological variation of three-dimensional transcranial Doppler measurements

DEFF Research Database (Denmark)

Thomsen, L L; Iversen, Helle Klingenberg

1993-01-01

A new transcranial Doppler system (3-D Transscan, Eden Medizinische Elektronik) was evaluated in relation to sex, age, intersubject, interobserver, side-to-side, and day-to-day variation. Fifty-eight healthy volunteers participated (aged 18-80 yr). Mean velocity was higher in females than in male...

Development of a Duplex Ultrasound Simulator and Preliminary Validation of Velocity Measurements in Carotid Artery Models.

Science.gov (United States)

Zierler, R Eugene; Leotta, Daniel F; Sansom, Kurt; Aliseda, Alberto; Anderson, Mark D; Sheehan, Florence H

2016-07-01

Duplex ultrasound scanning with B-mode imaging and both color Doppler and Doppler spectral waveforms is relied upon for diagnosis of vascular pathology and selection of patients for further evaluation and treatment. In most duplex ultrasound applications, classification of disease severity is based primarily on alterations in blood flow velocities, particularly the peak systolic velocity (PSV) obtained from Doppler spectral waveforms. We developed a duplex ultrasound simulator for training and assessment of scanning skills. Duplex ultrasound cases were prepared from 2-dimensional (2D) images of normal and stenotic carotid arteries by reconstructing the common carotid, internal carotid, and external carotid arteries in 3 dimensions and computationally simulating blood flow velocity fields within the lumen. The simulator displays a 2D B-mode image corresponding to transducer position on a mannequin, overlaid by color coding of velocity data. A spectral waveform is generated according to examiner-defined settings (depth and size of the Doppler sample volume, beam steering, Doppler beam angle, and pulse repetition frequency or scale). The accuracy of the simulator was assessed by comparing the PSV measured from the spectral waveforms with the true PSV which was derived from the computational flow model based on the size and location of the sample volume within the artery. Three expert examiners made a total of 36 carotid artery PSV measurements based on the simulated cases. The PSV measured by the examiners deviated from true PSV by 8% ± 5% (N = 36). The deviation in PSV did not differ significantly between artery segments, normal and stenotic arteries, or examiners. To our knowledge, this is the first simulation of duplex ultrasound that can create and display real-time color Doppler images and Doppler spectral waveforms. The results demonstrate that an examiner can measure PSV from the spectral waveforms using the settings on the simulator with a mean absolute error

Control of group velocity by phase-changing collisions

International Nuclear Information System (INIS)

Goren, C.; Rosenbluh, M.; Wilson-Gordon, A.D.; Friedmann, H.

2005-01-01

We discuss the influence of phase-changing collisions on the group velocities in Doppler-broadened, cycling, degenerate two-level systems where F e =F g +1 and F g >0, interacting with pump and probe lasers, that exhibit electromagnetically induced absorption (EIA). Two model systems are considered: the N system where the pump and probe are polarized perpendicularly, and EIA is due to transfer of coherence (TOC), and the double two-level system (TLS) where both lasers have the same polarization, and EIA is due to transfer of population (TOP). For the case of Doppler-broadened EIA TOC, which occurs at low pump intensity, there is a switch from positive to negative dispersion and group velocity, as the rate of phase-changing collisions is increased. For the case of EIA TOP at low pump intensity, the dispersion and group velocity remain negative even when the collision rate is increased. Pressure-induced narrowing, accompanied by an increase in the magnitude of the negative dispersion and a decrease in the magnitude of the negative group velocity, occurs in both EIA TOC and EIA TOP, at low pump intensity. When the pump intensity is increased, a switch from negative to positive dispersion and group velocity, with increasing collision rate, also occurs in the double TLS system. However, the effect is far smaller than in the case of the N system at low pump intensity

Cerebral Hemodynamics in the Elderly: A Transcranial Doppler Study in the Einstein Aging Study Cohort.

Science.gov (United States)

Yang, Dixon; Cabral, Digna; Gaspard, Emmanuel N; Lipton, Richard B; Rundek, Tatjana; Derby, Carol A

2016-09-01

We sought to describe the relationship between age, sex, and race/ethnicity with transcranial Doppler hemodynamic characteristics from major intracerebral arterial segments in a large elderly population with varying demographics. We analyzed 369 stroke-free participants aged 70 years and older from the Einstein Aging Study. Single-gate, nonimaging transcranial Doppler sonography, a noninvasive sonographic technique that assesses real-time cerebrovascular hemodynamics, was used to interrogate 9 cerebral arterial segments. Individual Doppler spectra and cerebral blood flow velocities were acquired, and the pulsatility index and resistive index were calculated by the device's automated waveform-tracking function. Multiple linear regression models were used to examine the independent associations of age, sex, and race/ethnicity with transcranial Doppler measures, adjusting for hypertension, history of myocardial infarction or revascularization, and history of diabetes. Among enrolled participants, 303 individuals had at least 1 vessel insonated (mean age [SD], 80 [6] years; 63% women; 58% white; and 32% black). With age, transcranial Doppler measures of mean blood flow velocity were significantly decreased in the basilar artery (P = .001) and posterior cerebral artery (right, P = .003; left, P = .02). Pulsatility indices increased in the left middle cerebral artery (P = .01) and left anterior cerebral artery (P = .03), and the resistive index was increased in the left middle cerebral artery (P = .007) with age. Women had higher pulsatility and resistive indices compared to men in several vessels. We report a decreased mean blood flow velocity and weakly increased arterial pulsatility and resistance with aging in a large elderly stroke-free population. These referential trends in cerebrovascular hemodynamics may carry important implications in vascular diseases associated with advanced age, increased risk of cerebrovascular disease, cognitive decline, and dementia.

Numerical study of glare spot phase Doppler anemometry

Science.gov (United States)

Hespel, C.; Ren, K. F.; Gréhan, G.; Onofri, F.

2008-03-01

The phase Doppler anemometry has (PDA) been developed to measure simultaneously the velocity and the size of droplets. When the concentration of particles is high, tightly focused beams must be used, as in the dual burst PDA. The latter permits an access to the refractive index of the particle, but the effect of wave front curvature of the incident beams becomes evident. In this paper, we introduce a glare spot phase Doppler anemometry which uses two large beams. The images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes through the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences and the intensity ratios between two signals, the distance between the reflected and refracted spots can be obtained. These measured values provide information about the particle diameter and its refractive index, as well as its two velocity components. This paper is devoted to the numerical study of such a configuration with two theoretical models: geometrical optics and rigorous electromagnetism solution.

B-mode and Doppler ultrasonography of adrenal glands of healthy dogs

Directory of Open Access Journals (Sweden)

S. Fernandez

2016-08-01

Full Text Available ABSTRACT The aim of this study was to determine the vascular indices of adrenal blood flow in healthy dogs (systolic velocity - SV; diastolic velocity - DV; resistance index - RI. Eighteen dogs (thirty six adrenal were studied. Physical examination, biochemical profile and dexamethasone suppression test were performed to determine general health status. Echotexture, size, contours and margins, and overall shape of the adrenal gland (right and left were assessed via ultrasound. By spectral Doppler of the phrenic-abdominal artery, the SV, DV, and RI were acquired. Animals did not show alterations in clinical and laboratory examination and suppression of cortisol. Normal homogeneous and echotexture, regular contours and margins and normal shape and size were verified via B mode. Spectral Doppler of the phrenic-abdominal artery showed monophasic-patterned waves and low vascular resistance and systolic peak evident with means values: left adrenal - SV = 31.34cm/s, DV = 9.54cm/s and RI = 0.69; and right adrenal - SV = 27.83cm/s, DV = 7.71cm/s and RI = 0.68. Doppler evaluation of adrenal was easily implemented and may provide base line data in the study, allowing for the use of this technique as a diagnostic tool for diseases of the dog's adrenal.

Color Doppler Echocardiographic Assessment of Valvular Regurgitation in Normal Infants

Directory of Open Access Journals (Sweden)

Shu-Ting Lee

2010-01-01

Conclusion: The prevalence of inaudible valvular regurgitation is high in infants with structurally normal hearts. Multiple-valve involvement with regurgitation is not uncommon. Mild severity and low velocity on color Doppler, and the structural information provided by 2D imaging strongly suggest that these regurgitant flows are physiologically normal in infancy.

Modified Feynman ratchet with velocity-dependent fluctuations

Directory of Open Access Journals (Sweden)

Jack Denur

2004-03-01

Full Text Available Abstract: The randomness of Brownian motion at thermodynamic equilibrium can be spontaneously broken by velocity-dependence of fluctuations, i.e., by dependence of values or probability distributions of fluctuating properties on Brownian-motional velocity. Such randomness-breaking can spontaneously obtain via interaction between Brownian-motional Doppler effects --- which manifest the required velocity-dependence --- and system geometrical asymmetry. A non random walk is thereby spontaneously superposed on Brownian motion, resulting in a systematic net drift velocity despite thermodynamic equilibrium. The time evolution of this systematic net drift velocity --- and of velocity probability density, force, and power output --- is derived for a velocity-dependent modification of Feynman's ratchet. We show that said spontaneous randomness-breaking, and consequent systematic net drift velocity, imply: bias from the Maxwellian of the system's velocity probability density, the force that tends to accelerate it, and its power output. Maximization, especially of power output, is discussed. Uncompensated decreases in total entropy, challenging the second law of thermodynamics, are thereby implied.

Coherent laser radar with dual-frequency Doppler estimation and interferometric range detection

NARCIS (Netherlands)

Onori, D.; Scotti, F.; Laghezza, F.; Scaffardi, M.; Bogoni, A.

2016-01-01

The concept of a coherent interferometric dual frequency laser radar, that measures both the target range and velocity, is presented and experimentally demonstrated. The innovative architecture combines the dual frequency lidar concept, allowing a precise and robust Doppler estimation, with the

Transcranial Doppler sonography in familial hemiplegic migraine

International Nuclear Information System (INIS)

Pierelli, F.; Pauri, F.; Cupini, L.M.; Fiermonte, G.; Rizzo, P.A.

1991-01-01

A patient affected by familial hemiplegic migraine underwent transcranial Doppler sonography twice: the first during a spontaneous attack with right hemiparesis and aphasia, the second during a headachefree period. During the attack the following haemodynamic changes were seen: (a) bilateral increase in the middle cerebral artery and anterior cerebral artery blood flow velocities (this increase was more pronounced on the left side), (b) decreased systo-diastolic ratio and pulsatility index on the right side, (c) increased systo-diastolic ratio and pulsatility index on the left side. The results indicate that during the attack in this familial hemiplegic migraine patient, a diffuse vasoconstriction of the basal cerebral arteries developed. Moreover, transcranial Doppler sonography data suggest that a prolonged vasoconstriction of the peripheral arterioles could play a role in determining the neurological symptoms in this syndrome. 13 refs., 1 figs., 1 tab

Transcranial Doppler sonography in familial hemiplegic migraine

Energy Technology Data Exchange (ETDEWEB)

Pierelli, F.; Pauri, F.; Cupini, L.M.; Fiermonte, G.; Rizzo, P.A. (Universita la Sapienza, Roma (Italy))

1991-02-01

A patient affected by familial hemiplegic migraine underwent transcranial Doppler sonography twice: the first during a spontaneous attack with right hemiparesis and aphasia, the second during a headachefree period. During the attack the following haemodynamic changes were seen: (a) bilateral increase in the middle cerebral artery and anterior cerebral artery blood flow velocities (this increase was more pronounced on the left side), (b) decreased systo-diastolic ratio and pulsatility index on the right side, (c) increased systo-diastolic ratio and pulsatility index on the left side. The results indicate that during the attack in this familial hemiplegic migraine patient, a diffuse vasoconstriction of the basal cerebral arteries developed. Moreover, transcranial Doppler sonography data suggest that a prolonged vasoconstriction of the peripheral arterioles could play a role in determining the neurological symptoms in this syndrome. 13 refs., 1 figs., 1 tab.

Velocimetria Doppler no período neonatal em recém-nascidos a termo pequenos para idade gestacional Neonatal Doppler velocimetry in full term small-for-gestational age newborns

Directory of Open Access Journals (Sweden)

Iracema Augusta Carvalho Cortez Muniz

2003-09-01

Full Text Available Este estudo teve como objetivo avaliar o fluxo sanguíneo cerebral em recém-nascidos a termo pequenos para idade gestacional, utilizando ultra-sonografia Doppler craniana ao nascimento. O estudo foi desenvolvido no CAISM/UNICAMP (Centro de Saúde Terciário para Mulheres. Foram selecionados sessenta recém-nascidos e divididos em 2 grupos: 36 adequados para idade gestacional (AIG e 24 pequenos para idade gestacional (PIG. Foi realizada a avaliação de ultra-sonografia Doppler craniana nos grupos, entre 24-48 horas após o nascimento. A velocidade de fluxo sanguíneo cerebral foi menor no grupo PIG na artéria cerebral anterior (ACA. As medidas Doppler foram estatisticamente diferentes entre os grupos apenas para valores relacionados à velocidade de fluxo de pico sistólico (VFPS e velocidade de fluxo médio (VFM na ACA. Não houve diferenças significantes para nenhum dos parâmetros avaliados de velocidade de fluxo na artéria cerebral média (ACM. Concluiu-se que recém-nascidos PIG apresentaram VFPS e VFM significativamente menores apenas na ACA. A adequação peso/idade gestacional, presença de policitemia neonatal e valores de pressão arterial média estiveram estatisticamente associados a VFM na ACA. A presença de sofrimento fetal, valores de pressão arterial média e hábito de fumar durante a gestação estiveram estatisticamente associados a VFM na ACM.This study aimed to evaluate the cerebral blood flow of full term small-for-gestational age newborns, using cranial ultrasound Doppler at birth. This study was performed at CAISM/UNICAMP (Tertiary Health Center for Women. Sixty term newborns were selected and divided in two groups: appropriate-for-gestational age (AGA (36 neonates and small-for-gestational age (SGA (24 neonates. Cranial ultrasound Doppler evaluation was performed on both groups, between 24 and 48 hours after birth. Cerebral blood flow velocity (CBFV was lower in the small-for-gestational age group, in the anterior

Quantitation of stress echocardiography by tissue Doppler and strain rate imaging: a dream come true?

Science.gov (United States)

Galderisi, Maurizio; Mele, Donato; Marino, Paolo Nicola

2005-01-01

Tissue Doppler (TD) is an ultrasound tool providing a quantitative agreement of left ventricular regional myocardial function in different modalities. Spectral pulsed wave (PW) TD, performed online during the examination, measures instantaneous myocardial velocities. By means of color TD, velocity images are digitally stored for subsequent off-line analysis and mean myocardial velocities are measured. An implementation of color TD includes strain rate imaging (SRI), based on post-processing conversion of regional velocities in local myocardial deformation rate (strain rate) and percent deformation (strain). These three modalities have been applied to stress echocardiography for quantitative evaluation of regional left ventricular function and detection of ischemia and viability. They present advantages and limitations. PWTD does not permit the simultaneous assessment of multiple walls and therefore is not compatible with clinical stress echocardiography while it could be used in a laboratory setting. Color TD provides a spatial map of velocity throughout the myocardium but its results are strongly affected by the frame rate. Both color TD and PWTD are also influenced by overall cardiac motion and tethering from adjacent segments and require reference velocity values for interpretation of regional left ventricular function. High frame rate (i.e. > 150 ms) post-processing-derived SRI can potentially overcome these limitations, since measurements of myocardial deformation have not any significant apex-to-base gradient. Preliminary studies have shown encouraging results about the ability of SRI to detect ischemia and viability, in terms of both strain rate changes and/or evidence of post-systolic thickening. SRI is, however, Doppler-dependent and time-consuming. Further technical refinements are needed to improve its application and introduce new ultrasound modalities to overcome the limitations of the Doppler-derived deformation analysis.

3D atom microscopy in the presence of Doppler shift

Science.gov (United States)

Rahmatullah; Chuang, You-Lin; Lee, Ray-Kuang; Qamar, Sajid

2018-03-01

The interaction of hot atoms with laser fields produces a Doppler shift, which can severely affect the precise spatial measurement of an atom. We suggest an experimentally realizable scheme to address this issue in the three-dimensional position measurement of a single atom in vapors of rubidium atoms. A three-level Λ-type atom-field configuration is considered where a moving atom interacts with three orthogonal standing-wave laser fields and spatial information of the atom in 3D space is obtained via an upper-level population using a weak probe laser field. The atom moves with velocity v along the probe laser field, and due to the Doppler broadening the precision of the spatial information deteriorates significantly. It is found that via a microwave field, precision in the position measurement of a single hot rubidium atom can be attained, overcoming the limitation posed by the Doppler shift.

Air-mass flux measurement system using Doppler-shifted filtered Rayleigh scattering

Science.gov (United States)

Shirley, John A.; Winter, Michael

1993-01-01

An optical system has been investigated to measure mass flux distributions in the inlet of a high speed air-breathing propulsion system. Rayleigh scattered light from air is proportional to the number density of molecules and hence can be used to ascertain the gas density in a calibrated system. Velocity field measurements are achieved by spectrally filtering the elastically-scattered Doppler-shifted light with an absorbing molecular filter. A novel anamorphic optical collection system is used which allows optical rays from different scattering angles, that have different Doppler shifts, to be recorded separately. This is shown to obviate the need to tune the laser through the absorption to determine velocities, while retaining the ability to make spatially-resolved measurements along a line. By properly selecting the laser tuning and filter parameters, simultaneous density measurements can be made. These properties are discussed in the paper and experiments demonstrating the velocimetry capability are described.

In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography

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Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

1999-04-01

Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

Calibrating Doppler imaging of preterm intracerebral circulation using a microvessel flow phantom

Directory of Open Access Journals (Sweden)

Fleur A. Camfferman

2015-01-01

Full Text Available Introduction. Preterm infants are born during critical stages of brain development, in which the adaptive capacity of the fetus to extra-uterine environment is limited. Inadequate brain perfusion has been directly linked to preterm brain damage. Advanced high-frequency ultrasound probes and processing algorithms allow visualization of microvessels and depiction of regional variation. To assess whether visualization and flow velocity estimates of preterm cerebral perfusion using Doppler techniques is accurate, we conducted an in vitro experiment using a microvessel flow phantom.Materials and Methods. An in-house developed flow phantom containing two microvessels (inner diameter 200 and 700 microns with attached syringe pumps, filled with blood-mimicking fluid, was used to generate non-pulsatile perfusion of variable flow. Measurements were performed using an Esaote MyLab70 scanner.Results. Microvessel mimicking catheters with velocities as low as 1cm/sec were adequately visualized with a linear ultrasound probe. With a convex probe velocities <2 cm/sec could not be depicted. Within settings, velocity and diameter measurements were highly reproducible (intra class correlation 0.997 (95% CI 0.996-0.998 and 0.914 (0.864-0.946. Overall, mean velocity was overestimated up to 3-fold, especially in high velocity ranges. Significant differences were seen in velocity measurements when using steer angle correction and in vessel diameter estimation (p<0.05.Conclusion. Visualization of microvessel size catheters mimicking small brain vessels is feasible. Reproducible velocity and diameter results can be obtained, although important overestimation of the values is observed. Before velocity estimates of microcirculation can find its use in clinical practice, calibration of the ultrasound machine for any specific Doppler purpose is essential. The ultimate goal is to develop a sonographic tool that can be used for objective study of regional perfusion in routine

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.

Drift velocities of 150-km Field-Aligned Irregularities observed by the Equatorial Atmosphere Radar

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Yuichi Otsuka

2013-11-01

Full Text Available Between 130 and 170 km altitude in the daytime ionosphere, the so-called 150-km field-aligned irregularities (FAIs have been observed since the 1960s at equatorial regions with several very high frequency (VHF radars. We report statistical results of 150-km FAI drift velocities on a plane perpendicular to the geomagnetic field, acquired by analyzing the Doppler velocities of 150-km FAIs observed with the Equatorial Atmosphere Radar (EAR at Kototabang, Indonesia during the period from Aug. 2007 to Oct. 2009. We found that the southward/upward perpendicular drift velocity of the 150-km FAIs tends to decrease in the afternoon and that this feature is consistent with that of F-region plasma drift velocities over the magnetic equator. The zonal component of the 150-km FAI drift velocity is westward and decreases with time, whereas the F-region plasma drift velocity observed with the incoherent scatter radar at Jicamarca, Peru, which is westward, reaches a maximum at about noon. The southward/upward and zonal drift velocities of the 150-km FAIs are smaller than that of the F-region plasma drift velocity by approximately 3 m/s and 25 m/s, respectively, on average. The large difference between the 150-km FAI and F-region plasma drift velocities may not arise from a difference in the magnetic latitudes at which their electric fields are generated. Electric fields generated at the altitude at which the 150-km FAIs occur may not be negligible.

The changes in Doppler indices of fetal ductus venosus and umbilical artery after amnioinfusion for women with preterm premature rupture of membranes before 26 weeks' gestation.

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Hsu, Te-Yao; Hsu, Jenn-Jeih; Fu, Hung-Chun; Ou, Chia-Yu; Tsai, Chih-Chang; Cheng, Bi-Hua; Fang, Fu-Min; Kao, Hui-Fen; Yang, Chun-Yuh; Tsai, Wen Lin; Sung, Chuen Chu; Tsai, Men-Yi

2009-09-01

To investigate the changes in Doppler indices of the fetal ductus venosus (DV) and umbilical artery (UMA) after amnioinfusion in pregnant women with preterm premature rupture of membranes (pPROM). Pregnancies with pPROM and severe oligohydramnios cause sequelae in newborns and mothers. This cross-sectional study included a group of 25 patients with pPROM before 26 weeks' gestation. Color Doppler imaging was used to measure the impedance index and quantitative blood flow in the DV and systolic/diastolic ratio (S/D) of the UMA before and 30 minutes after the end of amnioinfusion. The following velocity parameters were measured: (1) DV peak systolic velocity; (2) DV time-averaged velocity; (3) DV maximum forward velocity during atrial contraction; (4) DV S/D; (5) DV pulsatility index (PI); (6) DV Pourcelots resistance index (RI); (7) fetal heart rate; and (8) UMA S/D. Twenty-one of the 25 patients underwent a total of 27 amnioinfusions. The mean PI and RI of the DV, and S/D of the DV and UMA decreased significantly after amnioinfusion (PI, 0.75 +/- 0.24 vs. 0.60 +/- 0.18, p = 0.009; RI, 0.60 +/- 0.15 vs. 0.50 +/- 0.13; DV S/D, 3.07 +/- 1.81 vs. 2.13 +/- 0.66, p = 0.008; UMA S/D, 3.58 +/- 0.87 vs. 2.88 +/- 0.62, p = 0.001). Amnioinfusion increases the space for the fetuses and reduces the impedance of the fetoplacental circulation. Improvements in DV and UMA flow may benefit fetuses suffering severe oligohydramnios in mid-pregnancy.

Doppler ultrasound scan during normal gestation: umbilical circulation

International Nuclear Information System (INIS)

Ruiz, T.; Sabate, J.; Martinez-Benavides, M. M.; Sanchez-Ramos, J.

2002-01-01

To determine normal umbilical circulation patterns by means of Doppler ultrasound scan in a healthy gestating population without risk factors and with normal perinatal results, and to evaluate any occurring modifications relative to gestational age by obtaining records kept during pregnancy. One hundred and sixteen pregnant women carrying a single fetus have been studied. These women had no risk factors, with both clinical and analytical controls, as well as ultrasound scans, all being normal. There were performed a total of 193 Doppler ultrasound scans between weeks 15 and 41 of gestation, with blood-flow analysis in the arteries and vein of the umbilical cord. The obtained information was correlated with parameters that evaluate fetal well-being (fetal monitoring and/or oxytocin test) and perinatal result (delivery type, birth weight, Apgar score). Statistical analysis was performed with the programs SPSS 6.0.1 for Windows and EPIINFO 6.0.4. With pulsed Doppler, the umbilical artery in all cases demonstrated a biphasic morphology with systolic and diastolic components and without retrograde blood flow. As the gestation period increased, there was observed a progressive decrease in resistance along with an increase in blood-flow velocity during the diastolic phase. The Doppler ultrasound scan is a non-invasive method that permits the hemodynamic study of umbilical blood circulation. A knowledge of normal blood-flow signal morphology, as well as of the normal values for Doppler indices in relation to gestational age would permit us to utilize this method in high-risk pregnancies. (Author) 30 refs

Influence of the Metal Volume Fraction on the maximum deflection and impact load of GLARE plates subjected to low velocity impact

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Bikakis, GSE; Savaidis, A.; Zalimidis, P.; Tsitos, S.

2016-11-01

Fiber-metal laminates are hybrid composite materials, consisting of alternating metal layers bonded to fiber-reinforced prepreg layers. GLARE (GLAss REinforced) belongs to this new family of materials. GLARE is the most successful fiber-metal laminate up to now and is currently being used for the construction of primary aerospace structures, such as the fuselage of the Airbus A380 air plane. Impact properties are very important in aerospace structures, since impact damage is caused by various sources, such as maintenance damage from dropped tools, collision between service cars or cargo and the structure, bird strikes and hail. The principal objective of this article is to evaluate the influence of the Metal Volume Fraction (MVF) on the low velocity impact response of GLARE fiber-metal laminates. Previously published differential equations of motion are employed for this purpose. The low velocity impact behavior of various circular GLARE plates is predicted and characteristic values of impact variables, which represent the impact phenomenon, are evaluated versus the corresponding MVF of the examined GLARE material grades. The considered GLARE plates are subjected to low velocity impact under identical impact conditions. A strong effect of the MVF on the maximum impact load and a significant effect on the maximum plate deflection of GLARE plates has been found.

Characterizing Turbulent Events at a Tidal Energy Site from Acoustic Doppler Velocity Observations

Science.gov (United States)

McCaffrey, Katherine; Fox-Kemper, Baylor; Hamlington, Peter

2013-11-01

As interest in marine renewable energy increases, observations are crucial to understanding the environments encountered by energy conversion devices. Data obtained from an acoustic Doppler current profiler and an acoustic Doppler velocimeter at two locations in the Puget Sound, WA are used to perform a detailed analysis of the turbulent environment that is expected to be present at a turbine placed in a tidal strait. Metrics such as turbulence intensity, structure functions, probability density functions, intermittency, coherent turbulence kinetic energy, anisotropy invariants, and linear combinations of eigenvalues are used to characterize the turbulence. The results indicate that coherent turbulence kinetic energy and turbulence intensity can be used to identify and parameterize different turbulent events in the flow. An analysis of the anisotropy characteristics leads to a physical description of turbulent events (defined using both turbulence intensity and coherent turbulent kinetic energy) as being dominated by one component of the Reynolds stresses. During non-turbulent events, the flow is dominated by two Reynolds stress components. The importance of these results for the development of realistic models of energy conversion devices is outlined. Cooperative Institute for Research in Environmental Sciences, Department of Atmospheric and Oceanic Sciences.

Demonstration of coherent Doppler lidar for navigation in GPS-denied environments

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Amzajerdian, Farzin; Hines, Glenn D.; Pierrottet, Diego F.; Barnes, Bruce W.; Petway, Larry B.; Carson, John M.

2017-05-01

A coherent Doppler lidar has been developed to address NASA's need for a high-performance, compact, and cost-effective velocity and altitude sensor onboard its landing vehicles. Future robotic and manned missions to solar system bodies require precise ground-relative velocity vector and altitude data to execute complex descent maneuvers and safe, soft landing at a pre-designated site. This lidar sensor, referred to as a Navigation Doppler Lidar (NDL), meets the required performance of the landing missions while complying with vehicle size, mass, and power constraints. Operating from up to four kilometers altitude, the NDL obtains velocity and range precision measurements reaching 2 cm/sec and 2 meters, respectively, dominated by the vehicle motion. Terrestrial aerial vehicles will also benefit from NDL data products as enhancement or replacement to GPS systems when GPS is unavailable or redundancy is needed. The NDL offers a viable option to aircraft navigation in areas where the GPS signal can be blocked or jammed by intentional or unintentional interference. The NDL transmits three laser beams at different pointing angles toward the ground to measure range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. The three line-of-sight measurements are then combined in order to determine the three components of the vehicle velocity vector and its altitude relative to the ground. This paper describes the performance and capabilities that the NDL demonstrated through extensive ground tests, helicopter flight tests, and onboard an autonomous rocket-powered test vehicle while operating in closedloop with a guidance, navigation, and control (GN and C) system.

Doppler-ultrasonographic finding of air in the portal vein: a case report

Energy Technology Data Exchange (ETDEWEB)

Park, Ki Soon; Lee, Kwan Sup; Lee, Yul; Chung, Soo Young; Bae, Sang Hoon [College of Medicine, Hallym University, Seoul (Korea, Republic of)

1994-03-15

Classically air in the portal vein has been detected on plain radiography, but computed tomography and ultrasonography have been shown to be more sensitive. We report a case of air in the PV in a 10-day-old infant with pneumatosis intestinalis with its ultrasonographic and Doppler findings. The patient was a 10-day-old infant born by cesarean section at 41 weeks. Simple abdomen film revealed branching pattern of radiolucent air shadows within in contour of liver, gas distention of bowel loops and thickenod bowel walls with lincar intraluminal air shadows in abdomen, suggesting necrotizing enterocolitis. So we performed Doppler ultrasonography. Ultrasonography showed branching pattern of hyperechogenic dots and along the lumen of left portal vein. The color Doppler study revealed an aliasing duo to increased velocity and whirling pattern of blood flow, and the Duplex Doppler spectral display showed sharp, vertical bidirectional spikes by air in portal vein. Air in the portal vein can be easily diagnosed by the following signs: hyperechogenic dots in the portal vein on ultrasonography and vertical, sharp bidirectional spikes superimposed on the usual Doppler tracing of the portal vein on Duplex ultrasonography.

Doppler-ultrasonographic finding of air in the portal vein: a case report

International Nuclear Information System (INIS)

Park, Ki Soon; Lee, Kwan Sup; Lee, Yul; Chung, Soo Young; Bae, Sang Hoon

1994-01-01

Classically air in the portal vein has been detected on plain radiography, but computed tomography and ultrasonography have been shown to be more sensitive. We report a case of air in the PV in a 10-day-old infant with pneumatosis intestinalis with its ultrasonographic and Doppler findings. The patient was a 10-day-old infant born by cesarean section at 41 weeks. Simple abdomen film revealed branching pattern of radiolucent air shadows within in contour of liver, gas distention of bowel loops and thickenod bowel walls with lincar intraluminal air shadows in abdomen, suggesting necrotizing enterocolitis. So we performed Doppler ultrasonography. Ultrasonography showed branching pattern of hyperechogenic dots and along the lumen of left portal vein. The color Doppler study revealed an aliasing duo to increased velocity and whirling pattern of blood flow, and the Duplex Doppler spectral display showed sharp, vertical bidirectional spikes by air in portal vein. Air in the portal vein can be easily diagnosed by the following signs: hyperechogenic dots in the portal vein on ultrasonography and vertical, sharp bidirectional spikes superimposed on the usual Doppler tracing of the portal vein on Duplex ultrasonography

Study on Zero-Doppler Centroid Control for GEO SAR Ground Observation

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Yicheng Jiang

2014-01-01

Full Text Available In geosynchronous Earth orbit SAR (GEO SAR, Doppler centroid compensation is a key step for imaging process, which could be performed by the attitude steering of a satellite platform. However, this zero-Doppler centroid control method does not work well when the look angle of radar is out of an expected range. This paper primarily analyzes the Doppler properties of GEO SAR in the Earth rectangular coordinate. Then, according to the actual conditions of the GEO SAR ground observation, the effective range is presented by the minimum and maximum possible look angles which are directly related to the orbital parameters. Based on the vector analysis, a new approach for zero-Doppler centroid control in GEO SAR, performing the attitude steering by a combination of pitch and roll rotation, is put forward. This approach, considering the Earth’s rotation and elliptical orbit effects, can accurately reduce the residual Doppler centroid. All the simulation results verify the correctness of the range of look angle and the proposed steering method.

A novel decision tree approach based on transcranial Doppler sonography to screen for blunt cervical vascular injuries.

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Purvis, Dianna; Aldaghlas, Tayseer; Trickey, Amber W; Rizzo, Anne; Sikdar, Siddhartha

2013-06-01

Early detection and treatment of blunt cervical vascular injuries prevent adverse neurologic sequelae. Current screening criteria can miss up to 22% of these injuries. The study objective was to investigate bedside transcranial Doppler sonography for detecting blunt cervical vascular injuries in trauma patients using a novel decision tree approach. This prospective pilot study was conducted at a level I trauma center. Patients undergoing computed tomographic angiography for suspected blunt cervical vascular injuries were studied with transcranial Doppler sonography. Extracranial and intracranial vasculatures were examined with a portable power M-mode transcranial Doppler unit. The middle cerebral artery mean flow velocity, pulsatility index, and their asymmetries were used to quantify flow patterns and develop an injury decision tree screening protocol. Student t tests validated associations between injuries and transcranial Doppler predictive measures. We evaluated 27 trauma patients with 13 injuries. Single vertebral artery injuries were most common (38.5%), followed by single internal carotid artery injuries (30%). Compared to patients without injuries, mean flow velocity asymmetry was higher for single internal carotid artery (P = .003) and single vertebral artery (P = .004) injuries. Similarly, pulsatility index asymmetry was higher in single internal carotid artery (P = .015) and single vertebral artery (P = .042) injuries, whereas the lowest pulsatility index was elevated for bilateral vertebral artery injuries (P = .006). The decision tree yielded 92% specificity, 93% sensitivity, and 93% correct classifications. In this pilot feasibility study, transcranial Doppler measures were significantly associated with the blunt cervical vascular injury status, suggesting that transcranial Doppler sonography might be a viable bedside screening tool for trauma. Patient-specific hemodynamic information from transcranial Doppler assessment has the potential to alter

Application of DSA and ultrasonic blood rheography (Doppler) to benign paroxysmal positional vertigo

International Nuclear Information System (INIS)

Fujita, Nobuya; Wada, Yoshiro; Suzumura, Shigeo; Matsunaga, Takashi

1990-01-01

Fourteen cases of benign paroxysmal positional vertigo (BPPV) were studied with cervical circulation using DSA and Doppler. DSA study showed 7 abnormal cases out of 10 cases of BPPV. The abnormal findings included 5 cases of stenosis and 5 cases of coiling and kinking in cervical vertebral arteries. Doppler study showed that vertebral a. and also carotid a. had low volume and high laterality of cervical blood circulation in parameter of flow and velocity. These findings suggest the cervical circulation disorder was one of background factors in pathogenesis of BPPV. (author)

Application of DSA and ultrasonic blood rheography (Doppler) to benign paroxysmal positional vertigo

Energy Technology Data Exchange (ETDEWEB)

Fujita, Nobuya; Wada, Yoshiro; Suzumura, Shigeo; Matsunaga, Takashi (Nara Medical Univ., Kashihara (Japan))

1990-03-01

Fourteen cases of benign paroxysmal positional vertigo (BPPV) were studied with cervical circulation using DSA and Doppler. DSA study showed 7 abnormal cases out of 10 cases of BPPV. The abnormal findings included 5 cases of stenosis and 5 cases of coiling and kinking in cervical vertebral arteries. Doppler study showed that vertebral a. and also carotid a. had low volume and high laterality of cervical blood circulation in parameter of flow and velocity. These findings suggest the cervical circulation disorder was one of background factors in pathogenesis of BPPV. (author).

Reliability of the Load-Velocity Relationship Obtained Through Linear and Polynomial Regression Models to Predict the One-Repetition Maximum Load.

Science.gov (United States)

Pestaña-Melero, Francisco Luis; Haff, G Gregory; Rojas, Francisco Javier; Pérez-Castilla, Alejandro; García-Ramos, Amador

2017-12-18

This study aimed to compare the between-session reliability of the load-velocity relationship between (1) linear vs. polynomial regression models, (2) concentric-only vs. eccentric-concentric bench press variants, as well as (3) the within-participants vs. the between-participants variability of the velocity attained at each percentage of the one-repetition maximum (%1RM). The load-velocity relationship of 30 men (age: 21.2±3.8 y; height: 1.78±0.07 m, body mass: 72.3±7.3 kg; bench press 1RM: 78.8±13.2 kg) were evaluated by means of linear and polynomial regression models in the concentric-only and eccentric-concentric bench press variants in a Smith Machine. Two sessions were performed with each bench press variant. The main findings were: (1) first-order-polynomials (CV: 4.39%-4.70%) provided the load-velocity relationship with higher reliability than second-order-polynomials (CV: 4.68%-5.04%); (2) the reliability of the load-velocity relationship did not differ between the concentric-only and eccentric-concentric bench press variants; (3) the within-participants variability of the velocity attained at each %1RM was markedly lower than the between-participants variability. Taken together, these results highlight that, regardless of the bench press variant considered, the individual determination of the load-velocity relationship by a linear regression model could be recommended to monitor and prescribe the relative load in the Smith machine bench press exercise.

A local-velocity meter for hypersonic plasma jet

International Nuclear Information System (INIS)

Nyazev, A.A.; Lerner, N.B.; Svinolupov, K.I.

1985-01-01

This paper describes a system for a resonant laser Doppler meter for the local velocity in a hypersonic plasma flow. Preliminary test results on the prototype are reported for a jet of air containing sodium at 1100 degrees K, air pressure in the working region 20-200 Pa, and jet speed 6-8 km/sec. Measured speeds agree with theoretical predictions. The prototype and the method do not impose constraints on the working conditions but can be extended to wide ranges in temperature and pressure, such as ones in which the line width does not exceed the Doppler shift

Doppler spectroscopy as a path to the detection of Earth-like planets.

Science.gov (United States)

Mayor, Michel; Lovis, Christophe; Santos, Nuno C

2014-09-18

Doppler spectroscopy was the first technique used to reveal the existence of extrasolar planetary systems hosted by solar-type stars. Radial-velocity surveys led to the detection of a rich population of super-Earths and Neptune-type planets. The numerous detected systems revealed a remarkable diversity. Combining Doppler measurements with photometric observations of planets transiting their host stars further provides access to the planet bulk density, a first step towards comparative exoplanetology. The development of new high-precision spectrographs and space-based facilities will ultimately lead us to characterize rocky planets in the habitable zone of our close stellar neighbours.

New Methods for Estimating Water Current Velocity Fields from Autonomous Underwater Vehicles

Science.gov (United States)

Kinsey, J. C.; Medagoda, L.

2016-02-01

Water current velocities are a crucial component of understanding oceanographic processes and underwater robots, such as autonomous underwater vehicles (AUVs), provide a mobile platform for obtaining these observations. Estimating water current velocities requires both measurements of the water velocity, often obtained with an Acoustic Doppler Current Profiler (ADCP), as well as estimates of the vehicle velocity. Presently, vehicle velocities are supplied on the sea surface with velocity from GPS, or near the seafloor where Doppler Velocity Log (DVL) in bottom-lock is available; however, this capability is unavailable in the mid-water column where DVL bottom-lock and GPS are unavailable. Here we present a method which calculates vehicle velocities using consecutive ADCP measurements in the mid-water using an extended Kalman filter (EKF). The correlation of the spatially changing water current states, along with mass transport and shear constraints on the water current field, is formulated using least square constraints. Results from the Sentry AUV from a mid-water surveying mission at Deepwater Horizon and a small-scale hydrothermal vent flux estimation mission suggest the method is suitable for real-time use. DVL data is denied to simulate mid-water missions and the results compared to ground truth water velocity measurements estimated using DVL velocities. Results show quantifiable uncertainties in the water current velocities, along with similar performance, for the DVL and no-DVL case in the mid-water. This method has the potential to provide geo-referenced water velocity measurements from mobile ocean robots in the absence of GPS and DVL as well as estimate the uncertainty associated with the measurements.

Effects of coil closure of patent ductus arteriosus on left anterior descending coronary artery blood flow using transthoracic Doppler echocardiography.

Science.gov (United States)

Harada, Kenji; Toyono, Manotomo; Tamura, Masamichi

2004-06-01

Transthoracic Doppler echocardiography provides noninvasive measurements of coronary blood flow in the left anterior descending coronary artery (LAD). This method has the potential to show the effects of acute changes in loading conditions on blood flow. Coil closure of patent ductus arteriosus (PDA) is a model of acute changes in blood pressure and left ventricular (LV) preload that influences coronary blood flow. We applied this technique to assess the coronary blood flow changes for patients with PDA before and immediately after PDA coil closure. We examined 9 patients (1.8 +/- 1.1 years) with simple PDA and 8 age-matched healthy children. LV dimensions and LV mass were measured. Maximum peak flow velocity and flow volume in the LAD were measured. Pulmonary to systemic flow ratios (Qp/Qs) were obtained by cardiac catheterization. After PDA coil closure, LV end-diastolic dimension decreased, and systolic and diastolic blood pressures increased significantly. The maximum peak flow velocity, LAD flow volume, and the ratio of LAD flow volume to LV mass increased significantly. The changes in maximum peak flow velocity and the ratio of LAD flow volume to LV mass (F/M) correlated positively with the changes in diastolic pressure and Qp/Qs. In 5 patients who had Qp/Qs > 1.5, the mean F/M was significantly lower compared with control subjects, but they increased to normal values after coil closure of PDA. PDA coil closure increases diastolic pressure and decreases Qp/Qs, resulting in improvement of myocardial perfusion. These findings provide new insights into the relationship between cardiac function and coronary circulation in pediatric patients with heart diseases associated with PDA.

Inverse Doppler shift and control field as coherence generators for the stability in superluminal light

Science.gov (United States)

Ghafoor, Fazal; Bacha, Bakht Amin; Khan, Salman

2015-05-01

A gain-based four-level atomic medium for the stability in superluminal light propagation using control field and inverse Doppler shift as coherence generators is studied. In regimes of weak and strong control field, a broadband and multiple controllable transparency windows are, respectively, identified with significantly enhanced group indices. The observed Doppler effect for the class of high atomic velocity of the medium is counterintuitive in comparison to the effect of the class of low atomic velocity. The intensity of each of the two pump fields is kept less than the optimum limit reported in [M. D. Stenner and D. J. Gauthier, Phys. Rev. A 67, 063801 (2003), 10.1103/PhysRevA.67.063801] for stability in the superluminal light pulse. Consequently, superluminal stable domains with the generated coherence are explored.

Two-dimensional and Doppler echocardiographic findings in healthy non-sedated red-eared slider terrapins (Trachemys scripta elegans).

Science.gov (United States)

Poser, H; Russello, G; Zanella, A; Bellini, L; Gelli, D

2011-12-01

Echocardiographic evaluation was performed in six healthy young adult non-sedated terrapins (Trachemys scripta elegans). The best imaging quality was obtained through the right cervical window. Base-apex inflow and outflow views were recorded, ventricular size, ventricular wall thickness and ventricular outflow tract were measured, and fractional shortening was calculated. Pulsed-wave Doppler interrogation enabled the diastolic biphasic atrio-ventricular flow and the systolic ventricular outflow patterns to be recorded. The following Doppler-derived functional parameters were calculated: early diastolic (E) and late diastolic (A) wave peak velocities, E/A ratio, ventricular outflow systolic peak and mean velocities and gradients, Velocity-Time Integral, acceleration and deceleration times, and Ejection Time. For each parameter the mean, standard deviation and 95% confidence interval were calculated. Echocardiography resulted as a useful and easy-to-perform diagnostic tool in this poorly known species that presents difficulties during evaluation.

To assess the intimal thickness, flow velocities, and luminal diameter of carotid arteries using high-resolution B-mode ultrasound doppler imaging

Science.gov (United States)

Vemuru, Madhuri; Jabbar, Afzal; Chandra, Suman

2004-04-01

Carotid imaging is a Gold Standard test that provides useful information about the structure and functions of carotid arteries. Spectral imaging helps to evaluate the vessel and hemodynamic changes. High resolution B-mode imaging has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and its progression and for assessing cardiovascular risks. The measurements made with Doppler correlate well with pathologic measurements. Recent prospective studies have clearly demonstrated that these measurements of carotid intimal thickness are potent predictors of Myocardial Infarction and Stroke. This method appears very attractive as it is non-invasive, extremely safe, well accepted by the patient and relatively inexpensive. It can be performed serially and has the advantage of visualizing the arterial wall in contrast to angiographic techniques which provide only an outline of the arterial lumen. Recently, there has been an interest in the clinical use of this technique in making difficult clinical decisions like deciding on preventive therapies. 30 subjects aged 21-60 years and 30 subjects aged 61-85 years of both sexes are selected after doing a baseline study to exclude Hypertension, Diabetes, Obesity and Hyperlipidemia. The carotid arteries were examined for intimal thickening, blood flow velocities and luminal diameter. With aging there is a narrowing of the carotid vessels and significant increase in intimal thickening with a consequent increase in the blood flow velocities. Inter-observer, intra-observer and instrument variations are seen and there is no significant change in the values when the distal flow pattern is considered for measurements. Aging produces major cardiovascular changes including decreased elasticity and compliance of great arteries leading to structural and functional alterations in heart and vessels. With aging there is increased intimal thickness and increased pulse wave velocity which is clearly

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.

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.

An evaluation of the use of new Doppler methods for detecting longitudinal function abnormalities in a pacing-induced heart failure model

Science.gov (United States)

Tabata, Tomotsugu; Cardon, Lisa A.; Armstrong, Guy P.; Fukamach, Kiyotaka; Takagaki, Masami; Ochiai, Yoshie; McCarthy, Patrick M.; Thomas, James D.

2003-01-01

BACKGROUND: Doppler tissue echocardiography and color M-mode Doppler flow propagation velocity have proven useful in evaluating cross-sections of patients with left ventricular (LV) dysfunction, but experience with serial changes is limited. Purpose and methods: We tested their use by evaluating the temporal changes of LV function in a pacing-induced congestive heart failure model. Rapid ventricular pacing was initiated and maintained in 20 dogs for 4 weeks. Echocardiography was performed at baseline and weekly during brief pacing cessation. RESULTS: With rapid pacing, LV volume significantly increased and ejection fraction (57%-28%), stroke volume (37-18 mL), and mitral annulus systolic velocity (16.1-6.6 cm/s) by Doppler tissue echocardiography significantly decreased, with ejection fraction and mitral annulus systolic velocity closely correlated (r = 0.706, P evaluate the serial deterioration in LV dysfunction throughout the pacing period. These were more useful in quantifying progressive LV dysfunction than conventional ehocardiographic techniques, and were probably relatively independent of preload. These techniques could be suitable for longitudinal evaluation in addition to the cross-sectional study.

The Role of Color Doppler Ultrasonography in Characterization of Thyroid Tumors

International Nuclear Information System (INIS)

Kim, Hee Soo; Jeon, Pyong; Won, Jong Yoon; Na, Jae Beom; Lee, Hyang Mee; Yoo, Hyung Sik; Lee, Jong Tae; Park, Jeong Soo; Cho, Nam Hoon

1995-01-01

To assess the usefulness of color Doppler ultrasonography in the characterization of thyroid tumors, surgically proven 88 nodules in 85 patients were evaluated. Using 10 MHz linear array transducer, gray scale images were initially evaluated. Then, distribution pattern of color signals (marginal, intra-tumoral, mixed) and graded internal vascularity according to morphology of color signal (0:absence of internal signal, 1: spotty, 2: linear,3: branching) were observed on color doppler imaging. Pulsed doppler waves were analyzed with parameters including peak systolic velocity(PSV), resistive index(RI), and pulsatile index(PI). Significantly larger numbers of intra-tumoral type, 20 cases(62.5%), were observed in malignant nodules, whereas mixed forms were predominant in benign group, 37 cases (66%) In graded internal vascularity, malignant nodules tended to have grade 2 or 3 signals, whereas benign nodules tended to have grade 0 or 1 signals. Spectral wave analysis show no significant difference in the value of PSV, RI, and PI between malignancy and benignity group. In conclusion, color Doppler imaging has a potential role in the characterization of thyroid nodules as a supportive method for gray scale diagnosis

Cerebral Lateralization and General Intelligence: Gender Differences in a Transcranial Doppler Study

Science.gov (United States)

Njemanze, P.C.

2005-01-01

The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed…

Peak negative myocardial velocity gradient in early diastole as a noninvasive indicator of left ventricular diastolic function: comparison with transmitral flow velocity indices.

Science.gov (United States)

Shimizu, Y; Uematsu, M; Shimizu, H; Nakamura, K; Yamagishi, M; Miyatake, K

1998-11-01

We sought to assess the clinical significance of peak negative myocardial velocity gradient (MVG) in early diastole as a noninvasive indicator of left ventricular (LV) diastolic function. Peak systolic MVG has been shown useful for the quantitative assessment of regional wall motion abnormalities, but limited data exist regarding the diastolic MVG as an indicator of LV diastolic function. Peak negative MVG was obtained from M-mode tissue Doppler imaging (TDI) in 43 subjects with or without impairment of systolic and diastolic performance: 12 normal subjects, 12 patients with hypertensive heart disease (HHD) with normal systolic performance and 19 patients with dilated cardiomyopathy (DCM), and was compared with standard Doppler transmitral flow velocity indices. In a subgroup of 30 patients, effects of preload increase on these indices were assessed by performing passive leg lifting. In an additional 11 patients with congestive heart failure at the initial examination, the measurements were repeated after 26+/-16 days of volume-reducing therapy. Peak negative MVG was significantly depressed both in HHD (-3.9+/-1.3/s, p indices failed to distinguish DCM from normal due to the pseudonormalization. Transmitral flow velocity indices were significantly altered (peak early/late diastolic filling velocity [E/A]=1.1+/-0.5 to 1.5+/-0.7, p indicator of LV diastolic function that is less affected by preload alterations than the transmitral flow velocity indices, and thereby could be used for the follow-up of patients with nonischemic LV dysfunction presenting congestive heart failure.

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.

Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

Full Text Available The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of the ambient electrons is modelled by a near-Maxwellian distribution function in presence of a temperature gradient and a potential electric field. The velocity distribution function of the suprathermal electrons is derived from a numerical model of the angular energy flux spectrum obtained by solving the transport equation of electrons. The numerical method used to calculate the plasma dispersion function and the reduced velocity distribution is described. The numerical code is used with simulated data to evaluate the Doppler frequency asymmetry between the up- and downshifted plasma lines of the incoherent-scatter plasma lines at different wave vectors. It is shown that the observed Doppler asymmetry is more dependent on deviation from the Maxwellian through the thermal part for high-frequency radars, while for low-frequency radars the Doppler asymmetry depends more on the presence of a suprathermal population. It is also seen that the full evaluation of the plasma dispersion function gives larger Doppler asymmetry than the heat flow approximation for Langmuir waves with phase velocity about three to six times the mean thermal velocity. For such waves the moment expansion of the dispersion function is not fully valid and the full calculation of the dispersion function is needed.

Key words. Non-Maxwellian electron velocity distribution · Incoherent scatter plasma lines · EISCAT · Dielectric response function

Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

1998-10-01

Full Text Available The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron velocity distribution is separated into two distributions representing the distribution of the ambient electrons and the suprathermal electrons. The velocity distribution function of the ambient electrons is modelled by a near-Maxwellian distribution function in presence of a temperature gradient and a potential electric field. The velocity distribution function of the suprathermal electrons is derived from a numerical model of the angular energy flux spectrum obtained by solving the transport equation of electrons. The numerical method used to calculate the plasma dispersion function and the reduced velocity distribution is described. The numerical code is used with simulated data to evaluate the Doppler frequency asymmetry between the up- and downshifted plasma lines of the incoherent-scatter plasma lines at different wave vectors. It is shown that the observed Doppler asymmetry is more dependent on deviation from the Maxwellian through the thermal part for high-frequency radars, while for low-frequency radars the Doppler asymmetry depends more on the presence of a suprathermal population. It is also seen that the full evaluation of the plasma dispersion function gives larger Doppler asymmetry than the heat flow approximation for Langmuir waves with phase velocity about three to six times the mean thermal velocity. For such waves the moment expansion of the dispersion function is not fully valid and the full calculation of the dispersion function is needed.Key words. Non-Maxwellian electron velocity distribution · Incoherent scatter plasma lines · EISCAT · Dielectric response function

Doppler interpretation of quasar red shifts.

Science.gov (United States)

Zapolsky, H S

1966-08-05

The hypothesis that the quasistellar sources (quasars) are local objects moving with velocities close to the speed of light is examined. Provided there is no observational cutoff on apparent bolometric magnitude for the quasars, the transverse Doppler effect leads to the expectation of fewer blue shifts than red shifts for an isotropic distribution of velocities. Such a distribution also yields a function N(z), the number of objects with red shift less than z which is not inconsistent with the present data. On the basis of two extreme assumptions concerning the origin of such rapidly moving sources, we computed curves of red shift plotted against magnitude. In particular, the curve obtained on the assumption that the quasars originated from an explosion in or nearby our own galaxy is in as good agreement with the observations as the curve of cosmological red shift plotted against magnitude.

Middle cerebral artery blood velocity depends on cardiac output during exercise with a large muscle mass

NARCIS (Netherlands)

Ide, K.; Pott, F.; van Lieshout, J. J.; Secher, N. H.

1998-01-01

We tested the hypothesis that pharmacological reduction of the increase in cardiac output during dynamic exercise with a large muscle mass would influence the cerebral blood velocity/perfusion. We studied the relationship between changes in cerebral blood velocity (transcranial Doppler), rectus

The effect of TACE with endostatin on hemodynamics in hepatic implantation tumor using Doppler ultrasonography

International Nuclear Information System (INIS)

Zhou Guangli; Wu Yuanyuan; Wang Bin; Liu Yan; Zheng Chuanli; Sang Li; Liu Feng

2009-01-01

Objective: To investigate the hemodynamic changes in the rabbit liver and VX2 hepatic implantation tumor after treatment by transcatheter arterial chemoembolization (TACE)/endostatin using Doppler ultrasonography. Methods: Twenty rabbits with VX2 hepatic tumor were randomly distributed into the control group (n=10) and the anti- angiogenesis group (n=10). The rabbits were administered with endostatin and adriamycin-lipiodol in the anti-angiogenesis group and with 37℃ saline in the control group via hepatic artery. The hemodynamic changes of the tumors, hepatic artery, and portal vein were recorded with Doppler ultrasonography 1 week after the treatment. The results before and after the treatment were compared. Results: In the control group, the maximal hepatic artery blood flow velocity was significantly higher than that before the treatment (P<0.05). However, the resistance index and the portal vein blood flow velocities had no significantly change compared with those before the treatment (P>0.05). In the anti-angiogenesis group, the hepatic artery blood flow velocity was significantly lower than that before the treatment (P<0.05), and the resistance index was increased (P<0.05). However, the portal vein blood flow velocity had no significantly change (P>0.05). The blood flow signal in all tumors was rich before embolization. After TACE, the blood flow signal was significantly decreased, even partly disappeared in the anti-angiogenesis group. Conclusion: TACE with endostatin can effectively block the blood supplement of VX2 hepatic implantation tumor. Doppler ultrasonography can detected the blood flow changes and can be used in evaluating the therapeutic effect in hepatic implantation tumor. (authors)

High- and Low-Order Overtaking-Ability Affordances: Drivers Rely on the Maximum Velocity and Acceleration of Their Cars to Perform Overtaking Maneuvers.

Science.gov (United States)

Basilio, Numa; Morice, Antoine H P; Marti, Geoffrey; Montagne, Gilles

2015-08-01

The aim of this study was to answer the question, Do drivers take into account the action boundaries of their car when overtaking? The Morice et al. affordance-based approach to visually guided overtaking suggests that the "overtake-ability" affordance can be formalized as the ratio of the "minimum satisfying velocity" (MSV) of the maneuver to the maximum velocity (V(max)) of the driven car. In this definition, however, the maximum acceleration (A(max)) of the vehicle is ignored. We hypothesize that drivers may be sensitive to an affordance redefined with the ratio of the "minimum satisfying acceleration" (MSA) to the A(max) of the car. Two groups of nine drivers drove cars differing in their A(max). They were instructed to attempt overtaking maneuvers in 25 situations resulting from the combination of five MSA and five MSV values. When overtaking frequency was expressed as a function of MSV and MSA, maneuvers were found to be initiated differently for the two groups. However, when expressed as a function of MSV/V(max) and MSA/A(max), overtaking frequency was quite similar for both groups. Finally, a multiple regression coefficient analysis demonstrated that overtaking decisions are fully explained by a composite variable comprising MSA/A(max) and the time required to reach MSV. Drivers reliably decide whether overtaking is safe (or not) by using low- and high-order variables taking into account their car's maximum velocity and acceleration, respectively, as predicted by "affordance-based control" theory. Potential applications include the design of overtaking assistance, which should exploit the MSA/A(max) variables in order to suggest perceptually relevant overtaking solutions. © 2015, Human Factors and Ergonomics Society.

A clutter removal method for the Doppler ultrasound signal based on a nonlinear diffusion equation

International Nuclear Information System (INIS)

Li Peng; Xin Pengcheng; Bian Zhengzhong; Yu Gang

2008-01-01

Strong clutter components produced by stationary and slow-moving tissue structures render the lower frequency part of the spectrogram useless and degrade the accuracy of clinical ultrasound indices. An adaptive method based on the nonlinear forward-and-backward diffusion equation (FAB-DE) is proposed to remove strong clutter components from the contaminated Doppler signal. The clutter signal is extracted first by the FAB-DE accurately, in which the nonlinear diffusion coefficient function of the FAB-DE locally adjusts according to signal features and the diffusion adaptively switches between forward and backward mode. The present method has been validated by simulated and realistic pulse wave Doppler signals, and compared with the conventional high pass filter and the matching pursuit method. The simulation results, including spectrogram, mean velocity error, standard deviation of mean velocity and signal-to-clutter ratio of a decontaminated signal, demonstrate that the present FAB-DE method can remove clutter sufficiently and retain more low blood components simultaneously as compared with the other two methods. Results of the realistic Doppler blood signal, including spectrogram and low-frequency part of the spectrum, support the conclusion drawn from simulation cases

Changes in cerebral artery blood flow velocity after intermittent cerebrospinal fluid drainage.

OpenAIRE

Kempley, S T; Gamsu, H R

1993-01-01

Doppler ultrasound was used to measure blood flow velocity in the anterior cerebral artery of six premature infants with posthaemorrhagic hydrocephalus, before and after intermittent cerebrospinal fluid (CSF) drainage, on 23 occasions. There was a significant increase in mean blood flow velocity after the drainage procedures (+5.6 cm/s, 95% confidence interval +2.9 to +8.3 cm/s), which was accompanied by a decrease in velocity waveform pulsatility. CSF pressure also fell significantly. In pat...

Relativistic Velocity Addition Law from Machine Gun Analogy

Science.gov (United States)

Rothenstein, Bernhard; Popescu, Stefan

2009-01-01

Many derivations of the relativistic addition law of parallel velocities without use of the Lorentz transformations (LT) are known. Some of them are based on thought experiments that require knowledge of the time dilation and the length contraction effects. Other derivations involve the Doppler effect in the optic domain considered from three…

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.

Conceptual design of an airborne laser Doppler velocimeter system for studying wind fields associated with severe local storms

Science.gov (United States)

Thomson, J. A. L.; Davies, A. R.; Sulzmann, K. G. P.

1976-01-01

An airborne laser Doppler velocimeter was evaluated for diagnostics of the wind field associated with an isolated severe thunderstorm. Two scanning configurations were identified, one a long-range (out to 10-20 km) roughly horizontal plane mode intended to allow probing of the velocity field around the storm at the higher altitudes (4-10 km). The other is a shorter range (out to 1-3 km) mode in which a vertical or horizontal plane is scanned for velocity (and possibly turbulence), and is intended for diagnostics of the lower altitude region below the storm and in the out-flow region. It was concluded that aircraft flight velocities are high enough and severe storm lifetimes are long enough that a single airborne Doppler system, operating at a range of less than about 20 km, can view the storm area from two or more different aspects before the storm characteristics change appreciably.

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.

Doppler lidar sensor for precision navigation in GPS-deprived environment

Science.gov (United States)

Amzajerdian, F.; Pierrottet, D. F.; Hines, G. D.; Petway, L. B.; Barnes, B. W.

2013-05-01

Landing mission concepts that are being developed for exploration of solar system bodies are increasingly ambitious in their implementations and objectives. Most of these missions require accurate position and velocity data during their descent phase in order to ensure safe, soft landing at the pre-designated sites. Data from the vehicle's Inertial Measurement Unit will not be sufficient due to significant drift error after extended travel time in space. Therefore, an onboard sensor is required to provide the necessary data for landing in the GPS-deprived environment of space. For this reason, NASA Langley Research Center has been developing an advanced Doppler lidar sensor capable of providing accurate and reliable data suitable for operation in the highly constrained environment of space. The Doppler lidar transmits three laser beams in different directions toward the ground. The signal from each beam provides the platform velocity and range to the ground along the laser line-of-sight (LOS). The six LOS measurements are then combined in order to determine the three components of the vehicle velocity vector, and to accurately measure altitude and attitude angles relative to the local ground. These measurements are used by an autonomous Guidance, Navigation, and Control system to accurately navigate the vehicle from a few kilometers above the ground to the designated location and to execute a gentle touchdown. A prototype version of our lidar sensor has been completed for a closed-loop demonstration onboard a rocket-powered terrestrial free-flyer vehicle.

Comparison of brucella and non-specific epididymorchitis: gray scale and color Doppler ultrasonographic features

International Nuclear Information System (INIS)

Ozturk, Adil; Ozturk, Ebru; Zeyrek, Fadile; Onur, Kahraman; Sirmatel, Ocal; Kat, Nurcan

2005-01-01

Objective: The aim of this study is to find out if it is possible to differentiate between brucellar and non-specific epididymorchitis by comparing ultrasonography (US) and color Doppler ultrasonography (CDUS) findings. Material and methods: Fifty-six patients diagnosed to have epididymorchitis both clinically and ultrasonographically were included to study. All of the patients were investigated serologically for brucella. Twenty-eight of those patients were admitted brucella epididymorchitis because of high agglutinations titers for brucella. The other 28 patients were admitted non-specific epididymorchitis because of normal agglutinations titers for brucella. Testicular size, echogenicity, hydrocele, internal echoes and/or septations within hydrocele, and scrotal skin thickness of normal and involved testis were compared by ultrasonography. Besides, pick systolic velocity, end diastolic velocity, resistive index and pick systolic velocity ratio values were measured by bilateral testicular color Doppler ultrasonography in both groups. When the p-value is <0.05, the difference between groups is accepted as statistically significant. Results: Thickening of scrotal skin was seen in 17 of 28 patients with brucella epididymorchitis (BEPO) (67%) and in 25 of 28 patients with non-specific epididymorchitis (NEPO) (89.2%) (p < 0.01). There was no difference between groups regarding presence of hydrocele. However hydrocele seen in all patients was anechoic except for two patients (8.6%). Hydrocele seen in 18 of 22 patients with BEPO and hydrocele had internal echogenicity or septation (p < 0.001). Sizes of testes and epididymis were found to be increased in involved testis compared to normal testis. Testes of all patients with NEPO were homogenous with decreased echogenicity except for five patients (17.8%). However, 23 patients with BEPO (82%) found to have heterogenous testis (p < 0.001). Spectral measurements showed increased PSV and EDV values and decreased RI values in

Comparison of brucella and non-specific epididymorchitis: gray scale and color Doppler ultrasonographic features

Energy Technology Data Exchange (ETDEWEB)

Ozturk, Adil [Department of Radiology, Harran University School of Medicine, Arastirma ve Uygulama Hastanesi, TR-63100 Sanliurfa (Turkey)]. E-mail: ozturka26@hotmail.com; Ozturk, Ebru [Department of Radiology, Harran University School of Medicine, Arastirma ve Uygulama Hastanesi, TR-63100 Sanliurfa (Turkey); Zeyrek, Fadile [Department of Microbiology, Harran University School of Medicine, Sanliurfa (Turkey); Onur, Kahraman [Department of Urology, SSK Sanliurfa Hastanesi, Sanliurfa (Turkey); Sirmatel, Ocal [Department of Radiology, Harran University School of Medicine, Arastirma ve Uygulama Hastanesi, TR-63100 Sanliurfa (Turkey); Kat, Nurcan [Department of Radiology, Harran University School of Medicine, Arastirma ve Uygulama Hastanesi, TR-63100 Sanliurfa (Turkey)

2005-11-01

Objective: The aim of this study is to find out if it is possible to differentiate between brucellar and non-specific epididymorchitis by comparing ultrasonography (US) and color Doppler ultrasonography (CDUS) findings. Material and methods: Fifty-six patients diagnosed to have epididymorchitis both clinically and ultrasonographically were included to study. All of the patients were investigated serologically for brucella. Twenty-eight of those patients were admitted brucella epididymorchitis because of high agglutinations titers for brucella. The other 28 patients were admitted non-specific epididymorchitis because of normal agglutinations titers for brucella. Testicular size, echogenicity, hydrocele, internal echoes and/or septations within hydrocele, and scrotal skin thickness of normal and involved testis were compared by ultrasonography. Besides, pick systolic velocity, end diastolic velocity, resistive index and pick systolic velocity ratio values were measured by bilateral testicular color Doppler ultrasonography in both groups. When the p-value is <0.05, the difference between groups is accepted as statistically significant. Results: Thickening of scrotal skin was seen in 17 of 28 patients with brucella epididymorchitis (BEPO) (67%) and in 25 of 28 patients with non-specific epididymorchitis (NEPO) (89.2%) (p < 0.01). There was no difference between groups regarding presence of hydrocele. However hydrocele seen in all patients was anechoic except for two patients (8.6%). Hydrocele seen in 18 of 22 patients with BEPO and hydrocele had internal echogenicity or septation (p < 0.001). Sizes of testes and epididymis were found to be increased in involved testis compared to normal testis. Testes of all patients with NEPO were homogenous with decreased echogenicity except for five patients (17.8%). However, 23 patients with BEPO (82%) found to have heterogenous testis (p < 0.001). Spectral measurements showed increased PSV and EDV values and decreased RI values in

Performance evaluation of a thermal Doppler Michelson interferometer system.

Science.gov (United States)

Mani, Reza; Dobbie, Steven; Scott, Alan; Shepherd, Gordon; Gault, William; Brown, Stephen

2005-11-20

The thermal Doppler Michelson interferometer is the primary element of a proposed limb-viewing satellite instrument called SWIFT (Stratospheric Wind Interferometer for Transport studies). SWIFT is intended to measure stratospheric wind velocities in the altitude range of 15-45 km. SWIFT also uses narrowband tandem etalon filters made of germanium to select a line out of the thermal spectrum. The instrument uses the same technique of phase-stepping interferometry employed by the Wind Imaging Interferometer onboard the Upper Atmosphere Research Satellite. A thermal emission line of ozone near 9 microm is used to detect the Doppler shift due to winds. A test bed was set up for this instrument that included the Michelson interferometer and the etalon filters. For the test bed work, we investigate the behavior of individual components and their combination and report the results.

Ultrasonic Doppler Velocity Profiler for Fluid Flow

CERN Document Server

2012-01-01

The ultrasonic velocity profile (UVP) method, first developed in medical engineering, is now widely used in clinical settings. The fluid mechanical basis of UVP was established in investigations by the author and his colleagues with work demonstrating that UVP is a powerful new tool in experimental fluid mechanics. There are diverse examples, ranging from problems in fundamental fluid dynamics to applied problems in mechanical, chemical, nuclear, and environmental engineering. In all these problems, the methodological principle in fluid mechanics was converted from point measurements to spatio-temporal measurements along a line. This book is the first monograph on UVP that offers comprehensive information about the method, its principles, its practice, and applied examples, and which serves both current and new users. Current users can confirm that their application configurations are correct, which will help them to improve the configurations so as to make them more efficient and effective. New users will be...

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

Transcranial Doppler and cardiovascular responses during cardiovascular autonomic tests in migraineurs during and outside attacks

DEFF Research Database (Denmark)

Thomsen, L L; Iversen, Helle Klingenberg; Boesen, F

1995-01-01

during unilateral attacks of migraine without aura. Transcranial Doppler examinations of middle cerebral artery (MCA) blood velocity showed no differences between migraineurs and healthy subjects and no difference between migraineurs experiencing an attack and outside an attack when examined in response...

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

International Nuclear Information System (INIS)

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F.

2015-01-01

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

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

Science.gov (United States)

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F

2015-09-01

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. 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. 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 ± 0.31 μl/min among four wild-type rats. The authors' measured flow rates were consistent with results in the literature. 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.

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.

Velocity Estimation of the Main Portal Vein with Transverse Oscillation

DEFF Research Database (Denmark)

Brandt, Andreas Hjelm; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann

2015-01-01

This study evaluates if Transverse Oscillation (TO) can provide reliable and accurate peak velocity estimates of blood flow the main portal vein. TO was evaluated against the recommended and most widely used technique for portal flow estimation, Spectral Doppler Ultrasound (SDU). The main portal...

Augmented Reality Based Doppler Lidar Data Visualization: Promises and Challenges

Science.gov (United States)

Cherukuru, N. W.; Calhoun, R.

2016-06-01

Augmented reality (AR) is a technology in which the enables the user to view virtual content as if it existed in real world. We are exploring the possibility of using this technology to view radial velocities or processed wind vectors from a Doppler wind lidar, thus giving the user an ability to see the wind in a literal sense. This approach could find possible applications in aviation safety, atmospheric data visualization as well as in weather education and public outreach. As a proof of concept, we used the lidar data from a recent field campaign and developed a smartphone application to view the lidar scan in augmented reality. In this paper, we give a brief methodology of this feasibility study, present the challenges and promises of using AR technology in conjunction with Doppler wind lidars.

Spacecraft Doppler tracking with possible violations of LLI and LPI: a theoretical modeling

International Nuclear Information System (INIS)

Deng Xue-Mei; Xie Yi

2014-01-01

Currently two-way and three-way spacecraft Doppler tracking techniques are widely used and play important roles in control and navigation of deep space missions. Starting from a one-way Doppler model, we extend the theory to two-way and three-way Doppler models by making them include possible violations of the local Lorentz invariance (LLI) and the local position invariance (LPI) in order to test the Einstein equivalence principle, which is the cornerstone of general relativity and all other metric theories of gravity. After taking the finite speed of light into account, which is the so-called light time solution (LTS), we make these models depend on the time of reception of the signal only for practical convenience. We find that possible violations of LLI and LPI cannot affect two-way Doppler tracking under a linear approximation of LTS, although this approximation is sufficiently good for most cases in the solar system. We also show that, in three-way Doppler tracking, possible violations of LLI and LPI are only associated with two stations, which suggests that it is better to set the stations at places with significant differences in velocities and gravitational potentials to obtain a high level of sensitivity for the tests

Multipoint photonic doppler velocimetry using optical lens elements

Science.gov (United States)

Frogget, Brent Copely; Romero, Vincent Todd

2014-04-29

A probe including a fisheye lens is disclosed to measure the velocity distribution of a moving surface along many lines of sight. Laser light, directed to the surface and then reflected back from the surface, is Doppler shifted by the moving surface, collected into fisheye lens, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to an index-matching lens and eventually to a fisheye lens. The fiber array flat polished and coupled to the index-matching lens using index-matching gel. Numerous fibers in a fiber array project numerous rays through the fisheye lens which in turn project many measurement points at numerous different locations to establish surface coverage over a hemispherical shape with very little crosstalk.

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.

Doppler ultrasonography of the pectinis oculi artery in harpy eagles (Harpia harpyja

Directory of Open Access Journals (Sweden)

Wanderlei de Moraes

2017-03-01

Full Text Available Twenty harpy eagles (Harpia harpyja without systemic or ocular diseases were examined to measure blood velocity parameters of the pectinis oculi artery using Doppler ultrasonography. Pectinate artery resistive index (RI and pulsatility index (PI were investigated using ocular Doppler ultrasonography. The mean RI and PI values across all eyes were 0.44±0.10 and 0.62±0.20 respectively. Low RI and PI values found in the harpy eagle´s pectinis oculi artery compared with the American pekin ducks one and other tissue suggest indeed a high metabolic activity in pecten oculi and corroborates the hypothesis of a nutritional function and/or intraocular pressure regulation.

Evaluation of turbulence measurement techniques from a single Doppler lidar

Directory of Open Access Journals (Sweden)

T. A. Bonin

2017-08-01

Full Text Available 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.

Spin-Orbit Misalignments of Three Jovian Planets via Doppler Tomography

Science.gov (United States)

Johnson, Marshall C.; Cochran, William D.; Addison, Brett C.; Tinney, Chris G.; Wright, Duncan J.

2017-10-01

We present measurements of the spin-orbit misalignments of the hot Jupiters HAT-P-41 b and WASP-79 b, and the aligned warm Jupiter Kepler-448 b. We obtain these measurements with Doppler tomography, where we spectroscopically resolve the line profile perturbation during the transit due to the Rossiter-McLaughlin effect. We analyze time series spectra obtained during portions of five transits of HAT-P-41 b, and find a value of the spin-orbit misalignment of λ =-{22.1}-6.0{+0.8^\\circ }. We reanalyze the radial velocity Rossiter-McLaughlin data on WASP-79 b obtained by Addison et al. using Doppler tomographic methodology. We measure λ =-{99.1}-3.9{+4.1^\\circ }, consistent with but more precise than the value found by Addison et al. For Kepler-448 b we perform a joint fit to the Kepler light curve, Doppler tomographic data, and a radial velocity data set from Lillo-Box et al. We find an approximately aligned orbit (λ =-{7.1}-2.8{+4.2^\\circ }), in agreement with the value found by Bourrier et al. Through analysis of the Kepler light curve we measure a stellar rotation period of {P}{rot}=1.27+/- 0.11 days, and use this to argue that the full three-dimensional spin-orbit misalignment is small, \\psi ˜ 0^\\circ . Based in part on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

The impact of left ventricular preload reduction on cardiac pulsed doppler indices during hemodialysis and its relation to intra-dialysis hypotension: A pulsed doppler study

International Nuclear Information System (INIS)

Alarrayed, Sameer; Garadah Taysir Said; Alawdi, Abdulhai Ali

2009-01-01

Fluid status in the body plays an important role on left ventricular (LV) filling in patients with end-stage renal disease (ESRD) on regular hemodialysis (HD), and plays a role in intra-dialysis hemodynamic derangement. Fifty-two patients with ESRD on regular HD, including 34 males with a mean age of 45.5 +- 13 years (range 18-72 years), were studied. All patients underwent Echo-pulsed Doppler study before and immediately after a HD session. The Echo Doppler indices noted were: LV cavity dimension and wall thickness, LV ejection fraction (LVEF%), trans-mitral early diastolic filling velocity (E wave), atrial filling diastolic velocity (A wave), E/A ratio, Deceleration Time (DT) of E wave, Isovolumic relaxation time (IVRT), Aortic Velocity Integral (AVI) and Inferior Vena Cava Diameter (VCD) at expiration. Patients were divided into two groups according to the amount of net ultra filtrate loss after HD. Group I comprised of 25 patients with fluid loss of 2 liters. During the HD session, each patient was observed for the development of acute clinical events such as arterial hypotension (systolic BP less than 90 mmHg), chest pain and arrhythmias. There was a significant difference between the two groups in the mean values, pre- and post- HD, of reduction of E wave velocity (p < 0.01), the reduction of E/A ratio (p< 0.05), the increment in DT of E wave (p< 0.05), the reduction in AVI (p< 0.01) and the reduction of VCD (p< 0.05). There was no significant difference between the groups in the reduction of A wave velocity and the reduction of IVRT. Among the study patients, 11 (21%) developed systolic hypo-tension during HD. The pre-dialysis mean values of E/A ratio and DT of E wave in patients who developed hypotension compared to those who did not was 0.7 +- 0.2 vs 1.1 +- 0.2.1 (p< 0.001) and 246 +- 40 vs 224 +- 34 msec (p< 0.05), respectively. Our study suggests that preload reduction in patients with ESRD on regular HD is directly proportional to the reduction of left

Relationship of neonatal cerebral blood flow velocity asymmetry with early motor, cognitive and language development in term infants.

Science.gov (United States)

Wu, Ying-Chin; Hsieh, Wu-Shiun; Hsu, Chyong-Hsin; Chiu, Nan-Chang; Chou, Hung-Chieh; Chen, Chien-Yi; Peng, Shinn-Forng; Hung, Han-Yang; Chang, Jui-Hsing; Chen, Wei J; Jeng, Suh-Fang

2013-05-01

The objective of this study was to examine the relationships of Doppler cerebral blood flow velocity (CBFV) asymmetry measures with developmental outcomes in term infants. Doppler CBFV parameters (peak systolic velocity [PSV] and mean velocity [MV]) of the bilateral middle cerebral arteries of 52 healthy term infants were prospectively examined on postnatal days 1-5, and then their motor, cognitive and language development was evaluated with the Bayley Scales of Infant and Toddler Development, Third Edition, at 6, 12, 18 and 24 months of age. The left CBFV asymmetry measure (PSV or MV) was calculated by subtracting the right-side value from the left-side value. Left CBFV asymmetry measures were significantly positively related to motor scores at 6 (r = 0.3-0.32, p cognitive or language outcome. Thus, the leftward hemodynamic status of the middle cerebral arteries, as measured by cranial Doppler ultrasound in the neonatal period, predicts early motor outcome in term infants. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Investigations of unsteady flow in the draft tube of the pump- turbine model using laser Doppler anemometry

International Nuclear Information System (INIS)

Kaznacheev, A; Kuznetsov, I

2014-01-01

The measurements and video observation of unsteady flow in the draft tube cone of the pump-turbine model were conducted in the Laboratory of Water Turbines, property of OJSC ''Power machines'' - ''LMZ''. The prototype head was about 250 m. The experiments were performed for the turbine mode of operation. Measurements were taken for the unit speed value n11 corresponding to rated head in the generating mode of operation, for a wide range of guide vanes openings at loads ranging from partial to maximum value. The researches of the velocity field in function of the Thoma number were carried out in some operating conditions. The mean values and RMS deviations of the velocity components were the results of laser measurements. The curves of the intensity of the vortex versus the guide vane opening and the Thoma number were plotted. The energy velocity spectra were presented for the points at which the most pronounced frequency precession of the helical axial vortex was observed. Video recording and laser Doppler anemometry were made in the operating conditions of the developed cavitation. Based on the results of video observations and energy spectra obtained via LDA, vortex frequencies were determined i.e. the frequencies of the vortex precession under the runner in the draft tube cone

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.

AD Leonis: Radial Velocity Signal of Stellar Rotation or Spin–Orbit Resonance?

Science.gov (United States)

Tuomi, Mikko; Jones, Hugh R. A.; Barnes, John R.; Anglada-Escudé, Guillem; Butler, R. Paul; Kiraga, Marcin; Vogt, Steven S.

2018-05-01

AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days, as well as photometric signals: (1) a short-period signal, which is similar to the radial velocity signal, albeit with considerable variability; and (2) a long-term activity cycle of 4070 ± 120 days. We examine the short-term photometric signal in the available All-Sky Automated Survey and Microvariability and Oscillations of STars (MOST) photometry and find that the signal is not consistently present and varies considerably as a function of time. This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set, which are separated in median time by 3.38 days. In contrast, the Doppler signal is stable in the combined High-Accuracy Radial velocity Planet Searcher and High Resolution Echelle Spectrometer radial velocities for over 4700 days and does not appear to vary in time in amplitude, phase, period, or as a function of extracted wavelength. We consider a variety of starspot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots corotating on the stellar surface. This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin–orbit resonance. For such a scenario and no spin–orbit misalignment, the measured v\\sin i indicates an inclination angle of 15.°5 ± 2.°5 and a planetary companion mass of 0.237 ± 0.047 M Jup.

A brain-computer interface based on bilateral transcranial Doppler ultrasound.

Directory of Open Access Journals (Sweden)

Andrew J B Myrden

Full Text Available In this study, we investigate the feasibility of a BCI based on transcranial Doppler ultrasound (TCD, a medical imaging technique used to monitor cerebral blood flow velocity. We classified the cerebral blood flow velocity changes associated with two mental tasks--a word generation task, and a mental rotation task. Cerebral blood flow velocity was measured simultaneously within the left and right middle cerebral arteries while nine able-bodied adults alternated between mental activity (i.e. word generation or mental rotation and relaxation. Using linear discriminant analysis and a set of time-domain features, word generation and mental rotation were classified with respective average accuracies of 82.9%±10.5 and 85.7%±10.0 across all participants. Accuracies for all participants significantly exceeded chance. These results indicate that TCD is a promising measurement modality for BCI research.

Ultrasonographic study and Doppler flow velocimetry of maternal kidneys and liver in low-risk pregnancy

Energy Technology Data Exchange (ETDEWEB)

Daher, Cibele Helena; Gomes, Andrea Cavalanti; Kobayashi, Sergio; Chammas, Maria Cristina, E-mail: cibeledaher@hotmail.com [Universidade de Sao Paulo (In-Rad/HC-FMUSP), Sao Paulo, SP (Brazil). Hospital das Clinicas. Inst. de Radiologia; Cerri, Giovanni Guido [Universidade de Sao Paulo (FMUSP), Sao Paulo, SP (Brazil). Fac. de Medicina

2015-05-15

Objective: longitudinal study with B-mode ultrasonography and Doppler ultrasonography of maternal kidneys and liver in low-risk pregnancy, to establish and quantify normality parameters, correlating them with physiological changes. Materials and methods: twenty-five pregnant women were assessed and selected to participate in the study, each of them undergoing four examinations at the first, second, third trimesters and postpartum. Results: findings during pregnancy were the following: increased renal volume, pyelocaliceal dilatation with incidence of 45.4% in the right kidney, and 9% in the left kidney; nephrolithiasis, 18.1% in the right kidney, 13.6% in the left kidney. With pyelocaliceal dilatation, mean values for resistivity index were: 0.68 for renal arteries; 0.66 for segmental arteries; 0.64 for interlobar arteries; 0.64 for arcuate arteries. Without pyelocaliceal dilatation, 0.67 for renal arteries; 0.64 for segmental arteries; 0.63 for interlobar arteries; and 0.61 for arcuate arteries. Portal vein flow velocities presented higher values in pregnancy, with mean value for maximum velocity of 28.9 cm/s, and 22.6 cm/s postpartum. The waveform pattern of the right hepatic vein presented changes persisting in the postpartum period in 31.8% of the patients. Cholelithiasis was observed in 18.1% of the patients. Conclusion: alterations in renal volume, pyelocaliceal dilatation, nephrolithiasis, cholelithiasis, changes in portal vein flow velocity, alterations in waveform pattern of the right hepatic vein, proved to be significant. (author)

Ultrasonographic study and Doppler flow velocimetry of maternal kidneys and liver in low-risk pregnancy

International Nuclear Information System (INIS)

Daher, Cibele Helena; Gomes, Andrea Cavalanti; Kobayashi, Sergio; Chammas, Maria Cristina; Cerri, Giovanni Guido

2015-01-01

Objective: longitudinal study with B-mode ultrasonography and Doppler ultrasonography of maternal kidneys and liver in low-risk pregnancy, to establish and quantify normality parameters, correlating them with physiological changes. Materials and methods: twenty-five pregnant women were assessed and selected to participate in the study, each of them undergoing four examinations at the first, second, third trimesters and postpartum. Results: findings during pregnancy were the following: increased renal volume, pyelocaliceal dilatation with incidence of 45.4% in the right kidney, and 9% in the left kidney; nephrolithiasis, 18.1% in the right kidney, 13.6% in the left kidney. With pyelocaliceal dilatation, mean values for resistivity index were: 0.68 for renal arteries; 0.66 for segmental arteries; 0.64 for interlobar arteries; 0.64 for arcuate arteries. Without pyelocaliceal dilatation, 0.67 for renal arteries; 0.64 for segmental arteries; 0.63 for interlobar arteries; and 0.61 for arcuate arteries. Portal vein flow velocities presented higher values in pregnancy, with mean value for maximum velocity of 28.9 cm/s, and 22.6 cm/s postpartum. The waveform pattern of the right hepatic vein presented changes persisting in the postpartum period in 31.8% of the patients. Cholelithiasis was observed in 18.1% of the patients. Conclusion: alterations in renal volume, pyelocaliceal dilatation, nephrolithiasis, cholelithiasis, changes in portal vein flow velocity, alterations in waveform pattern of the right hepatic vein, proved to be significant. (author)

Evaluation of force-velocity and power-velocity relationship of arm muscles.

Science.gov (United States)

Sreckovic, Sreten; Cuk, Ivan; Djuric, Sasa; Nedeljkovic, Aleksandar; Mirkov, Dragan; Jaric, Slobodan

2015-08-01

A number of recent studies have revealed an approximately linear force-velocity (F-V) and, consequently, a parabolic power-velocity (P-V) relationship of multi-joint tasks. However, the measurement characteristics of their parameters have been neglected, particularly those regarding arm muscles, which could be a problem for using the linear F-V model in both research and routine testing. Therefore, the aims of the present study were to evaluate the strength, shape, reliability, and concurrent validity of the F-V relationship of arm muscles. Twelve healthy participants performed maximum bench press throws against loads ranging from 20 to 70 % of their maximum strength, and linear regression model was applied on the obtained range of F and V data. One-repetition maximum bench press and medicine ball throw tests were also conducted. The observed individual F-V relationships were exceptionally strong (r = 0.96-0.99; all P stronger relationships. The reliability of parameters obtained from the linear F-V regressions proved to be mainly high (ICC > 0.80), while their concurrent validity regarding directly measured F, P, and V ranged from high (for maximum F) to medium-to-low (for maximum P and V). The findings add to the evidence that the linear F-V and, consequently, parabolic P-V models could be used to study the mechanical properties of muscular systems, as well as to design a relatively simple, reliable, and ecologically valid routine test of the muscle ability of force, power, and velocity production.

Normal Doppler velocimetry of renal vasculature in Persian cats.

Science.gov (United States)

Carvalho, Cibele F; Chammas, Maria C

2011-06-01

Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m

Cluster headache: transcranial Doppler ultrasound and regional cerebral blood flow studies

International Nuclear Information System (INIS)

Dahl, A.; Russell, D.; Nyberg-Hansen, R.; Rootwelt, K.

1990-01-01

Transcranial Doppler and rCBF examinations were carried out in 25 cluster headache patients. Spontaneous glyceryl trinitrate (nitroglycerin) provoked attacks were accompanied by a bilateral decrease in middle cerebral artery blood flow velocities. This decrease was more pronounced on the symptomatic side, but the difference did not reach statistical significance. Mean hemispheric blood flow and rCBF were within normal limits during provoked attacks and similar to those found when patients were attack-free. During cluster periods middle cerebral artery velocities were significantly higher on the symptomatic side. Glyceryl trinitrate caused a bilateral middle cerebral artery velocity decrease which was significantly greater on the symptomatic side. Attacks provoked by glyceryl trinitrate appeared to begin when the vasodilatory effect of this substance was received. 17 refs., 2 figs., 5 tabs

Exercise and Cardiac Function by Tissue Doppler Imaging. The Copenhagen City Heart Study

DEFF Research Database (Denmark)

Joseph, Gowsini; Sogaard, Peter; Nielsen, Gitte

2016-01-01

diastolic (e') and late diastolic (a') velocities were measured by color TDI. Longitudinal displacement (LD) was calculated from the velocity curve during ejection. Statistical tests were performed by linear univariate and multivariable regression analyses, in relation to age groups (lt;50years, 50-65 years......Introduction: TDI (Tissue Doppler Imaging) is a sensitive marker of myocardial dysfunction and mortality in heart disease and in the general population. Regular physical activity is associated with risk reduction in coronary heart disease and mortality. There is a need for studies to clarify...

Exercise and Cardiac Function by Tissue Doppler Imaging. The Copenhagen City Heart Study

DEFF Research Database (Denmark)

Joseph, Gowsini; Sogaard, Peter; Nielsen, Gitte

diastolic (e') and late diastolic (a') velocities were measured by color TDI. Longitudinal displacement (LD) was calculated from the velocity curve during ejection. Statistical tests were performed by linear univariate and multivariable regression analyses, in relation to age groups (lt;50years, 50-65 years......Introduction: TDI (Tissue Doppler Imaging) is a sensitive marker of myocardial dysfunction and mortality in heart disease and in the general population. Regular physical activity is associated with risk reduction in coronary heart disease and mortality. There is a need for studies to clarify...

In-situ position and vibration measurement of rough surfaces using laser Doppler distance sensors

Science.gov (United States)

Czarske, J.; Pfister, T.; Günther, P.; Büttner, L.

2009-06-01

In-situ measurement of distances and shapes as well as dynamic deformations and vibrations of fast moving and especially rotating objects, such as gear shafts and turbine blades, is an important task at process control. We recently developed a laser Doppler distance frequency sensor, employing two superposed fan-shaped interference fringe systems with contrary fringe spacing gradients. Via two Doppler frequency evaluations the non-incremental position (i.e. distance) and the tangential velocity of rotating bodies are determined simultaneously. The distance uncertainty is in contrast to e.g. triangulation in principle independent of the object velocity. This unique feature allows micrometer resolutions of fast moved rough surfaces. The novel sensor was applied at turbo machines in order to control the tip clearance. The measurements at a transonic centrifugal compressor were performed during operation at up to 50,000 rpm, i.e. 586 m/s velocity of the blade tips. Due to the operational conditions such as temperatures of up to 300 °C, a flexible and robust measurement system with a passive fiber-coupled sensor, using diffractive optics, has been realized. Since the tip clearance of individual blades could be temporally resolved an analysis of blade vibrations was possible. A Fourier transformation of the blade distances results in an average period of 3 revolutions corresponding to a frequency of 1/3 of the rotary frequency. Additionally, a laser Doppler distance sensor using two tilted fringe systems and phase evaluation will be presented. This phase sensor exhibits a minimum position resolution of σz = 140 nm. It allows precise in-situ shape measurements at grinding and turning processes.

Photonic-Doppler-Velocimetry, Paraxial-Scalar Diffraction Theory and Simulation

Energy Technology Data Exchange (ETDEWEB)

Ambrose, W. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-07-20

In this report I describe current progress on a paraxial, scalar-field theory suitable for simulating what is measured in Photonic Doppler Velocimetry (PDV) experiments in three dimensions. I have introduced a number of approximations in this work in order to bring the total computation time for one experiment down to around 20 hours. My goals were: to develop an approximate method of calculating the peak frequency in a spectral sideband at an instant of time based on an optical diffraction theory for a moving target, to compare the ‘measured’ velocity to the ‘input’ velocity to gain insights into how and to what precision PDV measures the component of the mass velocity along the optical axis, and to investigate the effects of small amounts of roughness on the measured velocity. This report illustrates the progress I have made in describing how to perform such calculations with a full three dimensional picture including tilted target, tilted mass velocity (not necessarily in the same direction), and small amounts of surface roughness. With the method established for a calculation at one instant of time, measured velocities can be simulated for a sequence of times, similar to the process of sampling velocities in experiments. Improvements in these methods are certainly possible at hugely increased computational cost. I am hopeful that readers appreciate the insights possible at the current level of approximation.

Clinical significance of a presystolic wave on Doppler examination of the left ventricular outflow tract.

Science.gov (United States)

Joshi, Kamal R; Kabirdas, Deepa; Romero-Corral, Abel; Shah, Mahek; Figueredo, Vincent M; Pressman, Gregg S

2014-11-15

A presystolic wave (PSW) is commonly seen on Doppler examination of the left ventricular outflow tract (LVOT), but is little studied. We conducted a retrospective study to assess the prevalence of the PSW, correlations with various Doppler parameters, and its clinical significance. Two hundred echocardiograms, 100 with ejection fraction (EF) >55% and 100 with EF <45%, were reviewed. Mitral inflow velocities, septal annular velocities, LVOT, and PSW velocities were measured. Major adverse cardiovascular events (MACE [death, heart failure hospitalization, atrial fibrillation, and stroke]) were compared between those with and without a PSW, in both EF groups. Mean age was 58 ± 15 years; 56% were men and 69% were African-American. PSW prevalence was similar between normal (68%) and reduced EF groups (62%). However, its velocity was less in the low EF group (37 ± 10 vs 48 ± 16 cm/s, p <0.0001). In subjects with normal EF PSW velocity correlated with mitral A velocity (rho = 0.43, p = 0.0003). In subjects with reduced EF the association with A velocity was not significant (rho = 0.22, p = 0.09), but there was a significant association with annular a' velocity (rho = 0.38, p = 0.002). Over a mean follow-up of 1.7 ± 0.3 years, 57 subjects (28%) experienced MACE. Those without a PSW had more MACE (39% vs 23%, p = 0.02); PSW absence remained predictive of MACE after adjustment for multiple variables, especially in patients with reduced EF. In conclusion, PSW is common in the LVOT. Its presence and magnitude are associated with measures of atrial contraction. Its absence is associated with increased rates of adverse events, especially in patients with low EF. Copyright © 2014 Elsevier Inc. All rights reserved.

Contrast-enhanced color Doppler ultrasound characteristics in hypervascular breast tumors: comparison with MRI

International Nuclear Information System (INIS)

Alamo, L.; Fischer, U.

2001-01-01

The aim of this study was to evaluate the accuracy of contrast-enhanced color Doppler ultrasound (CE-US) in comparison with contrast-enhanced MR imaging (CE-MRI) in the discrimination of hypervascularized breast tumors. An additional CE-US of the breast was preoperatively performed in 40 patients with a hypervascular breast lesion detected on CE-MRI. The presence of blood flow signals and the morphological characteristics of the vessels in the breast lesions were evaluated pre- and post-contrast administration, as well as the dynamic aspects of the Doppler signal, including time interval to maximum signal enhancement and persistence of the signal enhancement. Twenty-three carcinomas and 17 fibroadenomas were explored. Considering initial signal enhancement > 100 % after the administration of contrast material as a criterion suggesting malignancy, CE-MRI showed a sensitivity of 100 % and a specificity of 76.5 % in the detection of malignant breast tumors. Color Doppler signals were consistently demonstrated in all carcinomas and in 68.7 % of fibroadenomas after the administration of Levovist, with CE-US showing a sensitivity of 95.6 % and a specificity of 5.9 %. Neither the mean number of vessels per tumor, nor the location of vessels, the time to maximum increase of the Doppler signal or the persistence of signal enhancement showed significant differences between benign and malignant lesions. Additional CE-US does not increase the low specificity of MRI in patients with hypervascularized breast tumors. (orig.)

Muscle Force-Velocity Relationships Observed in Four Different Functional Tests.

Science.gov (United States)

Zivkovic, Milena Z; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan

2017-02-01

The aims of the present study were to investigate the shape and strength of the force-velocity relationships observed in different functional movement tests and explore the parameters depicting force, velocity and power producing capacities of the tested muscles. Twelve subjects were tested on maximum performance in vertical jumps, cycling, bench press throws, and bench pulls performed against different loads. Thereafter, both the averaged and maximum force and velocity variables recorded from individual trials were used for force-velocity relationship modeling. The observed individual force-velocity relationships were exceptionally strong (median correlation coefficients ranged from r = 0.930 to r = 0.995) and approximately linear independently of the test and variable type. Most of the relationship parameters observed from the averaged and maximum force and velocity variable types were strongly related in all tests (r = 0.789-0.991), except for those in vertical jumps (r = 0.485-0.930). However, the generalizability of the force-velocity relationship parameters depicting maximum force, velocity and power of the tested muscles across different tests was inconsistent and on average moderate. We concluded that the linear force-velocity relationship model based on either maximum or averaged force-velocity data could provide the outcomes depicting force, velocity and power generating capacity of the tested muscles, although such outcomes can only be partially generalized across different muscles.

Atmospheric kinematics of high velocity long period variables

International Nuclear Information System (INIS)

Willson, L.A.

1982-01-01

Radial velocities of atomic absorption lines of three long period variables, RT Cyg, Z Oph and S Car, have been analysed in order to understand velocity gradients and discontinuities in their atmospheres. Phase coverage is from five days before maximum to 73 days after maximum for RT Cyg, from 17 days before to 44 days after maximum for Z Oph, and at 9 days before maximum for S Car. On a few spectrograms double lines were seen. All spectrograms were analysed by a four-parameter regression programme to yield the dependence of the radial velocity on the excitation potential, first ionization potential, wavelength and line strength, as indicators of the depth of line formation. The data were analysed to yield the velocity discontinuity across shock waves and velocity gradients between shock waves. Near maximum light the radial velocities cannot be understood by the presence of one shock only but rather require two shocks. The lower shock becomes apparent at the longer wavelengths. Consistent parameters are obtained if these stars are fundamental mode pulsators with total masses in the range of 0.5 to 1.0 solar mass and effective radii in the range of 0.85 to 1.5 x 10 13 cm. (author)

Intraparenchymal Doppler ultrasound after proximal embolization of the splenic artery in trauma patients

International Nuclear Information System (INIS)

Dormagen, Johann B.; Gaarder, Christine; Sandvik, Leiv; Naess, Paal A.; Kloew, Nils E.

2008-01-01

We studied the changes in proximal embolization of the splenic artery to the intraparenchymal blood flow with Doppler ultrasound. Seventeen trauma patients with spleen injury OIS grade 2-5 underwent embolization of the splenic artery. Peak-systolic velocity (PSV) and end-diastolic velocity (EDV) were measured in intrasplenic arteries initially 1 day after embolization, at early follow-up after 7 days, at intermediate follow-up after 10 weeks, and at late follow-up after 10 months. Resistance index (RI), systolic/diastolic ratio (S/D ratio), acceleration (AC), and acceleration time (AT) were calculated. The results were compared to values from 17 volunteers. RI increased from 0.39 initially to 0.49 (P = 0.002) at intermediate and to 0.52 (P 2 initially to 1.89 m/s 2 at late follow-up (P = 0.01). AC at late follow-up was not different from reference group (2.33 m/s 2 ). In conclusion, Doppler ultrasound is a useful tool in the evaluation of improvable intraparenchymal blood flow over time after central splenic artery embolization. (orig.)

A High-Speed Optical Diagnostic that uses Interference Filters to Measure Doppler Shifts

International Nuclear Information System (INIS)

Paul, S.F.; Cates, C.; Mauel, M.; Maurer, D.; Navratil, G.; Shilov, M.

2004-01-01

A high-speed, non-invasive velocity diagnostic has been developed for measuring plasma rotation. The Doppler shift is determined by employing two detectors that view line emission from the identical volume of plasma. Each detector views through an interference filter having a passband that varies linearly with wavelength. One detector views the plasma through a filter whose passband has a negative slope and the second detector views through one with a positive slope. Because each channel views the same volume of plasma, the ratio of the amplitudes is not sensitive to variations in plasma emission. With suitable knowledge of the filter characteristics and the relative gain, the Doppler shift is readily obtained in real time from the ratio of two channels without needing a low throughput spectrometer. The systematic errors--arising from temperature drifts, stability, and frequency response of the detectors and amplifiers, interference filter linearity, and ability to thoroughly homogenize the light from the fiber bundle--can be characterized well enough to obtain velocity data with + or - 1 km/sec with a time resolution of 0.3 msec

Doppler and time-travel broadening in ICR plasma isotope separation

International Nuclear Information System (INIS)

Karchevskii, A.I.; Potanin, E.P.

1994-01-01

Isotopically-selective ion-cyclotron resonance (ICR) heating is one of the most promising plasma isotope separation methods. The separation degree of ICR separation in a plasma depends on the resonance heating selectivity. The selectivity is due to the isotopically-adjacent accelerated ions resonance curve overlapping and therefore, is determined by the width of the resonance curves. In the case of a collisionless plasma in an ideal homogeneous longitudinal magnetic field, the line broadening is mainly determined by Doppler and time-travel effects. These effects differ in nature, and one has some difficulties in distinguishing them when interpreting the resonance curves because both broadenings depend on ion axial velocities. We consider the simplest case: the extrenal heating alternating electric field does not depend on the axial coordinate (the wave number γ = 0). Hence, in this case the Doppler effect does not occur

Coherent Doppler Laser Radar: Technology Development and Applications

Science.gov (United States)

Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

2000-01-01

NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

Power Doppler Ultrasonography and Shear Wave Elastography as Complementary Imaging Methods for Suspected Local Breast Cancer Recurrence.

Science.gov (United States)

Jales, Rodrigo Menezes; Dória, Maira Teixeira; Serra, Kátia Piton; Miranda, Mila Meneguelli; Menossi, Carlos Alberto; Schumacher, Klaus; Sarian, Luis Otávio

2018-06-01

To prospectively investigate the diagnostic accuracy and clinical consequences of power Doppler morphologic criteria and shear wave elastography (SWE) as complementary imaging methods for evaluation of suspected local breast cancer recurrence in the ipsilateral breast or chest wall. Thirty-two breast masses with a suspicion of local breast cancer recurrence on B-mode ultrasonography underwent complementary power Doppler and SWE evaluations. Power Doppler morphologic criteria were classified as avascular, hypovascular, or hypervascular. Shear wave elastography was classified according to a 5-point scale (SWE score) and SWE maximum elasticity. Diagnostic accuracy was assessed by the sensitivity, specificity, and area under the curve. A decision curve analysis assessed clinical consequences of each method. The reference standard for diagnosis was defined as core needle or excisional biopsy. Histopathologic examinations revealed 9 (28.2%) benign and 23 (71.8%) malignant cases. Power Doppler ultrasonography (US) had sensitivity of 34.8% (95% confidence interval [CI], 6.6%-62.9%) and specificity of 45.4% (95% CI, 19.3%-71.5%). The SWE score (≥3) had sensitivity of 87.0% (95% CI, 66.4%-97.2%) and specificity of 44.4% (95% CI, 13.7%-78.8%). The SWE maximum elasticity (velocity > 6.5cm/s) had sensitivity of 87% (95% CI, 66.4%-97.2%) and specificity of 77.8% (95% CI, 40.0% to 97.2%). The areas under the curves for the SWE score and SWE maximum elasticity were 0.71 (95% CI, 0.53-0.87) and 0.82 (95% CI, 0.64-0.93), respectively (P = .32). Power Doppler US is unsuitable for discrimination between local breast cancer recurrence and fibrosis. Although the SWE score and SWE maximum elasticity can make this discrimination, the use of these methods to determine biopsy may lead to poorer clinical outcomes than the current practice of performing biopsies of all suspicious masses. © 2017 by the American Institute of Ultrasound in Medicine.

Detection of Traveling Ionospheric Disturbances by Medium Frequency Doppler Sounding Using AM Radio Transmissions

Science.gov (United States)

Chilcote, M. A.; Labelle, J. W.; Lind, F. D.; Coster, A. J.; Galkin, I. A.; Miller, E.; Weatherwax, A. T.

2013-12-01

Nighttime traveling ionosphere disturbances (TIDs) propagating in the lower F region of the ionosphere were detected from time variations in the Doppler shifts of commercial AM radio broadcast stations. Three separately deployed receivers, components of the Intercepted Signals for Ionospheric Science (ISIS) Array software radio instrumentation network, recorded signals from two radio stations during eleven nights in March-April, 2012. Combining these measurements established that variations in the frequencies of the received signals, with amplitudes up to a few tenths of a Hertz, resulted from Doppler shifts produced by the ionosphere. At times, TIDs were detected as large amplitude variations in the Doppler shift with approximately 40-minute period correlated across the array. For one study interval, 0000-0400 UT on April 13, 2012, simultaneous GPS-TEC, digisonde, and superDARN coherent backscatter radar measurements confirmed the detection of TIDs with the same period. Detection of the AM signals at widely spaced receivers allowed the phase velocity and wavelength of the TIDs to be inferred, with some limitations due to differing reflection heights for the different frequencies. These measurements will be compared to phase velocities and wavelengths determined from combining an array of GPS receivers; discrepancies due to the altitude sensitivity of the techniques or other effects will be discussed. These results demonstrate that AM radio signals can be used for detection of nighttime TIDs.

Multichannel fiber laser Doppler vibrometer studies of low momentum and hypervelocity impacts

Science.gov (United States)

Posada-Roman, Julio E.; Jackson, David A.; Cole, Mike J.; Garcia-Souto, Jose A.

2017-12-01

A multichannel optical fiber laser Doppler vibrometer was demonstrated with the capability of making simultaneous non-contact measurements of impacts at 3 different locations. Two sets of measurements were performed, firstly using small ball bearings (1 mm-5.5 mm) falling under gravity and secondly using small projectiles (1 mm) fired from an extremely high velocity light gas gun (LGG) with speeds in the range 1 km/s-8 km/s. Determination of impact damage is important for industries such as aerospace, military and rail, where the effect of an impact on the structure can result in a major structural damage. To our knowledge the research reported here demonstrates the first trials of a multichannel fiber laser Doppler vibrometer being used to detect hypervelocity impacts.

Influence of type of aortic valve prosthesis on coronary blood flow velocity.

Science.gov (United States)

Jelenc, Matija; Juvan, Katja Ažman; Medvešček, Nadja Tatjana Ružič; Geršak, Borut

2013-02-01

Severe aortic valve stenosis is associated with high resting and reduced hyperemic coronary blood flow. Coronary blood flow increases after aortic valve replacement (AVR); however, the increase depends on the type of prosthesis used. The present study investigates the influence of type of aortic valve prosthesis on coronary blood flow velocity. The blood flow velocity in the left anterior descending coronary artery (LAD) and the right coronary artery (RCA) was measured intraoperatively before and after AVR with a stentless bioprosthesis (Sorin Freedom Solo; n = 11) or a bileaflet mechanical prosthesis (St. Jude Medical Regent; n = 11). Measurements were made with an X-Plore epicardial Doppler probe (Medistim, Oslo, Norway) following induction of hyperemia with an adenosine infusion. Preoperative and postoperative echocardiography evaluations were used to assess valvular and ventricular function. Velocity time integrals (VTI) were measured from the Doppler signals and used to calculate the proportion of systolic VTI (SF), diastolic VTI (DF), and normalized systolic coronary blood flow velocities (NSF) and normalized diastolic coronary blood flow velocities (NDF). The systolic proportion of the LAD VTI increased after AVR with the St. Jude Medical Regent prosthesis, which produced higher LAD SF and NSF values than the Sorin Freedom Solo prosthesis (SF, 0.41 ± 0.09 versus 0.29 ± 0.13 [P = .04]; NSF, 0.88 ± 0.24 versus 0.55 ± 0.17 [P = .01]). No significant changes in the LAD velocity profile were noted after valve replacement with the Sorin Freedom Solo, despite a significant reduction in transvalvular gradient and an increase in the effective orifice area. AVR had no effect on the RCA flow velocity profile. The coronary flow velocity profile in the LAD was significantly influenced by the type of aortic valve prosthesis used. The differences in the LAD velocity profile probably reflect differences in valve design and the systolic transvalvular flow pattern.

Coherent Doppler lidar for automated space vehicle, rendezvous, station-keeping and capture

Science.gov (United States)

Dunkin, James A.

1991-01-01

Recent advances in eye-safe, short wavelength solid-state lasers offer real potential for the development of compact, reliable, light-weight, efficient coherent lidar. Laser diode pumping of these devices has been demonstrated, thereby eliminating the need for flash lamp pumping, which has been a major drawback to the use of these lasers in space based applications. Also these lasers now have the frequency stability required to make them useful in coherent lidar, which offers all of the advantages of non-coherent lidar, but with the additional advantage that direct determination of target velocity is possible by measurement of the Doppler shift. By combining the Doppler velocity measurement capability with the inherent high angular resolution and range accuracy of lidar it is possible to construct Doppler images of targets for target motion assessment. A coherent lidar based on a Tm,Ho:YAG 2-micrometer wavelength laser was constructed and successfully field tested on atmospheric targets in 1990. This lidar incorporated an all solid state (laser diode pumped) master oscillator, in conjunction with a flash lamp pumped slave oscillator. Solid-state laser technology is rapidly advancing, and with the advent of high efficiency, high power, semiconductor laser diodes as pump sources, all-solid-state, coherent lidars are a real possibility in the near future. MSFC currently has a feasibility demonstration effort under way which will involve component testing, and preliminary design of an all-solid-state, coherent lidar for automatic rendezvous, and capture. This two year effort, funded by the Director's Discretionary Fund is due for completion in 1992.

Recent advances in self-mixing laser-doppler velocimetry: use as an in-vivo blood flow meter

NARCIS (Netherlands)

Scalise, Lorenzo; de Mul, F.F.M.; Steenbergen, Wiendelt; Petoukhova, Anna

2000-01-01

In the present paper, recent experimental advances obtained with a laser Doppler self-mixing velocimeter are reported. The self-mixing effect in a semiconductor laser is used to realize the velocimeter. The velocity is calculated measuring the frequency peak of the frequency spectrum of the

Blood velocity estimation using ultrasound and spectral iterative adaptive approaches

DEFF Research Database (Denmark)

Gudmundson, Erik; Jakobsson, Andreas; Jensen, Jørgen Arendt

2011-01-01

-mode images are interleaved with the Doppler emissions. Furthermore, the techniques are shown, using both simplified and more realistic Field II simulations as well as in vivo data, to outperform current state-of-the-art techniques, allowing for accurate estimation of the blood velocity spectrum using only 30......This paper proposes two novel iterative data-adaptive spectral estimation techniques for blood velocity estimation using medical ultrasound scanners. The techniques make no assumption on the sampling pattern of the emissions or the depth samples, allowing for duplex mode transmissions where B...

Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

International Nuclear Information System (INIS)

Goel, Sumit; Nagendrareddy, Suma Gundareddy; Raju, Manthena Srinivasa; Krishnojirao, Dayashankara Rao Jingade; Rastogi, Rajul; Mohan, Ravi Prakash Sasankoti; Gupta, Swati

2011-01-01

To evaluate the efficacy of ultrasonography (USG) with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas) of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas). There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions

Evaluation of Cardiovascular System in Fibromyalgia Syndrome: Tissue Doppler Echocardiographic Investigation

Directory of Open Access Journals (Sweden)

Selma YAZICI

2010-05-01

Full Text Available Aim: We aim to investigate besides the cardiac structures and functions by both conventionalmethods and Tissue Doppler Echocardiography (TDE which is a new and useful method inpatients with Fibromyalgia (FM. Additionally, we evaluated QT parameters (QT maximum,QT minimum and QT dispertion with the use of electrocardiography in order to measure theautonomic dysfunction which is a possible mechanism in the pathogenesis of the disease. Methods: The study was performed on 42 patients (mean age 41 years, 38 female and 38completely healthy subjects (35 female, mean age of 42 years who were admitted to the sameclinic were collected as the control group. All the individuals were undergone a completephysical examination, electrocardiography (recordings were displayed at 50 mm/s speed andechocardiography evaluation (both conventional methods and TDE.Results: Analysis of electrocardiographic recordings revealed mildly increased mean QTdispertion in the patient group, but this difference was statistically insignificant. Analysis ofconventional echocardiographic parameters revealed similar results between the patient groupand the control cases. However, an important finding of this study is that significant diastolicdysfunction was found in the patient group which was recorded with the TDE technique. Emwave velocity and Em/Am ratios were significantly lower in patients with FM compared withcontrols (p<0.005, p<0.01, respectively. Sm and Am waves velocities were similar in bothgroups. Conclusion: In this study, significant left ventricular diastolic dysfunction which was detectedby TDE technique can partly explain several symptoms such as fatigue and dyspnea in FM. Inaddition, fully cardiac evaluation of patients with FM might be obtained supporting findingsthe autonomic dysfunction theory in fibromyalgia pathogenesis.

Optical-fiber interferometer for velocity measurements with picosecond resolution

International Nuclear Information System (INIS)

Weng Jidong; Tan Hua; Wang Xiang; Ma Yun; Hu Shaolou; Wang Xiaosong

2006-01-01

The conventional Doppler laser-interference velocimeters are made up of traditional optical elements such as lenses and mirrors and will generally restrict its applications in multipoint velocity measurements. By transfering the light from multimode optical fiber to single-mode optical fiber and using the currently available conventional telecommunications elements, the authors have constructed a velocimeter called all-fiber displacement interferometer system for any reflector. The unique interferometer system is only made up of fibers or fiber-coupled components. The viability of this technique is demonstrated by measuring the velocity of an interface moving at velocity of 2133 m/s with 50 ps time resolution. In addition, the concept of optical-fiber mode conversion would provide a way to develop various optical-fiber sensors

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 comprise...

Particle sizing experiments with the laser Doppler velocimeter: Final report

Energy Technology Data Exchange (ETDEWEB)

Giel, T.V. Jr.; Son, J.Y.

1988-06-01

Measurement techniques for in-situ simultaneous measurements of particle size distributions and particle velocities using the dual beam laser Doppler velocimeter (LV) were analytically and experimentally investigated. This investigation examined the different signal characteristics of the LV for determination of particle size and particle velocity, simultaneously. The different size related signal components were evaluated not only singularly but also as simultaneous measurements to determine which characteristic, or combination of characteristics, provided the best measure of particle size. The evaluation concentrated on the 0.5 to 5 ..mu..m particle size range, in which the LV light scattering characteristics are complex often non-monotonic functions of the particle size as well as functions of index of refraction, the laser light wavelength, laser intensity and polarization, and the location and response characteristics of the detector. Different components of the LV signal were considered, but analysis concentrated on Doppler phase, visibility and scatter-intensity because they show the greatest promise. These signals characteristics were initially defined analytically for numerous optical configurations over the 0.5 to 5 ..mu..m diameter range with 0.1 ..mu..m segmentation, for refractive index values from 1.0 to 3.0 with absorptive (imaginary) components varied form 0 to 1.0. Collector orientation and effective f/No., as well as fringe spacing, beam polarization and wavelength, were varied in this analytical evaluation. 18 refs., 42 figs., 5 tabs.

In-vivo evaluation of three ultrasound vector velocity techniques with MR angiography

DEFF Research Database (Denmark)

Hansen, Kristoffer Lindskov; Udesen, Jesper; Oddershede, Niels

2008-01-01

In conventional Doppler ultrasound (US) the blood velocity is only estimated along the US beam direction. The estimate is angle corrected assuming laminar flow parallel to the vessel boundaries. As the now in the vascular system never is purely laminar, the velocities estimated with conventional...... additionally constructed and mean differences for the three comparisons were: DB/MRA = 0.17 ml; STA/MRA = 0.07 ml; TO/MRA = 0.24 ml. The three US vector velocity techniques yield quantitative insight in to flow dynamics and can potentially give the clinician a powerful tool in cardiovascular disease assessment....

Usefulness of pulse-wave doppler tissue sampling and dobutamine stress echocardiography for identification of false positive inferior wall defects in SPECT

International Nuclear Information System (INIS)

Altinmakas, S.; Dagdeviren, B.; Turkmen, M.; Gursurer, M.; Say, B.; Tezel, T.; Ersek, B.

2000-01-01

False positive inferior wall perfusion defects restrict the accuracy of SPECT in diagnosis of coronary artery disease (CAD). Pulse-Wave Tissue Doppler (PWTD) has been recently proposed to assess regional wall motion velocities. The objectives of this study were to evaluate the presence of CAD by using PWTD during dobutamine stress echocardiography (DSE) in patients with an inferior perfusion defect detected by SPECT and compare PWTD parameters of normal cases with patients who had inferior perfusion defect and CAD. Sixty-five patients (mean age 58±8 years, 30 men) with a normal LV systolic function at rest according to echocardiographic evaluation with an inferior ischemia determined by SPECT and a control group (CG) of 34 normal cases (mean age 56±7 years, 16 men) were included in this study. All patients underwent a standard DSE (up to 40 μg/kg/min with additional atropine during sub-maximum heart rate responses). Pulse-wave Doppler tissue sampling of inferior wall was performed in the apical 2-chamber view at rest and stress. The coronary angiography was performed within 24 hours. The results were evaluated for the prediction of significant right coronary artery (RCA) and/or left circumflex coronary artery (CX) with narrowing (≥50% diameter stenosis, assessed by quantitative coronary angiography). It was observed that the peak stress mean E/A ratio was lower in patients with CAD when compared to patients without CAD (0.78±0.2 versus 1.29±0.11 p<0.0001). Also the peak stress E/A ratio of normal cases was significantly higher than patients who had CAD (1.19±0.3 versus 0.78±0.2 p<0.0001). When the cut off point for the E/A ratio was determined as 1, the sensitivity and specificity of dobutamine stress PWTD E/A were 89% and 86%, respectively. The peak stress E/A ratio was higher than 1 in all patients with a false positive perfusion defect. Systolic S velocity increase during DSE was significantly lower in patients with CAD (54%±17 versus 99%±24 p=0

Coupling Between Doppler Radar Signatures and Tornado Damage Tracks

Science.gov (United States)

Jedlovec, Gary J.; Molthan, Andrew L.; Carey, Lawrence; Carcione, Brian; Smith, Matthew; Schultz, Elise V.; Schultz, Christopher; Lafontaine, Frank

2011-01-01

On April 27, 2011, the southeastern United States was raked with several episodes of severe weather. Numerous tornadoes caused extensive damage, and tragically, the deaths of over 300 people. In Alabama alone, there were 61 confirmed tornados, 4 of them produced EF5 damage, and several were on the ground an hour or more with continuous damage tracks exceeding 80km. The use of Doppler radars covering the region provided reflectivity and velocity signatures that allowed forecasters to monitors the severe storms from beginning to end issuing hundreds of severe weather warnings throughout the day. Meteorologists from the the NWS performed extensive surveys to assess the intensity, duration, and ground track of tornadoes reported during the event. Survey activities included site visits to the affected locations, analysis of radar and satellite data, aerial surveys, and interviews with eyewitnesses. Satellite data from NASA's MODIS and ASTER instruments played a helpful role in determining the location of tornado damage paths and in the assessment. High resolution multispectral and temporal composites helped forecasters corroborate their damage assessments, determine starting and ending points for tornado touchdowns, and helped to provide forecasters with a better big-picture view of the damage region. The imagery also helped to separate damage from the April 27th tornados from severe weather that occurred earlier that month. In a post analysis of the outbreak, tornado damage path signatures observed in the NASA satellite data have been correlated to "debris ball" signatures in the NWS Doppler radars and a special ARMOR dual-polarization radar operated by the University of Alabama Huntsville during the event. The Doppler radar data indicates a circular enhanced reflectivity signal and rotational couplet in the radial velocity likely associated with the tornado that is spatially correlated with the damage tracks in the observed satellite data. An algorithm to detect and

Active control of passive acoustic fields: passive synthetic aperture/Doppler beamforming with data from an autonomous vehicle.

Science.gov (United States)

D'Spain, Gerald L; Terrill, Eric; Chadwell, C David; Smith, Jerome A; Lynch, Stephen D

2006-12-01

The maneuverability of autonomous underwater vehicles (AUVs) equipped with hull-mounted arrays provides the opportunity to actively modify received acoustic fields to optimize extraction of information. This paper uses ocean acoustic data collected by an AUV-mounted two-dimensional hydrophone array, with overall dimension one-tenth wavelength at 200-500 Hz, to demonstrate aspects of this control through vehicle motion. Source localization is performed using Doppler shifts measured at a set of receiver velocities by both single elements and a physical array. Results show that a source in the presence of a 10-dB higher-level interferer having exactly the same frequency content (as measured by a stationary receiver) is properly localized and that white-noise-constrained adaptive beamforming applied to the physical aperture data in combination with Doppler beamforming provides greater spatial resolution than physical-aperture-alone beamforming and significantly lower sidelobes than single element Doppler beamforming. A new broadband beamformer that adjusts for variations in vehicle velocity on a sample by sample basis is demonstrated with data collected during a high-acceleration maneuver. The importance of including the cost of energy expenditure in determining optimal vehicle motion is demonstrated through simulation, further illustrating how the vehicle characteristics are an integral part of the signal/array processing structure.

Spectral Doppler findings in a rare case of acute compartment syndrome following leg burn

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Omer A. Mahmoud

2018-04-01

Full Text Available Acute compartment syndrome (ACS is an orthopedic emergency condition, which is rarely attributed to burns. It occurs when pressure in an enclosed space rises to a point where it reduces blood flow and impairs tissue perfusion. Its consequences often lead to ischemia and possible necrosis within that space. Until now, the use of Doppler assessment to explore different types of compartment syndrome has yielded contradictory findings. Here, we present a significant increase of blood flow velocity in the arteries proximal to the burned area. Thus, the combination of Duplex ultrasound results with clinical findings will help vascular surgeons to make immediate decision to perform fasciotomy. Keywords: Compartment syndrome, Spectral Doppler

Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

Science.gov (United States)

Goel, Sumit; Nagendrareddy, Suma Gundareddy; Raju, Manthena Srinivasa; Krishnojirao, Dayashankara Rao Jingade; Rastogi, Rajul; Mohan, Ravi Prakash Sasankoti; Gupta, Swati

2011-01-01

Aim: To evaluate the efficacy of ultrasonography (USG) with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Materials and Methods: Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. Results: USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas) of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas). There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. Conclusions: USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions. PMID:22223940

Ultrasonography with color Doppler and power Doppler in the diagnosis of periapical lesions

Directory of Open Access Journals (Sweden)

Sumit Goel

2011-01-01

Full Text Available Aim: To evaluate the efficacy of ultrasonography (USG with color Doppler and power Doppler applications over conventional radiography in the diagnosis of periapical lesions. Materials and Methods: Thirty patients having inflammatory periapical lesions of the maxillary or mandibular anterior teeth and requiring endodontic surgery were selected for inclusion in this study. All patients consented to participate in the study. We used conventional periapical radiographs as well as USG with color Doppler and power Doppler for the diagnosis of these lesions. Their diagnostic performances were compared against histopathologic examination. All data were compared and statistically analyzed. Results: USG examination with color Doppler and power Doppler identified 29 (19 cysts and 10 granulomas of 30 periapical lesions accurately, with a sensitivity of 100% for cysts and 90.91% for granulomas and a specificity of 90.91% for cysts and 100% for granulomas. In comparison, conventional intraoral radiography identified only 21 lesions (sensitivity of 78.9% for cysts and 45.4% for granulomas and specificity of 45.4% for cysts and 78.9% for granulomas. There was definite correlation between the echotexture of the lesions and the histopathological features except in one case. Conclusions: USG imaging with color Doppler and power Doppler is superior to conventional intraoral radiographic methods for diagnosing the nature of periapical lesions in the anterior jaws. This study reveals the potential of USG examination in the study of other jaw lesions.

Sc- and Si-associated ULF and HF-doppler oscillations during the great magnetic storm of february 1986

International Nuclear Information System (INIS)

Yumoto, K.; Watanabe, T.; Takahashi, K.; Ogawa, T.

1989-01-01

Sc- and si-associated ionospheric Doppler velocity oscillations and geomagnetic pulsations observed during the great geomagnetic storm of February 1986 can be explained by the 'dynamo-motor' mechanism of ionospheric electric fields and by global compressional oscillations in the magnetosphere and ionosphere, respectively. (author)

Angle-corrected imaging transcranial doppler sonography versus imaging and nonimaging transcranial doppler sonography in children with sickle cell disease.

Science.gov (United States)

Krejza, J; Rudzinski, W; Pawlak, M A; Tomaszewski, M; Ichord, R; Kwiatkowski, J; Gor, D; Melhem, E R

2007-09-01

Nonimaging transcranial Doppler sonography (TCD) and imaging TCD (TCDI) are used for determination of the risk of stroke in children with sickle cell disease (SCD). The purpose was to compare angle-corrected, uncorrected TCDI, and TCD blood flow velocities in children with SCD. A total of 37 children (mean age, 7.8 +/- 3.0 years) without intracranial arterial narrowing determined with MR angiography, were studied with use of TCD and TCDI at the same session. Depth of insonation and TCDI mean velocities with and without correction for the angle of insonation in the terminal internal carotid artery (ICA) and middle (MCA), anterior (ACA), and posterior (PCA) cerebral arteries were compared with TCD velocities with use of a paired t test. Two arteries were not found on TCDI compared with 15 not found on TCD. Average angle of insonation in the MCA, ACA, ICA, and PCA was 31 degrees , 44 degrees , 25 degrees , and 29 degrees , respectively. TCDI and TCD mean depth of insonation for all arteries did not differ significantly; however, individual differences varied substantially. TCDI velocities were significantly lower than TCD velocities, respectively, for the right and left sides (mean +/- SD): MCA, 106 +/- 22 cm/s and 111 +/- 33 cm/s versus 130 +/- 19 cm/s and 134 +/- 26 cm/s; ICA, 90 +/- 14 cm/s and 98 +/- 27 cm/s versus 117 +/- 18 cm/s and 119 +/- 23 cm/s; ACA, 74 +/- 24 cm/s and 88 +/- 25 cm/s versus 105 +/- 23 cm/s and 105 +/- 31 cm/s; and PCA, 84 +/- 27 cm/s and 82 +/- 21 cm/s versus 95 +/- 23 cm/s and 94 +/- 20 cm/s. TCD and angle-corrected TCDI velocities were not statistically different except for higher angle-corrected TCDI values in the left ACA and right PCA. TCD velocities are significantly higher than TCDI velocities but are not different from the angle-corrected TCDI velocities. TCDI identifies the major intracranial arteries more effectively than TCD.

On the apparent velocity of integrated sunlight. 2: 1983-1992 and comparisons with magnetograms

Science.gov (United States)

Deming, Drake; Plymate, Claude

1994-01-01

We report additional results in our program to monitor the wavelength stability of lines in the 2.3 micrometer spectrum of integrated sunlight. We use the McMath Fourier transform spectrometer (FTS) of the National Solar Observatory to monitor 16 delta V = 2 lines of (12)C(16)O, as well as five atomic lines. Wavenumber calibration is achieved using a low-pressure N2O absorption cell and checked against terrestrial atmospheric lines. Imperfect optical integration of the solar disk remains the principal source of error, but this error has been reduced by improved FTS/telescope collimation and observing procedures. The present results include data from an additional 13 quarterly observing runs since 1985. We continue to find that the apparent velocity of integrated sunlight is variable, in the sense of having a greater reshift at solar maximum. This is supported by the temporal dependence of the integrated light velocity, and by the presence of a correlation between velocity and the disk-averaged magnetic flux derived from Kitt Peak magnetograms. The indicated peak-to-peak apparent velocity amplitude over a solar cycle is approximately the same as the velocity amplitude of the Sun's motion about the solar system barycenter. This represents about half the amplitude which we inferred in Paper I (Deming et al. 1987), but the present result has a much greater statistical significance. Our results have implications for those investigations which search for the Doppler signatures of planetary-mass companions to solar-type stars. We contrast our results to the recent finding by McMillan et al. 1993 that solar absorption lines in the violet spectral region are wavelength-stable over the solar cycle.

Influence of caffeine and caffeine withdrawal on headache and cerebral blood flow velocities

NARCIS (Netherlands)

Couturier, EGM; Laman, DM; vanDuijn, MAJ; vanDuijn, H

Caffeine consumption may cause headache, particularly migraine. Its withdrawal also produces headaches and may be related to weekend migraine attacks. Transcranial Doppler sonography (TCD) has shown changes in cerebral blood flow velocities (BFV) during and between attacks of migraine. In order to

Analysis of Detectors and Transmission Curve Correction of Mobile Rayleigh Doppler Wind Lidar

International Nuclear Information System (INIS)

Tang Lei; Shu Zhi-Feng; Dong Ji-Hui; Wang Guo-Cheng; Xu Wen-Jing; Hu Dong-Dong; Wang Yong-Tao; Chen Ting-Di; Dou Xian-Kang; Sun Dong-Song; Cha Hyunki

2010-01-01

A mobile molecular Doppler wind lidar (DWL) based on double-edge technique is presented for wind measurement at altitudes from 10km to 40km. A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity. The lidar operates at 355 nm with a 45-cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing. In order to guarantee the wind accuracy, different forms of calibration function of detectors in different count rates response range would be especially valuable. The accuracy of wind velocity iteration is improved greatly because of application of the calibration function of linearity at the ultra low light intensity especially at altitudes from 10km to 40km. The calibration functions of nonlinearity make the transmission of edge channel 1 and edge channel 2 increase 38.9% and 27.7% at about 1 M count rates, respectively. The dynamic range of wind field measurement may also be extended because of consideration of the response function of detectors in their all possible operating range. (fundamental areas of phenomenology(including applications))

Right Ventricular Doppler Echocardiographic Study of Indeterminate Form of Chagas Disease

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Rogério Gomes Furtado

2015-03-01

Full Text Available Background: Patients with indeterminate form of Chagas disease/cardiac normality (ICD/CN exhibited normal electrocardiograms and chest X-rays; however, more sophisticated tests detected some degree of morphological and functional changes in the heart. Objective: To assess the prevalence of systolic and diastolic dysfunction of the right ventricle (RV in patients with ICD/CN. Methods: This was a case–control and prevalence study. Using Doppler two-dimensional echocardiography (2D, 92 patients were assessed and divided into two groups: group I (normal, n = 31 and group II (ICD/CN, n = 61. Results: The prevalence of RV systolic dysfunction in patients in groups I and II was as follows: fractional area change (0.0% versus 0.6%, mobility of the tricuspid annulus (0.0% versus 0.0%, and S-wave tissue Doppler (6.4% versus 26.0%, p = 0.016. The prevalence of global disorders such as the right myocardial performance index using tissue Doppler (16.1% versus 27.8%, p = 0.099 and pulsed Doppler (61.3% versus 68%, p = 0.141 and diastolic disorders such as abnormal relaxation (0.0% versus 6.0%, pseudonormal pattern (0.0% versus 0.0%, and restrictive pattern (0.0% versus 0.0% was not statistically different between groups. Conclusion: The prevalence of RV systolic dysfunction was estimated to be 26% (S wave velocity compared with other variables, suggesting incipient changes in RV systolic function in the ICD/CN group.

Comparison of power Doppler and color Doppler ultrasonography in the detection of intrasticular blood flow of normal infants

International Nuclear Information System (INIS)

Shin, Sung Ran; Lee, Ho Kyoung; Lee, Won Gyun; Youk, Dong Joon; Rho, Taek Soo; Lee, Min Jin; Lee, Sang Chun

1999-01-01

To compare color Doppler ultrasonography (US) and power Doppler US in the detection of intratesticular blood flow in normal infants and to asses the symmetry of blood flow. Testicular blood flow was assessed prospectively in 100 testes of 50 infants with both power and color Doppler US. We compared the power Doppler with color Doppler to detect intratesticular blood. When the flow was detected, intratesticular blood flow was graded as follows: grade 1: single intratesticular Doppler signal ; grade 2: multiple intratesticular Doppler signals. The symmetry of intratesticular flow was assessed by using the same method. Intratesticular flow was detected in 72 (72%) and 68 (68%) testes on power and color Doppler US, respectively. In 76 testes (76%), intratesticular flow was detected in either one or both techniques. On power Doppler US, grade 1 was seen in 40 tests and grade 2 in 32 testes. On color Doppler US, grade 1 was noted in 52 testes and grade 2 in 16 testes. Testicular blood flow was symmetric on both power and color Doppler US in each patient. There was no difference between power Doppler and color Doppler ultrasonography in detecting intratesticular blood flow in normal infants.

Determination of strength exercise intensities based on the load-power-velocity relationship.

Science.gov (United States)

Jandačka, Daniel; Beremlijski, Petr

2011-06-01

The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s(-1)) to maximal velocity (m•s(-1)). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.

Velocity slip and translational nonequilibrium of ternary gas mixtures in free jet expansions

International Nuclear Information System (INIS)

Cattolica, R.J.; Gallagher, R.J.; Anderson, J.B.; Talbot, L.

1977-05-01

An aerodynamic isotope separation technique based on the velocity slip between gases in a rarefied flow has been proposed. To evaluate the efficiency of this separation technique, the velocity and translational temperature of the individual species in binary and ternary gas mixtures of argon and neon in helium have been studied in a low density hypersonic free jet. The velocity and temperature of the gas were determined from the Doppler shift and broadening of the fluorescence excited by an electron beam. Velocity slip and translational nonequilibrium were observed over a range of source pressures. A separation factor based on the velocity slip and temperatures was also determined. A comparison of the velocity slip, temperatures, and separation factor with the results of a Monte Carlo simulation of the flow field is presented

Gallblader varices in children with portal cavernoma: duplex-Doppler and color Doppler ultrasound studies

International Nuclear Information System (INIS)

Muro, D.; Sanguesa, C.; Lopez, A.

1998-01-01

To determine the prevalence of varices in the gallbladder wall, observed by duplex-Doppler and color Doppler ultrasound, in children with cavernoma of the portal vein. Nineteen patients with portal hypertension were studied prospectively by duplex-Doppler and color Doppler ultrasound: 12 of the patients had developed a cavernoma of the portal vein. The presence of peri vesicular varices was assessed in the group of patients with portal cavernoma. Duplex-Doppler and color Doppler ultrasound disclosed the presence of varices in gallbladder wall in nine of the 12 patients (75%). The varices appeared as anechoic and serpiginous areas, and Doppler ultrasound revealed slowed venous flow. However, the three patients in whom gallbldder varices were not detected presented collateral gastric ciculation and spontaneous splenorenal shunt. Gallbladder varices are common in children with portal vein cavernoma; they present hepatopetal flow. Their developments is not related to the size of the portal cavernoma, the presence of spontaneous portosystemic shunts, or endoscopic obliteration of gastric and esophageal varices. The detection of gallbladder varices in patients with portal hypertension who are to undergo biliary surgery is highly important for the surgeon, helping to avoid perioperative complications. (Author) 15 refs

Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun

International Nuclear Information System (INIS)

Khlystova, Anna; Toriumi, Shin

2017-01-01

We study the plasma flows in the solar photosphere during the emergence of two small active regions, NOAA 9021 and 10768. Using Solar and Heliospheric Observatory /Michelson Doppler Imager data, we find that the strong plasma upflows appear at the initial stage of active region formation, with maximum upflow velocities of −1650 and −1320 m s −1 . The structures with enhanced upflows have size ∼8 Mm in diameter, and they exist for 1–2 hr. The parameters of the enhanced upflows are consistent with those of the large active region NOAA 10488, which may suggest the possibility that the elementary emerging magnetic loops that appear at the earliest phase of active region formation have similar properties, irrespective of scales of active regions. Comparison between the observations and a numerical simulation of magnetic flux emergence shows a striking consistency. We find that the driving force of the plasma upflow is at first the gas pressure gradient and later the magnetic pressure gradient.

Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun

Energy Technology Data Exchange (ETDEWEB)

Khlystova, Anna [Institute of Solar-Terrestrial Physics SB RAS, Lermontov St., 126a, 664033 Irkutsk (Russian Federation); Toriumi, Shin, E-mail: hlystova@iszf.irk.ru, E-mail: shin.toriumi@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2017-04-10

We study the plasma flows in the solar photosphere during the emergence of two small active regions, NOAA 9021 and 10768. Using Solar and Heliospheric Observatory /Michelson Doppler Imager data, we find that the strong plasma upflows appear at the initial stage of active region formation, with maximum upflow velocities of −1650 and −1320 m s{sup −1}. The structures with enhanced upflows have size ∼8 Mm in diameter, and they exist for 1–2 hr. The parameters of the enhanced upflows are consistent with those of the large active region NOAA 10488, which may suggest the possibility that the elementary emerging magnetic loops that appear at the earliest phase of active region formation have similar properties, irrespective of scales of active regions. Comparison between the observations and a numerical simulation of magnetic flux emergence shows a striking consistency. We find that the driving force of the plasma upflow is at first the gas pressure gradient and later the magnetic pressure gradient.

Volumetric velocity measurements in restricted geometries using spiral sampling: a phantom study.

Science.gov (United States)

Nilsson, Anders; Revstedt, Johan; Heiberg, Einar; Ståhlberg, Freddy; Bloch, Karin Markenroth

2015-04-01

The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. In a phantom model, maximum velocity, flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging (MRI) with velocity encoding in one (extending on current clinical practice) and three directions (for characterization of the flow field) using spiral readouts. Results of maximum velocity and pressure drop were compared to computational fluid dynamics (CFD) simulations, as well as corresponding low-echo-time (TE) Cartesian data. Flow was compared to 2D through-plane phase contrast (PC) upstream from the restriction. Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD (spiral sequences were respectively 14 and 13 % overestimated compared to CFD. Identification of the maximum velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.

Augmented Reality Based Doppler Lidar Data Visualization: Promises and Challenges

OpenAIRE

Cherukuru N. W.; Calhoun R.

2016-01-01

Augmented reality (AR) is a technology in which the enables the user to view virtual content as if it existed in real world. We are exploring the possibility of using this technology to view radial velocities or processed wind vectors from a Doppler wind lidar, thus giving the user an ability to see the wind in a literal sense. This approach could find possible applications in aviation safety, atmospheric data visualization as well as in weather education and public outreach. As a proof of...

An ML-Based Radial Velocity Estimation Algorithm for Moving Targets in Spaceborne High-Resolution and Wide-Swath SAR Systems

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Tingting Jin

2017-04-01

Full Text Available Multichannel synthetic aperture radar (SAR is a significant breakthrough to the inherent limitation between high-resolution and wide-swath (HRWS compared with conventional SAR. Moving target indication (MTI is an important application of spaceborne HRWS SAR systems. In contrast to previous studies of SAR MTI, the HRWS SAR mainly faces the problem of under-sampled data of each channel, causing single-channel imaging and processing to be infeasible. In this study, the estimation of velocity is equivalent to the estimation of the cone angle according to their relationship. The maximum likelihood (ML based algorithm is proposed to estimate the radial velocity in the existence of Doppler ambiguities. After that, the signal reconstruction and compensation for the phase offset caused by radial velocity are processed for a moving target. Finally, the traditional imaging algorithm is applied to obtain a focused moving target image. Experiments are conducted to evaluate the accuracy and effectiveness of the estimator under different signal-to-noise ratios (SNR. Furthermore, the performance is analyzed with respect to the motion ship that experiences interference due to different distributions of sea clutter. The results verify that the proposed algorithm is accurate and efficient with low computational complexity. This paper aims at providing a solution to the velocity estimation problem in the future HRWS SAR systems with multiple receive channels.

Direct measurement of Lorentz transformation with Doppler effects

Science.gov (United States)

Chen, Shao-Guang

For space science and astronomy the fundamentality of one-way velocity of light (OWVL) is selfevident. The measurement of OWVL (distance/interval) and the clock synchronization with light-signal transfer make a logical circulation. This means that OWVL could not be directly measured but only come indirectly from astronomical method (Romer's Io eclipse and Bradley's sidereal aberration), furthermore, the light-year by definitional OWVL and the trigonometry distance with AU are also un-measurable. For to solve this problem two methods of clock synchronization were proposed: The direct method is that at one end of dual-speed transmissionline with single clock measure the arriving-time difference of longitudinal wave and transverse wave or ordinary light and extraordinary light, again to calculate the collective sending-time of two wave with Yang's /shear elastic-modulus ratio (E/k) or extraordinary/ordinary light refractive-index ratio (ne/no), which work as one earthquake-station with single clock measures first-shake time and the distance to epicenter; The indirect method is that the one-way wavelength l is measured by dual-counters Ca and Cb and computer's real-time operation of reading difference (Nb - Na) of two counters, the frequency f is also simultaneously measured, then l f is just OWVL. Therefore, with classical Newtonian mechanics and ether wave optics, OWVL can be measured in the Galileo coordinate system with an isotropic length unit (1889 international meter definition). Without any hypotheses special relativity can entirely establish on the metrical results. When a certain wavelength l is defined as length unit, foregoing measurement of one-way wavelength l will become as the measurement of rod's length. Let a rigidity-rod connecting Ca and Cb moves relative to lamp-house with velocity v, rod's length L = (Nb - Na) l will change follow v by known Doppler effect, i.e., L(q) =L0 (1+ (v/c) cos q), where L0 is the proper length when v= 0, v• r = v cos q

Translation compensation and micro-Doppler extraction for precession ballistic targets with a wideband terahertz radar

Science.gov (United States)

Yang, Qi; Deng, Bin; Wang, Hongqiang; Zhang, Ye; Qin, Yuliang

2018-01-01

Imaging, classification, and recognition techniques of ballistic targets in midcourse have always been the focus of research in the radar field for military applications. However, the high velocity translation of ballistic targets will subject range profile and Doppler to translation, slope, and fold, which are especially severe in the terahertz region. Therefore, a two-step translation compensation method based on envelope alignment is presented. The rough compensation is based on the traditional envelope alignment algorithm in inverse synthetic aperture radar imaging, and the fine compensation is supported by distance fitting. Then, a wideband imaging radar system with a carrier frequency of 0.32 THz is introduced, and an experiment on a precession missile model is carried out. After translation compensation with the method proposed in this paper, the range profile and the micro-Doppler distributions unaffected by translation are obtained, providing an important foundation for the high-resolution imaging and micro-Doppler extraction of the terahertz radar.

Gas and particle velocity measurements in an induction plasma

International Nuclear Information System (INIS)

Lesinski, J.; Gagne, R.; Boulos, M.I.

1981-08-01

Laser doppler anemometry was used for the measurements of the plasma and particle velocity profiles in the coil region of an inductively coupled plasma. Results are reported for a 50 mm ID induction torch operated at atmospheric pressure with argon as the plasma gas. The oscillator frequency was 3 MHz and the power in the coil was varied between 4.6 and 10.5 kW. The gas velocity measurements were made using a fine carbon powder as a tracer (dp approx. = 1 μm). Measurements were also made with larger silicon particles (dp = 33 μm and sigma = 13 μm) centrally injected in the plasma under different operating conditions

Sheep as a large animal ear model: Middle-ear ossicular velocities and intracochlear sound pressure.

Science.gov (United States)

Péus, Dominik; Dobrev, Ivo; Prochazka, Lukas; Thoele, Konrad; Dalbert, Adrian; Boss, Andreas; Newcomb, Nicolas; Probst, Rudolf; Röösli, Christof; Sim, Jae Hoon; Huber, Alexander; Pfiffner, Flurin

2017-08-01

Animals are frequently used for the development and testing of new hearing devices. Dimensions of the middle ear and cochlea differ significantly between humans and commonly used animals, such as rodents or cats. The sheep cochlea is anatomically more like the human cochlea in size and number of turns. This study investigated the middle-ear ossicular velocities and intracochlear sound pressure (ICSP) in sheep temporal bones, with the aim of characterizing the sheep as an experimental model for implantable hearing devices. Measurements were made on fresh sheep temporal bones. Velocity responses of the middle ear ossicles at the umbo, long process of the incus and stapes footplate were measured in the frequency range of 0.25-8 kHz using a laser Doppler vibrometer system. Results were normalized by the corresponding sound pressure level in the external ear canal (P EC ). Sequentially, ICSPs at the scala vestibuli and tympani were then recorded with custom MEMS-based hydrophones, while presenting identical acoustic stimuli. The sheep middle ear transmitted most effectively around 4.8 kHz, with a maximum stapes velocity of 0.2 mm/s/Pa. At the same frequency, the ICSP measurements in the scala vestibuli and tympani showed the maximum gain relative to the P EC (24 dB and 5 dB, respectively). The greatest pressure difference across the cochlear partition occurred between 4 and 6 kHz. A comparison between the results of this study and human reference data showed middle-ear resonance and best cochlear sensitivity at higher frequencies in sheep. In summary, sheep can be an appropriate large animal model for research and development of implantable hearing devices. Copyright © 2017 Elsevier B.V. All rights reserved.

High-frequency dual mode pulsed wave Doppler imaging for monitoring the functional regeneration of adult zebrafish hearts

Science.gov (United States)

Kang, Bong Jin; Park, Jinhyoung; Kim, Jieun; Kim, Hyung Ham; Lee, Changyang; Hwang, Jae Youn; Lien, Ching-Ling; Shung, K. Kirk

2015-01-01

Adult zebrafish is a well-known small animal model for studying heart regeneration. Although the regeneration of scars made by resecting the ventricular apex has been visualized with histological methods, there is no adequate imaging tool for tracking the functional recovery of the damaged heart. For this reason, high-frequency Doppler echocardiography using dual mode pulsed wave Doppler, which provides both tissue Doppler (TD) and Doppler flow in a same cardiac cycle, is developed with a 30 MHz high-frequency array ultrasound imaging system. Phantom studies show that the Doppler flow mode of the dual mode is capable of measuring the flow velocity from 0.1 to 15 cm s−1 with high accuracy (p-value = 0.974 > 0.05). In the in vivo study of zebrafish, both TD and Doppler flow signals were simultaneously obtained from the zebrafish heart for the first time, and the synchronized valve motions with the blood flow signals were identified. In the longitudinal study on the zebrafish heart regeneration, the parameters for diagnosing the diastolic dysfunction, for example, E/Em < 10, E/A < 0.14 for wild-type zebrafish, were measured, and the type of diastolic dysfunction caused by the amputation was found to be similar to the restrictive filling. The diastolic function was fully recovered within four weeks post-amputation. PMID:25505135

Quantitative measurement of portal blood flow by magnetic resonance phase contrast. Comparative study of flow phantom and Doppler ultrasound in vivo

International Nuclear Information System (INIS)

Tsunoda, Masatoshi; Kimoto, Shin; Hamazaki, Keisuke; Takeda, Yoshihiro; Hiraki, Yoshio.

1994-01-01

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flow-metry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow. (author)

Line-of-Sight Velocity As a Tracer of Coronal Cavity Magnetic Structure

International Nuclear Information System (INIS)

Bąk-Stȩślicka, Urszula; Gibson, Sarah E.; Chmielewska, Ewa

2016-01-01

We present a statistical analysis of 66 days of observations of quiescent (non-erupting) coronal cavities and associated velocity and thermal structures. We find that nested rings of LOS-oriented velocity are common in occurrence and spatially well correlated with cavities observed in emission. We find that the majority of cavities possess multiple rings, and a range in velocity on the order of several km∕sec. We find that the tops of prominences lie systematically below the cavity center and location of largest Doppler velocity. Finally, we use DEM analysis to consider the temperature structure of two cavities in relation to cavity, prominence, and flows. These observations yield new constraints on the magnetic structure of cavities, and on the conditions leading up to solar eruptions.

Detection of Fast Moving and Accelerating Targets Compensating Range and Doppler Migration

Science.gov (United States)

2014-06-01

TR–2978 UNCLASSIFIED the chirp bandwidth is changed from pulse to pulse to realise the range migration com- pensation. Also, Dai et. al. [11] proposed...injected at different closing velocities and acceleration values . Figure 1(a) shows the range-Doppler map of a non-accelarating target moving at 100 knots...increase the noise floor. Hence, consideration must be given to establish a criteria for the combination processing to achieve a net SNR improvement for a

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.

Avaliação dos tumores hepáticos ao Doppler Doppler evaluation of liver tumors

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Márcio Martins Machado

2004-10-01

Full Text Available Os avanços recentes na ultra-sonografia têm ampliado a possibilidade de detecção de tumores hepáticos. Isto tem auxiliado na perspectiva de melhora do prognóstico destes pacientes, à medida que novas técnicas terapêuticas têm surgido. Neste artigo os autores relatam achados ao Doppler que podem auxiliar na identificação e caracterização dos tumores hepáticos, avaliando dados do Doppler colorido, pulsado e do Doppler de amplitude ("power Doppler". Fazem, também, referência a novas modalidades de imagem, como o uso da harmônica.Recent advances in ultrasound have optimized the detection of liver tumors and helped to improve the prognosis of patients with this condition as newly developed and improved therapeutic modalities have been established. The authors review important Doppler findings which may help in the identification and characterization of some hepatic tumors through the evaluation of color Doppler, pulsed Doppler and power Doppler features. New imaging methods such as the use of harmonics imaging are also reviewed.

The mechanism of mid-latitude Pi2 waves in the upper ionosphere as revealed by combined Doppler and magnetometer observations

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V. A. Pilipenko

2013-04-01

Full Text Available The interpretation of simultaneous ionospheric Doppler sounding and ground magnetometer observations of low-latitude Pi2 waves is revised. We compare the theoretical estimates of the ionospheric Doppler velocity for the same amplitude of the ground magnetic disturbances produced by a large-scale compressional mode and an Alfvén mode. The plasma vertical displacement caused by the wave electric field is shown to be the dominating effect. Taking into account the correction of the previous paper, the observations of low-latitude Pi2 in the F layer ionosphere by Doppler sounding and SuperDARN (Super Dual Auroral Radar Network radars give consistent results. We suggest that the Doppler response to Pi2 waves is produced by the Alfvén wave component, but not the fast-mode component, whereas the ground magnetic signal is composed from both Alfvén and fast magnetosonic modes.

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.

Application of photon Doppler velocimetry to direct impact Hopkinson pressure bars

Energy Technology Data Exchange (ETDEWEB)

Lea, Lewis J., E-mail: ll379@cam.ac.uk; Jardine, Andrew P. [SMF Fracture and Shock Physics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2016-02-15

Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion, and faster achievement of force equilibrium. Currently, these advantages are gained at the expense of all information about the striker impacted specimen face, preventing the experimental determination of force equilibrium, and requiring approximations to be made on the sample deformation history. In this paper, we discuss an experimental method and complementary data analysis for using photon Doppler velocimetry to measure surface velocities of the striker and output bars in a direct impact bar experiment, allowing similar data to be recorded as in a split bar system. We discuss extracting velocity and force measurements, and the precision of measurements. Results obtained using the technique are compared to equivalent split bar tests, showing improved stress measurements for the lowest and highest strains in fully dense metals, and improvement for all strains in slow and non-equilibrating materials.

Age-related decline in mitral peak diastolic velocities is unaffected in well-trained runners

DEFF Research Database (Denmark)

Olsen, Rasmus Huan; Couppé, Christian; Dall, Christian Have

2015-01-01

(a') diastolic and systolic (s') annular longitudinal tissue Doppler velocities were measured by echocardiography during four stages (rest, supine bike exercise at 30% and 60% of maximal workload, and recovery). RESULTS: The athletes had marked cardiac remodeling, while overall differences in mitral...

Bubble-Induced Color Doppler Feedback for Histotripsy Tissue Fractionation.

Science.gov (United States)

Miller, Ryan M; Zhang, Xi; Maxwell, Adam D; Cain, Charles A; Xu, Zhen

2016-03-01

Histotripsy therapy produces cavitating bubble clouds to increasingly fractionate and eventually liquefy tissue using high-intensity ultrasound pulses. Following cavitation generated by each pulse, coherent motion of the cavitation residual nuclei can be detected using metrics formed from ultrasound color Doppler acquisitions. In this paper, three experiments were performed to investigate the characteristics of this motion as real-time feedback on histotripsy tissue fractionation. In the first experiment, bubble-induced color Doppler (BCD) and particle image velocimetry (PIV) analysis monitored the residual cavitation nuclei in the treatment region in an agarose tissue phantom treated with two-cycle histotripsy pulses at [Formula: see text] using a 500-kHz transducer. Both BCD and PIV results showed brief chaotic motion of the residual nuclei followed by coherent motion first moving away from the transducer and then rebounding back. Velocity measurements from both PIV and BCD agreed well, showing a monotonic increase in rebound time up to a saturation point for increased therapy dose. In a second experiment, a thin layer of red blood cells (RBC) was added to the phantom to allow quantification of the fractionation of the RBC layer to compare with BCD metrics. A strong linear correlation was observed between the fractionation level and the time to BCD peak rebound velocity over histotripsy treatment. Finally, the correlation between BCD feedback and histotripsy tissue fractionation was validated in ex vivo porcine liver evaluated histologically. BCD metrics showed strong linear correlation with fractionation progression, suggesting that BCD provides useful quantitative real-time feedback on histotripsy treatment progression.

Updraft and downdraft characterization with Doppler lidar: cloud-free versus cumuli-topped mixed layer

Directory of Open Access Journals (Sweden)

A. Ansmann

2010-08-01

Full Text Available For the first time, a comprehensive, height-resolved Doppler lidar study of updrafts and downdrafts in the mixing layer is presented. The Doppler lidar measurements were performed at Leipzig, Germany, in the summer half year of 2006. The conditional sampling method is applied to the measured vertical velocities to identify, count, and analyze significant updraft and downdraft events. Three cases of atmospheric boundary-layer (ABL evolution with and without fair-weather cumuli formation are discussed. Updrafts occur with an average frequency of 1–2 per unit length z_i (boundary-layer depth z_i, downdrafts 20–30% more frequently. In the case with cumuli formation, the draft occurrence frequency is enhanced by about 50% at cloud level or near cloud base. The counted updraft events cover 30–34%, downdrafts 53–57% of the velocity time series in the central part of the ABL (subcloud layer during the main period of convective activity. By considering all drafts with horizontal extent >36 m in the analysis, the updraft mean horizontal extent ranges here from 200–420 m and is about 0.16 z_i–0.18 z_i in all three cases disregarding the occurrence of cumulus clouds. Downdraft extents are a factor of 1.3–1.5 larger. The average value of the updraft mean vertical velocities is 0.5–0.7 m/s or 0.40 w_*–0.45 w_* (convective velocity scale w_*, and the negative downdraft mean vertical velocities are weaker by roughly 10–20%. The analysis of the relationship between the size (horizontal extent of the updrafts and downdrafts and their mean vertical velocity reveals a pronounced increase of the average vertical velocity in updrafts from 0.4–0.5 m/s for small thermals (100–200 m to about 1.5 m/s for large updrafts (>600 m in the subcloud layer in the case with fair-weather cumuli. At cloudless conditions, the updraft

The Cognitive Doppler.

Science.gov (United States)

Kozoil, Micah E.

1989-01-01

Discusses the learning needs of students in the concrete operational stage in mathematics. Identifies the phenomenon of reduced cognitive performance in an out-of-class environment as the "Cognitive Doppler." Suggests methods of reducing the pronounced effects of the Cognitive Doppler by capitalizing on the students' ability to memorize…

Doppler ultrasound exam of an arm or leg

Science.gov (United States)

Peripheral vascular disease - Doppler; PVD - Doppler; PAD - Doppler; Blockage of leg arteries - Doppler; Intermittent claudication - Doppler; Arterial insufficiency of the legs - Doppler; Leg pain and ...

Free-surface velocity measurements using an optically recording velocity interferometer

International Nuclear Information System (INIS)

Lu Jianxin; Wang Zhao; Liang Jing; Shan Yusheng; Zhou Chuangzhi; Xiang Yihuai; Lu Ze; Tang Xiuzhang

2006-01-01

An optically recording velocity interferometer system (ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called 'Heaven I' with laser wavelength of 248.4 nm, pulse duration of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24 x 10 11 W·cm -2 , and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intensity 7.28 x 10 11 W·cm -2 . (authors)

PDV-based estimation of ejecta particles' mass-velocity function from shock-loaded tin experiment

Science.gov (United States)

Franzkowiak, J.-E.; Prudhomme, G.; Mercier, P.; Lauriot, S.; Dubreuil, E.; Berthe, L.

2018-03-01

A metallic tin plate with a given surface finish of wavelength λ ≃ 60 μm and amplitude h ≃ 8 μm is explosively driven by an electro-detonator with a shock-induced breakout pressure PSB = 28 GPa (unsupported). The resulting dynamic fragmentation process, the so-called "micro-jetting," is the creation of high-speed jets of matter moving faster than the bulk metallic surface. Hydrodynamic instabilities result in the fragmentation of these jets into micron-sized metallic particles constituting a self-expanding cloud of droplets, whose areal mass, velocity, and particle size distributions are unknown. Lithium-niobate-piezoelectric sensor measured areal mass and Photonic Doppler Velocimetry (PDV) was used to get a time-velocity spectrogram of the cloud. In this article, we present both experimental mass and velocity results and we relate the integrated areal mass of the cloud to the PDV power spectral density with the assumption of a power law particle size distribution. Two models of PDV spectrograms are described. The first one accounts for the speckle statistics of the spectrum and the second one describes an average spectrum for which speckle fluctuations are removed. Finally, the second model is used for a maximum likelihood estimation of the cloud's parameters from PDV data. The estimated integrated areal mass from PDV data is found to agree well with piezoelectric results. We highlight the relevance of analyzing PDV data and correlating different diagnostics to retrieve the physical properties of ejecta particles.

A novel velocity estimator using multiple frequency carriers

DEFF Research Database (Denmark)

Zhang, Zhuo; Jakobsson, Andreas; Nikolov, Svetoslav

2004-01-01

. In this paper, we propose a nonlinear least squares (NLS) estimator. Typically, NLS estimators are computationally cumbersome, in general requiring the minimization of a multidimensional and often multimodal cost function. Here, by noting that the unknown velocity will result in a common known frequency......Most modern ultrasound scanners use the so-called pulsed-wave Doppler technique to estimate the blood velocities. Among the narrowband-based methods, the autocorrelation estimator and the Fourier-based method are the most commonly used approaches. Due to the low level of the blood echo, the signal......-to-noise ratio is low, and some averaging in depth is applied to improve the estimate. Further, due to velocity gradients in space and time, the spectrum may get smeared. An alternative approach is to use a pulse with multiple frequency carriers, and do some form of averaging in the frequency domain. However...

The role of colour flow Doppler in the investigation of the salivary gland tumour

International Nuclear Information System (INIS)

Bradley, M.J.; Durham, L.H.; Lancer, J.M.

2000-01-01

AIMS: Ultrasound is a highly effective imaging technique to determine salivary gland tumours and may help to identify many benign lesions. The aim of this study is to evaluate whether colour Doppler is able to further differentiate the malignant tumour. METHODS: Fifty-six patients with salivary gland lesions were prospectively assessed using ultrasound imaging with colour flow and power Doppler. The peak systolic velocity (PSV) was measured and the pulsatility index (PI) and resistive index (RI) calculations were performed on the pulsed wave traces. The real time ultrasound morphology and the Doppler information were correlated with the histology. RESULTS: In 18 of the 56 patients, no internal colour flow or power Doppler changes could be detected. The real time ultrasound morphology diagnosed benign disease with sensitivity of 89.7% with specificity of 57.1%. The positive predictive value was 93.6%. There were no significant differences in the colour Doppler appearances in terms of vessel type or intratumour distribution which could separate benign from malignant conditions. However, there was statistical discrimination for PI and RI values (P = 0.0006, P = 0.0002, respectively). No malignant lesions were seen when the PI was less than 1.8 and RI was less than 0.8. The PSV was elevated in several cases (> 50 cm per s) but there was no statistical correlation with malignancy. CONCLUSION: The risk of malignancy increases by a third when the colour Doppler demonstrates increased intratumour vascular resistance (RI > 0.8 and PI > 1.8), with positive predictive value of 97.3% (sensitivity 75.5%, specificity 85.7%). Bradley, M.J. (2000). Clinical Radiology 55, 759-762

Measurement of turbulent flow fields in a agitated vessel with four baffles by laser-doppler velocimetry. Mean velocity fields and flow pattern; Buffle tsuki heiento kakuhan sonai nagare no LDV ni yoru keisoku. Heikin sokudoba to flow pattern

Energy Technology Data Exchange (ETDEWEB)

Suzukawa, K [Ube Industries, Ltd., Tokyo (Japan); hashimoto, T [Yamaguchi University, Yamaguchi (Japan); Osaka, H [Yamaguchi University, Yamaguchi (Japan). Faclty of Engineering

1997-12-25

The three dimensional complex turbulent flow fields induced by a four flat blade paddle impeller in agitated vessel were measured by laser Doppler velocimetry. Mixing vessel used was a closed cylindrical tank of 490 mm diameter with a flat bottom and four vertical buffles, giving water volumes of about 1001. The impellers were at the midnight of the water level in the tank. A height of liquid (water) was equal to the vessel diameter. Three components of mean velocity were measured at three vertical sections {theta}=7.5deg, 45deg and 85deg, in several horizontal planes. Mixing Reynolds number NRe was 1.2 times 10{sup 5}. It can be found from the results that circumferential mean velocity profiles show the symmetrical shape in the upper and lower sides of impeller. Secondary velocity components, such as axial and radial velocities, however, were not in symmetry. For this reason, the ratio of circulation flow volume which enter in upper and lower sides of impeller was roughly 7/3. In both the middle and buffle regions, mean flow velocities (flow patterns) were different, dependent of three vertical planes with different circumferential angle measured from buffle. 10 refs., 8 figs., 1 tab.

Velocities in a Centrifugal PAT Operation: Experiments and CFD Analyses

Directory of Open Access Journals (Sweden)

Mariana Simão

2017-12-01

Full Text Available Velocity profiles originated by a pump as turbine (PAT were measured using an ultrasonic doppler velocimetry (UDV. PAT behavior is influenced by the velocity data. The effect of the rotational speed and the associated flow velocity variations were investigated. This research focuses, particularly, on the velocity profiles achieved for different rotational speeds and discharge values along the impeller since that is where the available hydraulic power is transformed into the mechanical power. Comparisons were made between experimental test results and computational fluid dynamics (CFD simulations. The used CFD model was calibrated and validated using the same conditions as the experimental facility. The numerical simulations showed good approximation with the velocity measurements for different cross-sections along the PAT system. The application of this CFD numerical model and experimental tests contributed to better understanding the system behavior and to reach the best efficiency operating conditions. Improvements in the knowledge about the hydrodynamic flow behavior associated with the velocity triangles contribute to improvements in the PAT concept and operation.

A doppler-based evaluation of peripheral lower limb arterial insufficiency in diabetes mellitus

International Nuclear Information System (INIS)

Shaheen, R.; Sohail, S.

2010-01-01

To determine the frequency, level and flow patterns of lower limb arterial insufficiency in diabetic patients on Doppler ultrasound study. Study Design: Cross-sectional study. Place and Duration of Study: Radiology Department, Civil Hospital, Karachi, from February 2007 to September 2008. Methodology: One hundred adult diabetic patients with suspected peripheral vascular insufficiency irrespective of gender were included. Demographic data, presenting complaints, treatment history, and level of HbA1c were recorded. Doppler evaluated arterial status and ankle brachial index (ABI) were recorded on proforma. Statistical analysis were done on SPSS version 12. Results: The mean HbA1c was 8.4 +- 1.4 gm/dl, a majority of 77% having a controlled level of < 10 mg/dl. Arterial insufficiency on Doppler ultrasound was documented in 62% (p=0.016) and the dorsalis paedis artery was the predominant site of stenosis (24%). Spectral broadening and biphasic flow were salient features. The mean value of resistive index in stenotic cases was 0.563 +- 0.16 with a mean velocity difference of 0.37 +- 0.29 m/s (p < 0.001) at the site of stenosis. Conclusion: Peripheral vascular insufficiency was a significant finding in patients having diabetes for an average of 9.8 years, even in the presence of controlled HbA1c. The dorsalis paedis was the commonest site of involvement. The insufficiency was moderate with a biphasic flow pattern in a majority of cases. Difference in resistive index and flow velocities at and above the site of stenosis provided an important clue to the diagnosis of level of stenosis that helps in planning limb salvage management. (author)

Detection of geodesic acoustic mode oscillations, using multiple signal classification analysis of Doppler backscattering signal on Tore Supra

International Nuclear Information System (INIS)

Vermare, L.; Hennequin, P.; Gürcan, Ö.D.

2012-01-01