WorldWideScience
1

Laser double Doppler flowmeter  

Science.gov (United States)

The Laser Doppler flowmetry (LDF) is a non-invasive method for estimating the tissular blood flow and speed at a microscopic scale (microcirculation). It is used for medical research as well as for the diagnosis of diseases related to circulatory system tissues and organs including the issues of microvascular flow (perfusion). It is based on the Doppler effect, created by the interaction between the laser light and tissues. LDF measures the mean blood flow in a volume formed by the single laser beam, that penetrate into the skin. The size of this measurement volume is crucial and depends on skin absorption, and is not directly reachable. Therefore, current developments of the LDF are focused on the use of always more complex and sophisticated signal processing methods. On the other hand, laser Double Doppler Flowmeter (FL2D) proposes to use two laser beams to generate the measurement volume. This volume would be perfectly stable and localized at the intersection of the two laser beams. With FL2D we will be able to determine the absolute blood flow of a specific artery. One aimed application would be to help clinical physicians in health care units.

Poffo, L.; Goujon, J.-M.; Le Page, R.; Lemaitre, J.; Guendouz, M.; Lorrain, N.; Bosc, D.

2014-05-01

2

Monitoring of traumatic process after hernioplasty by allografts using laser doppler flowmeter  

International Nuclear Information System (INIS)

Full text: This is a comparative analysis of correlation between pathological phenomena of hemomicrom circulation at local trophic level of healing postoperative wounds by primary and secondary intention after hernioplasty by biomembranes (allografts) and by artificial reticular endoprosthesis. In this study two groups of patients were formed: I group (77 patients) underwent hernioplasty by implantation of biomembranes (Tutoplast allografts Fascia temporalis, Dermis); II group (81 patients) had hernioplasty using artificial reticular endoprosthesis. Comparative complex investigation of healing postoperative wounds was done by laser Doppler flowmeter, which allows fairly evaluating staging of traumatic process in 158 patients aging from 20 to 73 years, male, that underwent surgical treatments of inguinal hernia. In all patients traditional surgical technique using non-tension plasty methods for anterior abdominal wall was applied using above-mentioned materials. In first group wound healing took place by primary intention in all 77 patients and on amplitude-frequency spectrum of LDF charts happened by 4 phases: 1) reaction to trauma; 2) initial regeneration; 3) wound consolidation; 4) scar organization. In the second group - in 75 cases wound healing also took place by primary intention, but in 6 cases a secondary intention happened, which consisted on amplitude-frequency spectrum of LDF charts of 6 phases: 1) inflammation, 2) wound clearance from necrotic suppurative wound clearance from necrotic suppurative masses; 3) initial regeneration; 4) forming of granulations; 5) wound consolidation; 6) scar reorganization. To improve results of surgical treatment in patients with hernia it is needed to approach the choice of material for hernioplasty differentially depending hemodynamic type of microcirculation. Characteristics of vascular tissue system of future operative area directly influence the course of traumatic process in postoperative follow-up. Monitoring of traumatic process following hernioplasty by allografts done by laser Doppler flowmeter allows prognosing the course of early postoperative follow-up and to diagnosing complications in advance. (Author)

3

Correlation between Changes in Leg Blood Flow and Ankle-Brachial Pressure Index: A Study Using Laser Doppler Flowmeter —The 1st Report—  

OpenAIRE

Objective: The objective of this study was to use non-invasive laser Doppler flowmeter to measure changes in blood flow in peripheral vessels in the legs before and after stress induced by leg elevation stress test and investigate correlations with the ankle-brachial pressure index (ABI).

Suzuki, Kazuyoshi; Sekiguchi, Miho; Midorikawa, Hirofumi; Sato, Koichi; Akase, Kazuyoshi; Sawada, Renshi; Konno, Shin-ichi

2011-01-01

4

Wearable blood flowmeter appcessory with low-power laser Doppler signal processing for daily-life healthcare monitoring.  

Science.gov (United States)

A new appcessory for monitoring peripheral blood flow in daily life consists of a wearable laser Doppler sensor device and a cooperating smart phone application. Bluetooth Low Energy connects them wirelessly. The sensor device features ultralight weight of 15 g and an intermittent signal processing technique that reduces power consumption to only 7 mW at measurement intervals of 0.1 s. These features enable more than 24-h continuous monitoring of peripheral blood flow in daily life, which can provide valuable vital-sign information for healthcare services. PMID:25571431

Kuwabara, K; Higuchi, Y; Ogasawara, T; Koizumi, H; Haga, T

2014-01-01

5

Pancreatic capillary blood flow during caerulein-induced pancreatitis evaluated by a laser-doppler flowmeter in rats Estudo das alterações do fluxo capilar pancreático após infusão de ceruleína avaliado por laser-Doppler em ratos  

Directory of Open Access Journals (Sweden)

Full Text Available PURPOSE: The pancreatic capillary blood flow (PCBF was studied to determine its alterations during caerulein-induced pancreatitis in rats. METHODS: Twenty rats were divided in groups: control and caerulein. A laser-Doppler flowmeter to measure PCBF continuously was used. Blood pressure (BP and heart rate (HR were monitored. Serum biochemistry analyses were determined. Histopathological study was performed. RESULTS: The PCBF measured a mean of 109.08 ± 14.54% and 68.24 ± 10.47% in control group and caerulein group, respectively. Caerulein group had a mean decrease of 31.75 ± 16.79%. The serum amylase was 1323.70 ± 239.10U.I-1 and 2184.60 ± 700.46U.I-1 in control and caerulein groups, respectively. There was a significant difference in the PCBF (pOBJETIVO: O fluxo capilar pancreático (FCP foi estudado para determinar suas alterações durante a pancreatite aguda induzida por ceruleína, em ratos. MÉTODOS: Vinte ratos foram divididos em grupo controle e grupo ceruleína. Um laser-Doppler fluxímetro foi empregado para determinar, continuamente, o FCP durante 120 minutos. A pressão arterial média (PAM e a freqüência cardíaca (FC foram determinadas, durante o experimento. Análise bioquímica sérica e estudo histopatológico, por microscopia ótica, do tecido pancreático foram realizados, ao final do experimento. RESULTADOS: O FCP foi em média 109,08 ± 2,17% e 68,24 ± 16,79% nos grupos controle e ceruleína , respectivamente. No grupo ceruleína, houve uma diminuição média de 31,75 ± 16,79%. Os níveis de amilase sérica foram de 1323,70 ± 239,10U.I-1 e 2184,60 ± 700,46U.I-1 nos grupos controle e ceruleína, respectivamente. Houve diferença significante (p<0,05 no FCP e na amilasemia, quando comparado o grupo controle com o grupo ceruleína. Embora micro e macrovacuolização estivessem presentes no grupo ceruleína, não houve diferença histológica entre os grupos. CONCLUSÃO: A diminuição do FCP parece um evento precoce, antecedendo o aparecimento de alterações histopatológicas, por microscopia ótica, que caracterizam este modelo de pancreatite edematosa aguda.

Roberto Ferreira Meirelles Jr.

2003-01-01

6

The suitability of Doppler flowmeters for use in the minerals-processing industry  

International Nuclear Information System (INIS)

In this report, six commercially available Doppler flowmeters, which were operated under conditions likely to be encountered in the minerals-processing industry, are evaluated. The effects of the density and particle-size distribution of a flowing slurry and the optimum siting of the flowmeter probe are considered, and the results of tests on the response and linearity of the flowmeters are reported

7

Holographic laser Doppler ophthalmoscopy  

CERN Document Server

We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of the beat of the reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps of fluctuation spectra in the 10 Hz to 25 kHz band exhibit angiographic contrasts in the retinal vascular tree without requirement of an exogenous marker.

Simonutti, Manuel; Sahel, J A; Gross, Michel; Samson, Benjamin; Magnain, Caroline; Atlan, Michael; 10.1364/OL.35.001941

2010-01-01

8

Laser doppler perfusion imaging  

International Nuclear Information System (INIS)

Recording of tissue perfusion is important in assessing the influence of peripheral vascular diseases on the microcirculation. This thesis reports on a laser doppler perfusion imager based on dynamic light scattering in tissue. When a low power He-Ne laser beam sequentally scans the tissue, moving blood cells generate doppler components in the back-scattered light. A fraction of this light is detected by a photodetector and converted into an electrical signal. In the processor, a signal proportional to the tissue perfusion at each measurement site is calculated and stored. When the scanning procedure is completed, a color-coded perfusion image is presented on a monitor. To convert important aspects of the perfusion image into more quantitative parameters, data analysis functions are implemented in the software. A theory describing the dependence of the distance between individual measurement points and detector on the system amplification factor is proposed and correction algorithms are presented. The performance of the laser doppler perfusion imager was evaluated using a flow simulator. A linear relationship between processor output signal and flow through the simulator was demonstrated for blood cell concentrations below 0.2%. The median sampling depth of the laser beam was simulated by a Monte Carlo technique and estimated to 235 ?m. The perfusion imager has been used in the clinic to study perfusion changes in port wine stains treated with argon laser and to investigate the intensity and extension of the cutaneous axon reflex response after electrical nerve stimulation. The fact that perfusion can be visualized without touching the tissue implies elimination of sterilization problems, thus simplifying clinical investigations of perfusion in association with diagnosis and treatment of peripheral vascular diseases. 22 refs

9

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

International Nuclear Information System (INIS)

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)

10

Laser Doppler velocimetry for continuous flow solar-pumped iodine laser system  

Science.gov (United States)

A laser Doppler velocimetry (LDV) system was employed to measure the flow velocity profile of iodide vapor inside laser tubes of 36 mm ID and 20 mm ID. The LDV, which was operated in the forward scatter mode used a low power (15 mW) He-Ne laser beam. Velocity ranges from 1 m/s was measured to within one percent accuracy. The flow velocity profile across the laser tube was measured and the intensity of turbulence was determined. The flow of iodide inside the laser tube demonstrated a mixture of both turbulence and laminar flow. The flowmeter used for the laser system previously was calibrated with the LDV and found to be in good agreement.

Tabibi, Bagher M.; Lee, Ja H.

1991-01-01

11

Laser Doppler And Range Systems For Spacecraft  

Science.gov (United States)

Report discusses two types of proposed laser systems containing active transponders measuring distance (range) and line-of-sight velocity (via Doppler effect) between deep space vehicle and earth-orbiting satellite. Laser system offers diffraction advantage over microwave system. Delivers comparable power to distant receiver while using smaller transmitting and receiving antennas and less-powerful transmitter. Less subject to phase scintillations caused by passage through such inhomogeneous media as solar corona. One type of system called "incoherent" because range and Doppler measurements do not require coherence with laser carrier signals. Other type of system called "coherent" because successful operation requires coherent tracking of laser signals.

Kinman, P. W.; Gagliardi, R. M.

1990-01-01

12

Laser Doppler velocimeter aerial spray measurements  

Science.gov (United States)

An experimental research program for measuring the location, spatial extent, and relative concentration of airborne spray clouds generated by agricultural aircraft is described. The measurements were conducted with a ground-based laser Doppler velocimeter. The remote sensing instrumentation, experimental tests, and the results of the flight tests are discussed. The cross section of the aerial spray cloud and the observed location, extent, and relative concentration of the airborne particulates are presented. It is feasible to use a mobile laser Doppler velocimeter to track and monitor the transport and dispersion of aerial spray generated by an agricultural aircraft.

Zalay, A. D.; Eberle, W. R.; Howle, R. E.; Shrider, K. R.

1978-01-01

13

Quantitative measurement of portal blood flow in patients with chronic liver disease using an ultrasonic Duplex system consisting of a pulsed Doppler flowmeter and B-mode electroscanner.  

Science.gov (United States)

Portal blood flow (PBF) can be measured quantitatively using a B-mode combined pulsed Doppler (BCD) system. This system combines a real time B-mode linear type electroscanner and a pulsed Doppler (D-mode) flowmeter. Since both modes are displayed in realtime, Doppler blood flow signals can be retrieved at will from any depth. The blood flow velocity determined by the Doppler spectrogram and the vascular cross-sectional area measured from the B-mode tomographic image enables the quantitative calculation of blood flow volume. Using this system, PBF was measured quantitatively in 88 healthy adults, 54 patients with chronic hepatitis, 65 with cirrhosis of the liver, 27 with primary hepatoma and 12 with idiopathic portal hypertension (IPH). Results of PBF volume measurement were as follows: 889 +/- 284 ml/min (mean +/- S.D.) for healthy adults, 851 +/- 237 ml/min for patients with chronic hepatitis, 870 +/- 289 ml/min for cirrhosis of the liver, 966 +/- 375 ml/min for primary hepatoma and 1,047 +/- 381 ml/min for IPH. These preliminary results demonstrated that this ultrasonic Duplex system is clinically useful to determine the quantitative amount of PBF. PMID:6098510

Moriyasu, F; Ban, N; Nishida, O; Nakamura, T; Koizumi, S; Sakai, M; Kanematsu, Y; Miyake, T; Uchino, H

1984-12-01

14

Laser Doppler flowmetry for measurement of laminar capillary blood flow in the horse  

Science.gov (United States)

Current methods for in vivo evaluation of digital hemodynamics in the horse include angiography, scintigraphy, Doppler ultrasound, electromagnetic flow and isolated extracorporeal pump perfused digit preparations. These techniques are either non-quantifiable, do not allow for continuous measurement, require destruction of the horse orare invasive, inducing non- physiologic variables. In vitro techniques have also been reported for the evaluation of the effects of vasoactive agents on the digital vessels. The in vitro techniques are non-physiologic and have evaluated the vasculature proximal to the coronary band. Lastly, many of these techniques require general anesthesia or euthanasia of the animal. Laser Doppler flowmetry is a non-invasive, continuous measure of capillary blood flow. Laser Doppler flowmetry has been used to measure capillary blood flow in many tissues. The principle of this method is to measure the Doppler shift, that is, the frequency change that light undergoes when reflected by moving objects, such as red blood cells. Laser Doppler flowmetry records a continuous measurement of the red cell motion in the outer layer of the tissue under study, with little or no influence on physiologic blood flow. This output value constitutes the flux of red cells and is reported as capillary perfusion units. No direct information concerning oxygen, nutrient or waste metabolite exchange in the surrounding tissue is obtained. The relationship between the flowmeter output signal and the flux of red blood cells is linear. The principles of laser Doppler flowmetry will be discussed and the technique for laminar capillary blood flow measurements will be presented.

Adair, Henry S., III

1998-07-01

15

Laser Doppler instrument to investigate retinal neural activity-induced changes in optic nerve head blood flow  

Science.gov (United States)

A fundus camera-based instrument to investigate increased retinal neuronal activity effect on optic nerve blood flow is described. It incorporates (a) near infrared fundus illumination and observation, (b) near infrared laser Doppler flowmeter (LDF), (c) pupil position monitoring and (d) delivery of visual stimuli. Two types of stimulation are currently used: diffuse heterochromatic and chromatic luminance flicker generated by light emitting diodes, and contrast reversal pattern displayed on a video monitor. Recordings of the changes in the LDF parameters (blood velocity, volume and flow) from the optic nerve in response to these stimuli illustrate the potential of the technique.

Logean, Eric; Geiser, Martial H.; Riva, Charles E.

2005-03-01

16

Laser Doppler measurement of cutaneous blood flow  

International Nuclear Information System (INIS)

Laser Doppler velocimetry is an instrument system which has only recently been applied to the evaluation and quantitation of perfusion in the micro-vascular bed. The instrument is based on the Doppler principle, but uses low power laser light rather than the more commonly used ultrasound, and has a sample volume of approximately 1 mm/sup 3/. As it is non-invasive, it can be used on any skin surface or exposed microvascular bed and provides a continuous semi-quantitative measure of microcirculatory perfusion, it has a number of advantages as compared to other cutaneous blood flow measurement techniques. Initial studies have shown that it is easily used, and it has demonstrated good correlation with both xenon radio-isotope clearance and microsphere deposition techniques. Areas of current evaluation and utilization are in most major areas of medicine and surgery and include plastic, vascular and orthopaedic surgery, dermatology, gastro-enterology, rheumatology, burns and anaesthesiology

17

Fish embryo multimodal imaging by laser Doppler digital holography  

CERN Document Server

A laser Doppler imaging scheme combined to an upright microscope is proposed. Quantitative Doppler imaging in both velocity norm and direction, as well as amplitude contrast of either zebrafish flesh or vasculature is demonstrated.

Verrier, Nicolas; Picart, Pascal; Gross, Michel

2015-01-01

18

Optical scanner. [laser doppler velocimeters  

Science.gov (United States)

An optical scanner that sequentially focuses optical energy (light) at selected points in space is described. The essential component is a scanning wheel including several glass windows with each window having a different thickness. Due to this difference in thickness, the displacement of the emerging light from the incident light is different for each window. The scanner transmits optical energy to a point in space while at the same time receiving any optical energy generated at that point and then moves on to the next selected point and repeats this transmit and receive operation. It fills the need for a system that permits a laser velocimeter to rapidly scan across a constantly changing flow field in an aerodynamic test facility.

Rhodes, D. B. (inventor)

1977-01-01

19

Laser Doppler blood flow measurements of common cutaneous donor sites for reconstructive surgery.  

Science.gov (United States)

The purpose of this study was to evaluate cutaneous blood flow in regions commonly used as donor sites in reconstructive surgery in order to better establish normal flow ranges. Flow was measured with the TSI Laserflo BPM 403 in 27 healthy volunteers and compared to the flow in uncomplicated postoperative autologous tissue transplants. The forehead produced the highest flow, with an average value of 6.50 +/- 0.31 (mean +/- SE), and the dorsalis pedis had the lowest flow, with an average value of 0.60 +/- 0.04. Gender differences were noted in the latissimus dorsi, pectoralis major, and rectus abdominis areas. There were no significant differences between smokers and nonsmokers, hand dominance, musculocutaneous and fasciocutaneous tissues, or supine and sitting body positions. Flow levels in volunteers were similar to those in postoperative surviving autologous tissue transplants. The site-specific flow and flow changes over long time periods (hours) have helped clinical monitoring of 77 patients in the last 24 months. In every case identified by the flowmeter as decreased perfusion, a definite etiology for low reduction was documented. Complications occurred in 12 patients, and the rate of salvaging compromised tissue has increased from 50 percent using temperature monitoring and clinical observation to 83 percent with the computerized laser Doppler flowmeter. PMID:2179975

Goldberg, J; Sepka, R S; Perona, B P; Pederson, W C; Klitzman, B

1990-04-01

20

Wide-field stabilized Doppler flowmetry with the tracking scanning laser ophthalmoscope (TSLO)  

Science.gov (United States)

Real time, high-speed image stabilization with a retinal tracking scanning laser ophthalmoscope (TSLO) enables new approaches to established diagnostics. Large dynamic range, wide-field stabilized Doppler flowmetry imaging was demonstrated in initial human subject testing with a large frequency range and up to 40 deg fields of view. The retinal tracking system uses a confocal reflectometer with a closed loop optical servo system to lock onto features in the ocular fundus. The fundus imaging method is a quasi-confocal line-scanning laser ophthalmoscope (LSLO). By locking to the retina and performing a slow scan of the laser line imager taking up to 30 seconds, frequency-resolved retinal perfusion and vascular flow images were obtained. The tracking system and auto-relock algorithms after blinks allowed the full image to be captured free of eye motion artifacts. Image cubes comprised of 512 by 512 spatial pixels by 512 or more temporal pixels were captured with a line rate of up to 20 kHz. The line sensor integrates, as opposed to conventional SLO flowmeters, thus minimizing aliasing that contributes to velocity errors. Fast Fourier Transform (FFT) power spectra at each image pixel were computed. Image reconstruction accuracy was typically better than one pixel width. Doppler frequency resolution from 14 Hz to 3.675 kHz was demonstrated in this work. Pulsatile flow effects were observed. Normal adult subjects and patients were tested with or without mydriasis to characterize flow imaging performance.

Ferguson, R. D.; Hammer, Daniel X.; Elsner, Ann E.; Burns, Stephen A.; Webb, Robert H.; Weiter, John J.

2004-07-01

21

Analysis of blood flow in pulmonary hypertension with the pulsed Doppler flowmeter combined with cross sectional echocardiography.  

OpenAIRE

Blood flow patterns were analysed at nine points in the pulmonary area using the pulsed Doppler technique combined with cross-sectional echocardiography in 53 patients with heart disease and 10 healthy subjects. In subjects with a normal pulmonary artery pressure the blood flow pattern in systole showed a gradual acceleration and deceleration with a rounded summit in mid systole, designated the round type. In patients with pulmonary hypertension it showed a rapid acceleration and early decele...

Okamoto, M.; Miyatake, K.; Kinoshita, N.; Sakakibara, H.; Nimura, Y.

1984-01-01

22

Widefield laser doppler velocimeter: development and theory.  

Energy Technology Data Exchange (ETDEWEB)

The widefield laser Doppler velocimeter is a new measurement technique that significantly expands the functionality of a traditional scanning system. This new technique allows full-field velocity measurements without scanning, a drawback of traditional measurement techniques. This is particularly important for tests in which the sample is destroyed or the motion of the sample is non-repetitive. The goal of creating ''velocity movies'' was accomplished during the research, and this report describes the current functionality and operation of the system. The mathematical underpinnings and system setup are thoroughly described. Two prototype experiments are then presented to show the practical use of the current system. Details of the corresponding hardware used to collect the data and the associated software to analyze the data are presented.

Hansche, Bruce David; Reu, Phillip L.; Massad, Jordan Elias

2007-03-01

23

Laser Doppler vibrometry: new ENT applications  

Science.gov (United States)

Common audiometry often does not really allow a reliable and objective differential diagnosis of hearing disorders such as otosclerosis, adhesive otitis, ossicular interruption or tinnitus, even though several methods might be used complementarily. In recent years, some experimental studies on middle ear mechanics established laser Doppler vibrometry (LDV) as a useful method allowing objective measurement of human tympanic membrane displacement. The present study on LDV investigated the clinical use of this new method under physiological conditions. LDV proved to be a fast, reproducible, non-invasive and very sensitive instrument to characterize ear-drum vibrations in various middle ear dysfunctions, except in tinnitus patients. For future applications, improved optical characteristics of the vibrometer might result in a better differential diagnosis of subjective and objective tinnitus, otoacoustic emissions or Morbus Meniere.

Stasche, Norbert; Baermann, M.; Kempe, C.; Hoermann, Karl; Foth, Hans-Jochen

1996-12-01

24

Sub-Doppler laser cooling of potassium atoms  

CERN Document Server

We investigate sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of systems and an adiabatic ramping of the laser parameters allows to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25(3)microK and 47(5)microK in high-density samples of the two isotopes 39K and 41K, respectively. Our findings will find application to other atomic systems.

Landini, M; Carcagni', L; Trypogeorgos, D; Fattori, M; Inguscio, M; Modugno, G

2011-01-01

25

Sub-Doppler laser cooling of potassium atoms  

Energy Technology Data Exchange (ETDEWEB)

We investigate the sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of system and an adiabatic ramping of the laser parameters allows us to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25{+-}3 {mu}K and 47{+-}5 {mu}K in high-density samples of the two isotopes {sup 39}K and {sup 41}K, respectively. Our findings should find application to other atomic systems.

Landini, M. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Dipartimento di fisica, Universita di Trento, I-38123 Povo (Trento) (Italy); Roy, S.; Carcagni, L.; Trypogeorgos, D. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); Fattori, M.; Inguscio, M.; Modugno, G. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy)

2011-10-15

26

Application of laser Doppler velocimeter to chemical vapor laser system  

Science.gov (United States)

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

27

Muscle activity characterization by laser Doppler Myography  

International Nuclear Information System (INIS)

Electromiography (EMG) is the gold-standard technique used for the evaluation of muscle activity. This technique is used in biomechanics, sport medicine, neurology and rehabilitation therapy and it provides the electrical activity produced by skeletal muscles. Among the parameters measured with EMG, two very important quantities are: signal amplitude and duration of muscle contraction, muscle fatigue and maximum muscle power. Recently, a new measurement procedure, named Laser Doppler Myography (LDMi), for the non contact assessment of muscle activity has been proposed to measure the vibro-mechanical behaviour of the muscle. The aim of this study is to present the LDMi technique and to evaluate its capacity to measure some characteristic features proper of the muscle. In this paper LDMi is compared with standard superficial EMG (sEMG) requiring the application of sensors on the skin of each patient. sEMG and LDMi signals have been simultaneously acquired and processed to test correlations. Three parameters has been analyzed to compare these techniques: Muscle activation timing, signal amplitude and muscle fatigue. LDMi appears to be a reliable and promising measurement technique allowing the measurements without contact with the patient skin

28

Evaluating microcirculation by pulsatile laser Doppler signal  

International Nuclear Information System (INIS)

Laser Doppler flowmetry (LDF) is a popular method for monitoring the microcirculation, but it does not provide absolute measurements. Instead, the mean flux response or energy distribution in the frequency domain is generally compared before and after stimulus. Using the heartbeat as a trigger, we investigated whether the relation between pressure and flux can be used to discriminate different microcirculatory conditions. We propose the following three pulsatile indices for evaluating the microcirculation condition from the normalized pressure and flux segment with a synchronized-averaging method: peak delay time (PDT), pressure rise time and flux rise time (FRT). The abdominal aortic blood pressure and renal cortex flux (RCF) signals were measured in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The mean value of the RCF did not differ between SHR and WKY. However, the PDT was longer in SHR (87.14 ± 5.54 ms, mean ± SD) than in WKY (76.92 ± 2.62 ms; p < 0.001). The FRT was also longer in SHR (66.56 ± 1.98 ms) than in WKY (58.02 ± 1.77 ms; p < 0.001). We propose that a new dimension for comparing the LDF signals, which the results from the present study show, can be used to discriminate RCF signals that cannot be discriminated using traditional methods

29

Laser Doppler technology applied to atmospheric environmental operating problems  

Science.gov (United States)

Carbon dioxide laser Doppler ground wind data were very favorably compared with data from standard anemometers. As a result of these measurements, two breadboard systems were developed for taking research data: a continuous wave velocimeter and a pulsed Doppler system. The scanning continuous wave laser Doppler velocimeter developed for detecting, tracking and measuring aircraft wake vortices was successfully tested at an airport where it located vortices to an accuracy of 3 meters at a range of 150 meters. The airborne pulsed laser Doppler system was developed to detect and measure clear air turbulence (CAT). This system was tested aboard an aircraft, but jet stream CAT was not encountered. However, low altitude turbulence in cumulus clouds near a mountain range was detected by the system and encountered by the aircraft at the predicted time.

Weaver, E. A.; Bilbro, J. W.; Dunkin, J. A.; Jeffreys, H. B.

1976-01-01

30

Blood flow measurement by laser Doppler method in orofacial region  

Directory of Open Access Journals (Sweden)

Full Text Available Laser Doppler is a noninvasive, objective, reproducible and painless method for measuring blood flow in tissue microcirculation. This method is based on the Doppler effect, the change in frequency of light reflecting from blood cells in motion. Light from helium-neon laser through optical fibers and probes is directed to the surface of the tissue in which the flow is measured. Light portion is reflected from the cells in motion and changes the frequency while another portion is reflected from the static tissue maintaining the same frequency as the initial light. The total reflected light, with changed and original frequency, reaches photo detector in the same probe where the emitter is and it is transformed into electrical impulse. In the orofacial region the laser Doppler method is used to examine blood flow in the mandible, teeth pulp and masticator muscles. A significant drawback of the laser Doppler method is its sensitivity to the ambient conditions during measuring and the fact that blood flow is measured in all blood vessels of examined microregion. Therefore, the circulation of isolated individual blood vessels can not be monitored. Laser Doppler method can give reliable indicators of blood flow in mouth tissue and method is acceptable for the patients.

Grga ?urica

2010-01-01

31

Measurement depth and volume in laser Doppler flowmetry  

OpenAIRE

A new method for estimating the measurement depth and volume in laser Doppler flowmetry (LDF) is presented. The method is based on Monte Carlo simulations of light propagation in tissue. The contribution from each individual Doppler shift is calculated and thereby multiple Doppler shifts are handled correctly. Different LDF setups for both probe based (0.0, 0.25, 0.5, and 1.2 mm source-detector separation) and imaging systems (0.5 and 2.0 mm beam diameter) are considered, at the wavelengths 5...

Fredriksson, Ingemar; Larsson, Marcus; Stro?mberg, Tomas

2009-01-01

32

Vocal fold vibration measurements using laser Doppler vibrometry  

OpenAIRE

The objective of this study was to measure the velocity of the superior surface of human vocal folds during phonation using laser Doppler vibrometry (LDV). A custom-made endoscopic laser beam deflection unit was designed and fabricated. An in vivo clinical experimental procedure was developed to simultaneously collect LDV velocity and video from videolaryngoscopy. The velocity along the direction of the laser beam, i.e., the inferior-superior direction, was captured. The velocity was synchron...

Chan, Alfred; Mongeau, Luc; Kost, Karen

2013-01-01

33

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

Science.gov (United States)

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

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

2004-07-01

34

Perfusion of the human distal colon and rectum evaluated with endoscopic laser Doppler flowmetry  

International Nuclear Information System (INIS)

The aim of this study was to evaluate methodologic aspects of colonoscopic laser Doppler flowmetry. A Periflux PF1d flowmeter, set to 4 kHz/0.2 sec, with an endoscopic probe was used. In 20 patients, with a median age of 70 years and without colonic disease, flux was recorded at 10, 40, 30, 20 and again at 10 cm from the anal verge. A median of three repeated recordings were made at each level to calculate average flux and spatial variation. Median flux was 158 perfusion units, and the coefficient of variation of repeated recordings 0.14. There was no regional variation, and no increase in flux at 10 cm from the start until the end of the procedure. Pressure of the probe against the bowel wall and severe distention significantly reduced the flux. The interference of light from the endoscopic light source on the flux could not be predicted. It differed with different light sources, and also with the length of probe coming out of the colonoscope - that is, the distance from the light to the measurement point. To avoid the problem, the light source should be turned off while recording. 19 refs., 4 figs

35

Fano-Doppler laser cooling of hybrid nanostructures.  

Science.gov (United States)

Laser cooling the center-of-mass motion of systems that exhibit Fano resonances is discussed. We find that cooling occurs for red or blue detuning of the laser frequency from resonance depending on the Fano factor associated with the resonance. The combination of the Doppler effect with the radiation cross-section quenching typical of quantum interference yields temperatures below the conventional Doppler limit. This scheme opens perspectives for controlling the motion of mesoscopic systems such as hybrid nanostructures at the quantum regime and the exploration of motional nonclassical states at the nanoscale. PMID:21806014

Ridolfo, Alessandro; Saija, Rosalba; Savasta, Salvatore; Jones, Philip H; Iatì, Maria Antonia; Maragò, Onofrio M

2011-09-27

36

Tissue perfusion measurements: multiple-exposure laser speckle analysis generates laser Doppler-like spectra  

Science.gov (United States)

Variations in skin perfusion are easily detected by laser speckle contrast maps, but a robust interpretation of the information has been lacking. We show that multiple-exposure laser speckle methods produce the same spectral information as laser Doppler methods when applied to targets with embedded moving scatterers. This enables laser speckle measurements to be interpreted more quantitatively. We do this by using computer simulation of speckle data, and by experimental measurements on Brownian motion and skin perfusion using a laser Doppler system and a multiple-exposure laser speckle system. The power spectral density measurements of the light fluctuations derived using both techniques are exactly equivalent. Dermal perfusion can therefore be measured by laser Doppler or laser speckle contrast methods. In particular, multiexposure laser speckle can be rapidly processed to generate a full-field map of the perfusion index proportional to the concentration and mean velocity of red blood cells.

Thompson, Oliver B.; Andrews, Michael K.

2010-03-01

37

Holographic laser Doppler imaging of microvascular blood flow  

CERN Document Server

We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency shifted reference beam, permits frequency selective imaging in the radiofrequency range. These Doppler images are acquired with an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse method analysis of local first order optical fluctuation spectra at low radiofrequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1 to 10 millimeters per second range in vitro ...

Magnain, C; Boucneau, T; Simonutti, M; Ferezou, I; Rancillac, A; Vitalis, T; Sahel, J A; Paques, M; Atlan, M

2014-01-01

38

All semiconductor laser Doppler anemometer at 1.55 ?m  

DEFF Research Database (Denmark)

We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz. Udgivelsesdato: October 23, 2008

Hansen, René Skov; Pedersen, Christian

2008-01-01

39

Coherent Doppler Laser Radar: Technology Development and Applications  

Science.gov (United States)

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 headwind minimization. In addition to the airborne and space platforms, a coherent Doppler laser radar system in an unmanned aerial vehicle (UAV) could provide battlefield weather and target identification.

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

2000-01-01

40

Influence of laser frequency noise on scanning Fabry-Perot interferometer based laser Doppler velocimetry  

DEFF Research Database (Denmark)

n this work, we study the performance of a scanning Fabry-Perot interferometer based laser Doppler velocimeter (sFPILDV) and compare two candidate 1.5 um single-frequency laser sources for the system – a fiber laser (FL) and a semiconductor laser (SL). We describe a straightforward calibration procedure for the sFPI-LDV and investigate the effect of different degrees of laser frequency noise between the FL and the SL on the velocimeter’s performance

Rodrigo, Peter John; Pedersen, Christian

2014-01-01

41

Three-dimensional laser cooling at the Doppler limit  

Science.gov (United States)

Many predictions of Doppler-cooling theory of two-level atoms have never been verified in a three-dimensional geometry, including the celebrated minimum achievable temperature ? ? /2 kB , where ? is the transition linewidth. Here we show that, despite their degenerate level structure, we can use helium-4 atoms to achieve a situation in which these predictions can be verified. We make measurements of atomic temperatures, magneto-optical trap sizes, and the sensitivity of optical molasses to a power imbalance in the laser beams, finding excellent agreement with Doppler theory. We show that the special properties of helium, particularly its small mass and narrow transition linewidth, prevent effective sub-Doppler cooling with red-detuned optical molasses. This discussion can be generalized to identify when a given species is likely to be subject to the same limitation.

Chang, R.; Hoendervanger, A. L.; Bouton, Q.; Fang, Y.; Klafka, T.; Audo, K.; Aspect, A.; Westbrook, C. I.; Clément, D.

2014-12-01

42

Three-dimensional laser cooling at the Doppler limit  

CERN Document Server

Many predictions of the theory of Doppler cooling of 2-level atoms, notably the celebrated minimum achievable temperature $T_D=\\hbar \\Gamma/2 k_B$, have never been verified in a three-dimensional geometry. Here, we show that, despite their degenerate level structure, we can use Helium-4 atoms to achieve a situation in which these predictions can be verified. We make measurements of atomic temperatures, magneto-optical trap sizes, and the sensitivity of optical molasses to a power imbalance in the laser beams, finding excellent agreement with the Doppler theory. We show that the special properties of Helium, particularly its small mass and narrow transition linewidth, prevent effective sub-Doppler cooling with red-detuned optical molasses.

Chang, Rockson; Bouton, Quentin; Fang, Yami; Klafka, Tobias; Audo, Kevin; Aspect, Alain; Westbrook, Christoph I; Clément, David

2014-01-01

43

Laser Doppler flowmetry to measure changes in cerebral blood flow.  

OpenAIRE

Laser Doppler flowmetry (LDF) is a method by which relative cerebral blood flow (CBF) of the cortex can be measured. Although the method is easy to employ, LDF only measures relative CBF, while absolute CBF cannot be quantified. LDF is useful for investigating CBF changes in a number of different applications including neurovascular and stroke research. This chapter will prepare the reader for rodent experiments using LDF with two preparations. The closed skull preparation can be used to moni...

Sutherland, Ba; Rabie, T.; Buchan, Am

2014-01-01

44

Exploring shot noise and Laser Doppler imagery with heterodyne holography  

OpenAIRE

Heterodyne Holography is a variant of Digital Holography, where the optical frequencies of signal and reference arms can be freely adjusted by acousto-optic modulators. Heterodyne Holography is an extremely versatile and reliable holographic technique, which is able the reach the shot noise limit in sensitivity at very low levels of signal. Frequency tuning enables Heterodyne Holography to become a Laser Doppler imaging technique that is able to analyze various kinds of motion.

Gross, Michel; Verpillat, Fre?de?ric; Joud, Fadwa; Atlan, Michael

2012-01-01

45

Reynolds stress measurements in cylindrical geometry using laser Doppler anemometry  

International Nuclear Information System (INIS)

Two-component one-point velocity correlation measurements in a cylindrical test section were performed using two-color Laser Doppler anemometry (LDA). In order to overcome the severe optical distortion effects in cylindrical geometry and achieve two-color spatial coincidence, two experimental methods were used: (1) attaching a rectangular, fluid-filled box to the pipe exterior; and (2) employing a laser-beam translating device. A description of these methods and some examples of coincidence data taken in pipe flow are presented

46

Laser-scanning Doppler photoacoustic microscopy based on temporal correlation  

Science.gov (United States)

We present a methodology to measure absolute flow velocity using laser-scanning photoacoustic microscopy. To obtain the Doppler angle, the angle between ultrasonic detection axis and flow direction, we extracted the distances between the transducer and three adjacent scanning points along the flow and repeatedly applied the law of cosines. To measure flow velocity along the ultrasonic detection axis, we calculated the time shift between two consecutive photoacoustic waves at the same scanning point, then converted the time shift to velocity according to the sound velocity and time interval between two laser illuminations. We verified our method by imaging flow phantoms.

Song, Wei; Liu, Wenzhong; Zhang, Hao F.

2013-05-01

47

Wind Doppler lidar with 1.5 ?m fiber laser  

International Nuclear Information System (INIS)

Compact Doppler lidar with monostatic receiving geometry has been developed and tested. Laser source of the lidar is continuous wave fiber laser ELD-1000 with 1.5 ?m wavelength and 1 W output. For distances up to 100 m the range of measurable wind velocities is 1.5 – 20 m/s. Results obtained show that performance conditions for the lidar corresponds to the visibility range up to 1 km. Sonic vibrations with small amplitudes (? 10 nm) of remote targets with diffuse reflection has been registered by this device at distances up to 60 m

48

Sub-Doppler Laser Cooling of Fermionic K-40 Atoms  

CERN Document Server

We report laser cooling of fermionic K-40 atoms, with temperatures down to (15 +/- 5) microK, for an enriched sample trapped in a MOT and additionaly cooled in optical molasses. This temperature is a factor of 10 below the Doppler-cooling limit and corresponds to an rms velocity within a factor of two of the lowest realizable rms velocity (~3.5v rec) in 3D optical molasses. Realization of such low atom temperatures, up to now only accessible with evaporative cooling techniques, is an important precursor to producing a degenerate Fermi gas of K-40 atoms.

Modugno, G; Hannaford, P; Roati, G; Inguscio, M

1999-01-01

49

Short-time Fourier transform laser Doppler holography  

OpenAIRE

We report a demonstration of laser Doppler holography at a sustained acquisition rate of 250 Hz on a 1 Megapixel complementary metal-oxide-semiconductor (CMOS) sensor array and image display at 10 Hz frame rate. The holograms are optically acquired in off-axis configuration, with a frequency-shifted reference beam. Wide-field imaging of optical fluctuations in a 250 Hz frequency band is achieved by turning time-domain samplings to the dual domain via short-time temporal Four...

Samson, Benjamin; Atlan, Michael

2012-01-01

50

Fiber optic laser Doppler anemometry in swirling jets  

Science.gov (United States)

Time-averaged and fluctuating quantities are measured in a free turbulent swirling jet. Data from a two-component laser Doppler anemometry (LDA) are compared to the measurements via hot-wire and 5-hole pitot probes. To acquire the proper seeding density near the axis of a swirling jet for LDA measurements proved difficult. This is due to an imbalance of the centrifugal force and radial pressure gradient, which throws the seeding material off the axis. Despite this problem, close agreement between various measurement techniques is obtained.

Taghavi, R.; Rice, E. J.

1991-01-01

51

Holographic laser Doppler imaging of pulsatile blood flow  

CERN Document Server

We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

Bencteux, Jeffrey; Kostas, Thomas; Bayat, Sam; Atlan, Michael

2015-01-01

52

PC-integrated laser Doppler blood flow measurements in skin  

Science.gov (United States)

By irradiation of the skin with a diode laser the blood flow can be measured using the back scattered light. The majority of the back scattered light is scattered from fixed cells, but a small amount is scattered from moving erythrocytes and is Doppler shifted. The mixed light detected with a photodiode leads directly to a photocurrent proportional to the Doppler signal. A laser Doppler blood flow meter was developed, consisting of a PC-AT (66 MHz), a commercial A/D card (14 bit, 100 kHz) and a special head control card for two laser heads. The heads have a diameter of 35 mm and a height of 15 mm. The heads are fixed to the skin with tape. A DOS-Pascal software program provides the measurement, the calculation of a whole blood flow spectrum and shows the results on the screen with a time resolution of up to 50 Hz. The laser head is connected via 2 m cables with the head control card and contains a diode laser (5 mW, 670, 785 nm) a micro lens, two photodiodes and a pre-amplifier. On the head control card there is the current supply for the laser diodes, also the Doppler signals are band passed (400 Hz to 50 kHz), further amplified and fed into the A/D card. On the A/D card the analog signal is sampled with 100 kHz and digitized with 14 bit resolution. With 256 samples a frequency spectrum (128 channels, 0 - 50 kHz) is calculated by a FFT, but only the first 100 channels (0 - 39 kHz) are used to prevent ghosts. The measurements of the Doppler signal of the two laser heads need 5.2 ms and for all software calculations 15 ms are necessary. A quantitative recalculation of a velocity spectrum from the frequency spectrum is only possible if the velocity-, the irradiation-, and scattering-directions are known. In skin the small blood vessels have various directions and because of scattering in skin the irradiation of an erythrocyte can be assumed to be random. With this assumption of a random direction distribution a velocity spectrum can be calculated from the frequency spectrum. A flow spectrum is defined as the product of the velocity and the intensity at this velocity. The flow is defined as the integral over a given region of the flow spectrum. Four independent flow curves can be shown simultaneously on the screen and the frequency region for each flow can be set independently. The flows from low (1 - 3 mm/s) and high (7 - 9 mm/s) velocities show a different behavior and give the possibility to distinguish between the flow in the micro capillaries and larger vessels in the skin.

Doerschel, Klaus; Mueller, Gerhard J.

1996-05-01

53

Laser spectroscopy of multi-level doppler broadened atomic system  

International Nuclear Information System (INIS)

Doppler broadened atomic vapor system can be easily prepared for spectroscopy study than an atomic beam system can be. Vapor cell and hollow cathode discharge lamps are widely used in the experiment. The possibility for observing the trapped state in a Doppler broadened ? system was examined and confirmed by our early experiment where counter-propagating laser beams are used. For the measurement of the hyperfine structure constants of high-lying levels of heavy elements, we compared the co-propagating and counter-propagating beams in a Doppler broadened ladder systems. It was shown that the counter-propagating beams give a stronger and narrower signal than that from the co-propagating beams. Our treatment also considers the power broadening of the transition. For some photo-ionization experiments, it is necessary to pump two thermally populated levels simultaneously to the higher level and then to the auto-ionizing levels. A technique is proposed to avoid the trapped state and to increase the ionization efficiency.

54

Application of Doppler and transit laser anemometry in small turbomachines  

Science.gov (United States)

The selection laser anemometry systems and their application to the particularly hostile environment found in small high speed rotating turbomachines are discussed. There are several different laser anemometry systems which are used in turbomachinery studies and when selecting a system to carry out specific duties it is necessary to have some prior knowledge of the flows to be measured, the spacial resolution required and any limitations on optical access. The optical access will often determine the spatial resolution possible and the quality of the scattered signal will generally determine the type of signal processor which can be used. The criteria used for the selection of systems at Cranfield are discussed. The arrangements in use include both the Doppler and transit systems each of which are found to have unique and very distinct advantages.

Elder, R. L.; Forster, C. P.; Gill, M. E.

1986-11-01

55

Doppler instrumentation for measuring blood velocity and flow  

Science.gov (United States)

Doppler ultrasonic blood flowmeters are reviewed in detail. The importance of measurement accuracy for transcutaneous flowmeters and their clinical application is stressed. Doppler imaging was combined with conventional pulse echo imaging, and diagnostic information was extracted from flow signals. The range and extent of applications of Doppler instruments was also presented.

Gill, R. W.; Hottinger, C. F.; Meindl, J. D.

1975-01-01

56

The helicopter flight test analysis of all-fiber laser Doppler velocity sensor  

Science.gov (United States)

This paper gives a novel All-Fiber laser Doppler Velocity Sensor(ALDVS) to measure the relative velocity to the lunar or planetary bodies during the vehicle landing phase. In the beginning of the paper, A brief description of the principle of laser Doppler velocity sensor is given. After that, the paper gives the laser Doppler velocity sensor configuration. The paper introduce the helicopter flight test that was held in Zhengzhou. The altitude of flight is about 3km.The laser Doppler velocity data is analysed. The GPS velocity data and laser Doppler velocity sensor velocity information are compared. Finally, the equivalent distant in moon is calculated and the measurement error is discussed.

Liu, Bo; Sui, Xiao-lin; Zhao, Hong; Xiong, Wen-long; Cao, Chang-dong; Yan, Zi-heng; Zhang, Ying

2013-09-01

57

Measuring with laser Doppler vibrometer on moving frame (LDVMF)  

Science.gov (United States)

Structural dynamic gives insight into structural properties such as mass, eigenfrequencies, eigenmodes, modal damping and strain distribution and can be utilized in structural health monitoring, dynamic sub-structuring, etc. In this context structural vibration is measured and used. The measurement is done by means of conventional sensors such as accelerometers or non destructively using Laser Doppler Vibrometer (LDV), for instance. The non-destructive, non-contact measurement techniques preserve the integrity of the structure and don't add mass and stiffness to the structure under test. When one deals with civil structures such as rail and road ways, pipelines and catenary the importance of these techniques becomes more evident as they allow standoff measurement on a moving frame. Nevertheless when LDV is employed due to the relative in-plane motion between the LDV and the target speckle noise is generated which degrades the signal quality and makes this application not very straightforward but challenging. One of the first Laser Doppler Vibrometer on moving frame is adopted to measure and monitor the ground vibration, aiming at detection of buried land mines. The major addressed difficulty in this application is the speckle noise present in the acquired signal. In general the signal quality and the Signal to Noise Ratio (SNR) are a function of the laser spot size and wave length, measurement distance, relative velocity and sampling frequency. A trade-off between these factors, which are not always intuitive would help to minimize the noise floor due to the speckle noise. In this paper a test rig is presented which allows to study the speckle noise at different measurement ranges, between 1.8 and 2.8 m, and different velocities, up to 150 km/h. The results might serve as a guideline to the design process of a LDVMF.

Rahimi, Siamand; Li, Zili; Dollevoet, Rolf

2014-05-01

58

Laser Doppler flowmetry evaluation of gingival recovery response after laser treatment  

Science.gov (United States)

This study was performed in order to evaluate in vivo the applicability of Laser Doppler Flowmetry (LDF) in recording the gingival blood flow and to assess the changes of gingival blood flow following gingival reshaping performed with Er:YAG and 980 nm diode lasers. The LDF evaluation was performed on 20 anterior teeth, which underwent reshaping of gingiva, corresponding to 5 female patients (4 anterior teeth/patient), aged between 20 and 35. One part of the mouth was treated with Er:YAG laser (LP, VLP modes, 140 - 250 mJ, 10 - 20 Hz, using cylindrical sapphire tips) and other part with 980 nm diode laser (CW, 4 W, contact mode and saline solution cooling). The gingival blood flow was monitored using a MoorLab laser Doppler equipment (Moor Instruments Ltd., Axminster, UK) with a straight optical probe, MP3b, 10 mm. The data were processed using statistical analysis software SPSS v16.0.1. The investigation showed an evident decrease in perfusion for both areas in comparison with the baseline values 24 hours after treatment. The microvascular blood flow increased significantly after 7 days in both areas but mostly in diode area (plasers proved efficiency in the surgical treatment of gingival tissue. Moreover, Laser Doppler Flowmetry is adequate for recording changes in gingival blood flow following periodontal surgery.

Todea, Carmen; Cânj?u, Silvana; Dodenciu, Dorin; Miron, Mariana I.; Tudor, Anca; B?l?buc, Cosmin

2013-06-01

59

Similarity of fingertip skin blood flow patterns recorded by the model-based thermal clearance and large area laser Doppler probes.  

Science.gov (United States)

We compared two different techniques for non-invasive registration of fingertip skin blood flow patterns in 15 healthy volunteers during a rest at room temperature 26-28 degrees C. The large area probes of a two-channel laser Doppler flowmeter (LDF) and an experimental probe of a thermal clearance (TC) instrument provided approximately the same sample volume of the studied tissue. The laser Doppler probes were attached to the pulp of the index (LDF1) and ring (LDF2) fingers, while the TC probe to the pulp of the middle finger. A computer simulation method, provided by the MATLAB package, was introduced to speed up the frequency response of the TC probe. By calculating the correlation coefficients and applying the least squares criterion, we evaluated the similarity of the 3-min samples having time resolution of 1 s. The group-averaged value of the correlation coefficient (median with a 99% confidence interval) for LDF2 versus LDF1 equalled 0.95 (0.92-0.97). After an introduction of the computer-based frequency correction, the correlation coefficient for TC versus LDF1 increased from 0.81 (0.61-0.85) till 0.92 (0.84-0.95), while the root mean squared error between TC and LDF1 diminished by 33% (p<0.001). PMID:11755811

Raamat, R; Kudimov, B; Jagomägi, K

2001-11-01

60

Vocal fold vibration measurements using laser Doppler vibrometry.  

Science.gov (United States)

The objective of this study was to measure the velocity of the superior surface of human vocal folds during phonation using laser Doppler vibrometry (LDV). A custom-made endoscopic laser beam deflection unit was designed and fabricated. An in vivo clinical experimental procedure was developed to simultaneously collect LDV velocity and video from videolaryngoscopy. The velocity along the direction of the laser beam, i.e., the inferior-superior direction, was captured. The velocity was synchronous with electroglottograph and sound level meter data. The vibration energy of the vocal folds was determined to be significant up to a frequency of 3 kHz. Three characteristic vibrational waveforms were identified which may indicate bifurcations between vibrational modes of the mucosal wave. No relationship was found between the velocity amplitude and phonation frequency or sound pressure level. A correlation was found between the peak-to-peak displacement amplitude and phonation frequency. A sparse map of the velocity amplitudes on the vocal fold surface was obtained. PMID:23464036

Chan, Alfred; Mongeau, Luc; Kost, Karen

2013-03-01

61

Laser doppler techniques for sizing particulate pollutants and therapeutic aerosols  

Science.gov (United States)

A particle size analyzer based on laser Doppler velocimetry has been developed for measuring, in real time, the aerodynamic size distribution of aerosol particulates in the respirable range 0.1 to 10.0 ?m in diameter. The instrument, a single particle aerodynamic relaxation time analyzer, measures the aerodynamic relaxation time of individual suspended particles and droplets without removing the particulates from their aerosol phase. Measurements can be made at a maximum count rate of 200 particles/sec, although coincidence error restricts the count rate to a lower limit. The size resolution is within ±5% of the measured aerodynamic diameter. Currently, three prototype SPART analyzers are being used for: (1) studying aerodynamic size distribution and lung retention of therapeutic aerosols, (2) measuring fractional efficiency of electrostatic precipitators as a function of size and electrical resistivity of flyash particles, and (3) characterizing atmospheric and household aerosols.

Mazumder, M. K.; Hiller, F. C.; Ware, R. E.; Wilson, J. D.; McLeod, P. C.

1980-12-01

62

Short-time Fourier transform laser Doppler holography  

CERN Document Server

We report a demonstration of laser Doppler holography at a sustained acquisition rate of 250 Hz on a 1 Megapixel complementary metal-oxide-semiconductor (CMOS) sensor array and image display at 10 Hz frame rate. The holograms are optically acquired in off-axis configuration, with a frequency-shifted reference beam. Wide-field imaging of optical fluctuations in a 250 Hz frequency band is achieved by turning time-domain samplings to the dual domain via short-time temporal Fourier transformation. The measurement band can be positioned freely within the low radio-frequency spectrum by tuning the frequency of the reference beam in real-time. Video-rate image rendering is achieved by streamline image processing with commodity computer graphics hardware. This experimental scheme is validated by a non-contact vibrometry experiment.

Atlan, Michael

2012-01-01

63

Chopper stabilized laser-Doppler skin blood velocimeter  

Science.gov (United States)

Laser-Doppler velocimetry (LDV) is an established technique for noninvasive monitoring of skin blood flow. The LDV is based on the interference between the photons scattered from the moving red cells and the surrounding stationary tissue. In this work we have developed a new chopper stabilized LDV method. The light bema from the 10 mW HeNe laser was pulsed by a mechanical chopper at a frequency of 130 Hz. The light pulses backscattered from the skin were measured by a dual PIN photodiode electrometer amplifier. In the Fourier spectrum the chopper 130 Hz + harmonics peaks were dominating. The width of the peaks was diminished when measuring necrotic skin areas. The interference signal was demodulated by multiplying the measured pulsed signal by the chopper waveform. The resulting LDV spectra had a negligible amount of electrical distortion. The main advantage of the chopper stabilization is that pulse modulation concentrates the signal power near the chopper frequencies, which are free of electrical 50 Hz + harmonics pick-up.

Olkkonen, Hannu

1993-06-01

64

Laser Doppler vibrometry with a single-frequency microchip green laser  

International Nuclear Information System (INIS)

We have developed a laser vibrometer based on an Nd:YVO4/YVO4/KTP monolithic single-frequency green laser operating at 532 nm, with a narrow linewidth of radiation. Two configurations of the laser Doppler vibrometer have been investigated—with the so-called single- and double-frequency Bragg shifts. Measurement of heterodyne signals as a mixing result of scattered and reference beams has been carried out. In both configurations we have obtained signals with a high S/N ratio of >30 dB with resolution bandwidth = 200 kHz for a vibrometer output power of 3 mW. In our opinion, stable single-frequency solid-state green lasers provide new opportunities for the development of miniature laser vibrometry

65

Cramér–Rao lower bound of laser Doppler measurements at moving rough surfaces  

International Nuclear Information System (INIS)

Laser Doppler techniques are widely used for measuring both fluid flows and moving solid surfaces. The measurement uncertainty of laser Doppler sensors is fundamentally limited by the uncertainty of the Doppler frequency estimation. Generally, the minimum achievable uncertainty of any unbiased estimator is given by the Cramér–Rao lower bound (CRLB). While the CRLB is well known for laser Doppler burst signals of single tracer particles used in flow research, no analytical expression for the CRLB has been known up to now for scattered light signals of rough solid surfaces where speckle effects occur. Therefore, the aim of this paper is to close this gap and to provide a simple analytical expression for the CRLB for the Doppler frequency estimation from scattered light signals of moving rough solid surfaces for the first time. A comparison with experimental data demonstrates the validity of the derived analytical CRLB formula, which is also proven to be consistent with previous works. The progress for science is that this analytical CRLB formula enables both an easy estimation of the minimum achievable uncertainty of laser Doppler measurements at moving rough surfaces and a direct analysis of the influences of certain system and signal parameters on the measurement uncertainty. This reveals specific measuring features and capabilities of different laser Doppler techniques. In addition, the CRLB is a valuable tool to evaluate the efficiency of applied signal processing techniques

66

Diagnostic accuracy of laser Doppler flowmetry versus strain gauge plethysmography for segmental pressure measurement  

DEFF Research Database (Denmark)

To assess the diagnostic accuracy of laser Doppler flowmetry (LDF) with mercury-in-silastic strain gauge plethysmography (SGP) as a reference test for measuring the toe and ankle pressures in patients with known or suspected peripheral arterial disease (PAD).

HØyer, Christian; Sandermann, Jes

2013-01-01

67

Routine use of laser Doppler flowmetry for monitoring autologous tissue transplants.  

Science.gov (United States)

This is a report of a prospective study in which 41 consecutive autologous tissue transplants were monitored using the Laserflo BPM model 403 laser Doppler monitor (TSI Inc., St. Paul, MN). Flaps were monitored both intraoperatively and postoperatively, and clinical flap monitoring was compared with laser Doppler monitoring. Twenty-nine flaps had no problems as indicated by clinical or Doppler measurement. Twelve flaps underwent 13 reexplorations; one flap was explored twice. Five venous and five arterial anastomoses were corrected, with complete survival of the flaps. Three hematomas were evacuated. Two of these flaps failed. There were no instances where the laser Doppler indicated a problem with flap viability that subsequently did not merit reexploration. There were no instances of flap failure undetected by the laser Doppler. In comparison to the clinical monitoring, laser Doppler monitoring was more rapid and more precise in identifying problems with the flap. The use of this monitor has improved our salvage rate for flap reexploration from 50 to 85% and has provided a more objective standard for both nurses and physicians to evaluate flaps in the perioperative period. PMID:3069034

Jenkins, S; Sepka, R; Barwick, W J

1988-11-01

68

TVO-Flowmeter  

International Nuclear Information System (INIS)

TVO-flowmeter has been field tested in boreholes in the crystalline bedrock. It is possible to measure the groundwater flow both across and along a borehole. Sensitivity is better than 1 ml/h (milliliter per hour) for the flow across the hole. This corresponds the flux value (Darcy velocity) of about 2*10-9 m/s. The system makes it possible to determine roughly the direction of the flow across the hole. The boreholes in the bedrock change flow conditions. The effects of the borehole and flowmeter-borehole combination are studied by theoretical models. Field examples are presented from flows along and across the hole. The sensitivity of the instrument is demonstrated. Several repeated measurements are presented. Examples are shown of the variation of the flow with time

69

Dead time effects in laser Doppler anemometry measurements  

DEFF Research Database (Denmark)

We present velocity power spectra computed by the so-called direct method from burst-type laser Doppler anemometer (LDA) data, both measured in a turbulent round jet and generated in a computer. Using today’s powerful computers, we have been able to study more properties of the computed spectra than was previously possible, and we noted some unexpected features of the spectra that we now attribute to the unavoidable influence of a finite measurement volume (MV). The most prominent effect, which initially triggered these studies, was the appearance of damped oscillations in the higher frequency range, starting around the cutoff frequency due to the finite size of the MV. Using computer-generated data mimicking the LDA data, these effects have previously been shown to appear due to the effect of dead time, i.e., the finite time during which the system is not able to acquire new measurements. These dead times can be traced back to the fact that the burst-mode LDA cannot measure more than one signal burst at a time. Since the dead time is approximately equal to the residence time for a particle traversing a measurement volume, we are dealing with widely varying dead times, which, however, are assumed to be measured for each data point. In addition, the detector and processor used in the current study introduce a certain amount of fixed processing and data transfer times, which further contribute to the distortion of the computed spectrum. However, we show an excellent agreement between a measured spectrum and our modeled LDA data, thereby confirming the validity of our model for the LDA burst processor.

Velte, Clara Marika; Buchhave, Preben

2014-01-01

70

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

Czech Academy of Sciences Publication Activity Database

Liberec, 2014 - (Dan?ová, P.; Vít, T.), s. 71-77 [Experimental Fluid Mechanics 2014. ?eský Krumlov (CZ), 18.11.2014-21.11.2014] R&D Projects: GA ?R GA14-08888S Institutional support: RVO:61388998 Keywords : synthetic jet * laser Doppler vibrometry * laser induced fluorescence Subject RIV: BJ - Thermodynamics

Brou?ková, Zuzana; Vít, T.; Trávní?ek, Zden?k

71

Optical design for laser Doppler angular encoder with sub-nanoradian sensitivity  

Energy Technology Data Exchange (ETDEWEB)

A novel laser angular encoder system has been developed based on the principles of radar, the Doppler effect, optical heterodyning, and self aligning multiple reflection optics. Using this novel three dimensional multiple reflection optical path, a 10 to 20 times better resolution has been reached compared to commercially available laser Doppler displacement meters or laser interferometer systems. With the new angular encoder, sub-nanoradian resolution has been attained in the 8 degree measuring range in a compact setup about 60 mm (H) x 150 mm (W) x 370 mm (L) in size for high energy resolution applications at the Advanced Photon Source undulator beamline 3-ID.

Shu, D.; Alp, E.E.; Barraza, J.; Kuzay, T.M.; Mooney, T.

1997-09-01

72

Optical design for laser Doppler angular encoder with sub-nanoradian sensitivity  

International Nuclear Information System (INIS)

A novel laser angular encoder system has been developed based on the principles of radar, the Doppler effect, optical heterodyning, and self aligning multiple reflection optics. Using this novel three dimensional multiple reflection optical path, a 10 to 20 times better resolution has been reached compared to commercially available laser Doppler displacement meters or laser interferometer systems. With the new angular encoder, sub-nanoradian resolution has been attained in the 8 degree measuring range in a compact setup about 60 mm (H) x 150 mm (W) x 370 mm (L) in size for high energy resolution applications at the Advanced Photon Source undulator beamline 3-ID

73

Laser-diode based 10MHz photoacoustic Doppler flowmetry at 830 nm  

Science.gov (United States)

Photoacoustic Doppler Flowmetry has several potential advantages over its purely acoustical counterpart. The key ones are better inherent contrast and potential molecular information. It is therefore highly desired to continue to develop this modality into a viable complementary tool alongside with Doppler Ultrasound flowmetry. Working towards this goal we have constructed a Photoacoustic Doppler setup based on a combined pair of laser diodes at 830nm and a 10MHz focused acoustical transducer. Using tone-burst intensity modulation, depth-resolved Doppler spectrograms of a phantom vessel containing flowing suspension of carbon particles, were obtained. In order to investigate the conditions required for successful photoacoustic Doppler measurement in blood a k-space photoacoustic simulation was performed. It tested the photoacoustic response which is obtained for moving random spatial distributions of red blood cells and the effect of several parameters, such as particles density, ultrasonic frequency and optical spot size.

Sheinfeld, Adi; Eyal, Avishay

2012-02-01

74

Laser Doppler holographic microscopy in transmission: application to fish embryo imaging  

CERN Document Server

We have extended Laser Doppler holographic microscopy to transmission geometry. The technique is validated with living fish embryos imaged by a modified upright bio-microcope. By varying the frequency of the holographic reference beam, and the combination of frames used to calculate the hologram, multimodal imaging has been performed. Doppler images of the blood vessels for different Doppler shifts, images where the flow direction is coded in RGB colors or movies showing blood cells individual motion have been obtained as well. The ability to select the Fourier space zone that is used to calculate the signal, makes the method quantitative.

Verrier, Nicolas; Gross, Michel

2014-01-01

75

3-D laser Doppler velocimeter for use in high-speed flows  

International Nuclear Information System (INIS)

A description is given of a three-dimensional laser Doppler velocimeter system capable of measuring the cross-flow component directly while still using the nonorthogonal system. The Doppler frequency of the cross-flow component is obtained by appropriate electronic mixing and filtering of two other Doppler frequencies. Also described are some typical measurements of a three-dimensional boundary layer on a sharp cone at a small angle of attack in a Mach-3 flow using the new system. 15 references

76

Atmospheric transmission of CO2 laser radiation with application to laser Doppler systems  

Science.gov (United States)

The molecular absorption coefficients of carbon dioxide, water vapor, and nitrous oxide are calculated at the P16, P18, P20, P22, and P24 lines of the CO2 laser for temperatures from 200 to 300 K and for pressures from 100 to 1100 mb. The temperature variation of the continuum absorption coefficient of water vapor is taken into account semi-empirically from Burch's data. The total absorption coefficient from the present calculations falls within + or - 20 percent of the results of McClatchey and Selby. The transmission loss which the CO2 pulsed laser Doppler system experiences was calculated for flight test conditions for the five P-lines. The total transmission loss is approximately 7 percent higher at the P16 line and 10 percent lower at the P24 line compared to the P20 line. Comparison of the CO2 laser with HF and DF laser transmission reveals the P2(8) line at 3.8 micrometers of the DF laser is much better from the transmission point of view for altitudes below 10 km.

Murty, S. S. R.

1975-01-01

77

Time-resolved measurements with a vortex flowmeter in a pulsating turbulent flow using wavelet analysis  

International Nuclear Information System (INIS)

Vortex flowmeters are commonly employed in technical applications and are obtainable in a variety of commercially available types. However their robustness and accuracy can easily be impaired by environmental conditions, such as inflow disturbances and/or pulsating conditions. Various post-processing techniques of the vortex signal have been used, but all of these methods are so far targeted on obtaining an improved estimate of the time-averaged bulk velocity. Here, on the other hand, we propose, based on wavelet analysis, a straightforward way to utilize the signal from a vortex shedder to extract the time-resolved and thereby the phase-averaged velocity under pulsatile flow conditions. The method was verified with hot-wire and laser Doppler velocimetry measurements. (rapid communication)

78

Two-beam nonlinear Kerr effect to stabilize laser frequency with sub-Doppler resolution  

CERN Document Server

Avoiding laser frequency drifts is a key issue in many atomic physics experiments. Several techniques have been developed to lock the laser frequency using sub-Doppler dispersive atomic lineshapes as error signals in a feedback loop. We propose here a two-beam technique that uses non-linear properties of an atomic vapor around sharp resonances to produce sub-Doppler dispersive-like lineshapes that can be used as error signals. Our simple and robust technique has the advantage of not needing either modulation or magnetic fields.

Martins, Weliton Soares; de Silans, Thierry Passerat; Oriá, Marcos; Chevrollier, Martine; 10.1364/AO.51.005080

2012-01-01

79

Soap film gas flowmeter  

International Nuclear Information System (INIS)

A soap film gas flowmeter is described comprising: a flow tube having a hollow body with opposite open ends through which a soap film is propelled and a first closed chamber housing a soap solution. It also includes means for supporting the flow tube in a substantially vertical position with the open bottom end of the flow tube disposed in the first chamber above the soap solution; a second closed chamber into which the open top end of the flow tube extends and gas inlet means for introducing gas into the first chamber at a flow rate to be measured using the flowmeters. A gas exit means is included for discharging the gas introduced into the first chamber through the second chamber. Plus there are means for generating a single soap bubble from the soap solution substantially at the bottom end of the flow tube and a relatively large opening in the flowtube for providing an open passageway for inlet gas to pass through the flowtube when the bottom open end of the flowtube is covered by the soap solution

80

Reactor main steam flowmeter  

International Nuclear Information System (INIS)

The present invention intends to stabilize the measurement of a flowmeter disposed to a main steam pipe of a pressure vessel of a BWR type reactor. That is, the exit of the nozzle of the main steam pipe in the reactor pressure vessel comprises a gradually restricting portion, a throat portion and a diffusing portion. The position of the pressure detection terminal disposed downstream of the gradually restricting portion is below the pipeline of a flowmeter element, and condensates are stored in a pressure introduction pipeline succeeding to the pressure detection terminal. With such a constitution, when an accident of main steam pipe rupture should occur, the amount of steams jetted from the reactor pressure vessel to the reactor container, that is, the amount of loss of coolants can be reduced. As a result, the reactor container and the reactor building can be made compact and safe. Further, since a straight pipe, which has been necessary in an existent standard venturi type element, is no more necessary, the volume of the reactor container can be reduced. (I.S.)

81

Sub-Doppler Laser Cooling of Thulium Atoms in a Magneto-optical Trap  

CERN Document Server

We have experimentally studied sub-Doppler laser cooling in a magneto-optical trap for thulium atoms working at the wavelength of 410.6\\,nm. Without any dedicated molasses period of sub-Doppler cooling, the cloud of $3\\times 10^6$ atoms at the temperature of 25(5)\\,$\\mu$K was observed. The measured temperature is significantly lower than the Doppler limit of 240$\\mu$K for the cooling transition at 410.6\\,nm. High efficiency of the sub-Doppler cooling process is due to a near-degeneracy of the Land\\'e-$g$ factors of the lower $4f^{13}6s^{2}\\, (J\\,=\\,{7}/{2})$ and the upper $4f^{12}5d_{3/2}6s^{2}\\, (J\\,=\\,{9}/{2})$ cooling levels.}

Sukachev, D; Chebakov, K; Akimov, A; Kanorsky, S; Kolachevsky, N; Sorokin, V

2010-01-01

82

Development of CO2 laser Doppler instrumentation for detection of clear air turbulence, volume 1  

Science.gov (United States)

Modification, construction, test and operation of an advanced airborne carbon dioxide laser Doppler system for detecting clear air turbulence are described. The second generation CAT program and those auxiliary activities required to support and verify such a first-of-a-kind system are detailed: aircraft interface; ground and flight verification tests; data analysis; and laboratory examinations.

Harris, C. E.; Jelalian, A. V.

1979-01-01

83

Experimental data base of turbulent flow in rod bundles using laser doppler velocimeter  

International Nuclear Information System (INIS)

This report presents in detail the hydraulic characteristics measurements in subchannels of rod bundles using one-component LDV (Laser Doppler Velocimeter). In particular, this report presents the figures and tabulations of the resulting data. The detailed explanations about these results are shown in references publicated or presented at the conference. 4 kinds of experimental work were performed so far. (Author)

84

Velocity measurements of sputtered particles using the Laser-Doppler method  

International Nuclear Information System (INIS)

The development of tunable single frequency dye lasers has enabled the realization of a Doppler-Shift-Laser-Spectrometer (DSLS) for the detection and energy analysis of neutral sputtered particles. It is based on the Doppler-shifted resonance excitation by monochromatic radiation. The particle beam to be measured is intersected by two laser beams at 900 and 300 respectively. The laser is turned over a resonance line of the species to be investigated. The sharp non-Doppler-shifted 900 spectrum is used as zero marking on the velocity axis. The intensity of the Doppler-shifted 300 fluorescence spectrum is directly proportional to the particle intensity in the corresponding velocity interval. A high detection sensitivity of about 50 particles/cm3 and a velocity resolution of 50 m/s can be achieved. With the DSLS it is possible to investigate one particular kind of sputtered atoms with high resolution over a wide energy region. Results for different targets bombarded with rare gas ions are presented. The obtained spectra allow to determine the influence of slow thermal processes, thermal spikes and collision cascades to the sputtering process. A comparison with results obtained with time-of-flight experiments is given. (orig.)

85

Precise micro flow rate measurements by a laser Doppler velocity profile sensor with time division multiplexing  

International Nuclear Information System (INIS)

This paper presents the measurement of flow rate inside a microchannel by using a laser Doppler technique. For this application a novel laser Doppler velocity profile sensor has been developed. Instead of parallel fringe systems, two superposed fan-like fringe systems with opposite gradients are employed to determine the velocity distribution inside the microchannel directly. The sensor utilizes the time division multiplexing technique to discriminate both fringe systems. A velocity uncertainty of 0.18% and a spatial resolution of 960 nm are demonstrated in the flow, which is the highest spatially resolved measurement by a laser Doppler technique published to date. Flow rate measurements, in the range of 30 µl min?1, with a statistical uncertainty of 5 × 10?4 are further presented. In comparison to a reference, by precise weighing, the mean deviation between both measurement principles amounts to 1%. With the advantage of high spatial resolution with simultaneous low velocity uncertainty, the laser Doppler velocity profile sensor offers a new tool for microfluidic diagnostics, e.g. in lab-on-a-chip systems or for drug delivery, which requires very small flow rates

86

Electromagnetic flowmeters in multiphase flows  

OpenAIRE

The response of an Electromagnetic Flowmeter to a secondary, nonconducting phase in a continuous conducting phase is investigated. Experiments are carried out on a commercial 2" Foxboro flowmeter with sinusoidal mains field excitation and point electrodes. The main aspects which are looked for are the change in flow signal and transformer signal. A mathematical model is developed to simulate the effect of the nonconducting phase in. the form of single spherical particles. Th...

Krafft, Rainer

1993-01-01

87

Laser Doppler blood flow complementary metal oxide semiconductor imaging sensor with analog on-chip processing  

International Nuclear Information System (INIS)

A 4x4 pixel array with analog on-chip processing has been fabricated within a 0.35 ?m complementary metal oxide semiconductor process as a prototype sensor for laser Doppler blood flow imaging. At each pixel the bandpass and frequency weighted filters necessary for processing laser Doppler blood flow signals have been designed and fabricated. Because of the space constraints of implementing an accurate ?0.5 filter at the pixel level, this has been approximated using the ''roll off'' of a high-pass filter with a cutoff frequency set at 10 kHz. The sensor has been characterized using a modulated laser source. Fixed pattern noise is present that is demonstrated to be repeatable across the array and can be calibrated. Preliminary blood flow results on a finger before and after occlusion demonstrate that the sensor array provides the potential for a system that can be scaled to a larger number of pixels for blood flow imaging

88

Differential Laser Doppler based Non-Contact Sensor for Dimensional Inspection with Error Propagation Evaluation  

Directory of Open Access Journals (Sweden)

Full Text Available To achieve dynamic error compensation in CNC machine tools, a non-contactlaser probe capable of dimensional measurement of a workpiece while it is being machinedhas been developed and presented in this paper. The measurements are automatically fedback to the machine controller for intelligent error compensations. Based on a well resolvedlaser Doppler technique and real time data acquisition, the probe delivers a very promisingdimensional accuracy at few microns over a range of 100 mm. The developed opticalmeasuring apparatus employs a differential laser Doppler arrangement allowing acquisitionof information from the workpiece surface. In addition, the measurements are traceable tostandards of frequency allowing higher precision.

Ketsaya Vacharanukul

2006-06-01

89

1540-nm single frequency single-mode pulsed all fiber laser for coherent Doppler lidar  

Science.gov (United States)

A single-mode single frequency eye-safe pulsed all fiber laser based on master oscillator power amplification structure is presented. This laser is composed of a narrow linewidth distributed laser diode seed laser and two-stage cascade amplifiers. 0.8 m longitudinally gradient strained erbium/ytterbium co-doped polarization-maintaining fiber with a core diameter of 10 ?m is used as the gain fiber and two acoustic-optics modulators are adopted to enhance pulse extinction ratio. A peak power of 160 W and a pulse width of 200 ns at 10 kHz repetition rate are achieved with transform-limited linewidth and diffraction-limited beam quality. This laser will be employed in a compact short range coherent Doppler wind lidar.

Zhang, Xin; Diao, Weifeng; Liu, Yuan; Liu, Jiqiao; Hou, Xia; Chen, Weibiao

2015-02-01

90

A study of radial-flow turbomachinery blade vibration measurements using Eulerian laser Doppler vibrometry  

Science.gov (United States)

The structural integrity of blades is critical to the health of turbomachinery. Since operational failure of these blades can possibly lead to catastrophic failure of the machine, it is important to have knowledge of blade conditions in an online fashion. Due to several practical implications, it is desired to measure blade vibration with a non-contact technique. The application of laser Doppler vibrometry towards the vibration based condition monitoring of axial-flow turbomachinery blades has been successfully demonstrated in previous work. In this paper the feasibility of using laser Doppler vibrometry to measure radial-flow turbomachinery blade vibrations is investigated with the aid of digital image correlation and strain gauge telemetry.

Oberholster, A. J.; Heyns, P. S.

2014-05-01

91

Exploiting continuous scanning laser Doppler vibrometry (CSLDV) in time domain correlation methods for noise source identification  

Science.gov (United States)

This paper proposes the use of continuous scanning laser Doppler vibrometry (CSLDV) in time domain correlation techniques that aim at characterizing the structure-borne contributions of the noise emission of a mechanical system. The time domain correlation technique presented in this paper is based on the use of FIR (finite impulse response) filters obtained from the vibro-acoustic transfer matrix when vibration data are collected by laser Doppler vibrometry (LDV) exploited in continuous scan mode (CSLDV). The advantages, especially in terms of source decorrelation capabilities, related to the use of CSLDV for such purpose, with respect to standard discrete scan (SLDV), are discussed throughout the paper. To validate this approach, vibro-acoustic measurements were performed on a planetary gear motor for home appliances. The analysis of results is also supported by a simulation.

Chiariotti, Paolo; Martarelli, Milena; Revel, Gian Marco

2014-07-01

92

Parâmetros dopplervelocimétricos na avaliação da perviedade da anastomose portossistêmica intra-hepática transjugular (TIPS): estudo prospectivo / Doppler flowmeter parameters for evaluation of transjugular intrahepatic porto-systemic shunts (TIPS) patency: prospective study  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Estudar as alterações hemodinâmicas consideradas normais após a realização da anastomose portossistêmica intra-hepática transjugular (TIPS) e a eficácia dos parâmetros sugestivos de estenose do TIPS com o ultra-som Doppler. MATERIAIS E MÉTODOS: Dezesseis pacientes foram avaliados de maneir [...] a prospectiva, no período de dezembro de 2001 a março de 2003. As avaliações foram realizadas 24-48 horas após o TIPS e a seguir em intervalos regulares de 30 dias, três meses, seis meses e um ano, com ultra-som modo B, Doppler pulsado, Doppler colorido e de amplitude em diferentes pontos da prótese relacionados ao TIPS. A angiografia foi realizada apenas para a confirmação dos resultados e terapêutica pertinente. RESULTADOS: Até o momento apenas os achados de fluxo contínuo no terço proximal da prótese e o gradiente de velocidade entre dois pontos da prótese apresentaram significância estatística para o diagnóstico de estenose do TIPS (p Abstract in english OBJECTIVE: To assess the hemodynamic changes considered normal after transjugular intrahepatic porto-systemic shunt (TIPS) placement and the efficacy of TIPS parameters suggestive of stenosis using Doppler sonography. MATERIALS AND METHODS: Sixteen patients were prospectively evaluated from December [...] , 2001 to March, 2003 after TIPS placement. Evaluations were performed 24 to 48 hours after the procedure and then at intervals of 30 days, three months, six months and one year using B mode, color Doppler, power Doppler and spectral Doppler in different TIPS related sites. Angiography was performed only to confirm Doppler findings and treatment. RESULTS: To date the only statistically significant parameters for diagnosis of TIPS stenosis were continuous flow pattern in the proximal third of TIPS and the velocity gradient between the two sites (p

Antonio Sergio Zafred, Marcelino; Maria Cristina, Chammas; Ilka Regina Souza de, Oliveira; André Cosme de, Oliveira; Osvaldo Ignácio, Pereira; Francisco César, Carnevale; Osmar de Cássio, Saito; Giovanni Guido, Cerri.

2004-12-01

93

Measurement of the Doppler power of flowing blood using ultrasound Doppler devices.  

Science.gov (United States)

Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser-receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies. PMID:25542489

Huang, Chih-Chung; Chou, Hung-Lung; Chen, Pay-Yu

2015-02-01

94

Laser Doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing  

OpenAIRE

The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offe...

Cally Gill; Clough, Geraldine F.; Morgan, Stephen P.; Hayes-gill, Barrie R.; Crowe, John A.; Yiqun Zhu; Nguyen, Hoang C.; Diwei He

2013-01-01

95

Laser doppler myography (LDMi): A novel non-contact measurement method for the muscle activity  

OpenAIRE

Background and aims: Electromyography (EMG) is considered the gold-standard for the evaluation of muscle activity. Transversal and dimensional changes of the muscle, during muscle activity, generate vibrational phenomena which can be measured by Laser Doppler Vibrometry (LDVi). There is a relationship between muscle contraction and vibrational activity, therefore, some information on fundamental muscle parameters can be assessed without contact with LDVi. In this paper, we explore the possibi...

Scalise, L.; Casaccia, S.; Marchionni, P.; Ercoli, I.; Tomasini, Ep

2013-01-01

96

Determination of air and hydrofoil pressure coefficient by laser doppler anemometry  

OpenAIRE

Some results of experiments performed in water cavitation tunnel are presented. Pressure coefficient (Cp) was experimentally determined by Laser Doppler Anemometry (LDA) measurements. Two models were tested: model of airplane G4 (Super Galeb) and hydrofoil of high speed axial pump. These models are not prepared for conventional pressure measurements, so that LDA is applied for Cp determination. Numerical results were obtained using a code for average Navier-Stokes equations solutions. Compari...

Risti? Slavica S.; Puhari? Mirjana A.; Kutin Marina M.; Mati? Dušan R.

2010-01-01

97

Investigation of two-phase bubbly flows using laser doppler anemometry  

OpenAIRE

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 was applied to a turbulen...

Marie?, Jean-louis

1983-01-01

98

Laser Doppler flowmetry signals to quantify effects of isoflurane on the peripheral cardiovascular system of healthy rats  

Science.gov (United States)

The optical Doppler effect resulting from interactions between laser light photons and red blood cells of the microcirculation is used to characterize the influence of isoflurane, an halogenated volatile anesthetic, on the peripheral cardiovascular system. After having recorded laser Doppler flowmetry blood perfusion signals on isoflurane-induced anesthetized healthy rats, wavelet analyses show a significant decrease of the myogenic and neurogenic activities when isoflurane dose increases from 1.5% to 3%. Moreover, the approximate entropy shows a weak decrease of signal irregularity when dose of isoflurane increases. These findings demonstrate the usefulness of the optical Doppler effect in physiological and pharmacological applications.

Humeau, Anne; Fizanne, Lionel; Roux, Jérôme; Asfar, Pierre; Cales, Paul; Rousseau, David; Chapeau-Blondeau, François

2007-12-01

99

Comparative study of the performance of semiconductor laser based coherent Doppler lidars  

DEFF Research Database (Denmark)

Coherent Doppler Lidars (CDLs), operating at an eye-safe 1.5-micron wavelength, have found promising applications in the optimization of wind-power production. To meet the wind-energy sector's impending demand for more cost-efficient industrial sensors, we have focused on the development of continuous-wave CDL systems using compact, inexpensive semiconductor laser (SL) sources. In this work, we compare the performance of two candidate emitters for an allsemiconductor CDL system: (1) a monolithic master-oscillator-power-amplifier (MOPA) SL and (2) an external-cavity tapered diode laser (ECTDL).

Rodrigo, Peter John; Pedersen, Christian

2012-01-01

100

[Doppler effect on width of characteristic line in plasma induced by pulsed laser ablating Al].  

Science.gov (United States)

Aluminum (Al) plasma was induced with a pulsed Nd: YAG laser beam ablating Al target in Ar. Time-resolved information of the plasma radiation was taken with time-resolved technique, and the spectra of the radiation were recorded with an optical multi-path analyzer (OMA III ), whereupon, time-resolved spectra of the plasma radiation induced by pulsed laser were acquired. Based on the experiment data, Al resonant double lines, Al I 396.15 nm, Al I 394.40 nm, were respectively fitted with Lorentz, Gauss and their linear integrated function (abbr. Integrated function), whereupon, Lorentz and Gauss elements were separated from the experiment data profile curve. By contrasting Lorentz with Gauss curve separated, it was found that the experiment curve mainly consisted of Lorentz element, a with little Gauss. By contrasting Lorentz with Integrated fitting curve for experiment data, a visual picture of the characteristic lines broadened by Doppler effect was exhibited. According to the visual picture, the increase of full half-high width of the characteristic line broadened by Doppler effect was estimated. It was about 2 x 10(-)3 -8 x 10(-3) nm, approximating the theoretical value 6.7 x 10(-)3 nm. As a result, Doppler effect on the width of characteristic lines in the plasma could be reasonably explained by curve fitting analysis and theoretical calculation. PMID:16128055

Song, Yi-Zhong; He, An-Zhi

2005-05-01

101

Medical diagnosis of the cardiovascular system on the carotid artery with IR laser Doppler vibrometer  

Science.gov (United States)

Laser Doppler Vibrometry (LDV) is known to be a possible diagnosis tool for many cardiac applications as the detection and monitoring of some important vital parameters (Heart Rate, Heart Rate Variability, Pulse Wave Velocity) in a non-contact and non-intrusive way. The technique has become known as Optical Vibrocardiography (VCG) i.e. by measuring the vibrations on the carotid artery or on the thorax [1-5]. The aim of the present study is to interpret the vibrational signal acquired from the carotid artery in relation to the electrocardiographic and hemodynamic aspects and to enable the extraction of further medical information relevant for diagnosis purpose. For the investigation an infrared (IR) Laser Doppler Vibrometer has been used. The acquired VCG signals have been processed and compared with the simultaneously acquired electrocardiogram and the color-coded Doppler sonogram. This has enabled a deeper understanding of the signature of the vibrational signal. Furthermore, in this paper, we also discuss the medical value of the VCG signal obtained from the carotid artery.

Mignanelli, Laura; Rembe, Christian; Kroschel, Kristian; Luik, Armin; Castellini, Paolo; Scalise, Lorenzo

2014-05-01

102

Laser Doppler semiconductor anemometry of vortex flow behind the vane wheel rotor of the water turbine  

Science.gov (United States)

For hydrodynamic examinations of the turbid three-phase streams with air bubbles and with a depth more than 500 mm for the first time it is developed 2D Laser Doppler Semiconductor Anemometer LADO5-LMZ. Anemometer signal processor base on > and new procedure of adaptive selection of Doppler frequency. Complex testing of method and measuring tools have been done. Outcomes of full-scale experiments on diagnostic of nonstationary flow behind the vane wheel rotor in draught tube of the Frensis water turbine are presented from optimum regimes of activity to forced. Water discharge which has been calculated from water turbine universal performance model and calculated by measuring axial velocity profiles was compared. It is shown that the maximum aggregate error of definition of the consumption does not exceed 5%.

Meledin, V.; Anikin, Yu.; Bakakin, G.; Glavniy, V.; Dvoinishnikov, S.; Kulikov, D.; Naumov, I.; Okulov, V.; Pavlov, V.; Rakhmanov, V.; Sadbakov, O.; Mostovskiy, N.; Ilyin, S.

2006-05-01

103

A source of error in the velocity measurement of large spherical bubbles using laser Doppler anemometry  

International Nuclear Information System (INIS)

This article reports a source of error in the velocity measurements of large spherical bubbles by laser Doppler anemometry. Experimental evidences gathered in Poiseuille bubbly flows, as well as on controlled bubble streets, show that, for a detector at a 90 deg. viewing angle, the velocity of millimeter size spherical bubbles can be underestimated by 15%. Such a bias is shown to arise from the interaction on the receiver of two optical contributions, one from external reflection and one from internal reflection, produced from the same bubble. Their combination leads to alterations of the Doppler frequency inside a burst, and hence, to improper velocity measurements. An analysis based on geometrical optics indicates that such a combination is possible only for a ratio of the probe volume to the bubble diameter larger than unity. Such a conclusion is supported by careful experiments. Finally, simple ways of avoiding this bias are proposed and validated

104

A novel laser doppler linear encoder using multiple-reflection optical design for high-resolution linear actuator.  

Energy Technology Data Exchange (ETDEWEB)

A novel laser Doppler linear encoder system (LDLE) has been developed at the Advanced Photon Source, Argonne National Laboratory. A self-aligning 3-D multiple-reflection optical design was used for the laser Doppler displacement meter (LDDM) to extend the encoder system resolution. The encoder is compact [about 70 mm(H) x 100 mm(W) x 250 mm(L)] and it has sub-Angstrom resolution, 100 mm/sec measuring speed, and 300 mm measuring range. Because the new device affords higher resolution, as compared with commercial laser interferometer systems, and yet cost less, it will have good potential for use in scientific and industrial applications.

Shu, D.

1998-07-16

105

An in-vitro analysis of two laser Doppler flowmetry systems for evaluation of bone perfusion.  

Science.gov (United States)

Laser Doppler Flowmetry (LDF) has been shown to be a useful tool in the experimental and clinical measurement of bone blood flow. Two LDF receiving fiber channel systems, one with a 2mW He-Ne tube laser source and the other with an infrared diode laser source, were compared with specific reference to their light attenuation through three types of bone as well as their threshold thickness for the same specimens. The threshold thickness was higher for the infrared diode system for all three bone types whereas the attenuation was identical. The demonstrated differences were most likely due to the criteria established for flow detection; the infrared diode system has a greater degree of amplification of the output signal, yielding a higher value at each thickness of bone. The two systems will produce similar output data when used for experimental analysis of bone blood flow. PMID:2070276

Carpenter, G K; Swiontkowski, M F

1991-06-01

106

Experimental and clinical application of laser doppler flowmetry in gastric and duodenal ulcerative bleedings  

Directory of Open Access Journals (Sweden)

Full Text Available The research goal is to develop a new objective diagnostic method of prerecurrence syndrome that will prognose bleeding recurrence from gastroduodenal ulcers. Materials and methods. Method of laser Doppler flowmetry (LDF of the regional perfusion of tissue has been used. The experimental part has been done on 30 white laboratory rats. Characteristics of regional tissue perfusion in the simulation and laser hemostasis of bleeding have been studied. Gastroduodenal endoscopy has been performed with laser Doppler flowmetry (ELDF in clinical conditions to predict the recurrence of ulcerative bleeding. The prognostic method of gastroduodenal ulcerative bleeding was used in 58 patients hospitalized with such pathology and activity of bleeding Forrest II. Results. The study of microcirculation parameters and experimental hemostasis has showed the possibility of using LDF to measure its performance. Effective hemostasis has been accompanied by a significant decrease in perfusion. On the basis of microcirculation parameters in ulcerative bleeding, medical adrenaline test has been proposed for an objective verification pre-recurrence syndrome. To evaluate the effectiveness of endoscopic hemostasis perfusion has been measured before and after its implementation. Conclusion. ELDF has objectified the prognosis of ulcerative bleeding recurrence, verified pre-recurrence syndrome and evaluated the efficacy of endoscopic hemostasis

Afanasieva G.A.

2011-12-01

107

Monostatic coaxial 1.5 ?m laser Doppler velocimeter using a scanning Fabry-Perot interferometer  

DEFF Research Database (Denmark)

We present a laser Doppler velocimeter (LDV) in monostatic coaxial arrangement consisting of off-the-shelf telecom-grade components: a single frequency laser (wavelength ? = 1.5 ?m) and a high-finesse scanning Fabry-Perot interferometer (sFPI). In contrast to previous 1.5 ?m LDV systems based on heterodyne detection, our sFPI-LDV has the advantages of having large remote sensing range not limited by laser coherence, high velocity dynamic range not limited by detector bandwidth and inherent sign discrimination of Doppler shift. The more optically efficient coaxial arrangement where transmitter and receiver optics share a common axis reduces the number of components and greatly simplifies the optical alignment. However, the sensitivity to unwanted backreflections is increased. To circumvent this problem, we employ a custom optical circulator design which compared to commercial fiber-optic circulator achieves ~40 dB reduction in strength of unwanted reflections (i.e. leakage) while maintaining high optical efficiency. Experiments with a solid target demonstrate the performance of the sFPI-LDV system with high sensitivity down to pW level at present update rates up to 10 Hz.

Rodrigo, Peter John; Pedersen, Christian

2013-01-01

108

In vitro comparison of different signal processing algorithms used in laser Doppler flowmetry.  

Science.gov (United States)

The paper reports the results of investigations comparing the relative in vitro responses of different signal processing algorithms commonly employed in laser Doppler flowmetry (LDF). A versatile laser Doppler system is described which enabled complex signal processing to be implemented relatively simply using digital analysis. The flexibility of the system allowed a variety of processing algorithms to be studied by simply characterising the algorithm of interest under software control using a personal computer. An in vitro physical model is also presented which was used to maintain reproducible fluid flows. Flows of particles were studied in a physical model using both a near-infra-red (NIR) diode and an He/Ne laser source. The results show that frequency-weighted algorithms are responsive to both particle velocity and concentration, whereas non-weighted algorithms respond to concentration only. The linearity of the velocity response is critically dependent on both the dimensions of the in vitro model and the frequency bandwidth of the signal-processing algorithm. PMID:8326763

Obeid, A N

1993-01-01

109

Measurement of the resonance frequency of single bubbles using a laser Doppler vibrometer.  

Science.gov (United States)

The behavior of bubbles confined in tubes and channels is important in medical and industrial applications. In these small spaces, traditional means of experimentally observing bubble dynamics are often impossible or significantly perturb the system. A laser Doppler vibrometer (LDV) requires a narrow (bubble does not perturb its dynamics. LDV measurements of the resonance frequency of a bubble suspended in a small tank are presented to illustrate the utility of this measurement technique. The precision of the technique is similar to the precision of traditional acoustic techniques. PMID:18537297

Argo, Theodore F; Wilson, Preston S; Palan, Vikrant

2008-06-01

110

Measurement of turbulent flow using ultrasound velocity profile method. 2. Comparison with laser doppler velocimetry  

International Nuclear Information System (INIS)

Ultrasonic Velocity Profile (UVP) measuring method has many advantages over the conventional flow measurement methods, such as measurement of an instantaneous velocity profile on a line with the transducer was measured, and it is applicable to opaque liquids because of possible to measure from outside of the wall. This method has capabilities applicable to various flow measurements, but requires a large measurement volume. In this paper, the effect of the measurement volume on the mean velocity profile have been investigated for fully developed turbulent flows in a vertical pipe and was compared with a result obtained by Direct Numerical Simulation (DNS) and results of Laser Doppler Velocimetry (LDV) measurement. (author)

111

[Laser Doppler flowmetry in vital bone transplantation. Experimental and clinical results].  

Science.gov (United States)

Laser Doppler Flowmetry allows the measurement of the blood flow rate of different types of tissue. Rib on a muscle pedicle was compared with rib on a vascular pedicle in an animal experiment. The morphological results were compared with the LDF-results. During eleven clinical transfers of iliac crest bone grafts and one osteocutaneous scapular flap the blood flow values were measured intraoperatively before and after the transplantation. Postoperative monitoring was possible for 48 hours with the endoscopic probe and a screw implant. The blood flow of vascularized bone transplants is excellent and even rises post-operatively in some cases. PMID:3053364

Kärcher, H; Radner, H; Engler, J; Stenzl, A

1988-09-01

112

Measurement of velocity distributions in a 5 x 5-rod bundle by Laser-Doppler-anemometry  

International Nuclear Information System (INIS)

Measurements of velocity distributions in a 5x5-rod bundle consisting of original cladding tubes and segments of original PWR spacer grids were performed by Laser-Doppler-Anemometry. the test bundle was installed in a vertical square-section water channel. Two spacer grids with different lateral geometry were selected for the investigaitons. The tests produced detailed information on the velocity distribution in the rod bundle and in the peripheral zones in several axial levels between two spacer grids. The results were used to check and verify the Velasco and Thermohydraulik programs, which are used for thermohydraulic calculations in the PWR core and for the analysis of DNB tests. (orig.)

113

Efficient estimation of power spectral density from laser Doppler anemometer data  

Science.gov (United States)

A non-biased estimator of power spectral density (PSD) is introduced for data obtained from a zeroth order interpolated laser Doppler anemometer (LDA) data set. The systematic error, sometimes referred to as the ``particle-rate filter'' effect, is removed using an FIR filter parameterized using the mean particle rate. Independent from this, a procedure for estimating the measurement system noise is introduced and applied to the estimated spectra. The spectral estimation is performed in the domain of the autocorrelation function and assumes no further process parameters. The new technique is illustrated using simulated and measured data, in the latter case with direct comparison to simultaneously acquired hot-wire data.

Nobach, H.; Müller, E.; Tropea, C.

114

Laser Doppler vibrometry of the human middle ear: the technical point of view  

Science.gov (United States)

Laser-Doppler-vibrometry is used successfully to detect the motions of the tympanic membrane under normal hearing conditions. For more detailed information about the dynamical behavior of the middle ear, it is necessary to improve the experimental signal-to- noise-ratio, which is mainly determined by the amount of light coupled back into the interferometer. The paper focuses onto two possibilities to yield of this amount light by increasing the solid angle of the optics and increasing the reflectivity of the tympanic membrane.

Foth, Hans-Jochen; Brenner, Matthias; Stasche, Norbert; Hoermann, Karl

1995-03-01

115

Fast calibration of gas flowmeters  

Science.gov (United States)

Digital unit automates calibration sequence using calculator IC and programmable read-only memory to solve calibration equations. Infrared sensors start and stop calibration sequence. Instrument calibrates mass flowmeters or rotameters where flow measurement is based on mass or volume. This automatic control reduces operator time by 80 percent. Solid-state components are very reliable, and digital character allows system accuracy to be determined primarily by accuracy of transducers.

Lisle, R. V.; Wilson, T. L.

1981-01-01

116

Isotope shift in xenon by Doppler-free two-photon laser spectroscopy  

International Nuclear Information System (INIS)

Isotope shifts and pressure broadening have been measured in the two-photon transition at 249 nm from the 5p6 1So ground level of neutral xenon to a J = O level of the 5p56p configuration (the 2p5 level in Paschen notation). A continuous-wave tunable dye laser operating at 498 nm with intracavity frequency doubling excited the transition. The work is the first application of Doppler-free laser spectroscopy to a transition involving the ground level of a rare gas. The results show that although no s electron is directly involved in the transition, the field isotope shifts are comparable with those observed in transitions of the type 6s-np. (author)

117

Measuring the motions in the human middle ear by Laser Doppler Vibrometry  

Science.gov (United States)

For the detection of tiny motions which are caused by the tympanic membrane under normal hearing conditions, the touch-free method of Laser Doppler Vibrometry was used. Spectra containing information about the motions of the middle ear bones were recorded within 1 min when the umbo was chosen as the detection point and acoustic stimulation was performed via white noise excitation. It was observed that these spectra correlate to middle ear diseases, which had been artificially induced by manipulations in the chain of the middle ear bones in human temporal bones. The dosimetry of the applied laser radiation was found to be harmless to the tympanic membrane, which opened the way for successful in vivo measurements.

Foth, Hans-Jochen; Huthoff, Christian; Brenner, Matthias; Färber, Silke; Stasche, Norbert; Baker-Schreyer, Antonio; Hörmann, Karl

1996-11-01

118

Laser system for Doppler cooling of ytterbium ion in an optical frequency standard  

Science.gov (United States)

A laser system for Doppler cooling of ytterbium ion on the 2S1/2 ? 2P1/2 transition in a single-ion optical frequency standard is developed. The second harmonic of a semiconductor laser with a wavelength of 739 nm is used for cooling. The laser frequency is doubled in a nonlinear BiBO crystal embedded in a ring resonator, which also serves as a reference for laser frequency stabilisation. Second-harmonic power of ~100 ?W is generated at a wavelength of 369.5 nm. Diode laser radiation is modulated by an electro-optic modulator at 14.75 GHz to generate a sideband exciting the 2S1/2 (F = 0) ? 2P1/2 (F = 1) hyperfine component of the cooling transition that is not excited by resonant cooling light. The sideband relative intensity of a few percent proved to be sufficient to reduce the ion dwelling time in the 2S1/2 (F = 0) state to less than 10-4 s and increase the cooling efficiency.

Chepurov, S. V.; Lugovoy, A. A.; Kuznetsov, S. N.

2014-06-01

119

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

Science.gov (United States)

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 ?z = 140 nm. It allows precise in-situ shape measurements at grinding and turning processes.

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

2009-06-01

120

Fractal Dimension Characterization of in-vivo Laser Doppler Flowmetry signals  

Science.gov (United States)

Laser Doppler Blood Flow meter uses tissue backscattered light to non-invasively assess the blood flow rate. qualitatively. As there is large spatial variability and the temporal heterogeneity in tissue microvasculature, the measured blood flow rate is expressed in relative units. A non-linear approach in order to understand the dynamics of the microcirculation led to the fractal characterization of the blood flow signals. The study presented in the paper aims to analyze the fractal behavior of Laser Doppler Flow (LDF) signals and to quantitatively estimate the fractal dimension of waveforms using Box-Counting method. The measured Fractal dimension is an estimate of temporal variability of tissue perfusion. The rate at which fractal dimension varies as a function of location between individuals, exhibits a weak correlation with time. Further studies with a larger number of subjects are necessary to test the generality of the findings and if changes in dimension are reproducible in given individuals. In conclusion, the fractal dimension determined by Box-counting method may be useful for characterizing LDF time series signals. Future experiments evaluating whether the technique can be used to quantify microvascular dysfunction, as commonly occurring in conditions such as Diabetes, Raynaud's phenomenon, Erythromelalgia and Achenbach syndrome needs to be evaluated.

Srinivasan, Gayathri; Sujatha, N.

121

Agent-based station for on-line diagnostics by self-adaptive laser Doppler vibrometry  

Science.gov (United States)

A self-adaptive diagnostic system based on laser vibrometry is proposed for quality control of mechanical defects by vibration testing; it is developed for appliances at the end of an assembly line, but its characteristics are generally suited for testing most types of electromechanical products. It consists of a laser Doppler vibrometer, equipped with scanning mirrors and a camera, which implements self-adaptive bahaviour for optimizing the measurement. The system is conceived as a Quality Control Agent (QCA) and it is part of a Multi Agent System that supervises all the production line. The QCA behaviour is defined so to minimize measurement uncertainty during the on-line tests and to compensate target mis-positioning under guidance of a vision system. Best measurement conditions are reached by maximizing the amplitude of the optical Doppler beat signal (signal quality) and consequently minimize uncertainty. In this paper, the optimization strategy for measurement enhancement achieved by the down-hill algorithm (Nelder-Mead algorithm) and its effect on signal quality improvement is discussed. Tests on a washing machine in controlled operating conditions allow to evaluate the efficacy of the method; significant reduction of noise on vibration velocity spectra is observed. Results from on-line tests are presented, which demonstrate the potential of the system for industrial quality control.

Serafini, S.; Paone, N.; Castellini, P.

2013-12-01

122

Assessment of measurement efficiency in laser- and phase-Doppler techniques: an information theory approach  

International Nuclear Information System (INIS)

Laser- and phase-Doppler diagnostic techniques provide information on particle characteristics in the form of discrete probability distribution functions. Most methods assess the amount of information required for an accurate measurement through the first- and second-order moments of these distributions. However, considering that a measurement is the distribution and not its moments, a different approach is developed based on information theory (IT) concepts in order to assess if the information provided to the experimentalist is enough to ensure an accurate statistical analysis. The methodology and stopping criteria are presented and used in previously reported measurements obtained with laser- and phase-Doppler techniques. Results show that using an IT approach to assess the reliability of data provided by a measurement means evaluating the degree of stabilization of a discrete probability distribution, where more information acquired does not necessarily imply a more accurate measurement. The statistical analysis performed using the number of samples indicated by the IT method, compared to the total sample size previously measured, shows similar results. Moreover, measurement time is substantially reduced if the IT method is used, thus improving measurement efficiency. (paper)

123

Laser doppler flow imaging of open lower leg fractures in an animal experimental model.  

Directory of Open Access Journals (Sweden)

Full Text Available PURPOSE: Open lower leg fractures are frequently associated with severe soft tissue damage, followed by osteomyelitis. Using an animal experimental model, we investigated the effect of timing of coverage of a tibial fracture with a local muscle flap. METHODS: 80 rabbits had a tibial fracture induced in a standardised fashion, which was stabilised by screw osteosynthesis. After 3 (group A; n=40 and 7 days (group B; n=40, respectively, the tissue defect was covered by a local gastrocnemius flap. In increasing intervals from 1 to 2, 4, 8, and 16 weeks, the rabbits from each group were killed and the bone fracture was analysed histomorphologically. Cortical microcirculation was measured by 2-channel laser doppler flowmetry. RESULTS: Muscle flaps after 3 days improved perfusion significantly as compared with 7 days (24 Flux [standard error, 5 Flux] versus 10 Flux [3 Flux]; baseline, 1.4 Flux. Group A animals also displayed a lower rate of necrosis (0 versus 38. The incidence of osteomyelitis was higher in group B than in group A (24% versus 0%. CONCLUSION: Laser doppler flowmetry was proven to be a reliable, minimally invasive means for identifying avital tissue, leading to reduction in the loss of vital bone tissue in experimental settings.

Herzog L

2002-12-01

124

Simultaneous measurement of respiration and cardiac period in preterm infants by laser Doppler vibrometry  

Science.gov (United States)

The paper presents an optical non-contact method for simultaneous measurement of the heart beat and respiration period, based on the assessment of the chest wall movements induced by the pumping action of the heart, and by inspiration/expiration acts of the lungs. The measurement method is applied on 40 patients recovered in a Neonatal Intensive Care Unit (NICU), where the operating conditions are often critical and the contact with the patient's skin needs to be minimized. The method proposed is based on optical recording of the movements of chest wall by means of a laser Doppler vibrometer directly pointed onto the left, frontal part of the thoracic surface. Data measured were compared with reference instrumentation; to reach this goal, the ECG and Laser Doppler Vibrometer (LDV) signals were simultaneously acquired to monitor the heart period (HP), while to measure respiration period (RP) signals from a spirometer and a LDV were collected simultaneously. After LDV signals decomposition, heart and respiration acts were detected and compared in term of beat per minute (bpm). HPs measured by the proposed method showed an uncertainty heart and respiration rate also in critical, clinical environments such as the NICU.

Scalise, Lorenzo; Marchionni, Paolo; Ercoli, Ilaria; Tomasini, Enrico Primo

2012-06-01

125

Influence of intracavity doppler frequency shift in the swept-cavity ringdown spectroscopy incorporating continuous-wave laser excitation  

International Nuclear Information System (INIS)

Cavity ringdown spectroscopy (CRDS) with continuous-wave (cw) laser excitation has added high frequency resolution to the ability of CRDS being used for the absolute quantification of trace-level species present in many chemical processes. Cavity dithering technique has easily resolved the problem of resonant coupling of a cw laser light into a high-finesse cavity. The present study addresses the potential uncertainty involved in such cw-CRDS techniques incorporating the cavity mirror motion, i.e., the doppler frequency shift of a probe light inside the cavity. In the high-resolution spectroscopic work of megahertz-accuracy, even the influence of intracavity doppler effect may become significant.

126

Comparison of infrared and helium-neon lasers in the measurement of blood flow in human skin by the laser-Doppler technique.  

Science.gov (United States)

Histamine-induced changes in blood flow in normal human skin were assessed by laser-Doppler velocimetry using 2 lasers of different wavelengths: 780 nm infrared and 633 nm helium-neon. The visible flare response in skin was also measured by planimetry. Laser-Doppler velocimetry was shown to detect both the magnitude of the change in blood flow caused by histamine and also the extent of the changes in the skin. Both parameters were related to the dose of histamine, which ranged between 25 and 750 pmol/site. There was good correlation between the magnitude of the histamine-induced blood flow change and the extent of the response. The flare induced by histamine and measured by planimetry was similar in extent to the blood flow change recorded by laser-Doppler velocimetry. No difference in either the magnitude or the extent of blood flow changes in response to histamine, as measured by laser-Doppler velocimetry, were found when lasers of different wavelengths were used. PMID:1637563

Coulson, M L; Hayes, N A; Foreman, J C

1992-01-01

127

A comparison of measurements of cerebral blood flow in the rabbit using laser Doppler spectroscopy and radionuclide labelled microspheres.  

Science.gov (United States)

Laser Doppler spectroscopy has been evaluated for the measurement of cerebral blood flow (CBF) by correlation with simultaneous measurements by radionuclide labelled microspheres. The experimental procedures were carried out on five anaesthetised rabbits. The cortical tissue was exposed by means of a small burr hole and illuminated by a helium neon laser (632.8 nm). Reflected light was detected using a silicon photodiode, and CBF was calculated continuously from the power of the frequency weighted Doppler spectrum in the reflected light. Three successive measurements of CBF were made using the microsphere technique. Following an initial baseline measurement, CBF was increased by an infusion of metaraminol and then reduced by controlled haemorrhage. Laser Doppler spectroscopy provided continuous monitoring of blood flow fluctuations and during the haemorrhage it was possible to demonstrate CBF autoregulation until the mean blood pressure fell below 6.7 kPa (50 mmHg). A regression analysis was performed between the simultaneous CBF measurements from the two techniques using a least squares best fit straight line analysis (r = 0.92, P less than 0.001). It was concluded that the flow computed from laser Doppler spectroscopy varied linearly with CBF and offers the unique advantage of continuous and instantaneous measurements even during nonsteady state flow. PMID:2966027

Eyre, J A; Essex, T J; Flecknell, P A; Bartholomew, P H; Sinclair, J I

1988-02-01

128

Maximum-likelihood estimates of the frequency and other parameters of signals of laser Doppler measuring systems operating in the one-particle-scattering mode  

International Nuclear Information System (INIS)

Maximum-likelihood equations are presented for estimates of the Doppler frequency (speed) and other unknown parameters of signals of laser Doppler anemometers and lidars operating in the one-particle-scattering mode. Shot noise was assumed to be the main interfering factor of the problem. The error correlation matrix was calculated and the Rao - Cramer bounds were determined. The results are confirmed by the computer simulation of the Doppler signal and the numerical solution of the maximum-likelihood equations for the Doppler frequency. The obtained estimate is unbiased, and its dispersion coincides with the Rao-Cramer bound. (laser applications and other topics in quantum electronics)

129

Multi-beam laser Doppler vibrometry for acoustic landmine detection using airborne and mechanically coupled vibration  

Science.gov (United States)

Acoustic-to-seismic coupling-based technology using a multi-beam laser Doppler vibrometer (LDV) as a vibration sensor has proved itself as a potential confirmatory sensor for buried landmine detection. The multi-beam LDV simultaneously measures the vibration of the ground at 16 points spread over a 1-meter line. The multi-beam LDV was used in two modes of operation: stop-and-stare, and continuously scanning beams. The noise floor of measurements in the continuously scanning mode increased with increasing scanning speed. This increase in the velocity noise floor is caused by dynamic speckles. The influence of amplitude and phase fluctuations of the Doppler signal due to dynamic speckles on the phase locked loop (PLL) demodulated output is discussed in the paper. Either airborne sound or mechanical shakers can be used as a source to excite vibration of the ground. A specially-designed loudspeaker array and mechanical shakers were used in the frequency range from 85-2000 Hz to excite vibrations in the ground and elicit resonances in the mine. The efficiency of these two methods of excitation has been investigated and is discussed in the paper. This research is supported by the U. S. Army Research, Development, and Engineering Command, Night, Vision and Electronic Sensors Directorate under Contract DAAB15-02-C-0024.

Aranchuk, Vyacheslav; Sabatier, James M.; Lal, Amit K.; Hess, Cecil F.; Burgett, Richard D.; O'Neill, Michael

2005-06-01

130

Dual-frequency laser Doppler velocimeter for speckle noise reduction and coherence enhancement.  

Science.gov (United States)

We study the characteristics of a dual-frequency laser Doppler velocimeter (DF-LDV) based on an optically injected semiconductor laser. The laser operated in a period-one (P1) dynamical state with two optical frequencies separated by 11.25 GHz is used as the dual-frequency light source. With a microwave beat signal carried by the light, the DF-LDV possesses both the advantages of good directionality, high intensity, and high spatial resolution from the light and low speckle noise and good coherence from the microwave, respectively. By phase-locking the two frequency components with a microwave signal, the coherence of the dual-frequency light source can be further improved and the detection range can be much extended. In this paper, velocity resolutions of the DF-LDV with different amounts of speckle noise and at different detection ranges are experimentally measured and analyzed. Compared with the conventional single-frequency LDV (SF-LDV), the velocity resolution of the DF-LDV is improved by 8 × 10(3) times from 2.5 m/s to 0.31 mm/s for a target with a longitudinal velocity vz = 4 cm/s, a transverse velocity vt = 5 m/s, and at a detection range of 108 m. PMID:23037077

Cheng, Chih-Hao; Lee, Chia-Wei; Lin, Tzu-Wei; Lin, Fan-Yi

2012-08-27

131

A multi-point laser Doppler vibrometer with fiber-based configuration  

International Nuclear Information System (INIS)

Laser Doppler vibrometer (LDV) is a non-contact optical interferometric system to measure vibrations of structures and machines with a high precision. Normal LDV can only offer a single-point measurement. Scanning LDV is usually impractical to do measurement on transient events. In this paper, a fiber-based self-synchronized multi-point LDV is proposed. The multiple laser beams with different frequency shifts are generated from one laser source. The beams are projected onto a vibrating object, reflected and interfered with a common reference beam. The signal including vibration information of multiple spatial points is captured by one single-pixel photodetector. The optical system is mainly integrated by fiber components for flexibility in measurement. Two experiments are conducted to measure a steady-state simple harmonic vibration of a cantilever beam and a transient vibration of a beam clamped at both ends. In the first measurement, a numerical interpolation is applied to reconstruct the mode shape with increased number of data points. The vibration mode obtained is compared with that from FEM simulation. In transient vibration measurement, the first five resonant frequencies are obtained. The results show the new-reported fiber-based multipoint LDV can offer a vibration measurement on various spatial points simultaneously. With the flexibility of fiber configuration, it becomes more practical for dynamic structural evaluation in industrial areas

132

Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry  

CERN Document Server

In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a three dimensional laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limiting the fuel injection pressure. The vibrometer, which uses the Doppler effect to measure the velocity of a vibrating object, was used to scan injector nozzle tips during the injection event. The data were processed using a discrete Fourier transform to provide time-resolved spectra for valve-closed-orifice, minisac and microsac nozzle geometries, and injection pressures ranging from 60 to 160MPa, hence offering unprecedented insight into cyclic cavitation and internal mechanical dynamic processes. A peak was consistently f...

Crua, Cyril

2015-01-01

133

Elasticity Evaluation of Regenerating Cartilage Sample Based on Laser Doppler Measurement of Ultrasonic Particle Velocity  

Science.gov (United States)

It is important for regenerative medicine to evaluate the maturity of regenerating tissue. In the maturity evaluation of regenerating cartilage, it is useful to measure the temporal change of elasticity because the maturity of regenerating tissue is closely related to its elasticity. In this study, an elasticity evaluation method for the extracted regenerating cartilage sample, which is based on the laser Doppler measurement of ultrasonic particle velocity, was experimentally investigated using agar-based phantoms with different elastic moduli and the regenerating cartilage samples extracted from beagles in animal experiments. In addition, the experimentally-obtained elasticity was compared with the result of a static compression test. These results verified the feasibility of the proposed method in the elasticity evaluation of regenerating cartilage samples.

Nitta, Naotaka; Misawa, Masaki; Homma, Kazuhiro; Shiina, Tsuyoshi

2012-07-01

134

Ultrasonic characterization of materials by means of under water Laser Doppler Vibrometer measurements of continuous waves  

Science.gov (United States)

Pulse signals are widely use for several ultrasonic testing. They indeed allow an easy estimation of the delays occurring in echo and transmission measurements and give the possibility to filter the noise (i.e undesired reflections occurring in the surface of the transducers) applying a window in the time domain. However their high crest factor makes these signals unsuitable to test attenuating materials. For this reason this paper proposes a new method, based on continuous waves, for ultrasonic characterization of materials. A a wave propagation model in the frequency domain is presented, to determine simultaneously acoustic velocity, mass density, and thickness of two Plexiglas plates, during transmission experiments. The Ultrasonic waves are captured by a Scanning Laser Doppler Vibrometer (SLDV) in order to guarantee a large number of spatial points, acquired with a high resolution.

Longo, Roberto; Steenackers, Gunther; Vanlanduit, Steve; Guillaume, Patrick

2010-05-01

135

Accurate and precise calibration of AFM cantilever spring constants using laser Doppler vibrometry  

International Nuclear Information System (INIS)

Accurate cantilever spring constants are important in atomic force microscopy both in control of sensitive imaging and to provide correct nanomechanical property measurements. Conventional atomic force microscope (AFM) spring constant calibration techniques are usually performed in an AFM. They rely on significant handling and often require touching the cantilever probe tip to a surface to calibrate the optical lever sensitivity of the configuration. This can damage the tip. The thermal calibration technique developed for laser Doppler vibrometry (LDV) can be used to calibrate cantilevers without handling or touching the tip to a surface. Both flexural and torsional spring constants can be measured. Using both Euler–Bernoulli modeling and an SI traceable electrostatic force balance technique as a comparison we demonstrate that the LDV thermal technique is capable of providing rapid calibrations with a combination of ease, accuracy and precision beyond anything previously available. (paper)

136

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

DEFF Research Database (Denmark)

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

Ibsen, Claus Hübbe; Solberg, Tron

2002-01-01

137

Joint time-frequency analysis of tracking laser Doppler vibrometry data on a rolling tire  

Energy Technology Data Exchange (ETDEWEB)

The vibration analysis of a rolling tire is a very interesting but difficult task. To obtain realistic results on the dynamic characteristics of the tire, laboratory tests should be performed under simulated operative conditions, that is, when the tire is rolling. This task is not easy to achieve with traditional measurement techniques. In this paper tracking laser Doppler vibrometer (TLDV) has been applied for the measurement of time histories of the vibration velocity of a tire. A Lagrangian approach was adopted: data were acquired with the target in continuously changing conditions. In fact, the measurement point rotates with the tire and therefore it enters and exits from the contact area. In order to analyse vibration data, that are in an unsteady condition, a joint time-frequency analysis has been performed. Different algorithms have been compared and some preliminary results are shown in this work. (orig.)

Castellini, P. [Ancona Univ. (Italy). Dipt. di Meccanica; Montanini, R. [Messina Univ. (Italy). DCIIM

2001-07-01

138

Endoscopic laser Doppler flowmetry in the experiment and in the bleeding gastric and duodenal ulcer clinic  

Science.gov (United States)

One of the most complex problems of emergency surgery is the choice of surgical tactics to deal with bleeding peptic ulcer. Endoscopic hemostasis is prescribed to patients with continuing bleedings and prerelapse syndrome. But till nowdays the objective verification of the prerelapse condition had not been worked out. What is more there are no objective criteria to judge the effectiveness of the carried endohemostasis. The aim of the study was to work out a new objective diagnostic method of pre-recurrence syndrome that can be able to make prognosis for possible gastroduodenal ulcer bleeding recurrence more precise. Laser Doppler flowmetry was the method of studies the regional perfusion. The device used in this work was made at the Optics and Biophysics Department of Saratov State University.

Kapralov, S. V.; Shapkin, Y. G.; Lychagov, V. V.; Tuchin, V. V.

2007-05-01

139

An endoscopic laser Doppler flowmetry of a gastroduodenal mucosa at bleeding ulcer  

Science.gov (United States)

One of the important problems of a bleeding gastroduodenal ulcer surgery is a prognosis of the recurrent hemorrhage and appraisal of endoscopic hemostasis quality. Endoscopic Laser Doppler Flowmetry of a mucous coat of stomach and a duodenum was made on 34 patients for the purpose of investigation of features of microcirculation. Analogous researches are made on 30 patients with a peptic ulcer and on 28 practically healthy people. Analysis of LDF-grams has shown certain differences in regional microcirculations in stomach and duodenal at normal and at a pathology. Increase of regional perfusion in periulcerose zone with its pathology disbalance can serve as a criterion for activities of an alteration processes in gastroduodenal ulcer defining the risk of possible hemorrhage.

Shapkin, U. G.; Kapralov, C. V.; Gogolev, A. A.; Lychagov, V. V.; Tuchin, V. V.

2006-08-01

140

Development of a scanning head for laser Doppler vibrometry (LDV) using dual optical wedges.  

Science.gov (United States)

A new laser Doppler vibrometry scanning head is proposed based on a pair of rotating optical wedges. A comprehensive mathematical model is developed and used to demonstrate how the wedges can be configured to scan point-by-point, in a line, in a circle, and in a combination of the two such that a straight line scan could be performed on a structure during rotation. Inevitable misalignments are incorporated into the model and considered quantitatively for the circular tracking application. Certain advantages are apparent over systems based on dual mirrors and a Dove prism in terms of lower apparent velocities at low rotation orders. A scanning head design for the circular tracking application is presented, together with experimental data showing good agreement between predicted and measured apparent velocities caused by misalignments. PMID:24387409

Rothberg, S J; Tirabassi, M

2013-12-01

141

64×64 pixel smart sensor array for laser Doppler blood flow imaging.  

Science.gov (United States)

What is believed to be the first fully integrated two-dimensional complementary metal oxide semiconductor (CMOS) imaging array for laser Doppler blood flow imaging is demonstrated. The sensor has 64×64 pixels and includes both analog and digital on-chip processing electronics. This offers several potential advantages over commercial sensors as the processing is tailored to the signals of interest and the data bottleneck that exists between the sensor and processing electronics is overcome. To obtain a space efficient design over 64×64 pixels means that standard processing electronics used off-chip cannot be implemented. Images of both simulated blood flow responses and a blood flow occlusion test demonstrate the capability. PMID:22859085

He, D; Nguyen, H C; Hayes-Gill, B R; Zhu, Y; Crowe, J A; Clough, G F; Gill, C A; Morgan, S P

2012-08-01

142

Laser Doppler vibrometry for assessment of arteriosclerosis: A first step towards validation  

Science.gov (United States)

It has been shown that in cardiovascular risk management, stiffness of large arteries has a very good predictive value for cardiovascular disease and mortality. This parameter can be estimated from the pulse wave velocity (PWV) measured between the common carotid artery (CCA) in the neck and femoral artery (FA) in the groin. However PWV can also be measured locally in the CCA, using non-invasive methods such as ultrasound (US) or laser Doppler vibrometry (LDV). Potential of the latter approach was already explored in previous research, and in this work a first step towards clinical validation is made. 50 hypertension II/III patients aged between 30 and 65 participate in the study. Patients were asked to remain sober for 4 hours prior to the measurements. The trajectory of the CCA in the neck was determined by a trained clinician guided by an US probe. 3 laser Doppler vibrometer (LDV) systems were aimed along the CCA. PWV was then calculated from the distance between beams and the time-shift between waveforms. Immediately after LDV measurements, PWV was measured with US. Additionally, carotid-femoral PWV was measured. As a validation, PWV results of the different techniques were compared with each other, and with medical background of the test subjects. Since data acquisition is still ongoing, data from only 20 patients will be discussed. No trends between measurement methods for PWV are apparent. However, a positive trend was detected between PWV as measured with LDV and blood pressure. More data, including additional experiments will be needed to verify this observation.

Campo, Adriaan; Dirckx, Joris

2014-05-01

143

Kombineret laser Doppler flowmetri og spectrophotometri som metode til vurdering af mikrocirculation.  

DEFF Research Database (Denmark)

Kombineret laser Doppler flowmetri og spectrophotometri som metode til vurdering af mikrocirculation Berggren, MB, reservelæge, Karkirurgisk Afdeling, Kolding, mette.marie.berggren.olsen@slb.regionsyddanmark.dk; Houlind, K, lektor, afdelingslæge, Ph.d., Karkirurgisk afdeling, Kolding, kim.christian.houlind@slb.regionsyddanmark.dk; Sørensen, HB, lektor, speciallæge, Ph.d., Klinisk Institut, Århus Universitetshospital, hanne.Birke@ki.au.dk Foredragsholder: Berggren, MB, reservelæge, Karkirurgisk Afdeling, Kolding. Formål og baggrund: Postoperativ iskæmi er den største trussel mod autologe, mikrovaskulære transplantater. Da venøs occlusion er mere skadelig end arteriel, er det ønskeligt med en metode, som hurtigt og sikkert kan både afsløre og skelne mellem venøs og arteriel thrombose. O2C er en non-invasiv metode, som ved laser Doppler flowmetri og photospectroscopi måler flow, saturation, relativ hæmoglobin og flowhastighed i 2 og 8mm dybde. Tidligere in-vitro studier , indikerer, at metoden kan være et værdifuldt værktøj til monitorering af vævstransplantater, som giver mulighed for hurtigt at detektere vaskulære problemer, samt at skelne mellem venøs og arterielaflukning. Design: Deskriptivt, dyreeksperimentelt studie. Metoder: På 8 grise løftes højre og venstre rectusmuskel som fri lap og randomiseres til venøs eller arteriel okklusion. Der påsættes tang og på det relevante kar, og foretages O2C målinger hvert 5. min de første 30 min. og herefter hvert 15. min. Efter 3 timer fjernes tangen og der måles igen hvert 5. min. i 30 min. Data analyseres efterfølgende Vigtigste Variable: Ændringer i flow, hæmoglobin og saturation ved venøs og arteriel aflukning og reperfusion. Forventede resultater: Vi forventer at se, at en stigning i rHgb, samt et fald i flow og saturation i både 2 og 8mm dybde på lapperne med venøs obstruktion. På lapper med arteriel occlusion forventes et abrupt fald i flow og saturation. Såfremt ændringerne findes signifikante udregnes grænseværdier og SD.

Olsen, Mette Marie Berggreen; SØrensen, Hanne Birke

144

Laser Doppler vibrometry for assessment of arteriosclerosis: A first step towards validation  

Energy Technology Data Exchange (ETDEWEB)

It has been shown that in cardiovascular risk management, stiffness of large arteries has a very good predictive value for cardiovascular disease and mortality. This parameter can be estimated from the pulse wave velocity (PWV) measured between the common carotid artery (CCA) in the neck and femoral artery (FA) in the groin. However PWV can also be measured locally in the CCA, using non-invasive methods such as ultrasound (US) or laser Doppler vibrometry (LDV). Potential of the latter approach was already explored in previous research, and in this work a first step towards clinical validation is made. 50 hypertension II/III patients aged between 30 and 65 participate in the study. Patients were asked to remain sober for 4 hours prior to the measurements. The trajectory of the CCA in the neck was determined by a trained clinician guided by an US probe. 3 laser Doppler vibrometer (LDV) systems were aimed along the CCA. PWV was then calculated from the distance between beams and the time-shift between waveforms. Immediately after LDV measurements, PWV was measured with US. Additionally, carotid-femoral PWV was measured. As a validation, PWV results of the different techniques were compared with each other, and with medical background of the test subjects. Since data acquisition is still ongoing, data from only 20 patients will be discussed. No trends between measurement methods for PWV are apparent. However, a positive trend was detected between PWV as measured with LDV and blood pressure. More data, including additional experiments will be needed to verify this observation.

Campo, Adriaan; Dirckx, Joris [University of Antwerp, Laboratory of Biomedical Physics, Groenenborgerlaan 171 2020 Antwerp (Belgium)

2014-05-27

145

Efficient sub-Doppler transverse laser cooling of an indium atomic beam  

International Nuclear Information System (INIS)

Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at ?? = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5±3.8 cm/s yielding a full divergence of only 0.48 ± 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, ?-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two-color spectroscopy experiment. For the analysis of this atomic system, I have applied a density matrix theory providing an excellent basis for understanding the observed line shapes. (orig.)

146

Field performance of an all-semiconductor laser coherent Doppler lidar  

DEFF Research Database (Denmark)

We implement and test what, to our knowledge, is the first deployable coherent Doppler lidar (CDL) system based on a compact, inexpensive all-semiconductor laser (SL). To demonstrate the field performance of our SL-CDL remote sensor, we compare a 36 h time series of averaged radial wind speeds measured by our instrument at an 80 m distance to those simultaneously obtained from an industry-standard sonic anemometer (SA). An excellent degree of correlation (R2=0.994 and slope=0.996) is achieved from a linear regression analysis of the CDL versus SA wind speed data. The lidar system is capable of providing high data availability, ranging from 85% to 100% even under varying outdoor (temperature and humidity) conditions during the test period. We also show the use of our SL-CDL for monitoring the dependence of aerosol backscatter on relative humidity. This work points to the feasibility of a more general class of low-cost, portable remote sensors based on all-SL emitters for applications that require demanding laser stability and coherence.

Rodrigo, Peter John; Pedersen, Christian

2012-01-01

147

Laser Doppler field sensor for high resolution flow velocity imaging without camera  

International Nuclear Information System (INIS)

In this paper we present a laser sensor for highly spatially resolved flow imaging without using a camera. The sensor is an extension of the principle of laser Doppler anemometry (LDA). Instead of a parallel fringe system, diverging and converging fringes are employed. This method facilitates the determination of the tracer particle position within the measurement volume and leads to an increased spatial and velocity resolution compared to conventional LDA. Using a total number of four fringe systems the flow is resolved in two spatial dimensions and the orthogonal velocity component. Since no camera is used, the resolution of the sensor is not influenced by pixel size effects. A spatial resolution of 4 ?m in the x direction and 16 ?m in the y direction and a relative velocity resolution of 1x10-3 have been demonstrated up to now. As a first application we present the velocity measurement of an injection nozzle flow. The sensor is also highly suitable for applications in nano- and microfluidics, e.g., for the measurement of flow rates

148

Characterization and demonstration of a 12-channel Laser-Doppler vibrometer  

Science.gov (United States)

Scanning laser-Doppler vibrometry is the standard optical, non-contact technology for vibration measurement applications in all areas of mechanical engineering. The vibration signals are measured from the different measurement points at different time points. This requires synchronization and the technology is limited to repeatable or periodic events. We have explored a new solution for the optical setup of the sensing system of a multi-channel vibrometer that we present in this paper. Our optical system is a 12-channel vibrometer and consists of a 12-channel interferometer unit which is connected with 12 optical fibers to a sensor head with 12 fiber-coupled objective lenses. Every objective lens can be focused manually and is placed in a sphere which can be tilted and fixed by a blocking screw. Thus it is possible to adjust a user defined measurement grid by hand. The user can define the geometry of the measurement grid in a camera image displayed in the software by just clicking on the laser foci. We use synchronous analog-digital conversion for the 12 heterodyne detector signals and a digital 12-channel-demodulator which is connected via USB to a computer. We can realize high deflection angles, good sensitivity, proper resolution, sufficient vibration bandwidth, and high maximum vibration amplitudes. In this paper, we demonstrate the optical and electrical setup of the manually adjustable 12-channel vibrometer, we present the experimentally evaluated performance of our device, and we present first measurements from real automotive applications.

Haist, T.; Lingel, C.; Osten, W.; Bendel, K.; Giesen, M.; Gartner, M.; Rembe, C.

2013-04-01

149

Simple helium flowmeter for dilution refrigerators  

CERN Document Server

This flowmeter measures the molar flow rate of /sup 3/He and /sup 4/He gas, independently of pressure or isotopic composition. The principle is based on the constant C/sub p/. A calibration is needed for high accuracy.

Niinikoski, T O

1972-01-01

150

Flowmeter for pressure-driven chromatography systems  

Science.gov (United States)

A flowmeter for accurately measuring the flowrate of fluids in high pressure chromatography systems. The flowmeter is a porous bed of a material, the porous bed having a porosity in the range of about 0.1 to 0.6 and a pore size in the range of about 50 nm to 1 .mu.m, disposed between a high pressure pumping means and a chromatography column. The flowmeter is provided with pressure measuring means at both the inlet and outlet of the porous bed for measuring the pressure drop through the porous bed. This flowmeter system provides not only the ability to measure accurately flowrates in the range of .mu.L/min to nL/min but also to provide a signal that can be used for a servo loop or feedback control system for high pressure pumping systems.

Paul, Phillip H. (Livermore, CA); Arnold, Don W. (Livermore, CA)

2003-01-01

151

Nuclear magnetic resonance blood flowmeter  

International Nuclear Information System (INIS)

An improved nuclear magnetic resonance blood flowmeter is described for non-invasively measuring blood flow in a human limb comprising; polarizing magnet means for generating a substantially uniform magnetic field; a limb receiving lumen for supporting a human limb within the field generated by the polarizing magnet means so that blood molecules within the limb are magnetically polarized thereby; transmitter means located adjacent the lumen for inducing a nuclear magnetic resonance response in the blood molecules of the human limb disposed within the lumen; scanning means including: first means for generating a first pair of opposing magnetic fields within the lumen for cancelling the nuclear magnetic resonance response induced by the transmitter means everywhere except within a first null plane along which the first opposing magnetic fields cancel each other; second means for generating a second pair of opposing magnetic fields; and control means coupled to the first and second means for generating the first and second pair of opposing magnetic fields

152

Evaluation of endoscopic laser Doppler flowmetry for measurement of human gastric blood flow  

International Nuclear Information System (INIS)

Endoscopic measurement of gastric blood perfusion by laser Doppler flowmetry (LDF) has been evaluated in 28 patients and 15 healthy vounteers. During the recordings it was necessary to keep the probe in light contact with the mucosa to obtain stable curves and to avoid artificial Doppler signals caused by relative movements between the gastric wall and the probe. Gastric distention by air insufflation did not influence the recorded flow level significantly when air insufflation was moderate. The intravenous injection of 0.6 mg atropine did not cause any significant alteration in recorded blood flow, and this drug may be used as premedication before endoscopic blood flow measurements. Recordings with both 4 kHz and 12 kHz bandwidth of the LDF instruments showed a relative constant relationship for different flow levels, the flow values measured with 12 kHz being about twice the corresponding values measured with 4 kHz. With 12 kHz bandwith more of the disturbance signal is recorded, which makes analysis of endoscopic recorded flow curves difficult and inaccurate. It is therefore recommended to use 4 kHz bandwidth during endoscopic measurements in conscious humans. Blood flow measurements from both sides of the gastric wall were consistently of the same order of magnitude (r=0.91), and the endoscopically recorded output signal increased in three of five patients when a reflecting mirror was placed at the serosal side. The results indicate that endoscopic LDF usually reps indicate that endoscopic LDF usually represents blood perfusion in all layers of the gastric wall

153

Use of Wigner-Ville transformations for fluid particles in laser Doppler flow accelerometry  

International Nuclear Information System (INIS)

Flow acceleration with Lagrangian description is crucial to understanding particle movements in turbulent jet flows or dissipation statistics in isotropic turbulence. Laser Doppler anemometry is regarded as a suitable experimental tool for measuring flow acceleration, because scattering particles generate trajectories in the measurement volume, which process gives rise to flow acceleration at a fixed measuring point with the Lagrangian description. The most useful algorithm for processing Doppler signals is either the quadrature demodulation technique (QDT) or the iterative parametric method (alternatively, the minimization of least squares, LSM) as in the literature. In the present study, another algorithm using the Wigner-Ville transform (W-V) is introduced to give more accurate estimation of flow acceleration than the QDT or the LSM. Five signal-processing algorithms, including the QDT, the LSM, the MC (maximization of correlation), and the W-V, were compared with each other in experiments with an impinging air jet flow with a cylindrical rod and a round free-air jet flow. Mean flow acceleration distribution in the stream wise direction was mainly investigated. Processing speeds for the above-mentioned signal-processing algorithms were checked to find the best algorithm, which has best performance with short processing time. Although QDT was found to be an accurate algorithm with short processing time, it has limited applications to flows with large acceleration anations to flows with large acceleration and high SNR. The MC was also found to be a good algorithm with moderate processing speed, which can be useful in flows with low SNR because the MC is an iterative parametric method. The W-V gave the most accurate values for flow acceleration; however, the processing time for this method was the slowest among the signal-processing algorithms

154

Evaluation of algorithms for microperfusion assessment by fast simulations of laser Doppler power spectral density  

Science.gov (United States)

In classical laser Doppler (LD) perfusion measurements, zeroth- and first-order moments of the power spectral density of the LD signal are utilized for the calculation of a signal corresponding to the concentration, speed and flow of red blood cells (RBCs). We have analysed the nonlinearities of the moments in relation to RBC speed distributions, parameters of filters utilized in LD instruments and the signal-to-noise ratio. We have developed a new method for fast simulation of the spectrum of the LD signal. The method is based on a superposition of analytically calculated Doppler shift probability distributions derived for the assumed light scattering phase function. We have validated the method by a comparison of the analytically calculated spectra with results of Monte Carlo (MC) simulations. For the semi-infinite, homogeneous medium and the single Doppler scattering regime, the analytical calculation describes LD spectra with the same accuracy as the MC simulation. The method allows for simulating the LD signal in time domain and furthermore analysing the index of perfusion for the assumed wavelength of the light, optical properties of the tissue and concentration of RBCs. Fast simulations of the LD signal in time domain and its frequency spectrum can be utilized in applications where knowledge of the LD photocurrent is required, e.g. in the development of detectors for tissue microperfusion monitoring or in measurements of the LD autocorrelation function for perfusion measurements. The presented fast method for LD spectra calculation can be used as a tool for evaluation of signal processing algorithms used in the LD method and/or for the development of new algorithms of the LD flowmetry and imaging. We analysed LD spectra obtained by analytical calculations using a classical algorithm applied in classical LD perfusion measurements. We observed nonlinearity of the first moment M1 for low and high speeds of particles (v 10 mm s-1). It was also noted that the first moment M1 is less sensitive to the change of the mean RBC speed for flat speed distributions. The low-pass filter frequency f2 implemented in the LD instrument has a significant influence on the first moment of the spectrum. In particular, for a cut-off frequency lower than 10 kHz the M1 value is strongly underestimated.

Wojtkiewicz, S.; Liebert, A.; Rix, H.; Maniewski, R.

2011-12-01

155

Multi-channel laser Doppler velocimetry using a two-dimensional optical fiber array for obtaining instantaneous velocity distribution characteristics  

Science.gov (United States)

A laser Doppler velocimeter (LDV) has been developed that is capable of performing two-dimensional (2D) cross-sectional measurements. It employs two horizontal laser light sheets that intersect at an angle of 13.3°. Since the intersection region is thin, it can be used to approximately determine the 2D flow field. An 8 × 8 array of optical fibers is used to simultaneously measure Doppler frequencies at 64 points. Experiments were conducted to assess the performance of the LDV, and it was found to be capable of obtaining spatial and temporal velocity information at multiple points in a flow field. The technique is fast, noninvasive, and accurate over long sampling periods. Furthermore, its applicability to an actual flow field was confirmed by measuring the temporal velocity distribution of a pulsatile flow in a rectangular flow channel with an obstruction. The proposed device is thus a useful, compact optical instrument for conducting simultaneous 2D cross-sectional multipoint measurements.

Kyoden, Tomoaki; Yasue, Youichi; Ishida, Hiroki; Akiguchi, Shunsuke; Andoh, Tsugunobu; Takada, Yogo; Teranishi, Tsunenobu; Hachiga, Tadashi

2015-01-01

156

Laser-Doppler-Velocimetry on the basis of frequency selective absorption: set-up and test of a Doppler Gloval Velocimeter; Laser-Doppler-Velocimetry auf der Basis frequenzselektiver Absorption: Aufbau und Einsatz eines Doppler Global Velocimeters  

Energy Technology Data Exchange (ETDEWEB)

A Doppler Global Velocimeter was set up in the frame of a PhD thesis. This velocimeter is optimized to carry out high accuracy, three component, time averaged planar velocity measurements. The anemometer was successfully applied to wind tunnel and test rig flows, and the measurement accuracy was investigated. A volumetric data-set of the flow field inside an industrial combustion chamber was measured. This data field contained about 400.000 vectors. DGV measurements in the intake of a jet engine model were carried out applying a fibre bundle boroskope. The flow structure of the wake of a car model in a wind tunnel was investigated. The measurement accuracy of the DGV-System is {+-}0.5 m/s when operated under ideal conditions. This study can serve as a basis to evaluate the use of DGV for aerodynamic development experiments. (orig.) [German] Im Rahmen der Dissertation wurde ein auf hohe Messgenauigkeit optimiertes DGV-Geraet fuer zeitlich gemittelte Drei-Komponenten-Geschwindigkeitsmessungen entwickelt und gebaut, an Laborstroemungen, an Teststaenden und an Windkanaelen erfolgreich eingesetzt und das Potential der Messtechnik, insbesondere im Hinblick auf Messgenauigkeit, untersucht. Im Fall einer industriellen Brennkammer konnte ein Volumen-Datensatz des Stroemungsfeldes erstellt werden, dessen Umfang bei ca. 400.000 Vektoren lag. Es wurden DGV-Messungen mittels eines flexiblen Endoskops auf Basis eines Faserbuendels durchgefuehrt und damit die Stroemung in einem Flugzeugeinlauf vermessen. Es wurden DGV-Messungen im Nachlauf eines PKW-Modells in einem Windkanal durchgefuehrt. Die Messgenauigkeit des erstellten DGV-Systems betraegt unter Idealbedingungen {+-}0,5 m/s. Durch die Arbeit wurde eine Basis zur Beurteilung des Nutzens der DGV-Technik fuer aerodynamische Entwicklungsarbeiten geschaffen. (orig.)

Roehle, I.

1999-11-01

157

Pulse transit times to the capillary bed evaluated by laser Doppler flowmetry  

International Nuclear Information System (INIS)

The pulse transit time (PTT) of a wave over a specified distance along a blood vessel provides a simple non-invasive index that can be used for the evaluation of arterial distensibility. Current methods of measuring the PTT determine the propagation times of pulses only in the larger arteries. We have evaluated the pulse arrival time (PAT) to the capillary bed, through the microcirculation, and have investigated its relationship to the arterial PAT to a fingertip. To do so, we detected cardiac-induced pulse waves in skin microcirculation using laser Doppler flowmetry (LDF). Using the ECG as a reference, PATs to the microcirculation were measured on the four extremities of 108 healthy subjects. Simultaneously, PATs to the radial artery of the left index finger were obtained from blood pressure recordings using a piezoelectric sensor. Both PATs correlate in similar ways with heart rate and age. That to the microcirculation is shown to be sensitive to local changes in skin perfusion induced by cooling. We introduce a measure for the PTT through the microcirculation. We conclude that a combination of LDF and pressure measurements enables simultaneous characterization of the states of the macro and microvasculature. Information about the microcirculation, including an assessment of endothelial function, may be obtained from the responses to perturbations in skin perfusion, such as temperature stress or vasoactive substances

158

V-belt transverse vibration measurement by means of laser Doppler vibrometry  

Science.gov (United States)

The dynamic behaviour of a power transmission V-belt system with two fixed pulleys has been analysed by applying the theory of the forced non-linear response of a moving string driven harmonically by eccentrically mounted pulleys. The model has been validated experimentally with reference data obtained by measuring out-of plane components of the belt vibration. The experimental data have been acquired by means of a single-point laser Doppler vibrometer (LDV), measuring the transverse vibration of the belt. Another experimentally technique applied here, for transverse vibration acquisition, was the continuous scanning LDV (CSLDV) that has been used for the first time in translating objects. From the model and the measurements, it has been found that the frequency crossing diagrams, analogous to the so-called Campbell plot used in rotating machinery, perfectly agree. Essentially, this plot demonstrates that the natural frequencies are strongly dependent on the belt's transport speed. Consequently, the model can be employed as useful tool for identifying the transport speeds at which resonances are expected.

Agnani, A.; Martarelli, M.; Tomasini, E. P.

2008-06-01

159

Loss of contact sensitization evaluated by laser Doppler blood flowmetry and transepidermal water loss measurement.  

Science.gov (United States)

Allergic contact dermatitis, which is mediated by activated T cells through a Type IV reaction, is usually believed to persist throughout life. There have been several reports of spontaneous loss of sensitization, e.g., loss of previous patch test reaction or loss of allergic contact dermatitis withal continuous exposure to the allergens. However, these have been well quantified. The aim of this study was to confirm the development of desensitization or hyposensitization with the aid of objective measurements. A total of 18 patients with alopecia areata, who received 4 months diphenylcyclopropenone (DPCP) contact immunotherapy, were patch tested and the responses were measured by laser Doppler blood flowmetry (LDF) and transepidermal water loss (TEWL). Patch tests were performed 2X, before and after 4 months of immunotherapy. To determine whether local desensitization developed, we compared change of DPCP concentrations producing mild contact dermatitis on the scalp. Our results showed that systemic and local hyposensitization occurred in human subjects by weekly applications of low concentrations of DPCP for 4 months. LDF seems to be more correlated with visual scores than TEWL measurement. PMID:8730158

Seo, K I; Eun, H C

1996-04-01

160

Laser Doppler Blood Flow Imaging Using a CMOS Imaging Sensor with On-Chip Signal Processing  

Directory of Open Access Journals (Sweden)

Full Text Available The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue.

Cally Gill

2013-09-01

161

Estimation of scattering phase function utilizing laser Doppler power density spectra  

International Nuclear Information System (INIS)

A new method for the estimation of the light scattering phase function of particles is presented. The method allows us to measure the light scattering phase function of particles of any shape in the full angular range (0°–180°) and is based on the analysis of laser Doppler (LD) power density spectra. The theoretical background of the method and results of its validation using data from Monte Carlo simulations will be presented. For the estimation of the scattering phase function, a phantom measurement setup is proposed containing a LD measurement system and a simple model in which a liquid sample flows through a glass tube fixed in an optically turbid material. The scattering phase function estimation error was thoroughly investigated in relation to the light scattering anisotropy factor g. The error of g estimation is lower than 10% for anisotropy factors larger than 0.5 and decreases with increase of the anisotropy factor (e.g. for g = 0.98, the error of estimation is 0.01%). The analysis of influence of the noise in the measured LD spectrum showed that the g estimation error is lower than 1% for signal to noise ratio higher than 50 dB. (paper)

162

Serial assessment of laser Doppler flow during acute pain crises in sickle cell disease.  

Science.gov (United States)

Changes in basal laser Doppler flowmetry (LDF) of skin blood flow in sickle cell disease are reported to have pathophysiologic relevance in pain crisis. This is the first study to strictly control for LDF variability in determining the value of serial, basal (unprovoked) skin LDF as a practical method to assess resolution of acute pain crisis in sickle cell patients. Daily LDF measurements were repeated on the exact same skin areas of the calf and forehead throughout each of 12 hospital admissions for uncomplicated acute pain crisis. A progressive increase in perfusion was observed in the calf throughout hospitalization as pain crisis resolved, but measurement reproducibility in the calf was poor. Reproducibility in the forehead was better, but no significant trend over time in perfusion was seen. There was no significant correlation between perfusion and pain scores over time. There was also no significant pattern of LDF oscillations over time. In conclusion, only perfusion units and not oscillatory patterns of LDF have probable pathophysiological significance in sickle cell disease vaso-occlusion. The reproducibility of basal skin LDF specifically in sickle cell disease needs to be confirmed. PMID:24857171

Shi, Patricia Ann; Manwani, Deepa; Olowokure, Olugbenga; Nandi, Vijay

2014-12-01

163

Microcirculation assessment using an individualized model for diffuse reflectance spectroscopy and conventional laser Doppler flowmetry  

Science.gov (United States)

Microvascular assessment would benefit from co-registration of blood flow and hemoglobin oxygenation dynamics during stimulus response tests. We used a fiber-optic probe for simultaneous recording of white light diffuse reflectance (DRS; 475-850 nm) and laser Doppler flowmetry (LDF; 780 nm) spectra at two source-detector distances (0.4 and 1.2 mm). An inverse Monte Carlo algorithm, based on a multiparameter three-layer adaptive skin model, was used for analyzing DRS data. LDF spectra were conventionally processed for perfusion. The system was evaluated on volar forearm recordings of 33 healthy subjects during a 5-min systolic occlusion protocol. The calibration scheme and the optimal adaptive skin model fitted DRS spectra at both distances within 10%. During occlusion, perfusion decreased within 5 s while oxygenation decreased slowly (mean time constant 61 s dissociation of oxygen from hemoglobin). After occlusion release, perfusion and oxygenation increased within 3 s (inflow of oxygenized blood). The increased perfusion was due to increased blood tissue fraction and speed. The supranormal hemoglobin oxygenation indicates a blood flow in excess of metabolic demands. In conclusion, by integrating DRS and LDF in a fiber-optic probe, a powerful tool for assessment of blood flow and oxygenation in the same microvascular bed has been presented.

Strömberg, Tomas; Karlsson, Hanna; Fredriksson, Ingemar; Nyström, Fredrik H.; Larsson, Marcus

2014-05-01

164

Sample entropy of laser Doppler flowmetry signals increases in patients with systemic sclerosis.  

Science.gov (United States)

Associated to reactivity tests, laser Doppler flowmetry (LDF) emphasizes abnormal skin microvascular function in diseases affecting digits, such as Raynaud's phenomenon (RP) and systemic sclerosis (SSc). However, baseline perfusion value does not discriminate between disease states. We study if LDF sample entropy (SampEn) allows distinguishing healthy subjects, RP and SSc patients. LDF measurements were performed on finger pad and forearm of 108 subjects (27 controls, 28 RP patients, 53 SSc patients), before and after local thermal hyperemia. We also assessed the reproducibility of SampEn [expressed as within-subject coefficients of variation (CV) and intra-class correlation coefficients (ICC)]. Baseline SampEn is significantly increased in patients with SSc compared to RP and controls on finger pad [0.49 (0.19), 0.38 (0.14) and 0.36 (0.15), respectively; PSampEn at all sites and for all groups. Finally, reproducibility of SampEn computed on two baseline segments was acceptable (CV=26%, ICC=0.63). SampEn of skin blood flow at rest is increased on finger pad of patients with SSc but not on forearm. This is consistent with the pathophysiology of the disease, which predominantly affects digital microcirculation in most patients. SampEn of LDF signal could be a reproducible tool to predict digital microvascular impairment. PMID:21664914

Figueiras, E; Roustit, M; Semedo, S; Ferreira, L F Requicha; Crascowski, J L; Humeau, A

2011-09-01

165

Particle flow in blade passages of turbomachinery with application to laser-Doppler velocimetry  

Science.gov (United States)

A theoretical analysis was conducted of the dynamic behavior of micron size particles entrained in gas flow on the two-dimensional blade-to-blade surface of a circular stationary cascade of turbine stator blades. The particle velocity lag and angular deviation relative to the gas was determined as a function of particle diameter and mass density. Particles size and density were varied over ranges selected to correspond to typical laser-Doppler velocimeter (LDV) flow field mapping applications. It was found that velocity lag and angular deviation increased whenever particle size or mass density increased, and that particle tracking was more sensitive to a change in particle diameter than to a change in mass density. Results indicated that LDV applications employing 1 gm/cc tracer particles with diameters greater than approximately 1 micron, or 0.5 micron diameter particles with mass densities greater than 4 gm/cc would experience velocity and angular deviations generally greater than 2 percent and 1 degree, respectively.

Maxwell, B. R.

1974-01-01

166

Determination of Capsaicin Induced Increase in Dermal Blood Flow Using Laser Doppler Flowmetry Technique  

Directory of Open Access Journals (Sweden)

Full Text Available In the present study, we evaluated laser Doppler flowmetry technique using LDF100C (Biopac systems by determining blood flow changes following acute application of capsaicin on 12 healthy human subjects. Capsaicin applied locally (topical application at a dose of 0.075% produced significant increase in mean dermal blood flow from 31.4 ± 3.1 Blood Perfusion Units (BPU to 115. 7 ± 24.6 Blood Perfusion Units (BPU after 30 minutes, also there was significant difference in dermal blood flow change between placebo (32.1 ± 2.7 BPU and capsaicin (115.7 ± 24.6 BPU applica- tion. Capsaicin application produced significant percentage change in dermal blood flow by 291.0 ± 85.3% from baseline, while the change was insignificant with placebo (13.2 ± 7.4%. Therefore, it is suggested that this technique which is technically sound, non-invasive and inexpensive can be adopted in various fields of research to determine blood flow changes and this technique can also be utilized to determine the antagonists of the mediators involved in capsaicin induced vasodilatation.

Sunil Kumar Reddy Khambam

2011-07-01

167

High-Volume Hydrodissection: Assessment of Deep Inferior Epigastric Perforator Flap Perfusion Using Laser Doppler.  

Science.gov (United States)

High-volume hydrodissection of intramuscular perforators of deep inferior epigastric perforator (DIEP) flaps in Sprague-Dawley rats has previously demonstrated a significant reduction in dissection time while simultaneously increasing the safety of dissection. However, increasing volumes of fluid injected into the closed rectus compartment may have adverse consequences on perfusion to the overlying flap. A prospective experimental animal study was performed to define a safe upper limit of volume injection for high-volume hydrodissection. Eight Sprague-Dawley rats underwent bilateral "DIEP" flap dissections with varying volumes of fluid (1, 3, 6, and 9 mL) injected into the study side. The primary outcome measurement was overlying tissue perfusion, measured using laser Doppler imaging, at 6 separate time points during the flap harvest. Although no significant difference in perfusion was noted between study and control sides despite increasing volumes of injection, a trend toward significant altered perfusion was noted immediately after injection in the 9-mL study group. Six milliliters is defined as the safe upper limit volume of injection into the closed rectus compartment without significantly altering overlying flap perfusion in our Sprague-Dawley rats. Using volumetric analysis, these data translate to 425 mL as the safe upper limit for high-volume hydrodissection for a single average sized human rectus sheath during DIEP flap harvesting. The mechanical and potentially pharmacologic implications of these data in humans remain to be seen. PMID:25003454

Fanzio, Paolo Maria; Cheng, Ming-Huei; Samcam, Ivan; Lin, Yu-Te; Gorantla, Vijay; Lee, Bernard T; Singhal, Dhruv

2014-07-01

168

Dynamic Rotor Deformation and Vibration Monitoring Using a Non-Incremental Laser Doppler Distance Sensor  

International Nuclear Information System (INIS)

Monitoring rotor deformations and vibrations dynamically is an important task for improving the safety and the lifetime as well as the energy efficiency of motors and turbo machines. However, due to the high rotor speed encountered in particular at turbo machines, this requires concurrently a high measurement rate and high accuracy, which can not be fulfilled by most commercially available sensors. To solve this problem, we developed a non-incremental laser Doppler distance sensor (LDDS), which is able to measure simultaneously the in-plane velocity and the out-of-plane position of moving rough solid objects with micrometer precision. In addition, this sensor concurrently offers a high temporal resolution in the microsecond range, because its position uncertainty is in principle independent of the object velocity in contrast to conventional distance sensors, which is a unique feature of the LDDS. Consequently, this novel sensor enables precise and dynamic in-process deformation and vibration measurements on rotating objects, such as turbo machine rotors, even at very high speed. In order to evidence the capability of the LDDS, measurements of rotor deformations (radial expansion), vibrations and wobbling motions are presented at up to 50,000 rpm rotor speed.

169

Critical flow regions in tissue artificial heart valve assessed by laser doppler anemometer in continuous flow  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Flow diagnosis using non-invasive techniques such laser Doppler anemometer (LDA) is an important tool to improve the design of artificial heart valves. In the present study, an experimental protocol to obtain flow velocity field and colour coded maps of turbulent eddies dimensions using LDA measurem [...] ents in a 25 mm bovine pericardium bio prosthesis valve is reported. A transparent Plexiglas chamber was specially designed to allow optical access to the flow passing through the valve. Experiments were conducted for non-pulsate flow (to study the valve performance in the peak flow) for the aorta Reynolds number ranging from 3300 to 6800. LDA interrogation volume visited five thousand and one hundred points along the flow (2500 points upstream and 2600 points downstream) for each Reynolds number. Post-processing methodology was employed to obtain haemolytic potential colour-coded maps, which were related to turbulent quantities. It was observed that haemolytic regions tend to move downstream the valve when the flow rate is increased.

Marcos, Pinotti; Edna M. de, Faria.

2006-09-01

170

Laser doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing.  

Science.gov (United States)

The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue. PMID:24051525

He, Diwei; Nguyen, Hoang C; Hayes-Gill, Barrie R; Zhu, Yiqun; Crowe, John A; Gill, Cally; Clough, Geraldine F; Morgan, Stephen P

2013-01-01

171

Ray tracing model for the estimation of power spectral properties in laser Doppler velocimetry of retinal vessels and its potential application to retinal vessel oximetry  

Science.gov (United States)

A new model based on ray tracing was developed to estimate power spectral properties in laser Doppler velocimetry of retinal vessels and to predict the effects of laser beam size and eccentricity as well as absorption of laser light by oxygenated and reduced hemoglobin. We describe the model and show that it correctly converges to the traditional rectangular shape of the Doppler shift power spectrum, given the same assumptions, and that reduced beam size and eccentric alignment cause marked alterations in this shape. The changes in the detected total power of the Doppler-shifted light due to light scattering and absorption by blood can also be quantified with this model and may be used to determine the oxygen saturation in retinal arteries and veins. The potential of this approach is that it uses direct measurements of Doppler signals originating from moving red blood cells. This may open new avenues for retinal vessel oximetry.

Petrig, Benno L.; Follonier, Lysianne

2005-12-01

172

Coriolis-type mass flowmeter  

International Nuclear Information System (INIS)

A mass flowmeter of the Coriolis type is described comprising: A. a single turn flow loop formed by a pipe having a pair of arcuate legs the loop is supported on a frame whereby the loop is free to vibrate at its natural resonance frequency; B. a self-sufficient electromagnetic ballistic vibrator mounted on the loop at the vertex. The vibrator has a mass that oscillates to cause the loop to vibrate at its resonance frequency; C. means to feed a fluid to be metered through the vibrating loop to cause the loop to undergo tortional oscillation as a function of mass flow: D. a pair of strain gauges mounted on the respective legs of the loop whereby in the absence of flow, the gauges yield equal signals and during flow they yield signals of different magnitude as a function of mass flow; E. means to apply the signals from the gauges to a differential amplifier whose output is substantially proportional to the mass flow rate; and F. means responsive to the differential amplifier output to provide a mass flow rate reading

173

A laser-lock concept to reach cm/s-precision in Doppler experiments with Fabry-Perot wavelength calibrators  

CERN Document Server

State-of-the-art Doppler experiments require wavelength calibration with precision at the cm/s level. A low-finesse Fabry-Perot interferometer (FPI) can provide a wavelength comb with a very large bandwidth as required for astronomical experiments, but unavoidable spectral drifts are difficult to control. Instead of actively controlling the FPI cavity, we propose to passively stabilize the interferometer and track the time-dependent cavity length drift externally. A dual-finesse cavity allows drift tracking during observation. The drift of the cavity length is monitored in the high-finesse range relative to an external standard: a single narrow transmission peak is locked to an external cavity diode laser and compared to an atomic frequency. Following standard locking schemes, tracking at sub-mm/s precision can be achieved. This is several orders of magnitude better than currently planned high-precision Doppler experiments. It allows freedom for relaxed designs rendering this approach particularly interesting...

Reiners, A; Ulbrich, R G

2014-01-01

174

Laser Doppler measurement and CFD validation in 3 × 3 bundle flow  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Five-beam LDV is operated in the three-beam mode to measure 3 × 3 bundle flow. • Correlation and FFT techniques are applied to analyze the flow structure. • Large coherent structure is observed in gaps between different subchannels. • The Reynolds stress models predict weak mixing between different subchannels. - Abstract: The five-beam three-component laser Doppler system is operated in the three-beam two-component mode to measure the 3 × 3 bundle flow with simple grid spacer. Experiment has been conducted at Re = 15,200 and 29,900. According to the experiment result, the root mean square (RMS) of axial velocity fluctuation shows large value in the gap and the near-wall region of the edge sub-channel which is induced by the axial velocity gradient. Significant intensity of lateral velocity fluctuation is observed which indicates the strong lateral mixing in a 3 × 3 rod bundle. Through the correlation analysis coherent structures have been observed in the gap region. The spectral analysis shows that the LDV measurement complies to the Komogorov spectrum law, f{sup ?5/3}, well. The low-frequency peak spectral density of the axial velocity fluctuation has been observed in the gap region connecting sub-channels with velocity difference. The performance of the SSG model and the baseline Reynolds stress model are investigated based on the experiment result. The models predict higher axial velocity in the interior sub-channel and lower in the edge and corner ones than the experiment result. Large discrepancy between the calculated and measured axial flow velocity is resulted from failure in calculating the strong negative u{sup ?}w{sup ?¯} in the gap region connecting different sub-channels.

Xiong, Jinbiao, E-mail: xiongjinbiao@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University (China); Yu, Yang [School of Nuclear Science and Engineering, Shanghai Jiao Tong University (China); Yu, Nan; Fu, Xiaoliang [State Nuclear Power Software Development Center, National Energy Key Laboratory of Nuclear Power Software (China); Wang, Hongyan [School of Nuclear Science and Engineering, Shanghai Jiao Tong University (China); Cheng, Xu [Karlsruhe Institute of Technology (Germany); Yang, Yanhua [School of Nuclear Science and Engineering, Shanghai Jiao Tong University (China); State Nuclear Power Software Development Center, National Energy Key Laboratory of Nuclear Power Software (China)

2014-04-01

175

Effect of captopril on skin blood flow following intradermal bradykinin measured by laser Doppler flowmetry.  

Science.gov (United States)

The effect of captopril on skin response to intradermal injection of bradykinin was investigated by laser Doppler flowmetry (LDF) and weal and flare measurements in this randomised, double-blind, placebo-controlled, cross-over balanced study. Intradermal injections of 1 and 2.5 micrograms of bradykinin and normal saline were made into the forearm skin of six healthy volunteers between 1 and 2 h (t1) and between 3 and 4 h (t2) after either 25 mg captopril or placebo. Skin blood flow outside the induced weal was monitored continuously by LDF for 15 min and the mean LDF values over the last 15 s were used for analysis. Weal and flare sizes were measured at 15 min. On the placebo days, the mean LDF output, weal volume and flare area increased with incremental bradykinin dose. Pre-treatment with captopril significantly increased LDF output following intradermal bradykinin at t1 but not at t2. At both t1 and t2, captopril significantly increased weal volume. There was no significant difference between treatments in flare areas. Skin response following intradermal normal saline, measured by the above parameters, was not affected by captopril. This study showed that captopril potentiated the effects of intradermal bradykinin both with respect to blood flow changes and weal formation. The non-invasive technique of LDF can be used to detect the skin blood flow changes induced by intradermal bradykinin and the potentiation of this effect by captopril. It appears to be a useful and more objective method of quantifying local cutaneous blood flow changes than measurement of flare area. PMID:2532136

Li Kam Wa, T C; Almond, N E; Cooke, E D; Turner, P

1989-01-01

176

Laser Doppler measurement and CFD validation in 3 × 3 bundle flow  

International Nuclear Information System (INIS)

Highlights: • Five-beam LDV is operated in the three-beam mode to measure 3 × 3 bundle flow. • Correlation and FFT techniques are applied to analyze the flow structure. • Large coherent structure is observed in gaps between different subchannels. • The Reynolds stress models predict weak mixing between different subchannels. - Abstract: The five-beam three-component laser Doppler system is operated in the three-beam two-component mode to measure the 3 × 3 bundle flow with simple grid spacer. Experiment has been conducted at Re = 15,200 and 29,900. According to the experiment result, the root mean square (RMS) of axial velocity fluctuation shows large value in the gap and the near-wall region of the edge sub-channel which is induced by the axial velocity gradient. Significant intensity of lateral velocity fluctuation is observed which indicates the strong lateral mixing in a 3 × 3 rod bundle. Through the correlation analysis coherent structures have been observed in the gap region. The spectral analysis shows that the LDV measurement complies to the Komogorov spectrum law, f?5/3, well. The low-frequency peak spectral density of the axial velocity fluctuation has been observed in the gap region connecting sub-channels with velocity difference. The performance of the SSG model and the baseline Reynolds stress model are investigated based on the experiment result. The models predict higher axial velocity in the interior sub-channel and lower in the edge and corner ones than the experiment result. Large discrepancy between the calculated and measured axial flow velocity is resulted from failure in calculating the strong negative u?w?¯ in the gap region connecting different sub-channels

177

Laser-Doppler measurements of impinging jet flows through a crossflow  

Energy Technology Data Exchange (ETDEWEB)

The flowfield resulting from the impingement of a single axisymmetric jet against a wall after penetrating a confined crossflow has been studied experimentally using laser-Doppler anemometry. For sufficiently high jet velocities and small distances between the jet exit and the ground plane to produce impingement, two regions of the flow are seen to be of particular interest: the impinging region and the ground vortex caused by the interaction between the upstream wall jet and the crossflow. The latter consists of a vortical structure that wraps around the impinging jet like a scarf and should develop further downstream through a pair of streamwise vortices. The present work reports a study aimed at characterising the influence of the jet-to-crossflow velocity ratio on the structure of the ground vortex. The experiments were performed for Reynolds numbers based on the jet exit conditions of between 60,000 and 105,000 corresponding to jet-to-crossflow velocity ratios from 30 to 73 and for an impinging height of five jet diameters. The shape, size and location of the ground vortex were found to be dependent on the velocity ratio, and two different regimes were identified. For the higher velocity ratio regime, the downstream wall jet it is not strongly affected by the ground vortex, and the velocity profiles become similar. In both regimes, the crossflow acceleration over the ground vortex was found to be directly connected with the jet exit velocity. This indicates that the influence of the upstream wall jet is not confined to the ground vortex but spreads until the upper wall by a mechanism that needs further investigation. (orig.)

Barata, J.M.M. [Aerospace Sciences Department, Universidade da Beira Interior, Rua Marques d' Avila e Bolama, 6201-001, Covilha (Portugal); Durao, D.F.G. [Mechanical Engineering Department, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001, Lisboa (Portugal)

2004-05-01

178

New technique for calibrating hydrocarbon gas flowmeters  

Science.gov (United States)

A technique for measuring calibration correction factors for hydrocarbon mass flowmeters is described. It is based on the Nernst theorem for matching the partial pressure of oxygen in the combustion products of the test hydrocarbon, burned in oxygen-enriched air, with that in normal air. It is applied to a widely used type of commercial thermal mass flowmeter for a number of hydrocarbons. The calibration correction factors measured using this technique are in good agreement with the values obtained by other independent procedures. The technique is successfully applied to the measurement of differences as low as one percent of the effective hydrocarbon content of the natural gas test samples.

Singh, J. J.; Puster, R. L.

1984-01-01

179

Laser-driven flyer plates for shock compression science: Launch and target impact probed by photon Doppler velocimetry  

International Nuclear Information System (INIS)

We investigated the launch and target impact of laser-driven Al flyer plates using photon Doppler velocimetry (PDV). We studied different flyer designs launched by laser pulses of different energies, pulse durations and beam diameters, that produced km s?1 impacts with transparent target materials. Laser-launching Al flyers 25–100 ?m thick cemented to glass substrates is usually thought to involve laser vaporization of a portion of the flyer, which creates many difficulties associated with loss of integrity and heating of the flyer material. However, in the system used here, the launch mechanism was surprising and unexpected: it involved optical damage at the glass/cement/flyer interface, with very little laser light reaching the flyer itself. In fact the flyers launched in this manner behaved almost identically to multilayer flyers that were optically shielded from the laser pulses and insulated from heat generated by the pulses. Launching flyers with nanosecond laser pulses creates undesirable reverberating shocks in the flyer. In some cases, with 10 ns launch pulses, the thickest flyers were observed to lose integrity. But with stretched 20 ns pulses, we showed that the reverberations damped out prior to impact with targets, and that the flyers maintained their integrity during flight. Flyer impacts with salt, glass, fused silica, and acrylic polymer were studied by PDV, and the durations of fully supported shocks in those media were determined, and could be varied from 5 to 23 ns

180

Laser-driven flyer plates for shock compression science: Launch and target impact probed by photon Doppler velocimetry  

Energy Technology Data Exchange (ETDEWEB)

We investigated the launch and target impact of laser-driven Al flyer plates using photon Doppler velocimetry (PDV). We studied different flyer designs launched by laser pulses of different energies, pulse durations and beam diameters, that produced km s{sup ?1} impacts with transparent target materials. Laser-launching Al flyers 25–100 ?m thick cemented to glass substrates is usually thought to involve laser vaporization of a portion of the flyer, which creates many difficulties associated with loss of integrity and heating of the flyer material. However, in the system used here, the launch mechanism was surprising and unexpected: it involved optical damage at the glass/cement/flyer interface, with very little laser light reaching the flyer itself. In fact the flyers launched in this manner behaved almost identically to multilayer flyers that were optically shielded from the laser pulses and insulated from heat generated by the pulses. Launching flyers with nanosecond laser pulses creates undesirable reverberating shocks in the flyer. In some cases, with 10 ns launch pulses, the thickest flyers were observed to lose integrity. But with stretched 20 ns pulses, we showed that the reverberations damped out prior to impact with targets, and that the flyers maintained their integrity during flight. Flyer impacts with salt, glass, fused silica, and acrylic polymer were studied by PDV, and the durations of fully supported shocks in those media were determined, and could be varied from 5 to 23 ns.

Curtis, Alexander D.; Banishev, Alexandr A.; Shaw, William L.; Dlott, Dana D., E-mail: dlott@illinois.edu [School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2014-04-15

181

Laser-driven flyer plates for shock compression science: launch and target impact probed by photon Doppler velocimetry.  

Science.gov (United States)

We investigated the launch and target impact of laser-driven Al flyer plates using photon Doppler velocimetry (PDV). We studied different flyer designs launched by laser pulses of different energies, pulse durations and beam diameters, that produced km s(-1) impacts with transparent target materials. Laser-launching Al flyers 25-100 ?m thick cemented to glass substrates is usually thought to involve laser vaporization of a portion of the flyer, which creates many difficulties associated with loss of integrity and heating of the flyer material. However, in the system used here, the launch mechanism was surprising and unexpected: it involved optical damage at the glass/cement/flyer interface, with very little laser light reaching the flyer itself. In fact the flyers launched in this manner behaved almost identically to multilayer flyers that were optically shielded from the laser pulses and insulated from heat generated by the pulses. Launching flyers with nanosecond laser pulses creates undesirable reverberating shocks in the flyer. In some cases, with 10 ns launch pulses, the thickest flyers were observed to lose integrity. But with stretched 20 ns pulses, we showed that the reverberations damped out prior to impact with targets, and that the flyers maintained their integrity during flight. Flyer impacts with salt, glass, fused silica, and acrylic polymer were studied by PDV, and the durations of fully supported shocks in those media were determined, and could be varied from 5 to 23 ns. PMID:24784627

Curtis, Alexander D; Banishev, Alexandr A; Shaw, William L; Dlott, Dana D

2014-04-01

182

Continuous-scanning laser Doppler vibrometry: Extensions to arbitrary areas, multi-frequency and 3D capture  

International Nuclear Information System (INIS)

To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics

183

New applications of scanning laser Doppler vibrometry (SLDV) to nondestructive diagnosis of artwork: mosaics, ceramics, inlaid wood, and easel painting  

Science.gov (United States)

During the last years the growing importance of the correct determination of the state of conservation of artworks has been stated by all personalities in care of Cultural Heritage. There exist many analytical methodologies and techniques to individuate the physical and chemical characteristics of artworks, but at present their structural diagnostics mainly rely on the expertise of the restorer and the typical diagnostic process is accomplished mainly through manual and visual inspection of the object surface. The basic idea behind the proposed technique is to substitute human senses with measurement instruments: surfaces are very slightly vibrated by mechanical actuators, while a laser Doppler vibrometer scans the objects measuring surface velocity and producing 2D or 3D maps. Where a defect occurs velocity is higher than neighboring areas so defects can be easily spotted. Laser vibrometers also identify structural resonance frequencies thus leading to a complete characterization of defects. This work will present the most recent results coming out of the application of Scanning Laser Doppler Vibrometers (SLDV) to different types of artworks: mosaics, ceramics, inlaid wood and easel painting. Real artworks and samples realized on purpose have been studied using the proposed technique and different measuring issues resulting from each artwork category will be described.

Castellini, Paolo; Esposito, Enrico; Marchetti, Barbara; Paone, Nicola; Tomasini, Enrico P.

2001-10-01

184

Continuous-scanning laser Doppler vibrometry: Extensions to arbitrary areas, multi-frequency and 3D capture  

Energy Technology Data Exchange (ETDEWEB)

To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics.

Weekes, B.; Ewins, D. [University of Bristol, Queen' s Building, University Walk, Bristol, BS8 1TR (United Kingdom); Acciavatti, F. [Universita' Politecnica Delle Marche, Via Brecce Bianche 12, 60131 Ancona (Italy)

2014-05-27

185

Comparison between /sup 133/Xenon washout technique and Laser Doppler flowmetry in the measurement of local vasoconstrictor effects on the microcirculation in subcutaneous tissue and skin  

Energy Technology Data Exchange (ETDEWEB)

Changes in skin blood flow measured by Laser Doppler flowmetry and changes in subcutaneous blood flow measured by /sup 133/Xenon washout technique were compared during activation of the local sympathetic mediated veno-arteriolar vaso-constrictor reflex by lowering the area of investigation below heart level. The measurements were performed in tissue with and without sympathetic innervation. In five subjects, who all had been cervically sympathectomized for manual hyperhidrosis, the Laser Doppler and /sup 133/Xenon blood flow measurements were performed simultaneously on the sympathetically denervated forearm, and on the calf with preserved sympathetic nerve supply. The Laser Doppler method registered a 23% reduction in skin blood flow during lowering of the extremities independently of the sympathetic nerve supply to the skin. The /sup 133/Xenon method recorded a 44% decrease in blood flow in innervated and unchanged blood flow in denervated subcutaneous tissue during lowering of the extremities. Our results indicate that the Laser Doppler method and /sup 133/Xenon method are not comparable, and that the Laser Doppler method is not useful in measuring local sympathetic mediated blood flow changes.

Kastrup, J.; Buelow, J.; Lassen, N.A.

1987-10-01

186

Time of correlation of low-frequency fluctuations in the regional laser Doppler flow signal from human skin  

Science.gov (United States)

The laser Doppler flowmetry allows the non-invasive assessment of the skin perfusion in real-time, being an attractive technique to study the human microcirculation in clinical settings. Low-frequency oscillations in the laser Doppler blood flow signal from the skin have been related to the endothelial, endothelial-metabolic, neurogenic and myogenic mechanisms of microvascular flow control, in the range 0.005-0.0095 Hz, 0.0095-0.021 Hz, 0.021-0.052 Hz and 0.052- 0.145 Hz respectively. The mean Amplitude (A) of the periodic fluctuations in the laser Doppler blood flow signal, in each frequency range, derived from the respective wavelet-transformed coefficients, has been used to assess the function and dysfunctions of each mechanism of flow control. Known sources of flow signal variances include spatial and temporal variability, diminishing the discriminatory capability of the technique. Here a new time domain method of analysis is proposed, based on the Time of Correlation (TC) of flow fluctuations between two adjacent sites. Registers of blood flow from two adjacent regions, for skin temperature at 32 0C (basal) and thermally stimulated (42 0C) of volar forearms from 20 healthy volunteers were collected and analyzed. The results obtained revealed high time of correlation between two adjacent regions when thermally stimulated, for signals in the endothelial, endothelial-metabolic, neurogenic and myogenic frequency ranges. Experimental data also indicate lower variability for TC when compared to A, when thermally stimulated, suggesting a new promising parameter for assessment of the microvascular flow control.

Folgosi-Correa, M. S.; Nogueira, G. E. C.

2012-06-01

187

Cross-sectional laser Doppler velocimetry with nonmechanical scanning of points spatially encoded by multichannel serrodyne frequency shifting.  

Science.gov (United States)

A laser Doppler velocimeter (LDV) using nonmechanical scanning of multiple points spatially encoded by multichannel serrodyne frequency shifting is proposed for cross-sectional velocity distribution measurement. In the proposed LDV, nonmechanical scanning using wavelength change and simultaneous multipoint measurement using spatial encoding are combined. The use of a LiNbO3 phase-shifter array for multichannel serrodyne modulation makes it possible to simplify the generation of a spatially encoded beam array. An experiment was performed using a sensor probe setup with a six-channel beam array. The results indicate that two-dimensional velocity distribution measurement was successfully demonstrated. PMID:24365841

Maru, Koichi; Watanabe, Kento

2014-01-01

188

A laser-lock concept to reach cm s-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators  

Science.gov (United States)

State-of-the-art Doppler experiments require wavelength calibration with precision at the cm s-1 level. A low-finesse Fabry-Pérot interferometer (FPI) can provide a wavelength comb with a very large bandwidth as required for astronomical experiments, but unavoidable spectral drifts are difficult to control. Instead of actively controlling the FPI cavity, we propose to passively stabilize the interferometer and track the time-dependent cavity length drift externally using the 87Rb D2 atomic line. A dual-finesse cavity allows drift tracking during observation. In the low-finesse spectral range, the cavity provides a comb transmission spectrum tailored to the astronomical spectrograph. The drift of the cavity length is monitored in the high-finesse range relative to an external standard: a single narrow transmission peak is locked to an external cavity diode laser and compared to an atomic frequency from a Doppler-free transition. Following standard locking schemes, tracking at sub-mm s-1 precision can be achieved. This is several orders of magnitude better than currently planned high-precision Doppler experiments, and it allows freedom for relaxed designs including the use of a single-finesse interferometer under certain conditions. All components for the proposed setup are readily available, rendering this approach particularly interesting for upcoming Doppler experiments. We also show that the large number of interference modes used in an astronomical FPI allows us to unambiguously identify the interference mode of each FPI transmission peak defining its absolute wavelength solution. The accuracy reached in each resonance with the laser concept is then defined by the cavity length that is determined from the one locked peak and by the group velocity dispersion. The latter can vary by several 100 m s-1 over the relevant frequency range and severely limits the accuracy of individual peak locations, although their interference modes are known. A potential way to determine the absolute peak positions is to externally measure the frequency of each individual peak with a laser frequency comb (LFC). Thus, the concept of laser-locked FPIs may be useful for applying the absolute accuracy of an LFC to astronomical spectrographs without the need for an LFC at the observatory.

Reiners, A.; Banyal, R. K.; Ulbrich, R. G.

2014-09-01

189

Decoding carotid pressure waveforms recorded by laser Doppler vibrometry: Effects of rebreathing  

Science.gov (United States)

The principal goal of this study was to assess the capability of the laser Doppler vibrometry (LDV) method for assessing cardiovascular activity. A rebreathing task was used to provoke changes within individuals in cardiac and vascular performance. The rebreathing task is known to produce multiple effects, associated with changes in autonomic drive as well as alterations in blood gases. The rise in CO2 (hypercapnia), in particular, produces changes in the cerebral and systemic circulation. The results from a rebreathing task (involving rebreathing the same air in a rubber bag) are presented for 35 individuals. The LDV pulse was measured from a site overlying the carotid artery. For comparison and validation purposes, several conventional measures of cardiovascular function were also obtained, with an emphasis on the electrocardiogram (ECG), continuous blood pressure (BP) from the radial artery, and measures of myocardial performance using impedance cardiography (ICG). During periods of active rebreathing, ventilation increased. The conventional cardiovascular effects included increased mean arterial BP and systemic vascular resistance, and decreased cardiac stroke volume (SV) and pulse transit time (PTT). These effects were consistent with a pattern of ?-adrenergic stimulation. During the immediate post-rebreathing segments, in contrast, mean BP was largely unaffected but pulse BP increased, as did PTT and SV, whereas systemic vascular resistance decreased-a pattern consistent with ?-adrenergic effects in combination with the direct effects of hypercapnia on the vascular system. Measures of cardiovascular activity derived from the LDV pulse velocity and displacement waveforms revealed patterns of changes that mirrored the results obtained using conventional measures. In particular, the ratio of the maximum early peak in the LDV velocity pulse to the maximum amplitude of the LDV displacement pulse (in an early systolic interval) closely mirrored the conventional SV effects. Additionally, changes in an augmentation ratio (computed as the maximum amplitude of the LDV displacement pulse during systole / amplitude at the end of the incident wave) were very similar to changes in systemic vascular resistance. Heart rates measured from the ECG and LDV were nearly identical. These preliminary results suggest that measures derived using the non-contact LDV technique can provide surrogate measures for those obtained using impedance cardiography.

Casaccia, Sara; Sirevaag, Erik J.; Richter, Edward; O'Sullivan, Joseph A.; Scalise, Lorenzo; Rohrbaugh, John W.

2014-05-01

190

Investigation of laser Doppler anemometry in developing a velocity-based measurement technique  

Science.gov (United States)

Acoustic properties, such as the characteristic impedance and the complex propagation constant, of porous materials have been traditionally characterized based on pressure-based measurement techniques using microphones. Although the microphone techniques have evolved since their introduction, the most general form of the microphone technique employs two microphones in characterizing the acoustic field for one continuous medium. The shortcomings of determining the acoustic field based on only two microphones can be overcome by using numerous microphones. However, the use of a number of microphones requires a careful and intricate calibration procedure. This dissertation uses laser Doppler anemometry (LDA) to establish a new measurement technique which can resolve issues that microphone techniques have: First, it is based on a single sensor, thus the calibration is unnecessary when only overall ratio of the acoustic field is required for the characterization of a system. This includes the measurements of the characteristic impedance and the complex propagation constant of a system. Second, it can handle multiple positional measurements without calibrating the signal at each position. Third, it can measure three dimensional components of velocity even in a system with a complex geometry. Fourth, it has a flexible adaptability which is not restricted to a certain type of apparatus only if the apparatus is transparent. LDA is known to possess several disadvantages, such as the requirement of a transparent apparatus, high cost, and necessity of seeding particles. The technique based on LDA combined with a curvefitting algorithm is validated through measurements on three systems. First, the complex propagation constant of the air is measured in a rigidly terminated cylindrical pipe which has very low dissipation. Second, the radiation impedance of an open-ended pipe is measured. These two parameters can be characterized by the ratio of acoustic field measured at multiple locations. Third, the power dissipated in a variable RLC load is measured. The three experiments validate the LDA technique proposed. The utility of the LDA method is then extended to the measurement of the complex propagation constant of the air inside a 100 ppi reticulated vitreous carbon (RVC) sample. Compared to measurements in the available studies, the measurement with the 100 ppi RVC sample supports the LDA technique in that it can achieve a low uncertainty in the determined quantity. This dissertation concludes with using the LDA technique for modal decomposition of the plane wave mode and the (1,1) mode that are driven simultaneously. This modal decomposition suggests that the LDA technique surpasses microphone-based techniques, because they are unable to determine the acoustic field based on an acoustic model with unconfined propagation constants for each modal component.

Jung, Ki Won

2009-12-01

191

Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry  

Science.gov (United States)

Hydrodynamic turbulence and cavitation are known to play a significant role in high-pressure atomizers, but the small geometries and extreme operating conditions hinder the understanding of the flow’s characteristics. Diesel internal flow experiments are generally conducted using x-ray techniques or on transparent, and often enlarged, nozzles with different orifice geometries and surface roughness to those found in production injectors. In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a 3D laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limiting the fuel injection pressure. The vibrometer, which uses the Doppler effect to measure the velocity of a vibrating object, was used to scan injector nozzle tips during the injection event. The data were processed using a discrete Fourier transform to provide time-resolved spectra for valve-closed-orifice, minisac and microsac nozzle geometries, and injection pressures ranging from 60 to 160?MPa, hence offering unprecedented insight into cyclic cavitation and internal mechanical dynamic processes. A peak was consistently found in the spectrograms between 6 and 7.5?kHz for all nozzles and injection pressures. Further evidence of a similar spectral peak was obtained from the fuel pressure transducer and a needle lift sensor mounted into the injector body. Evidence of propagation of the nozzle oscillations to the liquid sprays was obtained by recording high-speed videos of the near-nozzle diesel jet, and computing the fast Fourier transform for a number of pixel locations at the interface of the jets. This 6–7.5?kHz frequency peak is proposed to be the natural frequency for the injector’s main internal fuel line. Other spectral peaks were found between 35 and 45?kHz for certain nozzle geometries, suggesting that these particular frequencies may be linked to nozzle dependent cavitation phenomena.

Crua, Cyril; Heikal, Morgan R.

2014-12-01

192

Laser Doppler vibrometry on rotating structures in coast-down: resonance frequencies and operational deflection shape characterization  

International Nuclear Information System (INIS)

In rotating machinery, variations of modal parameters with rotation speed may be extremely important in particular for very light and undamped structures, such as helicopter rotors or wind turbines. The natural frequency dependence on rotation speed is conventionally measured by varying the rotor velocity and plotting natural frequencies versus speed in the so-called Campbell diagram. However, this kind of analysis does not give any information about the vibration spatial distribution i.e. the mode shape variation with the rotation speed must be investigated with dedicated procedures. In several cases it is not possible to fully control the rotating speed of the machine and only coast-down tests can be performed. Due to the reduced inertia of rotors, the coast-down process is usually an abrupt transient and therefore an experimental technique, able to determine operational deflection shapes (ODSs) in short time, with high spatial density and accuracy, appears very promising. Moreover coast-down processes are very difficult to control, causing unsteady vibrations. Hence, a very efficient approach for the rotation control and synchronous acquisition must be developed. In this paper a continuous scanning system able to measure ODSs and natural frequencies excited during rotor coast-down is shown. The method is based on a laser Doppler vibrometer (LDV) whose laser beam is driven to scan continuously over the rotor surface, in order to measure the ODS, and to follow the rotation of the rotor itself even in coast-down. With a single measurement the ODSs can be recovered from the LDV output time history in short time and with huge data saving. This technique has been tested on a laboratory test bench, i.e. a rotating two-blade fan, and compared with a series of non-contact approaches based on LDV: - traditional experimental modal analysis (EMA) results obtained under non-rotating conditions by measuring on a sequence of points on the blade surface excited by an impact hammer,; - continuous scanning LDV measuring the ODS of the structure excited by an impact hammer modulating the laser output,; - tracking laser Doppler vibrometry (TLDV) operating at different rotation speeds under stationary conditions,; - tracking continuous scanning laser Doppler vibrometry (TCSLDV) operating at different rotation speeds under stationary conditions. EMA and TLDV have been performed over the same grid of points sufficiently dense to have ODSs with adequate spatial resolution, it requiring long measurement time. The application of different techniques allowed us to completely characterize the tested bladed rotor and to validate the continuous scanning application to transient rotator processes

193

Measuring the motion of the human tympanic membrane by laser Doppler vibrometry: basic principles and technical aspects  

Science.gov (United States)

Under hearing conditions, the amplitude of the motion of the human tympanic membrane is in the range of several tens of nanometers. To measure motions of this size by a touchfree method is a domain of laser technology. Here laser-Doppler-vibrometry was chosen because of its sensitivity in detecting small amplitudes and the clear information about the detected point on the tympanic membrane. Care was taken to develop the method for a clinically acceptable procedure for hearing diagnosis. The first realization by sinus wave excitation was found to be very time consuming. A measuring time of less than a minute was obtained by white noise excitation, fast Fourier transformation and choosing the umbo as the detection point. Meanwhile the setup is used for in vivo measurements.

Foth, Hans-Jochen; Huthoff, Christian; Stasche, Norbert; Hoermann, Karl

1994-02-01

194

Scanning Laser Doppler Vibrometer Measurements Inside Helicopter Cabins in Running Conditions: Problems and Mock-up Testing  

International Nuclear Information System (INIS)

The present work deals with the analysis of problems and potentials of laser vibrometer measurements inside helicopter cabins in running conditions. The paper describes the results of a systematic measurement campaign performed on an Agusta A109MKII mock-up. The aim is to evaluate the applicability of Scanning Laser Doppler Vibrometer (SLDV) for tests in simulated flying conditions and to understand how performances of the technique are affected when the laser head is placed inside the cabin, thus being subjected to interfering inputs. Firstly a brief description of the performed test cases and the used measuring set-ups are given. Comparative tests between SLDV and accelerometers are presented, analyzing the achievable performances for the specific application. Results obtained measuring with SLDV placed inside the helicopter cabin during operative excitation conditions are compared with those performed with the laser lying outside the mock-up, these last being considered as 'reference measurements'. Finally, in order to give an estimate of the uncertainty level on measured signals, a study linking the admitted percentage of noise content on vibrometer signals due to laser head vibration levels will be introduced.

195

Laser Radar Range-Doppler Imaging and Simulation on High-speed Target  

International Nuclear Information System (INIS)

On the basic of the representation of the principle of Doppler imaging, an echo model of high-speed target illuminated by broadband linear frequency modulated (LFM) signal was established in this paper. For high-speed target, because of its nonlinear echo phase and time-varying Doppler frequency shift, the Doppler spectrum of the target acquired by the traditional Fourier method was ambiguous, and the same in the radar images of the target. Therefore, an adaptive Wigner-Ville time-frequency analysis method was presented in the paper, that is, the local fuzzy function could be obtained by applying the two-dimensional adding Window Fourier Transform to signal's Wigner-Ville distribution, which made the kernel function, not only be adaptive to time, but also to the frequency. Finally, the simulation results show that the method has a good time-frequency concentration, and effectively control the cross-term interference.

196

Changes in skin blood flow and temperature during spinal analgesia evaluated by laser Doppler flowmetry and infrared thermography.  

Science.gov (United States)

Changes in skin blood flow and skin temperature during spinal analgesia and "sham" spinal analgesia were studied using laser Doppler flowmetry and skin temperature measurements on patients scheduled for transurethral resection. Infrared thermography was also used. During "sham" spinal analgesia skin blood flow decreased 17.7% +/- 37% (s.d.) and skin temperature fell 0.05 degrees C +/- 0.6 (s.d.) degree C. The height of the blockade was T10 or above in all cases. Using the laser Doppler technique with measuring points from the clavicle to T12, a tendency towards increased skin blood flow was seen in six cases out of 20 at T10 (significant elevations in 3/20) and in 14 cases out of 20 at T12 (significant elevations in 7/20). Skin temperature measurements and thermography showed a tendency towards cooling in the thoraco-abdominal region in the vast majority of the cases and a marked temperature elevation in the foot only. No differences between hyperbaric and glucose-free solutions for spinal analgesia were noticed. The conclusion of this study is that during spinal analgesia the extent of sympathetic blockade is less than the extent of analgesia. PMID:6240882

Bengtsson, M

1984-12-01

197

Laser-Doppler examinations in persons with healthy vasculature and in patients with peripheral arterial occlusive disease.  

Science.gov (United States)

Recently, a new procedure for noninvasive measurement of the microcirculation has been developed in the form of a helium-neon-laser Doppler apparatus with which the total erythrocyte flow through a cubic millimeter of skin is quantifiable. The authors used the procedure to examine 17 persons with healthy vessels, 36 patients with a degenerative occlusive disease of the peripheral arteries in Fontaine stages II-IV, and 5 patients with endangiitis obliterans. It is concluded that single measurements do not permit an assessment of microcirculatory conditions but that provocative tests (which are described), especially occlusion tests, make possible valid and reproducible statements and have a high selectivity with respect to the different stages of disease. By repeated measurements followed by calculation of mean values, a further reduction in intraindividual variability among the measurement results can be obtained. Laser-Doppler examinations of the skin constitute a new procedure with which quantitative statements on the blood flow through skin are feasible and from which interesting results can be expected, especially when used as an acute test. PMID:3789462

Ranft, J; Heidrich, H; Peters, A; Trampisch, H

1986-11-01

198

Laser Doppler measurements of inner ear blood flow during experimental thrombosis of cochlear blood vessels in the guinea pig.  

Science.gov (United States)

This study investigated the vascular effect of ferromagnetic obstruction of cochlear blood vessels in the guinea pig using dual-channel laser Doppler flowmetry. To improve this technique, we tested new types of magnets and iron spheres. In so doing, the cochlear temperature was lowered selectively and general hypothermia was avoided. The success of vascular impairment in the inner ear was found to depend on the experimental conditions used. Given normothermic conditions (38 degrees C body temperature), a clear reduction in cochlear blood flow (CBF) was found in only about 30% of the animals tested when an aluminium-nickel-cobalt alloy magnet and carbonyl iron spheres were used, while this ratio increased to about 80% under general hypothermia (33 degrees C). Using a stronger neodymium-iron-boron magnet and smaller-sized iron spheres, we found the success of vascular obstruction to be approximately 70% under normothermia and 100% with local hypothermia (to 33 degrees C) of the cochlea. Although the extent of vascular impairment revealed a considerable interindividual variation, the present findings demonstrate that ferromagnetic intervention in CBF with dual-channel laser Doppler flowmetry can be used to investigate the effect of quantified cochlear ischemia on inner ear physiology in the guinea pig model and test various therapeutic strategies. PMID:9065662

Scheibe, F; Haupt, H; Grunert, H

1997-01-01

199

Sub-Doppler Spectra of Infrared Hyperfine Transitions of Nitric Oxide Using a Pulse Modulated Quantum Cascade Laser: Rapid Passage, Free Induction Decay and the AC Stark Effect  

Energy Technology Data Exchange (ETDEWEB)

Using a low power, rapid (nsec) pulse-modulated quantum cascade (QC) laser, collective coherent effects in the 5 {micro}m spectrum of nitric oxide have been demonstrated by the observation of sub-Doppler hyperfine splitting and also Autler-Townes splitting of Doppler broadened lines. For nitrous oxide, experiments and model calculations have demonstrated that two main effects occur with ulsemodulated (chirped) quantum cascade lasers: free induction decay signals, and signals induced by rapid passage during the laser chirp. In the open shell molecule, NO, in which both {Lambda}-doubling splitting and hyperfine structure occur, laser field-induced coupling between the hyperfine levels of the two {Lambda}-doublet components can induce a large AC Stark effect. This may be observed as sub-Doppler structure, field-induced splittings, or Autler-Townes splitting of a Doppler broadened line. These represent an extension of the types of behaviour observed in the closed shell molecule nitrous oxide, using the same apparatus, when probed with an 8 {micro}m QC laser.

Duxbury, Geoffrey; Kelly, James F.; Blake, Thomas A.; Langford, Nigel

2012-05-07

200

Implementation and calibration of a laser Doppler velocimeter in order to measure liquids velocity  

Directory of Open Access Journals (Sweden)

Full Text Available Un sistema ? optico se aplic ? o y calibro con la t ? ecnica de l ? aser Doppler de diagnostico diferencial o configuraci ? on de doble haz, con detecci ? on hacia adelante, con el fin de medir un componente del vector de velocidad en l ? ?quidos transl ? ucidos. Este documento describe dos etapas, la primera es la calibraci ? on del veloc ? ?metro Doppler l ? aser a trav ? es de un objetivo rotatorio, y un acoplador ? optico que permiten verificar que las frecuencias que son detectados por el sistema ? optico, corresponden a las velocidades de rotaci ? on de dicho dispositivo. La segunda etapa es la medici ? on de la velocidad del l ? ?quido en un sistema de flujo estrecha que permite obtener r ? egimen de flujo laminar (bajo n ? umero de Reynolds, y se determin ? o la velocidad de componente ortogonal al patr ? on de interferencia franjas. Esta velocidad se calcula mediante la detecci ? on de la frecuencia de cambio en la intensidad que sufre la periferia (frecuencia Doppler donde las part ? ?culas artificiales o naturales (siembra sumergidos en el fluido a trav ? es de ellos. La radiaci ? on de la luz dispersa por la siembra conten ? ?a la se ? nal Doppler que se recoge con un fotodetector y se muestran en una computadora como un espectro de frecuencia.

C.F. Ord\\u00F3\\u00F1ez Urbano

2013-01-01

201

Contactless Electromagnetic Phase-Shift Flowmeter for Liquid Metals  

CERN Document Server

We present a concept and test results of an induction flowmeter for liquid metals. The flow rate is determined by applying a weak AC magnetic field to a liquid metal flow and measuring the flow-induced phase disturbance in the external electromagnetic field. The phase disturbance is found to be more robust than that of the amplitude used in conventional AC flowmeters. The basic characteristics of this type of flowmeter are analysed using simple theoretical models where the flow is approximated by a solid body motion. Design of such a flowmeter is presented and its test results reported.

Priede, J?nis; Gerbeth, Gunter

2010-01-01

202

Contactless electromagnetic phase-shift flowmeter for liquid metals  

International Nuclear Information System (INIS)

We present a concept and test results of an eddy-current flowmeter for liquid metals. The flow rate is determined by applying a weak ac magnetic field to a liquid metal flow and measuring the flow-induced phase disturbance in the external electromagnetic field. The phase disturbance is found to be more robust than that of the amplitude used in conventional eddy-current flowmeters. The basic characteristics of this type of flowmeter are analysed using simple theoretical models, where the flow is approximated by a solid body motion. Design of such a flowmeter is presented and its test results are reported

203

Theory of the Lorentz force flowmeter  

International Nuclear Information System (INIS)

A Lorentz force flowmeter is a device for the contactless measurement of flow rates in electrically conducting fluids. It is based on the measurement of a force on a magnet system that acts upon the flow. We formulate the theory of the Lorentz force flowmeter which connects the measured force to the unknown flow rate. We first apply the theory to three specific cases, namely (i) pipe flow exposed to a longitudinal magnetic field (ii) pipe flow under the influence of a transverse magnetic field and (iii) interaction of a localized distribution of magnetic material with a uniformly moving sheet of metal. These examples provide the key scaling laws of the method and illustrate how the force depends on the shape of the velocity profile and the presence of turbulent fluctuations in the flow. Moreover, we formulate the general kinematic theory which holds for arbitrary distributions of magnetic material or electric currents and for any velocity distribution and which provides a rational framework for the prediction of the sensitivity of Lorentz force flowmeters in laboratory experiments and in industrial practice

204

Using ordinal logistic regression to evaluate the performance of laser-Doppler predictions of burn-healing time  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Laser-Doppler imaging (LDI of cutaneous blood flow is beginning to be used by burn surgeons to predict the healing time of burn wounds; predicted healing time is used to determine wound treatment as either dressings or surgery. In this paper, we do a statistical analysis of the performance of the technique. Methods We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool. Results Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA, site and cause of burn, day of LDI scan, burn center. It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small. Conclusion Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for. The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the percentage of correct diagnoses.

Pape Sarah A

2009-02-01

205

Time domain algorithm for accelerated determination of the first order moment of photo current fluctuations in high speed laser Doppler perfusion imaging  

OpenAIRE

Advances in optical array sensor technology allow for the real time acquisition of dynamic laser speckle patterns generated by tissue perfusion, which, in principle, allows for real time laser Doppler perfusion imaging (LDPI). Exploitation of these developments is enhanced with the introduction of faster algorithms to transform photo currents into perfusion estimates using the first moment of the power spectrum. A time domain (TD) algorithm is presented for determining the first-order spectra...

Draijer, M.; Hondebrink, E.; Leeuwen, T.; Steenbergen, W.

2009-01-01

206

A feasibility study for the detection of upper atmospheric winds using a ground based laser Doppler velocimeter  

Science.gov (United States)

A possible measurement program designed to obtain the information requisite to determining the feasibility of airborne and/or satellite-borne LDV (Laser Doppler Velocimeter) systems is discussed. Measurements made from the ground are favored over an airborne measurement as far as for the purpose of determining feasibility is concerned. The expected signal strengths for scattering at various altitude and elevation angles are examined; it appears that both molecular absorption and ambient turbulence degrade the signal at low elevation angles and effectively constrain the ground based measurement of elevation angles exceeding a critical value. The nature of the wind shear and turbulence to be expected are treated from a linear hydrodynamic model - a mountain lee wave model. The spatial and temporal correlation distances establish requirements on the range resolution, the maximum detectable range and the allowable integration time.

Thomson, J. A. L.; Meng, J. C. S.

1975-01-01

207

Evaluation of a combined laser Doppler flowmetry and iontophoresis technique for the assessment of equine cutaneous microvascular function.  

Science.gov (United States)

A combined laser Doppler flowmetry and iontophoresis (LDFI) technique, used routinely to assess human microvascular function, was evaluated as a noninvasive technique for assessment of equine microvascular function, to facilitate the study of diseases such as laminitis. Baseline and vasoactive agonist-induced (acetylcholine and nitroprusside) microvascular flux was quantified at 2 sites (on the dorsal pastern adjacent to the coronary band and over the gluteals) in 6 clinically normal horses on 5 or 6 separate occasions under standardised conditions. Both agonists significantly increased microvascular flux. Skin pigmentation significantly attenuated the baseline flux, but not the magnitude of the agonist-mediated vasodilatory response. While LDFI was simple to perform, its value as a clinical and research tool for assessing the equine cutaneous microcirculation is limited by its poor reliability, as indicated by the marked intra- and intersubject variability in baseline and agonist-mediated microvascular flux. PMID:12455846

McGorum, B C; Milne, A J; Tremaine, W H; Sturgeon, B P R; McLaren, M; Khan, F

2002-11-01

208

Applying Laser Doppler Anemometry inside a Taylor-Couette geometry - Using a ray-tracer to correct for curvature effects  

CERN Document Server

In the present work it will be shown how the curvature of the outer cylinder affects Laser Doppler anemometry measurements inside a Taylor-Couette apparatus. The measurement position and the measured velocity are altered by curved surfaces. Conventional methods for curvature correction are not applicable to our setup, and it will be shown how a ray-tracer can be used to solve this complication. By using a ray-tracer the focal position can be calculated, and the velocity can be corrected. The results of the ray-tracer are verified by measuring an a priori known velocity field, and after applying refractive corrections good agreement with theoretical predictions are found. The methods described in this paper are applied to measure the azimuthal velocity profiles in high Reynolds number Taylor-Couette flow for the case of outer cylinder rotation.

Huisman, Sander G; Sun, Chao

2012-01-01

209

Heterodyne laser Doppler vibrometers integrated on silicon-on-insulator based on serrodyne thermo-optic frequency shifters.  

Science.gov (United States)

Miniaturized laser Doppler vibrometers (LDVs) have many advantages over conventional bulk LDVs. In this paper, the realization of a miniaturized heterodyne LDV integrated on silicon-on-insulator substrate is reported. The optical frequency shifters in these on-chip LDVs employ a serrodyne technique, and they generate a frequency shift at 2 kHz. Vibrations of a mirror for the frequency range between 1.1 and 123 Hz and the velocity range between 0.8 and 400 ?m/s are measured by both an on-chip LDV and a commercial LDV. The measurement results agree well. A compensation method for the influence of on-chip spurious reflections is also demonstrated. PMID:23545970

Li, Yanlu; Verstuyft, Steven; Yurtsever, Gunay; Keyvaninia, Shahram; Roelkens, Gunther; Van Thourhout, Dries; Baets, Roel

2013-04-01

210

Intraoperative prediction of ischaemic injury of the bowel: a comparison of laser Doppler flowmetry and tissue oximetry to histological analysis.  

Science.gov (United States)

Intraoperative diagnosis of inadequate colonic perfusion would contribute to prevention of ischaemic colitis after abdominal aortic reconstructions. The aim of this study was to evaluate laser Doppler flowmetry (LDF) and tissue oximetry (TpO2) as predictors of the development of bowel necrosis. Devascularised loops of colon and ileum in anaesthetised pigs were divided into 10-20 mm segments and measurements of laser Doppler flux and TpO2 were performed in each segment. After 7 h of ischaemia the segments were resected for histological and biochemical analysis. In 65 colonic and 58 ileal segments a significantly lower flux was found in segments with necrosis of greater than or equal to 30% of the mucosal thickness compared to segments with necrosis of less than or equal to 10% (p less than 0.01). The discriminant flux value was 50 perfusion units, confirming a previous clinical study. The specificity was 0.96 and the sensitivity 0.94. Flux was inversely correlated to tissue lactate concentration. Significantly lower TpO2 was found in 19 colonic segments with necrosis of greater than or equal to 30% of mucosa compared to 19 colonic segments with necrosis of less than or equal to 10% (p less than 0.01). Using a discriminant value of 5kPa, a specificity of 0.79, and a sensitivity of 0.95 were calculated. In 27 ileum segments no significant difference in TpO2 between different histological groups was found (p greater than 0.30). The results show that LDF and TpO2 can predict ischaemic injury of the colon, and LDF also of the small bowel. PMID:1397347

Krohg-Sørensen, K; Line, P D; Haaland, T; Horn, R S; Kvernebo, K

1992-09-01

211

Comparison Test and its Evaluation of Flowmeters for Heat Meter  

Science.gov (United States)

This study selected a total of 24 heat flowmeters consisting of three types: impeller, electromagnetic and ultrasonic, 8 meters each. The diameter was 0.05 m (9 meters), 0.08 m (9 meters), and 0.15 m (6 meters). In accordance with the OIML R 75 testing method accuracy, installation position, external environment, and durability were tested, and the flowmeter property field test was conducted in the field where of heat supply from winter to summer in order to select the type of heat flowmeter best suited for the circumstances in Korea. According to the test result, all 3 types of flowmeters met the OIML Recommendation, but the result of the field test showed that the electromagnetic flowmeters displayed a deviation at the low flow rate during summer. The impeller flowmeters showed accuracy suggested by the OIML Recommendation, but the ultrasonic flowmeter, a next-generation flowmeter, which is strong against contamination, low in maintenance-rate, and high in accuracy as it has no moving part, was found to be the best choice.

Choi, Hae-Man; Choi, Yong-Moon; Yoon, Byung-Ro

2010-06-01

212

FIELD TESTING OF PROTOTYPE ACOUSTIC EMISSION SEWER FLOWMETER  

Science.gov (United States)

This investigation concerns verifying the operating principles of the acoustic emission flowmeter (U.S. Patent 3,958,458) in the natural environment of three different storm sewer field sites in Nassau County, New York. The flowmeter is a novel, passive, nonintrusive method that ...

213

Measurements of ultrasonic waves by means of laser Doppler velocimeter and an experimental study of elastic wave propagation in inhomogeneous media; Laser doppler sokudokei ni yoru choonpa keisoku to ganseki wo mochiita fukinshitsu baishitsu no hado denpa model jikken  

Energy Technology Data Exchange (ETDEWEB)

In the study of seismic wave propagation, a model experimenting technique has been developed using a laser Doppler velocimeter (LDV) as the sensor. This technique, not dependent on conventional piezoelectric devices, only irradiates the specimen with laser to measure the velocity amplitude on the target surface, eliminating the need for close contact between the specimen and sensor. In the experiment, elastic penetration waves with their noise levels approximately 0.05mm/s were observed upon application of vibration of 10{sup 6}-10{sup 5}Hz. The specimen was stainless steel or rock, and waveforms caught by the LDV and piezoelectric device were compared. As the result, it was found that the LDV is a powerful tool for effectively explaining elastic wave propagation in inhomogeneous media. The piezoelectric device fails to reproduce accurately the waves to follow the initial one while the LDV detect the velocity amplitude on the specimen surface in a wide frequency range encouraging the discussion over the quantification of observed waveforms. 10 refs., 7 figs.

Nishizawa, O.; Sato, T. [Geological Survey of Japan, Tsukuba (Japan); Lei, X. [Dia Consultants Company, Tokyo (Japan)

1996-05-01

214

Slug flow measurement using a current-sensing electromagnetic flowmeter  

International Nuclear Information System (INIS)

In order to investigate the characteristics of two-phase slug flow, a current-sensing electromagnetic flowmeter with 240Hz triangular AC excitation was designed and manufactured. Theory of a current-sensing electromagnetic flowmeter with high temporal resolution was also developed. A flow pattern coefficient and a localization parameter were introduced for developing two-phase flow. The signals and noise from the flowmeter were obtained, and analyzed in comparison with the observations with a high speed CCD camera. The uncertainty of the flowmeter under singlephase flow was ±2.24% in real-time. For two-phase slug flow, electromagnetic flowmeter provided real-time simultaneous measurements of the mean film velocity around Taylor bubble and the relative location and the length of the bubble

215

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m3/h  

Science.gov (United States)

In the Physikalisch-Technische Bundesanstalt (PTB) the primary standard for on-line flowrate measurements using the laser Doppler anemometer (LDA) technique has been extended to a three-component LDA to improve velocity profile measurements in the boundary layers of a nozzle flow. The LDA flowrate measuring facility now consists of a two-colour argon ion LDA and a wavelength-stabilized GaAlAs diode laser LDA. The gas flowrate is obtained by numerical integration of the measured velocity profiles across the exit plane of the nozzle. High local resolution of the velocity profile measurements is achieved by perpendicular orientation of the measurement volumes of the two-component gas laser LDA and the semiconductor diode laser LDA (LD-LDA). This allows the resolution in the boundary layer to be improved significantly to velocity gradients. The present work presents the LD-LDA system for precise velocity profile measurements at flow velocities of up to 120 m/s; selected profile measurements are described in detail to demonstrate the high resolution and the symmetry of the flow profile. For the first time a wavelength-stabilized miniaturized diode laser LDA has been successfully applied in precise velocity measurements, and comparisons with well-established gas laser LDAs have been made. The uncertainty of the flowrate measurement up to 5 500 m3/h is 0,1% for air at atmospheric pressure. A turbine gas meter, type Elster G2500, was calibrated with the LDA and used as a transfer standard for an intercomparison with the Nederlands Meetinstituut (NMI) in the flowrate range up to 5 500 m3/h with and without the installation of perforated plates to condition the flow in the inlet section of the gas meter. The results of the comparison experiment clearly show the reliability and accuracy of the online flowrate measurement of gases and underline the necessity for a detailed research programme to investigate the relationship between installation effects, upstream flow conditions and the measurement uncertainty of gas meters. The design of a test rig now under construction at the PTB is shown. This will allow the diode laser LDA technique to be applied to the measurement of installation effects according to OIML Recommendation R-32.

Dopheide, D.; Strunck, V.; Krey, E.-A.

1994-01-01

216

Acute Effects of Vascular Modifying Agents in Solid Tumors Assessed by Noninvasive Laser Doppler Flowmetry and Near Infrared Spectroscopy  

Directory of Open Access Journals (Sweden)

Full Text Available The potential of noninvasive laser Doppler flowmetry (LDF and near infrared spectroscopy (NIRS to detect acute effects of different vascular-modifying agents on perfusion and blood volume in tumors was evaluated. C3H mouse mammary carcinomas (?200 mm3 in the rear foot of CDF1 mice were treated with flavone acetic acid (FAA, 150 mg/kg, 5,6-dimethylxanthenone-4acetic acid (DMXAA, 20 mg/kg, combretastatin A-4 disodium phosphate (CAMP, 250 mg/kg, hydralazine (HDZ, 5 mg/kg, or nicotinamide (NTA, 500 mg/kg. Tumor perfusion before and after treatment was evaluated by noninvasive LDF, using a 41°C heated custombuilt LDF probe with four integrated laser/receiver units, and tumor blood volume was estimated by MRS, using light guide coupled reflectance measurements at 800±10 nm. FAA, DMXAA, CAMP, and HDZ significantly decreased tumor perfusion by 50%, 47%, 73%, and 78%, respectively. In addition, FAA, DMXAA, and HDZ significantly reduced the blood volume within the tumor, indicating that these compounds to some degree shunted blood from the tumor to adjacent tissue, HDZ being most potent. CAMP caused no change in the tumor blood volume, indicating that the mechanism of action of CAMP was vascular shut down with the blood pool trapped in the tumor. NTA caused no change in either tumor perfusion or tumor blood volume. We conclude that noninvasive LDF and MRS can determine acute effects of vascular modifying agents on tumor perfusion and blood volume.

Michael Kragh

2002-01-01

217

A field-programmable gate array based system for high frame rate laser Doppler blood flow imaging.  

Science.gov (United States)

This paper presents a general embedded processing system implemented in a field-programmable gate array providing high frame rate and high accuracy for a laser Doppler blood flow imaging system. The proposed system can achieve a basic frame rate of flow images at 1 frame/second for 256 x 256 images with 1024 fast Fourier transform (FFT) points used in the processing algorithm. Mixed fixed-floating point calculations are utilized to achieve high accuracy but with a reasonable resource usage. The implementation has a root mean square deviation of the relative difference in flow values below 0.1% when compared with a double-precision floating point implementation. The system can contain from one or more processing units to obtain the required frame rate and accuracy. The performance of the system is significantly higher than other methods reported to date. Furthermore, a dedicated field-programmable gate array (FPGA) board has been designed to test the proposed processing system. The board is linked with a laser line scanning system, which uses a 64 x 1 photodetector array. Test results with various operating parameters show that the performance of the new system is better, in terms of noise and imaging speed, than has been previously achieved. PMID:20569169

Nguyen, H C; Hayes-Gill, B R; Morgan, S P; Zhu, Y; Boggett, D; Huang, X; Potter, M

2010-01-01

218

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

Science.gov (United States)

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.

Kaznacheev, A.; Kuznetsov, I.

2014-12-01

219

A remote and non-contact method for obtaining the blood-pulse waveform with a laser Doppler vibrometer  

Science.gov (United States)

The use of lasers to remotely and non-invasively detect the blood pressure waveform of humans and animals would provide a powerful diagnostic tool. Current blood pressure measurement tools, such as a cuff, are not useful for burn and trauma victims, and animals require catheterization to acquire accurate blood pressure information. The purpose of our sensor method and apparatus invention is to remotely and non-invasively detect the blood pulse waveform of both animals and humans. This device is used to monitor an animal or human's skin in proximity to an artery using radiation from a laser Doppler vibrometer (LDV). This system measures the velocity (or displacement) of the pulsatile motion of the skin, indicative of physiological parameters of the arterial motion in relation to the cardiac cycle. Tests have been conducted that measures surface velocity with an LDV and a signal-processing unit, with enhanced detection obtained with optional hardware including a retro-reflector dot. The blood pulse waveform is obtained by integrating the velocity signal to get surface displacement using standard signal processing techniques. Continuous recording of the blood pulse waveform yields data containing information on cardiac health and can be analyzed to identify important events in the cardiac cycle, such as heart rate, the timing of peak systole, left ventricular ejection time and aortic valve closure. Experimental results are provided that demonstrates the current capabilities of the optical, non-contact sensor for the continuous, non-contact recording of the blood pulse waveform without causing patient distress.

Desjardins, Candida L.; Antonelli, Lynn T.; Soares, Edward

2007-02-01

220

Effect of low level laser therapy on revascularization of free gingival graft using ultrasound Doppler flowmetry  

OpenAIRE

Low level laser therapy (LLLT) is widely used during the post-operative period to accelerate the healing process. It promotes beneficial biological action on neovascularization with anti-inflammatory and analgesic effects. Two systemically healthy patients with Miller's grade II recession on 33 and 41, respectively, were treated with free gingival graft. After surgery, second patient received LLLT using a 830 nm diode laser, with output power of 0.1 W on the first day half hour following surg...

Arunachalam, Lalitha T.; Sudhakar, Uma; Janarthanam, Akila Sivaranjani; Das, Nimisha Mithra

2014-01-01

221

Sub-Doppler temperature measurements of laser-cooled atoms using optical nanofibres  

International Nuclear Information System (INIS)

We present a method for measuring the average temperature of a cloud of cold 85Rb atoms in a magneto-optical trap using an optical nanofibre. A periodic spatial variation is applied to the magnetic fields generated by the trapping coils and this causes the trap centre to oscillate, which, in turn, causes the cloud of cold atoms to oscillate. The optical nanofibre is used to collect the fluorescence emitted by the cold atoms, and the frequency response between the motion of the centre of the oscillating trap and the cloud of atoms is determined. This allows us to make measurements of cloud temperature both above and below the Doppler limit, thereby paving the way for nanofibres to be integrated with ultracold atoms for hybrid quantum devices

222

Development of small size Coriolis Mass Flowmeter  

International Nuclear Information System (INIS)

A Coriolis Mass Flowmeter(CMF), which has U-Shaped unique measuring tube was developed for direct mass flow measurement. In order to convert the time difference between two measuring tubes motion into mass flowrate and flow quantity, a signal processing circuit, as a part of CMF, was also developed. The CMF was designed as the 15mm nominal diameter of pipe connection and the 8 mm stainless steel(sus 316) pipe was used for measuring tube. To maximize the flow signal(time difference) from the measuring tubes, the natural frequency of measuring tube was adjusted as 220 Hz, which is same as the frequency of exciter. The maximum displacement at the end of the measuring tube was measured as 0.05 mm, and the maximum time difference between two measuring tubes was observed as 20 ?s, which was proper for discrimination and measuring range of CMF. The developed CMF was tested against the gravimetric flowmeter calibrator in the range of 3 kg/min and 30 kg/min. The results showed that the CMF has good linearity and repeatability in the tested flow range. Large size of CMF base on the current study experience will be developed

223

Ultrasonic flow-meter test in sodium  

International Nuclear Information System (INIS)

As a part of the R and D programme for the prototype fast breeder reactor MONJU, an ultrasonic flow-meter (USFM) test is being carried out in sodium in the O-Arai Engineering Center of PNC. Prior to the present test, an in-water test was done at the manufacturer's as a preliminary investigation. The results reported here are the results up to the present. Calibration tests using the actual fluid were conducted on a 12-inch ultrasonic flow-meter with guide rods fabricated for sodium flow measurement. The test conditions in sodium were a temperature of 200 approximately 4000C and flow-rates of 0 approximately 6m/s. The main results are: (1) The linearity of output signal was good and accuracy was within 1%; (2) The alternating type of the USFM was much better than the fixed type in temperature change; (3) 2MHz of transducer frequency was better than 3MHz in sodium; (4) The S/N ratio of the ultrasonic signal and the length/diameter effect in a wide range in sodium surpassed the in-water test. (author)

224

Measurements of velocity profiles in a supersonic wind tunnel using the Laser-Doppler Method  

International Nuclear Information System (INIS)

A laser-velocimeter has been installed on a 100 x 100-mm-supersonic wind tunnel for measurements of mean velocity distributions and intensities of turbulence in the boundary layer of the tunnel at supersonic Mach numbers M = 1.75 and 2.5. The measured values, being reduced by means of a double counter method, have been compared with those formerly found using a combined pressure and temperature probe. The good correspondence of both results confirms that the laser-velocimetry is available as a non-interfering method for surveying supersonic flows. (orig.)

225

Physical model experiment for wave field measurements by means of laser Doppler vibrometer. Measurement of three components; Laser Doppler shindokei ni yoru butsuri model jikken. Hado sanseibun no kenshutsu  

Energy Technology Data Exchange (ETDEWEB)

In this experiment, a beam incident from an oblique direction is reflected by a spherical lens toward the direction of incidence. When the surface of a matter is vibrated by elastic waves, the spherical lens comes into a translation motion that accompanies the vibration. It follows accordingly that the vibration on the surface of the matter may be detected by sensing the spherical lens travelling speed. Three components of the vibration may be determined if beams are focused at one spot from three directions. Detection of the S-wave component by LDV (laser Doppler vibrometer) discloses the complicated wave field in a heterogeneous material, and this physical model experiment may be utilized in various fields of study. For instance, information about problems that may surface in the field work may be collected beforehand in a physical model experiment for developing an S-wave-aided probing method. For the study of seismic wave propagation in a complicated three-dimensional ground structure, a numerical model is not enough, and a physical model experiment will be an effective method to fulfill the purpose. In the monitoring of cracks in a rock, again, not only elastic wave velocity but also waveform information collected from a physical model experiment should be fully utilized. 6 refs., 6 figs.

Nishizawa, O.; Sato, T. [Geological Survey of Japan, Tsukuba (Japan); Lei, X. [DIA Consultant Co. Ltd., Tokyo (Japan)

1997-05-27

226

In situ testing of CO2 laser on dental pulp function: Effects on microcirculation  

Energy Technology Data Exchange (ETDEWEB)

The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304-1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.

Friedman, S.; Liu, M.; Doerscher-Kim, J.K.; Kim, S. (Department of Endodontics, Hadassah-Hebrew University School of Dental Medicine, Jerusalem (Israel))

1991-01-01

227

Studies of the flow of air in a model mixed-flow pump using laser Doppler anemometry. Part 1: Research facility and instrumentation  

Science.gov (United States)

A research facility was installed to study the behavior of air in a model mixed-flow pump, using a laser Doppler anemometer. The facility allows the detailed investigation of the three-dimensional velocity distributions which exist in the rotating and stationary passages of the model under a variety of operating conditions. The facility, including the model, instrumentation, data acquisition system (hardware and software) and the experimental methods used are described.

Carey, C.; Fraser, S. M.; Rachman, D.; Wilson, G.

1985-07-01

228

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  

OpenAIRE

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 degrees C for 20 mm) was assessed in 28 diabetic patients and 29 control subjects using a new velocity-resolved quantitative laser Doppler flowmetry technique (qLDF). The qLDF estimates erythrocyte (RBC) perfusion (velocity X concentration), in a physiologi...

Fredriksson, Ingemar; Larsson, Marcus; Nystro?m, Fredrik; La?nne, Toste; Johan O?stgren, Carl; Stro?mberg, Tomas

2010-01-01

229

Optic nerve head blood flow using a laser Doppler velocimeter and haemorheology in primary open angle glaucoma and normal pressure glaucoma.  

OpenAIRE

Optic disc blood flow velocity was measured in healthy patients, those with primary open angle glaucoma (POAG), and patients with normal pressure glaucoma (NPG). The velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head (ONH) has been measured with a laser Doppler velocimeter (LDV), and blood viscosity has been evaluated notably by determining the aggregability of the RBCs with an erythroaggregameter. Our results in POAG patients and NPG patients showed that their ...

Hamard, P.; Hamard, H.; Dufaux, J.; Quesnot, S.

1994-01-01

230

Simultaneous broadband laser ranging and photonic Doppler velocimetry for dynamic compression experiments  

Science.gov (United States)

A diagnostic was developed to simultaneously measure both the distance and velocity of rapidly moving surfaces in dynamic compression experiments, specifically non-planar experiments where integrating the velocity in one direction does not always give the material position accurately. The diagnostic is constructed mainly from fiber-optic telecommunications components. The distance measurement is based on a technique described by Xia and Zhang [Opt. Express 18, 4118 (2010)], which determines the target distance every 20 ns and is independent of the target speed. We have extended the full range of the diagnostic to several centimeters to allow its use in dynamic experiments, and we multiplexed it with a photonic Doppler velocimetry (PDV) system so that distance and velocity histories can be measured simultaneously using one fiber-optic probe. The diagnostic was demonstrated on a spinning square cylinder to show how integrating a PDV record can give an incorrect surface position and how the ranging diagnostic described here obtains it directly. The diagnostic was also tested on an explosive experiment where copper fragments and surface ejecta were identified in both the distance and velocity signals. We show how the distance measurements complement the velocity data. Potential applications are discussed.

La Lone, B. M.; Marshall, B. R.; Miller, E. K.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.

2015-02-01

231

Gingival blood flow under total combs by functional pressure evaluated with laser-Doppler flowmetry, a non-invasive method of blood flow measurement  

International Nuclear Information System (INIS)

Gingival blood flow under total-combs by functional pressure evaluated with Laser-Doppler Flowmetry, a non-invasive method of blood flow measurement. Microcirculation of gum's capillary system can be measured non-invasive by Laser-Doppler-Flowmetry (LDF). Circulation, defined by the number of floating erythrocytes per unit of time, is measured by a fibro-optical Laser-Doppler-Flowmetry. The task was to examine, if there is any change of gum's circulation during strain and relief. Circulation on defined measurepoints, divided on the four quadrants, was determined among maximal strain and subsequent relief, on one probationer (complete denture bearer). Before every measure session systemic pressure was taken. LDF-value was taken on top of jaw-comb, in doing so, to get reproducible result and a satisfying fixation of the probe, there was made an artificial limb of the upper and lower comb. In the upper comb a dynamometer-box, which determined minimal and maximal comb pressure, was integrated. The received results of the LDF-measurement, expressed as perfusion units (PU) were lower under applied pressure than by pressure points more distant. Hyperemia, resulting during relief, seemed the more intense, the less perfusion was before. This new, non-invasive kind of circulation measurement seems to be quite predestined to be used for gingival diagnostic under artificial limb in the future. (author)

232

A near infrared laser frequency comb for high precision Doppler planet surveys  

Directory of Open Access Journals (Sweden)

Full Text Available Perhaps the most exciting area of astronomical research today is the study of exoplanets and exoplanetary systems, engaging the imagination not just of the astronomical community, but of the general population. Astronomical instrumentation has matured to the level where it is possible to detect terrestrial planets orbiting distant stars via radial velocity (RV measurements, with the most stable visible light spectrographs reporting RV results the order of 1?m/s. This, however, is an order of magnitude away from the precision needed to detect an Earth analog orbiting a star such as our sun, the Holy Grail of these efforts. By performing these observations in near infrared (NIR there is the potential to simplify the search for distant terrestrial planets by studying cooler, less massive, much more numerous class M stars, with a tighter habitable zone and correspondingly larger RV signal. This NIR advantage is undone by the lack of a suitable high precision, high stability wavelength standard, limiting NIR RV measurements to tens or hundreds of m/s [1, 2]. With the improved spectroscopic precision provided by a laser frequency comb based wavelength reference producing a set of bright, densely and uniformly spaced lines, it will be possible to achieve up to two orders of magnitude improvement in RV precision, limited only by the precision and sensitivity of existing spectrographs, enabling the observation of Earth analogs through RV measurements. We discuss the laser frequency comb as an astronomical wavelength reference, and describe progress towards a near infrared laser frequency comb at the National Institute of Standards and Technology and at the University of Colorado where we are operating a laser frequency comb suitable for use with a high resolution H band astronomical spectrograph.

Bally J.

2011-07-01

233

Fiber optic laser Doppler velocimeter with non-mechanical scanning of spatially encoded points for cross-sectional velocity distribution measurement  

Science.gov (United States)

A fiber-optic laser Doppler velocimeter (LDV) combining non-mechanical scanning and multipoint measurement is proposed for two-dimensional velocity distribution measurement on a cross-sectional plane. The LDV consists of a main body including a tunable laser and LiNbO3 phase-shifter array, and a probe including diffraction gratings. The phaseshifter array is used to generate spatially encoded measurement points aligned in the transverse direction by multichannel optical serrodyne modulation, and these points are axially scanned with wavelength change. Two-dimensional velocitydistribution measurement is demonstrated using a probe setup with an 8-channel beam array.

Maru, Koichi; Watanabe, Kento

2014-07-01

234

Two-component simultaneous LDV (Laser Doppler Velocimeter) turbulence measurements in an axisymmetric nozzle afterbody subsonic flow field with a cold, underexpanded supersonic jet  

Science.gov (United States)

A test was conducted to obtain nonintrusive measurements in the flow field about an axisymmetric nozzle afterbody with a cold, underexpanded jet, M sub j = 1.563, in a parallel free stream, M sub alpha = 0.6. Reynolds shear stress and two components of mean velocity and turbulence intensity were measured using a two-color Bragg-diffracted laser Doppler velocimeter. Additional experimental data include the afterbody surface pressure distribution and laser vapor screen flow visualization of the jet plume. A multiple seeding technique was used to investigate the bimodal velocity probability distributions observed in the jet mixing region.

Heltsley, F. L.; Crosswy, F. L.

1983-06-01

235

Heterodyne laser Doppler distance sensor with phase coding measuring stationary as well as laterally and axially moving objects  

International Nuclear Information System (INIS)

Both in production engineering and process control, multidirectional displacements, deformations and vibrations of moving or rotating components have to be measured dynamically, contactlessly and with high precision. Optical sensors would be predestined for this task, but their measurement rate is often fundamentally limited. Furthermore, almost all conventional sensors measure only one measurand, i.e. either out-of-plane or in-plane distance or velocity. To solve this problem, we present a novel phase coded heterodyne laser Doppler distance sensor (PH-LDDS), which is able to determine out-of-plane (axial) position and in-plane (lateral) velocity of rough solid-state objects simultaneously and independently with a single sensor. Due to the applied heterodyne technique, stationary or purely axially moving objects can also be measured. In addition, it is shown theoretically as well as experimentally that this sensor offers concurrently high temporal resolution and high position resolution since its position uncertainty is in principle independent of the lateral object velocity in contrast to conventional distance sensors. This is a unique feature of the PH-LDDS enabling precise and dynamic position and shape measurements also of fast moving objects. With an optimized sensor setup, an average position resolution of 240 nm was obtained

236

[Measurement of cutaneous blood flow by laser Doppler velocimetry. Importance of probe effect and solvent effect after topical application].  

Science.gov (United States)

A comparative methodological study of the probe and/or vehicle effects was performed in Human volunteers with two laser Doppler velocimeters (L.D.V.): Laserflo BPM 403, T.S.I., U.S.A. and Periflux PF2B, Perimed, Sweden. Individual variations of skin blood flow are great (up to 1,400%); this could be related to spontaneous variations and/or to the occlusive effect of the probe. Skin blood flow was significantly increased in 35% of the subjects after the application of the probe alone, and in 70 to 90% of the cases after topical application of water or ethanol (20 to 50 microliters). Lag times before vasodilatation measured only when the probe was applied on the skin were between 7.4 and 27 minutes, they were reduced between 5.2 and 8.3 minutes when the vehicles were applied. These data suggest that in any protocol for L.D.V. determination an absolute control and a vehicle control should be included to evaluate objectively topical vasoactive drugs. PMID:8351685

Guessant, C; Marty, J P; Dupont, C

1993-01-01

237

Guided-wave-based damage detection in a composite T-joint using 3D scanning laser Doppler vibrometer  

Science.gov (United States)

Composite T-joints are commonly used in modern composite airframe, pressure vessels and piping structures, mainly to increase the bending strength of the joint and prevents buckling of plates and shells, and in multi-cell thin-walled structures. Here we report a detailed study on the propagation of guided ultrasonic wave modes in a composite T-joint and their interactions with delamination in the co-cured co-bonded flange. A well designed guiding path is employed wherein the waves undergo a two step mode conversion process, one is due to the web and joint filler on the back face of the flange and the other is due to the delamination edges close to underneath the accessible surface of the flange. A 3D Laser Doppler Vibrometer is used to obtain the three components of surface displacements/velocities of the accessible face of the flange of the T-joint. The waves are launched by a piezo ceramic wafer bonded on to the back surface of the flange. What is novel in the proposed method is that the location of any change in material/geometric properties can be traced by computing a frequency domain power flow along a scan line. The scan line can be chosen over a grid either during scan or during post-processing of the scan data off-line. The proposed technique eliminates the necessity of baseline data and disassembly of structure for structural interrogation.

Kolappan Geetha, Ganesh; Roy Mahapatra, D.; Srinivasan, Gopalakrishnan

2012-04-01

238

Experimental Study of the Applicability of the Remotely Positioned Laser Doppler Vibrometer to Rock-Block Stability Assessment  

Science.gov (United States)

This paper examines a new method for evaluating the stability of rock blocks on slopes using a remotely positioned Laser Doppler Vibrometer (LDV). A series of experiments using physical models were conducted to evaluate the validity of this new method. Based on the experimental studies, the applicability of LDV was examined by comparing results with a conventional seismometer measurement. To examine the quantitative correlations between vibration properties and the stability of a rock block, the effects on the vibration properties of the size of the rock block, the initial block position, the slope incline, and the type of ground surface were studied. The experimental results showed that LDV measurements agreed with conventional seismometer measurements. There was also a good correlation between vibration properties and rock-block stability. On the other hand, it was found that for a boulder on tightly compacted ground, the application of block stability assessment by tonometry was difficult when measuring microtremors or sloppy vibration due to nearby vehicle traffic. Furthermore, numerical analysis of the slope model was carried out to examine the validity of the model experiment and application of the suggested technique. The results of the analysis demonstrated that the suggested technique was effective for application to stability monitoring of a block and evaluation of the effect of stability measures.

Ma, Gui-Chen; Sawada, Kazuhide; Yashima, Atsushi; Saito, Hideki

2015-03-01

239

Experimental determination of mode correction factors for thermal method spring constant calibration of AFM cantilevers using laser Doppler vibrometry  

International Nuclear Information System (INIS)

Mode correction factors (MCFs) represent a significant adjustment to the spring constant values measured using the thermal cantilever calibration method. Usually, the ideal factor of 0.971 for a tipless rectangular cantilever is used, which adjusts the value by 3% for the first flexural mode. An experimental method for determining MCFs has been developed that relies on measuring the areas under the first few resonance peaks for the flexural mode type. Using this method, it has been shown that MCFs for the first flexural mode of commercially available atomic force microscope cantilevers actually vary from 0.95 to 1.0, depending on the shape and end mass of the cantilever. Triangular shaped cantilevers tend to lower MCFs with tipless versions providing the lowest values. Added masses (including tips) tend to increase the first flexural mode’s MCF to higher values with large colloid probes at the high extreme. Using this understanding and applying it to the recently developed laser Doppler vibrometry thermal calibration method it is now possible to achieve very accurate and precise cantilever spring constant calibrations (uncertainties close to ±1%) with commonly available commercial cantilevers such as tipped rectangular and triangular cantilevers, and colloid probes. (paper)

240

Repeatability, Reproducibility and Standardisation of a Laser Doppler Imaging Technique for the Evaluation of Normal Mouse Hindlimb Perfusion  

Directory of Open Access Journals (Sweden)

Full Text Available Background. Preclinical perfusion studies are useful for the improvement of diagnosis and therapy in dermatologic, cardiovascular and rheumatic human diseases. The Laser Doppler Perfusion Imaging (LDPI technique has been used to evaluate superficial alterations of the skin microcirculation in surgically induced murine hindlimb ischemia. We assessed the reproducibility and the accuracy of LDPI acquisitions and identified several critical factors that could affect LDPI measurements in mice. Methods. Twenty mice were analysed. Statistical standardisation and a repeatability and reproducibility analysis were performed on mouse perfusion signals with respect to differences in body temperature, the presence or absence of hair, the type of anaesthesia used for LDPI measurements and the position of the mouse body. Results. We found excellent correlations among measurements made by the same operator (i.e., repeatability under the same experimental conditions and by two different operators (i.e., reproducibility. A Bland-Altman analysis showed the absence of bias in repeatability (p = 0.29 or reproducibility (p = 0.89. The limits of agreement for repeatability were –0.357 and –0.033, and for reproducibility, they were –0.270 and 0.238. Significant differences in perfusion values were observed in different experimental groups. Conclusions. Different experimental conditions must be considered as a starting point for the evaluation of new drugs and strategic therapies.

Arturo Brunetti

2012-12-01

241

Studies of blood flow in human nasal mucosa with /sup133/Xe washout technique and laser doppler flowmetry  

International Nuclear Information System (INIS)

The techniques were applied for studies of the influence of environmental temperature on the human nasal mucosa, for studies of mediators in nasal allergy and for studies of the sympathetic neurogenic control of blood flow in the nasal mucosa. The results show that the two techniques are complementary to one another. The /sup133/Xe washout technique is useful for semiquantitative estimations of blood flow in the deeper parts of the mucosa, while the laser doppler technique is especially suited for continuous recordings of relative blood flow changes in the superficial part of the mucosa. Vascular changes may take part in body temperature regulation changes may take part in body temperature regulation as well as in conditioning of respiratory air. The results support the theories that changes in nasal mucosal blood flow are related to body temperature control, while conditioning of inspiratory air may be more dependent on mucosal blood content. The observed dissociation between changes in the resistance and the capacitance vessels also illustrates that these vascular segments are regulated in different ways. The present results indicate that leukotriene D/sub4/ might contribute to an increased blood flow in the nasal mucosa and to blockage of the nasal airway in the acute allergic reaction. Vasomotion is demonstrated to be present in the nasal mucosa, and it appears to be partly dependent on sympathetic neurogenic activity. The development of the present techniques, means that vascular changes involved in normal nasal function and in nasal disease may be evaluated by a new approach. (author)

242

Number of distal limb and brachial pressure measurements required when diagnosing peripheral arterial disease by laser Doppler flowmetry.  

Science.gov (United States)

We examine the reliability of single and repeated blood pressure measurements at ankle, toe, and arm levels for the diagnosis of peripheral arterial disease (PAD) by laser Doppler flowmetry. Segmental pressures were measured in 200 patients with known or suspected PAD. Segmental indices were calculated using (1) one measurement [M-1], two measurements [M-2], or by a predefined reproducibility criterion (RC) as well as (2) by using one brachial blood-pressure (BBP-one) or correspondent to each segmental pressure (BBP-all) as reference. The agreement in diagnosis of PAD by Cohen's Kappa was ? = 0.930 when comparing RC to M-1, and ? = 0.977 when comparing RC to M-2. The same comparison showed excellent relative reliability for segmental indices (all intra-class correlation coefficients (ICC) ? 0.980). Diagnostic classification agreement for BBP-all versus BBP-one were ? = 0.831 for RC, ? = 0.804 for M-1, and ? = 0.847 for M-2. The relative reliability analysis showed excellent correlation in segmental indices (all ICC ? 0.957). The study shows minimal difference in segmental indices and diagnostic classification when comparing calculations based on the listed strategies. However, the study indicated that it is important to measure BBPs correspondent to each segmental pressure. PMID:24045425

Høyer, C; Biurrun Manresa, J A; Petersen, L J

2013-10-01

243

Laser Echosclerotherapy of varicose veins with haemodynamic echo-doppler evaluation : some rationale and short-term outcomes  

Science.gov (United States)

Purpose: The aim is to verify short-term results in Endovenous Laser Treatment (EVLT) performed in haemodynamic way in patients belonging to C2, C3 classes and type I, II, III venous shunts, according respectively with CEAP and Teupitz classification. Methods: Minor changes of technique were applied to EVLT in order to provide haemodynamic conditions. Treatment efficacy, anatomical failure, complications, recurrence rate and clinical improvements were analyzed. 105 limbs were treated from November 2004 to November 2007. Clinical and Echo-Colour-Doppler (ECD) follow up was performed two weeks, one, two and three years after the surgery. Results: in 79 inferior limbs follow-up was concluded and this are the final data: a) no Deep Venous Thrombosis (DVT) was detected; b) a notable reduction of recurrence if compared with groin recurrence rate in traditional stripping; e) satisfactory cosmetic results and short recovery were found in all the patients. Conclusions: In selected patients haemodynamic-guided EVLT is equally safe and efficient than standard. Clinical and aesthetical outcomes are durable without statistical differences on the plan of disease progression and complications. The recurrence rate is lower in EVLT haemodynamic-guided surgery than in conventional stripping. Long-term outcomes should be investigated. We need studies camparison among the three different kind of surgery performed in haemodynamic way

Vettorello, Gianfranco; Marini, Leonardo

2009-06-01

244

A Study of Orifice Flowmeter with Low Loses  

International Nuclear Information System (INIS)

An orifice flowmeter is an efficient device for measuring flow rate utilizing velocity and pressure variation across the orifice plate. The orifice flowmeter is widely used in industry on account of its simple geometry, little maintenance, and advantage of a moderate production cost of installation. However there has been a frequent error caused by a large pressure drop and turbulent flow in orifice downstream. The present study analyzes a efficiency and performance of an orifice flowmeter by changing the diffuser design of outlet pipe so that the orifice flowmeter with losses system can induce a decrease pressure loss and uniform flow effectively adopting a diffuser. The two dimensional, compressible Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Sizes of the diffuser inlet diameter are changed, and enlargement angle, area ratio and total pressure losses are analyzed to find out the best design parameters

245

Unsteady Phenomena During Operation of the SSME Fuel Flowmeter  

Science.gov (United States)

This report describes a part of the analysis carried in support of the SSME (Space Shuttle Main Engine) Fuel Flowmeter redesign, addressing an intensely researched phenomenon known as "shifting" of the flowmeter constant value. It consists of a sudden change in the flowmeter indication, which occurs simultaneously with the onset of an oscillatory variation of the rotor speed. The change in the flowmeter indications does not correspond to a real change in the volumetric flow through the device. Several causes have been investigated in detail, in the past, without conclusive evidence towards a cause of this phenomenon. The present analysis addresses the flow physics through the flowmeter by assembling results from 3-D CFD (computational fluid dynamics) calculations, airfoil C(sub D)/C(sub L) performance curves and mass moment of inertia characteristics of the rotor into a synergistic calculation which simulates the unsteady regime of the flowmeter operation. The results show that the 4-bladed rotor interacts with the periodic flow pattern created behind the flow straightener upstream in a manner that generates a steady, periodic fluctuation in the rotor's speed. The amplitude of this fluctuation is significantly smaller than the 0.5% of mean speed threshold which constitutes a flight operational limit. When manufacturing errors occur, however, the fluctuations are amplified and can generate a significant apparent change in the flowmeter indication. Two types of possible fabrication errors-which can occur even for parts fabricated within the accepted tolerances for the blade airfoil-are presented, together with their effect on the flowmeter operation.

Marcu, Bogdan; McCool, A. (Technical Monitor)

2000-01-01

246

Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor  

Directory of Open Access Journals (Sweden)

Full Text Available A new laser air-motion sensor measures the true airspeed with an uncertainty of less than 0.1 m s?1 (standard error and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard-error uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the Global Positioning System, then indicate (via integrations of the hydrostatic equation during climbs and descents that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that the new laser air-motion sensor, combined with parametrized fits to correction factors for the measured dynamic and ambient pressure, provides a measurement of temperature that is independent of any other temperature sensor.

W. A. Cooper

2014-03-01

247

Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor  

Directory of Open Access Journals (Sweden)

Full Text Available A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s?1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

W. A. Cooper

2014-09-01

248

Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor  

Science.gov (United States)

A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s-1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents) that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

Cooper, W. A.; Spuler, S. M.; Spowart, M.; Lenschow, D. H.; Friesen, R. B.

2014-09-01

249

Doppler Lidar (DL) Handbook  

Energy Technology Data Exchange (ETDEWEB)

The Doppler lidar (DL) is an active remote sensing instrument that provides range- and time-resolved measurements of radial velocity and attenuated backscatter. The principle of operation is similar to radar in that pulses of energy are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is inferred. The radial or line-of-sight velocity of the scatterers is determined from the Doppler frequency shift of the backscattered radiation. The DL uses a heterodyne detection technique in which the return signal is mixed with a reference laser beam (i.e., local oscillator) of known frequency. An onboard signal processing computer then determines the Doppler frequency shift from the spectra of the heterodyne signal. The energy content of the Doppler spectra can also be used to determine attenuated backscatter.

Newsom, RK

2012-02-13

250

Doppler Effect  

Science.gov (United States)

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Mrs. Brown

2010-10-26

251

A solid state laser system for Doppler-free spectroscopy of muonium  

CERN Document Server

to 1MHz, was found to be of the order of 80-120 MHz for a 30-40 mJ output. This chirp was shown to be the result of a fast change of the refractive index in the alexandrite rods, and was found to be directly proportional to the population inversion change during the Q-switched pulse. A method of chirp compensation was developed leading to a reduction of the chirp by an order of magnitude i.e. to the level of 5-15 MHz. The alexandrite output was frequency tripled using LBO and BBO crystals with a conversion efficiency in excess of 10 %, yielding UV pulse energies of 3 to 6 mJ. The 1S-2S transition frequency has been measured to be 2,455,528,940.99 (9.75)(3.5) MHz which is in agreement with the theoretical value of 2,455,528,934.61 (3.44) MHz. Measurement of 1S-2S interval in deuterium, performed primarily to study systematic errors, represents the best pulsed measurement to date and is in an agreement with values obtained with cw lasers. The thesis describes a new high precision measurement of the 1S-2S transi...

Bakule, P

1998-01-01

252

Continual measurement of intramedullary blood perfusion with laser Doppler flowmetry in intact and ostectomized tibiae of rabbits.  

Science.gov (United States)

Blood flow is important for the healing of bone fractures. Until now, however, there have been no publications on the daily, continual measurement of intramedullary blood perfusion using laser Doppler flowmetry (LDF) in the conscious animal. In this study, a model for the daily, continual measurement of intramedullary blood perfusion by LDF and the temperature near the cortex both in intact and ostectomized tibiae in the conscious rabbit is described. The probes for blood perfusion and temperature measurement were implanted permanently at three different localizations into the right tibia of 10 adult New Zealand White rabbits. The probes were held in place by a bilateral, single-plane external fixator. In five of these animals, a midshaft tibial ostectomy was created in order to simulate a fracture. Intramedullary blood perfusion and temperature were measured daily over 49 days. While in intact tibiae no significant (P > 0.05) differences were found in blood perfusion readings taken at various time points, for mean values or for blood perfusion over time, in ostectomized tibiae the differences were significant: various time points (P = 0.0056), mean values (P = 0.0034) and blood perfusion over time (P = 0.0337). Blood perfusion readings at the centre probe were elevated compared with those at the proximal and distal probes. Thus, a revascularization in the ostectomy gap during the fracture healing was proven by means of the LDF. No influence of the blood perfusion on the temperature in the ostectomy area could be determined during healing of the ostectomy. The described model seems suitable for the continual measurement of intramedullary blood perfusion both in intact and ostectomized tibiae in the conscious rabbit. PMID:18625585

Hackenbroich, Ch; Wagner, S; Windhagen, H; Meyer-Lindenberg, A

2008-07-01

253

Smoothing and statistical evaluation of laser Doppler velocimetry data of turbulent flows in rotating and reciprocating machinery  

Energy Technology Data Exchange (ETDEWEB)

Arbitrarily time-distributed velocity information acquired by laser Doppler velocimeter systems needs special care when evaluated wrt. the mean velocity and the components of the Reynolds stress tensor. In rotating machinery, the arrival time information can be uniquely mapped to the angular position {phi} of the runner blades by using encoder signals relating a fixed runner position to an arrival time. It is convenient to statistically evaluate the velocity information of the detected particles in an angular window [{phi}{sub 0}-{delta}{phi}/2,{phi}{sub 0}+{delta}{phi}/2] in order to obtain mean velocities and turbulence values for an angular position {phi}{sub 0}. This approach has the inconvenience that turbulence values calculated from standard deviations are influenced by a possible variation in the mean velocity in the evaluation window. Other problems that arise with this ''evaluation window'' method are the influence of unevenly angular-distributed velocity information on the mean velocity or the poor resolution of maxima and minima of the mean velocity, which is similar to the problem pointed out by Jakoby et al. but being of second-order nature. In this paper, different improvements in the ''evaluation window'' method wrt these problems based on ideas found in a paper by McDonald and Owen are presented. A confidence interval calculation, generalizing the methods of Boutier, for all calculated values is included, which allows an appropriate window size {delta}{phi} to be chosen for each particular situation. The different methods are compared using examples from wake flows of axial hydraulic turbomachinery measured in air and water. (orig.)

Glas, W.; Forstner, M.; Kuhn, K.; Jaberg, H. [TU Graz (Austria). Inst. fur Hydraulische Stroemungsmaschinen

2000-11-01

254

Analysis of laser speckle contrast images variability using a novel empirical mode decomposition: comparison of results with laser Doppler flowmetry signals variability.  

Science.gov (United States)

Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) have emerged as noninvasive optical modalities to monitor microvascular blood flow. Many studies proposed to extract physiological information from LDF by analyzing signals variability. By opposition, such analyses for LSCI data have not been conducted yet. We propose to analyze LSCI variability using a novel data-driven method: the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). CEEMDAN is suitable for nonlinear and nonstationary data and leads to intrinsic mode functions (IMFs). It is based on the ensemble empirical mode decomposition (EEMD) which relies on empirical mode decomposition (EMD). In our work the average frequencies of LSCI IMFs given by CEEMDAN are compared with the ones given by EMD and EEMD. Moreover, LDF signals acquired simultaneously to LSCI data are also processed with CEEMDAN, EMD and EEMD. We show that the average frequencies of IMFs given by CEEMDAN depend on the signal-to-noise ratio (SNR) used in the computation but, for a given SNR, the average frequencies found for LSCI are close to the ones obtained for LDF. By opposition, EEMD leads to IMFs with frequencies that do not vary much when the SNR level is higher than a threshold. The new CEEMDAN algorithm has the advantage of achieving a complete decomposition with no error in the reconstruction but our study suggests that further work is needed to gain knowledge in the adjustment of the added noise level. CEEMDAN, EMD and EEMD are data-driven methods that can provide a better knowledge of LSCI. PMID:25347875

Humeau-Heurtier, Anne; Abraham, Pierre; Mahe, Guillaume

2015-02-01

255

Numerical calibration of a Lorentz force flowmeter  

International Nuclear Information System (INIS)

Numerical simulation of complex-shaped devices for contactless electromagnetic flow measurement in metallurgy is a challenge for computational magnetohydrodynamics. We report a series of numerical simulations which demonstrate for the first time that it is possible to predict the calibration constant of a generic Lorentz force flowmeter (LFF) with an uncertainty close to the requirements of real-life industrial applications. Our simulations involve both magnetostatic computations of a complex-shaped magnet system and magnetohydrodynamic computations of the flow of a liquid metal in a nozzle under the influence of a predominantly transverse magnetic field. In order to assess the role of turbulence, the simulations have been performed both for laminar and for turbulent flows using Reynolds-averaged Navier–Stokes equations in the latter case. In addition to the numerical simulations we have measured the calibration constant of the considered LFF using room-temperature liquid metal instead of liquid aluminum. A comparison between the numerically predicted and the measured values of the calibration constant shows that they differ by only 3.4%. This result suggests that numerical calibration of a LFF may become an economic alternative to expensive full-scale experimental calibration. (paper)

256

Improve flowmeter accuracy in cramped quarters  

International Nuclear Information System (INIS)

Getting accurate pipeline flow measurements with an orifice meter requires that the flow be streamlined and stable upstream of the orifice. A long, straight section of pipe usually provides the required stability. However, in many cases, a complex piping configuration or cramped site conditions make such long, straight piping runs more of a luxury than the norm. Straightening devices such as honeycombs and vanes inserted upstream of the orifice can reduce the length of straight pipe required. But they provide only marginal improvements in measurement accuracy, and may still require significant straight pipe. A new flow-conditioning device developed by Cheng Fluid Systems, Inc. (Sunnyvale, Calif.) solves this problem. Combining rotation vanes with a 90-deg elbow, the Cheng Rotational Vane (CRV) produces stable flow immediately downstream of the elbow. A complex gas piping system at Bechtel Savannah River, Inc.'s Defense Waste Processing Facility (DWPF; Aiken, S.C.) contains several 90-deg, long-radius elbows. Located in a high-radiation zone, the pipe carries offgas from a glass melter. During operation, impulse lines transmit the pressure drop signal outside the radiation area, where a microprocessor converts it to a 4- to 20-mA signal. That signal is then sent to a remote monitoring and control system. With the new Cheng elbow vanes in place, the orifice flowmeter has performed to design capacity. And, to date, the system has shown no random fluctuations and no lack shown no random fluctuations and no lack of repeatability

257

Measurement of blood flow velocity in a model of stenosis in vitro and in mesenteric vessels in vivo using non-invasive micro multipoint laser Doppler velocimetry  

International Nuclear Information System (INIS)

Our research goal is to carry out two-dimensional (2D) and three-dimensional (3D) measurements of the velocity distribution within a single vessel. We modified a non-invasive beam laser Doppler velocimeter using near-infrared light, and linearized the laser to carry out simultaneous multipoint measurements. We also scanned the measurement line in the direction of depth to allow 3D imaging of vascular blood flow in opaque areas in vivo. We used micro multipoint laser Doppler velocimetry (LDV) and a device with improved spatial resolution from 250 to 125 µm. We compared actual and calculated values using a rotating disk with an attached microwire. To demonstrate the effectiveness of the proposed system, blood flowing at a constant rate through a glass capillary and the velocity distribution of flow in the capillary were measured and mapped. The average flow velocity was calculated from the cross-sectional area and flow rate in the glass capillary, and we compared the calculated and measured values. To obtain an image of blood flow velocity in vivo, we measured both 2D and 3D flow velocity distributions in mouse mesenteric vessels. (paper)

258

A study on the uncertainty estimation of flowmeter calibrator with two master flowmeters  

International Nuclear Information System (INIS)

Comparing to the gravimetric and volumetric method, the flowmeter calibration based on the master meter method is relatively economical and convenient, especially for high flowrate. The uncertainty of flow quantity and flowrate using the master meter method was evaluated according to the GUM (Guide to the expression of Uncertainty in Measurement). In order to apply for the wider flow range, two master meters (electromagnetic flow meter) were employed as reference flowmeters. The uncertainty of the master meter was obtained by combining the statistical variation of the repeated measurements and the variation of fluid density and pipe material due to temperature and pressure changes were scrutinized. For a practical application, the uncertainty of calibrator, whose measuring capacity of 1000 m3/h obtained by employing two 500 m3/h electromagnetic flow meters, was evaluated. The uncertainty budget shows the quantitative contribution of each uncertainty component to the overall uncertainty of the calibrator. As a result, it was found that the dominant uncertainties were from the master meter, which was evaluated statistically, and from the process of least squares fitting. On the contrary, the uncertainties arising from the variation of the fluid density and the pipe volume due to the temperature and pressure were negligible

259

An infrared thermographic and laser doppler flowmetric investigation of skin perfusion in the forearm and finger tip :following a short period of vascular stasis  

OpenAIRE

The use of Infrared Thermography to diagnose circulatory problems in the hands is based upon the assumption that a change in skin temperature can be related to a change in skin blood flow. In this study 7 healthy volunteers were exposed to a 3 min period of vascular stasis of the right arm. The resultant reactive hyperaemia with associated skin erythemia was monitored on the forearm and finger tip of the 2nd digit with Infrared Thermography (IR) and with Laser Doppler Flowmetry (LDF). Followi...

Stikbakke, Einar

2010-01-01

260

An infrared thermographic and laser doppler flowmetric investigation of skin perfusion in the forearm and finger tip : following a short period of vascular stasis  

OpenAIRE

The use of Infrared Thermography to diagnose circulatory problems in the hands is based upon the assumption that a change in skin temperature can be related to a change in skin blood flow. In this study 7 healthy volunteers were exposed to a 3 min period of vascular stasis of the right arm. The resultant reactive hyperaemia with associated skin erythemia was monitored on the forearm and finger tip of the 2nd digit with Infrared Thermography (IR) and with Laser Doppler Flowmetry (LDF). Followi...

Stikbakke, Einar

2010-01-01

261

Simplified laser Doppler distance sensor employing a single fan-shaped interference fringe system for dynamic position and shape measurement of laterally moving objects  

Science.gov (United States)

We introduce a simplified laser Doppler distance sensor comprising only one single fan-shaped interference fringe system for dynamic position and shape measurement of fast moving objects with micrometer precision. Due to its low complexity, it can be built very compact and cheap, which is crucial for many industrial applications. It will be shown theoretically as well as experimentally that its position uncertainty is in principle independent of the object velocity in contrast to conventional distance sensors. In order to evidence its capability, radial and axial shape measurements of rotating bodies are presented employing a miniaturized sensor setup. An average position resolution of 2.3 ?m was obtained.

Pfister, Thorsten; Büttner, Lars; Czarske, Jürgen

2009-06-01

262

Measurements of the electrophoretic mobility with a new laser Doppler cytopherometer (Lazypher) and critical evaluation of the electrophorese mobility-test (EMT)  

International Nuclear Information System (INIS)

The new developed Laser Doppler Cytopherometer (Lazypher) allows the exact and objective measurement of the electrophoretic mobility of particles. Comparative experiments with the Free Flow Cell Electrophoresis instrument of Hannig showed identical results. The impression that the electrophoretic Mobility Test (EMT) is not valid for cancer diagnosis has been substantiated. But in its present form with the new instrument (Lazypher) possible improvements, e.g. isolation of lymphocytes, purification of antigens or indicator particles, can be estimated objectively for their value for the test system. (orig.)

263

Doppler Tomography  

OpenAIRE

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 c...

Marsh Tom

2000-01-01

264

A high-pressure bi-directional cycloid rotor flowmeter.  

Science.gov (United States)

The measurement of the flow rate of various liquids and gases is critical in industrial automation. Rotary positive displacement meters (rotary PD meters) are highly accurate flowmeters that are widely employed in engineering applications, especially in custody transfer operations and hydraulic control systems. This paper presents a high pressure rotary PD meter containing a pair of internal cycloid rotors. It has the advantages of concise structure, low pressure loss, high accuracy and low noise. The curve of the internal rotor is designed as an equidistant curtate epicycloid curve with the external rotor curve as its conjugate. The calculation method used to determine the displacement of the cycloid rotor flowmeter is discussed. A prototype was fabricated, and experiments were performed to confirm measurements over a flow range of 1-100 L/min with relative errors of less than ±0.5%. The pressure loss through the flowmeter was about 3 bar at a flow rate of 100 L/min. PMID:25196162

Liu, Shuo; Ding, Fan; Ding, Chuan; Man, Zaipeng

2014-01-01

265

Measurement of two-component flow using ultrasonic flowmeters  

International Nuclear Information System (INIS)

A novel application of existing ultrasonic flowmeter technology is described. This application was motivated by the need to make nonintrusive measurements of two-component flow in support of reactor safety research at the Savannah River Site (SRS). Two types of ultrasonic flowmeters were used during the test program in 1989. Both types were posttest calibrated in the summer of 1990 in a large gas/water flow facility at Wyle Laboratory in Norco, California. Both flowmeter types were found to measure total volumetric flow over a portion of their ranges accurately. When combined with void fraction measured by a three-beam gamma densitometer system it was possible to determine the individual gas and water flows

266

Effects of antipsoriatic treatment on cutaneous blood flow in psoriasis measured by 133Xe washout method and laser Doppler velocimetry  

International Nuclear Information System (INIS)

In 8 patients with psoriasis vulgaris, the cutaneous blood flow (CBF) was measured simultaneously in both involved and uninvolved psoriatic skin before (i.e., on the first day of hospitalization) and on the 3rd, 7th, 14th, and 28th days of treatment with tar. The 133Xe washout method was used after epicutaneous labeling and compared to the laser Doppler velocimetry (LDV) technique. Control experiments were performed in 10 normal individuals. Before treatment the mean CBF in involved psoriatic skin was 62.6 +/- 18.7 SD ml X (100 g X min)-1, which is significantly higher than CBF of uninvolved skin in psoriatic patients, 9.5 +/- 4.0 SD ml X (100 g X min)-1, (p less than 0.01) and is 13.6 times higher than CBF in the normal individuals (p less than 0.01). Fifty hours following onset of treatment (i.e., after only 2 applications of tar), mean CBF of the involved psoriatic skin had decreased significantly to 35.0 +/- 13.9 SD ml X (100 g X min)-1, (p less than 0.01), which was not statistically different from the CBF on the 7th day. During the following weeks, the CBF in involved psoriatic skin decreased at a more moderate rate than that observed during the first week and was 15.0 +/- 6.1 SD ml X (100 g X min)-1 on the 28th day. This value is not significantly different from the CBF of uninvolved skin in these patients. At the end of treatment, the CBF of the uninvolved skin had decreased significantly (p less than 0.05) in all the patients to values similar to tin all the patients to values similar to those observed in the skin of normal individuals. A parallel decline was observed in a clinical psoriatic score index; however, it is not known whether the observed decrease in CBF was preceded or succeeded by the clinical improvement

267

Free Convection of Gases in a Horizontal Cylinder with Differentially Heated End Walls - a Study by Laser Doppler Anemometry.  

Science.gov (United States)

An understanding of the prevailing fluid dynamics in ampoules used for the growth of single crystals from the vapor is mandatory for the design of growth apparatus and processes. In addition to diffusion in chemical concentration gradients, convective flows such as Stefan flow, streaming, and expansive and solutal convection can significantly affect transport rates, homogeneity, and morphological stability. Expansive convection dominates in many actual crystal growth situations. Its experimental characterization and mathematical description are the objectives of this dissertation. Therefore, the free convective flow of gases in a horizontal cylinder (radius to length, r(,0)/L = 0.1) with different end temperatures was characterized by Laser Doppler Anemometry (LDA). A linear temperature gradient at the wall of the quartz glass enclosure was established with a novel radiation heating arrangement. Experiments were conducted over a wide range of the Rayleigh number (74 (LESSTHEQ) Ra (LESSTHEQ) 1.3(.)10('6), with Ra (PROPORTIONAL) r(,0)('3)), which was varied via gas species and gas pressure. Agreement with theoretical predictions was found for velocity profiles in the cylinder core region at low Ra, and in the end regions at high Ra. A special effort was made to characterize the 3D flow behavior in the end zones. It was found that only part of the fluid flows along the cold (hot) thermode into the lower (upper) half of the cylinder. The remaining part changes the flow direction by dropping (rising) at the side wall over a considerable distance from the respective thermode. Nusselt numbers were estimated for a horizontal cylinder with adiabatic wall at high Rayleigh numbers, in good agreement with experiments of Kimura and Bejan. The calculations were based on the experimental finding that Gill's theory for free convection in tall, rectangular enclosures also predicts the velocity profile at mid-height near the vertical end walls in a long cylinder. Complete thermal stratification was assumed. This simple model yields more realistic Nusselt numbers for systems with Prandtl number (GREATERTHEQ) 1 than earlier more complex treatments. Finally, objects simulating crystals were inserted into the cylinder and positioned near the cold thermode. Their influence on the fluid flow was also studied by LDA.

Schiroky, Gerhard Hans

268

FLOWCER - a flowmeter based on radiotracer techniques  

International Nuclear Information System (INIS)

One of the most difficult problems in the field of flow measurement is the lack of a portable, clamp-on type of flowmeter of good accuracy. This is a serious restriction in non-continuous flow measurements and on-site calibrations of flow meters. One possibility of constructing a meter capable for these measurements is to use tracer techniques, particularly radioisotope tracers. A flow measurement instrument, FLOWCER, has been developed in the Reactor Laboratory of the Technical Research Centre of Finland (VTT). The instrument is based on the radioisotope transit time method. The device can be used for the accurate instantaneous measurement of volume flow rate in ducts. The tracer used is 137mBa produced in a portable isotope generator. Because of the short half-life (2.6 min) of 137mBa the measurement is radiologically very safe. The device consists of the isotope generator, an injection device for the tracer, radiation detectors, a data logger unit and a micro-computer. Also a transducer for various other quantities than flow may be connected to the analog input channels of the FLOWCER. The measurement program can be modified for measurements of different types. The FLOWCER has been used for the measurememts of energy and material balances, for the on-site calibrations of flow meters and for pump efficiency analysis. The application most frequently used has been the on-site calibration of flow meters. According to the present experience (over 100 calibrated flow meters) the accuracy level of flow measurements can be increased by a factor of ten or more by using the transit time method for on-site calibration

269

Modelling of flow in pipes and ultrasonic flowmeter bodies  

Directory of Open Access Journals (Sweden)

Full Text Available The contribution gives a summary of the flow modelling in flow parts of ultrasonic flowmeters using CFD system ANSYS/FLUENT. The article describes the basic techniques used to create CFD models of flow parts flow and selected results of the flow fields. The first part of the article summarizes the results of velocity profiles in smooth pipes for various turbulent models and used relations. The second part describes selected results of the numerical modelling of flow in the flow parts of the ultrasonic flowmeters and their partially comparison with experimental results.

Matas Richard

2014-03-01

270

Evaluation of the performance of an ultrasonic cross-correlation flowmeter  

International Nuclear Information System (INIS)

An ultrasonic cross-correlation flowmeter, developed to assist in improving performance of heavy water plants, was evaluated. Overall performance of the flowmeter is satisfactory. The flowmeter is ideally suited to industrial applications and has an accuracy and repeatability comparable to many laboratory instruments. An accuracy of 3% is readily obtainable. This new 'clamp-on' portable flowmeter should prove useful in applications which provide flow measurements in systems where pipe penetration is too costly or not practical, verify or replace existing flowmeters, and measure flows in lines not previously instrumented to provide better control or to verify performance of systems

271

Different imaging methods in the comparative assessment of vascular lesions: color-coded duplex sonography, laser Doppler perfusion imaging, and infrared thermography  

Science.gov (United States)

Aim of the study was the comparative investigation of cutaneous and subcutaneous vascular lesions. By means of color coded duplex sonography (CCDS), laser doppler perfusion imaging (LDPI) and infrared thermography (IT) we examined hemangiomas, vascular malformations and portwine stains to get some evidence about depth, perfusion and vascularity. LDI is a helpful method to get an impression of the capillary part of vascular lesions and the course of superficial vessels. CCDS has disadvantages in the superficial perfusion's detection but connections to deeper vascularizations can be examined precisely, in some cases it is the only method for visualizing vascular malformations. IT gives additive hints on low blood flow areas or indicates arterial-venous-shunts. Only the combination of all imaging methods allows a complete assessment, not only for planning but also for controlling the laser treatment of vascular lesions.

Urban, Peter; Philipp, Carsten M.; Weinberg, Lutz; Berlien, Hans-Peter

1997-12-01

272

Vibrational spectra of nanowires measured using laser doppler vibrometry and STM studies of epitaxial graphene : an LDRD fellowship report.  

Energy Technology Data Exchange (ETDEWEB)

A few of the many applications for nanowires are high-aspect ratio conductive atomic force microscope (AFM) cantilever tips, force and mass sensors, and high-frequency resonators. Reliable estimates for the elastic modulus of nanowires and the quality factor of their oscillations are of interest to help enable these applications. Furthermore, a real-time, non-destructive technique to measure the vibrational spectra of nanowires will help enable sensor applications based on nanowires and the use of nanowires as AFM cantilevers (rather than as tips for AFM cantilevers). Laser Doppler vibrometry is used to measure the vibration spectra of individual cantilevered nanowires, specifically multiwalled carbon nanotubes (MWNTs) and silver gallium nanoneedles. Since the entire vibration spectrum is measured with high frequency resolution (100 Hz for a 10 MHz frequency scan), the resonant frequencies and quality factors of the nanowires are accurately determined. Using Euler-Bernoulli beam theory, the elastic modulus and spring constant can be calculated from the resonance frequencies of the oscillation spectrum and the dimensions of the nanowires, which are obtained from parallel SEM studies. Because the diameters of the nanowires studied are smaller than the wavelength of the vibrometer's laser, Mie scattering is used to estimate the lower diameter limit for nanowires whose vibration can be measured in this way. The techniques developed in this thesis can be used to measure the vibrational spectra of any suspended nanowire with high frequency resolution Two different nanowires were measured - MWNTs and Ag{sub 2}Ga nanoneedles. Measurements of the thermal vibration spectra of MWNTs under ambient conditions showed that the elastic modulus, E, of plasma-enhanced chemical vapor deposition (PECVD) MWNTs is 37 {+-} 26 GPa, well within the range of E previously reported for CVD-grown MWNTs. Since the Ag{sub 2}Ga nanoneedles have a greater optical scattering efficiency than MWNTs, their vibration spectra was more extensively studied. The thermal vibration spectra of Ag{sub 2}Ga nanoneedles was measured under both ambient and low-vacuum conditions. The operational deflection shapes of the vibrating Ag{sub 2}Ga nanoneedles was also measured, allowing confirmation of the eigenmodes of vibration. The modulus of the crystalline nanoneedles was 84.3 {+-} 1.0 GPa. Gas damping is the dominate mechanism of energy loss for nanowires oscillating under ambient conditions. The measured quality factors, Q, of oscillation are in line with theoretical predictions of air damping in the free molecular gas damping regime. In the free molecular regime, Q{sub gas} is linearly proportional to the density and diameter of the nanowire and inversely proportional to the air pressure. Since the density of the Ag{sub 2}Ga nanoneedles is three times that of the MWNTs, the Ag{sub 2}Ga nanoneedles have greater Q at atmospheric pressures. Our initial measurements of Q for Ag{sub 2}Ga nanoneedles in low-vacuum (10 Torr) suggest that the intrinsic Q of these nanoneedles may be on the order of 1000. The epitaxial carbon that grows after heating (000{bar 1}) silicon carbide (SiC) to high temperatures (1450-1600) in vacuum was also studied. At these high temperatures, the surface Si atoms sublime and the remaining C atoms reconstruct to form graphene. X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) were used to characterize the quality of the few-layer graphene (FLG) surface. The XPS studies were useful in confirming the graphitic composition and measuring the thickness of the FLG samples. STM studies revealed a wide variety of nanometer-scale features that include sharp carbon-rich ridges, moire superlattices, one-dimensional line defects, and grain boundaries. By imaging these features with atomic scale resolution, considerable insight into the growth mechanisms of FLG on the carbon-face of SiC is obtained.

Biedermann, Laura Butler

2009-09-01

273

Integrated microfluidic flowmeter based on a micro-FBG inscribed in Co²?-doped optical fiber.  

Science.gov (United States)

A novel microfluidic flowmeter integrated with microfiber Bragg grating (µFBG) is presented. Two glass capillaries and a short length of high-light-absorption Co²?-doped optical fiber were stacked inside a larger outer capillary tube. The stack was then drawn into a tapered device. Two microchannels with the diameter of ~50???m were formed inside the capillaries for flowing of microfluidics. An FBG was inscribed in the tapered Co²?-doped fiber with waist diameter of ~70???m, and acts as a flow-rate sensor. A pump laser with wavelength of 1480 nm was utilized to locally heat the µFBG, rendering the µFBG as miniature "hot-wire" flowmeter. The flow rate of the liquid in the microchannels is determined by the induced wavelength shift of the µFBG. The experimental results achieve a minimum detectable change of ~16??nL/s in flow rate, which is very promising in the use as part of biochips. PMID:25361108

Liu, Zhengyong; Tse, Ming-Leung Vincent; Zhang, A Ping; Tam, Hwa-Yaw

2014-10-15

274

True mass flowmeter - a mass flowmeter for nonsteady-state two-phase flow  

International Nuclear Information System (INIS)

A measuring device for measuring the mass flow of nonsteady-state two-phase flows has been developed based on the principle of rotating flow machines. Two versions of the device (true mass flowmeter (TMFM) 2.5 with a measuring range of 2.5 kg/s, and TMFM 50 with a measuring range of 50 kg/s) were used to study the measuring accuracy and the field use of the system. While the measurement errors of TMFM 2.5 are within + or - 2.2% of the maximum flow, it is possible with the TMFM 50 to reduce the measuring error to + or - 1.5% (quality x 1%). This implies that the accuracy in measuring two-phase mass flow is practically identical with that obtained in single-phase flow by familiar standard measuring techniques

275

Vascularity in cutaneous melanoma detected by Doppler sonography and histology: correlation with tumour behaviour.  

OpenAIRE

The blood flow in 71 primary skin melanomas was investigated by a 10MHz Doppler ultrasound flowmeter and flow signals were analysed on an Angioscan-II spectrum analyser. Doppler flow signals were detected in 44 tumours, with a close relationship to Breslow's tumour thickness. No blood flow signal was detected in 27 lesions and 25 of these had a tumour thickness of 0.8 mm or less. Ninety-seven per cent of tumours of thickness greater than 0.8 mm had detectable Doppler flow signals. Histologica...

Srivastava, A.; Hughes, L. E.; Woodcock, J. P.; Laidler, P.

1989-01-01

276

Doppler tomography  

International Nuclear Information System (INIS)

The finding that cancer may have different Doppler characteristics from other tissues and vessels has prompted some interest in Dopper evaluation of breasts. In an effort to obtain sequences of Doppler images suitable for complete breast images, the authors have tested methods of Doppler tomography. Doppler tomography was performed in phantoms in which fluid was flowing in several tubes. The backscatter CW Doppler signal from a 2 MHz carrier was measured for 128 samples along 200 profiles taken at equispaced angles of view around the phantom. The RF signal was mixed to base stand, low pass filtered, and A/D converted to 10 KHz for subsequent computer analysis. The Doppler power in a specified frequency band was used to eliminate number of particles moving within a certain velocity range. Reconstructed images were obtained with and without flow in tubes within excised human breast. Images proportional to number of particles flowing at velocities greater than a certain velocity were of good quality. The results show that Dopper tomography is a distinct possibility even though the vector nature of Doppler shift causes some inconsistencies in the data

277

Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves / Velocimetria laser de escoamento permanente através de duas próteses cardíacas de duplo folheto  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese INTRODUÇÃO: A caracterização hidrodinâmica in vitro de próteses de válvulas cardíacas fornece informações importantes quanto ao seu funcionamento, sobretudo se realizada por meio de métodos não-invasivos de anemometria. Uma vez obtidos os perfis de velocidade para cada válvula, é possível compará-la [...] s quanto ao seu desempenho hidrodinâmico. Neste primeiro estudo experimental de anemometria laser com válvulas mecânicas, as simulações foram realizadas em bancada de testes para escoamento permanente. OBJETIVO: Comparar perfis de velocidade unidimensional no plano central de duas próteses aórticas de duplo folheto St. Jude (modelos AGN 21 - 751 e 21 AJ - 501) submetidas a um regime de fluxo permanente, para quatro seções distintas, três à jusante e uma à montante. MÉTODOS: Proporcionar condições de similaridade para o escoamento através de cada prótese, por meio de bancada hidrodinâmica para escoamento permanente (água, à vazão de 17 L/min.) e, por meio de anemometria laser unidimensional, obter os perfis de velocidades para as mesmas seções e varreduras. RESULTADOS: Verificou-se que as maiores velocidades correspondem à prótese de diâmetro interno menor e que as instabilidades do fluxo são maiores à medida que a seção de interesse encontra-se mais próxima da válvula. Também foram verificadas as regiões de recirculação, de estagnação do fluxo e de baixa pressão, além dos picos de velocidade para o escoamento em questão. CONCLUSÕES: Sob o aspecto hidrodinâmico e para todas as seções de interesse, foi possível concluir a preferência da válvula de modelo AGN 21 - 751 (RegentTM) sobre a 21 AJ - 501 (Master Series). Os resultados obtidos permitiram escolher, para os próximos trabalhos, um foco de estudo mais específico para regiões concretas dessas próteses. Abstract in english INTRODUCTION: In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hy [...] drodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. OBJECTIVE: To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. METHODS: To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min.) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. RESULTS: It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. CONCLUSIONS: Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.

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

2013-12-01

278

Method of assessing blood oxygenation in microcirculation vessels based on Doppler approach  

Science.gov (United States)

Combination of laser Doppler flowmetry and pulse oximetry methods allows for the direct assessment of oxygen supply to tissues at the microcirculatory level, namely, in that part of the vascular network where the transcapillary exchange takes place that is responsible for saturating tissues with oxygen. The microcirculation system comprises arterial and venous microvascular parts that differ in blood flow velocities. Frequency separation of the photodetector signal components related to different velocity ranges makes possible to distinguish the hemodynamic processes in these two parts of the microvascular system. Moreover, numerous studies of collective oscillatory processes in hemodynamics reveal that cardio-oscillations are more pronounced in arterioles, whereas venous hemodynamics is mostly influenced by the breath rhythm. Taking account of the above phenomena allows developing a signal-filtration system for separate characterization of blood-oxygenation states in arterial and venous blood flows. Light absorbance in the skin depends on both light wavelength and blood-oxygenation level. Processing the signals obtained with a two-channel dual-wavelength (630 and 1115 nm) laser Doppler flowmeter provides information about blood oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygen consumption in tissues. In particular, this approach allows revealing pathogenic processes resulting from hyper- and hypo-oxygenation in tissues. For instance, rapidly growing malignant tumors are characterized by intensive metabolism, rapid formation of capillaries, and active transcapillary oxygen exchange that results in higher level of oxygen diffusion into tissue, while the level of oxygen is lowered in the microvascular veins.

Sokolov, Vladimir G.; Korsi, Larissa V.; Egorov, Sergei Y.

2001-06-01

279

Sub-Doppler laser cooling of fermionic 40K atoms in three-dimensional gray optical molasses  

CERN Document Server

We demonstrate sub-Doppler cooling of 40K on the D_1 atomic transition. Using a gray molasses scheme, we efficiently cool a compressed cloud of 6.5x10^8 atoms from ~ 4\\mK to 20uK in 8 ms. After transfer in a quadrupole magnetic trap, we measure a phase space density of ~10^-5. This technique offers a promising route for fast evaporation of fermionic 40K.

Fernandes, Diogo Rio; Kretzschmar, Norman; Wu, Saijun; Salomon, C; Chevy, Frédéric

2012-01-01

280

Sub-Doppler laser cooling of fermionic 40K atoms in three-dimensional gray optical molasses  

Science.gov (United States)

We demonstrate sub-Doppler cooling of 40K on the D1 atomic transition. Using a gray-molasses scheme, we efficiently cool a compressed cloud of 6.5 × 108 atoms from ˜4 mK to 20 ?K in 8 ms. After transfer to a quadrupole magnetic trap, we measure a phase space density of ˜10-5. This technique offers a promising route for fast evaporation of fermionic 40K.

Rio Fernandes, D.; Sievers, F.; Kretzschmar, N.; Wu, S.; Salomon, C.; Chevy, F.

2012-12-01

281

Simultaneous sub-Doppler laser cooling of fermionic $^6$Li and $^{40}$K on the D$_1$ line: Theory and Experiment  

CERN Document Server

We report on simultaneous sub-Doppler laser cooling of fermionic $^6$Li and $^{40}$K using the D$_1$ optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semi-classical Monte Carlo wavefunction method. The simulation takes into account the three dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the D$_1$ transitions. We discuss the physical mechanisms at play, we identify the important role of coherences between the ground state hyperfine levels and compare D$_1$ and D$_2$ sub-Doppler cooling. In 5 ms, the D$_1$ molasses phase largely reduces the temperature for both $^6$Li and $^{40}$K at the same time, with a final temperature of 44 $\\mu$K and 11 $\\mu$K, respectively. For both species this leads to a phase-space density close to $10^{-4}$. These conditions are well suited to directly load an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.

Sievers, Franz; Kretzschmar, Norman; Fernandes, Diogo Rio; Suchet, Daniel; Rabinovic, Michael; Parker, Colin V; Khaykovich, Lev; Salomon, Christophe; Chevy, Frédéric

2014-01-01

282

Simultaneous sub-Doppler laser cooling of fermionic 6Li and 40K on the D1 line: Theory and experiment  

Science.gov (United States)

We report on simultaneous sub-Doppler laser cooling of fermionic 6Li and 40K using the D1 optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semiclassical Monte Carlo wave-function method. The simulation takes into account the three-dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the D1 transitions. We discuss the physical mechanisms at play, identify the important role of coherences between the ground-state hyperfine levels, and compare D1 and D2 sub-Doppler cooling. In 5 ms, the D1 molasses phase greatly reduces the temperature for both 6Li and 40K at the same time, with final temperatures of 44 and 11 ? K , respectively. For both species this leads to a phase-space density close to 10-4. These conditions are well suited to direct loading of an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.

Sievers, Franz; Kretzschmar, Norman; Fernandes, Diogo Rio; Suchet, Daniel; Rabinovic, Michael; Wu, Saijun; Parker, Colin V.; Khaykovich, Lev; Salomon, Christophe; Chevy, Frédéric

2015-02-01

283

Laser Doppler sensor employing a single fan-shaped interference fringe system for distance and shape measurement of laterally moving objects  

International Nuclear Information System (INIS)

For monitoring the position and shape of fast moving and, especially, rotating objects such as turbo machine rotors, contactless and compact sensors with a high measurement rate as well as high precision are required. We present for the first time, to the best of our knowledge, a novel laser Doppler sensor employing a single fan-shaped interference fringe system, which allows measuring for the position and shape of fast moving solid bodies with known tangential velocity. It is shown theoretically as well as experimentally that this sensor offers concurrently high position resolution and high temporal resolution in contrast to conventional measurement techniques, since its measurement uncertainty is, in principle, independent of the object velocity. Moreover, it can be built very compact, because it features low complexity. To prove its operational capability and its potential for practical applications, radial and axial shape measurements of rotating bodies are demonstrated in comparison with triangulation. An average position resolution of about 2 ?m could be achieved

284

Studies of the flow of air in a model mixed-flow pump by laser Doppler anemometry. Part 2: Velocity measurements within the impeller  

Science.gov (United States)

The behavior of air in the rotor of a model mixed-flow bowl pump was investigated using a laser Doppler anemometer. The model was operated at 4 different flowrates at the same rotational speed (1200 rpm); the best efficiency point, and 3 off-design points in an unstable region of the performance characteristic. For each flowrate, the blade-to-blade distributions of three-dimensional velocities were mapped within the rotor, and at inlet and outlet. The results of the flow surveys show complex flow phenomena occurring within the model, and the way the structure of the flow changes as the flowrate is reduced. The velocity distributions observed at the best efficiency point, and the predictions of a through-flow calculation used in the computer-aided design process for this machine are compared.

Carey, C.; Fraser, S. M.; Rachman, D.; Wilson, G.

1985-11-01

285

Optic nerve head blood flow using a laser Doppler velocimeter and haemorheology in primary open angle glaucoma and normal pressure glaucoma.  

Science.gov (United States)

Optic disc blood flow velocity was measured in healthy patients, those with primary open angle glaucoma (POAG), and patients with normal pressure glaucoma (NPG). The velocity of the red blood cells (RBCs) in the capillaries of the optic nerve head (ONH) has been measured with a laser Doppler velocimeter (LDV), and blood viscosity has been evaluated notably by determining the aggregability of the RBCs with an erythroaggregameter. Our results in POAG patients and NPG patients showed that their optic nerve blood flow velocity was reduced and that the aggregability of the RBCs was increased. The hyperaggregability of the erythrocytes is responsible for the increase of the local viscosity in the papillary capillary network. These haemodynamic modifications observed in patients with glaucoma support the hypothesis of a vasogenic mechanism that could impair the optic nerve in glaucoma patients. PMID:8060927

Hamard, P; Hamard, H; Dufaux, J; Quesnot, S

1994-01-01

286

Space Shuttle Hypergol Load Determination Using Nonintrusive Ultrasonic Flowmeters  

Science.gov (United States)

Space Shuttle preflight hypergol oxidizer and fuel loading were monitored using a nonintrusive flow measurement system (NFMS) during preflight operation. A pair of 4-megahertz ultrasonic transducers measured the flow rate using a transit-time flow measurement technique. Using wireless cellular phone technology, flow-rate data was monitored and recorded. Excellent correlation was observed between the flow profiles measured using the proposed nonintrusive ultrasonic flowmeters (UFM's) and those made from conventional intrusive turbine meters (TFM). Based on the preliminary tests, it is concluded that the nonintrusive method of flow measurement has the same or higher accuracy, is simpler, and costs less than the existing TFM. Benefits of UFM's include a highly flexible, cost-effective, reliable, hazard free, and streamlined hypergol operation. Redundant installation of ultrasonic flowmeters was recommended for a few more launches prior to the replacement of the existing TFM.

Werlink, Rudolph; Kelley, Andrew; Margasahayam, Ravi

1996-01-01

287

Experimental Research of Crosscorrelation-Based Virtual Dynamic Flowmeter  

International Nuclear Information System (INIS)

An innovated method for measuring dynamic flow is put forward, and a virtual dynamic flowmeter is established. Basing on the principle of pressure pulse containing the flow information, for the dynamic laminar flow, by means of collecting the pressure signals at two points at interval of L and processing them with crosscorrelation calculation, then the transit time is gained, consequently the average flow rate can be got. This calculation is prosecuted repeatedly according to a certain time step length, thus the average flow rates in each time slice can be acquired. If the step length is decreased to zero, the piecewise average flow rate is approximate to the instant dynamic flow. In order to calibrate the virtual dynamic flowmeter, the unloaded servo cylinder was used for the contrasting experiment. The accuracy and validity of this approach has been proved

288

Improvement of application range of ultrasonic flowmeters to small pipes  

Energy Technology Data Exchange (ETDEWEB)

The clamp-on technique enables the noninvasive measurement of flow in pipes by mounting the transducers to the pipe wall. A low efficiency of sound energy transmission of the excited wave to the pipe is caused by a line-type coupling between the plane transducer wedge and the curved pipe wall especially for small pipes. The consequences of scaling up the working frequency are discussed in the paper. As an alternative a novel noninvasive flowmeter with transducers of conical shape adapted to the pipe wall curvature is proposed to improve the coupling efficiency for small pipes. The frequency and incident angle selective properties of the pipe wall are analyzed to optimize the flowmeter arrangement. The influence of the acoustic behavior on the received signals will be discussed and compared with experimental results given for different flow meter arrangements. (orig.)

Panicke, M. [Rostock Univ. (Germany). Inst. fuer Allgemeine Elektrotechnik

2001-07-01

289

Doppler-free laser spectroscopy measurements on a Ne discharge for determination of 22Ne-20Ne isotope shifts  

International Nuclear Information System (INIS)

The authors have used Doppler-free polarization spectroscopy, intermodulated fluorescence and intermodulated optogalvanic spectroscopy for measuring isotope shifts in 6 Ne lines connecting the 2p53s and 2p53p configurations. The measurements were performed on two different hollow cathodes. For the 5852, 5882, 5945, 5976, 6143 and 6164 A lines the 22Ne-20Ne isotope shift was found to be 2300(15), 1740(2), 1717(3), 1728(5), 1669(4) and 1663(5) MHz, respectively. These results are in fair agreement with previous optical spectroscopy data. (Auth.)

290

Doppler-free intermodulated fluorescence spectroscopy of $^4He$ $2^3P-3^{1,3}D$ transitions at 588 nm with a one-watt compact laser system  

CERN Document Server

We have demonstrated Doppler-free intermodulated fluorescence spectroscopy of helium $2^3P-3^{1,3}D$ transitions in an rf discharged sealed-off cell using a compact laser system at 588 nm. An external cavity diode laser at 1176 nm was constructed to seed a Raman fiber amplifier. Laser power of more than one watt at 588 nm was produced by frequency doubling of the fiber amplifier output using a MgO:PPLN crystal. A doubling efficiency of 23 % was achieved. The power-dependent spectra of the $2^3P-3^3D$ transitions were investigated. Furthermore, the Doppler-free spectrum of the spin-forbidden $2^3P-3^1D$ transitions was observed for the first time. Our results are crucial towards precision test of QED atomic calculations, especially for improving the determination of the helium $3^1D-3^3D$ separation.

Luo, Pei-Ling; Feng, Yan; Wang, Li-Bang; Shy, Jow-Tsong

2015-01-01

291

In-sodium test of ultra-sonic flowmeter for fast breeder reactor  

International Nuclear Information System (INIS)

Developments on the ultra-sonic flowmeters, which are used widely in the water loop, have been carried out for the application on the sodium loop in fast breeder reactor. This is because of that ultra-sonic flowmeters have several characteristics needed to the large pipe sodium flowmeter, i.e. good linearity, lightweight, leak tight, low cost etc.. After fundamental improvement about the settling method of transducer to high temperature duct and about measurement circuit were developed, in-water tests were conducted and effectiveness of such improvements were confirmed. So 12 B and 24 B ultra-sonic flowmeters were made after additions of several improvements to high temperature problems, and tested in the sodium loop, and it is confirmed that the ultra-sonic flowmeters have superior characteristics as the sodium flowmeters. In the sodium temperature (200 ? 400 deg C) and flow rate (0 ? 6 m/s), linearity and repeatability were within ± 1 %. And effect of upper flow straight pipe length to the ultra-sonic flowmeter output was smaller than in water loop tests. This paper describes mainly the above results of sodium flow tests which showed that ultra-sonic flowmeters are useful as the sodium flowmeter. (author)

292

The wide-range ejector flowmeter: calibrated gas evacuation comprising both high and low gas flows.  

Science.gov (United States)

The wide-range ejector flowmeter is an active scavenging system applying calibrated gas removal directly to the anaesthetic circuit. The evacuation rate can be adjusted on the flowmeter under visual control using the calibration scale ranging from 200 ml X min-1 to 151 X min-1. The accuracy of the calibration was tested on three ejector flowmeters at 12 different presettings. The percentage deviation from presetting varied from + 18 to - 19.4 per cent. The ejector flowmeter enables the provision of consistent and accurately calibrated extraction of waste gases and is applicable within a wide range of fresh gas flows. PMID:6238660

Waaben, J; Brinkløv, M M; Jørgensen, S

1984-11-01

293

In-plant calibration of magnetic flowmeters in the pulp and paper industries  

International Nuclear Information System (INIS)

A number of magnetic flowmeters for pulp flow measurements were calibrated by means of the tracer velocity method during working conditions. Some of the meters were calibrated regularly during a period of more than 2 yr. The deviations between tracer measurements and flowmeter readings varied from -20% to + 30%. Some possible sources of error are discussed. The results clearly show the necessity of in-plant calibrations of magnetic flowmeters when accurate flow values are needed, which is usually the case when expensive flowmeters like the magnetic ones are used. (author)

294

Flowmeter and Ground Penetrating Radar: comparison between hydrogeological and geophysical methods  

OpenAIRE

We discuss a comparison between saturated hydraulic conductivity calculated with Electromagnetic Borehole Flowmeter (EBF) and water content obtained by Ground Penetrating Radar (GPR) Zero Offset Profile (ZOP)

Arato, Alessandro; Villa, Alberto; Godio, Alberto

2012-01-01

295

A study on applicability of ultrasonic flowmeter for feedwater flow measurements using measurement uncertainty analysis  

International Nuclear Information System (INIS)

The measurement uncertainties of an ultrasonic flowmeter and current venturi meter were analyzed to evaluate an applicability of ultrasonic flowmeter on measuring main feedwater flow rate in a nuclear power plant. The measurement uncertainty of a reactor power was also analyzed using the measurement uncertainties of flow meters. The ultrasonic flowmeter was installed on a feedwater pipe line of a typical 1000 MWe Korean Standardized Nuclear Power Plant and the collected data were used in the analyses. The results have indicated that the measurement uncertainty of reactor power on using the ultrasonic flowmeter are sufficiently enhanced within the uncertainty range assumed in the safety analysis

296

Flowmeters for use in the nuclear industry: How to select the appropriate instrument  

International Nuclear Information System (INIS)

Because flow is one of the most common process variables measured, numerous types of flowmeters based on a variety of measurement principles are available. Although these numerous flowmeter types allow one to measure almost any flow, the wide variety also makes selecting an appropriate flowmeter a complex and potentially difficult task. This paper reviews the definition and importance of basic hydraulic principles and the design parameters critical to an accurate flow measurement, the principles used in flow monitoring and their advantages and disadvantages, and a method for selecting an appropriate flowmeter. 6 refs

297

Calibration of a miniature permanent magnet flowmeter probe for velocity and temperature measurement in sodium  

International Nuclear Information System (INIS)

For the calibration of a miniature permanent magnet flowmeter probe, the working principle of which is based on the induction law, a measuring specification is given which allows to determine reproducibly the sensitivity of the flowmeter probe and the zero offsets of the temperature compensated voltages. The flowmeter probe has an outer diameter of 2.5 mm and is equipped with three-wire-thermocouples (Alumel/Chromel/stainless steel). The K- and S-values which are characteristic of the flowmeter probe are determined and discussed. (orig.)

298

A High-Pressure Bi-Directional Cycloid Rotor Flowmeter  

OpenAIRE

The measurement of the flow rate of various liquids and gases is critical in industrial automation. Rotary positive displacement meters (rotary PD meters) are highly accurate flowmeters that are widely employed in engineering applications, especially in custody transfer operations and hydraulic control systems. This paper presents a high pressure rotary PD meter containing a pair of internal cycloid rotors. It has the advantages of concise structure, low pressure loss, high accuracy and low n...

Shuo Liu; Fan Ding; Chuan Ding; Zaipeng Man

2014-01-01

299

A High-Pressure Bi-Directional Cycloid Rotor Flowmeter  

Directory of Open Access Journals (Sweden)

Full Text Available The measurement of the flow rate of various liquids and gases is critical in industrial automation. Rotary positive displacement meters (rotary PD meters are highly accurate flowmeters that are widely employed in engineering applications, especially in custody transfer operations and hydraulic control systems. This paper presents a high pressure rotary PD meter containing a pair of internal cycloid rotors. It has the advantages of concise structure, low pressure loss, high accuracy and low noise. The curve of the internal rotor is designed as an equidistant curtate epicycloid curve with the external rotor curve as its conjugate. The calculation method used to determine the displacement of the cycloid rotor flowmeter is discussed. A prototype was fabricated, and experiments were performed to confirm measurements over a flow range of 1–100 L/min with relative errors of less than ±0.5%. The pressure loss through the flowmeter was about 3 bar at a flow rate of 100 L/min.

Shuo Liu

2014-08-01

300

Skew photonic Doppler velocimetry to investigate the expansion of a cloud of droplets created by micro-spalling of laser shock-melted metal foils  

Energy Technology Data Exchange (ETDEWEB)

Dynamic fragmentation in the liquid state after shock-induced melting, usually referred to as micro-spallation, is an issue of great interest for both basic and applied sciences. Recent efforts have been devoted to the characterization of the resulting ejecta, which consist in a cloud of fine molten droplets. Major difficulties arise from the loss of free surface reflectivity at shock breakout and from the wide distribution of particle velocities within this cloud. We present laser shock experiments on tin and aluminium, to pressures ranging from about 70 to 160 GPa, with complementary diagnostics including a photonic Doppler velocimeter set at a small tilt angle from the normal to the free surface, which enables probing the whole cloud of ejecta. The records are roughly consistent with a one-dimensional theoretical description accounting for laser shock loading, wave propagation, phase transformations, and fragmentation. The main discrepancies between measured and calculated velocity profiles are discussed in terms of edge effects evidenced by transverse shadowgraphy.

Loison, D.; Resseguier, T. de; Dragon, A. [Institut P' , UPR 3346, CNRS, Universite de Poitiers, ISAE-ENSMA - 1, av Clement Ader, 86961 Futuroscope (France); Mercier, P.; Benier, J.; Deloison, G.; Lescoute, E.; Sollier, A. [CEA, DAM, DIF - 91297 Arpajon (France)

2012-12-01

301

Simultaneous three-dimensional velocity and mixing measurements by use of laser Doppler velocimetry and fluorescence probes in a water tunnel  

Science.gov (United States)

A water tunnel investigation was conducted to demonstrate the capabilities of a laser-based instrument that can measure velocity and fluorescence intensity simultaneously. Fluorescence intensity of an excited fluorescent dye is directly related to concentration level and is used to indicate the extent of mixing in flow. This instrument is a three-dimensional laser Doppler velocimeter (LDV) in combination with a fluorometer for measuring fluorescence intensity variations. This capability allows simultaneous flow measurements of the three orthogonal velocity components and mixing within the same region. Two different flows which were generated by two models were studied: a generic nonaxisymmetric nozzle propulsion simulation model with an auxiliary internal water source that generated a jet flow and an axisymmetric forebody model with a circular sector strake that generated a vortex flow. The off-body flow fields around these models were investigated in the Langley 16- by 24-Inch Water Tunnel. The experimental results were used to calculate 17 quantities that included mean and fluctuating velocities, Reynolds stresses, mean and fluctuating dye fluorescence intensities (proportional to concentration), and fluctuating velocity and dye concentration correlations. An uncertainty analysis was performed to establish confidence levels in the experimental results. In general, uncertainties in mean velocities varied between 1 and 7 percent of free-stream velocity; uncertainties in fluctuating velocities varied between 1 and 5 percent of reference values. The results show characteristics that are unique to each type of flow.

Neuhart, Dan H.; Wing, David J.; Henderson, Uleses C., Jr.

1994-01-01

302

Doppler photoacoustic and Doppler ultrasound in blood with optical contrast agent  

Science.gov (United States)

Photoacoustic Doppler flowmetry as well as Doppler ultrasound were performed in acoustic resolution regime on tubes filled with flowing blood with indocyanine green (ICG) at different concentrations. The photoacoustic excitation utilized a pair of directly-modulated fiber-coupled 830nm laser-diodes, modulated with either CW or tone-bursts for depthresolved measurements. The amplitude of the Doppler peak in photoacoustic Doppler measurements was found to be proportional to the ICG concentration. Photoacoustic Doppler was measured in ICG at human safe concentrations, but not in whole blood. Comparing the results between the two modalities implied that using a wavelength with higher optical absorption may improve the photoacoustic signal in blood.

Sheinfeld, Adi; Eyal, Avishay

2013-03-01

303

Output-only Modal Analysis using Continuous-Scan Laser Doppler Vibrometry and application to a 20 kW wind turbine  

Science.gov (United States)

Continuous-Scan Laser Doppler Vibrometry (CSLDV) is a technique where the measurement point continuously sweeps over a structure while measuring, capturing both spatial and temporal information. The continuous-scan approach can greatly accelerate measurements, allowing one to capture spatially detailed mode shapes in the same amount of time that conventional methods require to measure the response at a single point. The method is especially beneficial when testing large structures, such as wind turbines, that have low natural frequencies and hence may require very long time records at each measurement point. Several CSLDV methods have been presented that use sinusoidal excitation or impulse excitation, but CSLDV has not previously been employed with an unmeasured, broadband random input. This work extends CSLDV to that class of input, developing an Output-only Modal Analysis method (OMA-CSLDV). A recently developed algorithm for linear time-periodic system identification, which makes use of harmonic power spectra and the harmonic transfer function concept developed by Wereley [17], is used in conjunction with CSLDV measurements. One key consideration, the choice of the scan frequency, is explored. The proposed method is validated on a randomly excited free-free beam, where one-dimensional mode shapes are captured by scanning the laser along the length of the beam. The first seven natural frequencies and mode shapes are extracted from the harmonic power spectrum of the vibrometer signal and show good agreement with the analytically-derived modes of the beam. The method is then applied to identify the mode shapes of a parked 20 kW wind turbine using a ground based laser and with only a light breeze providing excitation.

Yang, Shifei; Allen, Matthew S.

2012-08-01

304

Sub-doppler spectroscopy with a frequency-doubled tunable single-frequency Nd:YAG laser  

International Nuclear Information System (INIS)

In the authors system, the master laser is a diode-laser-pumped mini-YAG/sup 3/ with single-frequency pulsed output power of 50 mW, while the slave oscillator is a modified commercial (Quanta-Ray DCR-1A) Nd:YAG systems which outputs 0.7 J with a single amplifier stage. Cavity matching of the master and slave resonators is achieved by using a feed-back scheme similar to the polarization technique introduced by a previous work. The authors' approach, which relies on the presence of finite strain in the mini-YAG crystal resonator, detects the depolarization of light reflected by this resonator whenever the incident wave matches the Fabry-Perot resonance. Once locked, the longterm frequency stability of the system is clearly governed by the temperature stability of the mini-YAG laser (a change in temperature of only 0.010 results in a frequency drift of 31 MHz)

305

Accuracy improvement of ultrasonic flowmeter for nuclear power station. 1st report. Influence of three-dimensional upstream pipe condition  

International Nuclear Information System (INIS)

An ultrasonic flowmeter is considered to replace flow nozzle and orifice meter as a main feedwater flowmeter in nuclear power station. This paper describes the first examination about the influence of the upstream condition using a cramp-on type ultrasonic flowmeter. (author)

306

Evolution of Magnetic Flowmeters: Technological Innovation Makes a Proven Meter Type More Useful  

Science.gov (United States)

This article from the Flow Control Network discusses magnetic flowmeters. To counteract the disadvantages of continuous AC magmeters, while retaining some of the advantages of pulsed DC meters, some suppliers have introduced pulsed AC magnetic flowmeters. The article also includes a brief history of AC and DC MFCs.

Yoder, Jesse

307

Practical experience of using thermal-mass flowmeters at the registration associated (free) petroleum gas  

Science.gov (United States)

The results of field tests of thermal-mass flowmeter TurboFlow TFG-S in comparison with ultrasonic flowmeter Dymetic-1223K at existing oil and gas extraction object are given in the article. Measured medium – associated (free) petroleum gas.

Fazlyyyakhmatov, M. G.; Kashapov, N. F.; Khayritonov, Kh A.; Lazarev, D. K.; Lazarev, V. K.

2014-12-01

308

Metrological problems in flowmeter calibration by means of primary fluid flow facilities  

Energy Technology Data Exchange (ETDEWEB)

Problems in the calibration of pipeline flowmeters with excellent metrological performances are discussed, particularly for flowmeters with a repeatibility of the same order of the global uncertainity of primary fluid flow facilities. Some significant calibration curves obtained by the authors in IMGC (Italy) primary fluid flow facilities are presented and discussed.

Cascetta, F.; Vigo, P.; Cignolo, G.

1988-06-01

309

The character of swirl in turbulent pipe flow with reference to its effect on flowmeters  

OpenAIRE

A theoretical and experimental investigation of the character of in turbulent pipe flow has been carried out and some implications for the use of flowmeters considered. An extensive survey of Industrial users of flowmeters has been made, involving the participation of over 70 companies, which provides information about current industrial practice, attitudes and understanding. Axisymmetric perturbations of fully developed turbulent pipe ...

Halsey, D. M.

1986-01-01

310

Comparison of the bioactivity of mometasone furoate 0.1% fatty cream, betamethasone dipropionate 0.05% cream and betamethasone valerate 0.1% cream in humans. Inhibition of UV-B-induced inflammation monitored by laser Doppler blood flowmetry.  

Science.gov (United States)

The bioactivity of a novel topical glucocorticosteroid, mometasone furoate 0.1% fatty cream was compared with betamethasone dipropionate 0.05% cream and betametasone valerate 0.1% cream. An ultraviolet light (UV-B)-induced inflammation assay in humans was used, and the combined effect of a single, open application of the corticosteroids was evaluated. Reduction of UV-B induced inflammation was monitored by laser Doppler blood flowmetry, clinical skin scoring and skin reflectance spectrophotometry. Skin scoring and reflectance spectrophotometry were found unsuitable because one of the cream vehicles contained titanium dioxide which shielded skin erythema. Laser Doppler blood flowmetry showed that mometasone furoate 0.1% fatty cream was more than twofold better in reducing UV-B-induced inflammation than betamethasone dipropionate 0.05% cream and betametasone valerate 0.1% cream, and that the effect was sustained for at least 24 h after a single application. PMID:8274288

Bjerring, P

1993-01-01

311

Evaluation of several ultrasonic flowmeter transducers in cryogenic environment  

Science.gov (United States)

Eighteen piezoelectric ultrasonic flowmeter transducers were laboratory tested to determine their suitability and long range reliability for use by the National Transonic Facility (NTF) to measure the flow rate of 450 Kg/sec of liquid nitrogen (LN2). Tests included thermally cycling each transducer 50 to 150 times over a temperature range of 295 K (ambient) to 77 K (LN2). The transducers were submerged in liquid nitrogen for 1 to 4 hours and the signal strength and quality noted. Results disclose that the current state-of-the-art ultrasonic flow transducers are very reliable and will meet the stringent requirements of the NTF.

Moughon, W. C.

1981-04-01

312

The use of spectral skin reflectivity and laser doppler vibrometry data to determine the optimal site and wavelength to collect human vital sign signatures  

Science.gov (United States)

The carotid artery has been used extensively by researchers to demonstrate that Laser Doppler Vibrometry (LDV) is capable of exploiting vital sign signatures from cooperative human subjects at stando. Research indicates that, the carotid, although good for cooperative and non-traumatic scenarios, is one of the first vital signs to become absent or irregular when a casualty is hemorrhaging and in progress to circulatory (hypovolemic) shock. In an effort to determine the optimal site and wavelength to measure vital signs off human skin, a human subject data collection was executed whereby 14 subjects had their spectral skin reflectivity and vital signs measured at five collection sites (carotid artery, chest, back, right wrist and left wrist). In this paper, we present our findings on using LDV and re ectivity data to determine the optimal collection site and wavelength that should be used to sense pulse signals from quiet and relatively motionless human subjects at stando. In particular, we correlate maximum levels of re ectivity across the ensemble of 14 subjects with vital sign measurements made with an LDV at two ranges, for two scenarios.

Byrd, Kenneth A.; Kaur, Balvinder; Hodgkin, Van A.

2012-06-01

313

Study of time reversibility/irreversibility of cardiovascular data: theoretical results and application to laser Doppler flowmetry and heart rate variability signals  

Science.gov (United States)

Time irreversibility can be qualitatively defined as the degree of a signal for temporal asymmetry. Recently, a time irreversibility characterization method based on entropies of positive and negative increments has been proposed for experimental signals and applied to heart rate variability (HRV) data (central cardiovascular system (CVS)). The results led to interesting information as a time asymmetry index was found different for young subjects and elderly people or heart disease patients. Nevertheless, similar analyses have not yet been conducted on laser Doppler flowmetry (LDF) signals (peripheral CVS). We first propose to further investigate the above-mentioned characterization method. Then, LDF signals, LDF signals reduced to samples acquired during ECG R peaks (LDF_RECG signals) and HRV recorded simultaneously in healthy subjects are processed. Entropies of positive and negative increments for LDF signals show a nonmonotonic pattern: oscillations—more or less pronounced, depending on subjects—are found with a period matching the one of cardiac activity. However, such oscillations are not found with LDF_RECG nor with HRV. Moreover, the asymmetry index for LDF is markedly different from the ones of LDF_RECG and HRV. The cardiac activity may therefore play a dominant role in the time irreversibility properties of LDF signals.

Humeau-Heurtier, Anne; Mahé, Guillaume; Chapeau-Blondeau, François; Rousseau, David; Abraham, Pierre

2012-07-01

314

Comparison of neovascularization in dermal substitutes seeded with autologous fibroblasts or impregnated with bFGF applied to diabetic foot ulcers using laser Doppler imaging.  

Science.gov (United States)

A bilayered artificial dermis (AD) composed of an upper silicone sheet and a lower collagen sponge has been widely applied for skin defects. After application, fibroblasts and capillaries infiltrate the AD and the collagen sponge is replaced by host dermal tissue within a few weeks. However, this delay and the high incidence of infection are concerns regarding the use of AD in the treatment of chronic ulcers. In this study, we compared the neovascularization of conventional AD seeded with autologous fibroblasts (cultured dermis: CD) and collagen/gelatin sponge (CGS), which is a novel artificial dermis capable of sustained release of basic fibroblast growth factor (bFGF) after application using laser Doppler imaging (LDI). CD (n = 5) and CGS impregnated with bFGF (n = 6) were applied to diabetic foot ulcers after debridement. Perfusion units (PUs) were measured just after, and 1, 2 and 3 weeks after application, and complete healing rates within 16 weeks were compared. No significant differences in PUs were seen 1, 2 and 3 weeks after application and in healing rates within 16 weeks between the two groups. This study suggested that CD and CGS treatments were effective, but there were no significant differences between them in the treatment of diabetic ulcers . PMID:25028148

Morimoto, Naoki; Kakudo, Natsuko; Valentin Notodihardjo, Priscilla; Suzuki, Shigehiko; Kusumoto, Kenji

2014-12-01

315

Simulations and Measurements of Human Middle Ear Vibrations Using Multi-Body Systems and Laser-Doppler Vibrometry with the Floating Mass Transducer  

Directory of Open Access Journals (Sweden)

Full Text Available The transfer characteristic of the human middle ear with an applied middle ear implant (floating mass transducer is examined computationally with a Multi-body System approach and compared with experimental results. For this purpose, the geometry of the middle ear was reconstructed from ?-computer tomography slice data and prepared for a Multi-body System simulation. The transfer function of the floating mass transducer, which is the ratio of the input voltage and the generated force, is derived based on a physical context. The numerical results obtained with the Multi-body System approach are compared with experimental results by Laser Doppler measurements of the stapes footplate velocities of five different specimens. Although slightly differing anatomical structures were used for the calculation and the measurement, a high correspondence with respect to the course of stapes footplate displacement along the frequency was found. Notably, a notch at frequencies just below 1 kHz occurred. Additionally, phase courses of stapes footplate displacements were determined computationally if possible and compared with experimental results. The examinations were undertaken to quantify stapes footplate displacements in the clinical practice of middle ear implants and, also, to develop fitting strategies on a physical basis for hearing impaired patients aided with middle ear implants.

Tobias Strenger

2013-10-01

316

Semi-invasive laser-Doppler flowmetry technique. New application for recordings of hemodynamics in combination with manometry of human small intestine.  

Science.gov (United States)

A small-bowel manometry tube was supplied with two single-fiber microprobes, which recorded blood flow in the proximal small intestine by the laser-Doppler flowmetry (LDF) technique. In all experiments, saline was infused intravenously as control during the first migrating motor complex (MMC) cycle, and a drug or another saline control given intravenously during the second MMC cycle. Recordings were performed during phase 1 of MMC, i.e. when motor pattern showed quiescence. Adrenaline increased blood perfusion values by 140% in proximal duodenum and 95% in distal duodenum. The alpha 2-adrenoceptor agonist clonidine decreased the corresponding values by 34 and 25%, respectively, while oxymetazoline decreased perfusion by 33 and 44% at the same levels. The beta-adrenoceptor agonist isoprenaline increased blood perfusion values by 172% in the proximal duodenum and 194% in the distal duodenum, whereas the antagonist propranolol decreased the corresponding values by 45 and 52%, respectively. In a separate group of subjects, propranolol was given after adrenaline. The increase in blood perfusion regularly seen after adrenaline was blocked after propranolol administration. In conclusion, our findings validate semi-invasive LDF technique for studies of hemodynamics in human small intestine under basal motor conditions and in drug-induced blood flow changes. PMID:9176721

Thollander, M; Hellström, P M; Gazelius, B

1997-01-01

317

Fisher information and Shannon entropy for on-line detection of transient signal high-values in laser Doppler flowmetry signals of healthy subjects  

International Nuclear Information System (INIS)

Laser Doppler flowmetry (LDF) is an easy-to-use method for the assessment of microcirculatory blood flow in tissues. However, LDF recordings very often present TRAnsient Signal High-values (TRASH), generally of a few seconds. These TRASH can come from tissue motions, optical fibre movements, movements of the probe head relative to the tissue, etc. They often lead to difficulties in signal global interpretations. In order to test the possibility of detecting automatically these TRASH for their removal, we process noisy and noiseless LDF signals with two indices from information theory, namely Fisher information and Shannon entropy. For this purpose, LDF signals from 13 healthy subjects are recorded at rest, during vascular occlusion of 3 min, and during post-occlusive hyperaemia. Computation of Fisher information and Shannon entropy values shows that, when calibrated, these two indices can be complementary to detect TRASH and be insensitive to the rapid increases of blood flow induced by post-occlusive hyperaemia. Moreover, the real-time algorithm has the advantage of being easy to implement and does not require any frequency analysis. This study opens new fields of application for Fisher information and Shannon entropy: LDF 'denoising'

318

Time-frequency analysis of laser Doppler flowmetry signals recorded in response to a progressive pressure applied locally on anaesthetized healthy rats  

International Nuclear Information System (INIS)

The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal, in response to a local non-noxious pressure applied progressively on the skin of both healthy humans and rats. This phenomenon is not entirely understood yet. In the present work, a time-frequency analysis is applied to signals recorded on anaesthetized healthy rats, at rest and during a cutaneous pressure-induced vasodilation (PIV). The comparison, at rest and during PIV, of the scalogram relative energies and scalogram relative amplitudes in five bands, corresponding to five characteristic frequencies, shows an increased contribution for the endothelial related metabolic activity in PIV signals, till 400 s after the beginning of the progressive pressure application. The other subsystems (heart, respiration, myogenic and neurogenic activities) contribute relatively less during PIV than at rest. The differences are statistically significant for all the relative activities in the interval 0-200 s following the beginning of the pressure. These results and others obtained on patients, such as diabetics, could increase the understanding of some cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers

319

Comparison between Hilbert-Huang transform and scalogram methods on non-stationary biomedical signals: application to laser Doppler flowmetry recordings  

International Nuclear Information System (INIS)

A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application on healthy subjects. This reflex may be impaired in diabetic patients. The work presents a comparison between two signal processing methods that provide a clarification of this phenomenon. Analyses by the scalogram and the Hilbert-Huang transform (HHT) of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied at different time intervals in order to take into account the dynamics of the phenomenon. The results show that both the scalogram and the HHT methods lead to the same conclusions concerning the comparisons of the myogenic, neurogenic and endothelial related metabolic activities-during the progressive pressure and at rest-in healthy and diabetic subjects. However, the HHT shows more details that may be obscured by the scalogram. Indeed, the non-locally adaptative limitations of the scalogram can remove some definition from the data. These results may improve knowledge on the above-mentioned reflex as well as on non-stationary biomedical signal processing methods

320

Some experiments in swirling flows: Detailed velocity measurements of a vortex breakdown using a laser Doppler anemometer. Ph.D. Thesis - Cornell Univ. Final Report  

Science.gov (United States)

The results of an experimental study of spiraling flows in a slightly diverging, circular duct are reported. Seven types of flow disturbances were observed. In addition to the spiral and axisymmetric vortex breakdowns and the double helix mode, four other forms were identified and are reported. The type and axial location of the disturbance depended on the Reynolds and circulation numbers of the flow. Detailed velocity measurements were made by using a laser Doppler anemometer. Measurements made far upstream of any disturbance showed that the introduction of swirl resulted in the formation of a high axial velocity jet centered around the vortex center. A mapping of the velocity field of a so-called axisymmetric breakdown, formed at a Reynolds number of 2560, revealed that the recirculation zone is a two-celled structure, with four stagnation points on the vortex axis marking the axial extremes of the concentric cells. The dominant feature of the flow inside the bubble was the strong, periodic velocity fluctuations. Existing theoretical models do not predict the two-celled structure and the temporal velocity fluctuations that were observed.

Faler, J. H.

1976-01-01

321

Non-invasive monitoring and quantitative analysis of patch test reactions by reflectance spectrophotometry, laser Doppler flowmetry and transepidermal water loss  

Science.gov (United States)

Reflectance spectrophotometry (RS), laser Doppler flowmetry (LDF) and transepidermal water loss (TEWL) techniques were simultaneously used to non-invasively monitor skin colour (SC), skin blood flow (SBF) and barrier function damage (BFD) in routinely patch-tested Japanese patients in dermatology clinic. The analytical quality, reliability and reproducibility of each technique were compared and analyzed in correlated to visual scoring patch test (PT) reactions as negative (-), doubtful (+?), weak (+) and strong (++/+++) at 48- and 72-hour monitoring. An attempt was made to quantify predominant in the clinic "+?"- and "+'"-PT-reactions. The relationship between 48 h and 72 h measurements in different reaction groups was poor for TEWL, LDF showed a tendency to decrease at 72 h, but good for RS. A correlation between visual scorings and instrumental mean values was poor for TEWL, good for LDF and excellent for RS. So, measurements by RS were the most statistically significant to non-invasively monitor and quantify doubtful, weak and strong PT reactions, accordingly providing continuous data grading of reaction intensity suitable in the clinic. Moreover, monitoring of SC changes was the most reliable parameter for the quantitative distinguishing of doubtful and weak reactions in pigmented skin.

Eikje, Natalja Skrebova; Arase, Seiji

2008-02-01

322

Spectral components of laser Doppler flowmetry signals recorded in healthy and type 1 diabetic subjects at rest and during a local and progressive cutaneous pressure application: scalogram analyses  

International Nuclear Information System (INIS)

A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application in healthy subjects. This reflex may be impaired in diabetic patients. The work presents a signal processing providing the clarification of this phenomenon. Scalogram analyses of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied. The results show that, at rest, the scalogram energy of each frequency band is significantly lower for diabetic patients than for healthy subjects, but the scalogram relative energies do not show any statistical difference between the two groups. Moreover, the neurogenic and endothelial related metabolic activities are significantly higher during the progressive pressure than at rest, in healthy and diabetic subjects. However, the relative contribution of the endothelial related metabolic activity is significantly higher during the progressive pressure than at rest, in the interval 200-400 s following the beginning of the pressure application, but only for healthy subjects. These results may improve knowledge on cutaneous microvascular responses to injuries or local pressures initiating diabetic complications

323

Evaluation of human hemispheric blood flow based on noninvasive carotid blood flow measurements using the range-gated Doppler technique  

International Nuclear Information System (INIS)

Common carotid blood flow (CCBF) was measured in 11 anesthetised patients without extracranial arterial disease (nine acute subarachnoid haemorrhages and two cases of head injury). The range-gated Doppler flowmeter with an adjustable range-gated time system and a double transducer probe was used to determine diameter, blood velocity, and blood flow of the common carotid artery. Values were, respectively, 5.9 +/- 1.1 mm, 13.8 +/- 6.1 cm . sec-1 and 387 +/- 183 cm3. min-1. Mean cerebral blood flow (rCBF) measurements were simultaneously made by 133Xe intra-arterial method, with a value of 22.28 +/- 5.96 ml . min-1 . 100 g. High correlation coefficient was found between CCBF and mean rCBF (r . 0.73, p less than 0.001). The range-gated Doppler flowmeter thus provides a non invasive and easily duplicated method for monitoring cerebral blood flow in anesthetized patients

324

Downhole ultrasonic transit-time flowmetering means and method  

Energy Technology Data Exchange (ETDEWEB)

A downhole ultrasonic flowmeter is provided which solves many of the prolems associated with spinner-type flowmeters and provides an improved flow measurement for production logging of oil wells. The sonde in the well logging system of the invention includes caliper means providing a signal corresponding to the diameter of a borehole traversing an earth formation. First and second transducers are controlled to transmit an ultrasonic pulse into fluid flowing in the borehole or to provide an electrical pulse in accordance with a received acoustical pulse from the fluid. A control network controls both transducers so that during one part of a measurement, the first transducer transmits an acoustic pulse into the fluid while the second transducer receives an acoustic pulse after it has passed through the fluid. In another part of the measurement, the second transducer is controlled to receive the acoustic pulse after it has passed through the fluid and provides a signal in accordance with the received acoustic pulse. A signal circuit connected to both transducers provides a signal correspoding to the travel times of the acoustic pulses for both parts of the measurement. A conventional well logging cable carries the control, diameter, and travel time signals to surface electronics which include processing apparatus to provide the control signal to the cable and which derives the flow rate of the fluid in accordance with the travel time and diameter signals. 2 figs.

Sims, J.C.; Supernaw, I.R.

1992-04-10

325

Use of a vortex flowmeter in the primary circuit of a research reactor  

International Nuclear Information System (INIS)

The paper describes the features of a flowmeter which operates on the principle of the Karman vortex street. Vortices are produced by a bluff body in a stream at a frequency which is proportional to the stream velocity. Because of its many advantages, such as the frequency output, the large measuring range and the high accuracy the vortex shedding flowmeter has aroused a considerable amount of interest. Experiments have been carried out with a commercial vortex flowmeter installed at the Primary Circuit of the Rossendorf Research Reactor. (author)

326

E.M.I Effects of Cathodic Protection on Electromagnetic Flowmeters  

Directory of Open Access Journals (Sweden)

Full Text Available Electromagnetic flowmeters are used to measure the speed of water flow in water distribution systems. Corrosion problem in metal pipelines can be solved by cathodic protection methods. This paper presents a research on corruptive effects of the cathodic protection system on electromagnetic flowmeter depending on its measuring principle. Experimental measurements are realized on the water distribution pipelines of the Izmir Municipality, Department of Water and Drainage Administration (IZSU in Turkey and measurement results are given. Experimental results proved that the values measured by the electromagnetic flowmeter (EMF are affected by cathodic protection system current. Comments on the measurement results are made and precautions to be taken are proposed.

Ozge Sahin

2007-01-01

327

Effects of prolonged surface pressure on the skin blood flowmotions in anaesthetized rats-an assessment by spectral analysis of laser Doppler flowmetry signals  

International Nuclear Information System (INIS)

The objective of this study is to assess the effect of prolonged surface compression on the skin blood flowmotion in rats using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. An external pressure of 13.3 kPa (100 mmHg) was applied to the trochanter area and the distal lateral tibia of Sprague-Dawley rats via two specifically designed pneumatic indentors. The loading duration was 6 hours/day for 4 consecutive days. Five frequency intervals were identified (0.01-0.04 Hz, 0.04-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. The results showed that (1) tissue compression following the above schedule induced significant decrease in the normalized amplitude in the frequency interval of 0.01-0.04 Hz both in the trochanter area (p < 0.001) and tibialis area (p = 0.023) (2) prolonged compression induced significant increase in the absolute amplitude (p = 0.004 for the trochanter area and p = 0.017 for the tibialis area) but significant decrease in the normalized amplitude (p = 0.023 for the trochanter area and p = 0.026 for the tibialis area) in the frequency interval of 0.15-0.4 Hz, and (3) at the tibialis area, the flowmotion amplitude (frequency irea, the flowmotion amplitude (frequency interval 0.15-0.4 Hz) measured prior to the daily tissue compression schedule was found to be significantly higher on day 4 than the measurements obtained on day 1. However, this finding was not observed at the trochanter area. Our results suggested that prolonged compression might induce endothelial damage and affect the endothelial related metabolic activities

328

Effects of prolonged surface pressure on the skin blood flowmotions in anaesthetized rats—an assessment by spectral analysis of laser Doppler flowmetry signals  

Science.gov (United States)

The objective of this study is to assess the effect of prolonged surface compression on the skin blood flowmotion in rats using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. An external pressure of 13.3 kPa (100 mmHg) was applied to the trochanter area and the distal lateral tibia of Sprague-Dawley rats via two specifically designed pneumatic indentors. The loading duration was 6 hours/day for 4 consecutive days. Five frequency intervals were identified (0.01-0.04 Hz, 0.04-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. The results showed that (1) tissue compression following the above schedule induced significant decrease in the normalized amplitude in the frequency interval of 0.01-0.04 Hz both in the trochanter area (p < 0.001) and tibialis area (p = 0.023), (2) prolonged compression induced significant increase in the absolute amplitude (p = 0.004 for the trochanter area and p = 0.017 for the tibialis area) but significant decrease in the normalized amplitude (p = 0.023 for the trochanter area and p = 0.026 for the tibialis area) in the frequency interval of 0.15-0.4 Hz, and (3) at the tibialis area, the flowmotion amplitude (frequency interval 0.15-0.4 Hz) measured prior to the daily tissue compression schedule was found to be significantly higher on day 4 than the measurements obtained on day 1. However, this finding was not observed at the trochanter area. Our results suggested that prolonged compression might induce endothelial damage and affect the endothelial related metabolic activities.

Li, Zengyong; Tam, Eric W. C.; Kwan, Maggie P. C.; Mak, Arthur F. T.; Lo, Samuel C. L.; Leung, Mason C. P.

2006-05-01

329

Laser Doppler Imaging para quantificação do fluxo sanguíneo de polpa digital em condições basais e após estímulo frio em pacientes com esclerose sistêmica Quantification of basal digital blood flow and after cold stimulus by laser doppler imaging in patients with systemic sclerosis  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Determinar o comportamento dinâmico do fluxo sanguíneo da microcirculação digital, antes e após dois estímulos frios (EF de diferentes intensidades, utilizando o método do Laser Doppler Imaging (LDI em pacientes com esclerose sistêmica (ES e controles saudáveis. MÉTODOS: Foram incluídos 14 pacientes com ES (51,2 ± 5,5 anos de idade e 12 controles saudáveis (44,8 ± 9,9 anos. Foram realizados dois protocolos alternativos de EF (submersão das mãos em água a 10 ºC ou 15 ºC, durante 1 minuto. O fluxo médio das quatro polpas digitais da mão esquerda (FPD foi mensurado com a utilização do LDI (Moor LDI-VR, em condições basais, nos períodos de 1, 4, 10, 25 e 40 minutos após EF. RESULTADOS: O fluxo basal foi significativamente menor em ambos os protocolos em pacientes com ES comparados a controles (312,9 ± 102,7 versus 465,4 ± 135,4 PU, P = 0,006, no protocolo a 15 ºC; 305,2 ± 121,0 versus 437,9 ± 119,8 PU, P = 0,01, no protocolo a 10 ºC. Nos controles houve declínio significativo do FPD após EF, em comparação aos valores basais apenas no tempo de um minuto após EF a 15 ºC (P = 0,001 e nos tempos de 1 e 25 minutos após EF a 10 ºC (P = 0,005; P = 0,001, respectivamente. Nos pacientes com ES, houve declínio significativo do FPD nos tempos de 1, 4 e 10 minutos após ambos EFs (P OBJECTIVES: The objective of this study was to investigate the dynamic behavior of the blood flow of the microvascular circulation of the fingertips before and after two cold stimuli (CS, using Laser Doppler Imaging with different intensities in patients with systemic sclerosis (SSc and in healthy individuals. PATIENTS AND METHODS: Fourteen SSc patients (51.2 ± 5.5 years with Raynaud's phenomenon and 12 healthy controls (44.8 ± 9.0 years were included in this study. Two CS protocols (submersion of the hands in water at 10 ºC or 15 ºC for 1 minute were performed on the same day. Mean fingertip blood flow (FBF of four digits of the left hand was measured using LDI (Moor LDI-VR, Moor Instruments at baseline and at 1, 4, 10, 25, and 40 minutes after CS. RESULTS: Baseline blood flow was significantly lower in both CS protocols in SSc patients when compared to controls (312.9 ± 102.7 vs 465.4 ± 135.4 PU, P = 0.006 at 15 ºC; 305.2 ± 121.0 vs 437.9 ± 119.8 PU; P = 0.01 at 10 ºC. In the control group, a significant decrease in FBF after CS, when compared to baseline, was observed 1 minute (P = 0.001 after CS at 15 ºC and at 1 (P = 0.005 and 25 minutes (P = 0.001 after CS at 10 ºC. In SSc patients, a significant decrease in FBF was observed in both CS protocols at 1, 4, and 10 minutes (P < 0.000; P = 0.002; P = 0.014, after CS at 15 ºC; P < 0.000; P = 0.004; P = 0.001, after CS at 10 ºC. CONCLUSIONS: Laser Doppler Imaging showed lower baseline fingertip perfusion and further reduction after CS in SSc patients compared to controls. Quantification of fingertip blood flow by LDI may be useful in the longitudinal monitoring of the disease status and therapeutic interventions in SSc.

Marcelo José Uchoa Corrêa

2010-04-01

330

Experience in designing and application of electromagnetic flowmeters for lead-bismuth eutectic alloy  

International Nuclear Information System (INIS)

Several flowmeters for the lead-bismuth coolants (the gradual wall method, the converter with tubular electrodes, the two stress method) are developed and realized. The calculation-theoretical analysis of operation of the proposed electromagnetic flowmeters is presented. The melt flow measurement error constitutes 2-5%. It is recommended to apply the described methods for measuring the flowrates of the metals, poorly wetting the pipeline wall (Pb, Pb-Bi, Ga, Hg)

331

The performance of electromagnetic flowmeters in a liquid metal two-phase flow  

International Nuclear Information System (INIS)

In order to investigate the characteristics of an electromagnetic flowmeter in a liquid metal two-phase flow, AC electromagnetic flowmeters were designed and manufactured. Two-phase flow experiments, encompassing bubbly to slug flow regimes, were realized with a water-air mixture and a liquid sodium-nitrogen mixture, respectively. The relation ?UTP=?USP/(1-?), between the flow induced electromotive force (e.m.f.) of a single-phase flow and that of a two-phase flow, was verified by the measured e.m.f.s. and the void fraction ? for a bubbly flow regime. Whereas there is no difference in the shape of the flow induced e.m.f. between single-phase and bubbly flow, the signal amplitude of the bubbly flow is greater than that of the single-phase flow under the same water or liquid sodium flow rate, since the real liquid velocity is higher than that of the single-phase flow. In the case of a slug flow, the phase and the amplitude of the flowmeter output changed drastically when a slug bubble passed through the flowmeter. Therefore, the electromagnetic flowmeter shows good potential as a useful device for identifying the flow regimes. The void fraction in a bubbly flow can be measured using two electromagnetic flowmeters. (author)

332

Flow Velocities After Carotid Artery Stenting: Impact of Stent Design. A Fluid Dynamics Study in a Carotid Artery Model with Laser Doppler Anemometry  

International Nuclear Information System (INIS)

Purpose. To study the influence of a newly developed membrane stent design on flow patterns in a physiologic carotid artery model. Methods. Three different stents were positioned in silicone models of the carotid artery: a stainless steel stent (Wall-stent), a nitinol stent (SelfX), and a nitinol stent with a semipermeable membrane (MembraX). To increase the contact area of the membrane with the vessel wall, another MembranX model was modified at the outflow tract. The membrane consists of a biocompatible silicone-polyurethane copolymer (Elast-Eon) with a pore size of 100 ?m. All stents were deployed across the bifurcation and the external carotid artery origin. Flow velocity measurements were performed with laser Doppler anemometry (LDA), using pulsatile flow conditions (Re = 220; flow 0.39 l/min; flow rate ratio ICA:ECA = 70:30) in hemodynamically relevant cross-sections. The hemodynamic changes were analyzed by comparing velocity fluctuations of corresponding flow profiles. Results. The flow rate ratio ICA:ECA shifted significantly from 70/30 to 73.9/26.1 in the MembraX and remained nearly unchanged in the SelfX and Wallstent. There were no changes in the flow patterns at the inflow proximal to the stents. In the stent no relevant changes were found in the SelfX. In the Wallstent the separation zone shifted from the orifice of the ICA to the distal end of the stent. Four millimeters distal to the SelfX and the Wallstent the flow profile returned to normal. In the flow profile returned to normal. In the MembraX an increase in the central slipstreams was found with creation of a flow separation distal to the stent. With a modification of the membrane this flow separation vanished. In the ECA flow disturbances were seen at the inner wall distal to the stent struts in the SelfX and the Wallstent. With the MembraX a calming of flow could be observed in the ECA with a slight loss of flow volume. Conclusions. Stent placement across the carotid artery bifurcation induces alterations of the physiologic flow behavior. Depending on the stent design the flow alterations are located in different regions. All the stents tested were suitable for the carotid bifurcation. The MembraX prototype has shown promising hemodynamic properties ex vivo

333

Electromagnetic Borehole Flowmeter Testing in R-Area  

International Nuclear Information System (INIS)

Six constant-rate, multiple-well aquifer tests were recently conducted in R-area to provide site-specific in situ hydraulic parameters for assessing groundwater flow and contaminant transport models of R-Reactor Seepage Basins (RRSB) plume migration and RRSB remedial alternatives. The pumping tests were performed in the Upper Three Runs and Gordon aquifers between December 1999 and February 2000. The tests provide reliable estimates of horizontal conductivity averaged over aquifer thickness, and a relatively large horizontal zone of influence. To complement these results, Electromagnetic Borehole Flowmeter (EBF) testing was subsequently performed to determine the vertical variation of horizontal conductivity for RPC-2PR, RPC-3PW, RPT-2PW, RPT-3PW, RPT-4PW and RPT-30PZ. The EBF data generally indicate significant aquifer heterogeneity over the tested screen intervals (Figures 14, 16-18, 20, 22, 24, 26 and 27-31). The vertical variation of groundwater flow in or out of the well screen under ambient conditions was also measured (Figures 13, 15, 19, 21, 23 and 25). These data have implications for contaminant monitoring

334

Development of a Digital and Battery-Free Smart Flowmeter  

Directory of Open Access Journals (Sweden)

Full Text Available To effectively manage and save energy and natural resources, the measurement and monitoring of gas/fluid flows play extremely important roles. The objective of this study was to incorporate an efficient power generation and a power management system for a commercial water flow meter thus eliminating the usage of batteries. Three major technologies have made this possible: a low power consumption metering unit, a cog-resistance-free generator with high efficiency; and an effective methodology to extract/store energy. In this system, a new attempt and simple approach was developed to successfully extract a portion of the kinetic energy from the fluid/air, store it in a capacitor and used it efficiently. The resistance to the flow was negligible because of the very low power consumption as well as the application of the coreless generator technology. Feasibility was demonstrated through repeated experiments: for air flowing in an 11 mm diameter pipe, 18 s of energy harvesting at 10 revolution-per-second (RPS turbine speeds generated enough power for the flowmeter to operate for 720 s with a flowrate of 20 RPS, without battery or any external power. The pipeline monitoring in remote areas such as deep sea oil drilling; geothermal power plants and even nuclear power plants could benefit greatly from this self-power metering system design.

Wang Song Hao

2014-06-01

335

A Study on Error Characteristics of Electromagnetic Flowmeter at various velocities  

Energy Technology Data Exchange (ETDEWEB)

The large size electromagnetic flow-meter was tested to investigate the variation of its error characteristics in the range of low velocity under 0.6m/s using flowmeter calibration system. For the two case of valve opening (100%, 50%), these tests were undertaken three times each for twelve velocity condition from 0.05m/s to 0.6m/s with increment of 0.05m/s. It is shown that the minimum velocity should be higher than 0.25m/s for {psi}300mm and 0.3m/s for {psi} 800mm to keep manufacturer's({+-}0.4% of rate). Measurement deviation of flowmeter for {psi}400mm and {psi} 600mm was out of expected deviation range suggested by manufacturer, however, its tendency was kept similar to manufacturer's suggestion. In conclusion, error characteristic of electromagnetic flowmeter wasn't changed proportion to its size but depended on the fact that if the flow through the flowmeter is fully developed or not.

Lee, Dong Keun [Korea Institute of Water and Enviroment, Daejeon (Korea, Republic of); Park, Jong Ho [Chungnam National Univ., Daejeon (Korea, Republic of)

2007-07-01

336

A Study on Error Characteristics of Electromagnetic Flowmeter at various velocities  

International Nuclear Information System (INIS)

The large size electromagnetic flow-meter was tested to investigate the variation of its error characteristics in the range of low velocity under 0.6m/s using flowmeter calibration system. For the two case of valve opening (100%, 50%), these tests were undertaken three times each for twelve velocity condition from 0.05m/s to 0.6m/s with increment of 0.05m/s. It is shown that the minimum velocity should be higher than 0.25m/s for ?300mm and 0.3m/s for ? 800mm to keep manufacturer's(±0.4% of rate). Measurement deviation of flowmeter for ?400mm and ? 600mm was out of expected deviation range suggested by manufacturer, however, its tendency was kept similar to manufacturer's suggestion. In conclusion, error characteristic of electromagnetic flowmeter wasn't changed proportion to its size but depended on the fact that if the flow through the flowmeter is fully developed or not

337

Borehole Flowmeter Logging for the Accurate Design and Analysis of Tracer Tests.  

Science.gov (United States)

Tracer tests often give ambiguous interpretations that may be due to the erroneous location of sampling points and/or the lack of flow rate measurements through the sampler. To obtain more reliable tracer test results, we propose a methodology that optimizes the design and analysis of tracer tests in a cross borehole mode by using vertical borehole flow rate measurements. Experiments using this approach, herein defined as the Bh-flow tracer test, have been performed by implementing three sequential steps: (1) single-hole flowmeter test, (2) cross-hole flowmeter test, and (3) tracer test. At the experimental site, core logging, pumping tests, and static water-level measurements were previously carried out to determine stratigraphy, fracture characteristics, and bulk hydraulic conductivity. Single-hole flowmeter testing makes it possible to detect the presence of vertical flows as well as inflow and outflow zones, whereas cross-hole flowmeter testing detects the presence of connections along sets of flow conduits or discontinuities intercepted by boreholes. Finally, the specific pathways and rates of groundwater flow through selected flowpaths are determined by tracer testing. We conclude that the combined use of single and cross-borehole flowmeter tests is fundamental to the formulation of the tracer test strategy and interpretation of the tracer test results. PMID:25417730

Basiricò, Stefano; Crosta, Giovanni B; Frattini, Paolo; Villa, Alberto; Godio, Alberto

2014-11-21

338

Accuracy improvement of ultrasonic flowmeter for nuclear power station. 2nd report. Influence of two-dimensional upstream pipe condition, flowconditioners and remounting of transducers  

International Nuclear Information System (INIS)

An ultrasonic flowmeter has a possibility of replacing flow nozzle and orifice meter as a main feedwater flowmeter in nuclear power stations. This paper describes the examination about the influence of the two-dimensional upstream condition, flowconditioner and remounting of transducers using a cramp-on type ultrasonic flowmeter. (author)

339

Laser Doppler Imaging para quantificação do fluxo sanguíneo de polpa digital em condições basais e após estímulo frio em pacientes com esclerose sistêmica / Quantification of basal digital blood flow and after cold stimulus by laser doppler imaging in patients with systemic sclerosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese OBJETIVO: Determinar o comportamento dinâmico do fluxo sanguíneo da microcirculação digital, antes e após dois estímulos frios (EF) de diferentes intensidades, utilizando o método do Laser Doppler Imaging (LDI) em pacientes com esclerose sistêmica (ES) e controles saudáveis. MÉTODOS: Foram incluídos [...] 14 pacientes com ES (51,2 ± 5,5 anos de idade) e 12 controles saudáveis (44,8 ± 9,9 anos). Foram realizados dois protocolos alternativos de EF (submersão das mãos em água a 10 ºC ou 15 ºC, durante 1 minuto). O fluxo médio das quatro polpas digitais da mão esquerda (FPD) foi mensurado com a utilização do LDI (Moor LDI-VR), em condições basais, nos períodos de 1, 4, 10, 25 e 40 minutos após EF. RESULTADOS: O fluxo basal foi significativamente menor em ambos os protocolos em pacientes com ES comparados a controles (312,9 ± 102,7 versus 465,4 ± 135,4 PU, P = 0,006, no protocolo a 15 ºC; 305,2 ± 121,0 versus 437,9 ± 119,8 PU, P = 0,01, no protocolo a 10 ºC). Nos controles houve declínio significativo do FPD após EF, em comparação aos valores basais apenas no tempo de um minuto após EF a 15 ºC (P = 0,001) e nos tempos de 1 e 25 minutos após EF a 10 ºC (P = 0,005; P = 0,001, respectivamente). Nos pacientes com ES, houve declínio significativo do FPD nos tempos de 1, 4 e 10 minutos após ambos EFs (P Abstract in english OBJECTIVES: The objective of this study was to investigate the dynamic behavior of the blood flow of the microvascular circulation of the fingertips before and after two cold stimuli (CS), using Laser Doppler Imaging with different intensities in patients with systemic sclerosis (SSc) and in healthy [...] individuals. PATIENTS AND METHODS: Fourteen SSc patients (51.2 ± 5.5 years) with Raynaud's phenomenon and 12 healthy controls (44.8 ± 9.0 years) were included in this study. Two CS protocols (submersion of the hands in water at 10 ºC or 15 ºC for 1 minute) were performed on the same day. Mean fingertip blood flow (FBF) of four digits of the left hand was measured using LDI (Moor LDI-VR, Moor Instruments) at baseline and at 1, 4, 10, 25, and 40 minutes after CS. RESULTS: Baseline blood flow was significantly lower in both CS protocols in SSc patients when compared to controls (312.9 ± 102.7 vs 465.4 ± 135.4 PU, P = 0.006 at 15 ºC; 305.2 ± 121.0 vs 437.9 ± 119.8 PU; P = 0.01 at 10 ºC). In the control group, a significant decrease in FBF after CS, when compared to baseline, was observed 1 minute (P = 0.001) after CS at 15 ºC and at 1 (P = 0.005) and 25 minutes (P = 0.001) after CS at 10 ºC. In SSc patients, a significant decrease in FBF was observed in both CS protocols at 1, 4, and 10 minutes (P

Marcelo José Uchoa, Corrêa; Sandro F, Perazzio; Luís Eduardo Coelho, Andrade; Cristiane, Kayser.

2010-04-01

340

Error Characteristics of Clamp-on Ultrasonic Flowmeters Depending on Location of Sensors and Downstream Straight Run of Bent Pipe  

International Nuclear Information System (INIS)

Flowmeters that measure the amount of fluid passing through conduits must kept accurate by comparison and the periodic calibration. The reference meters used are clamp-on meters that mount sensors on the outer wall of the pipe. They are called 1-path, 2-path or 4-path flowmeters depending on the number of sensors. We selected a flowmeter mainly used for K-water as test a flowmeter. We carried out experiments to find the intrinsic error of the flowmeter and errors in the downstream of a double bent pipe. The results show that there are the sensor locations that meet the tolerance. We suggested the angle of the sensor, the straight run from the downstream of the bent pipe and the number of sensors. So it is possible to improve the water treatment process and increase the accounted water rate by upgraded flow measurement technology

341

Coupled Lagrangian and Eulerian simulation of bubbly flows in vertical pipes: validation with experimental data using multi-sensor conductivity probes and laser doppler anemometry  

International Nuclear Information System (INIS)

Understanding the dynamics of multiphase systems is an issue of particular interest in the field of Computer Fluid Dynamics (CFD) applied to Nuclear Reactor Safety. A better knowledge of the forces that act on the bubbles moving in a continuous turbulent random fluid field is of importance for a complete description of the bubble's motion and to obtain for instance the radial and axial void fraction distribution inside the reactor channels. Experiments specifically designed to understand the forces that act on the bubbles are a tool necessary to validate the models implemented inside the CFD codes. With this goal in mind, an upward isothermal co-current air-water flow in a vertical pipe (52 mm inner diameter) has been experimental investigated. Local measurements of void fraction, interfacial area concentration (IAC), interfacial velocity and Sauter mean diameter were measured using a four sensor conductivity probe. Liquid velocity and turbulence intensity were also measured using Laser Doppler Anemometry (LDA). Different air-water flow configurations were investigated for a liquid flow rate ranged from 0.491 m/s to 3 m/s and a void fraction up to 25 pc. For each two-phase flow configuration twenty five radial position and three axial locations were measured by the conductivity probe methodology, and several radial profiles were also measured with LDA at different axial positions. Numerical simulations of these experiments for bubbly flow conditions were performed by bubbly flow conditions were performed by coupling a Lagrangian code that tracks the 3D motion of the individual bubbles in cylindrical coordinates (r, ?, Z) inside the fluid field under the action of the following forces: buoyancy, drag, lift, and wall lubrication. Also we incorporate a 3D stochastic differential equation model to account for the random motion of the individual bubbles in the turbulent velocity field of the carrier liquid. This type of models denoted as continuous random walk models are used to predict the turbulent diffusion of the bubbles in the fluctuating velocity field of the carrier fluid. Also we have considered the deformation that suffers the bubbles when they touch the walls of the pipe and are compressed until they rebound. The velocity and turbulence fields of the liquid phase were computed by solving the time dependent mass, energy, and momentum conservation equations in its Reynolds Averaged Transport Equation form (RANS). The turbulent kinetic energy k, and the dissipation rate ? transport equations were simultaneously solved by using the k, epsilon model or the renormalized group model (RNG) model in a (r,z) grid by the finite volume method using the SIMPLER algorithm. Both Lagrangian and Eulerian calculations were performed in parallel because when integrating the 3D stochastic differential equations that take into account the motion of the bubbles in the fluid field we must consider the effect of the turbulence on the bubble's motion. To do this we must know the turbulence field that feels the bubble at each position along the path trajectory. Good predictions were obtained for the bubbles trajectories and the void fraction distribution in the channels when we consider that the lift radial force depends on the bubble's size and the bubbles are distorted, expressing this deformation in terms of the Eoetvos number. (authors)

342

Note: Ultrasonic gas flowmeter based on optimized time-of-flight algorithms  

International Nuclear Information System (INIS)

A new digital signal processor based single path ultrasonic gas flowmeter is designed, constructed, and experimentally tested. To achieve high accuracy measurements, an optimized ultrasound driven method of incorporation of the amplitude modulation and the phase modulation of the transmit-receive technique is used to stimulate the transmitter. Based on the regularities among the received envelope zero-crossings, different received signal's signal-to-noise ratio situations are discriminated and optional time-of-flight algorithms are applied to take flow rate calculations. Experimental results from the dry calibration indicate that the designed flowmeter prototype can meet the zero-flow verification test requirements of the American Gas Association Report No. 9. Furthermore, the results derived from the flow calibration prove that the proposed flowmeter prototype can measure flow rate accurately in the practical experiments, and the nominal accuracies after FWME adjustment are lower than 0.8% throughout the calibration range.

343

A test circuit for calibration of liquid and supercritical helium flowmeters  

International Nuclear Information System (INIS)

This chapter investigates the behavior of flow transducers in different pressure conditions using a closed loop in which each component can withstand pressures up to 3 MPa. The test circuit consists of a variable speed superconducting motor, a centrifugal pump, a multi-function valve and a test section. It includes a commercial turbine transducer used as a reference standard flowmeter. An absolute calibration system, built for calibrating the turbine flowmeter standard in liquid helium at 0.1 MPa, is described. It is concluded that although the described test-circuit has been designed primarily for testing anemometric-type transducers, it can be used to calibrate other types of small-size LHe flowmeters also, provided they are suitable for complete immersion in liquid helium

344

Flow measurement in bubbly and slug flow regimes using the electromagnetic flowmeter developed  

International Nuclear Information System (INIS)

In order to investigate the characteristics of electromagnetic flowmeter in two-phase flow, an AC electromagnetic flowmeter was designed and manufactured. In various flow conditions, the signals and noises from the flowmeter were obtained and analyzed by comparison with the observed flow patterns with a high speed CCD camera. The experiment with the void simulators in which rod shaped non-conducting material was used was carried out to investigate the effect of the bubble position and the void fraction on the flowmeter. Based on the results from the void simulator, two-phase flow experiments encompassed from bubbly to slug flow regime were conducted. The simple relation ?UTP= ?USP/(1-?) was verified with measurements of the potential difference and the void fraction. Due to the lack of homogeneity in a real two-phase flow, the discrepancy between the relation and the present measurement was slightly increased with void fraction and also liquid volumetric flux jf. Whereas there is no difference in the shape of the raw signal between single-phase flow and bubbly flow, the signal amplitude for bubbly flow is higher than that for single-phase flow at the same water flow rate, since the passage area of the water flow is reduced. In the case of slug flow, the phase and the amplitude of the flowmeter output show dramatically the flow characteristics around each slug bubble and the position of a slug bubble itself. Therefore, the electromagubble itself. Therefore, the electromagnetic flowmeter shows a good possibility of being useful for identifying the flow regimes

345

Preliminary Modeling of Permanent Magnet Probe Flowmeter for Voltage Signal Estimation  

Energy Technology Data Exchange (ETDEWEB)

An experimental study on performance analysis of the flowmeter has been performed. The study shows that sodium flow rate is linearly proportional to the induced voltage signal from the flowmeter under the turbulent flow condition. The experimental results support its availability in the PDRC system. But, the flowmeter should be able to measure sodium flow at low Reynolds number as well. That is because the PDRC system uses sodium natural convection for its operation. Thus, calibration of the flowmeter should be done at very low sodium flow rates. However, Von Weissenfluh et al. showed that the relationship between flow rate and measured voltage signal from the flowmeter may become non-linear at very low flow rates. The nonlinearity restricts the utilization of level sensor which provide reference flow rate in the calibration experiment. The primary objective of this study is to predict the sodium flow rate range where the induced voltage signals are linearly proportional to flow rates by estimating the induced voltage signals against sodium flow rates for a wide range of flows numerically. A commercial code FLUENT is adopted for the analysis of flow field. And MAXWELL which is an electromagnetic analysis software using a finite volume method has been used to analyze the magnetic field generated by permanent magnet of the flowmeter. The induced voltage signals have been estimated by coupling the sodium flow field and the magnetic field using FLUENT MHD module. It is expected that the PMPF voltage signals are linearly proportional to flow rates range of 0.0059 to 1.96 lps. This suggests that simple calibration technique using the linearity between flow rate and the voltage signal can be adopted in calibration of the PMPF.

Jeong, Uiju; Kim, Sung Joong [Hanyang Univ., Seoul (Korea, Republic of); Jeong, Ji Young; Kim, Tae Joon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

346

Preliminary Modeling of Permanent Magnet Probe Flowmeter for Voltage Signal Estimation  

International Nuclear Information System (INIS)

An experimental study on performance analysis of the flowmeter has been performed. The study shows that sodium flow rate is linearly proportional to the induced voltage signal from the flowmeter under the turbulent flow condition. The experimental results support its availability in the PDRC system. But, the flowmeter should be able to measure sodium flow at low Reynolds number as well. That is because the PDRC system uses sodium natural convection for its operation. Thus, calibration of the flowmeter should be done at very low sodium flow rates. However, Von Weissenfluh et al. showed that the relationship between flow rate and measured voltage signal from the flowmeter may become non-linear at very low flow rates. The nonlinearity restricts the utilization of level sensor which provide reference flow rate in the calibration experiment. The primary objective of this study is to predict the sodium flow rate range where the induced voltage signals are linearly proportional to flow rates by estimating the induced voltage signals against sodium flow rates for a wide range of flows numerically. A commercial code FLUENT is adopted for the analysis of flow field. And MAXWELL which is an electromagnetic analysis software using a finite volume method has been used to analyze the magnetic field generated by permanent magnet of the flowmeter. The induced voltage signals have been estimated by coupling the sodium flow field and the magnetic field using FLUENT MHD module. It is expected that the PMPF voltage signals are linearly proportional to flow rates range of 0.0059 to 1.96 lps. This suggests that simple calibration technique using the linearity between flow rate and the voltage signal can be adopted in calibration of the PMPF

347

Permeability profiles in granular aquifers using flowmeters in direct-push wells.  

Science.gov (United States)

Numerical hydrogeological models should ideally be based on the spatial distribution of hydraulic conductivity (K), a property rarely defined on the basis of sufficient data due to the lack of efficient characterization methods. Electromagnetic borehole flowmeter measurements during pumping in uncased wells can effectively provide a continuous vertical distribution of K in consolidated rocks. However, relatively few studies have used the flowmeter in screened wells penetrating unconsolidated aquifers, and tests conducted in gravel-packed wells have shown that flowmeter data may yield misleading results. This paper describes the practical application of flowmeter profiles in direct-push wells to measure K and delineate hydrofacies in heterogeneous unconsolidated aquifers having low-to-moderate K (10(-6) to 10(-4) m/s). The effect of direct-push well installation on K measurements in unconsolidated deposits is first assessed based on the previous work indicating that such installations minimize disturbance to the aquifer fabric. The installation and development of long-screen wells are then used in a case study validating K profiles from flowmeter tests at high-resolution intervals (15 cm) with K profiles derived from multilevel slug tests between packers at identical intervals. For 119 intervals tested in five different wells, the difference in log K values obtained from the two methods is consistently below 10%. Finally, a graphical approach to the interpretation of flowmeter profiles is proposed to delineate intervals corresponding to distinct hydrofacies, thus providing a method whereby both the scale and magnitude of K contrasts in heterogeneous unconsolidated aquifers may be represented. PMID:20880040

Paradis, Daniel; Lefebvre, René; Morin, Roger H; Gloaguen, Erwan

2011-01-01

348

Resonant two photon spectrum in a doppler broadened line  

International Nuclear Information System (INIS)

The line shape in the resonant and near resonant two photon absorption spectra in the Na 3s1sub(/)2-3P1sub(/)2-5s1sub(/)2 transition was investigated using two single frequency dye lasers. Two types of Doppler-free peaks for resonant case and Doppler-broadened normal two photon peaks were observed. They were different in the width, selection rule and the laser power dependence in agreement with theory. (orig.)

349

A novel time varying signal processing method for Coriolis mass flowmeter.  

Science.gov (United States)

The precision of frequency tracking method and phase difference calculation method affects the measurement precision of Coriolis Mass Flowmeter directly. To improve the accuracy of the mass flowrate, a novel signal processing method for Coriolis Mass Flowmeter is proposed for this time varying signal, which is comprised of a modified adaptive lattice notch filter and a revised sliding recursive discrete-time Fourier transform algorithm. The method cannot only track the change of frequency continuously, but also ensure the calculation accuracy when measuring phase difference. The computational load of the proposed method is small with higher accuracy. Simulation and experiment results show that the proposed method is effective. PMID:24985861

Shen, Ting-Ao; Tu, Ya-Qing; Zhang, Hai-Tao

2014-06-01

350

High-pressure gas facilitates calibration of turbine flowmeters for liquid hydrogen  

Science.gov (United States)

Nitrogen gas at a pressure of 60 atmospheres and ambient temperature facilitates the calibration of turbine flowmeters used for monitoring the flow of liquid hydrogen in cryogenic systems. Full-scale calibration factors can be obtained to an accuracy of 0.4 percent.

Krause, L. N.; Szaniszlo, A. J.

1968-01-01

351

Development, computer simulation and performance testing in sodium of an eddy current flowmeter  

International Nuclear Information System (INIS)

Sodium is used as a coolant in Liquid Metal Fast Breeder Reactor (LMFBR). Sodium flow measurement is of prime importance both from the operational and safety aspects of a fast reactor. Various types of flowmeters namely permanent magnet, saddle type and eddy current flowmeters are used in FBRs. From the safety point of view flow through the core should be assured under all operating conditions. This requires a flow sensor which can withstand the high temperature sodium environment and can meet the dimensional constraints and be amenable to maintenance. Eddy current flowmeter (ECFM) is one such device which meets these requirements. It is meant for measuring flow in PFBR primary pump and also at the outlets of the fuel sub-assemblies to detect flow blockage. A simulation model of ECFM was made and output of ECFM was predicted for various flowrates and temperatures. The simulation model was validated by testing in a sodium loop. This paper deals with the design, simulation and tests conducted in sodium for the eddy current flowmeter for use in the Prototype Fast Breeder Reactor (PFBR).

352

Development, computer simulation and performance testing in sodium of an eddy current flowmeter  

Energy Technology Data Exchange (ETDEWEB)

Sodium is used as a coolant in Liquid Metal Fast Breeder Reactor (LMFBR). Sodium flow measurement is of prime importance both from the operational and safety aspects of a fast reactor. Various types of flowmeters namely permanent magnet, saddle type and eddy current flowmeters are used in FBRs. From the safety point of view flow through the core should be assured under all operating conditions. This requires a flow sensor which can withstand the high temperature sodium environment and can meet the dimensional constraints and be amenable to maintenance. Eddy current flowmeter (ECFM) is one such device which meets these requirements. It is meant for measuring flow in PFBR primary pump and also at the outlets of the fuel sub-assemblies to detect flow blockage. A simulation model of ECFM was made and output of ECFM was predicted for various flowrates and temperatures. The simulation model was validated by testing in a sodium loop. This paper deals with the design, simulation and tests conducted in sodium for the eddy current flowmeter for use in the Prototype Fast Breeder Reactor (PFBR).

Sharma, Prashant, E-mail: pacific@igcar.gov.i [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Suresh Kumar, S.; Nashine, B.K.; Veerasamy, R.; Krishnakumar, B.; Kalyanasundaram, P.; Vaidyanathan, G. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2010-03-15

353

Influence on Accuracy of Flow Rate under Position of Orifice Flowmeter using Numerical Analysis  

International Nuclear Information System (INIS)

The calculation of fluid flow rate by measuring the pressure difference across a pipe restriction is perhaps the most commonly used flow measurement technique in industrial application including the nuclear field. Because of the availability for all pipe sizes and the cost effectiveness for measuring flow rate in larger pipes (over 6' diameter), the orifice flowmeter is widely used in the nuclear power plant. These kinds of orifice flowmeter shall be installed in the pipeline at a position such that the flow conditions immediately upstream sufficiently approach those of a fully developed profile and are free from swirl. The industrial code such as ASME PTC 19.5) gives guidelines for installation requirements of these kinds of flowmeter. However, compared with the 1972 edition of ASME PTC 19.5, the 2004 edition is more strict in the standards for recommended straight lengths of orifice flowmeter. For example, in the 1972 edition, 16D (16 times the diameter of the pipe) is needed to make a fully developed upstream flow for the case of two or more bends in the same plane, but 36D is suggested in the 2004 edition. However, it's not always easy to conclude which of edition is correct and is suitable for applied system. In the present study, the flow characteristics of the orifice in the auxiliary feedwater system (AFWS) were investigated by changing the upstream and downstream length of the orifice, and each edition of ASME PTC 19.5 was compared5 was compared

354

Effects of free convection and friction on heat-pulse flowmeter measurement  

Science.gov (United States)

SummaryHeat-pulse flowmeter can be used to measure low flow velocities in a borehole; however, bias in the results due to measurement error is often encountered. A carefully designed water circulation system was established in the laboratory to evaluate the accuracy and precision of flow velocity measured by heat-pulse flowmeter in various conditions. Test results indicated that the coefficient of variation for repeated measurements, ranging from 0.4% to 5.8%, tends to increase with flow velocity. The measurement error increases from 4.6% to 94.4% as the average flow velocity decreases from 1.37 cm/s to 0.18 cm/s. We found that the error resulted primarily from free convection and frictional loss. Free convection plays an important role in heat transport at low flow velocities. Frictional effect varies with the position of measurement and geometric shape of the inlet and flow-through cell of the flowmeter. Based on the laboratory test data, a calibration equation for the measured flow velocity was derived by the least-squares regression analysis. When the flowmeter is used with a diverter, the range of measured flow velocity can be extended, but the measurement error and the coefficient of variation due to friction increase significantly. At higher velocities under turbulent flow conditions, the measurement error is greater than 100%. Our laboratory experimental results suggested that, to avoid a large error, the heat-pulse flowmeter measurement is better conducted in laminar flow and the effect of free convection should be eliminated at any flow velocities. Field measurement of the vertical flow velocity using the heat-pulse flowmeter was tested in a monitoring well. The calibration of measured velocities not only improved the contrast in hydraulic conductivity between permeable and less permeable layers, but also corrected the inconsistency between the pumping rate and the measured flow rate. We identified two highly permeable sections where the horizontal hydraulic conductivity is 3.7-6.4 times of the equivalent hydraulic conductivity obtained from the pumping test. The field test results indicated that, with a proper calibration, the flowmeter measurement is capable of characterizing the vertical distribution of preferential flow or hydraulic conductivity.

Lee, Tsai-Ping; Chia, Yeeping; Chen, Jiun-Szu; Chen, Hongey; Liu, Chen-Wuing

2012-03-01

355

Development, Calibration and Deployment of an Electromagnetic Flowmeter for Cross-Hole Hydrogeologic Experiments  

Science.gov (United States)

We developed an autonomous electromagnetic flowmeter as part of a cross-hole hydrogeologic experiment using subseafloor borehole observatories (CORKs) that penetrate into the volcanic ocean crust. The cylindrical flowmeter is adapted from a conventional industrial tool and hardened for use at water depths up to 6000 m. In addition, the electronics were modified with a new power controller, and a data logger and communication board was added to enable data storage and long-term, autonomous use for up to eight years. The flowmeter generates a magnetic field and measures a voltage gradient that is created across the orifice as water moves through it. This kind of tool is ideally suited for use in the deep sea, particularly for measuring hydrothermal fluids emanating from the ocean crust, because it requires no moving parts, places no obstructions along the flow path, gives total flow volume as well as instantaneous flow rate, and is highly accurate across a large dynamic range, including bi-directional flow. This flowmeter was deployed on a CORK wellhead using an adapter and ring clamp system located above a 4-inch ball valve. The ball valve can be opened to permit flow (from an overpressured formation) out of the CORK and into the overlying ocean. A polyvinyl chloride "chimney" positioned vertically above the flowmeter is instrumented with autonomous temperature loggers to permit an additional estimate of fluid flow rates with time, based on heat loss during fluid ascent, and to facilitate fluid sampling. Calibration of the new flowmeter was completed in two stages: tank testing using a pump at flow rates of 0.5 to 1.2 L/s, and by lowering the flowmeter on a wireline at sea at rates equivalent to 0.5 to 5.2 L/s. A cross plot of apparent and reference flow rates obtained during calibration indicates a highly linear instrument response. Comparison of instantaneous (once per minute) and integrated (total flow) data collected during calibration indicates good agreement, although the instantaneous data tended to be noisy because of irregularity of flow (turbulence). The flowmeter was deployed in Summer 2011 on a CORK installed in IODP Hole 1362B, on the eastern flank of the Juan de Fuca ridge. Once the flowmeter was attached to the wellhead, the underlying ball valve was opened, which allowed overpressured fluids from the permeable ocean crust to flow upward and out of the seafloor at 5 to 10 L/s (estimated rate). Changes in formation fluid pressure resulting from this flow are being monitored in four additional CORKs located 310 to 2320 m away from Hole 1362B, which will allow large-scale, directional assessment of formation properties. The flowmeter is recording data for instantaneous flow rate and total flow once per hour, and will be recovered to permit collection and analysis of experimental data during a servicing visit in Summer 2012.

Slovacek, A. E.; Fisher, A. T.; Kirkwood, W.; Wheat, C. G.; Maughan, T.; Gomes, K.

2011-12-01

356

Cosmology with Doppler Lensing  

CERN Document Server

Doppler lensing is the apparent change in object size and magnitude due to peculiar velocities. Objects falling into an overdensity appear larger on its near side, and smaller on its far side, than typical objects at the same redshifts. This effect dominates over the usual gravitational lensing magnification at low redshift. Doppler lensing is a promising new probe of cosmology, and we explore in detail how to utilize the effect with forthcoming surveys. We present cosmological simulations of the Doppler and gravitational lensing effects based on the Millennium simulation. We show that Doppler lensing can be detected around stacked voids or unvirialised over-densities. New power spectra and correlation functions are proposed which are designed to be sensitive to Doppler lensing. We consider the impact of gravitational lensing and intrinsic size correlations on these quantities. We compute the correlation functions and forecast the errors for realistic forthcoming surveys, providing predictions for constraints...

Bacon, David J; Clarkson, Chris; Bolejko, Krzysztof; Maartens, Roy

2014-01-01

357

An evaluation by laser Doppler anemometry of the correction algorithm based on Kaimal co-spectra for high frequency losses of EC flux measurements of CH4 and N2O  

International Nuclear Information System (INIS)

Eddy covariance (EC) technique is often used to determine greenhouse gas exchange at the earth's surface. In general, the instruments involved have a limited high frequency response which reduces the ability to detect the contribution to the flux of small eddies and in addition sensor separation gives high frequency losses. These missing contributions cause an EC flux underestimation which increases for higher values of the stability parameter z/L. Corrections can be performed based on the (empirical) Kaimal co-spectra; however, these were derived using instruments with a limited frequency response. In this study, the validity of the Kaimal spectrum during stable atmospheric conditions is assessed using laser Doppler anemometry (LDA) measurements of the vertical wind velocity at 1 m height during several stable nights at Cabauw in the Netherlands. LDA provides a means to determine the entire turbulent energy spectrum, i.e., from the production scale down to the dissipation scale. Since the measured spectra are found to be in good agreement with the Kaimal spectra, we assume that the Kaimal co-spectra are valid as well. Next, the effect of high frequency correction based on Kaimal co-spectra is assessed using 1 month of EC flux data of CH4 and N2O measured by quantum cascade laser (QCL) spectrometry at Reeuwijk in the Netherlands. After correction, the cumulative emissions increased about 15% for both gases. This underlines the importance of correcting for high frequen importance of correcting for high frequency losses.

358

An evaluation by laser Doppler anemometry of the correction algorithm based on Kaimal co-spectra for high frequency losses of EC flux measurements of CH4 and N2O  

Energy Technology Data Exchange (ETDEWEB)

Eddy covariance (EC) technique is often used to determine greenhouse gas exchange at the earth's surface. In general, the instruments involved have a limited high frequency response which reduces the ability to detect the contribution to the flux of small eddies and in addition sensor separation gives high frequency losses. These missing contributions cause an EC flux underestimation which increases for higher values of the stability parameter z/L. Corrections can be performed based on the (empirical) Kaimal co-spectra; however, these were derived using instruments with a limited frequency response. In this study, the validity of the Kaimal spectrum during stable atmospheric conditions is assessed using laser Doppler anemometry (LDA) measurements of the vertical wind velocity at 1 m height during several stable nights at Cabauw in the Netherlands. LDA provides a means to determine the entire turbulent energy spectrum, i.e., from the production scale down to the dissipation scale. Since the measured spectra are found to be in good agreement with the Kaimal spectra, we assume that the Kaimal co-spectra are valid as well. Next, the effect of high frequency correction based on Kaimal co-spectra is assessed using 1 month of EC flux data of CH4 and N2O measured by quantum cascade laser (QCL) spectrometry at Reeuwijk in the Netherlands. After correction, the cumulative emissions increased about 15% for both gases. This underlines the importance of correcting for high frequency losses.

Kroon, P.S.; Hensen, A. [Energy research Centre of the Netherlands ECN, Department of Air Quality and Climate Change, Westerduinweg 3, 1755 LE Petten (Netherlands); Schuitmaker, A.; Jonker, H.J.J.; Tummers, M.J. [Delft University of Technology, Department of Multi-Scale Physics, Research Group Clouds, Climate and Air Quality, Lorentzweg 1, 2628 CJ Delft (Netherlands); Bosveld, F.C. [Royal Dutch Meteorological Institute KNMI, Section Atmospheric Research, Wilhelminalaan 10, 3732 GK De Bilt (Netherlands)

2010-08-15

359

High-Energy 2-Micrometers Doppler Lidar for Wind Measurements  

Science.gov (United States)

High-energy 2-micrometer wavelength lasers have been incorporated in a prototype coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Calibration tests and sample atmospheric data are presented on wind and aerosol profiling.

Koch, Grady J.; Beyon, Jeffrey Y.; Barnes, Bruce W.; Petros, Mulugeta; Yu, Jirong; Amzajerdian, Farzin; Kavaya, Michael J.; Singh, Upendra N.

2006-01-01

360

Selection and Evaluation of Magnetic Flowmeter Liner Material for Nuclear Power Plants  

International Nuclear Information System (INIS)

Nuclear power plants are licensed to operate at power levels up to a specified thermal power rating. Safety analyses and evaluations are performed at conditions selected to account for uncertainties in determining thermal power. The NRC in Regulatory Guide 1.49, Rev. 1, December 1973 provides guidance regarding the amount of margin needed to account for uncertainties. Guidance provided in Regulatory Guide 1.49 recommends that analyses and evaluations be made by assuming the thermal power is equal to 1.02 times the licensed thermal power. The reason that analyses should be performed at two percent above the licensed thermal power is to allow for possible instrument errors. A 1% error in a primary loop flow can result in a 1% reduction in the unit net load if the error is in the high direction. In order to avoid errors in the low direction (and exceeding the licensed plant thermal power) a margin is built into the control system. Improved accuracy of the primary flow measurement allows for a reduction of this margin. EPRI has reported that the typical power plant primary flow measurement errors are 3?5%. Primary loop flow measurements are used to determine the core heat rate in PWRs and as such are a basic safety indication. These measurements are conventionally made using flowmeters based on the differential pressure. Differential pressure based on flowmeters have significant, fundamental accuracy limitations as well as having failure modes difficult to diagnose whilfailure modes difficult to diagnose while in service. Magnetic flowmeters offer a potential solution to these limitations. Magnetic flowmeters are highly accurate, respond linearly, and are obstructionless (no fouling; consume no pumping power). Also, the transmitter for magnetic flowmeters can be located remotely (up to hundreds of feet) from the point of the measurement, thus reducing the environmental exposure. The major limitation to the immediate application of magnetic flowmeters to nuclear power plants is the radiation sensitivity of the non-conductive inner pipe liner. Ceramic pipe liners are currently available for pipe diameters up to 30 cm. However, for larger pipes only radiation sensitive materials such as TeflonTM or rubber are available. Ceramic pipe liners are not currently available for larger diameter pipes due to manufacturing and material limitations

361

Rotational Doppler Effect  

OpenAIRE

A monochromatic linear source of light is rotated with certain angular frequency and when such light is analysed after reflection then a change of frequency or wavelength may be observed depending on the location of the observer. This change of frequency or wavelength is different from the classical Doppler effect [1] or relativistic Doppler effect [2]. The reason behind this shift in wavelength is that a certain time interval observed by an observer in the rotating frame is...

Halder, Amit

2002-01-01

362

Research & Medical Doppler platform  

OpenAIRE

A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables the diagnosis of intracranial vessels and the assessment of the blood flow. The device can display a color map of flow velocities in time-depth domain and a spectrogram of Doppler signal obtained at a selected depth. The system offers the multigate processing which allows to display simultaneously a number of spectrograms and to reconstruct a flow velocity profile. The digital signal processing i...

Lewandowski, Marcin; Walczak, Mateusz; Karwat, Piotr; Witek, Beata; Nowicki, Andrzej; Kar?owicz, Pawe?

2012-01-01

363

Comparison of Turbulence Models for Simulation of Flow around an Orifice Flowmeter  

International Nuclear Information System (INIS)

An orifice flowmeter is widely used to measure a flow rate in a pipe in various applications due to its simplicity. From the view point of a fluid flow, a flow around an orifice flowmeter is very complex and hard to measure its flow pattern. There is a velocity increase upstream of the plate. The flow is accelerated due to a contraction of the flow area around the plate and is decelerated after the orifice bore. Due to a sudden change of the flow area the flow shows complex flow patterns. It has been reported that two-equation turbulence models can not predict a flow with a sudden change of flow configurations. In this study various turbulence modes are tested and compared for the orifice flow field

364

Analysis of the feedback system in a nonintrusive dynamic flowmeter for measuring Pogo oscillations  

Science.gov (United States)

Equations were developed which describe the closed loop feedback system operation of a proposed ultrasonic, dynamic, nonintrusive flowmeter whose design is based on a constant phase, voltage controlled frequency feedback concept. These equations are based on linear feedback system theory. The time constant of a low pass filter is taken into account. The equations show that the larger the open loop gain, the smaller the error due to fluctuations in the speed of sound and the smaller the effective time constant.

Chapin, W. G.

1974-01-01

365

Numerical simulations of natural gas flow in pipe system with flowmeters  

Directory of Open Access Journals (Sweden)

Full Text Available Numerical simulation of the flow behavior in part of large pipe system is presented in this article. Compressed natural gas is transported through the system in a dynamic unsteady way. Velocities at several points and velocity profiles at certain positions are monitored during the numerical simulation. The aim is to investigate the stability of velocity profiles at the positions of flowmeters in course of flow time. In addition, the possibility of flow conditioning in the system is presented and discussed.

K?ourek Jind?ich

2014-03-01

366

Numerical simulations of natural gas flow in pipe system with flowmeters  

OpenAIRE

Numerical simulation of the flow behavior in part of large pipe system is presented in this article. Compressed natural gas is transported through the system in a dynamic unsteady way. Velocities at several points and velocity profiles at certain positions are monitored during the numerical simulation. The aim is to investigate the stability of velocity profiles at the positions of flowmeters in course of flow time. In addition, the possibility of flow conditioning in the system is presented ...

K?ourek Jind?ich; Matas Richard; Prokeš Ond?ej; Tenkrát Daniel

2014-01-01

367

Advances in Direct Detection Doppler Lidar Technology and Techniques  

Science.gov (United States)

In this paper we will describe the ground based Doppler lidar system which is mounted in a modified delivery van to allow field deployment and operations. The system includes an aerosol double edge receiver optimized for aerosol backscatter Doppler measurements at 1064 nm and a molecular double edge receiver which operates at 355 nm. The lidar system will be described including details of the injection seeded diode pumped laser transmitter and the piezoelectrically tunable high spectral resolution Fabry Perot etalon which is used to measure the Doppler shift. Examples of tropospheric wind profiles obtained with the system will also be presented to demonstrate its capabilities.

Gentry, Bruce; Einaudi, Franco (Technical Monitor)

2001-01-01

368

Doppler Lidar for Wind Measurements on Venus  

Science.gov (United States)

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

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

2010-01-01

369

Investigated conductive fracture in the granitic rocks by flow-meter logging  

International Nuclear Information System (INIS)

Test of the use of a measurement technique for the hydraulic conductivity of geological structures which act as flow paths or are impermeable to groundwater flow. In order to prove the value of flow-meter logging as an in-situ technique for detecting conductive fractures in granitic rocks, the method has been applied to a borehole near the Tono uranium mine, Gifu, Japan. This study in involved with detecting a conductive fracture and calculating the hydraulic conductivities. The results were as follows: (1) In a zone of groundwater inflow into the borehole, the hydraulic conductivity was calculated to be of the order of the 10-3 - 10-4 (cm/sec) from flow-meter logging. This value agreed with the results of a in-situ borehole permeability test carried out with a similar depth interval. (2) The study showed that flow-meter logging is effective for detecting the distribution of high conductivity fractures and calculating the hydraulic conductivity. (author)

370

An experimental study on installation effects of pipe elbow on the electromagnetic flowmeter characteristics (turbulent flow)  

International Nuclear Information System (INIS)

An ElectroMgnetic Flowmeter(EMF) essentially averages the velocity distribution over the pipe cross-sectional area, and the measured value is dependent on the velocity profiles. In this study, installation effects of 90 deg. long elbow(KS B 1522, ISO 3419) on the EMF characteristics was investigated. A commercial EMF was adopted and the distribution of magnetic field in the electrodes cross section was measured. In the experiment, the national flow standard system, of which measurement uncertainty was evaluated in a accordance with ISO 17025 recommendation, was used for characterization of EMF. The leading line has 150D long straight pipe to established a fully developed flow before entering into the elbow and the elbow was installed downstream of it, then the flowmeter was tested within 50 D from the elbow. The installation effects of the flowmeter were investigated by varying the mean velocity(Reynolds No.)in pipe section, the locations and the direction of electrodes plane.(?) From the experimental results, we find the optimal conditions to get most accurate measurements. Generally, the deviations from the calibration value were less than 0.5 % in farther than 10D distance from the elbow and the direction of electrodes plane, ? =90 deg. yielded the smallest measurement deviation. These characteristics were shown consistently in turbulent region regardless of the mean Reynolds number

371

On the concept of virtual current as a means to enhance verification of electromagnetic flowmeters  

International Nuclear Information System (INIS)

Electromagnetic flowmeters are becoming increasingly widely used in the water industry and other industries which handle electrically conducting liquids. When installed they are often difficult to remove for calibration without disturbing the liquid flow. Interest has therefore increased in the possibility of in situ calibration. The result has been the development of verification which attempts to approach calibration. However, while it checks on magnetic field and amplification circuits, it does not check adequately on the internals of the flowmeter pipe. This paper considers the use of the virtual voltage, a key element of the weight function theory of the flowmeter, to identify changes which have occurred in the flow tube and its liner. These could include a deformed insulating liner to the flow tube, or a deposit in the tube resulting from solids in the flow. The equation for virtual voltage is solved using a finite difference approach and the results are checked using a tank to simulate the flow tube, and tests on a flow rig. The concept is shown to be promising as a means of approaching verification of calibration

372

Magnetic field estimation in measurement dead domain for dry calibration of electromagnetic flowmeter  

International Nuclear Information System (INIS)

Advances in computing technology enable dry calibration of large-diameter electromagnetic (EM) flowmeters at low cost, which has been recognized as an effective alternative to traditional flow rigs. Dry calibration requiring no actual liquid in the measuring pipe utilizes the magnetic field distribution reconstructed from measured boundary conditions to determine the sensitivity of the EM flowmeter. However, because sensors have finite sizes, and the fact that inner linings of the measuring pipe deform due to mechanical stresses, a measurement dead domain (MDD) exists between the measured boundary surface and the pipe wall. As the MDD is often close to the magnetic exciting unit, neglecting it results in significant errors in dry calibration. This paper offers a practical method combining iterative optimization and reconstruction to estimate the magnetic field in the MDD from the field data on the measured boundary surface. The method has been validated on an off-the-shelf industrial EM flowmeter by comparing the estimated field in the MDD with experimental measurements. It has been demonstrated that accurately accounting for the immeasurable field in the MDD eliminates more than two-thirds of the dry calibration errors. The estimation method illustrated here can also be extended to measure other physical fields which obey similar governing equations. (paper)

373

The impact assessment of eccentric installation and roughness change in piping on the restriction type flowmeter  

International Nuclear Information System (INIS)

A lot of flow meters are set up in nuclear plants. One type of them is a restriction type flowmeter, and there is a plant design applying it to an ECCS system and feed water system. There are some requirements of the flowmeter installation in JIS and ASME standards. For instance, the requests are a limitation of the gap (eccentric) from the centerline under installation and the limitation and of roughness on the inside surface of the upstream piping. When these requirements are not satisfied, it is necessary to consider the error margin. However, the appropriate error margin that had to be considered when the requirement condition was not able to be satisfied was not clear. In this research, quantitative data of the relative error of the flowmeter were obtained by the experiments with the parameters of the inner surface roughness of the upstream piping and the amount of the eccentric installation of the flow hole. The maximum Reynolds number of the experimental facility is about 1.6x106. (author)

374

Analytical model of range-Doppler image of rough rotating cones  

Science.gov (United States)

The technique of laser range-Doppler image has get growing attentions from aerospace and national defense experts. Recently, in laser range-Doppler image system, laser scatter feature has been used for target ranging and orientation. Laser range-Doppler image can identify the moving components of the aeroplane, and detect the moving disk and sphere. Meanwhile, it is also widely used in detection of the moving gesture of the aerospace, discover of the target micro-motion and the measurement of the local fluid velocity. The laser range-Doppler image of target is the pulse laser scatter feature of the rotating target, which can reflect the shape, attitude and surface material of the target. For instance, detection of the flight gesture of target, identification of the warhead, the rotation of structures in a target, and the target torsional state. An analytical model of laser range-Doppler image of cones rotating around their axes is proposed in this paper. The analytical model can provide the effects of geometric parameters, the roughness of the surface, attitude and pulse duration on laser range-Doppler image. This analytical model can degenerate into the analytical model of Doppler spectra for plane waves. The influences of geometry parameters and attitude are analyzed numerically by using the analytical model. The results indicate that the laser range-Doppler image of cone can show the information about geometrical shape and attitude of target. Combining the theory and measurements, the analytical model can be used for identifying physical parameters and geometrical parameters of cone. This analytical solution may contribute to the laser Doppler velocimetry and ladar applications.

Luo, Long-gang; Wu, Zhen-sen; Liao, Run-gui

2013-09-01

375

Biosensors for Brain Trauma and Dual Laser Doppler Flowmetry: Enoxaparin Simultaneously Reduces Stroke-Induced Dopamine and Blood Flow while Enhancing Serotonin and Blood Flow in Motor Neurons of Brain, In Vivo  

Directory of Open Access Journals (Sweden)

Full Text Available Neuromolecular Imaging (NMI based on adsorptive electrochemistry, combined with Dual Laser Doppler Flowmetry (LDF is presented herein to investigate the brain neurochemistry affected by enoxaparin (Lovenox®, an antiplatelet/antithrombotic medication for stroke victims. NMI with miniature biosensors enables neurotransmitter and neuropeptide (NT imaging; each NT is imaged with a response time in milliseconds. A semiderivative electronic reduction circuit images several NT’s selectively and separately within a response time of minutes. Spatial resolution of NMI biosensors is in the range of nanomicrons and electrochemically-induced current ranges are in pico- and nano-amperes. Simultaneously with NMI, the LDF technology presented herein operates on line by illuminating the living brain, in this example, in dorso-striatal neuroanatomic substrates via a laser sensor with low power laser light containing optical fiber light guides. NMI biotechnology with BRODERICK PROBE® biosensors has a distinct advantage over conventional electrochemical methodologies both in novelty of biosensor formulations and on-line imaging capabilities in the biosensor field. NMI with unique biocompatible biosensors precisely images NT in the body, blood and brain of animals and humans using characteristic experimentally derived half-wave potentials driven by oxidative electron transfer. Enoxaparin is a first line clinical treatment prescribed to halt the progression of acute ischemic stroke (AIS. In the present studies, BRODERICK PROBE® laurate biosensors and LDF laser sensors are placed in dorsal striatum (DStr dopaminergic motor neurons in basal ganglia of brain in living animals; basal ganglia influence movement disorders such as those correlated with AIS. The purpose of these studies is to understand what is happening in brain neurochemistry and cerebral blood perfusion after causal AIS by middle cerebral artery occlusion in vivo as well as to understand consequent enoxaparin and reperfusion effects actually while enoxaparin is inhibiting blood clots to alleviate AIS symptomatology. This research is directly correlated with the medical and clinical needs of stroke victims. The data are clinically relevant, not only to movement dysfunction but also to the depressive mood that stroke patients often endure. These are the first studies to image brain neurotransmitters while any stroke medications, such as anti-platelet/ anti-thrombotic and/or anti-glycoprotein are working in organ systems to alleviate the debilitating consequences of brain trauma and stroke/brain attacks.

Edwin H. Kolodny

2010-12-01

376

Time-Variable Gravity from Satellite-Laser-Ranging and Doppler Measurements: An Update on the Low-degree components as well as the connections with Geophysical/Climatic Processes  

Science.gov (United States)

The oblateness of the Earth's gravity field, 52, has long been observed to undergo a slight decrease due to post-glacial rebound of the mantle. Sometime around 1998 this trend reversed quite suddenly. This reversal persisted until 2001, at which point the atmosphere-corrected time series appears to have reversed yet again. Presently, the time series appears to be returning to the value that would nominally have been reached had the anomaly not occurred. This anomaly signifies a large interannual change in global mass distribution whose J2 effect overshadows that of the post-glacial rebound over such timescales. A number of possible causes have been considered, with oceanic mass redistribution as the leading candidate although other effects, such as glacial melting and core effects may be contributing. The amount by which J2 returns to it's nominal value provides a valuable constraint on the separation of the causes, and will be considered. We will present our latest Satellite Laser Ranging and DORIS Doppler derived time series for J2, and various other low-degree harmonic terms, as well as our investigations into the causes. In addition, we will show the comparison of the J2 results with those derived from CHAMP, as computed at NASA GSFC, and the recently released GRACE gravity model.

Cox, Christopher M.; Chao, Benjamin F.; Au, Andrew Y.; Boy, J.-P.

2003-01-01

377

Sub-Doppler Spectroscopy by Use of Microwave Sidebands of CO2 Laser Lines Applied to the C-O Stretching Fundamental Band of Methanol  

Directory of Open Access Journals (Sweden)

Full Text Available Microwave sidebands of CO2 laser lines were used as an infrared source in infrared microwave double resonance spectroscopy and infrared saturation spectroscopy to study the C -O stretching fundamental band of methanol. In the former application, rotational lines in the vCO = 1 state have been observed with good signal to noise ratios and physical processes involved in this method have been discussed. In the latter method, (vt, A/E, K = (2, A, 4 sequence transitions in the C-O stretching fundamental band have been identified and term values for the (2, A, 4 levels in the vCO = 1 state have been determined.

Kojiro Takagi

2003-01-01

378

Rotational Doppler Effect  

CERN Document Server

A monochromatic linear source of light is rotated with certain angular frequency and when such light is analysed after reflection then a change of frequency or wavelength may be observed depending on the location of the observer. This change of frequency or wavelength is different from the classical Doppler effect [1] or relativistic Doppler effect [2]. The reason behind this shift in wavelength is that a certain time interval observed by an observer in the rotating frame is different from that of a stationary observer.

Halder, A

2002-01-01

379

Preliminary Study for a Numerical Investigation on the Effect of an Upstream Elbow on an Orifice Flowmeter Performance  

International Nuclear Information System (INIS)

In a previous work, we tested various turbulence models for simulating the flow through an orifice flowmeter under an assumption that the flow field is axisymmetric. We concluded that Wilcox's k-? model shows the best performance for this flow field among the chosen two-equation turbulence models, but it still requires a modification for an accurate prediction. Another question however has arisen after the numerical simulation of the orifice flow. There are recommendations for an installation of orifice flowmeters to measure the flowrates accurately. In many field installations, these requirements are difficult to be met. To reduce the installation effects, many flow conditioners, which shorten their length to achieve fully developed flow conditions, have been developed. To overcome these effects, it is possible to modify the discharge coefficient of orifice flowmeters by a suitable correction that is deduced by an understanding of the flow fields. In this paper, we attempt to numerically simulate installation effects by adding an elbow upstream of an orifice flowmeter. We hope that several simulations help us estimate the effects of the distance between the elbow and the orifice flowmeter on the orifice performance

380

Efficacy of the ejector flow-meter. A scavenging device for anaesthetic gases.  

Science.gov (United States)

Measurements of air concentrations of nitrous oxide and halothane in the breathing zone of the anaesthetist and the operating-room nurse were carried out during inhalation anaesthesia with a Mapleson D system. Gas removal was performed from inside the breathing system at the same rate as that of the fresh gas inflow by means of an ejector flow-meter. The concentrations of nitrous oxide and halothane were maintained below the Danish Threshold Limit Values of 100 and 5 parts per million, respectively, by using this type of scavenging. When these anaesthetics were used simultaneously, the reduced Threshold Limit Values were not exceeded during endotracheal anaesthesia. PMID:3156464

Obel, D; Jørgensen, S; Ferguson, A; Frandsen, K

1985-01-01

381

Doppler Optical Coherence Tomography  

OpenAIRE

Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained impo...

Leitgeb, Rainer A.; Werkmeister, Rene? M.; Blatter, Cedric; Schmetterer, Leopold

2014-01-01

382

Doppler-musical instrument  

Energy Technology Data Exchange (ETDEWEB)

We propose a possible ultra-high energy resolution backscattering spectrometer optimized to spallation neutron source. A combination of multi monochromator crystal and Doppler drive provides considerable neutron flux, together with the reasonable energy range -30 < E < 30 {mu}eV, even when the ultra-high energy resolution of {delta}E{approx}0.03 {mu}eV is attained. (author)

Sato, T.J. [National Research Institute for Metals, Tsukuba, Ibaraki (Japan); Watanabe, N. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Shibata, K. [Institute for Materials Research, Tohoku Univ., Sendai, Miyagi (Japan)

2001-03-01

383

Doppler Radar Technology  

Science.gov (United States)

This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

384

Wind Measurements with High Energy 2 Micron Coherent Doppler Lidar  

Science.gov (United States)

A coherent Doppler lidar based on an injection seeded Ho:Tm:YLF pulsed laser was developed for wind measurements. A transmitted pulse energy over 75 mJ at 5 Hz repetition rate has been demonstrated. Designs are presented on the laser, injection seeding, receiver, and signal processing subsystems. Sample data of atmospheric measurements are presented including a wind profile extending from the atmospheric boundary layer (ABL) to the free troposphere.

Barnes, Bruce W.; Koch, Grady J.; Petros, Mulugeta; Beyon, Jeffrey Y.; Amzajerdian, Farzin; Yu, Ji-Rong; Kavaya, Michael J.; Singh, Upendra N.

2004-01-01

385

Amplified Doppler shift observed in diffraction images as function of the COBE "ether drift" direction  

OpenAIRE

We report results on an ``one-way light path'' laser diffraction experiment as a function of the laser beam alignment relative to the Earth's velocity vector obtained by COBE measurements of the Doppler shift in the cosmic microwave background radiation (CMBR). An amplified Doppler shift is observed in the diffraction images, and the effect is compatible with a ``dipole'' speed of light anisotropy due to Earth's motion relative to the ``CMBR rest frame'', with an amplitude o...

Navia, C. E.; Augusto, C. R. A.

2006-01-01

386

The combined use of heat-pulse flowmeter logging and packer testing for transmissive fracture recognition  

Science.gov (United States)

This paper presents an improved borehole prospecting methodology based on a combination of techniques in the hydrogeological characterization of fractured rock aquifers. The approach is demonstrated by on-site tests carried out in the Hoshe Experimental Forest site and the Tailuge National Park, Taiwan. Borehole televiewer logs are used to obtain fracture location and distribution along boreholes. The heat-pulse flow meter log is used to measure vertical velocity flow profiles which can be analyzed to estimate fracture transmissivity and to indicate hydraulic connectivity between fractures. Double-packer hydraulic tests are performed to determine the rock mass transmissivity. The computer program FLASH is used to analyze the data from the flowmeter logs. The FLASH program is confirmed as a useful tool which quantitatively predicts the fracture transmissivity in comparison to the hydraulic properties obtained from packer tests. The location of conductive fractures and their transmissivity is identified, after which the preferential flow paths through the fracture network are precisely delineated from a cross-borehole test. The results provide robust confirmation of the use of combined flowmeter and packer methods in the characterization of fractured-rock aquifers, particularly in reference to the investigation of groundwater resource and contaminant transport dynamics.

Lo, Hung-Chieh; Chen, Po-Jui; Chou, Po-Yi; Hsu, Shih-Meng

2014-06-01

387

Dry calibration of electromagnetic flowmeters based on numerical models combining multiple physical phenomena (multiphysics)  

International Nuclear Information System (INIS)

This paper presents a method for dry calibration of an electromagnetic flowmeter (EMF). This method, which determines the voltage induced in the EMF as conductive liquid flows through a magnetic field, numerically solves a coupled set of multiphysical equations with measured boundary conditions for the magnetic, electric, and flow fields in the measuring pipe of the flowmeter. Specifically, this paper details the formulation of dry calibration and an efficient algorithm (that adaptively minimizes the number of measurements and requires only the normal component of the magnetic flux density as boundary conditions on the pipe surface to reconstruct the magnetic field involved) for computing the sensitivity of EMF. Along with an in-depth discussion on factors that could significantly affect the final precision of a dry calibrated EMF, the effects of flow disturbance on measuring errors have been experimentally studied by installing a baffle at the inflow port of the EMF. Results of the dry calibration on an actual EMF were compared against flow-rig calibration; excellent agreements (within 0.3%) between dry calibration and flow-rig tests verify the multiphysical computation of the fields and the robustness of the method. As requiring no actual flow, the dry calibration is particularly useful for calibrating large-diameter EMFs where conventional flow-rig methods are often costly and difficult to implement.

388

Experimental evaluation of permanent magnet probe flowmeter measuring high temperature liquid sodium flow in the ITSL  

International Nuclear Information System (INIS)

Highlights: • An Instrument Test Sodium Loop (ITSL) has been built and tested in various conditions at KAERI. • Free fall of liquid sodium was conducted experimentally and numerically. • A Permanent Magnet Probe Flowmeter (PMPF) was experimented in the ITSL. • Excellent linearity of the PMPF was achieved under high temperature condition. - Abstract: The Instrument Test Sodium Loop (ITSL) installed at Korea Atomic Energy Research Institute (KAERI) is a medium-size experimental facility dedicated to obtaining relevant experimental data of liquid sodium flow characteristics under various thermal hydraulic conditions and sodium purification. The ITSL has been utilized to perform thermal flow measurement of the liquid sodium and to calibrate a Permanent Magnet Probe Flowmeter (PMPF). The primary objective of this study is to obtain liquid sodium flow rate given a wide temperature range using the PMPF. Non-stationary method was adopted for the calibration of the probe given the liquid sodium temperature range of 150–415 °C. A relationship between the measured voltage signal and flow rate was obtained successfully. It is observed that the calibration experiments result in excellent linear relationships between measured voltage and volumetric flow rate at various temperature conditions. Also a computational analysis using FlowMaster, is employed to facilitate the calibration process by predicting the liquid sodium flow rate. Finally the effect of the fluid temperature on thermal flow measurements is discussed in light of the obtained experimental data

389

Application of a vortex shedding flowmeter to the wide range measurement of high temperature gas flow  

International Nuclear Information System (INIS)

A single flowmeter was required for helium gas measurement in a Gas Cooled Fast Breeder Reactor loss of coolant simulator. Volumetric flow accuracy of +-1.0% of reading was required over the Reynolds Number range 6 x 103 to 1 x 106 at flowing pressures from 0.2 to 9 MPa (29 to 1305 psia) at 3500C (6600F) flowing temperature. Because of its inherent accuracy and rangeability, a vortex shedding flowmeter was selected and specially modified to provide for a remoted thermal sensor. Experiments were conducted to determine the relationship between signal attenuation and sensor remoting geometry, as well as the relationship between gas flow parameters and remoted thermal sensor signal for both compressed air and helium gas. Based upon the results of these experiments, the sensor remoting geometry was optimized for this application. The resultant volumetric flow rangeability was 155:1. The associated temperature increase at the sensor position was 90C above ambient (250F) at a flowing temperature of 3500C. The volumetric flow accuracy was measured over the entire 155:1 flow range at parametric values of flowing density. A volumetric flow accuracy of +- % of reading was demonstrated

390

Two-phase measurement with electromagnetic flowmeters in the liquid metal two-phase flow and water-air two-phase flow  

International Nuclear Information System (INIS)

In order to investigate the characteristics of an electromagnetic flowmeter in the liquid metal two-phase flow, AC electromagnetic flowmeters were designed and manufactured. Two-phase flow experiments, encompassing bubbly to slug flow regimes, were conducted with the water-air mixture and the liquid sodium-nitrogen mixture, respectively. The simple relation ?UTP=?USP/(1-? ), relating flowmeter signal between single-phase flow and two-phase flow, was verified with measurements of the potential difference and the void fraction(? ) for a bubbly flow regime. Whereas there is no difference in the shape of the raw signal between single-phase flow and bubbly flow, the signal amplitude of bubbly flow is greater than that of single-phase flow under the same water flow and liquid sodium flow rates, since the passage area of the liquid flow is reduced. In the case of slug flow, the phase and the amplitude of the flowmeter output show a dramatic change in the flow characteristics around each slug bubble and the position of a slug bubble itself. Therefore, the electromagnetic flowmeter shows a good potential as a useful device for identifying the flow regimes. The void fraction can be simply measured with two electromagnetic flowmeters for a low-void fraction flow such as bubbly flow with some error margins. Thus, the flowmeters can be used to measure the void fraction for a liquid sodium within some tolerable error margins

391

Korea-China Joint R and D on Doppler Lidar Technology  

International Nuclear Information System (INIS)

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

392

Clinical applications of doppler ultrasound  

Energy Technology Data Exchange (ETDEWEB)

This book introduces a guide to the physical principles and instrumentation of duplex Doppler ultrasound and its applications in obstetrics, gynecology, neonatology, gastroentology, and evaluation of peripheral vascular disease. The book provides information needed to perform Doppler ultrasound examinations and interpret the results. An introduction to Doppler physics and instrumentation is followed by a thorough review of hemodynamics, which explains the principles underlying interpretation of Doppler signals. Of special note is the state-of-the-art coverage of new applications of Doppler in recognition of high-risk pregnancy, diagnosis of intrauterine growth retardation, investigation of neonatal blood flow, evaluation of first-trimester pregnancy, and diagnosis of gastrointestinal disease. The book also offers guidelines on the use of Doppler ultrasound in diagnosing carotid disease, deep venous thrombosis, and aorta/femoral disease.

Taylor, K.J.W.; Burns, P.N.; Well, P.N.T.

1987-01-01

393

Comparisons between PW Doppler system and enhanced FM Doppler system  

DEFF Research Database (Denmark)

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. This approach requires a priori knowledge of the envelope of the received sweep from a point scatterer

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

1995-01-01

394

Airborne Doppler-lidar and ground-based Doppler radar observations of a thunderstorm in Oklahoma  

Science.gov (United States)

The results of airborne Doppler-lidar and ground-based Doppler radar observations of multicellular storms, marked by heavy rainfall, strong surface outflow, and a gust-front tornado, on June 30, 1981 are analyzed. The airborne lidar comprised a CO2-laser operating in the IR region, which was discharged once each second at 20 deg fore and aft, alternatively, of the normal to the aircraft's heading, and a quarter-wave plate for registering the returning frequency-shifted beams. Wind fields are plotted taking into account the advection effects. The lidar data set is noted for its self-consistency, though limited to a range of 5 km by the high moisture levels. Fair agreement was found between the lidar-derived and radar-derived average ground-based radial wind fields, with discrepancies on the order of 1.5 m/s.

Bluestein, H. B.; Mccaul, E. W., Jr.; Fitzjarrald, D. E.

1983-01-01

395

Principles of doppler tomography  

International Nuclear Information System (INIS)

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

396

Extending the turbidity record: making additional use of continuous data from turbidity, acoustic-Doppler, and laser diffraction instruments and suspended-sediment samples in the Colorado River in Grand Canyon  

Science.gov (United States)

Turbidity is a measure of the scattering and absorption of light in water, which in rivers is primarily caused by particles, usually sediment, suspended in the water. Turbidity varies significantly with differences in the design of the instrument measuring turbidity, a point that is illustrated in this study by side-by-side comparisons of two different models of instruments. Turbidity also varies with changes in the physical parameters of the particles in the water, such as concentration, grain size, grain shape, and color. A turbidity instrument that is commonly used for continuous monitoring of rivers has a light source in the near-infrared range (860±30 nanometers) and a detector oriented 90 degrees from the incident light path. This type of optical turbidity instrument has a limited measurement range (depending on pathlength) that is unable to capture the high turbidity levels of rivers that carry high suspended-sediment loads. The Colorado River in Grand Canyon is one such river, in which approximately 60 percent of the range in suspended-sediment concentration during the study period had unmeasurable turbidity using this type of optical instrument. Although some optical turbidimeters using backscatter or other techniques can measure higher concentrations of suspended sediment than the models used in this study, the maximum turbidity measurable using these other turbidimeters may still be exceeded in conditions of especially high concentrations of suspended silt and clay. In Grand Canyon, the existing optical turbidity instruments remain in use in part to provide consistency over time as new techniques are investigated. As a result, during these periods of high suspended-sediment concentration, turbidity values that could not be measured with the optical turbidity instruments were instead estimated from concurrent acoustic attenuation data collected using side-looking acoustic-Doppler profiler (ADP) instruments. Extending the turbidity record to the full range of sediment concentrations in the study area using data from the ADP instruments is particularly useful for biological studies. In Grand Canyon, turbidity has been correlated with food availability for aquatic organisms (gross primary production) as well as with fish behavior specific to predator-prey interactions. On the basis of the complete “extended” turbidity record and the relation between suspended-sediment concentration and turbidity, levels were higher before the construction of Glen Canyon Dam by a factor of approximately 2,000 at the Lees Ferry monitoring station (15 miles downstream from the dam) and by a factor of approximately 20 at the monitoring station 87 miles downstream from Lees Ferry (102 miles downstream from the dam). A comparison of turbidity data with data from Laser In-Situ Scattering and Transmissometry (LISST) laser-diffraction instruments, suspended-sediment concentration data, and ADP data shows the influence of the physical properties of suspended sediment. Apparent outliers in relations between turbidity, ADP, and suspended-sediment data during two events within the study period, a 2007 tributary flood from a watershed altered by a recent wildfire and a 2008 experimental controlled-flood release from Glen Canyon Dam, are explained in part by atypical grain sizes, shapes, densities, colors, and (or) clay mineral assemblages of suspended sediment occurring in the Colorado River during these two events. These analyses demonstrate the value of using multiple data-collection strategies for turbidity and sediment-transport studies and of continuous monitoring for capturing the full range and duration of turbidity and sediment-transport conditions, identifying the provenance of the sediment causing turbidity, and detecting physical and chemical processes that may be important for management of critical physical and biological resources.

Voichick, Nicholas; Topping, David J.

2014-01-01

397

Laser doppler flowmetry in the fetal scalp.  

OpenAIRE

During labour, the fetus runs an increased risk of developing hypoxaemia, because uterine contractions reduce utero-placental blood flow, thereby decreasing the blood gas transfer between the maternal and fetal circulation. At present, the only reasonable way of obtaining information on fetal arterial blood pH and gas values is via the microvasculature of the presenting part, usually the fetal scalp. As long as scalp blood flow remains undisturbed, the peripheral pH and blood gas values will ...

Smits, Taco Minne

1989-01-01

398

Doppler Beats or Interference Fringes?  

Science.gov (United States)

Discusses the following: another version of Doppler beats; alternate proof of spin-1 sin-1/2 problems; some mechanisms related to Dirac's strings; Doppler redshift in oblique approach of source and observer; undergraduate experiment on noise thermometry; use of the time evolution operator; resolution of an entropy maximization controversy;…

Kelly, Paul S.

1979-01-01

399

Measurement of flow coefficient of orifice flowmeter for large diameter pipe  

International Nuclear Information System (INIS)

A facility to calibrate a large scale liquid flow meter with a high accuracy was constructed about four years ago. It has been used to test corner tap type orifice flowmeter which was attached to four big lines. The maximum flowrate of the facility is 3,000m/sup 3//h which corresponds to 3x10/sup 6/ Reynolds number and the biggest diameter of these lines is 1,100mm. The diameter ratio covered the range from 0.3 to 0.8. This paper describes the ultimate accuracy of the facility component and some experimental results by comparing ISO standard. The repeatability of flowrate is very good. The maximum difference from the mean value of six measurements is within +- 0.1%. The flow coefficients which is measured by gravimetric and volumetric methods are confirmed to coincide within +- 0.1%. Some amount of discrepancy is observed between ISO standard and measured values

400

Continuous flow phantom for the calibration of an ultrasonic transit-time flowmeter  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english INTRODUCTION: Ultrasound Transit-Time flowmeters are based on the fact that the time required for an ultrasound pulse to propagate through a given distance in a moving medium is a function of the vectorial sum of pulse propagation velocity and medium velocity. The most common application of this flo [...] wmeter in medicine is in the evaluation of blood flow in arteries and veins during heart vascular surgery. The present article describes the design, construction and evaluation of a flow phantom for transit-time flowmeters calibration. METHODS: Basically, it is a hydraulic circuit containing degassed and distilled water. In such a circuit, a constant differential water level is established between two columns that are interconnected by tubes with defined resistance, which determines a known flow rate. A basic theoretical model to estimate the system Reynolds Number and resistance was developed. RESULTS: A flow range between 4.43 ?± 0.18 ml.min-1 and 106.88 ?± 0.27 ml.min-1 was found to be compatible with physiological values in small vessels. The pressure range was between 0.20 ?± 0.03 cmH2O and 12.53 ?± 0.07 cmH2O, and the larger Reynolds Number was 1134.07. Experimental and theoretical resistance values were similar. CONCLUSION: A reproducible phantom was designed and built to be assembled with standard low-cost materials and is capable of generating adjustable and continuous flows that can be used to calibrate TTFM systems.

Fellipe Allevato Martins da, Silva; Marco Antônio, von Krüger; Wagner Coelho de Albuquerque, Pereira.

2014-03-01

401

The ejector flowmeter as air/oxygen mixing device. An apparatus providing gas mixtures with adjustable oxygen content for high-flow humidification systems.  

Science.gov (United States)

The ejector flowmeter is constructed for continuous removal of excess gas from anaesthetic circuits. This instrument can be used as an air/oxygen mixing device for high-flow humidification systems in wards where compressed air is not available. Pure oxygen is used as driving gas through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of air to the flowmeter, FIO2 and total outflow. PMID:6446224

Christensen, K N; Waaben, J; Jørgensen, S

1980-04-01

402

Characterization of vortices using pulsed-wave Doppler ultrasound.  

Science.gov (United States)

The detection and characterization of vortices from a Kaman vortex generator by means of a 20 MHz pulsed-wave Doppler ultrasound system were assessed. Measurements were made at different steady flowrates in a 10 mm internal diameter polyurethane tube, 14 mm distal to a circular cylinder of diameter 2 mm, placed across the tube inlet. The results were compared with those obtained with a two-component laser Doppler anemometer system. There was generally good agreement between the two techniques in the measurement of convective flow velocity, frequency of vortex shedding and the circulation velocity of the vortices. It is concluded that pulsed-wave Doppler ultrasound is a suitable technique for investigating vortical flow structures. PMID:11201415

Gaupp, S; Wang, Y; How, T V; Fish, P J

2000-01-01

403

Laser spectroscopy  

CERN Document Server

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers) and parametric oscillators, coherent matter waves, Doppler-free Fourier spectroscopy with optical frequency combs, interference spectroscopy, quantum optics, the interferometric detection of gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.

Demtröder, Wolfgang

404

Estudo Doppler na hipertensão portal / Doppler evaluation in portal hypertension  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A ultra-sonografia e o Doppler representaram grande marco no diagnóstico da hipertensão portal. Este fato decorre do aspecto não-invasivo destes métodos, possibilitando o estudo do fígado, do baço e da circulação esplâncnica. Neste artigo os autores discutem alguns aspectos importantes avaliados pel [...] a ultra-sonografia e pelo Doppler na avaliação da hipertensão portal. Abstract in english Ultrasonography and Doppler ultrasonography have dramatically improved the diagnosis of portal hypertension thanks to the noninvasive visualization of the liver, spleen and splanchnic blood flow. In this article the authors discuss some important issues raised by the use of ultrasound and Doppler in [...] the evaluation of portal hypertension.

Márcio Martins, Machado; Ana Cláudia Ferreira, Rosa; Nestor de, Barros; Letícia Martins, Azeredo; Junia Beatriz Ferreira, Rosa; Luciana Mendes de Oliveira, Cerri; Maria Cristina, Chammas; Murilo Tavares, Daher; Renato Tavares, Daher; William Abrão, Saad; Giovanni Guido, Cerri.

2004-02-01

405

Current status on high-accuracy ultrasonic flowmeter development for feedwater flow rate measurements in light water reactors  

International Nuclear Information System (INIS)

The licensing processes on uprating of current light water reactors (LWRs) are classified into three categories by US NRC, one of which is the uprating by MU, Measurement Uncertainty Recapture, targeting the uprating up to 2%. MU is enabled by the measurement-accuracy improvement of a feedwater flowmeter with 0.5-1.7% without issues arising from safety matters and remodeling equipment. Time-of-flight type ultrasonic flowmeters have been widely used in industries. However, it has to be considered the traceability for the national standard to assure high accuracy of flowmeters. It can be found the differences of the flow condition and configuration between the flow standard and measurement position on-site, where the 'Profile Factor' obtained from factory calibration tests at an ideal condition is not sufficient for correcting the meter reading. Flow profile factors (PFs), which adjust measurand to real flow rates, also strongly depend on flow profiles. Furthermore, as nuclear power plants are aging, readings of flowmeters for reactor feedwater systems drift due to the changes of flow profiles. We have conducted experiments to quantify the effects of flow patterns on the PFs due to pipe roughness and asymmetric flow, and the results of our experiments have shown the effects of elbows and pipe inner roughness, which strongly affect to the creation of the flow patterns. Those changes of flow patterns lead to large errors in measurements with transit time (time-of-flight: ements with transit time (time-of-flight: TOF) ultrasonic flow meters. In those experiments, changes of pipe roughness result in the changes of PFs with certain errors. Therefore, we must take into account those effects in order to measure the flow rates of feedwater with high accuracy in actual power plants. (author)

406

Doppler characteristics of sea clutter.  

Energy Technology Data Exchange (ETDEWEB)

Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

Raynal, Ann Marie; Doerry, Armin Walter

2010-06-01

407

Multipoint photonic doppler velocimetry using optical lens elements  

Science.gov (United States)

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.

Frogget, Brent Copely; Romero, Vincent Todd

2014-04-29

408

Continuous wave ultrasonic Doppler tomography  

OpenAIRE

In continuous wave ultrasonic Doppler tomography (DT), the ultrasonic beam moves relative to the scanned object to acquire Doppler-shifted frequency spectra which correspond to cross-range projections of the scattering and reflecting structures within the object. The relative motion can be circular or linear. These data are then backprojected to reconstruct the two-dimensional image of the object cross section. By using coherent processing, the spatial resolution of ultrasonic DT is close to ...

Liang, Haidong-dong; Tsui, Chun Sing Louis; Halliwell, Michael; Wells, Peter N. T.

2011-01-01

409

Adaptive Spectral Doppler Estimation  

DEFF Research Database (Denmark)

In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each veloc- ity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pul- sating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior per- formance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

Gran, Fredrik; Jakobsson, Andreas

2009-01-01

410

Airborne Doppler lidar activities  

Science.gov (United States)

During August and September 1984, 20 research flights were conducted by the CV990 with airborne doppler lidar installed. Nine of these flights were dedicated to the Lidar project. Excellent data were obtained in the Carquenez Strait downwind of San Francisco Bay, showing the divergence of the flow as it passes into the Central Valley. The data clearly show the horizontal and vertical structure of the wind flow in the pass region and adjoining parts of the Central Valley. Data were also obtained in the vicinity of Mount Shasta in northern California, showing the flow in the lee of the isolated mountain. Preliminary analyses of these flights using the McIdas interactive graphics system have been accomplished, and procurements have been initiated for detailed scientific analyses. A partial failure of a crucial optical component resulted in contamination of a portion of the wind data that were obtained in the Mount Shasta and subsequent flights. Analyses are underway to attempt reconstruction of the data to minimize the effects of the failure. Data were obtained in conjunction with a microwave wind profiler at Penn State University. It is expected that data reconstruction will be of use in this case. Procurement has been initiated for scientific analyses of these results. The improved airborne Lidar system performed well. In most of the research flights a large number of different scan angles were used to obtain the vertical structure of the wind fields being investigated.

Fitzjarrald, D. R.; Bilbro, J. W.

1985-01-01

411

Comparison of Triature Doppler Velocimetry and VISAR  

International Nuclear Information System (INIS)

Triature Photonic Doppler Velocimetry (TDV) is an adaptation of Photonic Doppler Velocimetry (PDV) that rejects common-mode data noise after splitting PDV three ways, with each signal 120o out of phase from each other. Testing has demonstrated that TDV also improves temporal resolution from the typical five nanoseconds of PDV to a subnanosecond range. This paper compares the temporal response of TDV with that of PDV and VISAR (velocity interferometer system for any reflector) in an experiment with a subnanosecond (?120-picosecond rise time) shock source. Laboratory tests were performed using a high-power laser on targets of copper and aluminum. A Buce Marshall fast VISAR with a single-point PDV and a prototype TDV were used. A special probe that combined PDV, TDV, and fast VISAR made simultaneous velocity measurements. Breakout velocities of 1.3 km/second on copper and 2.5 km/second on aluminum were observed, where TDV resolved rise times of ?200 ps. This resolution was better than that of a fast VISAR, which can achieve ?500 ps temporal resolution. Test methods and results are presented.

412

Comparison of Triature Doppler Velocimetry and Visar  

International Nuclear Information System (INIS)

Triature Photon Doppler Velocimetry (TDV) is an adaptation of Photonic Doppler Velocimetry (PDV) that rejects common-mode data noise after splitting PDV three ways, with each signal 1200 out of phase from each other. Testing has demonstrated that the TDV also improves temporal resolution from the typical five-nanoseconds of PDV to a subnanosecond range. This paper compares the temporal response of TDV with that of PDV and VISAR [velocity interferometer system for any reflector] in an experiment with a subnanosecond (?120-picosecond rise time) shock source. Laboratory tests were performed using a high-power laser on targets of copper and aluminum. A fast VISAR with a single-point PDV and a prototype TDV were used. A special probe that combined PDV, TDV, and fast VISAR made simultaneous velocity measurements. Breakout velocities of 1.3 km/second on copper and 2.5 km/second on aluminum were observed, where TDV resolved rise times of ?200 ps. This resolution was better than that of a fast VISAR, which can achieve ?500 ps temporal resolution. Test methods and results are presented.

413

Improved plant economics through accurate feedwater flow measurement with the crossflow ultrasonic flowmeter  

International Nuclear Information System (INIS)

The crossflow ultrasonic flowmeter (UFM) improves nuclear power plant performance through more accurate and reliable feedwater flow measurement. Reactor power levels are typically monitored via secondary-side calorimetric calculations that depend on the accurate measurement of feedwater flow . The feedwater flow is measured with calibrated venturis in most plants. These are subject to chemical fouling and other mechanical problems. If the loss in accuracy of the feedwater flow measurement overstates the actual flow rate, the result is a direct loss in megawatts generated by the plant. This paper describes a new, innovative ultrasonic technique to improve the accuracy, stability and repeatability of ultrasonic flow measurements. By employing this advanced technology to provide a continuous correction to the venturi-measured feed water flow rate, plants have reported the recovery of between 5 and 25 MWe. This technology has been implemented in a new flowmeter called CROSSFLOW. The CROSSFLOW meter utilizes a mathematical process called cross-correlation to process the ultrasonic signal, which is modulated by the flow eddys to determine the velocity of the feedwater. It replaces the older, less accurate transit-time methodology. Comparisons with weigh tank test, calibrated plant instrumentation, and chemical tracer tests have demonstrated a repeatable accuracy of 0.21% or better with this advanced cross-correlation technology. The paper discusses the history of the cross- paper discusses the history of the cross-correlation technique and its theoretical basis, illustrates how this technique addresses the measurement sensitivities for various parameters, demonstrates the calculation of the accuracy of the meter, and discusses the recently completed NRC review of the CROSSFLOW System and methodology. The paper also discusses recent precision flow measurement applications being performed with CROSSFLOW at nuclear plants worldwide. Among these applications are the measurement of Reactor Coolant System flow and the utilization of CROSSFLOW to take advantage of new NRC rule-making to reduce their assumed Power Measurement Uncertainty in Appendix K to gain a further 1% or more boost in power output. (author)

414

LISA data analysis; 1, Doppler demodulation  

CERN Document Server

The orbital motion of the Laser Interferometer Space Antenna (LISA) produces amplitude, phase and frequency modulation of a gravitational wave signal. The modulations have the effect of spreading a monochromatic gravitational wave signal across a range of frequencies. The modulations encode useful information about the source location and orientation, but they also have the deleterious affect of spreading a signal across a wide bandwidth, thereby reducing the strength of the signal relative to the instrument noise. We describe a simple method for removing the dominant, Doppler, component of the signal modulation. The demodulation reassembles the power from a monochromatic source into a narrow spike, and provides a quick way to determine the sky locations and frequencies of the brightest gravitational wave sources.

Cornish, N; Cornish, Neil; Larson, Shane

2003-01-01

415

Planar Particle Imaging Doppler Velocimetry Developed  

Science.gov (United States)

Two current techniques exist for the measurement of planar, three-component velocity fields. Both techniques require multiple views of the illumination plane in order to extract all three velocity components. Particle image velocimetry (PIV) is a high-resolution, high accuracy, planar velocimetry technique that provides valuable instantaneous velocity information in aeropropulsion test facilities. PIV can provide three-component flow-field measurements using a two-camera, stereo viewing configuration. Doppler global velocimetry (DGV) is another planar velocimetry technique that can provide three component flow-field measurements; however, it requires three detector systems that must be located at oblique angles from the measurement plane. The three-dimensional configurations of either technique require multiple (DGV) or at least large (stereo PIV) optical access ports in the facility in which the measurements are being conducted. Optical access is extremely limited in aeropropulsion test facilities. In many cases, only one optical access port is available. A hybrid measurement technique has been developed at the NASA Glenn Research Center, planar particle image and Doppler velocimetry (PPIDV), which combines elements from both the PIV and DGV techniques into a single detection system that can measure all three components of velocity across a planar region of a flow field through a single optical access port. In the standard PIV technique, a pulsed laser is used to illuminate the flow field at two closely spaced instances in time, which are recorded on a "frame-straddling" camera, yielding a pair of single-exposure image frames. The PIV camera is oriented perpendicular to the light sheet, and the processed PIV data yield the two-component velocity field in the plane of the light sheet. In the standard DGV technique, an injection-seeded Nd:YAG pulsed laser light sheet illuminates the seeded flow field, and three receiver systems are used to measure three components of velocity. The receiver systems are oriented at oblique angles to the light sheet in order to accurately resolve the three-component velocity. Each DGV receiver system contains two cameras, which share a common view of the illuminated flow through a beam-splitting cube. One camera views the illuminated flow directly (reference camera) and the second camera images the illuminated flow through an iodine vapor cell (signal camera). The laser frequency (wavelength) is adjusted so that the Doppler-shifted light from particles in the flow falls on an iodine absorption feature, see the following graph. The iodine vapor cell acts as a frequency-to-velocity filter by modulating the intensity of the transmitted light as a function of the flow velocity (Doppler shift). The ratio of the signal and reference images yields the component of the flow velocity along the bisector of the laser sheet propagation direction and the receiver system observation direction. The hybrid system employs a single-component DGV receiver system configured to simultaneously acquire PIV image data, as shown in the following diagram. The cameras used in the DGV receiver are replaced with PIV frame-straddling cameras, and the receiver system views the illuminated light sheet plane at 90 (as in the standard PIV configuration).

Wernet, Mark P.

2000-01-01

416

A Fiber Optic Doppler Sensor and Its Application in Debonding Detection for Composite Structures  

OpenAIRE

Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by using fiber optic Doppler (FOD) sensor with spiral shape. Interferometers based on two types of laser sources, namely the He-Ne laser and the infrared semiconductor laser, are proposed and compared in this study...

Fucai Li; Hideaki Murayama; Kazuro Kageyama; Guang Meng; Isamu Ohsawa; Takehiro Shirai

2010-01-01

417

Development of Coriolis mass flowmeter with digital drive and signal processing technology.  

Science.gov (United States)

Coriolis mass flowmeter (CMF) often suffers from two-phase flowrate which may cause flowtube stalling. To solve this problem, a digital drive method and a digital signal processing method of CMF is studied and implemented in this paper. A positive-negative step signal is used to initiate the flowtube oscillation without knowing the natural frequency of the flowtube. A digital zero-crossing detection method based on Lagrange interpolation is adopted to calculate the frequency and phase difference of the sensor output signals in order to synthesize the digital drive signal. The digital drive approach is implemented by a multiplying digital to analog conve